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Title:
ADAPTING MEASUREMENT FOR NARROW BAND INTERNET OF THINGS
Document Type and Number:
WIPO Patent Application WO/2017/138869
Kind Code:
A1
Abstract:
A method, wireless device and network node to adapt measurement for narrowband Internet of Things are disclosed. According to one aspect, a method in a network node serving a wireless device includes determining reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The RS type configuration information is sent to the wireless device to configure the wireless device to perform at least one radio measurement on at least one cell based on the RS type configuration information.

Inventors:
THANGARASA SANTHAN (SE)
TESSIER STÉPHANE (SE)
AXMON JOAKIM (SE)
KAZMI MUHAMMAD (SE)
Application Number:
PCT/SE2017/050114
Publication Date:
August 17, 2017
Filing Date:
February 07, 2017
Export Citation:
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Assignee:
ERICSSON TELEFON AB L M (PUBL) (SE)
International Classes:
H04L5/00; H04W4/00; H04W4/70
Domestic Patent References:
WO2014153777A12014-10-02
WO2015119559A12015-08-13
Foreign References:
US20100246527A12010-09-30
GB2510367A2014-08-06
Other References:
HUAWEI , HISILICON: "Downlink reference signal design", IN: 3GPP TSG RAN WG1 NB-IOT AD-HOC MEETING , R1-160027, 12 January 2016 (2016-01-12), XP051053350
Attorney, Agent or Firm:
BOU FAICAL, Roger (SE)
Download PDF:
Claims:
What is claimed is:

1. A method in a network node serving a wireless device (40), the method comprising:

determining reference signal, RS, type configuration information indicating one of (a) whether the wireless device (40) is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device (40) is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell, the determining of RS type configuration information being based on criteria that includes a signal level (S124); and

sending the RS type configuration information to the wireless device (40) to configure the wireless device to perform at least one radio measurement on at least one cell based on the RS type configuration information (S126). 2. The method of Claim 1, wherein the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell.

3. The method of any of Claims 1 and 2, wherein a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary

synchronization signal, and a secondary synchronization signal.

4. The method of any of Claims 1-3, wherein the at least one

measurement is based on estimated channel quality of a cell to be measured.

5. The method of any of Claims 1-4, wherein RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement.

6. The method of any of Claims 1-5, wherein the type of reference signal employed depends on a signal quality measurement.

7. A network node for serving a wireless device (40), the network node (20) comprising:

processing circuitry (22) configured to:

determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device (40) is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device (40) is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell, the determining of RS type configuration information being based on criteria that includes a signal level; and

send the RS type configuration information to the wireless device (40) to configure the wireless device to perform at least one radio measurement on at least one cell based on the RS type configuration information.

8. The network node of Claim 7, wherein the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell.

9. The network node of any of Claims 7 and 8, wherein a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal.

10. The network node of any of Claims 7-9, wherein the at least ( measurement is based on estimated channel quality of a cell to be measured.

11. The network node of any of Claims 7-10, wherein RS type

configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement.

12. The network node of any of Claims 7-11, wherein the type of RS employed depends on a signal quality measurement.

13. A network node for serving a wireless device, the network node comprising:

an RS type configuration information determination module (31) configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device (40) is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell, the determining of RS type configuration information being based on criteria that includes a signal level; and

a transmitter module (36) configured to send the RS type configuration information to the wireless device (40) to configure the wireless device (40) to perform at least one radio measurement on at least one cell based on the RS type configuration information.

14. A method in a wireless device, the method comprising:

determining a reference signal, RS, type configuration information indicating one of (a) whether the wireless device (40) is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device (40) is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell, the determining of RS type configuration information being based on criteria that includes a signal level (S128); and

performing at least one measurement on at least one cell based on the determined RS type configuration information (S130). 15. The method of Claim 14, wherein the determined RS type

configuration information is received from a network node (20).

16. The method of any of Claims 14 and 15, wherein the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell.

17. The method of any of Claims 14-16, wherein a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary

synchronization signal, and a secondary synchronization signal.

18. The method of any of Claims 14-17, wherein the at least one measurement is based on estimated channel quality of a cell to be measured.

19. The method of any of Claims 14-18, wherein RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement.

20. The method of any of Claims 14-19, wherein the type of reference signal employed depends on a signal quality measurement.

21. A wireless device, comprising:

processing circuitry (42) configured to:

determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device (40) is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device (40) is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell, the determining of RS type configuration information being based on criteria that includes a signal level; and perform at least one measurement on at least one cell based on the determined RS type configuration information.

22. The wireless device of Claim 21, wherein the determined RS type configuration information is received from a network node (20).

23. The wireless device of any of Claims 21 and 22, wherein the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell.

24. The wireless device of any of Claims 21-23, wherein a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal.

25. The wireless device of any of Claims 21-24, wherein the at least one measurement is based on estimated channel quality of a cell to be measured.

26. The wireless device of any of Claims 21-25, wherein RS type configuration information is specific for one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement.

27. The wireless device of any of Claims 21-26, wherein the type of reference signal employed depends on a signal quality measurement.

28. A wireless device, comprising:

an RS type configuration information determination module (51) configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device (40) is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device (40) is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell, the determining of RS type configuration information being based on criteria that includes a signal level; and a measurement performance module (53) configured to perform at least one measurement on the determined RS type on at least one cell.

Description:
ADAPTING MEASUREMENT FOR NARROW BAND INTERNET OF

THINGS

TECHNICAL FIELD

This disclosure relates to wireless communication and in particular, a method, wireless device and network node for adapting measurement for narrowband Internet of Things (NB-IOT).

BACKGROUND

Machine-to-machine (M2M) communication, also known as machine type communication (MTC) or Internet of Things (IoT), is used for establishing communication between machines and between machines and humans. The communication may include the exchange of data, signaling, measurement data, configuration information, etc. The device size may vary from that of a wallet to that of a base station. The IoT devices are quite often used for applications like sensing environmental conditions (e.g., temperature reading), metering or measurement (e.g., electricity usage, etc.), fault finding or error detection, etc. In these applications, the IoT devices are active very seldom but over a consecutive duration depending upon the type of service, e.g., about 200 ms once every 2 seconds, about 500 ms every 60 minutes, etc. The IoT device may also perform measurement on other frequencies or other radio access technologies (RATs).

The path loss between a wireless IoT device and a base station can be very large in some scenarios, such as when used as a sensor or metering device located in a remote location such as in the basement of the building. In these scenarios, the adequate reception of the signal from a base station may be difficult. For example, the path loss can be worse than 20 dB compared to normal operation. In order to cope with such challenges, the coverage in the uplink (from the wireless device to the base station) and/or in the downlink (from the base station to the wireless device) has to be substantially enhanced with respect to the normal or legacy coverage. This is realized by employing one or more advanced techniques in the wireless IoT device and/or in the radio network node for enhancing the coverage. Some non-limiting examples of such advanced techniques are transmit power boosting, repetition of transmitted signal, applying additional redundancy to the transmitted signal, use of advanced/enhanced receiver, etc. In general, when employing such coverage enhancing techniques, the IoT is regarded to be operating in "coverage enhancing mode" or coverage extending mode.

A low complexity wireless device, for example one having only a single receiver, may also be capable of supporting an enhanced coverage mode of operation. The coverage level of the wireless device with respect to a cell may be expressed in terms of signal level such as signal quality, signal strength or path loss with respect to that cell.

Radio measurements performed by the wireless device are typically performed on the serving as well as on neighbor cells over some known reference symbols or pilot sequences. The measurements are performed on cells on an intra-frequency carrier, inter-frequency carrier(s) as well as on inter-radio access technology (RAT) carriers(s), depending upon the whether the wireless device supports that RAT. To enable inter-frequency and inter-RAT measurements for the wireless device requiring gaps, the network has to configure the measurement gaps.

The measurements are done for various purposes. Some example measurement purposes are: mobility, positioning, self-organizing network (SON), minimization of drive tests (MDT), operation and maintenance (O&M), network planning and optimization, etc. Examples of measurements in long term evolution (LTE) are cell identification, also known as physical cell identity (PCI) acquisition, Reference Symbol Received Power (RSRP), Reference Symbol Received Quality (RSRQ), acquisition of system information (SI), cell global ID (CGI) acquisition, Reference Signal Time Difference (RSTD), wireless device RX-TX time difference

measurement, Radio Link Monitoring (RLM), which consists of Out of

Synchronization (out of sync) detection and In Synchronization (in-sync) detection, etc. Channel state information (CSI) measurements performed by the wireless device are used for scheduling, link adaptation by the network. Examples of CSI

measurements or CSI reports are channel quality information (CQI), precoding matrix indicators (PMI), rank indicator (RI), etc. They may be performed on reference signals such as cell-specific reference symbol (CRS), CSI-RS or demodulation reference symbol (DMRS). The measurements may be unidirectional, e.g., downlink (DL) or uplink (UL) or bidirectional (e.g., having UL and DL components such as receive-transmit (Rx- Tx), round trip time (RTT), etc.).

The DL subframe # 0 and subframe # 5 carry synchronization signals (i.e., both primary synchronization signal (PSS) and secondary synchronization signal (SSS)). In order to identify an unknown cell (e.g., a new neighbor cell) the wireless device has to acquire the timing of that cell and eventually the physical cell identification (PCI). This is called a cell search or cell identification or even cell detection. Subsequently, the wireless device also measures RSRP and/or RSRQ of the newly identified cell in order to use itself and/or report the measurement to the network node. In total there are 504 PCIs. The cell search is also a type of

measurement. The measurements are done in all RRC states, i.e., in RRC idle and connected states.

In radio resource control (RRC) idle state, the wireless device performs measurements (e.g. RSRP, RSRQ, reference signal-signal to interference plus noise ratio (RS-SINR), etc.) for cell selection and reselection purposes. When camped on a cell, the wireless device regularly searches for a better cell according to the cell reselection criteria. If a better cell is found, that cell is selected. The change of cell may imply a change to a new cell within the same radio access technology (RAT) or to a cell of a different RAT. That is, the wireless device performs intra-frequency, inter-frequency or inter-RAT cell reselection. The cell reselection is performed by the wireless device autonomously based on the network configured parameters e.g., absolute radio frequency channel number (ARFCN) of carriers, signal quality/strength offsets, cell reselection timer etc.

For example, in case of, intra-frequency cell reselection in long term evolution

(LTE), the wireless device identifies new intra-frequency cells and performs RSRP and RSRQ measurements of identified intra-frequency cells without an explicit intra- frequency neighbor list containing physical layer cell identities. The wireless device is able to evaluate whether a newly detectable intra-frequency cell meets the reselection criteria within a pre-defined time period. This time is defined as a function of the discontinuous transmission (DRX) cycle used in idle state. The objective of Narrow Band Internet of Things (NB-IOT) is to specify a radio access for cellular internet of things (IOT), based to a great extent on a non- backward-compatible variant of evolved universal terrestrial radio access (E-UTRA), that addresses improved indoor coverage, support for massive number of low throughput devices, low delay sensitivity, ultra-low device cost, low device power consumption and (optimized) network architecture.

The NB-IOT carrier bandwidth (BW) (BW2) is 200 KHz. Examples of operating bandwidth (BWl) of LTE are 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz etc.

NB-IoT supports 3 different modes of operation:

1. ' Stand-alone operation' utilizing, for example, the spectrum currently being used by global system for mobile communication(GSM)-edge radio access network (GERAN) systems as a replacement of one or more GSM carriers. In principle, the mode includes operation on any carrier frequency which is neither within the carrier of another system nor within the guard-band of another system's operating carrier. The other system can be another NB-IOT operation or any other RAT, e.g. LTE.

2. 'Guard-band operation' utilizing the unused resource blocks within a LTE carrier's guard-band. The term guard-band may also interchangeably be called guard bandwidth. As an example, in case of LTE BW of 20 MHz (i.e., Bwl= 20 MHz or 100 resource blocks (RBs)), the guard-band operation of NB-IOT can be placed anywhere outside the central 18 MHz but within 20 MHz LTE BW.

3. Ίη-band operation' utilizing resource blocks within a normal LTE carrier. The in-band operation may also interchangeably be called in-bandwidth operation. More generally, the operation of one RAT within the BW of another RAT is also called in- band operation. As an example, in a LTE BW of 50 RBs (i.e., Bwl= 10 MHz or 50 RBs), NB-IOT operation over one resource block (RB) within the 50 RBs is called in- band operation.

In NB-IOT, the downlink transmission is based on orthogonal frequency division multiplexing (OFDM) with 15kHz subcarrier spacing for all three scenarios: stand-alone, guard-band, and in-band. For UL transmission, both multi-tone transmissions based on single carrier frequency division multiple access (SC-FDMA), and single tone transmission is supported. This means that the physical waveforms for NB-IoT in the downlink and also partly in the uplink is similar to legacy LTE. In the downlink design, NB-IOT supports both master information broadcast (MIB) and system information broadcast (SIB) which are carried by different physical channels. For in-band operation, it is possible for NB-IoT wireless device to decode NB-PBCH without knowing the legacy PRB index. NB-IoT supports both downlink physical control channel (NB-PDCCH, or NB-M-PDCCH) and downlink physical shared channel (PDSCH). The operation mode of NB-IOT must be indicated to the wireless device, and currently 3GPP consider indication by means of NB-SSS, NB-MIB or perhaps other downlink signals.

At the moment, reference signals used in NB-IOT have not been decided. However, it is expected that the general design principle will follow that of legacy LTE. Downlink synchronization signals will most likely consist of primary synchronization signals (NB-PSS) and secondary synchronization signals (NB-SSS).

[0016] NB-IOT is a new radio access technology/feature based on LTE technology that is currently being specified in the third generation partnership project (3GPP). The NB-IOT device has to perform measurements on received downlink signals from the serving- and/or identified neighbor cells. Since NB-IOT is a new feature, measurement procedures have not yet been specified. Different options for measurement technology are being considered.

A main difference of NB-IOT compared to the legacy LTE measurement procedure is that wireless device bandwidth is reduced to 1 PRB only. Thus, the existing measurement, which is based on cell specific reference signals (CRS) on at least 6 PRBs, may not work very well for the NB-IoT. Going from a wireless device bandwidth of 6 PRBs to 1 PRB means that the number of resource elements available for measurement is significantly reduced, and that will affect the measurement accuracy as well as measurement time/rate. Furthermore, the NB-IOT wireless device may be capable of two or more operational modes, i.e., stand-alone, guard-band, and in-band modes. This may further impact the measurement procedure of the wireless device. SUMMARY

Some embodiments advantageously provide a method, wireless device and network node for configuring measurements of narrowband Internet of Things.

According to one aspect, a method in a network node serving a wireless device includes determining reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The method also includes sending the RS type configuration information to the wireless device to configure the wireless device to perform at least one radio measurement on at least one cell based on the RS type configuration information.

According to this aspect, in some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of reference signal employed depends on a signal quality measurement.

According to another aspect, a network node for adapting measurement for narrowband Internet of Things is provided. According to this aspect, processing circuitry is configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The processing circuitry is also configured to send the RS type configuration information to the wireless device to configure the wireless device to perform at least one radio measurement on at least one cell based on the RS type configuration information

According to this aspect, in some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of RS employed depends on a signal quality measurement.

According to another aspect, a network node for serving a wireless device includes an RS type configuration information determination module is configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. A transmitter module configured to send the RS type configuration information to the wireless device to configure the wireless device to perform at least one radio measurement on at least one cell based on the RS type configuration information.

According to yet another aspect, a method in a wireless device includes determining a reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The method also includes performing at least one measurement on at least one cell based on the determined RS type configuration information.

According to this aspect, in some embodiments, the determined RS type configuration information is received from a network node. In some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one

measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of reference signal employed depends on a signal quality measurement.

According to yet another aspect, a wireless device includes processing circuitry configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The processing circuitry is further configured to perform at least one measurement on at least one cell based on the determined RS type configuration information.

According to this aspect, in some embodiments, the determined RS type configuration information is received from a network node. In some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific for one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of reference signal employed depends on a signal quality measurement.

According to another aspect, a wireless device includes an RS type

configuration information determination module configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The wireless device also includes a measurement performance module configured to perform at least one measurement on the determined RS type on at least one cell.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block of a wireless communication network constructed in accordance with principles set forth herein;

FIG. 2 is a block diagram of a network node constructed in accordance with principles set forth herein;

FIG. 3 is a block diagram of an alternative embodiment of a network node constructed in accordance with principles set forth herein;

FIG. 4 is a block diagram of a wireless device constructed in accordance with principles set forth herein;

FIG. 5 is a block diagram of an alternative embodiment of a wireless device constructed in accordance with principles set forth herein; FIG. 6 is a flowchart of an exemplary process in a network node for determining an RS configuration type and configuring a wireless device;

FIG. 7 is a flowchart of an exemplary process performed by a wireless device according to an RS configuration received from the network node;

FIG. 8 is a flowchart of an exemplary process performed by a wireless device;

FIG. 9 is a flowchart of an exemplary process for determining an RS type at a network node; and

FIG. 10 is a flowchart of an exemplary process for selecting and RS type and implementing a performance measurement by a wireless device.

DETAILED DESCRIPTION

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to adapting measurement for narrowband Internet of Things (NB-IOT). Accordingly, the system and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. As used herein, relational terms, such as "first" and "second," "top" and

"bottom," and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements.

In some embodiments, based on at least the signal to noise ratio (SNR) level of signals received from a cell on which the measurement is to be performed, the network (NW) adapts the type of signals that are transmitted on which the

measurement is to be performed, and/or the wireless device adapts signals on which the measurement is performed to meet one or more pre-defined measurement requirements. In addition, the network node may configure and/or signal the information on which the device should measure. The receiving device may adapt its measurement procedure according to received configuration/signaling information. For example, the network node may configure the wireless device to measure according to configuration A when the quality of a reported measurement is greater than a certain threshold T, and it may configure the wireless device to measure according to configuration B when the quality of a reported measurement is below the threshold T. Configuration A may include information on what type of reference signals the wireless device should measure (e.g., CRS), while configuration B may indicate that the wireless device should measure using synchronization signals, which are specific types of reference signals. In addition, depending on what type of configurations are configured or what configurations the wireless device follows when performing the measurements, different requirements apply.

Note that the term reference signal is here used in a broad sense and may comprise for instance NB-IoT cell specific reference signals (CRS), NB-IoT specific demodulation reference signals (DM-RS), NB-IoT Primary Synchronization Signals, NB-IoT Secondary Synchronization Signals, channels with known or predictable contents, NB-IoT specific discovery signals, etc.

Referring now to the drawing figures in which like reference designators refer to like elements, FIG. 1 is a block of a wireless communication network 10, including a network cloud 16, network nodes 20 A and 20B, herein referred to collectively as network nodes 20, and wireless devices 40A and 40B, herein referred to collectively as wireless devices 40. Network nodes 20 may be base stations which may be in communication with one another by an X2 interface. The cloud 16 may include the Internet and/or the public switched telephone network (PSTN) and may include a backhaul network for the network nodes 20. The network nodes 20 are in

communication with the WDs 40 and the WDs may be in communication with each other by direct wireless link. Although only two network nodes 20 and two WDs 40 are shown for convenience, more or fewer network nodes 20 and WDs 40 may be employed in practice. A network node 20 constructed in accordance with principles set forth herein include an RS type configuration determiner 30 which is configured to determine what types of reference signals the wireless device 40 should measure. In some embodiments, a wireless device 40 constructed in accordance with principles set forth herein include an RS type configuration selector 50 which is configured to select one of a plurality of RS the wireless device 40 should measure. Also, each network node 20 may serve multiple cells which are different geographical coverage areas.

In some embodiments, the term "network node" is used and it can correspond to any type of radio network node or any network node 20, which communicates with a wireless device 40 and/or with another network node. Examples of network nodes are NodeB, master e B (Me B), secondary e B (Se B), a network node belonging to a master cell group (MCG) or secondary cell group (SCG), base station (BS), multi- standard radio (MSR) radio node such as MSR BS, eNodeB, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), access point (AP), transmission points, transmission nodes, remote radio unit (RRU), remote radio head (RRH), nodes in distributed antenna system (DAS), core network node (e.g. MSC, MME, etc.), O&M, OSS, SON, positioning node (e.g. evolved serving mobile location center (E- SMLC)), minimizing drive tests (MDT) etc.

Although embodiments are described herein with reference to certain functions being performed by a network node 20, it is understood that the functions can be performed in other network nodes and elements. It is also understood that the functions of the network node 20 or other network nodes can be distributed across network cloud 16 so that other nodes can perform one or more functions or even parts of functions described herein.

The wireless device 40 herein can be any type of wireless device capable of communicating with a network node 20 or another wireless device over radio signals. The wireless device 40 may also be a radio communication device, target device, device to device (D2D) wireless device , machine type wireless device or wireless device capable of machine to machine communication (M2M), low-cost and/or low- complexity wireless device , a sensor equipped with wireless device, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device, etc.

Also, in some embodiments, the generic term "radio network node" or

"network node" is used. This device can be any kind of a radio network node which may include any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, Multi- cell/multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

In some embodiments, the wireless device 40 may be configured with PCell and PSCell or with PCell, PSCell and one or more SCells such as in dual connectivity and/or carrier aggregation. The configured cells are wireless device specific serving cells of the wireless device 40.

FIG. 2 is a block diagram of an example network node 20 including processing circuitry 22. In some embodiments, the processing circuitry may include a memory 24 and processor 26, the memory 24 containing instructions which, when executed by the processor 26, configure processor 26 to perform the one or more functions described herein. In addition to a traditional processor and memory, processing circuitry 22 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry).

Processing circuitry 22 may include and/or be connected to and/or be configured for accessing (e.g., writing to and/or reading from) memory 24, which may include any kind of volatile and/or non-volatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only

Memory). Such memory 24 may be configured to store code executable by control circuitry and/or other data, e.g., data pertaining to communication, e.g., configuration and/or address data of nodes, etc. Processing circuitry 22 may be configured to control any of the methods described herein and/or to cause such methods to be performed, e.g., by processor 26. Corresponding instructions may be stored in the memory 24, which may be readable and/or readably connected to the processing circuitry 22. In other words, processing circuitry 22 may include a controller, which may comprise a microprocessor and/or microcontroller and/or FPGA (Field- Programmable Gate Array) device and/or ASIC (Application Specific Integrated Circuit) device. It may be considered that processing circuitry 22 includes or may be connected or connectable to memory, which may be configured to be accessible for reading and/or writing by the controller and/or processing circuitry 22.

The memory is configured to store RS type configuration information 28 as determined by an RS type configuration information determiner 30. The RS type configuration information specifies (a) whether the wireless device 40 is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. A receiver 34 is configured to receive channel measurement data from the wireless device 40. A transmitter 36 is configured to send the RS type configuration information to the wireless device 40.

FIG. 3 is a block diagram of an alternative network node 20 to perform the functions described herein. In particular, some of the functions of network node 20 may be implemented as software executed by a processor. The network node 20 includes a memory 24 that is configured to store RS type configuration information 28. An RS type configuration information determination module 31 is configured to determine the RS type configuration information. The receiver module 35 and transmitter module 37 may be implemented in part in software executed by a processor. The transmitter module 37 is configured to send the RS type configuration information to the wireless device 40.

FIG. 4 is a block diagram of a wireless device 40 that includes processing circuitry 42. In some embodiments, the processing circuitry may include a memory 44 and processor 46, the memory 44 containing instructions which, when executed by the processor 46, configure processor 46 to perform the one or more functions described herein. In addition to a traditional processor and memory, processing circuitry 42 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry).

Processing circuitry 42 may include and/or be connected to and/or be configured for accessing (e.g., writing to and/or reading from) memory 44, which may include any kind of volatile and/or non-volatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only

Memory). Such memory 44 may be configured to store code executable by control circuitry and/or other data, e.g., data pertaining to communication, e.g., configuration and/or address data of nodes, etc. Processing circuitry 42 may be configured to control any of the methods described herein and/or to cause such methods to be performed, e.g., by processor 46. Corresponding instructions may be stored in the memory 44, which may be readable and/or readably connected to the processing circuitry 42. In other words, processing circuitry 42 may include a controller, which may comprise a microprocessor and/or microcontroller and/or FPGA (Field- Programmable Gate Array) device and/or ASIC (Application Specific Integrated Circuit) device. It may be considered that processing circuitry 42 includes or may be connected or connectable to memory, which may be configured to be accessible for reading and/or writing by the controller and/or processing circuitry 42.

The memory 44 is configured to store RS type configuration information 48 received from a network node or generated by the wireless device 40 and to perform the functions described herein with respect to the wireless device 40. The RS type configuration information 48 indicates (a) whether the wireless device is to use only one type reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The RS type configuration information may be received from the network node 20 or determined by the wireless device 40 based on criteria that includes a signal level. The processor 46 is configured to implement an RS type configuration selector 50 configured to select one of a plurality of optional RS configuration types based on the RS type configuration information 48. The processor 46 is also configured to perform a radio measurement 53 based on the selected RS configuration type. The receiver 54 is configured to receive RS type configuration information from a network node 20 and the transmitter 56 is configured to transmit performance measurements to the network node 20.

FIG. 5 is a block diagram of an alternative wireless device 40. The wireless device 40 includes a memory module 44 that is configured to store RS type configuration information 48. The wireless device 40 includes an RS type

configuration selector module 51 configured to select one of a plurality of optional RS configuration types based on the RS type configuration information 48. The wireless device 48 further includes a measurement performance module 53 configured to perform at least one measurement on at least one cell based on the determined RS type configuration information. The receiver module 55 and the transmitter module 57 may be implemented in part by software executed by a processor.

The overall process described herein can be summarized as follows:

A method in a network node 20 (e.g., eNodeB or other base station) serving a wireless device 40 may include the steps of:

• Determining, based on one or more criteria (e.g., wireless device coverage level), reference signal (RS) type configuration information, the information indicating whether: o the wireless device 40 is to use only one type of reference signal on one or more cells for performing one or more radio measurements on one or more cells; or o the wireless device 40 is to use a combination of two or more types of reference signals for performing one or more radio measurements on one or more cells; and · Configuring the wireless device 40 with the determined RS type configuration information for enabling the wireless device 40 for performing at least one measurement on at least one cell.

A method in a wireless device 40 served by a first cell by a network node 20 (e.g., eNode B or other base station) may include:

· Receiving from the network node 20 at least reference signal (RS) type

configuration information, the information indicating whether:

o the wireless device 40 is to use only one type of reference signal on one or more cells for performing one or more radio measurements on one or more cells; or o the wireless device 40 is to use a combination of two or more types of reference signals for performing one or more radio measurements on one or more cells;

• Determining, based on the received RS type configuration information, the type of RS to be used by the wireless device 40 for performing one or more radio measurements on one or more cells; and

• Performing at least one measurement on the determined RS type on at least one cell. In another embodiment, a method in a wireless device 40 served by a first cell by a network node 20 (e.g., eNode B or other base station) may include:

• Receiving from the network node 20 at least two of the following sets of reference signal (RS) type configuration information: o a first type of reference signal that can be used by the wireless device 40 for performing one or more radio measurements on one or more cells; o a second type of reference signal that can be used by the wireless device 40 for performing one or more radio measurements on one or more cells; and o a combination of at least the first and the second types of reference signal that can be used by the wireless device 40 for performing one or more radio measurements on one or more cells;

• Selecting based on one or more criteria (e.g., wireless device 40 coverage level with respect to the measured cell) one of the received RS type configurations; and

• Using the received RS type information for performing at least one radio

measurement on at least one cell.

In yet another embodiment, a method in a wireless device 40 served by a first cell by a network node 20 (e.g., eNode B or other base station) includes:

• Obtaining information about at least two of the following sets of a reference signal (RS) type configuration information: o a first type of reference signal that can be used by the wireless device 40 for performing one or more radio measurements on one or more cells; o a second type of reference signal that can be used by the wireless device 40 for performing one or more radio measurements on one or more cells; and o a combination of at least the first and the second types of reference signal that can be used by the wireless device 40 for performing one or more radio measurements on one or more cells;

• Determining a coverage enhancement level (CE) of at least one cell on which the measurement is being or is to be performed by the wireless device 40; · Selecting based on at least the determined CE level of the cell one of the obtained RS type configurations (e.g., first or second type of RS when the CE is below a threshold and combination of first and second type of RS when the CE is equal or above the threshold); and

• Using the selected RS type information for performing at least one radio

measurement on the cell.

This method may allow the wireless device 40 to improve its measurement performance because the choice of measurement procedure is adapted based on estimated channel quality of the measured cell, operational mode, coverage enhancement level, etc. This may result in improved measurement accuracy, but also in some cases reduced processing, and improved battery life in the wireless device 40 because the sampling frequency can be adapted based on obtained information. This may in turn improve the performance of other functionalities that depend on reliable measurement performance such as mobility, Automatic Neighbor Relation (ANR), SON, etc.

FIG. 6 is a flowchart of an exemplary process in a network node 20 for determining an RS configuration type and configuring a wireless device 40. The process includes determining a set of criteria such as coverage level (block SI 00). A configuration is determined based on the criteria via the RS type configuration information determiner 30 (block S102). The configuration specifies one of a first type of reference signal (block SI 04 A), a second type of reference signal (block S104B), and a third type of reference signal (block S104C). In the alternative to a third type of reference signal, the configuration may specify a combination of the first and second types of reference signals. Note also that embodiments are not limited to specification of only three types of reference signals, as more or less than three reference signals may be specified. The three types of reference signals shown in FIG. 7 are merely an example. In some embodiments, the process includes sending the RS type configuration information to the wireless device 40 via the transmitter 36 (block SI 06).

FIG. 7 is a flowchart of an exemplary process performed by a wireless device

40 according to an RS configuration received from the network node 20 (block SI 08). A type of RS configuration information based on the received configuration is determined via the RS type configuration selector 50 (block SI 10). A measurement is performed by the wireless device 40 via the measurement performance unit 52 (block S112).

FIG. 8 is a flowchart of an alternative exemplary process performed by a wireless device 40 In FIG. 8, the wireless device 40 evaluates a set of criteria as the basis upon which RS type to select, whereas in FIG. 7, the wireless device 40 uses the selection made by the network node 20. The process includes receiving RS type configuration information from a network node 20 (block SI 14). The wireless device 40 evaluates a set of criteria that may include a coverage level (block SI 16). An RS type configuration is determined based on the criteria via RS type configuration selector 50 (block SI 18). One of a first, second and third type of reference signal is selected (S120A, S120B and S120C) and a measurement on the RS is performed via the measurement performance unit 52 according to the selection (block S122). In the alternative to selecting a third type of reference signal, a RS type configuration selector 50 may select a combination of the first and second types of reference signals. Note also that embodiments are not limited to specification of only three types of reference signals, as more or less than three may be specified.

FIG. 9 is a flowchart of an exemplary process for determining an RS type at a network node 20. The process includes determining, via the RS type configuration information determiner 30, reference signal, RS, type configuration information indicating one of (a) whether the wireless device 40 is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell (block S124). The process also further includes sending, via the transmitter 36, the determined RS type configuration information to configure the wireless device to perform at least one radio measurement on at least one cell (block S126).

FIG. 10 is a flowchart of an exemplary process for selecting and RS type and implementing a performance measurement by a wireless device 40. In the

embodiment of FIG. 10 a choice between a single RS type and multiple RS types is presented. The process includes determining, via RS type configuration selector 50, reference signal, RS, type configuration information indicating one of (a) whether the wireless device 40 is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell (block S128). The process also includes performing, via the measurement performance unit 52, at least one measurement on at least one cell based on the determined RS type configuration information (block S130).

The wireless device 40 may be served by a serving cell which has already been identified by the wireless device 40. The wireless device 40 further identifies at least one other cell, which may be called a target cell or neighbor cell. In some embodiments, the serving cell and neighbor cell are served or managed by the first network node 20A and the second network node 20B, respectively. In some embodiments, the serving cell and neighbor cell are served or managed by the same network node 20, e.g. a first network node 20A.

The embodiments are applicable for a wireless device 40 in a low or in high activity state. Examples of low activity state are RRC idle state, idle mode etc.

Examples of high activity state are RRC CONNECTED state, active mode, active state etc. The wireless device 40 may be configured to operate in DRX or in non-

DRX. If configured to operate in DRX, it may still operate according to non-DRX as long as it receives new transmissions from the network node 20. The wireless device 40 may operate under normal coverage, extended coverage or extreme coverage with respect to its serving cell or the target cell on which the measurement is to be performed. These coverage classes are also interchangeably referred to as normal coverage and enhanced coverage in some cases. The wireless device 40 may also operate in a plurality of coverage levels e.g. normal coverage, enhanced coverage level 1, enhanced coverage level 2, enhanced coverage level 3 and so on.

The coverage level may be expressed in terms of:

• received signal quality and/or received signal strength at the wireless device 40 with respect to its serving cell; and/or

• received signal quality and/or received signal strength at the serving cell with respect to the wireless device 40.

Examples of signal quality are S R, SINR, CQI, RSRQ, CRS Es/Iot, SCH Es/Iot, etc. Examples of signal strength are path loss, RSRP, SCH RP, etc. The notation Es/Iot is defined as ratio of:

• Es, which is the received energy per RE (power normalized to the subcarrier

spacing) during the useful part of the symbol, i.e., excluding the cyclic prefix, at the wireless device antenna connector, to

• lot which is the received power spectral density of the total noise and interference for a certain RE (power integrated over the RE and normalized to the subcarrier spacing) as measured at the wireless device antenna connector.

Consider an example of 2 coverage levels defined with respect to signal quality (e.g., SNR) at the wireless device 40, including:

• Coverage enhancement level 1 (CE1) where SNR > -6 dB at wireless device 40 with respect to its serving cell; and

• Coverage enhancement level 2 (CE2) where -12 dB < SNR < -6 dB at wireless device 40 with respect to its serving cell.

Consider another example of 4 coverage levels, including:

• Coverage enhancement level 1 (CE1) where SNR > -6 dB at wireless device 40 with respect to its serving cell; • Coverage enhancement level 2 (CE2) where -12 dB < S R < -6 dB at wireless device 40 with respect to its serving cell;

• Coverage enhancement level 3 (CE3) where -15 dB < SNR < -12 dB at wireless device 40 with respect to its serving cell; and

· Coverage enhancement level 4 (CE4) where -18 dB < SNR < -15 dB at wireless device 40 with respect to its serving cell.

In the above example the CE1 may also interchangeably be referred to as normal coverage level, baseline coverage level, reference coverage level, legacy coverage level etc. On the other hand, CE2-CE4 may be termed enhanced coverage or extended coverage 1 evel .

The embodiments are described herein within the context of NB-IOT devices. However, the embodiments are applicable to any RAT or multi-RAT systems where a measurement configuration is adapted based on channel quality of the measured cells.

One embodiment includes a method in a network node 20, that is serving at least one wireless device 40 (e.g., NB-IOT device). This embodiment also applies to a method in network node 20 serving a plurality of wireless devices in a cell.

A wireless device 40 in RRC connected state may be configured by network node 20 with measurement configuration using a dedicated signaling e.g. via RRC signaling on a shared channel. All or a plurality of wireless devices 40 in RRC idle state in the same cell may be configured by network node 20 with measurement configuration using a common signaling e.g. via RRC signaling on a broadcast channel. The method enables network node 20 to derive a measurement configuration which is customized for wireless device 40 or for a plurality of wireless devices in the cell. The measurement configuration may comprise information on at least what type of signals (e.g., cell specific reference signals, synchronization signals, combination thereof, etc.) a wireless device 40 should measure on.

It is assumed that at least the following two types of reference signals, which can be used by the wireless device 40 are transmitted by (on one or more cells):

• a first type of reference signal; and

· a second type of reference signal.

The first and the second types of reference signals (RSs) differ in terms of non-limiting examples of one or more of the following physical layer aspects: • the density of RS in time and/or frequency e.g. number of subcarriers containing RS per RB, number of symbols containing RS per RB etc.;

• the periodicity of occurrence of RS e.g. occurrence of a RB containing RS every 10 ms, every 20 ms, every 80 mc etc.;

· channel coding used for RS;

• modulation used for RS;

• Maximum number of antenna ports that can be used for transmitting RS;

• Number of antenna ports currently used for transmitting RS; and

• Deployment mode of the cell in which the RS is transmitted.

An example of the first type of RS is CRS, e.g., NB-IOT related CRS. An example of the second type of RS is synchronization signals, e.g., NB-IOT related secondary synchronization signal (SSS), primary synchronization signal (PSS) which are also known as NB-SSS and NB-PSS, etc. For example, NB-SSS are transmitted with higher density in time and frequency compared to CRS in NB-IOT system.

The measurement configuration in the network node 20 may include at least the reference signal (RS) type information to be used by the wireless device 40 for the measurement. That is, the network node 20 indicates whether the wireless device 40 is to perform one or more measurements in one or more cells using:

· Only one type of reference signal; or

• A combination of two or more types of reference signals.

More specifically, in one exemplary implementation the network node 20 may indicate, as part of RS type information, whether the wireless device 40 is to perform one or more measurements in one or more cells using:

· The first type of reference signal; or

• The second type of reference signal.

In another exemplary implementation, the network node 20 may indicate, as part of RS type information, whether the wireless device 40 is to perform one or more measurements in one or more cells using:

· The first type of reference signal; or • A combination of the first type of reference signal and the second type of reference signal.

In yet another exemplary implementation, the network node 20 may indicate, as part of RS type information, whether the wireless device 40 is to perform one or more measurements in one or more cells using:

• The second type of reference signal; or

• A combination of the first type of reference signal and the second type of

reference signal.

In the above exemplary embodiments, upon receiving the RS type

information, the wireless device 40 may use the indicated 'RS type' or 'combination of RS types' for performing measurements on one or more cells.

Alternatively, the network node 20 may provide, as part of RS type information, a list of two or more sets of RS to the wireless device 40. Each set may contain one type of RS or plurality of RSs. In this case, the wireless device 40 may autonomously determine, based on one or more criteria, the type of RS or

combination of RS types to be used for performing one or more measurements on one or more cells. Examples of criteria are signal quality (e.g., SINR) of the measured cell, coverage level of the cell, deployment mode (e.g., in-band, guard-band, standalone, etc.) of the measured cell, etc. The criteria may be pre-defined or configured by the network node 20 at the wireless device 40. For example, wireless device 40 may be configured to use either the second type of RS (e.g., B-SSS) or a

combination of the first and the second type of RSs (e.g., CRS and NB-SSS). In case of normal coverage (e.g., SINR > - 6 dB), with respect to the measured cell the wireless device 40 may use only the second type of RS for doing measurement on that cell. But in case of enhanced coverage (e.g. SINR < - 6 dB) with respect to the measured cell the wireless device 40 may use a combination of the first and the second type of RSs for doing measurement on that cell.

The RS type information provided by the network node 20 may be specific for one or more of the following:

· for a particular cell;

• for a group of cells;

• for all cells on the same carrier frequency; • for all cells on all the configured carrier frequencies, etc.; and

• for a particular type of measurement, e.g., RSRP, SINR, etc.

More specifically the network node 20 determines that the wireless device 40 is to perform one or more radio measurements on one or more cells based on one, or a combination of more, reference signals. Another type of information that the measurement configuration may include is information on which symbols to measure on, measurement period, filtering coefficient information etc. The measurement configuration is derived based on at least reported channel state information.

Examples of channel state information are reported CQI, RSRP, RSRQ, RS-SINR, etc.

As explained above, the B-IOT wireless device 40 can be operated under different coverage enhancement levels. For example, under normal coverage level (such as CE1) with good channel quality to the measured cell, wireless device 40 may be able to meet the measurement accuracy requirements by following a legacy measurement procedure. Legacy measurement procedure herein implies measurement using CRS signals. However, a NB-IOT wireless device 40 operating under extended coverage (e.g., CE2 or CE3) may not be able to meet the measurement requirements using the legacy measurement procedure. One reason for this could be that the wireless device 40 operating under extended coverage may experience a bad channel to the target cell, i.e., the SNR or SINR may be low. Another reason may be that the number of resource elements used for measurement may be significantly reduced when measuring over CRS REs over 1 PRB compared to 6 PRBs.

Another embodiment enables the network node 20 to derive a configuration related to measurement procedure which intends to reflect the current channel quality. The configuration can be derived based on reported channel state information by the wireless device 40. If the target cell is already known to the wireless device 40, e.g., the wireless device 40 has already identified that cell, or the wireless device 40 has already performed some measurements on that cell, then the network node 20 may use such information to derive the configuration.

An advantage of this embodiment is that the network node 20 is able to dynamically adapt the measurement configuration of a particular wireless device 40 to enable that wireless device to meet the measurement requirements. The measurement requirements in this case can be accuracy requirements (i.e., the uncertainty of measurement) or the delay of a measurement. In one embodiment, the adaptation in the network node 20 can be as follows:

• when the reported channel state information is high (e.g. SINR> threshold Tl), the configuration may enable the wireless device 40 to perform the measurement using the existing method, i.e., using CRS signals. The value of Tl could be predefined or a configurable parameter.

• When the reported channel state information is low (e.g. SINR < Tl), the

configuration may enable the wireless device 40 to perform measurement using an adaptive method, i.e., using synchronization signals (e.g. B-PSS, NB-SSS).

• When the reported channel state information is very low, (e.g. SINR <T0, wherein T0<T1), the configuration may enable the wireless device 40 to perform measurement using an adaptive method, i.e. using both CRS and synchronization signals (e.g. NB-PSS, NB-SSS). The value of TO could be predefined or a configurable parameter.

The measurement performance of a measurement done using only the first type of RS (e.g. CRS signals) may be worse compared to the second type of RS (e.g. NB-SSS signals). Examples of measurement performance metric or criteria are measurement accuracy, measurement period, etc. A measurement performance having a longer measurement period is worse than a performance having a shorter measurement period. This is because the density of NB-SSS can be higher, i.e., the number of resource elements containing the NB-SSS is much higher than the number of resource elements containing CRS. Thus, the measurement performance using NB- SSS may result in improved accuracy. Likewise, when the measurement is performed over both CRS and synchronization signals the accuracy can be further improved since even more number of resource elements are used for measurement. Since the measurement accuracy becomes a function of type of signals used for measurement, the network node 20 may use this information to derive the measurement

configuration which is later communicated to the wireless device 40.

In addition to number of resource elements, the measurement performance can also be improved by adapting the measurement filtering coefficient. A larger value of filtering coefficient may result in significantly improved accuracy in some cases (e.g., when the channel is not changing very much, or at low-mobility scenarios) while in other cases a smaller value can be preferred (e.g., at high Doppler scenarios). A larger value means that the number of samples or averages used for achieving the measurement result is increased. The adaptation in the network node 20 can be as follows:

• when the reported channel state information is high (e.g., SINR> threshold Tl), the configuration may enable the wireless device 40 to perform the measurement using filtering coefficient 1. Filtering coefficient 1 may correspond to a LI measurement period of 400 ms. The value of Tl could be predefined or a configurable parameter.

• When the reported channel state information is low (e.g., SINR < Tl), the

configuration may enable the wireless device 40 to perform measurement using filtering coefficient 2. Filtering coefficient 2 may correspond to a LI measurement period of 800 ms.

· When the reported channel state information is very low, (e.g., SINR <T0,

wherein T0<T1), the configuration may enable the wireless device 40 to perform measurement using filtering coefficient 3. Filtering coefficient 3 may correspond to a LI measurement period of 1600 ms. The value of TO could be predefined or a configurable parameter.

One example of measurement configuration derived in the network node 20 is shown in Table 1 below:

Table 1 : Example of adaptive measurement configuration

Es/Iot [dB] Type of Filtering Number of Type of signals to coefficient or consecutive averaging measure on measurement subframes to (coherent- or period be used for non-coherent measurement averaging)

Es/Iot≥-6 First type of 200 ms 1 Coherently dB reference within signal sample and non- coherently over the samples

-10 < Second type 400 ms 2 Coherently Es/Iot < -6 of reference within signal sample and non- coherently over the samples

-15 < Second type 800 ms 2 Coherently Es/Iot < - of reference within

10 signal sample and non- coherently over the samples

-20 < Combination 1600 ms 4 Coherently Es/Iot < - of first and within

15 second type sample and non- coherently over the samples

One embodiment is a method in a wireless device 40 to obtain, acquire, or determine a configuration related to the measurement procedure from the network node 20. The wireless device 40 uses the obtained configuration to adapt its measurement procedure to perform one or more measurements on a target cell. The target cell may include the serving cell, and/or other neighbor cells.

A wireless device 40 in RRC connected state may be configured by the network node 20 with a measurement configuration using a dedicated signaling, e.g., via RRC signaling on a shared channel. The wireless device 40 in RRC idle state in may be configured by the network node 20 with measurement configuration using a common signaling, e.g., via RRC signaling on a broadcast channel.

In some embodiment, it may be assumed that the received measurement information includes at least the following two types of reference signals (a first type of reference signal and a second type of reference signal), and some additional information related to measurements that may include:

• what filtering coefficient to use;

• the number of consecutive subframes to use for measurement; and

· whether to adopt coherent-averaging or non-coherent averaging

The latter may for instance include whether the B-IoT wireless device 40 can assume that, e.g., SSS and CRS are transmitted from the same antenna constellation by which they can be coherently combined, or whether they are transmitted from different antenna constellations by which they have to be non-coherently combined. In case the SSS is alternated between antenna constellations, a pattern may be conveyed from which the wireless device 40 can alternate between coherent and noncoherent combining.

The first and the second types of reference signals (RSs) differ in terms of non-limiting examples of one or more of the following physical layer aspects:

· o the density of RS in time and/or frequency e.g. number of subcarriers

containing RS per RB, number of symbols containing RS per RB, etc.; o the periodicity of occurrence of RS e.g. occurrence of a RB containing RS every 10 ms, every 20 ms, every 80 mc etc.;

• channel coding used for RS;

· maximum number of antenna ports that can be used for transmitting RS;

• number of antenna ports currently used for transmitting RS; and

• deployment mode of the cell in which the RS is transmitted.

An example of the first type of RS is CRS, e.g., NB-IOT related CRS. An example of the second type of RS is synchronization signals, e.g., NB-IOT related SSS, PSS which are also known as NB-SSS and NB-PSSS, etc. For example, NB- SSS are transmitted with higher density in time and frequency compared to CRS in NB-IOT system.

The measurement configuration received from the network node 20 may include at least the reference signal (RS) type information to be used by the wireless device 40 for the measurement. That is the network node 20indicates whether the wireless device 40 is to perform one or more measurements in one or more cells using:

• Only one type of reference signal; or

• Combination of two or more types of reference signals.

More specifically in one exemplary implementation the network node 20 may indicate, as part of RS type information, whether the wireless device 40 is to perform one or more measurements in one or more cells using:

• The first type of reference signal; or

• The second type of reference signal.

In another exemplary implementation, the network node 20 may indicate, as part of RS type information, whether the wireless device 40 is to perform one or more measurements in one or more cells using:

• The first type of reference signal; or

• Combination of the first type of reference signal and the second type of reference signal.

In yet another exemplary implementation, the network node 20 may indicate, as part of RS type information, whether the wireless device 40 is to perform one or more measurements in one or more cells using:

• The second type of reference signal; or

· Combination of the first type of reference signal and the second type of reference signal.

In the above exemplary embodiments, upon receiving the RS type

information, the wireless device 40 will use the indicated 'RS type' or 'combination of RS types' to perform measurements on one or more cells.

Alternatively, the network node 20 may provide, as part of RS type information, a list of two or more sets of RS to the wireless device 40. Each set may contain one type of RS or plurality of RSs. In this case the wireless device 40 may autonomously determine, based on one or more criteria, the type of RS or

combination of RS types to be used for performing one or more measurements on one or more cells. Examples of criteria are signal quality (e.g., SINR) of the measured cell, coverage level of the cell, deployment mode (e.g., in-band, guard-band, stand- alone, etc.) of the measured cell etc. The criteria may be pre-defined or configured by the network node 20 at the wireless device 40. For example, a wireless device 40 may be configured to use either the second type of RS (e.g., B-SSS) or a combination of the first and the second type of RSs (e.g. CRS and NB-SSS). In case of normal coverage (e.g., SINR > - 6 dB) with respect to the measured cell, the wireless device 40 may use only the second type of RS to perform measurement on that cell. But in case of enhanced coverage (e.g., SINR < - 6 dB) with respect to the measured cell the wireless device 40 may use a combination of the first and the second type of RSs for doing measurement on that cell.

The RS type information provided by the network node 20 may be specific for one or more of the following:

• for a particular cell;

• for a group of cells;

• for all cells on the same carrier frequency;

· for all cells on all the configured carrier frequencies etc., and

• for a particular type of measurement, e.g., RSRP, SINR, etc.

Non-limiting examples of methods which can be implemented in the wireless device 40 for obtaining configuration related to measurement procedure are:

• The wireless device 40 may obtain the configuration related to the measurement procedure from the serving network node 20, e.g., from network node 20 serving any of the serving cells such as PCell, SCell, PSCell, etc.

• The wireless device 40 may also obtain the configuration related to measurement procedure from other network nodes, such as neighbor network nodes, core- network node, or other type of dedicated or non-dedicated nodes. For example, in this case the wireless device 40 may read the system information sent on a broadcast channel by the network node 20.

• The wireless device 40 may also be pre-configured with full or partial

configuration related to the measurement procedure. In case of pre-configuration of the partial information some parameters can be pre-configured while the remaining parameters can be received from the network node 20. The wireless device 40 can be pre-configured with one or more parameters related to the measurement procedure in one or more of the following ways:

o pre-configured by the last serving cell (e.g., PCell) using signaling; and o pre-configured by the operator e.g. information stored in the SIM-card, information acquired from an application program, etc. The wireless device 40 can retrieve the information when reading information on the SIM card and/or from the application program,

o pre-defined in the specification/ standard. For example, the type of signals to measure on, when those signals are transmitted, what symbols to measure on, etc., can be pre-defined.

• The wireless device 40 may also obtain full or partial information on carrier

groups for measurement based on statistics or historical data stored in the memory of the wireless device 40, e.g., by retrieving from its memory the values of the parameters related to measurement configuration used by the wireless device 40 most frequently in the past, e.g., certain number of times in the past, over a certain time period in the past, etc.

• The wireless device 40 may determine full or partial configuration related to the measurement procedure autonomously based on one or more criteria. The wireless device 40 may also be configured by the network node 20 with one or more pre- defined criteria to be used by the wireless device 40 for autonomous determining the measurement configuration.

• The wireless device 40 may also obtain the full or partial configuration of

measurement procedure directly from one or more other wireless devices if the wireless devices are capable of device to device (D2D) operation. D2D operation is also interchangeably called D2D transmission and/or reception, ProSe operation, ProSe discovery, ProSe communication, etc.

• The wireless device 40 may additionally obtain full or partial configuration of measurement procedure over the user plane by retrieving it from a server which may be under operator control or third party control.

The wireless device 40, upon obtaining the configuration, uses at least the obtained information to adapt its measurement procedure to perform one or more measurements on cells to be measured. The measurements are performed by the wireless device 40 using the obtained measurement configuration also referred to as an adapted measurement procedure. The wireless device 40, after performing the measurements, uses the measurement results for one or more tasks or operations. Examples of such tasks include but are not limited to:

• Performing cell change e.g. cell selection, cell reselection, etc.;

• Transmitting the measurement results to the network node 20; and

• Using the measurement results for determining its position.

In order to perform measurements with good quality (e.g., accuracy below +/- x dB or to meet the requirements), wireless device 40 can adapt its measurement procedure. The wireless device 40 may, based on, e.g., estimated channel quality (e.g., S R/SINR level), adapt the values of some of the parameters used to carry out the measurements. In one example, the adaptation may include the wireless device 40 switching from measuring CRS signals to measuring synchronization signals at a certain point based on estimated channel quality. In another example, the wireless device 40 may switch from measuring synchronization signals to measuring CRS. In a third example, the adaptation may include the wireless device 40 switching from CRS/synchronization signals to both CRS and synchronization signals, etc.

The wireless device 40 may further adapt one or more additional parameters used to perform the measurements based on the signal quality of the measured cell. Examples of additional parameters to be adapted include the LI measurement period, the number of consecutive subframes, the types of averaging used for the

measurement, etc.

As an example, the wireless device 40 may adapt one or more parameters in accordance with the principles summarized in Table 2. The adaptation of the measurement procedure may be realized by the wireless device 40 based on one or more of:

• One or more pre-defined rules, e.g., rules specified in the standard;

• wireless device 40 implementation-specific, i.e., decided by the wireless device 40 itself; and

• One or more parameters or indications received from the network node 20. In one example, the parameters shown in Table 2 can be pre-defined. In another example, one or more parameters (e.g., number of consecutive subframes, type of reference signals) in the table may be configured by the network node 20 while the remaining ones are autonomously determined by the wireless device 40 or are pre-defined.

One important aim of the adaptation of the measurement procedure is to comply and meet one or more pre-defined wireless device 40 requirements related to wireless device 40 measurement requirements, RRM requirements, mobility requirements, positioning measurement requirements etc. Examples of wireless device requirements related to wireless device measurements are measurement time, measurement reporting time or delay, measurement accuracy (e.g., RSRP/RSRQ accuracy), number of cells to be measured over the measurement time etc. Examples of measurement time are LI measurement period, cell identification time or cell search delay, CGI acquisition delay, etc.

As discussed in the preceding sections, the wireless device 40 may obtain the configuration related to measurement procedure based on any combination of:

• autonomously;

• based on received configuration from network node 20 and/or other wireless

devices; and

· one or more predefined or preconfigured rules.

• One embodiment can be summarized as follows:

• Obtaining information related to measurement configuration, wherein the

configuration contains information on what signals to measure on, what symbols to measure on, when to perform the measurement, what measurement filtering coefficient to use, etc.

• Obtaining information on channel state information of the cell to be measured.

Examples of such information are estimated S R, SINR, CQI, RSRP, RSRQ, CRS, CRS Es/Iot, SCH Es/Iot. The term, obtaining, here may imply that the wireless device 40 autonomously estimates the channel quality of the target cell, or wireless device 40 receives such information from other nodes (e.g. other network node, other devices, relays, etc.).

• Comparing the obtained information to a set of predefined values; • Based on compared information, the wireless device 40 can decide whether to adapt its measurement procedure.

In one example, in a case where wireless device 40 has obtained configuration related to measurement procedure, the wireless device 40 may choose to adapt its procedure accordingly. In another example, it is assumed that wireless device 40 has not obtained/acquired any measurement configuration for other nodes. In this case, wireless device 40 may choose to adapt its measurement configuration procedure based on the comparison result in the previous step.

In a third example, it is assumed that wireless device 40 has obtained measurement configuration from other nodes, and wireless device 40 has obtained information related to channel quality information on the cell to be measured. In this case, wireless device 40 may choose to adapt its measurement procedure based on any combination of obtained measurement configuration and wireless device 40 estimated information on channel quality of target cell.

The wireless device 40 may also send information about pre-defined rule, configured/obtained rule and/or autonomously determined rule to other nodes and other wireless devices (e.g., D2D wireless devices) in its proximity. The comparison step above may include numerous configuration thresholds which can in some cases also be pre-defined.

One embodiment enables the wireless device 40 to derive a configuration related to measurement procedure which reflects the current channel quality. The configuration can be derived based on estimated channel state information of the cell to be measured. If the target cell is already known to the wireless device 40, e.g., the wireless device 40 may have already identified that cell, or the wireless device 40 may have already performed some measurements on that cell, then the wireless device 40 may use such historical information (e.g., estimated SINR, reported CQI, RSRP, etc. of that cell) to derive the configuration.

An advantage of this embodiment is that the wireless device 40 is able to dynamically adapt the values used to perform the measurement in order to meet the measurement requirements. The measurement requirements in this case can be accuracy requirements (i.e., the uncertainty of measurement) or the delay of a measurement. The adaptation in the wireless device 40 can be as follows: • when the estimated channel state information is high (e.g., SINR> threshold Tl), the configuration may enable the wireless device 40 to perform the measurement using existing method, i.e., using CRS signals. The value of Tl could be predefined or a configurable parameter.

· When the reported channel state information is low (e.g., SINR < Tl), the

configuration may enable the wireless device 40 to perform measurement using an adaptive method, i.e., using synchronization signals (e.g., B-PSS, NB-SSS).

• When the reported channel state information is very low, (e.g., SINR <T0,

wherein T0<T1), the configuration may enable the wireless device 40 to perform measurement using an adaptive method, i.e., using both CRS and synchronization signals (e.g., NB-PSS, NB-SSS). The value of TO could be predefined or a configurable parameter.

The measurement performance using only CRS signals may be worse compared to, e.g., NB-SSS signals. This is because the density of NB-SSS can be higher, i.e., the number of resource elements containing the NB-SSS is much higher than the number of resource elements containing CRS. Thus, the measurement performance using NB-SSS may result in improved accuracy of the measurement. Likewise, when the measurement is performed over both CRS and synchronization signals the accuracy can be further improved since even more number of resource elements are used for measurement. Since the measurement accuracy becomes a function of type of signals used for measurement, network node 20 may use this information to derive the measurement configuration which is later communicated to the wireless device 40.

• When the reported channel state information is high (e.g., SINR> threshold Tl), the configuration may enable the wireless device 40 to perform the measurement using filtering coefficient 1. Filtering coefficient 1 may correspond to a LI measurement period of 400 ms. The value of Tl can be predefined or a configurable parameter.

• When the reported channel state information is low (e.g., SINR < Tl), the

configuration may enable the wireless device 40 to perform measurement using filtering coefficient 2. Filtering coefficient 2 may correspond to a LI measurement period of 800 ms. • When the reported channel state information is very low, (e.g., SINR <T0, wherein T0<T1), the configuration may enable the wireless device 40 to perform measurement using filtering coefficient 3. Filtering coefficient 3 may correspond to a LI measurement period of 1600 ms. The value of TO could be predefined or a configurable parameter.

Another way to improve the measurement performance is by adapting the number of consecutive subframes to be used for measurement. The adaptation may be determined based on one or more of: the wireless device estimated channel state information (CSI), radio conditions, S R or SINR of the measured cell, etc.

The measurement configuration may further include information on whether to use coherent or non-coherent averaging to perform the measurement. One example of how the measurement configuration is autonomously derived by the wireless device 40 is shown in Table 2 below:

Table 2: Example of adaptive measurement configuration autonomously derived by wireless device 40

Es/Iot [dB] Type of Filtering Number of Type of signals to coefficient or consecutive averaging measure on measurement subframes to (coherent- or period be used for non-coherent measurement averaging)

Es/Iot≥-6 First type of 200 ms 1 Coherently dB reference within signal sample and non- coherently over the samples

-10 < Second type 400 ms 2 Coherently Es/Iot < -6 of reference within signal sample and non- coherently over the samples -15 < Second type 800 ms 2 Coherently Es/Iot < - of reference within 10 signal sample and non- coherently over the samples

-20 < Combination 1600 ms 4 Coherently

Es/Iot < - of first and within

15 second type sample and non- coherently over the samples

This embodiment is related to a transmitting network node 20 transmitting or signaling information to other nodes, the information being related to the

measurement procedure used or expected to be used by the wireless device 40 based on at least the channel state information (e.g., SINR, SNR, CQI, RSRP, RSRQ, RS- SI R, etc.). Examples of other nodes which may receive the information are radio network nodes (e.g., eNode B, base station, access point, etc.), ProSe wireless devices, ProSe relay wireless devices, IoT devices, NB-IOT devices, core network nodes, positioning nodes or any other node used for dedicated services such as self- organizing network (SON) nodes.

There are advantages to sharing the derived measurement configuration with other nodes. One advantage is that the same or partial information may be applicable to other nodes in the network, and in that case the partial information can be reused. This way, the measurements can be improved in large scale.

A second advantage is that deriving the measurement configuration, which can be quite complex sometimes, can be done in one place and only once, and then signaled to other nodes in the network. This way, processing in the different nodes in the network can be reduced. The network node 20 receiving this information may also adapt the parameters that are signaled by the network node 20 to the wireless device 40 as part of the measurement configuration.

For example, the network node 20 may configure the wireless device 40 to measure both CRS and synchronization signals when the reported channel state information (e.g., SINR) of the measured cell is poor. Alternatively, the network node 20 may configure the wireless device 40 with a larger value of the time domain filtering coefficient. The longer filtering coefficient will enable a longer measurement time which may be necessary when the channel quality is bad. In other cases, when the wireless device 40 has a good channel in the measured cell (e.g., high SINR), the network node 20 may configure the wireless device 40 to only measure CRS signals, or only synchronization signals. When the wireless device 40 measures both CRS and synchronization signals, measurement accuracy may improve. This may, for example, result in RSRP accuracy of +/- 1 dB instead of +/- 3 dB if the wireless device 40 has only measured CRS or a synchronization signal.

Some embodiments include:

Embodiment 1. A method in or for a network node serving a wireless device, the method including:

determining based on criteria, reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell; and

configuring the wireless device with the determined RS type configuration information to enable the wireless device to perform at least one radio measurement on at least one cell.

Embodiment 2. A method in or for a wireless device, the method comprising: receiving from the network node at least reference signal, RS, type

configuration information, the information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell;

determining, based on the received RS type configuration information, a type of RS to be used by the wireless device for performing one or more radio

measurements in at least one cell; and performing at least one measurement on the determined RS type on at least one cell.

Embodiment 3. A method in or for a wireless device served in a first cell by a network node, the method comprising:

receiving from the network node an indication of at least two of the following types of reference signals, RS:

a first type of reference signal that can be used by the wireless device for performing one or more radio measurements on one or more cells;

a second type of reference signal that can be used by the wireless device for performing one or more radio measurements on one or more cells; and a combination of at least the first and the second types of reference signal that can be used by the wireless device for performing one or more radio measurements on one or more cells;

selecting based on one or more criteria one of the received RS types; and using the selected received RS type for performing at least one radio measurement on at least one cell.

Embodiment 4. A wireless device, comprising:

a processor configured to:

receive from a network node an indication of at least two of the following types of reference signals, RS:

a first type of reference signal that can be used by the wireless device for performing one or more radio measurements on one or more cells;

a second type of reference signal that can be used by the wireless device for performing one or more radio measurements on one or more cells; and

a combination of at least the first and the second types of reference signal that can be used by the wireless device for performing one or more radio measurements on one or more cells;

select, based on one or more criteria, one of the received RS types and to use the received RS type information for performing at least one radio measurement on at least one cell.

Embodiment 5. A network node, comprising:

processing circuitry including a memory and a processor: the memory configured to store reference signal , RS, type configuration information;

the processor configured to:

determine RS type configuration information indicating one of whether the wireless device is to use only one type reference signal for performing at least one radio measurement on at least one cell and whether the wireless device is to use a combination of two or more types of reference signals for performing at least one radio measurement on at least one cell; and

configure the wireless device with the determined RS type configuration information to enable the wireless device to perform at least one radio measurement on at least one cell.

Embodiment 6. A network node, comprising:

a memory module configured to store reference signal, RS, type configuration information;

an RS type configuration determination module configured to determine RS type configuration information indicating one of whether the wireless device is to use only one type reference signal for performing at least one radio measurement on at least one cell and whether the wireless device is to use a combination of two or more types of reference signals for performing at least one radio measurement on at least one cell.

Embodiment 7. A wireless device, comprising:

processing circuitry including a memory and a processor:

the memory configured to store reference signal, RS, type configuration information; and

the processor configured to select based on one or more criteria one of the received RS type configurations and to use the received RS type information for performing at least one radio measurement on at least one cell.

Embodiment 8. A wireless device, comprising:

a memory module configured to store reference signal, RS, type configuration information;

a selection module configured to select based on one or more criteria one of the received RS type configurations; and a measurement module configured to use the received RS type information for performing at least one radio measurement on at least one cell.

Embodiment 9. A network node serving a wireless device, the network node including:

a processor configured to:

determine, based on criteria, reference signal (RS) type configuration information indicating one of (a) whether the wireless device is to use only one type reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell; and

configure the wireless device with the determined RS type configuration information to enable the wireless device to perform at least one radio measurement on at least one cell.

Thus, some embodiments advantageously provide a method, network node and wireless device for configuring measurements of narrowband Internet of Things. In some embodiments, a method in a network node 20 serving a wireless device 40 includes determining reference signal, RS, type configuration information indicating one of (a) whether the wireless device 40 is to use only one type reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell (block S124). The determining of RS type configuration information is based on criteria that includes a signal level. The method also includes sending the RS type configuration information to the wireless device 40 to configure the wireless device 40 to perform at least one radio measurement on at least one cell based on the RS type configuration

information (block S126).

In some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of reference signal employed depends on a signal quality measurement.

In some embodiments, a network node 20 for adapting measurement for narrowband Internet of Things is provided. In some embodiments, processing circuitry 22 is configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The processing circuitry 22 is also configured to send the RS type configuration information to the wireless device 40 to configure the wireless device 40 to perform at least one radio measurement on at least one cell based on the RS type configuration information.

In some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of RS employed depends on a signal quality measurement.

In some embodiments, a network node 20 for serving a wireless device 40 includes an RS type configuration information determination module 31 is configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level, a transmitter module 36 configured to send the RS type configuration information to the wireless device 40 to configure the wireless device 40 to perform at least one radio measurement on at least one cell based on the RS type configuration information.

In some embodiments, a method in a wireless device 40 includes determining a reference signal, RS, type configuration information indicating one of (a) whether the wireless device 40 is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell (S128). The determining of RS type configuration information is based on criteria that includes a signal level. The method also includes performing at least one measurement on at least one cell based on the determined RS type configuration information (S130).

In some embodiments, the determined RS type configuration information is received from a network node 20. In some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific to one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of reference signal employed depends on a signal quality measurement.

In some embodiments, a wireless device 40 includes processing circuitry 42 configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device 40 is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The processing circuitry 42 is further configured to perform at least one measurement on at least one cell based on the determined RS type configuration information.

In some embodiments, the determined RS type configuration information is received from a network node 20. In some embodiments, the signal level is one of signal quality, signal strength and path loss with respect to the at least one cell. In some embodiments, a type of reference signal is one of a cell specific reference signal, CRS, a demodulation reference signal, DMRS, a channel state indication reference signal, CRS-RS, a primary synchronization signal, and a secondary synchronization signal. In some embodiments, the at least one measurement is based on estimated channel quality of a cell to be measured. In some embodiments, RS type configuration information is specific for one of a particular cell, a group of cells, all cells on a same carrier frequency, all cells on all configured carrier frequencies, and a particular type of measurement. In some embodiments, the type of reference signal employed depends on a signal quality measurement.

In some embodiments, a wireless device 40 includes an RS type configuration information determination module 51 configured to determine reference signal, RS, type configuration information indicating one of (a) whether the wireless device 40 is to use only one type of reference signal for performing at least one radio measurement on at least one cell, and (b) whether the wireless device 40 is to use a combination of at least two types of reference signals for performing at least one radio measurement on at least one cell. The determining of RS type configuration information is based on criteria that includes a signal level. The wireless device 40 also includes a measurement performance module 53 configured to perform at least one measurement on the determined RS type on at least one cell. In some embodiments, performing the radio measurement is based on a first type of reference signal when the signal level is equal to or larger than a threshold, and performing the radio measurement is based on a combination of at least two types of reference signals when the signal level than the threshold.

Abbreviation Explanation

BS Base Station

CRS Cell-specific Reference Signal

DL Downlink

DRX Discontinuous Reception

E-CID Enhanced CID

eNodeB evolved Node B

LTE Long-Term Evolution

MDT Minimization of Drive Tests

MSR Multi- Standard Radio

PCI Physical Cell Identity

RF Radio Frequency

RRC Radio Resource Control

RSRP Reference Signal Received Power

RSRQ Reference Signal Received Quality

RSSI Received Signal Strength Indicator

SINR Signal-to-Interference Ratio

SON Self-Optimized Network

UL Uplink

HO Handover

M2M machine to machine

MTC Machine type communication

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, and/or computer program product. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a "circuit" or "module." Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, (thereby creating a special purpose computer) a special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other

programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that

communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.