Technical Field

The present disclosure generally relates to a technique for sharing frequencies. More specifically, and without limitation, methods and devices are provided for verifying that coverage of a cellular network obeys exclusion zones for shared frequencies.

Background

All radio technologies including cellular radio access networks, e.g., GSM EDGE Radio Access Network (GERAN), UMTS Terrestrial Radio Access Network (UTRAN), E-UTRAN, etc., and short-range radio access technologies, e.g., WiFi, require spectrum resources to establish wireless communications (including mobile communications). Spectrum is fundamental to the success of wireless communi ^¬ cations, and mobile operators rely on an exclusive license as a key asset for ensuring predictable service.

The range of spectrum that is made available for wireless communications has increased over years. Despite the increase, the demand for further spectrum still exceeds the available exclusive spectrum. The scarcity of spectrum has created a need for methods to assign spectrum resources and to share licensed spectrum with other applications.

One framework to address the sharing of spectrum is Licensed Shared Access (LSA), which is also referred to as Authorized Shared Access (ASA) or Spectrum Access System (SAS). Within the LSA framework, it is feasible for an operator or other licensee to use spectrum that is partly utilized already for another application. The entity or service operator that operates the other application is referred to as an incumbent. E.g., the incumbent operates applications such as radar, fixed- satellite system or fixed-satellite service (FSS), or similar. Alternatively or in addition, the other application includes an ad hoc application such as Programme Making and Special Events (PMSE).

A basic framework to handle sharing of spectrum and interference between applications has been defined by the Internet Engineering Task Force (IETF) in a Protocol to Access White-Space (PAWS) databases. The framework of LSA extends beyond the capabilities of the IETF PAWS.

Standardization of an LSA framework and related interfaces are ongoing in the European Telecommunications Standards Institute (ETSI), e.g., in the Recon- figurable Radio Systems (RRS) group within the ETSI.

In parallel, the Federal Communications Commission (FCC) in USA is defining a regulatory framework for use of 3.5 GHz spectrum as a step in recommendations of the President's Council of Advisors on Science and Technology (PCAST) to identify 1000 MHz bandwidth of federal spectrum to create shared-use spectrum superhighways. Details of the FCC framework are described in the document "Amendment of the Commission's Rules with Regard to Commercial Operations in the 3550-3650 MHz Band", FCC 14-49, GN Docket No. 12-354.

In the framework defined by the FCC, the use of SAS is required. The SAS is not only required to ensure that the spectrum licensees use a correct set of spectrum resources, e.g., in terms of frequency domain, geographical domain and timing domain. The SAS is also required to monitor the utilization of spectrum resources by licensees.

If there is a protection zone (that is also referred to as a geographical area, exclusion zone or protection area) in which a user and/or an operator may not be allowed to transmit radio signals on some of the frequencies the operator is (e.g., elsewhere) allowed to use, the operator is required to plan deployment of the radio access network such that the protection zone is withheld. The radio access network is typically deployed using a cell-planning tool. The cell planning includes setting sites, output power levels, antenna directions, tilt, etc., in order to provide the required coverage. The protection zones may be accounted for in the decision process to secure that the coverage does not expand into those protected areas, which puts limitations on site locations, output power levels, antenna directions, tilt, etc.

The conventional deployment setting may, however, be too restrictive, e.g., due to uncertainties as to area topography, channel attenuation or multi-path propagation. Summary

Accordingly, there is a need for a technique that supports a more accurate radio access deployment in at least some scenarios.

As to one aspect, a method of verifying that coverage of a cellular network obeys exclusion zones for shared frequencies is provided. The method comprises or triggers the step of receiving, by the cellular network, one or more reports from one or more user equipments (UEs) indicative of radio environment measurements and a location of the measurements; and the step of verifying that the coverage is within borders set for the shared frequencies based on the one or more reports.

In at least some embodiments, the technique provides for an automatic verification of coverage and adjustment of base station radio parameters, e.g., if coverage is not yet correct. In same or other embodiments, the technique enables frequency- sharing entities to get signal strength measurements on relevant frequencies from more positions than from measurements performed by the base stations.

Alternatively or in addition, coverage infringements from other networks and/or technologies operating in the band can be detected.

The measurements may be performed by and/or in the reporting UE. The UE may be used to verify one or more exclusion zones and/or protection zones, e.g., according to an Authorized Spectrum Access (ASA), Licensed Shared Access (LSA) or Spectrum Access System (SAS). Furthermore, if one or more exclusion zones are overridden or larger than needed, the measurement data from the one or more UEs may be used to change the configuration in one or more corresponding base stations, e.g., such that the one or more exclusion zones are obeyed.

The borders may relate to the exclusion zones. The exclusion zones may relate to areas in which the one or more user equipments and/or the cellular network are not allowed to transmit radio signals on the shared frequencies.

The method may further comprise or trigger the step of sending a configuration message to the one or more user equipments. The configuration message may request the respective user equipment to perform the radio environment

measurements and/or to report the radio environment measurements. The radio environment measurements may include signal strength measurements and/or signal-to-noise measurements. The reported locations may include positions other than sites of base stations of the cellular network. The reported locations may include positions of the UEs.

The method may further comprise or trigger at least one of the step of adjusting radio parameters of one or more base stations of the cellular network, if the coverage is not correct; and the step of changing the configuration of one or more base stations of the cellular network such that the exclusion zones are obeyed.

The configuration parameters may relate to a base station site, an output power level, an antenna direction and/or an antenna tilt.

The step of changing may comprise or trigger at least one of the substep of performing cell planning based on predictive models; and the substep of setting radio configuration parameters of the one or more base stations. The method may further comprise or trigger the step of updating the predictive models used for the cell planning based on the one or more reports. The cell planning may account for the exclusion zones.

Alternatively or in addition, the method may further comprise or trigger the step of handling real-time interference issues based on the reports.

Furthermore, the method may comprise or trigger the step of alerting an operator of the cellular network that action is needed to comply with regulatory requirements.

The cellular network may provide radio access using the shared frequencies. The radio access may be provided according to ASA, LSA and/or SAS at least for the shared frequencies.

The radio environment measurements may be performed on the shared frequencies or adjacent frequency bands. The step of verifying may include detecting internetwork coverage infringements and/or inter-radio access technology coverage infringements on the shared frequencies.

The cellular network may provide a Citizens Broadband Radio Service (CBRS). The base stations may be CBRS devices. The shared frequencies may include or relate to a 3.5 GHz band. The bandwidth of the shared frequencies may be 100 MHz or more. As to another aspect, a method of verifying that coverage of a cellular network obeys exclusion zones for shared frequencies is provided. The method comprises or triggers the step of performing radio environment measurements on the shared frequencies for verifying that the coverage is within borders set for the shared frequencies; and the step of sending, to the cellular network, one or more reports from a user equipment indicative of the radio environment measurements and a location of the measurements.

As to a further aspect, a computer program product is provided. The computer program product comprises program code portions for performing any one of the steps of the method aspects disclosed herein when the computer program product is executed by one or more computing devices. The computer program product may be stored on a computer-readable recording medium. The computer program product may also be provided for download via a data network, e.g., the cellular network and/or the Internet.

As to one hardware aspect, a device for verifying that coverage of a cellular network obeys exclusion zones for shared frequencies is provided. The device is configured to perform or trigger the step of receiving, by the cellular network, one or more reports from one or more user equipments indicative of radio environment measurements and a location of the measurements; and the step of verifying that the coverage is within borders set for the shared frequencies based on the one or more reports.

As to a further hardware aspect, a node of a cellular network comprising the device is provided.

The node may be, or may be implemented at, a base station (BS), an entity for Operations, Administration and Management (OAM or O&M) or a separate entity for shared access.

As to another hardware aspect, a device for verifying that coverage of a cellular network obeys exclusion zones for shared frequencies is provided. The device is configured to perform or trigger the step of performing radio environment

measurements on the shared frequencies for verifying that the coverage is within borders set for the shared frequencies; and the step of sending, to the cellular network, one or more reports from a user equipment indicative of the radio environment measurements and a location of the measurements. As to a still further hardware aspect, a user equipment (UE) is provided. The UE comprises the device according to above another hardware aspect.

The UE may be a mobile terminal. The UE may be connected or connectable to the cellular telecommunications network.

The device according to any one of the hardware aspects may further include any feature disclosed in the context of the method aspects. Particularly, any one of the units, or a dedicated unit, may be adapted to perform one or more of the steps of any one of the method aspects.

Brief Description of the Drawings

Further details of embodiments of the technique are described with reference to the enclosed drawings, wherein:

Fig. 1 shows a schematic block diagram of a device for coverage verification implementable at a cellular network;

Fig. 2 shows a schematic block diagram of a device for coverage verification implementable at a user equipment;

Fig. 3 shows a flowchart for a method of coverage verification implementable by the device of Fig. 1;

Fig. 4 shows a flowchart for a method of coverage verification implementable by the device of Fig. 2;

Fig. 5 schematically illustrates an example structure for a request message;

Fig. 6 schematically illustrates an example structure for a response message;

Fig. 7 shows a schematic block diagram for a system comprising embodiments of the devices of Figs. 1 and 2;

Fig. 8 schematically illustrates an example signaling between the devices of

Figs. 1 and 2 when performing the methods of Figs. 3 and 4; Fig. 9 schematically illustrates an environment for deployment planning including more than one cellular network;

Fig. 10 schematically illustrates a cellular network for wireless communications;

and

Fig. 11 schematically illustrates an embodiment of a user equipment in wireless communication with the cellular network of Fig. 10.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as a specific network environment in order to provide a thorough understanding of the technique disclosed herein. It will be apparent to one skilled in the art that the technique may be practiced in other embodiments that depart from these specific details. Moreover, while the following embodiments are primarily described for Long Term Evolution (LTE) and 5G implementations, it is readily apparent that the technique described herein may also be implemented in any other wireless communication network, including a Wireless Local Area Network (WLAN) according to the standard family IEEE 802.11 (e.g., IEEE 802.11a, g, n or ac; also referred to as Wi-Fi) and/or a Worldwide Interoperability for Microwave Access (WiMAX) according to the standard family IEEE 802.16.

Moreover, those skilled in the art will appreciate that the services, functions, steps and units explained herein may be implemented using software functioning in conjunction with a programmed microprocessor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP) or a general purpose computer, e.g., including an Advanced RISC Machine (ARM). It will also be appreciated that, while the following embodiments are primarily described in context with methods and devices, the invention may also be embodied in a computer program product as well as in a system comprising a computer processor and memory coupled to the processor, wherein the memory is encoded with one or more programs that may perform the services, functions, steps and implement the units disclosed herein.

Fig. 1 shows a schematic block diagram of a device 100 for verifying that coverage of a cellular network obeys exclusion zones. Frequencies are shared between the cellular network and other applications according to the exclusion zones. The device 100 comprises a receiving unit 102 for receiving measurement reports. The reports are indicative of local measurements as to the usage of the shared frequencies and a location of the measurements. A verifying unit 104 assesses whether the coverage obeys the exclusion zone based on the reports.

The device 100 is implemented, e.g., centralized or in a distributed manner, at one or more nodes of the cellular network.

Fig. 2 shows a schematic block diagram of a device 200 for verifying that coverage of a cellular network obeys exclusion zones. Frequencies are shared between the cellular network and other applications according to the exclusion zones.

The device 200 comprises a performing unit 202 for performing local measurement as to the usage of the shared frequencies. A sending unit 204 sends reports indicative of the local measurements and a location of the measurements to the cellular network.

The device 200 is implemented in a user equipment (UE). The UE is wirelessly connected or connectable to the cellular network or another radio access network.

Fig. 3 shows a flowchart for a method 300 of verifying that coverage of a cellular network obeys exclusion zones for shared frequencies. In a step 302, the cellular network receives one or more reports from one or more user equipments (UEs). The reports are indicative of radio environment measurements and a location of the measurements. A step 304 verifies that the coverage is within borders set for the shared frequencies based on the one or more reports.

The method 300 is performed by the device 100. The steps 302 and 304 are performed or triggered by the units 102 and 104, respectively.

Fig. 4 shows a flowchart for a method 400 of verifying that coverage of a cellular network obeys exclusion zones for shared frequencies. In a step 402, radio environment measurements are performed on the shared frequencies for verifying that the coverage is within borders set for the shared frequencies. In a step 404, one or more reports are sent from a user equipment (UE) to the cellular network. The reports are indicative of the radio environment measurements and a location of the

measurements. The method 400 is performed by the device 200. The steps 402 and 404 are performed or triggered by the units 202 and 204, respectively.

The existing Protocol to Access White-Space (PAWS) databases of the Internet Engineering Task Force (IETF) defines a protocol that enables a TVWS (TV White Space) device to access available spectrum via an Available Spectrum Query procedure. Frequencies used for TV broadcasting can in addition be used by the TVWS devices. A procedure for using the shared frequencies is initiated by a message, e.g. an AVAIL_SPECTRUM_REQ message, from the TVWS device to a database.

The request message includes a geo-location of the TVWS device and/or parameters such as device identifier, capabilities and characteristics, e.g., as defined by a rules set. The request message is sent to a spectrum database that maintains an updated view of available spectrum resources.

An example format of a request message 500 is schematically illustrated in Fig. 5. The request message 500 specifies the geo-location at reference sign 502.

If the correct information is provided, the database may respond with a response message, e.g., an AVAIL_SPECTRUM_RESP message 600 schematically illustrated in Fig. 6. The response message 600 includes a timestamp 602. The response message 600 includes one or more SpectrumSpec elements, one for each rules set supported at the location 502 specified in the corresponding AVAIL_SPECTRUM_REQ request message 500.

Embodiments are using measurements performed in one or more UEs to verify exclusion zones or protection zones according to Authorized Spectrum Access (ASA), Licensed Shared Access (LSA) or Spectrum Access System (SAS).

Furthermore, if the exclusion zones are overridden or larger than needed, the measurement data from the one or more UEs can be used for changing the configuration in one or more bases stations such that the exclusion zones are obeyed. Setting the radio configuration parameters of the one or more bases stations, to ensure a certain geographical coverage, is based on prediction models in cell planning tools.

Regarding the sharing of the 3.5 GHz band in USA, the document FCC 14-49A1 mentions (p. 20, item 66) that "[s]ome commenters suggested that, to enable the SAS to tune or update its predictive models and also address real time interference issues, CBSDs should be required to provide the SAS with signal level measurements in their band or other adjacent frequency channels as requested by SAS." Utilizing radio measurements from the base stations, also called Citizens Broadband Radio Service Devices (CBSDs), may provide some enhancements in predicting coverage and interference levels. However, prediction models together with measurements from base stations cannot provide knowledge of the actual coverage and signal levels on other locations than the base station sites.

Thus, the network deployment may have to exclude areas larger than needed (i.e., larger than the required exclusion zones) in order to be on the safe side. Measurements from one or more own CBSDs cannot measure the actual signal level at the border of the own cell. Furthermore, one or more own CBSDs cannot measure an interference level created by another usage in an adjacent area and/or an adjacent frequency.

The technique allows providing for an automatic verification of coverage and adjustment of base station radio parameters if coverage is not correct.

The technique also allows enabling frequency-sharing entities, e.g., the device 100, to get signal strength measurements on relevant frequencies from more positions than the measurements performed in the base stations. Coverage infringements from another network and/or other technologies operating in the band can be detected.

Block diagrams 700 for embodiments of the devices 100 and 200 performing the methods 300 and 400, respectively, are schematically illustrated in Fig. 7.

According to a first aspect of embodiments, a method 400 in a UE is provided. The UE receives a configuration message 702 from the network or at least one node of the network. In response to the received configuration message 702, the UE sends environment measurements 704 also comprising information of the location where the measurements were taken.

According to a second aspect of embodiments, a method 300 in one or more network nodes is provided. The network node sends a configuration message 702 to the UE to request the UE to send environment measurements 704. The network node then receives the environment measurements 704 also comprising

information of the location where the measurements were taken.

Based on the reported environment measurements 704, the one or more network nodes automatically adjust its or their parameters to ensure compliance with the required exclusion zones and/or protection zones, or to alert a network operator that action is needed to comply with regulatory requirements.

According to a third aspect of embodiments, a UE is provided. The UE comprises processing means 202 adapted to receive a configuration message 702 from the network. In response to the received configuration message, the UE is configured to send environment measurements 704 also comprising information of the location where the measurements were taken.

The processing means of the UE comprise a processor and a memory, said memory containing instructions executable by said processor.

According to a fourth aspect of embodiments, a network node is provided. The network node comprises processing means 104 adapted to send a configuration message 702 to the UE to request the UE to send environment measurements 704. Receiving means 102 are adapted to receive the environment measurements 704, also comprising information of the location where the measurements were taken. The processing means 104 are further adapted to automatically adjust, based on the reported environment measurements, its parameters to ensure compliance with the required exclusion zones and/or protection zones, or to alert a network operator that action is needed to comply with regulatory requirements.

The processing means 104 of the network node comprise a processor and a memory, said memory containing instructions executable by said processor.

Furthermore, the network node comprises a radio transceiver 102 for

communicating with the UE. The UE comprises a radio transceiver 204 for communicating (e.g., sending and/or receiving the messages described herein) with the network node. The means 102 and 204 for communication are illustrated by input and output units in Fig. 7.

The configuration message 702 indicates which type of measurements should be performed, how often, etc. A UE may, for other reasons, already be doing some of the measurements. The measurements and/or the measurement type may also differ depending on an operating mode of the UE. The operating mode may include an idle state or a connected state.

Measurements can be reported continuously or regularly. Moreover, results of the measurements can be stored and/or reported when it is possible to report, e.g., if a UE moves from idle state to connected state. The measurements that have been taken in the idle state may be reported when the UE enters the connected state.

The network node can be an ASA node, LSA node or SAS node.

The types of the environment measurements include received signal level, signal strength and signal-to-noise ratio (SNR). Measurements can be obtained on a serving cell and/or on other frequency channels.

By way of example, if the cellular network, or a network adjacent to the cellular network, provides access according to Long Term Evolution (LTE), the

measurements may include a Reference Signal Received Power (RSRP) and/or a Reference Signal Received Quality (RSRQ).

If Wideband Code Division Multiple Access (W-CDMA) is provided, the

measurements may include a Received Signal Code Power (RSCP) and/or Energy per Chip / Noise Spectral Density (E _c /N ₀ ).

If access according to the Global System for Mobile Communications (GSM) is provided, the measurements may include a Received Signal Strength Indicator (RSSI) and/or a Received Signal Level (RXLev).

If access according to CDMA2000 is provided, the measurements may include a CDMA2000 Pilot Strength and/or a Pilot Pseudo-Noise (PN) Phase. If access according to WiFi (IEEE 802.11) is provided, the measurements may include a Received Channel Power Indicator (RCPI), a Received Signal-to-Noise Indicator (RSNI), an Average Noise Power Indicator (ANPI), a Received Power Indicator (RPI), a Channel Load and/or a Noise Histogram.

To verify, detect and/or control that the coverage is within the borders set for the frequency sharing, radio environment measurements 704 from UEs, including the location where the measurements were taken, is obtained by the network in the step 302. Based on the reported measurements 704, the network can automatically adjust its parameters to ensure compliance with the required exclusion zones and/or protection zones, or alert the network operator that action is needed to comply with regulatory requirements.

The UE can also measure other frequencies, e.g., frequencies belonging to other licensees or users. Together with the UE position, this data may be utilized by controlling entities responsible for handling the sharing, such as SAS, to increase the number of geographical positions where measurement data is available.

The data from UEs can then be used to enhance prediction models and/or verify coverage and conformance to the exclusion zones and/or the protection zones. Thus, the received reports enable better sharing properties and increasing spectrum efficiency.

The network configures UEs to measure the local radio environment by, e.g., using the Minimization of Drive Tests (MDT) functionality defined in 3GPP for UMTS and LTE or similar techniques for other radio technologies. The MDT functionality comprises functionality for configuration and reporting of the measured radio environment. A specification of MDT for LTE networks is provided by document 3GPP TS 37.320, V12.2.0.

Based on the knowledge of the position at which the measurements were taken and the measurement specific details (e.g., signal strength levels, etc.), the network can determine if the coverage infringes the protection zones or if the margins are too large.

If the coverage extends into the protected zone, the network decides that it needs to change the configuration data. It can then, per affected cell, decide to not use the cell and/or lower (or increase) the output power and/or increase (or decrease) the tilt of the one or more antennas, and/or to change one or more directions of the one or more antennas. The output power level may be adjusted unequally on the frequency carrier. Alternatively or in addition, the frequency channel bandwidth is limited. E.g., the bandwidth is limited by avoiding usage of certain resource blocks in, e.g., an LTE carrier.

The deployment decision can be taken in an eNodeB (eNB) and/or a Radio Network Controller (RNC), an access controller, an access point, a base station, an

Operation and Maintenance (O&M) functionality, or a separate ASA/LSA/SAS entity or node. It is also possible that, if the protection zone is changing, the MDT mechanism or a similar mechanism is used to determine the new required settings.

Thus, a new manual cell planning may not be needed to accomplish the settings.

Fig. 8 schematically illustrates signaling 800 between embodiments of the devices 100 and 200. The device 200 is implemented at a UE. The device 100 is implemented at the base station (which alternative is shown at reference sign 100-1), the O&M functionality (which alternative is shown at reference sign 100-2) or the ASA/LSA/SAS functionality (which alternative is shown at reference sign 100-3).

When there is a need to verify coverage, the UEs are configured by, e.g., using the 3GPP RAN MDT functionality. The measurement reports 704 from the UEs are used to verify frequency channels that can be "heard" and their respective signal strength and quality. If any of the levels are not in accordance with the rules, measures are triggered or decided, and cell/radio configurations for the enhanced Node B (eNB in LTE), Node B (NB in UMTS) or Base Transceiver System (BTS in GSM) are changed and/or updated. The user devices, such as UEs, may be further informed about cell changes by any required configuration messages, e.g., system configuration messages that may be broadcast and/or sent dedicated to devices.

Fig. 8 illustrates an example for a step 804 of sending a cell reconfiguration message 802 by the network. The UE receives the cell reconfiguration message 802 in a step 806.

The technique may also be implemented to detect coverage infringements from geographically adjacent networks or adjacent frequencies, e.g., by allowing the UE to measure all available frequency blocks in the (e.g., shared) band. The numbers of available measurement positions/samples are thus increased as compared to if measurements only from a serving operator are used. Coverage infringement from networks using other technologies can also be detected by signal strength measurements.

Radio measurements 704 can be sent to a controlling entity from other networks to be used in verification and decisions on radio configuration matters. Fig. 9 schematically illustrates an implementation 900 for two (or more) networks. The device 100 may be implemented in each of the networks. Alternatively or in addition, the device 100 is implemented in the controlling entity accessed by, or accessible to, each of the networks.

Measurement results 704 and/or 902 can be reported to the controlling entity. The controlling entity may be, or may be implemented at, an ASA/LSA/SAS node or management system, e.g., for further decisions. Reporting to the controlling entity may include forwarding the one or more reports 704 from the UE as the message 902, or processing (e.g., aggregating) the one or more reports 704 before sending the message 902.

An example environment for the cellular network is schematically illustrated at reference sign 1000 in Fig. 10. The network 1000 includes one or more nodes, which implement the device 100, e.g., in a distributed manner. Alternatively or in addition, the base stations, illustrated at reference sign 1002, comprise an embodiment of the device 100.

Fig. 11 schematically illustrates a UE 1100 comprising an embodiment of the device 200. The UE 1100 may be served by the network 1000, which case is illustrated in Fig. 10. Alternatively or in combination, at least some of the UEs 1100 performing the measurements are served by a radio access network or radio access technology other than the network or technology that is being measured.

As has become apparent from above description of embodiments, at least some embodiment ensure that a coverage area obeys exclusion zones, e.g., without the need for drive testing and manual updating of the base station radio configuration parameters. The coverage areas can be controlled more precisely. Shared frequencies can be utilized more intensively (e.g. in time and/or space).

Controlling entities of the frequency sharing can obtain signal level measurements on more positions than the base station sites, which can further increase verification of coverage and interference levels and may also be used to further enhance prediction models.

The interference levels in own-license areas and/or own-license frequency domains can be monitored and, possibly, adjusted to comply with the protection levels applied, e.g., by a controlling entity.

Many advantages of the present invention will be fully understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the units and devices without departing from the scope of the invention and/or without sacrificing all of its advantages. Since the invention can be varied in many ways, it will be recognized that the invention should be limited only by the scope of the following claims.