(CE) MODE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 62/717,713, filed August 10, 2018, entitled“Non-bandwidth-reduced Low

Complexity (non-BL) User Equipment (UE) in Coverage Enhancement (CE) Mode”, the contents of which are herein incorporated by reference in their entirety.

FIELD

[0002] The present disclosure relates to long term evolution (LTE) communication systems, and in particular, to a method to enable channel state information (CSI) feedback based on channel state information reference signal (CSI-RS) for non bandwidth reduced low complexity (non-BL) user equipment (UE) in coverage enhancement (CE) mode.

BACKGROUND

[0003] Enhanced Machine Type Communication (eMTG) is a type of LTE-M network published by 3GPP in the Release 13 specification. eMTC is a low power wide area technology which supports internet of things (!oT) through lower device complexity and provides enhanced coverage, leveraging a mobile carriers existing LTE base stations. The enhanced/ improved coverage is expected to be needed by some user equipments with challenging coverage conditions, for example water/gas/electricity metering devices installed in basements. The coverage enhancement in eMTC is mainly achieved through repetition techniques. In ordinary 4G operations, each transmission spans just 1 millisecond, but for coverage enhancement, each transmission may be repeated tens, hundreds or even thousands of times to improve the chances of successful

transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Some examples of circuits, apparatuses and/or methods will be described in the following by way of example only. In this context, reference will be made to the accompanying Figures.

[0005] Fig. 1 illustrates a simplified block diagram of a long term evolution (LTE) communication system, according to one embodiment of the disclosure.

[0006] Fig. 2a illustrates an exemplary long term evolution (LTE) frame structure comprising a set of CSI-RS subframes, according to one embodiment of the disclosure.

[0007] Fig. 2b illustrates an exemplary long term evolution (LTE) frame structure comprising a set of CSI-RS subframes, according to another embodiment of the disclosure.

[0008] Fig. 3 illustrates an exemplary CSI-RS configuration for 8 CSI-RS ports, according to one embodiment of the disclosure.

[0009] Fig. 4 illustrates a block diagram of an apparatus employable at a Base Station (BS), eNodeB, gNodeB or other network device that can enable a user equipment (UE) in coverage enhancement (CE) mode associated therewith to determine channel state information (CSI) based on a repeated channel state information reference signal (CSI- RS), according to various aspects described herein.

[0010] Fig. 5 illustrates a block diagram of an apparatus employable at a UE or other network device (e.g., loT device) that facilitates to determine channel state information (CSI) based on a repeated channel state information reference signal (CSI-RS), according to various aspects described herein.

DETAILED DESCRIPTION

[0011] In one embodiment of the disclosure, an apparatus configured to be employed in an eNodeB associated with a long term evolution (LTE) communication system is disclosed. The apparatus comprises one or more processors configured to generate a set of repeated transmissions of a channel state information reference signal (CSI-RS), forming a repeated CSI-RS, to be provided to a user equipment (UE) in a set of CSI-RS subframes, respectively associated with an LTE frame structure, in order to enable the UE to determine channel state information (CSI) based on the repeated CSI-RS. The apparatus further comprises a radio frequency (RF) interface, configured to provide, to a radio frequency (RF) circuitry, the repeated CSI-RS, for subsequent transmission to the UE in the set of CSI-RS subframes.

[0012] In one embodiment of the disclosure, an apparatus configured to be employed in a user equipment (UE) in a coverage enhanced (CE) mode associated with a long term evolution (LTE) communication system is disclosed. The apparatus comprises one or more processors configured to monitor a repeated channel state information reference signal (CSI-RS) comprising a set of repeated transmissions of a CSI-RS from an eNodeB associated therewith, on a set of CSI-RS subframes, respectively associated with an LTE frame structure. In some embodiments, the one or more processors is further configured to process one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS, received from the eNodeB on one or more respective CSI-RS subframes of the set of CSI-RS subframes. In addition, in some embodiments, the one or more processors is configured to determine a channel state information (CSI) based on processing the one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS.

[0013] In one embodiment of the disclosure, a computer readable storage device storing executable instructions that, in response to execution, cause one or more processors of an eNodeB to perform operations is disclosed. In some embodiments, the operations comprises generating a set of repeated transmissions of a channel state information reference signal (CSI-RS), forming a repeated CSI-RS, to be provided to a user equipment (UE), in a set of CSI-RS subframes, respectively associated with an LTE frame structure, in order to enable the UE to determine channel state information (CSI) based on the repeated CSI-RS. In some embodiments, the operations further comprise providing the repeated CSI-RS, to a radio frequency (RF) circuitry, for subsequent transmission to the UE in the set of CSI-RS subframes.

[0014] The present disclosure will now be described with reference to the attached drawing figures, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures and devices are not necessarily drawn to scale. As utilized herein, terms“component,”“system,”“interface,”“circuit ” and the like are intended to refer to a computer-related entity, hardware, software (e.g., in execution), and/or firmware. For example, a component can be a processor (e.g., a microprocessor, a controller, or other processing device), a process running on a processor, a controller, an object, an executable, a program, a storage device, a computer, a tablet PC and/or a user equipment (e.g., mobile phone, etc.) with a processing device. By way of illustration, an application running on a server and the server can also be a component. One or more components can reside within a process, and a component can be localized on one computer and/or distributed between two or more computers. A set of elements or a set of other components can be described herein, in which the term“set” can be interpreted as“one or more.”

[0015] Further, these components can execute from various computer readable storage media having various data structures stored thereon such as with a module, for example. The components can communicate via local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network, such as, the Internet, a local area network, a wide area network, or similar network with other systems via the signal).

[0016] As another example, a component can be an apparatus with specific functionality provided by mechanical parts operated by electric or electronic circuitry, in which the electric or electronic circuitry can be operated by a software application or a firmware application executed by one or more processors. The one or more processors can be internal or external to the apparatus and can execute at least a part of the software or firmware application. As yet another example, a component can be an apparatus that provides specific functionality through electronic components without mechanical parts; the electronic components can include one or more processors therein to execute software and/or firmware that confer(s), at least in part, the functionality of the electronic components.

[0017] Use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term“or” is intended to mean an inclusive“or” rather than an exclusive“or”. That is, unless specified otherwise, or clear from conte8, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then“X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles“a” and“an” as used in this application and the appended claims should generally be construed to mean“one or more” unless specified otherwise or clear from conte8 to be directed to a singular form. Furthermore, to the event that the terms "including", "includes", "having", "has", "with", or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term

"comprising."

[0018] The following detailed description refers to the accompanying drawings. The same reference numbers may be used in different drawings to identify the same or similar elements. In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of various embodiments. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the various embodiments may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the various embodiments with unnecessary detail.

[0019] As indicated above, coverage enhancements (CEs) are required to support user equipments (UEs) deployed in remote areas with limited coverage. The CE is typically achieved through repeating the transmissions. In typical LTE operations, each transmission is carried in a 1 -millisecond span, but in coverage enhancement (CE) mode, each transmission is repeated tens, hundreds or even thousands of times improve the chances of a successful transmission. In some embodiments, the eMTC standard is further referred to as BL/CE, LTE-M1 , CAT-M1 etc. The eMTC specification has defined two CE modes: Mode A and Mode B. While CE Mode A provides moderate coverage enhancements and is mandatory for eMTC support, CE Mode B enables deep coverage but is optional. The eMTC standard, in Release-13, introduced a new class of UEs, referred to as bandwidth reduced low complexity coverage enhancement (BL/CE) UEs, in order to enable reduced power operation in poor coverage areas. In some embodiments, the term BL/CE UE is interchangeably used with the terms eMTC UEs, LTE-M1 UEs, CAT-M1 UEs etc.

[0020] In some embodiments, the BL/CE UEs operates on a bandwidth 1.08 MHz (i.e. , 6 PRB's) within an existing LTE deployment, or 1 .4 MHz in standalone

deployment. A narrowband is defined by 3GPP as six non-overlapping consecutive physical resource blocks in the frequency domain. An eMTC UE or BL/CE UE is only required to monitor a specific narrowband for upload and download (UL/DL)

transmissions as against the complete system bandwidth in traditional LTE. In some embodiments, LTE communication networks configured for eMTC operation supports BL/CE UEs. Further, the LTE communication networks configured for eMTC operation supports non-BL UEs. In some embodiments, the non-BL UE refers to a UE that is different from the BL/CE UEs and is configured to operate across the entire system bandwidth (e.g., the LTE bandwidth) or on a smaller system bandwidth (e.g., 6 PRBs,

25 PRBs, 100 PRBs etc.). In some embodiments, both BL/CE UEs and non-BL UEs are configured to operate in coverage enhancement (CE) modes.

[0021] In Rel-16 eMTC Wl description, one of the objectives is to specify coverage enhancement (CE) mode A and B improvements for non-bandwidth-reduced low complexity (non-BL) UEs. One of the considered improvements is to enable channel state information (CSI) feedback based on CSI reference signal (CSI-RS). The current Rel-15 specification of E-UTRAN does not support CSI feedback based on CSI-RS for non-BL UEs in CE mode. According to the Rel-15 specification, the CSI feedback is based on the cell reference signal (CRS). In particular, a BL/CE UE derives the channel measurements for computing CQI based on CRS. A BL/CE UE configured with CE ModeA or CE ModeB is not expected to be configured with non-zero transmission power CSI-RS in Rel-15. Further, a configuration of CSI-RS for non-BL UEs in CE mode is not supported in Rel-15. Therefore, current implementations do not support CSI feedback based on CSI-RS for both non-BL UEs in CE mode and BL/CE UEs.

[0022] Therefore, a system and a method to enable CSI feedback based on CSI-RS for UEs in CE mode is proposed herein. According to the current Evolved Universal Terrestrial Radio Access Network (E-UTRAN) technical specifications, the CSI-RS configurations do not assume repetition of CSI-RS. However, the repetition of signal over time is the main enabler of CE mode. Therefore, in order to enable CSI feedback based on CSI-RS for a user equipment (UE) in coverage enhancement (CE) mode, a configuration of CSI-RS repetition in time domain is proposed in this disclosure. In particular, an eNodeB configured to configure a channel state information reference signal (CSI-RS) to be repeatedly transmitted in a set of subframes associated with an LTE frame structure is proposed. In the embodiments described throughout the disclosure, the term LTE frame structure is utilized to refer to a time-frequency structure comprising a plurality of radio frames, and is not to be construed to a limited to a single radio frame. In some embodiments, configuring the CSI-RS to be repeated transmitted in time domain enables a UE in CE mode (e.g., non-BL UEs or BL/CE UEs) to determine CSI based on the repeated transmissions of the CSI-RS.

[0023] Fig. 1 illustrates a simplified block diagram of a long term evolution (LTE) communication system 100, according to one embodiment of the disclosure. In some embodiments, the LTE communication system 100 supports Enhanced Machine Type Communication (eMTC) and is referred to as LTE-M network in some embodiments.

The LTE communication system 100 comprises an eNodeB 102 and a user equipment (UE) 104. In other embodiments, however, the LTE communication system 100 can comprise a plurality of eNodeBs and UEs. In some embodiments, the eNodeB 102 is equivalent to a base station, an gNodeB in new radio (NR) systems etc. In some embodiments, the UE 104 may comprise a mobile phone, tablet computer, an internet of things (loT) device etc. The eNodeB 102 and the UE 104 are configured to communicate with one another over a communication medium (e.g., air). In some embodiments, the UE 104 comprise a non-bandwidth reduced low complexity (non-BL) UE configured to operate in coverage enhancement (CE) mode, as explained above. However, in other embodiments, the UE 104 may comprise a bandwidth reduced low complexity coverage enhancement (BL/CE) UEs.

[0024] In order to enable a UE in CE mode (e.g., the UE 104) to determine channel state information (CSI) based on channel state information reference signal (CSI-RS), in some embodiments, the eNodeB 102 is configured to configure the CSI-RS to be repeatedly transmitted in time domain, for example, in a set of CSI-RS subframes, respectively associated with an LTE frame structure. In particular, in some

embodiments, the eNodeB 102 is configured to generate a set of repeated transmissions of the CSI-RS, forming a repeated CSI-RS 106, to be provided to the UE 104, in the set of CSI-RS subframes, respectively associated with the LTE frame structure. In some embodiments, the eNodeB 102 is further configured to determine the set of CSI-RS subframes on which the set of repeated transmissions of the CSI-RS is to be transmitted to the UE 104. In some embodiments, the set of CSI-RS subframes on which the set of repeated transmission of the CSI-RS is transmitted may be determined at the eNodeB 102 based on channel conditions. Alternately, in other embodiments, the set of CSI-RS subframes may be predefined. In some embodiments, the eNodeB 102 is further configured to provide the repeated CSI-RS 106 to the UE 104 in the set of CSI-RS subframes.

[0025] In some embodiments, the LTE frame structure comprises bandwidth limited low complexity coverage enhanced (BL/CE) subframes and non-BL/CE subframes. In some embodiments, the BL/CE subframes comprises a plurality of subframes available to the BL/CE UEs for communication with the eNodeB 102. In other words, in some embodiments, the BL/CE UEs can communicate with the eNodeB 102 only via the

BL/CE subframes. However, the BL/CE subframes may be also available to non-BL/CE

UEs for communication with the eNodeB 102. Similarly, the non-BL/CE subframes comprises a plurality of subframes available to the non-BL/CE UEs for communication with the eNodeB 102. In some embodiments, the set of CSI-RS subframes comprises a set of consecutive BL/CE subframes (i.e., the subframes 202a and 202b), respectively, associated with the LTE frame structure, as shown in Fig. 2a. In such embodiments, the eNodeB 102 is configured to provide the repeated CSI-RS only in BL/CE subframes.

In particular, in Fig. 2a, the set of consecutive BL/CE subframes 202a and 202b associated with the LTE frame structure 200 forms a first set of CSI-RS subframes and the set of consecutive BL/CE subframes 204 associated with the LTE frame structure

200 forms a second set of CSI-RS subframes. Alternately, in other embodiments, the set of CSI-RS subframes comprises a set of consecutive subframes, respectively associated with the LTE frame structure as shown in Fig. 2b. In some embodiments, the set of consecutive subframes comprises BL/CE subframes or non-BL/CE

subframes, or both, associated with the LTE frame structure. In particular, in Fig. 2b, the set of consecutive subframes 252 (comprising both BL/CE subframes and non-

BL/CE subframes) associated with the LTE frame structure 250 forms a first set of CSI-

RS subframes and the set of consecutive subframes 254 (comprising only BL/CE subframes) associated with the LTE frame structure 250 forms a second set of CSI-RS subframes. However, in such embodiments, some of the CSI-RS subframes (in particular, the non-BL/CE subframes) may not be available to the UE 104, when the UE 104 comprises a BL/CE UE.

[0026] In some embodiments, the eNodeB 102 is further configured to generate a CSI- RS configuration signal 107 comprising one or more parameters associated with the repeated CSI-RS 106, to be provided to the UE 104, in order to enable the UE 104 to monitor the repeated CSI-RS 106. In some embodiments, the CSI-RS configuration signal 107 comprises a repetition parameter indicative of a number of subframes in the set of CSI-RS subframes where the CSI-RS transmission is repeated. In some embodiments, the eNodeB 102 is further configured to provide the CSI-RS configuration signal 107 to the UE 102. In some embodiments an existing parameter R ^CS1 , which determines the number of subframes where the Physical Downlink Shared Channel (PDSCH) is repeated, is reused as the repetition parameter in the CSI-RS configuration signal 107. Alternately, in other embodiments a new parameter R ^CSI~RS which may take different values than R ^csl , is introduced to be utilized as the repetition parameter in the CSI-RS configuration signal 107. In the LTE frame structure 200 in Fig. 2a, the set of CSI-RS subframes comprises 4 subframes. Therefore, in this embodiment, the value of the repetition parameter is 4. However, the value of the repetition parameter may be different in different embodiments.

[0027] In some embodiments, the repeated CSI-RS 106 has a repeated CSI-RS transmission periodicity T _CSI-RS associated therewith. In some embodiments, the repeated CSI-RS transmission periodicity indicates a number of subframes (e.g., 80 subframes, 160 subframes etc.) in which the repeated CSI-RS is transmitted

periodically. As can be seen in Fig. 2a, the repeated CSI-RS transmission periodicity Tcsi-Rs is 10 subframes. However, in other embodiments, the repeated CSI-RS transmission periodicity T _CSI-RS may be different. Currently, for CSI-RS transmission without repetition, a maximum value of the CSI-RS periodicity is 80 subframes.

However, in order to fit in the multiple repetitions of CSI-RS associated with the repeated CSI-RS 106, the repeated CSI-RS transmission periodicity T _CSI-RS rray be increased to be greater than 80 subframes, for example, T _CSI-RS 160 subframes. In some embodiments, the repeated CSI-RS transmission periodicity T _CSI-RS is chosen in a way that the periodic transmissions of the repeated CSI-RS 106 do not overlap.

Referring back to Fig. 1 , in some embodiments, the CSI-RS configuration signal 107 further comprises a repeated periodicity parameter indicative of the repeated CSI-RS transmission periodicity. In some embodiments, the repeated CSI-RS 106 further comprises a periodicity offset ^ ^CSI - ^RS _J indicative of a number of subframes within the repeated CSI-RS transmission periodicity T _CSI-RS , after which the transmission of the repeated CSI-RS 106 begins. In particular, in Fig. 2a, the periodicity offset ^{Acs s} = 2 subframes. However, the periodicity offset ^CSI-RS _ma y be different in different embodiments.

[0028] Current specification of E-UTRAN assumes maximum 8 antenna ports for CSI- RS. However, max number of antenna ports for demodulation reference signal (DMRS) of physical downlink shared channel (PDSCH) or Physical Downlink Control Channel (PDCCH) in CE mode is 4. Consequently, in some embodiments, it is proposed to limit the max number of CSI-RS antenna ports for non-BL UEs in CE mode also to 4 (or lesser than 8). In some embodiments, the existing CSI-RS configurations defined in 3GPP TS 36.21 1 for 1 ,2 and 4 antenna ports are reused. Therefore, in some embodiments, the eNodeB 102 is configured to utilize a reduced number of CSI-RS antenna ports compared to a maximum number of available CSI-RS antenna ports for the transmission of the repeated CSI-RS (e.g., 4 instead of 8). In some embodiments, reducing the number of CSI-RS antenna ports for the transmission of the repeated CSI- RS from the maximum number of available CSI-RS antenna ports enables to increase the density of each repeated transmission associated with the repeated CSI-RS based on reusing the resource elements (REs) previously allocated for the unused CSI-RS antenna ports. Fig. 3 illustrates an exemplary CSI-RS configuration 300 for 8 CSI-RS ports, where REs allocated for CSI-RS ports numbered from 4 to 7 can be reused for transmission of CSI-RS ports numbered from 0 to 3. Referring back to Fig. 1 , in some embodiments, the CSI-RS configuration signal 107 further comprises one or more CSI- RS bandwidth parameters indicative of a frequency range where the UE 104 can expect the repeated CSI-RS 106. In some embodiments, the one or more CSI-RS bandwidth parameters comprises a starting physical resource block (PRB) and a number of PRBs associated with the LTE frame structure where the UE 102 can expect the repeated CSI-RS 106. [0029] In some embodiments, the UE 104 is configured to monitor the repeated CSI- RS 106 on the set of CSI-RS subframes from the eNodeB 102, in order to determine the channel state information (CSI). In some embodiments, the UE 104 is further configured to process the CSI-RS configuration signal 107, received from the eNodeB 102, prior to monitoring the repeated CSI-RS 106, in order to enable the UE 104 to monitor the repeated CSI-RS 106. Based on monitoring the repeated CSI-RS, in some embodiments, the UE 104 is further configured to process one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS 106 (e.g., the repeated CSI-RS transmissions that successfully reached the UE 104) and determine the CSI based thereon. In some embodiments, when the UE 104 comprises a non-BL UE, the UE 104 may be configured to process all the repeated transmissions of the CSI- RS (or less than all, depending on the channel conditions) associated with the repeated CSI-RS 106, in order to determine the CSI. In such embodiments, the one or more repeated transmissions of the CSI-RS may comprise all the repeated transmissions of the CSI-RS associated with the repeated CSI-RS 106. However, in embodiments where the UE 104 comprises a BL/CE UE and when the set of CSI-RS subframes comprise both BL/CE subframes and non-BL/CE subframes, the UE 104 may be configured to process only the repeated transmissions of the CSI-RS on the BL/CE subframes, in order to determine the CSI. In some embodiments, the UE 104 is further configured to provide a CSI feedback signal 108 comprising the determined CSI to the eNodeB 102.

[0030] In some embodiments, the UE 104 is configured to monitor the repeated CSI- RS 106 in a frequency range indicated by the one or more CSI-RS bandwidth parameters within the CSI-RS configuration signal 107. Alternately, in other

embodiments, the UE 104 may be configured to monitor the repeated CSI-RS in a frequency range corresponding to a configured signal bandwidth associated with the UE. However, in some embodiments, the UE 104 may be configured to monitor the repeated CSI-RS 106 across the entire system bandwidth (e.g., the LTE bandwidth). Further, in some embodiments, when the UE 104 comprises a bandwidth limited low complexity coverage enhancement (BL/CE) UE, the UE 104 may be configured to monitor the repeated CSI-RS 106 in all narrowbands (NBs) configured for the UE 104, in order to enable frequency hopping for machine type communication physical downlink control channel (MPDCCH) monitoring in connected mode. [0031] Referring to FIG. 4, illustrated is a block diagram of an apparatus 400 employable at a Base Station (BS), eNodeB, gNodeB or other network device that can enable a user equipment (UE) in coverage enhancement (CE) mode associated therewith to determine channel state information (CSI) based on a repeated channel state information reference signal (CSI-RS), according to various aspects described herein. The apparatus 400 can include one or more processors 410 (e.g., one or more baseband processors) comprising processing circuitry and associated interface(s) (e.g., a radio frequency (RF) interface), communication circuitry 420 (e.g., which can comprise circuitry for one or more wired (e.g., X2, etc.) connections and/or RF circuitry, which can comprise one or more of transmitter circuitry (e.g., associated with one or more transmit chains) or receiver circuitry (e.g., associated with one or more receive chains), wherein the transmitter circuitry and receiver circuitry can employ common circuit elements, distinct circuit elements, or a combination thereof), and memory 430 (which can comprise any of a variety of storage mediums and can store instructions and/or data associated with one or more of processor(s) 410 or communication circuitry 420). In various aspects, the apparatus 400 can be included within an Evolved

Universal Terrestrial Radio Access Network (E-UTRAN) Node B (Evolved Node B, eNodeB, or eNB), next generation Node B (gNodeB or gNB) or other base station or TRP (Transmit/Receive Point) in a wireless communications network. In some aspects, the processor(s) 410, communication circuitry 420, and the memory 430 can be included in a single device, while in other aspects, they can be included in different devices, such as part of a distributed architecture.

[0032] In some embodiments, the apparatus 400 could be included within the eNodeB

102 of Fig. 1. Therefore, the apparatus 400 is described herein with respect to the eNodeB 102 of Fig. 1 , to cover the various aspects of the disclosure. However, in other embodiments, the apparatus 400 could be included within any eNodeB associated with a long term evolution (LTE) network. In some embodiments, the processing circuit 410 is configured to configure a channel state information reference signal (CSI-RS) to be repeatedly transmitted in a set of CSI-RS subframes associated with a long term evolution (LTE) frame structure. In particular, the processing circuit 410 is configured to generate a set of repeated transmissions of a channel state information reference signal

(CSI-RS), forming a repeated CSI-RS (e.g., the repeated CSI-RS 106 in Fig. 1 ), to be provided to a user equipment (UE) (e.g., the UE 104 in Fig. 1 ) in the set of CSI-RS subframes, respectively associated with an LTE frame structure, in order to enable the UE to determine channel state information (CSI) based on the repeated CSI-RS. In some embodiments, the processing circuit 410 is configured to generate the repeated CSI-RS, based on instructions stored in the memory circuit 430.

[0033] In some embodiments, the processing circuit 410 is further configured to provide, to communication circuitry 420, the repeated CSI-RS, for subsequent transmission to the UE in the set of CSI-RS subframes. In some embodiments, the processing circuit 410 is configured to provide the repeated CSI-RS, to communication circuitry 420, via a radio frequency (RF) interface. In some embodiments, the communication circuitry 420 is configured to transmit the repeated CSI-RS to the UE in the set of CSI-RS subframes. In some embodiments, the processing circuit 410 is further configured to determine the set of CSI-RS subframes on which the set of repeated transmissions of the CSI-RS is to be transmitted to the UE. In some embodiments, the set of CSI-RS subframes on which the set of repeated transmission of the CSI-RS is transmitted may be determined at the processing circuit 410 based on channel conditions. Alternately, in other embodiments, the set of CSI-RS subframes may be predefined. In some embodiments, the set of CSI-RS subframes comprises a set of consecutive BL/CE subframes, respectively, associated with the LTE frame structure, as shown in Fig. 2a above. Alternately, in other embodiments, the set of CSI- RS subframes comprises a set of consecutive subframes, respectively associated with the LTE frame structure as shown in Fig. 2b above. In some embodiments, the set of consecutive subframes comprises BL/CE subframes or non-BL/CE subframes, or both, associated with the LTE frame structure.

[0034] In some embodiments, the processing circuit 410 is further configured to generate a CSI-RS configuration signal (e.g., the CSI-RS configuration signal 107 in Fig. 1 ) comprising one or more parameters associated with the repeated CSI-RS, in order to enable the UE to monitor the repeated CSI-RS. In some embodiments, the processing circuit 410 is further configured to provide the CSI-RS configuration signal to the communication circuitry 420 for subsequent transmission to the UE. In some embodiments, the CSI-RS configuration signal comprises a repetition parameter indicative of a number of subframes in the set of CSI-RS subframes where the CSI-RS transmission is repeated. In some embodiments, the repeated CSI-RS has a repeated CSI-RS transmission periodicity associated therewith that indicates a number of subframes in which the repeated CSI-RS is transmitted periodically (e.g., 10 subframes in Fig. 2a). In some embodiments, the CSI-RS configuration signal further comprises a repeated periodicity parameter indicative of the repeated CSI-RS transmission periodicity. In some embodiments, the CSI-RS configuration signal further comprises one or more CSI-RS bandwidth parameters indicative of a frequency range where the UE can expect the repeated CSI-RS. In some embodiments, the one or more CSI-RS bandwidth parameters comprises a starting physical resource block (PRB) and a number of PRBs associated with the LTE frame structure where the UE can expect the repeated CSI-RS.

[0035] In some embodiments, the processing circuit 410 is further configured to utilize a reduced number of CSI-RS antenna ports compared to a maximum number of available CSI-RS antenna ports (e.g., 4 antenna ports instead of the maximum 8 antenna ports available for CSI-RS) for the transmission of the repeated CSI-RS. In some embodiments, utilizing a lower number of CSI-RS antenna ports for the transmission of the repeated CSI-RS enables to increase the density of each repeated transmission associated with the repeated CSI-RS, based on reusing the resource elements (REs) previously allocated for the unused CSI-RS antenna ports, as explained above with respect to Fig. 1 and Fig. 3 above.

[0036] Referring to FIG. 5, illustrated is a block diagram of an apparatus 500 employable at a user equipment (UE) or other network device (e.g., loT device) that facilitates to determine channel state information (CSI) based on a repeated channel state information reference signal (CSI-RS), according to various aspects described herein. Apparatus 500 can include one or more processors 510 (e.g., one or more baseband processors) comprising processing circuitry and associated interface(s) (e.g., a radio frequency (RF) interface), transceiver circuitry 520 (e.g., comprising RF circuitry, which can comprise transmitter circuitry (e.g., associated with one or more transmit chains) and/or receiver circuitry (e.g., associated with one or more receive chains) that can employ common circuit elements, distinct circuit elements, or a combination thereof), and a memory 530 (which can comprise any of a variety of storage mediums and can store instructions and/or data associated with one or more of processor(s) 510 or transceiver circuitry 520). In various aspects, apparatus 500 can be included within a user equipment (UE).

[0037] In various aspects discussed herein, signals and/or messages can be generated and output for transmission, and/or transmitted messages can be received and processed. Depending on the type of signal or message generated, outputting for transmission (e.g., by processor(s) 510) can comprise one or more of the following: generating a set of associated bits that indicate the content of the signal or message, coding (e.g., which can include adding a cyclic redundancy check (CRC) and/or coding via one or more of turbo code, low density parity-check (LDPC) code, tailbiting convolution code (TBCC), etc.), scrambling (e.g., based on a scrambling seed), modulating (e.g., via one of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), or some form of quadrature amplitude modulation (QAM), etc.), and/or resource mapping (e.g., to a scheduled set of resources, to a set of time and frequency resources granted for uplink transmission, etc.). Depending on the type of received signal or message, processing (e.g., by processor(s) 510) can comprise one or more of: identifying physical resources associated with the signal/message, detecting the signal/message, resource element group deinterleaving, demodulation, descrambling, and/or decoding.

[0038] In some embodiments, the apparatus 500 could be included within the UE 104 of Fig. 1 . Therefore, the apparatus 500 is described herein with respect to the UE 104 of Fig. 1 , to cover the various aspects of the disclosure. However, in other

embodiments, the apparatus 500 could be included within any UE in coverage enhanced (CE) mode associated with a long term evolution (LTE) network. In some embodiments, the processing circuit 510 is configured to monitor a repeated channel state information reference signal (CSI-RS) (e.g., the repeated CSI-RS 106 in Fig. 1 ) comprising a set of repeated transmissions of a CSI-RS from an eNodeB associated therewith (e.g., the eNodeB 102 in Fig. 1 ), on a set of CSI-RS subframes, respectively associated with an LTE frame structure. In some embodiments, the set of CSI-RS subframes comprises a set of consecutive BL/CE subframes, respectively, associated with the LTE frame structure, as shown in Fig. 2a above. Alternately, in other embodiments, the set of CSI-RS subframes comprises a set of consecutive subframes, respectively associated with the LTE frame structure as shown in Fig. 2b above. In some embodiments, the set of consecutive subframes comprises both bandwidth limited low complexity coverage enhanced (BL/CE) subframes and non-bandwidth limited low complexity coverage enhanced (non-BL/CE) subframes, associated with the LTE frame structure.

[0039] In some embodiments, the processing circuit 510 is configured to monitor the repeated CSI-RS, based on processing a CSI-RS configuration signal (e.g., the CSI-RS configuration signal 107 in Fig. 1 ) comprising one or more parameters associated with the repeated CSI-RS, received from the eNodeB. Therefore, in such embodiments, the processing circuit 510 is further configured to process the CSI-RS configuration signal, received from the eNodeB, prior to monitoring the repeated CSI-RS. In some embodiments, the CSI-RS configuration signal comprises a repetition parameter indicative of a number of subframes in the set of CSI-RS subframes where the CSI-RS transmission is repeated. In some embodiments, the repeated CSI-RS has a repeated CSI-RS transmission periodicity associated therewith that indicates a number of subframes in which the repeated CSI-RS is transmitted periodically (e.g., transmitted periodically in every 10 subframes in Fig. 2a). In some embodiments, the CSI-RS configuration signal further comprises a repeated periodicity parameter indicative of the repeated CSI-RS transmission periodicity.

[0040] In some embodiments, the CSI-RS configuration signal further comprises one or more CSI-RS bandwidth parameters indicative of a frequency range where the UE can expect the repeated CSI-RS. In some embodiments, the one or more CSI-RS bandwidth parameters comprises a starting physical resource block (PRB) and a number of PRBs associated with the LTE frame structure where the UE can expect the repeated CSI-RS. In some embodiments, the processing circuit 510 is configured to monitor the repeated CSI-RS in the frequency range indicated by the one or more CSI- RS bandwidth parameters. However, in other embodiments, the processing circuit 510 may be configured to monitor the repeated CSI-RS in a frequency range corresponding to a configured signal bandwidth associated with the UE. Further, in some

embodiments, when the UE comprises a bandwidth limited low complexity coverage enhancement (BL/CE) UE, the processing circuit 510 may be configured to monitor the repeated CSI-RS in all narrowbands (NBs) configured for the UE. [0041] Based on monitoring the repeated CSI-RS, the processing circuit 510 is further configured to process one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS, received from the eNodeB on one or more respective CSI- RS subframes of the set of CSI-RS subframes. In some embodiments, the

communication circuitry 520 is configured to receive the one or more repeated transmissions of the CSI-RS from the eNodeB, and provide the one or more repeated transmission of the CSI-RS to the processing circuit 510, via a radio frequency (RF) interface. In some embodiments, the processing circuit 510 is further configured to determine a channel state information (CSI) based on processing the one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS. In some embodiments, the processing circuit 510 is configured to determine the CSI based on instructions stored in the memory circuit 530. In some embodiments, the processing circuit 510 is further configured to provide a CSI feedback signal (e.g., the CSI feedback signal 108 in FIG. 1 ) comprising the determined CSI to the communication circuitry 520, for subsequent transmission to the eNodeB.

[0042] Examples can include subject matter such as a method, means for

performing acts or blocks of the method, at least one machine-readable medium including instructions that, when performed by a machine cause the machine to perform acts of the method or of an apparatus or system for concurrent

communication using multiple communication technologies according to

embodiments and examples described herein.

[0043] Example 1 is an apparatus configured to be employed in an eNodeB

associated with a long term evolution (LTE) communication system, comprising one or more processors configured to generate a set of repeated transmissions of a channel state information reference signal (CSI-RS), forming a repeated CSI-RS, to be provided to a user equipment (UE) in a set of CSI-RS subframes, respectively associated with an LTE frame structure, in order to enable the UE to determine channel state information (CSI) based on the repeated CSI-RS; and a radio frequency (RF) interface, configured to provide, to a radio frequency (RF) circuitry, the repeated CSI-RS, for subsequent transmission to the UE in the set of CSI-RS subframes. [0044] Example 2 is an apparatus, including the subject matter of example 1 , wherein the one or more processors is further configured to generate a CSI-RS configuration signal comprising one or more parameters associated with the repeated CSI-RS, to be provided to the RF circuitry for subsequent transmission to the UE, in order to enable the UE to monitor the repeated CSI-RS.

[0045] Example 3 is an apparatus, including the subject matter of examples 1 -2, including or omitting elements, wherein the CSI-RS configuration signal comprises a repetition parameter indicative of a number of subframes in the set of CSI-RS subframes where the CSI-RS transmission is repeated.

[0046] Example 4 is an apparatus, including the subject matter of examples 1 -3, including or omitting elements, wherein the repeated CSI-RS has a repeated CSI-RS transmission periodicity associated therewith that indicates a number of subframes in which the repeated CSI-RS is transmitted periodically, and wherein the CSI-RS configuration signal comprises a repeated periodicity parameter indicative of the repeated CSI-RS transmission periodicity.

[0047] Example 5 is an apparatus, including the subject matter of examples 1 -4, including or omitting elements, wherein the set of subframes comprises a set of consecutive bandwidth limited low complexity coverage enhanced (BL/CE) subframes, respectively, associated with the LTE frame structure.

[0048] Example 6 is an apparatus, including the subject matter of examples 1 -5, including or omitting elements, wherein the set of subframes comprises a set of consecutive subframes, respectively, associated with the LTE frame structure, wherein the set of consecutive subframes comprises bandwidth limited low complexity coverage enhanced (BL/CE) subframes or non-bandwidth limited low complexity coverage enhanced (non-BL/CE) subframes, or both, associated with the LTE frame structure.

[0049] Example 7 is an apparatus, including the subject matter of examples 1 -6, including or omitting elements, wherein the one or more processors is configured to utilize a reduced number of CSI-RS antenna ports compared to a maximum number of available CSI-RS antenna ports for the transmission of the repeated CSI-RS, thereby enabling to increase the density of each repeated transmission of the repeated CSI-RS based on reusing the resource elements (REs) previously allocated for the unused CSI- RS antenna ports.

[0050] Example 8 is an apparatus, including the subject matter of examples 1 -7, including or omitting elements, wherein the CSI-RS configuration signal further comprises one or more CSI-RS bandwidth parameters indicative of a frequency range where the UE can expect the repeated CSI-RS.

[0051] Example 9 is an apparatus, including the subject matter of examples 1 -8, including or omitting elements, wherein the one or more CSI-RS bandwidth parameters comprises a starting physical resource block (PRB) and a number of PRBs associated with the LTE frame structure where the UE can expect the repeated CSI-RS.

[0052] Example 10 is an apparatus configured to be employed in a user equipment (UE) in a coverage enhanced (CE) mode associated with a long term evolution (LTE) communication system, comprising one or more processors configured to monitor a repeated channel state information reference signal (CSI-RS) comprising a set of repeated transmissions of a CSI-RS from an eNodeB associated therewith, on a set of CSI-RS subframes, respectively associated with an LTE frame structure; process one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS, received from the eNodeB on one or more respective CSI-RS subframes of the set of CSI-RS subframes; and determine a channel state information (CSI) based on processing the one or more repeated transmissions of the CSI-RS associated with the repeated CSI-RS.

[0053] Example 1 1 is an apparatus, including the subject matter of example 10, wherein the one or more processors is further configured to process a CSI-RS configuration signal, received from the eNodeB, prior to monitoring the repeated CSI- RS, wherein the CSI-RS configuration signal comprises one or more parameters associated with the repeated CSI-RS.

[0054] Example 12 is an apparatus, including the subject matter of examples 10-1 1 , including or omitting elements, wherein the CSI-RS configuration signal comprises a repetition parameter indicative of a number of subframes in the set of subframes associated with an LTE frame structure, where the CSI-RS transmission is repeated, in order to enable the UE to monitor the repeated CSI-RS.

[0055] Example 13 is an apparatus, including the subject matter of examples 10-12, including or omitting elements, wherein the repeated CSI-RS has a repeated CSI-RS transmission periodicity associated therewith that indicates a number of subframes after which the repeated CSI-RS is transmitted periodically, and wherein the CSI-RS configuration signal further comprises a repeated periodicity parameter indicative of the repeated CSI-RS transmission periodicity.

[0056] Example 14 is an apparatus, including the subject matter of examples 10-13, including or omitting elements, wherein the set of CSI-RS subframes comprises a set of consecutive bandwidth limited low complexity coverage enhanced (BL/CE) subframes, respectively, associated with the LTE frame structure.

[0057] Example 15 is an apparatus, including the subject matter of examples 10-14, including or omitting elements, wherein the set of CSI-RS subframes comprises a set of consecutive subframes, respectively, associated with the LTE frame structure, wherein the set of consecutive subframes comprises bandwidth limited low complexity coverage enhanced (BL/CE) subframes or non-bandwidth limited low complexity coverage enhanced (non-BL/CE) subframes, or both, associated with the LTE frame structure.

[0058] Example 16 is an apparatus, including the subject matter of examples 10-15, including or omitting elements, wherein the CSI-RS configuration signal further comprises one or more CSI-RS bandwidth parameters indicative of a frequency range where the UE can expect the repeated CSI-RS, in order to enable the UE to monitor the repeated CSI-RS.

[0059] Example 17 is an apparatus, including the subject matter of examples 10-16, including or omitting elements, wherein the one or more processors is configured to monitor the repeated CSI-RS in the frequency range indicated by the one or more CSI- RS bandwidth parameters.

[0060] Example 18 is an apparatus, including the subject matter of examples 10-17, including or omitting elements, wherein the one or more processors is configured to monitor the repeated CSI-RS in a frequency range corresponding to a configured signal bandwidth associated with the UE.

[0061] Example 19 is an apparatus, including the subject matter of examples 10-18, including or omitting elements, wherein, when the UE comprises a bandwidth limited low complexity coverage enhancement (BL/CE) UE, the one or more processors is configured to monitor the repeated CSI-RS in all narrowbands (NBs) configured for the UE.

[0062] Example 20 is a computer readable storage device storing executable instructions that, in response to execution, cause one or more processors of an eNodeB to perform operations, the operations comprising generating a set of repeated transmissions of a channel state information reference signal (CSI-RS), forming a repeated CSI-RS, to be provided to a user equipment (UE), in a set of CSI-RS subframes, respectively associated with an LTE frame structure, in order to enable the UE to determine channel state information (CSI) based on the repeated CSI-RS; and providing the repeated CSI-RS, to a radio frequency (RF) circuitry, for subsequent transmission to the UE in the set of CSI-RS subframes.

[0063] Example 21 is a computer readable storage device, including the subject matter of example 20, wherein the operations further comprise generating a CSI-RS configuration signal comprising one or more parameters associated with the repeated CSI-RS, to be provided to the RF circuitry for subsequent transmission to the UE, in order to enable the UE to monitor the repeated CSI-RS.

[0064] While the apparatus has been illustrated and described with respect to one or more implementations, alterations and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In particular regard to the various functions performed by the above described

components or structures (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the invention.