Patent Application
20200195317
The present invention relates to a user apparatus in a radio communication system.
In LTE (Long Term Evolution) and the successor systems of LTE (e.g., LTE-A (LTE Advanced), NR (New Radio) (also called 5G)), D2D (Device to Device) technology in which user apparatuses directly communicate with each other without going through a radio base station has been studied.
D2D reduces the traffic between user apparatuses and a base station and enables communications between the user apparatuses even when the base station becomes unable to communicate in the event of a disaster, etc.
D2D technology is roughly divided into D2D discovery and D2D communication; D2D discovery being used for finding other communicative user apparatuses and D2D communication being used for direct communication between user apparatuses (also referred to as D2D direct communication, D2D communication, terminal-terminal direct communication, etc.). In the following, the above-described D2D communication, D2D discovery, etc. may be simply called D2D when they are not specifically distinguished. Further, a signal transmitted and received by D2D is referred to as a D2D signal.
In 3GPP (3rd Generation Partnership Project), D2D is referred to as “side link (sidelink)”; however, a more general term “D2D” is used in this specification. However, sidelink is also used as necessary in the description of the embodiment to be described later.
In 3GPP, implementation of V2X (Vehicle Attachment Everything) has been studied by extending the D2D function, and specifications of V2X are in progress. Note that V2X is a part of ITS (Intelligent Transport Systems); V2X is, as illustrated in
In Rel-14 of LTE, specifications of several functions of V2X have been made (e.g., Non-Patent Document 1). In these specifications, Mode 3 and Mode 4 are defined with respect to resource allocation for V2X communication to a user apparatus. In Mode 3, transmission resources are allocated dynamically by DCI (Downlink Control Information) sent from a base station to a user apparatus. In Mode 3, SPS (Semi Persistent Scheduling) is also possible. In Mode 4, a user apparatus autonomously selects transmission resources from the resource pool.
In V2X (especially V2V), which is expected to perform D2D communication between terminals moving at high speeds, studies have been conducted to improve the quality and reliability of communications by applying transmit diversity to the user apparatus for transmission. As one of transmit diversity technologies, precoding vector switching (PVS) may be given; PVS switches precoding vectors in the time domain. Studies have been conducted on the application of this PVS to D2D such as V2X. However, a specific technology for applying PVS to perform D2D communication has been yet to be proposed.
The present invention has been made in view of the above-described points, and it is an object of the present invention to provide a technology for allowing a user apparatus to apply a precoding vector switch to appropriately perform D2D communication in a radio communication system that supports D2D communication.
According to a disclosed technology, a user apparatus in a radio communication system that supports a D2D communication is provided. The user apparatus includes
a setting information storage unit configured to store a plurality of precoding matrices; and
a signal transmission unit configured to precode a D2D signal and transmit the precoded D2D signal while switching a precoding matrix among the plurality of precoding matrices in a time domain, in a predetermined time interval including a plurality of unit time intervals, wherein
the signal transmission unit maps a reference signal precoded by a same precoding matrix to at least two unit time intervals in the predetermined time interval.
According to the disclosed technology, a user apparatus is enabled to apply a precoding vector switch to appropriately perform D2D communication, in a radio communication system supporting D2D communication.
The following describes embodiments according to embodiments of the present invention with reference to the accompanying drawings. Note that the embodiments described below are merely examples and the embodiments to which the present invention is applied are not limited to the following embodiments. For example, it is assumed that a radio communication system according to an embodiment complies with LTE standards. However, the present invention may be applied not limited to LTE but may also be applied to other systems. Note that, in the specification and the claims, the term “LTE” is used not only to mean a communication scheme corresponding to 3GPP release 8 or 9, but also to mean the fifth-generation (5G, NR) mobile communication system corresponding to 3GPP release 10, 11, 12, 13, 14 or beyond.
Further, although a technology according to the present embodiment may be applied mainly to V2X, the application of the technology according to the present embodiment is not limited to V2X, but may be widely applicable to D2D in general. The aspect of the “D2D” includes V2X in this sense. In addition, the term “D2D” is not limited to LTE, but refers to general communications between terminals. Further, although the present embodiment is mainly applicable to “D2D communications”, the present invention is applicable not only to “D2D communications” but is also applicable to “D2D discovery”.
Furthermore, unless otherwise specified, the “D2D signal” may be a data signal, an SCI, a discovery signal, or a combination of the SCI and the data signal.
The present embodiment employs D2D as a basic technology; hence, an outline of D2D prescribed in LTE will be described first. It should be noted that V2X may also employ the D2D technology described below, and a user apparatus in this embodiment is enabled to transmit and receive D2D signals according to the technology.
As already described above, D2D is roughly divided into “D2D discovery” and “D2D communications”. With respect to “D2D discovery”, as illustrated in
Likewise, with respect to “D2D communications”, resource pools for SCI (Sidelink Control Information)/data transmission are periodically secured as illustrated in
Further, as described above, in Rel-14, there are Mode 3 and Mode 4 in addition to Mode 1 and Mode 2. In Rel-14, SCI and data may be transmitted simultaneously (in one subframe) with resource blocks adjacent in a frequency direction. It should be noted that the SCI may be referred to as SA (Scheduling Assignment).
In LTE, the channel for use in “D2D discovery” is referred to as PSDCH (Physical Sidelink Discovery Channel). The channel for transmitting control information such as SCI in “D2D Communications” is referred to as PSCCH (Physical Sidelink Control Channel). The channel for transmitting data is referred to as PSSCH (Physical Sidelink Shared Channel) Further, PSCCH and PSSCH have a PUSCH based structure, into which DMRS (Demodulation Reference Signal, demodulation reference signal) is inserted.
As illustrated in
As illustrated in
A user apparatus UE1 and a user apparatus UE2 depicted in
Further, the user apparatus UE may be any apparatus having a function of D2D; for example, the user apparatus UE may be a vehicle, a terminal held by a pedestrian, an RSU (a UE type RSU having a UE function), or the like.
The signal waveform used by the user apparatus UE may be a CP-OFDM (a waveform used in downlink of the existing LTE), a DFT-S-OFDM (DFT-Spreading-OFDM)), or any other signal waveforms.
In addition, a processing content of D2D transmission in the user apparatus UE is basically the same as a processing content of the uplink transmission in the LTE (Non-Patent Document 2). For example, the user apparatus UE scrambles and modulates codewords of transmission data, generates complex-valued symbols, and maps the complex-valued symbols (transmission signals) to one or two layers, thereby performing precoding. The user apparatus UE then maps the precoded complex-valued symbols to resource elements to generate a transmission signal (e.g., complex-valued time-domain SC-FDMA signal) and transmit the generated transmission signal via each antenna port. In the following embodiments, a description mainly focuses on precoding and reference signal mapping as a description of transmission processing.
Note that precoding a signal with a precoding vector indicates multiplying a signal by a precoding vector, according to which a transmission beam may be formed. Switching a precoding vector according to a lapse of time as in PVS (Precoding Vector Switching) in a time domain corresponds to switching a transmission beam direction according to a lapse of time. PVS in this embodiment is PVS in the time domain. Further, an antenna port is a logical antenna port corresponding to one or a plurality of antenna elements. Further, “precoding vector” may be referred to as “precoding matrix”. “Precoding vector” is a type of “precoding matrix”.
The base station 10 has a function of cellular communication for a base station 10 in LTE and a function (setting of DMRS mapping pattern etc.) for enabling communication of the user apparatus UE in this embodiment. Further, the base station 10 may be an RSU (eNB type RSU having the function of eNB).
The user apparatus UE in the present embodiment applies a PVS and transmits a data signal (PSSCH). The following illustrates first to fourth embodiments as specific examples thereof. In the first to fourth embodiments, the technology applied to the data signal may be applied to a control signal or a discovery signal.
The precoder 11 receives data signals and DMRSs input as transmission signals, and precodes these signals to transmit the precoded signals from each antenna port as radio signals. As an example, DMRS is a Zadoff-Chu sequence similar to LTE, and is capable of generating multiple orthogonal DMRS by cyclic shift. This also applies to later-described unprecoded RSs.
The precoder 11 in the first embodiment holds a plurality of precoding vectors in a memory or the like, and switches each precoding vector according to time. The plurality of precoding vectors are not particularly specified; however, the precoding vectors described in the codebook used for antenna ports {20, 21} are used in the first embodiment. This codebook is disclosed in Non-Patent Document 2.
In the first embodiment, a different orthogonal DMRS sequence is used for each precoder (precoding vector) in the precoders 0 to 3. Each of the plurality of different DMRSs may be associated with a corresponding one of DMRS ports (antenna port for DMRS). For example, DMRS input to precoder 0 is associated with a DMRS port 0, DMRS input to the precoder 1 is associated with a DMRS port 1, DMRS input to the precoder 2 is associated with a DMRS port 2, and DMRS input to the precoder 3 is associated with a DMRS port 3. Multiple DMRSs of different DMRS ports are mapped (multiplexed) to resource elements. It is also possible to multiplex a plurality of different DMRSs without using such a concept of “port”. In addition, CDM or FDM may be used for multiplexing of different DMRSs.
With reference to
As illustrated in each example of
Further, a time position at which a precoder is switched is referred to as a switch time position, and an interval between two switch time positions (not including either switch time position) is referred to as a switch time interval.
In any of the examples of
DMRS mapping method is different between the examples of
The user apparatus UE2 that receives the mapped signal illustrated in
In the example of
The user apparatus UE2 that receives the mapped signal illustrated in
In the example of
The user apparatus UE2 that receives the mapped signal illustrated in
The receiver end user apparatus UE2 is enabled to identify the switch time position in one subframe and the precoders used in each switch time interval, in accordance with the setting from the base station 10, definitions of the specification, or the like. Further, the user apparatus UE2 is enabled to identify the symbol position to which the DMRS is mapped, each DMRS sequence, precoders applied to each sequence, and which DMRS is mapped to each symbol, in accordance with the setting from the base station 10, definitions of the specification, or the like. Accordingly, the above-described reception operation may be accurately performed.
The user apparatus UE2 does not need to identify all the above information. For example, there may be a case where the user apparatus UE2 is enabled to identify the DMRS being mapped to the symbols #2, #5, #8, and #11, but is not enabled to identify the DMRS sequence (and the corresponding precoder). In such a case, the content of the SCI (SA) or its CRC and the corresponding sequence of the DMRS are associated in advance. Further, a cyclic shift offset (CS offset) for generating the other three sequences from this sequence is also determined in advance. It is assumed that these pieces of information are known by each user apparatus.
The transmitter end user apparatus UE1 then transmits the SCI (control information) with respect to the data signal to be transmitted, maps the sequence of DMRS (precoded by the precoder 0) corresponding to the content of the SCI or the CRC to the symbol #2 (corresponding to the first DMRS, the first precoder 0), maps the three DMRSs generated by using the CS offset to the symbols #5, #8, and #11 and transmits them together with the data signal (e.g.,
The receiver end user apparatus UE2 receives the SCI and identifies the DMRS sequence mapped to the symbol #2 based on the CRC of the SCI. Further, based on the identified sequence, the user apparatus UE2 identifies the other three DMRSs, performs channel estimation using respective DMRSs, and demodulates the data signals by using CS offset. It is assumed that the user apparatus UE 2 identifies that the DMRSs mapped to the symbols #2, #5, #8, and #11 are precoded by the precoders 0, 1, 2, and 3 based on the switch time positions of the precoders, for example.
According to the above method (method using content of SCI and its CRS), in any of
In a case where the mapping illustrated in
For example, the mapping of a DMRS precoded by the precoder corresponding to a switch time interval may be predetermined for two symbols, i.e., one symbol in the switch time interval and the subsequent (or preceding) symbol, and such information may be preset in each user apparatus. In this case, the receiver end user apparatus UE2 may perform channel estimation using the DMRS sequence precoded by the precoder 0 in the first two symbols in one subframe without performing the above blind detection. The user apparatus UE2 may perform channel estimation with the DMRSs corresponding to other precoders in the same manner as noted above.
The following describes a second embodiment.
The precoder 11 in the second embodiment holds a plurality of precoding vectors in a memory or the like, and switches each precoding vector according to time, in the same manner as the first embodiment. The plurality of precoding vectors are not particularly specified; however, the precoding vectors described in the codebook used for antenna ports {20, 21} are used as described in the first embodiment. This codebook is disclosed in Non-Patent Document 2.
The precoder 11 receives data signals and precodes the data signals to transmit the precoded signals from each antenna port as radio signals. In the second embodiment, a DMRS subject to precoding is not used, which differs from the first embodiment.
As illustrated in
With reference to
In
That is, the user apparatus UE 1 maps data signals precoded by the precoder 0 to the symbols #0, #1, and #3, maps data signals precoded by the precoder 1 to the symbols #4 and #6, maps data signals precoded by the precoder 2 to the symbols #7 and #9, and maps data signals precoded by the precoder 3 to the symbols #10 and #12. Such patterns of precoding (a pattern indicating which precode is applied in which switch time interval) are set from the base station 10 to the user apparatus UE1, for example. Further, such patterns may be defined by specifications or the like, the patterns may be held by the user apparatus UE1 in advance, the patterns may be transmitted by using a SCI (SA), and the patterns may each be uniquely determined from the CRC of the SA.
In addition, as illustrated in
In the second embodiment, it is assumed that the switch time position of the precoder, the precoder applied in each switch time interval, and the symbol to which the RS is mapped are known by each user apparatus, based on the setting from the base station 10, according to definitions of the specification, or the like.
There may be a case where the receiver end user apparatus UE2 is enabled to identify two RSs being mapped (multiplexed) to the symbols #2, #5, #8, and #11 and the multiplexing method (in FDM, the frequency position etc. of each RS), but is not enabled to identify the sequence of each RS. In such a case, for example, a plurality of pieces of information obtained from the content of SCI (SA) or its CRC may be associated with a plurality of first RS sequences (S1) in advance. Further, a cyclic shift offset (CS offset) for generating the second RS sequence from this sequence is also determined in advance. It is assumed that these pieces of information are known by each user apparatus.
The transmitter end user apparatus UE1 then transmits the SCI with respect to the data signal to be transmitted, maps a first RS sequence (S1) corresponding to the CRC of the SCI and a second RS sequence (S2) obtained from the first RS sequence (S1) by cyclic shift to the symbols #2, #5, #8, and #11, and transmits them together with the data signals.
The receiver end user apparatus UE2 receives the SCI and identifies the first RS sequence (S1) based on the content of the SCI or CRC of the SCI. Further, based on this sequence, the user apparatus UE2 identifies the second RS sequence (S2) by using CS offset, performs channel estimation using each RS, and demodulates the data signal. The user apparatus UE2 demodulates the data signal based on the precoder information (known) used in each switch time interval and the channel estimation result according to the two RSs.
In the second embodiment, two RS sequences of S1 and S2 are mapped to one symbol; however, this case is only an example. In the second embodiment, only one sequence may be mapped, or three or more sequences may be mapped.
The following describes a third embodiment. The third embodiment is a combination of the first embodiment and the second embodiment.
The precoder 11 in the third embodiment holds a plurality of precoding vectors in a memory or the like, and switches each precoding vector according to time, in the same manner as the first embodiment and second embodiment. The plurality of precoding vectors are not particularly specified; however, the precoding vectors described in the codebook used for antenna ports {20, 21} are used as described in the first embodiment and the second embodiment. This codebook is disclosed in Non-Patent Document 2.
The precoder 11 receives data signals and DMRSs input as transmission signals, as in the first embodiment and the second embodiment. The precoder 11 precodes the data signal and DMRS to transmit the precoded signal and DMRS from each antenna port as radio signals.
As illustrated in
With reference to
In
Further, in the example of
The user apparatus UE2, which receives the mapped signals illustrated in
As described in the first and second embodiments, the user apparatus UE2 may determine sequences using the SCI CRC and the CS offset, and by using the determined sequences, estimate the sequences of the DMRS and RS.
In the first to fourth embodiments, SCI is used for reporting a pattern or a sequence. In such a case, any information on SCI, without being limited to CRS, may be used.
The fourth embodiment is a modification from the second embodiment. The user apparatus UE 1 and the user apparatus UE2 in the fourth embodiment include the functions of the user apparatus UE1 and the user apparatus UE2 in the second embodiment. Hereinafter, the difference from the second embodiment (the features added from the second embodiment) will mainly be described. The processing features described below may be applied to the first embodiment or the third embodiment.
In the fourth embodiment, patterns of a plurality of precoding vectors used by the precoder 11 of the user apparatus UE1 are determined by specifications or the like, and the patterns are set in advance in each user apparatus. The base station 10 may set these patterns in the user apparatus UE1.
For example, when precoding vectors 0 to 3 (precoders 0 to 3) are used, a plurality of patterns (e.g., pattern 1={0, 1, 2, 3}, pattern 2={1, 0, 2, 3}, and pattern 3={3, 2, 1, 0}) are each defined as a pattern having the order of the application of the precoding vectors being changed, and are set in each user apparatus. Note that “0” indicates precoding vector 0. The other numbers similarly indicate precoding vectors accordingly. The order of numbers in each pattern indicates the order in which the corresponding precoding vector is applied. For example, the mapping illustrated in
Here, it is assumed that the information obtained from the contents of the SCI is associated with the pattern. The transmitter end user apparatus UE1 selects one pattern based on the contents (or CRC mask) of the SCI, performs the PVS applying the pattern, and transmits the data signal. For example, when pattern 1 is selected, the mapping signals illustrated in
The receiver end user apparatus UE2 receives the SCI from the user apparatus UE1, determines the pattern used by the user apparatus UE1 based on the contents of the SCI, and demodulates the data signals based on the determined pattern. For example, when the pattern used by the user apparatus UE1 is the above pattern 1 (
Alternatively, one pattern may be defined, and the determined pattern may be set in advance in each user apparatus. In such a case, for example, the correspondence between information (numerical values, etc.) obtained from the contents (or CRC mask) of the SCI and the cyclic shift may be defined and set in advance for each user apparatus.
The user apparatus UE 1 that performs transmission by applying the above-mentioned one pattern selects one cyclic shift from a plurality of cyclic shifts defined in advance on the basis of the contents (or CRC mask) of the SCI, performs the PVS applying the cyclic shift pattern, and transmits the data signal.
For example, in a case where the defined pattern is indicated by A in
Further, in a case of defining a plurality of patterns, the user apparatus UE1 may include the index of the pattern in the SCI and transmit the SCI including this index. In this case, the receiver end user apparatus UE2 receives the SCI from the user apparatus UE1, determines the pattern used by the user apparatus UE1 based on the index included in the SCI, and demodulates the data signal based on the determined pattern. Note that the user apparatus UE1 may select any pattern. For example, the user apparatus UE1 may select a pattern for “transmit diversity” or may select a pattern for beam forming.
In each of the first to fourth embodiments, the user apparatus UE1 may report to the user apparatus UE2 with the SCI (PSCCH) whether to apply transmit diversity to the data signal (PSSCH). For example, the user apparatus UE2 that has received the information indicating “presence” of transmit diversity may determine to perform the search operation (blind detection) of the DMRS described in the first embodiment (as required).
The user apparatus UE1 may report to the user apparatus UE2 with the SCI (PSCCH) index of DMRS/RS mapping pattern, mapping contents (such as which RS has been mapped to which symbol) to the symbols of DMRS/RS (especially precoded DMRS), and/or the index of the applied precoder cycling pattern (specifically, in the case of an RS not being precoded).
Each information to be reported is, for example, preconfigured information or information set from an upper layer (e.g., configuration by RRC signaling from the base station 10), or the like.
The following illustrates a functional configuration example of the user apparatus UE and the base station 10 that execute the processing operations described so far. The user apparatus UE and the base station 10 may have all the functions of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, etc., may have functions of only one of the five embodiments, or may have functions of four, three or two of the five embodiments.
The signal transmission unit 101 configured to create a transmission signal from the transmission data and wirelessly transmit the transmission signal. The signal receiving unit 102 configured to wirelessly receive various signals and acquire signals of a higher layer from the received signals of the physical layer. Each of the signal transmission unit 101 and the signal receiving unit 102 includes a D2D function and a cellular communication function. The signal transmission unit 101 includes a function of executing the signal transmission operations described in the first to fourth embodiments and others, and the signal receiving unit 102 includes a function of executing the signal receiving operations described in the first to fourth embodiments and others.
The setting information storage unit 103 is configured to store various configuration information received from the base station 10 via the signal receiving unit 102 and store configuration information in advance. For example, the setting information storage unit 103 is configured to store a plurality of precoding matrices.
The signal transmission unit 101 is configured to precode a D2D signal and transmit the precoded D2D signal while switching a precoding matrix among the plurality of precoding matrices in a time domain, in a predetermined time interval including a plurality of unit time intervals. For example, the signal transmission unit 101 maps reference signals precoded with the same precoding matrix to at least two unit time intervals in the predetermined time interval.
Further, the signal transmission unit 101 may also map reference signals that are not precoded in at least one unit time interval in the predetermined time interval. Further, the setting information storage unit 103 stores a plurality of types of patterns indicating a time sequence, in which a plurality of precoding matrices are to be applied, and in a case of precoding the D2D signal according to a specific pattern among the plurality of types of patterns, the signal transmission unit 101 may transmit control information including information corresponding to the specific pattern. The signal transmission unit 101 may cyclically shift a pattern indicating a time sequence, in which a plurality of precoding matrices are to be applied, to precode the D2D signal while switching a plurality of patterns. The signal transmission unit 101 may transmit control information including information corresponding to the cyclic shift used for the precoding of the D2D signal.
The signal transmission unit 201 includes a function of generating a signal to be transmitted to the user apparatus UE and transmitting the signal wirelessly. The signal receiving unit 202 includes a function of receiving various signals transmitted from the user apparatus UE and acquiring, for example, information of a higher layer from the received signal.
The signal transmission unit 201 includes a function of executing the operation of transmitting a signal (e.g., setting information) to the user apparatus UE as described in the first to fourth embodiments and others.
The setting information storage unit 203 stores various setting information to be transmitted to the user apparatus UE, various types of setting information received from the user apparatus UE, and preset setting information. The NW communication unit 204 is configured to execute information communication between base stations, for example.
The block diagrams (
Further, each of the user apparatus UE and the base station 10 in one embodiment of the present invention may function as a computer that performs the process according to this embodiment.
In the following description, the term “device” may be replaced with a circuit, an apparatus, a unit, or the like. The hardware configuration of the user apparatus UE or the base station 10 may be configured to include one or more of the respective devices illustrated with reference to 1001 to 1006 in
The functions of the user apparatus UE or the base station 10 are implemented by allowing predetermined software (programs) to be loaded on the hardware such as the processor 1001, the memory 1002, and the like, so as to cause the processor 1001 to perform calculations to control communications by the communication device 1004, and reading and/or writing of data in the storage 1003.
The processor 1001 may, for example, operate an operating system to control the entire computer. The processor 1001 may be configured to include a central processing unit (CPU) having an interface with peripherals, a control device, an operation device, and registers.
In addition, the processor 1001 loads programs (program codes), software modules or data from the storage 1003 and/or the communication device 1004 into the memory 1002, and executes various processes according to the loaded programs, software modules or data. The programs are configured to cause a computer to execute at least a part of the operations described in the above embodiment. For example, the signal transmission unit 101, the signal receiving unit 102, and the setting information storage unit 103 of the user apparatus UE illustrated in
The memory 1002 may be a computer-readable recording medium composed of at least one of a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), a RAM (Random Access Memory) and the like. The memory 1002 may be referred to as a register, a cache, a main memory (a main storage device), or the like. The memory 1002 may store executable programs (program codes), software modules, and the like for implementing a process according to the embodiment of the present invention.
The storage 1003 is a computer-readable recording medium composed, for example, of at least one of an optical disk such as a CD-ROM (Compact Disk ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, and a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, and a key drive), a floppy (registered trademark) disk, and a magnetic strip. The storage 1003 may be referred to as an auxiliary storage device. The above-described storage medium may be, for example, a database, a server, or another appropriate medium including the memory 1002 and/or the storage 1003.
The communication device 1004 is hardware (a transmitting-receiving device) for performing communications between computers via a wired and/or wireless network. The communication device 1004 may also be referred to as a network device, a network controller, a network card, a communication module, or the like. For example, the signal transmission unit 101 and the signal receiving unit 102 of the user apparatus UE may be implemented by the communication device 1004. Further, the signal transmission unit 201, the signal receiving unit 202, and the NW communication unit 204 of the base station 10 may be implemented by the communication device 1004.
The input device 1005 is configured to receive an input from the outside. Examples of the input device include a keyboard, a mouse, a microphone, a switch, a button, and a sensor. The output device 1006 is configured to generate an output to the outside. Examples of the output device include a display, a speaker, and an LED lamp. Note that the input device 1005 and the output device 1006 may be integrated (e.g., a touch panel).
In addition, the respective devices such as the processor 1001 and the memory 1002 may be connected by a bus 1007 for mutually communicating information with one another. The bus 1007 may be composed of a single bus or may be composed of different buses between the devices.
Further, the user apparatus UE or the base station 10 may include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array). Alternatively, a part or all of the functional blocks of the user apparatus UE or the base station eNB may be implemented by those hardware components. For example, the processor 1001 may be implemented with at least one of these hardware components.
As described above, an aspect of an embodiment may provide a user apparatus for use in a radio communication system that supports D2D communication. The user apparatus includes a setting information storage unit configured to store a plurality of precoding matrices; and a signal transmission unit configured to precode a D2D signal and transmit the precoded D2D signal while switching a precoding matrix among the plurality of precoding matrices in a time domain, in a predetermined time interval including a plurality of unit time intervals, where the signal transmission unit maps a reference signal precoded by the same precoding matrix to at least two unit time intervals in the predetermined time interval.
According to the above-described configuration, a user apparatus is enabled to apply a precoding vector switch to appropriately perform D2D communication, in a radio communication system supporting D2D communication. Specifically, according to the above-described configuration, the reference signal precoded by the same precoding matrix is mapped to at least two unit time intervals, which enables the receiver side to appropriately perform channel estimation.
Further, an aspect of an embodiment may provide a user apparatus for use in a radio communication system that supports D2D communication. The user apparatus includes a setting information storage unit configured to store a plurality of precoding matrices; and a signal transmission unit configured to precode a D2D signal and transmit the precoded D2D signal while switching a precoding matrix among the plurality of precoding matrices in a time domain, in a predetermined time interval including a plurality of unit time intervals, where the signal transmission unit maps an unprecoded reference signal to at least one unit time interval in the predetermined time interval.
In addition, an aspect of an embodiment may provide a technology that enables a user apparatus to apply a precoding vector switch to appropriately perform D2D communication, in a radio communication system supporting D2D communication. According to the above-described configuration, the user apparatus maps unprecoded reference signals, which enables the user apparatus to achieve relatively compact implementation.
The setting information storage unit stores a plurality of types of patterns indicating a time sequence, in which a plurality of precoding matrices are to be applied, and in a case of precoding the D2D signal according to a specific pattern among the plurality of types of patterns, the signal transmission unit transmits control information including information corresponding to the specific pattern. According to the above-described configuration, the user apparatus is enabled to change a pattern as needed to flexibly manage interference according to an interference situation.
The signal transmission unit may cyclically shift a pattern indicating a time sequence, in which a plurality of precoding matrices are to be applied, to precode the D2D signal while switching a plurality of patterns. According to the above-described configuration, the user apparatus is enabled to change a pattern by cyclically shifting the pattern to flexibly manage interference according to an interference situation.
The signal transmission unit may transmit control information including information corresponding to the cyclic shift used for the precoding of the D2D signal. According to this configuration, the receiver side is enabled to easily identify the pattern used by the transmitter side.
The embodiments have been described as described above; however, the disclosed invention is not limited to these embodiments, and a person skilled in the art would understand various variations, modifications, replacements, or the like. Specific examples of numerical values have been used for encouraging understanding of the present invention; however, these numeric values are merely examples and, unless otherwise noted, any appropriate values may be used. In the above description, partitioning of items is not essential to the present invention. Matters described in more than two items may be combined if necessary. Matters described in one item may be applied to matters described in another item (as long as they do not conflict). In a functional block diagram, boundaries of functional units or processing units do not necessarily correspond to physical boundaries of parts. Operations of multiple functional units may be physically performed in a single part, or operations of a single functional unit may be physically performed by multiple parts. The order of steps in the above described operating procedures according to an embodiment may be changed as long as there is no contradiction. For the sake of convenience, the user apparatus UE and the base station 10 have been described by using functional block diagrams. These apparatuses may be implemented by hardware, by software, or by combination of both. The software which is executed by a processor included in the user apparatus UE according to an embodiment and the software which is executed by a processor included in the base station 10 may be stored in a random access memory (RAM), a flash memory, a read-only memory (ROM), an EPROM, an EEPROM, a register, a hard disk drive (HDD), a removable disk, a CD-ROM, a database, a server, or any other appropriate recording medium.
Further, reporting of information is not limited to the aspects/embodiments described in this specification, and may be performed in other ways. For example, reporting of information may be performed by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, broadcast information (MIB (Master Information Block) and SIB (System Information Block)), and other signals or a combination thereof. Further, RRC signaling may be referred to as an RRC message, and may be an RRC connection setup (RRCC connection setup) message, an RRC connection reconfiguration (RRCC connection reconfiguration) message, or the like.
Each aspect/embodiment described herein may be applied to LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G, 5G, FRA (Future Radio Access), W-CDMA (registered trademark), GSM (registered trademark), CDMA 2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), and a system that utilize other suitable systems and/or a next generation system expanded based on such a system.
The order of processes, sequences, flowcharts, etc. of each aspect/embodiment described in the present specification may be exchanged as long as there is no inconsistency. For example, for the methods described herein, elements of the various steps are presented in an exemplary order and are not limited to the specific order presented.
The specific operation that is performed by the base station 10 in this specification may be performed by its upper node in some cases. In a network composed of one or more network nodes having a base station 10, it is clear that the various operations performed for communication with the user apparatus UE may be performed by other network nodes than the base station 10 and/or the base station 10. Examples of such other network nodes include, but not limited to, MME or S-GW. In the above embodiments, a case where there is one network node other than the base station 10 is described; however, a plurality of other network nodes other than the base station 10 may be combined (e.g., MME and S-GW).
Aspects/embodiments described in this specification may be used alone or in combination, or may be switched in accordance with execution.
The user apparatus UE may also be referred to, by those skilled in the art, as a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, a access terminal, a mobile computer, a wireless terminal, a remote terminal, a mobile subscriber station, a access terminal, a mobile computer, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or several other suitable terms.
The base station 10 may also be referred to, by those skilled in the art, as NB (Node B), eNB (enhanced Node B), Base Station, gNB, or several other suitable terms.
As used herein, the terms “determining” and “deciding” may encompass a wide variety of actions. The terms “determining” and “deciding” may be deemed to include, for example, judging, calculating, computing, processing, deriving, investigating, looking up (e.g., searching tables, databases or other data structures), and ascertaining. Further, the terms “determining” and “deciding” may be deemed to include, for example, receiving (e.g., receiving information), transmitting (e.g., transmitting information), input, output, and accessing (e.g., accessing data in memory). Moreover, the terms “determining” and “deciding”, may be deemed to include, for example, resolving, selecting, choosing, establishing, and comparing (comparing). In other words, the terms “determining” and “deciding” may be deemed to include, “determining” and “deciding” to take some action.
As used herein, the phrase “based on” does not mean “based only on” unless explicitly stated otherwise. In other words, the phrase “based on” means both “based only on” and “based at least on”.
As long as “include”, “including”, and variations thereof are used in the specification or claims, these terms are intended to be inclusive in a manner similar to the term “comprising”. Furthermore, the term “or” used in the specification or claims is intended to be not an exclusive “or”.
In the entirety of the present disclosure, articles, such as a, an, or the in English that are added to a noun term by translation may indicate a plurality of the noun terms unless the articles obviously indicate a singular noun from the context.
The present invention has been described in detail above; it will be obvious to those skilled in the art that the present invention is not limited to the embodiments described herein. The present invention may be implemented as revised and modified embodiments without departing from the spirit and scope of the present invention as defined by the scope of the claims. Therefore, the present specification is described for the purpose of illustrating examples and does not have any restrictive meaning to the present invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/017312 | 5/2/2017 | WO | 00 |
