Method, computer program product, and device implemented by a device transmitting a reference signal - Patents.com

Abstract

To provide a method implemented by a device to transmit a reference signal (RS) in a device-to-device (D2D) communication in a wireless communication system.SOLUTION: A base station and a transmitting device configure the transmitting device by the base station and the transmitting device itself S1; and, according to a configuration result, evaluate communication conditions related to radio channels between the transmitting device and receiving devices and / or to parameters of D2D communication S3. On the basis of the evaluated communication conditions, the transmitting device selects an RS pattern S5 and transmits information relative to the selected RS pattern to the receiving devices S7.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to device to device communications in wireless communication systems.

[0002] The invention more precisely relates to the implementation of Reference Signals (RS) in inter-device communication. [Background technology]

[0003] In device-to-device communication, the LTE standard requires that a transmitting device inserts RS according to a unique predefined RS pattern, which has a high time density.

[0004] In wireless communication, whenever communication is established between a radio base station and a mobile terminal, the radio base station determines an optimal RS pattern based on its knowledge of uplink / downlink channel state information and / or interference profile, and configures the mobile terminal to receive or transmit the RS pattern that the radio base station determines to be optimal. In device-to-device communication, in some scenarios, the radio base station cannot determine an optimal RS pattern to be implemented by the mobile device for sidelink communication (i.e., communication with another device). In practice, for example, two communication devices may be outside the area covered by the radio base station. In another example, the radio base station may not have enough information on the conditions of device-to-device communication to determine an optimal RS pattern. Therefore, the RS pattern implemented in device-to-device (D2D) communication in LTE (especially in V2X systems) is always the same and is designed to handle the worst case. In practice, this allows the receiver to retrieve data transmitted by the transmitter in D2D communication even when the communication path is poor (e.g., when the receiver and / or transmitter are moving at a very high speed).

[0005] Therefore, by using the RS pattern specified in LTE for D2D communication, it is possible to perform correct channel estimation and to properly decode the wireless signal even in the worst case, for example, when the wireless channel fluctuates significantly.

[0006] However, when the radio channel is not too bad, e.g. when the radio channel variations are the least severe, the RS pattern implemented in LTE for D2D communication will result in transmitting an unnecessarily large amount of RS, resulting in a decrease in the utilization efficiency of radio resources.

[0007] In addition, in new radio (NR) standards or modern mmWave systems, such as 5G, which is currently being standardized, operations performed at high carrier frequency levels are subject to strong and fast variations in the radio channel due to various causes such as phase noise, carrier frequency offset, Doppler effect, etc. This makes tracking of the channel state difficult, since strong variations can occur between two successive transmissions of an RS. In the worst case, new systems may require even higher time density RS patterns than in the LTE standard. Therefore, implementing such RS patterns in D2D communication involves a significant amount of radio resource waste. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to improve the above situation. [Means for solving the problem]

[0009] Therefore, the present invention relates to a method implemented by a device transmitting a reference signal (RS) in device-to-device (D2D) communication in a wireless communication system, the method comprising: selecting, by the device, an RS pattern from a set of at least two RS patterns according to a communication condition; -Emitting a radio signal for D2D communication transmitting an RS set according to the selected RS pattern; Includes.

[0010] The present invention enables a transmitting device in a D2D communication, i.e. a device that transmits data directly to other devices, to adapt the amount of RS in the radio signal and their location in time and frequency according to the conditions of the D2D communication. The communication conditions can be determined by the device, for example by determining the relative speed with another device with which it is involved in D2D communication. To determine the communication conditions, the device can use information transmitted by other devices with which it is or will be involved in D2D communication (e.g. via feedback on a sidelink control channel, synchronization sequences, and / or reference signals, etc.) or transmitted by a radio base station if the device is within the area covered by the base station. Based on those communication conditions, the transmitting device (the device emitting the radio signal) selects an RS pattern.

[0011] The RS pattern implemented by the transmitting device will be selected to optimize the amount of RS and their location (in frequency and / or time) according to the communication conditions, e.g., the quality of the radio channel and the communication parameters of the devices involved in the D2D communication (transmission scheme, subcarrier spacing, etc.) The base station may not be aware of the RS pattern selected by the transmitting device.

[0012] Therefore, this allows having a correct channel estimate and properly decoding the wireless signal at the receiver side without wasting radio resources by transmitting unnecessary amounts of RS.

[0013] In addition, the device can select an RS pattern adapted to the communication parameters of the device. For example, the RS pattern can be selected according to the waveform used to generate the wireless signal, such as DFTsOFDM or OFDM. Using the RS pattern adapted to the communication parameters can also improve the decoding of the wireless signal at the receiver side. For example, when data and RS are mixed in the same symbol, in DFTsOFDM (also known as SC-FDMA), it is preferable to insert the RS together with the data in the pre-DFT domain, rather than in the frequency domain as in CP-OFDM, to keep the signal low peak-to-average power ratio. Therefore, the patterns used for different waveforms are different. Moreover, if the insertion of RS in the frequency domain needs to be performed in DFTsOFDM, for example, to use the same frequency domain pattern as CP-OFDM and reduce the specification effort, the data / RS multiplexing in the same symbol must be prohibited or follow a specific repetition and / or phase shift rule to ensure a good peak-to-average power ratio. In such cases, in order to control the total RS overhead, the constraints on the density patterns in the time domain for DFTsOFDM can be different from those for CP-OFDM, and therefore the patterns used for different waveforms are different.

[0014] The reference signal in the present invention encompasses all symbols known by the receiver in terms of their values ​​and their positions, based on which the receiver can estimate the effects of the channel between the transmitter and the receiver, and (in the case of non-transparent transmission schemes) the transformations performed by the transmitting device resulting in a radio signal. For example, based on a received version of the reference signal (e.g., a version corrupted by the channel, noise and / or phase noise, etc.), the receiver can estimate the channel and / or improve the channel estimation quality. It should be noted here that the channel encompasses all effects including propagation and hardware effects such as non-linearity, phase noise, Doppler, carrier frequency offset, etc.

[0015] In the case of NR, these RSs can be, for example, PTRS, DMRS, SRS, CSI-RS, or RSs used for various purposes such as positioning, discovery, etc.

[0016] An RS pattern is a pattern that specifies the locations of RSs. These locations can be defined in several ways.

[0017] An RS pattern may specify the location in time (also referred to as time position) and the location in frequency that an RS will occupy.

[0018] For example, in LTE V2X, for each sidelink channel, one single RS pattern specifies the possible positions and number of DMRSs to be inserted by a mobile transmitter in a sidelink transmission in the context of cellular V2X communication. For example, for an LTE sidelink shared channel, the DMRSs are positioned at time positions 2 and 5 (i.e., at the third and sixth symbols) of the first slot in a subframe, and at time positions 1 and 4 (i.e., at the second and fifth symbols of the second slot) of the subframe. Here, a subframe always contains 14 symbols. In a specified symbol, all subcarriers are occupied by RSs. In another example, for an SC-QAM, SC-FDE scheme, or other transmission scheme based on processing blocks of symbols, each block of symbols is transformed into an SC-QAM / SC-FDE symbol by an SC-QAM / SC-FDE modulator, and the RS pattern may specify the time position (i.e., the position of the SC-QAM / SC-FDE symbol carrying the RS within a suite of SC-QAM / SC-FDE symbols) and the position occupied by the RS within each block of symbols containing the RS at the input of the SC-QAM / SC-FDE modulator. For example, if a dedicated RS symbol is utilized (there is no RS / data mix in one symbol), the RS pattern may specify only the time position.

[0019] The RS pattern may specify the time position and pre-DFT position occupied by the RS. For example, if the transmitting device implements a DFTs OFDM scheme with pre-DFT RS insertion, the RS pattern may specify the DFTs OFDM symbols that contain the RS and the position occupied by the RS at the input of the DFT for those DFTs OFDM symbols that contain the RS.

[0020] The locations in time and / or frequency are the resource units located at these time and / or frequency locations, possibly the smallest resource units. The frequency locations are often the subcarriers used to carry this RS (or resource unit) allocated resource. The time locations are often the symbols in which this RS resides. The pre-DFT location is the location of the RS within the block of symbols present at the input of the DFT of the DFTs OFDM modulator as described in FIG. 2.

[0021] Device-to-device communication is direct communication between at least two devices without traversing a wireless base station.

[0022] Communication conditions are conditions related to the wireless channel between devices involved in D2D communication and / or parameters of this D2D communication (communication parameters).

[0023] The set of RS patterns includes several different RS patterns, which make it possible to cover different situations, i.e. different situations according to communication conditions. Thus, at least one RS pattern in the set of RS patterns corresponds to a first situation of communication conditions, and another RS ​​pattern in the set of RS patterns corresponds to a second situation of communication conditions.

[0024] Emitting a wireless signal according to a selected RS pattern means emitting a wireless signal transmitting an RS set according to a selected RS pattern, i.e., inserting RSs according to a position defined by the selected RS pattern, i.e., carrying each RS on a specific subcarrier in a specific symbol or at a specific pre-DFT position in a specific symbol. If a frequency position is defined in the RS pattern, each symbol can carry one or several RSs, i.e., on one or several subcarriers. A series of symbols is output by the transmitting device, and each symbol of the series of symbols may or may not include one or several RSs according to the RS pattern. This series of symbols is then transmitted through a wireless signal.

[0025] The symbol into which the RS is inserted is a symbol transmitted through a wireless signal, for example, an OFDM symbol or a DFTsOFDM (DFT spread OFDM) symbol.

[0026] According to one aspect of the present invention, the device transmits information regarding the selected RS pattern.

[0027] This allows a device receiving a wireless signal in a D2D communication to be informed of the RS pattern according to which the RS was inserted in the wireless signal emitted by the transmitting device. The receiving device therefore requires less calculations to determine the location of the RS in the wireless signal. Hence, less calculations are required to process the RS and infer the effect of the wireless channel on the wireless signal and / or the transmission scheme used by the transmitting device (if it is a non-transparent transmission scheme).

[0028] The information regarding the selected RS pattern is any information that enables the receiving device to determine the RS pattern.

[0029] This information can be explicit information, e.g., a value from an index mapped to a set of RS patterns. This information can be configured in a field in the sidelink control channel, i.e., a control channel dedicated to D2D communication. In another example, each RS pattern can be represented by an index of the symbol containing the RS, or by the number of symbols containing the RS. Thus, a field in the sidelink control channel can signal these numbers. If for at least one of these numbers several RS patterns are available in the set of RS patterns, a second information can be transmitted in the sidelink control channel representing the level of density of the RS in the frequency domain, i.e., an indication of the number (or average number) of subcarriers carrying the RS in each symbol containing the RS, e.g., a value of low frequency density, a value of medium density, and a value of high density.

[0030] In another example, an RS pattern can be represented by its number of RSs. In case some RS patterns in a set of RS patterns have the same number of RSs, second information can be transmitted along with the number of RSs in the sidelink control channel to distinguish them.

[0031] This information may be implicit information that allows the receiving device to determine the RS pattern to be used without being explicitly identified by information transmitted by the transmitting device. For example, the receiving device may determine the RS pattern to be used based on a common set of rules known by both the receiving device and the transmitting device and / or based on information related to other purposes. For example, the information related to other purposes may be an indication to a slot configuration, an indication of a configuration of other types of RSs, and / or an indication regarding parameters of the communication, or any other information that does not explicitly indicate a particular RS pattern. In another example, the number and / or exact location of RSs in the frequency domain (or pre-DFT domain) depends on the communication conditions.

[0032] An RS pattern can be identified by information that jointly represents the time and frequency (or pre-DFT) location of the RS. Hence, all possible patterns are uniquely identified. An RS pattern can be identified by separate information for the time location of the RS and the frequency (or pre-DFT) location of the RS. Thus, part of this information can be implicitly inferred and does not need to be signaled, reducing signaling overhead.

[0033] According to one aspect of the present invention, at least one RS pattern in the set of RS patterns corresponds to a pattern in which a number X of symbols includes RS. One RS pattern in the set of RS patterns corresponds to a pattern in which a number Y of symbols includes RS, the number Y being different from the number X. The symbols of each pattern are symbols output by a transmission scheme used by a device to transmit a wireless signal.

[0034] Therefore, at least two RS patterns in the set of RS patterns have different numbers of symbols containing RS, which enables the transmitting device to select from the set of RS patterns an RS pattern with a larger number of RS symbols that is more suitable when the wireless channel has significant variations, and an RS pattern with a smaller number of RS symbols that is more suitable when the wireless channel has moderate or low variations and the wireless resource is better utilized.

[0035] The numbers X and Y are set between 1 and the maximum number of symbols in a time unit of the partitioning scheme. The partitioning scheme divides the wireless signal into time units (i.e., groups of symbols). Unless otherwise stated, a time unit is defined by the number of symbols in a group of symbols.

[0036] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being a number of symbols in a time unit of a partitioning scheme, the partitioning scheme dividing the wireless signal into a number of time units.

[0037] Therefore, the selection of the RS pattern is made at least according to the number of symbols in a time unit of the partitioning scheme.

[0038] A time unit of the partition scheme (or time partition scheme) is a time division of a signal within a time unit. That is, a wireless signal can be divided into several time units. Each of the time units is divided into several symbols. Advantageously, each RS pattern of the set of RS patterns is completely defined on a time unit. That is, when inserting an RS according to the RS pattern, the position of the RS is the same for each time unit.

[0039] The number of RS symbols can be seen as the number of RS symbols for a given time unit.

[0040] In the LTE and NR standards, the time unit is a subframe or a slot or minislot, respectively. In LTE, a slot contains 6 or 7 symbols, and a subframe contains 2 slots, i.e., 12 or 14 symbols. In NR, the number of symbols in a slot can range from 2 to 14 symbols.

[0041] When the number of symbols in a time unit increases, for example, it is necessary to have more symbols containing RS in order to achieve a corresponding channel estimation quality, and therefore, an RS pattern having a larger number of symbols containing RS in a time unit can be selected.

[0042] When the number of symbols in a time unit is reduced, it is possible to have fewer symbols containing RS, for example, to reduce the number of symbols containing RS so as to avoid using more resources to transmit RS while achieving a corresponding channel estimation quality. Therefore, an RS pattern having a smaller number of symbols containing RS in a time unit can be selected.

[0043] For example, in NR, when a small slot, e.g., a slot containing 4 symbols, is used for D2D communication, it is advantageous to use a pattern with a smaller number of RSs than when a large slot, e.g., a slot containing 14 symbols, is used.

[0044] According to one aspect of the invention, the selection of the RS pattern is made according to at least one of the communication conditions, said at least one of the communication conditions being the time domain duration of the symbols used for D2D communication.

[0045] Therefore, the selection of the RS pattern is made at least according to the time domain duration of the symbols used for D2D communication.

[0046] The time domain duration in multicarrier communication can depend on the subcarrier spacing configuration, i.e., the frequency spacing between two adjacent subcarriers. A symbol with a smaller subcarrier spacing configuration can have a longer duration than a symbol with a larger subcarrier spacing configuration.

[0047] New standards such as NR offer the possibility to use different subcarrier spacing configurations within the same carrier. Thus, devices may have the ability to use those different types of subcarriers. More generally, devices may have the ability to transmit data with symbols that have different time domain durations.

[0048] Therefore, different RS patterns can be implemented depending on the time domain duration (or subcarrier spacing configuration) of the symbols used by the device. For example, for a given time unit, when using symbols with a longer duration, it is more advantageous (e.g., advantageous to achieve a corresponding channel estimation quality) to select an RS pattern with a larger number of symbols containing RS than when using symbols with a smaller duration. In fact, when the duration of a symbol is shortened, the time between two symbols carrying an RS is also shortened. Therefore, an RS pattern with a smaller number of symbols carrying an RS can be selected.

[0049] According to one aspect of the invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being a set of resources including resources used by the device for transmitting wireless signals.

[0050] Thus, the selection of the RS pattern is made according to a set of resources that includes at least the resources used by the device transmitting the wireless signal.

[0051] The set of resources is for example a resource pool and / or a bandwidth portion, i.e. a set of radio resources (resource units) that can potentially be used by the device. To limit interference with cellular communication, at least one resource pool with its own resources can be configured for D2D communication. Also, to address the issue of devices supporting a narrower radio frequency band than that used by the radio base station, a bandwidth portion can be configured where the device is expected to transmit and / or receive. Each of these resource pools or bandwidth portions can be used with a specific RS pattern adapted to the particularity of the resource pool and / or bandwidth portion.

[0052] For example, different resource pools and / or bandwidth portions can be used for different types of services with different requirements, and thus the RS pattern is adapted to the requirements corresponding to a given resource pool / bandwidth portion.

[0053] For example, the set of RS patterns that a device may select from may be constrained by the network depending on the interference profile and / or the type of services that the network plans for scheduling in the same or adjacent bands, and therefore global network performance is not affected by the choices made by devices during device-to-device communication.

[0054] These particular RS patterns may then be included in a set of RS patterns, and the transmitting device may select one of the RS patterns that corresponds to the set of resources from which the device transmits data.

[0055] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being the relative speed between the device and a receiving device or the relative speed between the device and a group of receiving devices.

[0056] Thus, the selection of the RS pattern is made according to at least the relative speed between the device and the receiving device, or the relative speed between the device and a group of receiving devices.

[0057] In D2D communication, the relative speed between the transmitting device and the receiving device affects the wireless channel. More specifically, the higher the relative speed, the more significant the fluctuation of the wireless channel. Therefore, when two devices have a high relative speed between each other, an RS pattern with a large number of RS symbols is better suited for transmission between these devices. In fact, by inserting RS according to an RS pattern with a large number of RS symbols, it is possible to track the fluctuation of the wireless channel more finely and to avoid having a poor estimation of the wireless channel used to transmit symbols that do not contain RS. In contrast, when two devices have a low relative speed between each other, an RS pattern with a lower time density allows the use of wireless resources to be reduced. Therefore, by using an RS pattern adapted to the relative speed between the transmitting device and the receiving device, it is possible to improve the estimation of the channel to properly decode the wireless signal, and at the same time, the use of wireless resources is reduced.

[0058] A device can determine the relative velocity it has with a receiving device based on: -Measurements of the strength and / or signal strength fluctuations of the signal received from the receiving device; - a measurement of the Doppler shift and / or Doppler spread of the signal received from the receiving device, - an indication received from the receiving device of the Doppler shift and / or Doppler spread and / or signal strength performed by the receiving device, - Knowledge of the relative velocity obtained from the transmitting device or from other measurement systems co-located with the receiving device.

[0059] When a transmitting device is engaged in D2D communication with a group of receiving devices, the transmitting device may use an average relative velocity for all or some of the devices in the group of devices, or an average relative velocity obtained using relative velocities weighted according to the signal strength of all or some of the group of receiving devices (i.e. a subset of the devices in the group of receiving devices).

[0060] The relative speed may be a class or range of relative speeds, for example, a rough determination of the range of relative speeds (e.g., pedestrian / vehicle / fast, or low / medium / fast, etc.) is performed.

[0061] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being a type of routing scheme.

[0062] Therefore, the selection of the RS pattern is made at least according to the type of routing scheme used in the D2D communication.

[0063] The type of routing scheme is the range of other devices to which a device will send data. Examples of routing schemes are unicast, broadcast and multicast.

[0064] Unicast and multicast D2D communication is generally a two-way communication that allows feedback. Broadcast communication, on the other hand, is generally a one-way communication where little information about the receiving device is available. Thus, in unicast and multicast communication, the device can obtain more accurate information on the wireless channel, e.g., determine the relative speed between the device and the receiving device, e.g., through feedback or by analyzing previously received wireless signals transmitted from the receiving device. The device can select the RS pattern according to the communication conditions associated with the receiving device. For example, the device selects the RS pattern based on a rule that allows optimizing the performance of the communication by considering the median of the relative speed, the medium of the relative speed, or a weighted sum of the relative speed. If the number of receiving devices is reasonable, e.g., below a predefined threshold, the device can select the RS pattern by taking into account the relative speed between itself and each other receiving device. If the number of receiving devices requires too much processing on the transmitting device, e.g., the number of receiving devices exceeds a threshold, the device can select the RS pattern by taking into account the relative speed of only a subset of receiving devices in the group of receiving devices.

[0065] In the broadcast case, since the device may not have previously received a wireless signal transmitted from the receiving device, the device may select an RS pattern from the set of RS patterns that has the maximum number of RSs (or the maximum number of symbols containing RSs).

[0066] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being the type of modulation and coding scheme.

[0067] Therefore, the selection of the RS pattern is made at least according to the type of modulation and coding scheme used in the D2D communication.

[0068] By selecting the RS pattern of D2D communication according to the type of modulation coding scheme (MCS), it is possible to improve the estimation of the channel to properly decode the wireless signal, and at the same time, the use of wireless resources is reduced. In fact, the robustness of the wireless signal, and therefore the difficulty of decoding this wireless signal, directly depends on the modulation coding scheme used for communication. A modulation scheme with a small amount of symbols and a low coding rate (low order MCS) reduces the sensitivity of the wireless signal to the wireless channel, and therefore reduces the possibility of erroneous decoding. Therefore, an RS pattern with a smaller number of symbols containing RS and a low density in the frequency domain (i.e., low frequency density) may be suitable for properly decoding the wireless signal and at the same time using a reduced amount of wireless resources for RS.

[0069] In contrast, modulation schemes using a significant amount of symbols and high coding rates (higher order MCS) increase the sensitivity of wireless signals to the wireless channel and therefore increase the probability of erroneous decoding. Therefore, RS patterns with a larger number of symbols containing RS and higher density in the frequency domain may be suitable for properly decoding wireless signals.

[0070] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being a type of transmission scheme.

[0071] Therefore, the selection of the RS pattern is made at least according to the type of transmission scheme.

[0072] A transmission scheme is a scheme applied to the data to be transmitted by a device to obtain an emitted radio signal, i.e. a transmission scheme corresponds to different modules that are successively applied to obtain a radio signal.

[0073] By selecting the RS pattern according to the transmission scheme, it is possible to improve the channel estimation for proper decoding of the wireless signal.

[0074] In practice, different transmission schemes require different RS patterns. For example, a transmit diversity scheme such as time-domain precoder vector switching requires that there is at least one RS in each subgroup of symbols in a time unit precoded with the same precoder. In another example, a multi-layer transmission or non-transparent transmission scheme, several orthogonal antenna ports are used, and the transmitting device needs to select an appropriate sequence with a corresponding cyclic shift so that the receiving device can determine which cyclic shift is used by which layer (e.g., the cyclic shifts are selected in ascending order of antenna port numbering, and the reference signal used depends on the mobile device identifier).

[0075] In addition, the radio signal issued from the transmission scheme has a certain waveform that depends on the scheme implemented. For example, a transmission scheme implementing the DFTsOFDM scheme issues a single-carrier waveform. It is advantageous to maintain the properties of the waveform, for example the single-carrier property. To do this, it may be necessary to select a certain RS pattern, i.e. an RS pattern that allows maintaining the properties of the waveform or at least reducing the impact of the insertion of the RS on the properties of the waveform. For example, the single-carrier property in the DFTsOFDM scheme can be maintained by inserting the RS before applying the DFT module of the DFTsOFDM scheme (also known as SC-FDMA). The resulting position of the RS in the time and frequency domains can therefore be constrained by this requirement. Therefore, only certain RS patterns can be adapted for each waveform.

[0076] Therefore, by selecting the RS pattern according to the waveform, it is possible to maintain the characteristics of the waveform issued from the transmission scheme implemented by the device. Moreover, the device can implement several waveforms / transmission schemes.

[0077] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, the at least one of the communication conditions being resource allocation.

[0078] Therefore, the selection of the RS pattern is at least made according to the resource allocation.

[0079] A resource allocation is a radio resource that is allocated to a device and effectively used for transmitting in D2D communication with other devices.

[0080] A device transmits data through resource units allocated to it. Each allocation may differ in size and shape (how the allocated resource units are spread in frequency and time domains). According to the size and shape of the resource allocation, some RS patterns may be better adapted. For example, an allocation of short duration, e.g., fewer symbols in a time unit, and / or a narrow allocation in frequency domain, a pattern that maintains a desired density of RS (in time and / or frequency domain) may be selected. Thus, adapting the insertion of RS according to the allocation of resources used by the device in D2D communication allows maintaining the relative density of RS and therefore improving the estimation of the channel to properly decode the wireless signal, while at the same time reducing the usage of wireless resources.

[0081] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, which is an identifier of the transmitting device and / or an identifier of the receiving device and / or an identifier of a group of receiving devices. Thus, the interference from among the RSs corresponding to different transmissions can be randomized, and thus the system performance is improved. Thus, if the transmitting device and the receiving device and / or the group of receiving devices have knowledge of said identifiers, there is no need to transfer the second information, and the signaling overhead is reduced.

[0082] According to one aspect of the present invention, the selection of the RS pattern is - obtaining values ​​corresponding to communication conditions; -Th i ≦Th i+1 and for each interval [Th i ;Th i+1 [or]Th i ;Th i+1 ] corresponds to a subset of the set of at least two RS patterns, and we define the values ​​as thresholds Th0, ..., Th n and comparing it with the set of - selecting an RS pattern from the subset corresponding to the interval within which the value lies; Includes.

[0083] A value corresponding to a communication condition is a value obtained based on at least one of the communication conditions sought by the device, and more advantageously on some or all of the communication conditions sought by the device. For example, a condition value (e.g., a level) can be associated with each communication condition, and the value can be obtained as a weighted sum of these condition values.

[0084] This allows for efficient configuration of devices by transmitting only a set of thresholds to the device. In practice, only a set of thresholds is transmitted, and therefore each segment [Th i ;Th i+1 ] is Th i ≦Thi+1 Whatever value is obtained by the threshold value assumed to be , corresponds to the i-th subset of RS patterns previously defined. Therefore, the configuration can be performed by simply changing the threshold value, e.g., Th to disable the i-th subset of RS patterns. i =Th i+1 This can be easily accommodated by setting

[0085] Configuration of the device can be done by the network via a radio base station if the device is within the coverage of the base station.

[0086] A default configuration may be provided, i.e., certain thresholds may be defined and known by all devices. If the sending device uses thresholds different from the default configuration, information about these different thresholds is forwarded to the receiving device. The configuration of the device may be dependent on the geographic area in which the device is located, so that all devices in a given geographic area have a common understanding of the thresholds.

[0087] According to one aspect of the invention, the selection of the RS pattern is made according to at least one of the communication conditions, said at least one of the communication conditions being the type of information to be transmitted.

[0088] For example, different types of information, such as basic data, control data, safety-related information, etc., may have different requirements on reliability. For data with high reliability requirements, an RS pattern with more RSs is needed to ensure good quality of communication.

[0089] According to one aspect of the present invention, the selection of the RS pattern is made according to at least one of the communication conditions, which is the carrier frequency. In reality, the channel profile is different at different carrier frequencies, and there are significant differences in terms of frequency selectivity, phase noise profile, beamforming gain, and Doppler profile. Therefore, the selection of the RS pattern can be made according to the carrier frequency. For example, an RS pattern with more symbols containing RS is needed at higher carrier frequencies. Therefore, the phase effect of the channel can be better compensated. For example, an RS pattern with more RS in the frequency domain is needed at lower carrier frequencies. Therefore, the more frequency selective channel can be better compensated.

[0090] A second aspect of the invention relates to a computer program product comprising code instructions which, when executed by a processor, perform the method described above.

[0091] A third aspect of the present invention is a device that transmits a reference signal (RS) in device-to-device (D2D) communication in a wireless communication system, comprising: a processor; A non-transitory computer-readable medium having instructions stored thereon, the instructions, when executed by a processor, selecting an RS pattern from a set of at least two RS patterns according to a communication condition; Transmitting a radio signal for D2D communication according to the determined RS pattern; and a non-transitory computer-readable medium for configuring a device to The present invention relates to a device comprising:

[0092] The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference symbols refer to similar elements and in which: [Brief description of the drawings]

[0093] [Figure 1] FIG. 2 illustrates a sending device and a receiving device according to the present invention. [Diagram 2] FIG. 2 is a block diagram of an SC-FDMA transmitting device. [Figure 3.1] FIG. 2 is a diagram illustrating an RS pattern according to the present invention in the case of a transmitting device implementing an OFDM scheme. [Figure 3.2] FIG. 2 is a diagram illustrating an RS pattern according to the present invention in the case of a transmitting device implementing an OFDM scheme. [Figure 3.3] FIG. 2 is a diagram illustrating an RS pattern according to the present invention in the case of a transmitting device implementing an OFDM scheme. [Figure 4.1] FIG. 2 is a diagram illustrating an RS pattern according to the present invention in the case of a transmitting device implementing an SC-FDMA scheme. [Figure 4.2] FIG. 2 is a diagram illustrating an RS pattern according to the present invention in the case of a transmitting device implementing an SC-FDMA scheme. [Figure 4.3] FIG. 2 is a diagram illustrating an RS pattern according to the present invention in the case of a transmitting device implementing an SC-FDMA scheme. [Diagram 5] 4 is a flow chart illustrating the steps of emitting a radio signal according to a selected RS pattern according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0094] In Fig. 1, a transmitting device 1.1 is shown emitting a radio signal that is received by a receiving device 1.2. The receiving device 1.2 is in the coverage of the transmitting device 1.1. This transmission can be, for example, an OFDM-based transmission, or for example, SC-FDMA. The receiving device 1.2 and the transmitting device 1.1 are both mobile devices. That is, these devices are involved in D2D communication, for example, vehicle-to-everything (V2X) communication in a standard LTE or NR context. More generally, the transmitting device 1.1 and the receiving device 1.2 can be any type of mobile device, for example, a vehicular communication system, a personal communication device (e.g., user equipment), etc.

[0095] The transmitting device 1.1 comprises one communication module (COM_trans) 1.3, one processing module (PROC_trans) 1.4 and a memory unit (MEMO_trans) 1.5. MEMO_trans 1.5 includes a non-volatile unit for retrieving a computer program and a volatile unit for retrieving the parameters of the transmission scheme (applied modulation scheme, subcarrier spacing configuration, size of slots, etc.) and a set of RS patterns. PROC_trans 1.4 is configured to process data for transmission to the receiving device 1.2 according to the transmission scheme (an example of a transmission scheme is described in FIG. 2) and to insert these RSs, such as positions of RSs in the radio signal corresponding to positions defined in the RS pattern selected by the transmitting device 1.1. COM_trans 1.3 is configured to emit the radio signal. Processing of data intended to be transmitted can also be realized by COM_trans 1.3 instead of PROC_trans 1.4, in which case PROC_trans 1.4 configures COM_trans 1.3 to perform this processing. In practice, the processing may be performed by electronic circuitry dedicated to processing data according to the transmission scheme, or by a processor that processes data according to the transmission scheme, but the invention is not limited to such implementations and encompasses any combination of electronic and computing processing for processing data according to the transmission scheme.

[0096] The receiving device 1.2 comprises one communication module (COM_recei) 1.6, one processing module (PROC_recei) 1.7 and a memory unit (MEMO_recei) 1.8. MEMO_recei 1.8 includes a non-volatile unit for retrieving computer programs and a volatile unit for retrieving parameters of the reception scheme and for storing RS patterns used by the transmitting device 1.1 in D2D communication. PROC_recei 1.7 is configured to process wireless signals received from the transmitting device 1.1 according to the reception scheme. COM_recei 1.6 is configured to receive wireless signals from the transmitting device 1.1. The processing of the wireless signals to retrieve data can also be performed by COM_recei 1.6 instead of PROC_recei 1.5, in which case PROC_recei 1.5 configures COM_recei 1.6 to perform this processing. In practice, the processing can be performed by electronic circuits dedicated to the processing of wireless signals according to the reception scheme or by a processor that processes wireless signals according to the reception scheme. The invention is not limited to such implementations, but encompasses any combination of electronic and computing processing to process wireless signals according to a receiving scheme.

[0097] In the example of Fig. 1, only two devices are represented. However, the present invention is not limited to such one-to-one D2D communication, but also encompasses the case where more than one device is intended to receive the wireless signal. For example, several receiving devices may receive the wireless signal transmitted by the transmitting device 1.1, for example in a multicast or broadcast type transmission.

[0098] A block diagram of a transmitting device 1.1 implementing a Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme is shown in Fig. 2. Such a transmitting device 1.1 can apply the SC-FDMA scheme to a block of M symbols to obtain a radio signal.

[0099] The block of symbols can be obtained by a Modulation and Coding Scheme (MCS) module implementing, for example, a QAM digital modulation scheme or any other digital modulation scheme, where M is the number of allocated subcarriers.

[0100] M symbols (X n ), an M-size DFT2.1 (Discrete Fourier Transform) is applied to the block of M, where n goes from 0 to M-1. At the output of the M-size DFT2.1, M complex symbols are

number

number

[0101] Then, an inverse DFT 2.3 of size N is applied to the vector resulting from the subcarrier mapping module 2.2

number

number

number

number

number

[0102] The D2D communication can be a Multiple-Input Multiple-Output (MIMO) communication. In this case, the transmitting device 1.1 implements a MIMO encoder. A person skilled in the art knows how to implement the SC-FDMA scheme in the case of a MIMO communication implementing T transmitting antennas Txk, where k ranges from 1 to T. That is, the MIMO encoder can be configured, for example, at the output of an M-sized DFT2.1, which for the k-th antenna, calculates a vector of complex symbols input to the MIMO encoder.

number

number

number

number

[0103] A person skilled in the art will understand that the present invention can also be applied with other schemes implemented in the transmitting device 1.1, for example the OFDM scheme, i.e. not by applying DFT 2.1 to a block of M symbols, but by directly mapping these symbols to the M allocated subcarriers of the N existing subcarriers via the subcarrier mapping module 2.2. In the case of MIMO communication described above, implementing the OFDM scheme is done not by applying DFT 2.1 to a block of M symbols, but by directly inputting these M symbols to the MIMO encoder that processes these symbols described above.

[0104] In another variant, the invention can be applied to other types of precoding OFDM schemes by applying other types of precoding instead of the DFT module 2.1. In yet another variant, the invention applies equally to non-multicarrier transmission schemes.

[0105] Figures 3.1 to 3.3 and 4.1 to 4.3 show different possible DMRS insertion patterns for D2D communication in the NR standard with transmission schemes implementing different waveforms.

[0106] Figures 3.1-3.3 refer to insertion patterns used with transmission schemes implementing OFDM-based schemes.

[0107] In NR, a transmission is divided into slots of size 2 to 14 symbols. The depicted slot contains 9 symbols. Each square represents a resource element (RE), i.e., the smallest time-frequency unit. An RE is carried on a unique subcarrier in the frequency domain and a unique symbol in the time domain. That is, an RE represents a subcarrier of a symbol. 12 subcarriers represent a resource block RB, i.e., the smallest resource allocation unit.

[0108] One RS occupies one RE. Thus, the location of the RS (e.g., DMRS) in the RS pattern is shown in gray. Each of Figs. 3.1-3.3 shows RS patterns with different numbers of symbols including RSs. Fig. 3.1 shows a time density of 1 / 9, i.e., one of the nine symbols in a slot includes at least one RS. Fig. 3.2 shows a time density of 2 / 9, i.e., two of the nine symbols in a slot include at least one RS. Fig. 3.3 shows a time density of 3 / 9, i.e., three of the nine symbols in a slot include at least one RS. Figs. 3.1 and 3.3 have the same frequency density, a frequency density of four RSs (or 1 / 3 of the twelve subcarriers in the RB). Fig. 3.2 shows a frequency density of six RSs (or 1 / 2 of the twelve subcarriers in the RB).

[0109] In the NR standard, an RS pattern is completely defined over one slot. Therefore, when an RS pattern is implemented, the RS is inserted at the same position in all slots until another RS ​​pattern is implemented. Therefore, the time density is the number of symbols containing RS divided by the number of symbols in a time unit.

[0110] The transmitting device may inform the receiving device of the RS pattern to be used in D2D communication by transmitting specific information in a field in the sidelink control channel.

[0111] The particular information may be a value from an index that is mapped to a set of RS patterns, such that each value of the index refers to a particular RS pattern.

[0112] The specific information may include a value representing the time density (or the number of symbols containing RS) in the RS pattern, e.g., value 1 for the RS pattern depicted in Fig. 3.1, value 2 for the RS pattern depicted in Fig. 3.2, and value 3 for the RS pattern depicted in Fig. 3.3. If there is at most one RS pattern available for D2D communication per time density in the set of RS patterns, the receiving device 1.2 may derive the RS pattern to be used based on this value.

[0113] For at least one of these numbers, if several RS patterns are available in the set of RS patterns, the specific information may include a second value representing a level of density of RSs in the frequency domain. For example, a value of 1 may represent a low frequency density as represented in Figures 3.1 and 3.3, and a value of 2 may represent a high frequency density as represented in Figure 3.2. Thus, the specific information transmitted through the sidelink control channel is the pair (1;1) for the RS patterns represented in Figure 3.1, the pair (2;2) for the RS patterns represented in Figure 3.2, and the pair (3;1) for the RS patterns represented in Figure 3.3.

[0114] In another example, if several RS patterns are available within the set of RS patterns for at least one of these numbers and / or at least one of these pairs of numbers (e.g., having different positions in the frequency domain or having different values ​​mapped to the same position), the specific information needed to uniquely identify the RS pattern may depend on the communication conditions, such as, for example, the transmitter identifier and / or the receiver identifier and / or the receiver group identifier. In this case, the transmitter selects a pattern based on the communication conditions that are commonly known by the transmitter and the receiver and / or the receiver group, and does not need to transmit any supplementary specific information.

[0115] Figures 4.1 to 4.3 refer to insertion patterns used in conjunction with a transmission scheme implementing an SC-FDMA scheme.

[0116] When implementing such an SC-FDMA scheme, the RS can be inserted in the frequency domain, i.e., after the M-size DFT 2.1 is applied and before the N-size IDFT module 2.3 is applied. Therefore, the RS is inserted in the same manner as in the transmission scheme implementing the OFDM scheme. Therefore, the RS pattern can be represented by the same specific information.

[0117] In addition, when implementing the SC-FDMA scheme, it is advantageous to insert RS in the time domain, i.e., before applying the M-sized DFT2.1. Such insertion makes it possible to maintain the single carrier property of the SC-FDMA scheme. Therefore, among the M symbols input to the M-sized DFT2.1, some of them are set as RS. The RS pattern shown in Figure 4.1 requires that two RSs are inserted among the M symbols (M is equal to 12 on Figures 4.1 to 4.3) input to the DFT2.1. The RS pattern shown in Figure 4.2 requires that four RSs are inserted among the M symbols, and the RS pattern shown in Figure 4.3 requires that six RSs are inserted among the M symbols.

[0118] Similar to the cases of Figs. 3.1 to 3.3, the transmitting device may inform the receiving device of the RS pattern to be used in D2D communication by transmitting specific information in a field in the sidelink control channel.

[0119] The particular information may be a value from an index that is mapped to a set of RS patterns, such that each value of the index refers to a particular RS pattern.

[0120] The specific information may be a value representing the pre-DFT position of the RS pattern, e.g., value 1 for the RS pattern represented in Figure 4.1, value 2 for the RS pattern represented in Figure 4.2, and value 3 for the RS pattern represented in Figure 4.3.

[0121] As in Figures 3.1-3.3, the transmitting device may select pre-DFT locations based on communication conditions such as, for example, the transmitter identifier and / or the receiver identifier and / or the receiver group identifier. In this case, the transmitter selects the exact pattern based on communication conditions commonly known by the transmitter and the receiver and / or the receiver group, and does not need to transmit any supplementary specific information.

[0122] Those skilled in the art will appreciate that Figures 3.1 to 4.3 can be easily substituted for any other type of RS pattern and any frame structure.

[0123] Referring to FIG. 5, a flow chart illustrating the steps of emitting a wireless signal according to a selected RS pattern is shown.

[0124] In step S1, the sending device is configured. The configuration of the sending device 1.1 can be done by the base station and by the sending device 1.1 itself.

[0125] The configuration performed by the base station is performed when the transmitting device 1.1 is within the coverage of this base station, such that the transmitting device 1.1 is configured according to the receiving device 1.2 with which it will be involved in D2D communication.

[0126] The configuration performed by the transmitting device 1.1 itself concerns configuring the communication, i.e. setting the communication parameters (eg transmission scheme, subcarrier spacing, etc.) used by the transmitting device 1.1 in the D2D communication.

[0127] When the transmitting device 1.1 is within the coverage of a base station, the base station can send information to the transmitting device 1.1 for configuring the transmitting device 1.1.

[0128] For example, the base station may set thresholds Th0, ..., Th n A set of values ​​can be sent for each interval [Th i ;Th i+1 [or]Th i ;Th i+1 ] corresponds to the i-th subset of RS patterns. The set of values ​​transmitted by the base station is Th i =Th i+1the base station disables the i-th subset of RS patterns. The values ​​obtained by the boundaries of each interval determine the relevance of the corresponding subset of RS patterns according to the communication conditions. A previously configured set of thresholds can be set as a default configuration. Thus, the receiving device 1.2 involved in the D2D communication knows that the sending device 1.1 will use the configuration in the D2D communication. The subset of RS patterns can be configured by the base station only once or with thresholds.

[0129] In another example, the base station may transmit information related to resource pools and / or bandwidth portions, which allows the transmitting device 1.1 to determine different resource pools and / or bandwidth portions that it may use for D2D communication.

[0130] These configurations of the sending device 1.1 depend on the geographic area in which it is located. Thus, all devices in a given geographic area know a default set of thresholds. In addition, the frequency bands allocated for wireless communication vary from one geographic area to another.

[0131] In step S3, the communication conditions are determined (in other words evaluated). The communication conditions can be determined by the device 1.1 or can be transmitted by the other device 1.2, for example via a sidelink control channel. That is, the transmitting device 1.1 determines the level of the communication conditions or this level is transmitted to the transmitting device 1.1.

[0132] The communication conditions relate to parameters of the wireless channel and / or the D2D communication between the sending device 1.1 and the receiving device 1.2.

[0133] 1. Number of symbols One of the communication conditions may be the number of symbols in a time unit of the partition scheme. In the context of NR D2D communication, this communication condition refers to the number of symbols in a slot that will be used for transmission to the receiving device 1.2. The number of symbols in one slot may range from 2 to 14 symbols. Thus, the transmitting device 1.1 may assign levels 1 to 13 to the sizes of the slots, respectively. In one variant, the transmitting device 1.1 may assign levels to groups of slot sizes, for example level 1 to small size slots (e.g., 2 to 4 slots), level 2 to medium size slots (e.g., 5 to 10 slots), and level 3 to large size slots (e.g., 11 to 14 slots). This reduces the computational complexity for selecting the RS pattern.

[0134] 2. Time domain duration of the symbol One of the communication conditions may be the time domain duration of the symbols used for D2D communication. In the NR standard, especially when using multicarriers implementing several subcarrier spacing configurations, symbols with different durations may be used. The transmitting device 1.1 may assign a level to each subcarrier spacing configuration or a group of subcarrier spacing configurations, for example, level 1 to short duration symbols (with wide subcarrier spacing configuration), level 2 to medium duration symbols (with medium subcarrier spacing configuration), and level 3 to long duration symbols (with small subcarrier spacing configuration).

[0135] 3. Resource Pools and / or Bandwidth One of the communication conditions may be the resource pool and / or bandwidth portion used in D2D communication. In fact, in NR, several resource pools and / or bandwidth portions may be configured in one carrier. Each resource pool and / or bandwidth may be used for a specific service. These services may tolerate different levels of decoding errors. For example, emergency services (using safety-related information) may require a better level of decoding (and therefore an RS pattern with more RSs). In addition, the resource pool and / or bandwidth portion may have different interference profiles, for example, depending on whether the network uses radio resources in the same or adjacent bands. Thus, the transmitting device 1.1 may assign a level according to the resource pool and / or bandwidth portion used for D2D communication.

[0136] In addition, the network may prohibit some of the RS patterns.

[0137] 4. Relative Velocity One of the communication conditions may be the relative speed between a sending device 1.1 and a receiving device 1.2 involved in D2D communication.

[0138] A sending device 1.1 can determine the relative velocity between it and one receiving device 1.2 by measuring: - the strength of the signal received from the receiving device 1.2, - the strength variation of the signal received from the receiving device 1.2, - the Doppler shift of the signal received from the receiving device 1.2, and / or -Doppler spread of the signal received from the receiving device 1.2.

[0139] The relative velocity can also be measured by these methods by the receiving device 1.2 sending an indication as to its relative velocity to the sending device 1.1.

[0140] The relative velocity can also be obtained by other measurement systems co-located with the sending device 1.1 or the receiving device 1.2.

[0141] When D2D communication involves two or more receiving devices 1.2, the transmitting device 1.1 can obtain the relative velocity of each or at least a subset of the receiving devices 1.2 (as described above), based on which the relative velocity of the group of receiving devices 1.2 is obtained.

[0142] The relative velocity of the group can be obtained by calculating: - the average of the relative velocities obtained, or Each of the obtained relative velocities is weighted according to the signal strength and the average of the weighted relative velocities.

[0143] According to the relative speed, or relative speed of the group, the transmitting device 1.1 can assign a level, for example level 1 for low or pedestrian speed, level 2 for medium or vehicular speed, and level 3 for high speed.

[0144] 5. Routing Method One of the communication conditions may be the routing scheme used in the D2D communication.

[0145] In case of unicast and multicast routing schemes, the sender device 1.1 can get feedback on the wireless channel by the receiver device 1.2 or analyze previously received wireless signals sent from the receiver device 1.2. Thus, the sender device 1.1 can assign levels according to the quality of the wireless channel, for example level 1 for high quality wireless channels, level 2 for medium quality wireless channels and level 3 for poor quality wireless channels. If the D2D communication involves several receiver devices 1.2, an average level can be obtained for a group of receiver devices 1.2.

[0146] In the case of a broadcast, the sending device 1.1 may automatically assign a level of 3.

[0147] 6. Modulation Coding Scheme (MCS) One of the communication conditions may be the modulation and coding scheme used in the D2D communication.

[0148] In NR, similar to LTE, several coding schemes and several modulation schemes, i.e. several modulation and coding schemes, are available. The modulation and coding scheme directly affects the data rate and robustness of the signal. Thus, the transmitting device 1.1 can assign levels according to the order of the MCS, for example, level 1 for low order MCS, level 2 for medium order MCS, and level 3 for high order MCS.

[0149] 7. Transmission method and waveform One of the communication conditions may be the transmission scheme and / or waveform used in the D2D communication.

[0150] In NR, several transmission schemes are defined or may be introduced in future releases, such as codebook-based, non-codebook-based, single antenna port transmission, precoder vector cycling in the time or frequency domain, transparent (e.g., cyclic delay diversity) or non-transparent transmit diversity (e.g., Alamouti-based).

[0151] These transmission schemes implement different waveforms, e.g., SC-FDMA or OFDM type transmission schemes. The transmitting device 1.1 can be restricted to a particular RS pattern, e.g., an RS pattern designed for pre-DFT insertion of RS if an SC-FDMA type transmission scheme is used.

[0152] 8. Resource Allocation One of the communication conditions may be resources allocated for D2D communication.

[0153] The sending device 1.1 can assign the levels according to the size and shape of the resource allocation.

[0154] In the above example of levels being assigned according to each particular communication condition, the levels do not differ between the number of symbols containing the RS and the number of subcarriers carrying the RS. However, the levels can be replaced by pairs of levels, one level of the pair affecting the time density of the RS pattern to be selected and the other affecting the frequency density of the RS pattern to be selected.

[0155] Levels can be assigned differently for different communication conditions.

[0156] Once all communication conditions have been determined, the sending device 1.1 can select an RS pattern in step S5 based on these communication conditions. The selection of an RS pattern can also be done if sufficient communication conditions have been determined, i.e. not all communication conditions are determined, but only those groups based on communication conditions that could be determined, for example during a predefined duration.

[0157] In step S5, based on the communication conditions, the transmitting device 1.1 selects an RS pattern.

[0158] For each communication condition, or at least for some of the communication conditions, a level is assigned and / or RS patterns are prohibited and / or the selection is restricted to a subset of RS patterns. Before selecting an RS pattern from the set of RS patterns, the transmitting device 1.1 may remove prohibited RS patterns from the restricted subset of RS patterns and then select an RS pattern from the resulting set of RS patterns.

[0159] To select among the resulting set of RS patterns, the sending device 1.1 obtains a value V corresponding to the communication condition. This value can be obtained by summing the obtained levels for the communication conditions. The summation can be a weighted sum of the levels, and in fact some of the communication conditions may be more relevant and have a more direct influence on the selection of the RS pattern. Once the value V is obtained, the i-th interval ([Th i ;Th i+1 [or]Th i ;Th i+1 The subset of RS patterns corresponding to (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 111, 120, 120, 130, 140, 150, 160, 170, 180, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 199, 199, 199, 19

[0160] In step S7, the transmitting device 1.1 transmits information about the selected RS pattern. This information can be any information that allows the receiving device 1.2 to determine the RS pattern. For example, the specific information is the value described according to Figures 3.1 to 4.3 and is transmitted in a field in the sidelink control channel.

[0161] In another example, this information is implicit, e.g., receiving device 1.2 may determine the RS pattern to be used based on a common set of rules known to both receiving device 1.2 and sending device 1.1 and / or based on information related to other purposes, e.g., information related to other purposes may be an indication to a slot configuration and / or an indication of a configuration of other types of RSs and / or an indication regarding parameters of the communication, or any other information that does not explicitly indicate a particular RS pattern.

[0162] If the sending device 1.1 uses thresholds that differ from those in the default configuration, information about these different thresholds is forwarded to the receiving device 1.2.

[0163] The transmitting device 1.1 emits radio signals for D2D communication according to the determined RS pattern, i.e. emits radio signals including RSs at positions defined in the selected RS pattern.

Claims

1. 1. A method for device-to-device (D2D) communication in a wireless communication system, the method being implemented by a device transmitting a reference signal (RS), comprising: selecting an RS pattern from a set of at least two RS patterns according to a condition related to a communication parameter of the D2D communication; emitting a radio signal for D2D communication according to the selected RS pattern; Including, The selection of the RS pattern is obtaining a value corresponding to a condition related to the communication parameter of the D2D communication; comparing the corresponding values ​​to a set of values, each interval corresponding to a subset of the set of at least two RS patterns; selecting an RS pattern corresponding to the interval within which the corresponding value lies; Including, The method of claim 1, wherein the selection of the RS pattern is made according to at least one of the communication parameters, the communication parameter being a number of symbols in a time unit of a partitioning scheme, the partitioning scheme dividing the wireless signal into groups of symbols.

2. The communication parameters include a time domain duration of a symbol used for the D2D communication. The method of claim 1.

3. determining by the transmitting device a condition related to or the communication parameter of the D2D communication. The method according to claim 1 or 2.

4. transmitting information regarding the selected RS pattern. The method according to any one of claims 1 to 3.

5. At least one RS pattern in the set of RS patterns corresponds to a pattern in which a number X of symbols includes RSs, and one RS pattern in the set of RS patterns corresponds to a pattern in which a number Y of symbols includes RSs, the number Y being different from the number X, and the symbols of each pattern are symbols output according to a transmission scheme used by a device that transmits the wireless signal. The method according to any one of claims 1 to 4.

6. The communication parameter is a time domain duration of a symbol used for the D2D communication. The method according to any one of claims 1 to 5.

7. The communication parameter is a subcarrier spacing configuration used for the D2D communication. The method according to any one of claims 1 to 6.

8. The method of claim 7, wherein the communication parameters are a set of resources including resources used by the transmitting device to transmit the wireless signal. The method according to any one of claims 1 to 7.

9. The communication parameter is a type of routing scheme. The method according to any one of claims 1 to 8.

10. If the type of the routing scheme is broadcast, an RS pattern having a maximum number of symbols containing an RS among the RS patterns of the set of RS patterns is selected.

10. The method of claim 9.

11. The communication parameter is a type of modulation and coding scheme. The method according to any one of claims 1 to 10.

12. The communication parameter is a type of transmission method. The method according to any one of claims 1 to 11.

13. The communication parameter is a waveform type. The method according to any one of claims 1 to 12.

14. The communication parameter is a resource allocation. The method according to any one of claims 1 to 13.

15. The selection of the RS pattern is obtaining a value corresponding to a condition related to the communication parameter of the D2D communication; The corresponding value is Th ｉ ≦Th ｉ＋１ And each section [0010] or [0025] corresponds to a subset of the set of at least two RS patterns. ０ , . . . , Th ｎ and comparing it with the set of selecting an RS pattern corresponding to the interval within which the corresponding value lies; Including, The method according to any one of claims 1 to 14.

16. A computer program comprising code instructions for causing a processor to carry out the method according to any one of claims 1 to 15.

17. A device that transmits a reference signal (RS) in device-to-device (D2D) communication in a wireless communication system, A processor; A non-transitory computer-readable medium having instructions stored thereon, the instructions, when executed by the processor, selecting an RS pattern from a set of at least two RS patterns according to a condition related to a communication parameter of the D2D communication; transmitting a radio signal for D2D communication according to the selected RS pattern; a non-transitory computer-readable medium for configuring the transmitting device to perform the Equipped with The selection of the RS pattern is obtaining a value corresponding to a condition related to the communication parameter of the D2D communication; comparing the corresponding values ​​to a set of values, each interval corresponding to a subset of the set of at least two RS patterns; selecting an RS pattern corresponding to the interval within which the corresponding value lies; The device, wherein the selection of the RS pattern is made according to at least one of the communication parameters, the communication parameter being a number of symbols in a time unit of a partitioning scheme, the partitioning scheme dividing the wireless signal into groups of symbols.

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