Inserting a reference signal for phase tracking

Abstract

The invention relates to a method for inserting a reference signal for phase tracking implemented by a computer device of a communication entity using a discrete Fourier transform extended orthogonal frequency division multiplexing modulator, the method comprising the steps of inserting said reference signal for phase tracking within a series of data samples according to at least one insertion mode selected among predefined modes for predetermined criteria of communication conditions; and feeding said modulator with a series of signal blocks obtained from said series of signal samples to apply a discrete Fourier transform after the insertion of the reference signal for phase tracking. For a phase tracking reference signal (PT‑RS).

Description

[0001] This application is a divisional application of the Chinese invention patent application with application number "201780088245.6", application date "December 27, 2017", and invention name "Inserting reference signal for phase tracking". Technical Field

[0002] The present invention relates to telecommunications and more particularly to methods supporting compensation of time domain phase variations. Background Art

[0003] Various phenomena may cause phase changes in the time domain. For example, the presence of phase noise, frequency or insufficient frequency synchronization due to Doppler shift may produce phase changes in the time domain. Summary of the invention

[0004] Technical issues

[0005] Orthogonal Frequency Division Multiplexing (OFDM) systems appear to be very sensitive to phase noise. For example, it can be noted that OFDM systems are more sensitive to phase noise than subcarrier systems. This is part of the reason why systems that experience significant phase noise environments avoid using OFDM waveforms. Satellite systems are an example of systems that are particularly subject to challenging phase noise environments.

[0006] Time domain effects appear to be easier to monitor and compensate for in the time domain than in the frequency domain. Time domain training sequences are recognized to be particularly effective for phase noise compensation and carrier offset compensation.

[0007] The discrete Fourier transform extended orthogonal frequency division multiplexing (DFTsOFDM) waveform corresponds to a block of bit-interleaved and coded modulation symbols precoded by a discrete Fourier transform (DFT). The number of modulation symbols in a block corresponds to the DFT size and the number of effective subcarriers. Subcarrier mapping is then performed so that an inverse discrete Fourier transform (IDFT) can also be performed. For example, a block of M bit-interleaved and coded modulation symbols is precoded by an M-sized DFT, mapped to M of N subcarriers, and then passed through an N-sized IDFT. A cyclic prefix (CP) may optionally be appended after the IDFT. In this case, DFTsOFDM is referred to as cyclic prefix discrete Fourier transform extended orthogonal frequency division multiplexing (CP DFTsOFDM). CP DFTsOFDM has been used as an uplink (UL) waveform in long-term evolution / advanced long-term evolution (LTE / LTE-A) systems. CP DFTsOFDM will be used as one of the UL waveforms in 5G new radio (5G NR) systems. One of its essential characteristics is a low peak-to-average power ratio (PAPR) which allows the user equipment (UE) to use its high power amplifier (HPA) in an energy efficient manner near its saturation point.

[0008] The modulation symbols obtained from a single codeword may be spread over several DFTs OFDM blocks which are typically contained within a scheduling unit. A scheduling unit, which may be, for example, a slot, a microslot in NR 5G, or a subframe in LTE-LTE-A, is formed by blocks containing reference signals for demodulation and blocks not containing reference signals for demodulation.

[0009] In order to compensate for phase changes in the time domain for millimeter (mm) wave systems that are subject to more severe phase noise environments, a sequence that acts as support is needed. Such a sequence can also be used to compensate for residual carrier frequency offset (CFO) or effects due to Doppler shift. For example, such a sequence can compensate for high speeds in a low dispersion channel. For OFDM systems, it is known to insert sequences at the subcarrier level (in the frequency domain). The advantage of such a sequence inserted in the frequency domain is that it provides support for simpler estimation of phase changes during frequency domain processing at the receiver side. However, it is inconvenient that frequency domain observation of time domain effects cannot be performed at a finer granularity than one OFDM symbol.

[0010] Regarding DFTsOFDM, it is also possible to insert a phase tracking reference signal in the frequency domain at the subcarrier level. In this case, the phase tracking reference signal can be inserted into a carrier not occupied by data or can pierce an occupied subcarrier. The two types of insertion of the phase tracking reference signal for DFTsOFDM in the frequency domain result in a degraded PAPR. Another disadvantage of inserting the phase tracking reference signal into a carrier not occupied by data in the frequency domain is the need to implement DFTs of different sizes. Another disadvantage of inserting the phase tracking reference signal in the frequency domain by piercing the occupied subcarriers is that it can lead to a reduction in demodulation performance.

[0011] Therefore, there is a need to explore additional phase tracking reference signal insertion for DFTsOFDM.

[0012] The object of the present invention is to improve this situation.

[0013] Technical Solution

[0014] The present invention relates to a method for inserting a reference signal for phase tracking implemented by a computer device of a communication entity, wherein the communication entity uses a discrete Fourier transform extended orthogonal frequency division multiplexing modulator. Specifically, the method comprises the following steps:

[0015] - obtaining a series of signal samples by inserting the phase tracking reference signal within a series of data samples according to at least one insertion pattern selected from predefined patterns of predetermined criteria for communication conditions; and - feeding a series of signal blocks obtained from the series of signal samples to the modulator to apply a discrete Fourier transform after inserting the phase tracking reference signal.

[0016] By "pattern" is meant here a predetermined combination of positions expected to be occupied by a phase tracking reference signal in the aforementioned series of signal samples, insertion of the phase tracking reference signal is then performed in the time domain prior to the DFT application.

[0017] By "data sample" is meant a series of samples in the time domain including bit-interleaved encoded modulation symbols to be transferred during transmission. For simplicity, when constructed, any other reference signal samples other than the reference signal for phase tracking are also included here before the DFT (e.g., mobility reference signals, reference signals for fine time / frequency tracking of channels, additional demodulation reference symbols, etc.). The "signal sample" is still obtained in the time domain after inserting the reference signal for phase tracking in the series of data samples. A series of "signal blocks" are then obtained from the series of signal samples and applied to the DFTsOFDM modulator. Typically, the DFTsOFDM modulator is implemented in the frequency domain, and it implements at least a discrete Fourier transform, then a mapping, and then an inverse discrete Fourier transform. An equivalent time domain implementation of DFTsOFDM modulation also exists, but is generally not used in actual implementations due to lack of flexibility and higher complexity.

[0018] Therefore, support for time domain phase error compensation is provided according to the insertion mode due to the insertion of the reference signal for phase tracking. Moreover, advantageously, the selection of a mode among the predefined modes is performed according to a predetermined criterion of the communication conditions. Thus, the mode that best suits the communication conditions can be selected.

[0019] In an embodiment, one of the predetermined criteria of the communication condition is at least one of the following:

[0020] -Scheduling bandwidth;

[0021] -modulation;

[0022] - coding rate;

[0023] - carrier frequency;

[0024] - Physical resource block bundling; or

[0025] -Other reference signal densities.

[0026] Thus, implicit or low signaling mode insertion selection may be performed.

[0027] In an embodiment, a reference signal for demodulation is also inserted into a transformed series of signal blocks generated in the frequency domain by applying a discrete Fourier transform to at least one series of signal blocks. The reference signal for demodulation is inserted into the scheduled positions of the transformed series of signal blocks, but the applied pattern for inserting the reference signal for phase tracking takes these scheduled positions into account.

[0028] Therefore, since the reference signal for demodulation can serve as a support for phase error compensation, taking the position of the reference signal for demodulation into account makes it impossible to insert the phase tracking reference signal close to the reference signal for demodulation, thus it limits the penalty of the maximum achievable throughput.

[0029] In an embodiment, the transformed series of signal blocks includes N data The transformed signal blocks are mapped to M effective subcarriers. Therefore, the selected mode can be determined by D i K separated by data samples i N phase tracking reference signals k Group definitions such as:

[0030]

[0031] Among them, D i When i is different from 0 and N k is a non-zero positive integer.

[0032] In this embodiment, control K i The value of K enables i The phase tracking reference signal is used to control the accuracy of the phase error estimate. i The value of further enables control of the accuracy of interpolation between groups of phase tracking reference signals at the receiver side.

[0033] In implementation:

[0034] In implementation:

[0035] Therefore, the time domain distance between the two sets of phase tracking reference signals is equal and can be set according to a given degree of phase noise variation.

[0036] In implementation: Therefore, the estimates of each set of reference signals for phase tracking are equally reliable.

[0037] In an alternative embodiment:

[0038] In an embodiment: for from 0 to N k -2 for each k, In this embodiment, the set of phase tracking reference signals starts at the same relative position relative to the start of the signal block in each signal block in which the sequence exists, thereby allowing easier demapping implementation.

[0039] In an embodiment, for a range from 0 to Nk For each k of -1,

[0040]

[0041] Therefore, the groups of reference signals for phase tracking end at the same relative positions with respect to the start of the signal block for easier demapping implementation.

[0042] In an embodiment: For each k from 0 to N k -2, K i +D i+1 = + + =Δ, where

[0043] -Δ=M; or

[0044] -Δ<M; or

[0045] -Δ>M.

[0046] In this embodiment, if Δ<M, frequency interpolation allows reliable interpolation between the groups of reference signals for phase tracking. If Δ>M, the overhead K of the reference signals for phase tracking can be reduced by fewer frequency interpolations of the groups of reference signals for phase tracking tot / MN data , where Finally, if Δ=M, equally reliable phase estimation can be performed in each signal block.

[0047] In an embodiment, after the inverse discrete Fourier transform performed by the modulator after the discrete Fourier transform, a non-zero cyclic prefix CP is inserted, and here D i (i = 1...N k -1) can take one of the following two values:

[0048] - the selected integer D', if D i does not span two signal blocks; or

[0049] -D”=D’-E(N CP *M / N), if D i spans two signal blocks, where N CP corresponds to the number of CP samples appended after the inverse discrete Fourier transform, and E(x) specifies the nearest integer of x, and N corresponds to the number of subcarriers related to the inverse discrete Fourier transform.

[0050] In a variant, E(x) specifies the nearest integer below x. In another variant, E(x) specifies the nearest integer above x.

[0051] Hence, a regular insertion is obtained after CP insertion and it enables time domain processing before discrete Fourier transform at the receiver side.

[0052] In an embodiment, D i It may be chosen to avoid inserting a reference signal for phase tracking in a signal block having a position scheduled for a reference signal for demodulation or other reference signal allowing phase tracking (in the frequency domain, or possibly in the time domain according to the invention).

[0053] Another aspect of the present invention relates to a communication device, which uses a discrete Fourier transform extended orthogonal frequency division multiplexing modulator, the device includes a computer circuit, the computer circuit is used to insert a reference signal for phase tracking, and more specifically:

[0054] - obtaining a series of signal samples by inserting said phase tracking reference signal within a series of data samples according to at least one insertion pattern selected among predefined patterns for a predetermined criterion of a communication condition; and

[0055] - feeding a series of signal blocks obtained from the series of signal samples to the modulator for applying a discrete Fourier transform after inserting a reference signal for phase tracking.

[0056] A third aspect of the invention relates to a computer program product comprising instructions for performing the method described previously when run by a processor.

[0057] Other features and advantages of the methods and apparatus disclosed herein will become apparent from the following description of non-limiting embodiments with reference to the accompanying drawings.

[0058] 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 numerals refer to similar elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] [ Figure 1 ] Figure 1 is a flow chart illustrating the different steps of a method for inserting a reference signal for phase tracking.

[0060] [ Figure 2 ] Figure 2 is an example of a representation with a reference signal inserted for phase tracking.

[0061] [ Figure 3 ] Figure 3 is an example of insert mode.

[0062] [ Figure 4 ] Figure 4 is an example of insert mode.

[0063] [ Figure 5 ] Figure 5 is an example of insert mode.

[0064] [ Figure 6 ] Figure 6 is an example of insert mode.

[0065] [ Figure 7 ] Figure 7 is an example of insert mode.

[0066] [ Figure 8 ] Figure 8 is an example of insert mode.

[0067] [ Fig. 9 ] Fig. 9 is an example of insert mode.

[0068] [ Fig.10 ] Fig.10 is a possible implementation of an apparatus for enabling the method of the present invention.

[0069] [ Fig.11 ] Fig.11 Examples of alternative parameters set to describe a pattern sequence are shown.

[0070] [ Fig.12 ] Fig.12 Different embodiments are shown, in which, in the context of uplink communication, pattern insertion is selected by the base station, while insertion of a reference signal for phase tracking is performed by the terminal UE.

[0071] [ Fig.13 ] Fig.13 Different embodiments are shown, in which, in the context of uplink communication, pattern insertion is selected by the base station, while insertion of a reference signal for phase tracking is performed by the terminal UE.

[0072] [ Fig.14 ] Fig.14 Different embodiments are shown, in which, in the context of uplink communication, pattern insertion is selected by the base station, while insertion of a reference signal for phase tracking is performed by the terminal UE. DETAILED DESCRIPTION

[0073] Figure 1 is a flow chart illustrating different steps of a reference signal insertion method for phase tracking according to a possible embodiment of the present invention.

[0074] A sequence of data samples DATA_S101 representing a set of data can be modified by inserting a reference signal for phase tracking internally. The insertion follows a selected mode selected from a set of modes (such as the modes and mode combinations proposed below). The selection of a specific mode can be performed according to the communication criterion COM_CRIT 102. Thus, the communication criterion COM_CRIT102 can enable the insertion mode INS_PAT 103 of the reference signal for phase tracking. Therefore, when the reference signal for phase tracking is inserted according to the selected insertion mode PAT, the data samples can be modified to signal samples SIG_S104. A signal block can be obtained from the signal sample 104 to feed the signal block to the discrete Fourier transform extended orthogonal frequency division multiplexing modulator FEED_MOD 105, and the modulation starts with the discrete Fourier transform DFT 106.

[0075] The selection of the insertion mode PAT is based on the communication criteria COM_CRIT 102, such as the allocation size M (or equivalently the scheduled telecommunication bandwidth), modulation type, coding rate, carrier frequency, PRB (Physical Resource Block) bundling and / or other reference signal density. In addition, a combination of already existing modes can also be selected.

[0076] Figure 2 is an example of a representation of a reference signal inserted for phase tracking according to a possible implementation of the present invention. More specifically, Figure 2 It indicates that K phase tracking reference signal symbols are inserted into a discrete Fourier transform spread orthogonal frequency division multiplexing symbol carrying a phase tracking reference signal.

[0077] exist Figure 2 In the embodiment, a phase tracking reference signal RS_Phase Track 201 and data samples Data 202 are sent to a phase tracking reference signal insertion module RS_PhaseTrack PAT 203, which inserts the phase tracking reference signal into a series of data samples according to at least one insertion mode.

[0078] Consider scheduling units such as mini-slots, time slots or other units. Scheduling units include N sym blocks, where N data The signal blocks do not contain any reference signal for demodulation. data Each of the signal blocks will be mapped to M effective carriers. In module 204, N of the M signal samples may be generated. data signal blocks. Therefore, each block is hereinafter of size M. Module 205 may then send N data Before applying the inverse discrete Fourier transform IDFT 207, N dataand N RS_Demod Subcarrier mapping of blocks. RS_Demod The blocks correspond to blocks including reference signals used for demodulation.

[0079] exist Figure 2 In the example, the demodulation reference signal RS_Demod position is represented by a full pilot in module 206. However, mixed data / pilot symbols are another possible alternative, and the demodulation reference signal is inserted before or after applying the discrete Fourier transform 205 (DFT). After the inverse discrete Fourier transform 207, a cyclic prefix (CP) can be added.

[0080] The phase tracking reference signal may provide support for time domain phase error compensation. However, inserting the phase tracking reference signal may incur a penalty in terms of the maximum achievable throughput.

[0081] For this reason, the density of reference signals for phase tracking should not exceed the minimum density necessary to achieve the performance target. Because other reference signals such as demodulation reference signals or other reference signals (e.g., mobility reference signals, reference signals for fine time / frequency tracking of channels, additional demodulation reference symbols, etc.) can be used as support for phase error compensation when constructed, it may not always be necessary to insert a phase tracking reference signal.

[0082] Figure 3 is an example of an insertion mode according to a possible implementation of the present invention. i K separated by data samples i N phase tracking reference signals k Groups such as:

[0083]

[0084] Among them, D i When i is different from 0 and N k is a non-zero positive integer.

[0085] The number of inserted phase tracking reference signals accounts for the total phase tracking reference signal overhead K tot / MN data yes

[0086] When applying the discrete Fourier transform, the data samples and the reference signal for phase tracking are spread together. Due to the multipath channel, interference may exist between the data samples and the reference signal for phase tracking at the receiver side.

[0087] For a given reference signal overhead for phase tracking, K i Small values ​​of can allow for finer granularity of phase tracking with reference signal insertion (small D i), which is beneficial at the receiver side for interpolation between reference signal groups for phase tracking.

[0088] However, the phase estimate for each phase tracking reference signal group may be degraded due to interference with the data samples. In this case, K i The minimum value of may be above the threshold so that reliable averaging is possible.

[0089] A large phase tracking reference signal group can allow reliable phase estimation within the group with limited noise / interference. However, if the phase tracking reference signal overhead can be kept reasonable, the phase tracking reference signal group can be fairly spaced and it can produce a large D i In this case, interpolation between reference signal groups for phase tracking may not be reliable.

[0090] It can be realized in the overhead K tot / MN data The minimum K under the constraint i With maximum D i A compromise between k -1.

[0091] Other insertion modes can be defined, for example with This mode may allow equally reliable estimation of each set of phase tracking reference signals.

[0092] Another possible insertion mode is to use and to define.

[0093] A variation of the insertion pattern is a cyclic shift of the above insertion pattern.

[0094] Another possible insertion pattern can be defined by the following equation or any cyclic shift of this pattern: Among them, k ranges from 0 to N k -2. Therefore, the phase tracking reference signal group starts at the same relative position relative to the starting point of the signal block in each signal block where the phase tracking reference signal exists. This allows easier demapping. This mode can be combined with other features, such as:

[0095] -N K =N data , thus, a phase tracking reference signal group can exist in each data block,

[0096] -K i can depend on the distance to the nearest location containing other reference signals that can be used for phase estimation,

[0097] - or

[0098] (where k ranges from 0 to N k -1) can define another possible insertion pattern. Any cyclic shift of this pattern is also a possible insertion pattern. Thus, the groups of reference signals for phase tracking end at the same relative position with respect to the start of the signal block for easier demapping implementation. This pattern can be combined with other features, such as:

[0099] -N K = N data : a group of reference signals for phase tracking can exist in each data block,

[0100] -K i can depend on the distance to the nearest position containing other reference signals that can be used for phase estimation, and

[0101] - or

[0102] Equally spaced insertion patterns can be defined by the following formula . Any cyclic shift of this insertion pattern can also be a possibility. Thus, the time-domain distance between two groups of reference signals for phase tracking can be equal and can be set according to the phase noise intensity.

[0103] Regular insertion patterns can be defined by the following formula , where k ranges from 0 to N k -2. Variations of this pattern can be determined by . Different cases can be distinguished depending on the value of Δ. Figure 4 is an example of an insertion pattern according to a possible embodiment of the present invention. In Figure 4 , Δ = M, so equally reliable phase estimation can be performed within each data symbol.

[0104] Figure 6 is an example of an insertion pattern according to a possible embodiment of the present invention. In Figure 6 , Δ < M, and frequency insertion can allow reliable interpolation between groups of reference signals for phase tracking.

[0105] Figure 8 is an example of an insertion pattern according to a possible embodiment of the present invention. In Figure 8 , Δ > M, and the overhead of reference signals for phase tracking can be reduced.

[0106] The irregular insertion pattern can also be implemented when a non-zero cyclic prefix is to be inserted after the inverse discrete Fourier transform. The insertion pattern can also be adapted to this case, and D i (i = 1...N K -1) can take one of two values:

[0107] - the selected integer D', if D i does not span two signal blocks; or

[0108] - D” = D’ - E(N CP *M / N), if D i spans two signal blocks, where N CP corresponds to the number of CP samples appended after the inverse discrete Fourier transform, and E(x) specifies the nearest integer of x, and N corresponds to the number of subcarriers related to the inverse discrete Fourier transform. In a variant, E(x) specifies the nearest integer less than x. In another variant, E(x) specifies the nearest integer greater than x.

[0109] Figure 7 An example of the irregular insertion pattern resulting from the fact that the phase-tracking reference signal is not included in each M-sized signal block here is shown. Thereby, the overhead is reduced.

[0110] Figure 5 is an example of the insertion pattern according to a possible embodiment of the present invention. The irregular insertion pattern can also be defined in the following cases: as can be seen Figure 5 on, D i is selected to avoid inserting the phase-tracking reference signal near the demodulation reference signal position. Therefore, the phase-tracking reference signal density can be reduced by avoiding insertion when the phase error can be corrected with low error by other means such as the following:

[0111] - the signal blocks near the demodulation reference signal position cannot carry the phase-tracking reference signal;

[0112] - X signal blocks near the demodulation reference signal position cannot carry the phase-tracking reference signal;

[0113] - X signal blocks after the demodulation reference signal position cannot carry the phase-tracking reference signal;

[0114] - Y samples (Y < M) adjacent to the demodulation reference signal position cannot carry the phase-tracking reference signal;

[0115] - the irregular pattern can be obtained by removing the phase-tracking reference signal position from the regular pattern;

[0116] - K imay depend on the distance to the nearest location containing other reference signals that can be used for phase estimation;

[0117] -D i may depend on the distance to the nearest location containing other reference signals that can be used for phase estimation;

[0118] - Y samples (Y < M) adjacent to the location containing other reference signals that can be used for phase estimation cannot carry reference signals for phase tracking;

[0119] - The signal block containing other reference signals that can be used for phase estimation cannot carry reference signals for phase tracking;

[0120] - X signal blocks adjacent to the signal block containing other reference signals that can be used for phase estimation cannot carry reference signals for phase tracking.

[0121] An irregular insertion pattern can also be obtained in the following cases: D i is selected to avoid inserting reference signals for phase tracking in a specific signal block. Thereby, the overhead of reference signals for phase tracking can be reduced. For example, reference signals for phase tracking can be inserted only every other signal block. For example, reference signals for phase tracking can be inserted only every Z (e.g., 3, 4) signal blocks.

[0122] As mentioned, combinations of insertion patterns can also be used. The previously mentioned insertion patterns can be based on a master insertion pattern, where the subordinate insertion patterns are characterized by different parameters.

[0123] Fig. 9 is an example of an insertion pattern according to a possible embodiment of the present invention. More specifically, Fig. 9 represents a master pattern with a variable offset L, which variable offset may be introduced into any of the previously defined patterns.

[0124] Fig.11 shows other possible combinations of patterns that can also be used. The patterns can be based on a general master pattern, where the subordinate insertion patterns are characterized by different parameters, such as periodicity, separation between groups of reference signals for phase tracking, offset from the general master pattern, repetition of the pattern within a DFTs OFDM symbol, and / or other parameters.

[0125] An example of a set of parameters describing a sequence is related to Fig.11 The exemplified situation is as follows, where for i = 0... N k - 1, K i = K = 2:

[0126] - The repetition count (rep_time) can indicate how many signal blocks in a time slot contain reference signals for phase tracking;

[0127] - a parameter labeled "td_interv" indicates how many separated signal blocks are signal blocks in a time slot that contain a reference signal for phase tracking; i D when crossing the signal block boundary i The values ​​are:

[0128] D i =[remainder(M / (K+td_interv_inter_symbol))]+td_interv_inter_symbol+M*td_interv;

[0129] - The parameter TD interval within a symbol (labeled td_interv_inter_symbol) indicates the D i D when not crossing signal block boundaries i value.

[0130] Commented above Figure 7 The example of mode implementation shown corresponds to parameters having the following values, assuming that the value K=2 and the shift L=0 are predetermined and / or known by both the transmitter and the receiver.

[0131] -rep_time=4,

[0132] -td_interv=1,

[0133] -td_interv_inter_symbol=4.

[0134] The selectable modes may have some modes identified by the reference signal density (low, medium or high) for phase tracking. Depending on the selected modulation and coding scheme (MCS), one of the aforementioned modes may be associated with the selected MCS. For example, QPSK may be associated with a low density mode, while 16QAM may be associated with a medium density mode. Any modulation order higher than 16 may be associated with a high density mode.

[0135] Fig.10 is a possible implementation of a device enabling the present invention.

[0136] In this embodiment, the apparatus 10 may include a memory 13 storing program instructions that are loadable into the circuit and adapted to cause the circuit 12 to perform the steps of the present invention when the program instructions are executed by the circuit 12. The memory 13 may also store temporary data and other useful information for performing the steps of the present invention as described above.

[0137] The circuit 12 may be, for example:

[0138] a processor or a processing unit adapted to interpret instructions in a computer language, the processor or the processing unit comprising, being associated with or attached to a memory, the memory comprising the instructions; or

[0139] - an association of a processor / processing unit and a memory, the processor or processing unit being adapted to interpret instructions in a computer language and the memory comprising said instructions; or

[0140] - an electronic card in which the steps of the invention are described in silicon; or

[0141] - A programmable electronic chip, such as an FPGA chip (for "Field Programmable Gate Array").

[0142] The aforementioned apparatus 10 may be a terminal (such as a cellular telephone terminal) or simply a part of the terminal implementing the present invention in the context of uplink communication towards a base station, and the apparatus 10 may also be a base station (or a part thereof).

[0143] In the example of uplink transmission (from a terminal UE ("User Equipment") to a base station), compensation of the time domain phase variation will be performed at the receiver side (by the base station). To do this, the base station must know which insertion pattern sequence the terminal UE uses. Figure 12 to Figure 14 In the illustrated embodiment, the terminal UE sends information about communication conditions (such as, for example, the mobility and / or capabilities of the terminal UE) to the base station, and the base station selects the insertion mode based on the aforementioned criteria of the communication conditions derived from the information received from the terminal UE. Figure 12 to Figure 14 In the figure, the reference numerals L1, L2, L3 designate the different layers via which the control information is sent. L1 corresponds to the physical layer, L2 to the medium access control (MAC) layer and L3 to the radio resource control (RRC) layer. Once the base station has selected an appropriate mode (or sequence of modes), the base station sends information to the terminal UE, which allows the UE to determine the selected mode, which is used for inserting a reference signal for phase tracking applied at the terminal UE. For example, the information may be the values ​​of the parameters (rep_time, td_interv and td_interv_inter_symbol) as defined above. For example, the information may be an on / off configuration of a mode, or a density of a set of modes that the terminal UE can determine based on other transferred information, such as modulation and coding rate and / or scheduling bandwidth. Alternatively, the information may also be, for example, a series of bits of a mode index in a coding mode dictionary. In Fig.11 In an embodiment, a single insertion of a phase tracking reference signal is triggered by signaling: the terminal UE should request a single insertion of a phase tracking reference signal. The time slot carrying the phase tracking reference signal is determined based on the time information (predetermined or signaled) given by the transmission interval.

[0144] Therefore, in this embodiment in which the insertion of the reference signal for phase tracking is performed by the terminal (UE) for uplink transmission towards the base station:

[0145] - the terminal sends information related to the communication conditions to the base station,

[0146] - the base station derives said predetermined criterion of the communication condition from said information,

[0147] - the base station selects the interrupt mode according to predetermined criteria of the communication conditions, and

[0148] - The base station sends information to the terminal (UE), which indicates the selected mode to be used for inserting a reference signal for phase tracking at the terminal. That is, the signal sent by the base station to the terminal (UE) includes:

[0149] - information related to a reference signal insertion mode (ie a mode selected according to communication conditions); and / or

[0150] - Information related to several reference signal insertion modes (including the mode selected according to the communication conditions).

[0151] Therefore, the object of the present invention is a system comprising a terminal and a base station, wherein both the terminal and the base station are configured to perform the method according to the embodiment.

[0152] exist Fig.12 In the example shown, the terminal UE can insert a reference signal for phase tracking according to the selected mode whenever the base station deems it necessary. Fig.13 In the alternative embodiment shown, the terminal UE may repeat the insertion (e.g., periodically) a predetermined number of times according to the selected mode (the number of times may also be encoded by the base station and sent to the terminal UE). Fig.14 In another alternative embodiment shown, the insertion of the phase tracking reference signal can be repeatedly performed by the terminal until the base station deems it unnecessary. The base station can then request the terminal to stop inserting the phase tracking reference signal, or alternatively, for example, apply another insertion mode.

Claims

1. A method for inserting a reference signal for phase tracking implemented by a computer device of a communication entity using a discrete Fourier transform extended orthogonal frequency division multiplexing modulator, The method is characterized in that the method comprises the following steps: - obtaining a series of signal samples by inserting said phase tracking reference signal within a series of data samples according to at least one insertion pattern selected among predefined patterns for predetermined criteria of communication conditions; as well as - feeding a series of signal blocks obtained from said series of signal samples to said modulator for applying said discrete Fourier transform after said inserting of said reference signal for phase tracking; wherein one of the predetermined criteria of the communication condition is at least a scheduling bandwidth; Wherein, a series of signal blocks after applying the discrete Fourier transform include N data transformed signal blocks, each transformed signal block is mapped to M effective carriers, and wherein the selected mode includes D i K separated by data samples i N phase tracking reference signals k Groups: Among them, D i where i=0~N k , K i where i=0~N k -1.

2. The method according to claim 1, wherein: One of the predetermined criteria of the communication condition is at least one of the following: -Other reference signal densities; -modulation; - coding rate; - carrier frequency; or - Physical resource block bundling.

3. The method according to claim 1 or 2, wherein: A reference signal for demodulation is also inserted into a transformed series of signal blocks generated at least by applying a discrete Fourier transform to the series of signal blocks, the reference signal for demodulation being inserted into a scheduled position of the transformed series of signal blocks, and wherein the selected mode depends on the scheduled position.

4. The method according to claim 1, wherein: Among them, D i When i is different from 0 and N k is a non-zero positive integer.

5. The method according to claim 4, wherein:

6. The method according to claim 4, wherein:

7. The method according to claim 4, wherein:

8. The method according to claim 4, wherein: Where k = 0 to N k -2.

9. The method according to claim 4, wherein: Where k = 0 to N k -1.

10. The method according to claim 4, wherein:

11. The method according to claim 4, wherein: After the inverse discrete Fourier transform performed by the modulator after the discrete Fourier transform, a non-zero cyclic prefix CP is inserted, and wherein D i , i=1...N k -1, can take one of the following two values: - the selected integer D', if D i does not span two signal blocks; or -D"=D'-E(N CP *M / N), if D i Spanning two signal blocks, where N CP corresponds to the number of CP samples appended after the inverse discrete Fourier transform, and E(x) specifies the nearest integer of x, and N corresponds to the number of subcarriers associated with the inverse discrete Fourier transform.

12. The method according to any one of claims 4 to 11, wherein: D i is chosen to avoid inserting a reference signal for phase tracking in a signal block having a location scheduled for a reference signal for demodulation or other reference signal allowing phase tracking.

13. A communication device using a discrete Fourier transform extended orthogonal frequency division multiplexing modulator, wherein: The apparatus comprises a computer circuit for inserting a reference signal for phase tracking, and - obtaining a series of signal samples by inserting said phase tracking reference signal within a series of data samples according to at least one insertion pattern selected among predefined patterns for predetermined criteria of communication conditions; and - feeding a series of signal blocks obtained from said series of signal samples to said modulator for applying said discrete Fourier transform after said inserting of said reference signal for phase tracking; wherein one of the predetermined criteria of the communication condition is at least a scheduling bandwidth; Wherein, a series of signal blocks after applying the discrete Fourier transform include N data transformed signal blocks, each transformed signal block is mapped to M effective carriers, and wherein the selected mode includes D i K separated by data samples i N phase tracking reference signals k Groups: K0=K1=....= ; Among them, D i where i=0~N k , K i where i=0~N k -1.

14. A non-transitory computer-readable storage medium storing instructions for performing the method of any one of claims 1 to 12 when executed by a processor.

Images