Transmitter and method for specific STBC precoding
阅读说明：本技术 用于特定stbc预编码的发送器及方法 (Transmitter and method for specific STBC precoding ) 是由 C·西奥奇纳 于 2019-02-18 设计创作，主要内容包括：本发明涉及在MIMO无线通信系统中发送符号,所述方法包括：确定p值；向M个数据符号的第一块X＝(X<Sub>0</Sub>,…X<Sub>M-1</Sub>)应用预编码器,以获得M个符号的第二块Y＝(Y<Sub>0</Sub>,…Y<Sub>M-1</Sub>),其中：<Image he="124" wi="700" file="DDA0002687885550000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>向M个符号的第一块应用M大小的DFT然后应用N大小的IDFT,以获得第一SC-FDMA符号,所述第一SC-FDMA符号具有给定的持续时间；向M个符号的第二块应用M大小的DFT然后应用N大小的IDFT,以获得第二SC-FDMA符号,所述第二SC-FDMA符号具有给定的持续时间；在给定的持续时间的时间间隔期间,将第一SC-FDMA符号和第二SC-FDMA符号同时发送到无线电信号中。(The invention relates to transmitting symbols in a MIMO wireless communication system, the method comprising: determining a p value; to a first block of M data symbols X ═ (X) 0 ，…X M‑1 ) Applying a precoder to obtain a second block of M symbols Y ═ (Y) 0 ，…Y M‑1 ) Wherein: applying an M-sized DFT and then an N-sized IDFT to a first block of M symbols to obtain a first SC-FDMA symbolThe numbers have a given duration; applying an M-sized DFT and then an N-sized IDFT to a second block of M symbols to obtain a second SC-FDMA symbol, the second SC-FDMA symbol having a given duration; the first SC-FDMA symbol and the second SC-FDMA symbol are simultaneously transmitted into a radio signal during a time interval of a given duration.)
1. A method for transmitting symbols by means of a radio signal in a wireless communication system, said radio signal being transmitted by a transmitter comprising at least two transmit antennas, each antenna being configured to transmit at least on an even number M of different frequencies strictly greater than 1, said method comprising the steps of:
To a first block of M symbols X ═ (X)0，...XM-1) Applying a precoder to obtain a second block of M symbols Y ═ (Y)0，...YM-1) Wherein
Wherein, P1And P2Is a positive integer or a predefined integer equal to 0, such that P1+P2Strictly less than M/2, p is a predetermined integer, 1 or-1, and XkIs XkComplex conjugation of (a);
applying at least an M-sized DFT corresponding to a first transmit antenna and then an N-sized IDFT corresponding to the first transmit antenna to a first block of the M symbols to obtain a first single-carrier frequency division multiple Access (SC-FDMA) symbol representing the first block of the M symbols, the first SC-FDMA symbol having a given duration;
applying at least an M-sized DFT corresponding to a second transmit antenna and then an N-sized IDFT corresponding to a second transmit antenna to a second block of the M symbols to obtain a second single-carrier frequency division multiple Access, SC-FDMA, symbol representing the second block of the M symbols, the second SC-FDMA symbol having a given duration;
transmitting the first and second SC-FDMA symbols simultaneously into the radio signal on the first and second transmit antennas, respectively, during a time interval of the given duration.
2. The method of claim 1, wherein mod (P, Q) ≠ 1, and Q ═ M/2- (P1+ P2).
3. The method of claim 1, wherein,
4. The method of claim 3, wherein mod (p, Q) is equal toAnd/or
5. The method of claim 1, wherein mod (P, Q) ═ K, where K is the pth including the first block from the M symbols1A symbol
6. The method of claim 5, wherein the symbols in the group of symbols are reference signal symbols and/or control symbols.
7. The method of claim 1, wherein mod (P, Q) ═ 0 and Q ═ M/2- (P1+ P2).
8. The method of claim 7, wherein a first set of L, Gi, of Ki symbols each, defining the first block of M symbols, whereinEqual to Q, and for each i:
as a slave in the first block of the M symbols
9. The method of claim 8, wherein, for each i, the symbol of the i-th type is one of a data symbol, a reference signal symbol, or a control symbol.
10. The method of claim 9, wherein for each i, the ith group GiHas the same sign as the (i + 1) th group Gi+1Different types of symbols.
11. The method according to any one of the preceding claims, wherein the p-value is determined based on at least one of:
cell specific p-value information;
a set of predetermined values;
a dynamic control indication;
reference signal RS configuration;
modulation and coding scheme MCS;
a user-specific parameter;
a size of a resource allocation allocated to the transmitter;
sender-specific p-value information;
p 'value of another transmitter, such that the other transmitter sends a first block of M' symbols X ═ X (X)0，…XM′-1) Applying a precoder to obtain a second block of M' symbols Y ═ (Y)0，...YM′-1) Wherein
Wherein, P'1And P'2Is a positive integer or a predefined integer equal to 0, such that P' 1+P′2Strictly less than M'/2 and is 1 or-1.
12. The method of any preceding claim, wherein the p-value is determined randomly in a set of predetermined values.
13. The method according to any of the preceding claims, wherein the nth symbol X of the first block of M symbolsnThe value of (c):
in that
in thatIs equal to the (n-Q) th symbol X of the first block of the M symbolsn-QThe value of (c).
14. A computer program product comprising code instructions to perform the method according to any one of claims 1 to 13 when the instructions are executed at least by a processor.
15. A transmitter for transmitting symbols by radio signals in a wireless communication system, the transmitter comprising:
at least two transmit antennas, each antenna configured for transmitting on at least an even number M of different frequencies strictly greater than 1;
a processor; and
a non-transitory computer readable medium comprising instructions stored thereon that, when executed by a processor, configure the transmitter to:
To a first block of M symbols X ═ (X)0，...XM-1) Applying a precoder to obtain a second block of M symbols Y ═ (Y)0，...YM-1) Wherein
Wherein, P1And P2Is a positive integer or a predefined integer equal to 0 such that P1+P2Strictly less than M/2, p is a predetermined integer, 1 or-1, and XkIs XkComplex conjugation of (a);
applying at least an M-sized DFT corresponding to a first transmit antenna and then an N-sized IDFT corresponding to the first transmit antenna to a first block of the M symbols to obtain a first single-carrier frequency division multiple Access (SC-FDMA) symbol representing the first block of the M symbols, the first SC-FDMA symbol having a given duration;
applying at least an M-sized DFT corresponding to a second transmit antenna and then an N-sized IDFT corresponding to a second transmit antenna to a second block of the M symbols to obtain a second single-carrier frequency division multiple Access, SC-FDMA, symbol representing the second block of the M symbols, the second SC-FDMA symbol having a given duration;
transmitting the first and second SC-FDMA symbols simultaneously into the radio signal on the first and second transmit antennas, respectively, during a time interval of the given duration.
Technical Field
The present invention relates generally to the field of telecommunication systems and, more particularly, to wireless communication in the context of MIMO (multiple input multiple output) or MISO (multiple input single output) communication, in particular used in a combination of OFDM type transmission schemes.
Background
The invention is applicable to MIMO or MISO telecommunication systems using a specific single symbol STBC precoder. SS-STBC is also known as single symbol STBC, split symbol STBC, or virtual split STBC.
A classical SS-STBC scheme has been developed to provide low PAPR (peak to average power ratio), full diversity in the context of MISO or MIMO transmission, and to preserve the single carrier property of OFDM type schemes.
The classical SS-STBC consists of a vector block X ═ (X)0，…XM-1) Applying an SS-STBC precoder to obtain a block of symbols Y ═ (Y)0，…YM-1). Then, an M-sized DFT (discrete fourier transform) is applied to each block X and Y of the symbol. For each symbol block, M complex symbols, respectivelyAndthese complex symbols are mapped in the frequency domain to M of the N inputs of an IDFT (inverse discrete fourier transform) of size N, so as to obtain a signal at the output of the IDFT
Applied to the symbol block X ═ (X)0，…XM-1) (also referred to as first symbol block) pre-codingEncoder output symbol block Y ═ (Y)0，…YM-1) (also referred to as a second symbol block). As shown in fig. 3, the first symbol block X ═ (X)0，…XM-1) Divided into two parts of M/2 symbols. The first part and the corresponding second part contain Q consecutive modulation symbolsContinuous symbolsThe Q consecutive modulation symbols of the first and second portions contain data and/or reference signals.
To limit interference between the two parts of a block symbol, the first part may contain Q consecutive modulation symbolsBefore and after P1Optional cyclic prefix and/or P of consecutive symbols2An optional cyclic suffix for a consecutive symbol. The second part may also contain Q consecutive modulation symbolsBefore and after P1Optional cyclic prefix sum P of consecutive symbols2An optional cyclic suffix for a consecutive symbol. The first part contains P in the cyclic prefix 1P in symbol, cyclic suffix2A symbol, and Q data/RS symbols. Thus, P1+P2+ Q ═ M/2, where P1And/or P2Can be equal to zero. M is considered an even number.
Thus, the first symbol block X ═ (X)0，…XM-1) May be defined by:
for the cyclic suffix of the first part,
for the cyclic prefix of the second part,
a cyclic suffix for the second portion.
When the first symbol block X is equal to (X)0，…XM-1) Obtaining a second symbol block Y ═ (Y) when applying the SS-STBC precoder0，…YM-1). The second symbol block can be defined relative to the previously defined first symbol block by:
for the data/RS symbols of the first part,
for the cyclic suffix of the first part,
for the cyclic prefix of the second part,
for the data/RS symbols of the second part,
a cyclic suffix for the second portion.
Wherein the content of the first and second substances,
In the following, we refer to the reference and the symbol X onlynCorresponding high energy sampling (i.e., sampling)
However, this scheme using the above-described SS-STBC precoder may not be suitable for most reference signal insertion modes. In addition, the implementation of the SS-STBC precoder has a high complexity.
Moreover, such SS-STBC precoders make SS-STBC schemes sensitive to fast channel modifications, especially in mmwave systems as is the case with the new radio standard or 5G currently being standardized. Operations performed at high carrier frequency levels may suffer from strong/fast phase variations due to different reasons such as phase noise, carrier frequency offset, doppler effect, etc. This sensitivity may lead to interference and performance loss.
In addition, the SS-STBC scheme is susceptible to interference when several terminals in the same cell communicate with a base station using the same scheme.
Disclosure of Invention
The present invention aims to improve this situation.
To this end, the invention relates to a method for transmitting symbols by means of a radio signal in a wireless communication system, said radio signal being transmitted by a transmitter comprising at least two transmit antennas, each antenna being configured to transmit at least on an even number M of different frequencies strictly greater than 1, said method comprising:
-to a first block of M symbols X ═ (X)0，…XM-1) Applying a precoder to obtain a second block of M symbols Y ═ (Y)0，…YM-1) Wherein
Wherein, P1And P2Is a positive integer or a predefined integer equal to 0, such that P1+P2Strictly less than M/2, p is a predetermined integer, 1 or-1, and XkIs XkComplex conjugation of (a);
-applying at least an M-sized DFT corresponding to a first transmit antenna and then an N-sized IDFT corresponding to the first transmit antenna to a first block of M symbols to obtain a first single carrier frequency division multiple access (SC-FDMA) symbol representing the first block of M symbols, the first SC-FDMA symbol having a given duration;
-applying at least an M-sized DFT corresponding to a second transmit antenna and then an N-sized IDFT corresponding to the second transmit antenna to a second block of M symbols to obtain a second single-carrier frequency division multiple access (SC-FDMA) symbol representing the second block of M symbols, the second SC-FDMA symbol having a given duration;
-transmitting simultaneously a first SC-FDMA symbol and a second SC-FDMA symbol into a radio signal on a first transmit antenna and a second transmit antenna, respectively, during a time interval of a given duration.
It enables selection or adaptation toSymbol pair (X)k；Is in a first block of M data symbols. Hereinafter, these pairs are also referred to as Alamouti (Alamouti) pairs. In fact, in the second block of M data symbols, at the same position (k,
X* k). We will also refer to abs
By adapting the value of p used in the precoder, the method enables optimization of a particular SS-STBC type precoding according to other settings and circumstances of the communication. For example, simply changing the value of p used for precoding can reduce decoding errors, e.g., interference with respect to the channel or rapid modification and/or variation. In another example, the p-value can also be selected to adapt a particular SS-STBC type precoding to a particular reference signal insertion pattern.
The p-value represents a particular pairing of symbols in the first symbol block and the second symbol block. The pairing is predetermined, i.e. the p-value is predetermined, to take into account the communication settings and/or environment (e.g. communication scheme and/or communication interference and/or channel characteristics, etc.), and thus e.g. the precoder adapts to the communication settings and/or environment.
By time interval, it is understood that transmission is associated with all symbols Xn(where n-0 to M-1) the duration of the corresponding sample is equal to the duration of an SC-FDMA symbol.
For example, X ═ (X) may be obtained by a QPSK digital modulation scheme or any other digital modulation scheme as QAM0，…XM-1) Symbol X ofn. M is the number of allocated subcarriers. In such an SS-STBC scheme, M is an even number. Specific modulation schemes or other sequences may also be used for some xsnE.g. X for setting as reference signaln。
The transmit antennas are configured to transmit on M frequencies, that is, to provide signals transmitted by such transmit antennas by applying an IDFT of size N over M complex symbols, one complex symbol for each of the M allocated subcarriers. Prior to IDFT, M subcarriers may be mapped onto a greater number of N subcarriers with a subcarrier mapping module. N-M of these subcarriers are unallocated subcarriers because they are set to zero, and M other subcarriers are M allocated subcarriers on which M complex symbols are mapped. In this case, the size of the IDFT module is N.
A radio signal is understood to be a signal which is provided by all transmit antennas together.
Is a predefined value of 1 or-1. When not otherwise stated, in the following we consider 1. In practice, changing the sign (+/-) of the signal associated with the second antenna does not change the method.
By mod (a, B), it is understood that a modulo B is the remainder of the euclidean division of a over B. Formally mod (A, B) can be written as A-E [ A/B ] B.
According to an aspect of the invention, wherein mod (P, Q) ≠ 1, and Q ═ M/2- (P1+ P2).
This enables to avoid incompatibility with some reference signal insertion pattern diagrams defined for PUSCH in 3GPP NR. In addition, when an SS-STBC type precoder with a P value set to 1 is used, the maximum distance between two Alamouti pairs in the first block of M data symbols is M- (P)1+P2) -2, obtaining the sum symbol X in the first SC-FDMA symbolnTransmission of corresponding samples and synchronization of the second single carrier frequency division multiple access SC-FDMA symbol with the precoder from symbol XnThe significant duration between transmissions for which the symbols are sent, namely:
-
-when n is equal to or greater than M/2+ P 1And is less than or equal to M-P2Then (c) is performed.
In accordance with one aspect of the present invention,and Q ═ M/2- (P1+ P2). Advantageously mod (p, Q) is equal to
This enables to reduce the maximum distance between two symbols of an Alamouti pair in the first block of M data symbols, i.e. the maximum precoding distance. Thus, the sum symbol X in the first single carrier frequency division multiple access SC-FDMA symbol is reducednTransmission of corresponding samples and synchronization by a precoder from symbol X in second Single Carrier frequency division multiple Access, SC-FDMAnThe maximum duration between transmissions corresponding to the transmitted symbols.
Thus, by minimizing the duration, this enables minimizing the sum symbol X in the first SC-FDMA symbolnTransmission of corresponding samples and symbol X in the second SC-FDMA symbolnThe channel variation between the transmission of corresponding samples. This reduces the loss of orthogonality between symbols of the same Alamouti pair, especially when the transmitter or receiver is in motion, which leads to interference and performance loss.
According to an aspect of the invention, mod (P, Q) ═ K, where K is the pth including the first block of M symbols1A symbolTo the (P) th block of M symbols1+ K) symbols
This makes the characterThe K symbols in the set can be located next to P of the first block of M symbols1After the cyclic prefix composed of the first symbols, the symbols in the second symbol block (hereinafter referred to as the send-out symbols) sent out simultaneously from the symbols of the group are also positioned immediately after the slave of the second block of the M symbols
Advantageously, the symbols of the symbol group are reference signal symbols and/or control symbols. The reference signal symbols (i.e., symbols representing the reference signal) and the control symbols (i.e., symbols representing the control information) may be particularly important for correctly decoding other symbols, thus ensuring better reception of data intended for the receiver by setting the K symbols to the reference signal symbols or the control symbols.
According to an aspect of the invention, mod (P, Q) is 0 and Q is M/2- (P1+ P2).
This can reduce the complexity of the implementation.
According to an aspect of the invention, each of the first blocks defining M symbols is KiL first groups G of symbols iWherein
from the first block as M symbolsA symbolTo the first
The conversion by precoder operation preserves the group structure defined above. I.e. comprise a groupAnd
The structure also enables handling of interference between different groups of symbols, in particular interference from groups with different types of symbols. Advantageously, for each i, the symbol of the ith type is one of different symbol classes, such as a data symbol, a reference signal symbol and/or a control symbol. Advantageously, in order to avoid processing a large number of groups, for each i, ith group G iHas the same sign as the (i + 1) th group Gi+1Are different symbol types.
Advantageously, determining the p-value comprises determining an optimized p-value for use as the p-value in the precoder. Advantageously, determining the p-value comprises calculating the p-value.
The determination of a suitable p-value (or an optimized p-value) can be made in several ways. For example, the p-value can be determined based on:
cell-specific p-value information determined by a base station, enabling to reduce the interference impact between transmitters located in the coverage areas of different base stations; this value is cell-specific and needs to be sent only when the receiver enters a new cell and/or when the cell-specific p-value changes; thus, it can be sent with low signaling overhead (i.e., with a small amount of control data);
dynamic control indication via a control channel (e.g. DCI (downlink control information) field or SCI (sidelink control information) field) enabling adaptation of a precoder according to a configuration of a cell and/or according to a user specific configuration, such as resource allocation;
-reference signal RS configuration, enabling the determination of p-values compatible with the specific reference signal insertion pattern used. In fact, if XnUsed as reference symbols, then symbolsIn that
-a modulation and coding scheme, MCS, and/or any other user specific or group/specific parameters, which randomize the interference distribution created by the user with respect to other users;
the size of the resource allocation allocated to the transmitter, which enables easy decoding when users with the same allocation are paired in a MU-MIMO transmission;
-transmitter specific p-value information determined by the base station, the base station being able to directly specify to the terminal the p-value to be used;
-a value of p 'for the other transmitter, such that the other transmitter forwards a first block of M' symbols X ═ (X)0，…XM′-1) Applying a precoder to obtain a second block of M' symbols Y ═ (Y)0，…YM'-1) Wherein, in the step (A),
wherein, P'1And P'2Is a positive integer or a predefined integer equal to 0, such that P'1+P′2Strictly less than M'/2 and is 1 or-1. This enables easy decoding when users with different allocations are paired in a MU-MIMO transmission;
-a set of predetermined values, which are also able to be transmitted to the terminal, determined by the base station, including p-values authorized by the base station for the terminal to communicate with the base station. Based on such a set of values, the p-value used can be determined randomly. Therefore, the probability that both terminals use the same p value is low.
The above principles apply in a similar manner also in case the sender is a user equipment and the receiver is a base station, and in case the receiver is a user equipment (i.e. a mobile terminal) and the sender is a base station. In all cases, the receiver needs to know the parameters used by the transmitter.
In both cases, both the sender and the receiver need to have a common understanding about the p-value used during transmission. This value is signaled or implicit rules allow the transmitter and receiver to unambiguously determine the value to be used.
By dynamic control indication, it is understood the information carried by the physical control channel (e.g. in LTE or NR, PDCCH, PUCCH, PSCCH). For example, the information can be a field of a DCI/UCI/SCI format.
By user specific parameters, it is understood that the parameters can be configured individually for the user, e.g. via a physical control channel or by higher layer signaling. Such parameters configured for uplink or downlink communications include, but are not limited to, modulation and coding schemes, resource allocation, reference signal configuration/pattern maps (e.g., DMRS, SRS, PTRS, CSI-RS, TRS, PRS, etc.), transmission schemes, number of codewords, power control, etc. In a similar manner, with group specific parameters, it is understood that the parameters can be configured for a group of users and are common to that group.
According to an aspect of the invention, the value of the nth symbol of the first block of M data symbols:
-at
-at
This enables prefix and/or suffix symbols to be set to protect useful symbols.
A second aspect of the invention relates to a computer program product comprising code instructions to perform the method as described before when said instructions are executed by a processor.
A third aspect of the present invention is directed to a transmitter for transmitting symbols by radio signals in a wireless communication system, the transmitter comprising:
-at least two transmit antennas, each antenna being configured for transmitting at least on an even number M of different frequencies strictly greater than 1;
-a processor; and
-a non-transitory computer-readable medium comprising instructions stored thereon that, when executed by a processor, configure the transmitter to:
-to a first block of M symbols X ═ (X)0，…XM-1) Applying a precoder to obtain a second block of M symbols Y ═ (Y) 0，…YM-1) Wherein
Wherein, P1And P2Is a positive integer or a predefined integer equal to 0, such that P1+P2Strictly less than M/2, p is a predetermined integer, 1 or-1, and XkIs XkComplex conjugation of (a);
-applying at least an M-sized DFT corresponding to a first transmit antenna and then an N-sized IDFT corresponding to the first transmit antenna to a first block of M symbols to obtain a first single carrier frequency division multiple access, SC-FDMA, symbol representing the first block of M symbols, the first SC-FDMA symbol having a given duration;
-applying at least an M-sized DFT corresponding to the second transmit antenna and then an N-sized IDFT corresponding to the second transmit antenna to the second block of M symbols to obtain a second single carrier frequency division multiple access, SC-FDMA, symbol representing the second block of M symbols, the second SC-FDMA symbol having a given duration;
-transmitting simultaneously a first SC-FDMA symbol and a second SC-FDMA symbol into a radio signal on a first transmit antenna and a second transmit antenna, respectively, during a time interval of a given duration;
the present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements.
Drawings
[ FIG. 1]
Fig. 1 illustrates a specific SS-STBC type transmitter and receiver.
[ FIG. 2]
Fig. 2 illustrates a block diagram of a specific SS-STBC type transmitter according to the present invention.
[ FIG. 3]
Fig. 3 details the specific SS-STBC type precoder logic function according to the present invention.
[ FIG. 4]
Fig. 4 details the specific SS-STBC type precoder logic function according to the present invention.
[ FIG. 5]
FIG. 5 details a device according to the invention with an arrangementAnd/orA particular SS-STBC type precoder logic function.
[ FIG. 6]
Fig. 6 details the particular SS-STBC type precoder logic function with p set to K according to the present invention.
[ FIG. 7]
Fig. 7 details the particular SS-STBC type precoder logic function with p set to 0 in accordance with the present invention.
[ FIG. 8]
Fig. 8 illustrates a flow chart representing steps for transmitting symbols in a radio signal according to the present invention.
Detailed Description
Referring to fig. 1, a transmitter 1.1 is shown transmitting a radio signal to a receiver 1.2. The transmitter 1.1 is located in the cell of the receiver 1.2. In the context of an OFDM-based system, the transmission may be a specific SS-STBC based transmission. In this example, the transmitter 1.1 is a mobile terminal (also referred to as user equipment, UE) and the receiver 1.2 is a fixed station, which in the context of LTE is a base station. The transmitter 1.1 can also be a fixed station and the receiver 1.2 a mobile terminal. It is also possible to use both the sender 1.1 and the receiver 1.2 as mobile terminals (e.g. during device-to-device or sidelink communication).
The transmitter 1.1 comprises a communication module (COM _ trans)1.3, a processing module (PROC _ trans)1.4 and a memory unit (MEMO _ trans) 1.5. The MEMO _ trans 1.5 includes a non-volatile unit to fetch a computer program and a volatile unit to fetch parameters for communication (e.g., p-value for precoding). PROC _ trans 1.4 is configured to precode a first block X of M symbols into a second block Y of M symbols according to a particular SS-STBC type precoder. COM trans is configured to transmit radio signals to the receiver 1.2. The processing module 1.4 and the memory unit 1.5 may be dedicated to precoding or may also be used for other functions of the transmitter, such as other steps of processing radio signals.
The receiver 1.2 comprises a communication module (COM _ receiver) 1.6, a processing module (PROC _ receiver) 1.7 and a storage unit (MEMO _ receiver) 1.8. The MEMO _ receiver 1.8 includes a non-volatile unit that fetches a computer program and a volatile unit that fetches parameters for communication (e.g., p-values for precoding). PROC _ receiver 1.7 is configured to decode the signal to take out the symbols of a first block X of M symbols. COM _ receiver 1.6 is configured to receive radio signals from a transmitter.
Referring to fig. 2, a block diagram of a particular SS-STBC type transmitter is shown. This particular SS-STBC type transmitter applies an SC-FDMA scheme to a symbol block (first symbol block) and a precoded symbol block (second symbol block) to obtain a radio signal. This ensures full diversity of the rate at which one symbol is used per channel. Such a transmitter transmits radio signals by transmitting on at least two transmit antennas tx12.0 and tx22.1.
By applying a specific SS-STBC type precoder 2.2 to the first symbol block X ═ (X ═ X)0，…XM-1) And obtaining a second symbol block Y ═ (Y)0，…YM-1) To provide a radio signal. The first symbol block may be obtained by a QPSK digital modulation scheme or any other digital modulation scheme such as QAM. M is the number of allocated subcarriers. In such an SS-STBC scheme, M is an even number.
Then, M-sized DFT 2.3, 2.4 (discrete fourier transform) is applied to each symbol block X and Y. For each symbol block, M complex symbols, respectively
Then, the two result vectors of modules 2.5 and 2.6 are mapped to the subcarriers
Optionally, a cyclic prefix may be appended after the IDFT.
Referring to fig. 3, the logical function of a particular SS-STBC type precoder module 2.2 is shown in detail.
Applied to the symbol block X ═ (X)0，…XM-1) (also called first symbol block) SS-STBC type precoder 2.2 output symbol block Y ═ (Y)0，…YM-1) (also referred to as a second symbol block). Consider a first symbol block X ═ X0，…XM-1) As shown in fig. 2.2, the first symbol block is divided into two parts of M/2 symbols. The first part and the corresponding second part contain Q consecutive modulation symbols
To limit interference between the two parts of the symbol block, the first part may contain Q consecutive modulation symbols
Thus, the first symbol block X ═ (X) 0，…XM-1) May be defined by:
for the useful symbols of the first part (data, RS, control symbols),
for the cyclic suffix of the first part,
a cyclic suffix for the second portion.
When the first symbol block X is equal to (X)0，…XM-1) Obtaining a second symbol block Y ═ (Y) when applying a specific SS-STBC type precoder0，…YM-1). The second symbol block can be defined relative to the previously defined first symbol block by:
for the useful symbols of the first part (data, RS, control symbols),
for the cyclic prefix of the second part,
for the useful symbols of the second part (data, RS, control symbols),
a cyclic suffix for the second portion.
Wherein the content of the first and second substances,
In a variant, zero padding can be used instead of cyclic prefix/postfix. In yet another variation, the cyclic prefix and/or suffix can be inserted with respect to a group of symbols within the Q consecutive useful symbols, rather than with respect to the Q consecutive useful symbols.
Thus, Y can be defined based on X with respect to data, control, and reference signal symbols by:
is a value of 1 or-1. When not otherwise stated, in the following we consider 1. In practice, changing the sign (+/-) of the signal associated with the second antenna does not change the method.
Referring to fig. 4, the logical function of a particular SS-STBC type precoder module 2.2 and the particular Alamouti pairing structure resulting from the particular SS-STBC type precoder module 2.2 are shown in detail. That is, fig. 4 describes in detail the symbol pairing in the first block of M symbols according to the present invention.
When p is different from 0, the 0 th symbol A of the Q useful symbols of the first part of the first block of M symbols0P-1 symbols B of Q useful symbols associated with the second part of the first block of M symbolsp-1And (6) pairing. Then, for each i strictly smaller than p, the symbol AiAnd symbol Bp-iAnd (6) pairing.
Then, the remaining symbols A of the Q useful symbols of the first part of the first block of M symbolspTo AQ-1With the remaining symbols B of the Q useful symbols of the first part of the first block of M symbolsQ-1To BpPairing, and: first group (symbol A)pTo AQ-1) First symbol a in (1)pAnd a second set of symbols (B) pTo BQ-1) Last symbol B in (1)Q-1Pairing, first group (symbol A)pTo AQ-1) Second symbol of (1)p+1And a second set of symbols (B)pTo BQ-1) The second last symbol of (1)Q-2Pairing, and so on.
When p is equal to zero, the first symbol A0And the last symbol BQ-1Pairing, second symbol A1And the penultimate symbol BQ-2Are paired, in accordance withAnd so on.
Two symbols X of the first symbol blockaAnd XbAt the slave symbol XaLocation of the issued symbol (i.e., symbol Y)aPosition a 'of' such as) Is position b is considered a pair. Thus, the symbol XaAnd from XaIssued symbol Ya'At the positions of a and b in the first and second symbol blocks, respectively, and the symbol XbAnd from XbThe symbols emitted are at the positions of b and a in the first and second symbol blocks, respectively.
Referring to FIG. 5, FIG. 5 illustrates a system having a configuration configured to operate in accordance with an embodimentDetails of the specific SS-STBC type precoder logic function of the p value of (a). In the example of fig. 5, the sizes of P1, P2, and Q are set to simplify the representation of this embodiment. Thus (P)1，P2Q) ═ (3, 1, 8). Of course, the present invention is not limited to such sizes of P1, P2, and Q.
The maximum precoding distance between two symbols of an Alamouti pair is 15 symbols, i.e. there are only 14 symbols between two symbols of an Alamouti pair.
The subcarrier mapping modules 2.5 and 2.6 may have several configurations, e.g. the subcarrier mapping can be localized, i.e. each vector STx1,2Is mapped to M consecutive subcarriers among the existing N.
Thus, when N is a multiple of M, the signal in the time domain at the output of IDFT module 2.7
at other positions, values of samples in the first and second SC-FDMA symbols are all Xs having different complex weights, respectivelynAnd YnThe sum of (1). Therefore, the temperature of the molten metal is controlled,
Thus, the two samples in the first SC-FDMA symbol, which correspond to the two symbols of the Alamouti pair, respectivelyAndthe distance between (i.e., M (b-a) samples) depends on the distance of (b-a) symbols between the two Alamouti symbols in the first symbol block.
The subcarrier mapping may also be distributed, i.e. each vector STx1,2Are mapped equidistantly over the entire bandwidth and zeros occupy unused subcarriers.
Thus, when N is a multiple of M, the signal in the time domain at the output of IDFT module 2.7
thus, the two samples in the first SC-FDMA symbol, which correspond to the two symbols of the Alamouti pair, respectivelyAnd
The time difference (or duration) between the transmission of the two sampled radio signals can be understood by the distance between the two samples.
Thus, the distance between two samples, respectively corresponding to the symbols of the Alamouti pair, is proportional to or at least dependent on the distance of these symbols in the first symbol block.
This is also the case for all other subcarrier mapping types and/or non-integer N/M ratios of similar relationships between symbols and their corresponding samples in a radio signal.
Thus, by minimizing the difference between two symbols of the same pairThe maximum precoding distance in the first symbol block minimizes the maximum duration between samples in the radio signal corresponding to two symbols of the same pair. This enables the symbol X to be compared withaChannel variation between transmissions of samples in corresponding first and second SC-FDMA symbols is minimized. By minimizing the channel variation between the transmissions of these samples, the loss of orthogonality between symbols of the same Alamouti pair, which leads to interference and performance loss, is reduced.
When the value of p is set to a value around Q/2, especially when p is equal to
Referring to fig. 6, according to an embodiment, there is a detail of a specific SS-STBC type precoder logic function set to a p value of K. In this example, the sizes of P1, P2, and Q are set to simplify the representation of this embodiment. Thus, (P)1，P2Q) ═ (3, 1, 8). Of course, the present invention is not limited to such sizes of P1, P2, and Q.
The first K symbols of the useful portion of the first symbol block are paired with the first K symbols of the useful portion of the second portion of the first symbol block. Thus, the K symbols emitted from the precoder according to the first K symbols of the useful part of the first portion of the first symbol block are the first K symbols of the useful part of the second portion of the second symbol block.
Thus, both the first K symbols of the useful part of the first symbol block and their (from the precoder) transmitted symbols are located after the P1 prefix symbol, which enables to protect these 2K symbols from interference, in particular multipath interference. Note that in a variant, the prefix can be inserted with respect to the first K symbols of each useful part instead of Q symbols. That is, the prefixes inserted into the first symbol block contain the symbol a, respectivelyK--P1…AK-1And BK--P1…BK-1。
The first K symbols forming the first part of group G are more robust to interference since the K outgoing symbols can facilitate the extraction of the first K symbols of the useful part of the first symbol block. This is therefore relevant for inserting in the group G symbols, which are reference signal symbols and/or control symbols, which need to be protected especially from interference, since they are particularly important for correctly decoding the other symbols.
Referring to fig. 7, details of the logic function of a particular SS-STBC type precoder with p value set to 0 according to an embodiment are given. In this example, the sizes of P1, P2, and Q are set to simplify the representation of this embodiment. Thus (P)1，P2Q) ═ (3, 1, 8). Of course, the present invention is not limited to this size of P1, P2, and Q.
In this embodiment, the first symbol of the useful part of the first symbol block is paired with the last symbol of the useful part of the second part of the first symbol block. The second symbol of the useful part of the first symbol block is paired with the penultimate symbol of the useful part of the second part of the first symbol block and so on. For precoders, the complexity of such Alamouti pairing structure is low.
Based on this structure, it can be defined to have K eachiSeveral groups of symbols
by mixing KiIth first group G 'of symbols'iDefined as being formed by the first block of M symbols fromA symbol
Thus, the ith group GiSymbol of (2) and group G'iThe symbol pair of (1). Group GiAnd group G'iReferred to as a pairing group. Samples of the first and second SC-FDMA symbols corresponding to the i-th group of symbols and the group G 'of the first and second SC-FDMA symbols corresponding to the pairing' iAre transmitted simultaneously. Thus, the processing of samples corresponding to symbols of a group and its counterpart group can be separated at the receiver side from the processing of other samples corresponding to symbols of other groups.
If the symbols of the paired groups are of the same type, e.g. data symbols, reference signal symbols or control symbols, the processing of the reference signal part of e.g. a radio signal can be separated at the receiver side.
In addition, P value, P1And P2Set to zero and having this particular group structure facilitates the insertion of reference signals according to the PTRS insertion pattern map for DFTsOFDM PUSCH described in table 6.4.1.2.2.2-1 clause 6.4.1.2.2 for 3GPP TS 38.211. In practice, these insertion pattern diagrams are symmetrical, i.e. for example the first N in the first symbol blockgroup PTRSA symbol andrear Ngroup PTRSOne symbol is set as a reference signal. Thus, by mixing K1Is set to Ngroup PTRSMaking the group structure compatible with such an insertion pattern diagram.
In another example, when inserting two groups of two RS samples per group, the RS is inserted in the middle of each half of the first symbol block, i.e., at the positions of (M/4-1; M/4) and (3M/4-1, 3M/4). Thus, for example, by mixing K2Set to 2 and K 1Set to M/4-1, making the group structure compatible with this insertion pattern diagram. Thus, more generally, K is seti2, such as
In another example, before applying the precoder, symbols of a pair group into which the RS should be inserted are set to zero in the first symbol block. Then, after applying the precoder, RS is inserted instead of zero. This insertion can be done, for example, before applying the DFT modules 2.3 and 2.4, i.e. by setting the symbols of the first and second symbol blocks that are set to zero to the desired values. In the case of reference signals, since the receiver knows their values, it is not necessary to make the values of the reference signals inserted in the second block of symbols equal to those that would be obtained if the reference signals inserted in the first block of symbols had been precoded. As an equivalent implementation option, the reference signal can be inserted after DFT (i.e. in the frequency domain) or after IDFT by adding the respective signal to obtain the same or equivalent signal as if the reference signal was inserted before applying DFT.
Referring to fig. 8, a flow chart representing steps for transmitting symbols in a radio signal according to the present invention is illustrated.
In the step S1, the user can select the desired mode,parameters for configuring the precoder module 2.2 are determined. That is, the P value, P, is determined1、P2And the size of M. These parameters are referred to as parameters of the precoder.
The determination of the parameters is done according to the communication scheme and/or the configuration of the cell determined by the base station 1.2.
In case the transmitter is a mobile terminal, the base station 1.2 is able to predetermine the communication parameters and set the precoder parameters of the transmitter 1.1.
Information representative of the precoder parameters can be transmitted to the transmitter 1.1. Thus, the transmitter 1.1 receives a signal representing the P-value, P1、P2And information on the size of M or allowing calculation of P-value, P1、P2And information of the size of M, based on which the transmitter 1.1 can efficiently determine the P-value, P1、P2And the size of M.
For example, the base station 1.2 can send to the transmitter 1.1:
-cell specific p-value information; and/or
-sender specific p-value information; and/or
-P1、P2And the size of M.
These parameters, in particular the p-value, can be determined, for example, by the base station 1.2 on the basis of:
-cell specific configuration and/or
-dynamic control indication, e.g. DCI indicator/format and/or;
-reference signal RS configuration/insertion pattern map and/or;
-user specific parameters such as (but not limited to) modulation coding scheme, resource allocation size and/or;
-a p' value and/or used by another transmitter in the same cell;
-a plurality of sets of predetermined values (p)i、P1i、P2i、Mi)。
The value of p may also be determined randomly by the base station 1.2 in a set of predetermined values.
In an alternative, the base station 1.2 does not send the indication P value and P to the mobile terminal 1.11、P2And the size of M, but one of the above, based on which the terminal 1.1 can deduce the precoder parameters determined by the base station 1.2. For example, the use of a particular reference signal configuration can be related to parameters of a particular precoder.
In an alternative embodiment, the base station 1.2 can determine the communication scheme (e.g. RS insertion pattern map, modulation and coding scheme, MCS, … …) and/or the configuration of the cell instead of the parameters of the precoder, leaving the transmitter 1.1 to determine and/or calculate the parameters from the communication scheme. In this case, the transmitter 1.1 may send this information to the base station 1.2 once the parameters of the precoder have been determined, so that the base station 1.2 can take out the parameters of the precoder.
In case the transmitter 1.1 is a base station and the receiver 1.2 is a mobile terminal, the base station 1.1 determines parameters for configuring the precoder module 2.2 of the base station 1.1. That is, the P value, P, is set 1、P2And the size of M. These parameters are referred to as parameters of the precoder.
These parameters, and in particular the p-value, to be used when communicating with the receiver 1.2 can be determined by the base station 1.1 based on:
-a cell specific configuration;
-reference signal RS configuration/insertion pattern map;
-user specific parameters determined for the receiver 1.2;
-a value of p' used by the neighbouring base station;
-a plurality of sets of predetermined values (p)i、P1i、P2i、Mi)。
Additionally, similar to in the previous embodiments, the base station 1.1 provides the mobile terminal 1.2 with information that allows the mobile terminal 1.2 to derive parameters used by the precoder to enable the mobile terminal 1.2 to decode the received communication.
Additionally, in both cases, whether the mobile terminal is the receiver 1.2 or the transmitter 1.1, the mobile terminal can derive these parameters based on rules known to both the base station and the mobile terminal.
In yet another example, both the transmitter and the receiver are mobile terminals. The p-value can be determined based on predetermined rules or by cooperation.
(e.g., each mobile terminal determines the p-value to be used for its own communication and then transmits it to another mobile terminal;
for example, each mobile terminal determines a p-value to be used for its own communication, and another terminal can implicitly determine the value used from other information;
For example, one terminal decides a p value to be used during communication in both directions and transmits it to the other terminal;
for example, one terminal decides a p value to be used during communication in both directions, and the other terminal can implicitly determine the value used from other information;
for example, the terminals exchange information allowing to determine a common p-value;
for example, both terminals apply a set of known rules such that they unambiguously determine the p-value based on other known parameters/configurations; for example, the p-value is fixed for all sidelink communications, and so on)
At step S3, the precoder module 2.2 is configured according to the parameters of the precoder determined by the terminal 1.1.
In step S5, the signal is processed, i.e., the first symbol block X is (X)0，…XM-1) The application is preconfigured to obtain a second symbol block Y ═ (Y)0，…YM-1) Specific SS-STBC type precoder module 2.2. Then, for each of the first symbol block and the second symbol block, the SC-FDMA scheme (DFT modules 2.3 and 2.4, subcarrier mapping modules 2.5 and 2.6, and IDFT modules 2.7 and 2.8) is applied.
At step S7, a signal is transmitted by tx12.0 and tx22.1.
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