阅读说明：本技术 基于信号虚拟分解空域和功率域联合多址接入方法及系统 (Signal virtual decomposition-based airspace and power domain combined multiple access method and system ) 是由 李钊 胡娇娇 畅志贤 于 2021-05-17 设计创作，主要内容包括：本发明公开了一种基于信号虚拟分解的空域和功率域联合多址接入方法及系统,系统包含多个期望发射机、一个调和发射机和一个公共接收机,公共接收机和所有发射机共享信道状态信息,调和发射机通过遍历得到一个正交基使调和功率最小,并将该正交基共享给期望发射机和公共接收机,并将该正交基包含的基向量所表征的空间特征作为多路期望信号的方向,求解调和信号,期望发射机根据正交基确定接收端的匹配滤波向量,计算期望数据增益,并发送给接收端,调和信号与实际发送信号在接收端相互作用,公共接收机对混合信号进行滤波,然后将滤波输出除以期望数据增益,得到期望数据。从而实现公共接收机从接收混合信号中无干扰恢复出多路期望数据。(The invention discloses a space domain and power domain combined multiple access method and a system based on signal virtual decomposition, the system comprises a plurality of expected transmitters, a harmonic transmitter and a common receiver, the common receiver and all transmitters share channel state information, the harmonic transmitter obtains an orthogonal base through traversal to minimize harmonic power, the orthogonal base is shared to the expected transmitters and the common receiver, the space characteristic represented by a base vector contained in the orthogonal base is taken as the direction of a multi-path expected signal, a harmonic signal is solved, the expected transmitter determines a matched filtering vector of a receiving end according to the orthogonal base, expected data gain is calculated and sent to the receiving end, the harmonic signal and an actual sending signal interact at the receiving end, the common receiver filters a mixed signal and then divides the filtering output by the expected data gain, the desired data is obtained. Thereby realizing that the common receiver can recover the multi-path expected data from the received mixed signal without interference.)

1. A space domain and power domain combined multiple access method based on signal virtual decomposition is suitable for a wireless uplink communication system of a plurality of expected transmitters and a common receiver, and is characterized by comprising the following steps:

(1) the wireless uplink communication system is composed of N desired transmitters Tx_k(k-1, 2, …, N), 1 common receiver and 1 harmonic transmitter Tx_cThe common receiver shares channel state information with each desired transmitter to the reconciliation transmitter, while the desired transmitter Tx shares channel state information with each desired transmitter_kSharing the actual sending data information to a harmonic transmitter;

(2) each desired transmitter Tx_kDesigning a desired transmitter precoding vector p according to a channel matrix between the desired transmitter and a common receiver_k(k 1,2, …, N), the desired transmitter Tx_kPrecoding a vector p according to the desired transmitter_kSending carry data x 'to a common receiver'_kSignal s'_kWherein, x'_kData representing actual transmissions intended by the transmitter to the common receiver;

(3) the harmonic transmitter selects an orthogonal base through traversal, takes the spatial characteristics represented by the basis vectors contained in the orthogonal base as the directions of the multi-channel expected signals recovered by the common receiver, solves the interaction between the spatial characteristics and the actual transmission signals of the expected transmitter to obtain the harmonic signals of the recovered expected signals, and further calculates the harmonic transmission data x_cAnd blending thereofTransmitter precoding vector p_cA harmonic signal s_cThe method comprises the steps that the method can be decomposed into a plurality of mutually orthogonal virtual harmonic signal components virtually, a harmonic transmitter shares information of harmonic signals and selected orthogonal bases to all expected transmitters, the obtained orthogonal bases are shared to a common receiver at the same time, and the harmonic transmitter sends a path of harmonic signals carrying harmonic data to the common receiver;

(4) desired transmitter Tx_kDetermining a matched filter vector at the common receiver based on the quadrature basis selected by the harmonic transmitter and calculating a filtered desired data gain α_kThe desired transmitter will calculate the resulting filtered desired data gain α_kSending to a common receiver, the common receiver adopting the orthogonal basis shared by the harmonic transmitter, determining a filtering vector, performing matched filtering on the received mixed signal, and dividing the filtering output by the expected data gain alpha_kTo recover the desired data x_k。

2. The spatial domain and power domain joint multiple access method based on signal virtual decomposition according to claim 1, wherein the step (1) is specifically as follows:

common receiver Rx₀Broadcasting a pilot signal from which each desired transmitter estimates its sum Rx₀And feeds back to Rx₀，Rx₀Sharing channel state information of each desired transmitter to the reconciliation transmitter, while the desired transmitter shares data information actually transmitted to the reconciliation transmitter, wherein the common receiver Rx₀And Tx_kThe channel state information between is recorded as H_k(k＝1,2,…,N)，Rx₀And Tx_cThe channel state information between is recorded as H_c。

3. The spatial domain and power domain joint multiple access method based on signal virtual decomposition according to claim 1, wherein the step (2) is specifically as follows:

(2a) desired transmitter Tx_kProcessing precoding vector p_kSelected from the pair channel matrix H_kThe first column vector of the right singular matrix is obtained by singular value decomposition, wherein the first column vector carries data x'_kTo slave and desired transmitter Tx_kOriginal expected data x of_kRandomly selected, x, of the same set of modulation symbols to which they belong_kOriginal expected data indicating that the expected transmitter wishes to transmit to the common receiver;

(2b) harmonic transmitter Tx_cTo a common receiver Rx₀Transmitting data x_cThe common receiver performs a virtual orthogonal decomposition on the received harmonic signal to obtain N virtual harmonic signal components

Wherein the harmonic signalP_cIndicating the transmission power, s, of the transmitter transmitting the tone signal_ck(k-1, 2, …, N) represents the k-th virtual harmonic signal component,<s_cj,s_cl>representing virtual harmonic signal components s_cjAnd s_clThe inner product of (c), i.e., represents the calculated modulus value, j, l belongs to {1,2, …, N } and j is not equal to l;

(2c) common receiver Rx₀Received from the kth desired transmitter Tx_kIs recorded as the actual transmission signalThis component is combined with a virtual harmonic signal component s_ckInteract to obtain s_ck+s′_k，s_ck+s′_kIs the k-th desired signal s recovered by the common receiver_kWherein P is_TkRepresents Tx_kThe transmit power of.

4. The spatial domain and power domain joint multiple access method based on signal virtual decomposition according to claim 1, wherein the step (3) is specifically:

(3a) reconciling the transmitter from the recovered desired signal s_kUnit direction vector of (k 1,2, …, N)And actual transmission signal s'_kIn thatOrthogonal projection ofObtaining virtual harmonic signal components:

wherein, byThe constructed orthogonal vectors form a set of orthogonal bases;

the harmonic transmitter transmits signal s 'according to the actual of the desired transmitter'_kThe orthogonal basis containing a vector representing the common receiver Rx and minimizing the harmonic signal power overhead is obtained by traversal₀Direction of recovered multipath desired signals, common receiver Rx₀The directions of the recovered multipath expected signals are respectively located in the space direction represented by the basis vectors contained in the orthogonal basis.

(3b)η_k＝||s_ck||²(k-1, 2, …, N) is the power overhead of the virtual harmonic signal component required for the transmission signal of the kth desired transmitter, in the interval (0, | s'_k||²) Internal pair eta_kTraversing values are carried out, and each eta in the traversing process is subjected to_kThe values are all based on equation (2) to obtain a unit vectorAnd judgeWhether the condition is satisfied:

to satisfy the first subformula of the formula (3)And η corresponding thereto_kStoring as if it is a eta_kExhibiting a plurality of first sub-types conforming to formula (3)Then these will be metRecord as(k＝1,2,…,N,j_k1,2, …), corresponding η_kIs marked asAnd storing;

for pairs having different subscripts kAre combined, each k being from j only_kSelecting one j from 1,2, …_kAs mentioned aboveOne element in the combination can obtain a plurality of combinationsEach group is divided into two groupsAny two elements in (b) are tested by substituting the second subformula of the formula (3), and any two elements satisfy the second subformula of the formula (3)Saving is performed, and each group saved is calculatedCorresponding harmonic power overhead, the t-th group corresponding harmonic power overheadChoose the smallestIs marked asAnd obtain the correspondingIs marked as That is, the orthogonal basis obtained by traversal is used for restoring the signal actually transmitted by the expected transmitter to the space direction represented by the basis vector contained in the orthogonal basis, and the power overhead of the harmonic transmitter is minimum and isThe harmonic signal may be represented as:

(3c) computing a transmitted precoding vector p for a harmonic signal_cAnd the harmonic signal transmitting data x_c. According toAnd the minimum power overhead P calculated_cminCan obtain the productAccording to the harmonic signal obtained by the formula (4), letParameter a_kAndis a known amount, whereinThe number of antennas of the harmonic transmitter is adjusted, and the harmonic transmission data of the harmonic transmitter is expressed as x_c＝a_c+b_ci (definition)B is available_c＝a_c tanθ_c) Wherein theta_cSelecting by the harmonic transmitter in the phase interval [0,2 pi ]; precoding vectors for harmonic signalsWherein a is_ckAnd b_ck Is an unknown quantity, and | | | p_cIf 1, then there isThus, can obtainAccording to the principle that the real part and the imaginary part of the complex number are equal to each other, the equation system can be obtained:

all sub-formulae (corresponding) included in the pair formula (5)) The equal sign of (D) is squared and added to obtainThe harmonic sending data carried by the harmonic signal is obtained as follows:

x_c＝a_c+a_c tanθ_ci (6)

wherein the content of the first and second substances,

by | | | p_c1, pairBoth sides of equal sign are divided byTo obtainThe precoding vector to get the harmonic signal is:

the harmonic transmitter shares the information of the harmonic signal and the orthogonal base obtained by traversal to all expected transmitters, shares the orthogonal base obtained by traversal to a public receiver, and sends a path of harmonic signal carrying harmonic data to the public receiver.

5. The spatial domain and power domain joint multiple access method based on signal virtual decomposition according to claim 1, wherein the step (4) is specifically:

desired transmitter Tx_k(k 1,2, …, N) using beamforming to transmit powerAnd precoding p_kTransmitting data x 'to a common receiver'_kSignal s'_kHarmonizing the transmitter with a transmission power P_cminAnd precoding p_cReconciling transmit data x to a common receiver_cIs a harmonic signal s_cAt a common receiver Rx₀Matched filtering each of the recovered mutually orthogonal desired signal components, the desired transmitter determining a matched filtered vector at the common receiver based on the selected orthogonal basis information from the reconciling transmitter, the filtered vector being recorded asThe desired transmitter can calculate the desired data x after filtering according to the information of the harmonic signal shared by the harmonic transmitter and the orthogonal base_kGain alpha of_k(k ═ 1,2, …, N) is:

the desired transmitter is expected to gain the filtered desired data by α_kSending to a common receiver using quadrature-based deterministic filtering with transmitter sharingVector f_kMatched filtering the received mixed signal and dividing the filtered output by the desired data gain alpha_kThereby recovering the desired data x_k：

6. A wireless communication system applying the spatial domain and power domain joint multiple access method based on signal virtual decomposition according to any one of claims 1-5.

Technical Field

The invention belongs to the technical field of communication, and further mainly relates to a multiple access method, in particular to a space domain and power domain combined multiple access method based on signal virtual decomposition.

Background

Multiple access techniques are applied to wireless communication systems to allow multiple users to share limited system resources. From the first to fourth generation mobile communication systems, the Multiple Access technology has undergone Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), and Orthogonal Frequency Division Multiple Access (OFDMA). Increasingly, multiple access techniques are used to improve the spectral efficiency and resource utilization of the system. After the mobile communication technology enters the fifth generation (5G), the development of various new technologies and the rapid growth of intelligent terminals put new demands on the multiple access technology, and the future communication scenarios require intensive communication, low delay and high spectral efficiency. M.hen and s.li, "Power Allocation for NOMA Based Layered Transmission,"2018IEEE 4th International Conference Computer and Communications (ICCC), Chengdu, China, pp.678-682,2018. a Non-Orthogonal Multiple Access technique (NOMA) is designed, Power multiplexing is adopted at the transmitting end to allocate different transmitting powers to different users, and Serial Interference Cancellation (SIC) is used at the receiving end to realize the differentiation and recovery of user data, so as to improve the spectrum efficiency at the cost of increasing the complexity of the receiver. In addition, b.ling, c.dong, j.dai and j.lin, "Multiple Decision Aided Interference Cancellation receivers for NOMA Systems," in IEEE Wireless Communications receivers, vol.6, No.4, pp.498-501, and aug.2017 show that processing delay may be caused because a SIC Receiver needs to process a plurality of user signals one by one, and SIC has an error propagation problem, that is, a detection error of a previous user signal may affect recovery of a subsequent user signal, and these disadvantages may cause certain restrictions on application of NOMA using SIC. China, 202010682294.6,2020.07.15, proposes a Multiple Access method (VSDMA) based on Virtual Signal Division, in which Multiple desired transmitters transmit signals at the same time using the same frequency, and an extraction transmitter is introduced, which designs and transmits an extraction Signal, which can be equivalent to the in-phase superposition of Multiple extraction Signal components, which interact with the signals transmitted by the Multiple desired transmitters, so that a common receiver can recover the desired data transmitted by each desired transmitter from the received mixed Signal, but the method does not consider the power overhead of the extraction transmitter, which may result in too high power cost.

In a wireless communication system, interference has been a major factor affecting communication, and how to eliminate or suppress interference is a very important technical problem. Common Interference management methods include Zero-Forcing (ZF) using Channel State Information (CSI), Interference Alignment (IA), etc., and Interference Neutralization (IN) and Interference Steering (IS), etc., using CSI and Interference-carried data Information. The document k.gomadam, v.r.cadmbeand s.a.jafar, "applying the capacity of wireless networks with a distributed interference alignment", proc.ieee Globecom, pp.4260-4265,2008, the designed IA can map multiple interferers into a limited subspace at the interfered receiver by preprocessing the interferers, thereby leaving the desired signal unaffected by the interference. However, the feasibility of IA is limited by the parameter settings of the system, such as the number of transmitters and receivers and the number of antennas of the transmitters or receivers. The documents w.noh et al, "Adaptive Transmission Control IN Multiple Interference cancellation Groups," IEEE Communications Letters, vol.20, No.3, pp.526-529, March 2016. the IN design utilizes the interaction between signals to cancel Interference at the interfered receiver by generating a neutralizing signal. But generating the neutralizing signal by IN consumes transmit power and can result IN a performance loss for the desired communication. And when the interference is strong, the transmitter corresponding to the interfered receiver may lack sufficient power to generate a neutralizing signal, thereby rendering IN unavailable. The IS designed by the documents z.li, y.liu, k.g.shin, j.liu and z.yan, "Interference Steering to man Interference in IoT," in IEEE Internet of Things Journal, vol.6, No.6, pp.10458-10471, dec.2019, changes the spatial characteristics of the Interference by generating a pilot signal, thereby tuning the Interference to a subspace orthogonal to the desired communication. The IS power overhead IS reduced compared to IN, but space of Freedom (DoF) IS consumed to place steered interference, which IS similar to IA.

The problems existing in the prior art are as follows: the multiple access method for distinguishing user communication by frequency, time, code, space, etc. has low resource utilization rate and cannot adapt to the increasing communication demand. Although NOMA and VSDMA can obviously improve the utilization rate of the spectrum resources of the system, the complexity and the processing delay of a receiver are increased due to the SIC adopted by the receiver in NOMA, the SIC has the problem of error propagation, and the VSDMA has the problem of excessive power consumption of an extraction transmitter.

The difficulty and significance for solving the technical problems are as follows: when a plurality of users with communication requirements exist in the system, mutual interference exists among concurrent transmissions of the plurality of users, which affects the receiving effect (such as increase of bit error rate) of a receiver, and how to manage the interference among the communication of the plurality of users with lower resource overhead to realize multiple access is a problem worthy of study.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a Space Domain and Power Domain combined Multiple Access (SPD-VSDMA) method based on Signal Virtual decomposition.

The invention is realized by introducing a harmonic transmitter in an uplink communication system with a plurality of expected transmitters and a common receiver, enabling the plurality of expected transmitters to transmit signals to the common receiver by using the same frequency at the same time, traversing the power overhead of virtual harmonic signal components by the harmonic transmitter to minimize the power overhead of harmonic signals, selecting a proper orthogonal base according to the power overhead, taking the spatial characteristics represented by basis vectors contained in the orthogonal base as the direction of a plurality of paths of expected signals recovered at the common receiver, further solving the harmonic signals capable of interacting with the actual transmitted signals of the expected transmitters to recover the plurality of paths of the expected signals orthogonal to each other at the common receiver, determining the precoding vectors of the harmonic signals and data symbols carried by the harmonic signals, constructing the harmonic signals according to the precoding vectors of the harmonic signals and the data symbols carried by the harmonic signals and transmitting the harmonic signals to the common receiver A receiver, the harmonic signal being virtually decomposable into a plurality of mutually orthogonal harmonic signal components, the harmonic signal components interacting with the signal actually transmitted by the desired transmitter at the common receiver, such that the common receiver can recover from the received mixed signal a plurality of mutually orthogonal signals and from these signals the desired data for a plurality of users.

Compared with VSDMA, the invention has the following characteristics:

(1) the harmonic signal in the invention is formed by the interaction of a plurality of mutually orthogonal virtual harmonic signal components in a spatial domain, and the extraction signal in the VSDMA is formed by the superposition of a plurality of in-phase extraction signal components;

(2) the harmonic transmitter in the invention traverses the power cost of the virtual harmonic signal component to minimize the power cost of the harmonic signal, selects a proper orthogonal base according to the power cost, takes the spatial characteristics represented by the base vector contained in the orthogonal base as the direction of a multi-channel expected signal recovered at a public receiver, and directly recovers the expected signal by traversing the virtual decomposition factor in VSDMA;

(3) the invention can minimize the power overhead of the harmonic signal, is a power domain adjustment, and the power domain adjustment simultaneously affects the precoding vector design of the harmonic signal and the spatial characteristics of a plurality of paths of expected signals recovered by a common receiver, is essentially the joint design of a space domain and a power domain, and does not relate to the power domain adjustment in VSDMA.

Further, the space domain and power domain joint multiple access method based on the signal virtual decomposition comprises the following steps:

(1) the wireless uplink communication system is composed of N desired transmitters Tx_k(k-1, 2, …, N), 1 common receiver and 1 harmonic transmitter Tx_cComprising a common receiver sharing channel state information with desired transmitters, the common receiver being adapted to transmit to each desired transmitterChannel state information is shared to the transmitter and the transmitter Tx is expected at the same time_kSharing the actual sending data information to a harmonic transmitter;

(2) each desired transmitter Tx_kDesigning a desired transmitter precoding vector p according to a channel matrix between the desired transmitter and a common receiver_k(k 1,2, …, N), the desired transmitter Tx_kPrecoding a vector p according to the desired transmitter_kSending a payload data x to a common receiver_k'Signal s'_kWherein x is_k' represents data that a transmitter is expected to actually transmit to a common receiver;

(3) the harmonic transmitter selects an orthogonal base through traversal, takes the spatial characteristics represented by the basis vectors contained in the orthogonal base as the directions of the multi-channel expected signals recovered by the common receiver, solves the interaction between the spatial characteristics and the actual transmission signals of the expected transmitter to obtain the harmonic signals of the recovered expected signals, and further calculates the harmonic transmission data x_cAnd its harmonic transmitter precoding vector p_cA harmonic signal s_cThe method comprises the steps that the method can be decomposed into a plurality of mutually orthogonal virtual harmonic signal components virtually, a harmonic transmitter shares information of harmonic signals and selected orthogonal bases to all expected transmitters, the obtained orthogonal bases are shared to a common receiver at the same time, and the harmonic transmitter sends a path of harmonic signals carrying harmonic data to the common receiver;

(4) desired transmitter Tx_kDetermining a matched filter vector at the common receiver based on the quadrature basis selected by the harmonic transmitter and calculating a filtered desired data gain α_kThe desired transmitter will calculate the resulting filtered desired data gain α_kSending to a common receiver, the common receiver adopting the orthogonal basis shared by the harmonic transmitter, determining a filtering vector, performing matched filtering on the received mixed signal, and dividing the filtering output by the expected data gain alpha_kTo recover the desired data x_k。

Further, the first step specifically includes:

common receiver Rx₀Broadcast pilot signalNumber, from which each desired transmitter estimates its sum Rx₀And feeds back to Rx₀，Rx₀Sharing channel state information of each desired transmitter to the reconciliation transmitter, while the desired transmitter shares data information actually transmitted to the reconciliation transmitter, wherein the common receiver Rx₀And Tx_kThe channel state information between is recorded as H_k(k＝1,2,…,N)，Rx₀And Tx_cThe channel state information between is recorded as H_c。

Further, the second step specifically includes:

(2a) desired transmitter Tx_kProcessing precoding vector p_kSelected from the pair channel matrix H_kCarrying out singular value decomposition to obtain a first column vector of a right singular matrix, wherein the first column vector carries data x_k' as slave to desired transmitter Tx_kOriginal expected data x of_kRandomly selected, x, of the same set of modulation symbols to which they belong_kOriginal expected data indicating that the expected transmitter wishes to transmit to the common receiver;

(2b) harmonic transmitter Tx_cTo a common receiver Rx₀Transmitting data x_cThe common receiver performs a virtual orthogonal decomposition on the received harmonic signal to obtain N virtual harmonic signal components

Wherein the harmonic signalP_cIndicating the transmission power, s, of the transmitter transmitting the tone signal_ck(k-1, 2, …, N) represents the k-th virtual harmonic signal component,<s_cj,s_cl>representing virtual harmonic signal components s_cjAnd s_clThe inner product of (c), i.e., represents the calculated modulus value, j, l belongs to {1,2, …, N } and j is not equal to l;

(2c) common receiver Rx₀Received from the kth expectationTransmitter Tx_kIs recorded as the actual transmission signalThis component is combined with a virtual harmonic signal component s_ckInteract to obtain s_ck+s′_k，s_ck+s′_kIs the k-th desired signal s recovered by the common receiver_kWherein, in the step (A),represents Tx_kThe transmit power of.

Further, the third step specifically includes:

(3a) reconciling the transmitter from the recovered desired signal s_kUnit direction vector of (k 1,2, …, N)And actual transmission signal s'_kIn thatOrthogonal projection ofObtaining virtual harmonic signal components:

wherein, byThe constructed orthogonal vectors form a set of orthogonal bases;

the harmonic transmitter transmits signal s 'according to the actual of the desired transmitter'_kThe orthogonal basis containing a vector representing the common receiver Rx and minimizing the harmonic signal power overhead is obtained by traversal₀Direction of recovered multipath desired signals, common receiver Rx₀The directions of the recovered multiple expected signals are respectively located atThe orthogonal basis comprises a basis vector in the characterized spatial direction.

(3b)η_k＝||s_ck||²(k-1, 2, …, N) is the power overhead of the virtual harmonic signal component required for the transmission signal of the kth desired transmitter, in the interval (0, | s'_k||²) Internal pair eta_kTraversing values are carried out, and each eta in the traversing process is subjected to_kThe values are all based on equation (2) to obtain a unit vectorAnd judgeWhether the condition is satisfied:

to satisfy the first subformula of the formula (3)And η corresponding thereto_kStoring as if it is a eta_kExhibiting a plurality of first sub-types conforming to formula (3)Then these will be metRecord asWill correspond to eta_kIs marked asAnd storing;

for pairs having different subscripts kAre combined, each onek is only from j_kSelecting one j from 1,2, …_kAs mentioned aboveOne element in the combination can obtain a plurality of combinationsEach group is divided into two groupsAny two elements in (b) are tested by substituting the second subformula of the formula (3), and any two elements satisfy the second subformula of the formula (3)Saving is performed, and each group saved is calculatedCorresponding harmonic power overhead, the t-th group corresponding harmonic power overheadChoose the smallestIs marked asAnd obtain the correspondingIs marked asThat is, the orthogonal basis obtained by traversal is used for restoring the signal actually transmitted by the expected transmitter to the space direction represented by the basis vector contained in the orthogonal basis, and the power overhead of the harmonic transmitter is minimum and isThe harmonic signal may be represented as:

(3c) computing a transmitted precoding vector p for a harmonic signal_cAnd the harmonic signal transmitting data x_c. According toAnd the minimum power overhead P calculated_cminCan obtain the productAccording to the harmonic signal obtained by the formula (4), letParameter a_kAndis a known amount, whereinThe number of antennas of the harmonic transmitter is adjusted, and the harmonic transmission data of the harmonic transmitter is expressed as x_c＝a_c+b_ci (definition)B is available_c＝a_c tanθ_c) Wherein theta_cSelecting by the harmonic transmitter in the phase interval [0,2 pi ]; precoding vectors for harmonic signalsWherein a is_ckAndis an unknown quantity, and | | | p_cIf 1, then there isThus, can obtainAccording to the principle that the real part and the imaginary part of the complex number are equal to each other, the equation system can be obtained:

all sub-formulae (corresponding) included in the pair formula (5)) The equal sign of (D) is squared and added to obtainThe harmonic sending data carried by the harmonic signal is obtained as follows:

x_c＝a_c+a_c tanθ_ci (6)

wherein the content of the first and second substances,

by | | | p_c1, pairBoth sides of equal sign are divided byTo obtainThe precoding vector to get the harmonic signal is:

the harmonic transmitter shares the information of the harmonic signal and the orthogonal base obtained by traversal to all expected transmitters, shares the orthogonal base obtained by traversal to a public receiver, and sends a path of harmonic signal carrying harmonic data to the public receiver.

Further, the fourth step specifically includes:

desired transmitter Tx_k(k 1,2, …, N) using beamforming to transmit powerAnd precoding p_kTransmitting data x to a common receiver_k'Signal s'_kHarmonizing the transmitter with a transmission power P_cminAnd precoding p_cReconciling transmit data x to a common receiver_cIs a harmonic signal s_cAt a common receiver Rx₀Matched filtering each of the recovered mutually orthogonal desired signal components, the desired transmitter determining a matched filtered vector at the common receiver based on the selected orthogonal basis information from the reconciling transmitter, the filtered vector being recorded asThe desired transmitter can calculate the desired data x after filtering according to the information of the harmonic signal shared by the harmonic transmitter and the orthogonal base_kGain alpha of_k(k ═ 1,2, …, N) is:

the desired transmitter is expected to gain the filtered desired data by α_kSending to a common receiver, the common receiver determining a filter vector f using the quadrature basis shared by the harmonic transmitters_kMatched filtering the received mixed signal and dividing the filtered output by the desired data gain alpha_kThereby recovering the desired data x_k：

The invention aims to provide a space domain and power domain combined multiple access method based on signal virtual decomposition, which is suitable for an uplink wireless communication system comprising a plurality of transmitters and a common receiver.

In summary, the advantages and positive effects of the invention are: in the uplink communication system, the harmonic transmitter traverses the power overhead of virtual harmonic signal components to minimize the power overhead of harmonic signals, selects a proper orthogonal base according to the power overhead, uses the spatial characteristics represented by the base vectors contained in the orthogonal base as the direction of a plurality of paths of expected signals recovered at a common receiver, further solves the harmonic signals capable of interacting with the actual transmission signals of the expected transmitter to obtain the desired signals of the plurality of paths of mutually orthogonal expected signals, determines the pre-coding vectors of the harmonic signals and the data symbols carried by the harmonic signals, constructs the harmonic signals according to the pre-coding vectors of the harmonic signals and the data symbols carried by the harmonic signals and transmits the harmonic signals to the common receiver, the harmonic signals can be virtually decomposed into a plurality of mutually orthogonal harmonic signal components, and the harmonic signal components and the signals actually transmitted by the expected transmitter interact at the common receiver, the common receiver can recover a plurality of mutually orthogonal signals from the received mixed signals and recover the expected data of a plurality of users from the signals, thereby realizing multiple access. The method can be used for solving the interference problem in the multi-user communication system and improving the spectrum efficiency of the communication system. The SPD-VSDMA minimizes the power overhead of the harmonic signal, is a power domain adjustment, and the power domain adjustment simultaneously influences the precoding vector design of the harmonic signal and the spatial characteristics of a plurality of paths of expected signals recovered by a common receiver, and is a joint design of a space domain and a power domain.

Drawings

FIG. 1 is a schematic flow chart of a spatial domain and power domain combined multiple access method (SPD-VSDMA) based on signal virtual decomposition according to the present invention;

FIG. 2 is a system model schematic of the present invention;

fig. 3 is a schematic diagram of the SPD-VSDMA principle when the number N of users is 2;

FIG. 4 is a schematic diagram of control information interaction according to the present invention;

fig. 5 IS a schematic diagram of the comparison of the system average spectral efficiency of SPD-VSDMA and Zero Forcing reception (ZF), Matched Filtering (MF), Interference Steering (IS), Interference Neutralization (IN), and Virtual Signal Division based Multiple Access (VSDMA) methods according to the present invention.

FIG. 6 is an overhead comparison diagram of the harmonic signal power of the SPD-VSDMA and VSDMA of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in detail below with reference to examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a space domain and power domain joint multiple access method based on signal virtual decomposition aiming at a multi-user uplink communication scene with co-channel interference, which is suitable for a wireless communication system comprising a plurality of expected transmitters and a common receiver and solves the problem of wireless interference among multi-channel concurrent communication. By introducing a harmonic transmitter, the harmonic transmitter traversing the power cost of the virtual harmonic signal component to minimize the power cost of the harmonic signal, selecting a suitable orthogonal base according to the power cost, taking the spatial features represented by the base vectors contained in the orthogonal base as the direction of the multiple desired signals recovered at the common receiver, further solving the harmonic signal capable of interacting with the actual transmission signal of the desired transmitter to recover the desired signal at the common receiver, determining the precoding vector of the harmonic signal and the data symbols carried by the harmonic signal, the harmonic transmitter constructing the harmonic signal according to the precoding vector of the harmonic signal and the harmonic data carried by the harmonic signal and transmitting the harmonic signal to the common receiver, the harmonic signal being virtually decomposed into a plurality of mutually orthogonal harmonic signal components, the harmonic signal components interacting with the signal actually transmitted by the desired transmitter at the common receiver, so that the common receiver can recover a plurality of mutually orthogonal signals from the received mixed signal and recover the desired data of a plurality of users from the signals.

The SPD-VSDMA minimizes the power overhead of the harmonic signal, is a power domain adjustment, influences the precoding vector design of the harmonic signal at the same time, and the spatial characteristics of a plurality of paths of expected signals recovered by a common receiver, and is a joint design of a space domain and a power domain. The method can make the public receiver recover the multi-channel expected data without interference, realize multiple access and improve the frequency spectrum efficiency of the system.

As shown in fig. 1, a space domain and power domain joint multiple access method based on virtual signal decomposition according to an embodiment of the present invention, applied to a multi-user uplink communication system, includes the following steps:

step 101, the system is composed of N expected transmitters, 1 public receiver and 1 harmonic transmitter, the public receiver and the expected transmitters share channel state information, the public receiver shares the channel state information of each expected transmitter to the harmonic transmitter, and simultaneously the expected transmitter shares actually sent data information to the harmonic transmitter;

102, each expected transmitter obtains a precoding vector p by performing singular value decomposition on a channel matrix between the expected transmitter and a public receiver_k(k-1, 2, …, N). Desired transmitter Tx_kSending a payload data x to a common receiver_k'Signal s'_k；

Specifically, the desired transmitter Tx_iSending a payload data x to a common receiver_k'Signal s'_k，x_k' can be selected from_kOriginal expected data x of_kRandomly selecting the same modulation symbol set.

Step 103, the harmonic transmitter selects a suitable orthogonal basis by traversing, and uses the spatial features represented by basis vectors contained in the orthogonal basis as the directions of the multipath expected signals recovered at the common receiver, thereby solving the interaction between the actual transmission signals of the expected transmitter and the harmonic transmitterRecovering the desired signal's harmonic signal at the common receiver and further obtaining the harmonic transmitted data x_cAnd its harmonic precoding vector p_cThe harmonic transmitter shares the information of the harmonic signal and the selected orthogonal base to all expected transmitters, shares the orthogonal base to a common receiver at the same time, and transmits the harmonic signal to the common receiver;

in particular, the harmonic signal may be virtually decomposed into a plurality of mutually orthogonal virtual harmonic signal components.

The desired transmitter calculates 104 a filtered desired data gain α_k(k-1, 2, …, N) and sending the filtered desired data gain to the common receiver, which filters the recovered mixed signal with a matched filter vector to recover the desired data x_k。

Specifically, the desired transmitter Tx_k(k-1, 2, …, N) determining a matched filter vector at the common receiver based on the selected orthogonal basis information from the harmonic transmitter, calculating a filtered desired data gain α_k(k-1, 2, …, N) and applying the filtered desired data gain α_kSending to a common receiver, the common receiver filtering the received mixed signal using a quadrature-basis-determined filter vector shared by the harmonic transmitters, and dividing the filtered output by the desired data gain α_iRecovering the expected data x_i。

The application of the principles of the present invention will now be described in further detail with reference to the accompanying drawings.

As shown in fig. 2, the present invention studies a wireless communication uplink transmission system. There are N desired transmitters in the system, all of which are directed to a common receiver Rx₀And sending the signal. Tx_kRepresents the kth desired transmitter, is provided withRoot antenna of transmission power ofWhere k is 1,2, …, N. N desired transmittersA Beamforming (BF) method is adopted to transmit a single-path data stream to a common receiver. The desired transmitter no longer transmits the desired data x_kBut rather data x is sent_k' all desired transmitters use the same modulation scheme, x_k' can be selected from_iOriginal expected data x of_iRandomly selecting the same modulation symbol set. In order to correctly distinguish the signals from the N desired transmitters at a common receiver, a harmonic transmitter Tx is introduced_cWhich is equipped withRoot antenna with transmitting power of P_c。Tx_cSending a harmonic signal carrying harmonic sending data x_c. In addition, a common receiver Rx₀Is provided withThe root receives the antenna.Andrespectively represent Tx_kAnd Rx₀、Tx_cAnd Rx₀Channel State Information (CSI), Tx, between_kNeed to associate its own data information with Rx₀To the reconciliation transmitter. The channel matrix follows a complex gaussian distribution of zero mean, unit variance. Assuming that the channel state remains unchanged within a Block (Block) of several consecutive time slots, the link for CSI and control signaling is stable, error-free, and the transmission delay is negligible compared to the time scale of channel variations. Rx₀The CSI for all channels can be accurately obtained through feedback from the desired transmitter. Multiple desired transmitters to Rx₀The signals of the transmitter are mutually interfered, and the harmonic transmitter is introduced to Rx₀Sending a tone signal at Rx with the desired transmitter₀Interact with each other, canLet Rx be₀And recovering a plurality of paths of mutually orthogonal expected signals from the received mixed signals, and further demodulating the user data information from the expected signals. The SPD-VSDMA minimizes the power overhead of the harmonic signal, is a power domain adjustment, and the power domain adjustment simultaneously influences the precoding vector design of the harmonic signal and the spatial characteristics of a plurality of paths of expected signals recovered by a common receiver, and is a joint design of a space domain and a power domain.

Fig. 3 shows the design principle of SPD-VSDMA. Harmonic signal s_cCan be virtually decomposed into s_c1And s_c2Their actual transmission signal s with the desired transmitter₁' and s₂' acting separately, can be at Rx₀To recover mutually orthogonal desired signals s₁And s₂，s₁And s₂Can be characterized by a set of orthonormal basesDetermining that the spatial features of the basis vectors contained in the orthogonal basis correspond to the signal vectors s₁And s₂In the direction of (a).

The invention has the following implementation steps: a suitable scenario for this embodiment is that it is assumed that the transmitter and the receiver have already established time synchronization, and then multi-user communication can be performed according to the operation of the present invention. The data information in this embodiment includes data information expected to be transmitted by the transmitter, actual transmission data information expected to be transmitted by the transmitter, and reconciliation data information sent by the reconciliation transmitter.

Step 1, the system is composed of 2 expected transmitters, 1 public receiver and 1 harmonic transmitter, the public receiver and the expected transmitters share channel state information, the public receiver shares the channel state of each expected transmitter to the harmonic transmitter, and simultaneously the expected transmitter shares the actually sent symbol information to the harmonic transmitter;

specifically, the system includes 2 desired transmitters as Tx₁And Tx₂With 1 harmonic transmitter Tx_cWhereinCommon receiver Rx₀Broadcast pilot signals, each desired transmitter estimates channel information and feeds back to Rx₀Then a common receiver Rx₀Channel state information for each desired transmitter is shared to the reconciliation transmitter, while the desired transmitter shares the symbol information actually transmitted to the reconciliation transmitter. Common receiver Rx₀And Tx_kThe channel state information between (k 1,2) is denoted as H_k(k＝1,2)，Rx₀And Tx_cThe channel state information between is recorded as H_c。

Step 2, expect transmitter Tx₁And Tx₂Designing precoding vector p according to channel matrix between self and public receiver_k(k is 1, 2). Two desired transmitters send a carrier symbol x to a common receiver_kSignal s ' of' (k-1, 2) '_k(k＝1,2)；

(2a) Precoding vectors p for two desired transmitters₁And p₂By separately aligning the channel matrices H₁And H₂Singular value decomposition is performed to obtain, wherein the precoding of the desired transmitter is selected from a first column of vectors of a right singular matrix obtained by performing singular value decomposition on the channel matrix. Desired transmitter Tx₁And Tx₂Using Binary Phase Shift Keying (BPSK) modulation, x₁' and x₂' can be derived from the original expected data x of the expected transmitter respectively₁And x₂The same modulation symbol set omega { -1,1} is randomly selected, wherein x'_k(k ═ 1,2) denotes data symbols which the transmitter is expected to actually transmit to the common receiver, x_k(k ═ 1,2) indicates the original expected data that the expected transmitter wishes to send to the common receiver.

(2b) Harmonic transmitter Tx_cTo a common receiver Rx₀Sending a payload x_cThe common receiver performs virtual quadrature decomposition on the received harmonic signal to obtain 2 virtual harmonic signal components, namely:

wherein the harmonic signalP_EIndicating the transmission power, s, of the transmitter transmitting the tone signal_c1And s_c2Representing a virtual harmonic signal component, < s >_c1,s_c2>Representing virtual harmonic signal components s_c1And s_c2The inner product of (d) |, represents the calculated modulus.

(2c) Common receiver Rx₀Received from the desired transmitter Tx₁And Tx₂Is actually transmitted asThis component is combined with a virtual harmonic signal component s_ck(k-1, 2) interaction to give s_ck+s′_k，s_ck+s′_kThe k path expected signal s recovered by the common receiver_kI.e. s_k＝s_ck+s′_kWherein, in the step (A),andrepresenting the transmit power of the desired transmitter.

Step 3, the harmonic transmitter selects a proper orthogonal base through traversal, takes the spatial characteristics represented by the basis vectors contained in the orthogonal base as the direction of the multi-channel expected signals recovered at the public receiver, further solves the interaction between the spatial characteristics and the actual transmission signals of the expected transmitter, recovers the harmonic signals of the expected signals at the public receiver, and further obtains the harmonic transmission data x carried by the harmonic signals_cAnd its harmonic precoding vector p_cWherein the harmonic signal is virtually decomposed into a plurality of mutually orthogonal virtual harmonic signal components, the harmonic transmitter transmitting information of the harmonic signalThe selected orthogonal basis is shared to all desired transmitters and the selected orthogonal basis is simultaneously shared to a common receiver, and the reconciliation transmitter transmits a reconciliation signal to the common receiver;

(3a) the multiple access design of the harmonic transmitter according to different orthogonal bases can generate different power overhead of harmonic signals, and in order to minimize the power overhead of the harmonic signals under the given orthogonal bases, the recovered desired signals s₁And s₂Is expressed as a unit direction vectorAndthe orthogonal projection of the actual transmitted signal in the direction of the desired signal isThe virtual harmonic signal component can be obtained as equation (2), where k is 1,2Andthe constructed orthogonal vectors form a set of orthogonal bases. The harmonic transmitter transmits signal s 'according to the actual of the desired transmitter'_kThe orthogonal basis containing the vector representing the common receiver Rx and minimizing the harmonic signal power overhead can be obtained by traversal₀And recovering the directions of the two expected signals.

(3b) Let eta be₁＝||s_c1||²，η₂＝||s_c2||²Represents the power overhead of the virtual harmonic signal component required for the k (k ═ 1,2) th desired transmitter transmitted signal, in the interval (0, | s)₁′||²) Internal pair eta₁Traversing values are carried out, and each eta in the traversing process is subjected to₁The value can be obtained from equation (2) when k is equal to 1And judging each unit vector conforming to the first sub-formula of the formula (3) when k is 1Satisfies the first subformula of the formula (3) when k is 1And η corresponding thereto₁Is stored for an eta₁There may be a plurality of first subforms which correspond to the formula (3) when k is 1For each sub-formula conforming to formula (3)According toSolving unit vectorsAnd the resulting unit vectorThe first subformula of equation (3) must be satisfied when k is 2, according to η₂＝||s_c2||²Solving for η₂Fitting these to formula (3)Andrespectively record asAndand save each groupThe corresponding power cost is recorded as the corresponding power cost of the t-th groupObtaining the harmonic power overhead and selecting the minimumIs marked asAnd get correspondingAndare respectively marked asAndthenAndthat is, the orthogonal basis obtained by traversal is used for restoring the signal transmitted by the expected transmitter to the space direction represented by the basis vector contained in the orthogonal basis, and the power overhead of the harmonic transmitter is minimum and isThe harmonic signal may be represented as:

(3c) and calculating a transmitting precoding vector of the harmonic signal and harmonic sending data carried by the harmonic signal. According toAnd the minimum power overhead P calculated_cminCan obtain the productAnd the harmonic signal obtained according to equation (11), andparameter a₁，a₂，b₁And b₂The transmitted data symbols of the harmonic transmitter may be represented as x for a known quantity_c＝a_c+b_ci (definition)B is available_c＝a_c tanθ_c) Wherein theta_cSelected by the harmonic transmitter in the phase interval 0,2 pi). Precoding vectors for harmonic signalsWherein a is_c1，a_c2，b_c1And b_c2Is an unknown number, and | | | p_cIf 1, then there isThereby can obtainThen equation set (5) can be obtained according to the principle that the real part and the imaginary part of the complex number are equal to each other, where k is 1 and 2.

The two sides of the equal sign of all the sub-formulae included in the formula (5) are squared and added to obtainTherefore, it isThe symbols carried by the harmonic signal can be obtained as:

x_E＝a_c+a_c tanθ_ci (12)

by | | | p_c1, pairBoth sides of equal sign are divided byCan obtain the productThe precoding vector from which the harmonic signal can be derived is:

the harmonic transmitter shares the information of the harmonic signal and the orthogonal base obtained by traversal to all expected transmitters, shares the orthogonal base obtained by traversal to a public receiver, and sends a path of harmonic signal carrying harmonic data to the public receiver.

Step 4, expect transmitter Tx₁And Tx₂Determining a matched filter vector at a common receiver based on selected orthogonal bases from harmonic transmitters and calculating a filtered desired data gain α₁And alpha₂The calculated expected data gain is then sent to a common receiver, which filters the received mixed signal using a harmonic transmitter-shared quadrature-basis-determined filter vector and divides the filtered output by the expected data gain to recover the expected data x₁And x₂。

(4a) Desired transmitter Tx_k(k 1,2) using beamforming to transmit powerAnd precoding p_k(k is 1,2) eachTransmitting data x to a common receiver₁' and x₂' of a transmitter to transmit power P_cminAnd harmonic precoding p_cTransmitting carrier-and-tone transmit data x to a common receiver_EAt the common receiver, matched filtering the recovered desired signal component, the desired transmitter determining a matched filtered vector at the common receiver based on the selected orthogonal basis from the harmonic transmitter, the filtered vector noted asAndthe desired transmitter may calculate the gain of the desired data obtained after filtering according to the information of the harmonic signal shared by the harmonic transmitter and the orthogonal base as follows:

(4b) the desired transmitter sends the filtered desired data gain to the common receiver, which filters the received mixed signal using the orthogonal basis-defining filter vector shared by the harmonic transmitter and divides the desired data gain by the filter output to recover the desired data x₁And x₂：

The spectral efficiency of the system can be obtained as follows:

fig. 4 shows a schematic diagram of control information interaction according to the present invention. As shown, the first stage corresponds to step (1), where the desired transmitter shares its channel state information to the common receiver and shares the actually transmitted symbol information to the reconciliation transmitter, which then shares the channel state information of the desired transmitter to the reconciliation transmitter. And the second stage corresponds to the steps (3) and (4), the harmonic transmitter shares the harmonic signal and the selected orthogonal base to the expected transmitter according to the orthogonal base and the harmonic signal obtained by traversing, shares the selected orthogonal base to the common receiver, and further calculates the expected data gain according to the orthogonal base shared by the harmonic transmitter and the harmonic signal information, and then shares the gain to the common receiver.

The application effect of the present invention will be described in detail with reference to the simulation.

Firstly, simulation conditions:

for the purpose of evaluating the performance of the invention, we assume that the communication system comprises two desired transmitters Tx₁And Tx₂One harmonic transmitter Tx_cAnd a common receiver Rx₀It is assumed that all transmitters and receivers are configured with two antennas. Tx₁And Tx₂Using BPSK modulation, and going to Rx separately₀Transmitting data x₁' and x₂' actual transmission signal s₁' and s₂'. The desired data transmitted by the desired transmitter to the common receiver is x₁And x₂Wherein x is₁′,x₂′,x₁,x₂Are all taken from the modulation symbol set omega { -1,1 }. Tx₁And Tx₂Has the same transmission power ofNoise power ofSignal-to-Noise Ratio (SNR) ofIn the simulation, SNR E [ -10,20 ] is selected]dB。

Performance simulations and comparisons of ZF, MF, IS, IN and VSDMA with the proposed scheme were performed IN the above communication scenarios.

Secondly, simulating contents:

fig. 5 of the drawings IN the specification shows a case where the average Spectral Efficiency (SE) of a system using SPD-VSDMA, ZF, MF, IS, IN, and VSDMA varies with the signal-to-noise ratio when the desired number N of transmitters IS 2. As shown in fig. 4, the SE performance of SPD-VSDMA and VSDMA almost overlaps and is better than SE of other methods, because both SPD-VSDMA and VSDMA can ensure that the recovered multiple desired signals are orthogonal to each other at a common receiver, thereby eliminating mutual interference between the multiple desired signals. With ZF reception, although there is no interference between the desired signals, the power of the desired signals is lost, and thus the performance of SPD-VSDMA is better than ZF. At low signal-to-noise ratio, the SE of MF is better than ZF, close to SPD-VSDMA. The MF can maximize the receiving of the expected signal power, the performance of the MF mainly depends on the strength of interference, when the signal-to-noise ratio is low, the interference between two paths of expected signals is small, and noise is a main factor influencing SE (sequence error) so that the performance of the MF is equivalent to that of SPD-VSDMA; when the signal-to-noise ratio is increased and the interference between concurrent signals is increased, the receiving signal-to-interference-and-noise ratio of the MF is reduced, so that the performance of the MF is inferior to that of the SPD-VSDMA. It should be noted that IN the comparative simulations above regarding IS and IN, the total transmit power of the desired transmitters IS equal, i.e., the power of the SPD-VSDMA's harmonic transmitter would be equally distributed to both desired transmitters of IS and IN. With IS, the desired transmitter needs to consume a portion of the power for transmission of the pilot signal to make the multiple desired signals observed by the common receiver orthogonal to each other, but the power overhead of the pilot signal reduces the power for transmission of the desired data, so the SE of IS inferior to SPD-VSDMA. Since the transmission power of two desired transmitters is the same, the IN requires higher power overhead, resulting IN less power for transmitting desired data, and IN neutralizes one interference path IN order to recover the desired signal, so that only one data information path can be recovered at the receiver, so the SE of IN is the lowest.

Fig. 6 presents a simulated comparison of the reconciliation power costs of SPD-VSDMA and VSDMA, which we normalized the reconciliation power costs of the two methods to the power cost of VSDMA. As shown, the reconciliation power overhead for SPD-VSDMA is always lower than VSDMA, approximately 93% of VSDMA power overhead. This is because SPD-VSDMA can save the power overhead of the reconciling transmitter to the greatest extent by traversing through a set of orthogonal bases that minimize the power overhead of the reconciling signal as compared to VSDMA.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.