WO2017069510A1

WO2017069510A1 - Signal transmitting method, signal receiving method, transmitter and receiver

Info

Publication number: WO2017069510A1
Application number: PCT/KR2016/011746
Authority: WO
Inventors: Chen QIAN; Pengfei Sun; Bin Yu
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2015-10-19
Filing date: 2016-10-19
Publication date: 2017-04-27
Also published as: KR102650862B1; KR20180057611A

Abstract

The present application provides a signal transmitting method, the method comprising: transmitting, by a transmitter, link grouping configuration information; wherein said link grouping configuration information is, after dividing links into at least two groups, information of the links contained in each of the groups; layering, by the transmitter, data flow to be transmitted according to grouping of the links; performing, by the transmitter, spatial modulation on the layered data flow; performing, by the transmitter, multi-carrier modulation on the spatial modulated signals; transmitting, by the transmitter, the multi-carrier modulated signals. The present application further provides a signal receiving method, a transmitter and a receiver. The present application provides different levels of protection for different data flows by use of the features of the spatial modulation system, so that users in different channel conditions are able to obtain services of different quality.

Description

SIGNAL TRANSMITTING METHOD, SIGNAL RECEIVING METHOD, TRANSMITTER AND RECEIVER

The present application relates to wireless communication technology field, and more particularly to a signal transmitting method, a signal receiving method, a transmitter and a receiver.

The rapid development of information industry, particularly the increasing demand from the mobile Internet and the Internet of Things (IoT), brings about unprecedented challenges in the future mobile communications technology. According to the ITU-R M. [IMT.BEYOND 2020.TRAFFIC] issued by the International Telecommunication Union (ITU), it can be expected that, by 2020, mobile services traffic will grow nearly 1,000 times as compared with that in 2010 (4G era), and the number of user device connections will also be over 17 billion, while a vast number of IoT devices gradually expand into the mobile communication network, and the number of connected devices will be even more amazing. In response to this unprecedented challenge, the communications industry and academia have prepared for 2020s by launching an extensive study of the fifth generation of mobile communications technology (5G). Currently, in ITU-R M. [IMT.VISION] from ITU, the framework and overall objectives of the future 5G have been discussed, where the demands outlook, application scenarios and various important performance indexes of 5G have been described in detail. In terms of new demands in 5G, the ITU-R M. [IMT.FUTURE TECHNOLOGY TRENDS] from ITU provides information related to the 5G technology trends, which is intended to address prominent issues such as significant improvement on system throughput, consistency of the user experience, scalability so as to support IoT, delay, energy efficiency, cost, network flexibility, support for new services and flexible spectrum utilization, etc.

Multiple-input multiple-output (MIMO) technology is an important one to improve system spectral efficiency. As MIMO technology can effectively improve system data rate and improve the system link stability, it has been widely used in the fields of broadcast audio and video, as well as in the civilian communications systems, such as the Long Term Evolution (LTE) system corresponding to the Evolved Universal Terrestrial Radio Access (E-UTRA) protocol formulated by the 3rd Generation Partnership Project (3GPP), the European Digital Video Broadcasting (DVB) and IEEE802.16 World Interoperability for Microwave Access (WiMAX) , etc. By establishing communication links between the different antennas at the transmitting and receiving sides, MIMO technology can provide spatial diversity gain and spatial multiplexing gain for systems. By transmitting the same data in different links, MIMO technology can improve the reliability of data transmission, thereby obtaining the diversity gain; by transmitting different data in different links, MIMO technology can improve the system spectral efficiency without increasing the transmission bandwidth, thereby improving the transmission data rate. By means of the channel state information of the transmitting side, MIMO technology can further improve system overall spectral efficiency through, in combination with pre-coding, serving a number of users with the same time-frequency resources. At present, MIMO technology, as a key technology, can well support the 4G Mobile Broadband (MBB) service demands. In 5G, the existing MIMO technology will be difficult to meet the greatly improved data rates because the demand for spectral efficiency, energy efficiency and data rates will be further improved. Therefore, the evolved MIMO technology, i.e. large-scale MIMO, has gained wide attentions from academia and the industry. By deploying antennas far more than the number of users at the transmitting side, large-scale MIMO technology can get more degrees of spatial freedom while being able to get greater array processing gain (finer beam), and by a simple linear operation, it can distinguish users from each other completely, thus enabling the spectral efficiency and energy efficiency to get further huge improvements. In practical application scenarios, however, MIMO technology as well as large-scale MIMO technology also encountered some problems, for example: 1. whether MIMO technology is effective or reliable, is relying on whether the accurate channel state information can be acquired at the transmitting side. If the channel state information at the transmitting side is not accurate enough, it will result in a significant decrease in system gain. Present MIMO technology relies on the channel estimation based on reference signals and on the feedback. However, when the number of antennas increases, the overhead associated with the reference signals and feedback will severely reduce the system spectral efficiency . 2. The requirements for the inter-antenna synchronization are strict. 3. The inter-channel interference needs to be dealt with at the receiving side. 4. Although multi-user MIMO can improve the overall spectral efficiency of cells, but it has no help for the improvement of single user spectral efficiency.

As a branch of MIMO technology, Spatial Modulation (SM) gained widespread attention from academia in recent years. SM technology uses a portion of the information bits for selecting transmit antennas with only one antenna for each transmission. By using the antenna index as additional carrier to transmit information, a three-dimensional constellation is constructed based on traditional two-dimensional constellation, thereby getting higher spectral efficiency than a single-antenna system. Meanwhile, the SM technology further solved some problems in traditional MIMO technology. For example, since each transmission uses only a single antenna, SM technology does not require to perform complex inter-antenna synchronization and elimination of the inter-link interference at the receiving side, thereby simplifying the processes at the receiving side; SM technology can improve the single user spectral efficiency, and therefore is more suitable for some scenarios that need to improve single user data rate; SM technology does not require pre-coding at the transmitting side, and therefore no feedback is needed at the receiving side; the transmitting side requires only one RF link, greatly reducing the overhead of the transmitting side. Although multi-carrier based SM technology losses the advantages of single RF link, the allocation of time-frequency two-dimensional resources provides a higher degree of freedom for the system, while it has also better robustness for the frequency selective fading caused by multipath.

The advantages of SM technology make it gain widespread attention in the studies of communication. The characteristics that it does not require channel feedback and it has no requirement on the number of antennas at the receiving side enable it to be particularly suitable for broadcasting data or transmitting of data in open-loop mode. To extend the applications of spatial modulation technology in the 5G, and utilize the advantages of spatial modulation technology, there is a need for deep exploration of its characteristics and improvement on its scheme in different application scenarios.

The technical problem to be solved by the present invention is that the cellular system cannot provide differentiated services for users in different channel conditions during the transmission of broadcast data. To this end, the present application provides a signal transmitting method, a receiving method, a transmitter and a receiver, which provide different levels of protections for different data flow using the features of spatial modulation system, so that users in different channel conditions are able to get services of different quality.

The present invention provides a signal transmitting method, the method comprising:

transmitting, by a transmitter, link grouping configuration information, wherein, said link grouping configuration information is, after dividing links into at least two groups, information of the links contained in each of the groups;

layering, by the transmitter, data flow to be transmitted according to grouping of the links;

performing, by the transmitter, spatial modulation on the layered data flow;

performing, by the transmitter, multi-carrier modulation on the spatial modulated signals; and

transmitting, by the transmitter, the multi-carrier modulated signals.

Preferably, said dividing links into at least two groups comprising: dividing all available links into at least two groups, resulting groups being as groups in a first layer; further dividing each of the groups in the first layer into at least two groups, respectively, resulting groups being as groups in a second layer; and by this analogy, performing the dividing until each group contains only one link or a setting requirement of link grouping has been met.

Preferably, said layering, by the transmitter, data flow to be transmitted according to grouping of the links comprising: transmitting basic data using the groups in the first layer, and transmitting auxiliary data using the groups in each of the layers other than the first layer on the basis of previous layer; wherein said auxiliary data includes at least one of: extended data based on the basic data, redundant information of the data in previous layer, and the combination of said extended data and the redundant information.

Preferably, a criterion of dividing links into groups is to allocate links with correlation indexes greater than a setting threshold into one group.

Preferably, the method further comprising: estimating, by the transmitter, the correlation indexes between the links according to information from a receiver, and hereby dynamically adjusting number of links and the grouping of links; wherein, said information from the receiver comprises channel state information fed back from the receiver and/or sounding reference signal transmitted by the receiver to the transmitter via uplink channel.

Preferably, the method further comprising: allocating users with the same link grouping configuration information into one group, and performing broadcast service on same time-frequency resources for users in the same group.

Preferably, the method further comprising: after pre-processing the spatial modulated signals, performing the multi-carrier modulation and the transmitting.

Preferably, said pre-processing comprising: performing power adjustment on the links and/or phase adjustment on the links.

Preferably, said performing power adjustment on the links comprising: adjusting, while maintaining transmission power unchanged, average transmission power of each of the groups in the first layer, so that each of the groups having different average transmission power; adjusting, while maintaining the average transmission power of each of the groups in the first layer unchanged, average transmission power of each of the groups in the second layer, so that each of the groups in the second layer can have different average transmission power; and by this analogy, performing the adjusting, until adjustment on the average transmission power of each of the groups in the lowest layer is completed.

Preferably, the criterion of adjusting average transmission power of the groups in each of the layers is that an amount of power adjustment of a layer is no more than that of its previous layer.

Preferably, said performing phase adjustment on the links comprising: randomly selecting rotation phase for the links of each of the groups in the lowest layer, the interval of rotation phase of each of the links belonging to different groups does not intersect, selecting adjacent rotation phase interval for the links of each of the groups belonging to the same group in the previous layer.

Preferably, utilizing constellation point symbols of spatial modulation to transmit data in the lowest layer, or to transmit other auxiliary or redundant information.

Preferably, the method further comprising: transmitting, by the transmitter, reference signals according to the grouping of the links.

Preferably, said transmitting, by the transmitter, reference signals according to the grouping of the links comprising: transmitting, , by the transmitter, same reference signals sequence using same time-frequency resources for the links belonging to the same group, for estimation of equivalent channel coefficient of corresponding groups.

Preferably, if the multi-carrier modulation and transmission are preformed after pre-processing the spatial modulated signal, further comprising, prior to transmitting the reference signal: performing said pre-processing on said reference signal.

Preferably, the method further comprising: dividing the layered data in each of the layers into blocks, and adding independent cyclic redundancy check (CRC) code for data of each layer in each of the blocks of data.

Preferably, the transmitter transmits link-number information and the link grouping configuration information in at least one of physical broadcast channel, physical downlink control channel and physical downlink shared channel.

Preferably, the transmitter transmits in the physical broadcast channel, physical downlink control channel or physical downlink shared channel added with additional fields, said additional fields indicating the link-number information and the link grouping configuration information.

Preferably, the transmitter transmits link-number information using CRC check masks in the physical broadcast channel, each of transmission modes of the physical broadcast channel corresponding to at least two CRC check masks, each CRC check mask corresponding to one kind of information about the number of links, respectively; wherein, the transmission modes of the physical broadcast channel include a single-antenna port transmission mode, a dual-antenna port transmission diversity mode, and a four-antenna port transmission diversity mode;

the transmitter transmits in the physical broadcast channel, physical downlink control channel or physical downlink shared channel added with additional fields, said additional fields indicating the link grouping configuration information.

The present application further provides a transmitter, comprising:

a configuration module, for transmitting link grouping configuration information, wherein, said link grouping configuration information is, after dividing links into at least two groups, information of the links contained in each of the groups;

a data layering module, for layering data flow to be transmitted according to grouping of the links;

a spatial modulation module, for performing spatial modulation on the layered data flow;

a multi-carrier modulation module, for performing multi-carrier modulation on the spatial modulated signals; and

a transmitting module, for transmitting the multi-carrier modulated signals.

The present application further provides a signal receiving method. Said method comprising:

receiving, by a receiver, link grouping configuration information;

acquiring, by the receiver, grouping of links and information of the links contained in each of the groups, according to said link grouping configuration information; and

performing, by the receiver, layered-detection on the received data according to the grouping of the links.

Preferably, performing, by the receiver, layered-detection on the received data according to the grouping of the links comprising:

detecting, by the receiver, transmitted data from all layers according to channel state information of each link, and determines number of layers up to which to be kept according to a setting criterion; wherein said setting criterion includes: comparing estimated signal-to-noise ratio of the detected data from each of the layers with a pre-set signal-to-noise ratio threshold, and in case of being higher than said signal-to-noise ratio threshold, keeping data in corresponding layer and performing subsequent processing, otherwise, performing no subsequent processing; or, said setting criterion includes: determining, by a transmitter, whether to keep data of the corresponding layer for each receiver according to whether CRC check, added by the transmitter independently for each layer of data, has passed.

Preferably, the method further comprising: detecting, by the receiver, data in each of the layers layer-by-layer according to channel state information of each of the groups, and comparing estimated signal-to-noise ratio of the detected data from each of the layers with a pre-set signal-to-noise ratio threshold, and if higher than said signal-to-noise ratio threshold, performing subsequent detection of data of next layer, and otherwise, terminating the detection.

Preferably, the method further comprising: receiving, by the receiver, reference signals according to the grouping of the links, and performing channel estimation.

The present application further provides a receiver, comprising:

a configuration information receiving module, for receiving link grouping configuration information;

a grouping acknowledgement module, for acquiring grouping of links and information of the links contained in each of the groups, according to said link grouping configuration information;

a detection module, for performing the layered-detection on the received data according to the grouping of the links.

The present disclosure also provides a signal transmitting method based on multicarrier spatial modulation. The method includes:

a transmitting apparatus determining a preprocessing base matrix, and extending the preprocessing base matrix to obtain an extended preprocessing matrix;

the transmitting apparatus preprocessing a first reference signal with the preprocessing base matrix, and transmitting the preprocessed first reference signal to a receiving apparatus; and

the transmitting apparatus performing symbol mapping and spatial modulation on a bit stream to be transmitted, preprocessing symbols obtained after spatial modulation with the extended preprocessing matrix, and transmitting the preprocessed symbols to the receiving apparatus after multicarrier modulation.

In one embodiment, the determining the preprocessing base matrix includes at least one of: calculating the preprocessing base matrix according to channel state information, using a predefined preprocessing base matrix, or selecting the preprocessing base matrix from a predefined code book according to feedback from the receiving apparatus.

In one embodiment, the calculating the preprocessing base matrix according to the channel state information includes: calculating the preprocessing base matrix according to a channel coefficient matrix using a precoding algorithm; wherein the precoding algorithm includes at least one of: matched filter algorithm, zero-forcing algorithm, and minimum mean square error precoding algorithm.

In one embodiment, the channel coefficient matrix includes equivalent frequency-domain channel coefficients consisting of multicarrier modulation, actual physical channel between the transmitting apparatus and the receiving apparatus and the multicarrier demodulation.

In one embodiment, the extending the preprocessing base matrix to obtain the extended preprocessing matrix includes any one or any combination of:

performing a linear combination to columns of the preprocessing base matrix to obtain a column of the extended preprocessing matrix;

performing phase rotation to the columns of the preprocessing base matrix to obtain columns of the extended preprocessing matrix, wherein rotated phases of different elements in each column are the same or different; and

multiplying columns of the preprocessing base matrix by a power allocation factor to obtain the columns of the extended preprocessing matrix.

In one embodiment, the number of rows of the preprocessing base matrix equals to the number of transmit antennas, the number of columns of the preprocessing base matrix is determined by the transmitting apparatus according to the channel state information fed back by the receiving apparatus and the number of available reference signals or the amount of resources available for transmitting the reference signals.

In one embodiment, the number of rows of the extended preprocessing matrix equals to the number of rows of the preprocessing base matrix, and the number of columns of the extended preprocessing matrix is larger than or equal to the number of columns of the preprocessing base matrix.

In one embodiment, the method further includes:

the transmitting apparatus determining the number of columns of the extended preprocessing matrix according to information fed back by the receiving apparatus.

In one embodiment, the method further includes:

the transmitting apparatus preprocessing a second reference signal with the extended preprocessing matrix and transmitting the preprocessed second reference signal to the receiving apparatus.

In one embodiment, the first reference signal is used for estimating a basic equivalent channel, and the second reference signal is used for correcting the estimation of the extended equivalent channel.

In one embodiment, the basic equivalent channel consists of the preprocessing base matrix, multicarrier modulation, actual physical channel and multicarrier demodulation.

In one embodiment, the method further includes:

the transmitting apparatus adjusting an inserting density of the second reference signal according to the channel state information fed back by the receiving apparatus, wherein the adjusting includes at least one of: the transmitting apparatus selecting to not insert the second signal, insert with a density lower than the number of columns of the preprocessing matrix, or insert with a density equal to the number of columns of the preprocessing matrix.

The present disclosure further provides a transmitting apparatus, including: a first preprocessing base matrix calculating module, a first preprocessing matrix extending module, a first reference signal transmitting module and a first data transmitting module; wherein

the first preprocessing base matrix calculating module is configured to determine a preprocessing base matrix;

the first preprocessing matrix extending module is configured to extend the preprocessing base matrix to obtain an extended preprocessing matrix;

the first reference signal transmitting module is configured to performing preprocessing to a first reference signal with the preprocessing base matrix and transmit preprocessed first reference signal to a receiving apparatus; and

the first data transmitting module is configured to perform symbol mapping and spatial modulation on a bit stream to be transmitted, and perform preprocessing on symbols obtained after the spatial modulation with the extended preprocessing matrix, and transmit the preprocessed symbols to the receiving apparatus after multicarrier modulation.

The present disclosure further provides a signal transmitting method based on multicarrier spatial modulation in a multi-user system, including:

a transmitting apparatus selecting a preprocessing base matrix for each terminal according to channel state information, and extending the preprocessing base matrix of each terminal to obtain a corresponding extended preprocessing matrix;

the transmitting apparatus performing preprocessing to a reference signal with respective preprocessing base matrix, and transmitting the preprocessed reference signal to a corresponding terminal, wherein the reference signals transmitted to different terminals use orthogonal resources;

the transmitting apparatus performing symbol mapping and spatial modulation respectively on a bit stream of each terminal, and performing preprocessing on symbols obtained after the spatial modulation of each terminal with the corresponding extended preprocessing matrix; and

the transmitting apparatus combining the preprocessed symbols of each terminal, and transmitting the combined symbols after multicarrier modulation.

In one embodiment, the terminals are receiving apparatuses which are served simultaneously and using the same time-frequency resources.

In one embodiment, the transmitting apparatus selecting the preprocessing base matrix for each terminal according to the channel state information includes at least one of: the transmitting apparatus calculating the preprocessing base matrix according to a channel coefficient matrix, or selecting the preprocessing base matrix from a predefined code book according to the channel state information fed back by the terminals.

In one embodiment, the channel coefficient matrix includes equivalent frequency-domain channel coefficients consisting of multicarrier modulation, actual physical channel between the transmitting apparatus and all terminals, and multicarrier demodulation of each terminal.

In one embodiment, the combining includes: adding the symbols to be transmitted on the same link.

The present disclosure further provides a transmitting apparatus, applicable to a multi-user system based on multicarrier spatial modulation, including: a second preprocessing base matrix calculating module, a second preprocessing matrix extending module, a second reference signal transmitting module, and a second data transmitting module; wherein

the second preprocessing base matrix calculating module is configured to select a preprocessing base matrix for each terminal according to channel state information;

the second preprocessing matrix extending module is configured to extend the preprocessing base matrix of each terminal to obtain a corresponding extended preprocessing matrix;

the second reference signal transmitting module is configured to perform preprocessing to a reference signal with respective preprocessing base matrix and transmit the preprocessed reference signal to the corresponding terminal, wherein the reference signal transmitted to different terminals use orthogonal resources; and

the second data transmitting module is configured to perform symbol mapping and spatial modulation respectively on a bit stream of each terminal, and performing preprocessing on symbols obtained after the spatial modulation with the corresponding extended preprocessing matrix, combine the preprocessed symbols of the terminals, and transmit the combined symbols after multicarrier modulation.

The present disclosure further provides a signal receiving method based on multicarrier spatial modulation, including:

a receiving apparatus receiving a first reference signal, estimating a basic equivalent channel based on the first reference signal;

the receiving apparatus extending estimation of the basic equivalent channel using a manner consistent with that used by a transmitting apparatus for extending a preprocessing base matrix, to obtain an estimation of an extended equivalent channel; and

the receiving apparatus receiving data, and demodulating the received data according to the estimation of the extended equivalent channel to obtain original data.

In one embodiment, the method further includes:

the receiving apparatus receiving a second reference signal, and correcting the estimation of the extended equivalent channel according to the second reference signal.

The present disclosure further provides a receiving apparatus, including a receiving module, a basic equivalent channel estimation module, an extended equivalent channel estimation module and a demodulating module; wherein

the receiving module is configured to receive a first reference signal and data;

the basic equivalent channel estimation module is configured to estimate a basic equivalent channel based on the first reference signal;

the extended equivalent channel estimation module is configured to extend the basic equivalent channel using a method consistent with that used by a transmitting apparatus for extending a preprocessing base matrix, to obtain an estimation of an extended equivalent channel; and

the demodulating module is configured to demodulate the data according to the estimation of the extended equivalent channel to obtain original data.

In one embodiment, the receiving module is further configured to receive a second reference signal; and

the extended equivalent channel estimation module is further configured to correct the estimation of the extended equivalent channel according to the second reference signal.

The present invention provides a method and device for using a multiple of antennas to provide layered services for users receiving broadcast services. By employing the present invention, users in better channel conditions can receive more data or receive more reliable data, and users in poorer channel conditions can also get basic services, thereby avoiding the problem in conventional broadcast services that the quality of service is determined by users in poorest channel condition, and thus providing differentiated services for users in different channel conditions.

Meanwhile, through performing the spatial modulation over the equivalent channel consisting of the preprocessing, multicarrier modulation, actual physical channel and the multicarrier demodulation, link reliability can be effectively increased, and the ability of the multicarrier spatial modulation system against the fading or correlated channels is enhanced.

Fig. 1 is a block diagram of existing multi-carrier spatial modulation system;

Fig. 2 is a schematic view of an existing MBSFN system;

Fig. 3 is a schematic view of one possible way of link grouping in a first embodiment of the invention;

Fig. 4 is a schematic view of bit grouping in the first embodiment of the invention;

Fig. 5 is a schematic view of comparison of bit error rates performance of different groups when on the receiving side are equipped four receiving links in the first embodiment of the invention;

Fig. 6 is a schematic view of comparison of bit error rates performance of different groups when on the receiving side are equipped with two links in the first embodiment of the invention;

Fig. 7 is a schematic view of comparison of bit error rates performance of different groups when on the receiving side are equipped with two links and there are high correlation between the links in the first embodiment of the invention;

Fig. 8 is a schematic view of a way of data layering in the first embodiment of the invention;

Fig. 9 is a schematic view of power allocation among links in a second embodiment of the invention;

Fig. 10 is a schematic view of operational flow of multi-carrier spatial modulation technology supporting layered transmission employed in a third embodiment of the invention;

Fig. 11 is a schematic view of a way of transmitting link-number information and link grouping configuration information in the third embodiment of the invention;

Fig. 12 is a schematic view of carrying link-number information in the way of CRC masks in the third embodiment of the invention;

Fig. 13 is an exemplary diagram of grouped transmission of RS in a fourth embodiment of the invention;

Fig. 14 is a schematic view of resources allocation of grouped transmission of RS in the fourth embodiment of the invention;

Fig. 15 is a schematic view of grouping users in a fifth embodiment of the invention;

Fig. 16 is a schematic view of the process of grouping users in the fifth embodiment of the invention;

Fig. 17 is a schematic view of multi-carrier spatial modulation technology process based on layered transmission in the fifth embodiment of the invention;

Fig. 18 is a schematic view of the composition structure of one preferred transmitter of the invention;

Fig. 19 is a schematic view of the composition structure of one preferred receiver of the invention.

Fig. 20 is a schematic diagram illustrating preprocessing-based multicarrier spatial modulation system according to a first embodiment of the present disclosure.

Fig. 21 is a flowchart illustrating a signal processing procedure in TDD mode according to the first embodiment of the present disclosure.

Fig. 22 is a diagram illustrating comparison of bit error rate performance of a conventional solution and the proposed preprocessing-based solution with 6bps/Hz spectrum efficiency according to a second embodiment of the present disclosure.

Fig. 23 is a diagram illustrating comparison of bit error rate performance of the conventional solution and the proposed preprocessing-based solution with 4bps/Hz spectrum efficiency according to the second embodiment of the present disclosure.

Fig. 24 is schematic diagram illustrating a multi-user MIMO system based on preprocessed spatial modulation according to a third embodiment of the present disclosure.

Fig. 25 is a flowchart illustrating a signal processing procedure based on fixed preprocessing base matrix according to a fourth embodiment of the present disclosure.

Fig. 26 is a schematic diagram illustrating comparison of bit error rate performance of different solutions with 6bps/Hz spectrum efficiency according to the fourth embodiment of the present disclosure.

Fig. 27 is a schematic diagram illustrating comparison of bit error rate performance of different solutions with 4bps/Hz spectrum efficiency according to the fourth embodiment of the present disclosure.

Fig. 28 is a schematic diagram illustrating generation of the preprocessing matrix with adaptive parameter selection according to a fifth embodiment of the present disclosure.

Fig. 29 is a flowchart illustrating the insertion of reference signals and the channel estimation procedure according to the fifth embodiment of the present disclosure.

Fig. 30 is a schematic diagram illustrating comparison of a constellation with preprocessing and a constellation without preprocessing at the receiving end according to a sixth embodiment of the present disclosure.

Fig. 31 is a schematic diagram illustrating comparison of bit error rate performance of the conventional solution and the proposed solution in the case that the transmitting end has 4 antennas according to the sixth embodiment of the present disclosure.

Fig. 32 is a schematic diagram illustrating comparison of a constellation with preprocessing and a constellation without preprocessing at the receiving end according to the sixth embodiment of the present disclosure.

Fig. 33 is a schematic diagram illustrating comparison of bit error rate performance of the conventional solution and the proposed preprocessing solution in the case that the transmitting end has 16 antennas according to the sixth embodiment of the present disclosure.

Fig. 34 is a schematic diagram illustrating a structure of a transmitting apparatus according to an embodiment of the present disclosure.

Fig. 35 is a schematic diagram illustrating another structure of the transmitting apparatus according to an embodiment of the present disclosure.

Fig. 36 is a schematic diagram illustrating a structure of a receiving apparatus according to an embodiment of the present disclosure.

For the purpose of making the objectives, technical solutions and advantages of the present application more clear, the reference will be made in the following to the accompanying figures and will exemplify embodiments, to further detail the description of the present application.

Spatial modulation technology utilizes antenna index that transmits data as an additional carrier for the information. Compared with a single-antenna system, it can achieve higher spectral efficiency with the same bandwidth. But compared with conventional multi-antenna systems, spatial modulation technique has the following advantages: 1. because only one of a multiple of antennas is used in every data transmission, on the receiving side the inter-antenna synchronization is no longer needed; 2. the utilization of only one antenna cannot cause inter-link interference, and therefore at the receiving side there is no need for equalization algorithm with higher complexity to eliminate inter-link interference; 3. the need of only a few RF channels can significantly reduce the high energy consumption issue caused by the larger number of RF channels, that is, the spatial modulation is a system with higher energy efficiency; 4. spatial modulation system can still work when the number of antennas at transmitting side is greater than the number of receiving antennas. In addition, the same spectral efficiency can be implemented by a combination of different number of antennas and the modulation methods, and therefore the spatial modulation makes system parameters to be more flexible. A spatial modulation system, combined with multi-carrier technologies such as Orthogonal Frequency Division Multiplexing (OFDM), etc., performs spatial modulation for frequency domain equivalent multi-antenna channels including multi-carrier modulation, the actual physical channel, multi-carrier demodulation. Although it losses the advantage of having fewer number of RF channels, it gets greater freedom on issues such as resources allocation, pilot frequency allocation, among the others, while it also have a better compatibility with the standard.

A block diagram of a multi-carrier spatial modulation technology is shown in the dashed box on the left side of Fig. 1, where the number of antennas at the transmitting side is set to N, the modulation order used is Q=2^B, wherein B is the number of bits which is mapped to a symbol. The basic process thereof is as follows: in the transmitted data flow a number of log₂(NQ)=log₂(N)+B bits is being as one group, the first log₂(N) bits determines the data flow index used by data transmission, the following B bits are mapped to one QAM symbol. Taking N = 2, B = 2 as an example, the mapping relationship from spatial modulation bits to symbols is shown in Table 1 where antenna index represents current antenna index for transmitted data. In the sequence of transmitted bits, the first bit is used to determine antenna index, the next two bits are used to determine the symbol to be transmitted. After spatial modulated symbol is obtained, the Inverse Fast Fourier Transform (IFFT) is performed for all N data flows to get the data flow transmitted on N transmit antennas.

Table 1

Bit Sequence	Antenna Index	Symbol
0 0 0	0
0 0 1	0
0 1 0	0
0 1 1	0
1 0 0	1
1 0 1	1
1 1 0	1
1 1 1	1

Table 1: bit-symbol mapping relationship

The block diagram of the receiving side of spatial modulation technology employing OFDM technology is shown in Fig. 1 as dashed box on the right side, and M antennas are equipped at the receiving side. Upon receiving the received signal, at the receiving side Fast Fourier Transform (FFT) can be performed for the data flows of each receiving antenna to obtain frequency domain signals. Assume frequency domain equivalent channel matrix, which includes the transmitting side IFFT, the actual physical channel, and the receiving side FFT, to be H∈C^MxN, and then respective channel model can be written as:

y = Hx + n

wherein, H is the frequency domain equivalent channel matrix represented by M-multiply-N dimensional complex matrix, M is the number of equivalent receiving links, N is the number of equivalent transmitting links, C^MxN is the receiving vector after going through FFT, x = e_is_j∈C^Nx1 is the transmitted spatial modulation symbol vector, n∈C^Mx1 is noise vector. Only the i^th element in vector e_i=[0,...,0,1,0,...,0]^T∈C^Nx1 is 1, others are 0, which represents that, according to the transmitting bits, only the i^th antenna is used for data transmission, []^T represents the transposition of vector. Symbol s_j is the symbol selected from a symbol set of the constellation mapping, e.g., Quadrature Amplitude Modulation (QAM), Pulse Amplitude Modulation (PAM) or Phase Shift Keying (PSK), according to transmitting bits. Accordingly, the receiving symbol can be abbreviated as:

y = h_is_j + n

wherein, h_i∈C^Mx1 is the i^th column of matrix H.

At the receiving side maximum likelihood detection algorithm below is employed to detect transmitting symbols:

After obtaining the estimation of transmit antenna index

and the estimation of receiving symbol

, the estimated value of transmitting bit flow can be obtained according to the bit to symbol mapping criterion.

In addition to the spatial modulation system described above where there is only one data transmission link at a time, Generalized Spatial Modulation (GSM) system activates a subset of all links in each transmission, and uses indexes of the subset as a carrier to transmit information, while different links can transmit the same data to improve reliability of the system; or transmit different data to improve the data rate of the system. It is regarded as one form of spatial modulation in the present disclosure.

The prior art publishment [Bit Error Probability of SM-MIMO Over Generalized Fading Channels], as well as simulation results show that, comparing with conventional open-loop MIMO systems (for example, Space Frequency Block Coding (SFBC) or V-BLAST system), multi-carrier spatial modulation system can better explore the receive diversity provided by receiving antennas, thus can achieve significantly better performance than conventional open-loop system for users equipped with multiple receiving antennas. While the nature of the spatial modulation system requiring no channel feedback makes the technology particularly suitable for a broadcast channel, for example, the Physical Multicast Channel (PMCH) providing Multi-media Broadcast / Multicast Service (MBMS).

In the existing LTE-A, MBMS service is provided in the form of Multimedia Broadcast Single Frequency Network (MBSFN), as shown in Fig. 2. In the figure, a plurality of base stations transmit the same broadcast information in the same frequency at the same time, and users use signals from different base stations as multi-path components, which can obtain a higher Signal-interference plus noise ratio (SINR) than a single-cell system, thus being very suitable for the users in a move as well as users at the edge of a cell.

The difficulty of using the channel state information of the transmitting side in broadcast channels, as well as the feature of the diversity of users served at the same time make conventional MIMO technology difficult to be applied, so the physical layer multicast channel (PMCH) in existing standard uses only single antenna to transmit. In this case, the multi-carrier spatial modulation technique, which does not need channel state information feedback, not only can take advantage of multi-antenna on the base station side, but also can provide higher data rate than single antenna transmission. By combining MBSFN, it's possible to obtain higher reliability than single-cell multi-carrier spatial modulation. Therefore, there is a huge potential to apply the spatial modulation technology to PMCH.

In current MBMS transmissions, the transmission mode can only be designed for the worst channel, so it is also difficult for users in good channel conditions to obtain better data rate, thereby limiting the available overall system performance. In the present application, services with different qualities will be provided to users in different channel conditions by combining the characteristics of multi-carrier spatial modulation technology, thereby improving the user experience, and enhancing the overall system performance of broadcast channels. The basic idea of the present application is to use the correlation between links to layer the links, so that the data transmitted in different layers can get different protection. When a receiver is detecting data, it will choose the detected data layer according to its own channel condition. So users in poorer channel conditions can still get basic data, while users in good channel conditions will be able to detect more data layers, thereby obtaining higher data rate.

The First Embodiment:

In this embodiment, we introduce the multi-carrier spatial modulation system providing layered transmission in combination with specific system parameters settings. Suppose that the base station is equipped with 16 transmit antennas, that is, a maximum of 16 links can be activated at the same time. Available time-frequency resources use Physical Resource Blocks (PRB) specified in LTE as a unit, and one PRB consists of 12 subcarriers on 14 adjacent OFDM symbols. The number of system subcarriers is 256, and the number of available subcarriers is 120, i.e., the consecutive 10 subcarriers on the frequency domain are considered. To verify the possibility of using the link correlation to perform layered transmission, Space Shift Keying (SSK) modulation is used in this embodiment, i.e. one link is activated for every transmission, but each activated link does not transmit QAM signals, and instead, it transmits the signals known to both the transmitting and receiving sides. Channel model is as follows:

wherein, H∈C is a frequency domain equivalent channel coefficient matrix,

is flat fading MIMO matrix, that is, its elements follow independent complex Gaussian distribution whose mean value is zero and variance is 1.

is the transmitting side spatial correlation matrix, which is used to measure the correlation between links (inter-link correlation) at the transmitting side. The element in matrix R_T can be expressed as:

The element represents the correlation between the m^th link and the n^th link, d_m,n is the distance between the m^th link and n^th link, d_min represents the minimum distance between links, ρ represents the correlation coefficient, ()^* represents conjugate.

Layered data transmission service is provided in the form of layering and grouping among links. A preferred link grouping basis is the correlation between links, as shown in Fig. 3. In Fig. 3, all links are divided into N groups according to the correlation between links, labeled as Group 1, Group 2,...... Group N, respectively. Here, assuming that the spatial modulation system only activates one link. After grouping, use b₁ ~ b_n to indicate activated links, By "inter-group" it means in which group the activated link indicated by the bit is; and by "intra-group" it means in which specific location within the group the activated link indicated by the bit is. In this form of grouping, links with stronger correlation (i.e., correlation indexes bigger than set threshold) are placed into one group, and links belonging to different groups have relatively low correlation. Meanwhile, the upper bits in the transmission bits group are used for indicating in which group the activated link is, while the lower bits are used for indicating the activated links within the group (i.e., which link within the group is activated.) It should be noted that the way of grouping can be nested, that is, intra-groups can continue to perform grouping according to the correlation, thereby achieving the objective of the multi-layered data transmission.

In this embodiment, SSK modulation with 16 available links can transmit 4-bit information in each communication, and all the links are grouped into three layers. First, for the first layer of groups, the first 8 links are grouped as one group, and the latter 8 links are grouped into one group, with the highest bit indicating in which group the link is activated; next, each link group is divided into two groups according to the correlation, with each group containing 4 links with higher correlation, as the second layer of groups, and the second uppermost bit is used for indication; lastly, the remaining last two lowest bits are used to indicate which link out of the 4 links within the group is activated, as the third layer of groups. Fig. 4 shows the schematic view of bit grouping in this embodiment. As shown in Fig. 4, in the 4-bit information, b₁ is the bit for indicating the first layer of groups, b₂ is the bit for indicating the second layer of groups, b₃ and b₄ are the bits for indicating the third layer of groups.

First, consider the case in which at the receiving side four links are equipped, and the channel correlation coefficient ρ=0.1. Fig. 5 shows the bit error rate that can be obtained by different groups in such a case. In which, the legend 'first layer' represents the first layer of groups, i.e. the bit error rate of the highest bit; the 'second layer' represents the second layer of groups, i.e. the bit error rate of the second highest bit; the 'third layer' represents the third layer of groups, i.e. the bit error rate of the lowest two bits; the 'average' represents the average bit error rate. As it can be seen that, in this case, the first layer of groups has the best bit error performance, while the third layer of groups has the worst performance. Under the same bit error rate, the performance of the first layer of groups is about 2dB better than that of the second layer of groups, and about 4dB better than that of the third layer of groups. Therefore, for users in better channel condition and higher signal-to-noise ratio at the receiving side, all of the three layers of data can be decoded; while for users with lower signal-to-noise ratio, only the first layer of groups of data which has the best bit error performance may be got.

Next, consider the case in which at the receiving side two links are equipped, and the channel correlation coefficient ρ=0.3. Fig. 6 shows the bit error rate that can be obtained by different groups in such a case. In which, the legend 'first layer' represents the first layer of groups, i.e. the bit error rate of the highest bit; the 'second layer' represents the second layer of groups, i.e. the bit error rate of the second highest bit; the 'third layer' represents the third layer of groups, i.e. the bit error rate of the lowest two bits; the 'average' represents the average bit error rate. Similar to the results of Fig. 5, in this case, different groups can still get significant performance difference, so users can select the appropriate data rate according to their own channel conditions.

Lastly, consider the case in which at the receiving side two links are equipped, and the channel correlation coefficient ρ=0.5. Fig. 7 shows the bit error rate that can be obtained by different groups in such a case that links have high correlation. In which, the legend 'first layer' represents the first layer of groups, i.e. the bit error rate of the highest bit; the 'second layer' represents the second layer of groups, i.e. the bit error rate of the second highest bit; the 'third layer' represents the third layer of groups, i.e. the bit error rate of the lowest bit; the 'average' represents the total bit error rate. In this case, the performance gap between different layers is even more obvious. For example, when the bit error rate is 10^-3, the performance of the first layer of data is about 5dB better than that of the second layer of data, and about 8dB better than that of the third layer of data .

The simulation results from Fig. 5 to Fig. 7 show that, the way in which layered data are transmitted using the correlation between links is more effective when at the receiving side a multiple of antennas are equipped or when there are certain correlations between links; and it can provide differentiated services for users with different signal-to-noise ratio while ensuring users can get basic services.

These above results illustrate that the link grouping way provided by the embodiment can provide different bit error rate performance among different groups, thus facilitating the system to transmit different data on different groups. One possible way is to transmit the most basic information on the bits of the first layer of groups, with the bits of each subsequent layer of groups carrying extension information on the basis of this layer of data. For example: extension information may be additional services data on the basic services, and may also be the data to improve time-frequency definition or voice clarity. Thus, every time a layer of data is decoded, data rate can get improved based on the data of previous layer. Another possible way is to transmit the most basic information on the bits of the first layer of groups, with the bits of each subsequent layer of groups transmitting redundancy information (such as the parity bit for channel encoding, or the repetition of the information of the first layer of groups). Thus, every time a layer of data is decoded, reliability can be improved based on the data of previous layers, thereby improving the robustness of the system. To obtain the improvement of both data rate and reliability, above two ways can be combined.

To facilitate the receiving side to detect the data in each layer, the data in each layer can be divided into blocks, and CRC check code independent of each other can be added. Although this may slightly reduce data rate, it can facilitate users to perform layered data detection. Fig. 8 shows the schematic view of this way of data layering. In the figure, the first layer of data is basic data, other layers of data are the extensions or redundant based on the first layer of data. The example shown in the figure divides each layer of data into data block 1 and data block 2, and adds the CRC check codes independent of each other to the data block 1 and data block 2, respectively.

In channels of this embodiment, links are grouped according to the correlation between links. Because in the channel model used, the closer links have higher correlation, so in this embodiment, grouping can be performed directly according to the order of the links. Since a majority of systems employ dual-polarized antennas where different polarized antenna groups can be considered to be independent of each other, the first layer of groups can be determined by using polarization directions between different antennas. Considering that adjacent antennas tend to have higher correlation, so the grouping according to the distance between the antennas with the same polarization direction is also reliable. In addition, channel state information from user feedback can also be used to determine between which links the correlation is higher, and the grouping of links can be performed according to the information.

It should be noted that, although the simulation presented in this embodiment did not consider the case of transmission of the constellation point symbols, such as QAM symbol or PSK symbol, etc., in actual system, part of information can also be carried on the constellation point symbols for transmission. Considering that most detection algorithms with low complexity used in practice need to first detect the links used, and then perform subsequent constellation point symbol detection after determining the activated links at the transmitting side. Therefore, if link detection error occurs or link detection has higher uncertainty, it will cause severe negative impact on the detection of constellation point symbols. In such case, the constellation point symbols can be treated as the data with the priority or importance being one layer lower for transmission. Another way to transmit constellation point symbols is to use constellation point symbols to transmit separate data flow, and decide whether or not to keep the data flow by CRC detection. In some special circumstances, such as in the case there are links with stronger correlation such as stronger direct mapping path, although link detection may not be accurate, it can still ensure the accuracy of constellation point symbols. In such case, using constellation point symbols to transmit separate data flow can instead improve throughput. At this point, the data flow transmitted with the constellation point symbols should be some auxiliary data on the basic data, for example, the duplicates or redundancies of some layers of data, or some new auxiliary data information.

The Second Embodiment:

This embodiment will present the multi-carrier spatial modulation technology supporting layered transmission pre-processed at the transmitting side. In some actual systems, due to facts of lack of feedback or that the feedback is not ideal or the like, the link grouping configuration of base station may not ensure all users' requirements are met. At this point, the differences between different groups can be increased on the base station side by pre-processing different links, thereby increasing the probability of correct detection.

The pre-processing in this embodiment includes, but not limited to, power allocation and phase rotation. Both pre-processing methods will be described below respectively.

1. Power allocation.

In the premise of ensuring average transmission power unchanged, the average transmission power of each of the groups in the first layer is adjusted, so that different groups have different average transmission power; In the premise of ensuring average transmission power of each of the groups in the first lay unchanged, the average transmission power of each of the groups in the second layer is adjusted, so that different groups in the second layer have different average transmit power; the above procedure is recursively performed according to the steps described above and eventually the power allocation results for each of the groups in each layer is obtained. To ensure the detection of previous layer would not be affected by the power adjustment of the following layer, the amount of power adjustment of previous layer need to be specified to be strictly higher than the amount of the power adjustment of the following layer. An example of power allocation between links is shown in Fig. 9.

Fig. 9 shows a grouping configuration in which the number of available links for base station is 4 and two layers are used for transmission. Each group in the first layer contains two links; each group in the second layer contains one link. Assuming the average transmit power is 1, in the premise of ensuring the average transmission power unchanged, the average power of the two groups in the first layer is adjusted. For example, as shown in Fig. 9, the average power of group 1 in the first layer is adjusted to 1+p, and the average power of group 2 in the first layer is adjusted to 1-p. In the premise of ensuring the average power of each of the groups in the first layer unchanged, the power of each of the groups in the second layer is adjusted. For example, the average power of each of the groups in the second layer is adjusted to: 1+p+p₁, 1+p-p₁, 1-p+p₁, 1-p-p₁. To ensure the detection of groups in the first layer would not be affected by the power allocation of the second layer, it needs to ensure that p>p₁.

2. Phase rotation.

Except power adjustment among different links, the differential between different groups can be increased through phase rotation. One possible criterion for the phase rotation is to select randomly rotation phase for the links of each group in the lowest layer, and the randomly selected phase interval for each group does not intersect, with the adjacent phase intervals being selected for links belonging to the same group in previous layer. Still use the system shown in Fig. 9 as an example, in which the number of links is 4 and the number of layers is 2, because of the number of groups in the lowest layer being 4, so four phase intervals are selected as phase rotation interval. Considering that

groups

1, 2 in the second layer belong to the same group of the first layer (namely: group 1 in the first layer), and

group

3, 4 in the second layer belong to another group of the first layer (namely: group 2 in the first layer), therefore adjacent rotation phase intervals are selected for

group

1, 2 in the second layer, and another adjacent rotation phase intervals are selected for

group

3, 4 in the second layer. A simple example is: the rotation phase intervals for four groups in the second layer are:

[0,π/8],[π/8,π/4],[π/2,5π/8],[5π/8,3π/4]

Also noted that, the two methods described above can be combined, i.e., performing power adjustment and phase rotation at the same time, to further increase the distance between different groups.

When transmitting reference signal used for group channel estimation (the reference signal can be used for demodulation of each group), the reference signal passes through the same pre-processing, and therefore the reference signal can be directly used in the estimation of pre-processed equivalent channel coefficient. Furthermore, for the actual system based on physical resource block scheduling, each of the time-frequency resources from the same physical resource block uses the same way of pre-processing.

The Third Embodiment:

This embodiment will illustrate the operational flow of the multi-carrier spatial modulation technology which employs the layered transmission supported by the present solution in an actual system.

Fig. 10 shows a schematic view of the operational flow of the multi-carrier spatial modulation technology supporting layered transmission employed by this embodiment. On the base station side, the user equipment (UE) gets first notified of the link-number information and the link grouping configuration information used in data transmission; and the data to be transmitted is layered according to the information about the number of selected links and the link grouping configuration information; then the reference signal corresponding to the selected links is transmitted, and the data to be transmitted is transmitted to the UE after being performed multi-carrier spatial modulation. Wherein, the link-number information can be pre-set, or contained in the link grouping configuration information, and therefore, the link-number information is optional information to be transmitted. In addition, a pattern can be set for the link grouping, and the base station can enable UE to acquire the grouping of the links as well as the information about the links contained in each of the groups by specifying a specific link grouping pattern to the UE.

On UE side, the link-number information and the link grouping configuration information are acquired at first. Then link channel state information is estimated by the reference signal of each link or group according to the information. And at last detection is performed to the data flow to get the estimation of transmitted data.

The link-number information indicates the number of links used for transmitting spatial modulated signal. Since base stations often tend to be equipped with more antennas, they can support more links. But in terms of different channel conditions and users served, they need to select appropriate number of links according to specific situations. The link grouping configuration information refers to the grouping of links after the number of the links is selected. For one kind of link number, only one or two link grouping configuration needs to be specified. For example, when the number of links used by base station is 8, one possible link configuration is to place every four links into one group as the first layer, then every two links are allocated into one group as the second layer; or every two links are allocated into one group as the first layer. Specific link grouping configurations can also be determined by channel conditions and users' configurations. In combination with the link-number information and link grouping configuration information, the specific grouping configuration used by base stations can be determined.

The following is the detailed description of above processes.

When base station informs the link-number information and the link grouping configuration information to UEs, the information can be transmitted in the Physical Broadcast Channel (PBCH) or the Physical Downlink Control Channel (PDCCH). During the transmission in PBCH, the following two forms can be selected:

1. Add new fields in PBCH for transmitting the link-number information and link grouping configuration information.

As shown in Fig. 11, two fields, the link-number information indication field and the link grouping configuration information indication fields, respectively, are added to the reserved bits in PBCH (as shown in additional fields in Fig. 11).

Because the specified numbers of antenna ports are 1, 2 or 4 in PBCH, user performs detection in the forms of blind detection and the detection of CRC masks, so only the cases that the number of antenna ports is larger than 4 needs to be notified. For example, in case of base station being equipped with 128 antennas, the number of links can be used by multi-carrier spatial modulation are 2, 4, 8, 16, 32, 64 and 128 (i.e., powers of 2). When informing the number of links used, only cases that the number of links is greater than 4 are notified. One possible notification method is shown in table 2.

Table 2

Indication bits	000	001	010	011	100	101	110	111
The number of ports	1, 2, 4	8	16	32	64	128	reserved

Table 2: One possible way to indicate the link-number information when the number of links is 128

In Table 2, three bits are used to notify the number of links to UEs, in which the last two cases are reserved, showing that in this way more links can be supported. In addition, considering that the same kind link number only needs to support one or two grouping configuration to meet the requirement of layered transmission, and therefore the newly added two fields need to occupy 4 bits only. Considering that the reserved bit number is 10 in PBCH, so the overhead of 4 bits is acceptable.

2. Transmit the link number information by CRC mask.

The way to inform the user of the number of antenna ports in conventional PBCH channel is transmission mode blind detection plus CRC masks, that is, adding mask corresponding to respective number of antenna ports to the CRC check code. By adding available CRC mask, the link-number information can be informed the user without additional fields.

Fig. 12 shows a preferred way of carrying the link-number information using CRC masks. Since the transmission modes employed by PBCH include single-antenna port mode, dual-antenna port antenna diversity mode, and four-antenna port antenna diversity mode. To ensure the reliability of the PBCH transmission of information, available CRC masks can be divided into three groups, corresponding to a single-antenna port, a dual-antenna port and a four-antenna port, respectively. In the example shown in Fig. 12, CRC masks 1, 2, 3 all correspond to single-antenna port. Therefore, by decoding one of the masks, user can determine the transmission mode used by PBCH is single-antenna port mode. Each CRC mask in turn represents the link-number information used by actual broadcast channel. For example, if the number of links used by broadcast channel is configured to be 16, and PBCH transmission uses single-antenna port mode, then CRC mask 3 is selected to process CRC check bits. After user get to know by CRC check that mask 3 is used, user can get to know that the PBCH transmission mode is single-antenna port mode, and that the number of links used by the broadcast channel is 16. In using this method, user gets notified of the link grouping configuration information by adding extra fields in reserved bits.

In addition, these two ways described above can be combined, i.e. using CRC mask to notify the number of ports while adding extra fields in the reserved bits in PBCH, thus improving the reliability of information.

The link-number information and link grouping configuration information described above may also be transmitted in the downlink control channel, that is, to add extra fields in the control channel to indicate the link-number information and link grouping configuration information. One possible way to indicate the link-number information is shown in Table 2, in which bits 000 represent the link configuration used is the same as the configuration in PBCH.

In addition to these two ways, the link-number information and link grouping configuration information can also be transmitted in the Physical Downlink Shared Channel (PDSCH).

The data is layered by the base station according to one or more of the following criteria:

1. Layering in accordance with the priority of the data, that is, the data with the highest priority is allocated with bit layer with the highest reliability; the data with the second highest priority is allocated with bit layer with the second highest reliability; and by this analogy, the data with the lowest priority is allocated with the bit layer with the lowest reliability. Here, the priority can be the priority of application data, that is, the data with highest priority need more efficient and more reliable decoding, while the data with low priority may be relaxed in requirement for reliability. The priority can also be the priority of multimedia data, that is, the data with high priority is basic data, and by decoding the data with high priority, basic multimedia services can be obtained, while by further detection of low-priority data, the quality of service can be improved on the basis of basic services.

2. Alternatively, the bit layer with the highest reliability transmits basic information bits. After performing channel encoding on the basic information bits, redundant information bits are transmitted in the bit layer with the second highest reliability, and the redundancy bits resulting from further encoding are transmitted in the bit layer with lower reliability. Thus, once a layer of data is detected, the reliability of the received signal can be improved. Further, above two types of layering ways can be combined to increase the data rate and reliability at the same time.

For data detection, user can employ following two ways:

1. Joint detection. That is, user performs joint detection for each layer of data and gets estimated value of transmitted data of each layer. Then received signal-to-noise ratio is estimated for each layer of data, and layered data flow above a certain threshold is selected for further processing (such as channel decoding and source decoding, etc.); if the layered data is processed by adding CRC block by block, then CRC check can be done for each layer of data, and each of the layers which passes the check is remained.

2. Detection layer by layer. That is, the information transmitted on each layer of data is detected layer-by-layer according to the channel state information of each layer, until the received signal-to-noise ratio of a certain layer cannot reach a certain threshold, or until the CRC check of a certain layer does not pass.

The Fourth Embodiment:

In this embodiment, the reference signal configuration method employing the solutions provided by the present application will be presented.

Reference signals may be processed according to insertion method used in conventional communication systems, that is, the reference signals used for estimation of different link channels use resources orthogonal to each other for transmission, that is, transmission occurs in frequency domains orthogonal to each other, time resources, or in the same time-frequency resource but use mutually orthogonal codes to distinguish between different links. This method can estimate the channel state information for each link. Data detection can be done in a joint manner from each of the groups, and data from groups where reliability has reached above a certain threshold is selected for further processing. The channel state information of each of the groups can also be obtained by way of combination, then each layer of data can be detected by way of detection layer by layer, until the signal of a certain layer reaches the threshold of signal-to-noise ratio.

In this embodiment, a way of group transmitting reference signals will be presented. Its basic idea is to transmit reference signals in groups, so that each layer of data can be detected directly from the channel state information of groups, thereby simplifying the design of the receiver. Fig. 13 shows a simple example of a group transmitting reference signals where the number of links at the transmitting side is 8 and the number of layers is 3. In Fig. 13, the first layer of groups comprises two groups, with each group containing four links. To distinguish between the two groups in the first layer, two orthogonal reference signals with the length of 2 is needed, as shown in the figure as RS1 and RS2. When transmitting reference signals of this layer, in premise of ensuring power constraints, four links belonging to the same group transmit the same reference signal data, and four links belonging to another group transmit the reference signal data orthogonal to that signal. Each group in the second layer of groups contains two links; also only two reference signals orthogonal to each other with the length of 2 are needed to distinguish two different groups. Specifically, In Fig. 13, link 1 and link 2 transmit the same reference signal, i.e. RS3, while link 5 and link 6 transmit reference signal orthogonal to that signal, i.e. RS4, the remaining links are not activated. The channel state information of other two groups can be calculated in combination with the channel state information of the first layer groups. When transmitting the channel state information of the third layer of groups, four orthogonal reference signals with a length of 4 are used, as shown in the figure as RS5 to RS8, that is, only the channel state information of

links

1, 3, 5, 7 needs to be estimated while that of the remaining links can be obtained in combination with the channel state information of the second layer.

The way of group transmitting reference signals described above can simplify users' operations without consuming additional resources, so that users in poorer channel condition can decode the basic data more quickly.

Fig. 14 shows a schematic view of time-frequency resources allocation for group transmitting reference signals. For the example shown in Fig. 13, the way of a conventional reference signal transmission requires 8 orthogonal reference signals, thus requiring eight orthogonal time-frequency resources. From the foregoing description, layer 1 requires two orthogonal reference signals, thus requiring two orthogonal time-frequency resources; layer 2 requires two orthogonal reference signals, thus requiring two orthogonal time-frequency resources; while layer 3 requires four orthogonal reference signals, thus requiring four orthogonal time-frequency resources. Therefore, the time-frequency resources required by the present invention is the same as conventional way, but the present invention can support better layer-by-layer detections, and for users in poorer channel conditions, it is more advantageous.

The Fifth Embodiment:

In this embodiment, the solution to determine link grouping configuration and user grouping configuration according to channel state information from users' feedback is presented.

Although the Multimedia Broadcast / Multicast Service in the LTE-A does not support to adjust the process at the transmitting side according to users' feedback information, but for the solution proposed by present application, adjusting the number of used links and the link grouping configuration according to the channel state information from users' feedback can better provide services for users in different channel conditions. Meanwhile, the solution based on feedback can also be suitable for users where services are in open loop mode. Specifically, as shown in Fig. 15, according to the channel state information from users' feedback, base stations allocate users with the same or similar information of the number of links and the information of link grouping configuration into one group, and make broadcasting services on the same time-frequency resources.

The specific grouping process is shown as in Fig. 16. On the base station side downlink reference signal is transmitted for measuring the channel state information of downlink physical channel. The reference signal may be similar to the Cell-specific Reference Signal (CRS) or channel state information reference signal (CSI-RS) in the LTE / LTE-A. The reference signal plays different role as the reference signal described in the Second Embodiment. UEs estimate downlink channel based on the reference signal and feed back the estimated channel state information to the base station. The base station estimates the correlation between links according to the feedback from UEs, and determines the link grouping configuration of users, and allocates users with the same or similar link grouping configuration into one group, and performs broadcasting services on the same time-frequency resources for users who are in the same group.

In order to measure the correlation between links, the base station can also estimate the uplink channel state information according to the Sounding Reference Signal (SRS) transmitted from UE to the base station via the uplink channel, thereby estimating the correlation between the downlinks. For the Time-Division Duplex (TDD) system, using the reciprocity between the uplink and downlink channels, the correlation between the downlinks can be directly obtained. For Frequency-Division Duplex (FDD) system, because the correlation between links is affected and determined by the large-scale fading between channels, and therefore the correlation between downlinks can also be estimated by uplink channel estimation.

Users can feed back the channel state information through Rank Indication (RI) and Precoding Matrix Index (PMI) existing in the LTE. And the base station estimates the correlation between downlinks according to users' feedback. For the convenience of user feedback, link grouping configuration pattern codebook known to both base station and users can also be designed, and users feedback the link-number information through Rank Indication and feedback the needed link grouping configuration through link grouping configuration pattern.

Through the estimation of correlation between user links, base station can adjust user groups dynamically, and notify users the time-frequency resources location needed by its broadcasting data in the downlink control channel or downlink shared channel. Users read the information in the downlink control channel or in the downlink shared channel, and acquire the broadcast data resource allocation information as well as the information about the number of used links and the link grouping configuration information. Based on those information, users acquire broadcast data from respective sources.

Multi-carrier spatial modulation system signal process flow, which includes user grouping, pre-processing, and based on group transmission, is shown in Fig. 17. The user grouping and link configuration selections based on feedback/uplink transmission is an optional part. The structure shown in Fig. 17 is suitable for providing multimedia broadcast / multicast services broadcast channels, as well as suitable for control channel transmission. When applying this structure to the control channel, the basic data comprises some control information necessary for system, and extension data can be some extended control data for increasing transmission data rate of control channel, or can be the redundant or copy of basic data for increasing the reliability of control channel; it may also be used for receivers working in open-loop mode, and a receiver, in this kind of mode, cannot feedback the channel state information efficiently. With the solution provided by the present application, the receiver can spontaneously adjust the rate of receiving data according to changes in the channel conditions, providing greater flexibility and reliability.

Corresponding to the methods described above, the present application provides a transmitter, and its composition structure is shown as in Fig. 18. The transmitter comprises:

a configuration module, for transmitting link grouping configuration information, wherein, the link grouping configuration information is, after dividing links into at least two groups, the information of the links contained in each of the groups;

a data layering module, for layering the data flow to be transmitted according to the groups of the links;

a transmitting module, for transmitting the multi-carrier modulated signals.

Corresponding the methods described above, the present application also provides a receiver, and its composition structure is shown as in Fig. 19. The receiver comprises:

a group acknowledgement module, for acquiring the grouping of the links and the information of the links contained in each of the groups according to said link grouping configuration information; and

The Sixth Embodiment:

In this embodiment, a downlink physical channel training solution applicable for multicarrier spatial modulation is described with reference to example system parameter configurations. In this embodiment, the base station is equipped with N antennas, and the terminal is equipped with M antennas. The system operates in a Time-Division Duplex (TDD) mode. Therefore, the state of the uplink channel may be utilized for the downlink channel according to channel reciprocity.

FIG. 20 is a schematic diagram illustrating a preprocessing-based multicarrier spatial modulation system according to the first embodiment of the present disclosure. It can be seen from FIG. 20 that, compared with conventional multicarrier spatial modulation system, the preprocessing-based spatial modulation system provided by this embodiment adds a preprocessing module between the spatial modulation and the IFFT module. The basic idea is to perform spatial modulation operation to the equivalent channel consisting of preprocessing→IFFT→channel→FFT, so as to increase link reliability, reduce pilot overhead and support simultaneous serving multiple terminals. In this embodiment, the signal processing procedure in the TDD mode is as shown in FIG. 21 and is briefly described in the following.

Firstly, the terminal transmits an uplink Sounding Reference Signal (SRS) to the base station. The base station estimates system frequency-domain channel according to the received SRS, and obtains a channel coefficient matrix H∈C^MxN consisting of frequency-domain channel coefficients.

Then, the base station calculates a preprocessing base matrix W_b∈C^NxM according to the channel coefficient matrix. The preprocessing may be implemented through manners including but are not limited to: Matched-Filter (MF) precoding, i.e. W_b=H^H, Zero-Forcing (ZF) precoding, i.e.W_b=H^H(HH^H)^-1, or Minimum Mean Square Error (MMSE) precoding, etc.

Then, the base station extends the preprocessing base matrix to obtain an extended preprocessing matrix W∈C^NxN. The preprocessing base matrix may be extended via any one of the following three methods.

A first extending method: linear combination, i.e., performing a linear combination to the columns of the preprocessing base matrix to obtain the columns of the extended preprocessing matrix. For example, if

, where

denotes the mth column vector of the matrix W_b, then the nth column vector w_n of the matrix W may be denoted by:

, where

denotes linear combination coefficients for the vector W_b when generating w_n. The linear combination coefficients are selected to make the Euclidean distance between symbols received by the receiving end as large as possible (or make the Euclidean distance between equivalent channel vectors as large as possible). One simple condition is that: the linear combination coefficients are real numbers and there are no opposite numbers. This condition is merely one of the possible conditions. Any condition which can ensure the Euclidean distance between symbols as large as possible is applicable.

A second extending method: phase rotation, i.e., performing a phase rotation to the column vectors in the preprocessing base matrix to obtain the column vectors of the extended preprocessing matrix. In particular, the nth column of the extended preprocessing matrix may be denoted by:

; where the vector

denotes the mth column of the preprocessing base matrix, j is an imaginary unit,

denotes rotation angle. In addition, the phase rotation may be implemented via various manners, such as multiplying the elements of each column vector by different rotation factors, or multiplying the column vector by a NxN rotation matrix, etc.

A third extending method: power allocation, i.e., multiplying each column vector of the preprocessing base matrix by a power allocation factor to obtain the columns of the extended preprocessing matrix. In particular, the nth column of the extended preprocessing matrix may be denoted by:

where

denotes the power allocation factor.

It should be noted that, the above three methods may be used in combination. For example, a linear combination may be firstly performed to the columns of the preprocessing base matrix to obtain a NxN matrix, and then phase rotation and power allocation operations may be performed on this matrix to obtain the final extended preprocessing matrix.

Finally, when transmitting data to the terminal, the base station needs to perform downlink equivalent channel training. The equivalent channel experienced by the data transmitted by the base station is

, and the matrix W is generated following a particular rule. Therefore, if the terminal knows the rule, the terminal is able to generate a complete channel matrix according to the rule of the linear combination with less channel estimation. In particular, a basic equivalent channel is defined by:

whereas the equivalent channel

is denoted by:

It can be seen that, if the extending operation consistent with that for generating the preprocessing matrix is performed to the basic equivalent channel

, the estimation of the equivalent channel

can be obtained. This means, when estimating the downlink equivalent channel, it is only required to estimate the basic equivalent channel

, and estimation of the equivalent channel

is not required. Therefore, the overhead on the downlink channel estimation is effectively reduced.

In particular, when performing downlink training, the base station merely needs to estimate M downlink basic equivalent channels, perform preprocessing to the downlink reference signal with the preprocessing base matrix W_b and transmit the preprocessed downlink reference signal to the terminal. After finishing the downlink basic equivalent channel training, the base station uses the matrix W to perform the preprocessing to the downlink data.

During the downlink equivalent channel training, the signal received by the terminal may be denoted by:

Y_P = HW_bP+N;

where

denotes a reference signal matrix, M_P denotes the length of the reference signal. For example M_P=M, matrix P is a unit matrix, i.e. the reference signal is transmitted on orthogonal time-frequency resources. Since the terminal knows the reference signal matrix P, the terminal is able to obtain the estimation

of the basic equivalent channel

. Meanwhile, since the terminal already knows the extending rule for generating the extended preprocessing matrix from the preprocessing base matrix, the terminal is able to recover the estimation

of the extended equivalent channel matrix

using the same manner as the transmitting end when extending the preprocessing base matrix. When data is transmitted, the signals received by the terminal may be denoted by:

where x∈C^Nx1denotes the transmission signal after spatial modulation, y∈C^Mx1denotes signals received by the terminal. The terminal estimates the transmission signal according to the received signal y and the estimation

of the extended equivalent channel matrix, and outputs the estimated bit stream.

In this solution, the extended preprocessing matrix can be seen as being obtained through multiplying the preprocessing base matrix by an extending matrix, i.e., the finally obtained extended preprocessing matrix is calculated by:

W=W_bW_e

where W_e∈C^MxNdenotes the extending matrix and may be designed according to the above three extending methods described in this embodiment. During the channel estimation, the basic equivalent channel is firstly extended,

. The extended equivalent channel and the basic equivalent channel meet

. Therefore, if the receiving end knows the extending matrix W_e, it can recover the extended equivalent channel based on the estimation of the basic equivalent channel. At this time, the overhead of the downlink reference signal is merely relevant to the dimension of the basic equivalent channel. The impact of the downlink training to the system spectrum efficiency is greatly reduced.

Hereinafter, an example is provided to describe the parameter configuration. Suppose that the system is a multi-antenna system with QPSK modulation, N=16, M=2. If the conventional multicarrier spatial modulation is utilized, 6 bits can be transmitted each time. At the same time, the downlink training needs to estimate the overall 16 links, which brings heavy burden to the system spectrum efficiency. However, according to the solution of the present disclosure, it is merely required to estimate the two basic equivalent channels, which greatly reduce the overhead of the channel training. In this example, the linear combination and phase rotation extending methods are utilized to extend the preprocessing base matrix. The preprocessing base matrix generated by the transmitting end has a dimension of 16x2. Linear combination is performed to the columns of the matrix to obtain an extended intermediate matrix. The linear combination coefficients are as shown in Table 3.

Table 3

Index	Coefficients	Index	Coefficients	Index	Coefficients	Index	Coefficients
1	[0 1]	5	[1/2 3/2]	9	[1/3 5/3]	13	[1/4 5/4]
2	[1 0]	6	[1/2 -3/2]	10	[1/3 -5/3]	14	[1/4 -5/4]
3	[1 1]	7	[3/2 1/2]	11	[5/3 1/3]	15	[5/4 1/4]
4	[1 -1]	8	[3/2 -1/2]	12	[5/3 -1/3]	16	[5/4 -1/4]

Table 3: Linear combination coefficients

In order to obtain the final preprocessing matrix, phase rotation is performed to columns of the intermediate matrix. All elements of the same column vector use the same phase rotation factor. In this embodiment, two adjacent columns use the same phase rotation factor, e.g. a multiple of 11.25°.

Before data is transmitted, the reference signal matrix after being processed by the preprocessing base matrix is transmitted, and then data after spatial modulation and processing based on the extended preprocessing matrix is transmitted. The receiving end estimates the downlink basic equivalent channel according to the reference signal, and extends the columns of the basic equivalent channel matrix according to Table 3 and the phase rotation processing rule to obtain the extended equivalent channel. Finally, the terminal obtains estimated bit stream according to the extended equivalent channel matrix and the received signal.

It should be noted that, since the solution of the present disclosure establishes equivalent links between the transmitting end and the receiving end, multiple links may be activated at the same time based on the equivalent links to realize the generalized spatial modulation.

The Seventh Embodiment:

In this embodiment, the effectiveness of the solution of the present disclosure is described with reference to parameter configurations in a practical system and a simulated result. Suppose that the system uses 256 subcarriers, wherein the number of effective subcarriers used for transmitting data is 120. Consecutive 12 subcarriers of 14 OFDM symbols form a physical resource block (PRB). Suppose that the transmitting end knows the channel state information. According to the channel state information, the base station calculates a preprocessing base matrix according to a matched filter precoding algorithm, i.e.

W_b=H^H.

Thereafter, the base station extends the preprocessing base matrix according to the extending method described in embodiment 1, and performs preprocessing to the data. The EVA channel model is utilized. The moving speed of the terminal is 50km/h.

Firstly, the situation that the base station has 16 antennas and the terminal has 2 antennas is considered. The QPSK modulation scheme is adopted. In this situation, the spectrum efficiency is 6bps/Hz. The extending of the preprocessing base matrix is similar to embodiment 1, i.e., performing linear combination and phase rotation to the columns of the preprocessing base matrix. The linear combination coefficients are as shown in Table 3. The conventional multicarrier spatial modulation system is selected for comparison. The system structure of the conventional multicarrier spatial modulation system is shown in FIG. 1.

FIG. 22 is a schematic diagram illustrating comparison of the bit error rate performance of the convention solution and the preprocessing solution of the present disclosure. The horizontal axis denotes E_s/N₀, wherein E_Sdenotes the average energy of symbols transmitted at each time and is normalized to 1 in this embodiment. N₀denotes a noise spectrum density, used for evaluating noise energy. It can be seen that, with the preprocessing provided by the present disclosure, with the same data rate, the bit error rate performance of the multicarrier spatial modulation system is greatly enhanced. For example, around the bit error rate of 10^-3, using the preprocessing method provided by the present disclosure, the system performance is enhanced about 7dB compared to the conventional multicarrier spatial modulation system.

It can be seen from above that, the embodiment of the present disclosure firstly generates energy concentrated links through the preprocessing to optimize the signal-to-noise ratio at the receiving end. Based on these links, new virtual links are generated based on methods such as power allocation, phase rotation and linear combination, so as to provide higher spectrum efficiency using link indices. Therefore, the performance comparison result provided by this embodiment can be explained in the following two aspects: 1, since the channel state information known by the transmitting end is utilized, the basic preprocessing can concentrate the transmission energy, such that the signal-to-noise ratio of the receiving end on the basic link can be greatly increased; 2, through the preprocessing at the transmitting end, the generated new virtual links ensure that the Euclidean distance between symbols is relatively large, which further enhances the bit error rate performance of the system.

Then the situation that the base station has 4 transmit antennas and the terminal has 1 receiving antenna is considered. The QPSK modulation scheme is still utilized. At this time, the spectrum efficiency is 4bps/Hz. Since the receiving end has only one antenna, the equivalent channel after the conventional precoding is a single-input single-output channel. The linear combination preprocessing cannot be performed. Therefore, merely the phase rotation extending is performed to the preprocessing base matrix. In particular, the ith (1≤i≤4) column of the extended preprocessing matrix W is w_bexp{jx(i-1)θ}, wherein vector w_b∈C^4x1denotes the preprocessing base vector calculated according to the channel state information. The calculation may be performed based on the matched filter precoding algorithm.

is an imaginary unit, θ=π/8denotes rotation angle.

FIG. 23 shows comparison of the bit error rate performance of the conventional solution and the preprocessing solution of the present disclosure. It can be seen that, due to the reducing of the receiving antenna of the terminal, the bit error rate performance of the two solutions both degrade. But the solution of the present disclosure still has better performance. For example, around the bit error rate of 10^-2, the multicarrier spatial modulation system with the preprocessing has a performance advantage of over 5dB.

The Eighth Embodiment:

In this embodiment, support of the solution provided by the present disclosure to the multi-user MIMO system is described. In this embodiment, a multi-user MIMO system based on the preprocessing spatial modulation is as shown in FIG. 24.

In FIG. 24, the number of simultaneously served terminals is K. The base station is equipped with N antennas. The ith terminal is equipped with M_i antennas. The total number of receiving antennas is

. When performing preprocessing to the transmission data, the base station firstly calculates a frequency-domain precoding matrix according to the channel state information from the base station to all terminals, so as to obtain a precoding matrix for each terminal. Then, the base station extends the precoding matrix of each terminal according to the solution of embodiment 1 to obtain an extended preprocessing matrix and performs preprocessing to the data of each terminal. After the preprocessing, the base station combines the preprocessed data in the combination module, i.e., adds data to be transmitted on the same antenna. Then, the base station performs IFFT operation to the combined data before transmitting them via the antennas.

In particular, each of the M antennas of the K terminals is seen as a receiving end. The frequency-domain channel model between the base station and the receiving end may be denoted by:

y=Hx+n,

where H∈C^MxN denotes a frequency-domain equivalent channel matrix. The precoding processing is performed to this matrix to eliminate interference between terminals before transmitting data. Common precoding solutions include: matched filter precoding, zero forcing precoding, MME precoding and block diagonalization precoding, etc. Take the zero forcing precoding as an example, the precoding base matrix W_P is calculated by W_P=H^H(HH^H)^-1=[W₁W₂...W_K], wherein

denotes the precoding base matrix of the ith terminal. The matrix W_i is extended according to the solution of embodiment 1 to obtain the extended precoding matrix W_E,i∈C^NxN of the ith terminal. Thereafter, for each terminal, one link is selected from the N virtual links to transmit symbols with modulation order Q, and precoding is performed to the transmission vector using the corresponding extended precoding matrix, and the symbols are transmitted via the antennas after IFFT. It can be seen that, log₂(NQ) bits can be transmitted to each terminal.

Through the precoding, the interference between the terminals can be effectively reduced or even eliminated. Therefore, the multi-user system can be equivalently seen as multiple single-user systems at this time. As such, the processing at each terminal is similar to that of the receiving end in the single-user system, i.e., firstly performing FFT processing to each link to obtain frequency-domain received signals, and then demodulating the received signals according to the channel estimation to obtain the estimated transmission data. The downlink channel estimation needs to estimate the basic equivalent channel consisting of the preprocessing base matrix and the frequency-domain equivalent channel of each terminal. After obtaining the estimation of the equivalent channel through channel estimation, the terminal obtains the estimation of the extended equivalent channel through the extending operation similar to that of the transmitting end, and uses the estimation of the extended equivalent channel for the demodulation of the received signals.

Compared with conventional multi-user large-scale MIMO system, if the terminal is equipped with a single antenna, since the solution provided by the present disclosure can bear more information through the link indices, under the same modulation scheme, the solution provided by the present disclosure is able to transmit more bits. These additional bits can be used for increasing system reliability through channel coding, or can be used for transmitting data to increase system throughput or data rate. Or, some of these bits can be coded whereas others are used for transmitting data, thus higher reliability as well as higher throughput can be obtained. For the terminal equipped with multiple receiving antennas, the multiple antennas may provide a diversity gain and increase link reliability. The terminal with multiple antennas may also be seen as multiple single-antenna terminals, so as to provide higher throughput and data rate.

It should be noted that, the above multi-user architecture is applicable for the TDD mode or the frequency-division duplex (FDD) mode. In particular, for the TDD mode, the base station obtains the channel state information of the downlink based on the uplink channel estimation through channel reciprocity. For the FDD mode, the base station selects preprocessing base matrix for respective terminal according to the channel state information fed back by the terminal and performs the extending operation.

The transmission of the reference signals in the multi-user system is similar as in embodiment 1. Reference signals of different terminals use orthogonal resources (including time, frequency or orthogonal code book resources, etc.). The reference signals are processed according to the precoding base matrix of each terminal and transmitted to the corresponding terminal. The terminal estimates its basic equivalent channel, and extends the basic equivalent channel according to the extending method consistent with the base station to obtain the estimation of the extended equivalent channel. The basic equivalent channel of each terminal is defined as an equivalent channel coefficient matrix including the precoding basic matrix, multicarrier modulation, actual physical channel from the transmitting end to the terminal and the multicarrier demodulation of the terminal. The estimation of the extended equivalent channel of each terminal is defined as the equivalent channel coefficient matrix including the extended precoding matrix, multicarrier modulation, the actual physical channel from the transmitting end to the terminal and the multicarrier demodulation of the terminal.

The Ninth Embodiment:

Embodiments

6, 7 and 8 provide applications and performance comparison of the solution provided by the present disclosure under the TDD mode. A common feature of these embodiments is that the base station knows the accurate channel state information, which greatly facilitates the calculation of the precoding base matrix at the transmitting end. But in the FDD mode, this is hard to be implemented. This embodiment provides an implementation under the FDD mode.

In the FDD mode, it is hard for the base station to obtain accurate channel state information, which brings much trouble for the calculation of the preprocessing base matrix. But based on the principle of the solution provided by the present disclosure, the preprocessing base matrix may be irrelevant to the channel state information. Although the calculation of the preprocessing base matrix based on the known channel state information is able to increase the receiving signal-to-noise ratio of the terminal, but a randomly selected preprocessing base matrix can also be used for generating the basic channel link, and the virtual links can also be generated via a method similar to embodiment 1. Therefore, the solution of the present disclosure is also applicable for the FDD mode. Hereinafter, the implementation of the present disclosure in the FDD mode is described with reference to an embodiment.

FIG. 25 is a flowchart illustrating a signal processing procedure based on a fixed preprocessing base matrix in the FDD mode according to an embodiment of the present disclosure. In this embodiment, since it is not required to calculate the preprocessing base matrix according to the channel state information, the calculation does not depend on the feedback from the terminal to the base station. In this embodiment, the signal processing procedure based on the fixed preprocessing base matrix includes: firstly, the base station selects an appropriate code word from a fixed code book set as the preprocessing base matrix. The matrix may be randomly selected or may be an appropriate code word selected according to the channel state information fed back by the terminal. In the second situation, during the downlink channel estimation, the base station may perform preprocessing to a reference signal to be transmitted based on the predefined code book. The terminal selects a code word with maximum receiving signal-to-noise ratio and feeds back the index of the code word. The base station takes the code word fed back by the terminal as the preprocessing base matrix. Then, after the preprocessing base matrix is selected, the corresponding preprocessing matrix extending operation may be performed. Similar as embodiment 1, linear combination, phase rotation and/or power allocation may be performed to the columns of the preprocessing base matrix to obtain the extended preprocessing matrix. Finally, preprocessing is performed to the spatial modulation symbols to be transmitted with the extended preprocessing matrix, and the preprocessed symbols are transmitted via each antenna after IFFT operation.

As to the channel estimation, the base station transmits demodulation reference signal used for estimating basic equivalent channel after selecting the preprocessing base matrix, and performing preprocessing to the reference signal with the preprocessing base matrix. After obtaining the estimation of the basic equivalent channel based on the demodulation reference signal, the terminal performs extending operation consistent with the base station to the estimation of the basic equivalent channel (including linear combination of columns, phase rotation and power allocation) to obtain estimation of extended equivalent channels. Finally, the terminal performs spatial demodulation processing to the received signal according to the estimation of the extended equivalent channels to obtain estimation of the transmitted bit stream.

Hereinafter, the effectiveness of the solution provided by this embodiment is described with reference to performance simulation.

Firstly, suppose that the base station is equipped with 4 transmit antennas, the terminal is equipped with 1 receiving antenna. The QPSK modulation scheme is utilized. At this time, the spectrum efficiency is 4bps/Hz. Three solutions are considered, among which:

A first solution adopts the fixed preprocessing base matrix as described in this embodiment, and the preprocessing base vector is fixedly selected at the base station as w_b=[1 j 1 -j]^T, where j is the imaginary unit.

A second solution adopts the fixed preprocessing base matrix as described in this embodiment, and the base station selects a code word from a preconfigured code book as the preprocessing base matrix according to the channel state information fed back by the terminal. The code book utilized in the simulation in this embodiment is described by a following matrix:

where each column of the matrix denotes a code word and the code words are orthogonal. j denotes the imaginary unit. The preprocessing of the above two solutions includes phase rotation and power allocation. The phase rotation angle is a multiple of π/8, and the power allocation proportion is: P₁:P₂:P₃:P₄=5:6:7:8, where P_idenotes the transmit power of the ith link, the average transmit power is normalized to 1.

A third solution is the conventional multicarrier spatial modulation system.

FIG. 26 shows the comparison of bit error rate performance of the above three solutions. It can be seen that, when the base station does not consider the channel state information, i.e., the first solution in which the same preprocessing base matrix is selected for different subcarriers, the performance is a litter inferior or similar to the conventional multicarrier spatial modulation. The advantage of this solution is: merely the equivalent channel before the extending needs to be estimated, thus the overhead for downlink equivalent channel estimation is reduced. The second solution which considers the channel state information has an obvious advantage. For example, when the bit error rate is about 10^-2, the third solution has an additional 5dB gain than the conventional solution. But the second solution has to perform physical channel estimation based on code book, which brings out certain overhead.

Now another situation is considered, in which the base station is equipped with 16 antennas and the terminal is equipped with 1 antenna. The QPSK modulation scheme is still utilized. At this time, the spectrum efficiency is 6bps/Hz. The following two solutions are considered: a first solution adopts the fixed preprocessing base matrix as described in this embodiment, and the base station selects a code word from a preconfigured code book as the preprocessing base matrix according to the channel state information fed back by the terminal. The code book adopted in the simulation includes 4 columns selected with equal interval from a DFT matrix with a dimension of 16, i.e.

Each column in the above matrix denotes a code word. The second solution is the conventional multicarrier spatial modulation system.

FIG. 27 shows comparison of the bit error rate performance of the above two solutions. It can be seen that, compared with the conventional solution, the solution provided by the present disclosure can achieve better performance even if a small code book is adopted. In addition, the utilization of the small code book can reduce the overhead of the downlink channel estimation. The above shows that, even in the FDD mode, the solution provided by the present disclosure can achieve obvious performance gain with relatively small channel estimation and feedback cost. When the receiving end is equipped with multiple antennas, the code book may be designed taking a row full rank matrix as a code word. The transmitting end selects a code word matrix as the preprocessing base matrix according to the feedback from the receiving end and obtains the extended preprocessing matrix. In this scenario, the flexibility of the extending operation may be improved through taking the row full rank matrix as the preprocessing base matrix, which is favorable for obtaining large symbol distance and thereby obtaining better bit error performance.

The Tenth Embodiment:

This embodiment provides an adaptive parameter adjusting manner of the method provided by the present disclosure.

For a time-variant channel environment in practical communication scenario, the system parameters need to be adjusted in real time according to the channel state information, so as to optimize system performance. As to the solution provided by the present disclosure, the following may be adjusted according to the channel state information: the dimension of the extended preprocessing matrix, the dimension and selecting mode of the preprocessing base matrix, selection of the phase rotation angel, selection of power allocation, and the insertion frequency of the pilot used for estimating downlink equivalent channel at the transmitting end, etc. FIG. 28 is a schematic diagram illustrating the generation of preprocessing matrix based on adaptive parameter selection according to an embodiment of the present disclosure.

If the channel varies fast, the channel estimation error may lead to inaccuracy of the estimation of the effective channel. In the solution provided by the present disclosure, the virtual links are generated utilizing phase rotation and power allocation. Therefore, the channel estimation error may lead to decrease of Euclidean distance between symbols and thereby lead to increase of bit error rate. Considering that the extending of the preprocessing base matrix can be adjusted, i.e., the dimension of the extended preprocessing matrix W may be an integer N_c≥N_b, where N_cdenotes the number of columns of the matrix W, N_bdenotes the number of columns of the preprocessing base matrix, and the dimension of the extended preprocessing matrix W determines the number of effective transmission links and thereby determining the number of bits transmitted in the spatial domain, therefore a high dimension may increase data rate, and a low dimension can ensure a large difference between virtual links and increase the Euclidean distance between symbols at the receiving end and thereby increasing estimation accuracy of the system. The adjusting of the dimension of the extended preprocessing matrix W also leads to the adjusting of the phase rotation and power allocation. In particular, if the channel varies fast and the channel estimation at the receiving end is inaccurate, the estimation accuracy at the receiving end needs to be increased. Therefore, it is possible to select an extended preprocessing matrix with a low dimension, a large phase rotation angle and a power allocation mode with large difference between power allocation factors. On the contrary, if the channel condition is good, it may be an objective to increase the system data rate. Thus, it is possible to select an extended matrix with a high dimension, a small phase rotation angle and a power allocation mode with a little difference between power allocation factors.

For the FDD mode, the preprocessing base matrix is selected based on the channel state information. Therefore, the number of columns is not determined by the number of transmit antennas or the number of receiving antennas. The preprocessing base matrix with more columns may bring more flexibility to subsequent extending operation, and is favorable for improving system performance. However, the overhead used for downlink equivalent channel estimation is increased at the same time. Therefore, when the channel varies fast or is highly frequency/time selective, the preprocessing base matrix with more columns may be utilized, so as to increase link reliability; otherwise, the preprocessing base matrix with fewer columns may be selected, so as to reduce the overhead of the downlink equivalent channel estimation.

The above selection of the dimension of the preprocessing matrix shows that,W=W_bW_e, where

. Among these matrixes, merely the number of rows N of the preprocessing base matrix has to be consistent with the number of transmit antennas. Both N_b and N_c may be determined according to the feedback from the receiving end. For example, N_b may be determined by the channel state information such as channel varying speed or rank of the equivalent channel or may be determined by the available reference signal. N_c may be determined by the channel state information fed back by the receiving end and the data rate required by the receiving end.

In addition, when the channel varies fast or is highly frequency/time selective, there may be large error if merely estimating the basic equivalent channel and recovering the extended equivalent channel based on the basic equivalent channel, which makes the channel estimation inaccurate. At this time, it is possible to estimate the channel of some virtual links, so as to correct the estimation of the extended equivalent channel. In this embodiment, insertion of the reference signal and the channel estimation procedure are as shown in FIG. 29.

In FIG. 29, the reference signal is inserted for two times. In the first time, after the preprocessing base matrix is generated, preprocessing is performed to reference signal 1 using the preprocessing base matrix. The terminal estimates the equivalent channel according to the reference signal 1. Thereafter, the terminal extends the equivalent channel using the extending rule consistent with the base station to obtain the estimation of the extended equivalent channel. After obtaining the extended preprocessing matrix, the base station inserts reference signal 2 at the second time and performs preprocessing to the reference signal 2 using the extended preprocessing matrix and transmits the preprocessed reference signal 2. The terminal estimates the extended virtual link channel according to the reference signal 2, and corrects the previously obtained estimation of the extended equivalent channel based on the extended virtual link channel. It should be noted that, since the reference signal inserted at the second time is merely used for correcting the estimation of the equivalent channel, the inserting density may be adjusted according to the reliability of the channel. For example, if the current channel condition is good and the data transmission is relatively reliable, the insertion density of the reference signal at the second time may be low or even no insertion is required. If the channel condition is bad and the data transmission is less reliable, the insertion density of the reference signal at the second time needs to be increased.

The Eleventh Embodiment:

This embodiment provides an implementation of an open loop system with respect to single-antenna terminal provided by the solution of the present disclosure. Suppose that the base station already knows the channel state information and the terminal is equipped with a single antenna. At this time, the base station needs to increase the Euclidean distance between symbols at the receiving end through selecting the preprocessing base matrix, power allocation and phase rotation operations. The criterion for selecting the power allocation factor and the phase rotation angle is: let the minimum distance between constellation points in the equivalent constellation at the single-antenna receiving end as large as possible through the power allocation and the phase rotation between different links.

Firstly, a following situation is considered: the base station is equipped with 4 antennas and the QPSK modulation scheme is adopted. At this time, the spectrum efficiency is 4bps/Hz. A matrix with 4 rows and 1 column is selected as the preprocessing base matrix. The extended preprocessing matrix is generated through power allocation and phase rotation operations. The selection of the power allocation factors and the phase rotation angles are as shown in Table 4. It should be noted that, the generation of the phase rotation angles considers the amplitude and phase relationship between QPSK constellation and 16QAM constellation.

Table 4

Link index	1	2	3	4
Power factor	0.2	1	1.8	1
Rotation angle °	0	26.57	0	-26.57

Table 4: selection of power allocation factors and phase rotation angles when the transmitting end is equipped with 4 antennas

Based on the power allocation factors and the phase rotation angles as shown in Table 4, a satisfactory Euclidean distance between symbols may be obtained in the constellation at the receiving end. FIG. 30 shows a constellation with preprocessing and a constellation without preprocessing obtained by the receiving end for a particular channel realization. The left side of FIG. 30 shows the original constellation at the receiving end obtained without preprocessing. It can be seen that, due to the impact of the channel time and frequency selective fading, the Euclidean distance between some constellation points in the equivalent constellation at the receiving end is rather small, which degrades the system estimation performance. The right part of FIG. 30 shows the constellation at the receiving end when preprocessing is performed. The equivalent constellation at the receiving end is similar to a rotated 16QAM constellation. The average minimum Euclidean distance is increased. Therefore, the system estimation performance is enhanced. FIG. 31 shows comparison of the bit error rate performance of the above two solutions. It can be seen that, due to the increase of the distance between symbols, the solution involving preprocessing has an enhanced bit error rate performance.

Then, another situation is considered: the base station is equipped with 16 antennas and the QPSK modulation scheme is still utilized. At this time, the spectrum efficiency is 6bps/Hz. A vector with 16 rows and 1 column is randomly selected as the preprocessing base matrix. The selection of the power allocation factors and the phase rotation angle are as shown in Table 5.

Table 5

Link index	1	2	3	4	5	6	7	8
Power factor	2.33	1.77	1.77	1.19	1.19	1.38	1.38	1.19
Rotation angle °	0	9.46	-9.46	36.87	-36.87	21.80	-21.80	0
Link index	9	10	11	12	13	14	15	16
Power factor	0.62	0.62	0.81	0.81	0.05	0.24	0.24	0.43
Rotation angle °	33.69	-33.69	14.04	-14.04	0	26.57	-26.57	0

Table 5: selection of power allocation factors and phase rotation angles in the case that the base station is equipped with 16 antennas

FIG. 32 is a schematic diagram illustrating an equivalent constellation with preprocessing and an equivalent constellation without preprocessing at the receiving end for a particular channel realization. As shown by the left constellation in FIG. 32, in the case that there is no preprocessing, due to the impact of the channel, the Euclidean distance between some points in the equivalent constellation at the receiving end may be rather small, which degrades system bit error rate performance. However, as shown by the right part of FIG. 32, after the preprocessing, the equivalent constellation at the receiving end is similar to a rotated one of 16QAM, in which a certain Euclidean distance is ensured between each pair of constellation points. Therefore the minimum Euclidean distance between symbols is greatly increased and the bit error performance of the whole system is improved.

FIG. 33 is a schematic diagram illustrating comparison of bit error rate performance of the above two solutions in the case that the base station is equipped with 16 antennas. With the increase of data rate, the number of constellation points in the equivalent constellation at the receiving end also increases. Therefore, the system is easier to be interfered by noise. After the preprocessing, the minimum Euclidean distance between constellation points is increased. Therefore, the system has an enhanced capability against noise and the bit error rate performance of the whole system is improved. It can be seen from FIG. 33 that, after the preprocessing method provided by the present disclosure is applied, the bit error rate performance of the system is enhanced.

It should be noted that, in this embodiment, a constellation similar to the QAM modulation scheme is generated at the receiving end through the power allocation and the phase rotation. Constellation of other types may also be generated through adjusting the power allocation and phase rotation values. But the basic criterion is to make the minimum Euclidean distance between constellation points in the equivalent constellation at the receiving end is as large as possible.

The Twelfth Embodiment:

This embodiment provides an application of the solution of the present disclosure for reducing reference signal overhead. Suppose that the base station is equipped with 4 transmit antennas, the receiving end is equipped with 1 receiving antenna, and the base station does not know the channel state information. The preprocessing base matrix is defined as follows:

The rank of the preprocessing base matrix is 3, i.e., the column vectors of the matrix are not linear correlated. The matrix is extended through linear combination of the columns of the matrix, i.e., the first three columns of the extended preprocessing matrix are the three columns of the preprocessing base matrix W_b, the fourth column is w₄=w₁-w₂+w₃. Thus, the extended preprocessing matrix is obtained as follows:

The equivalent extended matrix is:

There are still 4 equivalent links. In order to transmit the spatial modulation symbols as described in the above embodiments, one of the four equivalent links is activated during each transmission. Information is transmitted through the index of the activated link and the transmitted symbols.

Since the column rank of the preprocessing base matrix is 3, merely 3 reference signals using orthogonal resources are required to finish the estimation of the basic equivalent channel. Thereafter, through the extension of the extended matrix W_e, the extended equivalent channel may be obtained and the estimation of the transmitted signal may be implemented.

The above embodiment shows that, a preprocessing base matrix with a corresponding column rank may be designed according to the amount of available reference signal or amount of resources available for transmitting reference signals. The extended preprocessing matrix may be generated through simple linear combination of the columns of the preprocessing base matrix. It is possible to achieve a high data rate with relatively low overhead of the reference signal. As such, a tradeoff between the overhead of the reference signal and the data rate may be obtained. Considering that the length of the reference signal is generally a power of 2, the occupied orthogonal resources are also a power of 2. If the required reference signal does not meet this condition, unused reference signal resources may be utilized to transmit data, so as to reduce overhead.

The above embodiment is taken as an example. Suppose that the length of the reference signal is 4. Although the number of required reference signals is 3, 4 orthogonal resources are still required to transmit the reference signals. Therefore, the overhead of the reference signal does not change. At this time, the orthogonal resource which is not used for transmitting reference signal may be used for transmitting data, and the data may be differentiated from the reference signals by orthogonal cover code technique, so as to reduce the overhead of the reference signal.

In accordance with the above signal transmitting method based on multicarrier spatial modulation, an embodiment of the present disclosure provides a transmitting apparatus, as shown in FIG. 34. The transmitting apparatus includes: a first preprocessing base matrix calculating module, a first preprocessing matrix extending module, a first reference signal transmitting module and a first data transmitting module; wherein

the first reference signal transmitting module is configured to perform preprocessing to a first reference signal with the preprocessing base matrix and transmit the preprocessed first reference signal to the receiving apparatus; and

the first data transmitting module is configured to perform symbol mapping and spatial modulation on a bit steam to be transmitted, and perform preprocessing on symbols obtained after the spatial modulation with the extended preprocessing matrix, perform multicarrier modulation on the preprocessed symbols and transmit the symbols to the receiving apparatus.

In accordance with the above signal transmitting method of the multi-user system based on the multicarrier spatial modulation, an embodiment of the present disclosure provides a transmitting apparatus, as shown in FIG. 35. It includes: a second preprocessing base matrix calculating module, a second preprocessing matrix extending module, a second reference signal transmitting module and a second data transmitting module; wherein

the second reference signal transmitting module is configured to perform preprocessing to a reference signal with the preprocessing base matrix, and transmit the preprocessed reference signal to the corresponding terminal; wherein the reference signal transmitted to different terminals uses orthogonal resources; and

the second data transmitting module is configured to respectively perform symbol mapping and spatial modulation on a bit stream of each terminal, perform preprocessing to spatial modulation symbols using the corresponding extended preprocessing matrix, combine the preprocessed symbols of respective terminal, perform multicarrier modulation on the combined symbols and transmit the symbols.

In accordance with the above signal transmitting method based on the multicarrier spatial modulation, an embodiment of the present disclosure provides a receiving apparatus, as shown in FIG. 36. It includes a receiving module, a basic equivalent channel estimation module, an extended equivalent channel estimation module and a demodulating module; wherein

the extended equivalent channel estimation module is configured to extend the basic equivalent channel using a manner consistent with that used by a transmitting apparatus for extending a preprocessing base matrix, to obtain an estimation of an extended equivalent channel; and

In one embodiment, the receiving module in the receiving apparatus further receives a second reference signal;

the extended equivalent channel estimation module further corrects the estimation of the extended equivalent channel according to the second reference signal.

The Thirteenth Embodiment:

In this embodiment, the method of combination of antenna port grouping and pre-processing based on spatial modulation will be described.

Assume multiple UEs are served within one cell. In order to serve multiple UEs in a broadcasting way, the methods in embodiments 1-5 can be applied. To enhance the performance, the pre-processing method can be applied. Specifically, the antenna grouping is based on the effective antenna ports generated by pre-processing. The basic procedure is described as follows.

1. UE estimates the downlink channel state information through CSI-RS or CRS, and reports the corresponding channel state information to BS by using quantified CSI or codebook based CSI feedback. In this step, base station can obtain the downlink CSI from multiple UEs. Another way to obtain downlink CSI is through uplink channel estimation by utilizing the channel reciprocity of TDD mode.

2. According to the downlink CSI from multiple UEs, the UEs with similar downlink channel state information are grouped as one group. For one UE group, one downlink CSI is used to calculate the pre-processing matrix. One potential way to obtain the downlink CSI for one UE group is to average all the downlink CSI for UEs of this UE group.

3. Based on the downlink CSI for UE group, the pre-processing matrix is calculated based on the methods proposed in embodiments 1-5. Specifically, the two-step method is used, including basic pre-processing matrix calculation based on the downlink CSI for UE group, and the extension by using the pre-defined extension method. In this step, the effective antenna ports corresponding to effective links are established.

4. Based on the effective antenna ports, the antenna ports grouping can be performed. Considering that the pre-processing procedure can be transparent to UEs, the only thing that should be informed to UEs is the antenna ports grouping information and the informing method proposed in previous embodiments can be applied.

5. Broadcast information is transmitted to multiple UEs within one group based on layered spatial modulation.

Note that the aforementioned layering of transmitted data in previous embodiments can be still applied to the pre-processing based scheme. Also note that the channel frequency selectivity as well as channel time selectivity will determine the parameters of pre-processing methods, as demonstrated in previous embodiments.

If there is no UE grouping procedure, or there is no downlink CSI of multiple UEs, random base matric or fixed base matrix can be used to generate the pre-processing matrix. In this way, no feedback is required with slightly performance loss.

The foregoing is only the preferred embodiments of the present application, and is not intended to limit the present application, and any of modifications, equivalent substitutions and improvements, etc, made within the spirit and principle of the application should fall into the scope of the claimed by the present application.

Claims

A signal transmitting method, characterized in that, the method comprising,

transmitting, by a transmitter, link grouping configuration information, wherein, said link grouping configuration information is, after dividing links into at least two groups, information of the links contained in each of the groups;

layering, by the transmitter, data flow to be transmitted according to grouping of the links;

performing, by the transmitter, spatial modulation on the layered data flow;

performing, by the transmitter, multi-carrier modulation on the spatial modulated signals; and

transmitting, by the transmitter, the multi-carrier modulated signals.
The method according to claim 1, characterized in that,

said dividing links into at least two groups comprising:

dividing all available links into at least two groups, resulting groups being as groups in a first layer;

further dividing each of the groups in the first layer into at least two groups, respectively, resulting groups being as groups in a second layer; andby this analogy, performing the dividing until each group contains only one link or a setting requirement of link grouping has been met;

said layering, by the transmitter, data flow to be transmitted according to grouping of the links comprising:

transmitting basic data using the groups in the first layer, and transmitting auxiliary data using the groups in each of the layers other than the first layer on the basis of previous layer; wherein said auxiliary data includes at least one of: extended data based on the basic data, redundant information of the data in previous layer, and the combination of said extended data and the redundant information; and

utilizing constellation point symbols of the spatial modulation to transmit data in the lowest layer, or to transmit other auxiliary or redundant information;

a criterion of dividing links into groups is to allocate links with correlation indexes greater than a setting threshold into one group;

estimating, by the transmitter, the correlation indexes between links according to information from a receiver, and hereby dynamically adjusting number of links and the grouping of links; wherein, said information from the receiver comprises channel state information fed back from the receiver and/or sounding reference signal transmitted by the receiver to the transmitter via uplink channel; and

allocating users with the same link grouping configuration information into one group, and performing broadcast service on same time-frequency resources for users in the same group.
The method according to claims 1 or 2, characterized in that, the method further comprising:

after pre-processing the spatial modulated signals, performing the multi-carrier modulation and the transmitting;

said pre-processing comprising: performing power adjustment on the links and/or phase adjustment on the links;

said performing power adjustment on the links comprising: adjusting, while maintaining transmission power unchanged, average transmission power of each of the groups in the first layer, so that each of the groups having different average transmission power; adjusting, while maintaining the average transmission power of each of the groups in the first layer unchanged, average transmission power of each of the groups in the second layer, so that each of the groups in the second layer can have different average transmission power; and by this analogy, performing the adjusting, until adjustment on the average transmission power of each of the groups in the lowest layer is completed;

the criterion of adjusting average transmission power of the groups in each of the layers is that an amount of power adjustment of a layer is no more than that of its previous layer;

said performing phase adjustment on the links comprising: randomly selecting rotation phase for the links of each of the groups in the lowest layer, the interval of rotation phase of each of the links belonging to different groups does not intersect, selecting adjacent rotation phase interval for the links of each of the groups belonging to the same group in the previous layer;

transmitting, by the transmitter, reference signals according to the grouping of the links;

said transmitting, by the transmitter, reference signals according to the grouping of the links comprising: transmitting, , by the transmitter, same reference signals sequence using same time-frequency resources for the links belonging to the same group, for estimation of equivalent channel coefficient of corresponding groups;

if the multi-carrier modulation and transmission are preformed after pre-processing the spatial modulated signal, further comprising, prior to transmitting the reference signal: performing said pre-processing on said reference signal;

dividing the layered data in each of the layers into blocks, and adding independent cyclic redundancy check (CRC) code for data of each layer in each of the blocks of data;

the transmitter transmits link-number information and the link grouping configuration information in at least one of physical broadcast channel, physical downlink control channel and physical downlink shared channel;

the transmitter transmits in the physical broadcast channel, physical downlink control channel or physical downlink shared channel added with additional fields, said additional fields indicating the link-number information and the link grouping configuration information;

the transmitter transmits link-number information using CRC check masks in the physical broadcast channel, each of transmission modes of the physical broadcast channel corresponding to at least two CRC check masks, each CRC check mask corresponding to one kind of information about the number of links, respectively; wherein, the transmission modes of the physical broadcast channel include a single-antenna port transmission mode, a dual-antenna port transmission diversity mode, and a four-antenna port transmission diversity mode; and

the transmitter transmits in the physical broadcast channel, physical downlink control channel or physical downlink shared channel added with additional fields, said additional fields indicating the link grouping configuration information.
A transmitter, characterized in that, comprising:

a configuration module, for transmitting link grouping configuration information, wherein, said link grouping configuration information is, after dividing links into at least two groups, information of the links contained in each of the groups;

a data layering module, for layering data flow to be transmitted according to grouping of the links;

a spatial modulation module, for performing spatial modulation on the layered data flow;

a multi-carrier modulation module, for performing multi-carrier modulation on the spatial modulated signals; and

a transmitting module, for transmitting the multi-carrier modulated signals.
A signal receiving method, characterized in that, said method comprising:

receiving, by a receiver, link grouping configuration information;

acquiring, by the receiver, grouping of links and information of the links contained in each of the groups, according to said link grouping configuration information;

performing, by the receiver, layered-detection on the received data according to the grouping of the links;

performing, by the receiver, layered-detection on the received data according to the grouping of the links comprising:

detecting, by the receiver, transmitted data from all layers according to channel state information of each link, and determines number of layers up to which to be kept according to a setting criterion; wherein said setting criterion includes: comparing estimated signal-to-noise ratio of the detected data from each of the layers with a pre-set signal-to-noise ratio threshold, and in case of being higher than said signal-to-noise ratio threshold, keeping data in corresponding layer and performing subsequent processing, otherwise, performing no subsequent processing; or, said setting criterion includes: determining, by a transmitter, whether to keep data of the corresponding layer for each receiver according to whether CRC check, added by the transmitter independently for each layer of data, has passed;

detecting, by the receiver, data in each of the layers layer-by-layer according to channel state information of each of the groups, and comparing estimated signal-to-noise ratio of the detected data from each of the layers with a pre-set signal-to-noise ratio threshold, and if higher than said signal-to-noise ratio threshold, performing subsequent detection of data of next layer, and otherwise, terminating the detection; and

receiving, by the receiver, reference signals according to the grouping of the links, and performing channel estimation.
A receiver, characterized in that, comprising:

a configuration information receiving module, for receiving link grouping configuration information;

a grouping acknowledgement module, for acquiring grouping of links and information of the links contained in each of the groups, according to said link grouping configuration information; and

a detection module, for performing the layered-detection on the received data according to the grouping of the links.
A signal transmitting method based on multicarrier spatial modulation, comprising:

a transmitting apparatus determining a preprocessing base matrix, and extending the preprocessing base matrix to obtain an extended preprocessing matrix;

the transmitting apparatus preprocessing a first reference signal with the preprocessing base matrix, and transmitting the preprocessed first reference signal to a receiving apparatus;

the transmitting apparatus performing symbol mapping and spatial modulation on a bit stream to be transmitted, preprocessing symbols obtained after spatial modulation with the extended preprocessing matrix, and transmitting the preprocessed symbols to the receiving apparatus after multicarrier modulation;

wherein the determining the preprocessing base matrix comprises at least one of: calculating the preprocessing base matrix according to channel state information, using a predefined preprocessing base matrix, or selecting the preprocessing base matrix from a predefined code book according to feedback from the receiving apparatus;

wherein the calculating the preprocessing base matrix according to the channel state information comprises: calculating the preprocessing base matrix according to a channel coefficient matrix using a precoding algorithm; wherein the precoding algorithm comprises at least one of: matched filter algorithm, zero-forcing algorithm, and minimum mean square error precoding algorithm; and

wherein the channel coefficient matrix includes equivalent frequency-domain channel coefficients consisting of multicarrier modulation, actual physical channel between the transmitting apparatus and the receiving apparatus and the multicarrier demodulation.
The method of claim 7, further comprising:

the transmitting apparatus determining the number of columns of the extended preprocessing matrix according to information fed back by the receiving apparatus;

whereinthe extending the preprocessing base matrix to obtain the extended preprocessing matrix comprises any one or any combination of:

performing a linear combination to columns of the preprocessing base matrix to obtain a column of the extended preprocessing matrix;

performing phase rotation to the columns of the preprocessing base matrix to obtain columns of the extended preprocessing matrix, wherein rotated phases of different elements in each column are the same or different;

multiplying columns of the preprocessing base matrix by a power allocation factor to obtain the columns of the extended preprocessing matrix;

wherein the number of rows of the preprocessing base matrix equals to the number of transmit antennas, the number of columns of the preprocessing base matrix is determined by the transmitting apparatus according to the channel state information fed back by the receiving apparatus and the number of available reference signals or the amount of resources available for transmitting the reference signals; and

wherein the number of rows of the extended preprocessing matrix equals to the number of rows of the preprocessing base matrix, and the number of columns of the extended preprocessing matrix is larger than or equal to the number of columns of the preprocessing base matrix.
The method of claims 7 or 8, further comprising:

the transmitting apparatus preprocessing a second reference signal with the extended preprocessing matrix and transmitting the preprocessed second reference signal to the receiving apparatus;

the transmitting apparatus adjusting an inserting density of the second reference signal according to the channel state information fed back by the receiving apparatus, wherein the adjusting comprises at least one of: the transmitting apparatus selecting to not insert the second signal, insert with a density lower than the number of columns of the preprocessing matrix, or insert with a density equal to the number of columns of the preprocessing matrix;

wherein the first reference signal is used for estimating a basic equivalent channel, and the second reference signal is used for correcting the estimation of the extended equivalent channel; and

the basic equivalent channel consists of the preprocessing base matrix, multicarrier modulation, actual physical channel and multicarrier demodulation.
A transmitting apparatus, comprising: a first preprocessing base matrix calculating module, a first preprocessing matrix extending module, a first reference signal transmitting module and a first data transmitting module; wherein

the first preprocessing base matrix calculating module is configured to determine a preprocessing base matrix;

the first preprocessing matrix extending module is configured to extend the preprocessing base matrix to obtain an extended preprocessing matrix;

the first reference signal transmitting module is configured to performing preprocessing to a first reference signal with the preprocessing base matrix and transmit preprocessed first reference signal to a receiving apparatus; and

the first data transmitting module is configured to perform symbol mapping and spatial modulation on a bit stream to be transmitted, and perform preprocessing on symbols obtained after the spatial modulation with the extended preprocessing matrix, and transmit the preprocessed symbols to the receiving apparatus after multicarrier modulation.
A signal transmitting method based on multicarrier spatial modulation in a multi-user system, comprising:

a transmitting apparatus selecting a preprocessing base matrix for each terminal according to channel state information, and extending the preprocessing base matrix of each terminal to obtain a corresponding extended preprocessing matrix;

the transmitting apparatus performing preprocessing to a reference signal with respective preprocessing base matrix, and transmitting the preprocessed reference signal to a corresponding terminal, wherein the reference signals transmitted to different terminals use orthogonal resources;

the transmitting apparatus performing symbol mapping and spatial modulation respectively on a bit stream of each terminal, and performing preprocessing on symbols obtained after the spatial modulation of each terminal with the corresponding extended preprocessing matrix; and

the transmitting apparatus combining the preprocessed symbols of each terminal, and transmitting the combined symbols after multicarrier modulation.
The method of claim 11, wherein

the terminals are receiving apparatuses which are served simultaneously and using the same time-frequency resources;

wherein the transmitting apparatus selecting the preprocessing base matrix for each terminal according to the channel state information comprises at least one of: the transmitting apparatus calculating the preprocessing base matrix according to a channel coefficient matrix, or selecting the preprocessing base matrix from a predefined code book according to the channel state information fed back by the terminals;

wherein the channel coefficient matrix includes equivalent frequency-domain channel coefficients consisting of multicarrier modulation, actual physical channel between the transmitting apparatus and all terminals, and multicarrier demodulation of each terminal; and

wherein the combining comprises: adding the symbols to be transmitted on the same link.
A transmitting apparatus, applicable to a multi-user system based on multicarrier spatial modulation, comprising: a second preprocessing base matrix calculating module, a second preprocessing matrix extending module, a second reference signal transmitting module, and a second data transmitting module; wherein

the second preprocessing base matrix calculating module is configured to select a preprocessing base matrix for each terminal according to channel state information;

the second preprocessing matrix extending module is configured to extend the preprocessing base matrix of each terminal to obtain a corresponding extended preprocessing matrix;

the second reference signal transmitting module is configured to perform preprocessing to a reference signal with respective preprocessing base matrix and transmit the preprocessed reference signal to the corresponding terminal, wherein the reference signal transmitted to different terminals use orthogonal resources; and

the second data transmitting module is configured to perform symbol mapping and spatial modulation respectively on a bit stream of each terminal, and performing preprocessing on symbols obtained after the spatial modulation with the corresponding extended preprocessing matrix, combine the preprocessed symbols of the terminals, and transmit the combined symbols after multicarrier modulation.
A signal receiving method based on multicarrier spatial modulation, comprising:

a receiving apparatus receiving a first reference signal, estimating a basic equivalent channel based on the first reference signal;

the receiving apparatus extending estimation of the basic equivalent channel using a manner consistent with that used by a transmitting apparatus for extending a preprocessing base matrix, to obtain an estimation of an extended equivalent channel;

the receiving apparatus receiving data, and demodulating the received data according to the estimation of the extended equivalent channel to obtain original data; and

the receiving apparatus receiving a second reference signal, and correcting the estimation of the extended equivalent channel according to the second reference signal.
A receiving apparatus, comprising: a receiving module, a basic equivalent channel estimation module, an extended equivalent channel estimation module and a demodulating module; wherein

the receiving module is configured to receive a first reference signal and data;

the basic equivalent channel estimating module is configured to estimate a basic equivalent channel based on the first reference signal;

the extended equivalent channel estimation module is configured to extend the basic equivalent channel using a method consistent with that used by a transmitting apparatus for extending a preprocessing base matrix, to obtain an estimation of an extended equivalent channel;

the demodulating module is configured to demodulate the data according to the estimation of the extended equivalent channel to obtain original data;

wherein the receiving module is further configured to receive a second reference signal; and

the extended equivalent channel estimation module is further configured to correct the estimation of the extended equivalent channel according to the second reference signal.