CN117395111A - Subcarrier space arrangement indexing method of MIMO-OFDM system - Google Patents
Subcarrier space arrangement indexing method of MIMO-OFDM system Download PDFInfo
- Publication number
- CN117395111A CN117395111A CN202311306435.4A CN202311306435A CN117395111A CN 117395111 A CN117395111 A CN 117395111A CN 202311306435 A CN202311306435 A CN 202311306435A CN 117395111 A CN117395111 A CN 117395111A
- Authority
- CN
- China
- Prior art keywords
- data
- subcarrier
- matrix
- qam
- antenna
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000011159 matrix material Substances 0.000 claims abstract description 38
- 238000013507 mapping Methods 0.000 claims abstract description 10
- 239000013598 vector Substances 0.000 claims description 16
- 238000007476 Maximum Likelihood Methods 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 claims description 6
- 239000000969 carrier Substances 0.000 claims description 3
- 238000001514 detection method Methods 0.000 claims description 3
- 230000021615 conjugation Effects 0.000 claims description 2
- 238000012163 sequencing technique Methods 0.000 claims description 2
- 238000004891 communication Methods 0.000 abstract description 10
- 238000001228 spectrum Methods 0.000 abstract description 6
- 238000006243 chemical reaction Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 3
- 238000005562 fading Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/12—Frequency diversity
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
Abstract
The invention discloses a subcarrier space arrangement indexing method of a MIMO-OFDM system. The method respectively carries out QAM modulation and index modulation on the source bit group of the transmitting end. The index modulated bits are mapped into a subcarrier space array matrix, multiplied by a constellation diagram modulated by QAM, and then subjected to space-time mapping to obtain the data to be transmitted by subcarriers of each transmitting antenna. The time domain signal to be transmitted by each antenna is then generated by IDFT variation. Demodulating in a corresponding mode at a receiving end to obtain a subcarrier space arrangement matrix and QAM symbols, mapping the subcarrier space arrangement matrix and index bits, and performing serial-parallel conversion to obtain source bit data. The method starts from the utilization of space resources, can improve the utilization rate of frequency spectrum, realizes a certain degree of receiving diversity, has better error rate and demodulator complexity than the prior art, and ensures that the communication quality and the utilization rate of frequency spectrum reach a balance.
Description
Technical Field
The invention belongs to the technical field of wireless communication, relates to a digital signal processing method of index modulation in baseband modulation, and in particular relates to a subcarrier space arrangement index method of a MIMO-OFDM system.
Background
The huge number of users of 5G wireless networks will greatly increase the energy consumption. Therefore, in the design process of communication between devices, spectrum sharing, ultra-dense network, millimeter wave network, internet of things communication, multiple Input Multiple Output (MIMO) system, and the like, the high data rate and high energy efficiency of the wireless communication system have high priority. The proposal of the MIMO technology enables the space resource to be better utilized, has obvious improvement in the aspects of channel capacity and error performance, and is the basis of the next generation wireless communication system. MIMO systems increase throughput and coverage on the one hand and on the other hand provide capacity and diversity gains by exploiting the multi-channel capability. MIMO systems enable the use of spatial resources, and one of the key goals is to increase the data transmission rate and spectrum utilization by using distinguishable spatial information. Conventional space-time block codes (STBC) or vertical layered space-time coding (V-BLAST) can maximize diversity and multiplexing gain, but the requirements on the channel are very demanding, and when the channel conditions cannot be met, there is severe inter-subcarrier interference (ICI).
Spatial Modulation (SM) technology is an important MIMO technology that has emerged in recent years. In the SM scheme, in order to obtain the space diversity of rich scattering environments, the receiving end and the transmitting end are provided with a plurality of antennas, but in each transmitting time slot, the transmitting end activates only one antenna, so that the problem of synchronization among antennas is solved, interference among channels is avoided, and the complexity of a communication system is greatly reduced. Furthermore, in the SM scheme, information is transferred using an active antenna index of a transmitter in addition to transmitting a data symbol. This scheme may allow the data rate to increase logarithmically with the number of transmit antennas. In a multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system, since data transmitted by one OFDM symbol is far greater than data carried by an active antenna index of a transmitter, in the MIMO-OFDM system, an SM modulation technique improves a data transmission rate very little, but a transmitter and a receiver become relatively complex.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a subcarrier space arrangement indexing method of an MIMO-OFDM system, which is characterized in that subcarriers of OFDM signals are grouped according to the number of antennas, and subcarriers in each group are respectively transmitted in different antennas according to different arrangement modes, so that the data transmission rate can be improved without increasing the bandwidth, and the frequency band utilization rate is improved.
A method for novel spatial index modulation of a MIMO-OFDM system, comprising the steps of:
step 1, in the MIMO-OFDM system of the P X Q antenna, the source data after channel coding is divided into m groups, whereinAnd m is an integer. The +.>The m groups get the QAM symbols { s } carried by N sub-carriers altogether 1 ,s 2 ,…,s N N, where N QAM Is a QAM modulation index. Initial space-frequency arrangement data block matrix M formed by ith group of subcarriers i The method comprises the following steps:
the matrix M i Is P, where i=1, 2, … m, s n Represents QAM data carried by the nth subcarrier of OFDM, n=1, 2, … N.
Step 2, D of the rest part in the ith group of source data imb Mapping bit data into subcarrier space arrangement index matrix I i ，D imb Satisfy the following requirementsThe index matrix I i The size of the vector is P, the vector is composed of P mutually orthogonal unit vectors, and each arrangement mode of the P unit vectors corresponds to one D imb Bit data.
Step 3, the initial space frequency number is calculatedData block M i And index matrix I i Multiplying to obtain space frequency data block matrix X carrying index information i Index matrix I i The arrangement modes of the unit vectors are different, the QAM symbols carried by the subcarriers are not changed, and only the transmitting antennas corresponding to the subcarriers are changed. Each space frequency data block X i Carry D imb +N QAM * P-bit data. Splicing the m space frequency data block matrixes according to the positive sequence of the subcarriers to obtain space frequency data matrixes S= [ X ] of the P antennas 1 X 2 X 3 …X m ]。
Step 4, IDFT calculation is sequentially performed on each row of the spatial data matrix S, so before IDFT calculation, each row of the matrix S needs to be constructed into a conjugate symmetric matrix form as shown in formula (4) in order to make the calculation result of IDFT be a pure real number:
in the aboveRepresenting the QAM symbols carried by the nth subcarrier on the p-th antenna. s represents the conjugation of s. />Is of a size of 1 XN zp All zero matrices of (a). Setting the oversampling rate C, c=n according to the number of 0 DFT /(N DFT -N zp ) Wherein N is DFT For the calculated length of IDFT and DFT, a large oversampling rate can reduce the error rate of the system. After IDFT calculation, the discrete form OFDM real signal x to be transmitted by the p-th antenna can be obtained p ：
Wherein k=0, 1,2, …, N DFT -1。S[p][n]Data representing the nth row and nth column of the space frequency data matrix S. p=1, 2,..p. After IDFT operation, space frequency data matrix S to be transmitted by the antenna is mapped into space time matrix blocks, x 1 ,x 2 ,…,x P Respectively emitted simultaneously through the P antennas.
And 5, grouping the received data according to a mode of transmitting subcarrier grouping. After receiving the signal, the receiving end performs OFDM demodulation and conversion to the frequency domain through DFT. In the MIMO-OFDM system, the perfect channel estimation is assumed, the MIMO channel has good scattering environment, the channel space is uncorrelated, the channel coherence time is far longer than the duration of the space-time block, and the transmission system model is as follows through the frequency selective fading channel:
wherein the method comprises the steps ofThe signal carried by the nth subcarrier received by the receiving antenna q. />The channel responses corresponding to the nth sub-carrier on the transmitting antenna p and the receiving antenna q are obtained. />Is the QAM signal carried by the nth subcarrier of the transmit antenna p. />Representing the additive noise of the nth subcarrier of the receiving antenna q.
According to the space frequency data matrix S, each subcarrier exists in only one antenna, namelyOnly one of which is not 0. Therefore->Can watchThe method is shown as follows:
wherein the method comprises the steps ofRepresented by the number t n N-th subcarrier data transmitted by the antenna, [ t ] 1 t 2 t 3 …t N ]Representing subcarrier spatial arrangement index information, t n ∈[1,2,…,P]。/>Indicating the receiving antenna q, numbered t n The channel response of the nth subcarrier is transmitted by the transmitting antenna. Since the N subcarriers of OFDM are divided into m groups of P subcarriers, the data received by each group of subcarriers is regarded as a vector:
number t in the m-th sub-carrier packet received by the receiving antenna q p The channel response of the p-th subcarrier of the transmit antennas of (c). Wherein->A data vector representing the mth packet received by the receiving antenna q. />And the QAM symbol carried by the p-th subcarrier in the m-th subcarrier group.
Step 6, antenna and QAM symbol detection is carried out on the received data vectors of the m groups of subcarrier groups by using a Maximum Likelihood (ML) detector:
wherein the method comprises the steps ofSpatial index information carried by the data vector for the mth group of subcarriers, and QAM symbols. Carry QAM data->The sub-carriers are numbered +.>Is provided.
And 7, performing QAM reflection on the data information subjected to ML demodulation of each group, demapping antenna index information, and finally obtaining a restored source bit stream after data sequencing.
The invention has the following beneficial effects:
aiming at the method that the transmitting end of the MIMO-OFDM system uses subcarrier grouping space arrangement, the number of OFDM subcarriers transmitted on each antenna is consistent, the frequency band utilization rate can be effectively improved by reasonably setting the grouping of the subcarriers, the data rate in the MIMO-OFDM system is increased logarithmically along with the number of transmitting antennas, and the PAPR (peak-to-average power ratio) on each transmitting antenna can be reduced. The receiving end can demodulate through a Maximum Likelihood (ML) demodulator to obtain a transmitting antenna index and QAM data. In addition, an MMSE equalizer can be used for noise removal and channel equalization, so that adverse effects on the transmission reliability of the system are avoided.
Drawings
Fig. 1 is a schematic diagram of a MIMO-OFDM system based on subcarrier spatial arrangement indexes;
the embodiment of fig. 2 enriches the system error rate results of different antenna combinations under scattering environment channels;
the system error rate results for different antenna combinations in the weak scattering environment channel in the embodiment of fig. 3.
Detailed Description
The invention is further explained below with reference to the drawings;
example 1
The present embodiment assumes that 24 original binary bit data after source coding is { 01110110100_1100101101101 }, using 4QAM modulation, the number of subcarriers n=8 of OFDM, the number of transmit antennas p=4, and the number of packets m=2, the original binary bit data is divided into {10110100_11011101} and {0111_1100}, where { 10100_11011101} is mapped into two initial space-frequency arrangement data blocks M by 4QAM modulation 1 ,M 2 ：
{0111_1100} is mapped to subcarrier spatially arranged index matrix I 1 ,I 2 ：
The mapping relationship is shown in table 1:
TABLE 1
The initial space frequency data block M i And index matrix I i Multiplying to obtain space frequency data block matrix X carrying index information i ：
Each space-frequency data block matrix X i Carrying 12 bits of data. Para [ X ] 1 X 2 ]Rearranging according to the subcarrier positions to obtain a space frequency data matrix S to be transmitted by the antenna:
each row of the matrix S is to represent data to be transmitted by one antenna. After receiving the signal, the receiving end can estimate the transmitted space arrangement index matrix I through maximum likelihood estimation, modulate the data M with QAM, and then obtain the original sequence through reflection.
Example 2
In an embodiment, after channel coding, QAM mapping, index matrix mapping, space-time mapping, a conjugate sequence is constructed for the obtained signal of each antenna, after IDFT calculation, an OFDM signal of each antenna is generated, and finally, the OFDM signal is transmitted through a radio frequency transmitting antenna. A corresponding MMSE frequency domain equalizer is designed on a receiving end, a QAM demodulator is cascaded at the back, and the ML subcarrier space arrangement decoder is firstly transmitted after the QAM demodulation. And finally, combining the index bit with the data bit, and obtaining a source bit stream after channel decoding. Specifically, the oversampling rate c=4, the ifft and FFT length is 1024, and the number of subcarriers n=400.
The error rates of different signal-to-noise ratios of the method under 10 multipath Rayleigh fading channels are calculated, the performances of the MISO-OFDM system, the double-transmission double-reception MIMO-OFDM system and the double-transmission four-reception system are compared, the result is shown in figure 2, the number of receiving antennas is increased, and the error rate can be obviously improved. It can be seen that MIMO-OFDM subcarrier spatial arrangement index modulation can effectively achieve receive diversity, and in a rich scattering environment, use spatial information to improve spectrum utilization and simultaneously enable reliable communication quality. Fig. 3 shows bit error rates of the method under different signal-to-noise ratios in a rayleigh fading channel with a multipath number of 2. Compared to fig. 2, it can be seen that the present system has better communication quality when multipath effects are weak. Compared with V-BLAST coding, the method reduces the requirement on scattering environment, improves the spectrum utilization rate and can obtain better communication quality. Can be applied to various channel environments. The method can realize a certain degree of receiving diversity, the error rate is superior to that of a space index (SM-OFDM) and a MIMO system based on V-BLAST coding, and the complexity of a demodulator is lower than that of the SM-OFDM and the MIMO system based on V-BLAST coding.
Claims (4)
- A subcarrier spatial arrangement indexing method of a mimo-OFDM system, characterized in that: the method specifically comprises the following steps:step 1, at the transmitting end of the MIMO-OFDM system with P antennas, firstly dividing the source data subjected to channel coding into m groups, whereinAnd m is an integer; the +.>Mapping the data into QAM symbols to obtain QAM symbols { s } carried by N subcarriers of a transmitting terminal 1 ,s 2 ,…,s N N, where N QAM Is a QAM modulation index; an initial space-frequency arranged data block matrix M of QAM symbols on the ith group of subcarriers i The method comprises the following steps:the matrix M i P, where i=1, 2, … m;step 2, D of the rest part in the ith group of source data imb Mapping bit data into subcarrier space arrangement index matrix I i ，D imb Satisfy the following requirementsThe index matrix I i Is composed of P mutually orthogonal unit vectors, the size of each unit vector is P, and each arrangement mode of the P unit vectors corresponds to one D imb Bit data;step 3, the initial space frequency data block M i And index matrix I i Multiplying to obtain space frequency data block matrix X carrying index information i Each space-frequency data block X i Carry D imb +N QAM * P-bit data; splicing the m space frequency data block matrixes according to the positive sequence of the subcarriers to obtain space frequency data matrixes S= [ X ] of the P antennas 1 X 2 X 3 … X m ]；Step 4, performing IDFT calculation on the space frequency data matrix S, mapping the space frequency data matrix S into a time sequence signal, and transmitting the time sequence signal by using a corresponding antenna; and (3) carrying out antenna and QAM symbol detection on the received data vector by using ML at a receiving end, then carrying out QAM reflection, carrying out antenna index information demapping according to the index matrix in the step (2), and finally obtaining restored source data after data sequencing.
- 2. The subcarrier spatial arrangement indexing method of a MIMO-OFDM system as claimed in claim 1, wherein: before IDFT calculation is carried out on an air frequency data matrix S, the following conjugate symmetric matrix is constructed for each row of the matrix in sequence:wherein the method comprises the steps ofRepresents QAM symbols carried by the nth subcarrier on the P-th antenna, p=1, 2, P; s is(s) * Represents the conjugation of s;is of a size of 1 XN zp All zero matrices of (a); setting the oversampling rate C and the calculated length N of the IDFT according to the number of 0 DFT ，C＝N DFT /(N DFT -N zp )；Calculating the time sequence signal x emitted by the p-th antenna p ：Wherein, S [ p ] [ n ] represents the data of the nth row and the nth column of the space frequency data matrix S.
- 3. The subcarrier spatial arrangement indexing method of a MIMO-OFDM system as claimed in claim 1, wherein: at the receiving end, assuming that the number of receiving antennas is Q, the transmission system model is:wherein,the signal carried by the nth subcarrier received by the receiving antenna q; />Represented by the number t n And (t) the QAM signal carried by the nth subcarrier transmitted by the antenna 1 t 2 t 3 … t N ]Representing subcarrier spatial arrangement index information, t n ∈[1,2,…,P]；/>Indicating the receiving antenna q and the number t n The channel response of the nth subcarrier under the transmitting antenna of (a); the data received by the receiving terminal carrier is expressed as:wherein,number t in the m-th sub-carrier packet received by the receiving antenna q p The channel response of the p-th subcarrier of the transmit antennas of (a); />A data vector representing the mth packet received by the receiving antenna q; />And the QAM symbol carried by the p-th subcarrier in the m-th subcarrier group.
- 4. The subcarrier spatial arrangement indexing method of a MIMO-OFDM system as set forth in claim 3, wherein: antenna and QAM symbol detection is performed on the received data vectors of the m groups of subcarrier packets using a maximum likelihood detector:wherein the method comprises the steps ofSpatial index information carried by data vectors of the m-th group of subcarriers and QAM symbols; carry QAM data->The sub-carriers are numbered +.>Is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311306435.4A CN117395111A (en) | 2023-10-10 | 2023-10-10 | Subcarrier space arrangement indexing method of MIMO-OFDM system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311306435.4A CN117395111A (en) | 2023-10-10 | 2023-10-10 | Subcarrier space arrangement indexing method of MIMO-OFDM system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117395111A true CN117395111A (en) | 2024-01-12 |
Family
ID=89438302
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311306435.4A Pending CN117395111A (en) | 2023-10-10 | 2023-10-10 | Subcarrier space arrangement indexing method of MIMO-OFDM system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117395111A (en) |
-
2023
- 2023-10-10 CN CN202311306435.4A patent/CN117395111A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100553186C (en) | OFDM channel estimating and multiple transmit antennas are followed the tracks of | |
| EP1531594A1 (en) | Apparatus and method for sub-carrier allocation in a multiple-input and multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) communication system | |
| CN110086743B (en) | Short burst MIMO-OFDM communication system and method based on differential coding | |
| Patil et al. | A review on MIMO OFDM technology basics and more | |
| Coon et al. | A comparison of MIMO-OFDM and MIMO-SCFDE in wlan environments | |
| Chaudhary et al. | WLAN-IEEE 802.11 ac: Simulation and performance evaluation with MIMO-OFDM | |
| CN101374036A (en) | Transmission diversity method and system for multi-input multi-output OFDM system | |
| Divyatha et al. | Design and BER performance of MIMO-OFDM for wireless broadband communications | |
| JP4459960B2 (en) | Multi-antenna system and method using high-throughput space-frequency block codes | |
| US20050007946A1 (en) | Multi-carrier transmission | |
| CA2722869A1 (en) | Methods and systems for hybrid mimo schemes in ofdm/a systems | |
| Wu et al. | Improved MIMO-OFDM scheme for the next generation WLAN | |
| Naumenko et al. | Signal-code construction based on space-time block coding with dual-mode index modulation aided OFDM | |
| CN117395111A (en) | Subcarrier space arrangement indexing method of MIMO-OFDM system | |
| Xuehua et al. | Study and implementation of MIMO-OFDM system based on Matlab | |
| Muoghalu et al. | MIMO-OFDM techniques for wireless communication system: performance evaluation review | |
| Nadiger et al. | MIMO-OFDM Implementation Using VLSI | |
| Akhtar et al. | A Comprehensive Performance Analysis of MIMO-OFDM Technology Using Different MIMO Configurations and M-QAM Modulation Schemes for LTE Cellular Network | |
| Boubaker et al. | A layered space-time coded wideband OFDM architecture for dispersive wireless links | |
| Xuehua et al. | Research and simulation of MIMO-OFDM wireless communication system | |
| CN110176978B (en) | Single-carrier and multi-carrier cross modulation 2 antenna transmitting device, receiving device and transmission method | |
| Yadav et al. | A Review on Compressed Sensing Space-Time Frequency Index Modulation in OFDM System | |
| Bergaoui et al. | Optimization of a scalable and adaptable diversity/multiplexing trade-Off in 28 GHz systems | |
| Gupta et al. | Space Time Block Coding Application for MIMO OFDM Broadband Wireless Solutions | |
| Kamatham et al. | Implementation of 2x2 MIMO-OFDM System using Universal Software Radio Peripherals |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |