CN110912585A - Antenna selection method based on channel factors - Google Patents

Abstract

The invention belongs to the technical field of communication anti-interference, and particularly relates to an antenna selection method based on channel factors. The method of the invention provides a simpler antenna selection method suitable for an OSM-MIMO system aiming at the specific structure of the OSM-MIMO system, namely, selecting an antenna with the maximum module value and N after sequencing the module values of the channel coefficients_s1 antenna set carrying bit is formed by the antenna with smaller module value. On one hand, the advantages of the OSM-MIMO system are kept, and meanwhile, the error rate of the system is reduced; on the other hand, compared with other antenna selection methods, the method has extremely low complexity, and therefore, the method can be suitable for large-scale antenna selection.

Description

Antenna selection method based on channel factors

Technical Field

The invention belongs to the technical field of communication anti-interference, in particular to an antenna selection method based on channel factors; more specifically, the present invention relates to mimo (Multiple Input Multiple output) technology, osm (offset spatial modulation) technology, Antenna Selection (Antenna Selection) technology, and the like.

Background

The MIMO technology is a high-speed transmission technology in a wireless environment, and it configures multiple antenna units at a transmitting end and a receiving end, and combines with an advanced space-time coding modulation scheme, and by fully utilizing spatial freedom, it can bring additional diversity, multiplexing and beamforming gains.

The conventional spatial modulation (SM-MIMO) system has many advantages, and its single radio frequency structure makes the overall complexity and hardware cost of the system low, and there is no inter-channel interference during transmission. Then, just because the transmitting end of the SM-MIMO system is equipped with only one rf chain, there is frequent switching between the rf chain and the transmitting antenna when transmitting different signals. Therefore, the switching speed will become one of the bottlenecks of the transmission rate, especially for those communication systems with very high requirements on the data transmission rate. The OSM-MIMO system not only solves the problem that the radio frequency chain in the SM-MIMO system needs to be frequently switched, but also further improves the error rate.

The antenna selection technology can bring considerable performance gain to the traditional SM-MIMO system, and therefore, the antenna selection technology is widely concerned in the research field. The antenna selection technology is applied on the premise that the number of antennas at the transmitting end is larger than that required for actual transmission. Suppose the number of antennas at the transmitting end is N_tIt is necessary to select N_sThe transmitting antennas are used for transmission, and then all antennas share

And (3) a situation. Under the condition that a transmitting terminal acquires Channel State Information (CSI), different criteria can be adopted to select transmitting antennas so as to obtain the error rate of cultivated land.

Fig. 1 is a diagram of a model for applying transmit antenna selection for an OSM-MIMO system. The transmitting terminal utilizes an antenna selection algorithm to select N after acquiring CSI_tSelecting N from root antenna_sRoot transmitting, selected N_sRoot antenna set is T_s. Let the transmitted symbols of the SM system be

Where i denotes the ith antenna transmitting in the SM system,

represents N_sThe ith column of the order identity matrix, which is set to

S e S represents one of an M-phase shift keying (M-PSK) or an M-quadrature amplitude modulation (M-QAM) signal. The OSM-MIMO system will fix the transmitting antenna on the antenna j, which is selected as

Wherein h is_kFor the k-th column of the channel matrix H, after j is determined, x_iAnd the sequence number i is sent to a precoding module, the obtained transmitting signal is

Wherein the normalization factor

Equation (3) represents the RF chain offset to the jth antenna. The receiving end signal can be expressed as

Where n is a noise vector obeying a complex gaussian distribution with a mean of 0 and a variance of 1, and ρ is the transmission power. The receiving end adopts maximum likelihood detection (ML):

disclosure of Invention

The invention aims at solving the problem of how to get from N_tSelecting N from root antenna_sFor an OSM-MIMO system, the upper real-time Bit Error Probability (BEP) bound can be written as:

wherein γ is N_rN_sM is the total number of the transmission modes; n is_neighThe representation results in a transmit vector x_kThe number of misjudged neighbor patterns;

N_e，B(κ-λ)denotes x_kMisjudge as x_λThe number of error bits of (d); p (x)_k→x_λ) Denotes x_kMisjudge as x_λPair-wise error probability (PEP). Wherein the pairwise error probability p (x)_k→x_λ) Can be expressed as:

wherein

It can be seen that the pair-wise error probability and hence the BEP can be reduced by increasing the channel factor β.

The technical scheme of the invention is as follows:

an antenna selection algorithm based on channel factors is used for an OSM-MIMO system and the number of transmitting antennas and receiving antennas is set to be N respectively_tAnd N_rFrom N_tTo select N_sRoot carry bit, let N be in order to maintain single radio frequency structure _r1. the characteristic lies in that the system power factor β is increased so as to reduce the error rate of the system

The method comprises the following steps:

s1, calculating the modulus value of the channel matrix:

assuming a channel matrix of

Each element of the matrix H is a complex Gaussian random variable with the mean value of 0 and the variance of 1, and the modulus of each element is calculated;

s2, sorting the modulus values of the obtained channel elements:

sequencing the obtained channel element modulus values to obtain

Wherein

S3, selecting the sequenced channel elements and the corresponding antennas:

selecting

A corresponding one of the antennas and

corresponding to N _s1 antenna, thereby ensuring that the system power factor β of the system is maximum during transmission so as to reduce the error rate;

the technical scheme of the invention provides a brand-new antenna selection scheme aiming at an OSM-MIMO system in the background technology, namely, an antenna with the maximum module value and N are selected after channel coefficient module values are sequenced_s1 antenna set carrying bit is formed by the antenna with smaller module value.

The invention has the beneficial effects that: on one hand, the advantages of the OSM-MIMO system are kept, and meanwhile, the error rate of the system is reduced; on the other hand, compared with other antenna selection methods, the method has extremely low complexity, and therefore, the method can be suitable for large-scale antenna selection.

Drawings

FIG. 1 is a diagram of an OSM-MIMO system employing a transmit antenna selection model;

FIG. 2 shows bit error rate comparison of three methods under different SNR in the embodiment;

figure 3 comparison of complexity of the invention and EDAS in the examples.

Detailed Description

The technical scheme of the invention is described in detail in the following with reference to the accompanying drawings and embodiments:

in this example, OSM-MIMO System, N_t＝7，N_sThe modulation scheme is 8QAM modulation, 4. It is to be expressly noted that in the following description, a detailed description of known functions and designs may be omitted when it may obscure the subject matter of the present invention.

b is the bit data to be transmitted, and can be regarded as an L × T matrix, where L is log₂(N_sM) 5, T is data length, in this example T10⁵And after 8QAM modulation and spatial modulation are carried out on the data, the data passes through an OSM-MIMO system which has already been subjected to antenna selection, and then error rate statistics is carried out. The method comprises the following specific steps:

step 1: generating L × T bit data, performing 8QAM modulation and spatial modulation on the data to generate N_r×N_tA channel matrix H of x T whose elements are complex gaussian independent random variables whose obedient mean is 0 and variance is 1;

step 2: selecting T times of antennas for H, wherein the specific method comprises sorting the channel coefficient modulus values and selecting the antenna with the maximum modulus value and N _s1 antenna with smaller module value;

and step 3: inputting the modulated bit data into an OSM-MIMO system with antenna selection, and counting the bit error rate for T times;

and 4, step 4: by way of comparison, at N_tRandomly selecting N in root antenna_sRepeating the step 3 by forming an antenna set by the roots to obtain the bit error rate without antenna selection;

and 5: for comparison, the optimal Euclidean distance method (EDAS) was used to pair N_tAnd (4) selecting the root antenna and repeating the step (3) to obtain the error bit rate of the EDAS applied by the OSM-MIMO system.

Step 6: counting floating point numbers (FLOPs) required to be multiplied by the EDAS for one-time selection under the condition to obtain a graph 3;

fig. 2 shows the bit error rate and the bit error rate of the invention compared with the conventional OSM-MIMO and optimal euclidean distance selection method (EDAS), and fig. 3 shows the complexity of EDAS compared with the invention.

Claims (1)

1. An antenna selection method based on channel factor is used for OSM-MIMO system, and the number of transmitting antennas and receiving antennas are respectively N_tAnd N_rFrom N_tTo select N_sRoot bearer send bit, N_r1 is ═ 1; the method is characterized by comprising the following steps:

s1, calculating the modulus value of the channel matrix:

assuming a channel matrix of

Each element of the matrix H is a complex Gaussian random variable with the mean value of 0 and the variance of 1, and the modulus of each element is calculated;

s2, sorting the modulus values of the obtained channel elements:

sequencing the obtained channel element modulus values to obtain

Wherein

S3, selecting the sequenced channel elements and the corresponding antennas:

selecting

A corresponding one of the antennas and

corresponding to N_s-1 antenna constituent antenna set carries transmission bits.

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