阅读说明：本技术 一种适用于散射通信的自适应均衡方法 (Self-adaptive equalization method suitable for scatter communication ) 是由 汪李峰 石全旺 董玮 于 2019-10-16 设计创作，主要内容包括：本发明公开了通信领域的一种适用于散射通信的自适应均衡方法,结合信道估计的结果,在不增加系统复杂度的前提下,利用判决反馈均衡器的结构实现线性、非线性两种均衡器,与采用线性均衡的散射系统相比,提高了深度衰落信道下系统的通信能力；与采用判决反馈非线性均衡的散射系统相比,避免了低信噪比下的误码扩散,提高了非深度衰落信道下的通信能力。(The invention discloses a self-adaptive equalization method suitable for scattered communication in the field of communication, which combines the result of channel estimation, realizes two equalizers of linearity and nonlinearity by using the structure of a decision feedback equalizer on the premise of not increasing the complexity of a system, and improves the communication capability of the system under a deep fading channel compared with a scattering system adopting linear equalization; compared with a scattering system adopting decision feedback nonlinear equalization, the method avoids error code diffusion under low signal-to-noise ratio and improves the communication capability under a non-deep fading channel.)

1. An adaptive equalization method for scatter communication, characterized by: combining the result of channel estimation, and on the premise of not increasing the system complexity, the structure of the decision feedback equalizer is used to realize two equalizers, namely a linear equalizer and a nonlinear equalizer, and the method specifically comprises the following steps:

s1: performing channel estimation by using a pilot frequency band in a signal to obtain a channel response h;

s2: transforming h to the frequency domain by using FFT (fast Fourier transform), and judging whether the channel of the current time slot is a frequency domain depth zero channel or not;

s3: the following operation is performed according to the result obtained in step S2:

s3.1: if the channel of the current time slot is the frequency domain depth zero channel, the coefficient { f of the feedforward equalizing filter is calculated by using the channel response h obtained in the step S1_iIn which-K is₁≤i≤0；

S3.2: if the channel of the current time slot is a channel with a flat frequency domain, the coefficient { c ] of the linear equalization filter is calculated by using the channel response h obtained in step S1_iIn which-K is₁≤i≤K₂；

S4: the following operation is performed according to the result obtained in step S2:

s4.1: if the channel of the current time slot is the frequency domain depth zero channel, the coefficient b of the feedback equalization filter is calculated using the channel response h obtained in step S1_iWherein i is more than or equal to 1 and less than or equal to K₂；

S4.2: if the channel of the current time slot is a channel with a flat frequency domain, then { b } is not calculated_i}；

S5: determining equalization filter coefficients:

s5.1: if the channel of the current time slot is a frequency domain depth zero channel, adopting a decision feedback equalizer:

let { x_i}＝{f_i}，-K₁≤i≤0；

Let { y_i}＝{b_i}，1≤i≤K₂；

Let { z_k}＝{I_k}，

s5.2: if the channel of the current time slot is a channel with a flat frequency domain, a linear equalizer is adopted:

let { x_i}＝{c_i}，-K₁≤i≤0；

Let { y_i}＝{c_i}，1≤i≤K₂；

Let { z_k}＝{v_k}，{v_kIs the received signal sequence;

s6: determining equalization filter coefficients: and (3) balanced filtering:

Technical Field

The invention relates to the technical field of communication, in particular to a self-adaptive equalization method suitable for scattered communication.

Background

Because a large number of scatterers with different sizes exist in the scattering common body, each scatterer is a secondary radiation wave source and radiates electromagnetic waves to the periphery, and thus multipath propagation is caused. In the time domain, the signals sent out at the same time are changed into a plurality of components which arrive at receiving points in different order, so that the signals are spread into a piece in time, and the received waveform is distorted; in the frequency domain, it is manifested as frequency selective fading, that is, if the delay difference of each path is large, and the frequency spectrum of the transmission waveform is wide, the channel affects the strength and phase of different frequency components in the transmission signal differently.

The equalization technology is one of the main methods for resisting the multipath effect, and currently, a single equalization method, namely time domain linear equalization, frequency domain linear equalization or time domain decision feedback nonlinear equalization, is adopted in the domestic scattered communication system.

Path components of scattering channel signals are quite large, amplitude and phase of a total signal can be greatly changed by changing amplitude or phase of a certain path, and experiments prove that frequency domain flat channels and frequency domain depth zero channels in a scattering communication environment are likely to occur. The linear equalization technology adopted by the prior scattering system can not be well adapted to a frequency domain depth zero channel due to the enhancement of noise power, and the performance of time domain decision feedback nonlinear equalization can not be guaranteed due to the fact that error code propagation exists when the signal to noise ratio is low, so that the working threshold is higher than the linear equalization when the channel environment is good.

Based on this, the invention designs a self-adaptive equalization method suitable for scattered communication, which integrates the advantages of a channel and a linear and decision feedback nonlinear equalizer, and obtains a flat receiving frequency response and a linear phase as much as possible at a receiving end so as to adapt to the diversity of scattered channels, thereby solving the problems mentioned above.

Disclosure of Invention

The invention aims to provide a self-adaptive equalization method suitable for scattered communication, which selects a proper equalization algorithm according to a channel estimation result, and solves the problem that a scattered communication system cannot give consideration to multiple channel environments due to the adoption of a single equalization algorithm on the premise of not increasing the complexity of the system.

In order to achieve the purpose, the invention provides the following technical scheme: a self-adaptive equalization method suitable for scattered communication combines the result of channel estimation, and realizes linear and nonlinear equalizers by using the structure of a decision feedback equalizer on the premise of not increasing the complexity of a system, and specifically comprises the following steps:

s1: performing channel estimation by using a pilot frequency band in a signal to obtain a channel response h;

s2: transforming h to the frequency domain by using FFT (fast Fourier transform), and judging whether the channel of the current time slot is a frequency domain depth zero channel or not;

s3: the following operation is performed according to the result obtained in step S2:

S3.1: if the channel of the current time slot is the frequency domain depth zero channel, the coefficient { f of the feedforward equalizing filter is calculated by using the channel response h obtained in the step S1_iIn which-K is₁≤i≤0；

S3.2: if the channel of the current time slot is a channel with a flat frequency domain, the coefficient { c ] of the linear equalization filter is calculated by using the channel response h obtained in step S1_iIn which-K is₁≤i≤K₂；

S4: the following operation is performed according to the result obtained in step S2:

s4.1: if the channel of the current time slot is the frequency domain depth zero channel, the coefficient b of the feedback equalization filter is calculated using the channel response h obtained in step S1_iWherein i is more than or equal to 1 and less than or equal to K₂；

S4.2: if the channel of the current time slot is a channel with a flat frequency domain, then { b } is not calculated_i}；

S5: determining equalization filter coefficients:

s5.1: if the channel of the current time slot is a frequency domain depth zero channel, adopting a decision feedback equalizer:

let { x_i}＝{f_i}，-K₁≤i≤0；

Let { y_i}＝{b_i}，1≤i≤K₂；

Let { z_k}＝{I_k}，

Is a previously detected symbol;

s5.2: if the channel of the current time slot is a channel with a flat frequency domain, a linear equalizer is adopted:

let { x_i}＝{c_i}，-K₁≤i≤0；

Let { y_i}＝{c_i}，1≤i≤K₂；

Let { z_k}＝{v_k}，{v_kIs the received signal sequence;

s6: determining equalization filter coefficients: and (3) balanced filtering:

is an estimate of the kth information symbol.

Compared with the prior art, the invention has the beneficial effects that: the self-adaptive equalization method suitable for the scattering communication selects a proper equalization algorithm by using the result of channel estimation on the premise of not increasing the complexity of a system, and has the following advantages:

1. compared with a scattering system adopting linear equalization, the communication capacity of the system under a deep fading channel is improved;

2. compared with a scattering system adopting decision feedback nonlinear equalization, the method avoids error code diffusion under low signal-to-noise ratio and improves the communication capability under a non-deep fading channel.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a technical scheme that: a self-adaptive equalization method suitable for scattered communication combines the result of channel estimation, and realizes linear and nonlinear equalizers by using the structure of a decision feedback equalizer on the premise of not increasing the complexity of a system, and specifically comprises the following steps:

s1: performing channel estimation by using a pilot frequency band in a signal to obtain a channel response h;

s2: transforming h to the frequency domain by using FFT (fast Fourier transform), and judging whether the channel of the current time slot is a frequency domain depth zero channel or not;

s3: the following operation is performed according to the result obtained in step S2:

s3.1: if the channel of the current time slot is a frequency domain depth zero channel, utilizingThe channel response h obtained in step S1 is used to calculate the coefficient { f ] of the feedforward equalization filter_iIn which-K is₁≤i≤0；

S3.2: if the channel of the current time slot is a channel with a flat frequency domain, the coefficient { c ] of the linear equalization filter is calculated by using the channel response h obtained in step S1_iIn which-K is₁≤i≤K₂；

S4: the following operation is performed according to the result obtained in step S2:

s4.1: if the channel of the current time slot is the frequency domain depth zero channel, the coefficient b of the feedback equalization filter is calculated using the channel response h obtained in step S1_iWherein i is more than or equal to 1 and less than or equal to K₂；

S4.2: if the channel of the current time slot is a channel with a flat frequency domain, then { b } is not calculated_i}；

S5: determining equalization filter coefficients:

s5.1: if the channel of the current time slot is a frequency domain depth zero channel, adopting a decision feedback equalizer:

let { x_i}＝{f_i}，-K₁≤i≤0；

Let { y_i}＝{b_i}，1≤i≤K₂；

Let { z_k}＝{I_k}，Is a previously detected symbol;

s5.2: if the channel of the current time slot is a channel with a flat frequency domain, a linear equalizer is adopted:

let { x_i}＝{c_i}，-K₁≤i≤0；

Let { y_i}＝{c_i}，1≤i≤K₂；

Let { z_k}＝{v_k}，{v_kIs the received signal sequence;

s6: determining equalization filter coefficients: and (3) balanced filtering:

is an estimate of the kth information symbol.

Wherein the content of the first and second substances,

1. the linear equalization part can adopt a time domain equalization algorithm or a frequency domain equalization algorithm, and can be specifically selected according to the waveform and the system requirements;

2. the linear equalization filtering can adopt a minimum mean square error equalization algorithm or a zero-forcing equalization algorithm;

3. the channel estimation is not limited to a method utilizing pilot frequency, and can be combined with an actual waveform adjusting algorithm;

4. the method for judging the channel characteristics and the threshold can be adjusted according to the actually adopted channel estimation algorithm and equalization algorithm.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.