CN105634633A - Adaptive multi-branch combined frequency domain detector for underwater acoustic cooperative communication - Google Patents

Abstract

The invention relates to the technical field of underwater acoustic cooperative communication, and particularly relates to an adaptive multi-branch combined frequency domain detector for the underwater acoustic cooperative communication. The adaptive multi-branch combined frequency domain detector is characterized by being provided with a YSD signal branch processor used for processing a YSD signal, a YRD signal branch processor used for processing a YRD signal, an adder and a detecting and decoding module connected with the output of the adder, wherein the YSD signal branch processor is provided with an FFT module, a balance coefficient multiplication module, an FFT inverse transform module and a multiplier, which are connected in sequence. Compared with the prior art, the adaptive multi-branch combined frequency domain detector provided by the invention can adaptively adjust the combination coefficient of the corresponding branch according to the steady state MSE of each branch, and does not need to assume that the channel state information of the nodes is known, so that better performance can be obtained.

Description

Frequency domain detection device is merged for the self adaptation multiple-limb in underwater sound collaboration communication

Technical field:

The present invention paddles sound cooperative communication technology field, a kind of specifically merges frequency domain detection device for the self adaptation multiple-limb in underwater sound collaboration communication.

Background technology:

In recent years, underwater sound communication, as the extremely competitive replacer of one of conventional wireline communication, has caused the extensive concern in subsurface communication field. This is to be caused by growing demand, because underwater sound communication is without cable, therefore not by the restriction of cable length, flexible and convenient to use, it has wide range of applications, the aspect such as including underwater target detection, pollution detection, the long-range monitoring of offshore production platform, seafari, oceanographic data collection, tsunami warning. In order to solve the link reliability problems in underwater sound communication, the latest developments of terrestrial radio Communication Studies, cooperative communication technology has been considered for underwater sound communication.

For underwater sound collaboration communication, the information that source node sends arrives destination node via different paths, a kind of for directly being arrived destination node by source node, and other is forwarded by via node to arrive destination node. Thus, the performance of system will depend in part on the merging treatment technology receiving signal via different paths. Existing merging treatment technology includes equal gain combining and maximum-ratio combing mode. Comparatively speaking, maximum-ratio combing mode can obtain better performance. But, the realization of maximum-ratio combing mode is to assume that each internodal channel condition information is known as premise. For actual underwater sound cooperation communication system, these channel condition informations are difficult to acquisition. Except this hypothesis, underwater acoustic channel has environmental dependence, and the underwater acoustic channel under varying environment is different. Thus due to the difference of environment, channel envelope is also different. And the required Optimum combining coefficient that can obtain optimum bit error rate performance depends on the concrete channel status of respective branch. Therefore, in order to obtain better bit error rate performance, multiple-limb detector needs the concrete channel envelope according to each branch, is adaptively adjusted and merges coefficient accordingly. At present, the research to self-adopt combination technology is also lacked.

Summary of the invention:

The present invention is directed to the shortcoming and defect existed in prior art, proposing a kind of based on the realization of single carrier frequency domain equalization (SC-FDE) system, the self adaptation multiple-limb being used in underwater sound collaboration communication for amplification forwarding underwater sound collaboration communication merges frequency domain detection device.

The present invention can be reached by following measures:

A kind of for the self adaptation multiple-limb merging frequency domain detection device in underwater sound collaboration communication, it is characterised in that to be provided with for Y_SDSignal carries out the Y processed_SDSignal branch processor, for Y_RDSignal carries out the Y processed_RDSignal branch processor, adder and the detection being connected with adder output and decoder module, wherein Y_SDSignal branch processor is provided with and is sequentially connected the FFT module that connects, equalizing coefficient is multiplied module, FFT inverse transform block, multiplier, described Y_SDSignal is multiplied with M equalizing coefficient after FFT resume module, after processing then through FFT inverse transform block, with C_SDIt is multiplied feeding adder through multiplier; Y_SDSignal branch processor is provided with and is sequentially connected the FFT module that connects, equalizing coefficient is multiplied module, FFT inverse transform block, multiplier, described Y_RDSignal is multiplied with M equalizing coefficient after FFT resume module, after processing then through FFT inverse transform block, with C_RDBe multiplied feeding adder through multiplier, the output signal of adder process with decoder module after testing after output data.

The present invention is based on three node underwater sound collaboration communication models, comprise a transmitting node S, an one via node R and destination node D, all nodes are single antenna construction, work in half-duplex transmission pattern, and having identical transmitting average power limit, the forward mode of via node is amplification forwarding;

Cooperation transmission from source node to destination node is divided into two stages, and in the first stage, source node is to destination node and relay node broadcasts signal, and in second stage, the signal received in the first stage is amplified by via node, is then forwarded to destination node;

In the first stage, the signal that relaying and destination node receive can be expressed as

$Y_{SR}=\sqrt{P_s}{h}_{SR}{X}_S+n_{SR}---\left(1\right)$

$Y_{SD}=\sqrt{P_s}{h}_{SD}{X}_S+n_{SD}---\left(2\right)$

Wherein P_SRepresent signal transmitting power, X_SFor the transmission signal of energy normalized, h_SRAnd h_SDRepresent the channel gain of S �� R and S �� D channel, n respectively_SRAnd n_SDRepresent that (average is 0 to corresponding additive white Gaussian noise, and variance is �� respectively²);

In second stage, the reception signal of what destination node received come from relaying is represented by

$Y_{RD}=\sqrt{P_R}{h}_{RD}\left({\mathrm{\β}}_R{Y}_{SR}\right)+n_{RD}---\left(3\right)$

Wherein n_RDFor additive white Gaussian noise, ��_RFor amplification factor, it is given by

${\mathrm{\β}}_R=\sqrt{\frac{1}{|h_{SR}{|}^2{P}_S+{\mathrm{\σ}}^2}}---\left(4\right)$

Wherein h_SRRepresent the fading coefficients of channel, P between source node and via node_SFor signal transmitting power, ��²For the noise power in S �� R channel.

Detector of the present invention is by the Y received_SDAnd Y_RDSignal processes respectively. M tap coefficient of each branch adopts adaptive frequency domain filtering algorithm to be trained adjusting. In the training stage, training sequence is utilized to train, the channel according to each branch, complete the self adaptation work of detector. Then, it is possible to obtain corresponding to the Steady State Square Error (MSE) of each branch. The stable state MSE definition of each branch is given by

${\mathrm{MSE}}_j=E\[|d_n-y_n{|}^2\]=\frac{{\mathrm{\Σ}}_{i=1}^n{e}_i^2}{n}---\left(5\right)$

Wherein, j represents jth branch, j �� { SD, RD}.

The present invention is different from maximum-ratio combing mode, it is in order to obtain merging coefficient, to assume that all internodal channel condition informations are known as premise, the self adaptation multiple-limb that the present invention proposes merges frequency domain equalization detector and is based on the stable state MSE acquisition merging coefficient of each branch, stable state MSE is a critically important index of frequency domain equalization detection performance, its value is more little, then detector just can obtain better performance, on the contrary, if stable state MSE is more big, then detector performance will be more poor, therefore, merge coefficient to draw according to stable state MSE, as follows:

$c_j=\frac{1/{\mathrm{MSE}}_j}{1/{\mathrm{MSE}}_{SD}+1/{\mathrm{MSE}}_{RD}}---\left(6\right)$

Wherein, j represents jth branch, j �� { SD, RD}. By (7) formula it can be seen that it is apparent that stable state MSEMSE_jMore little, then merge coefficient c accordingly_jValue more big. The calculating of this simple formula can realize the weighting to each branch signal and process, the branch that performance is more good, and weight coefficient is more big, otherwise, then more little, thus the performance of detector can be effectively improved. It is noted that the detector carried does not require an assumption that each internodal channel condition information is known, therefore it is more suitable for the underwater sound cooperation communication system of reality.

The present invention compared with prior art, according to the stable state MSE of each branch, can be adaptively adjusted the merging coefficient of respective branch, and not need to assume that each internodal channel condition information is it is known that better performance can be obtained.

Accompanying drawing illustrates:

Accompanying drawing 1 is underwater sound cooperation communication system block diagram in the present invention.

Accompanying drawing 2 is the structured flowchart of the present invention.

Accompanying drawing 3 is the present invention and existing methodical bit error rate performance comparative graph.

Detailed description of the invention:

Below in conjunction with accompanying drawing and simulation result, the present invention is further illustrated.

As shown in accompanying drawing 1 and accompanying drawing 2, modulation system adopts QPSK (QPSK), and all of node assumes there is identical Power Limitation. In emulation, adopting simple three nodal analysis methods, underwater acoustic channel adopts BELLHOP model to produce.

The present invention proposes a kind of for the self adaptation multiple-limb merging frequency domain detection device in underwater sound collaboration communication, it is characterised in that be provided with for Y_SDSignal carries out the Y processed_SDSignal branch processor, for Y_RDSignal carries out the Y processed_RDSignal branch processor, adder and the detection being connected with adder output and decoder module, wherein Y_SDSignal branch processor is provided with and is sequentially connected the FFT module that connects, equalizing coefficient is multiplied module, FFT inverse transform block, multiplier, described Y_SDSignal is multiplied with M equalizing coefficient after FFT resume module, after processing then through FFT inverse transform block, with C_SDIt is multiplied feeding adder through multiplier; Y_SDSignal branch processor is provided with and is sequentially connected the FFT module that connects, equalizing coefficient is multiplied module, FFT inverse transform block, multiplier, described Y_RDSignal is multiplied with M equalizing coefficient after FFT resume module, after processing then through FFT inverse transform block, with C_RDBe multiplied feeding adder through multiplier, the output signal of adder process with decoder module after testing after output data.

Accompanying drawing 3 gives the present invention and compares with existing methodical bit error rate performance. It can be seen that the carried detector of the present invention, equal gain combining and maximum-ratio combing scheme, comparable point-to-point (non-relay node participates in cooperation) scheme obtains better bit error rate performance. This is because these three scheme is under the cooperation of via node, it is possible to obtain diversity gain. From this figure it can be seen that compared with equal gain combining scheme, carried detector and maximum-ratio combing scheme considerably improve bit error rate performance. This is because multiple-limb is merged, merging coefficient is the critically important parameter affecting bit error rate performance, and the merging coefficient that carried detector and maximum-ratio combing scheme use is better than the coefficient of equal gain combining. Further it should be noted that carried detector and maximum-ratio combing scheme achieve close bit error rate performance. But, compared with maximum-ratio combing scheme, at receiving terminal, carried detector scheme need not assume that each internodal channel condition information is known. Therefore, proposed scheme is more suitable for the underwater sound cooperation communication system of reality.

Claims (4)

1. one kind merges frequency domain detection device for the self adaptation multiple-limb in underwater sound collaboration communication, it is characterised in that be provided with for Y_SDSignal carries out the Y processed_SDSignal branch processor, for Y_RDSignal carries out the Y processed_RDSignal branch processor, adder and the detection being connected with adder output and decoder module, wherein Y_SDSignal branch processor is provided with and is sequentially connected the FFT module that connects, equalizing coefficient is multiplied module, FFT inverse transform block, multiplier, described Y_SDSignal is multiplied with M equalizing coefficient after FFT resume module, after processing then through FFT inverse transform block, with C_SDIt is multiplied feeding adder through multiplier; Y_SDSignal branch processor is provided with and is sequentially connected the FFT module that connects, equalizing coefficient is multiplied module, FFT inverse transform block, multiplier, described Y_RDSignal is multiplied with M equalizing coefficient after FFT resume module, after processing then through FFT inverse transform block, with C_RDBe multiplied feeding adder through multiplier, the output signal of adder process with decoder module after testing after output data.

2. according to claim 1 a kind of for the self adaptation multiple-limb merging frequency domain detection device in underwater sound collaboration communication, it is characterised in that

$Y_{SD}=\sqrt{P_s}{h}_{SD}{X}_S+n_{SD}---\left(7\right),$

Wherein P_SRepresent signal transmitting power, X_SFor the transmission signal of energy normalized, h_SRAnd h_SDRepresent the channel gain of S �� R and S �� D channel, n respectively_SRAnd n_SDRepresent that (average is 0 to corresponding additive white Gaussian noise, and variance is �� respectively²),

$Y_{RD}=\sqrt{P_R}{h}_{RD}\left({\mathrm{\β}}_R{Y}_{SR}\right)+n_{RD}$ $\left(8\right)$

Wherein n_RDFor additive white Gaussian noise, ��_RFor amplification factor, it is given by

${\mathrm{\β}}_R=\sqrt{\frac{1}{|h_{SR}{|}^2{P}_S+{\mathrm{\σ}}^2}}---\left(9\right)$

Wherein h_SRRepresent the fading coefficients of channel, P between source node and via node_SFor signal transmitting power, ��²For the noise power in S �� R channel.

3. according to claim 1 a kind of for the self adaptation multiple-limb merging frequency domain detection device in underwater sound collaboration communication, it is characterised in that described detector is by the Y received_SDAnd Y_RDSignal processes respectively, M tap coefficient of each branch adopts adaptive frequency domain filtering algorithm to be trained adjusting, in the training stage, training sequence is utilized to train, channel according to each branch, completes the self adaptation work of detector, then, can obtaining the Steady State Square Error (MSE) corresponding to each branch, the stable state MSE definition of each branch is given by

${\mathrm{MSE}}_j=E\[|d_n-y_n{|}^2\]=\frac{{\mathrm{\Σ}}_{i=1}^n{e}_i^2}{n}---\left(10\right)$

Wherein, j represents jth branch, j �� { SD, RD}.

4. according to claim 1 a kind of for the self adaptation multiple-limb merging frequency domain detection device in underwater sound collaboration communication, it is characterised in that to merge coefficient and draw according to stable state MSE, as follows:

$c_j=\frac{1/{\mathrm{MSE}}_j}{1/{\mathrm{MSE}}_{SD}+1/{\mathrm{MSE}}_{RD}}---\left(11\right)$

Wherein, j represents jth branch, j �� { SD, RD}.