CN102055565A - Space diversity method for physical layer network coding in communication system - Google Patents

Abstract

The invention relates to a space diversity method for physical layer network coding in a communication system, and belongs to the technical field of wireless communication. The method comprises the following steps of: arranging a plurality of distributed relay station antennas between two single antenna users, sending data to a relay station by a user, estimating channel information between the relay station and a user antenna by the relay station, acquiring a channel matrix, selecting a binary phase shift keying modulation mode by the user, sending interactive information among the users to the relay station, performing combined detection on the received superposed signals by the relay station to acquire network coding symbols, selecting an antenna set, performing space-time coding on the network coding symbols, then sending the coded network coding symbols to the user, performing space-time decoding on the space-time coded symbols by the user, and decoding the estimation values of the network coding symbols according to the interactive information to acquire data information of an opposite user. The method improves the frequency spectrum utilization rate and energy utilization efficiency of a bidirectional relay network and remarkably improves the bidirectional communication reliability of the users.

Description

A kind of space diversity method that is used for the communication system physical-layer network coding

Technical field

The present invention relates to a kind of space diversity method that is used for the communication system physical-layer network coding, belong to wireless communication technology field.

Background technology

Two-way communication is the common means in the communication, such as real-time interactive document between the user, and business such as screen conversation, special-purpose supervisory control systems etc. all need reliable two-way communication.Because the interval, geographical position or the channel quality that direct transfers are abominable, expectation realizes user's networking realization reliable communication voluntarily of two-way communication, at this time can utilize relaying to assist to finish two-way communication.Wireless Network Coding is utilized the broadcasting of transmission of wireless signals and superimposed characteristics and advanced signal detecting method, can for these users that expect interactive information to information transmission reliably at a high speed is provided.Simultaneously, the application of Wireless Network Coding can effectively improve the availability of frequency spectrum and the capacity usage ratio of network integral body, thereby realizes two-way communication efficient, environmental protection, meets the demand of following green communications.

At present Wireless Network Coding has received the concern of academia and industrial circle gradually, wherein is applied in physical-layer network coding that Wireless Network Coding in the two-way communication comprises that mainly decoding is transmitted based on part and based on amplifying the analog network coding of transmitting.Wherein, the communication protocol of physical-layer network coding is as follows: the user that two-way communication is carried out in two hope finishes its uplink to utilizing identical running time-frequency resource, the base station end with overlapping or mutually interference signals directly be mapped as the symbol of network code, it is right that symbol after utilizing frequency resource when certain with this network code then is broadcast to this user, the user is after receiving the symbol of network code, after utilizing own existing information to carry out interference eliminated, obtain useful information from the other side.In addition, the communication protocol of analog network coding is as follows: the user that two-way communication is carried out in two hope finishes its uplink to utilizing identical running time-frequency resource, the base station end is with overlapping or to be broadcast to this user after interference signals is directly amplified mutually right, the user is after receiving the symbol of network code, after utilizing own existing information to carry out interference eliminated, obtain useful information from the other side.In two kinds of Wireless Network Coding, physical-layer network coding has higher capacity usage ratio, more meets the demand of future communications.

The signal processing technology that space diversity utilizes many antennas to receive/send out equipment and advanced person is effectively resisted the fading characteristic of wireless channel.Especially, for the relaying auxiliary network, relaying has the more antenna usually and can provide space diversity gain for network.But, utilize many antennas relaying to provide exclusive diversity scheme for physical-layer network coding, still there is not relevant report at present.

Summary of the invention

The objective of the invention is to propose a kind of space diversity method that is used for the communication system physical-layer network coding, to raise the efficiency the availability of frequency spectrum and energy utilization, and utilize many antennas relay nodes to obtain the end-to-end diversity gain of user, improve the reliability of user's two-way communication.

The space diversity method that is used for the communication system physical-layer network coding that the present invention proposes may further comprise the steps:

(1) establishes two single antenna users that carry out the full rate interactive communication, between two single antenna users, set M distributed relay station antenna, constitute a local communication network;

(2) two single antenna users in the local communication network send training data to relay station respectively, relay station is according to the training data that receives, estimate the channel information between relay station antenna and each user antenna respectively, obtain the channel matrix h between user antenna and the relay station antenna _k=[h _{1, k}, h _{2, k}..., h _{M, k}] ^T, k=1 wherein, 2, h _{M, k}It is the channel vector of user k and relaying m root antenna;

(3) two single antenna are with selecting two-phase PSK BPSK modulation system per family, to the relay station interactive information S that to send two length between the single antenna user respectively simultaneously be N signal ₁And S ₂

(4) receive i superposed signal y when relay station from two single antenna users _iAfter, carry out joint-detection, obtain i network code symbol

1≤i≤N, detailed process is as follows:

(4-1) to the channel matrix h of above-mentioned steps (2) _kSuperposed signal y with the relay station reception _iCarry out relevant treatment respectively, obtain two channel-data correlation value, be respectively:

Wherein, () ^*Be conjugate transpose;

(4-2) two single antenna users of above-mentioned steps (2) and two channel matrixes between the relay station are carried out relevant treatment, obtain a channel-channel correlation

(4-3) relay station utilizes above-mentioned two channel-data correlation value and a channel-channel correlation, to superposed signal y _iCarry out high specific and merge detection, obtain the network code symbol

The detection expression formula is:

Wherein

Real is got in expression;

(5) relay station is selected to gather to the antenna that the user sends network code from relay station from M root relay station antenna according to the user antenna of above-mentioned steps (2) and the channel matrix between the relay station antenna, and detailed process is as follows:

(5-1) relay station calculates the instantaneous channel gain that closes of M root antenna respectively, and sorts from big to small by channel gain;

(5-2) relay station is selected from above-mentioned ordering and the antenna of the big corresponding M ' root of channel gain antenna as the transmit network coding;

(6) relay station carries out the network code symbol of above-mentioned steps (4) that sky two the single antenna users of alignment by above-mentioned selection send behind the Space Time Coding;

(7) two single antenna users receive the symbol behind the Space Time Coding respectively, decipher when carrying out sky, obtain i network code symbol

Estimated value

(8) two single antenna users decipher network code sign estimation value respectively according to above-mentioned steps (3) interactive information, obtain the other side's single antenna user's data information.

The space diversity method that is used for the communication system physical-layer network coding that the present invention proposes adopts based on the efficient two-way communication strategy of physical-layer network coding with based on the combined transceiving treatment technology of many antennas relaying.Two-way communication based on physical-layer network coding comprises two transmit stages: the multiple access access phase (Multiple-Access, MA) and the broadcasting stage (Broadcast, BC).Two users that the MA stage is carried out two-way communication by hope are transmitted information simultaneously to relaying, and relaying merges detection (MRC-L) to carry out the physical-layer network coding high specific from the superposed signal of different user, and then directly obtains the network code symbol; In the BC stage, relaying utilizes transmitting antenna to select (AS) and Space Time Coding (STC) with network code symbol broadcasting reuse family, and the user utilizes self information to extract another one user's information after detecting network code.The inventive method has effectively improved the availability of frequency spectrum and the energy utilization efficiency of two-way junction network; Utilize many antennas relay nodes to obtain the end-to-end diversity gain of user, significantly improved the reliability of user's two-way communication.

Description of drawings

Fig. 1 be in the distributing antenna system user to the two-way communication schematic diagram.

Fig. 2 is the sky line options FB(flow block) that the present invention proposes.

Fig. 3 is the FB(flow block) of the inventive method.

Embodiment

The space diversity method that is used for the communication system physical-layer network coding that the present invention proposes, its FB(flow block) may further comprise the steps as shown in Figure 3:

(1) establishes two single antenna users that carry out the full rate interactive communication, between two single antenna users, set M distributed relay station antenna, constitute a communication network.As shown in Figure 1, the half-duplex relay station R that forms of selected single antenna user S_1 that carries out information interaction and S_2 and two spaced antennas together constitutes communication network, M=3.

(2) two single antenna users in the communication network send training data to relay station respectively, relay station is according to the training data that receives, estimate the channel information between relay station antenna and each user antenna respectively, obtain the channel matrix h between user antenna and the relay station antenna _k=[h _{1, k}, h _{2, k}, h _{3, k}] ^T, k=1 wherein, 2, h _{M, k}Be the channel vector of user k and relaying m root antenna, m=1,2,3, establish and obey independent identically distributed 0 average and the distribution of unit variance Ruili, promptly

(3) two single antenna are with selecting two-phase PSK BPSK modulation system per family, to the relay station R interactive information S that to send two length between the single antenna user respectively simultaneously be N signal ₁And S ₂

(4) receive i superposed signal y as relay station R from two single antenna users _i, behind 1≤i≤N, carry out joint-detection, obtain i network code symbol

1≤i≤N, detailed process is as follows:

(4-1) to the channel matrix h of above-mentioned steps (2) _kI superposed signal y with the relay station reception _iCarry out relevant treatment respectively, obtain two channel-data correlation value, be respectively:

() ^*Be conjugate transpose.

I the stack character expression that two users arrive relay station R is:

Wherein, s _{I, k}∈ (± 1) is S _k, k=1, i of 2 sends symbol, n _iBe the independent identically distributed additive white Gaussian noise matrix in relay station R place, promptly E _{B, k}Be the transmitted power of user S_k, we are normalized to E with it for convenience of explanation _{B, k}=E _b=1, therefore, expression formula is reduced to

(4-2) two single antenna users of above-mentioned steps (2) and two channel matrixes between the relay station R are carried out relevant treatment, obtain a channel-channel correlation

(4-3) relay station utilizes above-mentioned two channel-data correlation value and a channel-channel correlation, superposed signal yi is carried out high specific merge detection, obtains the network code symbol

The detection expression formula is:

Wherein

Real is got in expression;

Concrete derivation is as follows:

Detect judgement based on following basic binary system hypothesis testing after the superposed signal that relaying R reception two users S_1 and S_2 send:

H ₀：s _i＝s _i，1s _i，2＝1，

H ₁：s _i＝s _i，1s _i，2＝-1.

Wherein, s _iIt is the network code symbol that the relay station expectation recovers.It is right to introduce check character for ease of mark

Wherein Ω={ ± 1} * { ± 1} is a signal space.Y then _iThe condition joint probability density function be:

$p(y_i/H_0,H)=C_1(e^{-\frac{\mathrm{\Λ}(y_i;\tilde{s}=\left(\mathrm{1,1}\right),H)}{N_0}}+e^{-\frac{\mathrm{\Λ}(y_i;\tilde{s}=(-1,-1),H)}{N_0}}),$

$p(y_i/H_1,H)=C_1(e^{-\frac{\mathrm{\Λ}(y_i;\tilde{s}=(-\mathrm{1,1}),H)}{N_0}}+e^{-\frac{\mathrm{\Λ}(y_i;\tilde{s}=(1,-1),H)}{N_0}}),$

C wherein ₁Be constant, Be to receive waveform y _iWith the check waveform

Distance measure, ‖ ‖ _FIt is the Frobenius norm of vector or matrix.Suppose that information source etc. is general, the maximum-likelihood criterion of physical-layer network coding provides with following form:

$\log p(y_i/H_0,H)\begin{array}{c}\stackrel{{\hat{s}}_i=1}{\&GreaterEqual;}\\ \underset{{\hat{s}}_i=-1}{<}\end{array}\log p(y_i/H_1,H)$

Because logp (y _i/ H ₀, g) and logp (y _i/ H ₁, g) be logarithm-and-index (log-sum-exp) function, it can be approximately

Functional form, the accurate maximum-likelihood criterion that obtains Wireless Network Coding is:

$\min ({\mathrm{\&Lambda;}}_i\left(\mathrm{1,1}\right),{\mathrm{\&Lambda;}}_i(-1,-1))\begin{array}{c}\stackrel{{\hat{s}}_i=1}{\&le;}\\ \underset{{\hat{s}}_i=-1}{>}\end{array}\min ({\mathrm{\&Lambda;}}_i(-\mathrm{1,1}),{\mathrm{\&Lambda;}}_i(1,-1))---\left(1\right)$

Wherein, reduced representation For Launch

Wherein

Be and check character Irrelevant constant.Effectively estimate

Be expressed as

Wherein, Bring formula (2) into formula (1), the physical-layer network coding high specific that obtains under the BPSK modulation merges detection method:

Wherein

For step (4-1), step (4-2) obtain

Three relevant treatment.

(5) relay station is according to the user antenna of above-mentioned steps (2) and the channel matrix between the relay station antenna, from M root relay station antenna, select to send the antenna set of network code to the user from relay station, FB(flow block) as shown in Figure 2, detailed process is as follows:

(5-1) relay station calculates the instantaneous channel gain that closes of three antennas respectively: { g ₁, g ₂, g ₃, and sort from big to small by channel gain and to be { g ₁', g ₂', g ₃';

(5-2) relay station is selected from above-mentioned ordering and big channel gain g ₁' and g ₂' corresponding two antennas are as the antenna of transmit network coding;

(6) relay station R carries out the network code symbol of above-mentioned steps (4) that sky two the single antenna users of alignment by above-mentioned selection send behind the Space Time Coding.When user S_1 and S_2 obtained channel condition information, relay station can be used the quadrature space-time block code OSTBC based on coherent detection, the adjacent networks coded identification that is obtained by (4)

With

Being encoded to block code sends:

$D_i^{\left(\mathrm{OSTBC}\right)}=\left[\begin{array}{cc}{\hat{s}}_{2i-1}& {\hat{s}}_{2i}\\ {\hat{s}}_{2i}& {\hat{s}}_{2i-1}\end{array}\right]$

D wherein _iThe capable vector of m by the m root antenna transmission of relay station R, m=1,2.If user S_1 and S_2 can't obtain channel condition information, relay station R adopts differential space-time block code DSTBC, with adjacent network code symbol is at first in pairs

Be mapped to then

Certain DSTBC code book form and carry the code book C of information _i, wherein the code book of φ is as follows:

$C^{\left(1\right)}=\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right],$ $C^{\left(2\right)}=\left[\begin{array}{cc}0& 1\\ -1& 0\end{array}\right],$

$C^{\left(3\right)}=\left[\begin{array}{cc}-1& 0\\ 0& -1\end{array}\right],$ $C^{\left(4\right)}=\left[\begin{array}{cc}0& -1\\ 1& 0\end{array}\right]$

After the relay station R code book being obtained block sign indicating number through following differential coding sends:

Wherein, the first bulk coding that sends in the formula

Be expressed as:

$D_0^{\left(\mathrm{DSTBC}\right)}=\left[\begin{array}{cc}1& -1\\ -1& 1\end{array}\right];$

(7) two single antenna users receive the symbol behind the Space Time Coding respectively, decipher when carrying out sky, obtain i network code symbol

Estimated value

(8) two single antenna users decipher network code sign estimation value respectively according to above-mentioned steps (3) interactive information, obtain the other side's single antenna user's data information.User S_k is in conjunction with the data message s of self _{I, k}Extract the other user's useful information

And

Claims (1)

1. space diversity method that is used for the communication system physical-layer network coding is characterized in that this method may further comprise the steps:

(1) establishes two single antenna users that carry out the full rate interactive communication, between two single antenna users, set M distributed relay station antenna, constitute a local communication network;

(2) two single antenna users in the local communication network send training data to relay station respectively, relay station is according to the training data that receives, estimate the channel information between relay station antenna and each user antenna respectively, obtain the channel matrix h between user antenna and the relay station antenna _k=[h _{1, k}, h _{2, k}..., h _{M, k}] ^T, k=1 wherein, 2, h _{M, k}It is the channel vector of user k and relaying m root antenna;

(3) two single antenna are with selecting two-phase PSK BPSK modulation system per family, to the relay station interactive information S that to send two length between the single antenna user respectively simultaneously be N signal ₁And S ₂

(4) receive i superposed signal y when relay station from two single antenna users _iAfter, carry out joint-detection, obtain i network code symbol

1≤i≤N, detailed process is as follows:

(4-1) to the channel matrix h of above-mentioned steps (2) _kSuperposed signal y with the relay station reception _iCarry out relevant treatment respectively, obtain two channel-data correlation value, be respectively:

Wherein, () ^*Be conjugate transpose;

(4-2) two single antenna users of above-mentioned steps (2) and two channel matrixes between the relay station are carried out relevant treatment, obtain a channel-channel correlation

(4-3) relay station utilizes above-mentioned two channel-data correlation value and a channel-channel correlation, to superposed signal y _iCarry out high specific and merge detection, obtain the network code symbol

The detection expression formula is:

Wherein

Real is got in expression;

(5) relay station is selected to gather to the antenna that the user sends network code from relay station from M root relay station antenna according to the user antenna of above-mentioned steps (2) and the channel matrix between the relay station antenna, and detailed process is as follows:

(5-1) relay station calculates the instantaneous channel gain that closes of M root antenna respectively, and sorts from big to small by channel gain;

(5-2) relay station is selected from above-mentioned ordering and the antenna of the big corresponding M ' root of channel gain antenna as the transmit network coding;

(6) relay station carries out the network code symbol of above-mentioned steps (4) that sky two the single antenna users of alignment by above-mentioned selection send behind the Space Time Coding;

(7) two single antenna users receive the symbol behind the Space Time Coding respectively, decipher when carrying out sky, obtain i network code symbol

Estimated value

(8) two single antenna users decipher network code sign estimation value respectively according to above-mentioned steps (3) interactive information, obtain the other side's single antenna user's data information.

Images