CN103152311B - Based on the wireless communications method of the physical-layer network coding communication system power distributing technique of OFDM - Google Patents

Abstract

Based on the wireless communications method of the physical-layer network coding communication system power distributing technique of OFDM, relate to the communications field.The invention solves the problem that the wireless communications method throughput of existing physically based deformation layer network navamander is little.Wireless communications method of the present invention divides two time slots to carry out, first time slot carries out constellation mapping to the data of two information source node to input, power division, Fast Fourier Transform Inverse, add Cyclic Prefix and send to via node, via node carries out removal Cyclic Prefix to the mixed signal received, fast Fourier transform, judgement maps and obtains broadcast data, second time slot via node carries out constellation mapping to broadcast data, power division, Fast Fourier Transform Inverse, add Cyclic Prefix and acquisition signal is broadcasted away, two information source node receive broadcast singal and carry out removal Cyclic Prefix, fast Fourier transform, demappings etc. have operated between two information source node and have communicated.The present invention is applicable to radio communication.

Description

Based on the wireless communications method of the physical-layer network coding communication system power distributing technique of OFDM

Technical field

The present invention relates to the communications field, be specifically related to a kind of wireless communications method of physical-layer network coding communication system power distributing technique.

Background technology

Along with the arrival of information age, people have higher requirement to radio honeycomb communication system.User wishes that system both can provide high-speed data transmission service for the mobile terminal of Intra-cell, also can ensure the service quality of cell-edge terminals, and wherein, wireless relay transmission system is current important research direction.Wireless relay becomes multi-hop transmission by defeated for the jump set between base station and mobile terminal, reduces the transmitting power in wireless transmission, effectively improves systematic function, particularly improve the service quality of Cell Edge User.

Two-way relay model is as the typical wireless relay mode of one, and be a simplification of actual relay model, it also can be employed for actual cellular cell system.Two-way relay model comprises via node, the first information source node and the second information source node, and two-way relay model as shown in Figure 1.First information source node and the second information source node need exchange message, but do not have communication link between them.Information source node must complete whole communication process by via node.Due to hardware constraints, in model, each node can only work in half-duplex state, if directly do not communicated by other technologies, real system throughput is lower.For tdd systems (Time Division Duplexing, TDD), whole information exchanging process needs 4 time slots.At first time slot, its data is sent to via node by the first information source node; At second time slot, via node is by the data retransmission of the first information source node that receives before to the second information source node, and the data of the first information source node have been delivered to the second information source node in two time slots.In like manner, the second information source node also needs to transfer data to the first information source node in two time slots, and the exchange process of whole information consumes 4 time slots.

In order to improve throughput and the availability of frequency spectrum of system, network coding technique is introduced in two-way relay model.By network code, information exchange only needs 3 time slots just can complete.Subsequently, some are for wireless both-way trunk model, propose physical layer network coding technique (Physical layer network coding, PNC).Physical layer network coding technique takes full advantage of the interference signal of information source, can realize information exchange in two time slots.In first time slot, two information sources send data to relaying simultaneously, and the mixed signal received processes by relaying, then in second time slot, is broadcast to information source node.Information source node obtains the transmission data of the other side's information source node according to the broadcast singal received and the transmission data of self.Physical-layer network coding greatly improves the throughput of system.

Physical-layer network coding has two kinds of different working strategies: amplification forwarding strategy (Amplify-and-Forward, AF) and decoding forwarding strategy (Decode-and-Forward, DF).If adopt amplification forwarding strategy, via node only need simply amplify the mixed signal received and broadcast, and the signal transacting of all complexity all completes at information source end; Forwarding strategy of decoding then requires via node to adjudicate fully and the mixed signal received of decoding.Decoding forwarding strategy avoids the amplification of noise and adds up, and therefore can obtain systematic function better.Certainly, decoding forwarding strategy requires that relaying also has certain signal to carry out disposal ability, and thus its system complexity is relatively high.

Consider that multipath channel can produce a very large impact high-speed radiocommunication system, OFDM (Orthogonal Frequency Division Multiplexing, OFDM) has been incorporated in physical-layer network coding communication system.The introducing of OFDM can enhance the robustness of system, effectively eliminates multi-path jamming.This system is called as the physical-layer network coding communication system based on OFDM.Some scholars, round the physical-layer network coding communication system based on OFDM, has made a large amount of work, and one of them focus is the power division of system.But existing power distribution algorithm, or do not realize the optimization of the overall situation, otherwise the bit error rate performance that improve system but reduces volumetric properties, and the throughput of system cannot be made to be maximized.

Summary of the invention

The present invention, in order to the little problem of the wireless communications method throughput that solves existing physically based deformation layer network navamander, proposes the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM.

Based on the wireless communications method of the physical-layer network coding communication system power distributing technique of OFDM, the information source node in the method and via node all use N _cindividual subcarrier communicates, and communication channel is fiat multipath fading channel, channel multi-path number to be L, L be more than or equal to 1 integer, the time delay between adjacent two footpaths is a symbol period; Channel coefficients remains unchanged in two time slots of frequency division orthogonal multiplex-physical-layer network coding communication; N _cfor positive integer;

Wireless communications method under the first time slot:

Step one, the first information source node are to the binary data D of input ₁n () carries out serioparallel exchange, obtain the N of the first information source node _cchannel parallel data;

Second information source node is to the binary data D of input ₂n () carries out serioparallel exchange, obtain the N of the second information source node _cchannel parallel data;

Step 2, the first information source node are to the N obtained _cchannel parallel data carries out constellation mapping respectively, and the first information source node obtains N _croad frequency domain constellation symbol signal;

Second information source node is to the N obtained _cchannel parallel data carries out constellation mapping, and the second information source node obtains N _croad frequency domain constellation symbol signal;

Step 3, the N that the first information source node is obtained _croad frequency domain constellation symbol signal carries out power division, and the first information source node obtains N _csignal after the power division of road,

To the N that the second information source node obtains _croad frequency domain constellation symbol signal carries out power division, and the second information source node obtains N _csignal after the power division of road,

Step 4, the first information source node are to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, and the first information source node obtains N _croad time domain orthogonal frequency-division multiplex singal,

Second information source node is to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, and the second information source node obtains N _croad time domain orthogonal frequency-division multiplex singal;

Step 5, the N that the first information source node is obtained _croad time domain orthogonal frequency-division multiplex singal carries out parallel-serial conversion respectively, obtains serial time domain orthogonal frequency-division multiplex singal s ₁(t),

To the N that the second information source node obtains _croad time domain orthogonal frequency-division multiplex singal carries out parallel-serial conversion respectively, obtains serial time domain orthogonal frequency-division multiplex singal s ₂(t);

Step 6, the serial time domain orthogonal frequency-division multiplex singal s obtained to the first information source node ₁t () adds Cyclic Prefix, and be sent to via node continue adding the time domain orthogonal frequency-division multiplex singal channel after Cyclic Prefix node,

To the time domain orthogonal frequency-division multiplex singal s of the serial that the second information source node obtains ₂t () adds Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after adding Cyclic Prefix is sent to via node;

Time domain orthogonal frequency-division multiplex singal after time domain orthogonal frequency-division multiplex singal after the interpolation Cyclic Prefix of described first information source node and the interpolation Cyclic Prefix of the second information source node is sent simultaneously to via node, forms mixed signal at via node receiving terminal;

Step 7, the via node mixed signal from channel described in receiving step six, carries out removal circulation prefix processing to the mixed signal obtained, and obtains the mixed signal after removing Cyclic Prefix;

Step 8, carrying out serioparallel exchange to removing the mixed signal after Cyclic Prefix, obtaining N _croad walks abreast mixed signal;

Step 9, to obtain N _cthe road mixed signal that walks abreast carries out fast Fourier transform simultaneously, obtains N _croad frequency-region signal;

Step 10, via node utilize the N obtained _croad frequency-region signal, the judgement mapping rule according to presetting obtains broadcast data D _rn (), completes the radio communication under the first time slot;

Wireless communications method under the second time slot:

The broadcast data D that step 11, via node are obtained step 10 _rn () carries out serioparallel exchange, obtain N _croad broadcast in parallel data;

Step 12, via node are to the N obtained _croad broadcast in parallel data carry out constellation mapping respectively, obtain N _cfrequency domain symbol signal after the constellation mapping of road;

Step 13, via node are to the N obtained _cfrequency domain symbol signal after the constellation mapping of road carries out power division respectively, obtains N _csignal after the power division of road;

Step 14, via node are to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, obtains N _croad time-domain signal;

Step 15, to obtain N _croad time-domain signal carries out parallel-serial conversion, then adds Cyclic Prefix to the time-domain signal after parallel-serial conversion, and then the time-domain signal after interpolation Cyclic Prefix is broadcasted away by via node;

After step 10 six, first information source node receives the broadcast singal of via node, removal Cyclic Prefix is carried out to broadcast singal, obtain the signal r after removing prefix ₁(t),

After second information source node receives the broadcast singal of via node, removal Cyclic Prefix is carried out to broadcast singal, obtain the signal r after removing prefix ₂(t);

Step 10 seven, first information source node is to the signal r after the removal prefix obtained ₁t () carries out serioparallel exchange, obtain N _croad parallel signal, to the N obtained _cparallel signal carries out N simultaneously _cpoint quick Fourier converts, and the first information source node obtains N _croad frequency-region signal,

Second information source node is to the signal r after the removal prefix obtained ₂t () carries out serioparallel exchange, obtain N _croad parallel signal, to the N obtained _croad parallel signal carries out N simultaneously _cpoint quick Fourier converts, and the second information source node obtains N _croad frequency-region signal;

Step 10 eight, first information source node is to the N obtained _croad frequency-region signal is adjudicated respectively, and the first information source node obtains N _ccircuit-switched data,

Second information source node is to the N obtained _croad frequency-region signal is adjudicated respectively, and the second information source node obtains N _ccircuit-switched data;

Step 10 nine, the N that the first information source node in step 10 eight is obtained _ccircuit-switched data carries out demapping, and the first information source node obtains N _ccircuit-switched data D ₂(n),

To the N that the second information source node in step 10 eight obtains _ccircuit-switched data carries out demapping, and the second information source node obtains N _ccircuit-switched data D ₁n (), completes a radio communication between the first information source node and the second information source node.

The present invention is directed to the physical-layer network coding communication system of OFDM, a kind of power distribution method is proposed, the method is under the prerequisite of overall system power limited, power control and power division are carried out to the information source node of system and each subcarrier of via node, the throughput of whole system is greatly improved, adopt the throughput of the method for the invention communication system to improve 2 times compared with the throughput of traditional communication system, improve 1.5 times compared with the throughput of existing network code network communicating system.

Accompanying drawing explanation

Fig. 1 is the physical-layer network coding communication system schematic diagram based on two-way relay model,

In figure solid line represent the signalling of time slot one to; Dotted line represent meaning time slot two signalling to.

Fig. 2 is the inventive method the 1st time slot signal process schematic diagram.

Fig. 3 is the inventive method the 2nd time slot signal process schematic diagram.

Fig. 4 is the signal to noise ratio-throughput simulation result schematic diagram adopting the method for the invention and one-way junction communication system, in figure, the curve with symbol " ◆ " represents that the physical-layer network coding communication system based on OFDM adopting the method for the invention obtains signal to noise ratio-throughput curve;

Curve with symbol " ◇ " represents that the physical-layer network coding communication system based on OFDM not adopting the method for the invention obtains signal to noise ratio-throughput curve;

Curve with symbol " ▲ " represents the signal to noise ratio-throughput curve adopting the one-way junction system of power distribution method to obtain

Curve with symbol " △ " represents the signal to noise ratio-throughput curve not adopting the one-way junction system of power distribution method to obtain.

Fig. 5 be the method for the invention when multipath channel number is 8 and 16 with signal to noise ratio-throughput simulation result schematic diagram of not adopting the method for the invention when multipath channel number is 8 and 16, in figure

Curve with symbol " ◆ " represents that employing the method for the invention obtains signal to noise ratio-throughput curve when multipath channel number is 8;

Curve with symbol " ◇ " represents and does not adopt the method for the invention to obtain signal to noise ratio-throughput curve when multipath channel number is 8;

Curve with symbol "●" represents that employing the method for the invention obtains signal to noise ratio-throughput curve when multipath channel number is 16;

Curve with symbol "○" represents and does not adopt the method for the invention to obtain signal to noise ratio-throughput curve when multipath channel number is 8.

Embodiment

Embodiment one, composition graphs 2, Fig. 3 illustrates present embodiment, the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM described in present embodiment, the information source node in the method and via node all use N _cindividual subcarrier communicates, and communication channel is fiat multipath fading channel, channel multi-path number to be L, L be more than or equal to 1 integer, the time delay between adjacent two footpaths is a symbol period; Channel coefficients remains unchanged in two time slots of frequency division orthogonal multiplex-physical-layer network coding communication; N _cfor positive integer;

Channel between information source node one and via node is expressed as

$h_1\left(t\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_{1,l}\mathrm{\δ}(t-l)$

Wherein, h ₁, _lthe channel coefficients of l paths between the first information source node and via node, t=0 ~ Nc-1; As L=1, channel is single footpath fading channel;

The frequency-domain expression of the channel between the first information source node and via node is

$H_1\left(n\right)=\frac{1}{\sqrt{N_c}}\underset{t=0}{\overset{N_c-1}{\mathrm{\Σ}}}{h}_{1,l}\exp \left\{\frac{2\mathrm{\πnt}}{N_c}\right\}$

Wherein, 0≤n≤N _c-1; Channel between second information source node and via node is expressed as

$h_2\left(t\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_{2,l}\mathrm{\δ}(t-l)$

Wherein h ₂, _lit is the channel coefficients of l paths between the second information source node and via node;

The frequency-domain expression of channel is

$H_2\left(n\right)=\frac{1}{\sqrt{N_c}}\underset{t=0}{\overset{N_c-1}{\mathrm{\Σ}}}{h}_{2,l}\exp \left\{\frac{2\mathrm{\πnt}}{N_c}\right\}$

Concrete steps:

Wireless communications method under the first time slot:

Step one, the first information source node are to the binary data D of input ₁n () carries out serioparallel exchange, obtain the N of the first information source node _cchannel parallel data;

Second information source node is to the binary data D of input ₂n () carries out serioparallel exchange, obtain the N of the second information source node _cchannel parallel data;

Step 2, the first information source node are to the N obtained _cchannel parallel data carries out constellation mapping respectively, and the first information source node obtains N _croad frequency domain constellation symbol signal;

Second information source node is to the N obtained _cchannel parallel data carries out constellation mapping, and the second information source node obtains N _croad frequency domain constellation symbol signal;

Step 3, the N that the first information source node is obtained _croad frequency domain constellation symbol signal carries out power division, and the first information source node obtains N _csignal after the power division of road, after the power division that the first information source node obtains, the concrete form of signal is:

$S_1\left(n\right)=\sqrt{P_1\left(n\right)}{X}_1\left(n\right)$

Wherein, S ₁n () is signal after the n-th tunnel power division of the first information source node acquisition, X ₁n () is the n-th road frequency domain constellation symbol signal that the first information source node obtains, P ₁n () is the power that the first information source node distributes to the n-th subcarriers;

To the N that the second information source node obtains _croad frequency domain constellation symbol signal carries out power division, and the second information source node obtains N _csignal after the power division of road, after the power division that the first information source node obtains, the concrete form of signal is:

$S_2\left(n\right)=\sqrt{P_2\left(n\right)}{X}_2\left(n\right)$

Wherein, S ₂n () is signal after the n-th tunnel power division of the first information source node acquisition, X ₂(n) be second information source node obtain the n-th road frequency domain constellation symbol signal wherein, P ₂n () is the power that the first information source node distributes to the n-th subcarriers;

Step 4, the first information source node are to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, and the first information source node obtains N _croad time domain orthogonal frequency-division multiplex singal,

Second information source node is to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, and the second information source node obtains N _croad time domain orthogonal frequency-division multiplex singal;

Step 5, the N that the first information source node is obtained _croad time domain orthogonal frequency-division multiplex singal carries out parallel-serial conversion respectively, obtains serial time domain orthogonal frequency-division multiplex singal s ₁(t),

To the N that the second information source node obtains _croad time domain orthogonal frequency-division multiplex singal carries out parallel-serial conversion respectively, obtains serial time domain orthogonal frequency-division multiplex singal s ₂(t);

Step 6, the serial time domain orthogonal frequency-division multiplex singal s obtained to the first information source node ₁t () adds Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after adding Cyclic Prefix is sent to via node,

To the time domain orthogonal frequency-division multiplex singal s of the serial that the second information source node obtains ₂t () adds Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after adding Cyclic Prefix is sent to via node;

Time domain orthogonal frequency-division multiplex singal after time domain orthogonal frequency-division multiplex singal after the interpolation Cyclic Prefix of described first information source node and the interpolation Cyclic Prefix of the second information source node is sent simultaneously to via node, forms mixed signal at via node receiving terminal;

Step 7, the via node mixed signal from channel described in receiving step six, carries out removal circulation prefix processing to the mixed signal obtained, and obtains the mixed signal after removing Cyclic Prefix;

Step 8, carrying out serioparallel exchange to removing the mixed signal after Cyclic Prefix, obtaining N _croad walks abreast mixed signal;

Step 9, to obtain N _cthe road mixed signal that walks abreast carries out fast Fourier transform simultaneously, obtains N _croad frequency-region signal;

Step 10, via node utilize the N obtained _croad frequency-region signal, the judgement mapping rule according to presetting obtains broadcast data D _rn (), completes the radio communication under the first time slot;

Wireless communications method under the second time slot:

The broadcast data D that step 11, via node are obtained step 10 _rn () carries out serioparallel exchange, obtain N _croad broadcast in parallel data;

Step 12, via node are to the N obtained _croad broadcast in parallel data carry out constellation mapping respectively, obtain N _cfrequency domain symbol signal after the constellation mapping of road;

Step 13, via node are to the N obtained _cfrequency domain symbol signal after the constellation mapping of road carries out power division respectively, obtains N _csignal after the power division of road;

After the n-th tunnel power division that via node obtains, the concrete representation of signal is

$S_R\left(n\right)=\sqrt{P_R\left(n\right)}{X}_R\left(n\right)$

Wherein, S _rsignal after n the n-th tunnel power division that () obtains for via node, X _rn () is the frequency domain symbol signal after the n-th tunnel constellation mapping, P _rn () distributes to the power of the n-th subcarriers for via node;

Step 14, via node are to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, obtains N _croad time-domain signal;

Step 15, to obtain N _croad time-domain signal carries out parallel-serial conversion, then adds Cyclic Prefix to the time-domain signal after parallel-serial conversion, and then the time-domain signal after interpolation Cyclic Prefix is broadcasted away by via node;

After step 10 six, first information source node receives the broadcast singal of via node, removal Cyclic Prefix is carried out to broadcast singal, obtain the signal r after removing prefix ₁t (), removes the signal r after prefix ₁t () is by formula:

r ₁(t)＝h ₁(t)*s _R(t)+n ₁(t)

Obtain, in formula, n ₁t () is the first information source node end noise;

After second information source node receives the broadcast singal of via node, removal Cyclic Prefix is carried out to broadcast singal, obtain the signal r after removing prefix ₂(t); Remove the signal r after prefix ₂t () is by formula:

r ₂(t)＝h ₂(t)*s _R(t)+n ₂(t)

Obtain, in formula, n ₂t () is the second information source node end noise;

Step 10 seven, first information source node is to the signal r after the removal prefix obtained ₁t () carries out serioparallel exchange, obtain N _croad parallel signal, to the N obtained _cparallel signal carries out N simultaneously _cpoint quick Fourier converts, and the first information source node obtains N _croad frequency-region signal,

Second information source node is to the signal r after the removal prefix obtained ₂t () carries out serioparallel exchange, obtain N _croad parallel signal, to the N obtained _croad parallel signal carries out N simultaneously _cpoint quick Fourier converts, and the second information source node obtains N _croad frequency-region signal;

Step 10 eight, first information source node is to the N obtained _croad frequency-region signal is adjudicated respectively, and the first information source node obtains N _ccircuit-switched data,

Second information source node is to the N obtained _croad frequency-region signal is adjudicated respectively, and the second information source node obtains N _ccircuit-switched data;

Step 10 nine, the N that the first information source node in step 10 eight is obtained _ccircuit-switched data carries out demapping, and the first information source node obtains N _ccircuit-switched data D ₂(n),

To the N that the second information source node in step 10 eight obtains _ccircuit-switched data carries out demapping, and the second information source node obtains N _ccircuit-switched data D ₁n (), completes a radio communication between the first information source node and the second information source node.

The maximum throughput R that system obtains _sumby formula:

$R_{\mathrm{sum}}=\frac{1}{2}\underset{n=0}{\overset{N_c-1}{\mathrm{\Σ}}}{\log }_2(1+\frac{P_{\mathrm{tot}}\left(n\right){\left|H_1\left(n\right)H_2\left(n\right)\right|}^2}{{\mathrm{\σ}}^2(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)});$

Realize, in formula, σ ²for noise variance, R _sumunit be bps/transmission unit, R _sumrelevant with the sub-carrier number of system, as the N of system _cwhen determining, to R _sumoptimization problem be equivalent to sub-carrier average size R _aveoptimization, R _aveby formula

$R_{\mathrm{ave}}=\frac{1}{2N_c}\underset{n=0}{\overset{N_c-1}{\mathrm{\Σ}}}{\log }_2(1+\frac{P_{\mathrm{tot}}\left(n\right){\left|H_1\left(n\right)H_2\left(n\right)\right|}^2}{{\mathrm{\σ}}^2(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)})$

Realize.

First information source node of method described in present embodiment and the second information source node need the exchange being carried out information by via node, tdd systems, and whole communication process can complete in two time slots.First time slot, two information source node carry out power division to the transmission signal on respective each subcarrier respectively, then signal are sent to via node simultaneously; Via node receives mixed signal, then demodulation, maps out broadcast singal; At second time slot, via node carries out power division to the transmission signal on respective each subcarrier, then signal is broadcast to each information source node, and information source node, according to the broadcast singal received, can obtain the information of other information source node.

Present embodiment is under the prerequisite of overall system power limited, carries out power control and power division to each subcarrier of system information source node and via node, to realize the throughput-maximized of whole system.The present invention is applicable to fiat multipath fading channel, smooth single footpath fading channel and Gaussian channel.

At multipath number L=8, sub-carrier number N _cunder the condition of=256, the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM of the present invention is emulated, as shown in Figure 4, the wireless communications method adopted based on the physical-layer network coding communication system power distributing technique of OFDM and the signal to noise ratio-throughput curve comparison diagram of the physical-layer network coding communication system based on OFDM not adopting the method for the invention is given.The present invention effectively raises the throughput of the physical-layer network coding communication system based on OFDM as seen from Figure 4.Being it can also be seen that by Fig. 4 adopts the system of the method for the invention to provide higher system subcarrier average size than OFDM-one-way junction system, this is because physical-layer network coding system can complete exchanges data in two time slots, and one-way junction needs 4 time slots.Adopt the method for the invention better than adopting the optimal algorithm of one-way junction to the raising of throughput performance simultaneously.With R _ave=1 bps/transmission unit is example, now adopts method proposed by the invention to improve about 2dB than the throughput performance of traditional communication method, and adopt the optimal algorithm system of one-way junction improve about 1dB than the throughput performance of traditional communication method.

Under the condition of multipath number L=16 and L=8, the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM of the present invention is also emulated simultaneously, compare as shown in Figure 5 multipath number different when, adopt the throughput performance of system of the method for the invention.Can find out, during L=16, the Performance Ratio L=8 of the throughput of system is better, and all than not adopting this law to illustrate, the throughput performance that the communication means of described method obtains is better, this is because multipath number is more, system obtainable point of stage gain is larger.

Embodiment two, present embodiment are further illustrating the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM described in embodiment one, obtain N described in step 3 to the first information source node and the second information source node _cthe method that road frequency domain constellation symbol signal carries out power division is:

Steps A 1, obtain channel information by channel estimating;

Steps A 2, according to water filling theorem, calculate system assignment to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and;

Steps A 3, the channel information obtained according to steps A 1, and the system assignment that calculates of steps A 2 give the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and, to the N of the first information source node and the second information source node _croad frequency domain constellation symbol signal carries out power division; Wherein, 0≤n≤N _c-1.

Embodiment three, present embodiment are further illustrating the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM described in embodiment one, and via node described in step 13 is to the N obtained _cthe method that frequency domain symbol signal after the constellation mapping of road carries out power division is respectively:

Step B1, obtain channel information by channel estimating;

Step B2, to calculate according to water filling theorem system assignment to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and;

Step B3, the channel information obtained according to step B1, and the system assignment that obtains of step B2 to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and, power division is carried out to via node; Wherein, 0≤n≤N _c-1.

Embodiment four, present embodiment are further illustrating the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM described in embodiment two, the channel information obtained according to steps A 1 described in steps A 3, and the system assignment that obtains of steps A 2 to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and, to the N of the first information source node and the second information source node _cthe concrete grammar that road frequency domain constellation symbol signal carries out power division is:

When | H ₁(n) | > | H ₂(n) | time, P ₁(n) and P ₂n () is according to formula:

$\left\{\begin{array}{c}{P}_1\left(n\right)=\frac{{\left|H_2\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\\ P_2\left(n\right)=\frac{{\left|H_1\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\end{array}\right.;$

Obtain;

When | H ₁(n) |≤| H ₂(n) | time, P ₁(n) and P ₂n () is according to formula:

$\left\{\begin{array}{c}{P}_1\left(n\right)=\frac{{\left|H_2\left(n\right)\right|}^2}{({\left|H_1\left(n\right)\right|}^2+{2\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\\ P_2\left(n\right)=\frac{{\left|H_1\left(n\right)\right|}^2}{({\left|H_1\left(n\right)\right|}^2+{2\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\end{array}\right.$

Obtain, in formula: P ₁n () is the power distributing to the n-th road frequency domain constellation symbol signal in the first information source node; P ₂n () is the power distributing to the n-th road frequency domain constellation symbol signal in the second information source node; H ₁(n) and H ₂n frequency domain form that () is channel, P _tot(n) for system assignment give the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n subcarrier and system assignment to the power of a via node n subcarrier and:

P _tot(n)＝P ₁(n)+P ₂(n)+P _R(n)；

According to water filling theorem, calculate P _totn the value of () is:

Wherein: ${\left|\tilde{H}\left(n\right)\right|}^2=\frac{{\left|H_1\left(n\right)H_2\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}$

In formula, σ ²for the variance of white Gaussian noise; K is the water line factor, works as P _sumwhen being the gross power of system, by power limitation condition:

$\underset{n=0}{\overset{N_c-1}{\mathrm{\Σ}}}{P}_{\mathrm{tot}}\left(n\right)=P_{\mathrm{sum}}$

Obtain water line factor K.

Embodiment five, present embodiment are further illustrating the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM described in embodiment three, the channel information obtained according to step one described in step B3, calculates the power P that via node distributes to the signal of the n-th subcarrier _rn the value of () passes through formula:

$P_R\left(n\right)=\frac{|{H_1\left(n\right)|}^2}{\left(2\right|{H_1\left(n\right)|}^2+\left|{H_2\left(n\right)|}^2\right)}{P}_{\mathrm{tot}}\left(n\right)$

Obtain.

Embodiment six, present embodiment are further illustrating the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM described in embodiment one, and the first information source node described in step 10 nine utilizes self input data D ₁n N that () and step are obtained _ccircuit-switched data, carries out demapping, obtains the input data D of the first information source node ₂(n), by formula:

$D_2\left(n\right)=D_R\left(n\right)\⊕D_1\left(n\right)$

Realize;

Second information source node utilizes self input data D ₂n n circuit-switched data that () and step are obtained, carries out demapping, obtains the input data D of the first information source node ₁(n), by formula:

$D_1\left(n\right)=D_R\left(n\right)\⊕D_2\left(n\right)$

Realize.

Claims (5)

1., based on the wireless communications method of the physical-layer network coding communication system power distributing technique of OFDM, it is characterized in that, the information source node in the method and via node all use N _cindividual subcarrier communicates, and communication channel is fiat multipath fading channel, channel multi-path number to be L, L be more than or equal to 1 integer, the time delay between adjacent two footpaths is a symbol period; Channel coefficients remains unchanged in two time slots of frequency division orthogonal multiplex-physical-layer network coding communication; N _cfor positive integer;

Wireless communications method under the first time slot:

Step one, the first information source node are to the binary data D of input ₁n () carries out serioparallel exchange, obtain the N of the first information source node _cchannel parallel data; Wherein, n represents the n-th subcarrier, 0≤n≤N _c-1;

Second information source node is to the binary data D of input ₂n () carries out serioparallel exchange, obtain the N of the second information source node _cchannel parallel data;

Step 2, the first information source node are to the N obtained _cchannel parallel data carries out constellation mapping respectively, and the first information source node obtains N _croad frequency domain constellation symbol signal;

Second information source node is to the N obtained _cchannel parallel data carries out constellation mapping, and the second information source node obtains N _croad frequency domain constellation symbol signal;

Step 3, the N that the first information source node is obtained _croad frequency domain constellation symbol signal carries out power division, and the first information source node obtains N _csignal after the power division of road,

To the N that the second information source node obtains _croad frequency domain constellation symbol signal carries out power division, and the second information source node obtains N _csignal after the power division of road,

Step 4, the first information source node are to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, and the first information source node obtains N _croad time domain orthogonal frequency-division multiplex singal,

Second information source node is to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, and the second information source node obtains N _croad time domain orthogonal frequency-division multiplex singal;

Step 5, the N that the first information source node is obtained _croad time domain orthogonal frequency-division multiplex singal carries out parallel-serial conversion respectively, obtains serial time domain orthogonal frequency-division multiplex singal s ₁(t),

To the N that the second information source node obtains _croad time domain orthogonal frequency-division multiplex singal carries out parallel-serial conversion respectively, obtains serial time domain orthogonal frequency-division multiplex singal s ₂(t);

Step 6, the serial time domain orthogonal frequency-division multiplex singal s obtained to the first information source node ₁t () adds Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal after adding Cyclic Prefix is sent to channel,

To the time domain orthogonal frequency-division multiplex singal s of the serial that the second information source node obtains ₂t () adds Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal after adding Cyclic Prefix is sent to channel;

Time domain orthogonal frequency-division multiplex singal after the interpolation Cyclic Prefix that time domain orthogonal frequency-division multiplex singal after the interpolation Cyclic Prefix that described first information source node sends and the second information source node send forms mixed signal in the channel;

Step 7, the via node mixed signal from channel described in receiving step six, carries out removal circulation prefix processing to the mixed signal obtained, and obtains the mixed signal after removing Cyclic Prefix;

Step 8, carrying out serioparallel exchange to removing the mixed signal after Cyclic Prefix, obtaining N _croad walks abreast mixed signal;

Step 9, to obtain N _cthe road mixed signal that walks abreast carries out fast Fourier transform simultaneously, obtains N _croad frequency-region signal;

Step 10, via node utilize the N obtained _croad frequency-region signal, the judgement mapping rule according to presetting obtains broadcast data D _rn (), completes the radio communication under the first time slot;

Wireless communications method under the second time slot:

The broadcast data D that step 11, via node are obtained step 10 _rn () carries out serioparallel exchange, obtain N _croad broadcast in parallel data;

Step 12, via node are to the N obtained _croad broadcast in parallel data carry out constellation mapping respectively, obtain N _cfrequency domain symbol signal after the constellation mapping of road;

Step 13, via node are to the N obtained _cfrequency domain symbol signal after the constellation mapping of road carries out power division respectively, obtains N _csignal after the power division of road;

Step 14, via node are to the N obtained _cafter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, obtains N _croad time-domain signal;

Step 15, to obtain N _croad time-domain signal carries out parallel-serial conversion, then adds Cyclic Prefix to the time-domain signal after parallel-serial conversion, and then the time-domain signal after interpolation Cyclic Prefix is broadcasted away by via node;

After step 10 six, first information source node receives the broadcast singal of via node, removal Cyclic Prefix is carried out to broadcast singal, obtain the signal r after removing prefix ₁(t),

After second information source node receives the broadcast singal of via node, removal Cyclic Prefix is carried out to broadcast singal, obtain the signal r after removing prefix ₂(t);

Step 10 seven, first information source node is to the signal r after the removal prefix obtained ₁t () carries out serioparallel exchange, obtain N _croad parallel signal, to the N obtained _cparallel signal carries out N simultaneously _cpoint quick Fourier converts, and the first information source node obtains N _croad frequency-region signal,

Second information source node is to the signal r after the removal prefix obtained ₂t () carries out serioparallel exchange, obtain N _croad parallel signal, to the N obtained _croad parallel signal carries out N simultaneously _cpoint quick Fourier converts, and the second information source node obtains N _croad frequency-region signal;

Step 10 eight, first information source node is to the N obtained _croad frequency-region signal is adjudicated respectively, and the first information source node obtains N _ccircuit-switched data,

Second information source node is to the N obtained _croad frequency-region signal is adjudicated respectively, and the second information source node obtains N _ccircuit-switched data;

Step 10 nine, the N that the first information source node in step 10 eight is obtained _ccircuit-switched data carries out demapping, and the first information source node obtains N _ccircuit-switched data D ₂(n),

To the N that the second information source node in step 10 eight obtains _ccircuit-switched data carries out demapping, and the second information source node obtains N _ccircuit-switched data D ₁n (), completes a radio communication between the first information source node and the second information source node.

2. the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM according to claim 1, is characterized in that, obtains N described in step 3 to the first information source node and the second information source node _cthe method that road frequency domain constellation symbol signal carries out power division is:

Steps A 1, obtain channel information by channel estimating;

Steps A 2, to calculate according to water filling theorem system assignment to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and;

Steps A 3, the channel information obtained according to steps A 1, and the system assignment that calculates of steps A 2 give the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and, to the N of the first information source node and the second information source node _croad frequency domain constellation symbol signal carries out power division.

3. the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM according to claim 1, is characterized in that, via node described in step 13 is to the N obtained _cthe method that frequency domain symbol signal after the constellation mapping of road carries out power division is respectively:

Step B1, obtain channel information by channel estimating;

Step B2, to calculate according to water filling theorem system assignment to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and;

Step B3, the channel information obtained according to step B1, and the system assignment that obtains of step B2 to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and, power division is carried out to via node; Wherein, 0≤n≤N _c-1.

4. the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM according to claim 2, it is characterized in that, the channel information obtained according to steps A 1 described in steps A 3, and the system assignment that obtains of steps A 2 to the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n-th subcarrier and system assignment to the power of a via node n subcarrier and, to the N of the first information source node and the second information source node _cthe concrete grammar that road frequency domain constellation symbol signal carries out power division is:

When | H ₁(n) | >|H ₂(n) | time, P ₁(n) and P ₂n () is according to formula:

$\left\{\begin{array}{c}{P}_1\left(n\right)=\frac{{\left|H_2\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\\ P_2\left(n\right)=\frac{{\left|H_1\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\end{array}\right.;$

Obtain;

When | H ₁(n) |≤| H ₂(n) | time, P ₁(n) and P ₂n () is according to formula:

$\left\{\begin{array}{c}{P}_1\left(n\right)=\frac{{\left|H_2\left(n\right)\right|}^2}{({\left|H_1\left(n\right)\right|}^2+{2\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\\ P_2\left(n\right)=\frac{{\left|H_1\left(n\right)\right|}^2}{({\left|H_1\left(n\right)\right|}^2+2{\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)\end{array}\right.$

Obtain, in formula: P ₁n () is the power distributing to the n-th road frequency domain constellation symbol signal in the first information source node; P ₂n () is the power distributing to the n-th road frequency domain constellation symbol signal in the second information source node; H ₁(n) and H ₂n frequency domain form that () is channel, P _tot(n) for system assignment give the power of the first information source node n-th subcarrier, system assignment to the power of the second information source node n subcarrier and system assignment to the power of a via node n subcarrier and:

P _tot(n)＝P ₁(n)+P ₂(n)+P _R(n)；

According to water filling theorem, calculate P _totn the value of () is:

Wherein: ${\left|\tilde{H}\left(n\right)\right|}^2=\frac{{\left|H_1\left(n\right)H_2\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}$

In formula, σ ²for the variance of white Gaussian noise; K is the water line factor, works as P _sumwhen being the gross power of system, by power limitation condition:

$\underset{n=0}{\overset{N_c-1}{\mathrm{\Σ}}}{P}_{\mathrm{tot}}\left(n\right)=P_{\mathrm{sum}}$

Obtain water line factor K.

5. the wireless communications method of the physical-layer network coding communication system power distributing technique based on OFDM according to claim 3, it is characterized in that, the channel information obtained according to step one described in step B3, calculates the power P that via node distributes to the signal of the n-th subcarrier _rn the value of () passes through formula:

$P_R\left(n\right)=\frac{{\left|H_1\left(n\right)\right|}^2}{(2{\left|H_1\left(n\right)\right|}^2+{\left|H_2\left(n\right)\right|}^2)}{P}_{\mathrm{tot}}\left(n\right)$

Obtain.