CN103152311A - Wireless communication method based on orthogonal frequency division multiplexing physical layer network encoding communication system power distribution technology - Google Patents

Abstract

The invention provides a wireless communication method based on an orthogonal frequency division multiplexing physical layer network encoding communication system power distribution technology, relates to the field of communication, and solves the problem that the existing wireless communication method based on the physical layer network encoding communication system is small in throughout capacity. The wireless communication method is carried out through two timeslots: in the first timeslot, constellation mapping is carried out for the data input by two signal source node pairs; power is distributed, inverse fast Fourier transform is carried out, a cyclic prefix is added to send to a relay node, the relay node performs cyclic prefix removing for the received mixed signal, fast Fourier transform is carried out, the mapping is judged to obtain broadcast data; and in the second timeslot, the relay node performs constellation mapping for the broadcast data, power is distributed, inverse fast Fourier transform is carried out, a cyclic prefix is added and the obtained signal is broadcast, the two signal source nodes receive the broadcast signal to perform cyclic prefix removing, fast Fourier transform is carried out, and operations such as demapping are carried out to finish communication between the two signal source nodes. The wireless communication method provided by the invention is suitable for wireless communication.

Description

Wireless communications method based on 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.The user wishes that system both can provide high-speed data transmission service for the mobile terminal of inside, residential quarter, also can guarantee the service quality of cell edge terminal, and wherein, the wireless relay transmission system is present important research direction.Wireless relay has reduced the transmitting power in the wireless transmission with the defeated multi-hop transmission that become of the jump set between base station and mobile terminal, has effectively improved systematic function, has particularly improved the service quality of Cell Edge User.

The bi-directional relaying model as a kind of typical wireless relay mode, is a simplification of actual relay model, and it also can be applied to actual cellular cell system.The bi-directional relaying model comprises via node, the first information source node and the second information source node, and the bi-directional relaying model as shown in Figure 1.The first information source node and the second information source node need exchange message, yet there is no communication link between them.Information source node must be completed whole communication process by via node.Due to hardware constraints, in model, each node can only work in the half-duplex state, if directly do not communicate by other technologies, the real system throughput is lower.Take tdd systems (Time Division Duplexing, TDD) as example, whole information exchanging process needs 4 time slots.At first time slot, the first information source node sends to via node with its data; At second time slot, the data retransmission of the first information source node that via node will receive before is 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 need to transfer data to the first information source node in two time slots, and the exchange process of whole information has consumed 4 time slots.

For the throughput and the availability of frequency spectrum that improve system, network coding technique is introduced in the bi-directional relaying model.By network code, information exchange only needs 3 time slots just can complete.Subsequently, some have proposed physical layer network coding technique (Physical layer network coding, PNC) for the wireless both-way trunk model.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 relaying is processed the mixed signal that receives, and then in second time slot, it is broadcast to information source node.Information source node is obtained the transmission data of the other side's information source node according to the broadcast singal that receives 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 the amplification forwarding strategy, via node only needs the mixed signal that receives is simply amplified and broadcasted, and all complicated signals are processed and all completed at the information source end; The mixed signal that the decoding forwarding strategy requires via node to adjudicate fully and decode and receive.The decoding forwarding strategy has been avoided the amplification of noise and has been added up, and therefore can obtain systematic function better.Certainly, the decoding forwarding strategy requires relaying also to have certain signal to carry out disposal ability, thereby 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 the physical-layer network coding communication system.The introducing of OFDM can strengthen the robustness of system, effectively eliminates multipath and disturbs.This system is called as the physical-layer network coding communication system based on OFDM.Some scholars has been made a large amount of work round the physical-layer network coding communication system based on OFDM, and one of them focus is the power division of system.Yet existing power distribution algorithm, or do not realize overall optimization, otherwise the bit error rate performance that has improved system has but reduced volumetric properties, and the throughput of system is maximized.

Summary of the invention

The present invention is existing based on the little problem of the wireless communications method throughput of physical-layer network coding communication system in order to solve, and has proposed the wireless communications method based on the physical-layer network coding communication system power distributing technique of 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 smooth multidiameter fading channel, and the channel multi-path number is L, and L is the integer more than or equal to 1, and 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 _cBe positive integer;

Wireless communications method under the first time slot:

Step 1, the binary data D of the first information source node to inputting ₁(n) go here and there and change, obtaining the N of the first information source node _cChannel parallel data;

The binary data D of the second information source node to input ₂(n) go here and there and change, obtaining the N of the second information source node _cChannel parallel data;

Step 2, the N of the first information source node to obtaining _cChannel parallel data carries out respectively constellation mapping, and the first information source node obtains N _cRoad frequency domain constellation symbol signal;

The N of the second information source node to obtaining _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,

N to the second information source node acquisition _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 N of the first information source node to obtaining _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,

The N of the second information source node to obtaining _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 respectively parallel-serial conversion, obtains serial time domain orthogonal frequency-division multiplex singal s ₁(t),

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

Step 6, the serial time domain orthogonal frequency-division multiplex singal s that obtains for the first information source node ₁(t) add Cyclic Prefix, and be sent to the via node node that continues with adding time domain orthogonal frequency-division multiplex singal channel after Cyclic Prefix,

Give the time domain orthogonal frequency-division multiplex singal s of the serial of the second information source node acquisition ₂(t) add Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after the interpolation 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 the first information source node and the interpolation Cyclic Prefix of the second information source node is sent to via node simultaneously, forms mixed signal at the via node receiving terminal;

Step 7, via node be the described mixed signal of receiving step six from channel, and the mixed signal that obtains is removed circulation prefix processing, and the mixed signal after Cyclic Prefix is removed in acquisition;

Step 8, the mixed signal of removing after Cyclic Prefix gone here and there and changed, obtaining N _cThe road mixed signal that walks abreast;

Step 9, the N to obtaining _cThe parallel mixed signal in road is carried out fast Fourier transform simultaneously, obtains N _cThe road frequency-region signal;

The N that step 10, via node utilization obtain _cThe road frequency-region signal is obtained broadcast data D according to default judgement mapping rule _R(n), complete 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 _R(n) go here and there and change, obtaining N _CThe road broadcast data that walks abreast;

Step 12, the N of via node to obtaining _cThe parallel broadcast data in road carries out respectively constellation mapping, obtains N _cFrequency domain symbol signal after the constellation mapping of road;

Step 13, the N of via node to obtaining _CFrequency domain symbol signal after the constellation mapping of road carries out respectively power division, obtains N _cSignal after the power division of road;

Step 14, the N of via node to obtaining _cAfter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, obtains N _cThe road time-domain signal;

Step 15, the N to obtaining _cThe road time-domain signal carries out parallel-serial conversion, then the time-domain signal after parallel-serial conversion is added Cyclic Prefix, and then via node is broadcasted away the time-domain signal that adds after Cyclic Prefix;

After step 10 six, the first information source node receive the broadcast singal of via node, broadcast singal is removed Cyclic Prefix, the signal r after prefix is removed in acquisition ₁(t),

The second information source node is removed Cyclic Prefix to broadcast singal after receiving the broadcast singal of via node, and the signal r after prefix is removed in acquisition ₂(t);

Step 10 seven, the first information source node signal r after to the removal prefix that obtains ₁(t) go here and there and change, obtaining N _cThe road parallel signal is to the N that obtains _cParallel signal carries out N simultaneously _cThe point quick Fourier conversion, the first information source node obtains N _cThe road frequency-region signal,

The signal r of the second information source node after to the removal prefix that obtains ₂(t) go here and there and change, obtaining N _cThe road parallel signal is to the N that obtains _cThe road parallel signal carries out N simultaneously _cThe point quick Fourier conversion, the second information source node obtains N _cThe road frequency-region signal;

Step 10 eight, the N of the first information source node to obtaining _cThe road frequency-region signal is adjudicated respectively, and the first information source node obtains N _cCircuit-switched data,

The N of the second information source node to obtaining _cThe road 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 is separated mapping, and the first information source node obtains N _cCircuit-switched data D ₂(n),

N to the second information source node acquisition in step 10 eight _cCircuit-switched data is separated mapping, and the second information source node obtains N _cCircuit-switched data D ₁(n), complete 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, the information source node of system and each subcarrier of via node are carried out power control and power division, make the throughput of whole system be greatly improved, the throughput of employing the method for the invention communication system is compared with the throughput of traditional communication system and has been improved 2 times, compares with the throughput of existing network code network communicating system and has improved 1.5 times.

Description of drawings

Fig. 1 is the physical-layer network coding communication system schematic diagram based on the bi-directional relaying model,

The signalling that in figure, solid line represents time slot one to; Dotted line represent to anticipate time slot two signalling to.

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

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

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

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

Signal to noise ratio-the throughput curve that represents to adopt the one-way junction system of power distribution method to obtain with the curve of symbol " ▲ "

Signal to noise ratio-the throughput curve that represents not adopt the one-way junction system of power distribution method to obtain with the curve of symbol " △ ".

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

Representing to adopt the method for the invention with the curve of symbol " ◆ " is to obtain signal to noise ratio-throughput curve at 8 o'clock at the multipath channel number;

Representing not adopt the method for the invention with the curve of symbol " ◇ " is to obtain signal to noise ratio-throughput curve at 8 o'clock at the multipath channel number;

Representing to adopt the method for the invention with the curve of symbol "●" is to obtain signal to noise ratio-throughput curve at 16 o'clock at the multipath channel number;

Representing not adopt the method for the invention with the curve of symbol " zero " is to obtain signal to noise ratio-throughput curve at 8 o'clock at the multipath channel number.

Embodiment

Embodiment one, in conjunction with Fig. 2, Fig. 3 illustrates present embodiment, the wireless communications method of the described physical-layer network coding communication system power distributing technique based on OFDM of present embodiment, the information source node in the method and via node all use N _cIndividual subcarrier communicates, and communication channel is smooth multidiameter fading channel, and the channel multi-path number is L, and L is the integer more than or equal to 1, and 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 _cBe positive integer;

Channel table between information source node one and via node is shown

$h_1\left(t\right)=\underset{l=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA00002924127500031.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,l}\mathrm{\&delta;}(t-l)$

Wherein, h ₁, _lThe channel coefficients of l paths between the first information source node and via node, t=0～Nc-1; When 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

$H_1\left(n\right)=\frac{1}{\sqrt{N_c}}\underset{t=0}{\overset{N_c-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA00002924127500031.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,l}\exp \left\{\frac{2\mathrm{\&pi;nt}}{N_c}\right\}$

Wherein, 0≤n≤N _c-1; Channel table between the second information source node and via node is shown

$h_2\left(t\right)=\underset{l=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002924127500041.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,l}\mathrm{\&delta;}(t-l)$

H wherein 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

$H_2\left(n\right)=\frac{1}{\sqrt{N_c}}\underset{t=0}{\overset{N_c-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002924127500041.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,l}\exp \left\{\frac{2\mathrm{\&pi;nt}}{N_c}\right\}$

Concrete steps:

Wireless communications method under the first time slot:

Step 1, the binary data D of the first information source node to inputting ₁(n) go here and there and change, obtaining the N of the first information source node _cChannel parallel data;

The binary data D of the second information source node to input ₂(n) go here and there and change, obtaining the N of the second information source node _cChannel parallel data;

Step 2, the N of the first information source node to obtaining _cChannel parallel data carries out respectively constellation mapping, and the first information source node obtains N _cRoad frequency domain constellation symbol signal;

The N of the second information source node to obtaining _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 ₁(n) be signal after the n road power division that obtains of the first information source node, X ₁(n) be the n road frequency domain constellation symbol signal that the first information source node obtains, P ₁(n) be the power that the first information source node is distributed to n way carrier wave;

N to the second information source node acquisition _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 ₂(n) be signal after the n road power division that obtains of the first information source node, X ₂(n) be the n road frequency domain constellation symbol signal that obtains of the second information source node wherein, P ₂(n) be the power that the first information source node is distributed to n way carrier wave;

Step 4, the N of the first information source node to obtaining _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,

The N of the second information source node to obtaining _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 respectively parallel-serial conversion, obtains serial time domain orthogonal frequency-division multiplex singal s ₁(t),

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

Step 6, the serial time domain orthogonal frequency-division multiplex singal s that obtains for the first information source node ₁(t) add Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after the interpolation Cyclic Prefix be sent to via node,

Give the time domain orthogonal frequency-division multiplex singal s of the serial of the second information source node acquisition ₂(t) add Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after the interpolation 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 the first information source node and the interpolation Cyclic Prefix of the second information source node is sent to via node simultaneously, forms mixed signal at the via node receiving terminal;

Step 7, via node be the described mixed signal of receiving step six from channel, and the mixed signal that obtains is removed circulation prefix processing, and the mixed signal after Cyclic Prefix is removed in acquisition;

Step 8, the mixed signal of removing after Cyclic Prefix gone here and there and changed, obtaining N _cThe road mixed signal that walks abreast;

Step 9, the N to obtaining _cThe parallel mixed signal in road is carried out fast Fourier transform simultaneously, obtains N _cThe road frequency-region signal;

The N that step 10, via node utilization obtain _cThe road frequency-region signal is obtained broadcast data D according to default judgement mapping rule _R(n), complete 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 _R(n) go here and there and change, obtaining N _cThe road broadcast data that walks abreast;

Step 12, the N of via node to obtaining _cThe parallel broadcast data in road carries out respectively constellation mapping, obtains N _cFrequency domain symbol signal after the constellation mapping of road;

Step 13, the N of via node to obtaining _cFrequency domain symbol signal after the constellation mapping of road carries out respectively power division, obtains N _cSignal after the power division of road;

After the power division of via node obtains n road, the concrete representation of signal is

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

Wherein, S _R(n) signal after the n road power division that obtains for via node, X _R(n) be frequency domain symbol signal after the constellation mapping of n road, P _R(n) distribute to the power of n way carrier wave for via node;

Step 14, the N of via node to obtaining _cAfter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, obtains N _cThe road time-domain signal;

Step 15, the N to obtaining _cThe road time-domain signal carries out parallel-serial conversion, then the time-domain signal after parallel-serial conversion is added Cyclic Prefix, and then via node is broadcasted away the time-domain signal that adds after Cyclic Prefix;

After step 10 six, the first information source node receive the broadcast singal of via node, broadcast singal is removed Cyclic Prefix, the signal r after prefix is removed in acquisition ₁(t), the signal r after the removal prefix ₁(t) by formula:

r ₁(t)＝h ₁(t)*s _R(t)+n ₁(t)

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

The second information source node is removed Cyclic Prefix to broadcast singal after receiving the broadcast singal of via node, and the signal r after prefix is removed in acquisition ₂(t); Signal r after the removal prefix ₂(t) by formula:

r ₂(t)＝h ₂(t)*s _R(t)+n ₂(t)

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

Step 10 seven, the first information source node signal r after to the removal prefix that obtains ₁(t) go here and there and change, obtaining N _cThe road parallel signal is to the N that obtains _cParallel signal carries out N simultaneously _cThe point quick Fourier conversion, the first information source node obtains N _cThe road frequency-region signal,

The signal r of the second information source node after to the removal prefix that obtains ₂(t) go here and there and change, obtaining N _cThe road parallel signal is to the N that obtains _cThe road parallel signal carries out N simultaneously _cThe point quick Fourier conversion, the second information source node obtains N _cThe road frequency-region signal;

Step 10 eight, the N of the first information source node to obtaining _cThe road frequency-region signal is adjudicated respectively, and the first information source node obtains N _cCircuit-switched data,

The N of the second information source node to obtaining _cThe road 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 is separated mapping, and the first information source node obtains N _cCircuit-switched data D ₂(n),

N to the second information source node acquisition in step 10 eight _cCircuit-switched data is separated mapping, and the second information source node obtains N _cCircuit-switched data D ₁(n), complete a radio communication between the first information source node and the second information source node.

The maximum throughput R that system obtains _sumBy formula:

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

Realize, in formula, σ ²Be noise variance, R _sumUnit be bps/transmission unit, R _sumRelevant with the sub-carrier number of system, the N when system _cWhen determining, to R _sumThe optimization problem equivalence be to subcarrier average size R _aveOptimization, R _aveBy formula

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

Realize.

The first information source node of the described method of present embodiment and the second information source node need to be carried out the exchange of information by via node, tdd systems, and whole communication process can be completed in two time slots.First time slot, two information source node carry out power division to the transmitted signal on each subcarrier separately 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 transmitted signal on each subcarrier separately, then signal is broadcast to each information source node, and information source node can be obtained the information of other information source node according to the broadcast singal that receives.

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

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

Simultaneously the wireless communications method to the physical-layer network coding communication system power distributing technique based on OFDM of the present invention has also carried out emulation under the condition of multipath quantity L=16 and L=8, compared as shown in Figure 5 in the different situation of multipath number, adopted the throughput performance of the 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 better than the throughput performance of the communication means acquisition of not adopting the described method of this law explanation, and this is that system's stage gain in obtainable minute is larger because the multipath number is more.

Embodiment two, present embodiment are to the further illustrating of the wireless communications method of the described physical-layer network coding communication system power distributing technique based on OFDM of embodiment one, and described in step 3, the first information source node and the second information source node are obtained N _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 the water filling theorem, calculate system assignment give the power of n subcarrier of the first information source node, system assignment to n subcarrier of the second information source node power and system assignment to the power of a via node n subcarrier and;

Steps A 3, the channel information that obtains according to steps A 1, and the system assignment that calculates of steps A 2 power, system assignment of giving n subcarrier of the first information source node to the power of n subcarrier of the second information source node 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 to the further illustrating of the wireless communications method of the described physical-layer network coding communication system power distributing technique based on OFDM of embodiment one, the N of via node described in step 13 to obtaining _cThe method that frequency domain symbol signal after the constellation mapping of road carries out respectively power division is:

Step B1, obtain channel information by channel estimating;

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

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

Embodiment four, present embodiment are further illustrating the wireless communications method of the described physical-layer network coding communication system power distributing technique based on OFDM of embodiment two, the described channel information that obtains according to steps A 1 of steps A 3, and the system assignment that obtains of steps A 2 to the power of n subcarrier of the first information source node, system assignment to the power of n subcarrier of the second information source node 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) | the time, P ₁(n) and P ₂(n) 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) | the time, P ₁(n) and P ₂(n) 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 ₁(n) be the power of distributing to n road frequency domain constellation symbol signal in the first information source node; P ₂(n) be the power of distributing to n road frequency domain constellation symbol signal in the second information source node; H ₁(n) and H ₂(n) be the frequency domain form of channel, P _tot(n) power, system assignment of giving n subcarrier of the first information source node for system assignment to the power of second an 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 the water filling theorem, calculate P _tot(n) value 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 ²Variance for white Gaussian noise; K is the water line factor, works as P _sumWhen being the gross power of system, by the Power Limitation condition:

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

Obtain the water line factor K.

Embodiment five, present embodiment are further illustrating the wireless communications method of the described physical-layer network coding communication system power distributing technique based on OFDM of embodiment three, the described channel information that obtains according to step 1 of step B3 calculates the power P that via node is distributed to the signal of n subcarrier _R(n) value is passed 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 that described the first information source node of step 10 nine is utilized the input data D of self to the further illustrating of the wireless communications method of the described physical-layer network coding communication system power distributing technique based on OFDM of embodiment one ₁(n) and the N that obtains of step _cCircuit-switched data is separated mapping, obtains the input data D of the first information source node ₂(n), by formula:

$D_2\left(n\right)=D_R\left(n\right)\&CirclePlus;D_1\left(n\right)$

Realize;

The second information source node is utilized the input data D of self ₂(n) and the n circuit-switched data obtained of step, separate mapping, obtain the input data D of the first information source node ₁(n), by formula:

$D_1\left(n\right)=D_R\left(n\right)\&CirclePlus;D_2\left(n\right)$

Realize.

Claims (6)

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 smooth multidiameter fading channel, and the channel multi-path number is L, and L is the integer more than or equal to 1, and 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 _cBe positive integer;

Wireless communications method under the first time slot:

Step 1, the binary data D of the first information source node to inputting ₁(n) go here and there and change, obtaining the N of the first information source node _cChannel parallel data;

The binary data D of the second information source node to input ₂(n) go here and there and change, obtaining the N of the second information source node _cChannel parallel data;

Step 2, the N of the first information source node to obtaining _cChannel parallel data carries out respectively constellation mapping, and the first information source node obtains N _cRoad frequency domain constellation symbol signal;

The N of the second information source node to obtaining _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,

N to the second information source node acquisition _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 N of the first information source node to obtaining _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,

The N of the second information source node to obtaining _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 respectively parallel-serial conversion, obtains serial time domain orthogonal frequency-division multiplex singal s ₁(t),

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

Step 6, the serial time domain orthogonal frequency-division multiplex singal s that obtains for the first information source node ₁(t) add Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after the interpolation Cyclic Prefix be sent to via node,

Give the time domain orthogonal frequency-division multiplex singal s of the serial of the second information source node acquisition ₂(t) add Cyclic Prefix, and the time domain orthogonal frequency-division multiplex singal channel after the interpolation 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 the first information source node and the interpolation Cyclic Prefix of the second information source node is sent to via node simultaneously, forms mixed signal at the via node receiving terminal;

Step 7, via node be the described mixed signal of receiving step six from channel, and the mixed signal that obtains is removed circulation prefix processing, and the mixed signal after Cyclic Prefix is removed in acquisition;

Step 8, the mixed signal of removing after Cyclic Prefix gone here and there and changed, obtaining N _cThe road mixed signal that walks abreast;

Step 9, the N to obtaining _cThe parallel mixed signal in road is carried out fast Fourier transform simultaneously, obtains N _cThe road frequency-region signal;

The N that step 10, via node utilization obtain _cThe road frequency-region signal is obtained broadcast data D according to default judgement mapping rule _R(n), complete 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 _R(n) go here and there and change, obtaining N _cThe road broadcast data that walks abreast;

Step 12, the N of via node to obtaining _cThe parallel broadcast data in road carries out respectively constellation mapping, obtains N _cFrequency domain symbol signal after the constellation mapping of road;

Step 13, the N of via node to obtaining _cFrequency domain symbol signal after the constellation mapping of road carries out respectively power division, obtains N _cSignal after the power division of road;

Step 14, the N of via node to obtaining _cAfter the power division of road, signal carries out Fast Fourier Transform Inverse simultaneously, obtains N _cThe road time-domain signal;

Step 15, the N to obtaining _cThe road time-domain signal carries out parallel-serial conversion, then the time-domain signal after parallel-serial conversion is added Cyclic Prefix, and then via node is broadcasted away the time-domain signal that adds after Cyclic Prefix;

After step 10 six, the first information source node receive the broadcast singal of via node, broadcast singal is removed Cyclic Prefix, the signal r after prefix is removed in acquisition ₁(t),

The second information source node is removed Cyclic Prefix to broadcast singal after receiving the broadcast singal of via node, and the signal r after prefix is removed in acquisition ₂(t);

Step 10 seven, the first information source node signal r after to the removal prefix that obtains ₁(t) go here and there and change, obtaining N _cThe road parallel signal is to the N that obtains _cParallel signal carries out N simultaneously _cThe point quick Fourier conversion, the first information source node obtains N _cThe road frequency-region signal,

The signal r of the second information source node after to the removal prefix that obtains ₁(t) go here and there and change, obtaining N _cThe road parallel signal is to the N that obtains _cThe road parallel signal carries out N simultaneously _cThe point quick Fourier conversion, the second information source node obtains N _cThe road frequency-region signal;

Step 10 eight, the N of the first information source node to obtaining _cThe road frequency-region signal is adjudicated respectively, and the first information source node obtains N _cCircuit-switched data,

The N of the second information source node to obtaining _cThe road 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 is separated mapping, and the first information source node obtains N _cCircuit-switched data D ₂(n),

N to the second information source node acquisition in step 10 eight _cCircuit-switched data is separated mapping, and the second information source node obtains N _cCircuit-switched data D ₁(n), complete 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, described in step 3, the first information source node and the second information source node obtained N _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 the water filling theorem calculate system assignment give the power of n subcarrier of the first information source node, system assignment to n subcarrier of the second information source node power and system assignment to the power of a via node n subcarrier and;

Steps A 3, the channel information that obtains according to steps A 1, and the system assignment that calculates of steps A 2 power, system assignment of giving n subcarrier of the first information source node to the power of n subcarrier of the second information source node 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.

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, the N of via node described in step 13 to obtaining _cThe method that frequency domain symbol signal after the constellation mapping of road carries out respectively power division is:

Step B1, obtain channel information by channel estimating;

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

Step B3, the channel information that obtains according to step B1, and the system assignment that obtains of step B2 to the power of n subcarrier of the first information source node, system assignment to the power of n subcarrier of the second information source node and system assignment to the power of a via node n subcarrier and, via node is carried out power division; 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 described channel information that obtains according to steps A 1 of steps A 3, and the system assignment that obtains of steps A 2 to the power of n subcarrier of the first information source node, system assignment to the power of n subcarrier of the second information source node 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) | the time, P ₁(n) and P ₂(n) according to formula:

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

Obtain;

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

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

Obtain, in formula: P ₁(n) be the power of distributing to n road frequency domain constellation symbol signal in the first information source node; P ₂(n) be the power of distributing to n road frequency domain constellation symbol signal in the second information source node; H ₁(n) and H ₂(n) be the frequency domain form of channel, P _tot(n) power, system assignment of giving n subcarrier of the first information source node for system assignment to the power of second an 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 the water filling theorem, calculate P _tot(n) value 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 ²Variance for white Gaussian noise; K is the water line factor, works as P _sumWhen being the gross power of system, by the Power Limitation condition:

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

Obtain the 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 described channel information that obtains according to step 1 of step B3 calculates the power P that via node is distributed to the signal of n subcarrier _R(n) value is passed 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.

6. 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, described the first information source node of step 10 nine is utilized the input data D of self ₁(n) and the N that obtains of step _cCircuit-switched data is separated mapping, obtains the input data D of the first information source node ₂(n), by formula

$D_2\left(n\right)=D_R\left(n\right)\&CirclePlus;D_1\left(n\right)$

Realize;

The second information source node is utilized the input data D of self ₂(n) and the n circuit-switched data obtained of step, separate mapping, obtain the input data D of the first information source node ₁(n), by formula

$D_1\left(n\right)=D_R\left(n\right)\&CirclePlus;D_2\left(n\right)$

Realize.

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