CN106100716A - Cooperation communication system forwards based on mixing and the safety of opportunistic relay strengthens strategy - Google Patents

Abstract

The present invention proposes and forwards based on mixing in a kind of cooperation communication system and the safety enhancing strategy of opportunistic relay.With the channel quality between source sending node and via node as foundation, all via nodes are divided into amplification forwarding (AF) and relay and decode forwarding (DF) and relay two classes.When selecting to carry out the via node cooperated, from two class via nodes, select a via node that can maximize instantaneous secret speed.Secret outage probability and diversity order that the present invention is carried strategy are analyzed, and carried strategy validity has been carried out simulating, verifying, simulation result shows, compared with the relay selection scheme of traditional AF or DF mode, the secret outage probability that the safety of the opportunistic relay based on mixing forwarding that the present invention is carried strengthens strategy is less.

Description

Cooperation communication system forwards based on mixing and the safety of opportunistic relay strengthens strategy

Technical field:

The present invention relates to a kind of mechanism ensureing data transmission security in wireless cooperation system, assist particularly to one Make communication system to forward based on mixing and the safety enhancing strategy of opportunistic relay.

Background technology:

The wireless communication technology developed rapidly breaches the limitation that wired communication system is restricted by line so that information is mutual More convenient.The number of users accommodated in wireless communication system increases rapidly, accordingly, it would be desirable to system can provide higher data Transfer rate.But, the broadcast characteristic having due to wireless medium itself, compared to wire communication, data in radio communication Transmission is faced with the safety challenge of sternness.

One of key technology in communicating as 4G, cooperating relay increase coverage, improve message transmission rate with And strengthen the aspect such as transmission reliability there is significant advantage.But, owing to cooperative relay network existing more node, lead Cause its complicated network structure.Therefore, how to guarantee that in collaborative network, the safe transmission of data is a problem the most serious.From On the other hand considering, the polytropy of wireless communications environment and complexity make to also exist between wireless channel difference, separate Channel between there is the completely unrelated characteristic of channel, therefore, what different users received all have passed through different decline Signal, utilizes this diversity can greatly strengthen the safety of data transmission in wireless system.In recent years, physical layer is utilized Information solves the Security Data Transmission problem in wireless cooperation system becomes a direction of concern.

The basic thought of cooperating relay is the forwarding having cooperated with each other information between relaying, wireless cooperative relay network The cooperation of middle relay well is possible not only in the case of not increasing antenna number improve space diversity, also is able to effectively cancel out simultaneously Wireless fading channel is to increase secret speed, thus promotes the security performance of wireless system.A lot of documents all have studied exist single in The safety issue of cooperative system when continuing, in the presence of having multiple relaying, uses multiple relay forwarding, brings therewith It it is the significantly increase of system implementation complexity.For this problem, document is had to propose the concept of " opportunistic relay ", only with one The relaying of individual " best " carries out cooperation transmission.

Cooperating relay technology is widely used in strengthening safety of physical layer, AF and DF is as relay forwarding base The two ways of plinth is also commonly used.During relaying simple use AF cooperation transmission, via node is receiving at source node Message amplify after be sent to destination node, but, via node, while the useful message received forwards, has Also received by destination node with the noise being mingled with in signal, be unfavorable for that destination node is properly received data.On the other hand, if in The node that continues uses fixing DF mode to forward, then can occur via node that the information of erroneous interpretations is transmitted to the feelings of destination node Condition, now can reduce the performance of system.For some shortcomings point during simple use AF and DF cooperation transmission, a kind of being referred to as, mixes The mode forwarded is suggested, and under this pass-through mode, relaying can be according to the decoding capability of its own between AF and DF Select.Although having many documents all to consider via node participate in cooperation in the way of mixing forwarding, but they all not having There is the safety issue paid close attention in cooperative system.

Summary of the invention:

It is an object of the invention to, by for trunk node selection mode of operation, promote the safety of wireless cooperation system further Property, it is thus provided that in a kind of cooperation communication system and forwards based on mixing and the safety enhancing strategy of opportunistic relay.

For reaching above-mentioned purpose, the present invention adopts the following technical scheme that and is achieved:

Forwarding based on mixing in cooperation communication system and the safety of opportunistic relay strengthens strategy, model of communication system includes: Sending node S, purpose receiving node D, eavesdropping E and K via node R of node_k, k=1,2 ..., K, for data each time Transmission, at first time slot, data are sent to via node with the form of broadcast by sending node S；Second time slot, selects The data received in first time slot, as forward node, are transmitted to destination node D by K via node, with Time be ravesdropping node E eavesdropping.

The present invention is further improved by, and via node judges it according to sending node S and the channel quality between it All via nodes can be divided into AF via node and DF via node two class with this, specifically judge by the decoding capability of self Criterion is as follows:

1) ifVia node R_kDF pattern is selected to forward；

2) ifVia node R_kAF pattern is selected to forward；

Wherein, γ_skIt is sending node S and via node R_kBetween instantaneous signal-to-noise ratio, R_thIt is that given data send speed Rate threshold value, the coefficient before logarithmRepresent that the time of a communication process is divided into two time slots.

The present invention is further improved by, and via node mode of operation judgment criterion is as follows:

If sending node S and via node R_kBetween meet in claim 2 first of channel quality judge bar Part, then when relaying node R_kDF mode can be used time selected to forward, and now the instantaneous of system up to secret speed is:

Otherwise, when relaying node R_kTo participate in follow-up cooperation in the way of AF time selected, corresponding system wink Shi Keda secret rate representation is:

Wherein, γ_kdIt is via node R_kAnd the instantaneous signal-to-noise ratio between destination node D, γ_keIt is via node R_kWith eavesdropping Instantaneous signal-to-noise ratio between node E, function f () is:

The present invention is further improved by, when relaying node R_kSelected as forward node time, the instantaneous of system can Reaching secret speed is:

$R_s\left(k\right)=max\[0,\frac{1}{2}{\log }_2\left(\frac{1+{\mathrm{\γ}}_D^k}{1+{\mathrm{\γ}}_E^k}\right)\];$

Wherein,It is the received signal to noise ratio at destination node D,It is the received signal to noise ratio at eavesdropping node E,With's Expression is as follows:

${\mathrm{\&gamma;}}_D^k=\left\{\begin{array}{cc}{\mathrm{\&gamma;}}_{kd}& {\log }_2(1+{\mathrm{\&gamma;}}_{sk})/2\&GreaterEqual;R_{th}\\ f({\mathrm{\&gamma;}}_{sk},{\mathrm{\&gamma;}}_{kd})& {\log }_2(1+{\mathrm{\&gamma;}}_{sk})/2<R_{th}\end{array}\right.$

${\mathrm{\&gamma;}}_E^k=\left\{\begin{array}{cc}{\mathrm{\&gamma;}}_{ke}& {\log }_2(1+{\mathrm{\&gamma;}}_{sk})/2\&GreaterEqual;R_{th}\\ f({\mathrm{\&gamma;}}_{sk},{\mathrm{\&gamma;}}_{ke})& {\log }_2(1+{\mathrm{\&gamma;}}_{sk})/2<R_{th}\end{array}\right.$

The present invention is further improved by, and in order to make the instantaneous of communication system maximize up to secret speed, selects to make R_sK () takes that relaying of maximum and carries out cooperation forwarding, thus can obtain relay selection criterion is:

$k^{*}=\underset{k=1,\mathrm{...},K}{\mathrm{argmax}}\left\{\frac{1+{\mathrm{\&gamma;}}_D^k}{1+{\mathrm{\&gamma;}}_E^k}\right\};$

Wherein, k^*Index value for selected relaying.

Compared with prior art, the present invention has a following beneficial effect:

When high s/n ratio, the secret outage probability under the mode of traditional simple AF of use uses under DF mode than simple Secret outage probability high, and when low signal-to-noise ratio, the secret outage probability under AF mode is then lower than under DF mode；Compared to biography The simple of system uses AF or DF mode, and mode based on mixing relaying can obtain less secret outage probability, and at middle high letter Make an uproar more notable than the performance difference between the lower present invention and traditional two ways.

Additionally, the relay selection criterion carried in the present invention is disposed in centralized manner, need a center cell (source Node or destination node) maintain a table, this table comprises K relaying and each is relayed to source node, destination node And the channel condition information of eavesdropping node, the relaying that this table is inquired about best.

Accompanying drawing illustrates:

Fig. 1 is cooperative transmission system illustraton of model involved in the present invention；

Fig. 2 is secret outage probability simulation result of the present invention and theoretical analysis result comparison diagram；

Fig. 3 is the present invention and secret outage probability comparison diagram during simple use AF and DF；

Fig. 4 is the secret outage probability of the present invention change curve with target secret speed；

Fig. 5 is the curve chart that secret outage probability of the present invention changes with MER.

Detailed description of the invention:

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to embodiment party of the present invention Formula is described in further detail.

With reference to Fig. 1, the model of communication system that the inventive method uses includes: a source transmitting node S, and a purpose receives Node D, eavesdropping a node E, K via node (R_k, k=1 ..., K), all of node the most only configures individual antenna.Source Node S wishes private message to be securely transmitted to purpose receiving node D, simultaneously eavesdropping node E under the assistance of via node Also attempt to intercept and capture the message that source node S sends.Channel in this network obeys block flat Rayleigh fading, any two node i and Channel coefficients h between node j_ijBe an average be 0, varianceThe multiple Gaussian random variable of Cyclic Symmetry, wherein α It it is path loss index.The additive noise of each receiving terminal be zero-mean, variance be N₀Multiple Gaussian random variable.In due to The node that continues is operated in semiduplex mode, so, a communication process between source node S and destination node D will at two continuously Time slot in carry out.At first time slot, S is to K repeat broadcast private message.At second time slot, the present invention is used to be carried The mixing forwarding gone out and chance selection strategy, select a best relaying from K relaying and private message be transmitted to mesh Node D.

Embodiment:

In the present embodiment, simulating area is set to 3 × 3 square region, without loss of generality, source node S is fixed on (0,0) Point, destination node D is placed on coordinate (0,3) place, and eavesdropping node E is positioned at (3,0) point, and K relaying is equal in 3 × 3 square region Even random distribution.Assuming that each inter-nodal channel obeys block flat Rayleigh fading, the average of channel gain is by the distance between node And path loss index determines.Because being put forward strategy emphasis to be the selection of relay forwarding pattern, and relay forwarding pattern Selection relevant with the position distribution of node, therefore, generate 100 topologys the most altogether, use Monte Carlo imitate Very.In order to verify effectiveness of the invention, Monte Carlo simulation result being contrasted with theory analysis value, concrete outcome is such as Shown in Fig. 2, wherein, target secret speed R_s=0.1bit/s/Hz, it is contemplated that relaying quantity K takes 6, the situation of 8,10.From figure Three below conclusion can be drawn: first, when low signal-to-noise ratio, the relation of the approximation used during due to theory analysis, cause Theoretical value and simulation result have deviation, but, when high s/n ratio, simulation result is the most identical with theoretical analysis result, and this tests Demonstrate,prove the correctness of theory analysis of the present invention；Secondly, increasing the SNR of system, secret outage probability can reduce, but at high s/n ratio Time can tend to a positive constant, this is because high s/n ratio when, the transfer rate of legal link and eavesdropping link Difference between transfer rate almost no longer increases along with the increase of average signal-to-noise ratio.Finally, from the figure, it can be seen that pass through Increasing the quantity of via node, the security performance of system also can be significantly improved, because via node number is the most, system is just Higher degree of freedom is had to go to select preferably to relay for promoting security of system.

Fig. 3 gives the simulation result of the secret outage probability under mixing forwarding, tri-kinds of pass-through modes of AF and DF, from figure It will be seen that compared with simple AF and DF, the present invention has obvious advantage on reduction secret outage probability, particularly exists When signal to noise ratio is in medium level.When low signal-to-noise ratio, the probability that relaying decoding is correct is low, the principle forwarded according to mixing, in Continuing and participate in cooperation in the way of node will use amplification forwarding by high probability, the performance that mixing now forwards is close to property during AF Energy.And when high s/n ratio, the probability that relaying decoding is correct is high, what the optimum relaying selected worked in the way of decoding forwarding can Energy property is much greater, and i.e. when high s/n ratio, the Performance comparision when performance of the present invention and DF is close.But, in medium noise During than this region, the present invention would be even more beneficial to antagonism eavesdropping.

What Fig. 4 showed is the relation curve between secret outage probability and target secret speed, the relaying arranged in emulation Interstitial content is K=5, and the tri-kinds of situations of 10dB, 20dB and 30dB that take SNR are emulated.As we can see from the figure: first, Along with target secret speed increases, secret outage probability also can improve accordingly, but secret outage probability often eventually tends to one Number；Secondly, give set the goal secret speed time, along with the increase of SNR, secret outage probability can be more and more less, this is because SNR Increase can improve instantaneous secret speed, so, corresponding secret outage probability can reduce.

In order to the diversity order performance of the present invention is described, simulate the secret outage probability change curve relative to MER, as Shown in Fig. 5, MER refers toSNR is set in emulation 20dB, and target secret speed is 0.1bit/s/Hz.From figure It will be seen that along with the increase of MER, secret outage probability meeting monotone decreasing, this is because MER means the most greatly the letter of main channel Road quality is the best relative to the channel quality of tapping channel, so, system secret capacity is the biggest.It addition, along with relaying The number of node increases to 6 from 2, and secret outage probability is also diminishing significantly, and the quantity that this explanation increases cooperating relay has Help improve the ability of the anti-eavesdropping of safety of physical layer.As a example by there are 4 relayings in system, when MER is 5dB, the private of system Close outage probability is 10-2, when MER increases to 15dB, from the figure, it can be seen that now the secret outage probability of system approximates Declining 10dB for 10-6, i.e. MER, secret outage probability approximation have dropped 4 orders of magnitude, illustrates that the diversity order of the present invention is K。

So far, the advantage of the safety of the inventive method emerges from, and its technical scheme and simulation result can be verified Present invention useful effect in terms of strengthening cooperative system safety.

Claims (5)

1. cooperation communication system forwards based on mixing and the safety of opportunistic relay strengthens strategy, it is characterised in that communication system Model includes: sending node S, purpose receiving node D, eavesdropping E and K via node R of node_k, k=1,2 ..., K, for The transmission of data each time, at first time slot, data are sent to via node with the form of broadcast by sending node S；Second Individual time slot, select one in K via node as forward node, the data received in first time slot are transmitted to mesh Node D, be ravesdropping simultaneously node E eavesdropping.

Cooperation communication system the most according to claim 1 forwards based on mixing and the safety of opportunistic relay strengthens strategy, It is characterized in that, via node judges the decoding capability of himself according to sending node S and the channel quality between it, with this energy Enough all via nodes being divided into AF via node and DF via node two class, concrete judgment criterion is as follows:

1) ifVia node R_kDF pattern is selected to forward；

2) ifVia node R_kAF pattern is selected to forward；

Wherein, γ_skIt is sending node S and via node R_kBetween instantaneous signal-to-noise ratio, R_thIt it is given data transmission rate door Limit value, the coefficient before logarithmRepresent that the time of a communication process is divided into two time slots.

Cooperation communication system the most according to claim 2 forwards based on mixing and the safety of opportunistic relay strengthens strategy, It is characterized in that, via node mode of operation judgment criterion is as follows:

If sending node S and via node R_kBetween channel quality meet first Rule of judgment in claim 2, then When relaying node R_kDF mode can be used time selected to forward, and now the instantaneous of system up to secret speed is:

Otherwise, when relaying node R_kTo participate in follow-up cooperation in the way of AF time selected, corresponding system instantaneous up to Secret rate representation is:

Wherein, γ_kdIt is via node R_kAnd the instantaneous signal-to-noise ratio between destination node D, γ_keIt is via node R_kWith eavesdropping joint Instantaneous signal-to-noise ratio between some E, function f () is:

4. according to the cooperation communication system described in claim 3 forwarding based on mixing and the safety enhancing plan of opportunistic relay Slightly, it is characterised in that when relaying node R_kSelected as forward node time, the instantaneous of system up to secret speed is:

Wherein,It is the received signal to noise ratio at destination node D,It is the received signal to noise ratio at eavesdropping node E,WithTool Body expression formula is as follows:

。

Cooperation communication system the most according to claim 4 forwards based on mixing and the safety of opportunistic relay strengthens strategy, It is characterized in that, in order to make the instantaneous of communication system maximize up to secret speed, select to make R_s(k) take maximum that in Row cooperation of going on forwards, and thus can obtain relay selection criterion is:

Wherein, k^*Index value for selected relaying.