The relay selection method and device of a kind of full duplex relaying system
Technical field
The present invention relates to wireless communication technology field, more particularly to a kind of relay selection side of full duplex relaying system
Method and device.
Background technology
Recent years, cooperative communication technology receives the extensive concern of researcher all over the world.Collaboration communication is a kind of
New space diversity technology, can substantially be considered as the Principle of Communication of similar MIMO (MIMO technique), utilize nothing
The broadcast characteristic that line communication channel has, user is by way of cooperating with each other, distributed transmission and information processing, constitutes
Virtual distributed aerial array, while coverage rate is expanded, the higher power system capacity of acquisition and spectrum utilization efficiency.
In cooperation communication system, because relaying has the advantages such as the low, flexible layout of component cost, so the high speed in order to realize data
And effectively transmission, can be generally based on relaying technique.If the fixed single relaying of selection carries out signal in cooperation communication system
Transmission, trunk channel environmental change is larger, is not sufficiently stable, so needing to set up multiple relay cooperative communication systems, further carries
Rise systematic function., it is necessary to which the problem of considering " being cooperated with whom ", that is, carry out relay selection, such as in multi-relay cooperation communication system
What is selected optimal relaying from multiple candidate relays and carries out the research emphasis that signal transmission is collaboration communication.Research shows selection
Go out an optimal relaying and carry out the best solution that signal transmission is equilibrium stage gain and spectrum efficiency.
Existing relay selection technology be largely based on the two kinds of relay forwarding being easily achieved agreements i.e.:(amplification turns AF
Hair) agreement and DF (decoding forwarding) agreement.AF relays full duplex cooperative system because its design is relatively easy, it is easy to accomplish and
Lower deployment cost is low, takes the lead in being studied much.Under AF agreements, the continual transmission signal of source node, via node is only
It is to amplify the signal received according to specific coefficient, and forwards the amplified signal, other processing is not done to signal, are then used
Communicate general principle knowledge, can obtain power system capacity expression formula.Each channel coefficients is set to obey I.I.D. again (independent same
Distribution) Rayleigh fading, optimal relaying is selected according to the CSI (channel condition information) of feedback and carries out signal transmission, then is transported
The expression formula and approximate expression of out-trunk probability are derived with mathematical measures such as probability theories.Finally, simulation analysis of computer is passed through
The performance of different relay selection schemes.The many relay systems of full duplex under DF agreements, via node will receive signal decoding weight
After new modulation, then it is forwarded to destination node.The process for simplifying the analysis in existing research, it is assumed that via node from dry
Disturb and declined for perseverance, then with already present relay selection method in similar half-duplex and full duplex AF relayings, derive system
Average size, outage probability or the bit error rate, then go out by simulation analysis of computer the performance of each relay selection scheme.
Although can also realize relay selection using AF agreements, AF via nodes simply amplify according to specific coefficient
The signal received, and the amplified signal is forwarded, other processing are not done to signal, so the amplified signal of via node not only contains
Have useful signal, also comprising certain noise, this part by amplification noise signal by the noise received in next-hop together
The performance of influence system.In DF relayings, although assuming that self-interference simplifies analysis process for permanent decline, but actual conditions
Under self-interference be continually changing, the output of via node is one auspicious to the self-interference channel Link Fade coefficient of input
Profit distribution random process, it is impossible to ensure the service quality of user.Obviously, the prior art based on AF agreements and DF agreements is
The requirement selected in full duplex relaying System relays can not be met.
The content of the invention
Above mentioned problem is directed to, the present invention provides the relay selection method and device of a kind of full duplex relaying system, realized
Effective lifting system performance and QoS of customer and the purpose for saving equipment cost.
To achieve these goals, there is provided a kind of relaying of full duplex relaying system according to the first aspect of the invention
System of selection, the full duplex relaying system includes source node, destination node, multiple via nodes and source section
Point arrives channel link, the channel link of via node to destination node and the via node self-interference channel link of via node,
The relay selection method of the full duplex relaying system includes:
Based on DF agreements, the channel condition information of the channel link in the full duplex relaying system presets four kinds
Relay selection scheme, wherein, four kinds of relay selection schemes include a kind of optimal relay selection scheme and three kinds of suboptimum relayings
Selection scheme;
It is theoretical according to the system break performance of independent identically distributed rayleigh fading channel, to four kinds of relay selection sides
Case carries out analysis calculating, respectively obtains the outage probability corresponding to each relay selection scheme;
By the channel condition information of the channel link under the channel circumstance measured by reality, actual full duplex relaying system
Outage probability corresponding to the relaying number of system and each described relay selection scheme is as simulation analysis factor, using calculating
Machine carries out simulation analysis to the emulation factor, obtains four kinds of relay selection schemes in the channel measured by the reality
Performance state under environment;
The performance state under channel circumstance according to measured by four kinds of relay selection schemes in the reality, by institute
State the performance state under the channel circumstance measured by the reality of three kinds of suboptimum relay selection schemes and the optimal relay selection side
The performance state of case is contrasted, and selects performance state in three kinds of suboptimums relay selection scheme closest to described optimal
A kind of suboptimum relay selection scheme of the performance state of relay selection scheme, is used as the actual full duplex relaying system
Relay selection scheme.
It is preferred that, this method also includes:
After the relay selection scheme of the actual full duplex relaying system is determined, by described actual complete
Different relaying numbers are set to divide the outage probability of the actual full duplex relaying system in duplexing relay system
Analysis, determines the relaying number corresponding to the outage probability minimum, and according to the relaying number to the actual full duplex
Relay system carries out corresponding relaying deployment.
It is preferred that, it is described to be based on DF agreements, the channel status of the channel link in the full duplex relaying system
Information, presets four kinds of relay selection schemes, including:
The channel condition information of whole channel links in the full duplex relaying system, presets described in obtaining most
Excellent relay selection scheme;
The source node in the full duplex relaying system to the link of via node channel condition information and
The via node is preset to the channel condition information of the link of destination node and obtains minimax relay selection scheme;
The source node in the full duplex relaying system to the link of via node channel condition information and
The self-interference link of via node, presets and obtains part relay selection scheme;
The self-interference link of via node in the full duplex relaying system, presets and obtains self-interference relaying choosing
Select scheme;
Wherein, the minimax relay selection scheme, part relay selection scheme and self-interference relay selection scheme are
Suboptimum relay selection scheme.
It is preferred that, the system break performance according to independent identically distributed rayleigh fading channel is theoretical, to described four kinds
Relay selection scheme carries out analysis calculating, respectively obtains the outage probability corresponding to each relay selection scheme, including:
Four kinds of relay selection selection schemes are calculated, the system letter of each relay selection scheme is obtained respectively
Road capacity C, wherein,In formula,For the signal to noise ratio of the link of source node to via node,
For the signal to noise ratio of the link of source node to destination node;
Based on the system channel capacity of each relay selection scheme, calculate and obtain each described relay selection scheme
Outage probabilityIn formula, * represents the probability of different relay selection schemes, R respectively0
Represent via node capacity.
It is described complete double according to the second aspect of the invention there is provided a kind of relay selection device of full duplex relaying system
Work relay system includes the channel of source node, destination node, multiple via nodes and source node to via node
Link, via node are to the channel link and via node self-interference channel link of destination node, the full duplex relaying system
Relay selection device include:
Presetting module, for based on DF agreements, the channel status of the channel link in the full duplex relaying system
Information, presets four kinds of relay selection schemes, wherein, four kinds of relay selection schemes include a kind of optimal relay selection scheme
With three kinds of suboptimum relay selection schemes;
Computing module, it is theoretical for the system break performance according to independent identically distributed rayleigh fading channel, to described four
Plant relay selection scheme and carry out analysis calculating, respectively obtain the outage probability corresponding to each relay selection scheme;
Analysis module, for by the channel condition information of the channel link under the channel circumstance measured by reality, actual
Outage probability corresponding to the relaying number of full duplex relaying system and each described relay selection scheme as simulation analysis because
Element, simulation analysis are carried out using computer to the emulation factor, obtain four kinds of relay selection schemes in the actual institute
Performance state under the channel circumstance of measurement;
Comparison module, for according to four kinds of relay selection schemes in the reality measured by channel circumstance under
Performance state, by the performance state under the channel circumstance measured by the reality of three kinds of suboptimums relay selection scheme with it is described
The performance state of optimal relay selection scheme is contrasted, and selects the performance state in three kinds of suboptimums relay selection scheme
Closest to a kind of suboptimum relay selection scheme of the performance state of the optimal relay selection scheme, as described actual complete
The relay selection scheme of duplexing relay system.
It is preferred that, the device also includes:
Deployment module, for after the relay selection scheme of the actual full duplex relaying system is determined, by
Interruption of the different relaying numbers to the actual full duplex relaying system is set in the actual full duplex relaying system
Probability is analyzed, and determines the relaying number corresponding to the outage probability minimum, and according to the relaying number to the reality
The full duplex relaying system on border carries out corresponding relaying deployment.
It is preferred that, the presetting module includes:
First default unit, the channel status for whole channel links in the full duplex relaying system is believed
Breath, presets and obtains the optimal relay selection scheme;
Second default unit, the letter for the source node in the full duplex relaying system to via node
The channel condition information of road link and the via node are preset and obtained to the channel condition information of the channel link of destination node
Obtain minimax relay selection scheme;
3rd default unit, the letter for the source node in the full duplex relaying system to via node
The channel condition information of the channel condition information of road link and the self-interference channel link of via node, presets and obtains in part
After selection scheme;
4th default unit, for the self-interference link of the via node in the full duplex relaying system, presets
Obtain self-interference relay selection scheme;
Wherein, the minimax relay selection scheme, part relay selection scheme and self-interference relay selection scheme are
Suboptimum relay selection scheme.
It is preferred that, the computing module includes:
First computing unit, for calculating four kinds of relay selection selection schemes, obtains each relaying respectively
The system channel capacity C of selection scheme, wherein,In formula,Via node is arrived for source node
The signal to noise ratio or Signal Interference and Noise Ratio of link,Signal to noise ratio or signal interference for the link of source node to destination node are made an uproar
Acoustic ratio;
Second computing unit, for the system channel capacity based on each relay selection scheme, calculates and obtains described
The outage probability of each relay selection schemeIn formula, * represents different relayings respectively
The probability of selection scheme, R0Expression system needs the minimum capacity thresholding reached.
Compared to prior art, the present invention has preset a kind of optimal and three kinds of suboptimums relaying based on decoding retransmission protocol
Selection scheme, and the outage probability of four kinds of relay selection schemes is obtained according to independent same distribution rayleigh fading channel, with reference to
The channel status of actual measurement, the interruption performance to four kinds of relay selection schemes carries out com-parison and analysis, and selection is closest to most
A kind of suboptimum relay selection scheme of excellent relay selection scheme is used as final relay selection scheme, needed for so reducing
Channel condition information, and then the complexity of relay selection method is reduced, compared to the relay selection scheme of amplification forwarding
Systematic function gets a promotion;And the relay selection scheme under actual conditions is imitated by computer in the present invention
True analysis, it is possible to achieve according to the requirement of different geographical and different clients, using rational relay selection scheme, can both expire
The requirement of the service quality of sufficient different user, additionally it is possible to cost-effective.And then effective lifting system is realized by the present invention
Performance and QoS of customer and the purpose for saving equipment cost.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will to embodiment or
The accompanying drawing used required in description of the prior art is briefly described, it should be apparent that, drawings in the following description are only
Embodiments of the invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Other accompanying drawings are obtained according to the accompanying drawing of offer.
Fig. 1 is a kind of flow signal of the relay selection method for full duplex relaying system that the embodiment of the present invention one is provided
Figure;
Fig. 2 is the structural representation of full duplex relaying system provided in an embodiment of the present invention;
Fig. 3 is the flow signal of the default selection scheme in S11 steps shown in the corresponding Fig. 1 of the embodiment of the present invention two
Figure;
Fig. 4 is the flow of the calculating outage probability in step S12 steps shown in the corresponding Fig. 1 of the embodiment of the present invention two
Schematic diagram;
Fig. 5 is a kind of structural representation of the relay selection device for full duplex relaying system that the embodiment of the present invention three is provided
Figure.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on
Embodiment in the present invention, those of ordinary skill in the art obtained under the premise of creative work is not made it is all its
His embodiment, belongs to the scope of protection of the invention.
Term " first " and " second " in description and claims of this specification and above-mentioned accompanying drawing etc. are to be used for area
Not different objects, rather than for describing specific order.In addition term " comprising " and " having " and they it is any become
Shape, it is intended that covering is non-exclusive to be included.For example contain the process of series of steps or unit, method, system, product
Or equipment is not set in the step of having listed or unit, but the step of may include not list or unit.
Embodiment one
Referring to the flow for the relay selection method that Fig. 1 is a kind of full duplex relaying system that the embodiment of the present invention one is provided
Schematic diagram, and referring to the structural representation that Fig. 2 is full duplex relaying system provided in an embodiment of the present invention, in the full duplex
The channel of a source node S, destination node D, a multiple via node R and source node to via node is included after system
Link hSR, via node to destination node channel link hRDWith via node self-interference channel link hRR。
Specifically, in full duplex relaying system, including a source node (Source) and a destination node
And each DF via nodes (R of N (Destination)k,k∈{1,2,…,N}).Because between source node and destination node
Direct link can only be transmitted by very strong decline, signal by relay forwarding.Wherein, source node and destination node
An antenna is equipped with, semiduplex mode is operated in;All via nodes use DF agreements, and are equipped with one group of dual-mode antenna, make
Operation must be relayed in a full-duplex mode, the time is divided into multiple time slots, each time slot only selects a relaying to carry out signal
Transmission.
Three channel links, source node to via node link, via node are included in many relay communications systems of full duplex
Input link is output to destination node link and via node.For simplifying the analysis, it is assumed that each relaying mutually every
From the i.e. signal interfering link in the absence of relay well.In network all Radio Links be steady Rayleigh bulk nanometer materials and
Separate, receiving terminal noise is additive white Gaussian noise (AWGN), and its average is 0, and variance is N0。
The relay selection method of the full duplex relaying system comprises the following steps:
S11, based on DF agreements, the channel condition information of the channel link in the full duplex relaying system is preset
Four kinds of relay selection schemes, wherein, four kinds of relay selection schemes include a kind of optimal relay selection scheme and three kinds of suboptimums
Relay selection scheme;
Specifically, existing relay forwarding agreement is AF agreements and DF agreements, wherein, AF agreements are method retransmission protocol,
Because AF relaying full duplex cooperative system designs are relatively easy, it is easy to accomplish, lower deployment cost is low, takes the lead in being studied much.
Because AF via nodes are the signal for amplifying according to specific coefficient and receiving, and forward the amplified signal, it is not done to signal
He is handled, so the amplified signal of via node not only contains useful signal, also comprising certain noise, so in the present invention
Preferred DF agreements in embodiment.Default four kinds of relay selection schemes are included in full duplex relaying system according to all channels
The optimal relay selection scheme of the channel condition information of link and only need the suboptimum relay selection side of impaction of partial channel state information
Case.
Described four kinds relayings are selected by S12, the system break performance theory according to independent identically distributed rayleigh fading channel
Select scheme and carry out analysis calculating, respectively obtain the outage probability corresponding to each relay selection scheme;
Specifically, because the channel in full duplex relaying system is independent identically distributed Rayleigh fading, can obtain each
The probability density function (PDF) of individual channel, can be with mathematical measure and the Principle of Communication ABC such as probability theory
The cumulative distribution function (CDF) of outage probability is derived, the computational chart of outage probability can be obtained by providing specific channel speed
Up to formula.
S13, by the channel condition information of the channel link under the channel circumstance measured by reality, actual full duplex
After the outage probability corresponding to the relaying number and each described relay selection scheme of system as simulation analysis factor, use
Computer carries out simulation analysis to the emulation factor, obtains four kinds of relay selection schemes measured by the reality
Performance state under channel circumstance;
Specifically, when carrying out simulation analysis to the emulation factor using computer, can use in computer
Matlab softwares are analyzed, naturally it is also possible to using other there is the software of simulation analysis to be analyzed, this programme, which is not done, to be had
Body is limited.
Performance state under S14, the channel circumstance according to measured by four kinds of relay selection schemes in the reality,
Performance state under channel circumstance measured by the reality of three kinds of suboptimums relay selection scheme is selected with the optimal relaying
The performance state for selecting scheme is contrasted, and selects the performance state in three kinds of suboptimums relay selection scheme described in
A kind of suboptimum relay selection scheme of the performance state of optimal relay selection scheme, is used as the actual full duplex relaying system
The relay selection scheme of system.
Specifically, the performance shape under channel circumstance according to measured by four kinds of relay selection schemes in the reality
State is analyzed, and combines the influence of the self-interference signal to noise ratio in actual environment and relaying quantity to system break probability, is based on
Actual channel environment measured by different regions, is divided the performance of four kinds of relay selection schemes from the angle of interruption performance
Analysis is compared, and the second choice of opimization scheme of selection wherein interruption performance closest to optimal selection scheme is used as final relay selection scheme
To carry out specific relay selection, and then reduce the complexity of equipment.It is understood that so-called closest to being exactly basis
Four kinds of relay selection Scheme Choices go out corresponding relaying, and the relaying is carried out analysis obtain its corresponding channel capacity and
These parameters of signal to noise ratio, so as to obtain the outage probability of system, the smaller performance for showing system of outage probability is better, so just
It is channel capacity, signal to noise ratio and interruption that the selection scheme relayed according to three kinds of suboptimums carries out its system of relay selection post analysis
Parameter in probability, and being contrasted with these parameters in optimal relay selection scheme, selection suboptimum relay selection scheme with
The equal or close suboptimum relay selection scheme of parameter in optimal relay selection scheme, is used as the relay selection that system is final
Scheme.
By technical scheme disclosed in the embodiment of the present invention one, a kind of optimal and three have been preset based on decoding retransmission protocol
The relay selection scheme of kind of suboptimum, and four kinds of relay selection schemes are obtained according to independent same distribution rayleigh fading channel
Outage probability, with reference to the channel status of actual measurement, the interruption performance to four kinds of relay selection schemes carries out analysis ratio
Compared with, selection is used as final relay selection scheme closest to a kind of suboptimum relay selection scheme of optimal relay selection scheme,
Required channel condition information is so reduced, and then reduces the complexity of relay selection method, compared to amplification forwarding
The systematic function of relay selection scheme gets a promotion;And the relaying under actual conditions is selected by computer in the present invention
The scheme of selecting has carried out simulation analysis, it is possible to achieve according to the requirement of different geographical and different clients, selected using rational relaying
Scheme is selected, the requirement of the service quality of different user can be both met, additionally it is possible to cost-effective.And then pass through present invention realization
Effective lifting system performance and QoS of customer and the purpose for saving equipment cost.
Embodiment two
The detailed process of S11 to S14 steps with reference to described in the embodiment of the present invention one and Fig. 1, in present invention implementation
In example two, the relay selection method of the full duplex relaying system also includes:
After the relay selection scheme of the actual full duplex relaying system is determined, by described actual complete
Different relaying numbers are set to divide the outage probability of the actual full duplex relaying system in duplexing relay system
Analysis, determines the relaying number corresponding to the outage probability minimum, and according to the relaying number to the actual full duplex
Relay system carries out corresponding relaying deployment.
It is understood that by setting different relaying numbers to analyze interruption performance in Same Scene,
Optimal relay selection number N is found, because interruption performance is further not with relaying number when relaying number and being more than N
Increase and increase, so should avoid relaying the excessive of number, so as to effectively reduce the relaying number set needed for system, enter
And reduce the cost of system.
Referring to the flow that Fig. 3 is the default selection scheme shown in the corresponding Fig. 1 of the embodiment of the present invention two in S11 steps
Schematic diagram, it is described be based on DF agreements, the channel condition information of the channel link in the full duplex relaying system, in advance
If four kinds of relay selection schemes, including:
S111, whole channel links in the full duplex relaying system channel condition information, preset and obtain institute
State optimal relay selection scheme;
S112, the source node in the full duplex relaying system to the link of via node channel status
Information and the via node are preset to the channel condition information of the link of destination node and obtain minimax relay selection side
Case;
S113, the source node in the full duplex relaying system to the link of via node channel status
The self-interference link of information and via node, presets and obtains part relay selection scheme;
S114, via node in the full duplex relaying system self-interference link, preset and obtain in self-interference
After selection scheme;
Wherein, the minimax relay selection scheme, part relay selection scheme and self-interference relay selection scheme are
Suboptimum relay selection scheme.
Accordingly, it is the calculating interruption shown in the corresponding Fig. 1 of the embodiment of the present invention two in step S12 steps referring to Fig. 4
The schematic flow sheet of probability, the system break performance according to independent identically distributed rayleigh fading channel is theoretical, to described four
Plant relay selection scheme and carry out analysis calculating, respectively obtain the outage probability corresponding to each relay selection scheme, including:
S121, four kinds of relay selection selection schemes are calculated, each relay selection scheme is obtained respectively is
Unite channel capacity C, wherein,In formula,For the signal to noise ratio of the link of source node to via node
Or Signal Interference and Noise Ratio,For the signal to noise ratio or Signal Interference and Noise Ratio of the link of source node to destination node;
S122, the system channel capacity based on each relay selection scheme, calculate and obtain each described relay selection
The outage probability of schemeIn formula, * represents the general of different relay selection schemes respectively
Rate, R0Expression system needs the minimum capacity thresholding reached.
Specific analysis process is as follows in the embodiment of the present invention two:
The full duplex relaying system under independent same distribution rayleigh fading channel in embodiments of the present invention is as shown in Figure 2.
If{ A, B } ∈ { S, R, D } represents S-RkChannel link, Rk- D channel links and relaying self-interference channel chain
The channel fading coefficient on road, and its average is 0, variance isWherein, k represents k-th of relaying.Therefore, channel fading coefficient
AmplitudeObeying parameter isExponential distribution.The transmission signal of source node and via node is respectively xSAnd xR.Then should
Communication process can be counted as two stages under system model.
Stage 1,Source node is constantly by signal xSN number of DF via nodes are transmitted into, while a relaying section
A upper slot decoder signal is forwarded to destination node by point.During this period, the self-interference of generation is expressed asTherefore, relay
The reception signal of node is expressed as:
Wherein PSAnd PRThe transmission power of source node and via node is represented respectively.Represent in S-RkThe additivity of link is high
This white noise.S-R can be obtained by (1)kLink and relaying self-interference link signal to noise ratio be respectively
Accordingly,Signal to Interference plus Noise Ratio be
Stage 2,Select end-to-end signal to noise ratio best relaying and the signal of source node is forwarded to purpose
Node.At the same time, N number of DF via nodes receive the signal of next time slot.Therefore, the reception signal table of destination node
It is shown as:
nDThe additive white Gaussian noise in S-R links is represented, while R can be obtainedkThe signal to noise ratio of-D linksIt therefore, it can obtain system channel capacity expression:
The systematic function of each relay selection scheme is analyzed in the embodiment of the present invention according to outage probability.First, according to
The definition of outage probability, i.e. outage probability are another expression way of link capacity in fact, when link capacity can not meet institute
It is required that user rate when, interrupt event will be produced, this event is in probability distribution, depending on the average noise of link
Than and its channel fading distributed model, the infinitive of outage probability can be obtained:
Wherein, * represents the probability of different relay selection schemes respectively.For simplifying the analysis with formula complexity, Wo Mending
JusticeIt is the cumulative distribution function of stochastic variable.
Optimal relay selection scheme (OS) is that the channel capacity expression formula transmitted according to full duplex relaying system signal is obtained
, it needs to know the channel condition information of all channels.Therefore, OS schemes can be embodied as:
What formula (5) showed is the choosing principles of OS relay selection schemes, i.e., selected according to the selection standard of formula (5)
Relaying k out, the capacity that channel link where it is obtained by formula (3) is maximum.
Because all channels are all Rayleigh fadings, the probability density function clothes of the corresponding signal to noise ratio of each of the links
From exponential distribution, then:
γRCumulative distribution function be expressed as:
Again because γSRAnd γRDIt is separate, so γSRAnd γRDJoint probability density function be expressed as:
Further according to probability theory fundamental theorem, γ is obtainedRCumulative distribution function be:
If Z=min { γR,γRD, then Z cumulative distribution function is expressed as:
It can be learnt by formula (6)Bring it and formula (9) into formula (10) again, derive:
Finally, according to order statistic theorem, derive:
I.e. formula (12) is the final expression formula of the cumulative distribution function, i.e. outage probability of OS relay selection schemes.
In traditional half-duplex relay system, the reception or transmission that signal is only carried out in single time slot are relayed,
Therefore minimax relay selection scheme (MM) resulting under the system does not have the influence of self-interference, and this scheme is promoted
Into full duplex relaying system, relay selection does not consider the influence of self-interference, and MM schemes can be embodied as:
Formula (13) is the expression formula of MM relay selection schemes, i.e. this scheme selected relaying k, its S-RkWith
It is also maximum that repeated link, which may be selected, compared to other in the minimum signal to noise ratio of two sections of links.
Obtained according to probability theory is theoretical with symmetryExpression formula:
Will in two kinds of situation when being analyzed, γSR> γRDAnd γSR< γRD, according in existing documents and materials
Calculating process,It is embodied as:
BecauseIt is brought into formula (15), calculating is obtained:
Similarly, by the variable λ in formula (15)SRAnd λRDExchange, you can obtain γRDCumulative distribution function:
Finally, by formula (15) and (17) bring into (10) can be obtained by MM interrupt selection scheme under system interruption it is general
Rate.
Accordingly, it is assumed that relaying only just knows that the channel condition information of first link, i.e.,, it is known that and system evidence
This selects optimal relaying and carries out signal transmission, here it is part relay selection scheme (PS), can use following expression:
Formula (18) is the formula expression-form of PS relay selection schemes, is illustrated to selected relaying k, its S-RkLink
Signal to Interference plus Noise RatioIt is maximum.
For part relay selection scheme (PS), convolution (9) and order statistic theorem are derived:
Above-mentioned derivation applies mathematical formulaeIt is combined, obtains with Article 2 link again
Cumulative distribution function to the total signal to noise ratio of system is:
Self-interference relay selection scheme (SI) only just knows that the channel condition information of relaying self-interference link, can specific table
It is up to formula:
Formula (21) is the formula expression-form of SI relay selection schemes, is illustrated based on relaying k its RR selected by SIkLetter
The signal to noise ratio of road link is minimum.
Different from formula (15) and (16) hypothesis, the remaining residual self-interference by self-interference technology for eliminating is obeyed auspicious
Sharp block decline rather than permanent decline.
According to order statistic theorem, derive that first link selection relays the cumulative distribution letter of self-interference signal to noise ratio
Number is:
Derivation obtains probability density functionAnd combineIt can obtain:
Finally, combine the cumulative distribution function of Article 2 link signal to noise ratio, derive the cumulative distribution of the total signal to noise ratio of system
Function is:
The Cumulative Distribution Function of four kinds of relay selection schemes is obtained respectively, so as to obtain four kinds of relay selection schemes
Outage probability, measure channel status in conjunction with actual, the interruption performance of four kinds of relay selection schemes carried out using computer
Comparative analysis, the second choice of opimization scheme of selection wherein interruption performance closest to optimal selection scheme is used as final relay selection side
Case carries out specific relay selection, and then reduces the complexity of equipment.It is understood that so-called closest to being exactly root
Go out corresponding relaying according to four kinds of relay selection Scheme Choices, and analysis is carried out to the relaying and obtain its corresponding channel capacity
With these parameters of signal to noise ratio, so as to obtain the outage probability of system, the smaller performance for showing system of outage probability is better, so
Be exactly the selection scheme relayed according to three kinds of suboptimums carry out the channel capacity of its system of relay selection post analysis, signal to noise ratio and in
Disconnected probability, and contrasted with these parameters in optimal relay selection scheme, the parameter in selection suboptimum relay selection scheme
The suboptimum relay selection scheme equal or close with the parameter in optimal relay selection scheme, is selected as the relaying of system finally
Select scheme.Due to have selected the relay selection scheme of suboptimum, the channel condition information needed for reducing, and then reduce relaying choosing
Select the complexity of device.
Technical scheme disclosed according to embodiments of the present invention two, having preset needs the channel status of all channel links to believe
The optimal relay selection scheme of breath and the suboptimum relay selection scheme for the channel condition information for only needing local channel link;Save in source
The continuous item repeat broadcast signal of point, optimal relaying is gone out according to specific channel circumstance using corresponding relay selection Scheme Choice,
Then the decoding of via node reception signal is re-modulated again is forwarded to destination node.Because channel is independent identically distributed Rayleigh
Decline, can obtain the probability density function of each channel, basic with the mathematical measures such as probability theory and Principle of Communication
Simply, the cumulative distribution function of outage probability can be shifted out onto, the expression formula of outage probability is then obtained;Pass through computer again
Simulation analysis obtain performance state of the four kinds of relay selection schemes under the channel circumstance measured by the reality;Finally
Providing corresponding relay selection method and relaying deployment scheme under different channels environment can realize according to different geographical and difference
The requirement of client, using rational relay selection scheme, selection scheme is interrupted instead of optimal interruption selection due to have selected suboptimum
Scheme reduces the complexity for interrupting selection, can both meet the requirement of the service quality of different user, additionally it is possible to save into
This.And then effective lifting system performance and QoS of customer are realized by the present invention and the mesh of equipment cost is saved
's.
Embodiment three
It is relative with the relay selection method of the full duplex relaying system disclosed in the embodiment of the present invention one and embodiment two
Should, embodiments of the invention three additionally provide a kind of relay selection device of full duplex relaying system, are the present invention referring to Fig. 5
A kind of structural representation of the relay selection device for full duplex relaying system that embodiment three is provided, the device includes:
Presetting module 1, for based on DF agreements, the channel shape of the channel link in the full duplex relaying system
State information, presets four kinds of relay selection schemes, wherein, four kinds of relay selection schemes include a kind of optimal relay selection side
Case and three kinds of suboptimum relay selection schemes;
Computing module 2, it is theoretical for the system break performance according to independent identically distributed rayleigh fading channel, to described
Four kinds of relay selection schemes carry out analysis calculating, respectively obtain the outage probability corresponding to each relay selection scheme;
Analysis module 3, for by the channel condition information of the channel link under the channel circumstance measured by reality, reality
Full duplex relaying system relaying number and each described relay selection scheme corresponding to outage probability be used as simulation analysis
Factor, simulation analysis are carried out using computer to the emulation factor, obtain four kinds of relay selection schemes in the reality
Performance state under measured channel circumstance;
Comparison module 4, for according to four kinds of relay selection schemes in the reality measured by channel circumstance under
Performance state, by the performance state under the channel circumstance measured by the reality of three kinds of suboptimums relay selection scheme with it is described
The performance state of optimal relay selection scheme is contrasted, and selects the performance state in three kinds of suboptimums relay selection scheme
Closest to a kind of suboptimum relay selection scheme of the performance state of the optimal relay selection scheme, as described actual complete
The relay selection scheme of duplexing relay system.
It is preferred that, the device also includes:
Deployment module 5, for after the relay selection scheme of the actual full duplex relaying system is determined, passing through
Different relaying numbers are set in the actual full duplex relaying system in the actual full duplex relaying system
Disconnected probability is analyzed, and determines the relaying number corresponding to the outage probability minimum, and according to the relaying number to described
Actual full duplex relaying system carries out corresponding relaying deployment.
Accordingly, the presetting module 1 includes:
First default unit 11, the channel status for whole channel links in the full duplex relaying system
Information, presets and obtains the optimal relay selection scheme;
Second default unit 12, for the source node in the full duplex relaying system to via node
The channel condition information of channel link and the via node are preset to the channel condition information of the channel link of destination node
Obtain minimax relay selection scheme;
3rd default unit 13, for the source node in the full duplex relaying system to via node
The channel condition information of the channel condition information of channel link and the self-interference channel link of via node, presets and obtains part
Relay selection scheme;
4th default unit 14, for the self-interference link of the via node in the full duplex relaying system, in advance
If obtaining self-interference relay selection scheme;
Wherein, the minimax relay selection scheme, part relay selection scheme and self-interference relay selection scheme are
Suboptimum relay selection scheme.
Corresponding, the computing module 2 includes:
First computing unit 21, for calculating four kinds of relay selection selection schemes, is obtained in each respectively
After the system channel capacity C of selection scheme, wherein,In formula,For source node to via node
Link signal to noise ratio or Signal Interference and Noise Ratio,Signal to noise ratio or signal interference for the link of source node to destination node
Noise ratio;
Second computing unit 22, for the system channel capacity based on each relay selection scheme, calculates and obtains institute
State the outage probability of each relay selection schemeIn formula, * is represented in difference respectively
After the probability of selection scheme, R0Expression system needs the minimum capacity thresholding reached.
In embodiments of the invention three, a kind of optimal and three have been preset based on decoding retransmission protocol in presetting module
The relay selection scheme of suboptimum is planted, and is obtained in computing module according to independent same distribution rayleigh fading channel in four kinds
After the outage probability of selection scheme, the channel status of actual measurement is then combined by analysis module, finally in comparison module
Interruption performance to four kinds of relay selection schemes carries out com-parison and analysis, the one of the closest optimal relay selection scheme of selection
Plant suboptimum relay selection scheme and be used as final relay selection scheme, so reduce required channel condition information, and then
The complexity of relay selection method is reduced, the systematic function compared to the relay selection scheme of amplification forwarding gets a promotion;And
And simulation analysis have been carried out to the relay selection scheme under actual conditions by computer in the present invention, it is possible to achieve according to
The requirement of different geographical and different clients, using rational relay selection scheme, can both meet the service quality of different user
Requirement, additionally it is possible to it is cost-effective.And then by the present invention realize effective lifting system performance and QoS of customer with
And save the purpose of equipment cost.
The embodiment of each in this specification is described by the way of progressive, and what each embodiment was stressed is and it
Between the difference of his embodiment, each embodiment identical similar portion mutually referring to.For being filled disclosed in embodiment
For putting, because it is corresponded to the method disclosed in Example, so description is fairly simple, related part is referring to method portion
Defend oneself bright.
The foregoing description of the disclosed embodiments, enables professional and technical personnel in the field to realize or using the present invention.
A variety of modifications to these embodiments will be apparent for those skilled in the art, defined herein
General Principle can realize in other embodiments without departing from the spirit or scope of the present invention.Therefore, originally
Invention is not intended to be limited to the embodiments shown herein, and is to fit to special with principles disclosed herein and novelty
The consistent most wide scope of point.