CN105979556B - Take into account the fair relay selection method of rate and energy efficiency - Google Patents
Take into account the fair relay selection method of rate and energy efficiency Download PDFInfo
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- CN105979556B CN105979556B CN201610230574.7A CN201610230574A CN105979556B CN 105979556 B CN105979556 B CN 105979556B CN 201610230574 A CN201610230574 A CN 201610230574A CN 105979556 B CN105979556 B CN 105979556B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/02—Access restriction performed under specific conditions
- H04W48/06—Access restriction performed under specific conditions based on traffic conditions
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/20—Selecting an access point
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a kind of for taking into account the fair relay selection method of rate and energy efficiency in cooperation communication system.Purpose user selection；Purpose user initializes candidate relay set；Purpose user traverses candidate relay, achievable rate when calculation base station is transmitted through candidate relay to purpose user；MSkIt calculates the dispatch weight of all candidate relays and finally selectes relaying；Carry out data transmission according to selected relaying；MSkThe data of base station transmission are directly received without relay cooperative；MSkThe average transmission rate of all mobile subscribers is updated using proportional fair algorithm；This slot transmission terminates, and into next transmission cycle, repeats above step, completes fair relay selection.The present invention considers energy information in relay scheduling weight, avoids these nodes and exceedingly provides assistance for purpose user, so as to improve energy efficiency, therefore, system time is extended, and can be used for cooperation communication system relay selection, guarantees user's communication.
Description
Technical field
The invention belongs to fields of communication technology, further relate to fair relay selection method, specifically a kind of to take into account speed
The fair relay selection method of rate and energy efficiency, for the relay selection in cooperation communication system.
Background technique
In order to solve traditional point-to-point wireless transmission power system capacity, coverage area and in terms of deposit
Limitation, and to multiple antenna communication provide space diversity be used, collaboration communication (Cooperative
Communication) technology is come into being.Using the technology, the terminal of multiple single antenna cooperates to form virtual antenna arrays
Column, to obtain the improvement of communication performance.Typical relay cooperative mode include amplification forwarding (Amplify-and-Forward,
AF) and decoding forwards (Decode-and-Forward, DF).
In actual cooperation communication system, often there is the relay node of multiple candidates, how to select in suitable
After being the important problem in one, the field.The design of relay selection strategy can be based on up to data rate, node power/energy
The performances such as consumption, the bit error rate.Such as Barus B is in " On the SEP ofcooperative diversity with
Opportunistic relaying choosing is proposed in opportunistic relaying " (IEEE Communications Letters, 2008)
Strategy is selected, criterion is maximized with end-to-end transmission rate, relay node is selected；Altubaishi E S etc. is in " A
novel distributed fair relay selection strategy forcooperative wireless
One is devised based on AF in system " (IEEE International Conference on Communications, 2012)
The distributed relay selection strategy of kind, and outage probability equal in relay node mean power realize low complexity under conditions of constraint
The relay selection of degree；Li P Q etc. is in " Transmit power minimization for outage-constrained
relay selection overRayleigh-fading channels”(IEEE Communications Letters,
2014) a kind of relay selection strategy based on DF is proposed in, under conditions of outage probability and energy constraint, to minimize system
Transmission power is that optimization aim realizes relay selection.
In cooperation communication system of the mobile station as relaying, since mobile subscriber is usually energy constraint, move
Family is employed when other users that cooperate complete data communication, the transmission of its own business and the ratio of total energy consumption can
Amount efficiency is also an important performance indicator.Also, the node consumption self-energy for participating in relaying helps other users transmission
Data cause the energy consumption of itself to be accelerated, and system time reduces.
In the research of existing collaboration communication, user/relaying Combination selection and in terms of Shortcomings, it is specific to wrap
Include: network lifetime is lower, and user's energy efficiency is not high, cannot comprehensively consider two aspect of rate and energy efficiency.
Summary of the invention
The present invention, which is directed to exist in the prior art, cannot optimize comprehensively considering for rate and energy, propose that one kind takes into account rate
With the fair relay selection method of energy efficiency.
1. a kind of fair relay selection method for taking into account rate and energy efficiency, which is characterized in that be with t-th of time slot
Example, includes the following steps:
(1) base station carries out purpose user choosing according to the ratio between the average transmission rate in terminal achievable rate and transmission cycle
It selects, selectes purpose user MSk。
(2) candidate relay set Ω is initialized with purpose user:
MSkCount itself and relaying MS available in base stationiBetween channel status, purpose user MSkTo available around it
Relaying is screened, that is, compares MSiWith MSkBetween channel status hk,i, base station and MSkBetween channel status hk,0, only retain full
Sufficient condition | hk,i| > | hk,0| available relaying as candidate relay, and by hk,iBase station BS is fed back to, | | indicate modulus value fortune
It calculates.
(3) purpose user traverses candidate relay, achievable rate when calculation base station is transmitted through candidate relay to purpose user:
(3a) candidate relay MSiCalculation base station BS to MSiLink rate, and feed back to purpose user MSk；
(3b)MSkCalculate itself and MSiLink rate, and the information is fed back into base station；
(3c) is according to above-mentioned two rate values, MSkIt calculates and determines that time slot divides factor-alphaiValue, time slot divide factor-alphai
One transmission time slot is divided into two stages, wherein first stage base station is to MSiTransmit data, Shi Changwei αiTS, second-order
Section MSiTo MSkTransmit data, Shi Changwei (1- αi)TS,TSFor the length of a time slot；
(3d)MSkFactor-alpha is divided according to time slotiValue obtain MSiWhen as relaying, base station is through MSiTo MSkWhat is transmitted is reachable
Rate；
(3e)MSkJudge whether all candidate relays participate in the reachable of link when cooperation to purpose user itself in acquisition system
Rate thens follow the steps (4), otherwise, returns to step (3a) if all obtained.
(4) purpose user MSkIt calculates the dispatch weight of all candidate relays and finally selectes relaying:
(4a)MSkAccording to base station through MSiTo MSkThe achievable rate and purpose user MS of transmissionkBefore (t-1) a transmission week
The ratio between average transmission rate in phase and the ratio between transmission process maximum energy consumption and relay forwarding energy consumption determine in each candidate
After dispatch weight；
(4b)MSkCompare the dispatch weight of each relaying in candidate relay set, in selection scheduling weight in Maximum alternative
After being denoted as MSl, calculation base station is directly to MSkThe through rate of transmissionIt is relayed to MS to compare base stationkThe reachable speed of transmission
RateWith base station directly to MSkThe through rate of transmissionIfStep 5 is gone to, otherwise goes to step 6.
(5) the relaying MS selected according to step 4lCorresponding αl, a transmission cycle is divided into two stages；?
One stage, base station send the data to the selected MS of step 4l；In second stage, MSlTo purpose user MSkForward data,
The transmission of this time slot data is completed, step 7 is gone to.
(6)MSkDirectly receive the data that base station is sent.
(7) purpose user MSkThe average transmission rate of all mobile terminals is updated using proportional fair algorithm.
(8) this slot transmission terminates, and into next transmission cycle, repeats above step.
The basic ideas that the present invention realizes are that base station carries out purpose user's selection first, then obtain and analyze purpose use
Family channel status, the terminal using channel status better than purpose subscriber channel state is as candidate relay, secondly according to each candidate
The dispatch weight of relaying carries out relay selection.Transmission process is divided into two stages, divides the factor for a transmission week according to time slot
Phase is divided into two stages.First stage, base station send data to selected relaying；In second stage, relay to its service
Purpose user forwards data.
Compared with the prior art, the present invention has the following advantages:
In the present invention relaying energy efficiency and system time can be obtained under the premise of safeguarding relay well fairness
The performance improvement of aspect.
One, is avoided since the present invention is to data rate and energy efficiency has been comprehensively considered in the calculating of relaying dispatch weight
Data-rate information is only considered in previous relay scheduling weight, so that the energy efficiency of the candidate relay of system is improved.
Two, pass through since the present invention is to data rate and energy efficiency has been comprehensively considered in the calculating of relaying dispatch weight
Trunk subscriber energy information is included in the calculating of dispatch weight, exceedingly provides association so as to avoid these nodes for other users
It helps, so extending network lifetime.
Detailed description of the invention
Attached drawing 1 is the schematic diagram of applicable system model of the present invention；
Attached drawing 2 is flow chart of the invention；
Attached drawing 3 is that the rate of the method for the present invention and ratio justice relay selection method compares in the case where different signal-to-noise ratio
Analogous diagram；
Attached drawing 4 be in SNR=10dB the life span of the method for the present invention and ratio justice relay selection method with
Initialize the situation of change analogous diagram of gross energy.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to embodiments, to the present invention
It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to
Limit the present invention.
Embodiment 1
System model schematic diagram that the present invention is applicable in as shown in Figure 1, including a base station (Base station,
BS), L mobile station (Mobile station, MS), configuration single antenna, all users are according to time division multiple acess (Time
Division multiple access, TDMA) mode downlink broadcast channel is shared, i.e., in a transmission time slot
BS only sends data to a user, it is assumed that and all MS can be used as relay node and other users helped to forward data, and
An and relaying at most one user of service.Assuming that system is in the working condition of flat fading, thus the movement of cellular cell
User (Mobile station, MS) and relay node can obtain complete channel state information (CSI).Relay node is adopted
With half-duplex operation mode.By each transmission time slot (TS) it is divided into αi(t)TS(1- αi(t))TSTwo parts, cooperation mode are adopted
(DF) is forwarded with decoding, in αi(t)TSIn time slot, BS sends data x to relayingk；In (1- αi(t))TSIn time slot, relaying docking
The signal of receipts is decoded, and the data by recompiling then are forwarded to purpose userMeetWherein subscript k indicates the purpose user MS being sent tokData, E () expression ask the mathematics phase
It hopes.The transmission power of base station is PT, relaying is P for the power of data forwardingR。
The present invention is a kind of fair relay selection method for taking into account rate and energy efficiency, referring to fig. 2, with t-th of time slot
For, include the following steps:
(1) base station carries out purpose user choosing according to the ratio between the average transmission rate in terminal achievable rate and transmission cycle
It selects, selectes purpose user MSk。
(2) purpose user MS is usedkTo initialize candidate relay set Ω:
MSkCount itself and relaying MS available in base station BSiBetween channel status, purpose user MSkIt can use around it
Relaying screened, that is, compare MSiWith MSkBetween channel status hk,i, base station and MSkBetween channel status hk,0, only retain
Meet condition | hk,i| > | hk,0| available relaying as candidate relay, and by hk,iFeed back to base station BS, that is, this step is complete
Cheng Shi, candidate relay set Ω should meet condition comprising all | hk,i| > | hk,0| relaying, | | indicate the operation of modulus value.
(3) purpose user traversal candidate relay, achievable rate when calculation base station is transmitted through candidate relay to purpose user,
That is purpose user needs to calculate the achievable rate of all candidate relays in step 1:
(3a) candidate relay MSiCalculation base station BS to MSiLink rate, and feed back to purpose user MSk；
(3b)MSkCalculate itself and MSiLink rate, and the information is fed back into base station；
(3c)MSkAccording to base station BS to MSiLink rate and MSkWith MSiLink rate the two rate values, MSk
It calculates and determines that time slot divides factor-alphaiValue, time slot divide factor-alphaiOne transmission time slot is divided into two stages, wherein the
One stage base station is to MSiTransmit data, Shi Changwei αiTS, second stage MSiTo MSkTransmit data, Shi Changwei (1- αi)TS,TSFor
The length of one time slot；That is, a transmission time slot length of system is TS, when a slot length is exactly two stage
It is the sum of long: αiTS+(1-αi)TS=TS；
(3d)MSkFactor-alpha is divided according to time slotiValue MS is calculatediWhen as relaying, base station is through candidate relay MSiTo
Purpose user MSkThe achievable rate of transmission；
(3e)MSkJudge whether all candidate relays participate in the reachable of link when cooperation to purpose user itself in acquisition system
Rate thens follow the steps (4), otherwise, returns to step (3a) if all obtained.I.e. purpose user must obtain
The achievable rate of whole candidate relays just can, to calculate candidate relay dispatch weight.
(4) purpose user MSkIt calculates the dispatch weight of all candidate relays and finally selectes relaying, i.e., it is final selected
Relaying is selected in candidate relay:
(4a)MSkAccording to base station through candidate relay MSiTo purpose user MSkThe achievable rate and purpose user MS of transmissionk's
Before the ratio between average transmission rate in (t-1) a transmission cycle and the ratio between transmission process maximum energy consumption and relay forwarding energy consumption
Determine the dispatch weight of each candidate relay, that is, combine in the calculating of dispatch weight of both rate and energy because
Element.
(4b)MSkCompare the dispatch weight of each relaying in candidate relay set, in selection scheduling weight in Maximum alternative
After being denoted as MSl, relaying is finally had selected at this time, and calculation base station is directly to MSkThe through rate of transmissionCompare in the warp of base station
After to MSkThe achievable rate of transmissionWith base station directly to MSkThe through rate of transmissionIfIt is i.e. relayed
The achievable rate of cooperation transmission is bigger, goes to and executes step 5, conversely, i.e. base station is directly to the through rate of purpose user transmission
It is bigger, then it goes to and executes step 6.
(5) the relaying MS selected according to step 4lCorresponding αl, a transmission cycle is divided into two stages:
One stage, base station send the data to the selected MS of step 4l；In second stage, MSlTo purpose user MSkForward data,
The transmission of this time slot data is completed, this step is that selected relay in base station carries out data transmission to purpose user, goes to and executes step
Rapid 7.
(6)MSkDirectly receive the data that base station is sent.
(7) purpose user MSkThe average transmission rate of all mobile terminals is updated using proportional fair algorithm.
(8) this slot transmission terminates, and into next transmission cycle, repeats above step.
The forwarding energy expenditure information of the relay node is included in scheduling in the calculating of relay scheduling weight in the present invention
The calculating of weight will do it compensation to the dispatcher of relay node, maintain the fairness of relay selection, so as to improve its energy
Efficiency, realizes the fairness of trunk subscriber, and extends network lifetime.
Embodiment 2
The fair relay selection method of rate and energy efficiency is taken into account with embodiment 1, wherein MS in step (3c)kAccording to
BS to MSiLink rate and MSkWith MSiLink rate, MSkIt calculates and determines that time slot divides factor-alphaiValue, time slot divide because
Sub- αiOne transmission time slot is divided into two stages, wherein first stage base station is to MSiTransmit data, Shi Changwei αiTS, the
Two-stage MSiTo MSkTransmit data, Shi Changwei (1- αi)TS,TSFor the length of a time slot:
Work as MSiWhen as relaying, by the relayed MS of BSiTo purpose user MSkAchievable rateBS is limited to MSiWith
MSiTo MSkA poor jump in double bounce transmission, poor one jumps the bottleneck for being also referred to as link rate, and expression formula is,
For elimination gap, time slot is adaptively adjusted according to the channel status of two-hop link and divides the factor, is adjusted as the following formula
It is whole,
α is obtained after abbreviationiExpression formula it is as follows,
Time slot divides factor-alphaiIt is related with the factors such as channel status and noise variance.Wherein, h is usedi,0Indicate BS and MSk(i∈
Channel status between Ω)；Use hk,iIndicate MSi(i ∈ Ω) and MSkBetween channel status；The transmission power of base station is PT；Relaying turns
The power for sending out data is PR；N0Indicate white Gaussian noise variance；|·|2Indicate modulus value square operation；log2() indicate ask with
2 be the log operations at bottom.P in this exampleT=PR=100mw.
This example divides factor-alpha to time slotiDynamic adjustment, BS is through MSiTo MSkAchievable rate be no longer limited by double bounce compared with
Small rate, and the presence of bottleneck will lead to the waste of the communication resource, the present invention according to the channel status of two-hop link adaptively
It adjusts time slot and divides factor-alphai, also the communication resource is made to be fully used.
Embodiment 3
The fair relay selection method of rate and energy efficiency is taken into account with embodiment 1-2, MS described in step (3d)kRoot
MS is obtained according to the value that time slot divides the factoriWhen as relaying, base station is through MSiTo MSkThe achievable rate of transmission, the link is up to speed
Steps are as follows for the calculating of rate:
When bottleneck is eliminated, calculates link achievable rate and selects any one formula in following formula:
Or
Wherein, h is usedi,0Indicate BS and MSiChannel status between (i ∈ Ω)；Use hk,iIndicate MSi(i ∈ Ω) and MSkBetween
Channel status；The transmission power of base station is PT；The power of relay forwarding data is PR；N0Indicate white Gaussian noise variance；|·|2
Indicate modulus value square operation；log2() indicates to seek the log operations with 2 bottom of for.
Work as αiAfter determination, link achievable rateGround calculation formula is simplified, and can be chosen according to the actual situation
Any one in formula is stated to be calculated.
Embodiment 4
The fair relay selection method of rate and energy efficiency is taken into account with embodiment 1-3, step (4a) MSkIt is passed through according to base station
MSiTo MSkThe achievable rate and purpose user MS of transmissionkBefore average transmission rate in (t-1) a transmission cycle when pass
The ratio between defeated process maximum energy consumption and relay forwarding energy consumption determine that the dispatch weight of each candidate relay, the dispatch weight of relaying are pressed
It is obtained according to following formula:
Wherein, wi(t) candidate relay MS in t-th of transmission cycleiDispatch weight；Rk(t) indicate base station through MSiTo MSk
The achievable rate of transmission that is to say in embodiment three(t-1) a transmission cycle purpose user MS before expressionkIt is flat
Equal transmission rate, γiFor weight factor, γi∈(0,1),γiIt is MS for selected relayingiWhen, so that the maximum value of dispatch weight；
Namely during Project Realization each candidate relay weight factor γiDifference needs to find out for each candidate relay
Make γ corresponding to its dispatch weight maximumi；
Ei,k(t)=PR[1-αi(t)]TS
Ei,k(t) energy consumed by trunk subscriber forwarding data in t-th of transmission cycle is indicated；The transmitting function of base station
Rate is PT；The power of relay forwarding data is PR；
Data rate and energy efficiency have been comprehensively considered in the calculating of relay scheduling weight of the present invention, by candidate relay user
Energy information is included in the calculating of dispatch weight, and the user's dispatch weight for having neither part nor lot in collaboration data increased, and dispatcher can be corresponding
Increase, that is, obtains certain recompense, good node exceedingly provides assistance for other users to avoid channel status, to change
It is apt to its energy efficiency, so extending network lifetime.
Embodiment 5
The fair relay selection method of rate and energy efficiency is taken into account with embodiment 1-4,2 couples of present invention realize referring to attached drawing
The step of be specifically described.
Step 1, base station carries out purpose user according to the ratio between the average transmission rate in terminal achievable rate and transmission cycle
Selection:
K indicates the label of the user selected, Ri(t) user's achievable rate is indicated,(t-1) a transmission week before expression
Average transmission rate in phase.
Step 2, purpose user initializes candidate relay set Ω:
MSkCount itself and relaying MS available in base stationiBetween channel status, purpose user MSkTo available around it
Relaying is screened, that is, compares MSiWith MSkBetween channel status hk,iWith base station and MSkBetween channel status hk,0, only retain
Meet condition | hk,i| > | hk,0| candidate relay, and by hk,iBS is fed back to, | | indicate the operation of modulus value.
Step 3, purpose user traverse candidate relay, and calculation base station through candidate relay to purpose user transmit when it is reachable
Rate:
(3a)MSiCalculate BS to MSiLink rate, and feed back to MSk, the calculation formula of the link rate information is as follows,
BS to MSiData rate are as follows:
Wherein, h is usedi,0Indicate BS and MSiChannel status between (i ∈ Ω)；The transmission power of base station is PT；N0Indicate Gauss
White noise variance；|·|2Indicate modulus value square operation；log2() indicates to seek the log operations with 2 bottom of for.
(3b)MSkCalculate itself and MSiLink rate, and the rate information is fed back into base station, the link rate information
Calculation formula is as follows:
Wherein, h is usedk,iIndicate MSi(i ∈ Ω) and MSkBetween channel status；The power of relay forwarding data is PR；N0Table
Show white Gaussian noise variance.
(3c) is according to base station BS to MSiLink rate and MSkWith MSiLink rate the two rate values, MSkMeter
It calculates and determines that time slot divides factor-alphaiValue, time slot divide factor-alphaiRelated to this non-slotted channel status, time slot divides factor-alphai
One transmission time slot is divided into two stages, wherein first stage base station is to MSiTransmit data, Shi Changwei αiTS, second-order
Section MSiTo MSkTransmit data, Shi Changwei (1- αi)TS,TSFor the length of a time slot:
Work as MSiWhen as relaying, by the relayed MS of BSiTo purpose user MSkAchievable rateBS is limited to MSiWith
MSiTo MSkThe bottleneck of a poor jump in double bounce transmission, a poor jump i.e. link transmission rate, expression formula be,
For elimination gap, time slot is adaptively adjusted according to the channel status of two-hop link and divides the factor, is adjusted as the following formula
It is whole,
Wherein, h is usedi,0Indicate BS and MSiChannel status between (i ∈ Ω)；Use hk,iIndicate MSi(i ∈ Ω) and MSkBetween
Channel status；The transmission power of base station is PT；The power of relay forwarding data is PR；N0Indicate white Gaussian noise variance.
(3d)MSkFactor-alpha is divided according to time slotiValue obtain MSiWhen as relaying, base station is through MSiTo MSkWhat is transmitted is reachable
The calculation formula of rate, the link achievable rate is as follows:
When bottleneck eliminate when, according to the following formula in any one calculate link achievable rate:
Or
Wherein, h is usedi,0Indicate BS and MSiChannel status between (i ∈ Ω)；The transmission power of base station is PT；Use hk,iIt indicates
MSi(i ∈ Ω) and MSkBetween channel status；The power of relay forwarding data is PR；N0Indicate white Gaussian noise variance；|·|2Table
Show modulus value square operation.
(3e) judges purpose user MSkWhether in acquisition system all links average transmission rate, that is, purpose uses
Family must traverse each element in candidate relay set, if so, thening follow the steps 4, otherwise, execute step (3a).
Step 4, purpose user calculates dispatch weight and finally selectes relaying:
(4a)MSkAccording to base station through MSiTo MSkThe achievable rate and purpose user MS of transmissionkBefore (t-1) a transmission week
The when transmission process of average transmission rate in phase relays the ratio between maximum energy consumption and relay forwarding energy consumption to determine each candidate
The dispatch weight of the dispatch weight of relaying, relaying is obtained according to following formula:
Wherein, wi(t) cooperating relay MS in t-th of transmission cycleiDispatch weight；Rk(t) indicate base station through MSiTo MSk
The achievable rate of transmission；(t-1) a transmission cycle purpose user MS before expressionkAverage transmission rate, γiFor weight
The factor, γi∈(0,1),γiIt is MS for selected relayingiWhen, so that the maximum value of dispatch weight.
Ei,k(t)=PR[1-αi(t)]TS
Ei,k(t) energy consumed by trunk subscriber forwarding data to be transferred in t-th of transmission cycle is indicated；The hair of base station
Penetrating power is PT；The power of relay forwarding data is PR。
(4b)MSkCompare the dispatch weight of each relaying in candidate relay set, in selection scheduling weight in Maximum alternative
After being denoted as MSl, relay MSlThe relaying namely finally selected, calculation base station is directly to MSkThe through rate of transmissionIt is through
Rate calculations formula is as follows:
It is relayed to MS to compare base stationkThe achievable rate of transmissionWith base station directly to MSkThe through rate of transmission
IfStep 5 is gone to, otherwise goes to step 6.
Step 5, the relaying MS selected according to step 4lCorresponding αl, a transmission cycle is divided into two stages；?
First stage, base station send the data to the selected MS of step 4l；In second stage, MSlTo purpose user MSkForwarding number
According to going to step 7.
Step 6, MSkIt directly receives base station and transmits data, the through rate of purpose user is greater than the transmission speed of relayed cooperation
Rate does not need relay cooperative at this time.
Step 7, using proportional fair algorithm, MSkUpdate all mobile terminal MSsiAverage transmission rate
The formula that rate updates is as follows:
Wherein,Indicate the mobile subscriber MS in t-th of transmission cycleiAverage transmission rate；Ri(t) it indicates
Mobile terminal is selected as transmission rate when relaying；Mobile terminal i.e. mobile subscriber；δc∈ [0,1] indicates t-th of transmission
MS in periodkData rate Rk(t) to the influence degree of its Mean Speed or dispatch weight；Take δc=0.99, K indicate system
The number of middle cooperating relay；The present invention takes-(1- ηc)Rk(t) as the correction value for participating in user's Mean Speed that data are assisted, ηc
∈ [0,1] is known as excitation factor, reflects and participates in the excitation density that data are assisted, η to mobile subscribercSmaller, excitation density is bigger.Wherein, EiIt (0) is the primary power of mobile subscriber,For the residue of t-th of time slot initial time
Energy.
Step 8, this slot transmission terminates, and into next transmission cycle, repeats above step, completes fair relaying choosing
It selects.
The present invention realizes the fair relay selection for taking into account rate and energy efficiency, has comprehensively considered two side of rate and energy
The factor in face, improves network lifetime.
Embodiment 6
The fair relay selection method of rate and energy efficiency is taken into account with embodiment 1-5, below with reference to present invention emulation effect
Fruit figure is described further.
It is described further in conjunction with using effect of the following emulation experiment to the embodiment of the present invention:
Simulated conditions: the P of cooperative relay systemT=PR=PR=100mw, whole nodes are configured using single antenna, due to TS
Length it is related with practical application, in order to adapt to different communication systems, the present invention returns statistical time to slot length
One change processing；Subscriber channel coefficient is produced using Jakes simulation model at wherein maximum doppler frequency takes 6Hz, synthesis path number
N is 514；
Attached drawing 3 is total number of users L=10 user primary power E provided in an embodiment of the present inventionk(0)=103J, signal-to-noise ratio
(SNR) the system velocity schematic diagram not obtained simultaneously using distinct methods；In fig. 3, the curve with asterisk indicates the present invention
The emulation of method, the curve with circle indicate the emulation of ratio fair method.In attached drawing 3, ratio justice relay selection method with
System velocity maximum turns to target dispatch user, can obtain optimal rate capability, method proposed by the present invention --- it takes into account
The fair relay selection method of rate and energy efficiency can obtain the system velocity inferior to ratio justice relay selection method, this is
Since trunk subscriber energy information is included in the calculating of dispatch weight by the mechanism, cooperating relay forward information to be passed energy consumption this
Factor increases in the accounting of dispatch weight, and purpose user is more prone to the selection cooperating relay that low energy consumption, then cooperating relay
Energy efficiency will increase, therefore the information rate of purpose user can reduce accordingly.
Attached drawing 4 is number of users L=10 provided in an embodiment of the present invention, using the network survivability of distinct methods when SNR=5dB
Time diagram；
The definition of network lifetime (Lifetime, LT) is, when occur in network first node energy deplete or
When less than energy needed for transmission signal, the total time of network normal operation；
Assuming that any mobile subscriber MSiPrimary power be Ei(0), the dump energy of t-th of time slot initial time isThe MS in time slot tiRequired (consumption) energyFor,
Wherein, PRIndicate the transmission power of relaying, PCIt is flat to indicate that terminal carries out data transmission/reception period circuit consumption
Equal power, TsFor the length of a time slot.As λ=1, purpose user directly receives signal from BS；As λ=1- αk(t) it when, uses
Data of the relay reception from BS are passed through at family.User MSkDump energy become
Attached drawing 4 provides number of users K=10, the system time that difference relay selection mechanism obtains when SNR=5dB.It is horizontal
Coordinate is the initialization gross energy of total user in system, is set as PRTsIntegral multiple, ordinate indicate to TsNormalized system
System life span, normalized network lifetime are equivalent with the number of transmissions.In figure 4, the curve with asterisk indicates this hair
The emulation of bright method, the curve with circle indicate the emulation of ratio fair method.By attached drawing 4 as it can be seen that being relayed using ratio justice
Selection method, the cooperating relay that channel quality is good may be frequently called with high probability, then this node energy consumption is larger,
Cause its system time short.According toCalculation formula, purpose user receives energy consumed by data in time slot
It measures and receives base station data less than trunk subscriber and forward consumed energy to purpose user, therefore use and take into account rate and energy
The fair relay selection method of efficiency, by the way that trunk subscriber energy information to be included in the calculating of dispatch weight, by rationally reducing
The dispatch weight of these trunk subscribers exceedingly provides assistance so as to avoid these nodes for other users, it is raw to extend system
Deposit the time.Therefore, the system time of the fair relay selection method of rate and energy efficiency is taken into account better than in ratio justice
After selection method.
To sum up, of the invention a kind of for taking into account the fair relay selection side of rate and energy efficiency in cooperation communication system
Method.Purpose user selection；Purpose user initializes candidate relay set；Purpose user traverses candidate relay, and calculation base station is through waiting
Choose achievable rate when transmitting to purpose user；Purpose user MSkCalculate the dispatch weight of all candidate relays and final
Selected relaying；Carried out data transmission according to selected relaying；MSkThe data of base station transmission are directly received without relay cooperative；Using
Proportional fair algorithm, purpose user MSkUpdate the average transmission rate of all mobile subscribersThis slot transmission terminates, into
Enter next transmission cycle, repeat above step, completes fair relay selection.The present invention considers energy in relay scheduling weight
Information is measured, these nodes is avoided and exceedingly provides assistance for purpose user, so as to improve energy efficiency, therefore, system is raw
Depositing the time is extended, and can be used for cooperation communication system relay selection, guarantees user's communication.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (5)
1. a kind of fair relay selection method for taking into account rate and energy efficiency, which is characterized in that by taking t-th of time slot as an example, packet
Include following steps:
(1) base station carries out purpose user selection, choosing according to the ratio between the average transmission rate in terminal achievable rate and transmission cycle
Determine purpose user MSk；
(2) candidate relay set Ω is initialized with purpose user:
MSkCount itself and relaying MS available in base stationiBetween channel status, purpose user MSkTo relaying available around it
It is screened, that is, compares MSiWith MSkBetween channel status hk,iWith base station and MSkBetween channel status hk,0, only retain and meet
Condition | hk,i| > | hk,0| available relaying as candidate relay, and by hk,iBase station BS is fed back to, | | indicate modulus value fortune
It calculates；
(3) purpose user traverses candidate relay, achievable rate when calculation base station is transmitted through candidate relay to purpose user:
(3a) candidate relay MSiCalculation base station BS to MSiLink rate, and feed back to purpose user MSk；
(3b)MSkCalculate itself and MSiLink rate, and feed back to base station；
(3c)MSkAccording to BS to MSiLink rate and MSkWith MSiLink rate, MSkIt calculates and determines that time slot divides factor-alphai
Value, time slot divide factor-alphaiOne transmission time slot is divided into two stages, wherein first stage base station is to MSiTransmit number
According to Shi Changwei αiTS, second stage MSiTo MSiTransmit data, Shi Changwei (1- αi)TS, TSFor the length of a time slot；
(3d)MSkFactor-alpha is divided according to time slotiValue obtain MSiWhen as relaying, base station is through MSiTo MSkThe reachable speed of transmission
Rate；
(3e)MSkJudge whether all candidate relays participate in the achievable rate of link when cooperation in acquisition system for it, if entirely
Portion obtains, and thens follow the steps (4), otherwise, returns to step (3a)；
(4) purpose user MSkIt calculates the dispatch weight of all candidate relays and finally selectes relaying:
(4a)MSkAccording to base station through MSiTo MSkThe achievable rate and purpose user MS of transmissionkBefore in (t-1) a transmission cycle
The ratio between average transmission rate and the ratio between transmission process maximum energy consumption and relay forwarding energy consumption determine the tune of each candidate relay
Spend weight；
(4b)MSkCompare the dispatch weight of each relaying in candidate relay set, Maximum alternative relays in selection scheduling weight, note
Make MSl, calculation base station is directly to MSkThe through rate of transmissionIt is relayed to MS to compare base stationkThe achievable rate of transmission
With base station directly to MSkThe through rate of transmissionIfIt goes to and executes step 5, otherwise go to and execute step 6；
(5) the relaying MS selected according to step 4lCorresponding αl, a transmission cycle is divided into two stages；At first
Stage, base station send the data to the selected MS of step 4l；In second stage, MSlTo purpose user MSkData are forwarded, are completed
The transmission of this time slot data, goes to and executes step 7；
(6) purpose user MSkDirectly receive the data that base station is sent；
(7)MSkThe average transmission rate of all mobile subscribers is updated using proportional fair algorithm；
(8) this slot transmission terminates, and into next transmission cycle, repeats above step.
2. the fair relay selection method according to claim 1 for taking into account rate and energy efficiency, which is characterized in that step
MS in (3c)kAccording to BS to MSiLink rate and MSkWith MSiLink rate, MSkIt calculates and determines that time slot divides factor-alphai's
Value, time slot divide factor-alphaiOne transmission time slot is divided into two stages, wherein first stage base station is to MSiTransmit data,
Shi Changwei αiTS, second stage MSiTo MSkTransmit data, Shi Changwei (1- αi)TS, TSFor the length of a time slot:
Work as MSiWhen as relaying, by the relayed MS of BSiTo purpose user MSkAchievable rateBS is limited to MSiAnd MSiIt arrives
MSkA poor jump, expression formula are in double bounce transmission,
For elimination gap, α is adaptively adjusted according to the channel status of two-hop linki, it adjusts as the following formula,
α is obtained after abbreviationiExpression formula it is as follows,
Wherein, h is usedi,0Indicate BS and MSiChannel status between (i ∈ Ω)；Use hk,iIndicate MSi(i ∈ Ω) and MSkBetween channel
State；The transmission power of base station is PT；The power of relay forwarding data is PR；N0Indicate white Gaussian noise variance；|·|2It indicates
Modulus value square operation；log2() indicates to seek the log operations with 2 bottom of for；
3. the fair relay selection method according to claim 1 for taking into account rate and energy efficiency, which is characterized in that step
MS described in (3d)kFactor-alpha is divided according to time slotiValue obtain MSiWhen as relaying, base station is through MSiTo MSkWhat is transmitted is reachable
The calculation expression of rate, the link achievable rate is as follows,
When bottleneck is eliminated, calculates link achievable rate and selects any one formula in following formula:
Or
Wherein, h is usedi,0Indicate BS and MSiChannel status between (i ∈ Ω)；Use hk,iIndicate MSi(i ∈ Ω) and MSkBetween channel
State；The transmission power of base station is PT；The power of relay forwarding data is PR；N0Indicate white Gaussian noise variance；|·|2It indicates
Modulus value square operation；log2() indicates to seek the log operations with 2 bottom of for.
4. the fair relay selection method according to claim 1 for taking into account rate and energy efficiency, which is characterized in that step
(4a)MSkAccording to base station through MSiTo MSkThe achievable rate and purpose user MS of transmissionkBefore it is flat in (t-1) a transmission cycle
The ratio between equal transmission rate and the ratio between transmission process maximum energy consumption and relay forwarding energy consumption determine the scheduling of each candidate relay
The dispatch weight of weight, relaying is obtained according to following formula:
Wherein, wi(t) cooperating relay MS in t-th of transmission cycleiDispatch weight；Rk(t) indicate base station through MSiTo MSkTransmission
Achievable rate；Indicate purpose user MSiBefore (t-1) a transmission cycle average transmission rate, γiFor weight because
Son, γi∈ (0,1), γiIt is MS for selected relayingiWhen, so that the maximum value of dispatch weight；
Ei,k(t)=PR[1-αi(t)]TS
Ei,k(t) energy consumed by trunk subscriber forwarding data in t-th of transmission cycle is indicated；The transmission power of base station is
PT；The power of relay forwarding data is PR。
5. the fair relay selection method according to claim 1 for taking into account rate and energy efficiency, which is characterized in that step
(7)MSkThe average transmission rate of all mobile subscribers is updated using proportional fair algorithm,
The formula that rate updates is as follows:
Wherein,Indicate the average transmission rate of each mobile subscriber in t-th of transmission cycle；Ri(t) it indicates mobile to use
Family is selected as transmission rate when relaying；δc∈ [0,1] indicates MS in t-th of transmission cyclekData rate Rk(t) flat to it
The influence degree of equal rate or dispatch weight；The number of cooperating relay in K expression system；The present invention takes-(1- ηc)Rk(t) conduct
Participate in the correction value for user's Mean Speed that data are assisted, ηc∈ [0,1] is known as excitation factor, and reflection participates in number to mobile subscriber
According to the excitation density of assistance, ηcSmaller, excitation density is bigger,Wherein, Ei(0) for mobile subscriber's
Primary power,For the dump energy of t-th of time slot initial time.
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| CN104113365A (en) * | 2014-07-10 | 2014-10-22 | 广西师范大学 | A selection method of multi-antenna relay nodes in a cooperation communication system |
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