A kind of optimal D2D intermediate position user access method based on energy efficiencyTechnical field
The present invention relates to a kind of optimal D2D intermediate position user access method based on energy efficiency, belongs to wireless communicationTechnical field.
Background technique
With the rapid development of the communication technology, the requirement to communication is also higher and higher, to communication under different scenesThere is different requirements, in the communication resource increasingly deficient today, the utilization rate and transmission rate for improving the communication resource are communication systemsProblem to be solved in system, due to being limited by frequency spectrum resource and energy resource, biography that traditional communication network can be providedDefeated speed is unable to satisfy the demand of user, therefore recent domestic experts and scholars are by D2D (Device to Device) technologyIt is combined with Cellular Networks.D2D technology can effectively promote the availability of frequency spectrum and energy efficiency, D2D is made with the combination of Cellular NetworksTo relay, and it can solve user and access problem, the problem of main research is using D2D as user under the network relayed hereinThe correlative study of access, in numerous and complicated heterogeneous network, there are a plurality of types of base stations to provide access service for user, noSame access network has different characteristics；Therefore, reasonable selection access network is just particularly important according to demand, will be generalLogical user terminal is relayed as D2D, can improve the access experience of cell edge user.In some documents that can have been foundAlthough proposing user's access based on energy efficiency, just under the scene of single D2D relaying, target is more single；ButIt is typically all more relay scenes in reality, there can be the problems such as relay selection.
Based on above research, the present invention invents a kind of optimal relaying based on energy efficiency in the case where more D2D relay environmentUser's Access Algorithm of position, the transmission performance of the verified preferable balancing user of algorithm energy, effectively improves user'sAccess experience.
Summary of the invention
The present invention provides a kind of optimal D2D intermediate position user access method based on energy efficiency, it is existing to solveUser accesses that the signal fadeout occurred is big, and access experience is poor in communication, and efficiency of transmission is not high larger with communication signaling expense etc. to askTopic.
The technical scheme is that a kind of optimal D2D intermediate position user access method based on energy efficiency, describedSpecific step is as follows for optimal D2D intermediate position user access method based on energy efficiency:
Step1, the relay collection that D2D relaying is established according to the model of place of foundation；
Step2, optimal D2D relaying is selected from relay collection using optimal relay selection algorithm；
Step3, it calculates separately out user the direct of base station is directly arrived by energy efficiency under D2D repeater mode and userEnergy efficiency under mode；
Step4, the energy efficiency of both of which calculated in Step3 is compared；
If the energy under the energy effciency ratio Direct Model under repeater mode is high, selects repeater mode to carry out user and connectEnter；
If the energy under the energy effciency ratio repeater mode under Direct Model is high, selects Direct Model to carry out user and connectEnter；
If repeater mode is identical with Direct Model energy efficiency, then judges the transmission rate of both of which；Selection transmissionThe high mode of rate carries out user's access；
Step5, circulation step Step2-4 select optimal relaying and optimal mode to carry out user's access to determine.
In the step Step2, optimal relay selection algorithm: for the relay selection algorithm based on distance, when user relaysWith base station when on same straight line, most possibly there is optimal relaying；
The step Step2 is shown in specific step is as follows:
Step2.1, the power loss that formula calculates each relaying is lost according to relay power；
Step2.2, optimal selection is carried out to intermediate position, first establishes the optimal mathematical model of energy efficiency；
Step2.3, optimal location of the D2D relaying relative to base station is solved according to the optimal mathematical model of energy efficiency；
Step2.4, optimal D2D intermediate position can be obtained relative to the optimal location of base station according to D2D relaying.
In the step Step2.1, formula is lost in relay power are as follows:
Wherein, K is antenna gain；The respectively path loss constant of cellular link and D2D link；τ is noiseCompare loss late；R is to be relayed to base station transmission rate, and W is channel width；N0For noise power spectral density；du,0,BjFor user to baseIt stands the distance of B, dBThe distance of base station B is relayed to for D2D；Relay power loss is expressed as: pu,B(R,dB)；Equal under repeater modeAverage noise power of the path loss to base station of relaying than upper antenna gain.
In the step Step2.2, energy efficiency optimal mathematical model isRB,maxFor user's peak transfer rate, pu,B(R,dB) it is relay powerLoss, PcFor the power loss of device link.
In the step Step2.3, D2D relays the objective function of the optimal location relative to base station are as follows:
Wherein, dBIt (r) is the corresponding objective function of intermediate position；Target letter of the function representation user to intermediate positionNumber；dBFor base station between user on intermediate position region referring to function zero-point；For the target letter of intermediate position to base stationNumber；The solution of respective function is solved to get the specific optimal location relative to base station is relayed to D2D.
In the step Step3:
The energy efficiency of Direct Model are as follows:
The energy efficiency of repeater mode are as follows:
Wherein, Ru,0,BFor the transmission rate of user to base station, Ru,i,BFor the transmission rate under repeater mode；PcFor equipment chainThe power loss on road；PuFor the transmission power of user；PrFor the transmission power of D2D relaying.
In the step Step4:
Transmission rate under Direct Model are as follows:
Transmission rate under repeater mode are as follows:
Wherein gu,0,BFor the channel gain of base station, gu,iFor the channel gain that user to D2D relays, gi,BIt is relayed to for D2DThe channel gain of base station；τ leads for snr loss；W is channel width；N0For noise power spectral density, PuFor the transmitting function of userRate；PrFor the transmission power of D2D relaying.
The beneficial effects of the present invention are:
The present invention first determines the position of D2D relaying, optimal D2D relaying is found out, further according to energy efficiency and transmission rateCarry out user's access；The present invention can preferable balancing user transmission performance；
The position that the present invention is first relayed according to user location and D2D, on the basis of combining energy efficiency, balance efficiency andUnder the premise of ensureing minimum transmission rate, carries out user and access selection；The invention is it is only necessary to know that intermediate position and user locationCan carry out.Through simulating, verifying, but the difficulty of the algorithm and complexity are smaller than existing Access Algorithm, and the algorithm can haveEffect reduces the signaling overheads of communication system, the effective access experience for improving user.
Detailed description of the invention
Fig. 1 is present invention communication connection selection flow diagram；
Fig. 2 is communication scenes illustraton of model of the invention；
Fig. 3 is optimal D2D intermediate position schematic diagram of the invention.
Specific embodiment
Embodiment 1: as shown in Figure 1-3, a kind of optimal D2D intermediate position user access method based on energy efficiency, instituteStating the optimal D2D intermediate position user access method based on energy efficiency, specific step is as follows:
Step1, the relay collection that D2D relaying is established according to the model of place of foundation；Communication scenes illustraton of model such as Fig. 2 instituteShow；
Step2, optimal D2D relaying is selected from relay collection using optimal relay selection algorithm；
Step3, it calculates separately out user the direct of base station is directly arrived by energy efficiency under D2D repeater mode and userEnergy efficiency under mode；
Step4, the energy efficiency of both of which calculated in Step3 is compared；
If the energy under the energy effciency ratio Direct Model under repeater mode is high, selects repeater mode to carry out user and connectEnter；
If the energy under the energy effciency ratio repeater mode under Direct Model is high, selects Direct Model to carry out user and connectEnter；
If repeater mode is identical with Direct Model energy efficiency, then judges the transmission rate of both of which；Selection transmissionThe high mode of rate carries out user's access；
Step5, circulation step Step2-4 select optimal relaying and optimal mode to carry out user's access to determine.
Further, in the step Step2, optimal relay selection algorithm: for the relay selection algorithm based on distance, whenMost possibly there is optimal relaying when on same straight line in user's relaying and base station；
As shown in figure 3, being optimal D2D intermediate position schematic diagram, relay selection algorithm is according to existing based on distanceRelay selection algorithm, the algorithm is only it needs to be determined that the position of user and relaying can be chosen；User is to this straight line of base stationOn most possibly there is optimal relaying, first measure user to relaying, be relayed to base station, the distance of user to base station and use respectivelydu,i、dB,i、du,o,BIt indicates；According to du,i、dB,i、du,o,BDetermine the position of relaying and the opposite base station of user；Further according to relaying andThe position of user utilizes the optimal formula founding mathematical models of energy efficiency, then calculates the optimal solution of mathematical model, can be obtainedOptimal D2D relaying.
The step Step2 is shown in specific step is as follows:
Step2.1, the power loss that formula calculates each relaying is lost according to relay power；
Step2.2, optimal selection is carried out to intermediate position, first establishes the optimal mathematical model of energy efficiency；
Step2.3, optimal location of the D2D relaying relative to base station is solved according to the optimal mathematical model of energy efficiency；
Step2.4, optimal D2D intermediate position can be obtained relative to the optimal location of base station according to D2D relaying.
Further, in the step Step2.1, formula is lost in relay power are as follows:
Wherein, K is antenna gain；The respectively path loss constant of cellular link and D2D link；τ is noiseCompare loss late；R is to be relayed to base station transmission rate, and W is channel width；N0For noise power spectral density；du,0,BjFor user to baseIt stands the distance of B, dBThe distance of base station B is relayed to for D2D；Relay power loss is expressed as: pu,B(R,dB)；Equal under repeater modeAverage noise power of the path loss to base station of relaying than upper antenna gain.
Further, in the step Step2.2, energy efficiency optimal mathematical model isRB,maxFor user's peak transfer rate, pu,B(R,dB) it is relay powerLoss, PcFor the power loss of device link.
Further, in the step Step2.3, D2D relays the objective function of the optimal location relative to base station are as follows:
Wherein, dBIt (r) is the corresponding objective function of intermediate position；Target letter of the function representation user to intermediate positionNumber；dBFor base station between user on intermediate position region referring to function zero-point；For the objective function of intermediate position to base station；The solution of respective function is solved to get the specific optimal location relative to base station is relayed to D2D.
Further, in the step Step3:
The energy efficiency of Direct Model are as follows:
The energy efficiency of repeater mode are as follows:
Wherein, Ru,0,BFor the transmission rate of user to base station, Ru,i,BFor the transmission rate under repeater mode；PcFor equipment chainThe power loss on road；PuFor the transmission power of user；PrFor the transmission power of D2D relaying.
Further, in the step Step4:
Transmission rate under Direct Model are as follows:
Transmission rate under repeater mode are as follows:
Wherein gu,0,BFor the channel gain of base station, gu,iFor the channel gain that user to D2D relays, gi,BIt is relayed to for D2DThe channel gain of base station；τ leads for snr loss；W is channel width；N0For noise power spectral density, PuFor the transmitting function of userRate；PrFor the transmission power of D2D relaying.
Above in conjunction with attached drawing, the embodiment of the present invention is explained in detail, but the present invention is not limited to above-mentionedEmbodiment within the knowledge of a person skilled in the art can also be before not departing from present inventive conceptPut that various changes can be made.