Research On Energy-Efficiency Priority Based Resource Allocation Schemes In Cognitive Radio Network

Cognitive radio(CR)improves the spectral-efficiency(SE)of the limited spectrum resources via dynamic spectrum access.Secondary users(SU)detect the spectrum holes of primary user(PU)and access the authorized spectrum in an appropriate way to maximize the spectral-efficiency.With the enhancement of spectrum utilization and the popularization of the concept of green communication,energy-efficiency(EE)in cognitive radio network(CRN)has gradually become research hotspot.EE-based multi-user multi-resource dynamic allocation is an effective way to implement EE-SE tradeoff in CRN.EE priority based resource allocation schemes in CRN are investigated in this dissertation.The dynamic resource allocation of subcarriers,power and bits are studied with the objective of EE in the multi-user spectrum sharing environment.On the basis of that,the dissertation further investigates the tradeoff between EE and SE,and obtains the EE-SE tradeoff relationship curve.Specific researches are provided as below.EE priority based multi-user subcarrier and power joint allocation scheme in CRN is studied.A joint optimization algorithm for subcarrier and power with EE priority based water-filling factor aided search(EE-WFAS)is proposed in the scenarios of multiple SUs sharing PU licensed spectrum resources.Firstly,the proposed algorithm constructs a constrained optimization problem,with the target of total energy-efficiency maximization and the constraints of SU transmission power control,PU interference power control and SU information transmit rate constraint.Then,the optimization problem can be solved via EE priority based subcarrier assignment and WFAS power allocation.In the process of subcarrier assignment,the subcarriers are allocated to SUs with priority of energy efficiency in accordance with the channel gain of SUs and the limitation of information transmit rate.Power allocation process further analyzes the optimization model,transforms the non-convex optimization problem into a convex optimization problem and obtains the optimal power via a combination of bisection search of the Lagrangian multipliers and the EE-WFAS method.Simulation results and a comparison with the subcarrier and power equal allocation algorithm show that the proposed algorithm enhances energy-efficiency approximately 1.2kbit/J.Multi-user subcarrier and bit joint allocation scheme with EE-SE tradeoff in CRN is investigated.Firstly,CRN EE-SE weighted tradeoff optimization function is constructed.Then,the relationship between SU transmit power and bit error rate as well as the number of bits are analyzed with the implementation of M-ary quadrature amplitude modulation(MQAM)and M-ary phase shift keying(MPSK)modulation.In the consideration of SU transmission fairness ratio,the subcarriers are assigned to each SU in accordance with channel gain.After subcarrier assignment,two classical bit allocation algorithms,namely,Hughes-Hartogs and Chow,are implemented to allocate information bits in each subcarrier.Finally,the tradeoff relationship between EE and SE is given,which can effectively balance EE and SE in CRN.This dissertation initially analyzes and researches the EE priority based resource allocation schemes in CRN.Research provides significant value for the further related works.