Research On Resource Allocation In Distributed MIMO Systems

With the recent advances of smart grid and the increase of data communication services,it becomes the development trend of the future mobile communication that the wireless communication system has the energy renewable ability and satisfies the development concept of green communication.For one thing,the energy harvesting and cooperation techniques are promising solutions to alleviating energy consumption pressure by collecting energy from ambient environment and exchanging energy among base stations or nodes,thus becoming increasingly popular.Therefore,it is necessary to re-study resource management strategies such as power allocation and energy cooperation in the existing wireless communication systems.For another,Multiple Input and Multiple Output(MIMO)technique can increase both the information transmission rate and the energy efficiency in the distributed antenna system(DAS).This paper mainly studies the resource allocation and management problems in the DAS with hybrid energy supply,including the distributed wireless sensor network(WSN)system and the distributed cloud-radio access network(C-RAN)system.The main work and innovations of the paper are listed as follows.Firstly,the theoretical basis of wireless transmission in distributed MIMO systems is provided.We analyze the statistical characteristics of wireless channels in wireless communication networks through simulation,including path loss,shadow fading,and small-scale fading models.For the convenience of follow-up research,three common methods for solving fractional programming problems are briefly introduced.In addition,we elaborate the Lyapunov theory together with related concepts such as Lyapunov drift,Lyapunov optimization,and virtual queues,which serve as the basis for subsequent research.Next,we investigate a long-term energy efficiency optimization problem in hybrid energy supplied CRAN.Particularly,both of the instantaneous quality of service(Qo S)requirements and time-averaged limits are considered in the problem.By introducing Lyapunov framework together with the drift-plus-penalty method,we propose an energy-efficiency based power allocation and energy cooperation(EE-PAEC)scheme by jointly optimizing both of the sustainable energy and the grid power.The power allocation scheme contributes to optimal long-term EE with the deterministic upper bound of the data queue backlog,without requiring any prior knowledge on the traffic arrival or the amount of harvested energy for each remote radio unit(RRU).Furthermore,simulation results demonstrate the performance advantage of energy cooperation,and show that the proposed scheme can provide a balanced trade-off between utility and stability.Furthermore,it can be expanded to more comprehensive scenarios with RRU selection as well as random channel state.,which is conductive to implementation in practice.Then,we study the joint utility maximization problem for WSN in consideration of energy harvesting and cooperation.An upper bound on the Lyapunov drift is derived for the network stability.Then,we propose an energy harvesting and energy transfer,data transmission,power control,routing and scheduling(EDPR)online algorithm by combining Lyapunov optimization technique with drift-plus-penalty method and perturbation technique.It contributes to optimal utility in a distributed manner by jointly optimizing the energy storage and power allocation policy with the battery capacity limitation,the data rate bound,the networkstability requirement,and the energy-availability constraint.In addition,the proposed algorithm is able to achieve a balanced trade-off between network utility and queue backlog,with no need for any statistical information about dynamic systems and no concern of curse of dimensionality under large queue backlog.Furthermore,simulation results also show the practicality of the proposed algorithm in real implementation since data transmission has a linear relationship with battery life.Finally,the theoretical numerical analysis and derivation are carried out based on the aforementioned resource allocation strategy algorithms proposed in the hybrid energy supply distributed system.Detailed explanations and mathematical proofs are given in terms of queue stability,queue bound and achievable system performance.Through numerical analysis,it is founded that the performance achieved by the EEPAEC algorithm and the EDPR algorithm is consistent with the simulation results.