The Research And Implement Of Adaptive Schedule Algorithm Of MAC Layer In Broadband Wireless Access System

Broadband Wireless Access will become the main driving forces of mobile communications development.The Third Generation Partnership Project(3GPP)has initiated a standardization process about the evolution of the existed third generation (3G)systems which named as 3GPP Long Term Evolution(LTE).The objective was to develop a framework for the evolution of the 3GPP radio-access technology towards a high-data-rate,low-latency and packet-optimized radio-access technology. The orthogonal frequency division multiplex(OFDM)is considered as a most promising multi-carrier modulation technique and is proposed to be applied to the Third Generation Long Term Evolution(3G LTE)downlink transmission.Intense research has therefore focused on adaptive packet schedule schemes for OFDM systems,aiming at optimizing overall system throughput by dynamic and efficient resource block allocation,fast power control,adaptive transmission rate assignment, and etc.A lot of the existing schedule algorithms are presented to solve the dilemma of the system throughput and users fairness,while little of them concern the Quality of Service(QoS)indicators.To offer the connection-oriented service for subscriber, 3GPP System Architecture(SA)Work Group Two(WG2)propose to establishing a end-to-end QoS control mechanism,which can be dynamically managed through MAC messages to accommodate the dynamic service demand.In this paper,the cross-layer scheduling algorithms of QoS-aware multi-service for multi-users OFDM system are investigated,involving balancing between the system throughput and user fairness among the service with the same or similar QoS requirement.Furthermore, the impact of space resource on scheduling algorithm in antenna array system is investigated.With the introduction of the space resources,the dimension of resource allocation is expanded to four,including time resources,frequency resources, transmission order and space resources.As a result,the complexity of the scheduling algorithm is exponential growth. In this paper,OFDM-based LTE system is investigated.Adaptive scheduling method concerning QoS requirement of Medium Access Control(MAC)layer is designed and is implemented by using C programme.In addition,a VoIP-based half-persistence resource allocation algorithm is proposed to reducing amount of control signaling on the air interface,and a single-user with multiple code word optimal algorithm is also proposed to avoiding waste of scheduling resource and improving system frequency efficiency.C language is adopted in Software design under embedded system programming environment Code Composer Studio(CCS). Integration testing result exhibited that the data transmission rate over air interface achieved by proposed algorithm can meet the objective of LTE standard.The feasibility and effectiveness of the proposed resource allocation algorithm have also been testified.