Research On The Key Technology Of The MAC Layer Of The LTE-A Terminal Software Baseband

As the evolved version of the fourth generation wireless communication systems(LTE),LTE-Advanced system has greatly improved in the peak data rate,resource allocation efficiency,system bandwidth and system average spectral efficiency.TD-LTE system,as with China's independent intellectual property rights,developed based on TD-SCDMA communication system which has been applicated in extensive commercial business.TD-LTE system has been widely studied and applied in the world.TD-LTE-A system is TD-LTE enhancement technology,it introduced some key technology on the basis of the LTE network architecture,such as carrier-aggregation,double flue technology and so on.This key techniques can improve the system bandwidth and transmission rate.To further enhance the performances of data transmission speed and data utilization rate,after completed module design and realization of PDCP layer,RLC layer and MAC layer in LTE-A protocol stack system,it focuses on the key technologies of MAC layer research in this paper.The key technologies of MAC layer includes resource uplink/downlink scheduling,carrier-aggregation,double flue technology,trigger mechnism and the process of data transmission and other.Resource scheduling of Uplink and downlink is managed by the base station and terminal in the data transmission process.Carrier aggregation is aggregating continuous or discrete LTE component carrier into the lager bandwidth LTE-Advanced system carrier,it can improve the utilization of the discrete spectrum effectively,it can also realizes the smooth transition of the LTE system to LTE-Advanced system.Double flue transport mechanism is sharing component carrier by using the same piece of PRB resources,at the same time through multi-antenna to transport data independently.Trigger mechanism can according to the amount of data decided to trigger single or double flue transmission effectively.After research and analysis of the standard protocols of LTE-Advanced system,the PDCP layer,the RLC layer and MAC layer of the data link layer were studied respectively,finally finished the base station and the terminal design,realizes the key technologies of carrier aggregation and double flue technology and resource scheduling of MAC layer,including the framework design and flow chart design and also code design.Excited the key technologies of MAC layer above,against the problem that data transmission between the layers frequently,on the other hand,in order to reduce the redundant memory,storage mechanism of LTE-A protocol is studied.An "mBlk-clBlk-cluster"data structure is suggested to give“zero copy”memory managements in the protocol.Realized the fast transmission of the data between each layer and reduced the memory occupancy.Finally,through building a test platform to complete the functional verification of LTE-Advanced protocol.The protocol stack can realize the data transmission with speeds of 300Mbps on uplink and 600Mbps on downlink by testing at the main frequency of 500MHz,respectively.Meanwhile,it can realize transmission of single or double flue transmission.The results show that the multi carrier protocol stack can meet the function of LTE-Advanced.