| These days the 4G technology has been utilized as an implementa-tion of base stations by telecom operators on a worldwide scale, and FDD-LTE and TD-LTE have been widely used. Although each of the standards enjoys its merits in practical applications, TD-LTE shows its strong flexibility of uplink and downlink resource allocation.In Chapter 3 of this paper, according to the downlink physical layer standard in 3GPP TD-LTE protocol, we give detailed explanation of the downlink transmitting procedure at the base station and the simulation process of channel estimation and equalization module. From the per-spective of programming design, we analyze the implementation of each downlink channel and each processing module. Besides, we describe the optimization designs for procedures such as modulation to reduce time complexity in practical programming process. The optimization designs can improve the efficiency of the overall downlink procedure in physical layer.In Chapter 4, we introduce the implementation and optimization of the downlink program at the base station on a TMS320C6678-type DSP development board. After the code migration to the DSP platform, we optimize the program codes to adapt the hardware by fixed-point algo-rithm, cyclic trim, and so on. Moreover, we compare the execution time of programs at different optimization levels to prove the effect and sig-nificance of the optimization. In addition, we also propose a mul-ti-antenna smart switching scheme, which can reduce the power con-sumption of the base station in specific environments, providing an ap-plication value especially to battery-powered mobile base stations. |
