DSP Array Design For Baseband Signal Processing In Mobile WiMAX System

Based on the IEEE802.16e air interface standard, the mobile WiMAX is All-IP architecture of packet division multiplexing, which takes the advantage of both cellular mobile communication system and broadband wireless metropolitan area networks. Mobile WiMAX also supports high speed data transmission in stationary, pedestrian and fast-moving scenarios, and seamless handover between heterogeneous networks. With the employment of Software Defined Radio (SDR) techniques, a wireless communications platform is established to implement the key technologies such as channel coding, Orthogonal Frequency Division Multiple Access (OFDMA), space time processing and distributed antenna. Due to complex mobile environment, large-scale matrix operation and various services convergence, the wireless algorithm complexity in mobile WiMAX gets greatly increased, how to provide a kind of high performance digital signal processor is becoming a challenge. With the background of "the Research on Innovative Mobile Communications Platform", the baseband signal processing design of mobile WiMAX using picoArray DSP is explored in this paper.The research focuses on the hardware infrastructure design and wireless algorithm modules implementation of mobile WiMAX baseband signal processing. In aspect of baseband design, firstly, technical objective of the innovative platform's physical layer is analyzed in this paper. Then, the characteristics of various digital signal processors such as ASIC, FPGA, DSP are compared, the picoArray DSP processor is employed in Base Staion (BS) and Mobile Terminal (MT) hardware architecture, which provides a software platform to interlink wireless algorithm modules. According to extremely broad bandwidth of local bus and powerful calculation capability of picoArray, a dynamic subcarrier allocation algorithm called picoArray proportional fairness algorithm is proposed,which is capable of achieving balance of system capacity and access fairness. A simulation system is established to evaluate and verify the algorithm, based on the simulation result, the algorithm's critical parameter is suggested to be selected from a proper interval, within which, the algorithm performance is optimized. In aspect of key techniques, the exploring of the principle of OFDM, the research of space-time coding and decoding rules , the analysis of system capacity of centralized MIMO, and the deduction of the common channel matrix structure of centralized MIMO and distributed MIMO are contained in this paper as well.Meanwhile, in this paper, IEEE802.16e protocol stack, channel coding and decoding technical specifications, OFDMA standard symbol and frame structure, picoArray technology and its typical products are introduced. As for processor chip, the features of DSP array element of picoArray, software development environment, available programming resources and system development process are described detailedly. At last, an efficient pipeline FFT structure is implemented using picoArray DSP.