A baseband processor for software defined radio terminals.

Abstract

Software defined radio (SDR) is a technical effort to use programmable hardware in wireless communication systems so that various protocols can be easily supported by software. However, using programmable hardware for SDR terminals has been unachievable because of their tight power budget and high demand on computation capability. The main theme of this thesis is to design a power efficient programmable baseband processor for the SDR. This thesis analyzed most contemporary wireless communication protocols both in system and algorithm levels. System level analysis is to see the interactions between algorithms and the algorithm level analysis is to investigate the computation patterns of the algorithms comprising baseband operations. Based on the characterization results, this thesis proposes chip multiprocessor architecture, whose PEs have both parallel and scalar datapaths. Multiprocessor architecture is proposed to exploit the algorithm level parallelism. Both the parallel and scalar datapaths are used because baseband processing is a combination of parallelizable and scalar computations. For additional enhancements, three novel schemes are applied to the SIMD style parallel datapath: macro instructions, macro pipelining, and the staggered execution of computation units. Macro instruction is to combine several primitive instructions into one. It reduces system power by eliminating unnecessary register accesses. The macro pipelining is to form a pipeline by cascading hardware blocks for common macro operations. It enhances system throughput by concurrently executing the macro operations. The staggered execution is to shift the operation timing of computation units of the parallel datapath. It improves system throughput and power efficiency by replacing complex N x N crossbar switches with simple N x 1 switches. The power efficiency of the proposed architecture is evaluated through a Verilog model and commercial tools. The proposed architecture consumes only 150 mW while providing W-CDMA 2Mbps packet data service. The contributions of this thesis are to analyze the characteristics of baseband operations from the perspective of architecture and to adapt the three novel schemes for system enhancement.