Distributed arbitration scheme for on‐chip CDMA bus with dynamic codeword assignment

Abstract

Several code‐division multiple access (CDMA)‐based interconnect schemes have been recently proposed as alternatives to the conventional time‐division multiplexing bus in multicore systems‐on‐chip. CDMA systems with a dynamic assignment of spreading codewords are particularly attractive because of their potential for higher bandwidth efficiency compared with the systems in which the codewords are statically assigned to processing elements. In this paper, we propose a novel distributed arbitration scheme for dynamic CDMA‐bus‐based systems, which solves the complexity and scalability issues associated with commonly used centralized arbitration schemes. The proposed arbitration unit is decomposed into multiple simple arbitration elements, which are connected in a ring. The arbitration ring implements a token‐passing algorithm, which both resolves destination conflicts and assigns the codewords to processing elements. Simulation results show that the throughput reduction in an optimally configured dynamic CDMA bus due to arbitration‐related overheads does not exceed 5%.

Keywords

• cdma bus
• distributed arbitration
• dynamic spreading codeword assignment
• multiprocessor soc