In this paper an implementation of iterative joint detection for multiple access interference using direct-sequence code-division multiple-access (DS-CDMA) is presented. Results for multiple field programmable gate array (FPGA) platforms and multiple technology nodes for synthesized application specific integrated circuits (ASIC) are presented. The joint detection is performed using a generalized version of interleave-division multiple-access (IDMA) known as partition spreading (PS) CDMA. Decoding is performed using iterative methods from turbo and sum-product decoding. The synthesized ASIC system demonstrates a maximum aggregate throughput of 197 Mb/s for a fully loaded 50-user system, while the implemented FPGA 50-user system has a maximum aggregate throughput of 119 Mb/s. Index Terms-Digital circuits, direct-sequence code-division multiple access, field programmable gate arrays, interference cancellation.

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Computationally efficient joint detection in CDMA packetized communication is considered. The joint detection is based on iterative cancellation and utilizes only low complexity individual data receivers. The savings in complexity compared to other alternatives proposed in the literature is due to an encoding scheme known as partition spreading that can be decoded using algorithms that are similar to well-known turbo and sum-product decoding. Besides having a low computational complexity, the technique offers near-far resistant performance and can achieve higher system loads than conventional CDMA. The low complexity of these component receivers allows a large number of users to be implemented onto a single FPGA. A Virtex-IV on a Lyrtech Development board is used to implement a test bed for this PS-CDMA system. The implementation focuses on area optimization to give 50 users in a single Virtex-IV with 84% slice utilization and a maximum aggregate throughput of 192Mb/s. The measured performance of this prototype is compared against theoretical results on PS-CDMA in environments with varying power levels. An FPGA resource-performance analysis is given.

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