Rapid Prototyping of a Fixed-Throughput Sphere Decoder for MIMO Systems

A field-programmable gate array (FPGA) implementation of a new detection algorithm for uncoded multiple input-multiple output (MIMO) systems based on the complex version of the sphere decoder (SD) is presented in this paper. The algorithm overcomes the main drawback of the SD: its variable throughput, depending on the noise level and the channel conditions. Implementation results show that the algorithm is highly parallelizable and can be fully pipelined. This reduces the use of FPGA resources and results in a constant throughput, which is significantly higher than previous SD implementations at a cost of a very small bit error ratio (BER) degradation.