Hardware Emulation of Wideband Correlated Multiple-Input Multiple-Output Fading Channels

A low-complexity hardware emulator is proposed for wideband, correlated, multiple-input multiple-output (MIMO) fading channels. The proposed emulator generates multiple discrete-time channel impulse responses (CIR) at the symbol rate and incorporates three types of correlation functions of the subchannels via Kronecker product: the spatial correlation between transmit or receive elements, temporal correlation due to Doppler shifts, and inter-tap correlation due to multipaths. The Kronecker product is implemented by a novel mixed parallel-serial (mixed P-S) matrix multiplication method to reduce memory storage and to meet the real-time requirement in high data-rate, large MIMO size, or long CIR systems. We present two practical MIMO channel examples implemented on an Altera Stratix III EP3SL150F FPGA DSP development kit: a 2-by-2 MIMO WiMAX channel with a symbol rate of 1.25 million symbols/second and a 2-by-6 MIMO underwater acoustic channel with 100-tap CIR. Both examples meet real-time requirement using only 12-14% of hardware resources of the FPGA.