Development of an OFDM based high speed wireless LAN platform using the TI C6x DSP

Coded orthogonal frequency division multiplexing (COFDM) is currently specified in all three of the world's 5 GHz wireless LAN standards (HIPERLAN/2, IEEE 802.11a and MMAC HiSWANa). This technology was chosen due to its robustness at high data rates in a frequency selective multipath channel. Each standard operates using adaptive subband quadrature amplitude modulation (QAM) and offers a maximum data rate of 54 Mbits/s over a 20 MHz channel. This paper describes a real-time DSP implementation of an asynchronous OFDM based high speed WLAN system. The software reconfigurable OFDM based platform is developed around the Texas Instruments fixed point TMS320C6201 DSP. The physical layer DSP performance is evaluated and compared for an indoor channel against floating point C++ based simulations. Data throughput and complexity estimates are generated from the resulting hardware platform. Finally, a video based communications application is developed to operate over the demonstrator. Results indicate that the fixed point DSP solution can operate within 0.5 dB of the floating point simulation in an AWGN channel. For the indoor fading channel, an implementation loss of around 2.5 dB was observed.