Coded space-time-frequency OFDM employing adaptive multiple antenna selection (AdMAS) in broadband wireless access

In this paper we present an adaptive multiple antenna selection (AdMAS) employing a maximum of 4 transmit (4 Tx) and 1 receive (1 Rx) antenna in conjunction with coded space-time-frequency (STF) orthogonal frequency division multiplexing (OFDM) over broadband wireless access IEEE 802.16 Stanford Interim University (SUI) channels. Our coded STF-OFDM is a product of phase-shift-keying (PSK) modulated STF block code which has been concatenated with convolutional codes of rate 1/3, constant length of 8, and code generator of [225 331 367]. In transmitting data we adaptively select channel(s) with least fade and turn off the most faded channel(s) at the transmitter side. We determine levels of fading of the channel from each transmitter based on the calculated second moment of the channel impulse response (CIR). We also compare results when level of fading is based on the mean of the CIR. We tested our scheme in the most severe case of SUI channel, i.e SUI6. Results show that the employment of AdMAS does not give significant gain at low-level constellations. However significant gain is observed at higher constellations which makes our proposed scheme a potential scheme to be employed for the high data rate system.