Receive diversity versus space time block codes in IEEE 802.11a and ETSI HIPERLAN/2

The aim of this study is to enhance the performance of the current 802.11a and HIPERLAN/2 standards by employing multiple antennas at the transmitter, receiver, or both. These systems use coded orthogonal frequency division multiplexing (COFDM) technology and provide channel adaptive data rates of up to 54 Mbits/s. However, the performance of both standards can be improved, especially in environments with high root mean square (RMS) delay spread where uncoded data suffers from significant interchannel interference. Current techniques such as receive diversity and space time block codes (STBC) are presented as a simple solution to enhance these standards. The paper explains the characteristics of these technique and results are presented in order to discuss their merits and demerits. The paper also determines which technique offers the highest performance without the addition of significant complexity at the receiver. Receive diversity techniques should be considered for inclusion in devices requiring large coverage and high data rates, and STBC for inclusion in fixed access point devices.