Extending IEEE 802.11a to incorporate iterative turbo decoding and transmit delay diversity

The paper explores the use of iterative turbo decoding and transmit delay diversity to improve the performance of the IEEE 802.11a standard. The paper describes the modifications required to the forward error correction (FEC) block to support binary turbo codes (BTC) with Gray mapping for the various physical (PHY) layer modes. The paper also studies the simple use of two antennas at the access point (AP) with a single antenna at the mobile terminal (MT). This configuration offers downlink (DL) improvement through the use of transmit delay diversity. Software simulated PHY layer bit error rate (BER) and packet error rate (PER) results are presented for the proposed methods and compared with those of an unaided transceiver. Finally, by use of a link adaptation scheme, the operating range and throughput performance for the enhanced IEEE 802.11a modes are compared and discussed.