A feasibility study of two user downlink transmission for IS-856 system

This work presents a feasibility study for a possible extension to the IS-856 (HDR, 1xEV-DO) standard in terms of allowing two user transmission in the system downlink. Since the 1.25 MHz bandwidth of this system is not perfectly frequency flat, the one user at a time scheme is no longer optimal in theory. Furthermore, the two user transmission allows for more granular data rate selection by the base station. The extension requires minimum changes to the physical layer of the IS-856 standard and is compatible with the existing physical layer specifications with no additional overhead required in the downlink. A packet scheduling algorithm that is able to take advantage of the two user transmission is presented. The performance of the proposal is studied with physical layer and system simulations. The simulation results indicate that the proposed extension modestly increases the average system data rate that may not justify the required complexity.