A modified joint uplink-downlink opportunistic scheduling for Quality of Service guarantees

Quality of Service (QoS) is a very important metric in wireless communication systems, where both Uplink (UL) and Downlink (DL) connections request strict QoS demands in terms of rate, delay, etc. for their proper operation. The development of wireless communications standards and the emergence of new interactive and conversational services with bi-directional QoS requirements changes the scheduling context from a link-level to a system level. To this end, this paper presents a joint UL-DL bandwidth allocation approach that considers outage as the main QoS parameter to be minimized. The well-known opportunistic scheduling algorithm is first modified to account for the UL-DL coupling and a mathematical expression of the outage probability is derived. Then the expression is employed in the joint UL-DL bandwidth allocation problem. The formulated problem is shown to be a convex optimization problem. Simulation results demonstrate the merits of the proposed approach compared to traditional techniques.