Jointly Opportunistic Beamforming and Scheduling (JOBS) for Downlink Packet Access

Opportunistic scheduling (OS) has been proposed as a technique to improve the downlink throughput of high speed packet systems. OS attempts to use the time varying propagation channels between the base station (BS) and the mobile stations (MSs) when they reach their peak rate capability and defer using channels when in bad state. It exploits the fact that the propagation channels between the BS and the MSs fade independently and that many data services tolerate a certain amount of delay and delay jitter. However, when the fading is slow in comparison with an acceptable packet delay, or weak, OS is not very useful. In such cases, opportunistic beamforming (OBF), a recently proposed scheme, may offer additional gains. OBF is a "natural" enhancement to OS. The enhancement amounts to replacing the BS antenna with multiple antennas and implementing an algorithm that generates a different radiation pattern every timeslot. In this paper we propose to tie the sequence of radiation patterns to the waiting times of the served MSs. We show through simulations that the scheme we propose leads to both, reduced probabililty of excessive packet delay and improved throughput. This can be achieved by processing of the feedback the BSs receive from the MSs, with no, or minor additional signaling on the air interface.