Rate-Adaptive Concurrent Transmission Scheduling Schemes for WPANs With Directional Antennas

We consider the concurrent transmission scheduling problem in a rate-adaptive wireless personal area network (WPAN). In such networks, the physical layer can adaptively change modulation and coding schemes based on the interference level in the environment and accordingly change the data rate. The scheduling problem is to assign users to time slots so that the total throughput is maximized. The challenge is that the achieved data rate of one flow is limited by the interference from other flows in the same slot, which is unknown until the schedule is known. We propose to discretize data rate into several distinct levels supported by the PHY layer and then use a linear programming model to find the highest rate level a flow can achieve. The same model is extended to consider a mixture of omni-directional antennas and directional antennas with heterogeneous transmitting power. The simulation results show that the proposed algorithms outperform the previous work for adaptive-rate transmission scheduling in both throughput and fairness.