A two-level bandwidth allocation scheme is proposed for a slotted Time-Division Multiple Access high data rate relay satellite communication link to provide efficient and fair channel utilization. The long-term allocation is implemented to provide per-flow/per-user Quality-of-Service guarantees and shape the average behavior. The time-varying short-term allocation is determined by solving an optimal timeslot scheduling problem based on the requests and other parameters. Through extensive simulations, the performance of a suitable MAC protocol with two-level bandwidth allocation is analyzed and compared with that of the existing static fixed-assignment scheme in terms of end-to-end delay and successful throughput. It is also shown that pseudo-proportional fairness is achieved for our hybrid protocol.

We study rate control systems with heterogeneous time-varying propagation delays, based on analytic fluid flow models composed of first-order delay-differential equations. Both single-flow and multi-flow system models are analyzed, with special attention paid to the Mitra-Seery algorithm. The stationary solutions are investigated. For the fluctuating solutions, their dynamic behavior is analyzed in detail, analytically and numerically, in terms of amplitude, transient behavior, fairness and adaptability, etc.. Especially the effects of heterogeneous time-varying delays are investigated. It is shown that with proper parameter design the system can achieve stable behavior with close to pointwise proportional fairness among flows.

Finally we investigate the resource allocation in 802.16j multi-hop relay systems with rate fairness constraints for two mutually exclusive options: transparent and non-transparent relay systems (T-RS and NT-RS). Single-Input Single-Output and Multi-Input Multi-Output antenna systems are considered in the links between the Base Station (BS) and Relay Stations (RS). 1 and 3 RSs per sector are considered. The Mobile Station (MS) association rule, which determines the access station (BS or RS) for each MS, is also studied. Two rules: Highest MCS scheme with the highest modulation and coding rate, and Highest (Mod) ESE scheme with the highest (modified) effective spectrum efficiency, are studied along with the optimal rule that maximizes system capacity with rate fairness constraints. Our simulation results show that the highest capacity is always achieved by NT-RS with 3 RSs per sector in distributed scheduling mode, and that the Highest (Mod) ESE scheme performs closely to the optimal rule in terms of system capacity.