On CAC, DCA, and scheduling in TDD multi-hop 4G wireless networks

In our recent research [A. Safwat 2003, 2004] we envisioned wireless multi-hopping as a complementary technology to conventional cellular networks. In this paper, we present analytical models to compute the expected end-to-end delay and the connection and system throughput in multi-hop 4G/4G+ UTRA TDD networks. To avoid excessive queuing delays, we adopt (and later devise) an efficient scheduling mechanism in which routes pertaining to different connections are disjoint, unless independent resources are allocated to each connection. We demonstrate the delay and throughput characteristics, throughput-delay characteristics, and utilization-throughput characteristics under various offered loads and connection/routing schedules. We utilize the analytical models to develop a framework, namely multi-hop TDD CAC and DCA (MTCD), for optimal CAC and DCA. Finally, we also propose two CAC schemes which use a pre-defined optimization algorithm to ensure that admission is based, to a large extent, on topology maintenance, energy conservation, load balancing, and fairness.