Study On Time Division Multiple Access In Multihop Ad Hoc Networks

Ad hoc network is a self-organizing and self-configuring multihop wireless network without predefined infrastructure where the network topologies, transfer model and channel environment dynamically change with node mobility. Despite the long history of ad hoc networks, there are still quite a number of problems that are open. With the development of communication and electronics, ad hoc network faces a new chanllenge. The main research production of this dissertation is as follows:1. Unlike the current topology-dependent schedules, the efficiency and robustness of topology-transparent schedules are invulnerable in mobile ad hoc networks. In this paper, a topology-transparent time division multiple access (TDMA) with reservation is proposed for multi-hop ad hoc networks. The protocol is based on slotted TDMA architecture in which every slot is divided into reservation phase and data transmission phase. Each node resolves collisions by reservation in its assigned slots and utilizes free slots among its non-assigned slots through carrier sense. Through theoretical analysis, we derive the optimal parameter for the best performance. We testify our analysis by simulation and the influence of network topology and traffic load on the throughput is also invested. Simulation results also show that the protocol has stability and fairness. It is better than other topology-transparent schedules.2. To effectively combine ad hoc networks with multiple input multiple output (MIMO), distributed topology-transparent reservation for time division multiple access (TDMA) protocol with MIMO links in multihop ad hoc networks is proposed. By Galois Radio Network Design (GRAND), the protocol assigns each node slots in each frame and need not know the whole network topology information. As a result, the overhead to collect topology information is greatly reduced. By reservation each node simultaneously transmits all data streams in the MIMO link in its assigned interference-free slots and utilizes its shared slots with other nodes to transmit a part of all data streams in the MIMO link to resolve collisions. The guaranteed throughput and optimal frame length are also derived. Results show that the network throughput will be improved greatly by dynamically allocating MIMO transmission capacity and its anti-interference ability.3. As the current medium access control (MAC) protocols with multiple input...