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In this paper, we present a model to analyze the performance of three transmission strategies with smart antennas, i.e. directional antennas with adjustable transmission power. Generally, a larger transmission radius contributes a greater progress if a transmission is successful. However, it has a higher probability of collision with other concurrent transmissions. Smart antennas mitigate collisions with sectorized transmission ranges. They also extend the transmission radii. By modelling three transmission strategies, namely, Nearest with Forward Progress (NFP), Most Forward with Fixed Radius (MFR), and Most Forward with Variable Radius (MVR), our analysis illustrates that the use of smart antennas can greatly reduce the possibility of conflicts. The model considers the interference range and computes the interference probability for each transmission strategy. We have analyzed two Medium Access Control (MAC) protocols using our interference model, namely, the slotted ALOHA protocol and the slotted CSMA/CAlike protocol. The result shows that, for slotted ALOHA, NFP yields the best one-hop throughput, whereas MVR provides the best average forward progress. The overall performance is substantially improved with the slotted CSMA/CA-like protocol, and the network becomes more resilient.

-Transmission scheduling is a key design problem in wireless multi-hop networks and many scheduling algorithms have been proposed to maximize the spatial reuse and minimize the time-division multipleaccess (TDMA) frame length. Most of scheduling algorithms are graph-based, dependent on the exact network topology information and cannot adapt to the dynamic wireless environment. Some topology-independent TDMA scheduling algorithms have been proposed, and do not need accurate topology information. Our proposed algorithm follows a similar approach but with a different design strategy. Instead of minimizing the TDMA frame length, we maximize the minimum expected throughput, and we consider multicasting and broadcasting. The simulation result shows that the performance of our algorithm is better than the conventional TDMA and other existing algorithms in most cases.

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