A novel MAC protocol and layer two transmission scheduling algorithm for WLANs

It is known that hidden-terminal is one of the main problems in ad hoc wireless networks. In addition, there are scenarios where the desired destination is located in the range of other transmitters, so that the efforts on setting up communication with this terminal will fail due to collisions that may occur between transmitted control frames and undesired received control and data frames. This phenomenon becomes a bottleneck when most of data transmissions experience packet fragmentation. In such scenarios, the desired destination becomes unreachable during the data transfer of neighboring nodes. Furthermore, another problem that arises in such networks is in the case of mobile nodes with heterogeneous power capabilities where low power nodes have a disadvantage in accessing media due to higher levels of interference from the high power nodes. Conventional protocols can not address the aforementioned problems efficiently, resulting in throughput and channel utilization degradation. Using the same PHY of IEEE 802.11 and making slight modifications in its MAC, a new medium access control scheme is presented in this paper to address such problems. The performance of the proposed approach is compared with earlier schemes through simulation-based evaluations, showing performance enhancement due to better handling of unreachability issues in the proposed MAC scheme.