Real-time traffic support for ad hoc wireless networks

摘要

Ad hoc wireless networks are multihop packet radio networks which do not have any fixed infrastructure. A group of nodes using a single frequency spectrum, communicate with each other by resolving access to the shared broadcast channel. Providing support for real-time traffic in this environment where the topology is highly dynamic is very challenging due to the fact that efficient resource reservation mechanisms are very difficult. In this work we propose a MAC layer protocol, Realtime MAC (RTMAC) for ad hoc wireless networks, which provides a bandwidth reservation mechanism. The core concept of this protocol is the flexibility of placement of reservation slots in the super-frame, by which the protocol can make use of the holes (short free slots in the super-frame which otherwise cannot be utilized) in the super-frame. We have simulated our protocol using GloMoSim and compared it with MACA/PR (Lin and Gerla, 1997) for different performance evaluation metrics such as average end-to-end delay, packet delivery ratio, call blocking ratio, and out-of-order packets. Results show that the real-time traffic in RTMAC is less affected by the presence of best-effort traffic when compared to MACA/PR. Also, we found that RTMAC outperforms MACA/PR in call blocking ratio, average end-to-end delay, and packet delivery ratio.