Impact of Interference on the Throughput of a Multihop Path in a Wireless Network

The impact of interference on the throughput of a multihop path in a wireless network is studied in this paper. Interference is caused due to packets of the same end-to-end flow (intra-path), as well as packets of different flows (inter-path), as packets are transmitted over multiple hops in the network. We show how much throughput is lost due to such interference, and how much is lost due to other factors like the media access scheme, maximum transmission power limit, or overhead at various networking layers. The MAC is considered to be that of IEEE 802.11, while the physical layer is chosen to be that specified in IEEE 802.11a. The simulations are performed with careful representation of wireless channel characteristics, receiver performance, and IEEE 802.11 MAC layer parameters, such as the signal level that causes a device to be blocked (energy detect (ED) threshold). Sensitivity of the throughput of a multihop path, to parameters like transmission power, data rate and ED threshold is studied, and the throughput achievable by optimizing these parameters is evaluated for environments with different propagation characteristics. The limiting factors are identified in different cases, by contrasting the throughput of a multihop path with that of a single hop path and an optimally scheduled multihop path. The results are revealing in terms of the amount of throughput lost due to various factors. The paper also provides a good understanding with regards to the tuning of various parameters to improve the throughput of multihop paths in a wireless network.