Wireless lan technologies are becoming increasingly important to deliver solutions to london buses and bus operators. This work describes results of theoretical throughput model for the ieee 802.11 deployed systems. A keyfeature of this model is that it captures the effects and overheads of contention window (cw) and binary slotted exponential back off procedures used by the ieee 802.11. The interest in modelling this technology is derived from investigations into using the ieee 802.11 to transfer large data files in an area of competing network nodes. The interest is in the effectiveness of the technology to transfer large data files in the presence of many stations including the operation of the mac layer. A model of the ieee 802.11 mac layer was developed. the focus was on generating quick estimates for the expected operational performance throughput of the ieee 802.11 under an increasing number of stations, and varying protocol overheads. Thenetwork model was configured to use the distributed coordination function(dcf) within the mac sublayer. results of this paper show the operationalperformance is far from the expected theoretical upper bound of the ieee 802.11 systems. The performance of the ieee 802.11 depends on the network configuration, the backoff algorithm, packet size, and the number of the competing nodes, and distribution of packets transmitted at various allowedairspeeds. The model was used to generate results for the best case performance, then by varying the number of buses (clients) it can be demonstrated how performance degrades with increasing the number of stations. The presented results show the relationship between the total number of stationsfor one access point and total system throughput.
Abstract