Research And Performance Analysis Of MAC Protocols For Wireless LAN

Today is in the globalization and information intellectualized period, computercommunication industry rapidly rise. No matter scientific research and military orenterprise management and the national economy information strategy have theexpanding demand for the development of computer communication technology. Thatmainly lies in the following aspects: the computer communication technology towardsthe direction of integration, totalization and intelligent; the highly development ofcomputer communication technology makes system networking and engineerinfomationization in the application of all professions and trades; computercommunication products are diversified and popular increasingly to enter into families.Wireless LAN(WLAN) is the generated product of penetrating and integratingcomputer technology and communication technology mutually and closely. WirelessLAN technology is more and more mature widely used in various fields with itsflexible, convenient, very extensible and efficient networking feature. IEEE802.11isthe basic protocol of IEEE802.11protocol series, and is globally recognized authority.IEEE802standard proposed by the Working Group in the LAN field has been widelyused. Therefore, the IEEE802.11protocol of the multimedia application in theWLAN has a very important significance.This thesis probes into IEEE802.11wireless LAN MAC layer, and then analysesthe distinction among different service support and QoS guarantee IEEE802.11eprotocol. It perfects the theoretical analysis of the network. Specific content includesthe following aspects:1. In the case of containing hidden nodes，the thesis analyses the characteristicsof each station backoff timer and channel access principle spatio-temporally for theIEEE802.11DCF mechanism. And then proposes a new3D discrete time Markovchain.2. The analysis of real-time service in the wireless LAN applications, providingQoS guarantee protocol on IEEE802.11e EDCA mechanism. ConsideredAIFS(arbitribution inter-frame space) distinguish mechanisms, channel and framedifferent competitive mechanisms, contention window size and other factors in thesaturated condition. And then proposes a novel3D Markov chain analytical model.3. For the IEEE802.11DCF mechanism. The thesis utilizes NS2software tosimulate the ring scenarios, and compare the resulting throughput with the model analysis throughput value. Then takes the data load capacity as an unknown variable,and research the relationship between its data packet size and the throughput. Thecomparision of analytical results from the two aspects can be shown modelingaccuracy. The proposed model is in good agreement with the simulation on theperformance parameters such as the normalized offered load and throughput.4. For the IEEE802.11EDCA mechanism, this thesis creates relevant networkscenarios under the saturated condition and utilizes NS2software to analyze thescenario similarly. And then compares the resulting throughput value with somemodel analysis value in the references. The comparison of the data can be shown thatthe model analysis of this thesis throughput value have a better consistency than theothers for each access category throughput service.