| In recent years, short distance wireless communications technologies are widely applied in the fields of communications applications. Due to the increasing number of communication devices, it is common that various devices may coexist with each other. As these communication devices working on the ISM channel, mutual interference is inevitable. Therefore, how to analyze the performance of communication devices in the complex interference environment and how to propose a mechanism to avoid the interference become important issues. Taking IEEE802.15.4(ZigBee) as the research object, the thesis studies the performance analysis of ZigBee in a complex interference environment, and proposes an effective coexistence method of interference suppression.Firstly, the thesis introduces the protocol standards of short distance wireless communications technologies, such as IEEE802.15.4, IEEE802.11b and IEEE802.15.1.Secondly, the thesis studies the performance analysis of the ZigBee in a complex interference environment. Considering several communication devices working on the ISM channel may coexist with each other, the thesis proposes a new analytic method of the coexistence among ZigBee, WLAN, and multiple Bluetooth piconets. The impact of distance, the number of WLAN nodes, the number of Bluetooth piconets on packet error rate, average transmission delay and throughput of ZigBee are discussed, respectively. Simulation results show that the analytic method can reflect the performance of IEEE802.15.4(ZigBee) correctly.Finally, the thesis proposes an interference mitigation mechanism of IEEE802.15.4systems in the presence of co-channel interference. The proposed method first detects the presence of interference in a distributed manner. In the presence of interference, it transmits the signal using multiple channels in a frequency hopping manner and selects the best channel for the handoff, which can efficiently alleviate the interference problem and improve the performance of IEEE802.15.4systems. |
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