Coexistence Of Zigbee And IEEE802.11B

ZigBee is a new short-range wireless communications technology, which has low-cost, low-rate, low-power, flexible networking characteristics. And it has been more widely used in people life. Because it also works in the free ISM band, so it is inevitable to be influenced by other wireless communications technologies from the band. IEEE802.11b, WiFi technology, is the most widely used technology for applications in the ISM band. You can see the application of WiFi in schools, commercial streets, cafes, airports, office buildings and so on. Therefore, ZigBee almost inevitably suffer from the impact of WiFi. This paper studies the performance of ZigBee under the WiFi interference.The paper first describes the802.11system standards and network topology, then focuses on expounding the IEEE802.11b the physical layer, direct sequence spread spectrum, frequency hopping spread spectrum and complementary code keying technology, MAC layer and DCF access mechanism. Then the paper introduces the ZigBee protocol standards, technical characteristics, network topology, physical layer and MAC layer specification, and gives a brief introduction to the network layer and application layer.In this paper, the PER of ZigBee under the IEEE802.11b interference is analyzed, in the case that both systems frequency offset is zero. The PER is obtained by the BER and packet collision time. The BER can be obtained by the SINR. The packet collision time is defined as the time that IEEE802.11b packets overlap ZigBee packets. Because the bandwidth of the IEEE802.11b is22MHz, which is much larger than that of the ZigBee,2MHz. So the signal of the IEEE802.11b, interferer, can be modeled as band limited AWGN to the ZigBee signal. In this paper, the interference power of IEEE802.11b to ZigBee is calculated by the power spectral density of the IEEE802.11b. The in-band power of the IEEE802.11b to ZigBee depends on the frequency offset between the center frequencies of the two systems. Therefore, this article also studies the impact of ZigBee and IEEE802.11b center frequency offset on the PER. Finally, the PER is analyzed in the case that ZigBee and IEEE802.11b center frequency offset is2MHz. This paper suggests the appropriate packet length to reduce the interference of the IEEE802.11b, and obtains a maximum throughput of ZigBee.