IEEE_802.15.4协议原理与应用.ppt

IEEE802.15.4概述 IEEE 802.15.4不同版本 Zigbee/802.15.4和蓝牙的对比 Bluetooth, UWB, ZigBee, Wi-Fi对比 ZigBee的同类技术 Wibree a low-power solution based on Bluetooth Wavenis the only ultra low-power solution on the smart metering market today Zwave a short range solution backed by Intel and Cisco IO-Homecontrol an international alliance of worldwide leaders for building management solution Konnex/KNX, a European standard for home building automation Wireless HART a SIG offering a interoperable wireless communication standards for process measurement and control applications; just to mention a few. Architecture IEEE 802.15.4的主要特征 Low rate Short distance Low power consumption Small memory size Low cost Star, Peer-to-Peer , Cluster-tree topologies Data rates of 250 kb/s, 40 kb/s and 20 kb/s. Support for low latency devices CSMA-CA channel access. Dynamic device addressing. Fully handshaked protocol for transfer reliability Frequency Bands of Operation Supported Topology Network topology: Star topology Peer-to-peer topology (mesh-based) Cluster-tree-Topology Star Topology Peer-Peer Topology Cluster-tree-Topology Combined Topology (Cluster star) Cluster tree network PHY Overview The PHY is responsible for: Activation and deactivation of the radio transceiver ED within the current channel LQI for received packets CCA for CSMA-CA Channel frequency selection Data transmission and reception Receiver Energy Detection (ED) ? Estimation of the received signal power within the bandwidth of an IEEE 802.15.4 channel ? No attempt is made to identify or decode signals on the channel ? The ED time should be equal to 8 symbol periods ? The ED result shall be reported as an 8 bit integer ranging from 0x00 to 0xff ? Intended for use by a network layer as part of channel selection algorithm Link Quality Indication (LQI) ? Upon reception of a packet, the PHY sends the PSDU length, PSDU itself and link quality (LQ) in the PD-DATA.indication primitive ? LQI measurement is implemented using receiver ED, a