zigbee笔记.doc

Every PAN has a unique 16 bit ID and a single ZigBeecoordinator每个网络有一个独立的16比特的id和唯一的一个zigbee cordinator（协调器）For ZigBee V1.0, merging PANs after they have formedis not possible without re-commissioning the two systems对于zigbee 1.0版来说，在两个网络建成之后，再合并他们是不可能，除非两个网络重新建立The ZigBee coordinator has a special 16 bit networkaddress of 0x0000zigbee协调器有一个特殊的网络地址0x0000Every device has a 64 bit MAC address (unique)每个设备有一个唯一的64位的mac地址Upon association, every device receives a 16 bit network address(unique)经过协商，每个设备受到一个16位的网络地址（单独的）Only the 16 bit network address is used to route packets within thenetwork.只有16位的网络地址被网络路由包使用Devices retain their 16 bit address if they disconnect from the network,however, if LEAVE the network, the 16 bit address is re-assigned当设备断开网络时保留16位的网络地址，但当设备离开网络时，地址就重新分配了NWK broadcast implemented above the MAC: NWK address 0xFFFF is the broadcast address Special algorithm in NWK to propagate the message “Best Effort” or “Guaranteed Delivery” options网络广播在mac层上面执行网络地址0xffff是广播地址特殊的算法传递信息有最优传输和保证传输两个选项可选Two channel access mechanisms Beacon-enabled network Non-beacon network两种频道访问机制允许beacon网络没有beacon网络Beacon-enabled Network For dedicated bandwidth and low latency Set up by network coordinator to transmit in predetermined intervals Beacon frame is transmitted on the first slot of each superframe Beacons are used to: synchronize attached devices, identify the PAN(PAN ID), describe the structure of a superframe Devices wishing to communicate during CAP (Contention AccessPeriod) between two beacons compete using CSMA-CA All transactions must be completed by the time of the next networkbeaconbeacon允许网络带宽制定和低传输速率由网络协调器建立，以固定的时间间隔传输数据beacon帧在每个超级帧的第一个solt被传输beacons被用来同步设备，识别网络，描述超级帧的结构所有的传输都必须被下一个beacon时间结束Non-Beacon Mode A simple, traditional multiple access system used in simple peer and near-peernetworks Think of it like a two-way radio network, where each client is autonomous andcan initiate a conversation at will, but could interfere with others unintentionally However, the recipient may not hear the call or the channel might already be inuse Beacon Mode A very powerful mechanism for controlling power consumption in extendednetworks like cluster tree or mesh Allows all clients in a local piece of the network the ability to know when tocommunicate with each other Here, the two-way radio network has a central dispatcher who manages thechannel and arranges the calls As youll see, the primary value will be in system power consumptionBeacons add a new level of functionality to a networkbeacons 对网络增加了个新级别的功能 Client devices can wake up only when a beacon is to be broadcast, listen fortheir address, and if not heard, return to sleep客户端设备被一个beacon广播到时将会被唤醒， 侦听地址，如果不匹配继续转如到睡眠状态 Beacons are important for mesh and cluster tree networks to keep all of thenodes synchronized without requiring nodes to consume precious batteryenergy listening for long periods of timebeacons是对个网络和树形网络保持所有节点同步，without消耗很多昂贵的电池啊能量，侦听很长时间Data Frame format数据帧格式One of two most basic and important structures in 15.4 Provides up to 118 byte data payload capacity有118个字符的载荷能力 Data sequence numbering to ensure that packets are tracked数据序列数据保证包可被跟踪 Robust structure improves reception in difficult conditions鲁棒结构增强了在恶劣环境下的接受能力 Frame Check Sequence (FCS) validates error-free data帧检查序列验证错误数据Acknowledgement Frame format应答帧格式The other most important structure for 15.4 Provides active feedback from receiver to sender that packet wasreceived without error提供激活的反馈从接受者到发送者告诉其，帧是错误的还是正确的. Short packet that takes advantage of standards-specified “quiet time”immediately after data packet transmission短帧利用标准指定的安静时间，再数据帧传输后MAC Command Frame formatmac控制帧格式Mechanism for remote control/configuration of client nodes用来进行远程控制和配置 Allows a centralized network manager to configure individualclients no matter how large the network对一个星型网络来说，控制单独的终端，不管这个网络有多大Robustness健壮性 Carrier sense multiple access with collisionavoidance: CSMA-CA载波监听，冲突避免 Frame Acknowledgement应答帧 Data Verification: Cyclic Redundancy Check (CRC)使用crc进行错误分析Security Services安全服务 Access Control访问控制 Data Encryption数据加密 Frame Integrity？ Sequential freshness？MAC Layer TaskMAC层任务 Generating network beacons if the device is acoordinator.当设备时一个coordinator时，生成网络beacons Synchronizing to the beacons.同步到beacons Supporting PAN association and disassociation.支持