不错

zigbee学习笔记2008-06-14 17:38Every PAN has a unique 16 bit ID and a single ZigBee
coordinator
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 formed
is 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 network
address of 0x0000
zigbee协调器有一个特殊的网络地址0x0000

Every 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 the
network.
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 Access
Period) between two beacons compete using CSMA-CA
– All transactions must be completed by the time of the next network
beacon

beacon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-peer
networks
– Think of it like a two-way radio network, where each client is autonomous and
can 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 in
use
? Beacon Mode
– A very powerful mechanism for controlling power consumption in ex