12-1 RANDOMACCESS 随机访问协议 In random access or contention methods,no station is superior to another station and none is assigned the control over another.No station permits,or does not permit,another station to send.At each instance,a station that has data to send uses a procedure defined by the protocol to make a decision on whether or not to send. 在随机访问或竞争访问方式中，没有一个站点是优于其它站点的， 也不能控制其它站点。没有站点有权力允许或不允许其它站点发 送或不发送数据。有数据要发送的站通过自身的协议决定发送还 是不发送数据。 Topics discussed in this section: ALOHA ALOHA协议 Carrier Sense Multiple Access 载波侦听多路访问协议CSMA Carrier Sense Multiple Access with Collision Detection带有冲突检测能力CSMA Carrier Sense Multiple Access with Collision Avoidance带冲突避免CSMA 12.4 12.4 12-1 RANDOM ACCESS 随机访问协议 In random access or contention methods, no station is superior to another station and none is assigned the control over another. No station permits, or does not permit, another station to send. At each instance, a station that has data to send uses a procedure defined by the protocol to make a decision on whether or not to send. 在随机访问或竞争访问方式中，没有一个站点是优于其它站点的， 也不能控制其它站点。没有站点有权力允许或不允许其它站点发 送或不发送数据。有数据要发送的站通过自身的协议决定发送还 是不发送数据。 ALOHA ALOHA协议 Carrier Sense Multiple Access 载波侦听多路访问协议 CSMA Carrier Sense Multiple Access with Collision Detection 带有冲突检测能力CSMA Carrier Sense Multiple Access with Collision Avoidance 带冲突避免CSMA Topics discussed in this section: