| 摘要 |
<p>A wireless network has a distributed control protocol using carrier sense mutiple access. Each station in the network listens to traffic on the network communications channel (typically frequency hopping radio transmissions using spread spectrum). Based on the content of each received transmission, each station constructs its own perception of when the communications channel is going to be busy in the form of a network allocation vector (data structure). Each message transmission is by way of a four-way handshake involving two short control packets, the first being a request to send and the second being a clear to send that reserve the actual data transfer. The request to send includes an indication of the length of the subsequent data transmission. This length is used by the various receiving stations to reserve the communications channel for the period of time associated with that length of data transfer. The subsequent clear to send message echoes this data length for receipt by stations which are within range of the receiving station but not within range of the source station. This reservation increases the probability of subsequent successful transmission of the actual data.</p> |
