Content deleted Content added
→RRTS: move ref out of heading |
|||
| (One intermediate revision by one other user not shown) | |||
Line 3:
== Principles of operation ==
[[
Assume that node A has data to transfer to node B. Node A initiates the process by sending a ''Request to Send'' frame (RTS) to node B. The destination node (node B) replies with a ''Clear To Send'' frame (CTS). After receiving CTS, node A sends data. After successful reception, node B replies with an acknowledgement frame (ACK). If node A has to send more than one data fragment, it has to wait a random time after each successful data transfer and compete with adjacent nodes for the medium using the RTS/CTS mechanism.<ref name="MACAW"/>
Line 22:
MACAW is a [[non-persistent]] [[slotted]] protocol, meaning that after the medium has been busy, for example after a CTS message, the station waits a random time after the start of a time slot before sending an RTS. This results in fair access to the medium. If for example nodes A, B and C have data fragments to send after a busy period, they will have the same chance to access the medium since they are in transmission range of each other.
=== RRTS ===
Source:<ref name="MACAW"/> Node D is unaware of the ongoing data transfer between node A and node B. Node D has data to send to node C, which is in the transmission range of node B. D initiates the process by sending an RTS frame to node C. Node C has already deferred its transmission until the completion of the current data transfer between node A and node B (to avoid [[co-channel interference]] at node B). Hence, even though it receives RTS from node D, it does not reply back with CTS. Node D assumes that its RTS was not successful because of collision and hence proceeds to ''back off'' (using an [[exponential backoff]] algorithm).
| |||