Will users really see 54 Mbps with 54g?
As with any wireless protocol, 54g has overhead associated with it that limits performance. While signaling data rates of up to 54 Mbps may be achieved, like most shared media (e.g. Ethernet) throughput will be significantly less. There are two scenarios for 54g performance. In an environment with only 54g clients, throughput can exceed 24 Mbps. This performance is equivalent to that of 802.11a, although 54g is usually available over a greater range. The second scenario is where 802.11b clients are present. RTS/CTS flow control must be used to allow 802.11b clients to recognize and establish communications with 802.11g access points. This leads to delays in transmission and drops peak throughput to about 10 Mbps. 54g performance is still well in excess of the maximum measured speeds of 4-5 Mbps for 802.11b. The use of RTS/CTS is important because it provides determinism to the wireless network, ensuring a minimum bandwidth for each user. Like Ethernet, 802.11 LANs normally use a ג?œcarrier sense media accessג? mechanism to signal transmission without asking for permission from the network. As the network becomes highly loaded, collisions occur more frequently and the network can become saturated with packet retransmission attempts that eventually make it impossible for any data to get through. RTS/CTS provides a more formalized flow-control mechanism that avoids this problem.
Posted on Feb 16, 2006
203 views
Usually answered in minutes!
×