Date Added: Oct 2010
In packet-based IP networks, including wired and wireless sections, the end-to-end performance is governed by the protocols set at the transport layer, such as TCP and UDP. The traditional TCP's problems stem from the fact that retransmission takes place as long as a TCP segment is lost for whatever reason, congestion or random loss. This is also accompanied by a TCP window reduction. As a result, unnecessary delays and throughput decreases would occur when the loss is not caused by congestion, especially in wireless networks. In contrast, UDP does not need to retransmit lost packets in order to deliver time-critical services, but there are no reliability guarantees.