Network 320 Week 4

Wireless Network Traffic

More and more traffic is being moved to wireless networks of various types. Voice traffic in particular can provide substantial savings on a company’s telephone service. It allows companies to use an IP network to make phone calls instead of the traditional telephone companies' public switched telephone network (PSTN). Although cost savings is the biggest advantage to using wireless networks for voice traffic, there are still a few issues and limitations. When voice traffic travels over a wireless network, the packets must compete with occurrences that may affect the overall voice quality. The primary factors that determine voice quality are packet loss, latency and jitter.

Packet loss occurs when packets sent over the network are not properly received by end stations, causing them to be discarded by the receiver. There are several reasons why packet loss can occur. Overloaded links, overload in the receiving device, excessive collisions in the wireless link, physical media errors due to interference and low link quality are among a few of the reasons why packet loss happens. Packet loss can and will degrade voice quality. Some protocols such as TCP will ask the receiver for retransmission or the sender automatically resend any segments that have not been acknowledged when packet loss occurs. Others solutions to eliminate packet loss are: reduce the number of packets transmitted and enable the end stations to react more quickly to packet loss.

Excessive jitter can result from congestion on low bandwidth WAN links. High levels of jitter can cause large numbers of packets to be discarded by the jitter buffer in the receiving IP phone or gateway. This may result in severe degradation in call quality or large increases in delay. Solutions to eliminate jitter are increasing the jitter size buffer in the end station, enabling the adaptive jitter buffer operation. In the event there is large amounts of jitter, steps should be taken to...