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Wireless data transmission is much more susceptible to errors than wired. Packets sent over wireless networks are often lost, causing wireless hardware to retransmit the same packets over and over again. As described in the previous chapters, VoIP discards packets that are received too late or out of order. As such, wireless packet retries contribute to voice quality issues such as jitter and drops in audio streams caused by dropped frames.
High numbers of retries reduce the effective speed of the wireless network, lowering available bandwidth and making the data transfer speed variable; which, in turn, contributes to jitter and makes it even tougher to maintain an acceptable quality of conversation. Using the statistics proved by a Wi-Fi network analyzer, you can determine the number of retries on a per-node basis, as illustrated by the screen shot above. While some retries inevitably happen in any 802.11 network, a high number of retries compared to the total number of packets typically indicates that the clients are located too far away from the access point(s) or the level of radio interference is too high.
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