  Voice over Internet protocol (VoIP) is one of the most important applications
for the IEEE 802.11 wireless local area networks (WLANs). For network planners
who are deploying VoIP over WLANs, one of the important issues is the VoIP
capacity. VoIP bandwidth consumption over a WAN is one of the most important
factors to consider when building a VoIP infrastructure. Failure to account for
VoIP bandwidth requirements will severely limit the reliability of a VoIP
system and place a huge burden on the WAN infrastructure. Less bandwidth
utilization is the key reasons for reduced number of channel accesses in VOIP.
But in the QoS point of view the free bandwidth of atleast 1-5% will improve
the voice quality. This proposal utilizes the maximum bandwidth by leaving 1-5%
free bandwidth. A Bandwidth Data rate Moderation (BDM) algorithm has been
proposed which correlates the data rate specified in IEEE802.11b with the free
bandwidth. At each time BDM will calculate the bandwidth utilization before
sending the packet to improve performance and voice quality of VoIP. The
bandwidth calculation in BDM can be done by using Erlang and VOIP bandwidth
calculator. Finally, ns2 experimental study shows the relationship between
bandwidth utilization, free bandwidth and data rate. The paper concludes that
marginal VoIP call rate has been increased by BDM algorithm.
