Improving the VoIP Capacity in WiMAX Networks

Vitaliy Tykhomyrov

IEEE 802.16e-2005 was developed before other beyond-3G standards,
such as 3GPP LTE, but there are a few key areas where the
performance of 802.16 systems can be improved. Voice over IP
(VoIP) service is an essential service for operators. As new
mobile systems are developed, there will be continued interest in
further improving the VoIP capacity. The VoIP performance of
mobile systems is considered much more important now than it was
when IEEE 802.16e was initially developed. Voice services revenue
continues to be the major revenue source for operators and 802.16
expands its usage to the mobility scenario. One of the focus areas
for the current version of IEEE 802.16e is the expansion of VoIP
capacity. The VoIP capacity of a mobile communication system is
inversely related to the associated overhead. Overhead is
particularly important for VoIP applications due to the frequent
transmission and small packets for VoIP. In the 802.16e system,
much of the overhead associated with VoIP traffic occurs in the
MAP messages, since dynamic scheduling is used to support VoIP. To
decrease the MAP overhead, the
802.16 standard proposes a few mechanisms, such as the compressed
MAP and sub-MAPs. Sub-MAPs can improve the system performance by almost 25%.