Sean Mcbeath

Improved VoIP capacity in mobile WiMAX systems using persistent resource allocation

Efficient support of voice traffic has always been one of the key metrics for evaluating and selecting radio access technologies. Even for next-generation broadband wireless technologies primarily focused on the mobile Internet, special handling of VoIP traffic in the physical and MAC layers is required to maximize voice capacity. While Mobile WiMAX Release 1.0 and 802.16e have all the key features necessary to support mobile VoIP traffic, special attention is given in Mobile WiMAX Release 1.5 and 802.16REV2 to further optimizing VoIP capacity through reduction in the MAC layer overhead associated with signaling messages. This article focuses on features and solutions used in Mobile WiMAX and the 802.16 standard to support voice traffic and the expected performance in Release 1.0/802.16e-2005, as well as gains from optimization concepts such as persistent allocation added in Release 1.5/802.16REV2. In each case, MAP overhead reduction and the projected improvements in VoIP capacity are presented using typical industry accepted models and assumptions. The results show about 15 percent increase in bidirectional VoIP capacity.

VoIP support using group resource allocation based on the UMB system

It is now clear that the latest evolution of the wireless communication system, for example, the ultra mobile broadband (UMBtrade) system developed in 3GPP2, has significantly increased the packet data efficiency of the system. However, as voice is still a major part of the revenue stream for many operators, voice efficiency is still of prime concern in the industry. A detailed end-to-end scheme for supporting VoIP in the air interface, designated for the UMB system, is described. Full duplex simulations were performed to evaluate the proposed scheme. The results show that the UMB system has significantly improved upon the VoIP capacity. A 5-MHz UMB system can support 320 VoIP users while simultaneously supporting a forward link data throughput of over 2.26 Mbps. Although more of the delay budget was expanded on the reverse link, the system is still reverse link limited.