A Survey of Bandwidth Optimization Techniques and Patterns in VoIP Services and Applications <s> 1.1) Compression with Aggregation <s> In the recent past, there has been a tremendous increase in the popularity of VoIP services as a result of huge growth in broadband access. The same voice-over-Internet protocol (VoIP) service poses new challenges when deployed over a wireless mesh network, while enabling users to make voice calls using WiFi phones. Packet losses and delay due to interference in a multiple-hop mesh network with limited capacity can significantly degrade the end-to-end VoIP call quality. In this work, we discuss the basic requirements for efficient deployment of VoIP services over a mesh network. We present and evaluate practical optimizing techniques that can enhance the network capacity, maintain the VoIP quality and handle user mobility efficiently. Extensive experiments conducted on a real testbed and ns-2 provide insights into the performance issues and demonstrate the level of improvement that can be obtained by the proposed techniques. Specifically, we find that packet aggregation along with header compression can increase the number of supported VoIP calls in a multihop network by 2-3 times. The proposed fast path switching is highly effective in maintaining the VoIP quality. Our fast handoff scheme achieves almost negligible disruption during calls to roaming clients <s> BIB001 </s> A Survey of Bandwidth Optimization Techniques and Patterns in VoIP Services and Applications <s> 1.1) Compression with Aggregation <s> Header compression techniques can improve the speech quality of VoIP applications. However, its deployment over wireless mesh environments may not offer much improvement, since the wireless and multi-hop characteristics of such a network impose a high packet loss rate. In this work, we propose a new approach for header compression, using packet aggregation to cooperate with the header compression scheme. Simulation results show that the new cooperative approach can decrease significantly the packet loss, impacting positively on the speech quality. <s> BIB002
Since current header compression schemes are seen to maintain contexts with all kinds of information amounting to high level compressions, there is the need to achieve lower compression and higher speech quality, which could be attained through the utilization of algorithms that do not require recent memory yet realizing reasonable compression gains BIB002 . A possible tend towards such solutions is the combination of header compression scheme with packet aggregation. This offers an alternative potential for eliminating redundant information from headers. The initial compression is usually supported by a second compression by collating redundant dynamic information between headers into same aggregation packets and suppressing them into a single aggregate header BIB002 . This approach to optimizing VoIP bandwidth was exploited by BIB001 while proposing the use of a zero-length header compression (ZLH) algorithm for the elimination of redundant headers on VoIP networks. Combined with aggregation, the algorithm is able to support efficient header compression allowing for VoIP calls with as much as 75 R-score. Figure 4 shows how the compression with aggregation works. 