| Summary: | 碩士 === 國立宜蘭大學 === 資訊工程研究所碩士班 === 98 === A Voice over Internet Protocol (VoIP) packet is encapsulated by Internet Protocol (IP), User Datagram Protocol (UDP) and Real-time Transport Protocol (RTP) headers. In IEEE 802.11a/b/g wireless environments, the 802.11 data-link layer (i.e. Media Access Control) header and a checksum field should be added to the VoIP packet. Take G.729 as an example, the total length of IPv6 voice packet is 114 bytes, including 94 bytes (82%) header fields. The header overhead occupies more than 80% wireless bandwidth. To reduce header overhead of the IPv4 or IPv6 voice packets, we designs a VoIP compression method which integrates Robust Header Compression (ROHC) with Session Initiation Protocol (SIP). Then, we evaluate the improvement of the proposed method compared to the original header format for both IPv4 and IPv6. Eventually, we verify the analytical results through Network Simulator 2 (NS2).
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