| Summary: | 碩士 === 淡江大學 === 電機工程學系碩士班 === 95 === With the fast progress of the wireless networking technique and the extension of its application, lots of real-time services in addition to the transmission and downloading applications start to use the wireless network transmission. Those applications include video telephony, video conferencing, digital TV, streaming media application, etc, which should be considered with the trade-off between the real time and the image quality under the limited bandwidth. According to such demands, more and more novel techniques are proposed.
There are five levels of transmission mechanism in IEEE 802.16-2005, including Unsolicited Grant Service (UGS), extended real time Polling-Variable Rate Service (ert-VR), real time Polling-Variable Rate Service (rt-VR), non real time Polling-Variable Rate Service (nrt-VR), and Best Effort (BE). With the presentation of these five service levels, the data will be transmitted according to corresponding levels, and will be more suitable in wireless transmission.
This paper use H.264/AVC video transmission, which defines a set of three Profiles. Applications of the Baseline Profile include video telephony, video conferencing; applications of the Main Profile include television broadcasting and video storage; and the Extended Profile may be particularly useful for streaming media applications. H.264 proposes the idea of Network Abstraction Layer (NAL). The output of the encoding process of VCL data will be packeted into NAL units. The NAL will give the NAL units corresponding header information according the contents of the units.
This main research is to make the data of VCL transmit in network better by the parameters of NAL headers. According to the designed levels, the real-time multimedia information will be assigned with the priority of the ranking before transmission, and then transmitted in RT-VR of IEEE 802.16-2005.
In the circumstance with the finite bandwidth in wireless network, we try the best to assign the bandwidth to the transmission of data with higher priority for transmission ranking. We simulate the situations of the data in all ranks under different loss rate.
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