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Wcdma for umts radio access for third genergation mobile communacations phần 2

Về vấn đề này, polyme có những khoảng trống ban nhạc khác nhau có thể chứng minh là một yếu tố quan trọng trong outplaying công nghệ cạnh tranh. Phát thải của màu đỏ, xanh lá cây, hoặc ánh sáng màu xanh là có thể với các ban nhạc khác nhau, làm cho màn hình đầy màu sắc | UMTS Services and Applications 19 other hand crucial. A tolerable delay between taking a picture and showing it to the peer end could be in the order of some seconds 5 s . When it comes to bit rate requirements it is very much dependent on mobile station display sizes. Based on initial results from video streaming in current networks a lower bit rate limit for a 3.5 cm times 4 cm mobile phone display is around 40 to 64 kbps. However note that the required bit rate to use is a nonstraightforward function of the tolerable delay the image update rates and the applied coding schemes. From a network point of view the one-way video streaming service has one obvious property that is different from many other proposed services it requires a fairly high uplink bit rate. The UMTS network must be able to deliver a high and reasonably constant bit rate in order to support the low delay streaming connection as well as the voice connection if the voice connection is mapped over the packet switched domain. These bit rate and delay requirements may be met in a cost efficient way by utilising the QoS differentiation features that are available in UMTS. From a technical perspective the peer-to-peer connections are in the packet switched domain set up by using the IMS system and by utilising the session initiation protocol SIP 9 . From a network and end user perspective this sets requirements on the SIP signalling that it is fast enough not to disturb the user when setting up the additional video stream connection. Fast SIP signalling may be obtained by supporting one of multiple compression algorithms for SIP. In Figure 2.7 a simple service evolution path is depicted starting from simple packet switched services like MMS and going towards more demanding services like video telephony. Video telephony has even tighter requirements on the delays than one-way video streaming and a one-way end-to-end delay of less than 400 ms is needed for the connection while less than 150 ms is .