End-to-End Performance Analysis of Push to Talk Over Cellular (POC) in WCDMA

R. Cuny (Finland)


Push-to-Talk over Cellular, end-user experience, WCDMA.


One performance challenge with the Push-to-Talk over Cellular (PoC) service is that end users can stay connected to a PoC session for long, while being silent most of the time. During idle periods radio resources shall be released in order to save the radio capacity. However doing so will increase the voice transmission delay after a silent period, because of the delay associated with radio channels establishment. Studies made previously [1] have shown that GPRS/EDGE technology is able to cope with PoC end user requirements. One may consider that WCDMA is therefore also able to deliver good PoC end-user experience since it is generally accepted that WCDMA outperforms GPRS in respect to bandwidth and round trip time. Although the latter is true, packet switched radio resource reservation procedure in WCDMA takes typically slightly more time than in GPRS, and as a result the issue described above (i.e. PoC voice transmission extra delay after silent period) is more critical. In this paper we analyze the end-to-end performance of PoC service in WCDMA and we show that WCDMA systems are also able to deliver good end-user experience and that it outperforms GPRS/EDGE in several ways.

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