Feasibility study of IP Multimedia Subsystem (IMS) based Push-to-Talk over Cellular (PoC) for public safety and security communications

摘要

Feasibility of IMS based PoC over public cellular network, specifically over commercial GPRS network, has been studied for public safety and security communication. Both day-to-day routine work and emergency operation handling capability of the PoC service as well as of the network have been considered. The requirements of PSS communication have been taken as the basis for analysing the technical viability of PoC service for PSS communication. The study is based on publicly available specification documents and related literature. The technical data and factual information have been collected from technical papers, reports and news articles posted into the Internet. The thesis also included a case study comparing over-aged analogue PMR systems and possible PoC service over a nationwide commercial GSM/GPRS network for PSS communication.The key findings in favour of using PoC over commercial GPRS networks include already existed nation-wide radio coverage and roaming across the nation boarder, ease of use, special group call functionality, advanced IMS based multimedia services. The study has identified some challenges of using PoC for PSS communication, which are mainly due to the inherent latency of GPRS access network and lack of prioritisation of special groups of users in commercial networks. Though the PoC service over commercial network does not fulfil all the requirements strictly but taking into account the suggested measures, it can be a good alternative to PMR networks. Use of PoC for PSS communication requires zero initial as well as less operational expenses for the respective PSS organizations. At the same time PSS sector is a potential revenue generating market segment for the operator as well.