nt for circuit-switched voice is approximately 400 ms. This delay is not disturbing humans in voice communications. CHAPTER 4.2 The motives behind the 3G evolution system performance, thus the operator cannot optimize for only system performance. Interactive file down/upload 4.2.2 3G Evolution: Two radio access network approaches and an evolved core network 4.2.2.1 Radio access network evolution Gaming Voice TSG RAN organized a workshop on 3GPP long-term Evolution in the fall of 2004. The workshop was the Delay starting point of the development of the Long-Term Evo- lution (LTE) radio interface. After the initial requirement Figure 4.2-2 The bit rate - delay service space that is important phase in the spring of 2005, where the targets and objec- to cover when designing a new cellular system. tives of LTE were settled, the technical specification group TSG SA launched a corresponding work on the System Architecture Evolution, since it was felt that the LTE radio special design of the system. Of course, this requires that interface needed a suitable evolved system architecture. the devices used in the mobile-communication system The result of the LTE workshop was that a study item can be programmed by third-party providers and that the in 3GPP TSG RAN was created in December 2004. The operators allow third-party service providers to use their first 6 months were spent on defining the requirements, network for communication. or design targets, for LTE. These were documented in Another important factor is that operators need to a 3GPP technical report and approved in June 2005. provide the services to all the users. Not only one user Most notable are the requirements on high data rate at needs to get the low delay, high data rate, etc. that its the cell edge and the importance of low delay, in addi- service needs, but all the users with their different ser- tion to the normal capacity and peak data rate require- vice needs should be served efficiently. The processing ments. Furthermore, spectrum flexibility and maxi