rror correction (and a lower coding scheme) and minimum latency (reduced retransmission) rather than a higher coding scheme (less error correction) since retransmissions would lead to higher latency. This is a critical aspect when considering mobility management (GMM, or GPRS mobility management) and session management (SM) signalling performance of the packet core. For example, the routing area update (RAU) success rate along with attach and the PDP context success rate are adversely affected if too high an MCS is assigned in marginal channel conditions. In this case, it is more critical to reduce latency (and therefore signalling overhead) by maximising forward error correction than it is to attempt using the highest available coding scheme to gain throughput. The paradox of reducing latency by assigning higher throughput is resolved when considering the impact of retransmission time Radio Network Planning and Optimisation on latency. Radio network vendors use various algorithms to accomplish this balance. As a rule of thumb for very short data sessions, better performance is realized when lower EGPRS coding schemes are used (preferably in the GMSK range MCS-1 to MCS-4). A key feature that significantly reduces EGPRS latency is one-phase access. Here, with the capability of the mobile and network to support an 11-bit PRACH access burst, the mobile can transmit the mobile capability (EGPRS and MS class) on the access burst while the network can directly assign an appropriate number of EGPRS capable PDTCHs. One-phase access improves the setup time by making mobiles stay at the lowest 'GPRS compatible' coding scheme (MCS-1) for initial signalling. The result is that EGPRS RLC throughput/TSL will be lower but more robust. While RLC throughput may be reduced (given a high proportion of signalling blocks), the subscriber performance is enhanced. The positive part of this feature is the reduced latency in ideal conditions compared to two-phase access, where the mobile must go through a second packet channel request ro