ks and the EGPRS session is therefore re-established. Note that it takes some additional time (about 3 seconds) to ramp up and return to full downlink RLC throughput. Packet BCCH This text would be incomplete without addressing the packet BCCH (PBCCH) feature. Essentially, PBCCH utilises a timeslot on the existing BCCH TRX to provide additional dedicated packet system information and common control channels to separate control and signalling of voice and data calls. Packet BCCH can be used to reduce the latency during cell reselection since it broadcasts the packet system information messages at a higher frequency compared to standard BCCH. While this feature has some inherent benefits, it has not been deployed widely in US markets primarily due to the following four reasons: limited mobile support; additional radio timeslot is required and takes away from available TCH resources; additional operational complexity of maintaining separate BA and parameters for packet data; most mobiles have both voice and data capability and are likely to produce conflict when switching modes. Having mentioned the above, PBCCH would be extremely useful for networks where the mobile devices are restricted to EGPRS data (e.g. data cards) and demanded very high performance with low latency requirements. PBCCH could be used in those areas where reducing cell reselection time would provide the greatest benefit while also supporting high data signalling load that would ordinarily congest a typical combined or noncombined BCCH channel. EGPRS Throughput, Latency and Link Adaptation EGPRS radio throughput and latency (and ultimately end user application throughput) are fundamentally influenced by the radio environment in which the mobile subscriber is immersed. EGPRS technology has the ability to take advantage of link adaptation (LA) to combat the impact of fading to improve the overall performance experienced by the user. As a reference, Figure 2.87 illustrates a typical fading environment and the mechanisms used to combat this fading. W