st Uplink Channel Request Time: 20:26:03.24 Downlink System Information Type 2 Downlink Immediate Assignment Downlink Packet Uplink Ack/Nack Message Details Uplink Packet Control Acknowledgement Downlink System Information Type 1 Downlink System Information Type 2 Downlink System Information Type 3 Immediate Assignment Time: 20:26:05.55 Downlink System Information Type 4 Downlink System Information Type 13 Downlink System Information Type 2 Message Details Message Details Downlink System Information Type 3 Downlink Immediate Assignment Downlink Packet Polling Request Timeslot allocation : Uplink Packet Control Acknowledgement Packet Downlink Assignment [0 Timeslot is not assigned Downlink Synch Channel Information Time 20:26:05.80 [1] Timeslot is not assigned Downlink Parket Downlink Assignment [2] Timeslot is not assigned Uplink Packet Downlink Ack/Nack [3] Timeslot is not assigned Uplink Packet Downlink Ack/Nack [4 Timeslot is not assigned Uplink Packet Downlink Ack/Nack [5] Timeslot is assigned Uplink Packet Downlink Ack/Nack [6] Timeslot is assigned Uplink Packet Downlink Ack/Nack [7] Timeslot is assigned Figure 2.86 Layer 3 messaging sequence for EGPRS cell reselection Radio Network Optimisation 1.29 seconds to decode all required system information messages (1 to 4 and 13) and send a RACH (channel request). This time can change based on the frequency with which the BCCH/PBCCH (packet BCCH) broadcasts the system information messages along with the capability of the mobile to decode these messages (either based on MS activity or RF environment). It should also be noted that it took about 2.31 seconds for the LLC packets to be re-routed from the old BVCI to the new BVCI. This time can change based on the level of LLC packet routing required (i.e. intraPCU, interPCU, interBSC, interSGSN), along with the loading/speed of each network element (PCU, BSC, SGSN) and 'inter element signalling efficiency'. Finally, the packet downlink assignment message indicates that the PCU has segmented the LLC frames into RLC bloc