Detection Algorithm and Recovery Mechanism when Synchronized ‘Project 25 Phase 2’ TDMA Voice Channel and FDMA Control Channel get out of Sync
Original Publication Date: 2010-Dec-31
Included in the Prior Art Database: 2010-Dec-31
Project 25 Phase 2 is TDMA system which may or may not synchronize TDMA Voice Channels (VCH) to the FDMA Control Channel (CCH). The synchronized solution is preferred because it allows subscriber units (SU) to transmit sooner upon arriving on a TDMA VCH due to prior knowledge of synchronization. The problem would arise when VCH and CCH get out of sync, for whatsoever reason, and SUs still attempt to “synchronously” access TDMA VCH. In that case, obviously, the synchronization learned from CCH will not land SUs on the right VCH TDMA slot resulting in unsuccessful calls. This paper describes a detection algorithm to detect loss of synchronization between TDMA VCH and FDMA CCH followed by a description of the recovery mechanism which involves re-enabling calls, i.e. access to VCH.