Data mode optimization management for APCO Project-25 data networks

APCO Project-25 wireless data link is a narrow band wireless link. This causes communication link to have very limited bandwidth which is between from 4 kbps up to 7.2 kbps. In such case we are in search of every opportunity to improve and well-utilize this low-bandwidth channel for data communications. In this paper we study two data communication modes of APCO Project-25 data communication structure and offer to change these modes dynamically to improve efficiency. APCO Project-25 data communication modes are; 1. confirmed communication and 2. unconfirmed communication. For confirmed communication mode, all packets are protected by 3/4 trellis code and for each packet received, other party sends confirmation package. For uncofirmed communication mode, 1/2 trellis code is used for protection and there is no acknowledgement. In both modes, each packet has its CRC information. Based CRC success/fail statistics, system will decide to switch to other in order to increase bandwidth or provide robustness of communication.