Akademik Veri Yönetim Sistemi
2009 IEEE 17th Signal Processing and Communications Applications Conference, SIU 2009, Antalya, Türkiye, 9 - 11 Nisan 2009, ss.754-757, (Tam Metin Bildiri)
APCO Project-25 wireless data link is a Narrow Band wireless link. This causes communicataion 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. ©2009 IEEE.