Usage of rateless codes in APCO radio systems

APCO Project-25 the standard for public safety radio networks defines narrow band data links (12.5KHz) and provides 9600 bps data rate. There can be 1000-5000 users in a network and current broadcast techniques are inefficient. The current system broadcasts by transmitting to individual receivers one by one. Also, if there is any packet not received by at least one user, it is retransmitted. On the other hand, for the case of confirmed delivery, receivers send acknowledgement message to the transmitter for each packet. These messages cause collisions and extra burdens. In this paper we propose to use rateless codes to avoid these inefficiencies.