Use of fountain codes in APCO radio systems

Association of Public-Safety Communications Officials (APCO) Project25 is a standard that defines public safety and emergency wireless communications. It supports digital voice and data transmission. Among the wireless applications there are ones that require broadcast transmission besides unicast transmission. Broadcast transmission in APCO P25 is normally unconfirmed, as it is impossible to receive acknowledgement (ACK) from every user and for every packet. Depending on the importance of the information, either all packets are sent without any ACK and with stronger error correcting codes, or a separate confirmed session is established with each and every user. For confirmed transmission, requiring to get ACK from every user and sending whole information separately to each user make the system inefficient. Rateless coding is a technique that is especially useful in broadcast applications. The greatest advantage is that receivers don't need to send a separate ACK for each received packet. They only need to send ACK, as they are able to recover the original data. The second advantage is that no retransmission is needed. Due to the above listed advantages, this thesis will address the use of rateless codes in APCO P25 broadcast applications.