The turbo-fountain

Reliable wireless broadcast with asynchronous data access based on fountain coding is investigated. We review the traditional problem formalisation for fountain codes operating on erasure channels, and we generalise the problem formalisation to more general channels. We introduce a novel type of rateless codes based on the Turbo Principle: the Turbo-Fountain. The Turbo-Fountain is able to consider soft information from the channel in the decoding process. Two realisations for the Turbo-Fountain are introduced. We show simulation results for the Turbo-Fountain realisations on the AWGN and on fading channels. Additionally, we compare the achievable Turbo-Fountain performance with traditional fountain codes designed for the erasure channel, both on the AWGN and on fading channels, considering an appropriate erasure declaration. It is shown that the Turbo-Fountain provides significant performance gains, due to exploitation of soft information, and approaches capacity. Moreover, we investigate the Turbo-Fountain within the framework of joint source-fountain coding. We show that the Turbo-Fountain provides the additional ability of lossless source compression and outperforms a system with separate source coding followed by fountain coding. Copyright # 2006 AEIT.