Novel Design for Short Analog Fountain Codes

Adaptive coding and modulation in current cellular networks relies on a channel quality indicator fed back from the receiver to the transmitter. The process of acquiring channel state information at the transmitter (CSIT) is estimated to take 5–8 ms. For short-packet transmissions in machine-type communications (MTC), the data transmission of small payloads is estimated to take a fraction of a millisecond, i.e., a fraction of the end to end latency. This is especially problematic for ultra-reliable low-latency communications (URLLC) that require an end-to-end latency of 1 ms only. To this end, self-adaptive coding and modulation, aka rateless coding, is much needed to cater for these stringent requirements. In this letter, a new design is proposed for the recently proposed class of rateless codes, dubbed analog fountain codes (AFC), tailored for short-packet transmissions. The numerical results show no error floors down to block error rates of 10 ⁻⁷ , thus meeting the ultra-high reliability requirement of URLLC.