Spinal codes Citation

Spinal codes are a new class of rateless codes that enable wirelessnetworks to cope with time-varying channel conditions in a naturalway, without requiring any explicit bit rate selection. The key ideain the code is the sequential application of a pseudo-random hashfunction to the message bits to produce a sequence of coded symbolsfor transmission. This encoding ensures that two input messages thatdiffer in even one bit lead to very different coded sequences afterthe point at which they differ, providing good resilience to noiseand bit errors. To decode spinal codes, this paper develops an ap-proximate maximum-likelihood decoder, called the bubble decoder,which runs in time polynomial in the message size and achieves theShannon capacity over both additive white Gaussian noise (AWGN)and binary symmetric channel (BSC) models. Experimental resultsobtained from a software implementation of a linear-time decodershow that spinal codes achieve higher throughput than fixed-rateLDPC codes [11], rateless Raptor codes [33], and the layered rate-less coding approach [8] of Strider [12], across a range of channelconditions and message sizes. An early hardware prototype that candecode at 10 Mbits/s in FPGA demonstrates that spinal codes are apractical construction. CATEGORIES AND SUBJECT DESCRIPTORS C.2.1 [Network Architecture and Design]: Wireless communica-tion