Simple Streaming Codes for Reliable, Low-Latency Communication

Streaming codes offer reliable recovery under decoding-delay constraint τ, of packets transmitted over a burst- and-random-erasure channel. Prior rate-optimal code constructions had field size quadratic in τ and employed diagonal embedding of a scalar block code of length n within the packet stream. It is shown here that staggered diagonal embedding (SDE) under which the n code symbols are dispersed across a span of N ≥ n successive packets leads to a simpler, low-complexity construction of rate-optimal streaming codes having linear field size. The limits of the SDE approach under the restriction N ≤ τ + 1 are explored. Some binary streaming codes that are rate-optimal under this restriction are identified.

I. Introduction

Ensuring reliable, low-latency communication is key to enabling next-generation applications such as disaster recovery, industrial automation, interactive streaming, multi-player gaming, telesurgery, vehicular safety and virtual reality. Not surprisingly, Ultra-Reliable, Low-Latency Communication (URLLC) is one of the three core focus areas of 5G. The ITU-R report [1] sets a latency requirement of 1 millisecond for URLLC, where latency is measured as the time elapsed between transmission of a packet from the source and its recovery at the receiver. At the same time, it is also desired to keep the failure probability to acceptably low levels. It is challenging to meet the tight latency constraints while employing ARQ-based schemes on account of the large, inherent round-trip delays. On the other hand, ensuring reliability through the blind re-transmission of data is wasteful of resources. For these reasons, a viable alternative is the use of Forward Error Correction (FEC). Streaming codes represent a packet-level FEC scheme for ensuring reliable, low-latency communication.