A Simple PHY-Aware Outer Coding (SPOC) Scheme for Reliable, Low-Latency Communication

A simple, PHY-aware, packet-level outer coding scheme (SPOC) for beyond 5G is presented that permits reliable communication over just a single Transmission Time Interval (TTI), whenever there are two or more datalink paths between transmitter and receiver. The scheme has the following features: outer coding is positioned at the MAC layer, and each packet is made to correspond to a single LDPC code block, thereby enabling the scheme to take advantage of partially-decoded transport blocks; PHY layers at the receiver end are instructed to pass on to the MAC layer all correctly-decoded code blocks even if the entire transport block has not been correctly decoded. Simulation results are presented to show that the SPOC scheme outperforms the PDCP duplication feature present in the 5G standard, at no additional cost to spectral efficiency. Performance benefits are shown to increase with increased packet sizes, thus making the scheme attractive for high data rate applications that seek reliable communication with extremely low latency. Where latency constraints permit, the scheme can also take advantage of HARQ retransmissions to improve reliability. While the base scheme employs MDS codes, the scheme can be extended to incorporate binary codes as well.