Permutation-Based Transmissions in Finite Blocklength Regime: Efficient and Effective Resource Utilisation

In this paper, the concept of permutation-based transmissions is developed at the transport layer of short-packet communications, where the application-layer data is divided into two parts: one is conveyed by the permutation of various lengths in a group of packets, and the other is encapsulated into these various-length packets. The former part, referred to as permutation-conveyed data unit (PCDU), improves the goodput and reduces the latency. From a finite blocklength perspective, the maximal payload rate of permutation-based transmissions is formulated, based on which the goodput and latency are derived and obtained in analytical forms. Moreover, the spectral efficiency and energy efficiency are analysed. Illustrative numerical results on the performance and resource utilisation comparisons not only substantiate the advantages of our permutation-based transmissions over conventional transport-layer encapsulation schemes, but also provide useful tools and specifications for the PCDU design in short-packet communications.