Opportunistic Bits in Short-Packet Communications: A Finite Blocklength Perspective

Abstract

In this paper, the concept of opportunistic bits (OBs) is developed in short-packet communications and investigated from a finite blocklength perspective. In the OB-based transmission, the data unit of a packet is divided into two parts: OBs and conventional bits (CBs). The OBs are not physically transmitted but used to indicate the index of the time slot (TS) when the packet containing CBs is transmitted. The loading of a bulk of OB-based packets into multiple TSs can be modelled as a Repeated Balls-into-Bins process with a multi-queue storage. If the bulk is not large enough, certain combination(s) of OBs will not appear, which leaves certain TS(s) empty and hence reduces the TS load efficiency. To evaluate the OB-based transmission performance, we formulate its maximal payload rate and TS load efficiency. With the aid of these two formulations, the energy gain, the goodput, and the latency of OB-based short-packet communications are derived and obtained in analytical forms. For achieving further insights, illustrative numerical results on the resource utilisation efficiency and the performance not only substantiate the advantages of the OB-based transmission over the conventional but also provide useful tools and specifications for its design in massive short-packet communications.Index Terms-Opportunistic bit (OB), short-packet communications, finite blocklength, time slot (TS) load efficiency, maximal payload rate, energy gain, goodput.

Secure and Timely Status Updates in the IoT using Short-Packet Permutation-Based Transmissions

“…The permutation-based transmission is a transport-layer design strategy, where a portion of application-layer data is not physically encapsulated into the transport-layer data units (DUs) but conveyed by the permutation with repetition of various DU lengths in a group of packets. Moreover, in [5], the transmission order arrangement is utilised as a transport-layer resource for the permutation, where a portion of information bits in the DU of a packet, referred to as opportunistic bits, are conveyed by the index of the time slot when the packet is transmitted.…”

“…In addressing the challenge of scarce resources, the permutation-based transmission has been proven to be a suc-cessful application of the permutation philosophy in the transport layer, which effectively improves the spectral efficiency and energy efficiency while increasing the goodput and reducing the latency, compared with conventional transport-layer encapsulation [3], [4]. Concerning short-packet communications over wireless channels contribute to the practical requirements associated with URLLCs, the performance of permutationbased transmissions has been investigated in terms of maximal payload rate, latency reduction, spectral efficiency gain, and energy efficiency gain based on the advances of finiteblocklength information theory [5], [6].…”

Tight Bounds for Repeated Balls-into-Bins

“…Furthermore, formal methods have been used to prove guarantees for RBB with m = n [2]. The RBB setting has been also applied to analyze protocols in short packet communications [28].…”