Deterministic Distribution of Replicas Positions for Multiuser Random Transmissions in Satcoms

Abstract

Random Access (RA) protocols have considerably evolved in satellite communications, especially after the introduction of Contention Resolution Diversity Slotted Aloha (CRDSA). However, CRDSA finds itself in a deadlock when the number of users is important. A complementary treatment Multireplica Decoding using Correlation based Localization (MARSALA) has hence been proposed to unlock CRDSA. This is fulfilled by localizing then combining replicas of the same undecoded packets using correlations. Based on a prior knowledge of the potential frame content by the receiver, a random Shared POsition Technique for Interfered random Transmissions (SPOTiT) is proposed to reduce MARSALA's localization complexity. As a matter of fact, random SPOTiT highlights a manner for the receiver to be aware of time slot positions and the preamble used by each subscriber. Then it uses this information to target a lower number of slots for localization correlations. In this paper we propose a hybrid solution that mixes both DAMA and Random Access in order to lower the Packet Loss Ratio (PLR) floor. In fact, a centralized computing can manage replicas positions and preambles to use, in a way that no loops are created. This also allows to keep a simple packet localization as in SPOTiT. Hereafter, we provide an optimal distribution of frame content using two replicas per packet which is evaluated through simulation.

Complexity analysis for recent ALOHA random access techniques in satellite communications

“…Moreover, pseudo‐orthogonal preambles have been used to further reduce the localization complexity in terms of number of correlations. The second technique, Smart SPOTiT, 18 constructs an optimal distribution with packets' positions on the frame where no loops can be created,with minimum complexity and with signaling information that is sent only once to the receiver. R‐SPOTiT and MARSALA do not introduce modifications to the receiver, unlike Smart SPOTiT that requires position management and signaling.…”