Shared Position Technique for Interfered Random Transmissions in Satellite Communications

Abstract

In this paper we propose a new random access (RA) channel technique for the return link of satellite communications. It concerns slotted transmissions. This proposed method called Shared POsition Technique for Interfered random Transmissions (SPOTiT), is based on a shared knowledge between the receiver and each of the terminals. The shared information is about the time slot locations on which the terminal transmits its replicas as well as the preamble to use. The presented random version of SPOTiT aims to reduce the complexity of replicas localization process of the legacy technique Multireplica Decoding using Correlation based Localisation (MARSALA). It presents a less complex system without degrading performance and with no extra signaling information. Thus, SPOTiT is applied at the same level as MARSALA, i.e. when Contention Resolution Diversity Slotted Aloha (CRDSA) fails in retrieving more packets. This technique combined with CRDSA significantly reduces the number of data localization correlations, while maintaining the same performance as in CRDSA/MARSALA in terms of packet loss ratio and throughput.

Complexity analysis for recent ALOHA random access techniques in satellite communications

“…R‐SPOTiT with multiple preambles has been described in previous work 17 . However, a complete definition will be presented here.…”

“…Both rely on making the receiver be aware of the potential positions, on the frame, of all packets of users attached to it. The first technique, Random SPOTiT 17 (noted R‐SPOTiT in the rest of the paper), allows the receiver and each of the transmitters, without any additional signaling information, to have a common knowledge of the time slot positions in order to mitigate the replicas localization complexity. Moreover, pseudo‐orthogonal preambles have been used to further reduce the localization complexity in terms of number of correlations.…”

“…Therefore, we focus in this paper mainly on defining a whole version of R‐SPOTiT, its parameters, and to compare its complexity to that of MARSALA. The complexity assessment that was reported in Zamoum et al 17 concerns the number of data correlations that are necessary to localize replicas of collided packets on a given reference time slot. It was derived per user and without considering preamble detection.…”

“…In this paper, we derive the localization complexity over the whole frame, in addition to including preamble detection correlations. Besides, the case of a single preamble for Random SPOTiT, which was not considered in Zamoum et al, 17 will be described. The complexity of Smart SPOTiT is not in the scope of this paper and is a subject of study in future work.…”

Deterministic Distribution of Replicas Positions for Multiuser Random Transmissions in Satcoms

“…Considering MARSALA's efficiency and the complexity regarding its implementation, random SPOTiT [13] came out with a new solution aiming to reduce the localization correlations. It uses the pseudo-orthogonal characteristic of preambles, in addition to the shared information between the receiver and each of the transmitters to target a lower number of slots for localization correlations.…”