On the Gaussian multiway relay channel with intra-cluster links

Abstract

This paper studies the extension of the multiway relay channel (introduced by Gündüz et al.) by adding intra-cluster links. In this model, multiple clusters of users communicate with the help of one relay and the users within a cluster wish to exchange messages among themselves. Restricted encoders are considered; thus, the encoded messages of each user depend only on its own message, not on previously decoded ones. Cut-set bounds and achievable rates are given for the Gaussian case with and without time-sharing between clusters. Depending on the protocol considered, schemes based on random coding or nested lattice coding are proposed. The schemes are compared in terms of exchange capacity, that is the equal rate point in the capacity region of a symmetric multiway relay channel. It is shown that the gap between the cut-set bound and Compress-and-Forward, as well as Amplify-and-Forward, is independent of the transmit power constraints when time-sharing is used.

Generalized Multiway Relay Network: Proposition and Effective Rate Analysis

“…If successfully recovered, these neighbors information becomes available to that user. This fact is not exploited in other works that also consider simultaneous transmission of several users, such as [5], [8], [9], highlighting the novelty of the proposed solution.…”

“…The transmission strategies proposed in [5], [8] and [9] consider that all users transmit simultaneously during the first TS. In [8] and [9], users can communicate not only with the relay but also with one another.…”

“…In [8] and [9], users can communicate not only with the relay but also with one another. While in [8] all the users are arranged to belong to a single cluster, like in the original work [2], in [9] several clusters are possible.…”

“…In this regard, the authors in [4] considered a highly dense network where some users are selected to transmit simultaneously through half-duplex channels. Similar to [8] and [9], users can communicate with one another and the received information from the other users is employed as side information to increase even further the number of users. In [6], users are allowed to transmit more than once, and the number of users transmitting simultaneously varies in each TS.…”

“…Vehicles A and B (similarly, C and D) are close enough to have a direct link between them, but due obstacles (e.g., buildings) located at the corners, vehicles from one group can only exchange information with vehicles from the other group through the relay. In the present work, a generalization of the system models introduced in [1], [2], [8], [9], called generalized multiway relay network (g-mRN), is proposed with the purpose of representing a broader selection of practical scenarios, as the one presented in Figure 1. Regarding the example, in g-mRN the four vehicles form a cluster, because they want to exchange their information.…”