Abstract
Three transmission schemes over a new type of multiple-access channel (MAC) model with inter-source communication links are proposed and investigated in this paper. This new channel model is well motivated by, e.g., wireless distributed storage networks, where communication to repair a lost node takes place from helper nodes to a repairing node over a wireless channel. Since in many wireless networks nodes can come and go in an arbitrary manner, there must be an inherent capability of inter-node communication between every pair of nodes. Assuming that communication is possible between every pair of helper nodes, the newly proposed schemes are based on various smart time-sharing and relaying strategies. In other words, certain helper nodes will be regarded as relays, thereby converting the conventional uncooperative multiple-access channel to a multiple-access relay channel (MARC). The diversity-multiplexing gain tradeoff (DMT) of the system together with efficient sphere-decodability and low structural complexity in terms of the number of antennas required at each end is used as the main design objectives. While the optimal DMT for the new channel model is fully open, it is shown that the proposed schemes outperform the DMT of the simple time-sharing protocol and, in some cases, even the optimal uncooperative MAC DMT. While using a wireless distributed storage network as a motivating example throughout the paper, the MAC transmission techniques proposed here are completely general and as such applicable to any MAC communication with inter-source communication links.
Highlights
The amount of data in cloud storage systems and worldwide data traffic have reached incredible numbers
The reason for avoiding this approach is both its structural and computational complexity. In this paper2, we propose a class of transmission schemes for multiple-input multiple-output (MIMO)-multiple-access channel (MAC) when communication links among the sources do exist, which is generally true in many wireless storage networks
The communication channel deduced from Scheme 3 resembles the multiple-access relay channel (MARC), which was first introduced by Kramer and van Wijngaarden [49]
Summary
The amount of data in cloud storage systems and worldwide data traffic have reached incredible numbers. Storage nodes may erase their stored data and become blank, after which they can assume the role of a repairing node, etc This means that an inter-node communication capability exists between every pair of helper nodes, calling for the design of efficient transmission schemes when the sources are further allowed to communicate with each other in a wireless MIMO-MAC. The reason for avoiding this approach is both its structural (many antennas) and computational (decoding subject to partial brute-force) complexity In this paper, we propose a class of transmission schemes for MIMO-MAC when communication links among the sources (helper nodes) do exist, which is generally true in many wireless storage networks.
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