Browsing by Author "Barreal, Amaro"

Now showing 1 - 4 of 4

Efficiently sphere-decodable physical layer transmission schemes for wireless storage networks
(2016-05-05)
Lu, Hsiao-feng (Francis)
;
Barreal, Amaro
;
Karpuk, David
;
Hollanti, Camilla
;
資訊工程學系
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.
Efficiently sphere-decodable physical layer transmission schemes for wireless storage networks
(2016-05-05)
Lu, Hsiao-feng (Francis)
;
Barreal, Amaro
;
Karpuk, David
;
Hollanti, Camilla
;
電機工程學系
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.
New Relay-Based Transmission Protocols for Wireless Distributed Storage Systems
(2014-01-01)
Hollanti, Camilla
;
Lu, Hsiao-feng (Francis)
;
Karpuk, David
;
Barreal, Amaro
;
電機資訊學士班
Communication over a fading channel in a wireless storage system makes repair transmissions prone to physical layer errors. The repair transmission can be modeled as a multiple access channel (MAC), where multiple helpers are simultaneously communicating to the newcomer node. The existing optimal MAC space-time (ST) codes are, however, practically useless due to exponentially high decoding complexity when the number of helper nodes is big and the number of antennas at the newcomer node is low. To tackle this problem, two new repair transmission protocols based on ST-coding and relaying strategies are given in this paper. The diversity-multiplexing gain tradeoff (DMT) of the system together with sphere-decodability and low transmitter and receiver complexity in terms of the number of antennas required at each end are used as the main design criteria, thus naturally establishing a tradeoff between DMT, complexity, and the decoding delay. Both schemes are converting the MAC into a relay channel by increasing the decoding delay, which enables them to outperform the DMT of a simple time sharing protocol and the MAC DMT for certain multiplexing gains.
Space-Time Storage Codes for Wireless Distributed Storage Systems
(2014-01-01)
Hollanti, Camilla
;
Karpuk, David
;
Barreal, Amaro
;
Lu, Hsiao-Feng (Francis)
;
電機資訊學士班
Distributed storage systems (SDSSs) have gained a lot of interest recently, thanks to their robustness and scalability compared to single-device storage. Majority of the related research has exclusively concerned the network layer. At the same time, the number of users of, e.g., peer-to-peer (p2p) and device-to-device (d2d) networks as well as proximity based services is growing rapidly, and the mobility of users is considered more and more important. This motivates, in contrast to the existing literature, the study of the physical layer functionality of wireless distributed storage systems. In this paper, we take the first step towards protecting the storage repair transmissions from physical layer errors when the transmission takes place over a fading channel. To this end, we introduce the notion of a space-time storage code, drawing together the aspects of network layer and physical layer functionality and resulting in cross-layer robustness. It is also pointed out that existing space-time codes are too complex to be utilized in storage networks when the number of helpers involved is larger than the number of receive antennas at the newcomer or data collector, hence creating a call for less complex transmission protocols.