2,694 research outputs found
RECOMAC: a cross-layer cooperative network protocol for wireless ad hoc networks
A novel decentralized cross-layer multi-hop cooperative protocol, namely, Routing Enabled Cooperative Medium Access Control (RECOMAC) is proposed for wireless ad hoc networks. The protocol architecture makes use of cooperative
forwarding methods, in which coded packets are forwarded via opportunistically formed cooperative sets within a region, as RECOMAC spans the physical, medium access control (MAC) and routing layers. Randomized coding is exploited at the physical layer to realize cooperative transmissions, and cooperative forwarding is implemented for routing functionality, which is submerged into the MAC layer, while the overhead for MAC and route set up is minimized. RECOMAC is shown to provide dramatic performance improvements of eight times higher throughput and one tenth of end-to-end delay than that of the conventional architecture in practical wireless mesh networks
Diversity, Coding, and Multiplexing Trade-Off of Network-Coded Cooperative Wireless Networks
In this paper, we study the performance of network-coded cooperative
diversity systems with practical communication constraints. More specifically,
we investigate the interplay between diversity, coding, and multiplexing gain
when the relay nodes do not act as dedicated repeaters, which only forward data
packets transmitted by the sources, but they attempt to pursue their own
interest by forwarding packets which contain a network-coded version of
received and their own data. We provide a very accurate analysis of the Average
Bit Error Probability (ABEP) for two network topologies with three and four
nodes, when practical communication constraints, i.e., erroneous decoding at
the relays and fading over all the wireless links, are taken into account.
Furthermore, diversity and coding gain are studied, and advantages and
disadvantages of cooperation and binary Network Coding (NC) are highlighted.
Our results show that the throughput increase introduced by NC is offset by a
loss of diversity and coding gain. It is shown that there is neither a coding
nor a diversity gain for the source node when the relays forward a
network-coded version of received and their own data. Compared to other results
available in the literature, the conclusion is that binary NC seems to be more
useful when the relay nodes act only on behalf of the source nodes, and do not
mix their own packets to the received ones. Analytical derivation and findings
are substantiated through extensive Monte Carlo simulations.Comment: IEEE International Conference on Communications (ICC), 2012. Accepted
for publication and oral presentatio
A cross layer multi hop network architecture for wireless Ad Hoc networks
In this paper, a novel decentralized cross-layer multi-hop cooperative network architecture is presented. Our architecture involves the design of a simple yet efficient cooperative flooding scheme,two decentralized opportunistic cooperative forwarding mechanisms as well as the design of Routing
Enabled Cooperative Medium Access Control (RECOMAC) protocol that spans and incorporates the physical, medium access control (MAC) and routing layers for improving the performance of multihop communication. The proposed architecture exploits randomized coding at the physical layer to realize cooperative diversity. Randomized coding alleviates relay selection and actuation mechanisms,and therefore reduces the coordination among the relays. The coded packets are forwarded via opportunistically formed cooperative sets within a region, without communication among the relays and without establishing a prior route. In our architecture, routing layer functionality is submerged into the
MAC layer to provide seamless cooperative communication while the messaging overhead to set up routes, select and actuate relays is minimized. RECOMAC is shown to provide dramatic performance improvements, such as eight times higher throughput and ten times lower end-to-end delay as well as reduced overhead, as compared to networks based on well-known IEEE 802.11 and Ad hoc On Demand
Distance Vector (AODV) protocols
Adaptive Randomized Distributed Space-Time Coding in Cooperative MIMO Relay Systems
An adaptive randomized distributed space-time coding (DSTC) scheme and
algorithms are proposed for two-hop cooperative MIMO networks. Linear minimum
mean square error (MMSE) receivers and an amplify-and-forward (AF) cooperation
strategy are considered. In the proposed DSTC scheme, a randomized matrix
obtained by a feedback channel is employed to transform the space-time coded
matrix at the relay node. Linear MMSE expressions are devised to compute the
parameters of the adaptive randomized matrix and the linear receive filter. A
stochastic gradient algorithm is also developed to compute the parameters of
the adaptive randomized matrix with reduced computational complexity. We also
derive the upper bound of the error probability of a cooperative MIMO system
employing the randomized space-time coding scheme first. The simulation results
show that the proposed algorithms obtain significant performance gains as
compared to existing DSTC schemes.Comment: 4 figure
Distributed Linear Convolutional Space-Time Coding for Two-Relay Full-Duplex Asynchronous Cooperative Networks
In this paper, a two-relay full-duplex asynchronous cooperative network with
the amplify-and-forward (AF) protocol is considered. We propose two distributed
space-time coding schemes for the cases with and without cross-talks,
respectively. In the first case, each relay can receive the signal sent by the
other through the cross-talk link. We first study the feasibility of cross-talk
cancellation in this network and show that the cross-talk interference cannot
be removed well. For this reason, we design space-time codes by utilizing the
cross-talk signals instead of removing them. In the other case, the self-coding
is realized individually through the loop channel at each relay node and the
signals from the two relay nodes form a space-time code. The achievable
cooperative diversity of both cases is investigated and the conditions to
achieve full cooperative diversity are presented. Simulation results verify the
theoretical analysis.Comment: 11 pages, 7 figures, accepted by IEEE transactions on wireless
communication
Efficient Wireless Security Through Jamming, Coding and Routing
There is a rich recent literature on how to assist secure communication
between a single transmitter and receiver at the physical layer of wireless
networks through techniques such as cooperative jamming. In this paper, we
consider how these single-hop physical layer security techniques can be
extended to multi-hop wireless networks and show how to augment physical layer
security techniques with higher layer network mechanisms such as coding and
routing. Specifically, we consider the secure minimum energy routing problem,
in which the objective is to compute a minimum energy path between two network
nodes subject to constraints on the end-to-end communication secrecy and
goodput over the path. This problem is formulated as a constrained optimization
of transmission power and link selection, which is proved to be NP-hard.
Nevertheless, we show that efficient algorithms exist to compute both exact and
approximate solutions for the problem. In particular, we develop an exact
solution of pseudo-polynomial complexity, as well as an epsilon-optimal
approximation of polynomial complexity. Simulation results are also provided to
show the utility of our algorithms and quantify their energy savings compared
to a combination of (standard) security-agnostic minimum energy routing and
physical layer security. In the simulated scenarios, we observe that, by
jointly optimizing link selection at the network layer and cooperative jamming
at the physical layer, our algorithms reduce the network energy consumption by
half
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