9 research outputs found
Distributed MAC Protocol Supporting Physical-Layer Network Coding
Physical-layer network coding (PNC) is a promising approach for wireless
networks. It allows nodes to transmit simultaneously. Due to the difficulties
of scheduling simultaneous transmissions, existing works on PNC are based on
simplified medium access control (MAC) protocols, which are not applicable to
general multi-hop wireless networks, to the best of our knowledge. In this
paper, we propose a distributed MAC protocol that supports PNC in multi-hop
wireless networks. The proposed MAC protocol is based on the carrier sense
multiple access (CSMA) strategy and can be regarded as an extension to the IEEE
802.11 MAC protocol. In the proposed protocol, each node collects information
on the queue status of its neighboring nodes. When a node finds that there is
an opportunity for some of its neighbors to perform PNC, it notifies its
corresponding neighboring nodes and initiates the process of packet exchange
using PNC, with the node itself as a relay. During the packet exchange process,
the relay also works as a coordinator which coordinates the transmission of
source nodes. Meanwhile, the proposed protocol is compatible with conventional
network coding and conventional transmission schemes. Simulation results show
that the proposed protocol is advantageous in various scenarios of wireless
applications.Comment: Final versio
A Joint Network Coding and Scheduling Algorithm in Wireless Network
Network coding (NC) is an emerging technique of packet forwarding thatencodes packets at relay node in order to increase network throughput. It is understoodthat the performance of NC is strongly dependent on the physical layer as well as theMAC layer, and greedy coding method may in fact reduce the network throughputowing to the reduction in the spatial reuse. In this paper, we propose a NC-awarescheduling method combining link aggregation to improve the network throughput byconsidering the interplay between NC and spatial reuse. Simulation resultsdemonstrate the effectiveness of our proposed link aggregation method compared withthe unicast transmission model
Compute-and-forward on a line network with random access
Signal superposition and broadcast are important features of the wireless medium. Compute-and-Forward, also known as Physical Layer Network Coding (PLNC), is a technique exploiting these features in order to improve performance of wireless networks. More precisely, it allows wireless terminals to reliably de- code a linear combination of all messages, when a superposition of the messages is received through the physical medium.\ud
In this paper, we propose a random PLNC scheme for a local interference line network in which nodes perform random access scheduling. We prove that our PLNC scheme is capacity achieving in the case of one symmetric bi-directional session with terminals on both ends of this line network model. We demonstrate that our scheme significantly outperforms any other scheme. In particular, by eligibly choosing the access rate of the random access scheduling mechanism for the network, the throughput of our PLNC scheme is at least 3.4 and 1.7 times better than traditional routing and plain network coding, respectively
Wireless Broadcast with Physical-Layer Network Coding
This work investigates the maximum broadcast throughput and its achievability
in multi-hop wireless networks with half-duplex node constraint. We allow the
use of physical-layer network coding (PNC). Although the use of PNC for unicast
has been extensively studied, there has been little prior work on PNC for
broadcast. Our specific results are as follows: 1) For single-source broadcast,
the theoretical throughput upper bound is n/(n+1), where n is the "min
vertex-cut" size of the network. 2) In general, the throughput upper bound is
not always achievable. 3) For grid and many other networks, the throughput
upper bound n/(n+1) is achievable. Our work can be considered as an attempt to
understand the relationship between max-flow and min-cut in half-duplex
broadcast networks with cycles (there has been prior work on networks with
cycles, but not half-duplex broadcast networks).Comment: 23 pages, 18 figures, 6 table