04-08-2012, 12:04 PM
Many-to-Many Communication for Mobile Ad Hoc Networks
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INTRODUCTION
THE protocol stacks of wireless ad hoc networks implemented
or proposed to date have been designed to try to
avoid interference. Hence, communication protocols used in
wireless ad hoc networks today are meant to support reliable
communication among senders and receivers that are competing
with one another for the use of the shared bandwidth.
This “competition-driven” view of bandwidth sharing has had
profound implications on network architectures and methods
used to access the channel and disseminate information.
NETWORK MODEL
The term cell denotes the set of nodes located inside a
defined area of the network. The receiver range5 of a node is
defined as the radius, measured from the node, which contains
all other nodes of the same cell. The cluster associated with
a given node is the set of cells reached by the receiver range
of this node.
MANY-TO-MANY COMMUNICATION
In many-to-many communication, several nodes transmit
concurrently to many other neighbor nodes, and all such
transmissions are decoded. Thus, a node may concurrently
6Half-duplex means that a node cannot transmit and receive data simultaneously
through the same frequency bandwidth.
send to and receive from many nodes (i.e., MPT and MPR
in each node). Since full-duplex data communication in the
same frequency band is not practical, we present an example
of how many-to-many communication can be implemented
with a scheme based on frequency division multiple access
(FDMA) and CDMA that supports concurrent many-to-many
transmissions.
CONCLUSIONS
It was shown that the Shannon capacity and per sourcedestination
throughput can increase in wireless ad hoc networks
by employing mobility, FDMA/CDMA, SIC, and onetime
relaying of packets taking advantage of many-to-many
communication among nodes. Such performance is attained by
using successive interference cancellation and distinct codes
among close neighbors, which is enabled by running a simple
neighbor-discovery protocol. Accordingly, interference from
close neighbors is no longer harmful, but rather endowed
with valuable data. Many-to-many communication employs
multi-packet transmissions (MPTs) and multi-packet receptions
(MPRs) which can provide significant improvement in
scaling laws for future networks [27].