Enhanced multichannel routing protocols in MANET
Abstract
Utilising multiple non-overlapping channels in MANET networking can improve
performance and capacity. Most multichannel MAC and routing protocols rely on
an extra radio interface, a common control channel or time synchronisation to support channel selection and routing, but only at the expense of hardware and power
consumption costs. This thesis considers an alternative type of multichannel wireless network where each node has a single half-duplex radio interface and does not
rely on a common control channel or time synchronisation.
Multichannel MAC and routing protocols that adopt the Receiver Directed
Transmission (RDT) communication scheme are investigated to assess their ability to implement a multichannel MANET.
A novel multipath multichannel routing protocol called RMMMC is proposed
to enhance reliability and fault-tolerance in the MANET. RMMMC introduces new
route discovery and recovery processes. The former establishes multiple node and
channel disjointed paths in different channels and accumulates them to acquire a
full multi-hop path to each destination. The latter detects broken links and repairs
them using pre-discovered backup routes.
To enhance communication reliability, a novel cross-layer multichannel MAC
mechanism called RIVC is proposed. It mitigates transmitting/rerouting data packets to a node that does not have an updated route information towards a destination
and only allows data packets with valid routes to occupy the medium. The optional
access mode in the MAC protocol is modified to early detect invalid routes at intermediate nodes and switchover to an alternative path.
A new cross-layer multichannel MAC mechanism called MB is proposed to reduce contention in a busy channel and enhance load balancing. MB modifies the
MAC back-off algorithm to let a transmitter node invoke an alternative path in
the alternative channel when the retry count threshold is reached. The proposed
multichannel protocols are implemented and evaluated by extensive NS2 simulation
studies.