| Summary: | The problem of data communication in a multihop packet radio network (PRN) with a
number of mobiles or randomly distributed stationary nodes using a slotted ALOHA channel
access scheme is addressed. A multihop PRN is an extension of a single-hop PRN; in the
latter system, a node can communicate directly with any other nodes. A multihop PRN is
necessary if a node cannot reach another node due to transmit power constraints. In such a
case, the node requires repeaters to forward packets on to the destination. If a network has
a large number of nodes, employing spatial frequency reuse to achieve better spectrum is
one of the advantages of a multihop PRN over a single-hop PRN.
In multihop PRNs, a transmission strategy involves designing a routing algorithm and
determining the transmission probability for each node in the network. Routing is one of
the major problems in a multihop PRN. In this thesis, three new routing schemes, MAD,
ARR, and MTP, are proposed. The performances of five transmission strategies based
on the MFR, NFP, MAD, ARR, and MTP routing schemes with capture and fading are
studied and compared. Results show that the transmission strategies based on the ARR and
MTP routing schemes perform better than the other three transmission strategies. All five
transmission strategies perform worse in the presence of Rayleigh fading; this is in contrast
to contention-limited single-hop systems in which Rayleigh fading generally does not result
in a poorer performance.
A multiple receiver antenna system for a multihop PRN is proposed in which the
nodes make use of multiple receiver antennas so as to provide diversity reception. The
performances of the five transmission strategies based on the MFR, NFP, MAD, ARR, and
MTP routing schemes in a Rayleigh fading environment are investigated. Results show that the performances of all five transmission strategies can be substantially improved by
employing multiple antennas.
The performance improvements of the transmission strategies arising from the use of
directional transmitter antennas are also examined. It is found that the performances of all
five transmission strategies can be improved by reducing the beamwidth of the antennas.
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