850 research outputs found
BATSEN: Modifying the BATMAN Routing Protocol for Wireless Sensor Networks
The proliferation of autonomous Wireless Sensor Networks (WSN) has spawned research seeking power efficient communications to improve the lifetime of sensor motes. WSNs are characterized by their power limitations, wireless transceivers, and the converge-cast communications techniques. WSN motes use low-power, lossy radio systems deployed in dense, random topologies, working sympathetically to sense and notify a sink node of the detectable information. In an effort to extend the life of battery powered motes, and hence the life of the network, various routing protocols have been suggested in an effort to optimize converge-cast delivery of sensor data. It is well known that reducing the overhead required to perform converge-cast routing and communications reduces the effects of the primary power drain in the mote, the transceiver. Furthermore, WSNs are not well protected; network security costs energy both in computation and in RF transmission. This paper investigates the use of a Mobile Ad-hoc Networking (MANET) routing protocol known as B.A.T.M.A.N. in WSN. This thesis proposes that the features of B.A.T.M.A.N. in the MANET realm may prove beneficial to the WSN routing domain; and that slight modifications to the routing technique may prove beneficial beyond current protocol technologies. The B.A.T.M.A.N. variant will be compared against the contemporary LEACH WSN routing protocol to discern any potential energy savings
Time-Driven Access and Forwarding for Industrial Wireless Multihop Networks
The deployment of wireless technologies in industrial networks is very promising mainly due to their inherent flexibility. However, current wireless solutions lack the capability to provide the deterministic, low delay service required by many industrial applications. Moreover, the high level of interference generated by industrial equipment limits the coverage that ensures acceptable performance. Multi-hop solutions, when combining frame forwarding with higher node density, have the potential to provide the needed coverage while keeping radio communication range short. However, in multi-hop solutions the medium access time at each of the nodes traversed additively contributes to the end-to-end delay and the forwarding delay (i.e., the time required for packets to be processed, switched, and queued) at each node is to be added as well. This paper describes Time-driven Access and Forwarding (TAF), a solution for guaranteeing deterministic delay, at both the access and forwarding level, in wireless multi-hop networks, analyzes its properties, and assesses its performance in industrial scenario
On the performance of STDMA Link Scheduling and Switched Beamforming Antennas in Wireless Mesh Networks
Projecte final de carrera realitzat en col.laboració amb King's College LondonWireless Mesh Networks (WMNs) aim to revolutionize Internet connectivity due to
its high throughput, cost-e ectiveness and ease deployment by providing last mile
connectivity and/or backhaul support to di erent cellular networks. In order not to
jeopardize their successful deployment, several key issues must be investigated and
overcome to fully realize its potential. For WMNs that utilize Spatial Reuse TDMA
as the medium access control, link scheduling still requires further enhancements.
The rst main contribution of this thesis is a fast randomized parallel link swap
based packing (RSP) algorithm for timeslot allocation in a spatial time division multiple
access (STDMA) wireless mesh network. The proposed randomized algorithm
extends several greedy scheduling algorithms that utilize the physical interference
model by applying a local search that leads to a substantial improvement in the
spatial timeslot reuse. Numerical simulations reveal that compared to previously
scheduling schemes the proposed randomized algorithm can achieve a performance
gain of up to 11%. A signi cant bene t of the proposed scheme is that the computations
can be parallelized and therefore can e ciently utilize commoditized and
emerging multi-core and/or multi-CPU processors.
Furthermore, the use of selectable multi-beam directional antennas in WMNs,
such as beam switched phase array antennas, can assist to signi cantly enhance
the overall reuse of timeslots by reducing interference levels across the network and
thereby increasing the spectral e ciency of the system. To perform though a switch
on the antenna beam it may require up to 0.25 ms in practical deployed networks,
while at the same time very frequent beam switchings can a ect frame acquisition
and overall reliability of the deployed mesh network.
The second key contribution of this thesis is a set of algorithms that minimize the
overall number of required beam switchings in the mesh network without penalizing
the spatial reuse of timeslots, i.e., keeping the same overall frame length in the
network. Numerical investigations reveal that the proposed set of algorithms can
reduce the number of beam switchings by almost 90% without a ecting the frame
length of the network
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