4,778 research outputs found
Local heuristic for the refinement of multi-path routing in wireless mesh networks
We consider wireless mesh networks and the problem of routing end-to-end
traffic over multiple paths for the same origin-destination pair with minimal
interference. We introduce a heuristic for path determination with two
distinguishing characteristics. First, it works by refining an extant set of
paths, determined previously by a single- or multi-path routing algorithm.
Second, it is totally local, in the sense that it can be run by each of the
origins on information that is available no farther than the node's immediate
neighborhood. We have conducted extensive computational experiments with the
new heuristic, using AODV and OLSR, as well as their multi-path variants, as
underlying routing methods. For two different CSMA settings (as implemented by
802.11) and one TDMA setting running a path-oriented link scheduling algorithm,
we have demonstrated that the new heuristic is capable of improving the average
throughput network-wide. When working from the paths generated by the
multi-path routing algorithms, the heuristic is also capable to provide a more
evenly distributed traffic pattern
Cross-layer design of multi-hop wireless networks
MULTI -hop wireless networks are usually defined as a collection of nodes
equipped with radio transmitters, which not only have the capability to
communicate each other in a multi-hop fashion, but also to route each others’ data
packets. The distributed nature of such networks makes them suitable for a variety of
applications where there are no assumed reliable central entities, or controllers, and
may significantly improve the scalability issues of conventional single-hop wireless
networks.
This Ph.D. dissertation mainly investigates two aspects of the research issues
related to the efficient multi-hop wireless networks design, namely: (a) network
protocols and (b) network management, both in cross-layer design paradigms to
ensure the notion of service quality, such as quality of service (QoS) in wireless mesh
networks (WMNs) for backhaul applications and quality of information (QoI) in
wireless sensor networks (WSNs) for sensing tasks. Throughout the presentation of
this Ph.D. dissertation, different network settings are used as illustrative examples,
however the proposed algorithms, methodologies, protocols, and models are not
restricted in the considered networks, but rather have wide applicability.
First, this dissertation proposes a cross-layer design framework integrating
a distributed proportional-fair scheduler and a QoS routing algorithm, while using
WMNs as an illustrative example. The proposed approach has significant performance
gain compared with other network protocols. Second, this dissertation proposes
a generic admission control methodology for any packet network, wired and
wireless, by modeling the network as a black box, and using a generic mathematical
0. Abstract 3
function and Taylor expansion to capture the admission impact. Third, this dissertation
further enhances the previous designs by proposing a negotiation process,
to bridge the applications’ service quality demands and the resource management,
while using WSNs as an illustrative example. This approach allows the negotiation
among different service classes and WSN resource allocations to reach the optimal
operational status. Finally, the guarantees of the service quality are extended to
the environment of multiple, disconnected, mobile subnetworks, where the question
of how to maintain communications using dynamically controlled, unmanned data
ferries is investigated
Towards Optimal Distributed Node Scheduling in a Multihop Wireless Network through Local Voting
In a multihop wireless network, it is crucial but challenging to schedule
transmissions in an efficient and fair manner. In this paper, a novel
distributed node scheduling algorithm, called Local Voting, is proposed. This
algorithm tries to semi-equalize the load (defined as the ratio of the queue
length over the number of allocated slots) through slot reallocation based on
local information exchange. The algorithm stems from the finding that the
shortest delivery time or delay is obtained when the load is semi-equalized
throughout the network. In addition, we prove that, with Local Voting, the
network system converges asymptotically towards the optimal scheduling.
Moreover, through extensive simulations, the performance of Local Voting is
further investigated in comparison with several representative scheduling
algorithms from the literature. Simulation results show that the proposed
algorithm achieves better performance than the other distributed algorithms in
terms of average delay, maximum delay, and fairness. Despite being distributed,
the performance of Local Voting is also found to be very close to a centralized
algorithm that is deemed to have the optimal performance
Maximum Multipath Routing Throughput in Multirate Wireless Mesh Networks
In this paper, we consider the problem of finding the maximum routing
throughput between any pair of nodes in an arbitrary multirate wireless mesh
network (WMN) using multiple paths. Multipath routing is an efficient technique
to maximize routing throughput in WMN, however maximizing multipath routing
throughput is a NP-complete problem due to the shared medium for
electromagnetic wave transmission in wireless channel, inducing collision-free
scheduling as part of the optimization problem. In this work, we first provide
problem formulation that incorporates collision-free schedule, and then based
on this formulation we design an algorithm with search pruning that jointly
optimizes paths and transmission schedule. Though suboptimal, compared to the
known optimal single path flow, we demonstrate that an efficient multipath
routing scheme can increase the routing throughput by up to 100% for simple
WMNs.Comment: This paper has been accepted for publication in IEEE 80th Vehicular
Technology Conference, VTC-Fall 201
Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges
With the rapid development of marine activities, there has been an increasing
number of maritime mobile terminals, as well as a growing demand for high-speed
and ultra-reliable maritime communications to keep them connected.
Traditionally, the maritime Internet of Things (IoT) is enabled by maritime
satellites. However, satellites are seriously restricted by their high latency
and relatively low data rate. As an alternative, shore & island-based base
stations (BSs) can be built to extend the coverage of terrestrial networks
using fourth-generation (4G), fifth-generation (5G), and beyond 5G services.
Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs.
Despite of all these approaches, there are still open issues for an efficient
maritime communication network (MCN). For example, due to the complicated
electromagnetic propagation environment, the limited geometrically available BS
sites, and rigorous service demands from mission-critical applications,
conventional communication and networking theories and methods should be
tailored for maritime scenarios. Towards this end, we provide a survey on the
demand for maritime communications, the state-of-the-art MCNs, and key
technologies for enhancing transmission efficiency, extending network coverage,
and provisioning maritime-specific services. Future challenges in developing an
environment-aware, service-driven, and integrated satellite-air-ground MCN to
be smart enough to utilize external auxiliary information, e.g., sea state and
atmosphere conditions, are also discussed
Flow Allocation for Maximum Throughput and Bounded Delay on Multiple Disjoint Paths for Random Access Wireless Multihop Networks
In this paper, we consider random access, wireless, multi-hop networks, with
multi-packet reception capabilities, where multiple flows are forwarded to the
gateways through node disjoint paths. We explore the issue of allocating flow
on multiple paths, exhibiting both intra- and inter-path interference, in order
to maximize average aggregate flow throughput (AAT) and also provide bounded
packet delay. A distributed flow allocation scheme is proposed where allocation
of flow on paths is formulated as an optimization problem. Through an
illustrative topology it is shown that the corresponding problem is non-convex.
Furthermore, a simple, but accurate model is employed for the average aggregate
throughput achieved by all flows, that captures both intra- and inter-path
interference through the SINR model. The proposed scheme is evaluated through
Ns2 simulations of several random wireless scenarios. Simulation results reveal
that, the model employed, accurately captures the AAT observed in the simulated
scenarios, even when the assumption of saturated queues is removed. Simulation
results also show that the proposed scheme achieves significantly higher AAT,
for the vast majority of the wireless scenarios explored, than the following
flow allocation schemes: one that assigns flows on paths on a round-robin
fashion, one that optimally utilizes the best path only, and another one that
assigns the maximum possible flow on each path. Finally, a variant of the
proposed scheme is explored, where interference for each link is approximated
by considering its dominant interfering nodes only.Comment: IEEE Transactions on Vehicular Technolog
Rate Optimal design of a Wireless Backhaul Network using TV White Space
The penetration of wireless broadband services in remote areas has primarily
been limited due to the lack of economic incentives that service providers
encounter in sparsely populated areas. Besides, wireless backhaul links like
satellite and microwave are either expensive or require strict line of sight
communication making them unattractive. TV white space channels with their
desirable radio propagation characteristics can provide an excellent
alternative for engineering backhaul networks in areas that lack abundant
infrastructure. Specifically, TV white space channels can provide "free
wireless backhaul pipes" to transport aggregated traffic from broadband sources
to fiber access points. In this paper, we investigate the feasibility of
multi-hop wireless backhaul in the available white space channels by using
noncontiguous Orthogonal Frequency Division Multiple Access (NC-OFDMA)
transmissions between fixed backhaul towers. Specifically, we consider joint
power control, scheduling and routing strategies to maximize the minimum rate
across broadband towers in the network. Depending on the population density and
traffic demands of the location under consideration, we discuss the suitable
choice of cell size for the backhaul network. Using the example of available TV
white space channels in Wichita, Kansas (a small city located in central USA),
we provide illustrative numerical examples for designing such wireless backhaul
network
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