24,649 research outputs found
DMT of Multi-hop Cooperative Networks - Part I: Basic Results
In this two-part paper, the DMT of cooperative multi-hop networks is
examined. The focus is on single-source single-sink (ss-ss) multi-hop relay
networks having slow-fading links and relays that potentially possess multiple
antennas. The present paper examines the two end-points of the DMT of
full-duplex networks. In particular, the maximum achievable diversity of
arbitrary multi-terminal wireless networks is shown to be equal to the min-cut.
The maximum multiplexing gain of arbitrary full-duplex ss-ss networks is shown
to be equal to the min-cut rank, using a new connection to a deterministic
network. We also prove some basic results including a proof that the colored
noise encountered in AF protocols for cooperative networks can be treated as
white noise for DMT computations. The DMT of a parallel channel with
independent MIMO links is also computed here. As an application of these basic
results, we prove that a linear tradeoff between maximum diversity and maximum
multiplexing gain is achievable for full-duplex networks with single antenna
nodes. All protocols in this paper are explicit and rely only upon
amplify-and-forward (AF) relaying. Half duplex networks are studied, and
explicit codes for all protocols proposed in both parts, are provided in the
companion paper.Comment: This submission is Part-I of a two-part paper, which is a detailed
version of the previous submission arXiv:0802.188
Geometrical Localization Algorithm for 3-D Wireless Sensor Networks
In this paper, we propose an efficient range free localization scheme for
large scale three dimensional wireless sensor networks. Our system environment
consists of two type of sensors, randomly deployed static sensors and global
positioning system equipped moving sensors. These moving anchors travels across
the network field and broadcast their current locations on specified intervals.
As soon as the sensors which are deployed in random fashion receives three
beacon messages (known locations broadcasted by anchors), they computes their
locations automatically by using our proposed algorithm. One of our significant
contributions is, we use only three different beacon messages to localize one
sensor, while in the best of our knowledge, all previously proposed methods use
at least four different known locations. The ability of our method to localize
by using only three known locations not only saves computation, time, energy,
but also reduces the number of anchors needed to be deployed and more
importantly reduces the communication overheads. Experimental results
demonstrate that our proposed scheme improves the overall efficiency of
localization process significantly.
Important Note: Final version of this paper is accepted and published by
Journal of Wireless Personal Communication, Springer : June, 2014 The final
version of publication is available at link.springer.com Link:
http://link.springer.com/article/10.1007\%2Fs11277-014-1852-6Comment: Journal of Wireless Personal Communication, Springer : June, 2014,
The final version of publication is available at link.springer.com Link:
http://link.springer.com/article/10.1007%2Fs11277-014-1852-
How Much of Wireless Rate Can Smartphones Support in 5G Networks?
Due to the higher wireless transmission rates in the fifth generation (5G)
cellular networks, higher computation overhead is incurred in smartphones,
which can cause the wireless transmission rates to be limited by the
computation capability of wireless terminals. In this case, is there a maximum
receiving rate for smartphones to maintain stable wireless communications in 5G
cellular networks? The main objective of this article is to investigate the
maximum receiving rate of smartphones and its influence on 5G cellular
networks. Based on Landauer's principle and the safe temperature bound on the
smartphone surface, a maximum receiving rate of the smartphone is proposed for
5G cellular networks. Moreover, the impact of the maximum receiving rate of
smartphones on the link adaptive transmission schemes has been investigated.
Numerical analyses imply that the maximum receiving rate of smartphones cannot
always catch up with the downlink rates of future 5G cellular networks.
Therefore, the link adaptive transmission scheme for future 5G cellular
networks has to take the maximum receiving rate of smartphones into account
Grid-based Network Architecture for Distributed Computation in Wireless Sensor Networks
Wireless Sensor Networks (WSNs) are used to perform distributed sensing in
various fields, such as health, military, home etc. In WSNs, sensor nodes
should communicate among themselves and do distributed computation over the
sensed values to identify the occurrence of an event. This paper assumes the no
memory computation model for sensor nodes, i.e. the sensor nodes only have two
registers. This paper presents an optimal architecture for the distributed
computation in WSN and also claims that this architecture is the optimal for
the described computation model
An imporved decentralized approach for tracking multiple mobile targets through ZigBee WSNs
Target localization and tracking problems in WSNs have received considerable
attention recently, driven by the requirement to achieve high localization
accuracy, with the minimum cost possible. In WSN based tracking applications,
it is critical to know the current location of any sensor node with the minimum
energy consumed. This paper focuses on the energy consumption issue in terms of
communication between nodes whenever the localization information is
transmitted to a sink node. Tracking through WSNs can be categorized into
centralized and decentralized systems. Decentralized systems offer low power
consumption when deployed to track a small number of mobile targets compared to
the centralized tracking systems. However, in several applications, it is
essential to position a large number of mobile targets. In such applications,
decentralized systems offer high power consumption, since the location of each
mobile target is required to be transmitted to a sink node, and this increases
the power consumption for the whole WSN. In this paper, we propose a power
efficient decentralized approach for tracking a large number of mobile targets
while offering reasonable localization accuracy through ZigBee network.Comment: 16 page
Organizing the Aggregate: Languages for Spatial Computing
As the number of computing devices embedded into engineered systems continues
to rise, there is a widening gap between the needs of the user to control
aggregates of devices and the complex technology of individual devices. Spatial
computing attempts to bridge this gap for systems with local communication by
exploiting the connection between physical locality and device connectivity. A
large number of spatial computing domain specific languages (DSLs) have emerged
across diverse domains, from biology and reconfigurable computing, to sensor
networks and agent-based systems. In this chapter, we develop a framework for
analyzing and comparing spatial computing DSLs, survey the current state of the
art, and provide a roadmap for future spatial computing DSL investigation.Comment: 60 pages; Review chapter to appear as a chapter in book "Formal and
Practical Aspects of Domain-Specific Languages: Recent Developments
STAC: Simultaneous Transmitting and Air Computing in Wireless Data Center Networks
The data center network (DCN), wired or wireless, features large amounts of
Many-to-One (M2O) sessions. Each M2O session is currently operated based on
Point-to-Point (P2P) communications and Store-and-Forward (SAF) relays, and is
generally followed by certain further computation at the destination.
%typically a weighted summation of the received digits. Different from this
separate P2P/SAF-based-transmission and computation strategy, this paper
proposes STAC, a novel physical layer scheme that achieves Simultaneous
Transmission and Air Computation in wireless DCNs. In particular, STAC takes
advantage of the superposition nature of electromagnetic (EM) waves, and allows
multiple transmitters to transmit in the same time slot with appropriately
chosen parameters, such that the received superimposed signal can be directly
transformed to the needed summation at the receiver. Exploiting the static
channel environment and compact space in DCN, we propose an enhanced Software
Defined Network (SDN) architecture to enable STAC, where wired connections are
established to provide the wireless transceivers external reference signals.
Theoretical analysis and simulation show that with STAC used, both the
bandwidth and energy efficiencies can be improved severalfold
TEDS: A Trusted Entropy and Dempster Shafer Mechanism for Routing in Wireless Mesh Networks
Wireless Mesh Networks (WMNs) have emerged as a key technology for the next
generation of wireless networking due to its self-forming, self-organizing and
self-healing properties. However, due to the multi-hop nature of communications
in WMN, we cannot assume that all nodes in the network are cooperative. Nodes
may drop all of the data packets they received to mount a Denial of Service
(DoS) attack. In this paper, we proposed a lightweight trust detection
mechanism called Trusted Entropy and Dempster Shafer (TEDS) to mitigate the
effects of blackhole attacks. This novel idea combines entropy function and
Dempster Shafer belief theory to derive a trust rating for a node. If the trust
rating of a node is less than a threshold, it will be blacklisted and isolated
from the network. In this way, the network can be assured of a secure end to
end path free of malicious nodes for data forwarding. Our proposed idea has
been extensively tested in simulation using network simulator NS-3 and
simulation results show that we are able to improve the packet delivery ratio
with slight increase in normalized routing overhead
Opportunistic Routing with Congestion Diversity in Wireless Ad-hoc Networks
We consider the problem of routing packets across a multi-hop network
consisting of multiple sources of traffic and wireless links while ensuring
bounded expected delay. Each packet transmission can be overheard by a random
subset of receiver nodes among which the next relay is selected
opportunistically.
The main challenge in the design of minimum-delay routing policies is
balancing the trade-off between routing the packets along the shortest paths to
the destination and distributing traffic according to the maximum backpressure.
Combining important aspects of shortest path and backpressure routing, this
paper provides a systematic development of a distributed opportunistic routing
policy with congestion diversity ({D-ORCD}).
{D-ORCD} uses a measure of draining time to opportunistically identify and
route packets along the paths with an expected low overall congestion. {D-ORCD}
is proved to ensure a bounded expected delay for all networks and under any
admissible traffic. Furthermore, this paper proposes a practical implementation
which empirically optimizes critical algorithm parameters and their effects on
delay as well as protocol overhead. Realistic Qualnet simulations for
802.11-based networks demonstrate a significant improvement in the average
delay over comparative solutions in the literature. %Finally, various practical
modifications to {D-ORCD} are proposed and their performance are evaluated
Achieving Congestion Diversity in Multi-hop Wireless Mesh Networks
This paper reports on the first systematic study of congestion-aware routing
algorithms for wireless mesh networks to achieve an improved end-end delay
performance. In particular, we compare 802.11 compatible implementations of a
set of congestion-aware routing protocols against our implementation of state
of the art shortest path routing protocol (SRCR). We implement congestion-aware
routing algorithms Backpressure (BP), Enhanced-Backpressure (E-BP) adapted from
[1], [2] suitably adjusted for 802.11 implementation. We then propose and
implement Congestion Diversity Protocol (CDP) adapted from [3] recognizing the
limitations of BP and E-BP for 802.11-based wireless networks. SRCR solely
utilizes link qualities, while BP relies on queue differential to route
packets. CDP and E-BP rely on distance metrics which take into account queue
backlogs and link qualities in the network. E-BP computes its metric by summing
the ETX and queue differential, while CDP determines its metric by calculating
the least draining time to the destination. Our small testbed consisting of
twelve 802.11g nodes enables us to empirically compare the performance of
congestion-aware routing protocols (BP, E-BP and CDP) against benchmark SRCR.
For medium to high load UDP traffic, we observe that CDP exhibits significant
improvement with respect to both end-end delay and throughput over other
protocols with no loss of performance for TCP traffic. Backpressure-based
routing algorithms (BP and E-BP) show poorer performance for UDP and TCP
traffic. Finally, we carefully study the effects of the modular approach to
congestion-aware routing design in which the MAC layer is left intac
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