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LEE: Light‐Weight Energy‐Efficient encryption algorithm for sensor networks
Data confidentiality in wireless sensor networks is mainly achieved by RC5 and Skipjack encryption algorithms. However, both algorithms have their weaknesses, for example RC5 supports variable-bit rotations, which are computationally expensive operations and Skipjack uses a key length of 80-bits, which is subject to brute force attack. In this paper we introduce a light-weight energy- fficient encryption-algorithm (LEE) for tiny embedded devices, such as sensor network nodes. We present experimental results of LEE under real sensor nodes operating in TinyOS. We also discuss the secrecy of our algorithm by presenting a security analysis of various tests and cryptanalytic attacks
Innovative energy-efficient wireless sensor network applications and MAC sub-layer protocols employing RTS-CTS with packet concatenation
of energy-efficiency as well as the number of available applications. As a consequence there
are challenges that need to be tackled for the future generation of WSNs. The research work
from this Ph.D. thesis has involved the actual development of innovative WSN applications contributing
to different research projects. In the Smart-Clothing project contributions have been
given in the development of a Wireless Body Area Network (WBAN) to monitor the foetal movements
of a pregnant woman in the last four weeks of pregnancy. The creation of an automatic
wireless measurement system for remotely monitoring concrete structures was an contribution
for the INSYSM project. This was accomplished by using an IEEE 802.15.4 network enabling for
remotely monitoring the temperature and humidity within civil engineering structures. In the
framework of the PROENEGY-WSN project contributions have been given in the identification
the spectrum opportunities for Radio Frequency (RF) energy harvesting through power density
measurements from 350 MHz to 3 GHz. The design of the circuits to harvest RF energy
and the requirements needed for creating a WBAN with electromagnetic energy harvesting and
Cognitive Radio (CR) capabilities have also been addressed. A performance evaluation of the
state-of-the art of the hardware WSN platforms has also been addressed. This is explained by
the fact that, even by using optimized Medium Access Control (MAC) protocols, if the WSNs
platforms do not allow for minimizing the energy consumption in the idle and sleeping states,
energy efficiency and long network lifetime will not be achieved.
The research also involved the development of new innovative mechanisms that tries and solves
overhead, one of the fundamental reasons for the IEEE 802.15.4 standard MAC inefficiency. In
particular, this Ph.D. thesis proposes an IEEE 802.15.4 MAC layer performance enhancement by
employing RTS/CTS combined with packet concatenation. The results have shown that the use
of the RTS/CTS mechanism improves channel efficiency by decreasing the deferral time before
transmitting a data packet. In addition, the Sensor Block Acknowledgment MAC (SBACK-MAC)
protocol has been proposed that allows the aggregation of several acknowledgment responses
in one special Block Acknowledgment (BACK) Response packet. Two different solutions are
considered. The first one considers the SBACK-MAC protocol in the presence of BACK Request
(concatenation) while the second one considers the SBACK-MAC in the absence of BACK Request
(piggyback). The proposed solutions address a distributed scenario with single-destination and
single-rate frame aggregation. The throughput and delay performance is mathematically derived
under both ideal conditions (a channel environment with no transmission errors) and non
ideal conditions (a channel environment with transmission errors). An analytical model is proposed,
capable of taking into account the retransmission delays and the maximum number of
backoff stages. The simulation results successfully validate our analytical model. For more
than 7 TX (aggregated packets) all the MAC sub-layer protocols employing RTS/CTS with packet
concatenation allows for the optimization of channel use in WSNs, v8-48 % improvement in the
maximum average throughput and minimum average delay, and decrease energy consumption
Topics in access, storage, and sensor networks
In the first part of this dissertation, Data Over Cable Service Interface Specification (DOCSIS) and IEEE 802.3ah Ethernet Passive Optical Network (ETON), two access networking standards, are studied. We study the impact of two parameters of the DOCSIS protocol and derive the probability of message collision in the 802.3ah device discovery scheme. We survey existing bandwidth allocation schemes for EPONs, derive the average grant size in one such scheme, and study the performance of the shortest-job-first heuristic.
In the second part of this dissertation, we study networks of mobile sensors. We make progress towards an architecture for disconnected collections of mobile sensors. We propose a new design abstraction called tours which facilitates the combination of mobility and communication into a single design primitive and enables the system of sensors to reorganize into desirable topologies alter failures. We also initiate a study of computation in mobile sensor networks. We study the relationship between two distributed computational models of mobile sensor networks: population protocols and self-similar functions. We define the notion of a self-similar predicate and show when it is computable by a population protocol.
Transition graphs of population protocols lead its to the consideration of graph powers. We consider the direct product of graphs and its new variant which we call the lexicographic direct product (or the clique product). We show that invariants concerning transposable walks in direct graph powers and transposable independent sets in graph families generated by the lexicographic direct product are uncomputable.
The last part of this dissertation makes contributions to the area of storage systems. We propose a sequential access detect ion and prefetching scheme and a dynamic cache sizing scheme for large storage systems. We evaluate the cache sizing scheme theoretically and through simulations. We compute the expected hit ratio of our and competing schemes and bound the expected size of our dynamic cache sufficient to obtain an optimal hit ratio. We also develop a stand-alone simulator for studying our proposed scheme and integrate it with an empirically validated disk simulator
Performance Analysis of Random Linear Network Coding in Two-Source Single-Relay Networks
This paper considers the multiple-access relay channel in a setting where two
source nodes transmit packets to a destination node, both directly and via a
relay node, over packet erasure channels. Intra-session network coding is used
at the source nodes and inter-session network coding is employed at the relay
node to combine the recovered source packets of both source nodes. In this
work, we investigate the performance of the network-coded system in terms of
the probability that the destination node will successfully recover the source
packets of the two source nodes. We build our analysis on fundamental
probability expressions for random matrices over finite fields and we derive
upper bounds on the system performance for the case of systematic and
non-systematic network coding. Simulation results show that the upper bounds
are very tight and accurately predict the decoding probability at the
destination node. Our analysis also exposes the clear benefits of systematic
network coding at the source nodes compared to non-systematic transmission.Comment: Proc. ICC 2015, Workshop on Cooperative and Cognitive Mobile Networks
(CoCoNet), to appea
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