The standard IEEE 802.11 MAC protocol assumes that each mobile host uses maximum transmission power for the transmission of each packet. However, energy is very valuable resources for mobile host in ad hoc wireless network. In the past, several researches about power control were proposed. These power control schemes use different power levels and one more separate power control channel in order to save energy, avoid occurrence of collision, and increase network channel utilization. But various power levels lead to each mobile host having different transmission power ranges, and cause the additional hidden terminal problem, namely heterogeneous power terminal problem. Therefore, in this paper, we propose a simple and efficient power control protocol that used dynamic adjustment transmission power ranges to reduce power consumption, avoid collision, increase the network channel utilization, and ease heterogeneous power terminal problem as well.

The aim of this thesis is to develop a network, whose nodes communicate with the ZigBee wireless network protocol, and control this network with a PC through the Internet. One of the nodes of this network is designed to be master node. The other nodes are slave nodes. The master node can be connected to an Ethernet connected to the Internet. A PC can communicate with the master node via a specific web application over the Internet. The communication between a web server, in which the specific web application is loaded, and the master node is performed using a specific application protocol working over TCP/IP and defined in this thesis. The master node controls the slave nodes of the wireless network formed according to the commands given by the user of a PC over the Internet. The master node contains an implementation of the ZigBee stack along with a suitable application software to communicate with the slave nodes. The master node also contains an implementation of the TCP/IP stack along with a suitable application software to communicate with a web server in which the specific web application is loaded. The slave nodes contain an implementation of the ZigBee stack along with a suitable application software to communicate with the master node. For each type of node, appropriate hardware which is compliant with the software contained by that type of node is used. Each type of node uses microcontroller-based hardware.

Wireless data broadcast is an efficient way to disseminate digital information to clients equipped with mobile devices. It allows a huge number of the mobile clients simultaneously access data at anytime and anywhere in the wireless environments. Applications using wireless data broadcast to disseminate information include accessing stock activities and traffic conditions. Using index technologies on the broadcast file, i.e., selective tuning, can reduce a lot of energy consumption of the mobile devices without significantly increasing client waiting time. Most of the research work for selective tuning assumes that each data item broadcast on the wireless channel is fairly evenly accessed by mobile clients. In real-life applications, more popular data may be frequently accessed by clients than less popular ones, i.e., skewed access patterns. In this dissertation, to support efficiently selective tuning with skewed access patterns in the single-channel wireless environments, we first propose a skewed distributed index, SDI, on the uniform data broadcast, on which each data item is broadcast once in a broadcast cycle. Second, we propose a skewed index, SI, on the nonuniform data broadcast, on which a few popular data items are broadcast more frequently in a broadcast cycle than the others. The first proposed algorithm, SDI, considers the access probabilities of data items and the replication of index nodes. The proposed algorithm traverses a balanced tree to determine whether an index node should be replicated by considering the access probability of its child node. In our performance analysis and simulation results, we have shown that our proposed algorithm outperforms the variant-fanout tree index and the distributed index. The second proposed algorithm, SI, applies Acharya et al.'s Broadcast Disks to generate a broadcast program, in which the popular data items are broadcast more times than the others, in order to reduce client waiting time. Moreover, the proposed algorithm builds a skewed tree for these data items and allocates index nodes for the popular data items more times than those for the less popular ones in a broadcast cycle. From our performance analysis and simulation results, we have shown that our proposed SI outperforms the flexible index and the flexible distributed index.

This paper presents an open system architecture with wireless network centric telemetry and data acquisition over UDP/IP. This networked solution was designed and developed for iron bird and helicopter rotor applications which present a significant challenge for data acquisition and telemetry. Traditionally slip rings were used for data transfer however these result in issues with low bandwidth, electrical noise, installation complexity, and high maintenance costs. This paper describes a networked system using standardized technologies and protocols that was used for data acquisition and recording of parameters such as vibration, strain, and video on DAQ installed on the rotating part. The acquired data was transmitted in real-time via the network-centric wireless telemetry link which was synchronized with a ground-based DAQ used for real time processing of the rotor data.

The capacity of multiuser wireless network, unclear for many years, has always been a hot research topic. Many different operation schemes and coding techniques have been proposed to enlarge the achievable rate region. And omnidirectional relay scheme is one of them. This thesis mainly works on the achievable region of the all-source all-cast network with omnidirectional relay scheme. In order to better understand this problem, we first describe the half-duplex model on the one-dimensional and two-dimensional regular networks. And we present an optimal operation scheme for them to have the maximum achievable rate. For the one-dimensional general network, we proposed an achievable region that indicates valued improvement compared to the previous results. In the full-duplex model of the one-dimensional general network, the maximum achievable rate is presented with a simpler proof in comparison with the previous results. In this thesis, we also show some discussions on more general networks.

In dynamic peer group communications, security has been in high demand by many applications in recent years. One of the more popular mechanisms to satisfy these security requirements is the group key scheme in which the group key is to be shared by each group communication participant. However, how to establish and manage the group key efficiently in order to protect such communications imposes new challenges - especially when such schemes are to be deployed on resource-limited networks such as Mobile Ad hoc Networks (MANETs). The basic needs of such network settings require that the group key schemes must demonstrate not only high performance but also fault-tolerance. Furthermore, to encrypt group communication messages efficiently is essential. Therefore, it is anticipated that the contributions of this thesis will address the development of lightweight and high performance key management protocols for group communications while guaranteeing the same level of security as other approaches. These contributions are listed below: First, two efficient individual rekey schemes, in which most group members process one-way hash functions and other members perform Diffie-Hellman operations, are proposed to obtain performance efficiency. Second, a periodic batch rekey scheme is proposed to handle the out-of-sync problem resulting from individual rekeying schemes in cases where there is a high rate of group member requests for joining/leaving. Third, scalable maximum matching algorithms (M2) are designed to incorporate a tree-based group key generation scheme to forward the partial keys to other group members. Fourth, a hybrid group key management architecture is proposed as well to combine the advantages of centralized and contributory group key schemes. Fifth, a Fast Encryption Algorithm for Multimedia (FEA-M) is enhanced to overcome the vulnerabilities of its original solution and its former improved variant. Performance analyses and experimental results indicate that the proposed approaches reduce computational costs and communication overhead as compared to other popular protocols.

A wireless electronic nose network system has been developed for monitoring and analyzing livestock farm odour. The system utilizes electronic noses (e-noses) that can measure odour compounds and environment factors such as temperature and humidity. The e-noses are deployed at various locations on the farm, and sensor signals are transmitted via a wireless communication to a central station, where the data processing and sensor fusion algorithms analyze the collected odour data, compute the odour concentration, and display the odour dispersion plume. This system would provide users with convenient odour monitoring capabilities and help the development of an effective overall odour management strategy. In addition, an adaptive neuro-fuzzy inference approach is proposed to calibrate the e-nose responses to human panelists' perception. The proposed method can handle non-numeric information and human expert knowledge in livestock farm odour models, and can adjust the parameters in a systematic manner for optimal system performance. The proposed approach has been tested against a livestock farm odour database. Several livestock farm odour models have been developed for comparative studies. The results show that the proposed approach provides a more accurate odour prediction than a typical multi-layer feedforward neural network. Furthermore, to model odour dispersion around livestock facilities, a biologically inspired odour dispersion model is proposed, and is tested using computer simulations and a livestock farm odour database. Results show that the proposed approach is effective in providing accurate modelling of odour dispersion from multiple and various types of odour sources in both static and non-static environments.

Over the last decade, research into unmanned and autonomous vehicles has greatly increased. With applications ranging from science and exploration to humanitarian and military efforts, the rising need for autonomous vehicles demands constant innovation and growth. The Intelligent Dependable Embedded Architectures (IDEA) lab at the University of Kentucky is continually launching research oriented programs [1]. A few key projects focus on the development of Unmanned Aerial Vehicles (UAV). Through this research, at the University of Kentucky, the need to develop a reliable, lightweight, node based hardware for use in light UAVs and other unmanned and autonomous vehicles became apparent. This paper addresses the design and implementation of a network processing node for light UAVs. This system utilizes a Controller Area Network (CAN) noise tolerant communications bus, a low power ZigBee Wireless Network for expanded inner plane communications and Silicon Laboratories C8051F041 microcontrollers to provide the necessary inputs/output and data processing. The final result will be a flight ready light UAV featuring distributed processing nodes to handle the servo communications and controls.

Offentliga trådlösa nätverk finns idag mer tillgängliga än någonsin. Samtidigt haralla dessa nätverk något gemensamt – de går alla att avlyssna och risken finns attanvändarens information kan komma i fel händer. Uppsatsen behandlarallmänhetens säkerhetsmedvetenhet med avseende på denna typ av nätverk genomtvå undersökningar. Den första undersökningen sker via ett tekniskt experiment därdet på flera geografiska platser har erbjudits ett trådlöst nätverk till allmänheten. Pådetta nätverk har det i realtid getts möjligheten att bedöma användarnassäkerhetsmedvetenhet genom att analysera deras nätverkstrafik. Den andraundersökningen sker via en enkät för att få ett resultat från ett teoretiskt perspektiv,hur användarna tror sig agera vid användning av ett sådant nätverk. Således ger denen inblick i den kunskap och säkerhetsmedvetenhet människor i allmänhet tror sigbesitta.Resultaten från undersökningarna tyder på att människors säkerhetsmedvetenhetkan och bör förbättras. Ett första steg är ytterligare utbildning angående de riskersom existerar och hur man undviker dem, något som tas upp i denna uppsats. / Public wireless networks are more available than ever. The networks all havesomething in common—they can be tapped in to, which poses the risk of sensitiveuser information being compromised. This research paper explores the public’ssecurity awareness with regards to public wireless networks by two differentmethods. One technical experiment in which, access to a public wireless networks inseveral different locations were offered. This allowed us to, in real-time, assess thesafety awareness of the users of our public wireless network, by analyzing theirnetwork traffic. The second was a survey, which were distributed to our sample ofpeople. It asked the sample questions about how they perceive their own behavioron a public wireless network. Thus, the survey allowed us to get an idea of theknowledge and the security awareness the public in general believe that they have.The results from our research indicate that people’s security awareness can andshould be improved. One first step towards improvement would be educationconcerning the risks that exist and how to avoid them, which is something that will be brought up in this paper.

The aggregate interference distribution in cognitive radio networks is studied in a rigorous and analytical way using the popular Poisson point process model. While a number of results are available for this model for non-cognitive radio networks, cognitive radio networks present extra levels of difficulties for the analysis, mainly due to the exclusion region around the primary receiver, which are typically addressed via various ad-hoc approximations (e.g., based on the interference cumulants) or via the large-deviation analysis. Unlike the previous studies, we do not use here ad-hoc approximations but rather obtain the asymptotic interference distribution in a systematic and rigorous way, which also has a guaranteed level of accuracy at the distribution tail. This is in contrast to the large deviation analysis, which provides only the (exponential) order of scaling but not the outage probability itself. Unlike the cumulant-based analysis, our approach provides a guaranteed level of accuracy at the distribution tail. Additionally, our analysis provides a number of novel insights. In particular, we demonstrate that there is a critical transition point below which the outage probability decays only polynomially but above which it decays super-exponentially. This provides a solid analytical foundation to the earlier empirical observations in the literature and also reveals what are the typical ways outage events occur in different regimes. The analysis is further extended to include interference cancelation and fading (from a broad class of distributions). The outage probability is shown to scale down exponentially in the number of canceled nearest interferers in the below-critical region and does not change significantly in the above-critical one. The proposed asymptotic expressions are shown to be accurate in the non-asymptotic regimes as well.