The wireless network design problem (WNDP) considers how best to place a set of antennas so the antennas can send and receive the maximum possible amount of data subject to network-performance constraints (e.g., channel-availability constraints). To date, little research has considered how to choose the network-antenna layout that maximizes throughput under these conditions. Also, past research has mainly investigated networks with omnidirectional antennas only, not other types of antennas. A bi-level mixed-integer program is constructed to solve this problem using a cutting-plane approach. The data produced from this model demonstrate an extension of the WNDP under more realistic conditions than have been simulated previously. The questions answered by this research are as follows: (1) what are the effects on network throughput of utilizing directional or sectored antennas instead of omnidirectional antennas, and (2) what is the maximum possible throughput when imposing constraints related to differing interference types and channel availability?

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A goal of indoor wireless communication is to strategically place RF base stations to obtain optimum signal coverage at the lowest cost and power. Traditionally, transceiver locations have been selected by human experts who rely on experience and heuristics to obtain a near-optimum placement. Current methods depend on involved on-site communication measurements and crude statistical modeling of the obtained data which is time consuming and prohibitive in cost. Given the inherent variability of the indoor environment, such a method often yields poor efficiency. As an example, it is possible that more power than required or extra number of transceivers were used. This thesis describes an interactive software system that can be used to aid transceiver placement. The tool is easy to use and is targeted at users who are not experts in wireless communication system design. Once the transceiver locations are selected by the user within a graphical floor plan, the system uses simple path-loss models to predict coverage regions for each transceiver. The coverage regions are highlighted to indicate expected coverage. Earlier work assumed isotropic transceivers and had limited directional transmitter support. This thesis describes how the tool has been enhanced to support a wide range of 3D antenna patterns as encountered in practical situations. The tool has also been expanded to accommodate more partition types and to report area of coverage. The resulting system is expected to be very useful in the practical deployment of indoor wireless systems. / Master of Science

Ad hoc wireless networks are constructed by several mobile hosts and have a property that its topology is changed as mobile hosts moved. There is no stationary infrastructure or based station to coordinate packets transmissions and advertise the information of network topology or something important. The special networks are used in temporal wireless networks, such as battlefield, disease rescue place, and so on. So without any stationary infrastructure supported, mobile hosts can communicate with others immediately or indirectly. Because topology is often changed while mobile hosts moving, mobile hosts must exchange information to deal with the changed conditions. Mobile hosts often utilize broadcasting to exchange information with their neighbor hosts, but there is high bit error ratio in wireless networks, packet corruption occurs frequently, so that mobile host might lost some important information sent from its neighboring host. In 802.11 standard, lack of acknowledgement, broadcasting is an unreliable transmission, because sender host do not know whether all of it neighboring hosts received broadcasting packets correctly or no. Many proposed papers of reliable broadcast assumed that links between mobile hosts are bidirectional links, but bidirectional link is an ideal assumption. In real environment, links are unidirectional, so host A could send packets to host B immediately, but host B could not because of their transmission range are different. In this paper, we propose a new reliable broadcast scheme, Highly Reliable Broadcast Scheme with Directional Antennas (HRBSDA). HRBSDA can reduce the influence of unidirectional links and reach for highly reliable broadcasting. HRBSDA uses directional antennas and concept of Time Division Multiple Access (TDMA)-like. HRBSDA divide DCF Inter-Frame Space (DIFS) into several minislots, and mobile hosts use these minislots to ask sender for retransmission of lost packets. By the way, HRBSDA can not only reach for highly reliable broadcasting, but also reduce Packet Loss Recovery Time, and avoid causing extra overhead. Using directional antennas HRBSDA can reduce collision, so that improving throughput and channel utilization.

Reducing power consumption is among the top concerns in Wireless Sensor Networks, as the lifetime of a Wireless Sensor Network depends on its power consumption. Directional antennas help achieve this goal contrary to the commonly used omnidirectional antennas that radiate electromagnetic power equally in all directions, by concentrating the radiated electromagnetic power only in particular directions. This enables increased communication range at no additional energy cost and reduces contention on the wireless medium. The SPIDA (SICS Parasitic Interference Directional Antenna) prototype is one of the few real-world prototypes of electronically switchable directional antennas for Wireless Sensor Networks. However, building several prototypes of SPIDA and conducting real-world experiments using them may be expensive and impractical. Modeling SPIDA based on real-world experiments avoids the expenses incurred by enabling simulation of large networks equipped with SPIDA. Such a model would then allow researchers to develop new algorithms and protocols that take advantage of the provided directional communication on existing Wireless Sensor Network simulators. In this thesis, a model of SPIDA for Wireless Sensor Networks is built based on thoroughly designed real-world experiments. The thesis builds a probabilistic model that accounts for variations in measurements, imperfections in the prototype construction, and fluctuations in experimental settings that affect the values of the measured metrics. The model can be integrated into existing Wireless Sensor Network simulators to foster the research of new algorithms and protocols that take advantage of directional communication. The model returns the values of signal strength and packet reception rate from a node equipped with SPIDA at a certain point in space given the two-dimensional distance coordinates of the point and the configuration of SPIDA as inputs. / Phone:+46765816263 Additional email: burkaja@yahoo.com

Wireless ad-hoc networks are easily deployed, untethered to infrastructure, and have virtually an unlimited number of applications. However, this flexibility comes at the cost of finite and often unreplenishable power supplies. Once a node has consumed all of its power, it can no longer receive, transmit, gather information, or otherwise participate in the network. Therefore, reducing the amount of energy necessary for node communication has been an area of intense research. Previous work has investigated the use of directional antennas as a method to reduce inter-node power requirements. However, most proposed methods ignore inter-session interference, propose heuristic solution methods, and ignore the use of directional antennas for signal reception. We develop a flexible mixed-integer linear program (MILP) designed to optimize max-min multicast path lifetime for directional antenna equipped networks in the presence of interference. The MILP is utilized to perform a comparison directional antenna use for signal transmission and reception. Results indicate that directional reception is slightly superior to transmission for the defined max-min lifetime metric, and vastly superior when considering cumulative power use. We further analyze the performance of interference-ignorant link-based heuristics designed for both directional transmission and directional reception as they perform in our more realistic model. Our results show that interference-ignorant methods cannot find feasible solutions unless all nodes are equipped with high gain, high efficiency directional antennas. Even in these cases, directional reception outperforms directional transmission. Because of the superiority of directional reception, we focus our attention on this method. A heterogeneity study is performed, and two heuristic methods for approximating the MILP optima are developed. We find that even under heterogeneous conditions, directional reception can increase network lifetime. Finally, a genetic algorithm (GA) and semi-distributed heuristic method are developed as alternatives to the MILP. Results show that the GA often can find solutions with lifetimes 85% as long as the optimal. Our semi-distributed heuristic, designed to be even more computationally simple than the GA, and to serve as a basis for a distributed protocol, is almost as effective as the GA as approximating optimal solutions. We conclude that directional reception is the superior method of antenna use for extending max-min multicast tree lifetime, that it works well in heterogeneous conditions, and lends itself well to heuristic design. / Ph. D.

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The thesis is focused on special corrugated reflectors for ultra-wideband antennas. Corrugated reflectors are divided into a type H and a type E. Both these types are mutually combined. All those reflectors are simulated and subsequently analyzed. The thesis also deals with different types of broadband dipoles, which are completed by investigated types of reflectors. Created reflector antennas are then compared. For antennas exhibiting the best parameters, we performed simulations of the transmission between two antennas. For the simulations, we used CST Microwave Studio. Selected antennas were manufactured and measured. Consequent simulations were aimed to detect differences between the simulated and measured results.

An important aspect of wireless networks is their dynamic behavior. The conventional protocol stack is inflexible as various protocol layers communicate in a strict manner. In such a case the layers are designed to operate under the worst conditions as opposed to adapting to changing conditions. This leads to inefficient use of spectrum and energy. Adaptation represents the ability of network protocols and applications to observe and respond to channel conditions. Traditional simulation methodologies independently model the physical and higher layers. When multiple layer simulations are required, an abstraction of one layer is inserted into the other to provide the multiple layer simulation. However, recent advances in wireless communication technologies, such as adaptive modulation and adaptive antenna algorithms, demand a cross layer perspective to this problem in order to provide a sufficient level of fidelity. However, a full simulation of both layers often results in excessively burdensome simulation run-times. The benefits and possible parametric characterization issues arising due to the cross-layer integration of lower physical and higher network layers are investigated in this thesis. The primary objective of investigating cross-layer simulation techniques is to increase the fidelity of cross-layer network simulations while minimizing the simulation runtime penalties. As a study of cross-layer system design a medium access control (MAC) scheme is studied for a MANET wherein the nodes are equipped with smart antennas. Traditional MAC protocols assume the use of omnidirectional antennas. Nodes with directional antennas are capable of transmitting in certain directions only and significantly reduce the chances of collision and increase the effective network capacity. MANETs using omni-directional antennas severely limit system performance as the entire space around a node up to its radio range is seen as a single logical channel. In this research a MAC protocol is studied that exploits space division multiple access at the physical layer. This is a strong example where physical and MAC design must be carried out simultaneously for adequate system performance. Power control is a very important in the design of cellular CDMA systems which suffer from the near-far problem. Finally, the interaction between successive interference cancellation (SIC) receivers at the physical layer and power control, which is a layer 2 radio resource management issue, is studied. Traffic for future wireless networks is expected to be a mix of real-time traffic such as voice, multimedia teleconferencing, and games and data traffic such as web browsing, messaging, etc. All these applications will require very diverse quality of service guarantees. A power control algorithm is studied, which drives the average received powers to those required, based on the QoS requirements of the individual users for a cellular CDMA system using SIC receivers. / Master of Science

Most mobile nodes are operated using batteries, protocols which conserve energy are of interest. The Dynamic Directional Power Control Protocol (DDPC) is a protocol that dynamically varies the energy used in directional transmission to increase the battery life of the transmitter without sacrificing connectivity with the receiver. The advantage of DDPC is that it takes into account the remaining battery power of a node before changing its transmission power. DDPC can achieve a higher network lifetime when compared to a network where nodes use a fixed transmit power level. Meanwhile DDPC dynamically reduces the energy consumed by a node in transmission. It can also reach nodes far from the transmitter by using directional antennas.