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In this thesis we investigate improvements in efficiency of wireless communication networks, based on methods that are fundamentally different from the principles that form the basis of state-of-the-art technology. The first difference is that broadcast and superposition are exploited instead of reducing the wireless medium to a network of point-to-point links. The second difference is that the problem of transporting information through the network is not treated as a flow problem. Instead we allow for network coding to be used. First, we consider multicast network coding in settings where the multicast configuration changes over time. We show that for certain problem classes a universal network code can be constructed. One application is to efficiently tradeoff throughput against cost. Next, we deal with increasing energy efficiency by means of network coding in the presence of broadcast. It is demonstrated that for multiple unicast traffic in networks with nodes arranged on two and three dimensional rectangular lattices, network coding can reduce energy consumption by factors of four and six, respectively, compared to routing. Finally, we consider the use of superposition by allowing nodes to decode sums of messages. We introduce different deterministic models of wireless networks, representing various ways of handling broadcast and superposition. We provide lower and upper bounds on the transport capacity under these models. For networks with nodes arranged on a hexagonal lattice it is found that the capacity under a model exploiting both broadcast and superposition is at least 2.5 times, and no more than six times, the transport capacity under a model of point-to-point links.

The growing popularity of the Internet and the increasing demand of services based on IP have influenced the evolution of home networks. From a simple network constituted by just a PC and a modem, the home network has become a complex environment providing connectivity to several devices with different capabilities. Although service providers possess tools to manage their own core and access networks, they lack the tools to get information related to home network characteristics. Due to the impact of home network configurations on delivered services, operators are interested in diagnostic tools able to gather information about the topology of the home network, the link layer technologies that are used and which are the active devices requiring home network connectivity. The goal of this thesis is to study the currently available topology discovery protocols and evaluate their suitability for home networks. Our work focuses on two protocols that are believed by the service providers’ community to be appropriate for the home network scenario. These two protocols are the Link Layer Topology Discovery (LLTD) protocol and the Link Layer Discovery Protocol (LLDP), the latter also known as IEEE 802.1AB. Our study includes the definition of a set of performance indicators for topology discovery protocols and a performance analysis of LLTD and LLDP for different conditions and topologies. We designed several experiments representing the most common home network configurations, and carried out measurements that provide the data needed for our analysis. Based on the obtained results, we then proposed a novel topology discovery architecture, called Home Network Topology Discovery (HNTD) that fulfills most of operators’ requirements, in contrast to LLTD and LLDP.

Terrestrial Trunked Radio(TETRA) is a narrow band digital cellular network for Private Mobile Radio (PMR) communications mainly designed for voice communications with limited packet data capability because of band-width limitations. This limited packet data capability of TETRA is used for the integration of the TETRA network with wireless mesh networks. The wireless mesh network used in this thesis work is part of the FIGO network. FIGO is a robust communication system mainly intended for public safety communications and it consists two main network parts. One of these parts is the wireless adhoc network which can be deployed on incident areas. The oher one is the infrastructure omponent (back office node) that is used to nterlink disconnected adhoc nodes and it can also offer access for controlling an incident in the adhoc network. The FIGO network uses different communication technologies to link the adhoc network with the back office node and the main aim of this thesis work is to integrate the TETRA network with the FIGO network so that the TETRA can be used as one of the links from the adhoc network to the back offie node of the FIGO network. The main problem of the TETRA-FIGO integration is that the wireless adhoc network generates a lot of control signals that can easily overload the narrowband packet data channel of the of the TETRA network. In addition to the control overheads, the excessive headers also contribute a lot of overheads to the narrowband TETRA channel. Two architectures are proposed in thesis report to integrate TETRA with the FIGO network and the performance of these two new proposed architectures is analyzed and compared with the existing FIGO network protocols in terms of control traffic and header overheads.

Typically, in a wireless data network, all devices use the same channel (i.e. the same frequency) so that they can easily communicate with each other. However, as node density increases, the throughput share of each device decreases due to contention of the wireless medium. It seems that the capacity problem in wireless mesh networks can be alleviated by equipping the nodes with multiple radios tuned to non-overlapping channels. In theory it should be possible to have simultaneous reliable transmissions on orthogonal non-overlapping channels. In practice though, due to signal leakage from one channel to another, transmissions on these non overlapping channels interfere with one another. In this thesis, I claim that the assumption of perfect independence between non-overlapping operating channels does not always hold in general. During this work, I have done some practical measurements about adjacent channel interference, taking into consideration various factors such as antenna separation, number of channels and radio, transmit-power and packet size. I have compared the interference effects in different channels. Furthermore, I have evaluated and studied the causes and effects of adjacent channel interference via analysis, calculations and simulation. In order to cope with this problem, a classification of possible solutions which are feasible is discussed, and then by adopting the concept of reservation, I propose a solution called MRR (Multi-Radio Reservation). Finally the proposed solution is evaluated.

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