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Fiber to the Rooms paradigm is gaining a lot of attention recently. In this paradigm, the last mile wireless (viz., IEEE 802.11×) connectivity, backed by optical fiber infrastructure, supports uncompressed high data rate while rendering seamless mobility and higher frequency reuse. To provide cost effective solution, Access Points (AP) in each room are replaced by distributed antennas. A centralized home communication controller provides AP functionality. WiFi inherently suffers from the problem of hidden nodes (HN). This problem persists even in the Fiber-Wireless (Fi-Wi) hybrid world causing degradation of throughput. In this paper we propose a Multi-User Multiple Input Multiple Output (MU-MIMO) uplink technique using both spatial and optical wavelength multiplexing. This scheme can increase the data rate significantly through diversity gain or spatial multiplexing. The proposed scheme is compared against an eminent joint decoding technique called Successive Interference Cancellation (SIC) adapted for operability in Fi-Wi indoor environment. The main contribution is that we propose an unique MU-MIMO uplink technique for Fi-Wi Hybrid indoor environment which address the problem of HN. We evaluate the performance of our proposed MU-MIMO technique based on ergodic capacity and probability of bit error.

The current service- and device discovery protocols are not platform- and network independent Therefore, proxy servers will be needed to extend the range of IP-based discovery protocols to non-IP domains. We developed an architecture of a proxy that enables UPnP devices and services to be discovered on the Bluetooth network and vice versa, and allows Bluetooth devices and UPnP control points to access and utilize services located on devices in the other network. We managed to keep all functionality needed for effective proxying running on a single device, e.g. the mobile phone or the Residential Gateway. © 2007 IEEE.

This paper discusses the research issues that need to be addressed in order to create a personal distributed environment where people interact with various companion, embedded, or invisible computers not only in their close vicinity but potentially anywhere. These systems are called personal networks (PNs). They constitute a category of distributed systems with very specific characteristics. They are configured in an ad hoc fashion, as the opportunity and the demand arise, to support personal applications. PNs consist of communicating clusters of personal digital devices, devices shared with other people and even infrastructure-based systems. At the heart of a PN is a core Personal Area Network (PAN), which is physically associated with the owner of the PN. Unlike the present PANs that have a geographically limited coverage, the Personal Operating Space, PNs have an unrestricted geographical span, and incorporate devices into the personal environment regardless of their geographic location. In order to do this they need the services of infrastructure-based networks and ad-hoc networks to extend their reach. A PN extends and complements the concept of pervasive computing. We show that PNs introduce new design challenges due to the heterogeneity of the involved technologies, the need for self-organization, the dynamics of the system composition, the application-driven nature, the co-operation with infrastructure-based networks, and the security hazards. We discuss the impact of these problems on network design, assess present and proposed solutions, and identify the research issues.

The main theme of this paper is the presentation of some critical issues such as transcoding, transport interworking, handover, congestion control and network scalability, that influence the integration of the UMTS and B-ISDN. Solutions to these issues will also be discussed. Furthermore, we will address a number of quantitative (i.e. performance) aspects of an integrated UMTS/B-ISDN system.

Recent studies show the existence of a demand for a connectionless broadband service. In order to cope with this demand, a connectionless protocol for the B-ISDN needs to be designed. Such a protocol should make use of ATM and the ATM Adaptation Layer. It needs to specify destination and bandwidth of connections to the ATM network without advance knowledge of the traffic that has to be transferred over these connection. A possible mechanism which can cope with this problem, the 'On-demand Connection with Delayed Release' (OCDR) mechanism, is described. Its eficient operation is based on the assumption that there exists a certain correlation between subsequently arriving CL packets. Two different arrival processes are used to evaluate the performance of the OCDR mechanism: a Poisson arrival process, and a Markov Modulated Poisson Process (MMPP) which models a bursty trafic source. Markov models of the OCDR mechanism have been constructed for both arrival processes. For the madel with Poisson arrivals, a closed form solution is presented. The model with MMPP arrivals is solved numerically. Compared to a 'Permanent Connection' mechanism significant bandwidth reductions can be obtained provided that the offered trafic has a bursty nature. Furthermore, the OCDR mechanism has the advantageous property that the obtained average node delay is not strongly related to the intensity and burstiness of the offered trafic.

Because of high data rate multimedia applications such as HD and UHDTV, online games, etc., the future home networks are expected to support short-range gigabit transmission. With the worldwide availability of 5 GHz spectrum at the 60 GHz band, it creates the opportunity for a promising air interface for future home networks. This dissertation is concerned with the application of the 60GHz band in an indoor networking environment. First, we find the solution for the problem of the smaller size of 60GHz cells. Indoor networks are more complex since they consist of a high number of access points. To reduce the complexity of the networks and extend the coverage, a Radio over Fiber (RoF) technique using OFM, which combines 60 GHz wireless and optical communication, has been employed. In the proposed network, all signal processing functions in antennas are now transferred to a central controller. In addition, QoS and mobility control algorithms can be performed easily. In indoor environments, the 60GHz radio link is highly obstructed by objects. Moreover, the overlapping area between two adjacent cells is small, and the optical network introduces an extra delay. Both the small overlapping area and the extra delay make handoff in the proposed network more difficult. To overcome this problem, a prediction model and a positioning system could be added to an RoF network. The indoor prediction model is based on a Hidden Markov Model. We show that this model is working well in an indoor environment in two simulation cases. Utilizing the location information of the mobile station (MS), a handoff algorithm is proposed. This algorithm reduces the number of cells to be considered for scanning in the handoff process. Thus, the handoff delay is reduced. Bandwidth resource management is also addressed by reserving bandwidth for handoff calls only in candidate cells. In this mechanism, only handoff calls can use the reserved bandwidth in each cell, new calls are not allowed to use it. In that manner, QoS can be maintained since the call dropping probability is decreasing. Finally, the feasibility of two centralized 60 GHz MAC protocols, IEEE 802.15.3 c and IEEE 802.11 ad, is investigated in an RoF network. The major effect on MAC protocols is the extra delay introduced by the optical links. The analysis indicates that the drop in the throughput when increasing the fiber length is not significant. Based on network parameters and the requirements of applications, the system should apply an adaptive ACK mechanism.

Over the last couple of decades, wireless communication has proved to be a phenomenal success and has generated a booming industry with over 5 billion mobile handsets in use worldwide. This has on one end eased the life of its users while on the other end has introduced new challenges for wireless system designers. The varying nature of the wireless communication channel results in large differences in the instantaneous received signal strength. Since most mobile terminals are battery powered and operate in a network, simply increasing the transmission power is not an attractive solution, as it reduces the battery life and increases interference. Thus a major challenge in wireless communication is to increase the communication rate and link reliability by utilizing low power, low cost and spectrally efficient systems. Even with the advent of efficient signal processing techniques and miniaturized low power signal processing hardware, the physical bottleneck still remains the available system bandwidth. This has led to the introduction of the 60 GHz band as an attractive alternative. Among other benefits, the 60 GHz band is unlicensed and can provide system bandwidths up to 7 GHz, which is ideally suited for short range indoor wireless services such as wireless local area networks. There are, however, certain challenges that need to be overcome before full potential of 60 GHz band can be harnessed. These challenges include the design of hardware components such as antennas, amplifier and mixers, identification and utilization of suitable base band processing algorithms and efficient communication protocols for wireless networks operating in the 60 GHz domain. This dissertation deals with the design and development of baseband processing techniques for communication devices operating at a carrier frequency around 60 GHz. Firstly, two practical candidates for baseband implementation are identified. The performance of these two alternatives namely single-carrier and multi-carrier is analyzed under various radio frequency circuit imperfections such as phase noise and amplifier non-linearity because low cost radio frequency circuits operating in the 60 GHz band are expected to have less than ideal performance. For both schemes, the performance degradation in terms of operating parameters such as the required number of bits in digital-to-analog converter/analog-to-digital converter and input back-off requirements for the power amplifier as a function of bit error probability, is determined. It is shown that the single-carrier schemes suffer a lower degradation in system performance for a given set of circuit parameters. The single-carrier scheme is therefore, identified as a suitable candidate for 60 GHz baseband implementation. Secondly, we investigate the possibility of using low cost and complexity RF level diversity combining schemes to boost the system performance. Three low complexity diversity combining schemes namely equal gain combining, selection combining and switched combining are considered. An analytical framework for system performance evaluation of different diversity combining schemes by using low complexity RF level quantized phase combining is developed. Analytical expressions for the bit and symbol error rate of multi-level phase shift keying modulated symbols over Rayleigh fading channels are derived. The derived expressions are then utilized to compare the performance with non-coherent schemes under diversity reception. It is shown that the number of quantization levels required to achieve near ideal performance are dependent on the number of the receive antennas and the modulation level. The analysis is also utilized to investigate the impact of phase quantization on the switching threshold for switched combining schemes. It is shown that the switching threshold is not severely affected by phase quantization. The ability to perform various system level trade-offs is also demonstrated. Lastly, a low cost audio demonstrator is proposed. The acoustic channels investigated in this thesis are seen to provide a multi-path rich environment typical of 60 GHz channels. This offers a practical way of verifying the performance of various baseband processing algorithms in a cost effective manner.

As an emerging short-range wireless technology, IEEE 802.15.4/ZigBee Wireless Sensor Networks (WSNs) are increasingly used in the fields of home control, industrial control, consumer electronics, energy management, building automation, telecom services, personal healthcare, etc. IEEE 802.15.4/Zig-Bee WSNs share the same 2.4 GHz license-free Industrial, Scientific, and Medical (ISM) band with many other wireless systems such as IEEE 802.11b/g WLANs, Bluetooth, cordless phones, etc. Due to the low power, IEEE 802.15.4/ZigBee WSNs are potentially more vulnerable to interference by those systems. Among those systems, IEEE 802.11b/g WLANs are probably the most widely deployed ones. Because of their complementary applications, IEEE 802.15.4WSNs and IEEE 802.11b/gWLANs are often colocated, which causes the coexistence issue between them. In this thesis, we focus on the coexistence between IEEE 802.15.4/ZigBee WSNs and IEEE 802.11b/g WLANs. The targets of this thesis work are to achieve a clear understanding on the coexistence issue between IEEE 802.15.4/ZigBee WSNs and IEEE 802.11b/g WLANs, and then to propose cost-effective methods to enhance the coexistence capability of IEEE 802.15.4/ZigBee WSNs. Although many studies on the coexistence issue between IEEE 802.15.4/Zig-Bee WSNs and IEEE 802.11b/g WLANs have been done, the conclusions they drew are incomplete and/or conflicting, and therefore confusing. To get a clear understanding about the coexistence issue between them, an extensive study is needed. First, we propose a coexistence model of IEEE 802.15.4 nodes and IEEE 802.11b/g nodes. The model is based on two aspects, i.e., power and the timing. Due to the significant difference in transmit powers of IEEE 802.15.4 and IEEE 802.11b/g, the sensing ranges of them are quite asymmetric. As a result, three distinct coexistence regions can be identified. In each of these coexistence regions, IEEE 802.11 nodes and IEEE 802.15.4 nodes exhibit different interactive behavior and hence different coexistence performances, which may not be the same as we expected. For example, instinctively, we may feel that the closer an IEEE 802.15.4 node gets to an IEEE 802.11b/g interferer, the worse performance the IEEE 802.15.4 node would have. Our coexistence model, however, reveals that this perception is not true. In fact, as the IEEE 802.15.4 node and the IEEE 802.11b/g interferer get so close that they are in the coexistence region R1, where they can sense each other, the coexistence performance of the IEEE 802.15.4 node is not necessarily the worst. Instead, in the coexistence region R2, where the IEEE 802.11b/g interferer cannot sense the IEEE 802.15.4 and therefore does not respect the IEEE 802.15.4 transmission, the coexistence performance of the IEEE 802.15.4 node could get even worse than in R1. Clearly, the three coexistence regions and the different interactive behavior between IEEE 802.15.4 WSNs and IEEE 802.11b/g WLANs in each region explain the incomplete/conflicting conclusions drawn by many previous studies from their incomplete analysis and/or observations. Next, by taking into account some important implementation factors, we improved the coexistence model and studied the coexistence performance of IEEE 802.15.4 WSNs under IEEE 802.11b/g interference in a real-life environment. We revealed that some implementation factors such as IEEE 802.15.4 Rx-to-Tx turnaround time and Clear Channel Assessment (CCA) partial detection effect can have significant impact on IEEE 802.15.4 WSNs coexistence performance in reality, e.g., a long IEEE 802.15.4 Rx-to-Tx turnaround time can impair the CCA performance and therefore the IEEE 802.15.4 WSNs coexistence performance. The enhanced model can precisely explain and predict the IEEE 802.15.4WSNs coexistence performance. Furthermore, under the guidance of the model, the IEEE 802.15.4 WSNs coexistence performance were extensively investigated in all of the three coexistence regions in different scenarios by analysis, simulation and experiments. The simulation and experimental results agree with our analysis. Based on the clear understanding achieved from the work above, we then explore the solutions to help IEEE 802.15.4 WSNs deal with interference. Basically, there are two categories for the ways of dealing with interference: interference control/mitigation and interference avoidance. We address solutions in each of these two categories, respectively. We first propose an interference mitigation approach, which enables an IEEE 802.15.4 WSN to mitigate heavy interference by adaptively adjusting CCA thresholds of its nodes in a distributed manner. As the heavy interference appears, the CCA thresholds are increased in order to reduce the inhibition loss, whereas the CCA threshold gets decreased so as to avoid having a permanent channel access privilege over peers as the interference disappears. Compared to the centralized interference management approaches, e.g., the frequency agility approach specified in the ZigBee specification, which inappropriately assumes a reliable two-way communication between nodes even in the presence of heavy interference, our adaptive CCA approach is simpler but more robust, more responsive, and easier to be implemented at a lower cost. The simulation results validate that the adaptive CCA approach may significantly improve IEEE 802.15.4 WSNs performance in the presence of heavy interference. Then, we consider an interference avoidance solution. ZigBee specification proposes a feature called frequency agility, which refers to the ability of ZigBee networks to change the operational channel in the presence of interference. However, for a large-scale ZigBee network, changing the whole network operational channel to an idle one, may be neither appropriate if there is only local interference nor possible if there is no single idle channel available globally. Therefore, we propose a distributed adaptive interference-avoidance multi-channel protocol, which enables a conventional single-channel largescale ZigBee network to distributively, adaptively and partially change the operational channel in the presence of local interference. As a result, the Zig-Bee network performance under interference can be effectively and efficiently improved. The main contributions of this thesis are a coexistence model of IEEE 802.15.4/ZigBee WSNs and IEEE 802.11b/g WLANs, and two solutions to the coexistence issue between them. The model not only explains the interesting interactive coexistence behavior of the two systems, but provides many insights on the coexistence issue. Under the guidance of those insights, two solutions are proposed. The solutions can enhance the coexistence capability of IEEE 802.15.4/ZigBee WSNs and therefore their coexistence performance in the presence of interference, which includes but not limited to IEEE 802.11b/g interference.

Wireless communication and networking technology has facilitated people to be connected with each other closely. Cellular network is evolving now from the third generation to the fourth generation. In the meanwhile we are experiencing the demand for wireless networks which can facilitate the communication between humans and environment, human and machines or even machine and machine. Such networks will help us know more about our surroundings which could lead us towards a better and greener life. Wireless Sensor Networks (WSN) is one candidate among such networks. It turns sensing tasks from small scale, centralized and expensive to large scale, distributed and low-cost by connecting small battery powered sensors with wireless links. We start the thesis by introducing WSN, its background and current status in Chapter 1. Although a lot of work has been reported in the literature on WSN, there are still many challenges. In this thesis, we focus on five of them, namely, (1)energy, (2)reliability, (3)scalability, (4)ease of use and (5)ease of set up. Energy is a challenge since WSNs are powered by batteries or even energy harvested from the ambience. The second, fourth and the fifth challenges are the hindrance in the way of high adaptation of WSNs while the third one will challenge when WSNs are largely deployed. Motivations and contributions of the thesis are also presented in the first chapter. Chapter 2 gives an overview of the literature in the several categories, such as physical layer, MAC layer, networking layer, synchronization and real deployment. Our work in the rest of the thesis is related to the work introduced in this chapter. We present the first result of our research in Chapter 3, which focuses on energy and reliability challenge on link layer. To improve the reliability of a link, we have to know the quality of the link. Thus we firstly analyze and try to improve link quality estimation methods in the chapter. We propose a new method for the estimation of packet delivery ratio which balances estimation accuracy and the overhead it causes. Then Minimum Energy Packet Forwarding (MEPF) protocol is proposed with the purpose of delivering a packet reliable with least amount of energy. MEPF tries to achieve the objective by tuning transmission power online for each packet with respect to the link quality. If a packet is lost, MEPF retransmits it smartly only when the link is considered to be good enough. Experimental results prove that MEPF uses almost the lowest possible transmission power without increasing the packet loss and retransmits a lost packet only once to eventually deliver it. We move a layer up from MAC to the network layer in Chapter 4. We organize a network into a better topology to improve energy efficiency and scalability. Two types of topologies are considered in this chapter, flat and clustered. In the former one each node has the same role while in the latter one nodes are organized into clusters where a node is either a Cluster Head (CH) or a Cluster Member (CM). We firstly analyze why a clustered topology may save energy then we quantify the saving. Since traffic is reduced in a clustered network, less contention or collision is expected and more nodes can communicate simultaneously. Thus a clustered network is highly scalable. To form a cluster topology from a flat one, we propose a cluster forming protocol which selects least amount of CHs which have the highest remaining energy. Thus they can live longer under higher traffic load compared to CMs. Simulation results show the feasibility and performance of the proposed protocol. Chapter 5 improves accuracy of localization, one of the most important WSN applications. One reason for the low accuracy is that the radio coverage of small and inexpensive antennas on sensor nodes, especially those in a Body Area Sensor Networks (BASN), is not omnidirectional. This problem leads to the failure of many localization protocols to achieve good accuracy since they are based on the assumption of omnidirectional antennas. In the chapter we proposed to use multiple receivers to locate a person in the context of a BASN. This method improves localization accuracy from a single receiver by mitigating the errors caused by varied and non-uniform beamwidth of antennas and combating fading with spatial diversity. We test this method in two classes of localization methods. The outcome of experimental results show that the method achieves a higher accuracy than a single receiver. Thus the reliability of localization is improved. Setting up a WSN especially for experiments is cumbersome and time-consuming process. It impacts the ease of use and set up. Thus we propose a framework for flexible and low-cost testbed in Chapter 6. Such a testbed only has sensor motes. Other than experiments, testbed management such as downloading the experimental code, reprogramming, testbed control, logging and collecting experimental results and synchronization are all carried out by the sensor motes wirelessly without extra devices. Thus a low-cost testbed can be set up quickly. A case study which realizes components in the framework is also presented. Finally the results of the thesis are summarized in Chapter 7. Future work is also presented there.

Ultra Wideband (UWB) technology offers an unprecedented opportunity to further accelerate the evolution of wireless communication and expand the application landscape by enabling outstanding capabilities. UWB radio is fundamentally different from most radio technologies, e.g., Bluetooth, WLAN, etc. UWB has many forms. A promising but, not well explored form is single-band impulse radio UWB (IR-UWB). In IR-UWB data is transmitted by using a series of very narrow pulses rather than by modulating the data onto a carrier. IR-UWB has considerable potential benefits for high-bandwidth, low-power, low-cost and short-range communications, that make it a candidate for high-performance Wireless Personal Area Networks (WPAN). On the road to IR-UWB based ad hoc networking, there are technical and implementation challenges to be faced. Whether the capabilities and features of IR-UWB systems can be exploited in ad hoc networking has not been systematically investigated and how the network design takes IR-UWB peculiarities into account is kept open. This thesis concentrates on those open research topics. With IR-UWB technology, the richness of simultaneous non-interfering physical channels and the capability of full-duplex are the features that can bring real benefits in network design. Furthermore, impulse radio has an intrinsic flexibility, because the parameters of the physical layer can be explicitly controlled by the upper layers. Therefore, the IR-UWB features allow a simplified medium access control and the network topology can be either organized in a structured or a less structured way. A fundamental topic in designing self-organizing IR-UWB ad hoc networks is the automatic discovery of in-range devices and the dynamic organization of the access to radio resources shared among the devices. In this thesis a data link layer protocol based on time hopping is proposed to enable a device to discover most of its neighboring devices within a short discovery time and avoid collisions. The performance measures (delay time, network throughput) of the proposed protocol are evaluated using both simulations and analytical models to understand the behavior of such self-organizing processes. WPANs are usually ad hoc networks; we consider in this thesis ad hoc IR-UWB WPANs. They require a timely network establishment without relying on any infrastructure. An IR-UWB system can accomplish multiple access by using code division multiplexing, allowing multiple simultaneous transmissions. We propose and investigate a data link layer protocol for single-hop, high data rate IR-UWB WPANs to achieve efficient network initialization and channel management with low control overhead and limited interference. As an extension of our research on single-hop IR-UWB networks, we address the problem that IR-UWB device participating in a WPAN are not always reachable in a single-hop. A network architecture and a set of protocols are proposed to resolve the multi-hop communication among IR-UWB devices as well as enhance channel utilization efficiency. In summary, the essential research activity carried out in this thesis is the data link layer design for IR-UWB ad hoc networks for short-range, high data rate wireless applications. Our results facilitate self-configuration and topology adaptation in a timely fashion, and achieve efficient medium access and multi-hop communications.

The unlicensed frequency band around 60 GHz is a very promising spectrum due to its potential to provide multiple gigabits per second based data rates for short range wireless communication. Hence, 60 GHz radio is an attractive candidate to enable ultra high rate Wireless Personal Area Networks (WPANs), which are expected to support wireless multimedia applications like high-definition video streaming, ultra high speed content download, etc. Till now, the main research effort related to 60 GHz radio is at the physical layer design and channel model investigation. However, the unique properties of 60 GHz radio also create new research challenges for 60 GHz networking. Hence the aim of this dissertation is to provide an in-depth view on the Medium Access Control (MAC) layer and Network layer design for 60 GHz WPANs. To obtain sufficient link budget for multiple gigabits per second based wireless communication, directional antennas are needed in 60 GHz systems. Although directional antennas exhibit many advantages compared to omni-directional antennas, their deployment is very challenging for the MAC and Network layer protocols. For instance, to set-up directional connections, devices are expected to know the direction of their neighbors. The performance of directional neighbor discovery protocols is investigated in this dissertation to review the impact of directional antennas on the network setup durations. With the knowledge of orientation information of the network components, a resource management scheme, especially for the IEEE 802.15.3 featured WPANs, is proposed to support concurrent transmissions using directional antennas in a Time Division Multiple Access (TDMA) fashion with Quality of Service (QoS) and fairness provisioning. To further improve the transmission efficiency of the MAC layer protocol, standard frame aggregation and low latency frame aggregation mechanisms are investigated to alleviate the impact of transmission overhead. Another issue addressed at the MAC layer in this dissertation is how to support highly-reliable transmissions using 60 GHz radio. Due to the weak penetration and reflection properties, the Line-of-Sight (LOS) link between two 60 GHz components is easily blocked by obstacles in indoor environments, which is a severe hurdle that influences the reliability of 60 GHz systems. To resolve the link blockage problem, instant decision based beam switching mechanisms and environment learning based beam switching mechanisms are proposed in this dissertation targeting for different usage scenarios. Furthermore, to support the coexistence of multiple 60 GHz WPANs, a systematic analysis of using synchronization frame to mitigate Co-Channel Interference (CCI) is performed. It has been shown that the link capacity and the guaranteed transmission distance within a WPAN are upper bounded by the CCI. To enable the multi-hop communication among these inter-connected 60 GHz WPANs, the Network layer design is involved in this dissertation. First, a fundamental investigation is provided in ad-hoc networks for using directional antennas in the aspects of topology control and message dissemination. The results provide valuable insights for using directional antennas for multi-hop communication. Second, focusing on the specific network topology of WPANs, the performance of inter-piconet route discovery is examined. Moreover, a joint QoS routing and channel resource allocation mechanism is proposed to resolve the inter-piconet channel resource reservation collision problem.

Networking technologies have been changing the life of people in their private residential space. With the arrival of high definition (HD) multimedia services and broadband communications into the living space, future home networks are expected to support high speed device-to-device connectivity with Quality-of-Service (QoS) provisioning. There is no prize for guessing that it has to be wireless communication which creates maximal freedom. Nevertheless, it is doubtful that today's home networking technologies can sufficiently lead to the expected future of HD multimedia. Especially the maximum data rate and QoS that the network is expected to deliver have being pushed to the limits, which leads to users experience far from satisfying. In response to the critical throughput demands, the 60 GHz radio technology presents itself as an ideal solution for short-range Gbps speed indoor communication. However, from the networking point of view, the transmission range limitation and high line-of-sight (LOS) dependency are impediments for reliable connectivity at 60GHz. This leads us to critically examine current networking architecture (Chapter 3) and propose newer ones. We proposed two types of communication infrastructure with emphasis on deployment and capacity to overcome the range limitation of 60 GHz radio. The cell based infrastructure employs the radio-over-fiber (ROF) technique and brings great exibility for integrating 60 GHz radio into a multi-radio home networking environment. The ad hoc infrastructure creates a strictly wireless home networking environment, which provides maximum freedom in terms of usability. Further to resolve the dilemma of the increased network complexity and higher expectation of users on the quality of experience, we proposed functional network architecture focusing introducing "Cognitive Plane". It is expected to help in realizing more advanced control and management functions for enhancing service provisioning and ultimately usability of a home network to meet the expectations of users. The network architecture has sought to provide the fundamental communication means to provide in-home device-to-device 60 GHz connectivity. It leads us further towards the network protocol issues to provide reliable end-to-end connectivity with QoS. However, before setting out on specific solutions, it is of great importance to understand the features of the 60 GHz radio link in the home environment. First, we built a link stability model to understand the influence of a single link on LOS dependency under different channel conditions, antenna configurations and movement patterns of people (Chapter 4). Further to understand the performance starting from single hop to multiple hops, we studied the IEEE 802.15.3 MAC protocol and extended it to enable connectivity on the proposed ad hoc communication infrastructure (Chapter 5). To offset the influence of LOS dependency we further studied the potential use of multiple paths (Chapter 6). We proposed a cross-layer approach for assessing the multipath capacity with regard to high quality video transport. We also used the possible video coding techniques for video source and evaluating traffic allocation schemes for their abilities to make use of the capacity of multiple paths. In the cell based communication infrastructure, which is designed to support multiple radio systems, the dip in signal strength due to blocking of a 60 GHz link can be alleviated by vertical handover of a communication session to another radio to maintain the continuity of the session. However, neither the residential users nor the third party are practically able to manage such network operations in such a detail. The irregular blocking due to the presence of people throws a further challenge - solving the incertitude during handover. With the help of Artificial Intelligence (AI) based cognitive techniques, we investigated two decision making approaches utilizing Decision Theory (DT) and Markov Decision Process (MDP) (Chapter 7). Both of them are able to take into account multiple factors to make decisions in uncertain situations based on an evaluation of the candidate actions, but with different time horizons. The techniques within the cognitive networking framework can help in establishing reliable connection and application provisioning adaptively. The communication sessions are transported seamlessly without the intervention of users. Cognitive network is considered as one of the most distinguishing features of a future-proof home networking paradigm. Therefore, we looked into the proposed cognitive plane with special focus on provisioning location context information (Chapter 8). The 60 GHz radio LOS is largely influenced by the movement of people around, network devices and surrounding objects such as furniture and partitions. Thus awareness of location sustains important functionalities such as optimal radio and route selection, session transfer, self-organization and maintenance of the network etc. We designed and demonstrated an indoor positioning system using wireless sensor network as an important auxiliary component in the design of cognitive home network architecture of the future. In this dissertation we concentrated on investigating the feasible networking technologies for future homes supporting high quality high data rate multimedia services. At the same time, we are seeking approaches for embracing cognitive networks in the home network domain to assure a better user experience. Our contributions in this dissertation are in the right direction for future-proof inhome networks, by addressing both radio and network, from both architectural and protocol perspectives.

Ultra-wideband (UWB) is a promising technology that offers a potential solution for the data rate, cost, power consumption and physical size requirements of the next generation wireless devices. UWB may also play an important role in the realization of future heterogeneous networking. This technology has recently gained significant interest from both academia and industry. The strength of the UWB lies in the very large instantaneous bandwidth that is used and the potential for simple transceiver architectures. This thesis deals with several important aspects of the UWB technology, including modeling of feasible ultra-wideband impulse radio (UWB-IR) systems, their performance characterizations, and suitable methods for protection against errors. The main goal of this thesis is to propose and evaluate novel error control techniques particularly suitable for UWB-IR systems operating in severe multipath interference prone environments. The proposed methods exploit the temporal diversity brought by the UWB channels through multipaths and as a result allow for the alleviation of destructive effects of inter-symbol (ISI), inter-frame (IFI), and inter-pulse (IPI) interference. We found that rearranging the order of UWB chips or UWB frames results in a bit error rate (BER) performance improvement. This improvement is particularly apparent in case of UWB-IR systems with frame repetition as the method of protection against errors. The novelty of the presented analysis is that it considers ISI, IFI, and IPI effects, RF front-end issues and real antenna characteristics that are often neglected by the researchers. Moreover, they are presented, for the first time, for the given type of the simple incoherent receiver architecture (differential autocorrelation receiver), channel coding scheme (superorthogonal convolutional coding), and channel model (IEEE 802.15.3a multipath fading channel).

In the past several years, personal mobile devices have developed rapidly as versatile computing platforms, capable of installing and running many different applications. Often, these devices are equipped with multiple (wireless) network interfaces supporting internet access through one or more networks. The availability of these networks is dynamic over time, because the device owners move in and out of range during their daily activities: a device may connect to an ultra-wideband access point at home, simultaneously use a Bluetooth network and a cellular network while traveling, and connect to an 802.11 wireless local area network (WLAN) at work. Applications on mobile devices therefore experience intermittent connectivity or fluctuations in available throughput capacity when communicating with other nodes on the internet. Mobile applications may benefit from taking into account aspects of these dynamics – for instance, by adapting data rates to maximum available capacity or controlling when to scan and activate specific networks. Furthermore, they may provide a better service to the user when taking into account in a proactive manner the availability of these networks over time. This dissertation covers two aspects that are important for applications dealing with dynamic network resources on personal mobile devices. We define (1) a mechanism that provides applications with awareness of and control over current resources in a comprehensive, cross-layer way, and (2) we describe an approach to predict the future time of the occurrence of a network resource event, such as getting into range or moving out of range of a particular network, using traces of resource availability in the past.

The next generation communication devices are foreseen to not only support a large variety of applications, ranging from speech, audio and video graphics but also be able to maintain connection with many other devices (rather than a single base station) in different changing environments. The aim of the dissertation is to analyze digital modulation and coding techniques for wireless communication systems in realistic transmission scenarios. Furthermore, an important objective of the dissertation is to explore the degrees of freedom that can make the wireless communication systems overall more adaptive, thereby, resulting in systems that either consume less power for a given performance or offer more performance for a given amount of average energy than conventional systems. The techniques/algorithms analyzed in the dissertation are versatile and suitable for both narrowband as well as wideband wireless communication systems for indoor and low-mobility outdoor scenarios. Signal space diversity, also known as modulation diversity, is used to increase the overall received signal-to-noise ratio (SNR) and to reduce the probability of error. A thorough performance analysis of modulation diversity systems is presented in the thesis to understand the differences from conventional systems in narrowband and wideband channels and also to achieve the maximum possible performance. General methods are presented to optimize the system parameters and to exploit the degrees of freedom available. Channel coding, cooperative demodulation and decoding, and orthogonal frequency division multiplexing (OFDM) schemes are coupled with modulation diversity to reduce the overall power consumption and improve system performance.