The global mobile data traffic has increased tremendously in the last decade due to the technological advancement in smartphones. Their endless usage and bandwidth-intensive applications will saturate current 4G technologies and has motivated the need for concrete research in order to sustain the mounting data traffic demand. In this regard, the network densification has shown to be a promising direction to cope with the capacity demands in future 5G wireless networks. The basic idea is to deploy several low power radio access nodes called small cells closer to the users on the existing large radio foot print of macrocells, and this constitutes a heterogeneous network (HetNet). However, there are many challenges that operators face with the dense HetNet deployment. The mobility management becomes a challenging task due to triggering of frequent handovers when a user moves across the network coverage areas. When there are fewer users associated in certain small cells, this can lead to significant increase in the energy consumption. Intelligently switching them to low energy consumption modes or turning them off without seriously degrading user performance is desirable in order to improve the energy savings in HetNets. This dynamic power level switching in the small cells, however, may cause unnecessary handovers, and it becomes important to ensure energy savings without compromising handover performance. Finally, it is important to evaluate mobility management schemes in real network deployments, in order to find any problems affecting the quality of service (QoS) of the users. The research presented in this dissertation aims to address these challenges. First, to tackle the mobility management issue, we develop a closed form, analytical model to study the handover and ping-pong performance as a function of network parameters in the small cells, and verify its performance using simulations. Secondly, we incorporate fuzzy logic based game-theoretic framework to address and examine the energy efficiency improvements in HetNets. In addition, we design fuzzy inference rules for handover decisions and target base station selection is performed through a fuzzy ranking technique in order to enhance the mobility robustness, while also considering energy/spectral efficiency. Finally, we evaluate the mobility performance by carrying out drive test in an existing 4G long term evolution (LTE) network deployment using software defined radios (SDR). This helps to obtain network quality information in order to find any problems affecting the QoS of the users.

Upgrades to the University of Massachusetts S-Band FMCW boundary layer vertical wind profiling radar for use in the VORTEX-Southeast campaign are discussed. During the experiment, the radar characterizes velocity and reflectivity in clear-air and light to moderate precipitation conditions. Data is presented from the experiment which illustrates system performance and typical environmental results. This thesis begins with relevant background information on FM-CW radar operation, scattering mechanisms, and other calculations relevant to results discussed. The system hardware is described, along with improvements and modifications made prior to and during the experiment. Collected data is used to demonstrate system capabilities, improvements made, and remaining challenges. Various environmental features in the case of clear-air and precipitation are identified in the dataset. Several examples of Drop Size Distribution (DSD) estimates are presented, and the possibility of separating vertical wind speed biases from rain data is explored. Finally, the validity of results of DSD estimates are discussed.

<p>Conventional multiple description coding (MDC) is a source coding technique which provides resilience against packet loss. On the other hand, the correlation introduced between descriptions can be used to combat bit errors as well. While the latter feature of MDC has been attested and exploited in prior work, only few attempts have been made to design MDC with higher bit error resilience ability.</p> <p>This thesis makes some progress in the latter direction by addressing the problem of robust (i.e., bit error resilient) index assignment (IA) design for two description scalar quantizers. Our approach is to start from an initial IA which is known to be good for the conventional two description problem, and then apply permutations to indices in each description to increase a minimum Hamming distance-like performance measure.</p> <p>The criterion of increasing the minimum Hamming distance between valid index pairs (d_min), has been considered in prior work, however an efficient IA construction was presented only for the case of d_min = 2 and low redundancy.</p> <p>The contribution of this thesis is the following. For the scenario when one description is known to be error free, a new measure for IA robustness is proposed, which is termed minimum side Hamming distance (d_side,min). This quantity is defined as the minimum Hamming distance between valid indices of one description for fixed index of the other description. It is further shown that the problem of robust permutations design under the new criterion is closely connected to the anti-bandwidth problem in a certain graph derived from a hypercube. Leveraging this connection, permutations achieving d_side,min = 2 are proposed for all redundancy levels. Furthermore, for general values of d_side,min, a simple construction of permutations achieving d_side,min is presented, based on channel codes of appropriate block length and rate, and with minimum distance d_side,min + 1, respectively, d_side,min, for two types of initial IA (diagonal, respectively, square-based). The application of this result to achieve IA with d_side,min = 3 is further discussed for a wide range of redundancy levels.</p> <p>Finally, for the scenario when both descriptions may carry bit errors, simple constructions of permutations achieving d_min = 3 are proposed for the high redundancy case.</p> / Master of Applied Science (MASc)

We present a video-based system designed to enhance the efficiency of emergency preparedness and recovery. Our system includes two tools, one or emergency preparedness, and the other for emergency recovery. In our emergency preparedness tool, we 1) capture videos from the physical environment (e.g., University Campus, Knowles Engineering Building, North Station Subway Station), 2) generate an immersive virtual environment using these videos, 3) provide exploration and navigation mode in the virtual environment, and 4) allow users to make annotations of the environment and review these created annotations. By using this virtual environment, emergency personnel can familiarize themselves with the environment before their actual training in the physical setting. This tool can enhance the training experience of emergency responders as well as improve the training outcomes. Our emergency recovery tool includes two parts: 1) an Android application which captures the videos in the disaster site, and 2) a server that stores all these videos and provides visual analytics support. The recorded videos (both in indoor and outdoor settings), which include location and orientation information, are uploaded to the server that supports spatial queries. We developed tools for the investigators to review these videos, e.g., review videos in specific areas of interest. To test our tools, we select both outdoor and indoor environments. The results show that our tool works well in these situations.

Recently, many businesses are finding new ways to reach out to millions of people using a tool known as social media. Utilizing this tool, businesses are able to market their brand as well as instill company pride in their customers and employees. Top Fortune 500 companies like Walmart, Exxon Mobil, Costco, and Apple, to name a few, have a strong social media presence. Top aerospace companies such as Northrop Grumman, Lockheed Martin, and Boeing have taken advantage of the benefits. Interestingly, Loyola Marymount University has graced top social media sites with its presence. Popular social media websites include Facebook, Twitter, YouTube, lnstagram, and many others. When implemented correctly, social media will draw mass population to the brand and institution more than ever before. Businesses are able to advertise, familiarize, poll, and gauge interest with ease using social media. Businesses have gathered ideas or designs from the open public at no cost, or for a relatively cheap cash prize, to generate new products. There are many benefits that businesses can reap through the use of social media. With access to millions of users, businesses must remain ethical and responsible for their actions on social media sites. With posts that take seconds to upload, it is easy to make careless mistakes or create unintentional backlash from users. Ethics are important in social media and companies, such as Walmart, have published a set of social media Code of Ethics on their websites. Although social media is generally available at no cost to businesses, an organized team must be formed and managed. A significant budget is required to fund the labor hours for the media team, publishing department, contributors, and information security. Lean processes can be implemented to increase efficiency and reduce waste while quality ensures a robust process and continuous improvement. This integrative project will describe the System Engineering of the social media system from conception to maintenance. Compiling data found from internet resources, this project will integrate the different elements of social media to produce a system capable of efficiently marketing a company's brand to millions of people while delivering information that users demand. As evident from the above description, many elements of Systems Engineering can be applied to this social media system. This project will demonstrate how the application of the Systems Engineering tools and methodologies can optimize the implementation of the social media system to achieve the expectations of companies and users.

No description available.

Digital communications continues to be a relevant Field of study as new technologies appear and old methodologies get revisited or renovated. The goal of this research is to look into the old digital communication scheme of Bell 202 [67] used by APRS and improve software based demodulation performance. Improved performance is defined by being able to correctly decode more packets in an efficient, real time, manner. Most APRS demodulation is currently done using specialized hardware since that yields the best performance. This research shows that through using Sivan Toledo's javAX25 [72] software package, new demodulation algorithms can be implemented that decode more Bell 202 encoded AX.25 packets than the existing software could. These improvements may help drive the adoption of software demodulation since it is a low cost alternative to specialized hardware.

<p>In this thesis we study the handoff problem of mobile stations (MSs) jointly with the resource management at the access points (APs) for wireless mesh networks (WMNs), where the APs can dynamically adjust the transmission power and time to each of the associated MSs. Two objectives are considered, one is to balance the energy consumption of the APs, and the other is to achieve fair throughput among the MSs. Since the global optimum solutions are difficult to obtain, we propose heuristic schemes for achieving each of the objectives. The objective of balancing AP energy consumption is achieved in two steps. The optimum transmission power and rate is solved at each AP so that to minimize the energy consumption of the AP, assuming the MS-AP association is given. Two handoff schemes are then designed to find which MSs should be associated to which APs during each scheduling interval (SI). The schemes are based on energy consumption information exchanged among neighboring APs. The real-time energy balancing (REB) scheme tries to balance the energy consumption of the APs in each SI, while the long term energy balancing (LEB) scheme balances the AP energy consumption over a longer term. Our results indicate that the network lifetime can be significantly extended using the proposed handoff schemes, compared to the simple distance-based handoff scheme, and using LEB can achieve balanced AP energy consumption with a small number of handoffs. The second part of the thesis is to consider the MS handoff and AP resource allocations in order to achieve fair throughput among the MSs. An optimization problem is formulated and solved at each AP to achieve long term proportional fairness of the throughput among the MSs, assuming the MS-AP association is known. Two handoff schemes are proposed, one is utility-based, and the other is number-based, in order to determine which MSs should be associated to which APs. Our results show that both the schemes are good at achieving fair throughput among the MSs, and the schemes are not sensitive to MS moving speed or group mobility patterns. The number-based scheme is simpler than the utility-based one in terms of implementation.</p> / Master of Applied Science (MASc)

Thesis (Ph. D.)--Oregon Graduate Center, 1978.

Ph.D. / Physics / This work presents results pertinent to the study of spatial diversity as a means for partially overcoming the deleterious effects of the clear-air turbulent atmosphere on direct detection and heterodyne optical communication systems. For photon counting receivers, an averaged threshold receiver is presented, which is seen to be simpler to implement and to provide consistently lower bit error rates than optimized memoryless receivers. The heterodyne results include the introduction of a partial tracking heterodyne array; a discussion, both theoretical and experimental, of IF signal magnitude probability distributions for static heterodyne arrays; and a theoretical treatment of the probability distribution for a single heterodyne element with angle-of-arrival tracking.