Millimeter wave wearable communication networks : analytic modeling and MIMO support

Future high-end wearable electronic devices including virtual reality goggles and augmented reality glasses require rates of the order of gigabits-per-second and potentially very low latency. Supporting high data rate wireless connectivity for applications such as uncompressed video streaming among wearable devices in a densely crowded environment is challenging. This is primarily due to bandwidth scarcity when many users operate multiple devices simultaneously. The millimeter wave (mmWave) band has the potential to address this bottleneck, thanks to more spectrum and less interference because of signal blockage at these frequencies. This dissertation addresses key questions that need to be answered before realizing mmWave-based wearables in practice: (i) what are the expected achievable rates in a crowded user environment, with mmWave devices using a given hardware configuration? (ii) how is the wireless connectivity affected in an indoor operation, which is prone to surface reflections? (iii) can multi-stream data transmission, involving large bandwidth communication under hardware constraints be realized? To answer these, tools from stochastic geometry and compressive sensing, and architectures involving hybrid analog/digital multiple-input multiple-output (MIMO) are leveraged. The main contributions of this dissertation are 1) analytical modeling to compute average achievable rates in mmWave wearable networks consisting of finite number of user devices and human blockages, 2) characterizing the impact of reflections and non-isotropic performance of mmWave wearable networks in crowded indoor environments, 3) channel estimation to support MIMO for wideband mmWave wearable devices using hybrid architecture, and 4) designing optimal, but easy-to-implement, precoding/combining strategies in frequency-selective mmWave systems. Both analysis and numerical simulations show how the proposed evaluation methodology and solutions serve to enable mmWave based communication among next generation wearable electronic devices.Electrical and Computer Engineerin

Physical Layer Network Coding for Two-Way Relaying with QAM

The design of modulation schemes for the physical layer network-coded two way relaying scenario was studied in [1], [3], [4] and [5]. In [7] it was shown that every network coding map that satisfies the exclusive law is representable by a Latin Square and conversely, and this relationship can be used to get the network coding maps satisfying the exclusive law. But, only the scenario in which the end nodes use $M$-PSK signal sets is addressed in [7] and [8]. In this paper, we address the case in which the end nodes use $M$-QAM signal sets. In a fading scenario, for certain channel conditions $\gamma e^{j \theta}$, termed singular fade states, the MA phase performance is greatly reduced. By formulating a procedure for finding the exact number of singular fade states for QAM, we show that square QAM signal sets give lesser number of singular fade states compared to PSK signal sets. This results in superior performance of $M$-QAM over $M$-PSK. It is shown that the criterion for partitioning the complex plane, for the purpose of using a particular network code for a particular fade state, is different from that used for $M$-PSK. Using a modified criterion, we describe a procedure to analytically partition the complex plane representing the channel condition. We show that when $M$-QAM ($M >4$) signal set is used, the conventional XOR network mapping fails to remove the ill effects of $\gamma e^{j \theta}=1$, which is a singular fade state for all signal sets of arbitrary size. We show that a doubly block circulant Latin Square removes this singular fade state for $M$-QAM.Comment: 13 pages, 14 figures, submitted to IEEE Trans. Wireless Communications. arXiv admin note: substantial text overlap with arXiv:1203.326

Efficient video transfer using LAN caching assisted by cloud computing

There is a good probability of accessing same video content multiple times from a cloud based Video Streaming Server by same peer or different peers of a given LAN, effectively increasing Internet bandwidth or data flow for same content from server to client, thereby over loading routers between server and client and also resulting in higher power consumption at routers. This proposed concept tries to avoid multiple streaming of high volume video files from Server by caching first successful streamed data on to LAN peer which is currently viewing the video data and subsequently the same LAN peer streaming the video to other desiring peers when demanded for. Proposed implementation model retains all other server activities with server except for allowing an available LAN peer copy of video to be streamed to another peer of the same LAN when requested for

Fault tolerant BeeHive routing in mobile ad-hoc multi-radio network

In this paper, fault tolerance in a multi-radio network is discussed. Fault tolerance is achieved using the BeeHive routing algorithm. The paper discusses faults added to the system as random fluctuations in hardware radio operation. The multi-radio nodes are designed using WiMAX and WiFi Radios that work in conjunction using traffic splitting to transfer data across a multi-hop network. During the operation of this network random faults are introduced by turning off certain radios in nodes. The paper discusses fault tolerance as applied to multi radio nodes that use traffic splitting in the transmission of data. We also propose a method to handle random faults in hardware radios by using traffic splitting and combining it with the BeeHive routing algorithm

IOBR: Interoperable bee-hive routing in a heterogeneous multi-radio network

WiMAX and WiFi are the two proliferating wireless technologies with different physical and Media Access Control (MAC) layers. Today, WiFi radio is present in almost all the devices, and most of the devices are equipped with WiMAX radio. Both these technologies can be utilized, if the devices are equipped with both of them, to improve the performance. To cope up with the scenario, a method for routing in a heterogeneous infrastructure based mesh network is proposed. The heterogeneous network consists of a coordinator node and a subscriber node. In this paper, we assume that the coordinator nodes are equipped with both WiMAX and WiFi radios, whereas, the subscriber nodes need not have WiMAX radio. The protocol used for routing data is based on the bee-hive algorithm, in which the entire network is divided into foraging zones/regions. We propose a technique in which the intra-foraging zone communication happens through WiFi and the nodes across the foraging zone communicate via the coordinator using WiMAX. It is observed through simulations that our technique improves the overall network performance by making use of both the radios efficiently