WiLiTV: A Low-Cost Wireless Framework for Live TV Services

With the evolution of HDTV and Ultra HDTV, the bandwidth requirement for IP-based TV content is rapidly increasing. Consumers demand uninterrupted service with a high Quality of Experience (QoE). Service providers are constantly trying to differentiate themselves by innovating new ways of distributing content more efficiently with lower cost and higher penetration. In this work, we propose a cost-efficient wireless framework (WiLiTV) for delivering live TV services, consisting of a mix of wireless access technologies (e.g. Satellite, WiFi and LTE overlay links). In the proposed architecture, live TV content is injected into the network at a few residential locations using satellite dishes. The content is then further distributed to other homes using a house-to-house WiFi network or via an overlay LTE network. Our problem is to construct an optimal TV distribution network with the minimum number of satellite injection points, while preserving the highest QoE, for different neighborhood densities. We evaluate the framework using realistic time-varying demand patterns and a diverse set of home location data. Our study demonstrates that the architecture requires 75 - 90% fewer satellite injection points, compared to traditional architectures. Furthermore, we show that most cost savings can be obtained using simple and practical relay routing solutions

MAC Centered Cooperation - Synergistic Design of Network Coding, Multi-Packet Reception, and Improved Fairness to Increase Network Throughput

We design a cross-layer approach to aid in develop- ing a cooperative solution using multi-packet reception (MPR), network coding (NC), and medium access (MAC). We construct a model for the behavior of the IEEE 802.11 MAC protocol and apply it to key small canonical topology components and their larger counterparts. The results obtained from this model match the available experimental results with fidelity. Using this model, we show that fairness allocation by the IEEE 802.11 MAC can significantly impede performance; hence, we devise a new MAC that not only substantially improves throughput, but provides fairness to flows of information rather than to nodes. We show that cooperation between NC, MPR, and our new MAC achieves super-additive gains of up to 6.3 times that of routing with the standard IEEE 802.11 MAC. Furthermore, we extend the model to analyze our MAC's asymptotic and throughput behaviors as the number of nodes increases or the MPR capability is limited to only a single node. Finally, we show that although network performance is reduced under substantial asymmetry or limited implementation of MPR to a central node, there are some important practical cases, even under these conditions, where MPR, NC, and their combination provide significant gains

Geographic location and geographic prediction performance benefits for infrastructureless wireless networks

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 173-176).The field of infrastructureless wireless networks (IWNs) is a broad and varied research area with a history of different assumption sets and methods of analysis. Much of the focus in the area of IWNs has been on connectivity and throughput/energy/delay (T/E/D) tradeoffs, which are important and valuable metrics. When specific IWN routing protocols are developed, they are often difficult to characterize analytically. In this thesis we review some of the important results in IWNs, in the process providing a comparison of wideband (power-limited) versus narrowband (interference-limited) networks. We show that the use of geographic location and geographic prediction (GL/GP) can dramatically increase the performance of IWNs. We compare past results in the context of GL/GP and develop new results in this area. We also develop the idea of throughput burden and scaling for the distribution of topology and routing information in IWNs and we hope that this work provides a context in which further research can be performed. We primarily focus our work on wideband networks while also reviewing some narrowband results. In particular, we focus on wideband networks with non-zero processing energy at the nodes, which combines with distance-dependent transmission energy as the other main source of power consumption in the network. Often the research in this area does not take into account processing energy, but there is previous work which shows that processing energy is an important consideration. The consideration of processing energy is the determining factor in whether a whisper to the nearest neighbor (WtNN) or characteristic hop distance routing scheme is optimal. Whisper to the nearest neighbor routing involves taking a large number of short hops, while characteristic hop distance routing is the scheme by which the optimal hop distance is based on the distance dependent transmission energy and the processing energy, as well as the attenuation exponent. For a one-dimensional network, we use a uniform all-to-all traffic model to determine the total hop count and achievable throughput for three routing types: WtNN without GL/GP, WtNN with GL/GP, and characteristic hop distance with GL/GP. We assume a fixed rate system and a random and uniform node distribution. The uniform all-to-all traffic model is the model where every node communicates with every other node at a specified rate. The achievable throughput is the achievable rate at which each source can send data to each of its destinations. The results we develop show that the performance difference between WtNN with and without GL/GP is minimal for one-dimensional networks. We show the reduction in hop count of characteristic hop distance routing compared to WtNN routing is significant. Further, the achievable throughput of characteristic hop distance routing is significantly better than that of WtNN networks. We present a method to determine the link rate scaling necessary for link state distribution to maintain topology and routing information in mobile IWNs. We developed several results, with the main result of rate scaling for two-dimensional networks where every node is mobile. We use a random chord mobility model to represent independent node movement. Our results show that in the absence of GL/GP, there is a significant network burden for maintaining topology and routing information at the network nodes. We also derive real world scaling results using the general analytic results and these results show the poor scaling of networks without GL/GP. For networks of 100 to 1000 nodes, the rate scaling for maintaining topology in mobile wireless networks is on the order of hundreds of megabits to gigabits per second. It is infeasible to use such significant amounts of data rate for the sole purpose of maintaining topology and routing information, and thus some other method of maintaining this information will need to be utilized. Given the growing number of devices connected to the Internet, in the future it is likely that IWNs will become more prevalent in society. Despite the significant amount of research to date, there is still much work to be done to determine the attributes of a realistic and scalable system. In order to ensure the scalability of future systems and decrease the amount of throughput necessary for network maintenance, it will be necessary for such systems to use geographic location and geographic prediction information.by Shane A. Fink.S.M

Study on QoS support in 802.11e-based multi-hop vehicular wireless ad hoc networks

Multimedia communications over vehicular ad hoc networks (VANET) will play an important role in the future intelligent transport system (ITS). QoS support for VANET therefore becomes an essential problem. In this paper, we first study the QoS performance in multi-hop VANET by using the standard IEEE 802.11e EDCA MAC and our proposed triple-constraint QoS routing protocol, Delay-Reliability-Hop (DeReHQ). In particular, we evaluate the DeReHQ protocol together with EDCA in highway and urban areas. Simulation results show that end-to-end delay performance can sometimes be achieved when both 802.11e EDCA and DeReHQ extended AODV are used. However, further studies on cross-layer optimization for QoS support in multi-hop environment are required

Self-stabilizing cluster routing in Manet using link-cluster architecture

We design a self-stabilizing cluster routing algorithm based on the link-cluster architecture of wireless ad hoc networks. The network is divided into clusters. Each cluster has a single special node, called a clusterhead that contains the routing information about inter and intra-cluster communication. A cluster is comprised of all nodes that choose the corresponding clusterhead as their leader. The algorithm consists of two main tasks. First, the set of special nodes (clusterheads) is elected such that it models the link-cluster architecture: any node belongs to a single cluster, it is within two hops of the clusterhead, it knows the direct neighbor on the shortest path towards the clusterhead, and there exist no two adjacent clusterheads. Second, the routing tables are maintained by the clusterheads to store information about nodes both within and outside the cluster. There are two advantages of maintaining routing tables only in the clusterheads. First, as no two neighboring nodes are clusterheads (as per the link-cluster architecture), there is no need to check the consistency of the routing tables. Second, since all other nodes have significantly less work (they only forward messages), they use much less power than the clusterheads. Therefore, if a clusterhead runs out of power, a neighboring node (that is not a clusterhead) can accept the role of a clusterhead. (Abstract shortened by UMI.)