Dynamic Programming Optimization of Multi-rate Multicast Video-Streaming Services

In large scale IP Television (IPTV) and Mobile TV distributions, the video signal is typically encoded and transmitted using several quality streams, over IP Multicast channels, to several groups of receivers, which are classified in terms of their reception rate. As the number of video streams is usually constrained by both the number of TV channels and the maximum capacity of the content distribution network, it is necessary to find the selection of video stream transmission rates that maximizes the overall user satisfaction. In order to efficiently solve this problem, this paper proposes the Dynamic Programming Multi-rate Optimization (DPMO) algorithm. The latter was comparatively evaluated considering several user distributions, featuring different access rate patterns. The experimental results reveal that DPMO is significantly more efficient than exhaustive search, while presenting slightly higher execution times than the non-optimal Multi-rate Step Search (MSS) algorithm

CC-CAT: CONGESTION CONTROL FOR CACHE-AWARE TRANSPORT PROTOCOL IN WIRELESS SENSOR NETWORKS

Congestion control mechanism is vital component of an effective and efficient transport protocol both for wired and wireless networks. It is one of the primary functions of the transport layer together with a reliable data delivery. Wireless sensor networks (WSNs) are distinctive group of wireless ad hoc networks with unique characteristics and imperative restraints. It was proven that caching in the intermediate nodes reduces end-to-end retransmission that makes it a better option for an energy efficient transport protocol. However, none of the congestion control protocols developed for wireless sensor networks have considered the use of intermediate caching. Thus, is it not yet known which congestion control technique is appropriate for caching-aware data transport. This paper presents a new congestion control mechanism called Congestion Control for Cache-Aware Transport (CC-CAT). It was implemented in a cache-based transport protocol such as in an enhanced Distributed Transport Sensor Networks (DTSN+). The main idea of the congestion control algorithm is to adjust the transmission window AW of the sender based on the cache size in the intermediate nodes and congestion state. The movement of the window is based on two instances: the optimum energy efficiency and optimum goodput, which are both function of cache size. The simulation results indicate that the Congestion Control for Caching-Aware Transport was able to improve the DTSN+ protocol in terms of end-to-end packet delay and throughput on the average. The CC-CAT achieved remarkable packet end-to-end delay gain of 2.31%, 19.43% and 18.90% at condition where high congestions and packet error rate are being manifested in the network at cache sizes of 10, 20 and 30 packets, respectively. Although the CC-CAT obtained slightly notable throughput gain, the mechanism delivered better response in avoiding further occurrence of congestion as seen in the behavior of the transmission window AW shown in Figure 1. With this novel approach, CC-CAT is more compatible with WSN applications where strictly minimal end-to-end packet delay is required but may compromise the amount of data to be transmitted. Such applications can be in Wireless Multimedia Sensor Networks (WMSN) that implements interactive voice and video

PERFORMANCE ANALYSIS OF RPL UNDERAN AMBIENT ENERGY HARVESTING WIRELESS SENSOR NETWORK

Wireless sensor networks (WSNs) with millions or billions of nodes deployed in areas such as forests and electricity grids cannot use battery-operated sensor nodes since it would be highly impractical to replace the batteries of a large number of sensors while maintaining continuous operation. Instead, we must use sensors that can harvest ambient energy from the environment. These nodes would be cheap, have smaller energy capacity, and must recharge often to ensure that the size of the sensors will be small to be deployable in large quantities. To make that possible, we can make use of coin-sized supercapacitors, such as commercial surface mount supercapacitors sold by [1]. The IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) is currently the de facto standard routing protocol for low power and lossy WSNs as set by the Internet Engineering Task Force (IETF) [2]. Its performance has been comprehensively evaluated in multiple works [3][4] with good results in standard battery-operated WSNs. However, we need to determine how the standard RPL protocol will perform in a network of low energy capacity sensors that frequently recharge. Our results show that RPL performs poorly when run under an energy harvesting sensor network. Figure 1 shows that the number of lost packets of the harvester network is linearly increasing from the hundreds to the thousands, while the battery network has negligible loss. This results in the harvester network having a 40-45% lower throughput than the battery network. This poor performance is due to critical sensor nodes running out of energy all at the same time, thus creating a time period when the entire network is down, as seen in Figure 2. We can possibly improve the network performance by adding energy awareness with a smarter selection and switching of critical nodes via the use of cross-layer optimization techniques to incorporate energy measurement and packet caching. We propose to modify RPL's objective function to include a mechanism for parent switching based on the remaining energy of the sensor nodes

AN ANDROID-BASED, RASPBERRY PI WIRELESS MESH NETWORK IMPLEMENTATION USING BATMAN-ADV PROTOCOL FOR FIRST-RESPONSE COMMUNICATIONS

The Philippines' geographical location makes it prone to natural calamities, especially typhoons and earthquakes. In event of these disasters, communication is vital in performing rescues and saving lives. It is desired that firstresponse communications are fast and reliable to be able to perform those tasks. However, the Philippines is greatly lacking in this aspect. The country still relies on telecommunication infrastructures, which perform worse during disaster scenarios. Telecommunication infrastructures are unsuitable for first-response purposes because they are usually centralized; when the connection to the main node is down (usually due to snapped wires), the remaining nodes are rendered useless. Furthermore, when neighboring nodes are down, the remaining node is forced to cater to all the clients connected to it, which could lead to an overloaded and unreliable network. Wireless mesh networks have a potential to solve this problem; they are decentralized and are capable of rerouting and adjusting themselves to fit the situation. In this study, we devised an alternative low-power, reliable, cheap, and decentralized wireless mesh network. We used messaging with both direct and chatroom methods as our communication platform, and added message caching in order to add to reliability. To handle the messaging and caching, we created an Android application to accompany the network. The scope of the study was limited to four nodes and two Android phone clients. To create the network, we used four Raspberry Pi nodes connected via ad-hoc connection, with one Raspberry Pi node connected to the internet. [1][2] The network utilized the Better Approach To Mobile Ad-Hoc Networking (BATMAN-adv) [3] protocol to handle the routing of the nodes and their messages. Furthermore, the network nodes acted as Message Queuing Telemetry Transport [4] brokers to handle the tagging the messages and bridging to the other nodes' brokers. Using the MQTT protocol, chat communication was tested and implemented bidirectionally. The Android application was responsible for providing the interface where the clients will interact as well as the caching of the messages. We tested the network to be able to message other clients within the local area network first. Afterwards, we checked if the messages were forwarded to the node with internet and if they arrived at the internet broker. Using this project, we have proven that a low-powered, reliable, and cheap wireless mesh network using Raspberry Pis can be made. The network was able to perform the sending and caching messages successfully. The messages were successfully cached such that each Raspberry Pi can distribute the messages. We accomplished this by utilizing the topic hierarchy feature of the MQTT protocol to devise a tagging system for the messages. Furthermore, the decentralization of the nodes made the network reliable; broken nodes were ignored and the messages were rerouted to be able to reach their destination successfully. We were able to create an altemative to infrastructure networks whenever disasters occur. We also addressed issues of reliability, overloading, and power consumption. The wireless mesh network formed was able to perform well when nodes were added and removed. Communication can easily be done using the Android application where messages can be sent and received; caching was implemented so that messages can be seen by clients whenever they are available. For future studies, we recomm end that the network be deploy ed In an octual community to t estl f it can handl e th e load. We also suggest creatin g an lOS versiO n to lncrease reliability and usability. Finally, we recomm end that a tagging automation system be developed so that addition " nodes' messages can be tagged automatically