A Pragmatic View of MANET Performance Evaluation and Design of a Prototype MAC Level Routing Algorithm

Our goal in this research is to investigate and determine how to best support a challenging mobile wireless network based in a military operational environment. Since routing protocols used in mobile ad hoc networks (MANET) must adapt to frequent or continual changes of topology, while simultaneously limiting the impact of tracking these changes on wireless resources, we focused our initial research on improving the efficiency of route discovery. We proposed and designed a new MAC layer routing protocol that pursues reduced routing overhead, greater interaction of network protocol layers and passive neighbor/path discovery. This algorithm, called Virtual MAC Tag Switching (VMTS), evolved as we implemented a prototype in the ns-2 network simulator and conducted simulation analysis of existing protocols: DSDV, DSR and AODV. Upon analyzing the performance of existing routing protocols using pragmatic metrics not applied in any MANET literature it was found that current MANET models produce unsatisfactory performance. Subsequent analysis of transport layer protocol behaviors pinpointed the causes that undermine the performance of the existing protocols and would have thwarted VMTS as well

An Energy-conscious Transport Protocol for Multi-hop Wireless Networks

We present a transport protocol whose goal is to reduce power consumption without compromising delivery requirements of applications. To meet its goal of energy efficiency, our transport protocol (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgements and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within a recently developed ultra low-power multi-hop wireless network system, extensive simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network.Defense Advanced Research Projects Agency (NBCHC050053

Analysis of IPv6 Neighbor Discovery for Mobile and Wireless Networks

The majority of the current 3GPP and M2M networks use or will use IPv6 for accessing the internet. These IPv6 networks use Neighbor Discovery as defined in RFC 4861 to identify their neighbors on the link and see if they are active. The increase in the complexity of wireless networks and introduction of battery operated devices sets forth notable challenges to certain assumptions in the RFC 4861. The RFC 4861 is more suited for wired networks and its implementation in wireless networks makes it more inefficient. This thesis work focuses on the energy efficient implementation of RFC 4861 using the protocols mentioned in draft-chakrabarti-nordmark-6man-efficient-nd-06. The draft suggests a method of registering all the nodes in the network to their default router, so that the router takes care of all the basic neighbor discovery functionalities without disturbing the battery operated devices which are in sleepy mode. Alongside the legacy Neighbor Discovery, the optimizations proposed by the draft are implemented, on a RADVD based router and an Ubuntu host, to reduce redundant multicast signaling in mobile networks. These optimizations are theoretically analyzed to check if the draft is beneficial for the scalability and transient nature of the wireless networks.Popular Science Report With the rise of Internet of Things (IoT) and Machine to Machine communication (M2M) based networks, more and more wireless devices are communicating to each other and hence there is a need for IPv6 (Internet Protocol version 6) addressing. This new type of addressing forces us to make some design changes in the existing protocols. Wireless devices are mostly mobile, battery operated (hence a power constraint exists) and can undergo several disconnections and reconnections while moving inside the network, whereas wired devices are less prone to network instabilities and almost always connected to a power source. Because of these differences, the protocols of wired devices are not always suitable for wireless networks. Still today’s wireless devices often use protocols that were designed for wired devices and tend to be inefficient. This thesis work deals with one such protocol called Internet Control Message Protocol (ICMP), which is widely used to send control messages across the network between different nodes. Neighbor Discovery Protocol (NDP) is a part of ICMPv6 that helps a node in the network identify its Neighbors on the other side of the link. Present generation wireless devices use the protocols defined in RFC 4861 (a common reference used by major communication companies while creating products) for Neighbor discovery. But this protocol proves to be inefficient by flooding the network with unwanted multicast control messages. Hence we analyze a modified version of the existing NDP against the legacy protocol. RFC 4861 based ‘legacy NDP’ works based on multicasting. Every IPv6 host is a part of several solicited node multicast groups. All nodes with the same last 24 IPv6 address bits belong to the same solicited node multicast group. NDP is also performed based on 4 major control message packets namely, Router Solicitation (RS), Router Advertisement (RA), Neighbor Solicitation (NS) and Neighbor Advertisement (NA). RA is the packet from the router which contains all the information about the network and the router. It is flooded periodically through an all node multicast group to all IPv6 nodes. When a node wants a particular router to send some information about the network immediately without waiting for periodic RAs, it sends an RS. Neighbor Advertisement is used by a node to send information about itself to other nodes in the network. Neighbor Solicitation, as name suggests, is used by a particular node to request for information about another node. Consider the case of a network with a host and a router, and a new node enters the network. It sends out RS to the all routers multicast group, and the router responds with an RA. The new host reads the information about the network and begins address configuration. Stateless Address Auto Configuration (SLAAC) is the most suitable method of address configuration for M2M networks. Hence according to SLAAC, the new host chooses an IP address and checks if the address has already been used by some other host. This process is called as Duplicate Address Detection (DAD) and is carried out by sending out NS for that chosen IP address at the solicited node multicast group address. This means that the new host asks information about a node with that IP address, which may or may not exist at all. If a reply comes, it means that there is a node using this address. If a reply does not come, then it is free to choose the address. The response NA in case of a duplicate address, will be broadcast to all IPv6 nodes. A NS-NA pair is also used to resolve each other’s IP addresses against their MAC addresses. One of the major reasons why this method seems to be inefficient is that current wireless devices are programmed to be in sleep modes when not in use. The flow of control messages to unrelated nodes (because of multicast) will only lead to disrupted sleep. Consider a host A in the network which is in sleep mode, and has an IP address aaaa::aaaa:aaaa:a. When a new host arrives and wants to register itself with an address of aaaa::baaa:aaaa:a, it sends out NS to the multicast group of A (because A has the same last 24 bits). When a packet reaches A, it wakes up from sleep mode, reads the message and identifies that this message was not destined to it. If there was another host in the group which used the same IP address, then host A will also receive another NA, which again is not of any use. Hence this protocol proves to be inefficient. The new proposed protocol works with an efficient implementation of the NDP. It introduces a concept of registering a host with a router. And the router sends out NS and NA instead of the host. Hence each router’s NCE will be the source of information for those hosts which are registered to that router. If a node will request for details about another host, the details will either be fetched from that router’s NCE or the NS will be forwarded to that particular host instead of being multicast. The router to whom the destination host is registered will then send NAs on behalf of its host. Hence in this protocol, the router performs more work and the host less, allowing the host to stay in sleep modes without any problems. The analysis of the two protocols begins with their implementation. We decided to test the working of the two protocols at two specific case scenarios: when several hosts join the network and when the channel links are unsteady. Both protocols were implemented and compared. The implementation of the legacy NDP began with a router and a host system. We used an Ubuntu PC (which generally works as a host) as a router. RADVD is an open source software that helps to generate RAs and Wireshark the software used to analyze packets in the network. To make a host work as a router, the following changes were made: 1. Turn on forwarding in the PC 2. Configure the router with a static IP address 3. Configure the interfaces and add corresponding routing information 4. Install RADVD and include all the network parameters in the config file 5. Turn on Wireshark 6. Turn on RADVD Once all these steps are done in order, the RADVD sends out periodic RAs that can be viewed on the Wireshark. When the host is connected to the network, the entire process of address configuration and DAD can be identified. When pinged, the address resolution process can also be verified. To implement the new protocol, we downloaded the source code of the open source RADVD from GitHub and change the packet formats of the RA, NS and NA. When the router works as a NEAR (Neighbor Discovery Efficiency Aware Router), the host has to understand that it should not use legacy NDP anymore and must act as an Efficiency Aware host (EAH). This information comes with the RA in the form of a flag. When this is done, the host sends an NS in the form of registration request. The details of the host go in the Address Resolution Option (ARO) of the NS. The router responds with an NA which is the acknowledgement for the registration request. Now the host can enter into sleep mode and the router will send control packets to it only when required. When the registration expires, a new registration process has to be setup or a de-registration process has to happen by setting the ARO option in the NS to 0. To implement the changes in the host side, we downloaded the source code for Linux from GitHub and led the decoder side. The process ends by making all the necessary code changes, recompiling a new Kernel and installing the new version of Linux on the hosts. However, the complete reprogramming of the kernel is not handled in this thesis work. But the entire plan for the programming and the rest of the implementation is included in this report. The theoretical analysis of the protocols is also included in this report. This report concludes with a general analysis of the whole protocol. The whole protocol which was completely decentralized has a certain degree of centralized control now. As with all systems, centralization introduces better control but there is always a problem of device failure which can completely collapse the system. The protocol also provides solutions for router failure and recovery and hence the system is a good compromise between centralized and decentralized systems. If properly implemented, there will be an increase in the network efficiency (inversely proportional to the number of control packets for every single data point). This thesis ends with the theoretical analysis. A proper implementation followed by a practical analysis would be a natural future amendment to the projec

A framework for the dynamic management of Peer-to-Peer overlays

Peer-to-Peer (P2P) applications have been associated with inefficient operation, interference with other network services and large operational costs for network providers. This thesis presents a framework which can help ISPs address these issues by means of intelligent management of peer behaviour. The proposed approach involves limited control of P2P overlays without interfering with the fundamental characteristics of peer autonomy and decentralised operation. At the core of the management framework lays the Active Virtual Peer (AVP). Essentially intelligent peers operated by the network providers, the AVPs interact with the overlay from within, minimising redundant or inefficient traffic, enhancing overlay stability and facilitating the efficient and balanced use of available peer and network resources. They offer an “insider‟s” view of the overlay and permit the management of P2P functions in a compatible and non-intrusive manner. AVPs can support multiple P2P protocols and coordinate to perform functions collectively. To account for the multi-faceted nature of P2P applications and allow the incorporation of modern techniques and protocols as they appear, the framework is based on a modular architecture. Core modules for overlay control and transit traffic minimisation are presented. Towards the latter, a number of suitable P2P content caching strategies are proposed. Using a purpose-built P2P network simulator and small-scale experiments, it is demonstrated that the introduction of AVPs inside the network can significantly reduce inter-AS traffic, minimise costly multi-hop flows, increase overlay stability and load-balancing and offer improved peer transfer performance

ATLAS pixel detector electronics and sensors

The silicon pixel tracking system for the ATLAS experiment at the Large Hadron Collider is described and the performance requirements are summarized. Detailed descriptions of the pixel detector electronics and the silicon sensors are given. The design, fabrication, assembly and performance of the pixel detector modules are presented. Data obtained from test beams as well as studies using cosmic rays are also discussed

An Energy Efficient Dynamic Source Routing for MANET

Ad hoc networking allows portable mobile devices to establish communication path without having any central infrastructure. Since there is no central infrastructure and the mobile devices are moving randomly, gives rise to various kinds of problems, such as routing and security. In this thesis the problem of routing is considered. Routing is one of the key issues in MANETs because of highly dynamic and distributed nature of nodes. Especially energy efficient routing is most important because all the nodes are battery powered. Failure of one node may affect the entire network. If a node runs out of energy the probability of network partitioning will be increased. Since every mobile node has limited power supply, energy depletion is become one of the main threats to the lifetime of the ad hoc network. So routing in MANET should be in such a way that it will use the remaining battery power in an efficient way to increase the life time of the network. In this thesis, we have proposed an energy efficient dynamic source routing protocol (EEDSR) which will efficiently utilize the battery power of the mobile nodes in such a way that the network will get more lifetime. Transmission power control approach is used to adjust the node to node communication power and load balancing approach is used to avoid over utilized nodes. Transmission power control is done by calculating new transmission power between every pair of nodes on that route which will be the minimum power required for successful communication. Load balancing is done by selecting a route which contains energy rich nodes. Simulation studies revealed that the proposed scheme is more efficient than the existing one

Energy-Efficient Querying of Wireless Sensor Networks

Due to the distributed nature of information collection in wireless sensor networks and the inherent limitations of the component devices, the ability to store, locate, and retrieve data and services with minimum energy expenditure is a critical network function. Additionally, effective search protocols must scale efficiently and consume a minimum of network energy and memory reserves. A novel search protocol, the Trajectory-based Selective Broadcast Query protocol, is proposed. An analytical model of the protocol is derived, and an optimization model is formulated. Based on the results of analysis and simulation, the protocol is shown to reduce the expected total network energy expenditure by 45.5 percent to 75 percent compared to current methods. This research also derives an enhanced analytical node model of random walk search protocols for networks with limited-lifetime resources and time-constrained queries. An optimization program is developed to minimize the expected total energy expenditure while simultaneously ensuring the proportion of failed queries does not exceed a specified threshold. Finally, the ability of the analytical node model to predict the performance of random walk search protocols in large-population networks is established through extensive simulation experiments. It is shown that the model provides a reliable estimate of optimum search algorithm parameters

Optically Powered Highly Energy-efficient Sensor Networks

In optically powered networks, both, communication signals and power for remotely located sensor nodes, are transmitted over an optical fiber. Key features of optically powered networks are node operation without local power supplies or batteries as well as operation with negligible susceptibility to electro-magnetic interference and to lightning. In this book, different kinds of optically powered devices and networks are investigated, and selected applications are demonstrated

Design of Optical Interconnect Transceiver Circuits and Network-on-chip Architectures for Inter- and Intra-chip Communication

The rapid expansion in data communication due to the increased multimedia applications and cloud computing services necessitates improvements in optical transceiver circuitry power efficiency as these systems scale well past 10 Gb/s. In order to meet these requirements, a 26 GHz transimpedance amplifier (TIA) is presented in a 0.25-µm SiGe BiCMOS technology. It employs a transformer-based regulated cascode (RGC) input stage which provides passive negative-feedback gain that enhances the effective transconductance of the TIA’s input common-base transistor; reducing the input resistance and pro- viding considerable bandwidth extension without significant noise degradation or power consumption. The TIA achieves a 53 dBΩ single-ended transimpedance gain with a 26√ GHz bandwidth and 21.3 pA/H z average input-referred noise current spectral density. Total chip power including output buffering is 28.2 mW from a 2.5 V supply, with the core TIA consuming 8.2 mW, and the chip area including pads is 960 µm × 780 µm. With the advance of photonic devices, optical interconnects becomes a promising technology to replace the conventional electrical channels for the high-bandwidth and power efficient inter/intra-chip interconnect. Second, a silicon photonic transceiver is presented for a silicon ring resonator-based optical interconnect architecture in a 1V standard 65nm CMOS technology. The transmitter circuits incorporate high-swing drivers with non-linear pre-emphasis and automatic bias-based tuning for resonance wavelength stabilization. An optical forwarded-clock adaptive inverter-based transimpedance amplifier (TIA) receiver trades-off power for varying link budgets by employing an on-die eye monitor and scaling the TIA supply for the required sensitivity. At 5 GB/s operation, the ring modulator un- der 4Vpp driver achieves 12.7dB extinction ratio with 4.04mW power consumption, while a 0.28nm tuning range is obtained at 6.8µW/GHz efficiency with the bias-based tuning scheme implemented with the 2Vpp transmitter. When tested with a wire-bonded 150f- F p-i-n photodetector, the receiver achieves -12.7dBm sensitivity at a BER=10−15 and consumes 2.2mW at 8 GB/s. Third, a novel Nano-Photonic Network-on-Chip (NoC) architecture, called LumiNoC, is proposed for high performance and power-efficient interconnects for the chip-multi- processors (CMPs). A 64-node LumiNoC under synthetic traffic enjoys 50% less latency at low loads versus other reported photonic NoCs, and ∼25% less latency versus the electrical 2D mesh NoCs on realistic workloads. Under the same ideal throughput, LumiNoC achieves laser power reduction of 78%, and overall power reduction of 44% versus competing designs