WiEnum: Node enumeration in wireless networks

This paper addresses the Quality of Service (QoS) degradation problem of wireless relay node failures in multihop Worldwide interoperable Microwave Access (WiMAX) and Long Term Evolution (LTE) networks. In general, node protection in a communication network increases the reliability of the traffic flow from source to destination. For wireless networks, implementing the traditional 1+1 protection scheme increases the capital cost, as resources cannot be fully utilized. On the other hand, the design and implementation of the 1:N protection scheme in wireless networks for greater value of N (> 2) is very difficult, due to wireless network coverage and the physical layer design. To overcome the above drawbacks, a technique based on network coding is proposed for node protection in multihop wireless networks. In multihop wireless networks, few research efforts are concentrated on node protection schemes using network coding. Moreover, to best of our knowledge, no reports have been published on measuring the QoS performance for node protection in 4G wireless networks using network coding. In this paper, we first describe the node protection scheme using XOR network coding for multihop 4G wireless networks. Then, we measure the QoS performance, such as packet delivery ratio (PDR), latency and jitter, for different scenarios. The scenarios include a failure of a single relay node and failures of two relay nodes with and without our protection scheme and user's mobility. The simulation results show that the QoS performance with protection against a single relay node failure and failures of two relay nodes are very close to that of no failure scenario, while the network reliability increases due to the protection mechanism. Also, we report a decoding problem in multihop wireless networks using XOR network coding.

Multi-hop wireless networks have attracted much attention because of their flexibility and deploy ability. However, we have previously shown that communication stability in multi-hop wireless networks is degraded by a congestion propagation problem that occurs among neighbor APs. To prevent congestion propagation and enable stable communication, we proposed QMTR (Queue Management with Transmission Record) as a buffer management scheme. We have shown that this scheme allows sufficiently stable communication in a steady state. In this study, we consider a more realistic environment that includes transient states. Through simulation evaluation, we show that the scheme enables sufficiently stable communication even under a transient state in multi-hop wireless networks.

AMI (Advanced Metering Infrastructure) is an advanced form of power metering system for smart grid. The AMI communicates information which is required for efficient power management with server. This information needs to protect because this information can be exploited. AMI can use public key certificate to protect this information. However, AMI can be physical attacked because the AMI is located outdoor as existing power metering system. AMI needs an additional security techniques against physical attacks. In order to solve these security problems, we propose the hardware (HW) public key certificate chip using unique identifier (ID) as an alternative.

The key factor of influencing the network capacity performance is the effect of interference power of receiving nodes, which is obtained from the other transmitting nodes in multihop wireless networks (MWNs) that are simultaneously using the same channel. Minimizing total interference power can improve overall network capacity and reduce total energy consumption. In this paper, we propose a consensus transmit power control (CTPC) algorithm to maximize end-to-end throughput in MWNs. The CTPC algorithm tunes the nodes' transmit powers to maximize the average end-to-end throughput with a consensus coefficient. Simulation results reveal that the CTPC algorithm enables all the traffic flows to accomplish the maximum average end-to-end throughput. At the same time, the total interference power and the total power consumption are decreasing. Only in the dense MWNs, under usual threshold of received signal strength indicator (RSSI) setting, the CTPC algorithm cannot achieve good performance. In addition, an advanced wmediumd emulator over the StarBED testbed is used to further verify the performance evaluation of CTPC algorithm.

Gossiping is to broadcast the message of every node to all the other nodes in multi-hop wireless networks (MWNs). This operation plays an important role and is widely used in MWNs. Interference-aware gossiping scheduling (IAGS) aims to provide an interference-free scheduling for gossiping with the minimum latency. Previous work on IAGS mostly assumes that nodes are always active, and thus is not suitable for duty-cycled scenarios. In this paper, we investigate the IAGS problem in uncoordinated duty-cycled multi-hop wireless networks (IAGS-UDC problem) under protocol interference model and unbounded-size message model. We prove that the IAGS-UDC problem is NP-hard. We propose a novel approximation algorithm called MILD for this problem. The MILD algorithm achieves an approximation ratio of 3β 2(Δ + 6)|T|, where β is \(\lceil \frac{2}{3}(\alpha+2)\rceil\), α denotes the ratio of the interference radius to the transmission radius, Δ denotes the maximum node degree of the network, and |T| denotes the number of time-slots in a scheduling period. Moreover, the number of transmissions scheduled by the MILD algorithm is at most 3 times as large as the minimum number of transmissions.KeywordsGossiping schedulinginterferenceduty cyclemulti-hop wireless networks

Nodes in a multi-hop wireless network rely on each other to maintain network connectivity. A primary design objective of these networks is to eliminate or minimize the unavailability of network at some point. However, the movement of nodes creates service disruption and delay as path failure detection and re-establishment consume considerable amount of time. Existing solutions for link classification and prediction operate on discrete values resulting in performance degradation. This problem can best be modelled using fuzzy logic. This work presents a new fuzzy logic based link status classification mechanism for the use with multipath routing protocols in multi-hop wireless networks. The new Enhanced Adhoc On-demand Multipath Distance Vector (eAOMDV) uses fuzzy logic to classify the link status as active, about-to-break or broken. On the basis of fuzzy input parameters RSSI, velocity, distance and bit error rate, the fuzzy based classification mechanism predicts in advance that a particular link, on the active path between the sender and receiver, is about-to-break and helps the reactive multipath routing protocol to start the rerouting operation, thus minimizing the service disruption time, route discovery frequency, end-to-end delay and the packet loss.

Cooperative communication has emerged as a promising technique to improve transmission reliability and spectral efficiency by utilizing virtual antenna arrays formed by multiple nodes in wireless networks. In this paper, we study distributed interference-aware random access strategies based on cooperative link selection scheduling for multi-hop wireless networks. In order to fully exploit the broadcast feature of wireless channels, improve spatial reuse, and achieve diversity gains, the cooperative random access is formulated as a network utility optimization problem with probabilistic model and interference avoidance. In the multi-hop wireless networks, the nodes near the destination node in the current hop that can decode the data packets from the source node are able to serve as candidate relays to take part in the cooperative transmission in the next hop. Simulation results show that our proposed spectrum access strategy significantly improves the system average throughput and spectrum efficiency compared with the existing solutions.

Further to the detection by the German authorities of the unauthorised flax CDC Triffid event FP967 (Unique Identifier CDC-FLOO1-2) in materials imported from Canada, a notification was sent through the Rapid Alert System for Food and Feed (RASFF) in September 2009. On 21 August 2009, the Community Reference Laboratory for Genetically Modified Food and Feed received from the German authorities a construct-specific method for the detection of flax CDC Triffid event FP967, developed by Genetic ID, Augsburg (Germany). The method developer declared this method as specific for event FP967 as it targets a transition sequence spanning the nopaline synthase (nos) terminator gene and the spectinomycin/streptomycin resistance gene, construction being found only in the flax FP967 event. On 11 September 2009, the CRL-GMFF received from the German authorities the FP967 positive control in the form of DNA extracted from seeds. Seeds were provided to the German authorities by the University of California, Riverside, USA. The CRL-GMFF carried out experiments on the control sample received in order to verify the specificity and the Limit of Detection (LOD) of the construct-specific method. The CRL-GMFF observed that the NOST-Spec (nos terminator – spectinomycin resistance gene) construct- specific method generates a PCR amplification product of 105 bp, whose sequence is homologous to a transition sequence spanning the nopaline synthase (nos) terminator gene and the dihydrofolate reductase gene. The experimental testing of the specificity indicates that the NOST-Spec construct-specific assay does not detect genetically modified events under the conditions reported. The limit of detection (LOD) established is between 1 and 5 haploid genome copies of FP967. How to obtain EU publications Our priced publications are available from EU Bookshop (http://bookshop.europa.eu), where you can place an order with the sales agent of your choice. The Publications Office has a worldwide network of sales agents. You can obtain their contact details by sending a fax to (352) 29 29-42758. The mission of the JRC is to provide customer-driven scientific and technical support for the conception, development, implementation and monitoring of EU policies. As a service of the European Commission, the JRC functions as a reference centre of science and technology for the Union. Close to the policy-making process, it serves the common interest of the Member States, while being independent of special interests, whether private or national. LB -N A -2454-EN -C

The JRC as Community Reference Laboratory for GM Food and Feed (CRL-GMFF), established by Regulation (EC) No 1829/2003, has carried out an in-house verification study to assess the performance of two quantitative event-specific methods on the maize event MON 88017 x MON 810 (unique identifier MON-88Ø17-3 x MON-ØØ810-6) which combines the MON 88017 and MON 810 transformation events. The two methods have been previously validated individually on single-trait event, to detect and quantify each event in maize samples; a validation report for each method is available at http://gmo-crl.jrc.ec.europa.eu/statusofdoss.htm. This study was conducted according to internationally accepted guidelines (1, 2). \nIn accordance to Regulation (EC) No 1829/2003 of 22 September 2003 on genetically modified food and feed and to Regulation (EC) No 641/2004 of 6 April 2004 on detailed rules for the implementation of Regulation (EC) No 1829/2003, Monsanto Europe S.A. provided the detection methods and the control samples: whole seeds of MON 88017 x MON 810 maize (TPX151-DT, GLP-0409-15526-S) and whole conventional maize seeds of EXP258 (GLP-0409-15528-S). The JRC prepared the in-house verification samples (calibration samples and blind samples at different GM percentages). \nThe results of the in-house verification study were evaluated with reference to ENGL method performance requirements (http://gmo-crl.jrc.ec.europa.eu/guidancedocs.htm) and to the validation results on the individual parental events (http://gmo-crl.jrc.ec.europa.eu/statusofdoss.htm).\nThe results of this CRL-GMFF in-house verification studies are made publicly available at http://gmo-crl.jrc.ec.europa.eu/.

Previous chapter Next chapter Full AccessProceedings Proceedings of the 2013 Annual ACM-SIAM Symposium on Discrete Algorithms (SODA)Near Optimal Leader Election in Multi-Hop Radio NetworksMohsen Ghaffari and Bernhard HaeuplerMohsen GhaffariMITMITSearch for more papers by this author and Bernhard HaeuplerMITMITSearch for more papers by this authorpp.748 - 766Chapter DOI:https://doi.org/10.1137/1.9781611973105.54PDFBibTexSections ToolsAdd to favoritesExport CitationTrack CitationsEmail SectionsAboutAbstract We design leader election protocols for multi-hop radio networks that elect a leader in almost the same time TBC that it takes for broadcasting one message (one ID). For the setting without collision detection our algorithm runs whp. in rounds on any n-node network with diameter D. Since is a lower bound, our upper bound is optimal up to a factor of at most log log n and the extra log n factor on the additive term. Our algorithm is furthermore the first O(n) time algorithm for this setting. Our algorithm improves over a 23 year old simulation approach of Bar-Yehuda, Goldreich and Itai with a O(TBC log n) running time: In 1987 they designed a fast broadcast protocol and subsequently in 1989 they showed how it can be used to simulate one round of a single-hop network that has collision detection in TBC time. The prime application of this simulation was to simulate Willards single-hop leader election protocol, which elects a leader in O(log n) rounds whp. and O(log log n) rounds in expectation. While it was subsequently shown that Willards bounds are tight, it was unclear whether the simulation approach is optimal. Our results break this barrier and essentially remove the logarithmic slowdown over the broadcast time TBC. This is achieved by going away from the simulation approach. We also give an leader election algorithm for the setting with collision detection (even with single-bit messages). This is optimal up to log log n factors and improves over a deterministic algorithm that requires Θ(n) rounds independently of D. Our almost optimal leader election protocols are especially important because countless communication protocols in radio networks use leader election as a crucial first step to solve various, seemingly unrelated, communication primitives such as gathering, multiple unicasts or multiple broadcasts. Even though leader election seems easier than these tasks, its best-known O(TBC log n) running time had become a bottleneck, preventing optimal algorithms. Breaking the simulation barrier for leader election in this paper has subsequently led to the development of near optimal protocols for these communication primitives. Previous chapter Next chapter RelatedDetails Published:2013ISBN:978-1-61197-251-1eISBN:978-1-61197-310-5 https://doi.org/10.1137/1.9781611973105Book Series Name:ProceedingsBook Code:PR143Book Pages:xix + 1915

This paper concerns a study of the process of localizing the nodes of a multi-hop wireless networks, i.e., of having the node computing their coordinates with 'respect to a suitable reference system. We consider networks where the nodes perform measurements of distance and angle of arrival from nodes within their transmission radius. We describe a simple localization protocol, termed range-based centroid (RBC), that starting from a single node (the beacon) with given coordinates localizes all the network nodes with reasonable accuracy. We then propose a new localization protocol that achieves greater accuracy by containing the propagation of the localization error as the process progresses away from the beacon. We quantify the improvements of the proposed protocol, termed MEC/sup 2/ (for minimum enclosing circle containment) by simulations. In the considered scenarios, MEC/sup 2/ keeps the localization error within 21% of the nodes' transmission radius, with 20-30% improvements over RBC.

Wireless multi-hop local area networks use in general scheduling schemes that assume the network capacity to be known. Indeed in most of the throughput-optimal algorithms the sources are assumed to send at a rate within the capacity region. However, measurements made on real deployments show that the network capacity is usually difficult to characterize and also time-varying. It is therefore important to understand how the network behaves when the sources attempt to transmit at a rate above capacity. Toward this goal, we show 3-phase regime in the effect of the input rate λ on the end-to-end throughput μ of a multi-hop network. First, when λ is smaller than a threshold λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , μ is an increasing function of λ. Second, when λ is larger than another threshold λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> > λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , μ is independent of λ. Third, when λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> <; λ <; λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , μ decreases with λ. To understand this phenomenon, we capture the relation between the end-to-end throughput and the queue stability with a mathematical model that allows us to explain and derive the exact values of the transition points λi. We then validate experimentally our simulation results with measurements on a testbed composed of five wireless routers.

In this study we investigate the interaction between TCP and MAC layer in a wireless multi-hop network. This type of network has traditionally found applications in the military (automated battlefield), law enforcement (search and rescue) and disaster recovery (flood, earthquake), where there is no fixed wired infrastructure. Wireless "ad-hoc" multi-hop networks have previously been proposed for nomadic computing applications. Key requirements in all the above applications are reliable data transfer and congestion control, features that are generally supported by TCP. Unfortunately, TCP performs on wireless in a much less predictable way than on wired protocols. Using simulation, we provide new insight into two critical problems of TCP over wireless multi-hop. The first is the conflict between data packets and ACKs, which causes TCP performance to degrade for window sizes greater than 1 packet. The second is the interaction between MAC and TCP layer backoff timers which causes severe unfairness and capture conditions. In the paper, we identify these problems in several representative simulation runs on various topologies and traffic patterns and indicate possible remedies to improve TCP efficiency over a wireless multi-hop network.

Reducing number of forwarding nodes is the primary objective when broadcasting the same message to all the nodes in a multi-hop wireless network. Without proper measures broadcasting may result in many redundant (re)transmissions. The prominent Dominant Pruning (DP) algorithm reduces re-transmissions to some extent using only 2-hop neighbor information of each node. Further reduction is possible if a node is equipped with three or more hops' neighborhood information. In this paper, we propose a new broadcasting technique dubbed as "ExDP" which uses extended 3-hop neighborhood information of each node in order to reduce redundancy. Expanding neighborhood knowledge up to three hops enables a forwarding node to detect which other nodes in the previous node's forwarding list are going to cover some of its 2-hop neighbors and eliminate those from reconsideration. We verify the efficacy of the proposed protocol with rigorous simulation results. The experimental results show that the proposed protocol outperforms the dominant pruning algorithm in reducing broadcast redundancy. Although collecting 3-hop neighborhood information requires some extra overhead, the additional cost is amortized over large data packets as number of re-transmissions of data packets is significantly reduced in the proposed technique.

The increasing use of multi-hop wireless networks and the growing demand of bandwidth-intensive multimedia applications are the driving force to explore innovative techniques that can enhance the capacity of multi-hop wireless networks. The commonly used omni-directional antennas limit the spatial reusability of the wireless channel and hence reduce the available capacity of wireless networks. On the contrary, bandforming antennas, that enable directional transmissions and receptions, can overcome the aforementioned limitation. With the recent advances in signed processing and antenna technologies, smart beamforming antennas have become feasible in compact sizes and suitable prices and hence pertinent to multi-hop wireless networks. However, lack of appropriate control over the antenna beamforming may deteriorate the overall performance even below the level achieved by omni-directional antennas. Moreover, beamforming antennas introduce unprecedented challenges including deafness and directional hidden terminal problems. Hence, it is important to design efficient mechanisms for both Medium Access Control (MAC) and routing to deal with these challenges that hinder the full exploitation of spatial reusability offered by smart beamforming antennas. In this dissertation, we develop an analytical framework for modeling directional contention-based MAC protocols, which is, up to our knowledge, the first model to include deafness in the analysis. We show that deafness can severely limit the network capacity. Based on the insights gained from our analysis of the limitations of the existing solutions, we propose a novel opportunistic directional MAC protocol for multi-hop wireless networks with beamforming antennas. The proposed MAC protocol employs a new backoff mechanism that aims at minimizing the unnecessary idle waiting time, which is a key factor in leveraging the spatial reuse. Through extensive simulations, we demonstrate that the proposed MAC protocol enhances the performance in terms of throughput, delay, packet delivery ratio and fairness. We have also addressed the question about the theoretical capacity gain achieved by beamforming antennas. We derive a generic interference model that can accommodate any antenna radiation pattern and show that the capacity gain is significant even when realistic antenna radiation patterns are used. Since smart beamforming antennas can significantly spare the network resources, they can be utilized to provide Quality of Service (QoS) guarantees. We study the bandwidth-guaranteed routing problem in contention-based multi-hop wireless networks with beamforming antennas. We first present an analysis for the wireless links interdependencies in a contention-based environment in the presence of beamforming, which helps in our formulation of the QoS routing problem as a mixed-integer non-linear optimization problem. We then propose a routing and admission control algorithm for its solution. Our simulation results demonstrate the accuracy of our analysis and the ability of our proposed algorithm to find bandwidth-guaranteed routes. In summary, the analysis and design approaches, adopted in this dissertation, enhance the throughput of multi-hop wireless networks by grasping the transmission opportunities offered by smart beamforming antennas while dealing with the beamforming-related challenges at the MAC and network layers, which otherwise limit the spatial reusability of the wireless channel.