waashk/dblp huggingface dataset:
coverage-aware connectivity restoration in mobile sensor networks. mobile sensor networks rely heavily on inter-sensor connectivity for collection of data. nodes in these networks monitor different regions of an area of interest and collectively present a global overview of some monitored activities or phenomena. a failure of a sensor leads to loss of connectivity and may cause partitioning of the network into disjoint segments. a number of approaches have been recently proposed that pursue node relocation in order to restore connectivity. however, these approaches tend to ignore the possible loss of coverage in some areas, either due to the failure itself or due to the connectivity-limited focus of the recovery. this paper fills this gap by addressing the connectivity and coverage concerns in an integrated manner. a novel coverage conscious connectivity restoration (c^3r) algorithm is presented. c^3r involves one or multiple neighbors of the failed node to recover from the failure. each neighbor temporarily relocates to substitute the failed node, one at a time, and then returns back to its original location. this leads to intermittent connectivity and monitoring of all the originally covered spots. this paper also presents energy-centric optimized recovery algorithm (ecr), an optimized version of c^3r that is geared for energy efficiency. both c^3r and ecr are validated through simulation. the simulation results confirm the effectiveness of these approaches.
a mathematical view of network-based suppressions of worm epidemics. when worms self replicate, their probe traffic increases the network load. it is known that some "bandwidth-limited" worms such as slammer spread so rapidly that they impede their own progress by congesting the network. existing worm epidemic models do not take into consideration the phenomenon of network congestion acting naturally to slow down the epidemic rate. in this paper, we present a new epidemic model, the community of households with limited inter-household bandwidths (coh-lihb), which we believe is the first model to account for limited network capacity and its impact on the spreading rate of a random scanning worm. in addition to explaining the natural dampening effect of network congestion, we use the new model to study the effectiveness of active defenses, namely dynamic quarantine and rate limiting, which artificially restrict the bandwidth available to worm traffic. the cohlihb model is applied to the specific example of a slammer-like worm to show how the combination of quarantine and rate throttling hypothetically could have been effective in suppressing the slammer outbreak.
fragmentation and aes encryption overhead in very high-speed wireless lans. in this paper, we study the overhead introduced by the advanced encryption standard cipher in the context of wireless lans, specifically at the medium access control layer, as described in the 802.11 standard developed by the 802.11n task group. we compute the maximum throughput, optimal frame, and fragment sizes which can be achieved in this context and compare them to the optimal values when encryption is not used.
an efficient software radio framework for wimax physical layer on cell multicore platform. wireless baseband processing, which is characterized by high computation complexity and high data throughput, is regarded as the most challenging issue for software radio (sr) systems. to relieve this implementation difficulty in sr systems, the multicore architecture is proposed. however, due to the lack of the universal parallel programming framework for sr systems, it is difficult to take full advantage of the multicore architecture. to fill this gap, in this paper, an efficient parallel sr framework is proposed under the cell multicore architecture for wimax base station (bs). with the proposed framework, one cell blade server (including two cell processors) can support up to three sectors, and each sector can support 20mbps data rate for both uplink and downlink. the system performance results verify the effectiveness of the proposed sr multicore framework.
on the performance of harq with hybrid relaying schemes. in this paper, we consider a three-node relay system with a hybrid relaying scheme, where the relay, based on its decoding status, switches between decode-and-forward (df) and compress-and-forward (cf) adaptively. we propose according harq strategy and analyze its throughput performance. then, we consider practical implementation issues by enhancing the ability of the feedback channel from the destination to the relay to convey a few extra bits (only 2 bits in this paper) and propose a modified harq scheme accordingly. the combined technique exhibits superior performance over direct transmission and conventional df.
a multi-agent reinforcement learning approach to path selection in optical burst switching networks. an important issue of research in optical burst switching (obs) networks is to minimize the loss of bursts due to contention at the intermediate nodes. these contention losses can be minimized with the design of efficient path selection algorithms at the ingress node. path selection algorithms that learn the optimal path dynamically with the changing traffic conditions outperform the deterministic path selection algorithms. usually in the single agent path selection algorithms, a path is selected by the agent based on the feedback received at the ingress node which does not capture the effect of the paths selected by the other nodes in the network. we develop a multi-agent approach for path selection that includes the effect of the selection made by all the other nodes in the network. the proposed path selection algorithm uses agents at different source nodes to collectively learn the network dynamics and select the best outgoing path for each burst. we present simulation results to demonstrate the effectiveness of the proposed algorithm over the other similar algorithms in the literature.
optimal sleep-wake policies for an energy harvesting sensor node. we study a sensor node with an energy harvesting source. in any slot, the sensor node is in one of two modes: wake or sleep. the generated energy is stored in a buffer. the sensor node senses a random field and generates a packet when it is awake. these packets are stored in a queue and transmitted in the wake mode using the energy available in the energy buffer. we obtain energy management policies which minimize a linear combination of the mean queue length and the mean data loss rate. then, we obtain two easily implementable suboptimal policies and compare their performance to that of the optimal policy. next, we extend the throughput optimal policy developed in our previous work to sensors with two modes. via this policy, we can increase the throughput substantially and stabilize the data queue by allowing the node to sleep in some slots and to drop some generated packets. this policy requires minimal statistical knowledge of the system. we also modify this policy to decrease the switching costs.
differentiated static resource allocation in wdm networks. we present a study on the static resource allocation in lightpath routed wdm networks, where each request is associated with a service grade. the goal is to maintain certain acceptance ratios for the requests of all grades, as well as to minimize the resource consumption. we propose a model of static grade-of-service (gos) differentiation as minimizing the total rejection and cost penalty. then, we use the lagrangian relaxation and subgradient methods to solve the problem. the results of using static gos differentiation are presented.
on the capacity of bidirectional broadcast channels under channel uncertainty. we consider the broadcast phase of a spectrally efficient two-phase decode-and-forward protocol which is used by a relay node to establish a bidirectional communication between two nodes. in the first phase the two nodes transmit their message to the relay node which decodes the messages. in the succeeding phase the relay node broadcasts a re-encoded composition of them. we consider imperfect channel knowledge and assume that all nodes merely know that the channel used for the transmission belongs to a set of channels. this is called compound bidirectional broadcast channel. we derive a universal strategy which achieves capacity and show that perfect channel state information (csi) at the receivers does not lead to an increased capacity region. otherwise, perfect csi at the transmitter can advantageously be used to enlarge the capacity region. finally, we give a game-theoretic interpretation as a game against nature.
design, implementation, and performance evaluation of an advanced sip-based call control for voip services. the growing interest in developing value-added services based on internet telephony brings into sharp focus several issues related to service creation. it becomes compelling for developers to take advantage of a platform that could offer high-level apis and standard interfaces, in order to reduce the time-to-market and extend the service portability over multiple networks and devices. the java community is tackling those issues within the java apis for integrated networks (jain) activity, utilizing java enterprise edition technologies in order to ease the development process of telecommunication services. this paper describes a sip-based call control service for internet telephony, designed for an ip-pstn converged scenario. the service has a back-to-back user agent (b2bua) architecture and is deployed into a service logic execution environment (slee). our slee is based on mobicents, an open-source platform for telecom applications, which offers an implementation of the jain slee specifications. we present the design and a comparative performance evaluation of different architectural implementations of the service, carried out with sipp, an open-source sip traffic generation tool.
sensitivity analysis of burst detection and rf fingerprinting classification performance. there has been a recent shift toward improving wireless access security within the osi phy layer by exploiting rf features that are inherently device specific and difficult to replicate by an unintended party. this work addresses the extraction and exploitation of rf "fingerprints" to classify emissions and provide device-specific identification. burst transient detection precedes rf fingerprint extraction and is generally the most critical step in the overall process. this work provides a much needed sensitivity analysis of burst detection capability. the analysis is conducted using instantaneous amplitude responses with both fractal-bayesian step change detection (fractal-bscd) and variance trajectory (vt) processes. the performance of each method is evaluated under varying snr conditions using experimentally collected 802.11a ofdm signals. the impact of transient detection error on signal classification performance is then demonstrated using rf fingerprints and multiple discriminant analysis (mda) with maximum likelihood (ml) classification. the vt technique emerges as the better alternative for all snrs considered and yields mda-ml classification accuracy that is consistent with "perfect" transient estimation performance.
a novel ray tracing based multipath modeling approach for site-specific wlan simulations. current propagation models used in network simulations neglect obstacles of a propagation environment and employ over-simplified assumptions that the received signal strength is a simple function of distance and the transmission area of a node is circular. these assumptions are in contradiction with the actual tests and the measurement results. to run reasonable simulations for evaluating the performance of a specific outdoor wireless testbed, a novel multipath propagation framework is proposed in this paper, which is based on the ray tracing technique and uses site-specific geographic data of the analyzed area. it provides accurate propagation predictions, and it does not significantly prolong the simulation duration.
minimum-latency gossiping in multi-hop wireless mesh networks. wireless mesh networks (wmns) is an emerging communication paradigm to enable resilient, cost-efficient and reliable services for the future-generation wireless networks. we study the minimum-latency communication primitive of gossiping (all-to-all communication) in multi-hop ad-hoc wmns. each mesh node in the wmn is initially given a message and the objective is to design a minimum-latency schedule such that each mesh node distributes its message to all other mesh nodes. minimum-latency gossiping problem is known to be np-hard even for the scenario in which the topology of the wmn is known to all mesh nodes in advance. we show an approximation scheme that can complete gossiping task in o(n log3/2n) time units with high probability at least 1-1/n in any ad-hoc wmn of size n. our algorithm allows the labels (identifiers) of the mesh nodes to be polynomially large in n. to the best of our knowledge, this is the first time that randomized algorithm has been considered in ad-hoc wmns with large labels. moreover, our gossiping scheme also significantly improved all current gossiping algorithms in terms of approximation ratio. our work has approximation ratio at most o(log32n) which is a great improvement of the current best known state-of-the-art algorithm with approximation ratio o(log3/2 n) but for linearly large node labels by czumaj and rytter[11].
effects of imperfect channel state information on achievable rates of precoded multi-user mimo broadcast channels with limited feedback. we consider multi-user mimo broadcast channels with limited feedback. a recently proposed linear precoding technique, regularized block diagonalization (rbd), is used to mitigate multi-user interference. we assume that each receiver has estimated channel state information (csi) via downlink training and independently quantizes its channel by using an efficient channel quantization scheme that we propose in this paper. the transmitter acquires the quantized csi from each receiver through a noiseless and delayed feedback channel. the achievable rates are studied under these assumptions. we derive an upper bound for the rate loss compared to the case that the transmitter has perfect csi and quantify the impact of channel estimation errors, quantization errors, and outdated quantized csi on the rate loss. furthermore, we provide an expression of the number of feedback bits needed per user to maitain that bound. it is found that the delay of the feedback is the predominant cause of performance degradation in the case of rapidly changing channel impluse response.
reduced complexity intrusion detection in sensor networks using genetic algorithm. we propose a reduced-complexity genetic algorithm for intrusion detection of resource constrained multi-hop mobile sensor networks. traditional intrusion detection mechanisms have limited applicability to the sensor networks due to scarce battery and processing resources. therefore, an effective scheme would require a power efficient and lightweight approach to identify malicious attacks. the goal of this paper is to evaluate sensor node attributes by measuring the perceived threat and its suitability to host local monitoring node (lmn) that acts as trusted proxy agent for the sink and capable of securely monitoring its neighbors. security attributes in conjunction with genetic algorithm jointly optimizes the placement of monitoring nodes (i.e, lmn) by dynamically evaluating node fitness by profiling workloads patterns, packet statistics, utilization data, battery status, and quality-of-service compliance.
optimum internet gateway selection in ad hoc networks. wireless ad hoc networks are connected to the fixed internet by means of internet gateways. whenever a node within the ad hoc network wishes to communicate with a host in the internet, it selects a default internet gateway to relay its traffic from the ad hoc network to the internet. in this paper, we formulate the problem of selecting the best internet gateway as a mixed integer linear program minimizing the maximum node utilization in the wireless network. by simulations, we show that the performance that can be achieved by solving this optimization problem is significantly higher than what is achieved by standard gateway selection algorithms based on hop count or gateway load. in particular, these heuristic algorithms fail to adapt to the offered traffic and available capacity in the network.
analysis of network coding in slotted aloha with two-hop bidirectional traffic. this paper deals with two representative bidirectional traffic cases in two-hop wireless relay access systems employing network coding and a slotted aloha protocol. network coding is a recent and highly regarded technology for capacity enhancement of multiple unicast and multisource multicast networks. the relay nodes are generally involved with unbalanced multidirectional traffic, but the impact of the unbalanced traffic on network coding has not been analyzed. this paper provides closed-form expressions for the throughput and packet delay for two-hop bidirectional traffic cases both with and without network coding even if the buffers on nodes are unsaturated. the analytical results are mainly derived by solving queueing systems for the buffer behavior at the relay node. the results show that the transmission probability of the relay node is a design parameter that is crucial for maximizing the achievable throughput of slotted aloha systems with network coding in two-hop bidirectional traffic cases.
achievable rates for the gaussian relay interferer channel with a cognitive source. a relay interferer channel consists of the classic relay channel with an additional source of interference. a three-terminal full-duplex gaussian relay interferer channel with a cognitive source is analyzed. each of the relay node and the destination node experiences on its link an additive gaussian outside interference, in addition to additive noise. only the source node, referred to as being the cognitive encoder, knows the interferences, in a non-causal manner. we first focus on the case in which the links to the relay and to the destination are corrupted by the same interference; and then we focus on the case of independent interferences. for each of these two models, we establish a lower bound on the channel capacity. the coding schemes for the lower bounds use techniques of dirty paper coding or carbon copying onto dirty paper, interference reduction at the source and decode-and-forward relaying. the results reveal that, by opposition to carbon copying onto dirty paper and its root costa's initial dirty paper coding (dpc), it may be beneficial in our setup that the informed source uses a part of its power to partially cancel the effect of the interference so that the uninformed relay benefits from this cancellation, and so the source benefits in turn.
fast spanning tree reconnection for resilient metro ethernet networks. ethernet is becoming a preferred technology to be deployed in metro domain due to its low cost, simplicity and ubiquity. however, spanning tree based ethernet protocol does not meet the requirement for metro area networks in terms of network resilience, despite the advancement of ethernet standardization and commercialization. in this paper, we propose a fast spanning tree reconnection (fstr) mechanism for metro ethernet networks to handle any single link failure, which has features of fast recovery, backup capacity guarantees and ease of implementation. upon failure of a link on a spanning tree, a distributed failure recovery protocol is activated to reconnect the broken spanning tree using a reconnect-link not on the spanning tree. we present the details of the protocol, including failure notification and forwarding table reconfiguration procedures. the pre-configuration of the reconnect-links to reconnect each spanning tree is formulated as an integer linear programming (ilp) problem. the optimization results show that with lower implementation cost, fast spanning tree reconnection mechanism can achieve comparative or considerably better performance than other resilient mechanisms for metro ethernet networks.
mechanism for maximizing area-centric coding gains in wireless multihop networks. localized network coding is a promising technique to improve the throughput of wireless multihop networks with multiple concurrent unicast sessions. however, most existing mechanisms in this field perform network coding without considering the maximization of joint coding gain among neighboring nodes. in this paper, we study how to improve network performance by maximizing the area-centric coding gains in wireless networks. to achieve this goal, we design an efficient coding-aware transmission scheduling mechanism. simulation results show that our mechanism can remarkably improve the network throughput as compared with existing mechanisms.
markov chain minimum bit error rate detection for multi-functional mimo uplink. in this paper, we introduce a novel markov chain (mc) representation aided minimum bit error rate (mber) detection method that is applicable to an m-qam modulated sdm/sdma uplink system. compared to the conventional mber scheme, the proposed mc-mber scheme is capable of reducing the complexity imposed with the aid of its efficient detection candidate set generation assisted by the markov chain process. our performance results demonstrate that the mc-mber multi-user detection (mud) is capable of reducing the computational complexity by a factor of eight in comparison to the conventional mber mud in a rank-deficient system transmitting four 4-qam uplink substreams with the aid of two receive antennas at the base station (bs), while achieving a ber performance comparable to that of the mber mud.
efficient fpga implementation of mimo decoder for mobile wimax system. in this paper, we present a fpga prototyping of the mimo decoder for the ieee 802.16e wimax mobile systems. the ieee 802.16e standard supports three types of mimo space time codes (stc), referred to in the standard by matrix a, b, and c, that achieve different levels of throughput and diversity depending on the quality of the mimo channels. in particular, the stc matrix a achieves full diversity by employing the alomuti coding, while the stc matrix b achieves full rate by employing spatial multiplexing and the stc matrix c achieves full rate and diversity by employing the golden code. in this paper, we present a fpga architecture of mimo decoder based on the fixed sphere decoder (fsd) algorithm that achieves close-to ml ber performance with a reduced computational complexity and fixed throughput. we show how a single fsd can be used to decode the different stc by adaptively processing the received signal according to the stc type prior to be fed to the fsd. the fpga design is incorporated with a qr decomposition of the channel matrix. the proposed fsd achieves fixed and high throughput required for the wimax systems. the fpga implementation is incorporated with a matlab simulation model of an fusc ofdma-based wimax 2x2 mimo system to validate the hardware design.
base station pilot management for user-deployed cellular networks. in this paper we review a 4g vision of deploying a cellular network whose infrastructure topology can be autonomously determined by cellular users. intelligent spectrum management is required for cellular interference control and mobile handoff management etc. we study an optimization method that maximizes the cell size coverage for user-deployed base stations, e.g. femtocells. the algorithm periodically updates the pilot power configuration based on each femtocell's channel pass loss and the global traffic distribution in the network. performance results are studied by simulation based on the wcdma cellular standard.