waashk/dblp huggingface dataset:
a fluid background traffic model. background traffic has a significant impact on the behavior of network services and protocols. however, a detailed model of the background traffic can be extremely time consuming in simulation. in this paper, we extend our previous hybrid model that combines fluid and packet-oriented characterization of network traffic for a realistic representation of the background traffic on internet. in particular, we get rid of some unrealistic assumptions in the hybrid model, by adding an acknowledgment scheme to correctly capture the mutual influence of fluid tcp flows on network queues, and by applying the poisson pareto burst process (ppbp) model to describe the long-range dependencies of the internet traffic. experiments show that our fluid background traffic model can capture similar level of realism as the traditional packet-oriented approach.
problem-specific encoding and genetic operation for a multi-objective deployment and power assignment problem in wireless sensor networks. wireless sensor networks deployment and power assignment problems (dpaps) for maximizing the network coverage and lifetime respectively, have received increasing attention recently. classical approaches optimize these two objectives individually, or by combining them together in a single objective, or by constraining one and optimizing the other. in this paper, the two problems are formulated as a multi-objective dpap and tackled simultaneously. problem-specific encoding representation and genetic operators are designed for the dpap and a multi-objective evolutionary algorithm based on decomposition (moea/d) is specialized. the multi-objective dpap is decomposed into many scalar subproblems which are solved simultaneously by using neighborhood information and network knowledge. simulation results have shown the effectiveness of the proposed evolutionary components by providing a high quality set of alternative solutions without any prior knowledge on the objectives preference, and the superiority of our problem-specific moea/d approach against a state of the art moea.
spectrum balancing algorithms for power minimization in dsl networks. spectrum balancing (sb) techniques optimize transmission and can significantly improve digital subscriber lines (dsl) services. in the literature, the dsl system optimization is typically formulated as a rate maximization problem. however, there is an increasing interest in minimizing the considerable amount of power consumed by telecommunication networks. few works in the sb literature have explored algorithms for power minimization. it is known that some existing solutions for rate maximization can be converted into power minimization algorithms. this relation has not been fully explored and, consequently, the area lacks results regarding what can be achieved with power minimization sb algorithms. this work aims to diminish this gap. first, the equivalence between rate maximization and power minimization problems is formalized. second, extended versions of some rate maximization sb algorithms are proposed for power minimization purposes and evaluated through simulations. in addition, the power-usage capabilities and convergence characteristics of each extended sb algorithms is discussed.
uwb radar sensor networks detection of targets in foliage using short-time fourier transform. in this paper, we study target detection in foliage environment. when radar echoes are in good quality, the detection of target can be achieved by applying short time fourier transform (stft) to the received uwb radar waveform. we compare our approach in case of no target as well as with target against the scheme in which 2-d image was created via adding voltages with the appropriate time offset. results show that our approach can detect target more easily. when radar echoes are in poor condition and single radar is unable to carry out the detection, we employ both radar sensor networks (rsn) and rake structure to combine the echoes from different radar members and finally detect the target.
performance of host identity protocol on symbian os. the host identity protocol (hip) has been specified by the ietf as a new solution for secure host mobility and multihoming in the internet. hip uses self-certifying public-private key pairs in combination with ipsec to authenticate hosts and protect user data. while there are three open-source hip implementations, little experience is available with running hip on lightweight hardware such as a mobile phone. limited computational power and battery lifetime of lightweight devices raise concerns if hip can be used there at all. this paper describes the porting process of hip on linux (hipl) and openhip implementations to symbian os, as well as performance measurements of hip over wlan using nokia e51 and n80 smartphones. we found that with 1024-bit keys, the hip base exchange with a server varies from 1.68 to 3.31 seconds depending on whether the mobile phone is in standby or active state respectively. after analyzing hip performance in different scenarios we make conclusions and recommendations on using ip security on lightweight hardware clients.
minimum energy strong bidirectional topology for ad hoc wireless sensor networks. a node in a wireless sensor network typically consists of a micro-controller, a communication device or transceiver, and a battery unit for powering the transceiver and other devices. an important feature of wireless sensor networks is the low power consumption requirement, since these sensor nodes carry generally irreplaceable power sources or batteries. we consider the problem of assigning a power to each node in the network such that the induced connectivity graph is strongly connected with only bidirectional links, and the sum total of powers assigned to all sensor nodes is minimized. this will allow the nodes to communicate with each other, while conserving battery power as much as possible. this problem has been shown to be strongly np-complete and heuristic approaches for solving this problem have been reported in the literature. in this paper, we establish a lower bound on the optimal power value, and provide a sufficient condition for a minimal spanning tree (mst) based approach to be an optimal solution to the problem. based on this condition, we propose a novel heuristic approach which computationally outperforms previously reported heuristics.
quantum coin-flipping-based authentication. quantum cryptographic key distribution (qkd) is a promising candidate for achieving unconditional security, making the renowned one-time pad encryption technically feasible for building computer networks. however, although well-developed theoretical foundations perfectly ensure protection against eavesdropping, no natural mechanism is yet able to successfully repel an adversary sitting between alice and bob, performing qkd with both and re-encrypting each message after heaving read it in plain text. authentication is hence of crucial importance, and normally applied to all messages that are related to the public discussion part of the qkd protocol. we present an analysis of a scenario, in which authentication is postponed until the end of the qkd protocol. this yields to reduced computational effort, as well as simple and tight bounds on the amount of preshared key material. our solution relies on a combination of quantum key distribution and quantum coin-flipping, which ensures noncontrollability of the qkd key. based on this assumption, we can apply a standard fingerprint comparison for authentication, to guard the protocol against a person-in-the-middle attack.
space-time coding and processing with differential chaos shift keying scheme. this paper investigates the feasibility to use chaotic communications in mimo channel. differential chaos shift keying modulation is chosen as a benchmark and alamouti space-time code scheme is used for the 2 transmit and 2 receiver antennas wireless system. based on the evaluation of system performance, improvements are also discussed.
minimizing energy consumption in ir-uwb based wireless sensor networks. impulse radio ultra-wideband (ir-uwb) communication has proven an important technique for supporting high-rate, short-range, low-power communication. these are necessary criteria for emerging sensor networks, which oftentimes have very short distance communication requirements, necessitate low power operation and may require high data rates (e.g., for supporting the transmission of images or video). in this paper, using detailed models of typical ir-uwb transmitter/receiver structures, we minimize the energy consumption per information bit in a single link of an ir-uwb system, considering packet retransmissions and overhead. this minimization is realized by finding the optimum packet length and the optimum number of rake fingers at the receiver for different transmission distances, using differential bpsk (dbpsk) and ook with coherent and non-coherent detection. our results show that at very short distances, it is optimum to use ook with non-coherent detection and large packets, and at longer distances, it is optimum to use dbpsk with coherent detection and small packets.
a simplified suboptimal algorithm for tone reservation ofdm. a gradient algorithm has been used in the tone reservation technique for peak to average power ratio (papr) reduction. this provides a good approximation to the optimal solution with lower complexity. this technique requires that a kernel signal be computed and iteratively shifted in the time-domain to the peak locations to reduce the papr. the kernel signal should be updated dynamically for the best performance in time varying channels, which increases the computational complexity. in this paper, we propose a low complexity gradient algorithm for computing the peak reduction kernels. this approach is more efficient than the previous algorithm, and provides better papr performance.
performance comparison among conventional selection combining, optimum selection combining and maximal ratio combining. reference [1] introduced optimum selection combining (osc) for binary phase shift keyed signals which selects the diversity branch having the maximum a posteriori probability. it performs much closer to maximal ratio combining (mrc) than the conventional selection combining (csc) which selects the diversity branch having the maximal instantaneous signal power [2]. it is known that these combining techniques have the same diversity order (do), i.e., the same performance slope (log error probability versus signal-to-noise ratio (snr) in db) - the performance variation is the snr difference (gap) between any two techniques to achieve the same bit error rate (ber). this paper derives closed-form expressions for the snr gaps among these three combining schemes. the paper also analyzes the asymptotic ber for these three combining schemes as a function of do for a fixed snr.
dsc: cooperation incentive mechanism for multi-hop cellular networks. muli-hop cellular network is a promising network architecture which incorporates the ad hoc characteristic into the cellular system aiming to improve current cellular network performance. unlike single hop cellular network, due to involving autonomous devices in packet forwarding, routing process suffers from new security challenges which endanger the practical implementation of the network. one security challenge is that selfish devices do not relay other nodes' packets because cooperation consumes their resources and does not provide any immediate advantages. selfish nodes degrade the network throughput, connectivity and power consumption. in order to stimulate the nodes' cooperation, we propose a micro-payment mechanism to reward the forwarding nodes and charge the communicating ones. the security analysis shows that the proposed mechanism is robust against rational attacks, and it can thwart some irrational ones. to evaluate the cost of applying our mechanism, an implementation model is proposed. the performance analysis based on the implementation model demonstrates that the overhead is acceptable.
matched rotation precoding: a new paradigm in space-frequency coding. this paper proposes an efficient rate one space-frequency block code (sfbc) for multiple-input multiple-output orthogonal frequency division multiplexing (mimo-ofdm) systems. the proposed sfbc incorporates concept of matched rotation precoding (mrp) to achieve full transmit diversity and optimal system performance for arbitrary number of transmit antennas, subcarrier interval and subcarrier grouping. the mrp exploits the inherent rotation property of sfbc and has relaxed restrictions on subcarrier interval and subcarrier grouping, making it ideal for adaptive/time varying systems. the lowerbound of the coding gain for mrp is derived and shown that it is useful when designing a sfbc for practical scenarios, e.g. when transmitters have only partial knowledge of power delay profile or when the power delay profile has only a few dominant delayed paths. simulation results show that themrp can achieve a similar or better performance than existing sfbcs.
downlink resource allocation for ofdma-based multiservice networks with imperfect csi. this paper addresses practical implementation issues of resource allocation in ofdma networks: inaccuracy of channel state information (csi) available to the resource allocation unit (rau) and diversity of subscribers' quality of service (qos) requirements. the resource allocation problem in the considered point-to-multipoint (pmp) network is modeled as a network utility maximization (num) problem that allocates subcarriers, rate and power while satisfying orthogonal frequency division multiple access (ofdma) constraints and qos constraints defined in the service level agreement. performance evaluation findings support our theoretical claims: a substantial data rate gain is achieved by considering the csi imperfection and multiservice classes are supported with qos guarantees by coordinating with a call admission control (cac) scheme.
performance evaluation of harq schemes for cooperative regenerative relaying. two hybrid arq (harq) schemes based on selective decode and forward are considered for a cooperative half-duplex relay channel. two time slot types: t1 slot for relay listening and t2 slot for relay forwarding are assumed to accommodate half duplex relaying. the considered harq schemes differ in the frequency of the arq feedback: one is frame and the other is slot based where each frame is composed of one t1 followed by one t2 slot. two types of encodings: repetition coding (rc) and unconstrained coding (uc) (also known as incremental redundancy) are assumed. outage performance analysis is carried out for both rc and uc. the state transition models of the considered protocols are presented and are used to analytically calculate the harq throughput and latency performance; thus avoiding time consuming monte carlo based evaluations. the provided analysis enables us to predict the system performance and tune its transmission parameters (transmission rate and frame structure) for any combination of the signal to noise ratio (snr) of the constituent links.
spectrum handoff in cognitive radio networks: opportunistic and negotiated situations. spectrum handoff is an indispensable component in cognitive radio networks to provide resilient service for the secondary users. in this paper, we explore the spectrum handoff procedure and then propose four metrics to characterize both short-term and long-term spectrum handoff performance: link maintenance probability, the number of spectrum handoff, switching delay, and non-completion probability. in particular, the probability mass function (pmf) and the average number of spectrum handoff are developed. the tele-traffic parameters are relaxed to follow a general distribution function, which will enable a wide applicability and theoretical significance of the derived formulae. both opportunistic and negotiated spectrum access strategies are investigated. results show that these two mechanisms will generate significantly different performance. numerical examples are presented to demonstrate the performance trade-off and the interaction between the primary users and the secondary users. the impact of key parameters on spectrum handoff is also discussed. the techniques as well as the results are important for evaluating the primary and second users co-existence, and hence helpful for design and optimization of cognitive radio networks.
em-based maximum-likelihood sequence detection for mimo optical wireless systems. a major performance-limiting factor in terrestrial optical wireless (ow) systems is turbulence-induced fading. exploiting the additional degrees of freedom in the spatial dimension, multiple laser transmitters combined with multiple receiver apertures provide an effective solution for fading mitigation. although mimo (multiple-input multiple-output) ow systems have been extensively studied in recent years, most of these works are mainly limited to symbol-by-symbol decoding. maximum likelihood sequence detection (mlsd) exploits the temporal correlation of turbulence-induced fading and promises further performance gains. in this paper, we investigate mlsd for im/dd (intensity-modulation/direct-detection) mimo ow systems over log-normal atmospheric turbulence channels. even with a low-order modulation scheme such as on-off keying which is typically used in ow systems, the complexity of mlsd might be prohibitive. we therefore present an iterative sequence detector based on the expectation-maximization (em) algorithm. the complexity of the proposed algorithm is much smaller than a direct evaluation of the log-likelihood function. the monte-carlo simulation results demonstrate that the em-based algorithm outperforms the symbol-by-symbol decoder and achieves a performance which lies within 0.5 db of that of the optimal mlsd.
design of a delay-based routing protocol for multi-rate multi-hop mobile ad hoc networks. the temporal fluctuations in quality exhibited by the wireless links act as a major challenge in the design of efficient routing protocols in real-world mobile ad hoc networks (manets). none of the existing link metrics fully account for the characteristics of data loss and delay on the links of a manet. this paper provides the design of a novel delay-based link quality metric that uses real-time statistics from the wireless driver to take into account wireless contention, congestion, channel loss and mobility. the proposed delay metric is additive, does not introduce much additional overhead and is reflective of the varying wireless link quality. we design an efficient link delay-aware routing (ldar) protocol based on the proposed link metric. the proposed protocol has been implemented on a manet test bed consisting of 5 laptop nodes. the evaluation of our protocol performed through extensive experimentation on the 5-node multi-hop manet testbed and network simulator ns-2 demonstrate the superior benefits of the new protocol.
delay-based congestion avoidance for qos provisioning in wired/wireless networks. with the emergence of high bandwidth-delay product and heterogeneous wired / wireless networks, the standard tcp appears to be too conservative to offer reasonable performance. the use of parallel tcp connections has been suggested in such environments. we have demonstrated that, with the same level of aggressiveness, this approach can outperform the single-connection based approach. however, this approach also introduces new problems: the complexity of managing multiple connections and its performance sensitive to the number of the connections in use. this paper presents a few methods to overcome these problems. in particular, we propose a novel method using a delay-based congestion avoidance (ca) algorithm with multiple connections. this method is not sensitive to the number of the connections in use. we also suggest using a smaller number of connections to emulate the behaviours of a number of standard tcp connections, in order to reduce the complexity of connection management.
shedding new light on sequence design criteria for multipath channels. the merit factor (mf) introduced by golay has long been accepted as the standard criterion to evaluate and design binary sequences with good anti-multipath property in sonar, radar, and communication systems for its theoretical tightness and practical simplicity. in this paper, we first show that the mf is a biased anti-multipath performance evaluation metric in theory and, more importantly, is not a pertinent sequence design criterion in practice for most binary sequences of practical interest. then we propose the weighted merit factor (wmf) based on a non-uniform weighting of the out-of-phase aperiodic autocorrelation function (acf) that provides accurate measurement of self-generated interference for the constant amplitude complex-valued sequences and the nonconstant modulus ones. based on the wmf, a list of "bad" (of low mfs) binary sequences (lengths 33-95) with better anti-multipath performance than the "best" (known) ones have been designed to verify its greater pertinence over the mf as a sequence design criterion for sonar, radar, and communication systems. moreover, we extend the weighted correlation model of the wmf to the code-division multiple-access (cdma) systems and propose the weighted cross-correlation factor (wcf) to evaluate the sequence set's multiple-access interference (mai) rejection property in the context of multipath propagation. theoretical analysis corroborated by simulations confirms that the wcf provides greater practical pertinence and analytical tractability over the current standard criterion.
transmission control with imperfect csi in channel-aware slotted aloha networks. the impact of imperfect channel state information (csi) on the transmission control of channel-aware slotted aloha networks is studied in this work. by taking into consideration the statistics of the channel estimation error to maximize the achievable stable throughput, we obtain the optimal transmission control policy that determines the transmission probability, rate, and power that should be adopted under different channel states. specifically, with imperfect csi, we find that high transmission probabilities should be assigned to channel states that allow for high probability of successful transmission (which may be affected by the estimation errors), but rate allocation must be performed more conservatively (compared to the case with perfect csi) in order to avoid transmission errors due to imprecise channel estimates. the policies are first developed for single carrier systems and then extended to multi-carrier systems with maximum per-user power constraints. the asymptotic maximal stable throughput is analyzed for both the single and multiple carrier systems as the number of users goes to infinity. we observe that, with error in the channel estimate, the proposed transmission control policy that takes into consideration the error statistics may significantly increase the throughput compared to strategies that are derived under the perfect csi assumption.