waashk/dblp huggingface dataset:
transmission capacity of wireless ad hoc networks: successive interference cancellation vs. joint detection. the performance benefits of two interference cancellation methods, successive interference cancellation (sic) and joint detection (jd), in wireless ad hoc networks are compared within the transmission capacity framework. sic involves successively decoding and subtracting out strong interfering signals until the desired signal can be decoded, while higher-complexity jd refers to simultaneously decoding the desired signal and the signals of a few strong interferers. tools from stochastic geometry are used to develop bounds on the outage probability as a function of the spatial density of interferers. these bounds show that sic performs nearly as well as jd when the signal-to-interference ratio (sir) threshold is less than one, but that sic is essentially useless for sir thresholds larger than one whereas jd provides a significant outage benefit regardless of the sir threshold.
optimising radio access in a heterogeneous wireless network environment. a variety of wireless network technologies have been developed and deployed, including gsm, umts, wifi and wimax. the advantages of having an integrated heterogeneous wireless network environment include seamless communications, joint resource management and adaptive quality of service. in such environment, operators would not need to reject the service requests, but redirect them to appropriate networks. however, the sought aims of a heterogeneous network system still have many pending issues. one of them is the selection of the most appropriate radio access network (ran) according to the requested service and the context information about the user and the networks. we aim to develop efficient ran selection algorithms to facilitate radio access optimisation for future heterogeneous network system. the simulation results show that our ran selection algorithm can improve the network performance.
near-optimal relaying strategy for cooperative broadcast channels. we propose a near-optimal relaying strategy for cooperative broadcast channels (cbc), cbc-ssaf, based on the class of sequential slotted amplify and forward (ssaf) strategies. our strategy allows each destination to act in turn as a relay and forward its previously received signal to other destinations. while cbc-ssaf is not a full multiplexing gain strategy, the loss is negligible when the number of destinations is large. moreover, cbc-ssaf allows each destination to be protected by the maximum number of extra paths in order to achieve the near-optimal diversity gain in the high multiplexing gain regime. a diversity and multiplexing tradeoff (dmt) lower bound for cbc-ssaf is derived which suggests that our proposed relaying strategy approaches the multiple-input multiple-output (mimo) dmt upper bound and is therefore asymptotically optimal.
distributed ecn-based congestion control. following the design philosophy of xcp, vcp is a router-assisted congestion protocol that intends to balance the efficiency and the fairness control in high bandwidth-delay product networks. while both vcp and xcp achieve comparable performance, vcp represents a more practical alternative of deployment as it only requires the use of two ecn bits in the ip header. however, the use of two ecn bits only allows for establishing three levels of congestion notification signaling. our previous work reveals that vcp suffers from relatively low speed of convergence and exhibits a biased fairness behavior in moderate bandwidth high delay networks due to utilizing an insufficient amount of congestion feedback. in this paper, we propose a distributed ecn-based congestion control protocol to which we refer as double-packet congestion control protocol (dpcp). dpcp is capable of relaying a more precise congestion feedback compared to earlier proposed variable-structure congestion-control protocol (vcp) yet preserving the utilization of the two ecn bits. by distributing (extracting) congestion related information into (from) a series of packets, dpcp is able to circumvent the limitations of vcp related to the use of three congestion levels encoded into two ecn bits. we implement dpcp in linux and demonstrate its performance improvements compared to vcp through experimental studies.
second order statistics of non-isotropic mobile-to-mobile ricean fading channels. this paper develops a generic geometry-based stochastic model for mobile-to-mobile (m2m) ricean fading channels. from the generic model, the level crossing rate (lcr) and average fade duration (afd) are derived. based on the derived expressions, we for the first time investigate the lcr and afd for m2m channels with different vehicular traffic densities (vtds). excellent agreement is achieved between the theoretical results and measured data, demonstrating the utility of the proposed model.
optimization of cooperative sensing in cognitive radio networks: a sensing-throughput tradeoff view. in cognitive radio networks, protection to primary users can be quantified by the probability of detection. on the other hand, the probability of false alarm affects the achievable throughput of secondary users. performances of these two probabilities depend heavily on the fusion scheme used when cooperative sensing is performed. in this paper, we consider the case where n secondary users sense the channel cooperatively using k-out-of-nfusion rule. a sensing-throughput tradeoff under cooperative sensing scenario is formulated to find a pair of sensing time and k value that maximize the secondary users' throughput subject to sufficient protection provided to the primary user. an iterative algorithm is proposed to obtain the optimal values of these two parameters. computer simulations show that significant improvement of the secondary users' throughput can be achieved when the parameters from the fusion scheme and sensing time are jointly optimized.
signal classification using a peak-to-average power ratio statistic. this paper addresses signal classification based on an average power statistic for peak-to-average-power ratio (par) reduced signals. specifically, it is assumed that either a qam or a complex gaussian finite-length symbol is transmitted in a noisy, peak-limited channel with known peak power. the goal is determine the whether an uninformed receiver can distinguish between these signal types using an average power statistic. several methods for transmitting through peak-power channels are examined including optimal clipping and piecewise linear scaling (pwls) with selected mapping (slm) par reduction. for the analysis, it is necessary to derive the mean power for each of the transmission methods. accordingly, we show how the harmonic mean par, e[1/par], is related to the mean power and derive e[1/par] in closed form. we find that average power is a accurate discriminator for low-order qam and gaussian symbols. for high-order qam, accurate discrimination is also possible when the noise level is sufficiently low or when enough signal samples are available.
error probability of energy detected multilevel pam signals in lognormal multipath fading channels. noncoherent multilevel systems have been typically analyzed with spectrally inefficient orthogonal modulation methods. in this paper, we present a novel error probability analysis of energy detected (ed) signals with spectrally efficient multilevel pulse amplitude modulation (pam). one of the main challenges in the analysis of ed systems with the multilevel pam is to find analytical methods to evaluate and optimize the performance of ed systems with respect to arbitrary system parameters, e.g., decision thresholds for chi-squared-distributed decision variables, integration time, bandwidth, and number of modulation levels. we propose analytically tractable methods that can be efficiently used to design spectrally efficient ed systems for short-range, wideband, and high data rate wireless communications in lognormal multipath fading channels with uncorrelated diversity paths.
generalized differential vector signaling. binary nrz signaling over single ended or fully differential parallel wired channels is commonly used for chip-to-chip communications. this paper presents differential vector signaling as a generalized new class of signaling for parallel wired links. differential vector signaling has many of the benefits inherent to differential signaling while maintaining high pin efficiency of single ended parallel links and offers an alternative solution for high speed chip-to-chip interconnections. the signaling is viewed as a multi-wire coded communication system. the encoding method and the maximum likelihood decoding algorithm are presented. also a variant of this signaling which requires a reduced complexity receiver is proposed.
marking conversion for pre-congestion notification. pre-congestion notification (pcn) defines admissible rates (ar) and supportable rates (sr) per link and marks the pcn traffic rate above these thresholds as ar- or sr-overload. the ietf standardizes simple mechanisms for admission control (ac) and flow termination (ft) based on this pcn-feedback for high-priority diffserv traffic. while admission control (ac) has been extensively discussed in the literature, flow termination (ft) is a new control function. in this paper we propose an algorithm that converts marked ar-overload into marked sr-overload by unmarking appropriate packets. classic marked flow termination (mft) is based on marked sr-overload and works well even with a small number of pcn flows per ingress-egress aggregate and in case of multipath routing. thanks to the new marking converter mft also works with marked ar-overload so that a single marking scheme suffices to support ac and ft. we investigate whether mft with marking conversion based on ar-overload retains the benefits classic mft.
a fault-tolerant backbone network architecture targeting time-critical communication for avionic wdm lans. in this paper, we focus on the design and analysis of a torus-based backbone architecture which targets to meet both the low delay and high reliability requirements of avionic time-critical communications. reliable optical connection between arbitrary source-destination pairs is proposed by enabling four non-overlapping lightpaths between the source and destination, which makes the network tolerant to at least three arbitrary link failures without losing connectivity. a greedy algorithm is introduced to set up the four non-overlapping lightpaths with the aim of maximizing two-terminal reliability (ttr), as well as minimizing signal attenuation and propagation delay. a wavelength assignment and reuse (war) method is used to reduce by half the wavelength requirement for all-to-all communication in a case study of 4×4 torus. both probabilistic analysis and a packet-level simulation reveal that the proposed architecture can provide efficient communication with a 3-fault reliability guarantee.
interference-aware energy-efficient power optimization. while the demand for battery capacity on mobile devices has grown with the increase in high-bandwidth multi-media rich applications, battery technology has not kept up with this demand. therefore power optimization techniques are becoming increasingly important in wireless system design. power optimization schemes are also important for interference management in wireless systems as interference resulting from aggressive spectral reuse and high power transmission severely limits system performance. although power optimization plays a pivotal role in both interference management and energy utilization, little research addresses their joint interaction. in this paper, we develop energy-efficient power optimization schemes for interference-limited communications. both circuit and transmit powers are considered and energy efficiency is emphasized over throughput. we note that the general power optimization problem in the presence of interference is intractable even when ideal user cooperation is assumed. we first study this problem for a simple two-user network with ideal user cooperation and then develop a practical non-cooperative power optimization scheme. simulation results show that the proposed scheme improves not only energy efficiency but also spectral efficiency in an interference-limited cellular network.
an automatic and dynamic parameter tuning of a statistics-based anomaly detection algorithm. the detection of anomalies in network traffic is a crucial issue affecting the security of internet users. a statistical network anomaly detection algorithm is a promising way of detecting such anomalies, however, it has to be given appropriate parameters for accurate detection and identification. in general, it is very difficult to obtain appropriate parameter settings a priori, because network traffic is not stable in time or space. thus, although many anomaly detection methods have been proposed, there has been little discussion about their parameter tunings. in this paper, we investigate an automatic and dynamic parameter tuning of a statistical network traffic anomaly detection method. in particular, we clarify whether one can consistently use the best parameter fixed for a certain instance; this choice clearly depends on the macroscopic and dynamic behavior of internet traffic anomalies. we ascertain the appropriate learning period for setting a parameter of an anomaly detection algorithm based on a sketch and multi-scale gamma-function model by using real network traces measured in a trans-pacific link over a period of six months. the main results of our study are as follows: (1) without learning, the best parameter varies day by day. (2) with a longer learning period, the best parameter setting is affected by significant data during the learning period. (3) the appropriate period of the learning is about 3 days. (4) the performance degradation from introducing dynamic parameter tuning is 17% in the best case.
mean waiting delay for web object transfer in wireless sctp environment. most current web application use http (hyper text transfer protocol) and tcp (transmission control protocol) to retrieve objects from the internet. sctp (stream control transmission protocol) is recently proposed transport protocol with congestion control mechanism similar to that of tcp. waiting delay is an important performance criterion for when transferring web object over the internet. in this paper, we present an analytical model of mean waiting delay for object transfers over the internet in a wireless using the sctp as the transport protocol and compare with the mean waiting in using tcp. validation of the model using experimental results show that the mean waiting delay for http over sctp is less than that for http over tcp. this is caused by the small slow-start time of sctp.
a polite cross-layer protocol for contention-based home power-line communications. in typical home power-line communication (plc) networks using contention-based access methods, providing quality-of-service (qos) to high-priority users often comes at the expense of reducing the throughput of low-priority users. this paper proposes a cross-layer protocol which involves interaction between the physical (phy) and the medium-access-control (mac) layers, for ensuring politeness of the high-priority users toward the low-priority users for uplink transmission in home plc networks. this protocol modifies the contention-based csma protocol of the mac layer to exploit the cyclostationarity of the noise in home plc networks. the plc noise spectrum has been shown in literature to be periodic with the period of ac line cycle. using this periodicity, the proposed protocol allows longer medium-access times for low-priority users in every ac line cycle, while meeting the high throughput requirements of the high-priority users. the proposed cross-layer protocol, termed opportunistic csma, improves the throughput of the low-priority users by as much as 300% compared to the current csma protocols in home plc networks.
distributed intrusion detection with intelligent network interfaces for future networks. intrusion detection remains an important and challenging task in current and next generation networks (ngn). emerging technologies such as multi-core processors and virtualization have changed the architecture of the building elements of ngn significantly, thus call for rethinking of how network processing is done. in this paper, we propose distributed intrusion detection using intelligent network interfaces where additional processing capabilities are available. we design and implement a prototype to perform pattern matching using network processors since pattern matching is one of the important workloads in intrusion detection. through the experimental results, we show the feasibility and performance of distributed intrusion detection in next generation networks.
real-time traffic in ad-hoc sensor networks. the usage of sensors is emerging in the nowadays scenario where safety related applications are more and more used. these applications have timing constraints that need to be met by the control system. thus, guaranteeing timeliness properties is considered a key challenge for research on wireless sensor networks. among the different components that need to address this problem, we focus on the communication sub-system and, in particular, on the mac protocols that handles transmissions. to provide timeliness behavior, the employed mac protocol has to provide a time-bounded service. the contribution of this paper is to investigate the performance of two wireless mac protocols that can be employed in wireless sensor networks: ieee 802.11e and wrt-ring. the former is part of the well know ieee 802.11 standard, whereas the latter has characteristics that well fit the requirements of wireless sensor networks. results show that two protocols have similar performances for networks with limited devices and/or traffic, whereas when devices and/or traffic increases, wrt-ring has to be preferred.
routing-based source-location privacy in wireless sensor networks. wireless sensor networks (wsn) have the potential to be widely used in many areas for unattended event monitoring. mainly due to lack of a protected physical boundary, wireless communications are vulnerable to unauthorized interception and detection. privacy is becoming one of the major issues that jeopardize the successful deployment of wireless sensor networks. while confidentiality of the message can be ensured through content encryption, it is much more difficult to adequately address the source-location privacy. for wsn, source-location privacy service is further complicated by the fact that the sensor nodes consist of low-cost and low-power radio devices, computationally intensive cryptographic algorithms (such as public-key cryptosystems) and large scale broadcasting-based protocols are not suitable for wsn. in this paper, we propose a scheme to provide both content confidentiality and source-location privacy through routing to a randomly selected intermediate node (rrin). while being able to provide source-location privacy for wsn, our simulation results also demonstrate that the proposed scheme is very efficient and can be used for practical applications.
protocols and resource allocation for the two-way relay channel with half-duplex terminals. the two-way relay channel (twrc) describes the communication between two terminals sharing a common relay. in this work we compare different protocols for the twrc with a half-duplex relay (forwarding and protocol i) and transmission schemes (network coding relaying with random binning and xor precoding), when the relay works in decode-and-forward and without channel state information at the transmitters. we provide the optimal resource allocation (in terms of phase duration, data rate and power allocation) when there is an individual or sum-average power constraint over the terminals. closed-form solutions are derived whenever it is possible, while for others cases we show that the resource allocation can be formulated as a convex problem, which means that the solution can be obtained by low-complexity interior point methods.
three layered hidden markov models for binary digital wireless channels. generative models are created to be used in the design and performance assessment of high layer wireless communication protocols and some error control strategies. generative models can replace real digital wireless channels to significantly reduce the time and complexity of system simulation. the errors occurring in digital wireless channels are not independent but form clusters or bursts. generative models have to produce error sequences having similar burst error statistics to those of original error sequences obtained from real digital systems. in this paper, we propose a generative hidden markov model (hmm) with three layers. it is shown that the proposed three layered hmm can generate error sequences that have statistics compatible with those of original error sequences derived from an enhanced general packet radio service (egprs) transmission system.
performance improvement of error-prone multi-rate wlans through adjustment of access/frame parameters. the ieee 802.11 standard supports multiple phy rates. however, the ieee 802.11 dcf in a multiple-rate environment may cause a performance anomaly. there have been many studies about the performance analysis and improvement of single- and multi-rate wlan systems. however, there were a few studies about a generalized analysis on throughput and channel utilization for successful transmissions in multi-rate wlan systems with different frame parameters and channel errors. in particular, the performance anomaly problem of the multi-rate wlans still needs to be solved. we propose a more generalized mathematical model for each station with a different data transmission time and mathematically analyze the throughput and channel utilization for successful transmission in error-prone multi-rate wlans. moreover, we propose a contention window size adjustment scheme and a payload adjustment scheme to resolve the well-known performance anomaly problem in multi-rate wlans by achieving temporal fairness. numerical results show that the proposed scheme is very effective in achieving temporal fairness.
target identification and distributed cooperative control of sensor networks. with the advances in communication and embedded systems, the monitoring and/or controlling of physical phenomena that span over wide spatial area have been attempted with deployment of a network of inexpensive and miniature sensors. in this paper, we focus on the automated sensor management for target identification at the application layer. the sensor management is formulated using graph grammar that reactively control the states of the sensors based on their proximity to the target and the states of their neighboring sensors. target identification, on the other hand, concerns the estimation of the target's kinematics and attributes. the current practice is often formulated as finding the conditional probability of the target type on features derived from the sensor measurements with statistical pattern recognition. however, due to lack of training data, we demonstrate that the use of semantic latent indexing and stochastic approximation techniques, borrowed from the computer science community, is a more powerful method for sensor management and target identification.