waashk/dblp huggingface dataset:
analytical and experimental comparison of packet loss recovery methods based on amr-wb for voip. forward error control (fec) and multiple description coding (mdc) are two classical techniques to resist packet loss for voice over ip (voip). amr-wb codec has been standardized for wideband speech conversational applications and has widely potential applications in the migration of wireless or wired networks toward a single converged ip network. however, how to choose the optimal fec or mdc for amr-wb in different loss rate conditions is an unexplored option. in this paper, we compare the performance of different fec and mdc techniques for amr-wb codec both analytically and experimentally. based on the comparison results, some practical configurations of fec and mdc for amr-wb codec are obtained.
bit loading for mimo with statistical channel information at the transmitter and zf receivers. for single-user mimo communication with uncoded and coded qam signals, we propose bit and power loading schemes that rely only on channel distribution information at the transmitter. to that end, we develop the relationship between the average bit error probability at the output of a zf linear receiver and the bit rates and powers allocated at the transmitter. this relationship, and the fact that a zf receiver decouples the mimo parallel channels, allow leveraging bit loading algorithms already existing in the literature. we solve dual bit rate maximization and power minimization problems and present performance results that illustrate the gains of the proposed scheme with respect to a non-optimized transmission.
distributed scalable multi-target tracking with a wireless sensor network. we propose a novel technique for tracking multiple co-dependently maneuvering targets using a wireless sensor network. we consider the scenario where the targets carry radio frequency identification (rfid) tags and the sensors in the network measure some metric of the radio transmissions from these tags, like the received signal strength, the time of arrival or the angle of arrival. these measurements are then processed by a sampling importance re-sampling particle filter for tracking. while such a set-up is now fairly standard in literature, the novel aspect of our algorithm is that it exploits the co-dependencies in the motion of the targets via a fully distributed and tractable particle filter bank. we thereby extract a significant "diversity gain", while allowing the network to scale seamlessly to a large tracking region. in particular, we avoid the pitfalls of network congestion and severely shortened battery lifetimes that plague currently used procedures that implement the filter on the joint multi-target probability density.
performance evaluation of interactive data services under sharing and preemptive scheduling disciplines. as specified by the third-generation (3g) wireless networks such as the universal mobile telecommunication system (umts), interactive data services, such as web browsing, voice messaging, and file transfer, represent a major service class in operation nowadays. in this paper, we develop an analytical approach to evaluate the performance of interactive data services under sharing and preemptive scheduling. specifically, we take into account user interactions in data sessions and the heavy-tailed data file size. both the mean and the standard deviation of data transfer delay are investigated for the two representative scheduling disciplines. numerical results are given to show the validity of the evaluation approach and the impact of the on-off user behavior under the scheduling disciplines.
stateful scheduling with network coding for roadside-to-vehicle communication. in urban areas such as street blocks, media-rich services are delivering to moving vehicles through access points (aps) deployed on the roadside. to increase the capacity of wireless links for these services, a roadside-to-vehicle communication system based on a novel stateful scheduling with network coding (ssnc) strategy is proposed. a major innovation of ssnc is that it enables the scheduling on the roadside ap to fully utilize the states of received data from vehicles for an enhanced performance. furthermore, a set of mechanisms are proposed to ensure reliable transmission in such highly dynamic and error-prone wireless channels. extensive simulations show that ssnc achieves an increased throughput gain between 1.2 and 2.0 at various conditions.
energy saving mac for mimo systems. over the last decade multiple-input and multiple-output (mimo) systems have been actively researched and started to be deployed in wireless communications owing to the significant increase in channel capacity. in this paper, we propose an energy saving mac protocol in mimo (esmacm) systems by focusing on energy efficiency instead of capacity maximization. esmacm considers the energy consumption together with the tradeoff between reliability (i.e., diversity) and throughput (i.e., multiplexing gain), and dynamically chooses an appropriate number of antennas for transmission. in computing the total energy consumption, esmacm counts circuit energy as well as transmission energy. naturally the circuit energy consumption is directly proportional to the number of active antennas. through numerical analysis, we confirm that our esmacm considerably saves energy consumption compared to conventional capacity maximization schemes that use a fixed number of mimo channels, for a given outage constraint. our finding is that the capacity maximizing communication which possibly can be regarded best in terms of energy efficiency gives a different solution from the energy minimizing communication.
constructions on 2d wavelength-time codes for cdma fiber-optic systems. in this paper, we study a new class of two-dimensional codes, here called multi-level prime codes, with expanded code cardinality by relaxing the maximum cross-correlation function to any arbitrary positive integer n. besides having asymptotically optimal cardinality and zero autocorrelation sidelobes, these multi-level prime codes can be partitioned into n levels, such that the cross-correlation function between any two code matrices in level l is at most l, where l ∈ [1, n]. the performance of the new codes in an optical code-division multiple-access system with hard-limiting detection is analyzed. our results show that the unique partition property of the multi-level prime codes allows the trade-off between code cardinality and performance for meeting different system requirements, such as capacity and throughput.
atomic distributed semaphores for accessing networked data. distributed hash tables (dhts), based on consistent hashing, offer efficient lookup services for decentralized distributed systems. dhts operate efficiently to handle large number of network nodes with continual node arrivals, departures, and failures. upon addressing the crucial issues of communication efficiency and offering load balancing in dynamic networking environments, dhts are the essential components for building structured peer-to-peer (p2p) overlay networks. although structured overlays improve data availability and consistency, they do not provide strong semantics on distributed data mutual exclusion operations. for a robust network operating system, it is essential to provide atomic data access semantic services. in this paper, a distributed semaphore (disem) mechanism is proposed, and it is designed on top of a dynamic structured overlay. the proposed design circumvents the availability and consistency issues. independent of any underlying overlay algorithms, disem provides a tunable level of data availability and consistency, while offering fault tolerance and reliable delivery services. a testbed prototype has been implemented to validate the mutual exclusiveness of networked replicas under different traffic loadings. the measured results indicate that disem offers high mutual exclusive access rates under different networking conditions.
comparison of analog and digital relay methods with network coding for wireless multicast. we study wireless multicasting from two sources to two destinations with the assistance of a single half-duplex relay. the objective is to evaluate the throughput and error performance of different analog and digital relay schemes with linear network coding at the relay. the analog relay node forwards either a scaled version of the received signal to the destinations, or alternatively, first filters the received signals to generate a linear minimum mean squared error (mmse) estimate, which is subsequently forwarded. the digital relay scheme first detects the source transmissions, combines the packets with a network code, and forwards the resulting symbols to the destinations. for all schemes the destinations recover the source and relay signals by first applying linear mmse filters, followed by decoding of the source bits. the performance of the schemes are compared in terms of normalized throughput (bits per channel use accounting for the delay due to the relay) and uncoded error probability, given a normalized power constraint. both narrowband and wide-band transmission schemes are considered. our results show that the analog relay schemes outperform the digital network coding scheme with respect to both throughput and error probability because of error propagation through the relay. numerical results are presented, which illustrate throughput-reliability trade-offs for all schemes considered.
efficient load-balanced ip routing scheme based on shortest paths in hose model. this paper proposes a simple shortest-path-based load-balanced ip routing scheme for the hose model. the proposed scheme is an extension of the smart-ospf scheme. the proposed scheme, the same as s-ospf, splits traffic demand only at source edge nodes and transmits the traffic along the shortest path routes. in s-ospf, the split ratios are determined for each source-destination edge node pair by assuming that the traffic demand between all source-destination edge node pairs are known, in other words, the exact traffic matrix is completely given. on the other hand, in the proposed scheme, we assume the use of the hose model; in this model, only the total amount of traffic that a node injects into the network and the total amount of traffic it receives from the network are known. any extension of the linear programming (lp) formulation to suit the hose model cannot be solved as a simple lp problem, because the traffic matrix is not known. by introducing a duality theorem, we successfully formulate our problem as an lp formulation that can be easily solved yielding the desired split ratios. numerical results show that the proposed scheme dramatically reduces the network congestion ratio compared to the classical shortest path routing scheme and it provides performance close to that provided by the sophisticated traffic-engineering (te) scheme of multi-protocol label switching (mpls)-te.
mean time to loss of lock and average switching rate of an automatic frequency control loop with an interferer and noise in a fading channel. the performance of an automatic frequency control (afc) loop in a noisy fading channel when an interference signal is present at the input of the afc is studied. independent non-identically distributed (i.n.d.) channels with rayleigh and rician fading are considered. the received signals are assumed to be narrowband and linearly modulated while the analysis is applicable to the unmodulated scenario as well. closed-form expressions and integral form formulas are derived for the mean time to loss of lock (mtll) and the average switching rate (asr) of an afc. numerical examples are provided to illustrate the effects of noise and slow fading on the performance of an afc in the presence of an interferer. it is shown that in some scenarios, an afc has a better performance if the desired signal is corrupted by more noise.
cooperative cognitive radio with priority queueing analysis. in this paper, we model the hierarchical structures inherent in cognitive radio networks as the priority queueing system in which primary users interact with the highest priority and secondary users belong to the lowest priority class. in a m/g/1 system containing one primary user and multiple secondary users, we obtain analytical forms of delay and throughput for different users with the function of traffic and channel conditions. based on the analysis, the secondary user is considered to act as a relaying terminal to assist the primary communication by adopting an amplify-and-forward tdma protocol. cooperative diversity gains are examined next and the benefits of the secondary: improvement of throughput, is discussed with respect of the primary traffic.
a flexible antenna selection scheme for 60 ghz multi-antenna systems using interleaved adcs. we present a new scheme for maximizing the signal-to-noise ratio (snr) in wideband multi-antenna receivers that employ time-interleaved analog-to-digital converters (adcs). current wideband receivers interleave a fixed number of slower adcs into one fast adc and assign this latter to one antenna according to an antenna selection algorithm. however, this does not always guarantee an optimal trade-off between thermal noise and quantization noise. this results in an overall snr that is lower than what could be obtained with the same number of adcs, assigned in a more optimal way. therefore, we propose to adjust the number of slower adcs assigned to a certain fast, interleaved adc dynamically, according to the snr of every individual antenna. our proposed algorithm can be implemented at the expense of a very limited hardware complexity increase. the snr gain of our new scheme can exceed 7 db, depending on channel conditions and adc specifications.
on the use of an adsl2+ testbed for video quality assessment. in this paper we share our experience in building an adsl video delivery test-bed. as a result, we are able to measure the impact of important parameters such as the loop length, the presence of background traffic and line protection against transmission errors on video quality. we show that although these access technologies promise a broadband pipe and low delay communication, a careful configuration of line parameters is paramount to achieve optimal access and is needed for the success of multimedia triple play (3p) services. we particularly analyze the delay, jitter, packet loss and bitrate consumption obtained from real adsl measurements. these results are an important step towards understanding the adequate deployment of such services. as a special case, we study the effect of repetitive noise on sdtv.
effective capacity maximization in multi-antenna channels with covariance feedback. the optimal transmit strategies of single-user multi-antenna systems with respect to average capacity maximization are well understood. however, the performance measure does neglect delay aspects which are important for higher layer design. therefore, we consider the maximization of the effective capacity in a single-user multi-antenna system with covariance knowledge. the optimal transmit strategy is derived and the properties as a function of the decay-rate requirement of the buffer occupancy are analyzed. in particular, we show that the larger the decay-rate requirement, the smaller the beamforming optimality range, i.e., the more spatial eigenmodes are activated. this behavior is illustrated by numerical simulations and explained by the channel hardening effect.
quality of service in 802.11 networks: modeling and experimental evaluation. this paper compares the theoretical and the experimental throughput of an 802.11 adhoc network implementing quality of service (qos) mechanisms. the theoretical model provides the throughput of each access category (ac) of each node in saturated and non-saturated traffic conditions. the experimental setup is described in detail to enable the reproduction of the presented measurements. this setup adopts the widely used multiband atheros driver forwireless fidelity (madwifi), which, however, provides the qos option for centralized operations only. hence, this study describes the adjustments to the madwifi source code that guarantee the control of the qos parameters in adhoc mode.
performance analysis of maximum likelihood decode and forward cooperative systems in rayleigh fading. the bit error rate (ber) performance analysis of maximum-likelihood (ml) based decode and forward (df) cooperative diversity systems has been a subject of considerable interest. exact analysis of ml-df transmission has been considered a challenging problem due to the nonlinear characteristic of the ml detector. in this paper, we provide exact expressions for the ber of ml-df cooperative systems employing a single relay. we extend these results to the case of multiple relays for the piecewise linear (pl) combiner, that is known to be a close approximation of the ml detector. this is done by using a novel theory of conditionally gaussian random variables. by expressing the ml decision variable in terms of functions of conditionally gaussian variables, exact expressions for the ber of the ml-df system are obtained. through simulation results, we verify the validity of the derived analytical expressions.
idc: an energy efficient communication scheme for connected mobile platforms. mobile platforms (e.g. laptops) offer ubiquitous network connectivity through its wireless communication interfaces, with most of usage models driven by always-on communication activities. however this in turn creates significant power challenges as the battery life is a critical resource for all mobile platforms. while the communication device itself consumes a relatively small portion of the total power, the impact of communication on the overall platform power is significant, due to the non-deterministic nature of the network traffic, which tends to keep the platform busy more than necessary. in this paper, we extensively investigate characteristics of various real-world network-centric workloads, e.g., voip, web browsing, etc., and their impact on the mobile platform in terms of power consumption and energy. based on the understandings, we propose, implement and evaluate an interrupt /dma (direct memory access) coalescing (idc) scheme at the wireless network interface card (nic). this scheme effectively reduces platform wakeups due to incoming network traffic, another advantage of the scheme is that it requires only nic modification at the receiving node, and is transparent to the user and the network. using a commercial nic with a laptop testing platform, we evaluate the power savings and performance impact of our proposed scheme. the measurements show that our scheme achieves significant platform power saving, around 25% of platform components, without impacting user experience.
a progressive chaotic mpeg-4 video encryption scheme for wireless networks. the intrinsic vulnerabilities of wireless networks place a great demand on efficient encryption techniques.with the proliferation of video streaming applications, the need for multimedia encryption techniques is becoming of utmost importance. this paper presents a scalable coding scheme for multimedia transmission over wireless networks. the proposed approach unifies the compression and encryption functionalities using the wavelet transform and chaotic functions to build up random permutations. the major advantage of our chaotic multimedia encryption process is that a client can access to multiple resolutions of the streamed video. these resolutions vary according to the security level of the client as well as the networking and processing capabilities. a set of simulations have also been carried out to assess the performance of the proposed coding scheme in terms of security, compression ratio, and error resilience.
an analytical model for the contention access period of the slotted ieee 802.15.4 with service differentiation. the ieee 802.15.4 standard is poised to become the global standard for low data rate, low energy consumption wireless sensor networks (wsn). by assigning the same sets of contention access parameters for all data frames and nodes, the contention access period (cap) of the slotted ieee 802.15.4 medium access control (mac) currently provides a priorityindependent channel access functionality and no service diiterentiation. several recent wsn applications such as wireless body sensor networks, however, may require service dilterentiation and traf6e prioritization support to accommodate potential highpriority traffic (e.g., alarms or emergency alerts). by allowing dilterent sets of access parameters and data frame lengths for differentpriority classes, this paper develops a markov-chain-based analytical model of the cap of the ieee 802.15.4 mac with service dilterentiatlon, under unsaturated traffic conditions. in particular, given two priority classes, our analytical model is used to evaluate the performance of a simple, yet eitective, contentionwindow-based service dilterentiation strategy, in terms of the resulting throughput, average frame service time and access priority for each priority class. the accuracy of the analytical model is validated by extensive ns-2 simulation.
degrees of freedom and sum rate maximization for two mutually interfering broadcast channels. in this paper, we derive a precise expression of spatial degrees of freedom (dof) for two mutually interfering broadcast channels (ifbc) as a function of arbitrary numbers of transmit antennas and users. the lower bound on the dof is obtained by showing that the zero-forcing solution suffices to achieve all the dof. also, the upper bound which coincides with the lower bound is shown using jafar's earlier work. from the derived result, we observe that disabling receive cooperation of the mimo interference channel causes the dof loss. additionally, we propose a linear precoding scheme for the ifbc by extending one designed for broadcast channels with an aim of maximizing the sum rate performance. we utilize the fact that the precoding matrices in stationary point always satisfy the zero-gradient condition. our result is confirmed through numerical simulations on the sum rate performance of the proposed precoding technique.
authentication in 802.11 lans using a covert side channel. we present a covert side channel technique that uses the 802.11 mac rate switching protocol as cover for covert authentication messages. covert authentication prevents an attacker from knowing when a user is authenticating and protects user credentials from malicious software attacks. similar to port knocking, a remote client sends authentication messages to an access point in order to access a protected service. the technique uses a one-time password algorithm to protect against replay attacks. we investigate how the covert side channel affects node throughput in mobile and non-mobile scenarios. we also investigate the covertness of the covert side channel using standardized entropy. the results show that the performance impact is minimal and increases slightly as the authentication frequency increases. we further show that we can authenticate with 100% accuracy with minimal impact on rate switching entropy.
fast connected dominating set construction in mobile ad hoc networks. the connected dominating set (cds) has been commonly used for routing and broadcast in mobile ad hoc networks (manets). considering the applications of manets, it is generally preferred that the cds protocol not only creates cds of small size, incurs less communication and computational overheads, adapts to the nodal mobility, but also generates cds as quickly as possible. unfortunately, none of the existing cds protocols possesses all of these desirable properties. in this paper, we propose an algorithm to rapidly grow a cds tree from an initiator. by incorporating this algorithm with the multi-initiator cds protocol, we have created the cds protocol for manets which enjoys all the aforementioned desirable properties. the simulation results validate that our proposed protocol achieves its design goals. in addition, an analytical model is provided that can accurately estimate the convergence time required by our proposed cds protocol.