waashk/dblp huggingface dataset:
multi-dimensional nested lattice quantization for wyner-ziv coding. in this paper, we consider the coding of an independent and identically distributed (i.i.d.) gaussian source with side information available only at the decoder in the form of a noisy version of the source to be encoded. this problem is known as wyner-ziv coding in literature. in this paper, we propose concrete implementation by using the strategy of multi-dimensional nested lattice quantization (nlq). by investigating various lattices in the dimensions considered, we give some analysis on how lattice properties affect performance. we also propose a method on choosing good coarse lattices in multiple dimensions. by introducing scale factors, we examine the relationship between distortion and scale factor for various rates. as dimension increases to eight and twenty-four, we obtain distortion performance close to the wyner-ziv limit. meanwhile, our scheme is simple without causing long delay and large storage, which is suitable for sensor networks.
prototyping of a pass-band chaos-based cdma system in fpga technology. this paper presents the theoretical analysis, design and fpga implementation of a pass-band chaos-based cdma system. the system uses a digital modulation technique called chaos-phase-shift-keying (cpsk) in a complex form, where chaotic sequences are used for spreading digital messages. conventional multi-rate signal processing techniques are employed for carrier modulation and demodulation, which changed the structure of the theoretical model of the analysed system. the model of a pass-band additive white gaussian noise channel is also constructed. the system is implemented in altera stratix ii ep2s180 dsp development board. the fpga design flow is carried out using alter dsp builder integrated into mathworks simulink algorithm development environment. the ber characteristics obtained on the prototype and simulation confirmed the theoretical findings.
trust-based data disclosure in sensor networks. in sensor networks, privacy can be addressed in different levels of the network stack and at different points of the information flow. this paper presents an application level scheme for controlling information disclosure at the points of data capture. the scheme includes a trust model for facilitating in-network privacy decisions. the trust model exploits the pre-deployment knowledge on the network topology and the information flows, and combines aspects from alternative approaches on trust establishment on common evaluation metrics, in order to allow for flexibility in the trust establishment process. the trust assigned to each data requestor is used to determine if the data or only a sample of it will be disclosed, or if the request will be rejected. the scheme allows the use of various mechanisms, including negative surveys, for publishing samples of data to partially trusted requestors. the proposed scheme has been validated through simulation. the results and analysis demonstrate its effectiveness in managing trust relationships and data disclosure operations.
algebraic reduction for the golden code. in this paper we introduce a new right preprocessing method for the decoding of 2×2 algebraic space-time codes, called algebraic reduction, which exploits the multiplicative structure of the code. the principle of the new reduction is to absorb part of the channel into the code, by approximating the channel matrix with an element of the maximal order of the code algebra. we prove that algebraic reduction attains the receive diversity when followed by a simple zero-forcing (zf) detection. simulation results for the golden code show that using minimum mean squared error generalized decision feedback equalization (mmse-gdfe left preprocessing), algebraic reduction with simple zf detection has a loss of only 3db with respect to optimal decoding.
joint power allocation and scheduling of multi-antenna ofdm system in broadcast channel. this paper considers the general multiuser down-link scheduling problem and power minimization with multiuser rate constraints. we present joint user selection algorithms for dpc, zf-dpc, zfbf and tdma for multi-antenna ofdm system in broadcast channels, and we also present a practical waterfilling solution in this paper. by the selected users with the consideration of fairness, we derive the power optimization algorithm with multiuser rate constraints. simulation results show that the presented user scheduling algorithms and power minimization algorithms can achieve good power performance. meanwhile, simulation results also show that the scheduling algorithm can guarantee fairness.
matched spectral-null code with run-length limitation for optical recording channels. high track-density recording and multi-layer recording have been investigated for large capacity optical recording discs. in this case, the recorded data will be reproduced under the low signal-to-noise ratio (snr) condition due to crosstalk from the adjacent tracks or the other layers, and robust data detection will be required. in this paper, a novel matched spectral-null (msn) code providing the property of run-length limitation (rll) was described considering the optical recording channels. trellis coded partial response maximum likelihood (tcprml) employing the msn code with rll was also proposed for the data detection method enhancing the minimum euclidian distance. the detection performance was estimated through the simulation model, which emulates the optical recording channels based on the blu-ray disc (bd) specification.
successive par reduction in (mimo) ofdm. a successive scheme for par reduction in (mimo/ siso) ofdm is presented, where k (parallel/consecutive) ofdm frames are treated jointly. employing reed-solomon codes further candidate ofdm frames are generated and assessed successively; the currently best k are selected for possible transmission. the procedure stops if (i) all k best frames stay below a given tolerable par limit, or (ii) the maximally allowed number of candidates is exhausted. thereby complexity compared to other par reduction schemes can be reduced significantly. analytical derivations show that for par limits in the region of the "critical par" value ξcrit = log(d), with d being the number of carriers, the average number candidates is close to euler's number e = 2.71828..., which is particularly low.
cross-layer optimized routing for wireless sensor networks using dynamic programming. in this paper, we study the joint optimization problem on channel coding, power allocation, and route planning in wireless sensor networks (wsn) using dynamic programming (dp). each sensor node has multiple antennas and applies orthogonal space time block codes (ostbc) in order to improve the transmission reliability. a decode-and-forward protocol is adopted to relay the signals. the objective function is to determine the packet forwarding route that has the maximum successful transmission rate (str) subject to the source-to-destination (s-d) energy consumption constraint. specifically, we cast this energy and quality-of-service (qos) aware packet forwarding problem into the framework of dp, such that adaptive power allocation can be jointly realized at each sensor node. state space partition techniques and state aggregation approximation architecture are introduced to derive the value function. simulation results show that the proposed protocols significantly outperform classical routing algorithms, especially when the energy constraint becomes stringent.
a dynamic ultrapeers selection policy for collaborative virtual environments over mobile ad hoc networks. with the rapid developments in technology, mobile collaborative virtual environments (mcves) have become an unavoidable application in area such as military training, health, and education. unfortunately, as 1the number of users grows, nodes may easily become overloaded as they process messages from other nodes. most of the existing ultrapeer systems are confined to wired network environments and thus preclude collaboration while users are mobile. in this paper, a gnutella ultrapeer system gus to improve the performance of mcves is proposed. in manets, a reconfiguration process is frequently required in the ultrapeer system due to node mobility. in addition, the number of ultrapeers must be well dispersed throughout the overlay network. to address these problems, we adopt a novel selection approach in which we create a hierarchical overlay network based on the cve profile in order to reflect the user's interest in the virtual environment. we then perform a dynamic ultrapeer election based on a score measurement that combines the network behaviors and the user behaviors in the ve. thus, not every change in the network topology will entail an immediate ultrapeer system reconfiguration. simulation results indicate that the proposed gus is more efficient than popular ultrapeer topologies in several important scenarios.
a multihoming support scheme with localized shim protocol in proxy mobile ipv6. this paper proposes an enhanced multihoming support scheme based on combining ideas from both the shim and proxy mobile ipv6 (pmipv6) protocols. the proposed scheme not only resolves the multihoming support problems with the current pmipv6, but also provides mobility support to the shim protocol. in the proposed scheme, the shim protocol is locally used between a multihomed mobile node (mn) and the local mobility anchor (lma) in the pmipv6 domain. a flow distribution scheme with the shim locator preferences is proposed to provide flexible multihoming. simulation results show that the pmipv6 combined with the localized shim protocol can support both mobility and multihoming efficiently.
salsa: super-peer assisted live streaming architecture. in p2p live streaming, free-riders which do not upload data but only download them are still present. since a greater number of viewers can generate more profit, the streaming server wants to serve the free-riders also. in this paper, we have proposed a novel p2p live streaming system, called super-peer assisted live streaming architecture (salsa). in salsa, super-peers, which have high upload bandwidth and serve many free-riders, are eligible to receive an incentive reward that is the ability to watch high quality videos. the server places high-quality-view-tickets at auction to make the super-peers serve free-riders more efficiently. we have proposed novel auction mechanisms and a heuristic algorithm. the simulation results showed that the proposed scheme has comparable performance to the optimal form and are able to differentiate the super-peers' video quality commensurate with their contribution level.
energy savings for wireless terminals through smart vertical handover. this paper optimizes handover decisions between wlan (802.11) and wimax (802.16e) standards, for both uplink and downlink data transmission. the handover becomes part of a cross-layer approach controlling several knobs (air interface parameters or platform settings) in order to reduce the terminal power consumption. the first step is to derive detailed power and performance models for both standards, in order to correctly evaluate the opportunity of a handover. this includes channel fading fluctuations, extraction of mac-level behavior and packet error rates, and overall power consumption from the wireless platform. such models enable first optimal single-standard power-throughput trade-offs, that will be used as reference points before adding the handover possibility in order to assess its specific gain. the second step is the design of a handover controller that selects the network with the lowest expected power for the required rate. the proposed mechanism is based on regular scanning of both networks. it computes the expected energy in order to send a given amount of data over each network, taking handover cost into account, and selects the most appropriate one. based on a software-defined radio platform and a typical channel coherence time of one second, simulations demonstrate a power saving factor up to 2.5 as a function of the scenario, compared to a single-standard system that is already cross-layer optimized. this illustrates the large gain that is available, besides the handover advantage in terms of improved connectivity.
differential (de)modulation for orthogonal bi-pulse noncoherent uwb. in this paper, we propose a novel noncoherent uwb (de)modulation system, which uses a pair of orthogonal pulses to convey information symbols. same as the original noncoherent uwb [1], our approach remains operational even without timing and channel estimation. moreover, due to the orthogonality between the received waveforms of the pulse pair, our approach results in a differential demodulator. this means that our approach does not need viterbi decoding which is required by [1], even in the presence of timing error. simulations are also carried out to corroborate our theoretical analysis.
maximizing the sum rate in symmetric networks of interfering links. we consider the power optimization problem of maximizing the sum rate of a symmetric network of interfering links in gaussian noise. all transmitters have an average transmit power constraint, the same for all transmitters. this problem has application to dsl, as well as wireless networks. we solve this nonconvex problem by indentifying some underlying convex structure. in particular, we characterize the maximum sum rate of the network, and show that there are essentially two possible states at the optimal solution depending on the cross-gain (√ε) between the links, and/or the average power constraint: the first is a wideband (wb) state, in which all links interfere with each other, and the second is a frequency division multiplexing (fdm) state, in which all links operate in orthogonal frequency bands. the fdm state is optimal if the cross-gain between the links is above 1/√2. if √ε < 1/√2, then fdm is still optimal provided the snr of the links is sufficiently high. with √ε < 1/√2, the wb state occurs when the snr is low, but as we increase the snr from low to high, there is a smooth transition from the wb state to the fdm state: for intermediate snr values, the optimal configuration is a mixture, with some fraction of the bandwidth in the wb state, and the other fraction in the fdm state. we also consider an alternative formulation in which the power is mandated to be frequency flat. in this formulation, the optimal configuration is either all links at full power, or just one link at full power. in this setting, there is an abrupt phase transition between these two states.
an m-sequence based steganography model for voice over ip. differing from applying steganography on storage cover media, steganography on voice over ip (voip) must often delicately balance between providing adequate security and maintaining low latency for real-time services. this paper presents a novel real-time steganography model for voip that aims at providing good security for secret messages without sacrificing real-time performance. we achieve this goal by employing the well-known least-significant-bits (lsb) substitution approach to provide a reasonable tradeoff between the adequate information hiding requirement (good security and sufficient capacity) and the low latency requirement for voip. further, we incorporate the m-sequence technique to eliminate the correlation among secret messages to resist the statistical detection based on the fact that the distribution of the lsbs in the stego-speech is not uniform and to provide a short-term security protection of secret messages. to accurately recover secret messages at the receiver side, we design a synchronization mechanism based on the rsa key agreement and the synchronized sequence transmission using techniques of the protocol steganography, which can effectively enhance the flexibility of the covert communication system and be extended to other steganography schemes based on real-time systems. we evaluate the effectiveness of our model with itu-t g.729a as the codec of the cover speech in stegtalk, a covert communication system based on voip. the experimental results demonstrate that our technique provides good security and transparency for transmitting secret messages while adequately meeting the real-time requirement of voip.
evaluation of the extremely low block error rate of irregular ldpc codes. in this paper, we attempt to evaluate irregular ldpc code performance at the high snr region using the importance sampling (is) approach in conjunction with primary-trapping-set identification. results have indicated that our proposed is scheme can produce speed-up gains up to 3.9 × 109 times compared with monte carlo simulations.
reduced feedback designs for sdma-ofdma systems. in sdma-ofdma wireless communication systems, the feedback load increases with the number of users, subcarriers and antennas in the cell. in this paper, we propose two efficient reduced feedback algorithms by selecting the clusters at the user side. for each cluster, we select the users according to their norm and their orthogonality. we evaluate the performance of the user selection algorithms considering the quantization effect. we also design a specific codebook design to quantize csi for the proposed criterion.
energy-efficient itinerary planning for mobile agents in wireless sensor networks. compared to conventional wireless sensor networks (wsns) that are operated based on the client-server computing model, mobile agent (ma) systems provide new capabilities for energy-efficient data dissemination by flexibly planning its itinerary for facilitating agent based data collection and aggregation. it has been known that finding the optimal itinerary is np-hard and is still an open area of research. in this paper, we consider the impact of both data aggregation and energy-efficiency in sensor networks itinerary selection, we propose an itinerary energy minimum for first-source-selection (iemf) algorithm, as well as the itinerary energy minimum algorithm (iema), the iterative version of iemf. our simulation experiments show that iemf provides higher energy efficiency and lower delay compared to existing solutions, and iema outperforms iemf with some moderate increase in computation complexity.
complexity reduced soft-in soft-out sphere detection based on search tuples. depth-first tree search algorithms provide a promising approach to solve the detection problems in mimo systems. realizations like the list sphere detector (lsd) or the single tree search (sts) enable near max-log detection at reduced but still high complexity. in this paper we show how the complexity of list sphere detection can be significantly reduced by mmse preprocessing in combination with a novel unbiased and separated candidate handling. therefor, we propose an extension of the lsd by search tuples. without any performance loss, the resulting tuple search (ts) algorithm enables major reduction of sphere sizes and enables moreover a detection with flexible performance respectively complexity. avoiding loss of useful status information, caused by unbiased mmse preprocessing or small candidate storage, is provided by a novel matched candidate determination, leading also to reduced hardware complexity. the combination of these methods enable high-performance soft-out detection at very low complexity. more specifically, this enables a performance improvement up to 1 db at half the complexity of common lsd or sts algorithms.
speech quality while roaming in next generation networks. in ngns, handovers between different wireless access technologies provide seamless roaming during voice calls. the resulting speech quality depends on the audio bandwidth of the speech codecs used in the respective networks, as well as on degradations resulting from the handover, coding, and packet loss. we present the results of four listening experiments where speech quality is quantified as a function of network and codec characteristics, and compare them to estimations obtained from instrumental models. the results show when and under which circumstances a network handover and/or codec changeover should be scheduled in order to obtain better speech quality. this is important for the development of high-quality roaming strategies.
idle channel time estimation in multi-hop wireless networks. this paper presents a theoretical estimation for idle channel time in a multi-hop environment. idle channel time is the time proportion of a node during which the channel state is idle. thus, it can be used to evaluate the available bandwidth. major related work considers a cross-layer model, where the idle channel time measure is available at the mac layer, but it is rarely implemented. furthermore, this measure is not very flexible: it cannot differentiate the traffic's priorities and it works under the hypothesis that flows are strictly policed. estimating instead of measuring the idle channel time prevents these drawbacks. this estimation is computed in three steps by (1) calculating the idle channel time bounds, (2) evaluating the probability of a given idle channel time value, (3) computing the expected value of this distribution and deducing the average idle channel time. we show by simulation that our estimation is accurate.
combining hidden markov models for improved anomaly detection. in host-based intrusion detection systems (hids), anomaly detection involves monitoring for significant deviations from normal system behavior. hidden markov models (hmms) have been shown to provide a high level performance for detecting anomalies in sequences of system calls to the operating system kernel. although the number of hidden states is a critical parameter for hmm performance, it is often chosen heuristically or empirically, by selecting the single value that provides the best performance on training data. however, this single best hmm does not typically provide a high level of performance over the entire detection space. this paper presents a multiple-hmms approach, where each hmm is trained using a different number of hidden states, and where hmm responses are combined in the receiver operating characteristics (roc) space according to the maximum realizable roc (mrroc) technique. the performance of this approach is compared favorably to that of a single best hmm and to a traditional sequence matching technique called stide, using different synthetic hids data sets. results indicate that this approach provides a higher level of performance over a wide range of training set sizes with various alphabet sizes and irregularity indices, and different anomaly sizes, without a significant computational and storage overhead.
interferer classification, channel selection and transmission adaptation for wireless sensor networks. wireless sensor networks (wsns) are being increasingly deployed in office blocks or residential areas for commercial applications, such as home automation, meter reading, surveillance, among others. at these locations, the wsns experience interference in the 2.4ghz unlicensed band due to wireless lans (wlans) and commercial microwave devices, leading up to 92% packet losses. in this paper, an algorithmic framework is proposed, that allows the sensor nodes to identify the type of the interferer and its operational channel, so that the former may adapt their own transmission to reduce packet losses in the network. our proposed interference classification approach comprises of an (i) offline measurement of the spectral characteristics of the wlan and microwave devices to obtain a reference spectrum shape, and (ii) matching the observed spectral pattern during network operation with the stored reference shape the knowledge of the interferer characteristics is then leveraged by the sensor nodes to decide their transmission channel, packet scheduling times and sleep-awake cycles. results reveal that our approach incurs up to 50-70% energy savings in the wsn, by reducing interference related packet losses.