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Impact of network routing on the end-to-end transmission quality of cellular and PCS connections

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1998年第4期47卷 1227-1233页

作者： Dimolitsas, S Corcoran, FL Ravishankar, C Comsat Labs Clarksburg MD 20871 USA

Long-distance and especially international calls involve an increasing number of multilink circuits of cellular, personal communications, mobile satellite, and public switched telephone network (PSTN)-type connections incorporating a variety of speech coding devices, In particular, the rapid growth of cellular communications and the impeding emergence of personal communication systems (PCS's) has highlighted the need to characterize the quality of end-to-end connections when cellular and PCS terminals are connected over the PSTN. At the same time, the nonlinear nature of low-rate parametric speech coding has rendered unsuitable known analytical methods for estimating end-to-end quality of interconnected networks. Instead, quantification of transmission performance requires direct subjective evaluation of the pertinent connections of interest. In this paper, the quality of North American, Japanese, and European digital cellular and PCS terminals is quantified when these are interconnected using 16-kb/s low-delay code-excited linear prediction (LD-CELP) and 32-kb/s adaptive differential pulse code modulation (ADPCM) facilities. From these assessments, it can be concluded that digital cellular networks may meet end-to-end transmission planning criteria when interconnected with the switched network as long as calls are terminated to a wired terminal.

关键词： adaptive codes adaptive modulation cellular radio delays differential pulse code modulation digital radio internetworking linear predictive coding mobile satellite communication personal communication networks speech coding telecommunication network plan cellular radio Personal communication networks end-to-end transfer differential pulse code modulation Information Network Transmission Characteristics Digital radio mobile satellite communication Linear Prediction coding Network routing adaptive coding speech coding Personal communication systems adaptive modulation internetworking

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Space-time code selection for transmit antenna diversity systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2008年第1期57卷 620-629页

作者： Mavares, Dimas T. Torres, Rafael P. Univ Polytech Antonio Jose Sucre UNEXPO Lara 3001 Venezuela Univ Cantabria Dept Commun Engn Cantabria 39005 Spain

In this correspondence, a space-time code selection approach for transmit antenna diversity (TAD) systems is proposed. The receiver compares the equivalent single-input-single-output channel envelopes with a set of predetermined threshold levels, decides the antennas to be used, and sends this information to the transmitter, which adjusts the space-time code to the number of selected antennas using a small amount of feedback information. Threshold levels are found out-of-line based on the Doppler frequency in such a way that channel state information outdate at the transmitter is taken into account. Analysis and simulation results show that the system performs well for a wide range of Doppler frequencies, outperforming transmit antenna selection techniques and adaptive TAD systems.

关键词： adaptive coding adaptive transmission diversity methods multiple-input-multiple-output (MIMO) systems space-time coding transmit antenna diversity (TAD) Wireless local area network (LAN)

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adaptive Spectral Transform for Wavelet-Based Color Image Compression

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2011年第7期21卷 983-992页

作者： Bayazit, Ulug Istanbul Tech Univ Dept Comp Engn TR-34469 Istanbul Turkey

Since different regions of a color image generally exhibit different spectral characteristics, the energy compaction of applying a single spectral transform to all regions is largely inefficient from a compression perspective. Thus, it is proposed that different subsets of wavelet coefficients of a color image be subjected to different spectral transforms before the resultant coefficients are coded by an efficient wavelet coefficient coding scheme such as that used in JPEG2000 or color set partitioning in hierarchical trees (CSPIHT). A quadtree represents the spatial partitioning of the set of high frequency coefficients of the color planes into spatially oriented subsets which may be further partitioned into smaller directionally oriented subsets. The partitioning decisions and decisions to employ fixed or signal-dependent bases for each subset are rate-distortion (R-D) optimized by employing a known analytical R-D model for these coefficient coding schemes. A compression system of asymmetric complexity, that integrates the proposed adaptive spectral transform with the CSPIHT coefficient coding scheme yields average coding gains of 0.3 dB and 0.9 dB in the Y component at 1.0 b/p and 2.5 b/p, respectively, and 0.9 dB and 1.35 dB in the U and V components at 1.0 b/p and 2.5 b/p, respectively, over a reference compression system that integrates the single spectral transform derived from the entire image with the CSPIHT coefficient coding scheme.

关键词： adaptive coding color image coding Karhunen-Loeve transform quadtree wavelet transform

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Performance analysis of variable rate: Symbol-by-symbol adaptive bit interleaved coded modulation for Rayleigh fading channels

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2002年第3期51卷 537-550页

作者： Lau, VKN Bell Labs Whippany NJ 07981 USA

A challenging problem in offering high-speed data service over wireless is to protect data over the error-proned fading channel in an effective way (high-bandwidth efficiency). In this paper, we propose a bandwidth-efficient error correction scheme, namely the variable rate adaptive bit interleaved coded modulation (ABICM), for the wireless mobile channel. The code rate and modulation level are varied according to the current channel state to exploit the time-varying nature of the wireless channel. Design challenges to achieve symbol-by-symbol adaptation are addressed. In particular, we address the criteria to choose the family of component codes for the ABICM system. We propose a multilevel puncturing scheme that solves the problem of symbol-by-symbol adaptive puncturing and interleaving. Equivalent distance spectrum for variable rate symbol-by-symbol adaptive codes are introduced and analytical bounds on adaptive codes are derived that enable us to determine the optimal adaptation thresholds. Two operation modes, namely the constant throughput and the constant bit error rate (BER) controls, are proposed. It is found that there are significant gains relative to fixed-rate coding in terms of signal-to-noise ratio (SNR) and throughput. It is also found that the ABICM scheme is essentially not degraded when used with small interleaving depths. This makes the ABICM very suitable for real-time applications.

关键词： adaptive bit interleaved coded modulation (ABICM) adaptive coding bit interleaved modulation

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Channel-adaptive Transmission Protocols for Smart Grid IoT Communication

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IEEE INTERNET OF THINGS JOURNAL 2020年第8期7卷 7823-7835页

作者： Tripathi, Sharda De, Swades Politecn Torino Dept Elect & Telecommun I-10129 Turin Italy Indian Inst Technol Delhi Dept Elect Engn New Delhi 110016 India Indian Inst Technol Delhi Bharti Sch Telecommun New Delhi 110016 India

This article presents a new paradigm for channel dynamics adaptive transmission of intermittent data in smart grid IoT communication networks, wherein novel channel prediction frameworks using stochastic modeling as well as data-driven learning of channel variability are proposed. A probing-based transmission is also proposed as a benchmark. These prediction frameworks are complemented with an adaptive channel coding scheme to increase the transmission reliability of time-critical grid monitoring data over a wireless channel. Through analyzing the prediction and packet loss performance at varying SNR and fading conditions, it is noted that the stochastic modeling framework is efficient when the fading correlation in the channel is high while the learning-based approach is more adaptive to channel dynamics as the correlation reduces. The proposed frameworks are easily implementable on low-cost end nodes, owing to the optimal selection of parameters for low runtime complexity. When compared to probing-based data transmission for a given fading in the channel, the packet loss probability of the learning-based transmission closely matches while with stochastic model loss probability is found to be 12.3% higher. However, their respective signaling overheads are 38% and 98% lower with respect to the probing-based approach, which is a significant gain at the cost of marginally additional computation complexity.

关键词： Phasor measurement units Data communication Internet of Things Predictive models Fading channels Smart grids Adaptation models adaptive coding Gaussian process regression IoT data communication protocols resource efficiency smart grid communication wireless channel prediction

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Low-complexity adaptive transmission for cognitive radios in dynamic spectrum access networks

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2008年第1期26卷 83-94页

作者： Pursley, Michael B. Royster, Thomas C. Clemson Univ Clemson SC 29631 USA

Cognitive radios that are employed in a network with dynamic frequency assignments must operate efficiently in the presence of uncertainties and variations in the propagation characteristics of the network's communication links. A low-complexity adaptive transmission protocol is described and evaluated for use in cognitive radio networks whose links have unknown and possibly time-varying propagation losses as a result of such phenomena as slow fading or variations in shadowing. The cognitive radios are required to derive only simple statistics in the receivers in order to provide the information that is needed by our protocol;no estimates or measurements of received power or channel gain are used. The protocol's primary mechanism for responding to changes in propagation loss is to adjust the modulation and coding. Because of disruptions that can be caused by higher levels of interference to other radios in the network, the transmitter power is increased only if the most powerful combination of coding and modulation is inadequate. We employ finite-state Markov models for slowly varying channels, and we demonstrate that for such channels our protocol performs nearly as well as an ideal protocol that is told the exact value of the propagation loss for each packet transmission. Thus, the additional complexity that is required to enable cognitive radios to obtain precise channel-gain estimates is not justified and would lead to only negligible improvement in throughput. The throughput of our adaptive transmission protocol is compared with an upper bound that is derived from information theory for a hypothetical ideal protocol that is given perfect channel-state information, and some preliminary results on learning the adaptation decision intervals are included.

关键词： adaptive modulation adaptive coding cognitive radio dynamic spectrum access packet radio

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Feature-selective Attention in Frontoparietal Cortex: Multivoxel Codes Adjust to Prioritize Task-relevant Information

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JOURNAL OF COGNITIVE NEUROSCIENCE 2017年第2期29卷 310-321页

作者： Jackson, Jade Rich, Anina N. Williams, Mark A. Woolgar, Alexandra Macquarie Univ Level 316 Univ Ave N Ryde NSW 2109 Australia

Human cognition is characterized by astounding flexibility, enabling us to select appropriate information according to the objectives of our current task. A circuit of frontal and parietal brain regions, often referred to as the frontoparietal attention network or multiple-demand (MD) regions, are believed to play a fundamental role in this flexibility. There is evidence that these regions dynamically adjust their responses to selectively process information that is currently relevant for behavior, as proposed by the adaptive coding hypothesis [Duncan, J. An adaptive coding model of neural function in prefrontal cortex. Nature Reviews Neuroscience, 2, 820-829, 2001]. Could this provide a neural mechanism for feature-selective attention, the process by which we preferentially process one feature of a stimulus over another? We used multivariate pattern analysis of fMRI data during a perceptually challenging categorization task to investigate whether the representation of visual object features in the MD regions flexibly adjusts according to task relevance. Participants were trained to categorize visually similar novel objects along two orthogonal stimulus dimensions (length/orientation) and performed short alternating blocks in which only one of these dimensions was relevant. We found that multivoxel patterns of activation in the MD regions encoded the task-relevant distinctions more strongly than the task-irrelevant distinctions: The MD regions discriminated between stimuli of different lengths when length was relevant and between the same objects according to orientation when orientation was relevant. The data suggest a flexible neural system that adjusts its representation of visual objects to preferentially encode stimulus features that are currently relevant for behavior, providing a neural mechanism for feature-selective attention.

关键词： dimensions Stimuli brain region current task adaptive coding Nervous System Physiological Phenomena Pattern analysis

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Capacity of Remote Classification Over Wireless Channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2021年第7期69卷 4489-4503页

作者： Lan, Qiao Du, Yuqing Popovski, Petar Huang, Kaibin Univ Hong Kong Dept Elect & Elect Engn Hong Kong Peoples R China Aalborg Univ Dept Elect Syst DK-9220 Aalborg Denmark

Remote classification involves offloading complex object-recognition tasks from mobile devices to servers at the network edge. It brings to the mobile device the capability of discerning hundreds of object classes by using the computational and storage capabilities of the infrastructure. Remote classification is challenged by the finite and variable data rate of the wireless channel, which affects the capability to transfer high-dimensional features and thus limits the classification resolution. We introduce a set of metrics under the name of classification capacity that are defined as the maximum number of classes that can be discerned over a given communication channel while meeting a target probability for classification error. We treat both the cases of a channel where the instantaneous rate is known and unknown. The objective is to choose a subset of classes from a class library that offers satisfactory performance over a given channel. We treat two different cases of subset selection. First, a device can select the subset by pruning the class library until arriving at a subset that meets the targeted error probability while maximizing the classification capacity. Adopting a subspace data model, we prove the equivalence of classification capacity maximization to the problem of packing on the Grass-mann manifold. The results show that the classification capacity grows exponentially with the instantaneous communication rate, and super-exponentially with the dimensions of each data cluster. This also holds for ergodic and outage capacities with fading if the instantaneous rate is replaced with an average rate and a fixed rate, respectively. In the second case, a device has a unique preference of class subset for every communication rate, which is modeled as an instance of uniformly sampling the library. Without class selection, the classification capacity and its ergodic and outage counterparts are proved to scale linearly with their corresponding communication ra

关键词： Edge computing adaptive coding fading channels

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Group 3 error-free facsimile terminal for analog cellular networks

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1996年第1期45卷 64-73页

作者： Kawabe, M Kato, T Sato, T Bessho, M Fukasawa, A Communication Systems Laboratory Oki Electric Industry Company Limited Tokyo Japan

Group 3 error-free facsimile terminal for use in an analog cellular network has been developed, This facsimile terminal is provided with the International Telecommunication Union (ITU-T, formerly CCITT) T.30 recommendation protocol and an adaptive error control scheme (AECS) for Group 3 communication and error-free communication, The AECS monitors the channel conditions and selects the optimum error correction code, ITU-T V.27ter is used as the modulation method and the transmission rate is 4800 bps, This system is compatible with the modified Huffman (MH), modified READ (MR), and modified modified READ (MMR) image data compression codes. The average communication time of this facsimile terminal is 40 s per page under moving condition through the analog cellular network.

关键词： adaptive codes cellular radio error correction codes facsimile facsimile equipment modulation protocols radio networks telecommunication standards 40 s 4800 bit/s CCITT Group 3 communication Group 3 error-free facsimile terminal ITU-T ITU-T V.27ter Inter TELEPHOTOGRAPHY(FACSIMILE) modulation mode Error-free operations Error correction codes adaptive coding cellular radio telecommunication standards protocols Radio networks

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Advanced communications technology satellite (ACTS) fade compensation protocol impact on very small-aperture terminal bit error rate performance

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1999年第2期17卷 173-179页

作者： Cox, CB Coney, TA NASA Lewis Res Ctr Cleveland OH 44135 USA Analex Corp Brook Pk OH 44142 USA

The Advanced Communications Technology Satellite (ACTS) communications system operates at Ka band. ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of an analysis characterizing the improvement in VSAT performance provided by this protocol. The metric for performance is VSAT bit error rate (BER) availability. The acceptable availability defined by communication system design specifications is 99.5% for a BER of 5E-7 or better. VSAT EER availabilities with and without rain fade compensation are presented. A comparison shows the improvement in EER availability realized with rain fade compensation. Results are presented for an eight-month period and for 24 months spread over a three-year period. The two time periods represent two different configurations of the fade compensation protocol.

关键词： adaptive coding attenuation propagation rain satellite communication satellites

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