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IEEE International Conference on Communications (ICC)

作者： V. Boussemart H. Brandt M. Berioli German AeroSpace Center (DLR) Institute of Communications and Navigation Oberpfaffenhofen Wessling Germany

The number of coding and modulation Schemes suggested for the two standards DVB-S2 and DVB-RCS (in its "advanced" version) is overdimensioned; a subset of schemes can be used and this only reduces the overall system performance negligibly. This paper presents the investigations performed on this rain fading mitigation technique, called Adaptive coding and modulation (ACM), supported by the DVB-S2 standard and shows how the sets of modulation and coding schemes, considered in the forward and in the return-links, can be changed to reduce terminal complexity and how this affects the overall system performance. It is shown that, by a careful selection of the ACM schemes, already with less than one fourth (7 or 5 out of 28) of the total number of schemes it is possible to get performance close to the optimum, but with a much lower terminal complexity.

关键词： Adaptive coding modulation coding Digital video broadcasting Satellite broadcasting Analytical models Robustness System performance Rain Fading Clouds

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Pattern-Based Channel Quality Prediction for Adaptive coding and modulation in Wireless Networks

Pattern-Based Channel Quality Prediction for Adaptive Coding...

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IEEE International Conference on Communications (ICC)

作者： D.-D. Luong J.-C. Gregoire Z. Dziong Department of Electrical Engineering École de Technologie supérieure Canada Energy Materials and Telecommunications Institut national de la Recherche Scientifique Canada

Channel quality prediction is important for many networking mechanisms. This paper considers long-term prediction with the prediction distance of some hundred milliseconds. The prediction works in the context of Adaptive coding and modulation, which actually converts the task of continuous value prediction into discrete value prediction. In this work, pattern management is also considered as a key mechanism to reduce memory and processing overheads. Performance evaluation is carried out using measurement traces to evaluate the prediction algorithm with different parameter settings and matching measures.

关键词： Adaptive coding modulation coding Wireless networks Fading Interference Pattern matching Transmitters Delay estimation Signal to noise ratio Paper technology

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Adaptive Turbo Trellis Coded modulation Aided Distributed Space-Time Trellis coding for Cooperative Communications

Adaptive Turbo Trellis Coded Modulation Aided Distributed Sp...

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IEEE Conference on Vehicular Technology (VTC)

作者： Soon Xin Ng Chuyi Qian Dandan Liang Lajos Hanzo School of Electronics and Computer Science University of Southampton UK

Abstract-In this contribution, we propose an adaptive Turbo Trellis Coded modulation (TTCM) aided Distributed Space-Time Trellis coding (STTC) scheme for cooperative communication over quasi-static Rayleigh fading channels. An adaptive TTCM (ATTCM) scheme is employed by the source node during the first transmission period for reliably conveying the source bits to N number of relay nodes by appropriately adjusting the code-rate and modulation mode according to the near-instantaneous channel condition. The TTCM switching thresholds are chosen to ensure that the Bit Error Ratio (BER) at each relay node becomes lower than 10 -6 in order to minimise the potential error propagation imposed by the relay nodes. During the second transmission period, an N-antenna assisted Distributed STTC (DSTTC) scheme is created with the aid of the aforementioned N single-antenna relay nodes. More specifically, the N relay nodes are utilised to form STTC codewords based on the re-encoded TTCM symbols of the relays for transmission to the destination node. At the destination node, iterative extrinsic information exchange is performed between the STTC and TTCM decoders for recovering the original source bits. It is shown that the proposed ATTCM-DSTTC scheme requires 12 dBs less transmission power in comparison to a standard TTCM scheme when aiming for a frame error ratio of 10 -3 .

关键词： modulation coding Relays Fading AWGN Bit error rate Collaboration MIMO Additive white noise Receiving antennas Transmitting antennas

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On the Throughput of an OFDM-based Cellular Optical Wireless System for an Aircraft Cabin

On the Throughput of an OFDM-based Cellular Optical Wireless...

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European Conference on Antennas and Propagation

作者： Svilen Dimitrov Harald Haas Mario Cappitelli Michael Olbert The University of Edinburgh Institute for Digital Communications Joint Research Institute for Signal and Image Processing EADS Germany

ISBN: (纸本)9781457702501

In this paper, a cellular optical wireless communication system based on orthogonal frequency division multiplexing (OFDM) is simulated inside an aircraft cabin. Asymmetrically clipped optical OFDM (ACO-OFDM) and direct-current-biased optical OFDM (DCO-OFDM) transmission schemes are compared in terms of throughput and cell coverage. Cellular networks with wavelength reuse factors of 1 (full reuse), 2 and 3 are modeled, and off-the-shelf optical front-end components are assumed. Signal-to-interference-and-noise ratio (SINR) maps are determined via a Monte Carlo ray-tracing (MCRT) global irradiation simulation in a computer-aided design (CAD) cabin model. Due to the use of OFDM, adaptive modulation and coding (AMC) can be applied to the SINR maps to arrive at the spatial throughput. It is shown that throughput within the range of 1.56 - 30 Mbps is achievable with the considered ACO-OFDM system, whereas DCO-OFDM doubles the throughput to 3.13-60 Mbps. In addition, wavelength reuse factors of 3 or higher are needed to ensure full cell support for both transmission schemes.

关键词： ACO-OFDM DCO-OFDM Throughput Cellular optical wireless system Adaptive modulation and coding Throughput Aircraft cockpits Orthogonal frequency division multiplexing modulation coding Optical wireless SINR CARRIER SYSTEM Reuse reuse Cells

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A study of access methods effect on the performance of two-tier LTE femtocell networks

A study of access methods effect on the performance of two-t...

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National Conference on Radio Science (NSRC)

作者： Mofreh El- Gendy Essam Sourour Faculty of Engineering Alexandria University Alexandria Egypt

Femtocells are a promising solution for the provision of high indoor coverage and capacity. Furthermore, OFDMA-based femtocells have proven to be highly versatile when dealing with cross-layer co-channel interference; however, concerns still exist related to the impact of the different access methods to femtocells in an overlaid network. Femtocells based on a Closed Subscribers group, where only device owners are allowed to connect, introduce severe interference to microcells' users. On the other hand, Open Access femtocells where any user can connect, does not bring many advantages to the femtocell owner. In this paper, a study of the two types of access methods (Closed & Open Access) is proposed and a discussion of how to overcome their drawbacks by using the Hybrid access method is presented, which allows all users to connect but under restrictions. The performance of the model is evaluated throughout system level simulations and it is shown that Hybrid access contributes to seriously improve the performance of the whole network.

关键词： Downlink Phase shift keying Signal to noise ratio Interference modulation coding

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Improving Data Throughput for Cell-Edge Users in a LTE Network Using Up-Link HARQ Relays

Improving Data Throughput for Cell-Edge Users in a LTE Netwo...

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IEEE Conference on Vehicular Technology (VTC)

作者： R. Neil Braithwaite Powerwave Technologies AB Santa Ana CA USA

It is proposed that up-link relays be used to improve the data throughput for user equipment (UE) near the cell edge in a LTE network. Relay assistance on the up-link occurs when the evolved Node B (eNB) requests a retransmission (HARQ) from the UE at which point the UE and relay transmit simultaneously. The quality of the up-link signal received by the eNB is improved due to a favorable channel through the relay. An analysis and simulation show that relay assistance improves the throughput for a cell-edge user when the average delay per data transport block is allowed to increase. A modification of the up-link power control is recommended when using relays, where the maximum power transmitted by the UE is reduced.

关键词： Relays Throughput Signal to noise ratio Power control modulation coding Receivers Indexes

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Orthogonal chaotic vector shift keying in digital communications

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IET COMMUNICATIONS 2010年第6期4卷 739-753页

作者： Wren, T. J. Yang, T. C. Univ Sussex Dept Engn & Design Brighton BN1 9QT E Sussex England

An orthogonal chaotic vector shift keying digital communication scheme is presented. The main characteristics of the scheme are increased data transmission rates with greatly improved robustness and an increase in security of communications links because of the structure of the scheme and the nature of the message bearer. Compared with some existing schemes, for example, quadrature chaos shift keying (QCSK) reported in the literature, the noise rejection is improved by an increase in the 'inter-symbolic separation'. Furthermore, a new method of characterising non-linear processing elements in complex communication schemes has been presented. Based on this, a simple modelling and evaluation method to determine the bit error rates of these schemes is derived. Various simulated results are presented to demonstrate these achievements.

关键词： quadrature chaos shift keying telecommunication security error statistics noise rejection modulation coding modulation and coding methods OCVSK method inter-symbolic separation QPSK BER performance BPSK digital communications differential chaos shift keying DCSK bit error rates nonlinear processing elements chaotic communication phase shift keying data communication data transmission orthogonal chaotic vector shift keying digital communication communications link security

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Slot and frame synchronisation in dicode pulse-position modulation

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IET OPTOELECTRONICS 2010年第4期4卷 174-182页

作者： Charitopoulos, R. A. Sibley, M. J. N. Univ Huddersfield Sch Comp & Engn Dept Engn & Technol Huddersfield HD1 3DH W Yorkshire England

Dicode pulse position modulation (DiPPM) has been postulated as a coding scheme that appears to be more efficient than some of previous coding techniques. Previous publications reported theoretical simulations of DiPPM coder and spectrums of both practical and theoretical DiPPM coders have been presented. In this study, for the first time, the extraction of a clock from a 240 Mbit/s DiPPM signal is demonstrated. Original experimental, theoretical and computer predicted results for the spectrum of a DiPPM signal are presented. The results obtained agree with each other. It is shown that DiPPM is a very attractive pulse position modulation (PPM) scheme for optical communication.

关键词： modulation coding modulation and coding methods frame synchronisation dicode pulse-position modulation optical modulation pulse position modulation synchronisation bit rate 240 Mbit/s Optical communication equipment slot synchronisation optical communication optical receivers

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Interference Estimation in IEEE 802.11 Networks A KALMAN FILTER APPROACH FOR EVALUATING CONGESTION IN ERROR-PRONE LINKS

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IEEE CONTROL SYSTEMS MAGAZINE 2010年第2期30卷 30-43页

作者： Tinnirello, Ilenia Bianchi, Giuseppe Univ Palermo Dipartimento Ingn Elettr Elettron & Telecomunicaz I-90128 Palermo Italy Univ Roma Tor Vergata Sch Engn Rome Italy Politecn Milan Milan Italy

This article describes a technique for distinguishing and quantifying medium access control (MAC) and physical layer (PHY) interference in error-prone 802.11 networks. This technique, is fully distributed, allowing each station to estimate interference individually. The estimator is based on an extended Kalman filter coupled to a mechanism for revealing abrupt changes in state. The network state is a vector of two components, representing PHY interference, expressed in terms of channel-error rate, and MAC interference. Two distinct state models are considered. When PHY interference can be assumed to be constant for all stations, network congestion is expressed by the number of competing terminals.

关键词： Interference Physical layer Access protocols Media Access Protocol Hardware modulation coding IP networks Local area networks Portable computers Wireless sensor networks

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Channel estimation in bit-interleaved coded modulation with iterative decoding

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IET COMMUNICATIONS 2010年第17期4卷 2095-2103页

作者： Andalibi, Z. Nguyen, H. H. Salt, J. E. Univ Saskatchewan Dept Elect & Comp Engn Saskatoon SK S7N 5A9 Canada TRlabs Saskatoon SK Canada

This study improves the fading channel estimation in bit-interleaved coded modulation systems with iterative decoding (BICM-ID) and signal space diversity (SSD) by embedding a training sequence. Existing training schemes work well at high signal-to-noise ratio (SNR) or slowly time-varying channels whereas the applications of BICM-ID are beneficial at low SNR and fast time-varying fading channels. Motivated by the power/bandwidth efficiency of the SSD technique and the fact that superimposed training outperforms pilot symbol-assisted modulation (PSAM) training over relatively fast time-varying channels, a new superimposed training sequence is explored. The proposed training sequence inserts pilot bits into the coded bits prior constellation mapping and signal rotation. This becomes a superimposed training sequence in the rotated symbols and helps the estimator to track fast variation of the channel gains. A soft iterative channel estimator is developed to work with the superimposed training sequence. The performance of the proposed scheme, namely SSD-pilot, is shown to be superior to PSAM scheme. To gauge the performance improvement achieved with the proposed channel estimation, an analytical bound on the asymptotic bit error probability for BICM-ID using SSD over correlated fading channels is provided. The Cramer-Rao bound on the mean-square error of the channel estimator is also derived to evaluate the performance of the iterative channel estimator.

关键词： Iterative decoding bit error probability correlated fading channel Bit interleaved coded modulation time-varying channels channel estimation modulation coding training sequence Pilots low SNR performance boost

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