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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Reem Abdelhadi Hesham Elbadawy Salwa El-Ramly Network Planning Department NTI Cairo Egypt Communication & Electronics Department Ain Shams University Cairo Egypt

WiMAX technology is considered one of the most important solutions capable to provide a Broadband Wireless Access in metropolitan areas. Mobility issues have become challenging for the rollout for WiMAX networks in order to compete against the other competitive technologies such as 3.5G and LTE. In this paper, a unified approach to derive the overall BER and data rate for mobile WiMAX (in uplink direction) will be introduced. This approach will take into consideration different operational scenarios such as time varying channels with different values of channel estimation precision values, different number of subcarriers, and different symbol durations. An analytical expression for the effect of ICI power on the bit error probability and effective bit rate will be obtained for BPSK, QPSK, and 16QAM in presence of AMC. This paper also investigates the effect of the use of AMC techniques on the obtained system performance.

关键词： Performance analysis WiMAX Adaptive systems modulation coding Fading Urban areas Bit error rate Channel estimation Error probability Bit rate

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Adaptive Algorithm for Mapping Channel Quality Information to modulation and coding Schemes

Adaptive Algorithm for Mapping Channel Quality Information t...

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IEEE Conference on Vehicular Technology (VTC)

作者： Patrick Hosein Huawei Technologies Company Limited San Diego CA USA

In the present and future generation of wireless networks, link adaptation is used for better channel efficiency. With link adaptation the modulation and coding scheme used for transmissions to a particular user is adjusted based on the user's channel conditions. However, because of delays and measurement errors in the reported channel quality information, the actual transmission may experience a significantly different channel than anticipated. This can either lead to transmission errors (if the channel has deteriorated) or wasted transmission resources (if the channel is actually better than predicted). To avoid the former scenario, a conservative mapping from channel quality information to modulation and coding scheme is used. However, the degree of this conservatism depends on the Doppler Frequency of the channel with higher values requiring a more conservative mapping. In this paper we propose an algorithm for dynamically adjusting the mapping from channel quality reports to the modulation and coding scheme. Hybrid ARQ is assumed and we use the outcome of the first transmission to adjust the mapping. Simulation results are used to illustrate the effectiveness of the approach.

关键词： Adaptive algorithm modulation coding Frequency Statistics Wireless networks Delay Automatic repeat request Measurement errors Heuristic algorithms Standards development

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Adaptive modulation and coding for generalized fading channels

Adaptive modulation and coding for generalized fading channe...

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International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Service (TELSIKS)

作者： Ivan B. Djordjevic Goran T. Djordjevic Department of Electrical and Computer Engineering IUniversity of Arizona Tucson AZ Telecommunications Department University of Nis Serbia Montenegro

The adaptive modulation and coding can provide robust and spectrally efficient transmission over generalized ¿-¿ (or generalized gamma) wireless fading channels. The key idea of our proposal is to transmit the low-density parity-check (LDPC) encoded sequence over the generalized fading channel, feedback the channel state information of by an RF feedback channel, and adapt the powers and rates of so that the channel capacity is maximized. The optimal power adaptation policy maximizing the channel capacity is derived. We show that deep fades can be tolerated with proposed scheme.

关键词： modulation coding Fading Parity check codes Radio frequency Channel capacity Power system modeling Transmitters Wireless communication Receiving antennas Transmitting antennas

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Performance and complexity tradeoffs of space-time modulation and coding schemes

Performance and complexity tradeoffs of space-time modulatio...

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Asilomar Conference on Signals, Systems & Computers

作者： Nicholas B. Chang Adam R. Margetts Andrew L. McKellips Lincoln Laboratory Massachusetts Institute of Technology Lexington MA USA Advanced Sensor Techniques Group Lincoln Laboratory Massachusetts Institute of Technology Lexington MA USA

ISBN: (纸本)9781424458257

Wireless communication using multiple-input multiple-output (MIMO) systems improves throughput and enhances reliability for a given total transmit power. Achieving a higher data rate in MIMO systems requires utilizing an effective space-time coding and modulation scheme. The appropriate algorithm to use for a system will depend on parameters such as the number of transmit/receive antennas, target spectral efficiency, complexity limitations, channel environment, and other factors. In this paper, we examine the performance of various two-transmit and four-transmit space-time coding schemes under different channel types and target data rates. We compare the performance of state of the art space-time coding schemes including direct non-binary LDPC GF(q) modulation, bit interleaved coded modulation using iterative detection, and space-time trellis coded modulation. We obtain a tradeoff between performance and complexity of these various schemes.

关键词： modulation coding MIMO Receiving antennas Fading Decoding Wireless communication Power system reliability Parity check codes Transmitting antennas Transmitters

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Performance of multi-user MIMO OFDM system with adaptive modulation and coding for wireless communications

Performance of multi-user MIMO OFDM system with adaptive mod...

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International Conference on Advanced Communication Technology (ICACT)

作者： Kwang Yoon Kim Yoon Hyun Kim Jin Young Kim Department of Wireless Communications Engineering Kwangwoon University Seoul South Korea

As the demand of high quality service in next generation wireless communication systems, a high performance of data transmission requires an increase of spectrum efficiency and an improvement of error performance in wireless communication systems. In this paper, we propose a multi-user multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with adaptive modulation and coding to improve system capacity with maintaining good error performance. The results of computer simulation show the improvement of system capacity in Rayleigh fading channel.

关键词： MIMO Adaptive systems modulation coding OFDM modulation Wireless communication Data engineering Base stations Computer errors Fading Interference

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ARQ strategies for MIMO eigenmode transmission with adaptive modulation and coding

ARQ strategies for MIMO eigenmode transmission with adaptive...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Elisabeth de Carvalho Petar Popovski University of Aalborg Aalborg Denmark

Packet retransmission strategies are presented for MIMO eigenmode transmission where adaptive modulation and coding (AMC) is implemented. The retransmission design is based on weighted linear MMSE. It includes the transmit and receiver filter, the power and eigenmode allocation and AMC level when new packets are transmitted. The weight matrix of WMMSE is used to appropriately weight streams with different AMC levels in order to maximize the system throughput. Simulations show that the choice of the weight factors has a major impact on the performance.

关键词： Automatic repeat request MIMO modulation coding Decoding Power filters Transceivers Error correction Throughput Transmitters Channel state information

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Block modulation for Interference Management in Heterogeneous Wireless Networks

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2012年第3期6卷 241-256页

作者： Ayyar, Arun Balakrishnan, Hari Ram Thangaraj, Andrew Nagarajan, Vinoth Giridhar, K. Indian Inst Technol Dept Elect Engn Madras 600036 Tamil Nadu India Broadcom Commun Bangalore 560037 Karnataka India

To meet growing target data rates, future wireless networks will be heterogeneous with macro and pico base stations (BSs). Allocating resources and managing interference between various types of BSs are of primary importance for achieving acceptable throughput in cell edges. In this work, we propose the interference canceling block modulation (ICBM) scheme for interference management in heterogeneous networks. We provide analytical design methods for ICBM and study the application of ICBM in heterogeneous wireless networks. Our results essentially show that ICBM acts as a virtual resource, significantly improving the data rates for cell-edge users as well as the cell average throughput over the conventional techniques in typical interference scenarios arising in heterogeneous networks.

关键词： 4G mobile communication interference channels interference elimination maximum-likelihood detection modulation coding

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Error Correcting Capable 2/4 modulation Code Using Trellis Coded modulation in Holographic Data Storage

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JAPANESE JOURNAL OF APPLIED PHYSICS 2012年第8期51卷 08JD08-08JD08页

作者： Kim, Yongok Kong, Gyuyeol Choi, Sooyong Yonsei Univ Sch Elect & Elect Engn Seoul 120749 South Korea

An error correcting capable 2/4 modulation code scheme is proposed in holographic data storage (HDS) systems. We adopt trellis coded modulation (TCM) to obtain a good error correcting capability without loss of data rate in the HDS systems. To overcome loss of a data rate caused by a 1/2-rate convolutional code, we extend a 2/4 modulation code set the 3/4 modulation code set as high-order modulation in the proposed scheme. Additionally, we find an optimal mapping method of index numbers to maximize the free distance on the trellis and calculate the free distance according to each constraint length. The simulation results show that the proposed scheme with the same data rate has about 4 dB coding gains compared to the conventional 2/4 modulation coding scheme. (C) 2012 The Japan Society of Applied Physics

关键词： Data transfer rates error correction constraint length Data Storage Holography Trellis codes trellis coded modulation Codes modulation coding

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Analysing bit-interleaved coded modulation in multiple-input multiple-output systems with channel estimation error

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IET COMMUNICATIONS 2012年第11期6卷 1502-1510页

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

The performance of bit-interleaved coded modulation in multiple-input multiple-output (BICM-MIMO) systems using an iterative channel estimator is analysed. In a conventional iterative channel estimator, after initialisation with the training phase, the channel estimator switches to the data phase. However, such a conventional iterative channel estimator does not always improve the performance of the receiver. In order to guarantee the performance improvement, a condition on when the output of the decoder should be used by the estimator is determined. Such a condition is related to the reliability of the soft information utilised by the channel estimator. The key in establishing this relationship is to use the mutual information (MI) that the observation vector has about the channel gains given the output of the decoder at each iteration. In this switch-augmented conventional iterative channel estimator, referred to as SAICE, the condition is theoretically found and indicates the needed reliability of the soft information for the channel estimator at the switching time. The switch-augmented scheme guarantees performance improvement of the iterative receiver with each iteration, however, it might need many iterations to converge for moderate to low signal-to-noise ratios (SNRs). A less computationally intensive approach is to use both the training and data segments of the observation. This approach produces a combined iterative channel estimator (CICE) for BICM-MIMO systems. The performance behaviour of the BICM-MIMO system is illustrated through the extrinsic information transfer (EXIT) chart with imperfect channel state information (CSI). Analytical results are verified with computer simulations.

关键词： reliability Communication switching SAICE error Reliability signal-to-noise ratio BICM-MIMO system observation vector multiple-input multiple-output system MI Codes modulation coding imperfect CSI wireless channels iterated switching networks channel estimation combined iterative channel estimator Algebra soft information utilised mutual information channel coding EXIT chart interleaved codes radio receivers bit-interleaved coded modulation analysis less computationally intensive approach radio receiver vectors extrinsic information transfer chart CICE channel estimator switch imperfect channel state information decoder Radio links and equipment Communication channel equalisation and identification iterative decoding SNR switch-augmented conventional iterative channel estimator error telecommunication network reliability MIMO communication

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Competitive decoders for turbo-like chaos-based systems

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IET COMMUNICATIONS 2012年第10期6卷 1278-1283页

作者： Wagemakers, A. Escribano, F. J. Lopez, L. Sanjuan, M. A. F. Univ Rey Juan Carlos Dept Phys Mostoles 28933 Spain Univ Alcala Dept Signal Theory & Commun Alcala De Henares 28805 Spain Univ Rey Juan Carlos Dept Telemat Syst & Comp Mostoles 28933 Spain

Recent work has shown that chaos-based communication systems can yield performances as good as their non-chaotic counterparts in additive white Gaussian noise (AWGN), and behave even better in flat-fading channels. However, much of this work relies on computer simulations and there is still a need to study in depth the implementation issues of such systems. The authors address for the first time a fixed-point arithmetic implementation of the iterative decoding algorithm for a recently proposed and successful class of parallel concatenated chaos-based coded modulations. The novel digital signal processor (DSP) results demonstrate that it is possible to implement in standard hardware competitive chaos-based communication systems.

关键词： Communication system theory competitive decoder additive white Gaussian noise turbo like chaos based systems Codes AWGN parallel concatenated chaos based coded modulation modulation coding fading channels fixed point arithmetic Codecs, coders and decoders decoding Digital signal processing chips chaotic communication digital signal processor turbo codes iterative decoding algorithm digital signal processing chips Radio links and equipment chaos based communication systems computer simulations fixed point arithmetic implementation flat fading channel

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