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turbo coding with equalization in WCDMA downlink

WIRELESS PERSONAL COMMUNICATIONS 2004年第4期28卷 259-276页

作者： Drajic, D Hooli, K Juntti, M Ericsson DOO YU-11070 Belgrade Serbia Univ Oulu Ctr Wireless Commun FIN-0014 Oulu Finland

In this paper, the performance of turbo coding in WCDMA downlink is considered in conjunction with receivers using two adaptive channel equalizers. Bit error and frame error rates are compared to the performance of the conventional Rake receiver. Special consideration is given to the cases with two receive antennas, the efficiency of the channel interleaver, the number of iterations in decoding, the performance with various numbers of users, the influence of mobile receiver velocity as well as to the effect of power control. The simulation results show that turbo coding, combined with power control and channel equalizers is a very efficient way to implement reliable data transmissions in WCDMA downlink. The results in the paper also verify that the adaptive channel equalizers is a very promising technique to improve the receiver performance and increase the user capacity.

关键词： WCDMA downlink turbo coding equalization Rake receiver

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turbo coding of strongly nonuniform memoryless sources with unequal energy allocation and PAM signaling

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2006年第5期54卷 1942-1946页

作者： Cabarcas, F Souza, RD Garcia-Frias, J Univ Delaware Dept Elect & Comp Engn Newark DE 19716 USA CPGEI CEFET PR BR-80230901 Curitiba Parana Brazil

The design of asource-controlled turbo coding scheme for the transmission of strongly nonuniform binary memoryless sources over additive white Gaussian noise (AWGN) channels is considered. The use of non-binary signaling allows performance improvements over previous existing schemes that use binary modulation. The basic idea is to allocate more energy to the transmitted symbols associated with the information bits that occur less likely and to exploit the source nonuniformity in the decoding process. If the source and channel parameters are unknown, they can be estimated jointly with the encoding/decoding process. No performance degradation is observed in this case.

关键词： nonuniform sources source coding turbo coding unequal energy allocation

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The performance of turbo coding over power-controlled fading channel in Ka-band LEO satellite systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2003年第4期52卷 1032-1043页

作者： Li, WZ Dubey, VK Law, CL OKI Techno Ctr Singapore Singapore Nanyang Technol Univ Nanyang Singapore

In this paper, the integration of power control and turbo coding is adopted to achieve reliable communications over Ka-band code-division multiple-access (CDMA)-based low earth orbit (LEO) satellite systems. The effect of imperfect power control on the bit error ratio (BER) performance is analyzed, and the upper bounds on BER are also derived for the case of slow and fast imperfect power control. The analytical and simulation results show that power-control error (PCE) degrades the BER performance of turbo-decoded systems significantly in the waterfall region. In the region of error floor, the degradation effect slows down and the BER obtained under imperfect power control eventually converges with the BER under perfect power control. Moreover, in the waterfall region, the correlation characteristics of the PCE fluctuation do not degrade the BER performance as anticipated.

关键词： imperfect power control Ka-band low earth orbit (LEO) satellite pairwise error probability (PEP) turbo coding

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Capacity-approaching turbo coding for half-duplex relaying

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IEEE TRANSACTIONS ON COMMUNICATIONS 2007年第10期55卷 1895-1906页

作者： Zhang, Zheng Duman, Tolga M. Arizona State Univ Dept Elect Engn Tempe AZ 85287 USA

In this paper, we develop capacity-approaching turbo-coding schemes for half-duplex relay systems as an extension of our previous work on coding for full-duplex relays. We consider the use of specific signal constellations (e.g., binary phase-shift keying) in transmission, develop practical coding schemes to. be used at the source and the relay nodes, and describe a suitable information combining technique at the destination node. Unlike the full-duplex relay systems, the destination node does not perform joint decoding of multiple consecutive blocks;instead, it works with one frame at a time. Furthermore, for the half-duplex relaying scheme, the optimization of the length of the listening period for the relay node is an issue. By utilizing information theoretical tools, we perform this optimization and use it in the development of our capacity-approaching coding/decoding schemes. Specifically, when the fraction of time turns out to be less than the transmission rate, the relay node is unable to decode all the information bits transmitted, and a partial decoding approach has to be used. Through a comprehensive set of examples, we observe that the proposed scheme is promising to approach the corresponding information theoretical limits (bounds). In particular, for all the cases studied, we have obtained bit error rates of 10(-5) or lower within 1-1.5 dB (in most cases, almost within 1.2 dB) of the constrained capacity under a variety of channel conditions. Extensions of the proposed scheme to coded modulation and to multiple-input multiple-output systems are also described.

关键词： channel capacity cooperative diversity half duplex information rates iterative decoding multihop multiple-input multiple-output (MIMO) relay turbo coding

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Combined turbo coding and hierarchical QAM for unequal error protection of H.264 coded video

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2006年第5期21卷 390-395页

作者： Barmada, B. Ghandi, M. M. Jones, E. V. Ghanbari, M. Univ Essex Dept Elect Syst Engn Colchester CO4 3SQ Essex England

This paper investigates the unequal error protected (UEP) transmission of scalable H.264 bitstreams with two-priority layers, where differentiated turbo coding provides better protection for the high priority (HP) base layer than for the low priority (LP) enhancement layer. The drawback of such a method is the high overhead introduced by the channel coding, which results in a low source data rate for the HP layer, and hence lowers video quality. To overcome this problem, we introduce an efficient combination of turbo coding and hierarchical quadrature amplitude modulation (HQAM) to provide a high protection for the HP layer and at the same time maintaining the requisite channel coding redundancy. Simulation results show that, over a wide range of channel signal-to-noise ratio (SNR), our combined technique is superior to non-scalable transmission and outperforms UEP with turbo coding alone. (C) 2006 Elsevier B.V. All rights reserved.

关键词： prioritized layered video transmission hierarchical QAM turbo coding

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Capacity-approaching turbo coding and iterative decoding for relay channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2005年第11期53卷 1895-1905页

作者： Zhang, Z Duman, TM Arizona State Univ Dept Elect Engn Tempe AZ 85287 USA

In this paper, we design turbo-based coding schemes for relay systems together with iterative decoding algorithms. In the proposed schemes, the source node sends coded information bits to both the relay and the destination nodes, while the relay simultaneously forwards its-estimate for the previous coded block to the destination after decoding and re-encoding. The destination observes a superposition of the codewords and uses an iterative decoding algorithm to estimate the transmitted messages. Different from the block-by-block decoding techniques used in the literature, this decoding scheme operates over all the transmitted blocks jointly. Various encoding and decoding approaches are proposed for both single-input single-output and multi-input multi-output systems over several different channel models. Capacity bounds and information-rate bounds with binary inputs are also provided, and it is shown that the performance of the proposed practical scheme is typically about 1.0-1.5 dB away from the theoretical limits, and a remarkable advantage can be achieved over the direct and multihop transmission alternatives.

关键词： channel capacity cooperative diversity full duplex information rates iterative decoding multihop multiple-input multiple-output (MIMO) relay turbo coding

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Design of a new interleaver using cross entropy method for turbo coding

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IET COMMUNICATIONS 2013年第9期7卷 828-835页

作者： Abderrahmane, Lahcen Hadj Algerian Space Agcy ASAL Ctr Satellite Dev CDS Oran Algeria

The main aim of this work is to find a way to improve a turbo code performance by designing a new interleaver structure based on the cross entropy (CE). The goal is to compare the performance of the CE method to a more popular interleaver such as the dithered golden interleaver. This study describes the performance of the turbo code - binary phase shift keying (BPSK) modem which was designed at the Instrumentation Division, Centre of Space Techniques. The simulation results are detailed in terms of the optimal solution observed along with the estimated bit-error rate against E-b/N-0. The authors compare the performance of turbo codes for different interleaver sizes and different number of iterations (resulting trade-off curves) assuming two channel types (Gaussian and Rayleigh channels). For the simulated cases of the interleavers, good performance is obtained with the CE interleaver when transmitting data both in short block length (N = 400 bits), and long block length (N = 1024).

关键词： channel coding Gaussian channels interleaved codes phase shift keying Rayleigh channels turbo codes interleaver code design cross entropy method turbo coding interleaver structure CE method dithered golden interleaver BPSK modem estimated bit-error rate Rayleigh channels Gaussian channels CE interleaver block length

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Multi-user MIMO mobile CDMA uplink system employing turbo coding and joint detection through a multipath Rayleigh fading channel

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WIRELESS PERSONAL COMMUNICATIONS 2006年第3期38卷 325-341页

作者： Fahmy, Yasmine A. Mourad, Hebat-Allah M. Al-Hussaini, Emad K. Cairo Univ Fac Engn Elect & Commun Dept Giza 12613 Egypt

In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitter, the information bits are turbo coded, then interleaved and passed through a serial-to-parallel converter. The channel is assumed bad urban suffering from multipath Rayleigh fading resulting in inter-symbol and multiple access interferences (ISI and MAI). At the front-end of the receiver, a number of receiving antennas are used followed by a joint multi-user estimator based on the Minimum Mean Square Error Block Linear Equalizer (MMSE-BLE). Computer simulations demonstrate a significant performance improvement in both single user and multi-user cases.

关键词： MIMO systems turbo coding CDMA joint multi-user detection multipath Rayleigh fading channel least mean square error equalizers

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Performance of turbo coding with improved interference estimation on the CDMA space time transmit diversity forward link

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2006年第3期55卷 1074-1079页

作者： Messier, Geoffrey G. Krzymien, Witold A. Univ Calgary Dept Elect & Comp Engn Calgary AB T2N 1N4 Canada Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 2E1 Canada TRLabs Edmonton AB T6G 2V4 Canada

This paper proposes an approach to improve turbo code performance on the space time transmit diversity (STTD) code-division multiple-access (CDMA) forward link through better estimation of the channel state information (CSI) required by the mobile turbo decoder. An improved CSI estimation scheme that accounts for the unique nature of CDMA STTD intracell interference is presented. It is compared to a standard CSI estimation scheme that assumes all STTD interference and noise can be represented as additive white Gaussian noise at the mobile receiver input. An STTD CDMA forward link simulation shows that link performance is significantly improved when the mobile turbo decoder uses the more accurate CSI provided by improved estimation. However, the degree of improvement depends on the turbo decoding algorithm, mobile velocity, and whether the base station is using STTD or single-antenna transmission.

关键词： code-division multiple-access space time block codes transmit diversity turbo coding

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A turbo coding Scheme for Channels with Synchronization Errors

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IEEE TRANSACTIONS ON COMMUNICATIONS 2012年第8期60卷 2091-2100页

作者： Mansour, Mohamed F. Tewfik, Ahmed H. Texas Instruments Inc Syst & Applicat R&D Ctr Dallas TX 75243 USA Univ Texas Austin Dept Elect & Comp Engn Austin TX 78712 USA

We describe a turbo coding scheme with nonsystematic recursive convolutional codes for channels that exhibit insertions and deletions along with substitution errors. The scheme uses the MAP decoding algorithm for this channel and a special codeword arrangement to simplify the synchronization process. The decoder uses a special trellis structure to extract synchronization extrinsic information that is exchanged between the two constituent decoders. The proposed scheme is shown to provide improvement over earlier channel coding approaches for this channel model.

关键词： turbo coding synchronization insertions deletions MAP trellis

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