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EMI suppression technique for ISM-band WLANs using multicode transmission and EMI observation channel

IEICE TRANSACTIONS ON COMMUNICATIONS 2000年第3期E83B卷 532-540页

作者： Unawong, S Miyamoto, S Morinaga, N Osaka Univ Grad Sch Engn Suita Osaka 5650871 Japan

It is well known that the electromagnetic interference (EMI) radiated from industrial, scientific and medical (ISM) apparatus seriously degrades the performance of wireless communication systems. In this paper, an ISM-band wireless local area network (WLAN) which employs a direct sequence spread spectrum (DS-SS) system is designed to be sufficiently robust and reliable to operate in the presence of this EMI. To satisfy this goal, a technique to suppress EMI in the DS-SS system using a multicode transmission and an EMI observation channel is proposed. In the study, thf EMI radiated from switching-type microwave ovens (MWO interference) which are ISM apparatus is concerned, and for a tractable investigation, a statistical model to represent MWO interference based on experimental measure ment results is employed. As well known that MWO interference exhibits a bursty impulsive characteristic in time, a technique to transmit multiple long spreading codes (multicode transmission) is introduced for the DS-SS system to overcome the burstness of the interference. Moreover, inspired by the broadband in frequency of MWO interference, a technique to estimate the channel MWO interference by means of observing its levels in an adjacent channel is proposed, and this technique is applied to construct a multicode DS-SS receiver which can suppress the channel MWO interference. An evaluation of the Lit error rate performance of the proposed multicode DS-SS system is conducted bg computer simulation, and the numerical results demonstrate that the proposed DS-SS system can operate effectively even in the presence of MWO interference.

关键词： DS-SS multicode transmission MWO interference observation channel

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Generation of sets of sequences suitable for multicode transmission in quasi-synchronous CDMA systems

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IEICE TRANSACTIONS ON COMMUNICATIONS 2001年第3期E84B卷 576-580页

作者： Saito, M Yamazato, T Okada, H Katayama, M Ogawa, A Nagoya Univ Grad Sch Engn Nagoya Aichi 4648603 Japan Nagoya Univ Ctr Informat Studies Nagoya Aichi 4648603 Japan Meijo Univ Dept Informat Sci Nagoya Aichi 4688502 Japan

In this letter, we present a method to generate sets of sequences suitable for multicode transmission in quasi-synchronous (QS) CDMA systems. We focus on Gold code but extension to orthogonal Gold code is straightforward. We show that by appropriate classification of sequences, it is possible to have sets whose cross correlation is small in QS situations.

关键词： quasi-synchronous CDMA Gold code orthogonal Gold code multicode transmission

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Analysis of the adaptive modulation and coding algorithm with the multicode transmission

Analysis of the adaptive modulation and coding algorithm wit...

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56th IEEE Vehicular Technology Conference

作者： Kwan, R Chong, P Rinne, M Nokia Res Ctr FIN-00045 Helsinki Finland

ISBN: (纸本)0780374673

Adaptive Modulation and Coding (AMC) has gained a lot of attention in the research targeting for the standardization of the High Speed Downlink Packet Access (HSDPA) [1]. The idea is to adapt the transmission to-the-fast changing channel conditions by the use of different modulation and coding schemes (MCS). In this paper, an algorithm is presented for the AMC technique in the HSDPA concept with multicode transmission, and the mathematical analysis of this algorithm is given: Furthermore, a scheduling algorithm is introduced-in which the terminal in a queue with the best expected carrier-to-interference ratio (C/I) is selected for the transmission interval. Such maximum C/I scheduling with the AMC and multicode transmission is anticipated to increase the throughput. In this paper, the numerical results of the analysis are compared to the respective results obtained by the simulations.

关键词： WCDMA high speed downlink packet access HSDPA adaptive modulation and coding multicode transmission

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Dynamic rate and power adaptation for forward link transmission using high-order modulation and multicode formats in cellular WCDMA networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2005年第5期4卷 2361-2372页

作者： Kim, DI Hossain, E Bhargava, VK Simon Fraser Univ Sch Engn Sci Burnaby BC V5A 1S6 Canada Univ Manitoba Dept Elect & Comp Engn Winnipeg MB R3T 5V6 Canada Univ British Columbia Dept Elect & Comp Engn Vancouver BC V6T 1Z4 Canada

This paper addresses. the problem of dynamic rate and power adaptation for forward link data transmission using high-order modulation and multicode formats in cellular wideband code division multiple access (WCDMA) networks. A novel framework for dynamic joint adaptation of modulation order, number of code channels (hence transmission rate), and transmission power is proposed for downlink data transmission in a cellular WCDMA system where different users have similar frame error rate (FER) requirements. Based on a general downlink signal-to-interference ratio (SIR) model, the problem of optimal dynamic rate and power adaptation is formulated, for which the rate and power allocation can be found by an exhaustive search. Two heuristic-based dynamic rate and power allocation schemes are proposed. Performance of dynamic joint rate and power adaptation under the proposed framework is evaluated for a random micromobility model using computer simulations. Also, an analytical approach to evaluate the throughput performance of dynamic rate and power adaptation using high-order modulation and multicode formats is presented.

关键词： cellular wideband code division multiple access (WCDMA) dynamic rate and power adaptation frame fill efficiency high-order modulation multicode transmission

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Wireless P-MP transmission with multicode assignment algorithm

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS 2006年第8期89卷 14-25页

作者： Nakamura, H Shinkuma, R Takahashi, T Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan

The demand for video service in mobile communications systems is increasing. In response to this demand. wireless P-MP(Point-to-MultiPoint) videotransmission, in which a given video is transmitted to several moving terminals via a single channel, has been studied. This scheme can make effective use of bandwidth, power, and spreading codes. In this paper, as wireless P-MP video transmission schemes effective in the CDMA system, we propose MCAP (multicode Assignment algorithm For P-MP transmission) and the P-MP video transmission system. In MCAP, the mobile terminals receiving the identical video arc divided into two groups, high quality and low quality, based on the channel quality. By performing transmission power and transmission rate control for each group, the transmission rate call be improved. Also, by using multicode transmission, transmission rate control and the channel allocation are carried out in a unified fashion. In this paper, by means of simulations it is demonstrated that the proposed scheme can substantially improve the transmission rate without increasing the number of spreading codes and the power. Several schemes are compared as power control base selection schemes needed for MCAP. An optimum scheme is determined from the comparative evaluation results. (c) 2006 Wiley Periodicals. Inc.

关键词： wireless video transmission video quality control point-to-multipoint transmission CDMA multicode transmission

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Space-time spreading MIMO-CDMA downlink systems using constrained tensor modeling

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SIGNAL PROCESSING 2008年第10期88卷 2403-2416页

作者： de Almeida, Andre L. F. Favier, Gerard Mota, Joao C. M. Univ Nice Sophia Antipolis CNRS I3S Lab Nice France Univ Fed Ceara Wireless Telecom Res Grp Fortaleza Ceara Brazil

This paper considers the downlink of a multiple-input multiple-output (MIMO) code-division multiple-access (CDMA) system based on space-time spreading (STS) using multiuser/multicode transmission. A constrained tensor model is proposed for the STS l transmitted signal. The new STS model generalizes existing ones by allowing multiuser spatial multiplexing with different code reuse/multiplexing patterns for each user. This model is parametrized by two allocation matrices with variable Structure, which allow to control, respectively, the allocation of multiple data streams and spreading codes to the transmit antennas. A methodology is proposed to design these allocation matrices leading Blind detection to finite sets of feasible STS schemes with guaranteed blind symbol recovery. The construction of feasible STS schemes for 2, 3 and 4 transmit antennas is presented as an illustration of this methodology. A blind receiver based on the alternating least Squares algorithm is used for symbol recovery. The bit-error-rate performance of this receiver is tested and compared to some existing STS-based downlink transceivers. (C) 2008 Elsevier B.V. All rights reserved.

关键词： allocation matrices blind detection constrained tensor model downlink transmission MIMO-CDMA system multicode transmission space-time spreading

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Transmit Power Allocation for Successive Interference Cancellation in multicode MIMO Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2008年第12期56卷 2200-2213页

作者： Park, Chang Soon Lee, Kwang Bok Seoul Natl Univ Sch Elect Engn & Comp Sci Seoul 151742 South Korea

Multiple-input multiple-output (MIMO) system with multicode transmission can provide high speed data service's by transmitting independent parallel substreams from multiple antennas and through multicode channelization. In this paper, we first introduce an iterative two-stage successive interference cancellation (SIC) detection scheme for a multicode MIMO system. The proposed technique cancels the interference signals successively in the space domain followed by the code domain. Next, we develop various transmit power allocation schemes over different data substreams for the proposed detection process to improve error rate performance. The joint transmit power allocation is derived to make the post-detection signal-to-interference_ plus-noise ratio (SINR) become the same for all substreams in both the space and code domains. As a computationally efficient scheme, we propose a two-stage power allocation scheme, which allocates the total transmit power to the substreams in the code domain at the first stage, and allocates this code domain power to the substreams;in the space domain at the second stage. Furthermore, variable and constant power ratio (PR) schemes are derived to reduce the feedback overhead. In particular, the constant PR scheme utilizes the transmit power ratio determined by the long-term statistical properties of the fading channel amplitudes, and achieves significantly reduced feedback rate. Numerical results show that the proposed transmit power allocation schemes for the two-stage SIC significantly outperform the equal power allocation scheme.

关键词： Bit error rate (BER) multicode transmission multiple-input multiple-output (MIMO) systems successive interference cancellation (SIC) transmit power allocation

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A new multicarrier multicode DS-CDMA scheme for time and frequency selective fading channels

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JOURNAL OF COMMUNICATIONS AND NETWORKS 2005年第1期7卷 13-20页

作者： Cao, YW Tjhung, TT Ko, CC Univ Glamorgan Sch Comp Pontypridd CF37 1DL M Glam Wales Inst Infocomm Res Singapore Singapore Natl Univ Singapore Dept Elect & Comp Engn Singapore 117548 Singapore

In this paper, a new multicarrier, direct sequence code division multiple access (MC-DS-CDMA) system is proposed. Our new signal construction is based on convolutional encoding of the transmitted data, serial-to-parallel (S/P) conversion of the encoded data, Walsh-Hadamard-transformation (WHT), a second S/P conversion of the WHT outputs, spread spectrum (SS) modulation with a common pseudo-noise (PN) sequence, and then multicarrier transmission. The system bit error rate (BER) performance in frequency selective fading channel in the presence of additive white Gaussian noise (AWGN) and a jamming tone is analyzed and simulated. The numerical results are compared with those from an orthogonal MC-DS-CDMA system of Sourour and Nakagawa [7]. It is shown that the two systems have almost the same BER performance, but the proposed scheme has better anti-jamming ability.

关键词： DS-CDMA multicarrier CDMA system multicode transmission

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Constant amplitude signaling for parallel combinatory spread spectrum systems

Constant amplitude signaling for parallel combinatory spread...

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2nd International Workshop on Sequence Design and Its Applications in Communications

作者： Ohuchi, Kouji Shizuoka Univ Grad Sch Sci & Technol Hamamatsu Shizuoka 4328011 Japan

In this paper, a parallel combinatory spread spectrum (PC/SS) system using a constant amplitude signaling scheme is proposed. The amplitude of the transmitted signal from multicode transmission systems such as PC/SS systems have a large dynamic range which requires that amplifiers have a wide linearity in the transmitter. From a view point of power efficiency, however, it is reasonable to use non-linear amplifiers rather than linear ones. In that case, the bit error rate performance must degrade because of non-linear distortion. The proposed system can avoid influence of the non-linear amplifiers by making the transmitted signal have a constant amplitude. The bit error rate performance and the data transmission rate performance are investigated. They prove that the proposed system is an attractive candidate among the constant amplitude signaling systems.

关键词： multicode transmission parallel combinatory spread spectrum constant amplitude transmission non-linear amplifier

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Reduced complexity decorrelating detector for multicode system

Reduced complexity decorrelating detector for multicode syst...

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15th IEEE International Symposium on Personal, Indoor, Mobile, Radio Communications (PIMRC 2004)

作者： Krenz, R Poznan Tech Univ PL-60965 Poznan Poland

ISBN: (纸本)0780385233

In this paper a reduced complexity decorellating receiver for multicode system is investigated. It is similar to the classical decorellating detector used for multiuser detection, however, it operates on a short window and not on the entire transmitted frame. Consequently, it can be used for processing long frames with a moderate complexity and, therefore, can be applied to high-speed data communication systems.

关键词： multicode transmission multiuser detection decorellating receiver

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