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Channel adaptive fair queueing for scheduling integrated voice and data services in multicode CDMA systems

COMPUTER COMMUNICATIONS 2004年第9期27卷 809-820页

作者： Wang, L Kwok, YK Lau, WC Lau, VKN Univ Hong Kong Dept Elect & Elect Engn Hong Kong Hong Kong Peoples R China

Code Division Multiple Access (CDMA) systems continue to be critical building blocks of future high performance wireless and mobile computing systems. While CDMA systems are very mature for voice services, their potentials in delivering high quality data services (e.g. multimedia messaging services) are yet to be investigated. One of the most crucial components in an advanced wideband CDMA system is the judicious allocation of band width resources to both voice and high data rate services so as to maximize utilization while satisfying the respective quality of service requirements. Specifically, in a multicode CDMA system, the goal is to intelligently allocate codes to the users' requests. While previous work in the literature has addressed this problem from a capacity point of view, the fairness aspect, which is also important from the users' point of view, is largely ignored. In this paper, we propose a new code allocation approach that is channel adaptive and can guarantee fairness with respect to the users' channel conditions. Simulation results show that our approach is more effective than the proportional fair approach. (C) 2004 Elsevier B.V. All rights reserved.

关键词： wireless multicode code division multiple access scheduling rate allocation fairness channel adaptive

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Channel assignment with QoS guarantees for a multiclass multicode CDMA system

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2002年第5期51卷 935-948页

作者： Do, MS Park, Y Lee, JY Yonsei Univ Dept Elect & Elect Engn Seoul 120749 South Korea Columbia Univ Dept Elect Engn New York NY 10027 USA

In a wireless system that supports multimedia services, each traffic requires different quality of service (QoS) at both communication on radio links and connection admission. In this paper, we initially derive the uplink capacity satisfying the QoS constraint on radio links in a multiclass multicode code-division multiple-access (CDMA) system. Based on the derived capacity, the number of channel elements, which is one of the system resources, is determined. Then, we define the QoS parameters associated with connection processes. To guarantee the defined QoS at connection level, under given channel elements, we propose a channel-assignment scheme with dynamic priority adjustment (DPA). The proposed scheme gives multipriority to different traffic classes. Real-time classes can preempt non-real-time classes with restricted preemptive priority, Such restriction is regulated by preemption-free code channels and a buffer threshold for non-real-time classes. Among real-time classes, different priorities are assigned to each traffic class by code reservation parameters. These multipriority parameters are dynamically adjusted in order to guarantee different QoS requirements. We analyze the DPA scheme by the matrix-geometric method, and evaluate the performance of each traffic class. The results show that the proposed scheme flexibly guarantees QoS depending on traffic loading condition and achieves high channel, utilization.

关键词： code-division multiple access (CDMA) dynamic priority adjustment (DPA) multicode multipriority quality of service (QoS) guarantee uplink capacity

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Optimal power distribution control for multicode MC-CDMA with zero-forcing successive interference cancellation

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EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2005年第5期2005卷 718-729页

作者： Tan, MZ Ibars, C Bar-Ness, Y Agere Syst Allentown PA 18109 USA Ctr Tecnol Telecommun Catalunya Barcelona 08034 Spain New Jersey Inst Technol Ctr Commun & Signal Proc Res Dept Elect & Comp Engn Newark NJ 07102 USA

Multicarrier CDMA (MC-CDMA) has become a promising candidate for future wireless multimedia communications for its robustness to frequency-selective fading and its flexibility in handling multiple data rates. Among different multirate access schemes, multicode MC-CDMA is attractive for its high performance, good flexibility in rate matching, and low complexity. However, its performance is limited by self-interference (SI) and multiuser interference (MUI). In this paper, a zero-forcing successive interference cancellation (ZF-SIC) receiver is used to mitigate this problem for multicode MC-CDMA. Furthermore, optimal power distribution control (PDC), which minimizes each user's bit error rate (BER), is considered. Our results show that, in correlated Rayleigh fading channels, the ZF-SIC receiver integrated with the optimal PDC dramatically improves the performance of the multicode MC-CDMA system in comparison with other receivers proposed in the literature. Moreover, the optimal PDC significantly outperforms the PDC based on equal BER criterion, particularly under a short-term transmit power constraint.

关键词： multicode multicarrier CDMA zero-forcing successive interference cancellation power distribution control

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Linear Equalization for multicode MC-CDMA Downlink Channels

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IEEE COMMUNICATIONS LETTERS 2012年第9期16卷 1353-1356页

作者： Rugini, Luca Univ Perugia DIEI I-06125 Perugia Italy

We investigate multirate multicarrier code-division multiple-access (MC-CDMA) downlink systems with multicode transmission. Specifically, we design a new linear equalizer that outperforms the minimum mean-squared error (MMSE) percarrier equalizer, without requiring the spreading codes of the interfering users. The complexity of this new linear equalizer is similar to that of the MMSE per-user equalizer, which however needs the spreading codes of the interfering users. Simulation results validate the effectiveness of the proposed equalizer, especially when there are few interfering users.

关键词： Downlink equalization multicarrier code-division multiple access (MC-CDMA) multicode multirate

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Precise analysis of bit-error probability for asynchronous multicode DS-CDMA systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2006年第4期54卷 637-647页

作者： Lee, SJ Beaulieu, NC Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 2V7 Canada

A precise bit-error probability (BEP) analysis method is derived for a multicode direct-sequence code-division multiple:access (DS-CDMA) system in an additive white Gaussian noise channel. The method is applicable to a multicode DS-CDMA system with an arbitrary number of multiple code sequences, and any selection of multiple code sequences. The precise method gives results that discriminate the effect of the selection of different multiple code sequences on the BEP, whereas Gaussian approximations (GAs) do not. Thus, the new method can be used to select the best multicode set for a given system, a task that cannot be achieved using GAS. A two-step analytical procedure enables deriving an explicit, compact form for the CF of the receiver decision statistic in a DS-CDMA system with an arbitrary number of multiple code sequences, and for any selection of multiple code sequences.

关键词： bit-error probability (BEP) characteristic function (CF) code-division multiple access (CDMA) Gaussian approximation (GA) multicode spread spectrum multiple access (SSMA)

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An Efficient multicode Design for Real Time QoS Support in OVSF Based CDMA Networks

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WIRELESS PERSONAL COMMUNICATIONS 2016年第4期90卷 1799-1810页

作者： Saini, Davinder S. Balyan, Vipin Chandigarh Coll Engn Dept Elect & Commun Engn Chandigarh 160019 Punjab India Cape Peninsula Univ Technol Dept Elect Elect & Comp Engn ZA-7535 Cape Town Western Cape South Africa

Orthogonal variable spreading factor (OVSF) codes are used for CDMA based networks to handle multimedia rates. While waiting time (or call establishment delay) is a significant QoS parameter for real time calls, its impact on non-real time calls is negligible. Traditionally, the call handling in OVSF based CDMA system has been accomplished with multi code approach, where the arriving call is divided into many quantized fractions and each fraction is handled by different code. These designs are very efficient for non-real time calls, but the code search corresponding to each fraction needs significant time that makes existing multi code approaches unsuitable for real time calls. This paper describes a novel multi code design, in which the waiting time for real time call is zero. The design initially assigns the incoming call to the vacant code with the capacity equal to call capacity, and subsequently looks for the vacant codes for each quantized fraction after code assignment. Once the vacant codes with capacities equal to the capacity of all rate fractions are available, the call is shifted to these codes. The information of this code assignment for every fraction needs to be sent to the receiver like existing schemes. Therefore, there is no additional hardware requirement for the proposed design. Simulation results show significant dominance of our scheme as compared to the existing multi code schemes.

关键词： OVSF Rake Real time call Non-real time call OVSF code tree multicode

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Performance Analysis of multicode OCDM Networks Supporting Elastic Transmission With QoS Differentiation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2016年第2期64卷 741-752页

作者： Farghal, Ahmed E. A. Shalaby, Hossam M. H. Kato, Kazutoshi Pokharel, Ramesh K. E JUST Dept Elect Commun Engn Alexandria 21934 Egypt Kyushu Univ Grad Sch Informat Sci & Elect Engn Fukuoka 8190395 Japan

A multicode optical code-division multiplexing (OCDM) is proposed to support the dynamic changes in the requested traffic demand in OCDM networks by adapting the number of allocated codes according to the requested transmission rate. In order to support time-variant data rates and multiservice transmissions;a multicode variable-weight 2D one-coincidence frequency hopping code/optical orthogonal code (OCFHC/OOC) is employed as the signature code in the proposed system. Two multicode assignment methods, namely, random multicode assignment (RMA) policy and uniform multicode assignment (UMA) policy, are presented. For each code assignment method, we drive the probability density function (pdf) of the number of active codes in each wavelength group. The bit error probability (BEP), the probability of degradation, and the blocking probability are derived as network performance key parameters. The proposed system has a simplified routing and code assignment process with a lower blocking probability. Our numerical results indicate that the network teletraffic capacity and blocking probability can be improved significantly using UMA policy and call admission control.

关键词： Optical code-division multiplexing (OCDM) multicode blocking probability QoS spectral efficiency

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Performance analysis of wavelet packet multirate multicarrier multicode CDMA for wireless multimedia communications

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2014年第4期68卷 291-300页

作者： Akho-Zahieh, Maryam M. Abdellatif, Nasser Appl Sci Private Univ Dept Elect & Comp Engn Amman 11931 Jordan

Different kinds of Multirate (MR) communication systems, such as multicode (MCD) scheme and variable spreading length (VSL) schemes, have been considered for accommodating information sources with different data rates in Multicarrier code-division multiple access (MC-CDMA). In this paper, we propose the use of MCD scheme for MR services in MC/MCD-CDMA system that employs wavelet packets (WPs) as subcarriers. The bit error rate (BER) performance for the system was investigated by means of analytical methods and numerical results in a slow fading frequency selective Nakagami channel. The performance analysis includes the effects of diversity techniques, channel intensity profile, diversity order and fading parameter. Also, the effects of different service rates and number of users in each service rate were investigated. The performance of the system was compared to that of MC/MCD-CDMA based on sinusoidal carrier. Results reveal that BER performance is proportional to the service rate and our proposed system outperform the other system. (C) 2013 Elsevier GmbH. All rights reserved.

关键词： Multirate multicode Wavelet packet Multicarrier CDMA

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Performance evaluation of a rapid molecular diagnostic, multicode based, sample-to-answer assay for the simultaneous detection of Influenza A, B and respiratory syncytial viruses

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JOURNAL OF CLINICAL VIROLOGY 2016年 85卷 65-70页

作者： Voermans, Jolanda J. C. Seven-Deniz, S. Fraaij, P. L. A. van der Eijk, Annemiek A. Koopmans, M. P. G. Pas, Suzan D. Erasmus MC Dept Virosci Room Na1017Wytemanweg 80 NL-3015 CE Rotterdam Netherlands Erasmus MC Dept Pediat Rotterdam Netherlands

Background: Clinical signs and symptoms of different airway pathogens are generally indistinguishable, making laboratory tests essential for clinical decisions regarding isolation and antiviral therapy. Immunochromatographic tests (ICT) and direct immunofluorescence assays (DFA) have lower sensitivities and specificities than molecular assays, but have the advantage of quick turnaround times and ease-of-use. Objective: To evaluate the performance of a rapid molecular assay, ARIES FluA/B & RSV, using laboratory developed RT-PCR assays (LDA), ICT (BinaxNOW) and DFA. Methods: Analytical and clinical performance were evaluated in a retrospective study arm (stored respiratory samples obtained between 2006-2015) and a prospective study arm (unselected fresh clinical samples obtained between December 2015 and March 2016 tested in parallel with LDAs). Results: Genotype inclusivity and analytical specificity was 100%. However, ARIES was 0.5 log, 1-2logs and 2.5logs less sensitive for fluA, RSV and fluB respectively, compared to LDA. In total, 447 clinical samples were included, of which 15.4% tested positive for fluA, 9.2% for fluB and 26.0% for RSV, in both LDA and ARIES. ARIES clinical sensitivity compared to LDA was 98.6% (fluA), 93.3% (fluB) and 95.1% (RSV). Clinical specificity was 100% for all targets. ARIES detected 10.6% (4 fluA, 8 fluB, 11 RSV) and 26.9% (7 fluA, 3 fluB, 22 RSV) more samples compared to DFA and ICT, all confirmed by LDA. Conclusion: Although analytically ARIES is less sensitive than LDA, the clinical performance of the assay in our tertiary care setting was comparable, and significantly better than that of the established rapid assays. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Aries luminex Real-time PCR multicode Point of impact Rapid test Direct immunofluorescence assay DFA Immunochromatography test ICT

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On codes with low peak-to-average power ratio for multicode CDMA

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IEEE TRANSACTIONS ON INFORMATION THEORY 2004年第3期50卷 550-559页

作者： Paterson, KG Hewlett Packard Labs Bristol BS34 8QZ Avon England

Codes which reduce the peak-to-average power (PAPR) in multicode code-division multiple-access (MC-CDMA) communications systems,are systematically studied. The problem of designing such codes is reformulated as a new coding-theoretic problem: codes with low PAPR are ones in which the codewords are far from the first-order Reed-Muller code. Bounds on the tradeoff between rate, PAPR, and error-correcting capability of codes for MC-CDMA follow. The connections between the code design problem, bent functions, and algebraic coding theory (in particular, the Kerdock codes and Delsarte-Goethals codes) are exploited to construct code families with flexible parameters for the small values of n of practical interest. In view of their algebraic structure, these codes enjoy efficient encoding and decoding algorithms. The correspondence concludes by listing open problems in algebraic coding theory and Boolean functions motivated by the correspondence.

关键词： Bent function code-division multiple access (CDMA) envelope Kerdock multicode power rate adaptation Reed-Muller codes Walsh-Hadamard transform

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