检索结果-内蒙古大学图书馆

code division multiple access based on independent codes and turbo decoding

ANNALES DES TELECOMMUNICATIONS-ANNALS OF TELECOMMUNICATIONS 1999年第7-8期54卷 401-410页

作者： Brunel, L Boutros, J Ecole Natl Super Telecommun Commun & Elect Dept F-75634 Paris 13 France

We study a multiple access encoding/decoding algorithm based on iterative (turbo) decoding. The algorithm is suitable for both synchronous and asynchronous systems. The quasi-orthogonal pseudo-noise sequences of the DS-SSMA system are replaced by independent channel codes constructed by combining convolutional codes and random interleavers. The interference is rebuilt using soft output information. The results show that the iterative joint decoder is able to completely eliminate the co-channel interference. The performance of the multiple access system tends practically to that of a single user system.

关键词： code division multiple access direct sequence spectrum error correcting code decoding convolutional code interleaving iteration signal interference channel capacity numerical simulation system performance

来源：评论

学校读者我要写书评

暂无评论

code division multiple access Channel Resources Allocation with Applied Token Sub-Queuing for Wireless Multi-Service Packet Switch Traffics 2

Code Division Multiple Access Channel Resources Allocation w...

引用

2nd International Conference on Informatics, Engineering, Science, and Technology (INCITEST) - Building Competitive Advantage to Face Industry 4.0

作者： Lestariningati, S., I Agusdian, A. Univ Komputer Indonesia Comp Engn Kota Bandung Jawa Barat Indonesia Inst Teknol Bandung Sch Elect Engn & Informat Kota Bandung Jawa Barat Indonesia

The purpose of this paper is to determine the method of Channel Resources Allocation of wireless Multi-Service Packet Switch CDMA based. As it has been known, CDMA cell has a fluctuated capacity mainly due to its varying co-channel interference. The simulation is performed to shows the characteristic for Multi-Service Packet Switch traffic such combine CBR, VBR, and ABR users is applied on CDMA system. The idea is to deliver the traffics when capacity increase from assigned minimum value, by implementing Proposed Token Sub-Queue and Multi-Service Traffic Channel Resources Algorithm. In the first time, this method is aim for non-real time traffic such ABR traffic, but the simulation shows that it can be applied further to the real-time connection by prioritizing delaying the drop calls of certain agreed QoS values to re-seize into services. The simulation of proposed method shows better CDMA channel or bandwidth utilization, and suppresses drop call probability for real-time traffic.

关键词： code division multiple access

来源：评论

学校读者我要写书评

暂无评论

code division multiple access with adaptable reservation: A new paradigm for CDMA-based multimedia wireless networks

Code division multiple access with adaptable reservation: A ...

引用

7th IEEE International Symposium on Computers and Communications

作者： Yeh, CH Zhang, D Iltis, R Lee, H Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada

ISBN: (纸本)0769516718

An advantage of CDMA-based protocols is that packets can be transmitted immediately without prior channel access or resource reservation. In this paper however we propose to incorporate a reservation mechanism into CDMA-based protocols for next-generation wireless networks with data, voice, and multimedia applications. The resultant paradigm is called code division multiple access with adaptable reservation (CDMA/AR). The motivations for this change include that QoS guarantees can continue to be provisioned in CDMA/AR-based systems even when man), handoff mobile stations enter an already heavily utilized cell. Our simulation results and mathematical analysis show that the adaptable reservation and differentiated admission control mechanisms of CDMA/AR can considerably reduce the handoff-rejection and call-blocking rates for higher-priority traffic to very small values, while achieving throughput close to 100% at the same time..

关键词： code division multiple access

来源：评论

学校读者我要写书评

暂无评论

code division multiple access in Centimeter Accuracy Harmonic RFID Locating System

Code Division Multiple Access in Centimeter Accuracy Harmoni...

引用

作者： Hui, Xiaonan Ma, Yunfei Kan, Edwin C. Cornell University IthacaNY14850 United States Massachusetts Institute of Technology CambridgeMA02139 United States

In conventional passive UHF radio frequency identification (RFID) systems, time-division multiple access (TDMA) protocols are designed to counter inter-tag collision and multi-path interference for digital ID retrieval. However, high-accuracy (centimeter-level and below) localization to track multiple tags simultaneously still awaits a feasible solution. Overlap on the same carrier frequency of the downlink (from the reader to tags) and uplink (from tags to the reader) leads to severe self-jamming and reader collision, which makes tag localization especially difficult. The present narrow bandwidth also limits the localization accuracy and reliability. Starting from the polling process and synchronization by TDMA, we propose the code division multiple access within the broadband harmonic backscatter RFID system to enable the simultaneous real-time (15 Hz) tag localization with centimeter accuracy and millimeter deviation. We investigate the impacts of the number of tags with respect to the sampling rate, tag power consumption, and locating errors originated from the inter-tag collision, and then present an experimental prototype for verification. © 2017 IEEE.

关键词： code division multiple access

来源：评论

学校读者我要写书评

暂无评论

code division multiple access (CDMA) applicable for mobile satellite communications

Code Division Multiple Access (CDMA) applicable for mobile s...

引用

2011 International Siberian Conference on Control and Communications, SIBCON 2011

作者： Ilcev, Stojce Dimov Durban University of Technology Durban South Africa

ISBN: (纸本)9781457710681

This paper describes in particular code division multiple access (CDMA) applicable in Mobile Satellite Communications (MSC) connecting Mobile Earth Stations (MES) via Land Earth Stations (LES). However, in satellite communication systems, as a rule, especially in MSC many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users, however, can be solved by using multiple access (MA) technique. Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MA to the channel, such as example of the described CDMA. This generates a problem of summation and separation of Radio Frequency (RF) signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part. © 2011 IEEE.

关键词： code division multiple access

来源：评论

学校读者我要写书评

暂无评论

Performance analysis of quantum access network using code division multiple access model

引用

Chinese Physics B 2017年第6期26卷 37-41页

作者：胡林曦杨灿何广强 State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic EngineeringShanghai Jiao Tong University State Key Laboratory of Precision Spectroscopy East China Normal University State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of Sciences

A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently,the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise.

关键词： quantum access network chaotic phase shifter code division multiple access

来源：评论

学校读者我要写书评

暂无评论

Layered space-time receiver for downlink multiple-input multiple-output multi-carrier code division multiple access systems

引用

IET COMMUNICATIONS 2011年第13期5卷 1907-1917页

作者： Phasouliotis, A. So, D. K. C. Univ Manchester Sch Elect & Elect Engn Manchester Lancs England

Multi-carrier code division multiple access (MC-CDMA) allows multiuser communication with frequency diversity. To increase the system data rates, spatial multiplexing for multiple-input multiple-output (MIMO) MC-CDMA has been investigated. This study proposes a chip level layered space-time (LST) receiver architecture for coded downlink MIMO MC-CDMA systems. As the conventional chip level ordered successive interference cancellation (OSIC) receiver is unable to overcome multiple access interference and performs poorly in multiuser scenarios, the proposed receiver cancels both spatial and multiuser interference in an ordered LST detection process by requiring only the knowledge of the desired user's spreading sequence. Simulation results show that the proposed receiver not only performs better than the existing linear detectors but also outperforms both the chip and symbol level OSIC receivers. In this study the authors also compare the error rate performance between the proposed system and MIMO orthogonal frequency division multiple access (MIMO OFDMA) system and they justify the comparisons by deriving and analysing the pairwise error probability (PEP) for both systems. MIMO MC-CDMA demonstrates a better performance over MIMO OFDMA under low system load. If all users' spreading sequences are known, multiuser interference can be reduced and MIMO MC-CDMA performs better than MIMO OFDMA at all system loads.

关键词： PEP Electromagnetic compatibility and interference symbol level OSIC receivers Communication switching frequency diversity space division multiplexing MIMO OFDMA system multiuser scenarios chip level layered space-time receiver architecture downlink multiple-input multiple-output multicarrier code division multiple access systems error statistics linear detectors spatial multiplexing probability Modulation and coding methods code division multiple access Other topics in statistics multiple access interference diversity reception OFDM modulation multiuser communication multiple access communication MIMO orthogonal frequency division multiple access system multiuser detection Signal detection system data rates radio receivers error rate performance spreading sequence LST detection process frequency division multiple access pairwise error probability conventional chip level ordered successive interference cancellation receiver coded downlink MIMO MC-CDMA systems multiple-input multiple-output MC-CDMA Radio links and equipment low system load multiuser interference spatial interference LST receiver architecture MIMO communication interference suppression

来源：评论

学校读者我要写书评

暂无评论

Performance analysis of asynchronous optical code division multiple access with spectral-amplitude-coding

引用

IET COMMUNICATIONS 2014年第6期8卷 956-963页

作者： Sedaghat, Mohammad Ali Muller, Ralf R. Marvasti, Farokh Norwegian Univ Sci & Technol NTNU Dept Elect & Telecommun Trondheim Norway Univ Erlangen Nurnberg Dept Elect Elect & Commun Engn D-91054 Erlangen Germany Sharif Univ Technol Dept Elect Engn Tehran Iran

In this study, the performance of a spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) system in the asynchronous regime is evaluated using a Gaussian approximation of the decision variable for codes with fixed cross-correlation used in SAC-OCDMA systems. The authors consider the effect of phase-induced intensity noise (PIIN), thermal noise and shot noise. Moreover, the validity of the Gaussian approximation is confirmed by a Kolmogorov-Smirnov fitness test. For sake of comparison, the bit error rate (BER) of the asynchronous SAC-OCDMA system is also plotted numerically in comparison with the BER of the synchronous SAC-OCDMA. They show that a SAC-OCDMA system without any time management for the users, that is, the asynchronous regime, has a better performance than the synchronous SAC-OCDMA when PIIN effect exists.

关键词： code division multiple access code division multiplexing Gaussian noise approximation theory phase coding phase noise thermal noise shot noise error statistics asynchronous SAC-OCDMA system BER bit error rate Kolmogorov-Smirnov fitness test shot noise thermal noise PIIN phase-induced intensity noise cross-correlation system Gaussian approximation spectral-amplitude-coding asynchronous optical code division multiple access

来源：评论

学校读者我要写书评

暂无评论

Orthogonal short codes for code division multiple access networks

引用

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 1996年第4期7卷 297-304页

作者： Kanj, K Elhakeem, AK LeNgoc, T Dept. of Elec. & Comp. Eng. Concordia University 1455 De Maisonneuve Blvd. (West) Montreal Quebec H3G 1M8 Canada

Short codes are known to hale better balance and spectral characteristics than their long counterparts. In this work we show by simulations that for certain users loads their bit error performance are excellent. A CDMA network performance is investigated under different load and fading situations. We also investigate the effects of using orthogonal codewords in conjunction with concatenated short codes to further reduce the multi-user interference in these networks.

关键词： Orthogonal code division multiple access Multi-user Interference code division variable amplitude loading error performance codes CONJUNCTION Network spectral characteristic

来源：评论

学校读者我要写书评

暂无评论

Iterative low-complexity multi-user detection for asynchronous multi-sequence signalling based bit-interleaved coded modulation code division multiple access systems

引用

IET COMMUNICATIONS 2007年第4期1卷 628-637页

作者： Tseng, D-F. Lu, K-C. Natl Taiwan Univ Sci & Technol Dept Elect Engn Taipei 106 Taiwan

An uplink direct sequence spread spectrum communications systems employing a multi-sequence model over a quasi-static frequency-selective fading channel is considered. In analogy with bit-interleaved coded modulation (BICM) technique, a group of bits at the output of a bit-wise interleaver is mapped uniquely to a complex signalling vector belonging to an orthogonal plane sequence modulation signal space, which is constructed over a set of expanded signature sequences. This transmission system provides not only bandwidth efficiency offered by additional signal planes but also time diversity resulting from the BICM technique. It is observed that at high system traffic load error performance could degrade substantially due to user cross-correlations, multi-access asynchronism as well as channel frequency selectivity. The authors employ a 'turbo principle' receiver, consisting of a soft interference cancellation scheme, soft demappers and maximum a posteriori decoders, to avert this capacity loss by exploiting the serially concatenating structure at the transmitter. After simple mathematical manipulation, a soft space-time linear minimum mean-square error multi-user detector could even be explored on the basis of per signal plane per user. Both analytical performance-bound and computer simulation of the proposed framework in terms of bit-error rate (BER) are revealed. Further, performance comparisons with convolutionally coded and conventional bandwidth-efficient coded direct sequence code division multiple access systems under the same system conditions are illustrated. The authors have also investigated the impact of labelling maps on the BER performance.

关键词： multiuser detection space-time linear minimum mean-square error multiuser detector code division multiple access systems fading channels turbo principle receiver modulation coding telecommunication traffic system traffic load error code division multiple access least mean squares methods quasi-static frequency-selective fading channel direct sequence spread spectrum communications systems asynchronous multisequence signalling iterative low-complexity multiuser detection bit-interleaved coded modulation soft interference cancellation scheme interference suppression soft demappers error statistics bit-error rate bandwidth efficiency spread spectrum communication telecommunication signalling maximum a posteriori decoders

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：