Reduction of the near-far effect in mobile communication systems with Code-Division Multiple-Access

2006 ◽  
Author(s):  
Magdalena Purchla
Keyword(s):  
Mobile Communication ◽  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Mobile Communication Systems ◽  
Code Division Multiple

scholarly journals Link budget comparison of different mobile communication systems based on EIRP and EISL

2005 ◽  
Vol 2 ◽  
pp. 127-133 ◽  
Author(s):  
G. Fischer ◽  
F. Pivit ◽  
W. Wiebeck
Keyword(s):  
Mobile Communication ◽  
Communication Systems ◽  
Multiple Access ◽  
Mobile Communication Systems ◽  
Air Interface ◽  
Sensitivity Level ◽  
Link Budget ◽  
Code Division Multiple ◽  
Time Division ◽  
Effective Sensitivity

Abstract. The metric EISL (Equivalent Isotropic Sensitivity Level) describing the effective sensitivity level usable at the air interface of a mobile or a basestation is used to compare mobile communication systems either based on time division or code division multiple access in terms of coverage and emission characteristics. It turns out that systems that organize the multiple access by different codes rather than different timeslots run at less emission and offer greater coverage.

PROSPECTS FOR MOBILE COMMUNICATION SYSTEMS AND KEY TECHNOLOGIES CAPABLE OF SUPPORTING EXPANDING MOBILE MULTIMEDIA SERVICES

2004 ◽  
Vol 13 (02) ◽  
pp. 237-251
Author(s):  
MASAHIRO MINOMO ◽  
TATSURO MASAMURA
Keyword(s):  
Mobile Communication ◽  
Code Division Multiple Access ◽  
Communication Systems ◽  
Base Stations ◽  
Mobile Multimedia ◽  
Multimedia Services ◽  
Mobile Communication Systems ◽  
Research Activities ◽  
Air Interface ◽  
Code Division Multiple

The first commercial service of the 3rd generation (3G) mobile communication system, IMT-2000 (International Mobile Telecommunications), was launched in October 2001 in Japan. This is the first 3G service employing Wideband Code Division Multiple Access (W-CDMA) as its air interface between mobile terminals and base stations. This new system, 3G, is expected to accelerate the deployment of future mobile multimedia services, which substantially got started with the "i-mode" service in February 1999 in Japan. Research activities into future mobile communication systems capable of supporting a vastly expanded market for mobile multimedia services are underway worldwide. This paper describes the vision, service trends, and technical challenges of such future systems. Broadband packet wireless access, Variable Spreading Factor Orthogonal Frequency and Code Division Multiplexing (VSF-OFCDM), are promising candidates for realizing future mobile communication systems that provide higher transmission rates and capacity than 3G systems.

scholarly journals Large deviations for eigenvalues of sample covariance matrices, with applications to mobile communication systems

2008 ◽  
Vol 40 (04) ◽  
pp. 1048-1071
Author(s):  
Anne Fey ◽  
Remco van der Hofstad ◽  
Marten J. Klok
Keyword(s):  
Mobile Communication ◽  
Communication Systems ◽  
Large Deviation ◽  
Covariance Matrices ◽  
Mobile Communication Systems ◽  
Sample Covariance Matrices ◽  
Sample Covariance ◽  
Standard Normal ◽  
Rate Functions ◽  
Code Division Multiple

We study sample covariance matrices of the form W = (1 / n) C C T, where C is a k x n matrix with independent and identically distributed (i.i.d.) mean 0 entries. This is a generalization of the so-called Wishart matrices, where the entries of C are i.i.d. standard normal random variables. Such matrices arise in statistics as sample covariance matrices, and the high-dimensional case, when k is large, arises in the analysis of DNA experiments. We investigate the large deviation properties of the largest and smallest eigenvalues of W when either k is fixed and n → ∞ or k n → ∞ with k n = o(n / log log n), in the case where the squares of the i.i.d. entries have finite exponential moments. Previous results, proving almost sure limits of the eigenvalues, require only finite fourth moments. Our most explicit results for large k are for the case where the entries of C are ∓ 1 with equal probability. We relate the large deviation rate functions of the smallest and largest eigenvalues to the rate functions for i.i.d. standard normal entries of C . This case is of particular interest since it is related to the problem of decoding of a signal in a code-division multiple-access (CDMA) system arising in mobile communication systems. In this example, k is the number of users in the system and n is the length of the coding sequence of each of the users. Each user transmits at the same time and uses the same frequency; the codes are used to distinguish the signals of the separate users. The results imply large deviation bounds for the probability of a bit error due to the interference of the various users.

scholarly journals Constructions of asymptotically optimal codebooks with respect to Welch bound and Levenshtein bound

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Gang Wang ◽  
Deng-Ming Xu ◽  
Fang-Wei Fu
Keyword(s):  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Cross Correlation ◽  
Hadamard Matrices ◽  
Circulant Matrices ◽  
Asymptotically Optimal ◽  
Welch Bound ◽  
Construction Methods ◽  
Code Division Multiple

<p style='text-indent:20px;'>Codebooks with small maximum cross-correlation amplitudes are used to distinguish the signals from different users in code division multiple access communication systems. In this paper, several classes of codebooks are introduced, whose maximum cross-correlation amplitudes asymptotically achieve the corresponding Welch bound and Levenshtein bound. Specially, a class of optimal codebooks with respect to the Levenshtein bound is obtained. These classes of codebooks are constructed by selecting certain rows deterministically from circulant matrices, Fourier matrices and Hadamard matrices, respectively. The construction methods and parameters of some codebooks provided in this paper are new.</p>

scholarly journals LARGE-SCALE MIMO MC-CDMA SYSTEM USING COMBINED MULTIPLE BEAMFORMING AND SPATIAL MULTIPLEXING

2018 ◽  
Vol 56 (1) ◽  
pp. 102 ◽  
Author(s):  
Nguyen Huu Trung ◽  
Doan Thanh Binh
Keyword(s):  
System Performance ◽  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Large Scale ◽  
Spatial Multiplexing ◽  
Propagation Loss ◽  
Fifth Generation ◽  
Simulation Results ◽  
Code Division Multiple

This paper proposes a novel Large-scale (massive) Multi-input Multi-output Multi-carrier Code division multiple access (LS MIMO MC-CDMA) model and application to Fifth-Generation Mobile Communication Systems (5G). This system uses combined cylindrical array antenna multiple beamforming architecture with spatial multiplexing. The model is optimized by Min-Max criteria in order to minimize side lobes and maximize compression of propagation loss. The Monte Carlo simulation results unify with the analytical solution for system performance.

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