Signal design and spectral efficiency in multi-carrier multiple access systems with PAPR as a parameter

2002 ◽  
Author(s):  
T. Ginige ◽  
N. Rajatheva ◽  
K.M. Ahmed
Keyword(s):  
Spectral Efficiency ◽  
Multiple Access ◽  
Signal Design

UWB Positioning Systsem Design: Selection of Modulation and Multiple Access Schemes

2007 ◽  
Vol 61 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Hui Yu ◽  
Enrique Aguado ◽  
Gary Brodin ◽  
John Cooper ◽  
David Walsh ◽  
...  
Keyword(s):  
Multiple Access ◽  
High Performance ◽  
Ultra Wideband ◽  
Good Time ◽  
Modulation Scheme ◽  
Positioning System ◽  
Indoor Environments ◽  
Signal Design ◽  
Positioning Systems ◽  
Design Selection

In densely-populated cities or indoor environments, limited visibility to satellites and severe multipath effects significantly affect the accuracy and reliability of satellite-based positioning systems. To meet the needs of “seamless navigation” in these challenging environments an advanced terrestrial positioning system is under development. This system is based upon Ultra-Wideband (UWB) technology, which is a promising candidate for this application due to good time domain resolution and immunity to multipath. This paper presents a detailed analysis of two key aspects of the UWB signal design that will allow it to be used as the basis of such a high performance positioning system: the modulation scheme and the multiple access technique. These two aspects are evaluated in terms of spectral efficiency and synchronisation performance over multipath channels. Thus this paper identifies optimal modulation and multiple access techniques for a long range, high performance terrestrial positioning system using UWB.

Subcarrier and Power Allocation Algorithm for Spectral Efficiency Maximization in Superposition Coding OFDMA Systems

2015 ◽  
Vol 24 (05) ◽  
pp. 1550061
Author(s):  
Mateus de Paula Marques ◽  
Taufik Abrão
Keyword(s):  
Power Allocation ◽  
Spectral Efficiency ◽  
Time Complexity ◽  
Multiple Access ◽  
Optimization Problem ◽  
Frequency Division ◽  
Superposition Coding ◽  
Ofdma System ◽  
Transmission Strategy ◽  
Throughput Gain

This paper addresses the optimization problem on subcarrier and power allocation of orthogonal frequency division multiple access (OFDMA) system under spectral efficiency (SE) metric when deploying superposition coding (SC) transmission strategy. An algorithm with polynomial time complexity, of the order of (UN log 2(N)) has been proposed for sub-optimal SE maximization. Results indicate that the system SE increases with the use of SC technique. Besides, the throughput gain with SC adoption increases when the number of users (U) approaches the number of subcarriers (N) available in the system.

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