Generalisation of code division multiple access systems and derivation of new bounds for the sum capacity

Shayan Dashmiz; Mohammad Reza Takapoui; Sajjad Moazeni; Mehrdad Moharrami; Melika Abolhasani; Farokh Marvasti

doi:10.1049/iet-com.2013.0344

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Generalisation of code division multiple access systems and derivation of new bounds for the sum capacity

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Generalisation of code division multiple access systems and derivation of new bounds for the sum capacity

Shayan Dashmiz, Mohammad Reza Takapoui, Sajjad Moazeni, Mehrdad Moharrami, Melika Abolhasani and Farokh Marvasti

IET communications, Vol.8(2), pp.153-162

01/2014

DOI: 10.1049/iet-com.2013.0344

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Abstract

In this study, the authors explore a generalised scheme for the synchronous code division multiple access (CDMA). In this scheme, unlike the standard CDMA systems, each user has different codewords for communicating different messages. Two main problems are investigated. The first problem concerns whether uniquely detectable overloaded matrices (an injective matrix, i.e. the inputs and outputs are in one‐to‐one correspondence depending on the input alphabets) exist in the absence of additive noise, and if so, whether there are any practical optimum detectors for such input codewords. The second problem is about finding tight bounds for the sum channel capacity. In response to the first problem, the authors have constructed uniquely detectable matrices for the generalised scheme and the authors have developed practical maximum likelihood detection algorithms for such codes. In response to the second problem, lower bounds and conjectured upper bounds are derived. The results of this study are superior to other standard overloaded CDMA codes since the generalisation can support more users than the previous schemes.

channel capacity

code division multiple access

codes

codewords

conjectured upper bounds

detectable overloaded matrices

generalised scheme

injective matrix

matrix algebra

maximum likelihood detection

maximum likelihood detection algorithms

one‐to‐one correspondence

overloaded CDMA codes

standard CDMA systems

sum channel capacity

synchronous code division multiple access

Details

Title: Subtitle: Generalisation of code division multiple access systems and derivation of new bounds for the sum capacity
Creators: Shayan Dashmiz - London School of Economics and Political Science
Mohammad Reza Takapoui - Samford University
Sajjad Moazeni - University of California, Berkeley
Mehrdad Moharrami - Sharif University of Technology
Melika Abolhasani - University of Maryland
Farokh Marvasti - Sharif University of Technology
Resource Type: Journal article
Publication Details: IET communications, Vol.8(2), pp.153-162
DOI: 10.1049/iet-com.2013.0344
ISSN: 1751-8628
eISSN: 1751-8636
Publisher: The Institution of Engineering and Technology
Number of pages: 10
Grant note: INSF (Iran National Science Foundation)
Language: English
Date published: 01/2014
Academic Unit: Computer Science
Record Identifier: 9984446278002771

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