Iterative Detection and Estimation for Multiple Access Interference Mitigation in Asynchronous Frequency-Hop Spread Spectrum

MILCOM 2006 ◽  
2006 ◽  
Author(s):  
Xing Tan ◽  
John Shea
Keyword(s):  
Spread Spectrum ◽  
Multiple Access ◽  
Interference Mitigation ◽  
Multiple Access Interference ◽  
Iterative Detection ◽  
Detection And Estimation

scholarly journals Incremental gradient algorithm for multiuser detection in multi-carrier DS-CDMA system under modulation schemes

2018 ◽  
Vol 7 (2.6) ◽  
pp. 311
Author(s):  
Sumitra N. Motade ◽  
Anju V. Kulkarni
Keyword(s):  
Spread Spectrum ◽  
Multiple Access ◽  
Minimum Mean Square Error ◽  
Multiple Access Interference ◽  
Gradient Algorithm ◽  
Channel Noise ◽  
Cdma System ◽  
Communication Performance ◽  
Optimum Performance ◽  
Code Division Multiple

Nowadays, Multicarrier Direct sequence code division multiple access (MC DS-CDMA) systems are used in mobile communication. Performance of these systems are limited by multiple access interference (MAI) created by spread-spectrum users in the channel as well as background channel noise. This paper proposes an incremental gradient descent (IGD) multi-user detection (MUD) for MC DS-CDMA system that can achieve near-optimum performance while the number of users is linear in its implementation complexity.  The IGD algorithm make an effort to perform optimum MUD by updating one user's bit decision each iteration in the best way. This algorithm accelerates the gradient algorithm convergence by averaging. When a minimum mean square error (MMSE) MUD is employed to initialize the proposed algorithm, in all cases tested the gradient search converges to a solution with optimum performance. Further, the iterative tests denote that the proposed IGD algorithm provides significant performance for cases where other suboptimum algorithms perform poorly. Simulation compares the proposed IGD algorithm with the conventional detectors. 

The Wireless Application of Spread-Spectrum OFDM Technology in the Internet of Things

2013 ◽  
Vol 756-759 ◽  
pp. 1793-1797
Author(s):  
Han Cheng Liao
Keyword(s):  
Internet Of Things ◽  
Spread Spectrum ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
High Rate ◽  
Future Application ◽  
The Internet ◽  
Decision Variable ◽  
Wireless Application ◽  
The Internet Of Things

Lots of data have to be transferred in the internet of things at high rate. Using spectrum spreaded by LAS multiple access codes and orthogonal subcarriers, spread-spectrum OFDM system integrates both technologies. When it is elaborately designed, the inter-symbol interference and multiple access interference are eliminated to a large extent. In the environment of fading channel, the decision variable of the receiver is given. This kind of wireless or mobile communication system has good performance so that it is very useful in the future application especially in the internet of things.

Novel Scheme for Multiple-Access Interference Mitigation with Low Complexity

2011 ◽  
Vol 143-144 ◽  
pp. 371-375
Author(s):  
Zuo Liang Yin ◽  
Hui Xiao Ma ◽  
Xing Peng Mao ◽  
Jun Cai
Keyword(s):  
Multiple Access ◽  
Interference Mitigation ◽  
Multiple Access Interference ◽  
Low Complexity ◽  
System Capacity ◽  
Error Performance ◽  
Multiuser Detector ◽  
Access Scheme ◽  
Lower Complexity

To mitigate multiple access interference and improve the system capacity, an effective multiple access scheme, called GCDMA, is proposed. Exploiting the IDMA iterative multiuser detector in each group, the intra-group interference can be effectively handled. Analysis and simulations demonstrate that the proposed technique outperforms the conventional CDMA in terms of both system capacity and bit error performance. Lower complexity of the proposed scheme can be achieved than CDMA and even IDMA.

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