Abstract
The problem of designing bittopattern mappings and power allocation schemes for orthogonal frequencydivision multiplexing (OFDM) systems that employ subcarrier index modulation (IM) is considered. We assume that the binary source conveys a stream of independent, uniformly distributed bits to the pattern mapper, which introduces a constraint on the pattern transmission probability distribution that can be quantified using a binary tree formalism. Under this constraint, we undertake the task of maximizing the achievable rate subject to the availability of channel knowledge at the transmitter. The optimization variables are the pattern probability distribution (i.e., the bittopattern mapping) and the transmit powers allocated to active subcarriers. To solve the problem, we first consider the relaxed problem where pattern probabilities are allowed to take any values in the interval [0, 1] subject to a sum probability constraint. We develop (approximately) optimal solutions to the relaxed problem by using new bounds and asymptotic results, and then use a novel heuristic algorithm to project the relaxed solution onto a point in the feasible set of the constrained problem. Numerical analysis shows that this approach is capable of achieving the maximum mutual information for the relaxed problem in low A nd highSNR regimes and offers noticeable benefits in terms of achievable rate relative to a conventional OFDMIM benchmark.
Original language  English 

Article number  8704951 
Pages (fromto)  12701285 
Number of pages  16 
Journal  IEEE Journal of Selected Topics in Signal Processing 
Volume  13 
Issue number  6 
Early online date  2 May 2019 
DOIs  
Publication status  Published  1 Oct 2019 
Externally published  Yes 
Bibliographical note
This work is licensed under a Creative Commons Attribution 3.0 License. For more information, see http://creativecommons.org/licenses/by/3.0/.Keywords
 Modulation
 Binary trees
 Encoding
 Probability distribution
 Indexes
 OFDM
 Optimization
 binary tree
 achievable rate
 mutual information
 index modulation
ASJC Scopus subject areas
 Signal Processing
 Electrical and Electronic Engineering
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Profiles

Ye Liu
 Faculty Research Centre for Data Science  Associate
 School of Computing, Electronics and Maths  Lecturer in Electronic Engeineering
Person: Teaching and Research