Thummaluri, Uday Reddy and Natarajan, Lakshmi Prasad
(2018)
Codes for DC Balance and Dimming Control in
Visible Light Communications.
Masters thesis, Indian Institute of Technology Hyderabad.
Abstract
In visible light communications (VLC), direct current (DC) level balancing is important to maintain
constant illumination while the light emitting diodes are being used for communication. In this
thesis, perfectly DC balanced codes which have equal number of zeros and ones in all their codewords
are proposed. Given codeword length of n bits, we provide a relationship between maximum possible
input bits, k, and n for a perfectly DC balanced kb=nb code. We propose an algorithm to generate
the codebook of these perfectly DC balanced codes that avoid
ickering and maintain consistency
in the brightness. The performance of the proposed codes is compared with several existing codes
in terms of code rate, Hamming distance, frame error rate (FER), and bit error rate (BER). The
numerical results show that the proposed codes provide perfect DC balance and perform better
than existing codes in terms of minimum Hamming distance, FER, and BER without signi�cant
loss in code rate. We also derive a lower bound on average Hamming distance for the proposed
perfectly DC balanced codes for VLC. In VLC, dimming control is required to maintain desired
ambiance. For dimming control, addition of compensation symbols (CS) at the end of the runlength
limited (RLL) codes has been proposed in the literature. In this thesis, we propose novel RLL codes
for VLC that utilize these CS to improve the BER performance in addition to providing dimming
control. For various dimming factors, we compare the BER performance and mutual information of
the proposed and existing codes to show that the proposed codes result in improved performance.
A brief discussion on high rate codes for VLC is also presented.
[error in script]
| IITH Creators: |
| IITH Creators | ORCiD |
|---|
| Natarajan, Lakshmi Prasad | http://orcid.org/0000-0003-1552-5240 |
|
| Item Type: |
Thesis
(Masters)
|
| Uncontrolled Keywords: |
Visible Light Communication, DC Balance, Diming Control, Hamming Distance, Mutual Information |
| Subjects: |
Electrical Engineering |
| Divisions: |
Department of Electrical Engineering |
| Depositing User: |
Team Library
|
| Date Deposited: |
03 Jul 2018 04:42 |
| Last Modified: |
22 May 2019 07:08 |
| URI: |
http://raiithold.iith.ac.in/id/eprint/4137 |
| Publisher URL: |
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| Related URLs: |
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