Page 149 - Proceedings of the 2017 ITU Kaleidoscope

MODELING AND ANALYSIS OF SPATIAL INTER-SYMBOL INTERFERENCE
FOR MIMO IMAGE SENSORS BASED VISIBLE LIGHT COMMUNICATION

1
1
2
Rongzhao Wu , Yarong Guo , Jiang Liu , Peng Liu 1
1
Yangzhong Intelligent Electrical Institute, North China Electric Power University
Yangzhong city, Jiangsu Province, China
2
Faculty of Science and Engineering, Waseda University
Shinjuku, Tokyo, Japan
Email:liupeng@ncepu.edu.cn

ABSTRACT

In this paper, a MIMO image sensors based visible light com-
munication system is designed and researched. In our study,
the spatial inter-symbol interference was considered and the
formation mechanism of the stray light and the influence of
the spatial inter-symbol interference is analyzed. The math-
ematics expression of the system SNR and BER is given. The
simulation result indicates that there is a critical communi- d
cation distance in the system. Once the communication dis-
tance exceeds the critical value, the system BER increases
sharply. In addition, an adaptive threshold detection method
(a) (b)
is introduced and the performance is simulated. By means of
estimating the spatial inter-symbol interference noise power, 500
the optimal detection threshold can be obtained and the sys-
tem BER performance enhances significantly. 450
Keywords— Optical wireless communication, Image sensor
400
communication, MIMO, spatial inter-symbol interference,
optimum detection threshold method 350

300
1. INTRODUCTION
250 A
With several advantages such as saving the radio frequency
resource and being harmless to human being, the visible light 200
communication (VLC) technology develops rapidly in the
last decade. Depended on the detection method, the VLC 150
system can be divided into photodiode (PD) based VLC sys-
B
tem and image sensors based VLC (IS-VLC) system [1]. Due 100
to the widespread use of image sensors, the IS-VLC tech-
nology has a promising future in low-speed optical wireless 50 C
communication, indoor positioning application and intelli-
0
gent transportation system [2, 3, 4]. 0 50 100 150 200 250 300 350 400 450 500
In order to improve the performance, multi-input multi-
output (MIMO) scheme is utilized in IS-VLC system. Com- (c)
pared with the single-input single-output scheme, MIMO-IS-
Fig. 1: Demonstration of the SISI. (a) The designed experi-
VLC system can not only achieve a higher symbol transmis-
ment board with 6 × 6 LED array and the LED spacing dis-
sion rate but also a lower bit error rate [5]. In a MIMO-IS-
tance d. (b) Imaging result of the LED array. (c) Light inten-
VLC system, a frame of digital data stream drivers the LED
sity contour plot of (b).
array where the on status of LEDs represents the data ’1’ and
off status corresponds to the data ’0’. An image sensor used
as receiver captures a picture and send it to be processed. By

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