1. Submission Title: CSK related Comment Resolution Input Summary
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: CSK related Comment Resolution Input Summary
Date Submitted: 17. May 2010
Source: [Jaeseung Son, Taehan Bae,Sridhar Rajagopal, Atsuya Yokoi, E.T. Won]
Contact:
Voice:
Re:
Abstract:
Purpose: addresses comments pending on input from Samsung for comment resolution
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
Slide 1
Euntae Won 1

2. Samsung response about CSK comment
17. May 2010

3. CID 399 Figure 40 – CSK system x y D/A Optical source xy to Pi,Pj,Pk
Color
Coding x y Pi Pj Pk
Data
Channel
Estimation
Sequence
Encoder
Scrambler
Band i
Band j
Band k
In actual, VLC system could have some degradation, for example, RGB imbalance, RGB interference or other error on xy color coordinate caused by ambient light or own light device characteristics.
Therefore, we have to prepare RGB compensation method.
This shows RGB calibration for solving the problem.
By preamble symbols on the header of the frame.
The system estimates the channel propagation matrix.
And data symbols are compensated by using the estimated channel matrix.
It is similar as MIMO algorithm on radio systems.
Signal detection / Timing synchronization
Using random sequence that has good auto-correlation like M sequence
Same code is used with RGB
RGB Calibration
Using orthogonal sequence like Hadamard code
Channel estimation is done by the different orthogonal code with RGB
RGB compensation is done according to the channel estimation result by MIMO algorithm
Figure 40 – CSK system

4. CID 404, 405 Figure 44 – Color Calibration x x y y Optical sources
Photo Detectors Pi
Pi’ Pi x
D/A
Band i
Band i’
A/D
Data x xy to
Pi,Pj,Pk
RGB to xy
Color
Coding Pj
RGB
Compensation Pj
Pj’
Color
Decoding
Data y
D/A
Band j
Band j’
A/D y Pk
Pk’ Pk
D/A
Band k
Band k’
A/D
Channel
Estimation
Sequence
Channel
Estimation
In actual, VLC system could have some degradation, for example, RGB imbalance, RGB interference or other error on xy color coordinate caused by ambient light or own light device characteristics.
Therefore, we have to prepare RGB compensation method.
This shows RGB calibration for solving the problem.
By preamble symbols on the header of the frame.
The system estimates the channel propagation matrix.
And data symbols are compensated by using the estimated channel matrix.
It is similar as MIMO algorithm on radio systems.
Signal detection / Timing synchronization
Using random sequence that has good auto-correlation like M sequence
Same code is used with RGB
RGB Calibration
Using orthogonal sequence like Hadamard code
Channel estimation is done by the different orthogonal code with RGB
RGB compensation is done according to the channel estimation result by MIMO algorithm
Figure 44 – Color Calibration

5. Figure 39 – Color constellations for CSK
CID 873 G G G R R R B B B
4 CSK
(2bits/Symbol)
8 CSK
(3bits/Symbol)
16 CSK
(4bits/Symbol)
Figure 39 – Color constellations for CSK
Next, I’d like to show some results of evaluating CMC performance.
These three pictures show the symbol position in xy color coordinate for the CMC evaluation.
We call 4CMC which has 4 symbol positions. In this case, system can send 2bits per every symbol.
And also, we prepared 16CMC with 4bits/symbol and 64CMC with 6bits/symbol.
Those symbol positions were decided for having same distance from adjacent symbols.
＊上記の信号点配置は、隣接する信号点との距離が一定であり、且つ
RGBで囲まれる面内で出来るだけ間隔が大きくなることを考慮して決定した

6. CID 879 Figure 41 – CIE 1931 xy color coordinates (xj,yj) (xp,yp)01 10 00 11 R B G
(xj,yj)
(xi,yi)
(xk,yk)
(xp,yp)
This slides shows ‘What is CMC?’.
This block diagram is the CMC system configuration.
First, transmit data is coded by the color coding block into xy values according to the xy color coordinate.
This picture shows the CIE1931 xy color coordinate with the example for CMC symbol positions.
All visible colors in the color palette defined by xy values.
And the numbers around the color palette show the wave lengths at each single tone colors.
And R,G,B figures shows the center wave length of the actual RGB LED devices.
In this case, 4 Symbol points are placed in the RGB tri angle.
That means this system can send 2 bits data information per symbol.
Next, these xy values are transformed into RGB values.
The relation between xy and RGB is showed by thses equations (according to “CIE1931 RGB color space”).
Those coefficients are defined by the RGB wave length. In this case RGB wave length are these (R:700nm, G:546.1nm, B:435.8nm).
In the receiver side, xy values are calculated from received RGB values.
And xy values are decoded into the received data.
In this system,
CMC symbols are provided as the visible colors which are made by RGB light sources.
And, the information is transmitted as the intensity ratio among RGB. Not as the each RGB absolute values like WDM.
CIE (Commission internationale de l'éclairage)
In 1931, CIE defined color standard as ‘CIE1931 RGB color space’.
3 primary colors in CIE1931 are R:700nm, G:546.1nm, B:435.8nm.
Figure 41 – CIE 1931 xy color coordinates