1. September 2009doc.: IEEE 802.15-09-0117-00-0007
1/3/2019<month year>
<month year>
doc.: IEEE
July 2012
Project: IEEE LED(Light Emitting Diode) Interest Group (IG-LED)
Submission Title: [Performance Enhancement for LED-ID Systems by User Cooperation and Beamforming]
Date Submitted: [9th July, 2012]
Source: [Jin Young Kim, Yoon Hyun Kim, In Hwan Park, Jaesang Cha, Kyesan Lee, and Yeong Min Jang]
[Kwangwoon University, Seoul National University of Technology, Kyunghee University, Kookmin University]
Address [Kwangwoon University, Seoul, Korea]
Voice:[ ], FAX: [ ],
Re: []
Abstract: [Performance Enhancement for LED-ID Systems by User Cooperation and Beamforming]
Purpose: [Contribution to IEEE a]
Notice: This document has been prepared to assist the IEEE P a. 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 a
Slide 1
Jin Young Kim, Kwangwoon University
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2. September 2009doc.: IEEE 802.15-09-0117-00-0007
1/3/2019<month year>
July 2012
Contents
Introduction
Concept of cooperative communication systems
Beamforming for LED-ID in cooperative network
Optical Beamforming
Some Simulation Results
Conclusions
Jin Young Kim, Kwangwoon University

3. What is the LED-ID System
July 2012
What is the LED-ID System
Definition of LED-ID
- Light Emitting Diode Identification (LED-ID) is a technology that uses communication via light waves (especially visible light) to contactless exchange voice/video/data among one Tag(or Reader) to one or more identified Readers(or Tags).
Components of LED-ID
LEDs(maybe likened transmitter)
Photo Detector(maybe likened
receiver)
Each Reader and Tag of LED-ID
must have at least one LED and PD
Jin Young Kim, Kwangwoon University

4. Characteristic of LED-ID
July 2012
Characteristic of LED-ID
Long Brightness, Low Power Consumption
Frequency Band
- Visible light band (384 THz ~ 790 THz)
- No interference with RF
High speed Read and write capability
Security
No harmful to human
Green technology
Jin Young Kim, Kwangwoon University

5. LED-ID in Cooperative Network
July 2012
Reader 2 receives not only tag’s signal but also relay’s signal
Reader 2 can achieve full diversity gain with two-path signals
“Better” reliability and “Higher” data rates
Jin Young Kim, Kwangwoon University

6. September 2009doc.: IEEE 802.15-09-0117-00-0007
1/3/2019<month year>
July 2012
Cooperative Transmission
Advantages
Higher spatial diversity
Higher throughput
Lower delay
Reduced interference
Lower transmitted power
Adaptability to network conditions
Jin Young Kim, Kwangwoon University
<author>, <company>

7. Tag to Tag Interference in Cooperative Network
July 2012
Tag to Tag Interference in Cooperative Network
Tag-to-Tag interference.
Tag to Tag interference in LED-ID system occurs, and seriously affect the performance.
Reader #2 receives Tag#1 and Tag#2 signal
Tag#2’ signal is interference
Worse reliability
Jin Young Kim, Kwangwoon University

8. Optical Beamforming Concept
July 2012
Concept & Motivation of Optical Beamforming
Interference mitigation
- Two tags and one reader
- Reader is in interference region between each tag
Optical beamforming mitigate the interference
Optical Beamforming Concept
Jin Young Kim, Kwangwoon University

9. Optical Beamforming for LED-ID systems
July 2012
Optical Beamforming for LED-ID systems
We propose an Tag-to-tag interference mitigation method with Optical Beamforming for LED-ID in cooperative network.
OBF can be used at both the transmit and receiver side to achieve spatial selectivity
“Better” reliability
“High” SNR
Jin Young Kim, Kwangwoon University

10. Beamforming technique
July 2012
Beamforming technique
Beamforming
-Signal processing technique used in sensor arrays for directional signal transmission or reception
Beamforming has basic two categories
Zero forcing (ZF)
Minimum mean square error (MMSE)
Jin Young Kim, Kwangwoon University

11. Beamforming technique
July 2012
Beamforming technique
ZF beamforming
- Good solution for low-noise or high-power situation
Transmitter knows the downlink channel state information (CSI)
perfectly, ZF-beamforming can achieve almost the system capacity
when the number of users is large.
Jin Young Kim, Kwangwoon University

12. Beamforming technique
July 2012
Beamforming technique
MMSE beamforming
- This type called “regularized” ZF beamforimg
- Loading factor maximizes the signal-to-interference-plus- noise
ratio (SINR) at the receiver
P : Power constraint
: Loading factor
K : Number of users
Jin Young Kim, Kwangwoon University

13. Optical Beamforming Advantages Tag to Tag Interference mitigation
July 2012
Optical Beamforming
Advantages
Tag to Tag Interference mitigation
High SNR gain
Lower transmitted power
Jin Young Kim, Kwangwoon University

14. Simulation Parameters
July 2012
Simulation Parameters
Parameters
Values
The receiver O/E
conversion efficiency
0.53[A/W]
Detector physical area of PD
1.0[cm2]
Transmitted optical power
200[mW]
FOV at the receiver
60[deg.]
Optical relay method AF
Interference mitigation
ZF, MMSE
Jin Young Kim, Kwangwoon University

15. BER Performance of Optical Cooperation for LED-ID systems
July 2012
BER Performance of Optical Cooperation for LED-ID systems
Jin Young Kim, Kwangwoon University

16. BER Performance of Optical Beamforming for LED-ID systems
July 2012
BER Performance of Optical Beamforming for LED-ID systems
Jin Young Kim, Kwangwoon University

17. Conclusion Tag to Tag interference in LED-ID system
July 2012
Conclusion
Tag to Tag interference in LED-ID system
Proposed optical-beamforming and cooperative network for LED-ID systems
- Interference mitigation
- High SNR
→ Coverage extension
Jin Young Kim, Kwangwoon University