September 2009doc.: IEEE 802.15-09-0117-00-0007 1/3/2019<month year> <month year> doc.: IEEE 802.15-09-0117-00-0007 July 2012 Project: IEEE 802.15 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:[82-10-5355-4825], FAX: [82-2-913-5006], E-Mail:[jinyoung@kw.ac.kr] Re: [] Abstract: [Performance Enhancement for LED-ID Systems by User Cooperation and Beamforming] Purpose: [Contribution to IEEE 802.15.4a] Notice: This document has been prepared to assist the IEEE P802.15.4a. 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 P802.15.4a Slide 1 Jin Young Kim, Kwangwoon University <author>, <company>

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

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

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

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

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>

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

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

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

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

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

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

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

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

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

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

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