Numerical Evaluation SINR of an IR system Jinhui Wang

Introduction  What is Infrared? Why?  nm  Abundance of unregulated bandwidth.  No multi-path fading  High security  Direct Sequence Code Division Multiple Access  Low power transmission and reception  Security

Asynchronous CDMA Channel Model

Interference and Noise 1. multi-user interference 2. Multipath dispersion 3. Noise (Background)

Channel Model – Exponentially and Linearly Decay

Evaluate SINR

Three main sources of ambient light 1. Sun light, produces the highest levels of background current, so it is the major source of shot noise. 2. Incandescent light 3. Fluorescent light Optical Power spectrum for Ambient light noise

Building Noise Model  Very shiny day  Well fluorescent room: 5x6m  Incandescent light: 60W, 1m away  Fluorescent light: 8x36W, 2.2m away  With and without filter

Background Current (IB) Type of light sourceWithout Filter( A) With filter ( A) Transmission coefficient Direct sun light % Indirect sun light % Incandescent light % Incandescent light % Fluorescent light4025.0% Fluorescent, conventional % Fluorescent, electronic % Fluorescent, electronic % Fluorescent, electronic %

Effect of Code Length (N) on SINR

Effect of optical filter on SINR

Important Conclusion  DS-CDMA is used in Infrared system.  SINR is calculated on three parts of noise components.  SINR for Exponentially Decay Channel is always better than Linearly Decay Channel.  Optical filter greatly reduces the background current. Higher SINR is achieved.  With larger Code length (N), higher SINR.  As the users increase, SINR decrease.

Reference  [1] Xavier N. Fernando, “Performance of an Infrared Wireless CDMA System” Proceedings of the Digital Wireless Communications Conference V at SPIE's 17th Annual AeroSense Symposium  [2] Adriano J.C. Noreira, Rui T. Valadas and A.M. de Oliveira Duarte, “ Optical interference produced by artificial light”, Wireless Networks 3 (1997)  [3] Moreia A.J.C., Valadas R.T, and de Oliveira Duarte A.M. Optical interference produced by artificial light, Wireless Networks, Vol.3, pp , 1997.