Wireless Infrared LANintroduction

INTRODUCTION

Now a days the telecommunication principles takes a wide ways and types can be classified according to the medium and frequencies used ; IR LANS or routers is a part that uses the IR frequencies to transport such a data and build networks.

INTRODUCTION

INTRODUCTION

The network shown can use IR LANS to connect the PCs but with limitations (Line of sight required to transport with IR frequency.

INTRODUCTION

UNLIKE radio LANS (routers) it can be transmitted even if LOS is not avaliable (i.e through walls)

INTRODUCTION

UNLIKE radio LANS (routers) it can be transmitted even if LOS is not avaliable (i.e through walls)

BUT data ranges and BW is better in IR and channels can be separated because of wide frequency range (carrier frequency will be > 200 THZ and BW easily becomes wider)

INTRODUCTION

UNLIKE radio LANS (routers) it can be transmitted even if LOS is not available (i.e through walls)

BUT data ranges and BW is better in IR and channels can be separated because of wide frequency range (carrier frequency will be > 200 THZ and BW easily becomes wider)

IR is more SECURED than radio networks

INTRODUCTION

INTRODUCTION

This table shows a differences between IR and radio LANs

INTRODUCTION

This figure shows a typical topology for IR Network (for example)

THE WIRELESS IR Channel

THE WIRELESS IR Channel

Non-directed infrared links, which do not require alignment between transmitter and receiver, can be categorized as either line-of-sight (LOS) or diffuse ; LOS links means communication with a line without any object but diffuse can depends on reflections

THE WIRELESS IR Channel

The optical signal in a diffuse link can undergo many reflections and still have appreciable energy.

THE WIRELESS IR Channel

The optical signal in a diffuse link can undergo many reflections and still have appreciable energy.

Practical wireless infrared link will use intensity modulation and direct detection (IM/DD).

Achieving a High Signal-to-Noise Ratio:

Achieving a High Signal-to-Noise Ratio:

The electrical signal-to-noise ratio (SNR) of IM/DD links is limited by noise from ambient light sources.

Achieving a High Signal-to-Noise Ratio:

The electrical signal-to-noise ratio (SNR) of IM/DD links is limited by noise from ambient light sources.

Since a photodetector produces a current proportional to the received optical power, the SNR of IM/DD links is proportional to the square of the received optical power.

Bandwidth Reuse in Multi-User Systems

Evaluations of the performance of time-, subcarrier frequency- and code-division multiple-access (TDMA, FDMA, and CDMA) schemes for bandwidth reuse, demonstrating this advantage of infrared over radio.It appears also possible to employ space-division multiple-access (SDMA) with infrared, leading to an even greater increase in network capacity.

Future Developments

Optical technology and communication techniques could enable the realization of a LAN that employs very high-bit-rate (up to 100 Mb/s) diffuse infrared links to access a wired backbone.

Such a LAN would enable users to run communication-intensive applications, including real-time video, on portable computers.