280 likes | 565 Views
Wireless Infrared LAN. introduction. 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.
E N D
Wireless Infrared LAN introduction
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 • 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.ethrough walls)
INTRODUCTION • UNLIKE radio LANS (routers) it can be transmitted even if LOS is not avaliable (i.ethrough 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.ethrough 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 • 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 • 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: • 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.