Infrared wireless tecnology is the use of wireless technology in devices or systems that allow data transfer through infrared (IR) radiation.In infrared communication , an LED transmits the infrared signal as bursts of non-visible light. At the receiving end a photodiode or photoreceptor detects and captures the light pulses,and retrieve the information they contain.
IR wireless is used for short- and medium-range communications and control.It is used in computer hardware such as in wireless mouse, keyboard,Floppy disk drives,Printers.It is also used in Car locking systems,Emergency response systems, Headphones,Home security systems ,Robot control systems and more.
Infrared technology offers several important advantages as well as disadvantages as a form of wireless communication.
1. Low power requirements: ideal for laptops, telephones
2. Low circuitry costs: $2-$5 for the entire coding/decoding circuitry
3. Simple circuitry: no special hardware is required.
4. Higher security: directionality of the beam helps ensure that data isn’t leaked or spilled to nearby devices as it’s transmitted
1. Line of sight: transmitters and receivers must be almost directly aligned to
2. Blocked by common materials: people, walls, plants, etc. can block transmission
3. Short range: transmission become slow on longer distances
4. Light, weather sensitive: direct sunlight, rain, fog, dust, pollution can affect
5. Speed: transmission rate is lower than typical wired transmission.
There are no confirmed health risks or scientific dangers from infrared or radio frequency but in case of point-to-point lasers which can cause burns or blindness and also continuous microwave exposure which has been linked to cancer and leukemia.
Electromagnetic frequencies currently have less protection and can be freely intercepted by motivated individuals. But,security issue varies by the type of wireless transmission method .Infrared data transmission is more difficult to intercept when compared to radio frequency. Radio frequency can penetrate walls, making it much easier to transmit a message, but also more susceptible to tapping.
Wireless technologies is emerging as a one of the rapidly growthing technology.It provides unintrupted access to the network for all of the campus community. Every one increasingly want un-tethered network access for general-purpose,for example,people wants laptop computers equipped with wireless Ethernet cards.Wireless is being adopted for many new applications: to connect computers, to allow remote monitoring and data acquisition, to provide access control and security etc.
There are various applications for all the different wireless technologies,but we can divided into the following:
* Voice and messaging,
* Hand-held and other Internet-enabled devices, and
* Data Networking.
Voice and Messaging
Cell phones, pagers, and commercial two-way business radios can access voice and messaging services. These devices may be based on analog or digital standards.The analog standard is AMPS. Digital standards are GSM,TDMA, or CDMA.
Generaly, devices operate within networks that provide metropolitan, statewide, or nationwide coverage and operate in different frequency bands which are allocated by the FCC. Presently in the U.S., these networks operate throughput rates up to 16 kilobits per second (Kbps).
Hand-held and Internet-enabled devices
Cell phones and Personal Digital Assistants (PDAs) enabled with Internet,have emerged as the latest products that can connect to the Internet across a digital wireless network. Protocols, such as Wireless Application Protocol (WAP), and WML (Wireless Markup Language) have been developed for these devices to connect to the Internet.
Data is transfered in various way such as,through wireless local area networks (WLANs),Bluetooth.
Wireless Local Area Networks
WLANs are implemented within a building and can provide the final few meters of connectivity between a wired network and the mobile user.It is based on the IEEE 802.11 standard.It has three physical layer,two radio frequency specification and one infrared.Most WLANs operate in the 2.4 GHz license-free frequency band and have throughput rates up to 2 Mbps.The new 802.11astandardprovides throughput rates up to 54 Mbps.
WLAN configurations provides peer-to-peer connections between a set of PCs . It also provides point-to-point and point-to-multipoint wireless solutions. A point-to-point solution is used to bridge between two local area networks, and it is an alternative to cable between two geographically distant locations (up to 30 miles). Point-to-multi-point solutions connect several, separate locations to one single location or building.
Broadband wireless (BW) is an emerging wireless technology that allows simultaneous wireless delivery of voice, data, and video. BW is considered a competing technology with Digital Subscriber Line (DSL). BW comes in two ways: Local multi-point distribution service (LMDS) and Multi-channel multi-point distribution service (MMDS).
LMDS operates at high bandwidth of 28-31 GHz range of the frequency spectrum and has sufficient bandwidth to broadcast all the channels.
MMDS operates at lower frequencies, in the 2 GHz licensed frequency bands. MMDS has wider coverage than LMDS , but has lower throughput rates.
It is important to understand that in WLANs, data is encrypted only between the wireless adapter and the access point. Data travels through a wired LAN unencrypted. Therefore, data transmitted by wireless is not more secure than data transmitted through the wire, but probably not less secure.
The wireless communication system is one of the important communication system.Todays world allmost depand upon wireless communication system.Here I give you some brief history and types of
wireless communication system.
The concept of cellular radio was initiatly developed by AT&T at Bell loboratories.Initialy it is known as mobile phone ststem(MTSs).The cellular system are broken into matropolitan statistical area(MSA) and rural statical area(RSA).Each MSA and MSA has two different cellular operator that offer service.They are reffered as A-band and B-band system.A-band system is the non-wire system and B-band system is the wire system.
Personal communication service(PCS) is a next geeration of wireless commmunications.It is ageneral name given to the wireless system.This is devide into A,B,C,D,E and F blocks.A,B and C blocks involve a total of 30MHZ and D,E and F blocks are allocated 10 MHz.
There are different types of cellular system whose brief discusion of some cellulor system are given bellow:
1.The Advance Mobile Phone System(AMPS)-this standerd was developed for use in North America.
2.The code division Multiple acces(CDMA)-It is a IS-95 standerd developed in US.
3.The Digital Advanced Mobile Phone system(D-AMPS)-It is also called North Amarican disital Cellular (NADC) system.It is D-AMPS digital standerd.It is design to coexist with current cellular system and relies on both the IS-54 and IS-136.
4.The Global System for Mobile Communication(GSM)-It is a european standard for digital cellular system working on 900MHz band.This tecnology offer intrnational roaming,hight speed quality and high secuirity
6.The Total Access Commmunication System(TACS)-
This technology is drived from AMPS technology.It is operated in both 800- and 900-MHz bands.
7.The Integrated Dispatch Enhanced Network(iDEN)-It is known as alternative form of cellular communication that operate in the specialized mobile radio band.The iDEN utilized adigital radoi formate called QAM, and, with the exception of the radio link,it is aderivative of the GSM.