Wireless Telecommunications

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WIRELESS TECHNOLOGY Presented by: A.Jeyakumar & Siva Chidambaram

Email id:[email protected] [email protected] Mobile No:9597976944

WIRELESS TECHNOLOGY Wireless telecommunications is the transfer of information between two or more points that are physically not connected. Distances can be short, as a few meters as in television remote control; or long ranging from thousands to millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of wireless technology include GPS units, Garage door openers or garage doors, wireless computer mice, keyboards and Headset (telephone/computer), headphones, radio receivers, satellite television, broadcast television and cordless telephones.
CONTENTS:
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Mobile telephones o Wireless data communications o Wireless energy transfer o Computer interface devices Categories of wireless implementations, devices and standards See also References
o

INTRODUCTION

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Introduction Wireless services Wireless networks Wired vs Wireless LAN Modes Cordless History o Photophone o Early wireless work o Radio Electromagnetic spectrum Applications of wireless technology o Security systems

Wireless operations permits services, such as long range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refertotelecommunications systems (e.g. radio transmitters and receivers, remote controls, computer networks, network terminals, etc.) which use some form of energy (e.g. radio frequency (RF),acoustic energy, etc.) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances.
WIRELESS SERVICES

This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2006)

Common examples equipment include:
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of

wireless







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Telemetry control and traffic control systems Infrared and ultrasonic remote control devices Modulated laser light systems for point to point communications Professional LMR (Land Mobile Radio) and SMR (Specialized Mobile Radio) typically used by business, industrial and Public Safety entities. Consumer Two way radio including FRS Family Radio Service, GMRS (General Mobile Radio Service) and Citizens band ("CB") radios. The Amateur Radio Service (Ham radio). Consumer and professional Marine VHF radios. Airband and radio navigation equipment used by aviators and air traffic control Cellular telephones and pagers: provide connectivity for portable and mobile applications, both personal and business. Global Positioning System (GPS): allows drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth.





Cordless computer peripherals: the cordless mouse is a common example; keyboards and printers can also be linked to a computer via wireless using technology such as Wireless USB or Bluetooth Cordless telephone sets: these are limited-range devices, not to be confused with cell phones. Satellite television: Is broadcast from satellites in geostationary orbit. Typical services use direct broadcast satellite to provide multiple television channels to viewers.

WIRELESS NETWORKS

Wireless networking (i.e. the various types of unlicensed 2.4 GHz WiFi devices) is used to meet many needs. Perhaps the most common use is to connect laptop users who travel

from location to location. Another common use is for mobile networks that connect via satellite. A wireless transmission method is a logical choice to network a LAN segment that must frequently change locations. The following situations justify the use of wireless technology:
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total cost reliability performance security

About Wired LANs
Wired LANs use Ethernet cables and network adapters. Although two computers can be directly wired to each other using an Ethernet crossover cable, wired LANs generally also require central devices like hubs, switches, or routers to accommodate more computers. For dial-up connections to the Internet, the computer hosting the modem must run Internet Connection Sharing or similar software to share the connection with all other computers on the LAN. Broadband routers allow easier sharing of cable modem or DSL Internet connections, plus they often include built-in firewall support.

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To span a distance beyond the capabilities of typical cabling, To provide a backup communications link in case of normal network failure, To link portable or temporary workstations, To overcome situations where normal cabling is difficult or financially impractical, or To remotely connect mobile users or networks.

WIRED VS WIRELESS TECHNOLOGY

Computer networks for the home and small business can be built using either wired or wireless technology. Wired Ethernet has been the traditional choice in homes, but Wi-Fi wireless technologies are gaining ground fast. Both wired and wireless can claim advantages over the other; both represent viable options for home and other local area networks (LANs). Below we compare wired and wireless networking in five key areas:


Installation
Ethernet cables must be run from each computer to another computer or to the central device. It can be timeconsuming and difficult to run cables under the floor or through walls, especially when computers sit in different rooms. Some newer homes are pre-wired with CAT5 cable, greatly simplifying the cabling process and minimizing unsightly cable runs.

ease of installation

The correct cabling configuration for a wired LAN varies depending on the mix of devices, the type of Internet connection, and whether internal or external modems are used. However, none of these options pose any more difficulty than, for example, wiring a home theater system. After hardware installation, the remaining steps in configuring either wired or wireless LANs do not differ much. Both rely on standard Internet Protocol and network operating system configuration options. Laptops and other portable devices often enjoy greater mobility in wireless home network installations (at least for as long as their batteries allow).

remain the single most common and annoying source of failure in a wired network. When installing a wired LAN or moving any of the components later, be sure to carefully check the cable connections. Broadband routers have also suffered from some reliability problems in the past. Unlike other Ethernet gear, these products are relatively new, multifunction devices. Broadband routers have matured over the past several years and their reliability has improved greatly.

Performance
Wired LANs offer superior performance. Traditional Ethernet connections offer only 10 Mbps bandwidth, but 100 Mbps Fast Ethernet technology costs little more and is readily available. Although 100 Mbps represents a theoretical maximum performance never really achieved in practice, Fast Ethernet should be sufficient for home file sharing, gaming, and high-speed Internet access for many years into the future. Wired LANs utilizing hubs can suffer performance slowdown if computers heavily utilize the network simultaneously. Use Ethernet switches instead of hubs to avoid this problem; a switch costs little more than a hub.

Cost
Ethernet cables, hubs and switches are very inexpensive. Some connection sharing software packages, like ICS, are free; some cost a nominal fee. Broadband routers cost more, but these are optional components of a wired LAN, and their higher cost is offset by the benefit of easier installation and built-in security features.

Reliability
Ethernet cables, hubs and switches are extremely reliable, mainly because manufacturers have been continually improving Ethernet technology over several decades. Loose cables likely

Security
For any wired LAN connected to the Internet, firewalls are the primary security consideration. Wired Ethernet hubs and switches do not support firewalls. However, firewall software products like ZoneAlarm can be installed on the computers themselves. Broadband routers offer equivalent firewall capability built into the device, configurable through its own software.





"Ad hoc" mode allows wireless devices to communicate in peer-to-peer mode with each other. "Infrastructure" mode allows wireless devices to communicate with a central node that in turn can communicate with wired nodes on that LAN.

About Wireless LANs
Popular WLAN technologies all follow one of the three main Wi-Fi communication standards. The benefits of wireless networking depend on the standard employed:
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Most LANs require infrastructure mode to access the Internet, a local printer, or other wired services, whereas ad hoc mode supports only basic file sharing between wireless devices. Both Wi-Fi modes require wireless network adapters, sometimes called WLAN cards. Infrastructure mode WLANs additionally require a central device called the access point. The access point must be installed in a central location where wireless radio signals can reach it with minimal interference. Although Wi-Fi signals typically reach 100 feet (30 m) or more, obstructions like walls can greatly reduce their range.



802.11b was the first standard to be widely used in WLANs. The 802.11a standard is faster but more expensive than 802.11b; 802.11a is more commonly found in business networks. The newest standard, 802.11g, attempts to combine the best of both 802.11a and 802.11b, though it too is more a more expensive home networking option.

Cost
Wireless gear costs somewhat more than the equivalent wired Ethernet products. At full retail prices, wireless adapters and access points may cost three or four times as much as Ethernet cable adapters and hubs/switches, respectively. 802.11b

Installation
Wi-Fi networks can be configured in two different ways:

products have dropped in price considerably with the release of 802.11g, and obviously, bargain sales can be found if shoppers are persistent.

away from the access point or other communication endpoint. As more wireless devices utilize the WLAN more heavily, performance degrades even further. Overall, the performance of 802.11a and 802.11g is sufficient for home Internet connection sharing and file sharing, but generally not sufficient for home LAN gaming. The greater mobility of wireless LANs helps offset the performance disadvantage. Mobile computers do not need to be tied to an Ethernet cable and can roam freely within the WLAN range. However, many home computers are larger desktop models, and even mobile computers must sometimes be tied to an electrical cord and outlet for power. This undermines the mobility advantage of WLANs in many homes.

Reliability
Wireless LANs suffer a few more reliability problems than wired LANs, though perhaps not enough to be a significant concern. 802.11b and 802.11g wireless signals are subject to interference from other home applicances including microwave ovens, cordless telephones, and garage door openers. With careful installation, the likelihood of interference can be minimized. Wireless networking products, particularly those that implement 802.11g, are comparatively new. As with any new technology, expect it will take time for these products to mature.

Security
In theory, wireless LANs are less secure than wired LANs, because wireless communication signals travel through the air and can easily be intercepted. To prove their point, some engineers have promoted the practice of wardriving, that involves traveling through a residential area with Wi-Fi equipment scanning the airwaves for unprotected WLANs. On balance, though, the weaknesses of wireless security are more theoretical than practical. WLANs protect their

Performance
Wireless LANs using 802.11b support a maximum theoretical bandwidth of 11 Mbps, roughly the same as that of old, traditional Ethernet. 802.11a and 802.11g WLANs support 54 Mbps, that is approximately one-half the bandwidth of Fast Ethernet. Furthermore, Wi-Fi performance is distance sensitive, meaning that maximum performance will degrade on computers farther

data through the Wired Equivalent Privacy (WEP) encryption standard, that makes wireless communications reasonably as safe as wired ones in homes. No computer network is completely secure and homeowners should research this topic to ensure they are aware of and comfortable with the risks. Important security considerations for homeowners tend to not be related to whether the network is wired or wireless but rather ensuring:
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Security Mobility
MODES

reasonably reasonably good good limited outstanding

Wireless communications can be via:
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the home's Internet firewall is properly configured the family is familiar with the danger of Internet "spoof emails" and how to recognize them the family is familiar with the concept of "spyware" and how to avoid it babysitters, housekeepers and other visitors do not have unwanted access to the network Wired vs Wireless

radiofrequency communication, microwave communication, for example long-range line-ofsight via highly directional antennas, or short-range communication, infrared(IR)shortrangecommunication,for example from consumer IR devices such as remote controls or via Infrared Data Association (IrDA).

Applications may involve point-topoint communication, point-tomultipointcommunication, broadcasting, cellular networks and other wireless networks.
CORDLESS

Wireless easier, but moderate beware Installation difficulty interference less more Cost reasonably Reliability high high Performance very good good

Wired

The term "wireless" should not be confused with the term "cordless", which is generally used to refer to powered electrical or electronidevices that are able to operate from a portable power source (e.g. a battery pack) without any cable or cord to limit the mobility of the cordless device through a connection to the mains power supply.

Some cordless devices, such as cordless telephones, are also wireless in the sense that information is transferred from the cordless telephone to the telephone's base unit via some type of wireless communications link. This has caused some disparity in the usage of the term "cordless", for example in Digital Enhanced Cordless Telecommunications.
HISTORY PHOTOPHONE

in military communications and later in fiber-optic communications.
EARLY WIRELESS WORK

The world's first wireless telephone conversation occurred in 1880, when Alexander Graham Bell and Charles Sumner Tainter invented and patented the photophone, a telephone that conducted audio conversations wirelessly over modulated light beams (which are narrow projections of electromagnetic waves). In that distant era when utilities did not yet exist to provide electricity, and lasers had not even been conceived of in science fiction, there were no practical applications for their invention, which was highly limited by the availability of both sunlight and good weather. Similar to free space optical communication, the photophone also required a clear line of sight between its transmitter and its receiver. It would be several decades before the photophone's principles found their first practical applications

David E. Hughes, eight years before Hertz's experiments, transmitted radio signals over a few hundred yards by means of a clockwork keyed transmitter. As this was before Maxwell's work was understood, Hughes' contemporaries dismissed his achievement as mere "Induction". In 1885, T. A. Edison used a vibrator magnet for induction transmission. In 1888, Edison deployed a system of signaling on the Lehigh Valley Railroad. In 1891, Edison obtained the wireless patent for this method using inductance (U.S. Patent 465,971). In the history of wireless technology, the demonstration of the theory of electromagnetic waves by Heinrich Hertz in 1888 was important. The theory of electromagnetic waves was predicted from the research of James Clerk Maxwell and Michael Faraday. Hertz demonstrated that electromagnetic waves could be transmitted and caused to travel through space at straight lines and that they were able to be received by an experimental apparatus. The experiments were not followed up by Hertz. Jagadish Chandra Bose around this time developed an early wireless detection device and helped increase the knowledge of millimeter length

electromagnetic waves. Practical applications of wireless radio communication and radio remote control technology were implemented by later inventors, such as Nikola Tesla.
RADIO

The term "wireless" came into public use to refer to a radio receiver or transceiver (a dual purpose receiver and transmitter device), establishing its usage in the field of wireless telegraphy early on; now the term is used to describe modern wireless connections such as in cellular networks and wireless broadband Internet. It is also used in a general sense to refer to any type of operation that is implemented without the use of wires, such as "wireless remote control" or "wireless energy transfer", regardless of the specific technology (e.g. radio, infrared, ultrasonic) used. Guglielmo Marconi and Karl Ferdinand Braun were awarded the 1909 Nobel Prize for Physics for their contribution to wireless telegraphy.
ELECTROMAGNETICSPECTRUM

Communications Commission in the USA, or Ofcom in the United Kingdom. This determines which frequency ranges can be used for what purpose and by whom. In the absence of such control or alternative arrangements such as a privatized electromagnetic spectrum, chaos might result if, for example, airlines didn't have specific frequencies to work under and an amateur radio operator were interfering with the pilot's ability to land an aircraft. Wireless communication spans the spectrum from 9 kHz to 300 GHz.
APPLICATIONS TECHNOLOGY OF WIRELESS

SECURITY SYSTEMS

Wireless technology may supplement or replace hard wired implementations in security systems for homes or office buildings. MOBILE TELEPHONES One of the best-known examples of wireless technology is the mobile phone, also known as a cellular phone, with more than 4.6 billion mobile cellular subscriptions worldwide as of the end of 2010. These wireless phones use radio waves to enable their users to make phone calls from many locations worldwide. They can be used within range of the mobile telephone site used to house the equipment required

Light, colors, AM and FM radio, and electronic devices make use of the electromagnetic spectrum. The frequencies of the radio spectrum that are available for use for communication are treated as a public resource and are regulated by national organizations such as the Federal

to transmit and receive the radio signals from these instruments.
WIRELES DATA COMMUNICATION

Wireless data communications are an essential component of mobile computing. The various available technologies differ in local availability, coverage range and performance, and in some circumstances, users must be able to employ multiple connection types and switch between them. To simplify the experience for the user, connection manager software can be used, or a mobile VPN deployed to handle the multiple connections as a secure, single virtual network. Supporting technologies include: Wi-Fi is a wireless local area network that enables portable computing devices to connect easily to the Internet. Standardized as IEEE 802.11 a,b,g,n, Wi-Fi approaches speeds of some types of wired Ethernet. Wi-Fi has become the de facto standard for access in private homes, within offices, and at public hotspots. Some businesses charge customers a monthly fee for service, while others have begun offering it for free in an effort to increase the sales of their goods. Cellular data service offers effective coverage within a range of 10-15 miles from the

nearest cell site. Speeds have increased as technologies have evolved, from earlier technologies such as GSM, CDMA and GPRS, to 3G networks such as W-CDMA, EDGE or CDMA2000. MobileSatelliteCommunicatio ns may be used where other wireless connections are unavailable, such as in largely rural areas or remote locations. Satellite communications are especially important for transportation, aviation, maritime and military use.
WIRELESS ENERGY TRANSFER

Wireless energy transfer is a process whereby electrical energy is transmitted from a power source to an electrical load that does not have a built-in power source, without the use of interconnecting wires.
COMPUTER INTERFACE DEVICES

Answering the call of customers frustrated with cord clutter, many manufactures of computer peripherals turned to wireless technology to satisfy their consumer base. Originally these units used bulky, highly limited transceivers to mediate between a computer and a keyboard and mouse, however more recent generations have used small, high quality devices, some even incorporating Bluetooth. These

systems have become so ubiquitous that some users have begun complaining about a lack of wired peripherals. Wireless devices tend to have a slightly slower response time than their wired counterparts, however the gap is decreasing. Initial concerns about the security of wireless keyboards have also been addressed with the maturation of the technology.
CONCLUSION


friends and family about their experiences with building LANs. And, spend just a few more minutes with our interactive Home Network Advisor tool. It should help you decide on the type of network as well as the gear you will want to have. Categories of wireless implementations, devices and standards
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You've studied the analysis and are ready to make your decision. Bottom line, then, which is better - wired or wireless? The table below summarizes the main criteria we've considered in this article. If you are very cost-conscious, need maximum performance of your home system, and don't care much about mobility, then a wired Ethernet LAN is probably right for you. If on the other hand, cost is less of an issue, you like being an early adopter of leading-edge technologies, and you are really concerned about the task of wiring your home or small business with Ethernet cable, then you should certainly consider a wireless LAN. Many of you will naturally fall somewhere in between these two extremes. If you're still undecided, consider asking







Radio communication system Broadcasting Amateur radio Land Mobile Radio Communication radio Cordless telephony:DECT (Digital Enhanced Cordless Telecommunications) Cellular networks: 0G, 1G, 2G, 3G, Beyond 3G (4G), Future wireless Short-range point-to-point communication : Wireless microphones, Remote controls, IrDA, RFID (Radio Frequency Identification), TransferJet, Wireless USB, DSRC (Dedicated Short Range Communications), EnOcean, Near Field Communication Wireless sensor networks: ZigBee, EnOcean; Personal area networks, Bluetooth, TransferJet, Ultra-wideband (UWB from WiMedia Alliance).



Wireless networks: Wireless LAN (WLAN), (IEEE 802.11 branded as Wi-Fi and HiperLAN), Wireless Metropolitan Area Networks (WMAN) and Broadband Fixed Access (BWA) (LMDS, WiMAX, AIDAAS and HiperMAN)

REFERENCES 1. "ATIS Telecom Glossary 2007".atis.org. http://www.atis.org/tg2k/. Retrieved 2008-03-16. 2. Alfred Thomas (1904). A story of wireless telegraphy. New York, D. Appleton and Co.. 3. "Heinrich Rudolf Hertz". chem.ch.huji.ac.il. http://chem.ch.huji.ac.il/~eugen iik/history/hertz.htm. Retrieved 2008-03-16. 4. J.C. Bose, Collected Physical Papers. New York, N.Y.: Longmans, Green and Co., 1927 5. Hard-wired VS Wireless Home Security Systems 6. Robust demand for mobile phone service will continue, UN agency predicts UN News Centre February 15, 2010 7. TCO Insights on Rugged Mobile Computers, VDC Research, 2007. 8. High Speed Internet on the Road,http://www.geeksontour.c om/showme/wifi/wifi00_3ways .cfm 9. Mitchell, Bradley. Wireless Internet Service: An Introduction 10.What is Connection Manager? Microsoft Technet, March 28, 2003

SEE ALSO
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Mobile (disambiguation) History of radio, Timeline of radio, Digital radio, Radio resource management (RRM) Ham radio Hotspot (Wi-Fi), Wireless energy transfer, True wireless, Wireless security, Wireless access point Personal area network, comparison of wireless data standards, List of emerging technologies Radio antenna Television antenna Terrestrial television Tuner (radio) Tuner (television)

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