What is Wireless Communication

OVERVIEW OF WIRELESS COMMUNICATION TECHNOLOGIES

GROUP ONE

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MEMBERS

Transmitting/receiving voice and data using electromagnetic waves in open space, It is The transmission of user data without the use of wires.

Wireless communications is revolutionizing the way we live—just as personal computers in the 1980s forever altered how we work, and the Internet in the 1990s dramatically changed how we acquire information.

A wide array of devices ranging from computers to digital cameras, laser printers, and even refrigerators can already communicate without wires.

What is Wireless Communication?

The first wireless networks were developed in the Pre-industrial age.

These systems transmitted information over line-of-sight distances (later extended by telescopes) using smoke signals, torch signaling, flashing mirrors, signal flares, or semaphore flags.

An elaborate set of signal combinations was developed to convey complex messages with these rudimentary signals.

Observation stations were built on hilltops and along roads to relay these messages over large distances.

History of wireless communications

These early communication networks were replaced first by the telegraph network (invented by Samuel Morse in 1838) and later by the telephone. In 1895, a few decades after the telephone was invented, Marconi demonstrated the first radio transmission from the Isle of Wight to a tug boat 18 miles away, and radio communications was born.


The U.S. military was extremely interested in the combination of packet data and broadcast radio inherent to ALOHANET.

Throughout the 1970’s and early 1980’s the Defense Advanced Research Projects Agency (DARPA) invested significant resources to develop networks using packet radios for tactical communications in the battlefield.

Packet radio networks also found commercial application in supporting wide-area wireless data services.


The current generation of wireless LANs, is based on the family of IEEE 802.11 standards.

wireless LANs is becoming the preferred Internet access method in many homes, offices, and campus environments due to their convenience and freedom from wires. However, most wireless LANs support applications such as email and web browsing that are not bandwidth-intensive.


In 1946 public mobile telephone service was introduced in 25 cities across the United States: thirty years after the introduction of mobile telephone service the New York system could only support 543 users.A solution to this capacity problem emerged during the 50’s and 60’s when researchers at AT&T Bell Laboratories developed the cellular concept.


Mobility The freedom to move about without being tethered by wires is certainly the primary advantage of a wireless network

Mobility enables users to stay connected to the network no matter where they go within the network’s range

Many occupations that require workers to be mobile instead of tied to a desk, such as police officers and inventory clerks, are finding that wireless communications to be vital.

Advantages of Wireless Networking

Easier and Less Expensive Installation Installing network cabling in older buildings can be a difficult, slow, and costly task.


Increased Reliability Network cable failures may be the most common source of network problems.

Moisture from a leak during a thunderstorm or a coffee spill can erode metallic conductors.

A user who shifts the computer on her desk may break the network connection. A cable splice that is done incorrectly can cause problems that result in unexplainable errors and are very difficult to identify.

Using wireless technology eliminates these types of cable failures and increases the overall reliability of the network.


Disaster Recovery Many businesses are turning to WLANs as a major piece of their disaster recovery plans. Savvy planners keep laptop computers with wireless NICs and access points in reserve along with backup network servers.

Then, in the event of a disaster, managers can quickly relocate the office, without needing to find a new facility with network wiring. Instead, the network servers are installed in the building along with the access points, and the laptop computers are distributed to the resettled employees.


Radio Signal Interference Because wireless devices operate using radio signals, the potential for two types of signal interference exists. Signals from other devices can disrupt what a wireless device is trying to transmit, or a wireless device may itself be a source of interference for other devices.

Several common office devices transmit radio signals that may interfere with a WLAN.

These devices include microwave ovens, elevator motors, and other heavy electrical equipment, such as manufacturing machines, photocopiers, certain types of outdoor lighting systems, theft protection systems, and cordless telephones.

Disadvantages of Wireless networking

Radio Signal Interference These may cause errors to occur in the transmission between a wireless device and an access point. In addition, Bluetooth and

WLAN 802.11b/g devices both operate in the same radio frequency, potentially resulting in

interference between such devices.


Security Because a wireless device transmits radio signals over a broad area, security becomes a major concern.

It is possible for an intruder to be lurking outdoors with a notebook computer and wireless NIC with the intent of intercepting the signals from a nearby wireless network.

Because much of a business’ network traffic may contain sensitive information, this is a realb concern for many users.


Health Risks Wireless devices contain radio transmitters and receivers that emit radio frequency (RF) energy.

Typically, these wireless devices emit low levels of RF while being used. High levels of RF can produce biological damage through heating effects (this is how a microwave oven is able to cook food).

However, it is not known if lower levels of RF can cause adverse health effects.

Although some research has been done to address these questions, no clear picture of the biological effects of this type of radiation has emerged to date.


RADIO Definition: It is the radiation of electro-magnetic signals through the atmosphere or free space. – Wikipedia.org

It is the most popular mode of wireless communication technology. It used to carry information such as sound, pictures, and videos by changing (modulation) properties of radio waves. This properties include amplitude, frequency, phase angles e.t.c.

Modes & mechanisms of wireless communication technologies

RADIOKey Features Transmission is normally via a transmitter & an antenna.

A transmitter consists of a source of electrical energy which produces an alternating current of a given frequency or oscillation. The transmitter sends the oscillated signal to a resonant antenna, which converts the AC current into an electromagnetic wave. An antenna converts electric current into electromagnetic waves and vice versa. It is used with a radio transmitter or a radio receiver.


RADIOKey Features Radio communication can be in two operation modes, either simplex or duplex.

Simplex – Two stations make take turns in communicating i.e., they cannot communicate at the same time.

Duplex – Both stations can communicate simultaneously.

Radio signals can be transmitted over long ranges

Radio transmission is regulated by licenses


RADIOKey FeaturesAdvantages No cables needed. Multiple channels for communication available.

Wide bandwidth. Disadvantages Line of sight can be disrupted by any obstacle.

Signal loss due to absorption by the atmosphere (attenuation).

Radio communication equipment are expensive to build and buy e.g. Towers


FREE SPACE OPTICSAs the name states, it is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking.


FREE SPACE OPTICSKey Features There must be a clear line of sight between two communicating stations.

Optical links use infra-red laser light.

If no clear line of sight, mirrors can be used to reflect signals.

Maximum data speeds is 10 Gbit/s Maximum range is 7km.


FREE SPACE OPTICSApplications of FSO LAN to LAN connection on campuses at fast Ethernet or Gigabit Ethernet speeds.

LAN to LAN connections in a city or metropolitan area network.

Used for communication between space craft.

To cross a public road or other barriers which sender and receiver do not own.

Converged Voice data connection.


FREE SPACE OPTICSAdvantages Ease of deployment – Easy to deploy and configure FSO.

Can be used to power devices – Laser beams have energy which can be transmitted to power devices.

License free long range operation as compared to radio communication.

Immune to electromagnetic interference.

Full duplex operation. No Fresnel zone necessary.


FREE SPACE OPTICSDisadvantages Atmospheric absorption. Interference with background lighting sources e.g. the sun.

Beam dispersion.


WI-FI Low-power wireless communication used by computers and hand-held electronic devices

Key Features Communication is via a wireless router which serves as a communication hub.

Limited in range due to low power, devices must be close to the wireless router.

May be free to use. Can be secured using passwords.

TYPES & APPLICATIONS OF WIRELESS TECHNOLOGIES

WI-FIAPPLICATIONS Home networking allowing users to link devices without using lengths of cable.

Commercial applications where businesses provide internet to their customers.


SATELLITE A communications satellite or Comsat is an artificial satellite sent to space for the purpose of telecommunications – Wikipedia.org

Key Features Powered by engines to keep it in orbit. Engines derive power from solar cells.

Consists communication payload composed of transponders.

Expensive to build and deploy. Offers superior speeds compared to other types of wireless technologies


SATELLITEAPPLICATIONS Telephone – Satellite phones are used in areas where landline or other types of telecommunication cannot be achieved. Especially in submarines, airplanes and remote places like isolated islands.

Television – Satellite TV mainly Pay TV is common in urban areas or areas without reliable UHF or VHF signals.


SATELLITEAPPLICATIONSInternet Access - Satellites have been used to connect internet via broadband data connections especially in remote areas.

GPS - A series of global positioning satellites that offer accurate directions and coordinates of devices. Used for navigation purposes

Satellite Radio –Allows Radio stations to offer same audio programming anywhere anytime.

Weather Forecasting – Meteorologists use data gathered from satellites to accurately forecast weather patterns.


Mobile Telephones Mobile telephones make use of cellular networks. A cellular network uses connected transmitters that enable users to move around while still remaining in contact with the network.


WiMAXWorldwide Interoperability for Microwave Access is a wireless communications standard designed to provide 30 to 40 megabit-per-second data rates, with the 2011 update providing up to 1 Gbit/s for fixed stations. –Wikipedia.org


BLUETOOTH Bluetooth is a standard for the short-range wireless interconnection of cellular phones, computers, and other electronic devices. It allows exchange of data over short distances.


BLUETOOTHApplications Wireless control of and communication of mobile phones and heads free kits.

Used in car stereo systems. Transfer of files, contacts between 2 devices over OBEX.

Bluetooth modems allow dialup connections to the internet.

Can be used as remote controls for controlling PCs.


K. Pahlavan and P. Krishnamurthy, Principles of Wireless Networks A Unified Approach, New Jersey:Prentice.7.

V.H. McDonald, ―The Cellular Concept,‖ Bell System Tech. J. 8.

S. Schiesel. Paging allies focus strategy on the Internet.9.

F. Abrishamkar and Z. Siveski, ―PCS global mobile satellites,‖ IEEE Commun. Mag.

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What is Wireless Communication

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