In Computer networking, the wireless network makes use of the wireless media or the unbounded media to transfer signals (data) from one computer to another, or from one network to another. The wireless network is often an appropriate, and sometimes necessary, networking option because it eliminates the need for too much cabling.
Sometimes the wireless network will incorporate the use actual cables thus forming a kind of mixed component network called Hybrid Network.
Sometimes the wireless network will incorporate the use actual cables thus forming a kind of mixed component network called Hybrid Network.
Types of Wireless Networks
- Wireless PAN (Wireless Personal Area Networks)
- Wireless LAN (Wireless Local Area Network)
- Wireless WAN (Wireless Wide Area Network)
- Mobile devices networks
Capabilities of Wireless Networks.
Whenever you implement a wireless network, you can be able to achieve the following;- Provide temporary connections to an existing, cabled network.
- Help provide backup to an existing network.
- Provide some degree of portability.
- Extend networks beyond the limits of physical connectivity.
Uses of Wireless Network
These are some of the areas where the wireless network can be used:-- Busy areas, such as lobbies and reception areas.
- People who are constantly moving, such as doctors and nurses in hospitals.
- Isolated areas and buildings.
- Departments where physical settings changes frequently and unpredictably.
- Structures, such as historic buildings, for which cabling present challenges.
Wireless Communications with LANs
The use of an access point transceiver is one of several ways to achieve wireless networking. An access point is a stationary transceiver connected to the cable based LAN that enables the cordless PC to communicate with the network. The access point acts as a conduit for the wireless PC. The process is initiated when the wireless PC sends a signal to the access point; from there, the signal reaches the network. The truly wireless communication, therefore, is the communication from the wireless PC to the access point.Wireless LANs use five techniques for transmitting data:
- Infrared transmission.
- Laser transmission.
- Narrowband (single-frequency) radio transmission.
- Spread-spectrum radio transmission.
- Microwaves.
1. INFRARED: All infrared wireless networks operate by using an infrared light beam to carry the data between devices. These systems need to generate very strong signals because weak transmission signals are susceptible to interference from light sourcessuch as windows and the signal cannot travel through objects.
LEDs are used to transmit signals or data between devices and photoreceptor diodes are used to receive data on the other side. Infrared signals are in a very high frequency range hence they have a good thro’ put. Infrared is just below the visible range of light between 100 GHz and 1000 THz.
There are four types of infrared networks:
1. Line-of-sight networks: - Data is transmitted only if the transmitter and the receiver have a clear line of sight between them.
2. Scatter infrared networks: - As the name suggests, signals are scattered in all directions, the broadcasted signals bounce of walls and ceilings and eventually hit the receiver.
3. Reflective networks: - Optical receiver situated near the computer transmits towards a common location which then direct transmission to the appropriate computer.
4. Broadband optical telepoint: - This infrared wireless LAN provides broadband services and is capable of handling high-quality multimedia requirements that can match those provided by a cabled network.
LEDs are used to transmit signals or data between devices and photoreceptor diodes are used to receive data on the other side. Infrared signals are in a very high frequency range hence they have a good thro’ put. Infrared is just below the visible range of light between 100 GHz and 1000 THz.
There are four types of infrared networks:
1. Line-of-sight networks: - Data is transmitted only if the transmitter and the receiver have a clear line of sight between them.
2. Scatter infrared networks: - As the name suggests, signals are scattered in all directions, the broadcasted signals bounce of walls and ceilings and eventually hit the receiver.
3. Reflective networks: - Optical receiver situated near the computer transmits towards a common location which then direct transmission to the appropriate computer.
4. Broadband optical telepoint: - This infrared wireless LAN provides broadband services and is capable of handling high-quality multimedia requirements that can match those provided by a cabled network.
3. NARROWBAND (SINGLE-FREQUENCY) RADIO TRANSMISSION: This approach is similar to broadcasting from a radio station. The user tunes both the transmitter and the receiver to a certain frequency. This does not require line-of-sight focusing because the broadcast range is 3000 meters (9842 feet).
4. SPREAD-SPECTRUM RADIO TRANSMISSION: - Spread-spectrum radio broadcasts signals over a range of frequencies.The available frequencies are divided into channels, known as hops, which are comparable to one leg of a journey that includes intervening stops between the starting point and the destination.
The spread-spectrum adapters tune in to a specific hop for a predetermined length of time, after which they switch to a different hop. A hopping sequence determines the timing. The computers in the network are all synchronized to the hop timing. This type of signaling provides some built-in security in that the frequency-hopping algorithm of the network would have to be known in order to tap into the data stream.
The spread-spectrum adapters tune in to a specific hop for a predetermined length of time, after which they switch to a different hop. A hopping sequence determines the timing. The computers in the network are all synchronized to the hop timing. This type of signaling provides some built-in security in that the frequency-hopping algorithm of the network would have to be known in order to tap into the data stream.
5. MICROWAVES: - Microwave systems are a good choice for a wireless network and can interconnect buildings in small, short-distance systems such as those on a campus or in an industrial park.
Microwave transmission is currently the most widely used long-distance transmission method. It is excellent for communicating between two line-of-sight points such as:
Microwave transmission is currently the most widely used long-distance transmission method. It is excellent for communicating between two line-of-sight points such as:
- Satellite-to-ground links.
- Between two buildings.
- Across large, flat, open areas, such as bodies of water or deserts.
- Two radio transceivers: one to generate (transmitting station) and one to receive (receiving station) the broadcast.
- Two directional antennas pointed at each other to implement communication of the signals broadcast by the transceivers. These antennas are often installed on towers to give them more range and to raise them above anything that might block their signals. (Move out or peer through the window and you will be able to see some).
satellite communication dish
Satellite
Microwave communication falls into two categories:-
i.Terrestrial Microwave
ii.Satellite microwave.
i) TERRESTRIAL MICROWAVE: - It uses earth based transmitters and receivers in the low GHz range of frequency (4-6GHz or 21-23GHz). Speed is often 1-10Mbps. The signal is normally encrypted for privacy. Communication is through line of sight and cannot go round corners or through buildings. Line-of-sight means that the transmitter’s beam is focused directly on the receiver. Microwave dishes (parabolic antennas) are seen on top of tall buildings.
ii) SATELLITE MICROWAVE: - It uses communication satellite that operates in geosynchronous orbit (rotate round the earth) at 22300 miles 36000km above the earth’s surface which is an altitude that will cause it to stay in a fixed position relative to the rotation of the earth. A geosynchronous satellite must orbit at 22,300 miles altitude and it must be over the earth’s equator.
i.Terrestrial Microwave
ii.Satellite microwave.
i) TERRESTRIAL MICROWAVE: - It uses earth based transmitters and receivers in the low GHz range of frequency (4-6GHz or 21-23GHz). Speed is often 1-10Mbps. The signal is normally encrypted for privacy. Communication is through line of sight and cannot go round corners or through buildings. Line-of-sight means that the transmitter’s beam is focused directly on the receiver. Microwave dishes (parabolic antennas) are seen on top of tall buildings.
ii) SATELLITE MICROWAVE: - It uses communication satellite that operates in geosynchronous orbit (rotate round the earth) at 22300 miles 36000km above the earth’s surface which is an altitude that will cause it to stay in a fixed position relative to the rotation of the earth. A geosynchronous satellite must orbit at 22,300 miles altitude and it must be over the earth’s equator.
Parabolic antennas are used to communicate with the satellite, and a transmission from earth’s station to the satellite is called an uplink while the transmission from the satellite to the earth station is called a downlink.
