Wireless Communication Methods

Wireless Communication Methods

1. Infrared Communication

   • Found in remote controls for televisions, dvd players and most other entertainment devices
     • Dimmer lights and other facilities can also be controlled by infrared
   • Infrared uses light that is invisible to us and is just above the red end of the colour spectrum
     • An infrared system uses an LED to emit the light and a photo-diode in the television to receive the light
     • Digital code within the controller switches the light on and off, this is then picked up as digital code at the other end.
       • The communication standard is called 'IrDA', short for Infrared Digital Association and it allows for wireless communication
   • Infrared Peripherals
     • Mouse
     • Keyboard
     • Joysticks
     • Gamepads
   • Infrared bandwidth is most around 115.2 kbps
     • IR works only up to about 10 metres but that is fine for the type of applications it is mainly used for
       • It will only work line-of-sight
   • Technologies such as Bluetooth has largely supplanted infrared as a communication method for mobiles and computers
   • Pros and Cons
     • Advantages
       • Inexpensive compared to other technologies
       • Works over a moderate bandwidth 115 Kbps
       • Works well over a short
     • Disadvantages
       • Only works line-of-sight
       • Short range - a few metres
       • Low bandwidth

2. Fibre Optic Communication

   • Offers the widest bandwidth of all optical tech
     • Based around highly transparent glass fibre
       • Light is launched at one end and a photo-diode translates the light back into digital data at the other end
   • Fibre optic cable is widely used for larger LAN installations where cable runs exceed 100 metres
     • It is also used where extreme bandwidth is required, for example cable television and high speed internet access
   • Pros and Cons
     • Advantages
       • Can carry signals over a much longer distance without a repeater compared to copper
       • Extremely large data capacity
       • Immune to electrical interference
       • Immune to corrosion
       • Can carry many different services over the same line
       • Can be used in hazardous environments such as petro-chemical refineries
       • Future proofs your network to cope with the growth in data traffic
         • Plenty of bandwidth
       • Excellent security as it is difficult to tap into a glass fibre without detection
       • One cable carries many fibres
         • Each fibre can carry 10 Gbps or more
       • Each fibre could be used for a different service
     • Disadvantages
       • Fibre is more expensive than copper cable
       • Connecting fibres together ("splicing") is more difficult
       • The complex electronics at both ends of the line tends to be more expensive
       • Needs specialist expertise to lay fibre and many installers are more familiar with copper cable
       • Fibre cannot carry power as it is made of glass
         • Copper cable can carry both signal and power at the same time
       • Failure can be more catastrophic than a copper
         • Many services may be sent through one cable
           • They can all fail because of a single cable failure

3. Laser Communication

   • Lasers can be used as a communication system
     • High power laser beams are used to transmit light signals
   • Sometimes called a 'free space' laser system because the beams travel directly through the air
     • For example, setting up a high bandwidth data link between two line-of-sight buildings
   • Commercial systems available that offer Gigabit speeds up to 3 kilometres
   • The system can be affected by weather
     • Fog or haze can block the beams
   • It can be set up very quickly and easily, making it ideal for setting up a video feed to cover outdoor events
   • Laser communication is also used to exchange data between satellites
     • In space the beams remain strong and tightly focused offering speeds of up to 10 Gbps
   • Uses
     • Campus wide communication
     • Emergency data links
     • Outdoor events requiring high speed data feeds
     • Building - to - building communication
     • Satellite to satellite communcation
     • Backup network in case main cabled network fails
   • Pros and Cons
     • Advantages
       • Wide bandwidth compared to infrared
       • Can be set up quickly (compared to laying cable)
     • Disadvantages
       • Affected by weather
       • Requires line of sight to work

4. Bluetooth

   • Bluetooth is a type of short range radio communication and networking protocol combined
   • It was designed to that close range devices could exchange data
     • 10 metres close, even if there is a wall in between
   • Detects phones nearby and provides a list of usernames
     • Files and messages can be sent with permission
   • Provides hands free use of a phone whilst driving, by connecting to a headset for example
   • Uses
     • Hands-free mobile telephone calls
     • Short range communication such as a PC and a pinter
     • Transferring files between devices
     • Connection to measurement devices, medical equipment, GPS receivers, bar code scanners
     • Connection to industrial and medical sensors
   • Pros and Cons
     • Advantages
       • Excellent for short range communication
       • World-wide standard so all bluetooth certified devices are compatible
       • Fully automatic - can auto-sense other bluetooth devices nearby
       • Low power, ideal for battery operation
       • Does not require line-of-sight, unlike infrared
       • Can use passwords to only allow authorised people to connect
     • Disadvantages
       • It is a short range technology
       • Low bandwidth

5. Wireless communication

   • This form of communication makes use of radio waves in order to transmit and receive information
   • Standards have been developed for wireless communication that specify the protocols to be used and the maximum bandwidth it can support
     • These are called the IEEE 802.11 standards
   • A WiFi alliance exists to ensure all equipment using the term are compatible with one another
   • WiFi is widely used for LANs and WANs as it does not need any cabling to be laid down
     • It needs a wireless access point to handle the radio traffic
   • Uses
     • Connecting to an organisations Local Area Network
     • Connecting to the Internet through a hotspot
     • Smartphones and PDA connecting to the internet
     • Wirelessly downloading electronic books into a reader
     • Wirelessly streaming music throughout a home
     • WiFi enabled printers
     • Games consoles to connect to the Internet
   • Pros and Cons
     • Advantages
       • No need for physical cables
       • The laptop or device can work anywhere within range of a WAP
       • Can work through walls and on different floors as long as the radio signal is not too weak
       • Smartphones can roam the Internet through the home network without incurring expensive 3G charges
       • Sufficient bandwidth for most Internet use, streaming and online gaming requires more
       • WiFi certified devices are guaranteed to be compatible
     • Disadvantages
       • Slower than cabled networks
       • Requires a Wireless Access Point (WAP)
       • Requires encryption to ensure data privacy
       • It can only support a limited number of simultaneous connections
       • Performance depends on the structure of the building and any obstacles there may be weakening the radio signal