SLIDE 1
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16: Networks 2: Wireless world
Computer literacy 1
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Introduction
- Quick overview of Wireless technologies
- Focus on mobile phones
- Wireless issues:
– Security – Interference
- Applications of Wireless technology
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LAN Mesh Networks
- Each device
– Sender, Receiver, Repeater, Router
- Connection topology
– All-to-all – Partial: all nodes connected to a number of others
- Issues
– Reliable: remember ARPANET – Lots of wiring: expensive to set up and to reorganise – Star or bus topologies can be cheaper to set up – Wireless Mesh networks (see later)
CL1 2007/08
Web server / network DIY
- Run server software, e.g. Apache
- Open up to the outside world
– Drill hole in firewall for port 80 – If local network is NAT addressed then route – port 80 traffic to server
- Fixed address (no DHCP)
- What is NAT addressing?
– Local non-unique network addresses
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Wireless Mesh Network
- Advantages of no wire
– More flexible organisation – No intrusive wiring: good for home use – Cost of changing network organisation cheaper
- Disadvantages
– Interference: other users – Interference: the environment (weather, walls etc)
- Though this works both ways
– Security: restricting use to network members – Security: protecting transmitted data
CL1 2007/08
Wireless technologies
- Infra-red (e.g. remote controls)
– 1-4 MBps – Low power use – Must be in line of sight
- Radio
– 2 MBps – Long distance
- Microwave radio (e.g. long distance telephone