Mobile phones and networks (lecture 2)

Written by: Jonathan Briggs

February 8, 2007 [2990 views]

Radio spectrum

• Radio spectrum is a finite resource and divided into different uses by national and international agreements
• Mobile and other wireless technologies have been granted permission (a licence) to transmit and receive within particular radio frequencies ranges
• Companies pay to operate these licences

How the radio spectrum works
US Spectrum Allocation
Europes Wireless Potential

Mobile network

• Network of base stations (towers, antenna)
• Offers multiple channels
• Can handle multiple calls/data transmissions on each channel through code (CDMA), frequency (FDMA) or time based (TDMA/GSM) multiplexing
• Coverage affected by topography (hills, buildings)
• Mobile switching centres – transfer calls and data within the network and into the Internet and conventional phone network
• Can locate a customer when an incoming call needs to be routed
• Identifies each subscriber through information about phone and handset ID
• Records the location of every phone in its area
• Base station monitors signal strength and may ask the network to handover the call to another base station
• Must accept emergency calls from any phone on any network

how mobile networks work (O2)

Handset/terminal

• SIM card – identity, address book and preferences
• Power supply – battery technology still a limit on power and battery life
• Radio transmitter & receiver – maintain a two-way conversation with the network
  Keypad
• Operating System – provides support environment for applications
• RAM – local storage to record recent calls, text messages etc
• Storage – card storage for long term storage of data, images and applications
• Antenna – often hidden within the case these days
• CPU – processor that runs the operating system and applications
• Bluetooth – alternative communications module
• WiFi – alternative communications module
• LCD Screen
• Speaker/Microphone
• Cameras – for image capture and video conferencing

Whats inside a mobile?(How Stuff Works)

Mobile Operating System:Symbian
Mobile Operating System:Windows Mobile
Mobile Operating System:Palm OS
Mobile Operating System:OS X?

Limitations of mobile phones

Screen size: 96x65, 128x128, 176x208, 640x200 (Nokia), 320x480 (iPhone)
Battery life: 5 hours talk time, 3 hours video watching?
Memory: 6M (Nokia 6680)
Data transfer speeds: 9.6k, 14.4k (GSM), 32k-48k (GPRS), 384k (3G)
Cost: £1-10 per Mbyte

How does this affect building a mobile business or application?

• Need to build services based on the functional characteristics of existing devices or persuade handset manufacturers to change the devices
• Need to be aware of the limitations of the devices: memory, processor power, data transfer
• Need to consider user acceptance

Some examples to consider

• How would you provide network coverage on the Underground?
• What would be possible if the screen or memory was bigger or costs were lower?

What do you think?

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