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Cellular Networks

Cellular Networks. How do Mobile & Satellite Phones work? What can we do with them?. Learning Objectives:. By the end of this topic you should be able to: describe how a mobile phone network operates; describe the use of cellular and satellite mobile phone systems

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Cellular Networks

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  1. Cellular Networks How do Mobile & Satellite Phones work? What can we do with them?

  2. Learning Objectives: By the end of this topic you should be able to: • describe how a mobile phone network operates; • describe the use of cellularandsatellite mobile phone systems • describe the advantages and disadvantages of cellularandsatellite mobile phone systems and their use; • describe how mobile technology and networks can  enable communication from anywhere in the world;

  3. Mobile Communications topics:

  4. How does that work……? • Explain how a mobile phone network works. [4] • Describe how an call from a mobile telephone, anywhere in the UK, is routed to a landline telephone in Spain. [6] • Identify three limitations on the use of a mobile telephone. [3] • Describe how the emergency services can find the exact location of a mobile phone that is being used to make an emergency call in the UK. [6]

  5. How does it happen? Steps ?

  6. Terminology used:

  7. Base Station Transceiver

  8. Terminology used: • Cells • the area covered by a network is broken down into cells, • each cell has a Base Station Transceiver (BST), • a mobile ‘phone mast that gives coverage to that cell • Base Station Controllers (BSC) • manages communication between a set of BSTs and the MSC • a Mobile Switching Centre (MSC) • controls all of the calls taking place on the network • when a mobile phone moves into a new cell: • it registers with the BSC • a database stores the current locations of mobile ‘phones

  9. Terminology used:

  10. Calling a Mobile ‘Phone • caller dials the number from the mobile ‘phone • mobile phone sends a call request to a Base Station Transceiver • mobile phone connects to BST with the best signal (nearest) • transceiver sends request to base station switching centre (BSC) • BSC connects to the Mobile Switching Centre (MSC) • MSC checks the caller’s status • enough credit to make the call? • MSC identifies which BSC the receiving ‘phone is connected to • by searching a database (updated in real-time) • BSC sends a ‘request to dial’ signal to all BSTs under its control • mobile phone receives the request and acknowledges it to the BST • call is connected by the MSC • if user is 'on the move' when making the call • system detects this and transfers call to next cell

  11. Base Station Controller (BSC)

  12. Base Station Controller (BSC)

  13. Base Station Controller (BSC) • BSC controls one or more base transceiver stations (BTS) • base stations or cell sites. • BSC is a high capacity sitch • a BSC may have tens or hundreds of BTSs under its control. • a BSC communicates with the MSC • The BSC handles allocation of radio channels, receives measurements from the mobile phones, and controls handovers from BTS to BTS (except in the case of an inter-BSC handover in which case control is in part the responsibility of the anchor MSC). • networks are often structured to have many BSCs distributed into regions near their BTSs which are then connected to large centralised MSC sites.

  14. Mobile Switching Centre (MSC)

  15. Mobile Switching Centre (MSC) • large cellular network will require multiple MSCs. • MSC controls handovers between multiple BSCs • on detecting that a mobile device is approaching the edge of its cell, a BSC requests handover assistance from its MSC. • MSC then scans a list of adjacent cells and their corresponding BSCs and facilitates the handover to the appropriate BSC. • For this task, the MSC works with a large database known as the home location register (HLR), which stores relevant location and other information for each mobile phone.

  16. Mobile Communication trends • not just voice data • SMS, email, Internet, IM, …. • higher bandwidth telecommunication • GPRS, 3G, 4G • convergence with other mobile technologies • ‘phone includes other devices (GPS, digital camera …) • PDA capabilities • address book, calendar, …. • synchronisation with other computing devices • = same, real-time data available on all devices & everywhere • not just ‘phones  tablet devices, convertibles

  17. Mobile ‘Phone Features • digital camera • still & video (video conferencing) • media playback • mp3, video, radio • high resolution, colour display • touch screen interface • wireless connectivity – IR, Bluetooth, WiFi • GPS / Satellite Navigation

  18. Advantages & Disadvantages

  19. Advantages • mobile phones can be used anywhere there is a signal • users are not restricted to sitting in an office or at home to make and receive calls

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