1. First Generation Justin Champion C208 Ext:3273

2. First Generation What we will look at 1 st Generation technology Analogue signals Frequency Division Handover Infrastructure

3. First Generation Early Wireless communications Signal fires Morse Code Radio Radio Transmitter 1928 Dorchester

4. First Generation 1 st Generation devices Introduced in the UK by Vodafone January 1985 UK Technology (and Italy) Total Access Cellular System (TACS)  This was based on the American design of AMPS Used the 900MHz frequency range Europe Germany adopted C-net France adopted Nordic Mobile Telephone (NMT)

5. First Generation Operates Frequency Division Multiple Access (FDMA) Covered in next slide Operates in the 900MHz frequency range Three parts to the communications  Voice channels  Paging Channels  Control Channels

6. PCS – 1G to 2G technology FDMA Breaks up the available frequency into 30 KHz channels Allocates a single channel to each phone call The channel is agreed with the Base station before transmission takes place on agreed and reserved channel The device can then transmit on this channel  No other device can share this channel even if the person is not talking at the time!  A different channel is required to receive The voice/sound is transmitted as analogue data, which means that a large than required channel has to be allocated.

7. PCS – 1G to 2G technology FDMA Frequency

8. PCS – 1G to 2G technology FDMA You use this technology all of the time! Consider your radio in the house As you want different information you change the frequency which you are receiving

9. PCS – 1G to 2G technology Voice calls Are transferred using Frequency modulation The rate at which the carrier wave undulates is changed Encoding information More resistant to interference than AM radio (www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0030280.html, 2004)www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0030280.html

10. PCS – 1G to 2G technology 1G infrastructure Mobile Switching Centre PSTN

11. First Generation Infrastructure Base Station Carries out the actual radio communications with the device Sends out paging and control signals MSC Takes responsibility  Controls all calls attached to this device  Maintains billing information  Switches calls (Handover)

12. First Generation Cellular Architecture Allows the area to be broken into smaller cells The mobile device then connects to the closest cell Cell

13. First Generation Cellular Architecture continued Cellular architecture requires the available frequency to be distributed between the cells If 2 cells next to each other used the same frequency each would interfere with each other Cell Frequency 900

14. First Generation Cellular Architecture continued There must be a distance between adjoining cells This distance allows communications to take place Cell Frequency 900 Frequency 920 Frequency 940 Frequency 960

15. First Generation Cellular Architecture continued This is referred to as the “Minimum Frequency Reuse Factor” This requires proper planning and can be an issue for all radio based wireless communications Planning the radio cell and how far a signal may go Cell

16. First Generation Radio Planning Logically we picture a cell as being a Octagon In reality the shape of a transmission will change depending on the environment In this diagram of a cell you can see this  The building are the rectangles in dark green  The darker the shade of green the stronger the signal Cell

17. First Generation Radio Planning Planning needs careful thought You must cover the entire area with the minimum of base stations Base stations cost the company money They also make the potential for radio problems greater Simulations can be used but accurate models of the area is required Best solution is to measure the signals at various points  From this a decision can be made Cell

18. First Generation Cellular infrastructure why ?? Cells with different frequencies allow devices to move between these cells The device just informing what frequency they are communicating at Cellular communications can only travel a certain distance Discussed in the wireless LAN’s lecture Cell sizes are flexible  Examples in the TUK TACS system were up to 50 Miles!

19. First Generation Cellular infrastructure Once you get to the ‘edge’ of a cell you will need a handover Handover allows the user to move between cells  After a certain distance the amount of data which is sent in error becomes greater than the data sent correctly at this point you need to connect to a new cell which is closer.  TACS carries this out by monitoring the amplitude of the voice signal

20. First Generation Cellular infrastructure Communicating with BS1 Moving towards BS2 BS2 BS1 Transmission BS2 Transmission BS1

21. First Generation Cellular infrastructure Power of signal now weakening BS2 BS1

22. First Generation Cellular infrastructure Paging signal stronger so hand over to new MSC BS2 BS1

23. First Generation Handover Once a handover is decided upon by the BS The MSC is informed  All BS in the area of the current location are informed to start paging the device  The BS with the strongest signal is then handed over to  The call can continue  In reality a lot of calls were dropped whilst waiting for a handover to take place Ending a call A 8Khz tone is sent for 1.8 seconds  The phone then returns to an idle state

24. First Generation TACS Problems Roaming was not applicable outside of the UK  All of Europe was using different standards  Different frequencies  Different frequency spacing  Different encoding technologies Security  Calls were easily ‘listened’ upon  Limited capacity of the available spectrum  Analogue signal meant a larger than required amount of the frequency had to be allocated to each call  Expansion of the network was difficult This was unacceptable  GSM was introduced  Next weeks lecture!

25. First Generation Summary 1G systems TACS Frequency Use Infrastructure Handover Problems