First generation cellular networks used frequency division multiple access (FDMA) to operate over analog signals in the 900MHz frequency range. The network consisted of base stations that communicated with mobile devices and switching centers that managed calls and handovers between base stations. As users moved between cells, their calls were handed off between base stations using different frequencies to avoid interference. However, 1G networks had limitations such as a lack of roaming compatibility across countries and standards, low capacity, and dropped calls during handovers.

1. First Generation
Network
Muhammad Uzair Rasheed
2009-CPE-03
UCE&T BZU MULTAN

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

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

4. First Generation
 1st Generation devices
 Introduced in the UK by Vodafone
 January 1985
 UK Technology (and Italy)
 Total Access Cellular System
 This was based on the American design
 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. 1G technology
 FDMA
 Breaks up the available frequency into 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 analog data.

7. Continued …
 FDMA
Frequency

8. Continued….
 FDMA
 You use this technology all of the time!
 Consider your radio in the house(well use too!!!)
 As you want different information you change the frequency
which you are receiving

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

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/hand off)

12. First Generation
 Cellular Architecture
 Allows the area to be broken into smaller cells
 The mobile device then connects to the closest
cell
Cell
Cell Cell
Cell Cell Cell
Cell Cell Cell Cell
Cell Cell Cell
Cell 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
Cell Cell Cell Frequency 900
Cell

14. First Generation
 Cellular Architecture continued
 There must be a frequency difference
between adjoining cells.
Cell Frequency 900
Cell Frequency 920
Cell
Cell Cell Cell Frequency 940
Cell
Cell Frequency 960

15. First Generation
 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 Cell
Cell Cell
Cell

16. 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
 Cell sizes are flexible
 Examples in the AMP system were up to 50 Miles!

17. 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 area covered by a certain cell
ends so it switches over to the domain of the next cell.

18.  Cellular infrastructure
 Communicating with BS1
 Moving towards BS2
Tnm
rasis
snS
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SBosm
n i nT
is s
ar
1
BS1
BS2

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

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

21. 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
 The phone returns to an idle state and pagging ends

22. First Generation
 Problems
 Roaming was not applicable
 All of Europe was using different standards
 Different frequencies
 Different frequency spacing
 Security
 Calls were easily ‘listened’ upon
 Limited capacity of the available spectrum
 Analog 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….

23.  Summary
 1G systems
 Frequency Used
 Infrastructure
 Handover
 Problems
Jazak Allah!!!!