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.
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)
10.
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
ioB2
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!!!!