first generation network
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TRANSCRIPT
First GenerationNetwork
Muhammad Uzair Rasheed
2009-CPE-03
UCE&T BZU MULTAN
First Generation
What we will look at 1st Generation technology Frequency Division Handover Infrastructure
First Generation
Early Wireless communications Signal fires Morse Code Radio
Radio Transmitter 1928 Dorchester
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)
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
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.
FDMAFrequency
Continued …
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
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)
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)
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
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
Cell Frequency 900
First Generation
Cellular Architecture continued There must be a frequency difference
between adjoining cells.
Cell
Cell Cell
CellCell
Cell
Cell
Cell Frequency 900
Frequency 920
Frequency 940
Frequency 960
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
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!
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.
Cellular infrastructure Communicating with BS1
Moving towards BS2
BS2BS1
Transmission BS2Transmission BS1
First Generation
Cellular infrastructure Power of signal now weakening
BS2BS1
First Generation
Cellular infrastructure Paging signal stronger so hand over to new MSC
BS2BS1
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
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….
Summary 1G systems Frequency Used Infrastructure Handover Problems
Jazak Allah!!!!