01-01-2013, 12:15 PM
First Generation
[attachment=45960]
Early Wireless communications
Signal fires
Morse Code
Radio
1st 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)
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
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.
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
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!
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
[attachment=45960]
Early Wireless communications
Signal fires
Morse Code
Radio
1st 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)
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
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.
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
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!
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