GPRS Air Interface
• New ‘Packet’ logical channels defined - PBCCH, PDTCH etc.
• New multiframe structure based on ‘radio blocks’ of 4 timeslots
• Allows up to 8 mobiles to share a timeslot
• For high data rates, several physical channels may be allocated to
one user
• 4 levels of channel coding schemes (CS-1 to CS-4):
• Decreasing level of error checking
• Greater data throughput rates
• Scheme selected according to
interference level (C/I)
• GPRS can use traffic capacity on
the GSM network away from the
busy hour for non time critical data
transfers
• Even during the busy hour, there
is spare capacity that GPRS can
make use of:
• Voice calls start and finish at
random times, leaving short
periods when channels are
unused
• Packets of data can be sent when
these channels become available -
dynamic allocation
• New ‘Packet’ logical channels defined - PBCCH, PDTCH etc.
• New multiframe structure based on ‘radio blocks’ of 4 timeslots
• Allows up to 8 mobiles to share a timeslot
• For high data rates, several physical channels may be allocated to
one user
• 4 levels of channel coding schemes (CS-1 to CS-4):
• Decreasing level of error checking
• Greater data throughput rates
• Scheme selected according to
interference level (C/I)
• GPRS can use traffic capacity on
the GSM network away from the
busy hour for non time critical data
transfers
• Even during the busy hour, there
is spare capacity that GPRS can
make use of:
• Voice calls start and finish at
random times, leaving short
periods when channels are
unused
• Packets of data can be sent when
these channels become available -
dynamic allocation
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