26-07-2012, 10:24 AM
Transport Formats in UMTS Radio Network Controller’s Software
[attachment=28987]
Introduction
3G networks offer
wide range of advanced services
constantly growing network capacity, shorter delay times and higher bit rates
seamless mobility and inter-working with the existing GSM/GPRS networks
Need for resource optimisation from all underlying network components
Transport formats (1/3)
Data transfer between MAC and PHY is organised by the transmission of transport blocks.
One transport block belongs to one transport channel
Several transport blocks can be sent simultaneously transport block set
Transmission Time Interval (TTI) defines the time interval between two subsequent transport block set transfers between MAC and PHY
Transport format implementation in the RNC (1/3)
The RNC consists of several different hardware and software layers
System blocks, service blocks and program blocks
One particular program block was investigated in Radio Resource Management (RRM) area
Completely new program block, a result of a major architectural change
Responsible for RRM related tasks and Layer 3 signalling inside the RNC
Interfaces to a couple of other program blocks and RNC’s internal database
Performs TFS and TFCS calculation for one Radio Resource Control (RRC) connection
RRC connection setup
State transition from Cell_FACH to Cell_DCH
RAB establishment / modification / release
SRNC relocation
Compressed mode activation / deactivation
Transport format implementation in the RNC (2/3)
TFS calculation is performed in one code module (Module 6)
For each DCH separately, both uplink and downlink direction
Based on DCH type and maximum bit rates
HSDPA and HSUPA not considered here (TF calculation in the Node B)
Maximum of 8 simultaneous DCHs
Own internal procedures for calculating the different parts of the TFS
TFCS calculation is performed in another code module (Module 7)
Calculation is based on current DCH list and their TFS parameters
Calculated Transport Format Combination (CTFC) is a tool for efficient signalling of transport format combinations (3GPP TS 25.331)
UE-capability is taken into account and it may also set limitations to TFCS
Generally more complex than TFS calculation
Transport format implementation in the RNC (3/3)
The implementation has been ported from the old architectural solution, dates back to year 2002 and 2003
Originally 3500 code lines in Module 6 and 4000 code lines in Module 7
Deploys global data structures, problems with information hiding
Now the code was fully inspected and improved
Lots of commentary lines were added, code optimisation was done and obsolete code was removed – also minor bugs were corrected
The implementation still deploys global data structures and clumsy data conversions that could (and should) be improved
More profound changes and a complete re-design are still possible
The software is under constant state of change – code maintainability and proper testing is important
[attachment=28987]
Introduction
3G networks offer
wide range of advanced services
constantly growing network capacity, shorter delay times and higher bit rates
seamless mobility and inter-working with the existing GSM/GPRS networks
Need for resource optimisation from all underlying network components
Transport formats (1/3)
Data transfer between MAC and PHY is organised by the transmission of transport blocks.
One transport block belongs to one transport channel
Several transport blocks can be sent simultaneously transport block set
Transmission Time Interval (TTI) defines the time interval between two subsequent transport block set transfers between MAC and PHY
Transport format implementation in the RNC (1/3)
The RNC consists of several different hardware and software layers
System blocks, service blocks and program blocks
One particular program block was investigated in Radio Resource Management (RRM) area
Completely new program block, a result of a major architectural change
Responsible for RRM related tasks and Layer 3 signalling inside the RNC
Interfaces to a couple of other program blocks and RNC’s internal database
Performs TFS and TFCS calculation for one Radio Resource Control (RRC) connection
RRC connection setup
State transition from Cell_FACH to Cell_DCH
RAB establishment / modification / release
SRNC relocation
Compressed mode activation / deactivation
Transport format implementation in the RNC (2/3)
TFS calculation is performed in one code module (Module 6)
For each DCH separately, both uplink and downlink direction
Based on DCH type and maximum bit rates
HSDPA and HSUPA not considered here (TF calculation in the Node B)
Maximum of 8 simultaneous DCHs
Own internal procedures for calculating the different parts of the TFS
TFCS calculation is performed in another code module (Module 7)
Calculation is based on current DCH list and their TFS parameters
Calculated Transport Format Combination (CTFC) is a tool for efficient signalling of transport format combinations (3GPP TS 25.331)
UE-capability is taken into account and it may also set limitations to TFCS
Generally more complex than TFS calculation
Transport format implementation in the RNC (3/3)
The implementation has been ported from the old architectural solution, dates back to year 2002 and 2003
Originally 3500 code lines in Module 6 and 4000 code lines in Module 7
Deploys global data structures, problems with information hiding
Now the code was fully inspected and improved
Lots of commentary lines were added, code optimisation was done and obsolete code was removed – also minor bugs were corrected
The implementation still deploys global data structures and clumsy data conversions that could (and should) be improved
More profound changes and a complete re-design are still possible
The software is under constant state of change – code maintainability and proper testing is important