1. 1© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Seminaariesitelmä / Jukka Valtanen / 08.01.2008

2. 2© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Introduction – 3G network structure UTRA radio interface protocol architecture – logical channels / transport channels / physical channels Transport formats – data transmission between the physical (L1) and data link (L2) layer – transport format set (TFS) / transport format combination set (TFCS) Transport format implementation in the RNC – RNC software architecture / program block under investigation – current implementation / analysis / improvements / further changes Testing of transport formats in RNC software – testing process / testing methods / testing environment – test cases / analysis / improvements / results Discussion and conclusion

3. 3© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Introduction - 3G network structure (1/2) – 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 GSM = Global System for Mobile CommunicationsGPRS = General Packet Radio Service

4. 4© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Introduction - 3G network structure (2/2) CN = Core Network RNC = Radio Network Controller UE = User Equipment UMTS = Universal Mobile Telecommunications System UTRAN = UMTS Terrestrial Radio Access Network The RNC is a service access point for all services that UTRAN provides the core network. It owns and controls radio resources in its domain, i.e. Node Bs connected to it.

5. 5© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation UTRA radio interface protocol architecture (1/3) 3GPP TS 25.201 “Physical layer - general description” version 7.3.0 Release 7(2007-06)

6. 6© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation UTRA radio interface protocol architecture (2/3) Physical channels: Transport channels: Logical channels: layer 1 communication streams (frequency, scrambling etc.) 5 dedicated UL channels and 1 common UL channel 4 dedicated DL channels and 10 common DL channels a service offered by the physical layer (L1) to the MAC how and with what characteristics data is transferred 2 dedicated channels (DCH, E-DCH) 5 common channels (BCH, FACH, PCH, RACH, HS-DSCH) the RNC deals with transport channels a service provided by the MAC layer to higher layers for which purpose and what type of data is transferred 6 control channels 3 traffic channels DCH = Dedicated ChannelE-DCH = Enhanced Dedicated ChannelBCH = Broadcast Channel FACH = Forward Access ChannelPCH = Paging Channel RACH = Random Access ChannelHS-DSCH = High Speed Downlink Shared Channel

7. 7© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation UTRA radio interface protocol architecture (3/3) – Mapping of transport channels onto physical channels

8. 8© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation 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

9. 9© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Transport formats (2/3) – Transport Format (TF)  Defines the characteristics of a transport channel  Specifies the physical layer processing to be applied to the channel  Controls how much data is transferred during one TTI and how the data is coded etc. by the physical layer  Semi-static part and dynamic part – Transport Format Set (TFS)  The set of transport formats associated to a transport channel  Enables variable data rates (multiple parameter sets) TTI = Transmission Time Interval CRC = Cyclic Redundancy Check TB = Transport Block

10. 10© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Transport formats (3/3) – Transport Format Combination Set (TFCS)  Several transport channels can be multiplexed together  The set of transport format combinations of currently valid transport formats TFI = Transport Format IndicatorTFCI = Transport Format Combination Indicator

11. 11© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 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 Formats in UMTS Radio Network Controller’s Software Implementation RAB = Radio Access BearerSRNC = Serving Radio Network Controller

12. 12© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation 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 DCH = Dedicated Channel HSDPA = High Speed Downlink Packet AccessHSUPA = High Speed Uplink Packet Access

13. 13© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation 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

14. 14© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Testing of transport formats in RNC software (1/2) – The product and all program blocks are tested in separate phases  Module testing (the focus in the thesis) integrated part of design and implementation new functionalities should be verified as soon as possible regression testing after major corrections or other changes in later phases should be thorough (code coverage), repeatable, well maintainable and automatic  Integration and load testing  Functional testing  System testing – Testing methods  Black box testing: no insight into the code itself, based on inputs and outputs  White box testing: system state can be observed, more complicated  Hybrid test strategies

15. 15© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Testing of transport formats in RNC software (2/2) – Windows workstation + RNC software emulator + definition database – 47 initial test cases were prepared for TFS and TFCS features  mainly different kind of RAB setup scenarios  other TFS/TFCS calculation scenarios use the same procedures  inputs sent to the program block  calculation  output data verified – Test cases were inspected and analysed for code coverage properties – During the thesis work, a need for some changes was discovered  10 test cases updated  6 totally new test cases designed  all 53 test cases finally passed, no bugs found in later testing phases – Designed test case set will remain as an essential part of normal regression testing of the program block

16. 16© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Discussion and conclusion (1/1) – Transport formats are applied in the data exchange between the physical layer and the data link layer – Transport formats enable variable bit rates and multiplexing of services – The theory is largely based on 3GPP specifications, but manufacturer specific implementations enable efficient usage of radio resources – The program code of a program block in RRM area was inspected and analysed – Code maintainability was improved and minor bugs were corrected – Testing of TFS and TFCS functionalities was carried out, a test case set was designed and the related code was found to be fully functional – Used testing methods were considered to be applicable – The observed features are now fully tested in module level testing – The obtained results will act as a reference for any future improvements

17. 17© Nokia Siemens NetworksSeminaariesitelmä / Jukka Valtanen / 08.01.2008 Transport Formats in UMTS Radio Network Controller’s Software Implementation Thank you!