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Content and rem..

TCS 316 High Speed Information Networks UMTS Handover by Nasir Faruk Email: nasirfaruk@ieee.org Mobile +234 8032428141 Week 13 May , 2014. Content and rem. Weeks 13 Cell Search procedure (Skipped) Handover Softer Soft Hard Sectorisation (Briefly taught last semester).

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Content and rem..

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  1. TCS 316High Speed Information NetworksUMTS HandoverbyNasir FarukEmail: nasirfaruk@ieee.orgMobile +234 8032428141Week 13May, 2014

  2. Content and rem.. • Weeks 13 • Cell Search procedure • (Skipped) • Handover • Softer • Soft • Hard • Sectorisation (Briefly taught last semester) • Weeks 14 ( To be skip. You met it in industry when lucky hahaha) • IP • IP Mobility • Mobile IP • VoIP

  3. wray castle browser wray castle browser Internet Search Internet Search http:/www.wraycastle.co.uk http:/www.wraycastle.co.uk XXXXXXX XXX XXXXXXX XXX XXXXX XXXX XXXXX XXXX XXXX XXX XX XXXX XXX XX Air Interface Modes UMTS Core Network Frequency Division Duplex Mode 1 Direct Sequence Mode CDMA UMTS Terrestrial Radio Access network (UTRAN) Time Division Duplex Mode 1 TD-CDMA User Equipment (UE) FDD Mode User Equipment (UE) TDD Mode Figure 2

  4. Handover Types • Within UTRA FDD – Intra-Mode Handover • Soft • Softer • Hard (intra- or inter-frequency) • Inter Mode Handover • Handover to UTRA TDD – not implemented yet! • Inter-system Handover • In R99 means only to GSM handover • In R8 & LTE (E-UTRA or E-UTRAN) means handover to and from LTE (Long Term Evolution).

  5. Effect on Capacity with Contiguous Coverage Cell A Cell B Cell A in isolation 10 channels Cell B in isolation 10 channels Interference Capacity of Cells A and B is less than 20 because of increased interference Figure 9

  6. Cell Capacity 10 users using 10 kbit/s channel Total Cell Capacity = 100 kbit/s 2 users using 50 kbit/s channel Total Cell Capacity = 100 kbit/s Figure 10

  7. wray castle browser wray castle browser Internet Search Internet Search http:/www.wraycastle.co.uk http:/www.wraycastle.co.uk XXXXXXX XXX XXXXXXX XXX XXXXX XXXX XXXXX XXXX XXXX XXX XX XXXX XXX XX Power Control at Cell Boundaries Power Control instructs mobile to turn power up Increase in interference here Power Control Node B 1 Node B 2 Figure 29

  8. Necessity for Soft/Softer Handover • Essentially to avoid interference • Mobile could penetrate far into adjacent cell without being power controlled by that cell • This could be overcome by the use of very fast and frequent hard handovers • Not efficient as too much signalling involved.

  9. wray castle browser Internet Search http:/www.wraycastle.co.uk XXXXXXX XXX XXXXX XXXX XXXX XXX XX Soft Handover Power Control B Power Control Node B 2 Node B 1 Soft Handover – make before break Figure 30

  10. WCDMA Soft Handover • Active set - the cells participating in the soft handover • Normally just 2 cells • Neighbour or monitored set • Cells that the UE continuously measures • Pilot Ec/No not strong enough to be added to the active set

  11. wray castle browser Internet Search http:/www.wraycastle.co.uk XXXXXXX XXX XXXXX XXXX XXXX XXX XX UE Measurements GSM BTS Inter- system Node B Intra- frequency Node B Micro Inter- frequency RLC Buffer Downlink Quality Intra-frequency Uplink Traffic Volume Node B Internal TX power RSSI UE Local Measurement Figure 21

  12. Ec/No Measurement from CPICH • UTRA FDD intra-mode handover relies on the Ec/No measurement performed from the CPICH. • Quantities defined that can be measured by the terminal from the CPICH are as follows: • Received Signal Code Power (RSCP) – received power on one code after despreading defined on the pilot symbols; • Received Signal Strength Indicator (RSSI) – wideband received power within the channel bandwidth; • Ec/No = RSCP/RSSI, i.e. RSCP divided by the total power in the channel bandwidth.

  13. WCDMA Handover Algorithm • If a neighbour cell pilot channel signal remains better than the current best cell’s pilot minus a hysteresis value for a timeout period the neighbour cell may be added to the active set. • If an active cell signal is worse than that of the current best cell minus a different hysteresis value for a short period it may be removed from the active set. • If a neighbour cell signal is better than the current worst active cell plus a third different hysteresis value for the timeout period it may replace that worst active cell.

  14. wray castle browser Internet Search http:/www.wraycastle.co.uk XXXXXXX XXX XXXXX XXXX XXXX XXX XX Soft Handover Region Two-Cell Case Soft handover region A B Start End Figure 31

  15. Soft Handover Region Three-Cell Case Three-way handover Required here B A C Figure 31 (continued)

  16. Example of a Soft Handover Quality Cell A Timer Timer Timer Macro Remove Threshold Macro Add Threshold Timer Macro Replacement Threshold Cell B Cell C Time 1. 2. 3. Full specification is in 3GPP TR 25.922 V6.0.1 (2004-04)

  17. Soft vs Softer Handover Softer Handover – also make before break

  18. Softer Handover • Between two cells or sectors supported by the same Node B • UE transmits & receives from both cells simultaneously: • UE combines downlink information • Node B combines uplink information • Only one power control loop • Both soft & softer handover may occur simultaneously • Soft/softer handover at the UE & softer at the Node B • Similar to multipath reception • Two separate downlink codes • RAKE fingers need to generate two codes

  19. Soft Handover at the RNC • Uplink data routed to RNC for combining • Better frame selected • After each interleaving period 10-80 ms • Outer loop power control frame reliability indicator utilised.

  20. Serving & Drift RNC

  21. Serving & Drift RNC

  22. Serving & Drift RNC

  23. wray castle browser Internet Search http:/www.wraycastle.co.uk XXXXXXX XXX XXXXX XXXX XXXX XXX XX Macro and Micro Diversity Macro Diversity Combining at RNC for Soft Handover RNC Cell A Soft Handover Cell B Softer Handover Node B Node B Micro Diversity Combining at Node B for Softer Handover UE Figure 36

  24. UMTS Hard Handover • Between two cells using different carrier frequencies • Between cells whose Nodes B are • connected to different RNCs without the Iur interface • To and from GSM

  25. Handover and External Reselection Related Procedures UMTS Core Network GSM Core Network RNC BSC Node B micro Node B macro Node B macro BTS Hard Handover Soft Handover Hard Handover within UTRAN within UTRAN outside UTRAN Reselection outside UTRAN Figure 19

  26. wray castle browser Internet Search http:/www.wraycastle.co.uk XXXXXXX XXX XXXXX XXXX XXXX XXX XX UMTS Handover Types - Summary GSM Hard Handover – break before make UMTS Micro UMTS Macro C Hard B Hard A Soft UMTS Macro UE A = intra-frequency B = inter-frequency C = inter-system Figure 33

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