Cell search,paging and uplink access in CDMA systems Song Pengpeng
Contents <ul><li>Cell search in cdma2000 and WCDMA </li></ul><ul><ul><li>Acquisition in cdma2000 </li></ul></ul><ul><ul><l...
Acquisition in CDMA2000 <ul><li>Pilot channel </li></ul><ul><li>Pilot Channel is effectively the   PN sequences itself   a...
Acquisition in CDMA2000 <ul><li>The Sync Channel carries baseband information at 1.2 kbps and is spread by Walsh function ...
Acquisition in CDMA2000 <ul><li>Pilot channel for short code acquisition--- search window of 26.66ms </li></ul><ul><li>Dec...
Acquisition in CDMA2000 <ul><li>Ec/No @-21dB at cell boundary; </li></ul><ul><li>The sync channel can be reliably decoded ...
Cell search  in WCDMA <ul><li>cell search---to resolve code ,time and frequency ambiguity. </li></ul><ul><ul><li>Power on-...
Cell search  in WCDMA <ul><li>Sync channels in a cell search for WCDMA </li></ul>“ cell searching in WCDMA”,Sanat Kamal Ba...
Cell search  in WCDMA <ul><li>Stage 1: Slot synchronization by PSC </li></ul>Autocorrelation function over the full PN per...
Cell search  in WCDMA <ul><li>Stage 2: frame synchronization and GI(Group Indicator) identification </li></ul>“ Initital c...
Cell search  in WCDMA <ul><li>Stage 3: scrambling code identification </li></ul><ul><ul><li>---symbol-wise correlation ove...
Cell search  in WCDMA “ Cell search in WCDMA”, Yi-Pin Wang, Tony Ottosson, IEEE joural on selected areas in communications...
Cell search  in WCDMA <ul><li>It can be seen that for a 90% reliability, the acquisition time is around  500 ms at the cel...
Cell search  in WCDMA <ul><li>Average acquisition time with different radio configuration parameter </li></ul>“ Cell searc...
Paging channel in CDMA2000 <ul><li>QPCH, BCCH and CCCH replace the paging channel in IS95. </li></ul><ul><ul><li>Enabling ...
Paging channel in WCDMA <ul><li>PCH+FCCH  Secondary Common Control Channel </li></ul><ul><li>PICH: to carry the paging in...
Enhanced random access in CDMA2000 <ul><li>IS95 access mode: slotted ALOHA mode </li></ul><ul><li>New features in CDMA2000...
Enhanced random access in CDMA2000 <ul><li>REACH: Basic Access mode </li></ul><ul><li>Involved channels: </li></ul><ul><ul...
Enhanced random access in CDMA2000 <ul><li>REACH: Power control access mode </li></ul>“ Enhanced Random Access and Reserva...
Enhanced random access in CDMA2000 <ul><li>REACH: reservation access mode </li></ul>A reservation access probe followed by...
Enhanced random access in CDMA2000 <ul><li>Enhanced access procedures </li></ul>Monitors the Ec/Io RA mode for long data b...
Random access scheme in WCDMA <ul><li>Initial access scheme proposed in [*] </li></ul><ul><ul><li>In use of Orthogonal sig...
Random access scheme in WCDMA <ul><li>RACH access: acknowledged by AICH </li></ul><ul><ul><li>Minimized buffer requirement...
Random access scheme in WCDMA <ul><li>CPCH access scheme: acknowledged by AP-AICH and CD/CA-ICH </li></ul><ul><ul><li>DSMA...
Random access scheme in WCDMA <ul><li>RACH---for fast access and short/medium packets </li></ul><ul><ul><li>High rate RACH...
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Cell Search,Paging And Uplink Access In Cdma Systems

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a comparison between cdma2000 and wcdma on cell search, paging and random access.

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  • Cell Search,Paging And Uplink Access In Cdma Systems

    1. 1. Cell search,paging and uplink access in CDMA systems Song Pengpeng
    2. 2. Contents <ul><li>Cell search in cdma2000 and WCDMA </li></ul><ul><ul><li>Acquisition in cdma2000 </li></ul></ul><ul><ul><li>Cell search in WCDMA </li></ul></ul><ul><li>Paging in cdma2000 and WCDMA </li></ul><ul><ul><li>Paging channels in cdma2000 </li></ul></ul><ul><ul><li>Paging channels in WCDMA </li></ul></ul><ul><li>Random access in cdma2000 and WCDMA </li></ul><ul><ul><li>Random access in cdma2000 </li></ul></ul><ul><ul><li>Random access in WCDMA </li></ul></ul>
    3. 3. Acquisition in CDMA2000 <ul><li>Pilot channel </li></ul><ul><li>Pilot Channel is effectively the PN sequences itself and contains no information. </li></ul><ul><li>Pilot channel provides the mobile with timing and phase reference. </li></ul><ul><li>Pilot symbol strength is a key measurement in soft handoff. </li></ul>
    4. 4. Acquisition in CDMA2000 <ul><li>The Sync Channel carries baseband information at 1.2 kbps and is spread by Walsh function 32. </li></ul>
    5. 5. Acquisition in CDMA2000 <ul><li>Pilot channel for short code acquisition--- search window of 26.66ms </li></ul><ul><li>Decoding Sync channel --- data rate@2kbps </li></ul>“ Handoff between asynchronous and synchronous systems”, [email_address] , IEEE VTC2000
    6. 6. Acquisition in CDMA2000 <ul><li>Ec/No @-21dB at cell boundary; </li></ul><ul><li>The sync channel can be reliably decoded in 240 ms; </li></ul><ul><li>Maximal boot_up time for cdma2000 system is 325 ms ! </li></ul>“ Handoff between asynchronous and synchronous systems”, [email_address] , IEEE VTC2000
    7. 7. Cell search in WCDMA <ul><li>cell search---to resolve code ,time and frequency ambiguity. </li></ul><ul><ul><li>Power on---for initial cell search </li></ul></ul><ul><ul><li>Idle mode---for identifying new camping cells </li></ul></ul><ul><ul><li>Active mode---for identifying handover candidates </li></ul></ul><ul><li>Cell search procedures </li></ul>“ Cell search in WCDMA”, Yi-Pin Wang, Tony Ottosson, IEEE joural on selected areas in communications, Vol18,No8, August 2000 “ Handoff between asynchronous and synchronous systems”, [email_address] , IEEE VTC2000
    8. 8. Cell search in WCDMA <ul><li>Sync channels in a cell search for WCDMA </li></ul>“ cell searching in WCDMA”,Sanat Kamal Bahl, IEEE Potential 2003; 3gpp TS 25.211~214 Unmodulated orthogonal gold code --- Cp Cs*Dj Cell specific Scrambling code
    9. 9. Cell search in WCDMA <ul><li>Stage 1: Slot synchronization by PSC </li></ul>Autocorrelation function over the full PN period Slot synchronization using the matched filter “ Initital cell search procedure in WCDMA---an imporved algorithm for FDD”, mcinteza@yahool.com,IEEE 2003
    10. 10. Cell search in WCDMA <ul><li>Stage 2: frame synchronization and GI(Group Indicator) identification </li></ul>“ Initital cell search procedure in WCDMA---an imporved algorithm for FDD”, mcinteza@yahool.com,IEEE 2003
    11. 11. Cell search in WCDMA <ul><li>Stage 3: scrambling code identification </li></ul><ul><ul><li>---symbol-wise correlation over CPICH with all scrambling codes within the code group identified in step 2. </li></ul></ul>“ Cell search in WCDMA”, Yi-Pin Wang, Tony Ottosson, IEEE joural on selected areas in communications, Vol18,No8, August 2000 <ul><li>False alarm probability and detection threshold </li></ul>
    12. 12. Cell search in WCDMA “ Cell search in WCDMA”, Yi-Pin Wang, Tony Ottosson, IEEE joural on selected areas in communications, Vol18,No8, August 2000 <ul><li>Initial Cell search procedures </li></ul>30 ms 20 ms 10 ms
    13. 13. Cell search in WCDMA <ul><li>It can be seen that for a 90% reliability, the acquisition time is around 500 ms at the cell boundary of –21dB ! </li></ul>WCDMA acquisition time in AWGN channel WCDMA acquisition time in fading channel “ Handoff between asynchronous and synchronous systems”, [email_address] , IEEE VTC2000 <ul><li>Synchronization time : Ts=Tc/(1-Pe) </li></ul><ul><li>Where </li></ul>
    14. 14. Cell search in WCDMA <ul><li>Average acquisition time with different radio configuration parameter </li></ul>“ Cell search in WCDMA”, Yi-Pin Wang, Tony Ottosson, IEEE joural on selected areas in communications, Vol18,No8, August 2000
    15. 15. Paging channel in CDMA2000 <ul><li>QPCH, BCCH and CCCH replace the paging channel in IS95. </li></ul><ul><ul><li>Enabling Access Probe Handoff(APHO) and Access Handoff (AHO) </li></ul></ul><ul><ul><li>BCCH---cell specific broadcasting information </li></ul></ul><ul><ul><li>CCCH---BS responds to MS </li></ul></ul><ul><ul><li>QPCH---to improve mobile phone standby time </li></ul></ul><ul><ul><ul><li>Single bit messages twice per 80ms slot to direct slotted-mode MS </li></ul></ul></ul><ul><ul><ul><li>Pilot aided coherent OOK detection </li></ul></ul></ul><ul><ul><ul><li>Tri-valued decision:0,1 or Erasure </li></ul></ul></ul>“ The paging channel in cdma2000”,ssarkar@qualcomm.com, IEEE 2000 “ Phone standby time in cdma2000:the quick paging channel in soft handoff”,__,IEEE transactions on vehicular technology,vol 50,No5,Sept 2001. “ soft handoff on the quick paging channel”,__,Globalcomm’99 “ Cdma2000:battery life improvement techniques”,__,IEEE 2000
    16. 16. Paging channel in WCDMA <ul><li>PCH+FCCH  Secondary Common Control Channel </li></ul><ul><li>PICH: to carry the paging indicators. </li></ul><ul><ul><li>A PICH is always associated with an S-CCPCH to which a PCH transport channel is mapped. </li></ul></ul>3GPP physical layer specification 25.211 Structure of Paging Indicator Channel (PICH)
    17. 17. Enhanced random access in CDMA2000 <ul><li>IS95 access mode: slotted ALOHA mode </li></ul><ul><li>New features in CDMA2000 reverse access: </li></ul><ul><ul><li>Faster capture feedback: an access header containing request ID and access type </li></ul></ul><ul><ul><li>Fast congestion and overload control:periodically broadcasting a fast access inhibit indicator bit (ISMA) </li></ul></ul><ul><ul><li>Support of variable-size/rate packets </li></ul></ul><ul><ul><li>Closed loop power control </li></ul></ul><ul><ul><li>Shortened access probe </li></ul></ul><ul><ul><li>Soft handoff capability </li></ul></ul><ul><ul><li>Discontinuous /gated-off preamble </li></ul></ul>“ Enhanced Random Access and Reservation Scheme in CDMA2000”, kamran etemad, IEEE Personal Communications. April 2001 3GPP2 C.S00002-A,”physical layer standard for cdma2000 spread spectrum systems”, Release A
    18. 18. Enhanced random access in CDMA2000 <ul><li>REACH: Basic Access mode </li></ul><ul><li>Involved channels: </li></ul><ul><ul><li>REACH: distinguished by its long codes </li></ul></ul><ul><ul><li>RCCCH: only be used based on a reservation mode </li></ul></ul><ul><ul><li>FCPCH(forward common power control channel) </li></ul></ul><ul><ul><li>FCACH(forward common channel assignment channel): to provide a fast feedback or response mechanism </li></ul></ul><ul><ul><li>FCCCH: </li></ul></ul>“ Enhanced Random Access and Reservation Scheme in CDMA2000”, kamran etemad, IEEE Personal Communications. April 2001
    19. 19. Enhanced random access in CDMA2000 <ul><li>REACH: Power control access mode </li></ul>“ Enhanced Random Access and Reservation Scheme in CDMA2000”, kamran etemad, IEEE Personal Communications. April 2001
    20. 20. Enhanced random access in CDMA2000 <ul><li>REACH: reservation access mode </li></ul>A reservation access probe followed by data transmission on RCCCH “ Enhanced Random Access and Reservation Scheme in CDMA2000”, kamran etemad, IEEE Personal Communications. April 2001
    21. 21. Enhanced random access in CDMA2000 <ul><li>Enhanced access procedures </li></ul>Monitors the Ec/Io RA mode for long data burst; BA or PCA mode for short signaling and MAC messages Check the busy/idle status or inhibit flag Randomly selects a ERACH “ Enhanced Random Access and Reservation Scheme in CDMA2000”, kamran etemad, IEEE Personal Communications. April 2001
    22. 22. Random access scheme in WCDMA <ul><li>Initial access scheme proposed in [*] </li></ul><ul><ul><li>In use of Orthogonal signatures ;preamble and data both transmitted in I&Q branches </li></ul></ul><ul><li>Access scheme proposed by ARIB[**] </li></ul><ul><ul><li>Data on I branch;preamble and pilot on Q branch </li></ul></ul><ul><li>Access scheme for UTRA </li></ul><ul><ul><li>Power ramping method </li></ul></ul><ul><ul><li>Guard period for frame alignment </li></ul></ul><ul><ul><li>Avoid the drawbacks of above schemes </li></ul></ul>[*] Esmailzadeh.R,Gustafsson,M. “A novel random access method for CDMA systems”,ICUPC’97,San Diego,CA,USA [**]ARIB,”specification of Air Interface for the 3G Mobile System”,ARIB report of IMT-2000 Radio Transmission Technology Special Group,Vol 3 Frank.G,Weber G,”random access scheme for the ETSI/UTRA WCDMA”,IEEE VTC99
    23. 23. Random access scheme in WCDMA <ul><li>RACH access: acknowledged by AICH </li></ul><ul><ul><li>Minimized buffer requirements; </li></ul></ul><ul><ul><li>Minimized processing delay; </li></ul></ul><ul><ul><li>Frame structure compatibility with dedicated physical channels </li></ul></ul>Frank.G,Weber G,”random access scheme for the ETSI/UTRA WCDMA”,IEEE VTC99 3GPP physical layer specification TS 25.11~214
    24. 24. Random access scheme in WCDMA <ul><li>CPCH access scheme: acknowledged by AP-AICH and CD/CA-ICH </li></ul><ul><ul><li>DSMA/CR(digital sense multiple access/collision resolution) </li></ul></ul>“ an overview of Common Packet Channel(CPCH), an opitmum wireless Internet Mechanism in 3GPP WCDMA system and comparison of various UMTS Non Real Time data deployment opitons”, Dr. Kourosh Parsa,
    25. 25. Random access scheme in WCDMA <ul><li>RACH---for fast access and short/medium packets </li></ul><ul><ul><li>High rate RACH---suited for packet transmissions of medium size </li></ul></ul><ul><ul><li>Low rate RACH--- only used for very short packet transmissions </li></ul></ul><ul><li>CPCH--- the most efficient approach to bursty packet access </li></ul><ul><ul><li>Do not need multiple control channels running to support the circuit operation </li></ul></ul><ul><ul><li>A factor of 4 and 26 higher spectrum efficiency in downlink and uplink as compared to use of dedicated channels. </li></ul></ul><ul><ul><li>Four –fold efficiency as compared to RACH </li></ul></ul>“ an overview of Common Packet Channel(CPCH), an opitmum wireless Internet Mechanism in 3GPP WCDMA system and comparison of various UMTS Non Real Time data deployment opitons”, Dr. Kourosh Parsa, “ Performance of a common channel packet access in WCDMA”,Farooq Khan, Christiaan Roobol and Johan Larsson, IEEE 1998
    26. 26. Thank you!

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