3G CDMA - WCDMA and Cdma2000
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3G CDMA - WCDMA and cdma2000 Rodger E. Ziemer IEEE Communications Society Distinguished Lecturer Program Outline v Multiple access/channel measurement guidelines v Current 1G and 2G technology v What is Third Generation? v WCDMA features v cdma2000 features v WCDMA and cdma2000 contrasted v Summary May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 2 Rules for Efficient Multiple Access v Three immutable laws v Know the channel v Minimize interference to others v Mitigate interference received from others v Requirements of wireless multiple access v Channel measurement v Channel control and modification v Multiple user channel isolation May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 3 Channel Measurement Guidelines v Wider the bandwidth = better the measurement v Limitations on this rule v Regulatory (indoor path isolation = 10 ns delay resolution) v Complexity (combining more paths = more hardware) v Physical limitations (splitting energy over more paths = increasingly inaccurate parameter measurements) v Measure at frequency > rate of change of channel v No other users: good receiver attempts to put together all received multipath components coherently v Other users present: Optimum = multiuser detection; suboptimum = power control; minimize near-far problem May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 4 Current 1G and 2G Technology System Jun-00 PDC Analog 78,339,980 8% cdmaOne 67,964,980 GSM 337,794,500 GSM IS-136 PDC 47,739,500 58% 8% IS-136 48,079,830 Africa USA/Canada 2% Americas 17% Analog 9% 14% Middle East 1% Asia Pacific cdmaOne 32% 12% Europe: Western Europe: Source: EMC World Cellular Database 36% Eastern 3% May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 5 Why CDMA? v Higher capacity v Improved performance in multipath by diversity v Lower mobile transmit power = longer battery life v Power control v Variable transmission rate with voice activity detection v Allows soft handoff v Sectorization gain v High peak data rates can be accommodated v Combats other-user interference = lower reuse factors May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 6 IS-95 Forward Link Xmtr Diagram [5] 8600 bps 9600 bps 19200 sps data scrambling 19200 sps voice error detection R=1/2; k = 9 user m code (CRC) block analog voice encoder convolutional interleaver & tail bits encoder + mux 172 bits + 12 bit CRC 384 sym cl ,m per 20 msec 8 bit tail per 20 msec user m long code wm reverse user m link power Walsh code control bit 1.2288 Mcps data scrambling 19200 sps error detection voice R=1/2; k = 9 block user n code (CRC) analog voice encoder convolutional interleaver & tail bits encoder + mux + user n long code cl ,n reverse user n pulse link power Walsh code shaping control bit 1.2288 Mcps cI , pilot cosw ot 1.2288 Mcps LPA 19200 sps S S data cQ, pilot sinw ot paging scrambling paging channel data R=1/2; k = 9 channel block pulse 9600/4800/ convolutional framing interleaver + + shaping 2400 bps encoder paging c wp channel l, page paging channel long code Walsh code 1.2288 Mcps 4800 sps sync synchronization R=1/2; k = 9 block channel channel data convolutional interleaver 1200 bps framing encoder + w32 synch channel Walsh code 1.2288 Mcps pilot channel data all 0's + w0 pilot channel Walsh code 1.2288 Mcps May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 7 What is Third Generation? [1] v Flexible support of multiple services v Voice v Messaging – email, fax, etc. v Medium-rate multimedia – Internet access, educational v High-rate multimedia – file transfer, video v High-rate interactive multimedia – video telecon-ferencing, telemedicine, etc. v Mobility: quasi-stationary to high-speed platforms v Global roaming: ubiquitous, seamless coverage v Evolution from second generation systems May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 8 Evolution of Standards [1] world GSM GPRS EDGE Japan PDC W-CDMA HSPDA U.S. iDEN U.S. IS-136 U.S./Asia IS-95A IS-95B cdma2000 1xEV-DV 2G 2.5G 3G 1xEV-DO May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 9 Peak Data Rates [1] 2072.0 2000 1500 1000 kbps 614.2 473.0 500 171.0 115.2 0 GPRS IS-95B WCDMA cdma2000 EDGE May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 10 3G Spectrum Availability [2] 3G 3G ITU MSS* MSS * Region 2 MSS* MSS 1885 1930 1980 2010 2025 2110 2120 2170 2200 PHS 3G 3G Japan MSS MSS 1885 1895 1918.1 1980 2010 2025 2110 2170 2200 DCS DCS DECT 3G 3G Europe 1800 1800 MSS MSS 1710 1785 1805 1880 1900 1996 2010 2025 2110 2186 2200 3G 3G China MSS MSS 1885 2025 2110 2200 Broadcast PCS Unl. PCS Reserve PCS Auxiliary USA A D B E F C A D B E F C 1850 1910 1930 1990 2110 2150 2200 All Frequencies in MHz May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 11 Main Differences between WCDMA and GSM Air Interfaces [3] WCDMA GSM Carrier spacing 5 MHz 200 kHz Reuse factor 1 1-18 Power control freq 1500 Hz 2 Hz or lower Quality control Radio resource Network planning management algorithms (frequency planning) Frequency diversity Wideband with RAKE Frequency hopping Packet data Load based packet Time slot base scheduling scheduling with GPRS Downlink diversity Supported Not supported May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 12 Main Differences between WCDMA and IS-95 Air Interfaces [3] WCDMA IS-95 Carrier spacing 5 MHz 1.25 MHz Chip rate 3.84 Mcps 1.2288 Mcps Power control freq 1500 up- & downlink 800 Hz uplink; slow, DL Base station synchronization Not needed Yes, typically via GPS Inter-frequency handovers Yes, measurements with Possible; measurement slotted mode method not specified Radio resource management Yes, provides QoS Not needed (speech only) Packet data Load-based packet Packet data xmitted as scheduling short circuit switched cells Downlink transmit diversity Supported Not supported May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 13 WCDMA Transmission Parameters v Wideband direct-sequence spreading v 3.84 Mcps chip rate v Spreading gains (ratios) from 4 to 512 v Complex QPSK spreading v Both frequency- and time-division duplex modes v Both forward and reverse fast power control v Coherent forward and reverse links using both code-division and time-division pilots v Asynchronous cells May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 14 New Features of cdma2000 vs. IS-95 v Forward link [4] v Quadrature PSK data modulation (doubles avail. Walsh codes) v Transmit diversity v Fast power control v Quasi-orthogonal codes (more codes) v Auxiliary pilots (beam forming) v New common power control and assignment channels v Increased standby time (changes in paging channel) v Turbo codes v Variable rate v Flexible frame length (5, 20, 40, and 80 ms) v Multiframe interleaving May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 15 New Features of cdma2000 vs. IS-95 v Reverse Link [4] v Coherent pilot channel assisted v Binary PSK data modulation v Complex PN spreading v Enhanced access channel = decreased setup times for traffic channeless connections (allows power control and slot reservations) v Improvements to interfrequency hard handoff to support subframe searches May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 16 W-CDMA Versus cdma2000 [2] W-CDMA IS-2000 Chip Rate 4.096 Mcps 3.6864 Mcps Frame Duration 10 ms 20 ms Base Stn Sync Asynchronous Synchronous 3 step paral code srch for Sync through time- Base Stn Acq/Det base stn det & slot/frame shifted PN correlation Forward Link Pilot TDM dedicated pilot CDM common pilot Antenna Beam Form TDM dedicated pilot Auxiliary pilot May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 17 Technologies Considered in Arriving at Third Generation v Wideband Direct-Sequence Code Division Multiple Access (CDMA) v Wideband Time Division Multiple Access (TDMA) v Wideband C/TDMA v Orthogonal Frequency Division Multiplexing (OFDM) v Opportunity Driven Multiple Access (ODMA) May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 18 WCDMA Uplink Frame Structure [1] k I: data channel Ndata = 10 * 2 bits (k = 0,K ,6) DPDCH Tslot = 2560 chips Q: sync & control Pilot: N pilot bits TFCI FBI TPC DPCCH 0.667 ms slot 0 slot 1 slot i slot 14 radio frame = 10 ms TFCI = transmit format combination indicator DPDCH = dedicated physical data channel FBI = feedback information DPCCH = dedicated physical control channel TPC = transmit power control May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 19 WCDMA Uplink Modulator Structure [1] DPDCH1 + pulse shape cd ,1 S b d filter (SRC) I - DPDCH S 3 cos(w t ) c c d ,3 b d + S + DPDCH2 c d ,2 b d Q DPCCH S + pulse shape c S filter (SRC) c b c + sin( wct ) clong,1 clong,2 May 28-June1, 2001 R. Z. Ziemer, Colorado Springs, CO 20 Orthogonal Variable Spreading Factor Codes selected from this tree cdi, Notes: 00000000 1) For fixed chip rate, desired information 0000 rate determines length of spreading 00001111 00 sequence and therefore processing gain. 00110011 2) When a specific code is used, no other 0011 code on the path from that code to the root 00111100 and or on the subtree beneath that 0 code may be used. 01010101 3) All the codes at any depth into the tree 0101 01011010 are the set of Walsh Sequences. 01 4) Code phase is synchronous with 01100110 information symbols. 0110 5) FDD UL processing gain between 256 and 4 01101001 FDD DL processing gain between 512 and 4 TDD UL/DL processing gain between 16 and 1 6) Multicode used only for SF = 4 May 28-June1, 2001 R.