LTE technology introduction

Transcription

1 LTE technoogy introduction

2 My business card ROHDE & SCHWARZ Taiwan Ltd. 14F,No.13,Sec. 2,Pei-Tou Road, Taipei, 112,Taiwan, R.O.C. Lance Yang ( 楊 聯 甫 ) Appication Engineer Appication & System Support Phone: Ext.321 Fax: emai: [email protected] Internet: Hot Line: LTE technoogy introduction p 2

3 Contents Overview UMTS evoution and 3GPP standardization LTE radio transmission schemes OFDM OFDMA / SC-FDMA Physica channes Downink/upink LTE MIMO MIMO Fading R&S LTE portfoio R&S Test Soutions LTE technoogy introduction p 3

4 UMTS / WCDMA today UMTS = Universa Mobie Teecommunications System WCDMA = Wideband Code Division Mutipe Access 140 WCDMA networks aunched commerciay wordwide* 120 miion WCDMA subscribers wordwide as of Mar 2006* Services: video teephony, video streaming, mobie TV, mobie e-mai, Chaenges: Continuousy improved end-user experience Improved speed, service attractiveness, service interaction Long-term 3G competitiveness *Source: LTE technoogy introduction p 4

5 Today's technoogy evoution path 2003/ / / / /2012 GSM/ GPRS EDGE, 200 khz DL: 473 kbps UL: 473 kbps E-EDGE, 200 khz DL: 1.9 Mbps UL: 947 kbps UMTS HSDPA, 5 MHz DL: 14.4 Mbps UL: 2.0 Mbps HSPA, 5 MHz DL: 14.4 Mbps UL: 5.76 Mbps HSPA+, Re. 7 DL: 21.0 Mbps UL: 11.5 Mbps HSPA+, Re. 8 DL: 42.0 Mbps UL: 11.5 Mbps LTE (2x2), Re. 8, 20 MHz DL: 173 Mbps UL: 58 Mbps LTE (4x4), 20 MHz DL: 326 Mbps UL: 86 Mbps cdma xEV-DO, Rev MHz DL: 2.4 Mbps UL: 153 kbps 1xEV-DO, Rev. A 1.25 MHz DL: 3.1 Mbps UL: 1.8 Mbps 1xEV-DO, Rev. B 5.0 MHz DL: 14.7 Mbps UL: 4.9 Mbps 1xEV-DO, Rev. C (= UMB 2x2) 20 MHz DL: 140 Mbps UL: 34 Mbps 1xEV-DO, Rev. D (= UMB 4x4) 20 MHz DL: 280 Mbps UL: 68 Mbps IEEE a/b/g IEEE n Mobie WiMAX scaabe bandwidth MHz up to 15 Mbps Mobie WiMAX, e 10 MHz DL: 64 Mbps (2x2) UL: 28 Mbps (1x2) Mobie WiMAX, m 20 MHz DL: >130 Mbps (4x4) UL: 56 Mbps (2x4) LTE technoogy introduction p 5

6 UMTS/HSPA voice and data traffic Data approximatey 4x-over-year-growth of data traffic How the data traffic wi deveop in Voice the next years? Source: Peter Rysavy, 3G Americas LTE technoogy introduction p 6

7 Data traffic growth forecast Hypothesis Today's (air interface and) core network might not be abe to hande the forecasted data traffic!? Source: Peter Rysavy, 3G Americas LTE technoogy introduction p 7

8 Why LTE? Further demand for higher data rates (peak and average) and a significant decrease of atency, How this can be achieved? Re-use of features ike CQI, adaptive moduation and coding, HARQ, Using higher bandwidths, but fexibe and scaabe, ony possibe by using another transmission scheme, Further atency reduction with simper and fatter network architecture, Cost efficiency Affordabe ro-out costs (CAPEX 1) ), ow maintenance cost (OPEX 2) ), Wordwide network operator commitments for LTE, 1) CAPita Expenditures 2) OPerationa EXpenditure LTE technoogy introduction p 8

9 Ambitious targets with LTE Significanty increased peak data rate, e.g. 100 Mbps (downink) and 50 Mbps (upink), Significanty improved spectrum efficiency, e.g. 2-4 times compared to 3GPP Reease 6, Improved atency, Radio access network atency (user pane Network UE) beow 30 ms, Significanty reduced contro pane atency, e.g. ide to active <100 ms, Scaeabe bandwidth, 5, 10, 15, 20 MHz, Smaer bandwidths to aow fexibiity in narrow spectra aocations, Support for inter-working with existing 3G systems and non-3gpp specified systems, Reduced CAPEX 1) and OPEX 2) incuding backhau, Cost effective migration from reease 6 UTRA radio interface and architecture, Efficient support of the various types of services, especiay from the PS domain System shoud be optimized for ow mobie speed but aso support high mobie speed Operation in paired and unpaired spectrum shoud not be precuded (FDD and TDD modes) Enhanced Mutimedia Broadcast Muticast Services (E-MBMS) 1) CAPita Expenditures 2) OPerationa EXpenditure LTE technoogy introduction p 9

10 Don t get confused LTE = EUTRA(N) = Super3G = 3.9G EUTRA(N) = Evoved UMTS Terrestria Radio Access (Network) Used within 3GPP for LTE technoogy / network, ike UTRA FDD and UTRA TDD is used within 3GPP for 3G/UMTS Super3G Is referring to LTE, ike WCDMA is referring to UTRA FDD and TDD 3.9G Used to indicate that LTE is not 4G, since the requirements for 4G are set by ITU / IMT-advanced, where 3GPP wi approach these requirements with LTE-Advanced LTE technoogy introduction p 10

11 LTE Key Parameter Frequency Range Channe bandwidth 1 Resource Bock (RB) =180 khz Moduation Schemes Mutipe Access MIMO technoogy Peak Data Rate UMTS FDD bands and UMTS TDD bands 1.4 MHz 6RB Downink Upink Downink Upink Downink Upink Downink Upink 3 MHz 15 RB QPSK, 16QAM, 64QAM QPSK, 16QAM, 64QAM ( optiona for handset) OFDMA (Orthogona Frequency Division Mutipe Access) SC-FDMA (Singe Carrier Frequency Division Mutipe Access) Wide choice of MIMO configuration options for transmit diversity, spatia mutipexing, and cycic deay diversity (max. 4 antennas at base station and handset) Muti-user coaborative MIMO 150 Mbps (UE category 4, 2x2 MIMO, 20 MHz) 300 Mbps (UE category 5, 4x4 MIMO, 20 MHz) 75 Mbps (20 MHz) 5 MHz 25 RB 10 MHz 50 RB 15 MHz 75 RB 20 MHz 100 RB LTE technoogy introduction p 11

12 LTE UE categories (downink and upink) UE category Maximum number of DL-SCH transport bock bits received within TTI Maximum number of bits of a DL-SCH transport bock received a TTI Tota number of soft channe bits Maximum number of supported ayers for spatia mutipexing in DL ~300 Mbps peak DL data rate for 4x4 MIMO MIMO = Mutipe Input Mutipe Output UL-SCH = Upink Shared Channe DL-SCH = Downink Shared Channe UE = User Equipment TTI = Transmission Time Interva ~150 Mbps peak DL data rate for 2x2 MIMO UE category Maximum number of UL-SCH transport bock bits received within TTI ~75 Mbps peak UL data rate Support 64QAM in UL No No No No Yes LTE technoogy introduction p 12

13 Spectrum fexibiity LTE physica ayer /FDD/TDD) supports any bandwidth from 1.4 to 20 MHz, Current LTE specification supports a subset of 6 different system bandwidths, A UE s must support the maximum bandwidth of 20 MHz, Channe bandwidth BW Channe [MHz] Number of resource bocks Channe Bandwidth [MHz] Transmission Bandwidth Configuration [RB] Channe edge Resource bock Transmission Bandwidth [RB] Channe edge Active Resource Bocks DC carrier (downink ony) LTE technoogy introduction p 13

14 Depoyment scenarios for LTE LTE wi use same frequency bands as 3G, Current 3G frequency bocks, icensed by operators in various countries provide not enough bandwidth, for exampe in Europe/USA, or a continuous frequency range, for exampe USA, to ro-out LTE and use the fu capacity, New frequency ranges wi be used to use fu capacity of LTE, Asia/Europe 1) 2.5 to 2.7 GHz, USA 2) 700 MHz Band, Inter-working between WCDMA/HSPA, CDMA2000 1xRTT/1xEV-DO and GSM/EDGE is considered and currenty specified, 1) Auction in Norway, Sweden happened, Austria, Hong Kong, Netherands Q1/2009, Germany, UK probaby Q2/2009, Spain, Portuga probaby Q4/2009, Itay, France probaby Q1/2010 2) auction happened, spectrum avaiabe in February GHz antennas used for fied tria test on LTE in Nuremberg, GERMANY LTE technoogy introduction p 14

15 What is OFDM basicay? Orthogona Frequency Division Mutipex (OFDM) is a muticarrier transmission technique, which divides the avaiabe spectrum into many subcarriers, each one being moduated by a ow data rate stream, Singe Carrier Transmission (e.g. WCDMA) 5 MHz (Orthogona ) Frequency Division Mutipexing ((O)FDM) Typicay severa 100 sub-carriers with spacing of x khz e.g. 5 MHz LTE technoogy introduction p 15

16 OFDM Summary Advantages and disadvantages High spectra efficiency due to efficient use of avaiabe bandwidth, Scaabe bandwidths and data rates, Robust against narrow-band cochanne interference, Intersymbo Interference (ISI) and fading caused by mutipath propagation, Can easiy adapt to severe channe conditions without compex equaization 1-tap equaization in frequency domain, Low sensitivity to time synchronization errors, Very sensitive to frequency synchronization, Phase noise, frequency and cock offset, Sensitive to Dopper shift, Guard interva required to minimize effects of ISI and ICI, High peak-to-average power ratio (PAPR), due to the independent phases of the sub-carriers mean that they wi often combine constructivey, High-resoution DAC and ADC required, Requiring inear transmitter circuitry, which suffers from poor power efficiency, Any non-inearity wi cause intermoduation distortion raising phase noise, causing Inter- Carrier Interference (ICI) and out-of-band spurious radiation. LTE technoogy introduction p 16

17 LTE Physica Layer Concepts OFDMA in the Downink LTE technoogy introduction p 17

18 Difference between OFDM and OFDMA OFDM aocates user just in time domain, OFDMA aocates user in time and frequency domain, Frequency domain User 1 User 2 Frequency domain User 1 User 3 User 2 User 3 Time domain Time domain LTE technoogy introduction p 18

19 Downink physica channes and signas LTE Downink Physica Signas Primary and Secondary Synchronization Signa Downink Reference Signa Provide acquisition of ce timing and identity during ce search Ce search, initia acquisition, coherent demod., channe estimation LTE Downink Physica Channes Physica Broadcast Channe (PBCH) Physica Contro Format Indicator Channe (PCFICH) Physica Downink Contro Channe (PDCCH) Physica Downink Shared Channe (PDSCH) Physica Hybrid ARQ Indicator Channe (PHICH) Physica Muticast Channe (PMCH) Provides essentia system information e.g. system bandwidth Indicates format of PDCCH (CFI) Carries contro information (DCI = Downink Contro Information) Carries data (user data, system information, ) Carries ACK/NACK (HI = HARQ indicator) for upink data packets Carries MBMS user data LTE technoogy introduction p 19

20 Downink reference signas Each antenna has a specific reference signa pattern, e.g. for 2 antennas, Frequency domain spacing is 6 subcarrier, Time domain spacing is 4 OFDM symbos 4 reference signas per resource bock, Resource Bock LTE technoogy introduction p 20

21 How to derive information in LTE? Check the PDCCH for an unique IDENTITY 1). As soon as you have found it, you wi get a the information you need there. Physica Downink Contro Channe (PDCCH)?! Physica Downink Shared Channe (PDSCH) I woud ike to read the PDSCH but I don t know which resources are aocated for the transport of system or paging information or data and how they ook ike? 1) Severa identities are used in LTE to identify UE s (e.g. C-RNTI), System Information (SI-RNTI), Paging Information (P-RNTI) or during Random Access Procedure (RA-RNTI), for detais see 3GPP TS MAC Protoco Specification LTE technoogy introduction p 21

22 Indicating PDCCH format Check PCFICH! It wi te you how many symbos (1, 2, 3 (or 4)) in the beginning of each subframe are aocated for PDCCH! Physica Contro Format Indicator Channe (PCFICH)?! Physica Downink Contro Channe (PDCCH) I woud ike to read the PDCCH but where is it? LTE technoogy introduction p 22

23 Resource Aocation T sot Smaest resource unit is Resource Eement, which is 1 symbo on 1 subcarrier, But minimum aocation for transmission is a Resource Bock (RB), 1 RB spans 12 sub-carriers (12*15 khz = 180 khz) in the frequency domain and 1 Time Sot (= 0.5 ms) in the time domain, 10 MHz= 50 RB 50 RB*180 khz = 9.0 MHz + 1 unused DC subcarrier (= f Carrier ) = MHz TTI is 1 subframe, which is 2 time sots, With norma (extended) cycic prefix (CP) we got 7 (6) OFDM symbos per time sot, RB sc DL N RB N RB N sc DL N symb DL RB k = N N DL symb RB sc N N 1 RB sc ( k, ) Configuration OFDM Symbos Subcarrier Cycic Prefix Length in Sampes Cycic Prefix Length in µs Norma CP f = 15 khz Extended CP f = 15 khz Extended CP f = 7.5 khz for 1 st symbo 144 for other symbos 512 3MBMS 24 Scenario for 1 st symbo 4.7 for other symbos DL = 0 = N symb 1 k = 0 LTE technoogy introduction p 23

24 1 radio frame = 10 ms #0 #1 #19 1 sot = 0.5 ms 1 subframe = 1 ms LTE frame structure type 1 (FDD), downink User data aocations L1/2 downink contro channes Screenshot of R&S SMU200A signa generator Downink reference signa LTE technoogy introduction p 24

25 1 radio frame = 10 ms One radio frame T f =10 ms #0 #1 #19 1 sot = 0.5 ms LTE frame structure type 2 (TDD) 1 subframe = 1 ms Specia subframes containing: DwPTS: downink piot time sot UpPTS: upink piot time sot GP: guard period for TDD operation Possibe upink-downink configurations (D=Downink, U=Upink, S=Specia Subframe): DSUUU D S U U Screenshot of R&S SMU200A signa generator LTE technoogy introduction p 25

26 LTE Physica Layer Concepts SC-FDMA in the Upink LTE technoogy introduction p 26

27 How to generate a SC-FDMA? DFT pre-coding is performed on moduated data symbos to transform them into frequency domain, Sub-carrier mapping aows fexibe aocation of signa to avaiabe subcarriers, IFFT and cycic prefix (CP) insertion as in OFDM, Time Domain Frequency Domain Time Domain coded symbo rate R N TX symbos N-point DFT Subcarrier Mapping. M-point IDFT... Parae/Seria CP Insertion Each subcarrier carries a portion of superposed DFT spread data symbos, therefore SC-FDMA is aso referred to as DFT-spread-OFDM (DFT-s-OFDM). LTE technoogy introduction p 27

28 How does a SC-FDMA signa ook ike? Simiar to OFDM signa, but in OFDMA, each sub-carrier ony carries information reated to one specific symbo, in SC-FDMA, each sub-carrier contains information of ALL transmitted symbos. LTE technoogy introduction p 28

29 SC-FDMA parameterization (FDD and TDD) LTE FDD Same as in downink, TD-LTE Configurati on Norma CP f = 15 khz Extended CP f = 15 khz Number SC- FDMA Symbos 7 6 Number of Subcarrie r 12 Cycic Prefix Length in Sampes 160 for 1 st symbo 144 for other symbos Usage of UL depends on the seected UL-DL configuration (1 to 8), each configuration offers a different number of subframes (1ms) for upink transmission, Parameterization for those subframes, means number of SC-FDMA symbos same as for FDD and depending on CP, 512 Cycic Prefix Length in µs 5.2 for 1 st symbo 4.7 for other symbos 16.7 LTE technoogy introduction p 29

30 Upink physica channes and signas LTE Upink Physica Channes Physica Upink Shared Channe (PUSCH) Physica Upink Contro Channe (PUCCH) Physica Random Access Channe (PRACH) Carries user data Carries contro information (UCI = Upink Contro Information) Preambe transmission for initia access LTE Upink Physica Signas Demoduation Reference Signa (DRS) Sounding Reference Signa (SRS) Enabes channe estimation and data demoduation Enabes upink channe quaity evauation LTE technoogy introduction p 30

31 Scheduing of upink data Check PDCCH for your UE ID. As soon as you are addressed, you wi find your upink scheduing grants there. Physica Downink Contro Channe (PDCCH) Physica Upink Shared Channe (PUSCH) (QPSK, 16QAM moduated, 64QAM is optiona for the UE)?! I woud ike to send data on PUSCH but I don t know which resource bocks and transport formats I can use? LTE technoogy introduction p 31

32 Demoduation Reference Signa (DRS) in the UL DRS are used for channe estimation in the enodeb receiver in order to demoduate data (PUSCH) and contro (PUCCH) channes, PUSCH. Located in the 4 th SC-FDMA symbo in each sot (symbo #3, #10 for norma CP), spanning the same BW as aocated for user data, PUCCH. Different symbos, depending on format (see one of the foowing sides), Demoduation Reference Signa (DRS) Screenshot of R&S SMU200A Vector Signa Generator LTE technoogy introduction p 32

33 Sounding Reference Signa (SRS) in the UL SRS are used to estimate upink channe quaity in other frequency areas as a basis for scheduing decisions, Transmitted in areas, where no user data is transmitted, first or ast symbo of subframe is used for transmission, Configuration (e.g. BW, power offset, cycic shift, duration, periodicity, hopping pattern) is signaed by higher ayers, Screenshot of R&S SMU200A Vector Signa Generator LTE technoogy introduction p 33

34 LTE MIMO LTE technoogy introduction p 34

35 MIMO? SISO Singe Input Singe Output MISO Mutipe Input Singe Output MIMO Mutipe Input Mutipe Output MIMO = Mutipe Input Mutipe Output Refers to the use of mutipe antennas at transmitter and/or receiver side Requirement of 100 Mbps peak downink data rate => MIMO urgenty needed in LTE LTE technoogy introduction p 35

36 Topics reated to MIMO in LTE Cassica configuration with 2 Tx and 2Rx antennas Scenarios with 4 Tx antennas are aso supported Modes of operation of mutipe transmit antennas: Spatia mutipexing (inear codebook-based precoding) Beamforming Singe stream transmit diversity Singe User - MIMO and Mutipe User - MIMO systems are supported Mutipe codeword (MCW) transmission is agreed for the SU-MIMO LTE technoogy introduction p 36

37 MIMO in LTE Requirement of 100 Mbps peak downink data rate => MIMO urgenty needed in LTE Configuration with 2 Tx and 2 Rx antennas Scenarios with 4 Tx antennas aso supported Modes of operation of mutipe transmit antennas: Open or cosed oop spatia mutipexing Singe stream transmit diversity Beamforming Singe User - MIMO and Mutipe User - MIMO systems are supported LTE technoogy introduction p 37

38 MIMO modes T 1 T 2 T Nt s 1 s 12 ss Mt 1 R 1 Antenna array R Nr Transmit diversity (TxD) Combat fading Repicas of the same signa sent on severa Tx antennas Get a higher SNR at the Rx Spatia mutipexing (SM) Different data streams sent simutaneousy on different antennas Higher data rate No diversity gain Limitation due to path correation Beamforming LTE technoogy introduction p 38

39 Increasing data rate with spatia mutipexing origina 010 h TX ij RX N t antennas at node B N t N r antennas at UE MIMO channe mode Η = h h M h Nr1 h h h Nr2 K O K h h h 1Nt 2Nt M NrNt N r hij = channe coefficients in time domain from Tx antenna j to Rx antenna i LTE technoogy introduction p 39

40 Downink spatia mutipexing - precoding The signa is pre-coded at Node B side before transmission Optimum precoding matrix is seected from predefined codebook known at Node B and UE side UE estimates the channe, seects the best precoding matrix at the moment and sends back its index LTE technoogy introduction p 40

41 SU-MIMO versus MU-MIMO s1 s2 sn UE1 UE2 UEn SU (Singe User)-MIMO Goa: to increase user data rate Simutaneous transmission of different data streams to 1 user Efficient when the user experiences good channe conditions MU (Mutipe User)-MIMO Goa: to increase sector capacity Seection of the users experiencing good channe conditions Efficient when a arge number of users have an active data transmission simutaneousy LTE technoogy introduction p 41

42 Beamforming Smart antennas are divided into two groups: - Phased array systems (switched beamforming) with a finite number of fixed predefined patterns - Adaptive array systems (AAS) (adaptive beamforming) with an infinite number of patterns adjusted to the scenario in reatime LTE technoogy introduction p 42

43 MIMO in Radio Communications Systems LTE technoogy introduction p 43

44 MIMO and Fading MIMO precoding When testing MIMO receivers two major aspects need to be taken into account, the MIMO precoding and the channe simuation. LTE technoogy introduction p 44

45 C Fading sources A F D Transmitter E B Ampitude A: free space B: refection (object is arge compared to waveength) C: diffraction D: scattering (object is sma or its surface irreguar) E: shadowing (birth death) F: dopper Deay Spread Time Deay LTE technoogy introduction p 45

46 MIMO receiver verification with R&S SMU200A TX1 Code word and precoding seection for MIMO TX2 MIMO Fading (R&S SMU-K74) Screenshot of R&S SMU200A LTE technoogy introduction p 46

47 Signa Generation & MIMO Precoding Supported Features in SMU/SMJ/SMATE/SMBV/AMU/AFQ Feature Signa generation (Piots + Data) TX Diversity coding (DL) Spatia Mutipexing (DL) Coaborative / Virtua / Muti User MIMO (UL) mobie WiMAX IEEE e-2005 Option -K49/-K249 Antenna 1 or 2 2 Tx, STC, Matrix A 2 Tx, Matrix B Yes, supported LTE (3GPP Reease 8) Option -K55/-K255 Antenna 1, 2, 3 or 4 2 or 4 Tx SFC 2 or 4 Tx, Code Book (219 aternatives) Yes, supported LTE with MIMO precoding avaiabe LTE technoogy introduction p 47

48 Downink MIMO receiver verification Configuring MIMO mode and precoding MIMO data precoding per aocation Screenshot of R&S SMU200A LTE technoogy introduction p 48

49 LTE MIMO channe mode supported Particuary reevant for receiver performance tests Extension to traditiona ITU fading modes (tapped deay ine) required to cover higher bandwidths of LTE and MIMO operation Propagation conditions agreed in 3GPP for: Extended pedestrian A (EPA) Extended vehicuar A mode (EVA) Extended Typica Urban mode (ETU) Definition of deay profie, Dopper spectrum and set of correation matrices describing correation between UE and BS antennas LTE technoogy introduction p 49

50 Unique LTE/MIMO signa generation soution R&S SMU200A Vector signa generator LTE signa generation Dua channe baseband + RF Fading + AWGN simuator option 2x2 MIMO option K74 R&S AMU200A Baseband signa generator LTE signa generation Stand-aone baseband fading + AWGN simuator Dua channe baseband in/out 2x2 MIMO option K74 dua channe RF dua channe I/Q LTE technoogy introduction p 50

51 Measurement Rea-time MIMO fading up to 4 x 2 and 2 x 4 4 x 2 MIMO up to 3 GHz two SMU200A Each of the four basebands represent one transmit antenna. The two receive antennas are represented by combining the first RF outputs of both SMU200A and the second RF outputs of both SMU200A by RF combiners respectivey. By doing so, a eight possibe fading channes of a 4 x 2 MIMO setup can be simuated. Minimum instrument configuration: Both SMU200A need the same options as described above for the 2 x 2 MIMO case. LTE technoogy introduction p 51

52 LTE MIMO anaysis (Software Option FSQ-K102) Supports 2x2 and 4x4 MiMO Supports Transmitt Diversity Spacia mutipexing Cycic deay diversity Measurements are possibe on singe antennas or combined LTE technoogy introduction p 52

53 LTE MIMO anaysis MIMO transmitter tests on mutipe antennas DUT Precoded MIMO Signa LTE technoogy introduction p 53

54 LTE RF Testing Aspects UE/BS requirements according to 3GPP Transmitter Characteristics: Transmit power Frequency error Output power dynamics Output RF spectrum emissions Transmit intermoduation Moduation quaity, Error Vector Magnitude Receiver characteristics: Reference sensitivity eve UE maximum input eve Adjacent channe seectivity Bocking characteristics Intermoduation characteristics Spurious emissions Performance requirements Currenty captured in TR : User Equipment (UE) radio transmission and reception TR : Base Station (BS) radio transmission and reception LTE technoogy introduction p 54

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57 Further information on Technoogies: LTE technoogy introduction p 57