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A slide presentation of LTE fundamentals

A slide presentation of LTE fundamentals

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  • 1. UMTS Long Term Evolution LTE Reiner StuhlfauthReiner.Stuhlfauth@rohde- schwarz.com Training Centre Rohde & Schwarz, Germany Subject to change - Data without tolerance limits is not binding. R&S© is a registered trademark of Rohde & Schwarz GmbH & Co. KG. Trade names are trademarks of the owners. 2011 ROHDE & SCHWARZ GmbH & Co. KG Test & Measurement Division - Training Center - This folder may be taken outside ROHDE & SCHWARZ facilities. ROHDE & SCHWARZ GmbH reserves the copy right to all of any part of these course notes. Permission to produce, publish or copy sections or pages of these notes or to translate them must first be obtained in writing from ROHDE & SCHWARZ GmbH & Co. KG, Training Center, Mhldorfstr. 15, 81671 Munich, Germany
  • 2. Overview 3GPP UMTS Evolution Driven by Data Rate and Latency Requirements WCDMA HSDPA/HSUPA HSPA+ LTE 384 kbps downlink 14 Mbps peak downlink 28 Mbps peak downlink 100 Mbps peak downlink 128 kbps uplink 5.7 Mbps peak uplink 11 Mbps peak uplink 50 Mbps peak uplink RoundTripTime~150ms RoundTripTime<100ms RoundTripTime <50 ms RoundTripTime~10 ms 3GPP Release 99/4 3GPP Release 5/6 3GPP Release 7 7 3GPP Release 8 8 3GPP Release 99/4 3GPP Release 5/6 2003/4 2005/6 (HSDPA) 2008/9 2009/10 2007/8 (HSUPA) Approx. year of specification freezing November 2012 | LTE Introduction | 3
  • 3. Overview 3GPP UMTS evolution HSDPA/ LTE and LTE- WCDMA HSPA+WCDMA HSUPA HSPA+ advanced 3GPP 3GPP Study3GPP Release 99/4 3GPP Release 73GPP Release 5/6 3GPP Release 8release Item initiated App. year of 2005/6 (HSDPA) 2008/20092003/4 2010network rollout 2007/8 (HSUPA) Downlink LTE: 150 Mbps* (peak) 100 Mbps high mobility HSPA+: 42 Mbps (peak)384 kbps (typ.) 28 Mbps (peak)14 Mbps (peak)data rate 1 Gbps low mobility Uplink LTE: 75 Mbps (peak)128 kbps (typ.) 5.7 Mbps (peak) 11 Mbps (peak)data rate Round LTE: ~10 ms< 50 ms< 100 ms~ 150 msTrip Time *based on 2x2 MIMO and 20 MHz operation November 2012 | LTE Introduction | 4
  • 4. Overview TD-SCDMA evolution towards LTE TDD TD-LTE TD-SCDMA HSDPA HSUPA HSPA+ 3GPP release 3GPP Release 4 3GPP Release 5 3GPP Release 7 3GPP Release 8 Downlink 384/128 kbps (typ.) 2.8 Mbps (peak) 2.8 Mbps (peak)* LTE:100 Mbps(req.) data rate Uplink data rate 128 kbps (typ.) 128 kbps (typ.) 2.2 Mbs (peak)* LTE: 50 Mbps (req.) * Higher data rate with the use of multi carrier possible November 2012 | LTE Introduction | 5
  • 5. Why LTE? Ensuring Long Term Competitiveness of UMTS l LTE is the next UMTS evolution step after HSPA and HSPA+. l LTE is also referred to as EUTRA(N) = Evolved UMTS Terrestrial Radio Access (Network). l Main targets of LTE: l Peak data rates of 100 Mbps (downlink) and 50 Mbps (uplink) l Scalable bandwidths up to 20 MHz l Reduced latency l Cost efficiency l Operation in paired (FDD) and unpaired (TDD) spectrum November 2012 | LTE Introduction | 6
  • 6. Introduction to UMTS LTE: Key parameters Frequency UMTS FDD bands and UMTS TDD bands Range 1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHzChannel bandwidth, 6 15 25 50 75 1001 Resource Resource Resource Resource Resource Resource ResourceBlock=180 kHz Blocks Blocks Blocks Blocks Blocks Blocks Modulation Downlink: QPSK, 16QAM, 64QAM Schemes Uplink: QPSK, 16QAM, 64QAM (optional for handset) Downlink: OFDMA (Orthogonal Frequency Division Multiple Access) Multiple Access Uplink: SC-FDMA (Single Carrier Frequency Division Multiple Access) Downlink: Wide choice of MIMO configuration options for transmit diversity, spatial MIMO multiplexing, and cyclic delay diversity (max. 4 antennas at base station and handset) technology Uplink: Multi user collaborative MIMO Downlink: 150 Mbps (UE category 4, 2x2 MIMO, 20 MHz) Peak Data Rate 300 Mbps (UE category 5, 4x4 MIMO, 20 MHz) Uplink: 75 Mbps (20 MHz)
  • 7. LTE/LTE-A Frequency Bands (FDD) Uplink (UL) operating band Downlink (DL) operating bandE - UTRA BS receive UE transmit BS transmit UE receiveOperating Duplex Mode Band 1 1920 MHz - 1980 MHz 2110 MHz - 2170 MHz FDD 2 1850 MHz - 1910 MHz 1930 MHz - 1990 MHz FDD 3 1710 MHz - 1785 MHz 1805 MHz - 1880 MHz FDD 4 1710 MHz - 1755 MHz 2110 MHz - 2155 MHz FDD 5 824 MHz - 849 MHz 869 MHz - 894MHz FDD 6 830 MHz - 840 MHz 875 MHz - 885 MHz FDD 7 2500 MHz - 2570 MHz 2620 MHz - 2690 MHz FDD 8 880 MHz - 915 MHz 925 MHz - 960 MHz FDD 9 1749.9 MHz - 1784.9 MHz 1844.9 MHz - 1879.9 MHz FDD 10 1710 MHz - 1770 MHz 2110 MHz - 2170 MHz FDD 11 1427.9 MHz - 1452.9 MHz 1475.9 MHz - 1500.9 MHz FDD 12 698 MHz - 716 MHz 728 MHz - 746 MHz FDD 13 777 MHz - 787 MHz 746 MHz - 756 MHz FDD 14 788 MHz - 798 MHz 758 MHz - 768 MHz FDD 17 704 MHz - 716 MHz 734 MHz - 746 MHz FDD 18 815 MHz - 830 MHz 860 MHz - 875 MHz FDD 19 830 MHz - 845 MHz 875 MHz - 890 MHz FDD 20 832 MHz - 862 MHz 791 MHz - 821 MHz FDD 21 1447.9 MHz - 1462.9 MHz 1495.9 MHz - 1510.9 MHz FDD 22 3410 MHz - 3500 MHz 3510 MHz - 3600 MHz FDD November 2012 | LTE Introduction | 13
  • 8. LTE/LTE-A Frequency Bands (TDD) Uplink (UL) operating band Downlink (DL) operating band E - UTRA BS receive UE transmit BS transmit UE receive Operating Duplex Mode Band 33 1900 MHz - 1920 MHz 1900 MHz - 1920 MHz TDD 34 2010 MHz - 2025 MHz 2010 MHz - 2025 MHz TDD 35 1850 MHz - 1910 MHz 1850 MHz - 1910 MHz TDD 36 1930 MHz - 1990 MHz 1930 MHz - 1990 MHz TDD 37 1910 MHz - 1930 MHz 1910 MHz - 1930 MHz TDD 38 2570 MHz - 2620 MHz 2570 MHz - 2620 MHz TDD 39 1880 MHz - 1920 MHz 1880 MHz - 1920 MHz TDD 40 2300 MHz - 2400 MHz 2300 MHz - 2400 MHz TDD 3400 MHz - 3400 MHz - 41 TDD 3600MHz 3600MHz November 2012 | LTE Introduction | 14
  • 9. LTE frequency allocation - FDD = Uplink frequency = Downlink frequency November 2012 | LTE Introduction | 16
  • 10. Orthogonal Frequency Division Multiple Access the modulation scheme for LTE in downlink andOFDM is uplink (as reference) Some technical explanation about our physical base: radio link aspects November 2012 | LTE Introduction | 17
  • 11. What does it mean to use the radio channel? Using the radio channel means to deal with aspects like: C A D B ReceiverTransmitter MPP Time variant channel Doppler effect attenuationFrequency selectivity November 2012 | LTE Introduction | 18
  • 12. Types of degradation in cellular networks l Multiple Access Interference (MAI) l Inter cell interference l Intra cell interference l Adjacent channel interference l Co channel interference l Fading l Large scale fading - Known as log-normal fading or shadowing - Depends on distance between transmitter and receiver l Small scale fading - due to Multipath propagation and Doppler shift - Depends on signal bandwidth, relative velocity, environment November 2012 | LTE Introduction | 19
  • 13. What is OFDM? Single carrier transmission, e.g. WCDMA Broadband, e.g. 5MHz for WCDMA Orthogonal Frequency Division Multiplex Several 100 subcarriers, with x kHz spacing November 2012 | LTE Introduction | 27
  • 14. OFDM signal generation e.g. QPSK 00 11 01 10 01 01 11 01 > . h*(sin jwt + cos jwt ) h*(sin jwt + cos jwt ) => S h * (sin.. + cos > ) Frequency time OFDM symbol duration ? tNovember 2012 | LTE Introduction | 29
  • 15. OFDM Symbol OFDM symbol duration ? t November 2012 | LTE Introduction | 33
  • 16. Inter-Carrier-Interference (ICI) 10 Σ ΜΧ ( φ ) 0 -10 -20 -30 xx S -40 -50 -60 -70 -1 -0.5 0 0.5 1 f -1 f 0 f 1 ff -2 f 2 ICIProblem of MC - FDM Overlapp of neighbouring subcarriers Inter Carrier Interference (ICI). Solution "Special" transmit g s (t) and receive filter g r (t) and frequencies f k allows orthogonalsubcarrier Orthogonal Frequency Division Multiplex (OFDM) November 2012 | LTE Introduction | 34
  • 17. Rectangular Pulse A(f) Convolution sin(x)/x t f ? t ? f time frequency November 2012 | LTE Introduction | 35
  • 18. Orthogonality Orthogonality condition: ? f = 1/ ? t ? f November 2012 | LTE Introduction | 36
  • 19. ISI and ICI due to channel Symbol ll-1 l+1 L L η ( ν ) Receiver DFTn Window Delay spread L L L L L L fade out (ISI)fade in (ISI) November 2012 | LTE Introduction | 37
  • 20. ISI and ICI: Guard Interval Symbol ll-1 l+1 L L η ( ν ) T G > Delay Spread Receiver DFTn Window Delay spread L L L L L L Guard Interval guarantees the suppression of ISI! November 2012 | LTE Introduction | 38
  • 21. Guard Interval as Cyclic Prefix Cyclic Prefix Symbol ll-1 l+1 L L η ( ν ) T G > Delay Spread Receiver DFTn Window Delay spread L L L L L L Cyclic Prefix guarantees the suppression of ISI and ICI! November 2012 | LTE Introduction | 39
  • 22. Synchronisation Cyclic Prefix l + 1OFDM Symbol : l 1 l CP CPCP CP Metric -Search window ~n November 2012 | LTE Introduction | 40
  • 23. DL CP-OFDM signal generation chainl OFDM signal generation is based on Inverse Fast Fourier Transform (IFFT) operation on transmitter side: N UsefulData QAM OFDM Cyclic prefix1:N N:1symbol IFFT OFDMsource Modulator symbols insertionstreams symbols Frequency Domain Time Domain l On receiver side, an FFT operation will be used. November 2012 | LTE Introduction | 41
  • 24. OFDM: Pros and Cons Pros: scalable data rate efficient use of the available bandwidth robust against fading 1-tap equalization in frequency domain Cons: high crest factor or PAPR. Peak to average power ratio very sensitive to phase noise, frequency- and clock-offset guard intervals necessary (ISI, ICI) reduced data rate November 2012 | LTE Introduction | 42
  • 25. MIMO Multiple Input Multiple Output Antennas November 2012 | LTE Introduction | 43
  • 26. MIMO is defined by the number of Rx / Tx Antennasand not by the Mode which is supported Mode SISO Typical todays wireless Communication System1 1 Single Input Single Output Transmit Diversity MISO l Maximum Ratio Combining (MRC)1 1 l Matrix A also known as STC Multiple Input Single OutputM l Space Time / Frequency Coding (STC / SFC) Receive Diversity SIMO l Maximum Ratio Combining (MRC)1 1 Single Input Multiple Output Receive / Transmit Diversity M Spatial Multiplexing (SM) also known as: l Space Division Multiplex (SDM) l MIMO True MIMO 1 1 l Single User MIMO (SU-MIMO) l Matrix BMultiple Input Multiple OutputM M Space Division Multiple Access (SDMA) also known as: l Multi User MIMO (MU MIMO) l Virtual MIMO l Collaborative MIMODefinition is seen from Channel BeamformingMultiple In = Multiple Transmit Antennas November 2012 | LTE Introduction | 44
  • 27. MIMO modes in LTE -Spatial Multiplexing -Tx diversity -Multi-User MIMO -Beamforming -Rx diversity Increased Increased Throughput per Throughput at UEBetter S/N Node B November 2012 | LTE Introduction | 45
  • 28. RX Diversity Maximum Ratio Combining depends on different fading of the two received signals. In other words decorrelated fading channels November 2012 | LTE Introduction | 46
  • 29. TX Diversity: Space Time Coding Fading on the air interface data The same signal is transmitted at differnet antennas space Aim: increase of S/N ratio increase of throughput*s 1 s 2 Alamouti Coding = diversity gain Σ 2 = time approaches*s 2 s 1 RX diversity gain with MRRC! Alamouti Coding -> benefit for mobile communications November 2012 | LTE Introduction | 47
  • 30. MIMO Spatial Multiplexing C=B*T*ld(1+S/N) SISO: Single Input Single Output Higher capacity without additional spectrum! MIMO: S T B ld ( 1 + ) ? Χ = min( N T , N R ) i N ii = 1 Multiple Input i Multiple Output Increasing capacity per cell November 2012 | LTE Introduction | 48
  • 31. The MIMO promisel Channel capacity grows linearly with antennas Max Capacity ~ min(N TX , N RX ) l Assumptions l Perfect channel knowledge l Spatially uncorrelated fading l Reality l Imperfect channel knowledge l Correlation ? 0 and rather unknown November 2012 | LTE Introduction | 49
  • 32. Spatial Multiplexing Coding Fading on the air interface data data <200%200%100%Throughput: Spatial Multiplexing: We increase the throughput but we also increase the interference! November 2012 | LTE Introduction | 50
  • 33. Introduction - Channel Model II Correlation of propagation h 11 pathes h 21 s 1 r 1 h M R1 h 12 estimatess 2 h 22 r 2 Transmitter Receiverh M R2 h 1M h 2M T T N Tx N Rx h M sN Tx r NRx antennas RMT antennas s rH Rank indicator Capacity ~ min(N TX , N RX ) max. possible rank! But effective rank depends on channel, i.e. the correlation situation of H November 2012 | LTE Introduction | 51
  • 34. Spatial Multiplexing prerequisitesDecorrelation is achieved by: difficultl Decorrelated data content on each spatial stream l Large antenna spacing Channel condition l Environment with a lot of scatters near the antenna (e.g. MS or indoor operation, but not BS) Technical l Precoding assist But, also possible that decorrelation l Cyclic Delay Diversity is not given November 2012 | LTE Introduction | 52
  • 35. MIMO: channel interference + precoding MIMO channel models: different ways to combat against channel impact: I.: Receiver cancels impact of channel II.: Precoding by using codebook. Transmitter assists receiver in cancellation of channel impact III.: Precoding at transmitter side to cancel channel impact November 2012 | LTE Introduction | 53
  • 36. MIMO - work shift to transmitter Channel ReceiverTransmitter November 2012 | LTE Introduction | 57
  • 37. MIMO precodingprecoding Ant1 Ant2 t + 1 2 S1 t + 1 -11precoding S =0 tt November 2012 | LTE Introduction | 59
  • 38. MIMO - codebook based precodingPrecoding codebook noise s r+ RA H receivertransmitter channel Precoding Matrix Identifier, PMI Codebook based precoding creates some kind of "beamforming lite" November 2012 | LTE Introduction | 60
  • 39. MIMO: avoid inter-channel interference - future outlook e.g. linear precoding: Y=H*F*S+VV 1,k +S Link adaptation H Space timeTransmitter receiverF +x k y k V M,k Feedback about H Idea: F adapts transmitted signal to current channel conditions November 2012 | LTE Introduction | 61
  • 40. MAS: "Dirty Paper" Coding - future outlook l Multiple Antenna Signal Processing: "Known Interference" l Is like NO interference l Analogy to writing on "dirty paper" by changing ink color accordingly "Known"Known"Known"Known InterferenceInterferenceInterferenceInterference is Nois Nois Nois No Interference"Interference"Interference"Interference" November 2012 | LTE Introduction | 62
  • 41. Spatial Multiplexing Codeword Fading on the air interface data Codeword data Spatial Multiplexing: We like to distinguish the 2 useful Propagation passes: How to do that? => one idea is SVD November 2012 | LTE Introduction | 63
  • 42. Idea of Singular Value Decomposition MIMOs1 r1 know r= H s+n s2 r2 channel H Singular Value Decomposition ~ ~s1 r1 SISO wanted ~ ~s2 r2 ~ = D s + n~ ~ r channel D November 2012 | LTE Introduction | 64
  • 43. MIMO transmission modes Transmission mode 2 Transmit diversity PDCCH indication via DCI format 1 or 1A Codeword is sent redundantly over several streams 1 codeword PDSCH transmission via 2 Or 4 antenna ports No feedback regarding antenna selection or precoding needed November 2012 | LTE Introduction | 72
  • 44. MIMO transmission modes Closed loop MIMO = UE feedback needed regarding Transmission mode 6 precoding and antenna Transmit diversity or Closed loop selection spatial multiplexing with 1 layer PDCCH indication via DCI format 1A 1 codeword PDSCH transmission via 2 or 4 antenna ports PDCCH indication via DCI format 1B Codeword is split into 1 streams, both streams havecodeword to be combined feedback PDSCH spatial multiplexing, only 1 codeword November 2012 | LTE Introduction | 76
  • 45. Beamforming Closed loop precoded Adaptive Beamforming beamforming Classic way Kind of MISO with channel knowledge at transmitter Antenna weights to adjust beam Precoding based on feedback Directional characteristics No specific antenna Specific antenna array geometrie array geometrie Dedicated pilots required Common pilots are sufficient November 2012 | LTE Introduction | 78
  • 46. Spatial multiplexing vs beamforming Spatial multiplexing increases throughput, but looses coverage November 2012 | LTE Introduction | 79
  • 47. Spatial multiplexing vs beamforming Beamforming increases coverage November 2012 | LTE Introduction | 80
  • 48. System architectureevolution , SAE +IP multimediasubsystem , IMS November 2012 | LTE Introduction | 81
  • 49. 3 GPP System Architecture Evolution Signaling interfaces Data transport interfaces RAN Access PDN directly or via IMS MME PDNUE Evolved nodeB IMSS-GW P-GW PSTNEvolved Packet Core external IMS to control All interfaces are packet switched access + data transfer November 2012 | LTE Introduction | 82
  • 50. LTE: EPS Bearer E-UTRAN EPC Internet UE eNB S-GW P-GW Peer Entity End-to-end Service EPS Bearer External Bearer Radio Bearer S1 Bearer S5/S8 Bearer Radio S1 S5/S8 Gi November 2012 | LTE Introduction | 83
  • 51. What is IMS?A high level summary l The success of the internet, using the Internet Protocol (IP) for providing voice, data and media has been the catalyst for the convergence of industries, services, networks and business models, l IP provides a platform for network convergence enabling a service provider to offer seamless access to any services, How to merge IPanytime, anywhere, and with any device, and cellularl 3GPP has taken these developments into account world?? with specification of IMS, l IMS stands for I P M ultimedia S ubsystem, l IMS is a global access-independent and standard-based IP connectivity and service control architecture that enables various types of multimedia services to end-users using common internet-based protocols, l Defines an architecture for the convergence of audio, video, data and fixed and mobile networks. November 2012 | LTE Introduction | 84
  • 52. IMS: Reference Model (3GPP/3GPP2) November 2012 | LTE Introduction | 85
  • 53. IMS simplified structure November 2012 | LTE Introduction | 86
  • 54. IMS protocol structure user plane Control plane Voice messaging video SIP/SDP IKE RTP MSRP UDP / TCP / SCTP IP / IP secLayer 3 control Layer 1/2Layer 1/2 (other IP CAN) Mobile com specific protocols IMS specific protocols November 2012 | LTE Introduction | 87
  • 55. LTE physical layeraspect s November 2012 | LTE Introduction | 88
  • 56. Basic OFDM parameter LTE 1 φ = 15 κΗζ = T F s = N FFT f N FFT Φ σ = 3 . 84 Mcps 256 f = 2048N FFT Coded symbol rate= R Sub-carrier CP S/P IFFTMapping insertion N Data symbolsTX Size-N FFT November 2012 | LTE Introduction | 89
  • 57. Cyclic prefix lengthNormal cyclic prefix length: 1st CP is longer 1 2 3 4 5 6 7 1 slot = 0,5msecMismatch in time! 1st Cyclic prefix is longer 1 2 3 4 5 6 7 Normal CP OFDM OFDM OFDM OFDM OFDM OFDM Extended CPCP CP CP CP CP CPSymbol Symbol Symbol Symbol Symbol Symbol 2 different Cyclic prefix lengths are defined November 2012 | LTE Introduction | 90
  • 58. Resource block definition 1 slot = 0,5msec Resource block =6 or 7 symbols In 12 subcarriers 12 subc arrier s Resource element ULN symb or N symbDL 6 or 7, Depending on cyclic prefix November 2012 | LTE Introduction | 91
  • 59. LTE: new physical channels for data and control Physical Control Format Indicator Channel PCFICH: Indicates Format of PDCCH Physical Downlink Control Channel PDCCH: Downlink and uplink scheduling decisions Physical Downlink Shared Channel PDSCH: Downlink data Physical Hybrid ARQ Indicator Channel PHICH: ACK/NACK for uplink packets Physical Uplink Shared Channel PUSCH: Uplink data Physical Uplink Control Channel PUCCH: ACK/NACK for downlink packets, scheduling requests, channel quality info November 2012 | LTE Introduction | 92
  • 60. LTE Downlink OFDMA time-frequency multiplexing frequency QPSK, 16QAM or 64QAM modulation UE4 1 resource block = 180 kHz = 12 subcarriers UE5 UE3 UE2 UE6 Subcarrier spacing = 15 kHz time UE1 1 subframe = 1 slot = 0.5 ms = 1 ms= 1 TTI*=*TTI = transmission time interval 7 OFDM symbols** 1 resource block pair** For normal cyclic prefix duration November 2012 | LTE Introduction | 93
  • 61. Adaptive modulation and coding Transportation block size FECUser data Flexible ratio between data and FEC = adaptive coding November 2012 | LTE Introduction | 97
  • 62. Channel Coding Performance November 2012 | LTE Introduction | 98
  • 63. Automatic repeat request, latency aspects Transport block size = amount of data bits (excluding redundancy!) TTI, Transmit Time Interval = time duration for transmitting 1 transport block Transport block Round Trip Time ACK/NACK Network UE Immediate acknowledged or non-acknowledged feedback of data transmission November 2012 | LTE Introduction | 99
  • 64. HARQ principle: Stop and Wait ? t = Round trip time Data Data Data Data Data Data Data Data Data DataTx ACK/NACK Demodulate, decode, descramble, Rx FFT operation, check CRC, etc. process Processing time for receiver Described as 1 HARQ process November 2012 | LTE Introduction | 100
  • 65. HARQ principle: Multitasking ? t = Round trip time Data Data Data Data Data Data Data Data Data DataTx ACK/NACK Demodulate, decode, descramble, Rx FFT operation, check CRC, etc. process ACK/NACK Processing time for receiver Demodulate, decode, descramble,Rx FFT operation, check CRC, etc. process t Described as 1 HARQ process November 2012 | LTE Introduction | 101
  • 66. LTE Round Trip Time RTTn+4 n+4 n+4 ACK/N ACKPDCC H PHICH Downlink HARQData DataUL Uplink t=0 t=1 t=2 t=3 t=4 t=5 t=6 t=7 t=8 t=9 t=0 t=1 t=2 t=3 t=4 t=5 1 frame = 10 subframes 8 HARQ processes RTT = 8 msec November 2012 | LTE Introduction | 102
  • 67. HARQ principle: Soft combining l T i is a e am l o h n e co i g Reception of first transportation block. Unfortunately containing transmission errors November 2012 | LTE Introduction | 103
  • 68. HARQ principle: Soft combining l hi i n x m le f cha n l c ing Reception of retransmitted transportation block. Still containing transmission errors November 2012 | LTE Introduction | 104
  • 69. HARQ principle: Soft combining1st transmission with puncturing scheme P1 l T i is a e am l o h n e co i g 2nd transmission with puncturing scheme P2 l hi i n x m le f cha n l c ing Soft Combining = S of transmission 1 and 2 l Thi is an exam le of channel co ing Final decoding l This is an example of channel coding November 2012 | LTE Introduction | 105
  • 70. Hybrid ARQChase Combining = identical retransmission Turbo Encoder output (36 bits) Systematic Bits Parity 1 Parity 2 Transmitted Bit Rate Matching to 16 bits (Puncturing) Original Transmission Retransmission Systematic Bits Parity 1 Parity 2 Punctured Bit Chase Combining at receiver Systematic Bits Parity 1 Parity 2 November 2012 | LTE Introduction | 106
  • 71. Hybrid ARQIncremental Redundancy Turbo Encoder output (36 bits) Systematic Bits Parity 1 Parity 2 Rate Matching to 16 bits (Puncturing) Original Transmission Retransmission Systematic Bits Parity 1 Parity 2 Punctured Bit Incremental Redundancy Combining at receiver Systematic Bits Parity 1 Parity 2 November 2012 | LTE Introduction | 107
  • 72. LTE Physical Layer:SC-FDMA in uplink Single Carrier Frequency DivisionMultiple Access November 2012 | LTE Introduction | 108
  • 73. LTE Uplink:How to generate an SC-FDMA signal in theory? Coded symbol rate= R Sub-carrier CP DFT IFFTMapping insertion N TX symbols Size-N FFTSize-N TX LTE provides QPSK,16QAM, and 64QAM as uplink modulation schemes DFT is first applied to block of N TX modulated data symbols to transform them into frequency domain Sub-carrier mapping allows flexible allocation of signal to available sub-carriers IFFT and cyclic prefix (CP) insertion as in OFDM Each subcarrier carries a portion of superposed DFT spread data symbols Can also be seen as " pre-coded OFDM " or " DFT-spread OFDM " November 2012 | LTE Introduction | 109
  • 74. LTE Uplink:How does the SC-FDMA signal look like? In principle similar to OFDMA, BUT : In OFDMA, each sub-carrier only carries information related to one specific symbolIn SC-FDMA, each sub-carrier contains information of ALL transmitted symbols November 2012 | LTE Introduction | 110
  • 75. LTE uplinkSC-FDMA time-frequency multiplexing1 resource block = 180 kHz = 12 subcarriers Subcarrier spacing = 15 kHz frequency UE1 UE2 UE3 1 slot = 0.5 ms = 7 SC-FDMA symbols** 1 subframe = 1 ms= 1 TTI* UE4 UE5 UE6 *TTI = transmission time interval ** For normal cyclic prefix duration time QPSK, 16QAM or 64QAM modulation November 2012 | LTE Introduction | 111
  • 76. LTE Uplink:baseband signal generation UE specific Scrambling code Modulation Transform SC-FDMAResource Scrambling mapper precoder element mapper signal gen. Mapping on physical 1 stream = Discrete Ressource, several FourierAvoid QPSK i.e. subcarriers, Transformconstant 16 QAM subcarriers based on sequences 64 QAM not used for Physical (optional) reference ressource signals blocks November 2012 | LTE Introduction | 112
  • 77. LTE Physical Layer: Reference signals - general aspects Reference signals in Downlink Reference signals in Uplink November 2012 | LTE Introduction | 113
  • 78. LTE Reference signals in UL and DL overview l i nk U plown i nkD Downlink reference signals: Uplink reference signals: Primary synchronisation signal Random Access Preamble Secondary synchronisation signal Uplink demodulation reference signal Cell specific reference signals Sounding reference signal UE specific reference signals = based on pseudo random bit sequences = based on Zhadoff-Chu sequences MBMS specific reference signals = only used for special applications November 2012 | LTE Introduction | 114
  • 79. Downlink Reference Signals Cell-specific reference signal R 0 R 0 One antenna port R 0R 0 freque ncy R 0R 0 R 0 R 0 l = 0 l = 6 l = 0 l = 6 time Cell specific reference signals Pseudo random bit sequence, based on physical cell ID Staggered in frequency + time Distributed over channel bandwidth, always sent November 2012 | LTE Introduction | 115
  • 80. MIMO channel estimation due to reference signals Estimate h 11 h 11 Estimate h 21 h 12 h 21 Estimate h 22h 22 Estimate h 12 Antenna 1 Antenna 2 November 2012 | LTE Introduction | 116
  • 81. MIMO in LTE (DL)Reference Symbols / Pilots Antenna 0R0 R1 Antenna 1 R1 R3 R0 R1 R2 R0 R2 Antenna 2 R3 Antenna 3 R0 R2 R1 R0 R3 R1 12 subcar riers Different Tx antennas R1 R3 R0 R1 R2 R0 Can be recognized separately R0 R2 R1 R0 R3 R1 1 subframe November 2012 | LTE Introduction | 117
  • 82. Cell recognition due to physical cell identityCell specific reference signals depend on N cell ID ceenreferCell ficspe pec i cific s eNodeB 2Cell refer enc e Physical Cell eNodeB 1, identity B Physical Cell Neighbour cells should have different identity A physical layer cell identities to be distinguished November 2012 | LTE Introduction | 118
  • 83. LTE Uplink:Reference Signals 2 different purposes: 1. Uplink channel estimation for uplink coherent demodulation/detection (reference symbol on 4th SC-FDMA symbol) 2. Channel sounding: uplink channel-quality estimation for better scheduling decisions (position tbd) November 2012 | LTE Introduction | 119
  • 84. LTE Uplink: Reference Signals when PUSCH time0123456 0123456 0123456 0123456 Allocated bandwidth Example structure SRS bandwidth configurationfrequency Allocation for PUSCH Demodulation Reference Signal: Uplink channel estimation for uplink coherent demodulation/detection Sounding Reference Signal SRS: Channel sounding: uplink channel-quality estimation for better scheduling decisions November 2012 | LTE Introduction | 120
  • 85. Sounding reference signalFrequency selective channel allcoated bandwidth eNodeB configures the UE when and where to send sounding reference signals Sounding reference signals in uplink may assist the eNodeB to investigate frequency selectivity => Maybe change frequency scheduling November 2012 | LTE Introduction | 121
  • 86. Security aspects power control random access Handover aspects November 2012 | LTE Introduction | 122
  • 87. LTE security aspects: USIMModell of UMTS Subscriber Identity Module, USIM Statements from TS 33.401: A Rel-99 or later USIM shall be sufficient for accessing E-UTRAN Access to E-UTRAN with a 2G SIM shall not be granted. November 2012 | LTE Introduction | 123
  • 88. LTE fundamentals Downlink power allocation (1 RB) For PDSCH power in samePDSCH power to RS, where NO referenceCell-specific PDCCH power symbol as reference signal ansignals are present, is UE specific andreference signal depending additional cell specific offsetsignaled by higher layers as P A ( ? A ).power (RS power), on ? B / ? A is applied, that is signaled bysignaled in SIB Type 2 higher layers as P B ( ? B ). [Power] -50.00 dBm P A = -4.77 dB 2011 ¸ Rohde&S chwarz y]-54.77 dBm cen quP B = 3 (-3.98 dB) re [F-58.75 dBm rrie ar bc Su [Time]1311 127 9 103 5 6 81 2 40 OFDM symbols PDSCH - Physical Downlink Shared Channel PDCCH - Physical Downlink Control Channel November 2012 | LTE Introduction | 126
  • 89. RACH Preamble (RAP) l RACH Preamble consists of - CAZAC (Zadoff / Chu Sequence) in TDD/FDD -> orthogonality - Cyclic Prefix Easy processing in frequency domain - Guard Time Avoids Interference by no UL-Synchronization l Different formats for different cell sizes: 0-3 (FDD: 1,2,3 Subframes), 4 (TDD: 1 Symbol) November 2012 | LTE Introduction | 132
  • 90. LTE Protocol Architecture November 2012 | LTE Introduction | 133
  • 91. EUTRAN stack: protocol layers overviewMM ESM User plane Radio Resource Control RRC Packet Data Convergence PDCP Contr ol & Meas urem ents Radio Bearer Radio Link Control RLC Logical channels Medium Access Control MAC Transport channels PHYSICAL LAYER November 2012 | LTE Introduction | 134
  • 92. LTE - channels November 2012 | LTE Introduction | 135
  • 93. Control plane Broadcast Paging RRC connection setup Radio Bearer Control Mobility functions UE measurement control > EPS bearer management Authentication ECM_IDLE mobility handling Paging origination in ECM_IDLE Security control > EPS = Evolved packet system RRC = Radio Resource Control NAS = Non Access Stratum ECM = EPS Connection Management November 2012 | LTE Introduction | 136
  • 94. EPS Bearer Service Architecture E-UTRAN EPC Internet UE eNB S-GW P-GW Peer Entity End-to-end Service EPS Bearer External Bearer Radio Bearer S1 Bearer S5/S8 Bearer Radio S1 S5/S8 Gi November 2012 | LTE Introduction | 137
  • 95. LTE TDD and FDD mode ofoperation November 2012 | LTE Introduction | 138
  • 96. TDD versus FDD Downlink Guard band needed Uplink Independent resources in uplink + downlink Down- and Uplink No duplexerTiming and UL/DL neededconfiguration needed November 2012 | LTE Introduction | 139
  • 97. Paired spectrum not always available -> use TDD mode November 2012 | LTE Introduction | 140
  • 98. General comments What is called "Advantages of TDD vs. FDD mode" l Data traffic, l Asymmetric setting between downlink and uplink possible, depending on the situation, See interference aspects: UL - DL and inter-cell l Channel estimation, l Channel characteristic for downlink and uplink same, In principle yes: But hardware influence! And: Timing delay UL and DL l Design, l No duplexer required, simplifies RF design and reduce costs. But most UEs will be dual- mode: FDD and TDD! November 2012 | LTE Introduction | 141
  • 99. LTE TDD mode - overview 7 different UL/DL configurations are defined Characteristics + differences of UL/DL configurations: Number of subframes dedicated to Tx and Rx Number of Hybrid Automatic Repeat Request, HARQ processes HARQ process timing: time between first transmission and retransmission Scheduling timing: What is the time between PDCCH and PUSCH? 9 different configurations for the "special subframe" are defined Definition of how long are the DL and UL pilot signals and how much control information can be sent on it. -> also has an impact on cell size Differences between Uplink and Downlink in TD-LTE Characteristic of HARQ: Synchronuous or asynchronuous Number of Hybrid Automatic Repeat Request, HARQ processes HARQ process timing: time between first transmission and retransmission November 2012 | LTE Introduction | 143
  • 100. LTE TDD: frame structure type 2 Used Always Always Optionally Alwaysfor UL used as DL UL DLor DL special subframe Subframe# 0 Subframe# 2 Subframe # 3 Subframe#4 Subframe #5 Subframe #7 Subframe #8 Subframe #9 One subframe, DwPTS GP UpPTSDwPTS GP UpPTS DwPTS = PDCCH, P-Sync, Reference symbol, User Data GP = main Guard Period for TDD operation UpPTS = PRACH, sounding reference signal November 2012 | LTE Introduction | 144
  • 101. LTE Rel9 / LTE-Rel 10 (= LTE- Advanced) Technology Outlook Reiner StuhlfauthReiner.Stuhlfauth@rohde- schwarz.com Training Centre Rohde & Schwarz, Germany
  • 102. Technology evolution path 2005/2006 2009/2010 2011/20122007/2008 2013/2014 EDGE, 200 kHz EDGEevo VAMOSGSM/ DL: 473 kbps DL: 1.9 Mbps Double Speech GPRS UL: 473 kbps UL: 947 kbps Capacity HSDPA, 5 MHzUMTS HSPA+, R7 HSPA+, R8 HSPA+, R9 HSPA+, R10 DL: 14.4 MbpsDL: 2.0 Mbps DL: 28.0 Mbps DL: 42.0 Mbps DL: 84 Mbps DL: 84 Mbps UL: 2.0 MbpsUL: 2.0 Mbps UL: 11.5 Mbps UL: 11.5 Mbps UL: 23 Mbps UL: 23 Mbps HSPA, 5 MHz DL: 14.4 Mbps UL: 5.76 Mbps LTE (4x4), R8+R9, 20MHz LTE-Advanced R10 DL: 300 Mbps DL: 1 Gbps (low mobility) UL: 75 Mbps UL: 500 Mbps 1xEV-DO, Rev. 0 1xEV-DO, Rev. A 1xEV-DO, Rev. B DO-Advancedcdma 1.25 MHz 1.25 MHz 5.0 MHz DL: 32 Mbps and beyond 2000 DL: 2.4 Mbps DL: 3.1 Mbps DL: 14.7 Mbps UL: 12.4 Mbps and beyond UL: 153 kbps UL: 1.8 Mbps UL: 4.9 Mbps Fixed WiMAX Mobile WiMAX, 802.16e Advanced Mobile scalable bandwidth Up to 20 MHz WiMAX, 802.16m 1.25 > 28 MHz DL: 75 Mbps (2x2) DL: up to 1 Gbps (low mobility) typical up to 15 Mbps UL: 28 Mbps (1x2) UL: up to 100 Mbps November 2012 | LTE Introduction | 157
  • 103. The LTE evolution Rel-9 eICIC enhancements Relaying Rel-10In-device Diverse Data co-existence Application CoMP Rel-11 Relaying eICIC eMBMS SONenhancements enhancements MIMO 8x8 MIMO 4x4Carrier Enhanced Aggregation SC-FDMA Public Warning Positioning Home eNodeBSystem Self Organizing NetworkseMBMS ULDL Multi carrier / DL ULDual Layer Multi-RAT Beamforming Base Stations LTE Release 8 FDD / TDD November 2012 | LTE Introduction | 159
  • 104. Location based services The idea is not new, > so what to discuss? Satellite based services Location controller Network based services Who will do the measurements? The UE or the network? = "assisted" Who will do the calculation? The UE or the network? = "based" So what is new? Several ideas are defined and hybrid mode is possible as well, Various methods can be combined. November 2012 | LTE Introduction | 169
  • 105. Measurements for positioning l lUE-assisted measurements. eNB-assisted measurements. l lReference Signal Received eNB Rx - Tx time difference. Power l TADV - Timing Advance. (RSRP) and Reference Signal - For positioning Type 1 is of Received Quality (RSRQ). relevance. l RSTD - Reference Signal Time l AoA - Angle of Arrival. Difference. l UTDOA - Uplink Time Difference l UE Rx-Tx time difference. of Arrival. TADV (Timing Advance) = eNB Rx-Tx time difference + UE Rx-Tx time difference Neighbor cell j = (T eNB-RX - T eNB-TX ) + (T UE-RX - T UE-TX ) UL radio frame #i RSTD - Relative time difference between a subframe received from neighbor cell j and corresponding subframe from serving cell i: T SubframeRxj - T SubframeRxi DL radio frame #i UL radio frame #i DL radio frame #i Serving cell i eNB Rx-Tx time difference is defined UE Rx-Tx time difference is defined as T eNB-RX - T eNB-TX , where T eNB-RX is the RSRP, RSRQ are as T UE-RX - T UE-TX , where T UE-RX is the received timing of uplink radio frame #imeasured on reference received timing of downlink radio frame and T eNB-TX the transmit timing ofsignals of serving cell i #i from the serving cell i and T UE-TX the downlink radio frame #i. transmit timing of uplink radio frame #i. Source: see TS 36.214 Physical Layer measurements for detailed definitions November 2012 | LTE Introduction | 170
  • 106. E-UTRAN UE Positioning Architecture l In contrast to GERAN and UTRAN, the E-UTRAN positioning capabilities are intended to be forward compatible to other access types (e.g. WLAN) and other positioning methods (e.g. RAT uplink measurements). l Supports user plane solutions, e.g. OMA SUPL 2.0 UE = User Equipment SUPL* = Secure User Plane Location OMA* = Open Mobile Alliance SET = SUPL enabled terminal SLP = SUPL locaiton platform E-SMLC = Evolved Serving Mobile Location Center MME = Mobility Management Entity RAT = Radio Access Technology *www.openmobilealliance.org/technical/release_program/supl_v2_0.aspx Source: 3GPP TS 36.305November 2012 | LTE Introduction | 171
  • 107. GNSS positioning methods supported l Autonomeous GNSS l Assisted GNSS (A-GNSS) l The network assists the UE GNSS receiver to improve the performance in several aspects: - Reduce UE GNSS start-up and acquisition times - Increase UE GNSS sensitivity - Allow UE to consume less handset power l UE Assisted - UE transmits GNSS measurement results to E-SMLC where the position calculation takes place l UE Based - UE performs GNSS measurements and position calculation, suppported by data > - > assisting the measurements, e.g. with reference time, visible satellite list etc. - > providing means for position calculation, e.g. reference position, satellite ephemeris, etc. Source: 3GPP TS 36.305November 2012 | LTE Introduction | 172
  • 108. GPS and GLONASS satellite orbits GPS: 26 Satellites Orbital radius 26560 km GLONASS: 26 Satellites Orbital radius 25510 km November 2012 | LTE Introduction | 173
  • 109. Why is GNSS not sufficent? Critical scenario Very critical scenario GPS Satellites visibility (Urban) l Global navigation satellite systems (GNSSs) have restricted performance in certain environments l Often less than four satellites visible: critical situation for GNSS positioning support required (Assisted GNSS) alternative required (Mobile radio positioning) Reference [DLR] November 2012 | LTE Introduction | 174
  • 110. Cell ID l Not new, other definition: Cell of Origin (COO). l UE position is estimated with the knowledge of the geographical coordinates of its serving eNB. l Position accuracy = One whole cell . November 2012 | LTE Introduction | 175
  • 111. Enhanced-Cell ID (E- CID) l UE positioning compared to CID is specified more accurately using additional UE and/or E UTRAN radio measurements: l E-CID with distance from serving eNB position accuracy: a circle. - Distance calculated by measuring RSRP / TOA / TADV (RTT). l E-CID with distances from 3 eNB-s position accuracy: a point. - Distance calculated by measuring RSRP / TOA / TADV (RTT). l E-CID with Angels of Arrival position accuracy: a point. - AOA are measured for at least 2, better 3 eNB's. RSRP - Reference Signal Received Power TOA - Time of Arrival November 2012 | LTE Introduction | 176TADV - Timing Advance RTT - Round Trip Time
  • 112. Angle of Arrival (AOA) l AoA = Estimated angle of a UE with respect to a reference direction (= geographical North), positive in a counter- clockwise direction, as seen from an eNB. l Determined at eNB antenna based on a received UL signal (SRS). l Measurement at eNB: l eNB uses antenna array to estimate direction i.e. Angle of Arrival (AOA). l The larger the array, the more accurate is the estimated AOA. l eNB reports AOA to LS. l Advantage: No synchronization between eNB's. l Drawback: costly antenna arrays. November 2012 | LTE Introduction | 177
  • 113. OTDOA - Observed Time Difference of Arrival l UE position is estimated based on measuring TDOA of Positioning Reference Signals (PRS) embedded into overall DL signal received from different eNB's. l Each TDOA measurement describes a hyperbola (line of constant difference 2a), the two focus points of which (F1, F2) are the two measured eNB-s (PRS sources), and along which the UE may be located. l UE's position = intersection of hyperbolas for at least 3 pairs of eNB's. November 2012 | LTE Introduction | 178
  • 114. Positioning Reference Signals (PRS) for OTDOA Definition l Cell-specific reference signals (CRS) are not sufficient for positioning, introduction of positioning reference signals (PRS) for antenna port 6. l SINR for synchronization and reference signals of neighboring cells needs to be at least -6 dB. l PRS is a pseudo-random QPSK sequence similar to CRS; PRS pattern: l Diagonal pattern with time varying frequency shift. l PRS mapped around CRS to avoid collisions; never overlaps with PDCCH; example shows CRS mapping for usage of 4 antenna ports. November 2012 | LTE Introduction | 179
  • 115. Observed Time difference Observed Time Difference of Arrival OTDOA If network is synchronised, UE can measure time difference November 2012 | LTE Introduction | 180
  • 116. Public Warning System (PWS) l Extend the Warning System support of the E-UTRA/E-UTRAN beyond that introduced in the Release 8 ETWS (Earthquake and Tsunami Warning System) by providing l E-UTRA/E-UTRAN support for multiple parallel Warning Notifications l E-UTRAN support for replacing and canceling a Warning Notification l E-UTRAN support for repeating the Warning Notification with a repetition period as short as 2 seconds and as long as 24 hours l E-UTRA support for more generic "PWS" indication in the Paging Indication l The requirement is to extend the UE RRC ETWS broadcast reception mechanism and the associated paging mechanism to accommodate reception of CMAS (Commercial Mobile Alert System) alerts contained in a CBS message. l New: TS 22.268 Public Warning System (PWS) Requirements (Release 9) November 2012 | LTE Introduction | 182
  • 117. IMT - International Mobile Communication l IMT-2000 l Was the framework for the third Generation mobile communication systems, i.e. 3GPP-UMTS and 3GPP2-C2K l Focus was on high performance transmission schemes: Link Level Efficiency l Originally created to harmonize 3G mobile systems and to increase opportunities for worldwide interoperability, the IMT-2000 family of standards now supports four different access technologies, including OFDMA (WiMAX), FDMA, TDMA and CDMA (WCDMA). l IMT-Advanced l Basis of (really) broadband mobile communication l Focus on System Level Efficiency (e.g. cognitive network systems) l Vision 2010 - 2015 November 2012 | LTE Introduction | 183
  • 118. IMT Spectrum MHz MHz Next possible spectrum allocation at WRC 2015! MHz MHz November 2012 | LTE Introduction | 184
  • 119. LTE-Advanced Possible technology features Relaying Wider bandwidth technology support CooperativeEnhanced MIMO base stationsschemes for DL and UL Interference management Cognitive radio methods methods Radio network evolution Further enhanced MBMS November 2012 | LTE Introduction | 185
  • 120. Bandwidth extension with Carrier aggregation November 2012 | LTE Introduction | 186
  • 121. LTE-Advanced Carrier Aggregation Contiguous carrier aggregation Non-contiguous carrier aggregation November 2012 | LTE Introduction | 187
  • 122. Aggregation l Contiguous l Intra-Band l Non-Contiguous l Intra (Single) -Band l Inter (Multi) -Band l Combination l Up to 5 Rel-8 CC and 100 MHz l Theoretically all CC-BW combinations possible (e.g. 5+10+20 etc) November 2012 | LTE Introduction | 188
  • 123. Overview l Carrier Aggregation (CA) enables to aggregate up to 5 different cells (component carriers CC), so that a maximum system bandwidth of 100 MHz can be supported (LTE-Advanced requirement). l Each CC = Rel-8 autonomous cell Cell 2Cell 1 - Backwards compatibility l CC-Set is UE specific - Registration Primary (P)CC UE1 UE4 UE3 U3 UE4 U2 - Additional BW Secondary (S)CC-s 1-4 l CC2 Network perspective CC1 - Same single RLC-connection for one UE (independent on the CC-s) UE1 UE2 CC2 CC1 - Many CC (starting at MAC scheduler) UE3 operating the UE l For TDD - Same UL/DL configuration for all CC-s UE4 November 2012 | LTE Introduction | 189
  • 124. Deployment scenarios 3) Improve coverage l #1: Contiguous frequency aggregation - Co-located & Same coverage - Same f l #2: Discontiguous frequency aggregation - Co-located & Similar coverage - Different f l #3: Discontiguous frequency aggregation - Co-Located & Different coverage - Different f - Antenna direction for CC2 to cover blank spots l #4: Remote radio heads - Not co-located - Intelligence in central eNB, radio heads = only transmission antennas - Cover spots with more traffic - Is the transmission of each radio head within the cell the same? l #5:Frequency-selective repeaters - Combination #2 & #4 - Different f - Extend the coverage of the 2nd CC with Relays November 2012 | LTE Introduction | 190
  • 125. Physical channel arrangement in downlink Each component carrier transmits P- Each component SCH and S-SCH, carrier transmits Like Rel.8 PBCH, Like Rel.8 November 2012 | LTE Introduction | 191
  • 126. Carrier aggregation: control signals + scheduling Each CC has its own control channels, like Rel.8 Femto cells: Risk of interference! -> main component carrier will send all control information. November 2012 | LTE Introduction | 193
  • 127. LTE-Advanced Carrier Aggregation - Scheduling Non-Contiguous spectrum allocationContiguous l There is one transport block RLC transmission buffer (in absence of spatial Dynamic multiplexing) and one HARQ switching entity per scheduled component carrier (from the Channel Channel Channel Channel coding coding coding coding UE perspective), l A UE may receive multiple HARQ HARQ HARQ HARQ component carriers simultaneously, Data Data Data Data mod. mod. mod. mod. l Two different approaches are discussed how to inform the Mapping Mapping Mapping Mapping UE about the scheduling for each band, e.g. 20 MHz l Separate PDCCH for each carrier, l Common PDCCH for multiple carrier, [frequency in MHz] November 2012 | LTE Introduction | 194
  • 128. LTE- AdvancedCarrier Aggregation - Common and Separate PDCCH? l Based on RAN WG1#58 the following isup to 3 (4) symbols 1 subframe = 1 msper subframe considered being supported for LTE-Time 1 slot = 0.5 ms Advanced,Freque ncy l Variant I PDCCH on a component carrier PDCCHPDCCH PDCCH PDCCH assigns PDSCH resources on the same PDSCH PDSCH PDSCH PDSCH component carrier (and PUSCH resources on a single linked UL component carrier) - No carrier indicator field, i.e. Rel-8 PDCCH structure (same coding, same CCE-basedPDSCH PDSCH PDSCH PDSCH resource mapping) and DCI formatsPDCCHPDCCH PDCCH PDCCH l Variant II PDCCH on a component carrier can assign PDSCH or PUSCH resources in one of multiple component carriers using the carrier indicator field PDSCH PDSCH PDSCH PDSCH - Rel-8 DCI formats extended with 1 to 3 bit carrierPDCCHPDCCH PDCCH PDCCH indicator field - Reusing Rel-8 PDCCH structure (same coding, same CCE-based resource mapping) - Solutions to PCFICH detection errors on the component Variant (I) Variant (II) Variant (III) PDSCH to be studied Variant (IV)carrier carrying l In both cases, limiting the number of blind decoding is desirable, November 2012 | LTE Introduction | 195
  • 129. Carrier aggregation activation 1. Establish SRB 3. Network Activates PCC =UL + DL 2. UE sends Capability information to the network 4.Network Add secondary CC November 2012 | LTE Introduction | 196
  • 130. Carrier aggregation activation - mobility 1. UE has EUTRAN connection active 2. Secondary CC is added 3. Secondary CC is removed 4. UE and network perform Handover on primary CC 3. Secondary CC is Added in target cell November 2012 | LTE Introduction | 197
  • 131. DL MIMO Extension up to 8x8 Codeword to layer mapping for spatial multiplexing l Max number of transport blocks: 2 Number Number Codeword-to-layer mapping of code l Number of MCS fields of layers i = 0 , 1 , K M symb layer 1words l one for each transport block x ( 0 ) ( i ) = d ( 0 ) ( 2 i ) l ACK/NACK feedback x ( 1 ) ( i ) = d ( 0 ) ( 2 i + 1 ) l 1 bit per transport block for evaluation M symb = M symb 2 = M symb 3layer ( 0 ) ( 1 ) 5 2 as a baseline x ( i ) = d ( 3 i )( 2 ) ( 1 ) x ( 3 ) ( i ) = d ( 1 ) ( 3 i + 1 ) l x ( 4 ) ( i ) = d ( 1 ) ( 3 i + 2 )Closed-loop precoding supported l Rely on precoded dedicated x ( 0 ) ( i ) = d ( 0 ) ( 3 i )x ( 1 ) ( i ) = d ( 0 ) ( 3 i + 1 )demodulation RS (decision on DL RS) x ( 2 ) ( i ) = d ( 0 ) ( 3 i + 2 ) l M symb = M symb 3 = M symb 3layer ( 0 ) ( 1 ) Conclusion on the codeword-to- 6 2 x ( i ) = d ( 3 i )( 3 ) ( 1 ) layer mapping: x ( 4 ) ( i ) = d ( 1 ) ( 3 i + 1 )x ( 5 ) ( i ) = d ( 1 ) ( 3 i + 2 )l DL spatial multiplexing of up to eight x ( 0 ) ( i ) = d ( 0 ) ( 3 i )layers is considered for LTE-Advanced, x ( 1 ) ( i ) = d ( 0 ) ( 3 i + 1 )l x ( 2 ) ( i ) = d ( 0 ) ( 3 i + 2 )Up to 4 layers, reuse LTE codeword-to- M symb = M symb 3 = M symb 4layer ( 0 ) ( 1 ) 7 2 layer mapping, x ( 3 ) ( i ) = d ( 1 ) ( 4 i ) x ( 4 ) ( i ) = d ( 1 ) ( 4 i + 1 ) l Above 4 layers mapping - see table x ( 5 ) ( i ) = d ( 1 ) ( 4 i + 2 ) x ( 6 ) ( i ) = d ( 1 ) ( 4 i + 3 ) l Discussion on control signaling x ( 0 ) ( i ) = d ( 0 ) ( 4 i ) details ongoing x ( 1 ) ( i ) = d ( 0 ) ( 4 i + 1 ) x ( 2 ) ( i ) = d ( 0 ) ( 4 i + 2 ) x ( 3 ) ( i ) = d ( 0 ) ( 4 i + 3 ) M symb = M symb 4 = M symb 4layer ( 0 ) ( 1 ) 8 2 x ( 4 ) ( i ) = d ( 1 ) ( 4 i ) x ( 5 ) ( i ) = d ( 1 ) ( 4 i + 1 ) x ( 6 ) ( i ) = d ( 1 ) ( 4 i + 2 ) x ( 7 ) ( i ) = d ( 1 ) ( 4 i + 3 ) November 2012 | LTE Introduction | 198
  • 132. LTE- AdvancedEnhanced uplink SC- FDMA l The uplink transmission scheme remains SC-FDMA. l The transmission of the physical uplink shared channel (PUSCH) uses DFT precoding. l Two enhancements: l Control-data decoupling l Non-contiguous data transmission November 2012 | LTE Introduction | 199
  • 133. Significant step towards 4G: Relaying ? Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008 November 2012 | LTE Introduction | 200
  • 134. Radio Relaying approach No Improvement of SNR resp. CINR Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008 November 2012 | LTE Introduction | 201
  • 135. L1/L2 Relaying approach Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008 November 2012 | LTE Introduction | 202
  • 136. LTE-Advanced Coordinated Multipoint Tx/Rx (CoMP) CoMP Coordination between cells November 2012 | LTE Introduction | 203
  • 137. Present Thrust- Spectrum Efficiency Momentary snapshot of frequency spectrum allocation Why not use this part of the spectrum? l FCC Measurements:- Temporal and geographical variations in the utilization of the assigned spectrum range from 15% to 85%. November 2012 | LTE Introduction | 204
  • 138. ODMA - some ideas. BTS Mobile devices behave as relay station November 2012 | LTE Introduction | 205
  • 139. There will be enough topics for future trainings Thank you for your attention! Comments and questions welcome! November 2012 | LTE Introduction | 208

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