LTE Phy Engineering - additional slides
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LTE Phy Engineering - additional slides

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Here are some additional materials from LTE Phy Engineering course delivered in August 2013 in Umeå, Sweden. ...

Here are some additional materials from LTE Phy Engineering course delivered in August 2013 in Umeå, Sweden.

If you are interested in attending top in class LTE/LTE-Advanced courses, please have a look http://is-wirelesstraining.com/course-map-2 or contact us directly: sales@is-wirelesstraining.com.

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LTE Phy Engineering - additional slides LTE Phy Engineering - additional slides Presentation Transcript

  • Technical content provided by IS-Wireless, www.is-wireless.com OFDM Processing Chain (From Bits to Carrier Frequency) 101010011101….. Modulator QPSK/16QAM/64QAM S/P IFFT P/S CP D/A Upconverter (Local Oscillator) X1 X2 X3 X4 … XN X1 X2 X3 X4 … XN x1 x2 x3 x4 … xN xN … x4 x3 x2 x1 t I Q xN … x4 x3 x2 x1 xN xN-1 t t t fc t f0MHz BW ffc BW 0MHz
  • Technical content provided by IS-Wireless, www.is-wireless.com 1 Radio Frame (10 ms) 1 subframe (1 ms) 1 slot (0.5 ms) Slot = 7 OFDM symbols (Normal CP) CP CP CP CP CP CPUseful Part CP Useful Part CP Useful Part CP Useful Part CP Useful Part CP Useful Part CP Useful Part CP Useful Part 1 OFDM symbol (83μs) 1 OFDM symbol (71μs) Frame = 10 subframes Subframe = 2 slots Slot = 6 OFDM symbols (Extended CP) or Useful Part Useful Part Useful Part Useful Part Useful Part Radio Frame Time Structure
  • Technical content provided by IS-Wireless, www.is-wireless.com 1 Symbol in the frequency domain Subcarrier (SC) BW: 1.4MHz = 128 SC (72 useful SC) 3MHz = 256 SC (180 useful SC) 5MHz = 512 SC (300 useful SC) 10MHz = 1024 SC (600 useful SC) 15MHz = 1536 SC (900 useful SC) 20MHz = 2048 SC (1200 useful SC) Smallest allocation 12 SCs (180kHz) Guardband (not used SCs) Guardband (not used SCs) DC subcarrier (not used in DL) Pilot subcarrier (QPSK symbol) Data Subcarrier (QPSK/16QAM/64QAM symbol) Useful Subcarriers Radio Frame Frequency Structure
  • Technical content provided by IS-Wireless, www.is-wireless.com TDD E-UTRA Radio Frame Downlink Frame Parts (e.g. Configuration 1) 1 slot (0.5 ms) Control Region: First 1-3 OFDM Symbols in subframe (for DwPTS 1-2 Symbols) PCFICH – OFDM symbol 0, PHICH – OFDM symbol 0 PDCCH – the rest PBCH – 4 OFDM symbols (0-3) in slot 1 in subframe 0 Synchronization Signals: P-SS – OFDM symbol 2 in subframe 1 and 6 S-SS – OFDM symbol 13 in subframe 0 and 5 BW PDSCH – rest REs DC 1 subframe (1 ms) 62 SCs 72 SCs 1 Radio Frame (10 ms) 12 SC 7 OFDM Symbols RS RE 2 PRB OFDM Subcarrier OFDM Symbol Guard Band for S-SS or P-SS ULTransmission ULTransmission DwPTS
  • Technical content provided by IS-Wireless, www.is-wireless.com TDD E-UTRA Radio Frame Uplink Parts (e.g. Configuration 1) DLTransmission PUCCH – firsts and last PRB alternatively SRS – on demand last SCFDMA symbol in subframe every second subcarrier (also in UpPTS) 12 SC 1 slot (0.5 ms) 2 PRB PUSCH – rest REs 1 Radio Frame (10 ms) 1 subframe (1 ms) BW PRACH – 72 subcarriers x 1 subframe May appear several times within a frame, up to 6 RACHs in subframe (also shorter RACH 72 subcarriers x 2 symbols in UpPTS) DRS 7 SCFDMA Symbols PUSCH – can include: • User data multiplexed with feedback: CQI/PMI/RI/HARQ-ACK • Only feedback: CQI/PMI/RI/HARQ-ACK UpPTS UpPTS DLTransmission DLTransmission
  • Technical content provided by IS-Wireless, www.is-wireless.com TDD E-UTRA Radio Frame DL and UL Subframe Configuration 1 1 slot (0.5 ms) BW DC 1 subframe (1 ms) 62 SCs 72 SCs 1 Radio Frame (10 ms) DwPTS Downlink SF UpPTSGP Special SF Uplink SF Uplink SF Downlink SF Downlink SF Special SF Uplink SF Uplink SF Downlink SF
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE Rel. 8 Duplex Types Frequency Division Duplex Half-duplex FDD DL: fC UL: fC DL: fC UL: fC Time Division Duplex DL/UL: fC FDD for reduced UE complexity t f t f t f UL and DL selected from different frequency bands UL and DL use the same frequency band divided in time
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE Rel. 8 Radio Frame Differences Between FDD and TDD DLUL FDD frame 10ms frame TDD frame (example configuration) DL/UL One half frame (5ms) 10ms frame 1ms subframe 1ms subframe Control Region (CR) DL resource allocation ptr UL resource allocation ptr Special Subframe 0 1 2 3 4 5 6 7 8 9 # Subframe DL/UL Switch FDD DL/UL resource allocations: single allocation PDCCH – single PDSCH/PUSCH TDD DL resource allocation: single allocation PDCCH – single PDSCH TDD UL resource allocation possible single allocation PDCCH – for multiple PUSCHs (for UL heavy conf) DL:DCIsubframen,allocsubframen UL:DCIsubframen,allocsubframen+4 DL:DCIsubframen,allocsubframen UL:DCIsubframen,allocsubframen+k(k=4-7) P-SS S-SS Different placement of sync signals After synchronization UE knows already if this is TDD or FDD system
  • Technical content provided by IS-Wireless, www.is-wireless.com E-UTRA TDD Radio Frame Configurations DL/UL configuration is broadcasted in SIB 1 (subframe #5) Configuration 0 DL:UL 2:3 (UL HEAVY) Configuration 1 DL:UL 3:2 Configuration 2 DL:UL 4:1 5ms half frame 10ms frame Configuration 3 DL:UL 7:3 Configuration 4 DL:UL 8:2 Configuration 5 DL:UL 9:1 (DL HEAVY) Configuration 6 DL:UL 5:5 5 ms switch periodicity configurations 10 ms switch periodicity configurationsGuard period Downlink Uplink 1ms subframe 0 1 2 3 4 5 6 7 8 9# Subframe Special Subframe Special Subframe
  • Technical content provided by IS-Wireless, www.is-wireless.com Special Subframe Structure and Configurations Special switching subframes #1 and #6 UpPTSDwPTS GP Subframe (1ms), 14 OFDM Symbols Downlink Pilot Time Slot Guard Period Uplink Pilot Time Slot DLUL switch time (no transmission) To allow UE to switch from Rx to Tx To support coexistence with other systems Normal, but shorter DL subframe includes: * Control region – 1 to 2 symbols * P-SS * PDSCH and RSs – 1 to 10 symbols Possible Configurations (normal CP) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 0 1 2 3 4 5 6 7 8 Symbol number Configuration PDCCH PCFICH PHICH PDCCH or PDSCH P-SS PDSCH SRS or PRACH PDSCH
  • Technical content provided by IS-Wireless, www.is-wireless.com E-UTRA Rel.8 MIMO Processing OFDMA Mod OFDMA Mod FEC/ Mod FEC/ Mod Layer Mapping MIMO Precoding Resource Mapping Resource Mapping Channel Matrix BS Tx UE Rx OFDMA deMod OFDMA deMod deFEC/ deMod deFEC/ deMod Layer deMapping MIMO dePrecoding Resource deMapping Resource deMapping Data bits Data bits Data bits Data bits 1 or 2 transport blocks 1 or 2 codewords 1 to 4 layers 1 to 4 antennas MIMO Processing Selection of predefined Matrix Selection of technique (SISO/ SM/TxDiv) Channel estimation Synchronization Channel correction CQI, ACK/NACK PMI/RI CQI Feedback Indicates preferred matrix Indicates number of layers Different RSs placement for accurate channel estimation mapping of symbols into the transmit antenna port independently encoded data block Indicates good part of the spectrum Indicates achievable spectral efficiency
  • Technical content provided by IS-Wireless, www.is-wireless.com EUTRA MIMO MIMO Operation for SFBC Layer Mapping One codeword 2 Layers MIMO Precoding 2 antennas Matrix for 2 antennas Matrix for 4 antennas Alamouti with antennas switch x4x3x2x1 x4 x3 x2 x1 x*3 -x* 4 x*1 -x* 2 x3 x1 x4 x2 Towards Resource Mapping Mapped to different SCs 2 antennas are used in a single symbol transmission
  • Technical content provided by IS-Wireless, www.is-wireless.com EUTRA MIMO MIMO Operation for SM (1/2) Precoding for CL SM (low speed scenario) Precoding for OL SM with large CDD (high speed scenario) Precoding matrix Large CDD matrix For CL UE indicates PMI – index of matrix W Layer Mapping 2 codewords 3 Layers MIMO Precoding (W) 4 antennas x2x1 z21 z11 x2 x1 y2 y1 Towards Resource Mapping y4y3y2y1 y4 y3 z22 z12 z23 z13 z24 z14 z1=Wv1 z2=Wv2 v1v2 BS may or may not to use it
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE MIMO - Large delay CDD - Cyclically assigned precoding matrices - For high mobile users - SU-MIMO: 2x2, 4x2, 4x4 - UE feedbacks the CQI, PMI (codebook selection) with Rank adaptation - 1 or 2 codewords applies - Pair of UE uses the same TF resources with Rank=1 transmission - MU-MIMO precoding vector uses a subset of SU-MIMO codebook Open-loop Spatial Multiplexing Closed-loop Spatial Multiplexing Multi-User MIMO MCS eNB Code books Channel UE Channel estimation Code books MCS eNB Code books MCS Feedback processing UE 1 Channel 1 estimation Code books UE 2 Channel 2 estimation Code books MCS eNB Code books Channel UE Channel estimation UEs are semistatically assigned to MU-MIMO mode. UE is not allowed to be scheduled in MU-Mode in one subframe and SU MIMO in the next one Only one stream can be allocated to a UE operating in a MU-Mode MIMO Operation for SM (2/2)
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE MIMO MIMO Operation for BF Eigenbeamforming Suitable precoding is chosen as a form of eigenbeamforming for 1layer-1codeword the same matrices as for SVD SM Based on UE specific RS. UE sends in UL then BS adjust RF parts. Phased array appears at UE as a single transmission, for UEs at cell edge Layer Mapping 1 codeword 1 Layer MIMO Precoding (W) 4 antennas z21 z11 x4x3x2 x1 Towards Resource Mapping z22 z12 z23 z13 z24 z14 z1=Wx1 z2=Wx2 x4x3x2 x1 DoA based beamforming 2 Types of BF Specs don’t include exact definition of operation for these
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE MIMO Feedback Reporting UE eNB UE Rank Indication Good uncorrelation of spatial channels (3 streams are transmitted) Worse uncorrelation of spatial channels (2 streams can be transmitted) Rank indication informs base station how many layers/streams can it transmit RI = 2 RI = 3 Precoding Matrix Indication UE eNB UE PMI = 0 PMI = 2        10 01 0P          11 11 2P . . . Channel realization 1 Matrix P2 applied Channel realization 2 (conditions has changed) Matrix P0 applied Precoding matrix indication is used by the UE for pointing to the selected codebook index for 2 and 4 antennas (only for SM) Single RI per UE allocation Single PMI per UE allocation if allocated RB < 12, per 5RB if allocated RB > 12 Minimum periodicity of the reports = 1subframe (1ms) Examples Examples
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE MIMO Spatial Mode Switching Transmission mode Multi-antenna mode of PDSCH 1 Single-antenna port, port 0 2 Transmit diversity 3 Transmit diversity if the associated rank indicator is 1, otherwise large delay CDD 4 Closed-loop spatial multiplexing 5 Multi-user MIMO 6 Closed-loop spatial multiplexing with a single transmission layer 7 If the number of PBCH antenna ports is one, Single-antenna port, port 0; otherwise Transmit diversity FEC/ Modulator SD encoder Tx Mode Resource Mapper SM Encoder Resource Mapper IFFT IFFT Tx mode selection SD layer mapper SM layer mapper SNIR SpectralEfficiency Switching point (10dB – rule of thumb) SM SD
  • Technical content provided by IS-Wireless, www.is-wireless.com LTE MIMO Rel. 8 Scenarios eNB UE eNB UE UE eNB UE UE eNB UE Space Diversity DL: 2x1, 2x2, 4x1, 4x2, UL: 1x2, 1x4 Used for: PHICH, PCFICH, PDCCH, PBCH, PDSCH, PUSCH Uncorrelated Channels (rich scattering) Poor Channel (Fast variations) Precoded 2 copies of the same signal SFBC rank-1 transmission Improved Link Reliability SU-MIMO (Spatial Multiplexing) DL: 2x2, 4x2, 4x4 Used for: PDSCH (traffic) Uncorrelated Channels (rich scattering) Good Channel (slow variations) Precoded 2 different streams Increase in throughput MU-MIMO (Spatial Multiplexing) DL: 2x1, UL: 1x2 Used for: PDSCH(traffic) Uncorrelated Channels (rich scattering) Good Channels Precoded 2 different streams for 2 users Increase in system capacity Beamforming DL: 2x1, 4x1, 8x1 Used for: PDSCH, PUSCH (traffic) Uncorrelated Channels (between users) Poor/Good channels (for each user) Increase in coverage Less interference Detailed operation not described in specs