LTE物理层综合介绍

,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,UNIVERSITY OF NEBRASKA LINCOLN,COLLEGE OF ENGINEERING,Advanced Telecommunications Engineering Laboratory (www.TEL.unl.edu),A Comprehensive Analysis Of LTE Physical Layer,Master of Science Thesis,Fahimeh Rezaei,Supervisor: Dr.Hamid Sharif-Kashani, Dr. Michael Hempel,Department of Computer and Electronics Engineering,University of Nebraska-Lincoln,December, 1,st,2010,Outline,Background,LTE General Architecture,Thesis Objective and Motivation,Literature Review,LTE Physical Layer Characteristics,Performance Study Approach,Simulation Results and Analysis,Summary and Conclusion,Background,LTE General ArchitectureThesis Objective and MotivationLiterature ReviewLTE Physical Layer CharacteristicsPerformance Study ApproachSimulation Results and AnalysisSummary and Conclusion,Background,Standard developers: 3GPP, IEEE, and 3GPP2,3,rd,Generation Standards:,Long Term Evolution (LTE Release8),802.16e (WiMAX), 802.16m,UMB,4,th,Generation standards,Satisfy IMT-Advanced Requirements : 100 Mbps in high mobility (300 km/h) and 1 Gbps in low mobility (3 km/h), less than 5ms Data Latency, ,LTE Release8 General Features,Packet Switched Network,OFDM in Downlink and SC-FDMA in Uplink,Duplex Schemes: TDD and FDD,Adoptive Modulation and Coding scheme (QPSK, 16-QAM, 64-QAM),Multiple Antenna Techniques,Transmit Diversity,Single User MIMO,Multi User MIMO,Close-Loop rank1 precoding,dedicated beam forming,System Bandwidth from 1.4 MHz to 20MHz (1.4, 3, 5, 10, 15, 20),Background,LTE General Architecture,Thesis Objective and MotivationLiterature ReviewLTE Physical Layer CharacteristicsPerformance Study ApproachSimulation Results and AnalysisSummary and Conclusion,General Architecture,Long Term Evolution associated with radio access technology,System Architecture Evolution (SAE) associated with the core network,LTE architecture-EPS:,E-UTRAN (EUTRA Node) - LTE,EPC (Evolved Packet Core) - SAE,User Plane and Control Plane Protocol Stacks,Background,LTE General Architecture,Thesis Objective and Motivation,Literature ReviewLTE Physical Layer CharacteristicsPerformance Study ApproachSimulation Results and AnalysisSummary and Conclusion,Thesis Objective and Motivations,Are these values accurate or even correct?,Is the right approach used for getting proposed values and results?,In which conditions and scenarios presented values and results are valid?,Thesis Objective and Motivations, cnt.,Provide the,right approach for evaluation of physical layer performance,Provide a performance study that includes,all possible scenarios,which is addresses by,Different antenna diversity modes,Different modulation schemes and code rates,Include both FDD and TDD operations,Include all channel bandwidths,Understanding the performance evaluation approaches used before,(Literature Review),Profound understanding of Physical layer Structure to determine resource allocation used for data and control information transmission,(LTE Physical Layer Configuration ),Implementing the physical layer procedure to provide an accurate simulation model,(Performance study approach and simulation results),Background,LTE General ArchitectureThesis Objective and Motivation,Literature Review,LTE Physical Layer CharacteristicsPerformance Study ApproachSimulation Results and AnalysisSummary and Conclusion,Literature Review,J. J. Snchez, D. Morales-Jimnez, G. Gmez, J. T. Enbrambasaguas, “Physical Layer Performance of Long Term Evolution Cellular Technology”, 16th IST Mobile and Wireless Communications Summit, 2007.,This paper mainly focuses on outlining the impact of different features of LTE on performance. However, at the time of this publication, some characteristics of LTE were under development, e.g., channel coding and rate matching, 4x4 MIMO.,D. M. Sacristn, J. Cabrejas, D. Calabuig, J. F. Monserrat , Institute of Telecommunications and Multimedia Applications, “MAC Layer Performance of Different Channel Estimation Techniques in UTRAN LTE Downlink”, 69,th, IEEE, VTC,Performance study is limited to downlink transmission. Simulation results are based on 10 MHz system bandwidth, one transmit and two receive antenna (SIMO),Literature Review, cnt.,D.M. Sacristn,J. F. Monserrat,J. Cabrejas, D. Calabuig,S. Garrigas,N. Cardona, “ On the Way towards Fourth-Generation Mobile: 3GPP LTE and LTE-Advanced ”, EURASIP Journal on Wireless Communications and Networking, July 2009,This paper also presents a performance analysis for 10 MHz of channel bandwidth, MIMO 4x4 and 2x2 in downlink and MIMO 1x2 in uplink cases.,The maximum throughput of the downlink and uplink is stated to be around 130 Mbps and 40 Mbps, respectively. (2 OFDM symbol for PDCCH and ),C. Ball, T. Hindelang, I. Kambourov, S. Eder, “Spectral Efficiency Assessment and Radio Performance Comparison between LTE and WiMAX “, 2008 IEEE,Performance comparison of LTE and WiMAX is limited to Downlink FDD scenario, not excluding control information.,Maximum Downlink Throughput: 120Mbps (2x2 MIMO),3GPP R1-072261, “LTE Performance EvaluationUplink Summary,” May 2007.,3GPP R1-072578, “Summary of Downlink Performance Evaluation,” May 2007.,Maximum Downlink Maximum Throughput: 326.4 Mbps,Maximum Uplink Throughput: 86.4 Mbps,Background,LTE General ArchitectureThesis Objective and MotivationLiterature Review,LTE Physical Layer Characteristics,Performance Study ApproachSimulation Results and AnalysisSummary and Conclusion,LTE Transmission Procedure,Physical Layer Structure,Uplink-Downlink configuration,Downlink-Uplink switch point Periodicity (ms),Subframe number,0,1,2,3,4,5,6,7,8,9,0,5,D,S,U,U,U,D,S,U,U,U,1,5,D,S,U,U,D,D,S,U,U,D,2,5,D,S,U,D,D,D,S,U,D,D,3,10,D,S,U,U,U,D,D,D,D,D,4,10,D,S,U,U,D,D,D,D,D,D,5,10,D,S,U,D,D,D,D,D,D,D,6,5,D,S,U,U,U,D,S,U,U,D,T,s,= 1/ (15000*2048),: 2048,is the FFT length,Frame size: 10 ms (,is 307200* T,s,),Subframe : 1ms, slot: 0.5 ms,A special subframe does not exist in second half frames with 10ms downlink to uplink switch point periodicity,Physical Layer Structure, cnt.,Channel Bandwidth,(MHz),1.4,3,5,10,15,20,Number of RBs,6,15,25,50,75,100,Normal Cyclic Prefix,Extended Cyclic,Prefix,Subcarrier Spacing:,15kHz,Subcarrier Spacing: 15kHz,Subcarrier Spacing: 7.5kHz,Downlink,Number of OFDM Symbols,7,6,3,Number of Subcarriers,12,12,24,Uplink,Number of SC-FDMA Symbols,7,6,-,Number of Subcarriers,12,12,-,Downlink Physical Channels,PDSCH: Physical Downlink Share Channel,This physical channel is utilized for transmission of user data, broadcast system information that is not transmitted by PBCH, and paging messages,QPSK, 16QAM, and 64-QAM,PBCH: Physical Broadcast Channel,Physical broadcast channel contains basic information for UE to access the cell,72 subcarriers and 4 OFDM symbols, QPSK Modulation.,PDCCH: Physical Downlink Control Channel,This channel conveys UE specific control information such as scheduling assignment, resource allocation of physical channels, and HARQ information,It can occupy 1 to 4 OFDM symbols based on Channel Conditions, antenna ports, ,QPSK modulation,PCFICH: Physical Control Format Indicator Channel,The number of OFDM symbols that used for PDCCH transmission in each subframe is specified by PCFICH,16 resource elements in the first OFDM symbol,QPSK modulation,PHICH: Physical Hybrid ARQ Indicator Channel,When eNB receives a transmission on the PUSCH, it sends back ACK (0 for positive Acknowledgement) and NACK (1 for Negative Acknowledgement) through PHAICH,BPSK Modulation,PMCH: Physical Multicast Channel,Multimedia Broadcast and Multicast Services (MBMS) are available in later releases of LTE such as Release 9 and 10,Downlink Reference Signals,P-SS: Primary Synchronization Signal,P-SS provides slot timing information and Physical layer ID for UE,2 OFDM Symbols are assigned for P-SS,S-SS: Secondary Synchronization Signal,S-SS utilizes UE with the information of cell ID, cyclic prefix length, and whether the eNB is working based on TDD or FDD operations.,2 OFDM Symbols are assigned for S-SS,RS: Reference Signal,Reference signals (RSs) in LTE are used for channel estimation and are sent on particular resource elements by a predefined structure,Cell-specific RSs that are available to all UEs in the cell and also known as common RSs.,UE-specific RSs that are used for specific UEs,MBSFN-specific RSs that are used for MBFSN operations,Uplink Physical Channels and Reference Signal,PUSCH: Physical Uplink Share Channel,Uplink Data transmission , QPSK, 16-QAM, and 64-QAM,PUCCH: Physical Uplink Control Channel,Control information such as HARQ ACK/NACK, CQI,6 formats based on the information that this channel contains,PRACH: Physical Random Access Channel,Provides random access operation for non-Synchronous UEs or UEs that lost their synchronization,Demodulation Reference Signals,D-RS-PUSCH and D-RS-PUCCH,Channel estimation and coherent demodulation,Occupies the same bandwidth as its associated physical channel,S-RS: Sounding Reference Signal,This reference signal is mainly used for channel quality estimation for frequency selective scheduling or providing initialization and set-up functions for UEs that are not scheduled.,Downlink and uplink physical, transport and logical channel mapping,Logical Channels,Transport Channels,Physical Channels,Background,LTE General ArchitectureThesis Objective and MotivationLiterature ReviewLTE Physical Layer Characteristics,Performance Study Approach,Simulation Results and AnalysisSummary and Conclusion,FDD Downlink Physical Layer Outline,FDD Uplink Physical Layer Outline,TDD Physical Layer Outline,FDD PDSCH Maximum REs,One antenna port,Two antenna ports,Four antenna ports,In case of 4 antenna ports , 1 OFDM symbol assigned for PDCCH, and 64-QAM modulation scheme, throughput is 325.132 Mbps,By applying the maximum code rate (0.92) the throughput is 299.122 Mbps.,FDD PUSCH Maximum REs,Using 64-QAM modulation scheme for PUSCH data, the throughput is: 84.672 Mbps,By applying the maximum code rate (0.85) the throughput is 71.97Mbps.,TDD Uplink and Downlink Maximum REs,Downlink Maximum Throughput: 260.16, assuming 0.92 code rate: 239.34 Mbps,Uplink Maximum Throughput : 50.80 Mbps assuming 0.85 code rate: 43.18 Mbps,PDSCH Res, Mode 5,PUSCH Res, Mode 0,Downlink transport channel and physical channel processing for data transmission,24 bits of CRC,Code block size form 40 to 6144,1/3 turbo coder,Different puncturing patterns to create different rates,Uplink transport channel and physical channel processing for data transmission,After concatenation, the data and CQI or/and PMI control information are multiplexed together,Channel interleaver,maps the adjacent data symbols to the adjacent SC-FDMA symbols in the time domain first and then in the frequency domain,transform precoding refers to dividing the block of input symbols M into M/ NSC,rb,sets that each set corresponds to one SC-FDMA symbol,Channel Coding and Rate Matching,Turbo coding basic rate is 1/3,Interleaver is Quadratic Permutation Polynomial,Rate Matching (RM) algorithm selects bits for transmission via puncturing or repetition,Simulation Parameters,Simulations are done in MATLAB Using CML library,Two different code block sizes are used: 6144 and 40 (the maximum and minimum),Parameter,Value(s),Channel Bandwidth,1.4, 3, 5, 10, 15, 20 (MHz),FFT Length,2048,Maximum Number of RBs,100,Duplex Mode,FDD, TDD,Channel Type,AWGN,FEC Coding Scheme,Turbo coding, R=1/3,Modulation,QPSK, 16-QAM, 64-QAM,Frame Period,10 ms,Subcarrier spacing,15 kHz,Cyclic prefix,Normal,Code Block Sizes,40, 6144,Code Rates,0.33 to 0.92,Antenna Diversity,SISO, 2x2 MIMO, and 4x4 MIMO,Maximum iteration of turbo code,10,Wrap up depth for turbo code,6,Min BER,10,-9,Max BER,10,-4,Number of Errors,300,Background,LTE General ArchitectureThesis Objective and MotivationLiterature ReviewLTE Physical Layer CharacteristicsPerformance Study Approach,Simulation Results and Analysis,Summary and Conclusion,Simulation Results and Analysis,Frame sizes: 40 and 6144,QPSK, 16-QAM, 64-QAM,Simulation Results, cont.,PDSCH Throughput,1.4 MHz SISO and 20 MHZ 4x4 MIMO,QPSK, RC= 0.75,16-QAM , RC = 0.85,64-QAM, RC=0.85,Simulation Results, cont.,PUSCH throughput,1.4 MHz and 20 MHZ,QPSK, RC= 0.75,16-QAM , RC = 0.85,64-QAM, RC=0.85,Simulation Results, cont.,1.4 MHZ,20 MHz,QPSK,RC=0.75,0.817,20.039,16-QAM, RC=0.85,2.47,47.980,64-QAM,RC= 0.85,3.56,71.971,1.4 MHZ, SISO,20 MHz, MIMO 4x4,4 OFDM,2 OFDM,3 OFDM,1 OFDM,2 OFDM,3 OFDM,QPSK, RC=0.75,0.941,1.157,1.049,81.383,76.483,69.283,16-QAM, RC=0.85,2.13,2.62,2.37,184.241,173.361,157.041,64-QAM,RC= 0.85,3.20,3.935,3.567,276.362,260.0428,235.562,Simulation Results, cont.,PDSCH throughput,1.4 MHz SISO and 20 MHZ 4x4 MIMO,Mode0 and 5,QPSK, RC= 0.75,16-QAM , RC = 0.85,64-QAM, RC=0.85,Simulation Results, cont.,PUSCH throughput,1.4 MHz and 20 MHZ,Mode0 and 5,QPSK, RC= 0.75,16-QAM , RC = 0.85,64-QAM, RC=0.85,Simulation Results, cont.,1.4 MHz SISO,QPSK,0.75,16-QAM, 0.85,64-QAM,0.85,PDSCH,MOD 0,0.165288,0.39576,0.59364,MOD5,0.932372,1.93244,2.84866,PUSCH,MOD0,0.518,1.17,1.76,MOD5,0.11928,0.2856,0.4284,20 MHZ, MIMO,QPSK,0.75,16-QAM, 0.85,64-QAM,0.85,PDSCH,MOD 0,13.68,31.02,46.54,MOD5,55.44,125.685,188.528,PUSCH,MOD0,12.70,28.78,43.18,MOD5,2.11,4.79,7.19,Background,LTE General ArchitectureThesis Objective and MotivationLiterature ReviewLTE Physical Layer CharacteristicsPerformance Study ApproachSimulation Results and Analysis,Summary and Conclusion,Summary and Conclusion,Throughput calculation exclusively contains data channels (PUSCH and PDSCH) for both FDD and TDD operations,High performance in respect to signal- to-noise ratio resulted from turbo coding, interleaver and rate matching algorithm of LTE Release8,Overall Control information overhead is low, providing more resources for data transmission.,FDD Maximum Throughput,299.122 Mbps in Downlink,71.97 Mbps in Uplink,TDD Maximum Throughput,205.684Mbps in downlink,42.696 Mbps in uplink,Questions and Comments,