lte介紹（諾基亞西門子內(nèi)部培訓資料）-文庫吧
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【正文】 IP UDP UDP GTPU GTPU eNB MAC L2 eNB S1 RLC PHY PHY eUE eUu L1 MME L2 L1 IP IP SCTP SCTP S1AP S1AP PDCP MAC RLC PDCP RRC RRC NAS NAS L2 X2 L1 L2 L1 IP IP SCTP SCTP X2AP X2AP eNB eNB 13 169。 Nokia Siemens Networks Charles / 20220505 For internal use LTE Physical Layer For internal use 14 169。 Nokia Siemens Networks Charles / 20220505 Functionality of Physical Layer ? Data Transfer via Transport Channels. ? Error Detection. Hybrid ARQ Combining. ? Channel Coding and Rate Matching. ? Modulation and Demodulation. ? Measurements. ? MIMO, Transmit Diversity, Beamforming. ? RF Processing. For internal use 15 169。 Nokia Siemens Networks Charles / 20220505 Orthogonal Frequency Division Multiplexing Figure 1: FrequencyTime Representation of an OFDM Signal OFDM is a digital multicarrier modulation scheme, which uses a large number of closelyspaced orthogonal subcarriers. Each subcarrier is modulated with a conventional modulation scheme (such as QPSK, 16QAM, 64QAM) at a low symbol rate similar to conventional singlecarrier modulation schemes in the same bandwidth. For internal use 16 169。 Nokia Siemens Networks Charles / 20220505 LTE Radio principles ? Power efficient uplink increasing battery lifetime ? Improved cell edge performance by low peak to average ratio ? Reduced Terminal plexity Uplink: SCFDMA ? Enabling peak cell data rates of 173 Mbps DL and 58 Mbps in UL * ? Scalable bandwidth: / 3 / 5 / 10 /15 / 20 MHz also allows deployment in lower frequency bands (rural coverage, refarming) ? Short latency: 10 – 20 ms ** ? Improved spectral efficiency ? Reduced interference ? Very well suited for MIMO Downlink: OFDMA * At 20 MHz bandwidth, FDD, 2 Tx, 2 Rx, DL MIMO, PHY layer gross bit rate ** roundtrip ping delay (server near RAN) For internal use 17 169。 Nokia Siemens Networks Charles / 20220505 OFMD Downlink amp。 SCFDMA Uplink TDD Timing SCFDMA: PRB?s are grouped to bring down Peak to Average Power Ratio (PAPR) better power efficiency at the terminal MHz = 72 Tones 20 MHz = 1200 Tones Subchannels / Tones (each 15 kHz) 1 TTI = 1ms 1 PRB (Physical Resource Block) = 12 Subcarriers = 180 kHz 1 PRB = 2 Slots = 2 * ms User 1 User 2 User 3 User .. Special subframe containing guard period (switching from DL UL) For internal use 18 169。 Nokia Siemens Networks Charles / 20220505 Physical Layer definitions – Frame Structure (DL) – Slot/Frame NsymbDL OFDM symbols (=7 OFDM symbols @ Normal CP) Cyclic Prefix 160 2048 144 2048 144 2048 144 2048 144 2048 144 2048 144 2048 (x Ts) 1slot = 15360 1 0 2 3 4 5 6 1 0 2 3 4 5 6 0 1 2 3 4 5 6 PSCH SSCH PBCH PDCCH Reference Signal 1 frame 1 subframe 1 slot 0 1 8 2 3 4 5 6 7 9 10 11 12 19 13 14 15 16 17 18 Ts = 1 / (15000x2048)= Configuration CP length Guard interval FS type1 FS type2 Normal CP ?f=15kHz 160 (0) 512 (8 slot0) 224 otherwise 0 (slot) 288 otherwise 144 (1..6) Extended CP ?f=15kHz 512 (0 .. 5) 768 (7 slot0) 512 otherwise 0 (slot) 288 otherwise ?f= 1024 (0..2) 1280 (3 slot0) 1024 otherwise For internal use 19 169。 Nokia Siemens Networks Charles / 20220505 Ts = 1 / (15000x2048)= Ts: Time clock unit for definitions Frame Structure type 2 (TDD) DwPTS, T(variable) One radio frame, Tf = 307200 x Ts = 10 ms One halfframe, 153600 x Ts = 5 ms 0 2 3 4 5 One subframe, 30720 x Ts = 1 ms Guard period, T(variable) UpPTS, Ｔ(variable) One slot, Tslot =15360 x Ts = ms 7 8 9 For 5ms switchpoint periodicity
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