LTE帧结构和协议

1、一、协议知识1. LTE帧结构及物理资源基本概念RE/RB/CCE/REG/RBG帧结构Typel: FDD（全双工和半双工）（FDD上下行数据在不同的频带里传输；使用成对频谱）每一个无线帧长度为10ms,由20个时隙构成，每一个时隙长度为Tslot = 15630 x Ts =。对于FDD在每一个10ms中，有10个子帧可以用于下行传输，并且有10个子帧可以用于上行传输。上下行传输在频域上进行分开。#0#1#2斗 slot Sub-frame 我One radio frame = 10ms#18#19帧结构Type2 : TDD （TDDh下行数据可以在同一频带内传输；可使用非成对频谱）一个

2、无线帧10ms，每个无线帧由两个半帧构成，每个半帧长度为5mso每一个半帧由8个常规时隙和DwPTS GP和UpPTS三个特殊时隙构成，DwPT和UpPTS勺长度可配置，要求 DwPTS GF以及UpPTS勺总长度为1ms。=One radio frame =10 ms亠 One half frame =5 ms 1 ms 一尸:111#2#3厂B 1 1#7# 8# 911111!E11|DwPTS GP UpPTSDwPTS GP UpPTSDwPTS: Dow nlink Pilot Time SlotGP: Guard Period(GP越大说明小区覆盖半径越大)UpPTS: Upli

3、nk Pilot SlotTs = 1 / (15000x2048) sFrame 帧的长度： Tf = 307200 x Ts = 10msSubframe 子帧的长度： Tsubframe = 30720 x Ts = 1msSlot 时隙的长度：Tslot = 15360 x Ts =1 Sub-Carrier = 15 kH z;1 TTI = 1 ms = 1 sub-frame = 2 slots ms *2)# for one user, min 2 RB allocati on.1 RB = 12 sub-carriers dur ing 1 slot ms) =12 * 15

4、kHz =180kHz (Ba ndwidth); = 12 * 7 symbols=84 REs1 RE= 1 sub-carrier x 1 symbol period (Each symbol is QPSK, 16QAM or 64QAM modulated. )LTE支持可变带宽：，3, 5, 10, 15 和20MHz一个小区 最少使用 6 个 RB,即最少包含 72 个 sub-carriers: 6 RB * 12 sub-carriers = 72 sub-carriers一个小区 最多 支持 110 个 RB,相当于 1320 个 sub-carriers: 110 *12

5、 =1320 sub-carriersCha nnel ban dwidthBWhannel MHz35101520Tran smissi on ban dwidth615255075100特殊帧格式 7: DwPTS:GP:UpPTS = ( 21952Ts-32Ts) :4384TS : 4384Ts= 10:2:2最小分配单位为：2192 TsCon figure TDD:上下行配置（下图）+特殊帧格式（上图）2:7 1:7)Upli nk-dow nli nkcon figurati onDow nlin k-to-Upli nkSwitch-po int periodicitySub

6、frame n umber012345678905 msDSUUUDSUUU1 2:25 msDSUUDDSUUD2 3:15 msDSUDDDSUDD310 msDSUUUDDDDD410 msDSUUDDDDDD510 msDSUDDDDDDD65 msDSUUUDSUUDTDD支持5ms和10ms的周期转换：= 5ms转换周期：一个帧的上下半帧的特殊帧格式配置相同，= 10ms转换周期：一个帧分成上下半帧，下半帧的特殊帧为DwPTS=1m，用于DL传输(如上图3，4，5所示)RE Resource Element ，称为资源粒子，是上下行传输使用的最小资源单位。1 RE = 1 subc

7、arrier x 1 symbol periodRB: Resource Block ，称为资源块，用于描述物理信道到资源粒子的映射。一个RB包含若干个R吕一个RB由 12个在频域上的子载波和时域上一个slot周期构成(1 RB = 12 subcarriers x 1 slot)。1 个 RB在频域上对应 180kHz : 1 RB = 12 subcarriers x 15kHz = 180kHz1个RB在时域上对应1个时隙，1 slot =CCE Control Channel Element，称为控制信道粒子，PDCC在一个或多个 CCEh传输，CCE寸应于9个REG 每个REG包含

8、4个 RECCED 0 开始编号。(1 CCE = 9 REGs = 9 x 4 REs = 36 REs )PDCCH format与CCE间的关系如下图所示：PDCCH formatNumber of CCEsNumber of REGsNumber of PDCCH bits(QPSK)01972121814424362883872576REG Resource Element Group ，用来定义控制信道到RE的映射.(1 REG = 4 REs)RBG Resource Block Group ， RBG连续的PRB勺集合，其大小根据系统带宽配置的不同而定，如下图所示:System

9、 Ban dwidth (Number of DL RBs)RBG Size ( P) Dedicated Search Space (for only one UE) & CSS = Com mon Search Space (for several UEs)PDCCH decoding (4/4)2 candidates having 8PDCCHNo. of CCEs No. oftormatcandidates incommonHE 4search space382244PDCCHNo. of CCEs No. offormatcamdidate incommonUE 2search

10、spaceCCEs each226utninniffl叩叩叩印口叩叩o叩叩叩i6Gammon search space22No. of ca ndidates in dedicated se arch space闻皿HE叵No. of candidates in dedicated search spaceDedicated search space (UE2|亠丄丄山山山山一I LU 一LLiffiraffiiazaoDoaz 匸匚咖血B2.4 PDSCH Physical Downlink Shared Channel(物理下行共享信道)-用于承载DL-SCHW息，传递 SIB信息(SIB

11、消息传递方向：BCCH - DL-SCH - PDSCH)-SIB1消息的重复周期为 80ms,初始位置为 subframe#5 of SFN mod 8 = 0 ，在SFN mod 2 = 0的帧上重复.SIB - System In formation Blocks-SIB1: Cell Access Info (PLMN, TAC, CID )；小区选择相关信息；TDD相关配置信息；余下SIB的时域调度信息 -SIB2:公共信道的 无线资源配置 (PCCH, RACH); freqInfo (ul-carrierFreq, ul-bandwidth);defaultPagi ngCycl

12、e-SIB3: Cell re-selectio n in formati on.(In tra/I nter freque ncy or/a nd In ter-RAT cell re-selectio n)-SIB4: Neighbor cell related info only forIntra-frequencycell re-selection information.-SIB5: E-UTRAN Inter-frequencycell re-selection information.-SIB6: UTRAZrequencies and neighboring cell re-s

13、election.-SIB7: GERANrequencies cell re-selection.-SIB8: CDMA2000 frequencies and neighbouring cell re-selection.-SIB9: Home eNB.-SIB10: ETWS primary notification.-SIB11: ETWS secondary notification.-如果UE专用参考信号不被传输，使用天线端口集合P = 0 ,0,1 , or 0,1,2,3-如果UE专用参考信号被传输，则使用天线端口P = 52.5 PHICH: Physical HARQ In

14、dicator Channel（物理 HAR指示信道）-用于承载HAR的ACK/NACK-在每个 subframe 的第 1个 symbol 上进行传递（symbol 0 of each subframe ）-一个PHICH组对应于3个REG 12个RE资源2.6 PMCH Physical Multicast Channel（物理多播信道）-目前不支持，无需掌握没有对传输分集方案进行标准化单天线端口传输，使用端口 4在支持PDSC和 PMC混合传输的载波上，PMC不能再子帧0和5中传输下行物理层信号：对应于一系列物理层使用的RE这些RE不传递任何来自高层信息注：物理信号都由ZC序列生成，每一

15、个子载波占用一个ZC序列的符号。SSS PS同步信号内容固定，重复发送，不承载任何上层信息，是UE在进行小区搜索时第一个要找的信息。UES行盲检搜索同步信号，目前只支持Normal CP的格式。2.7 PSS: Primary Synchronization Signal（主同步信号）-频域上占系统带宽中间的6个RB,即72sc-在第 2个subframe 的第 3个symbol 中进行传递（subframe 1 or 6, symbol 2）-指示一个物理小区组内的id : Physical-layer id : 0, 1,2 （3个）2.8 SSS: Secondary Synchroni

16、zation Signal（辅同步信号）-频域上占系统带宽中间的6个RB,即72sc-在第1个subframe的最后1个symbol中进行传递（subframe 0 or 5, symbol 6 ）在subframe 0和5中的SSS结构相 同，但是在频域上错开，以区别前5ms或后5ms的半帧。-指示物理小区组号：Physical-layer cell-id group: 0167 （ 168个）-Total cell IDs: 168 x 3 = 504 cell IDs. （0503）RS: Referenee Signal（参考信号）（every slot, symbol 0&4）用于下

17、行信道估计，信道质量测量以及相关解调，对UE来说是已知信号（RS信号与小区physical id有关，这个在小区搜索过程中的同步信号中获得）频域上：每6个子载波分配一个 RS时域上：每个slot的symbol 0&4 用来传递RS, symbol 0和4之间有3个SC勺间差，用于时频域分集。多天线传输情况下，天线端口集合与参考信号配置之间的关系：Cell-specific RS, non-MBSFN transmission =P = 0 ,0,1 , or 0,1,2,3MBSFN RS, associated with MBSFN tran smissio n =P = 4UE-speci

18、fic RS. = P = 5 （用于 BF技术）UL: PUSCH/PUCCH/PRACHRS/DMRS3. 上行物理信道及物理信号的功能和占用时频码域位置（PRACH slotDuration( e,g. 1ms)PUSCH Physical Uplink Shared Channel(物理上行共享信道)Carries the user data from UL-SCH.Carries L1/L2 control in formation: ACK/NACK, CQI, PMI, RI (Ra nk In dicator)PUCCH Physical Uplink Control Chan

19、nel(物理上行控制信道)PUCCI承载上行控制信息(UCI)，不与PUSC同时传输，处于上行带宽的边缘，在TD冲不在UpPT域上传输UCI信息包括以下4部分：Scheduli ng Request (SR). CQI and Scheduli ng Requests are provided to Layer 2.HARQ ACK/NACK for DL tra nsmissio n;CQI reports.PMI reports.-PUCCI具有6种格式，1系列承载SR和ACK/NAC信息，2系列承载CQI/PMI信息，如下图所示：PUCCH formatModulationschemeN

20、umber of bits per !subframe, M bitType of information1N/AN/AScheduling Request (SR)1aBPSK1ACK/ NACK1bQPSK2ACK/ NACK2QPSK20CQI/PMI/RI2aQPSK+BPSK21CQI/PMI + 1 bit ACK/ NACK2bQPSK+QPSK22CQI/PMI + 2 bits ACK/ NACK3.1 PRACH Physical Ra ndom Access Cha nnel(物理随机接入信道)-Carries the random access preamble.PRA

21、CH Preamble:-频域：6 RB x 180kHz = MHz-时域：1ms / 2ms / 2 symbols ( UpPTS64个可-随机接入前导由具有零相关区的ZC (Zadoff-Chu )序列产生，有一个或多个根ZC序列产生。每个小区中包含用的前导。-PRAC共有5种结构(04),目前支持 Format 0, 1 & 4:PRACH Formats and cell rangesCELL RANGEFormat 0Preamble-14 Km1 ms-2 msFormat 11600 psFormat 2CPPreamblePreamble-77 Km29 Km3 ms71F

22、ormat 3F CPPreamblePreamble684 ygFormat 4洎SJEmens Nel worksorTDD only, in Up PTS100 KmRACH-FDD!要额外配置一个 GP( Guard Period )以适应RTD( Round Trip Delay )，在TDD勺特殊帧中已包含这个 GP-FD匪一个子帧中只能分配一个RACH源，而TDD可以分配多于一个的随机接入资源-TD嗾式下，在UpPT沖，可以调度Short RACH ( S-RACH，与GF结合使用，最多可配置 6个RACHDwPTSGPUpPTS11RACK allocationGPRACH 0

23、RACH 1RACH 5UpPTS = 2 symbolsDwPTS Downlink Pilot time SlotUpPSS： UplinK Pilot Ume SIOCMax 6 RACH cha nrwlsNetwcvlu随机接入过程:-基于竞争的随机接入过程：如 UE初始接入上行物理层信号：指物理层使用的但是不承载任何来自高层信息的信号，如参考信号。3.2 DRS/DMRS Demodulation Referenee Signal（解调用参考信号）-与上行数据传输有关，both PUSCH and PUCCH。-用于信道评估，对 PUSC和 PUCC信道的连续检测和解调，上行功率控

24、制，时间评估等 -DR在时域上的分配：o PUSCH:每个 slot 的第 4th 个symbol （ symbol 3 in every slot ） oPUCCH: DR由 PUCC的格式来决定（1/1a/1b 或者 2/2a/2b ）-DR在频域上的分配：o PUSCH: DR与终端的上行传输具有同样的带宽。o PUCCH:如下图所示ACKACKDRSDRSDRSACKACKACKACKDRSDRSDRSACKACKCQIDRSCQICQICQIDRSCQICQIDRSCQICQICQIDRSCQIa123456 0 12 -3456ACK=AcknowledgmentkSymbol n

25、umber (normal CPCQI =Channel Quality IndicatorDRS=Demoduhtion Reference SignalNohld Menwn3.3 SRS Sounding Referenee Signal(探测用参考信号)= 与 PUSC和 PUCC无关与上行数据传输无关，可用于评估上行信道质量，实现以下功能：初始化 MCS( Modulation and Coding Scheme )选择数据传输的功率控制TA( Timing Advanee )UL频率的独立调度(Freque ncy depe nde nt seheduli ng for the U

26、L)SRS tran smitted in the last SC-FDMA symbol in the eon figured subframes.在TDD莫式中，UpPT竝可用作传递SRS4. 逻辑信道、传输信道与物理信道的映射关系:4.1逻辑信道（7）soxRLCLogical channelsDPCCHurSCHAir interfaceNMild 5WTwni wwmu；5. MIMO tech nology-Two kinds of MIMO tech ni ques forDL tran smissi onthe same in formati onstreammultiple

27、in formatio nstreamso Transmit diversity use multiple channels to send Improve coverage and robust ness of data tra nsmissi on o Spatial multiplexing- use multiple channels to sendIn crease throughput SU-MIMO/ MU-MIMO6. PDSC下行资源分配方式(TypeO/1/2 );Type 0: PDCCH DCI formats 1,2 and 2ARBs are grouped to

28、RBG. RBGs are selected.RBG Size ( P)System Ban dwidth (Number of DL RBs) w 1011 - - 2627 - 6463 10MHz - 50 RBs)64 - 110 .: 20MHz - 100 RBs)Type 1: PDCCH DCI formats 1,2 and 2ARBs are grouped to RBG subset. First select one RBG subset, the n select the RBs in the RBG subset. RBG subset的值(P)与Type0中RBG

29、勺定义一致。-氐r P-1Log2(P)RBG subsets :RB assig nmentType 2: PDCCH with DCI format 1A, 1B, 1C and 1D Start RB and width is assigned.7. DCI FormatDCI: Dow nli nk Con trol In formation (ref. = Carriered by PDCCH一个DCI传递上下行调度信息，或者针对一个RNTI的上行功率控制命令DCI FormatUse scopeDCI 0zor the schedul ing of PUSCH(For Upli n

30、k only)DCI 1zor the schedul ing of one PDSCH codeword,TM1,2 and 7 (Type0, 1)DCI 1Azor the compact scheduli ng of one PDSCH codeword and ran dom access procedure in itiated by a PDCCH order, TM17 (Type 2)DCI 1Czor very compact scheduli ng of one PDSCH codeword(Type 2)DCI 2zor MIMO .: CL MIMO),TM4 (Ty

31、pe0, 1)zor the scheduli ng of on e/two PDSCH codewordTPC comma nd for PUCCHDCI 2Azor MIMO .: OL MIMO),TM3 (Type0, 1)zor the scheduli ng of on e/two PDSCH codeword TPC comma nd for PUCCHFormat 0: 用于上行传输，PUSCI的调度Flag for formatO/format1A differe ntiati on - 1 bit,0=format 0 and 1=format 1AResource blo

32、ck assig nment and hop ing resource allocati onModulati on and cod ing schemeHARQ in formati on and redu ndancy vers ionTPC comma nd for scheduledPUSCH - 2 bitsCQI request 1bitFormat 1:用于传输分集，单码字PDSC的调度(Used for the scheduling of single codeword PDSCH)(TM1,2, and 7-not support)Resource allocati on t

33、ype, .: type 0 / type 1 1bitResource block assig nmentModulati on and cod ing scheme 5 bitsHARQ process number - 4 bitsTPC comma nd for PUCCH - 2 bitsFormat 1A:用于下行传输，单码字PDSC调度，下行数据触发随机接入过程，适用所有TM传输模式。= Compactscheduling of one PDSCH codeword and random access procedure initiated by a PDCCH order(为

34、UE分配0=format 0 and 1=format 1A一个非竞争随机接入的特定preamble).Flag for format0/format1A differentiation -1 bit,Resource block assig nmentModulati on and cod ing scheme 5 bitsHARQ in formation 4 bitsTPC comma nd for PUCCH - 2 bitsFormat 1B: Compact scheduli ng of one PDSCH codeword with precod ing in formatio

35、n. Closed loop precoding with rank-1 transmission. （TM6,目前不支持，不需要掌握）Format 1C: Very compact schedulingof single codeword PDSCH. （Paging, SIB, 系统广播信息 ）Resource block assig nmentModulati on and cod ing schemeRedu ndancy versi onFormat 1D: Compact scheduli ng of one PDSCH codeword with precodi ng and p

36、ower offset in formatio n. （using Multi-user MIMO, TM5,目前不支持）Format 2: For MIMO （Closed-Loop），两码字，下行 PDSC调度（闭环模式，TM4需要上报PMI信息）Format 2A: For MIMO （Ope n-Loop），两码字，下行 PDSC 调度（开环模式， TM3Format 3/3A: Tran smissio n of TPC comma nds for PUCCH and PUSCH with 2-bit or 1-bit power adjustme nts8. LTE相关接口的控制面

37、和用户面协议栈Radio in terfaceControl Pla ne:User Pla ne:PHY: L1 协议，Data Tran sfer via Tran sport Chann els. Error Detecti on. Hybrid ARQ Combi ning.Channel Coding and Rate Match ing. Modulati on and Demodulati on. Measureme nts.（发送分集），Beamformi ng （波速成型）MIMO（多进多岀），Tran smit Diversity RF Process ing.（确认模式）

38、数据传输UE测量上报和控制功能等功能S1 in terfacesUser Pla ne (eNB-S-GW):X2 in terfacesData Tran sfer via Logical Chann els.逻辑信道和传输信道之间的映射UE之间以及一个 UE在不同逻辑信道之间的资源分配和调度 传输格式选择HARC纠错功能RLC: L2协议，主要实现与 ARCO!关的功能，保证数据传输的可靠性上层PDU数据传输：TM （透明模式），UM （非确认模式），AM ARQ纠错功能（CRC检验由物理层完成）串联，分段及重分段功能顺序传送上层数据以及重复检测功能PDCP: L2协议，提供ROH（可靠头

39、压缩功能，以及加密和完整性保护功能RRC: L3协议，提供广播、寻呼、RRC连接管理、无线承载控制、移动性、NAS:非接入层控制协议，主要实现以下功能SAE承载管理鉴权LTE-IDLE状态下的移动性管理 产生LTE_IDLE状态下的寻呼消息 安全控制Control Pla ne (eNB-MME):S1-APUser pla ne PDUsX2-AP9. LTE相关流程9.1 Call Setup呼叫流程9.2 Cell Selection小区搜索过程9.3 Random Access随机接入过程-In itial access from RRC_IDLE;- RRC Conn ecti on

40、 Re-establishme nt procedure;- Han dover;- DL data arrival duri ng RRC_CONNECTED requiri ng ran dom access procedure;-.when UL synchronisation status is“non-synchronised ”；- UL data arrival duri ng RRC_CONNECTED requiri ng ran dom access procedure;-.whe n UL syn chro ni sati on status is non-syn chr

41、 oni sed or there are no PUCCH resources for SRavailable.Contention based (applicable to all five events): Non-contention based (Handover & DUEeNBRandom Access Preamble毛Random Access ResponseScheduled Transmission-Cca+an+icai+icaVyUI IUI ILIVI 1 1 JOkJIULIUI 1UEeNBRA Preamble assignmentRandom Access

42、 PreambleRandom Access Response9.4 RRC conn ection establish procedure RRC连接建立过程-SRB: Signalling Radio Bearer(Transmission of RRC&NAS messages.)o SRB0: for RRCnsg, using CCCHo SRB1: for RRC& NAS(before SRB2 established) msg, usingDCCHo SRB2: for NASmsg, usingDCCHConfigured after security activation

43、together with DRB.-DRB: Data Radio Bearer(Transmission of user data)RRC Co nn ection Setup (SRB0,1) & recon figuratio n (SRB2, DRB)UEeNBMMEUL-SCH RLC TM SRB0 RRC-ConnectionRequestUL-SCH RLC AM SRB1DL-SCH RLC TM SRB0 RRC-ConnectionSetupRRCCo nn ectio nSetupCompleteNAS(EMM Attach Request (ESM PDN CONN

44、ECTIVITY REQUEST)S1AP: INITIAL UE MESSAGENAS (EMM Attach Request (ESM)1.0 Autentication and 2.0Security Mode ProceduresDL-SCH RLC AM SRB1S1AP: INITIAL CONTEXT SETUP REQUESTNAS (EMM Attach Accept (ESM)RRC-C onnection Rec on figuratio nNAS (EMM Attach Accept (ESM ACTIVATE DEFAULT EPS BEARER CONTEXT RE

45、QUEST)UL-SCH RLC AM SRB1 RRC-ConnectionReconfiguratio nCompleteS1AP: INITIAL CONTEXT SETUP RESPONSEerNAS (EMM Attach Complete (ESM ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT)UL-SCH RLC AM SRB2 RRC UplinklnformationTraflgS1AP: UPLINK NAS TRANSPORT NAS (EMM Attach Complete (ESM)IP uplink and downlink traffic料比也注SKnncns!Neiwwks.Only for internal usage 8? Nokia Siemens NetworksWBTS Architecture / 9/14/2010OFDM/和 SCFDMA勺区另V：- OFDMA tra