2017624 LTE0 More Next Blog» Create Blog Sign In LTE Monday, 23 November 2015 About Me varadamohan reddy Carrier Aggregation: Follow 7 View my complete profile 1. Many operators want to push for higher data rates but don’t have contiguous 20MHz spectrum So CA solve that problem. 2. CA allows to aggregate data rates per UE using multiple carriers 3. Major operator for CA are AT&T, Spirent, VzW. Blog Archive 4. Provide for contiguous and noncontiguous spectrum aggregation 5. Supports asymmetric bandwidths, means different number of component carriers (CCs) of ▼ 2015 (1) possibly different UL and DL bandwidths ▼ November (1) 6. Support of heterogeneous networks, means Layer of highpower Macro cells and layer of low Carrier Aggregation: 1. Many operators power small cells. want to p... 7. CA effects MAC and Phy but not RLC, PDCP, RRC and higher layers. 8. CA is applied to device in connected mode only, it is not applicable to device in Idle mode. 9. Only CCs that belong to the same eNodeB may be aggregated, and they are assumed to be synchronized. 10. For potential UE power saving, UE does not receive data, nor monitor PDCCH, nor sends CQI feedback for deactivated SCell. 11. Default linkage between DL CC and UL CC composing a serving cell is signaled in System Information Block 2 (SIB2) on each DL CC 12. A UE's identity (CRNTI) is the same in the PCell and all its configured SCells Cross Carrier Control: It means control channel belongs to one CC can schedule control info for other CC, It works with the help new 3bit CIF(Carier Indicator Field) inserted at the begining of PDCCH message. The presence or absence of CIF on each CC is configured semi statically for each UE. via RRC signaling. CIF is configured as UE specific(Not for all UEs in the cell). Cross carier Scheduling: Cross carrier scheduling info is send in, PhysicalConfigDedicatedSCell crossCarrierSchedulingConfig SchedulingCellInfo {Own, Other} (Own means No CCS, and Other means CCS is present) schedulingCellId {Informs about the ServingCellIndex} PDSCH Start > As we know if CCS in SCell is enabled, then UE won't decode PCFICH hence no PDCCH symbols, so eNB gives the starting of PDSCH info. > Its value ranges from 1, 2, 3, 4. > 1, 2, 3 when DLBW is greater than 10 PRBs. > 2, 3, 4 when DLBW is less that or equal to 10 PRBs. Common search space is always on the primary cell, But UE specific search space is may be in Primary/secondary cell. SCELL Deact / Act: In addition to the DRX, some additional power saving techniques also used, which are Scell Act/ Deact of individual Scell. For Deact Scell UE is not required to measure CQI. ACT/De ACT is done by using MAC CE, which has BITMAP of 8 Bit, on these 0..6 are varry and 7th bit is Reserved and equal to 0. MAX 15 ms allocated to UE for for configuration. MAX 8ms should be allocated for UE to ACT/DeACT. Measurement Events: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 1/43 2017624 LTE For Measuremnts events like A1 and A2, measuremant object or serving C consider as either PCell or SCell. For measurements events like A3, A5, B2 measurement object is consider as only PCell. A1 Ser > Thre (S+1) A2 Ser < Thre (S1) A3 Nei > Pcell+Hyst(N+1) A4 Nei > Thre (N+1) A5 PCell < Thre1 and Nei > Thre2 (N+1, S1) A6 Nei > Offset + SCell ( ) Measurement report triggering Event A1 (Serving becomes better than threshold) Either PCell or SCell on the frequency indicated in measObjectEUTRA. Event A2 (Serving becomes worse than threshold) Either PCell or SCell Event A3 (Neighbor becomes offset better than PCell) Only with respect to PCell Event A4 (Neighbor becomes better than threshold) No impact Event A5 (PCell becomes worse than threshold1 and neighbor becomes better than threshold2) With respect to PCell Event A6 (Neighbor becomes offset better than SCell) New optional event: with respect to SCell Event B1 (Inter RAT neighbor becomes better than threshold) No impact Event B2 (PCell becomes worse than threshold1 and inter RAT neighbor becomes better than threshold2) 13. RRC signals or configures the measurement time(time to send measurement report) for deactivated SCell By default its value is 320 ms. Random Access Procedure: A UE configured with CA can perform RA Procedure in UL only. Only one CA is ongoing at a time. 14. If Measurement event A6 is not supported then it won't support SCell replacement. 15. Multiple Cluster Allocation(UL CA) is not supporting when using 1 CC in UL. 16. Simultaneous PUCCH and PUSCH is not supports when using 1 CC in Ul. 17. RL Monitoring is only on PCell. 18. MAX 1.3 micro seconds time difference between cells, in addition to UE should be able to handle up to 30 micro seconds diff due to propagation delay. 19. CQI reports is there in SCell when SCell is in Activation state, Once Deact it won't send CQI reports. CA Effect on MAC : 1. Independent HARQ for each CC.: > One Transport Block is schedule for each HARQ entity in absense of Spatial Mux, and 2 Transport blocks is schedule for independent HARQ process, in of Spatial MUX. > 8 HARQ Ids per CC. Periodic HARQ feed back: PUCCH format 1b with Carrier selection It Supports only up to 2 CCs( with 4 ACK / NACK per subframe) PUCCH format 3 It is used to support to provide A/NACK up to 3 DL CCs. Aperiodic HARQ feed back: UE sends feed back on PUSCH, UE supports signaling for CC selection. UE this report on HARQ, Max num of ACK/NACK bits for increased to 6 for 3 DL CA(2 TBs for cell, so 3 cells > 3*2 =6 ). 2. Scheduling: Cross carrier Scheduling: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 2/43 2017624 LTE In 2 DL CC scenario, PCell PDCCH carries resource allocation for SCell also. Configured semi statically through RRC. Dynamic Scheduling: UL grants are given to PCell on every SF. In DL Per carrier scheduling is required if Cross carrier scheduling is not enabled. If CCS is used then, one PDCCH can control all CCs. Semi Persistant Scheduling: Only PCell can configured. Only PDCCH associated PCell can over ride an SPS resource allocation. 3. PDCCH decode: Number of BLIND DECODES increases as the number of CCs increases. For PCC, 44 decodes (12 common search space + 32 for UE Specific search space). For SCC1, 32 decodes, For SCCs only UE specific Search spaces are there. > Totally 108 Search spaces, with 74 for SCC's. Scheduling: Cross Carrier Scheduling on one PCC allows to schedule data on another CC. RACH: UE performs RACH when UL associated with PCell. UE performance RACH procedure when the TAG for the SCell is expired. On PCC UE receives SCCs PDCCH order, then UE sends preamble request in SCC and get Response in PCC. DRX: Same DRX is applied to all the cells, and Active time for PDCCH monitoring is identical across all cells. SPS: It is configured to only PCell and PDCCH of PCell can only over ride it. PHR: It is different when UL CA will support. ePHR is used in UL CA. BSR: Not affected for 1 UL CC. eBSR is used in UL CA. SRS Transmission No impact for 1 UL CC UE may signal the CA MIMO capability for the same band multiple times in different band combinations Periodic SRS transmission on all CCs support (FGI 113) TACMD: Different cells have diff TAdvance. So Cells with same TA are grouped and named as TAG(TAGroups) When TATimer associated with TAG is not running, UE does not performs any UL transmission on any SCell except RACH on PCell. MUltiple TAGs for CA: If PCEll and SCell belongs to diff TAGs, then UL transmission timing of each cell is adjusted individually. MAx 32.47 mico seconds delay difference TAG is configured by RRC signaling. No of TAGs configured is depende on the UE TAG capability. SCells TAG is configured by sTAGId, If not configured it takes pTAGId by default. CA Effect on RRC: > NAS and upper layers has no effect on CA. > RRC Idle mode has no effect. > RRC connected mode mobility, HO is possible for only PCell is CA is activated SCell is deact and HO Trigger and SCell is again added after successful HO. > SCell addition: Using RRCCONNECTIONRECONFIGURATION with or without MobilityControlInfo Receiving Dedicated SI(Other cell system information) when adding new SCell, Only necessary SI will carry about SCell in this message. > SCell Activation: ACT is done by MAC CE, after addition of SCell. SCell is Deact by MAC CE/after certain period of inactivity(time expiry)/ HO/ RLF(RRC_CONN_RESTA / Required SI about SCell is get to UE using Dedicated signaling. UE does not remove SCell during HO. > SCell Deact: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 3/43 2017624 LTE It is done by MAC CE/ RLF(RRCCONN_REESTAB)/RRC/sCellDeactivationTimer. sCellDeactivationTimer Restart the timer if there is UL / DL grants is scheduled. RRC Functions over CA: Enabling crosscarrier scheduling (semistatic) Optional – not supported Simultaneous PUCCH and PUSCH transmission Optional – not supported Configuring UE to use PUCCH format 1b with channel selection or format 3 for HARQ feedback. Changes in RRC IEs: CQIReportConfig, CrossCarrierSchedulingConfig, MACMainConfig, PRACHConfig, PhysicalConfigDedicated, RadioResourceConfigCommon, RadioResourceConfigDedicated, UplinkPowerControl PUSCHConfig, SoundingRSULConfig do not change for 1 UL CC Mobility Control IEs: ServCellIndex, SCellIndex, Internode RRC Messages EUTRAInterNodeDefinitions CA BULLETS: 1. Transmission modes on different CCs are independent. 2. Same UE identity(CRNTI) is used across all the CC. 3. HARQ processors are independent. 4. CSI reports are independent(Diff ) for diff CC. Both Aperiodic/Periodic CSI reporting modes are present. 5. Periodic SRS transmission on all CCs support (FGI 113). 6. When more than one serving cell is configured (CA), one value of cqiMask applies for all serving cells (the associated functionality is common i.e. not performed independently for each cell). CA Bullets: RRC Level: What are the parameters(IEs) that indicate about CA. > In UE_Capability_information message UE send its supported, 1. Band class IEs: >caBandwidthClassUL >CABandwidthClassDL a, b, c, d, e, f a: No.of Resource Blocks to aggrigate is < 100 Max No.of supported CCs > 1. b: No.of Resource Blocks to aggrigate is < 100 Max No.of supported CCs > 2. c: No.of Resource Blocks to aggrigate is in Between 100 to 200. Max No.of supported CCs > 2. d: No.of Resource Blocks to aggrigate is in Between 200 to 300 Max No.of supported CCs > Not defined. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 4/43 2017624 LTE e: No.of Resource Blocks to aggrigate is in Between 300 to 400 Max No.of supported CCs > Not defined. f: No.of Resource Blocks to aggrigate is in Between 400 to 500 Max No.of supported CCs > Not defined. 2. MIMO Supported Capability. supportedMIMOCapability for both UL and DL MIMOCapabilityUl {Two layer, Four layer} MIMOCapabilityDL {Two layer, Four layer, Eight layer} 3. Supported Band Combination: On BandEUTRAr10 IE. NOTE: For each supported BandCombination, independent Supported MIMO Capabilities for UL/ DL and Band_class_supported in UL/DL is distributed. > nonCriticalExtention: 111 Measurement report A6. 112 Scell addition on HO to EUTRA. This bit set only if UE supports CA. 113 It will set only if UE supports UL CA. It Triggers Type 0 SRS transmission(Periodic SRS) on X serving cells. Where, X Number of UL Supported CC. > How SCell is Deactivated: In rrcConnectionReconfiguration radioResourceConfigDedicated Mac main config SCell Deact timer is configured. SCell Deactivation is done if UE doesn't receive any resource with in the configured time. What are the SCell Configuration is send in rrcConnectionReconfiguration to add SCell ? sCelltoAddMod List sCell Index Used to identify the resource assigned are for PCell/Scell. Cell Identification PCI DL carrier Carrier freq / EARFCN RadioResourceConfigCommonScell DL bandwidth antena info common phich duration and resource (It comes in MIB for PCell). PDSCH config RS Power RadioResourceConfigDedicatedScell PhyConfigDedicatedScell AntenaInfo Transmission Mode UE transmit antena selection setup Openloop PDSCH configDedicated UL Configuration CQI reportConfigSCell CQI reportModeAperiodic CA Possibilities: 1. CCs are On the Same Frequency Band or Different Bands Close to Each Other Note: 1. Cross carrier scheduling is introduced in Rel11. 2. Each CC has independent HARQ. 3. Neighbour measurements in connected and idle are independent for each CC, PCell or SCell measurement is identified by using Serving_Cell_Index. 4. In RLM BLER and SNR are calculated only on PCell. 5. PCFICH is independent for both, i.e both PCell and SCell have PCFICH. 6. UE decodes PDCCH on both PCC and SCC if SCScheduling is not configured, PCC and SCC is identified by using Carrier index. 7. PDSCH decoding result is different for different CC. 8. Rx AGC is different for different CC. It is used to calculate Broadband RSSI, Inband RSSI, Measured Total RSSI. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 5/43 2017624 LTE 9. MAC CE for CA to activate code is > 3B 02 with LCID=27, it has a SCell index of 8 Bits in length among this last 7 Bit is reserved so 8th bit = 1. If SCell index is set to i then SCell index with i value is activated. 10. Transport Block size is different for diff CC. 11. The term Serving Cell can refer to either a PCell or an SCell. 12. The same frame structure is used in all aggregated serving cells. 13. Only PCell HO is possible, SCell HO is not possible. SCell is Released in HO of PCell. 14. CA is also used to Reduce Cell Edge Effect.(i.e when UE is at cell edge with PCell, then eNB schedules more grants in SCell.) 15. SCELL_TO_ADD_MODE_LIST: IEs are, sCellIndexr10 1, cellIdentificationr10 { physCellIdr10 116, dlCarrierFreqr10 3098 } radioResourceConfigCommonSCellr10 dlBandwidthr10 n100, antennaInfoCommonr10 { antennaPortsCount an2 }, phichConfigr10 { phichDuration normal, phichResource oneSixth }, pdschConfigCommonr10 { referenceSignalPower 0, pb 1 } }, ulConfigurationr10 { ulFreqInfor10 { ulCarrierFreqr10 21098, ulBandwidthr10 n100, additionalSpectrumEmissionSCellr10 1 }, uplinkPowerControlCommonSCellr10 { p0NominalPUSCHr10 99, alphar10 al09 }, soundingRSULConfigCommonr10 release : NULL, ulCyclicPrefixLengthr10 len1, puschConfigCommonr10 { puschConfigBasic { nSB 1, hoppingMode interSubFrame, puschHoppingOffset 0, enable64QAM FALSE }, ulReferenceSignalsPUSCH { groupHoppingEnabled FALSE, groupAssignmentPUSCH 0, sequenceHoppingEnabled FALSE, cyclicShift 0 } CSI Feed back: Periodic CSI Feed back: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 6/43 2017624 LTE Periodic CSI report for DL CC is independent, each CC has diff CSI report. It will transmit on PUCCH or piggy backed on PUSCH. Aperiodic Feed back: UE perform Aperiodic CSI reports using PUSCH in subframe n+k if it detects UL DCI format or Random access resp grants for serving cell. It will trigger if the respective CSI field is requested to set to trigger a report. CSI request field value, 00 No Aperiodic reports is triggered. 01 Aperiodic reports is trigger for serving cell. 10 Aperiodic reports is trigger for 1 set of Serving cells config by upper layers. 11 Aperiodic reports is trigger for 2 set of Serving cells config by upper layers. Periodic CSI Feedback on PUCCH: Periodic CSI reporting for each DL CC is independently configured Periodic CSI is reported for only one DL carrier in one subframe When DL CC is determined according to a priority, if the reporting type is the same for multiple serving cells, the cell with smallest value of ServCellIndex has the highest priority. Drop the reports of lower priority CSI Feedback on PUSCH: UE power on procedure: 1. UE switch on 2. Frequency scan 1. LFS or System Scan Upperlayers provide list of EARFCN and requested bandwidth, Duplex mode to L1 2. FFS or Band Scan Upperlayer provide Band index, set of band widths to L1. On scanning L1 gets, 1. Fc, 2. Bandwidth 3. Energy estimation UE Scan all RF channels in the EUTRA band, and reports available PLMNs to NAS only if below condition satisfies. The measured RSRP value should be > 110 dBm 3. PSS 1. Cell id Index or sector id (0,1,2) 2. SF timing > twice per 10ms radio frame(sf0 and sf5 on slot 0 and 10 in last symbol) or time synchronization 3. PSS repeats every 5ms. Measures the all the available Cell idex 0 1 and 2 and compare this with threshold, and selects the best cell index. 4. SSS 1. Cell id group(0..167) 2. FDD/TDD detection 3. SFN detection or frame synchronization 4. CP length > NCP or ECP 5. Twice for radio frame last but 1 of PSS. 6. SSS1 on slot 0(before PSS or last but one to PSS) and SSS2 on slot 10 in last but one symbol and repeats every 10ms(SSS1(on 0th slot) and SSS2(on 10th slot)). 7. Based on PSS and SSS UE detects PCI, PCI = (3*SSS+PSS). It have 0..503 identities. PSS and SSS will totally occupy 0.96 Mhz frequency and PBCH occupy 1.08 MhZ frequency. 5. Cell specific RS > On detection of PCI, UE's responsibility is to read RS. > RS is used to estimate PBCH. 6. PBCH It have MIB info, First 4 symbols in subframe 0 and slot 1 of every radio frame. MIB's periodicity is 40ms and repeats in each RFrame at 10ms, If 1 attempt is failed then tries to decode in 2 attempt, max retry atempts are only 2(320ms), if still fails then added cell to black list. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 7/43 2017624 LTE > 1. Phich info (resource and Config) 2. SFNumber 3. DL bandwidth 4. Antenna information It present in slot0 on 4, 5, 8, 9 symbols in NCP. in slot0 on 4, 7, 8, 9 symbols in ECP. Initial ACQ is completed Cell selection is triggered in the following scenarios: Service Request from NAS State transition (connected to Idle with redirection) Interfrequency redirection (from CEP) Out of Service (OoS) indication from ML1 (Idle mode) Radio link failure (Connected mode) InterRAT reselection/redirection to LTE (from WCDMA, GSM, 1X) RACH Procedure: Rach procedure could be triggered due to one of the following reason, 1. Initial Access. 2. UL Data available in Out of sync scenario(i.e in connected mode Time alignment timer expiry and UE has UL data to transfer). 3. HO. 4. DL data available. 5. RLF. RACH procedure types: 1. Contention based (When UE initiated) 2. Non contention based(eNB initiated this procedure). > applicable in HO and DL data arrivial. 1. Contention based RACH procedure: MSG1: RANDOM ACCESS PREAMBLE It has, Preamble Index PRACH Mask Index It is selected by UE MAC in contention based. Location of RACH and time domain resource is came to know by the UE is by using SIB2. UE sends RACH preamble carring RARNTI eNB gets the preamble and decode RARNTI. RARNTI = 1+t_id + 10*f_id RARNTI decides the sending sub frame number. Where t_id (0 <≤ t_id <10) = PRACH Preamble transmission timing or Index of the first subframe of the specified PRACH. f_id (0≤ f_id< 6) = Location of PRACH transmission in frequency domain. or Index of the specified PRACH within that subframe For FDD f_id is zero(=0). The end of RACH preamble and RACH Response is only 12 subframes (12 ms) RAPreamble Information : 1. Preamble Index. 2. SF 3. Preamble counter 4. Frequency index(by default it is zero). 5. Preamble Format (0 .. 4) 6. Timing off set 7. RB Start http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 8/43 2017624 LTE MSG2: RANDOM ACCESS RESPONSE This message is adderssed to RARNTI and contains 1. TCRNTI. 2. TA CMD. 3. UL grants. RAResponse Information : 1. RAP Id (6 bits) > It is same as Preamble Index. 2. TA CMD (12 bits) 3. UL Grants(20 Bits) Where UL grants are: 1. Hopping flag (1 bit) 2. Fixed size resource allocation(10 Bits) It has RIV: Resource Indication Value. It is present for only UL resource allocation. Resource Allocation Type2 is used for UL Resource allocation. RIV: It came to know 1. The Num of Contineously allocated Resource Blocks(CRB). 2. rb_Start. 3. MCS and Coding schemes(4 Bits) 4. TPC Cmd for scheduling PUSCH(3 Bits). 5. UL Delay (1 Bit) 6. CQI Request (1 Bit) (APeriodic report triggering) 4. TCRNTI (20 Bits) MSG3: RRCConnection request: It is 48 Bits in length. HARQ process starts from this message. MSG3 Information: 1. UE identity > 1. Random value (40 Bits) or 2. STMSI => MMEGI + MTMSI 2. Establishment Cause > MO Signaling. Other Estd causes are, 1. MO Signaling > 1. Attach 2. Detach 3. TA Update 2. MO Data 1. Service Request (User plane radio resource request) (UL Signaling Resou Req) 2. Extended Service Request(MO CSFB Call) 3. MT Access 1. Service Request (Paging Response for PS Core network) 4. High priority Access 2. Extended Service Request (MT CSFB Call Request) 5. Emergency Support 3. Extended Service Request (MO CSFB ECALL) HARQ ACK: As the HARQ process basically starts from MSG3. So eNB sends the HARQ ACK about the MSG3 reception to UE through PHICH. DCI Format 1A INFO: As you know in LTE Resource scheduling is done in SF basis which is by SF to SF wise. So by using DCI format 1A DL resource is scheduled. > DCI format 1a It has Info as, 1. Format type 2. D VRB flag 3. MCS 4. HARQ Process Number 5. NDI(True) =1 6. RV = 0 7. TPC for PUCCH =1 MSG4: RRCConnection Setup: MSG4 carries Random value which comes in MSG3. MSG4 Information: It has Mainly, UE CONTENTION RESOLUTIONN IDENTITY(48 Bits) This contention resolution message is equal to RLCCCCH message which comes in RRC_Connection_Request RRC LEVEL CONFIG: 1. RAdio Resource Config Dedicated http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 9/43 2017624 LTE 1. SRBtoADDmod list 2. DRBtoADDmod list 3. DRBtoREL list 4. MACmain Config SPS Config 5. PhyConfigDedicated. 2. Physical Config Dedicated. ULHARQ: By using PUCCH UL Ack is send by using PUCCH Format 1A. Scheduling Request (By Using PUCCH UCI) As there is no Ul resource hence UE again asks UL resource by using SR. PDCCHDCIFormat 0: eNB schedules UL resource by this message. ULResource are: 1. Format type 2. RIV Which means 1. Number of RBs and 2. Resource Blocks start time 3. MCS 4. RV 5. TPC 6. NDI 7. Cyclic Shift for DMRS 8. CQI Request = 0 RRC_Connection_Setup complete: As this message is large message, hence this message can transfers data in the form of chunks which transfer in different SubFrames(SFs). Each may have different layer messages like, first chunk has, MAC, RLC PDCP data. second Chunk also have, MAC, RLC, PDCP data. Each chunk will transmit in different SFN and SF For Ex: 1 chunk will transfer in SFN =402 and SF=2. then, 2 chunk will transfer in SFN = 402 and SF=3. In some chunks it is possible to send PUSCH and PUCCH data. It has mainly, MAC Level Info: 1. PHR report 2. BSR RRC Level Info: 1. Selected PLMN. 2. Registered MME > PLMN id + MMEGI + MMEC 3. Dedicated Info NAS It has: 1. Attach Request: It has, Type of attach : 1. Type of Attach It has 1. Combined EPS + IMSI Attach. This type is mainly for CSFB conditions to 3GPP RATs. 2. EPS Only This type of attach is for 1. 1xCSFB 2. While Registering for IMS. 3. SRLTE. 3. EPS Mobile Identity. Id_Type: GUTI or others 4. UE Network Capability 5. Old Location Id 6. Tracking Area Id 2. PDN Connectivity Request It has mainly, 1. PDN type > IPV4/IPV6 or combined(Both) 2. Request Type > Initial request 3. Primary and secondary DNS Server address 4. Voice domain preference Mainly: 1. ESM Information PDN connectivity request http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 10/43 2017624 LTE 2. EPS mobile identity IMSI or GUTI 3. UE network capability. All UE supported RATs info 4. DRX parameters. CN DRX cycle. Non DRX timer 5. TMSI Status Does any TMSI available 6. Voice domain preference. UE usage settings Data centric or Voice centric CS/IMS PS voice prefered. 7. NAS EMM Message Type of attach Type of security context flag NAS Key set identifier Types of RACH Procedures with RRC Messages: Contention Based: 1. During Initial Access: As Discusses above 2. During Handover: Here UE is in RRC connected hence it has CRNTI. Here eNB won't assign any Dedicated Preamble to UE. In Random Access Response UE receives TCRNTI also but UE discards this and use C RNTI for contention Resolution. Here in Contention Based UE must and should transmit CRNTI to eNB. UE New eNB < RRC_Connection_Reconfiguration (Received from Old eNB) > RACH Preamble < RACH Response > CRNTI MAC CE < RRC_Connection_Reconfiguration_Complete + DCI Format 0 + CRNTI 3. RRC_CONNECTED Out of Sync on expiring n311 timer DL data arrival : Once the n311 timer expires then RLFailure occurs then UE moves to RRC_IDLE state then Contention Based RACH procedure triggers. UE eNB RRC_CONNECTED_STATE OUT_OF_SYNC < PDCCH Order(DCI 1a) > RACH Preamble < RACH Response > MAC CE CRNTI < RRC_Connection_Reestablishment + DCI format 0 + CRNTI. > RRC_Connection_Reconfiguration < RRC_Connection_Reconfiguration_Compplete. IN_SYNC Contention Free: 1. During Handover: UE New eNB < RRC_Connection_Reconfiguration (Received from Old eNB) > RACH Preamble < RACH Response > RRC_Connection_Reconfiguration_Complete + DCI Format 0. 2. Out of Sync on RRC connected before n311 timer expires when DL data arrival : http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 11/43 2017624 LTE UE eNB RRC_CONNECTED_STATE OUT_OF_SYNC < PDCCH Order(DCI 1a) > RACH Preamble < RACH Response > RRC_Connection_Reconfiguration < RRC_Connection_Reconfiguration_Compplete. IN_SYNC 3. Out of sync on RRC connected on DL data arrival. NOTE: Different cases in RACH / MSG1 Failures: 1. UE does not receive any RANDOM ACCESS RESPONSE message: In this case UE transmits MSG1 with increased power. 2. UE receives RANDOM ACCESS RESPONSE but with different Preamble(RAP ID): In this case UE reads the RAResponse and finds that it is not the one transmitted in MSG1(Preamble Index) and selects Backoff Indicator from RAResponse and choose the timer mentioned in the Backoff Indicator and on expiry of this timer UE again sends the MSG1. CELL RESELECTION: CELL Selection/Reselection is done in Idle mode only i.e in EMM REGISTERED + ECM_IDLE + RRC_IDLE. Where as while HandOver triggers in EMM REGISTERED + ECM_Connected + RRC_Connected state only. HO is network controlled, where as Cell Selection/Reselection is controlled by UE itself. There are two cases in Cell Selection/Reselection with and without tracking area. Cell Selection/Reselection with TAU: In this case UE performs Cell reselection to the TA which that cell is listed in that Tracking Area. Cell Selection/Reselection without TAU: In this case UE performs Cell reselection to the TA which that cell is not listed in that Tracking Area. Cell Selection Critiria: When ever UE comes in DRX active state, it measures the Qrxlevmeas and calculates the received signal level Srxlev of serving cell, to decide weather to stay in the present cell or to perform Cell reselection. When Cell Reselection can trigger, > If the received Signal level of serving cell(Srxlev) > S_IntraSearch then UE stays in serving cell. If not it trigger Reselection. > The required threshold value to trigger cell Reselection comes in SIB3 as S_IntraSearch as of Rel8 and S_IntraSearchP and S_IntraSearchQ as per Rel9. Cell Ranking Criteria: >UE measured each cell(Rs, Rn) and ranked them based on the measured signal strength of the serving cell (Qmeas,s) and neighbour cell (Qmeas,n). >The serving cell is ranked based on the hysteresis(PHyst), value stored in SIB3, while neighbour cell is ranked based on offset (qOffsetCell) which comes in SIB4. Cell Reselection Trigger: > Once Rank is calculated it checks weather Cell selection criteria is satisfied (Rn > Rs) or not. > Cell reselection is performed only when the criterion is satisfied for a certain period of time (tReselectionEUTRA) Release 8: Srxlev > SintraSearch Release 9: Srxlev > SintraSearchP and Squal > SintraSearchQ Srxlev = Qrxlevmeas Qrxlevmin PCompensation [dB] Squal = Qqualmeas – Qqualmin [dB] http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 12/43 2017624 LTE Cell selection: Release 8: Srxlev > 0 Release 9: Srxlev > 0 and Squal > 0 where, Srxlev = Qrxlevmeas Qrxlevmin PCompensation [dB] Squal = Qqualmeas – Qqualmin [dB] During Initial Cell Selection: During Initial Cell Selection a UE must choose, Cell Reception lev(Srxlev) > Qrxlevmin + Pcompensation criteria ]]] When selecting as a Serving cell. Atleast Srxlev must be greater than Qrxlevmin. In Rel9, In addition to Srxlev Squal is added as cell selection criteria. Where Qrxlevmin = RSRP, It only provides only strength of received signal. Qqualmeas = RSRQ, more accurate information for radio link quality because it indicates the signal to interference and noise ratio (SINR). SIMPLY, Cell selection criteria: Release 8: Srxlev > 0 Release 9: Srxlev > 0 and Squal > 0 HPLMN: where, Srxlev = Qrxlevmeas Qrxlevmin PCompensation [dB] Squal = Qqualmeas – Qqualmin [dB] VPLMN: Where, Srxlev = Qrxlevmeas [ Qrxlevmin + QrxlevminOffset ] PCompensation. Squal = Qualmeas [ Qqualmin + QualminOffset] PCompensation: max(PeMAXPowerclass, 0). Neighbour Selection criteria: Release 8: Srxlev ≤ SintraSearch Release 9: Srxlev ≤ SintraSearchP or Squal ≤ SintraSearchQ Cell Ranking Criteria: Serving CellRank: Rs = Qmeas,s + Qhyst Neighbor Cell (nonserving cell) Rank: Rn = Qmeas,n Qoffset Where Qhyst = Hysterious value for the serving cell. Qoffset = Offset between the serving and neighbour cell. It is defined by qOffsetCell in SIB4. Cell Reselection: Rn > Rs NOTE: > Measure Qrxlevmeas and calculates Srxlev and compare it with threshold(S_IntraSearch in SIB3). If Srxlev > S_IntraSearch then , No cell reselection triggers. > If Srxlev < S_IntraSearch then calcultes Rank(based on Qmeas,s and Qmeas,n) based on that RANK REselection triggers. > Serving Cell is ranked by using PHYSt(SIB3) and Neighbour Cell is ranked using q OffsetCell(SIB4). > Cell reselection is performed only when the criterion is satisfied for a certain period of time (t ReselectionEUTRA). CDRX: Connected Mode DRX Mainly used for 1. Power Saving. 2. Resource Saving. If DRX is configured then UE need not to send CSI report on PUCCH and SRS contineously. Hence eNB uses these resource to schedule to some other UEs. In Rel 8, no need to transmit CSI when DRX is not in ACTIVE. But if UL resource are http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 13/43 2017624 LTE available then it will send CSI report even in DRX sleep state also. In Rel 9, If CQIMASK is enabled then UE sends Periodic CSI reports in OnDuration Time only, even UE has UL GRANTS it won't send CSI report, when OnDuration Timing is not running. DRX Config info which comes from eNB is, LongDrxCycle ShortDrxCycle longDRXCycleStartOffset: Starting of the long DRX cycle. OndurationTimer UL/DL config for TDD drxRetransmissionTimer: Up on PDSCH decode failure, UE starts HARQ RTT timer(Round Trip Timer). It is about 8 ms to come any ack/nack for that harq process. Up on the expiry of this time UE wakes up and and again monitors for that NACK packet. DRX Inactivity timer SFs and SFN calculation: ShortDRXCycle: (SFN*10) + SF_num modulo (ShortDrxCycle) = (drxstartoffset) Modulo (ShortDrxCycle) LongDRXCycle: (SFN*10) +SF_num Modulo (LongDrxCycle) = DrxStartOffset DRX BULLETS: > CDRX is configured in rrcConnectionReconfiguration message. RadioResourceConfigDedicated MacMainConfig drxConfig setup. > If UE sends SR in DRX ACTIVE period then UE should contineously motinors the PDCCH untill it gets DCI0. > OnDurationTimer value should be less than LONG DRX CYCLE. > OFFSETVALUE should be less than DRXLONGCYCLE. > LONG DRX CYCLE > OnDurationTimer > LONG DRX CYCLE > OFFSETVALUE. > DRX Retransmit timer is for present for each DL HARQ process > Active time: Total duration that the UE is awake. IDLE MODE DRX: Paging Occasion(PO): In 1 SF where PDCCH will come. Paging Frame(PF): 1 Radio Frame in which one or more PO will present. When DRX is used UE monitors only one SFrame and one PRNTi per DRX cycle. DRX ranges from 32, 64, 128, 256 radio frames, it means once in 32/64/128/256 radio frames. Idle mode DRX configuration comes in, SIB:2 RadioResourceConfigCommonSIB: PCCH Configuration Default_paging_Cycle It ranges from 32/64/128/256 nB 4T, 2T, T, T/2, T/4, T/8, T/16, T/32 DRX: Similar to DRX in LTE, on HSPA CPC is used for power consumption and resource saving. CPC Contineous Packet Connectivity CPC Uses in UL and DL: In UL: New UL DPCCH slot format. UL DPCCH discontineous transmission. Implicit CQI reporting reduction. In DL: Discontineous reception at UE. HSSCCH less operation Modified HSSCCH for retransmission. DRX Bullets: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 14/43 2017624 LTE 1. Inactivity timer will start every time when a UE is scheduled 2. Restarted when a new scheduling is received 3. DRX may varry in UL and DL, In UL: Since UL retransmissions are Synchronous in time hence UE knows when it will receive the retransmission request. Hence UE will automatically awake at the reception time. In DL: DL retransmissions are asynchronous in time, hence timing relations are not possible. Hence UE should monitors the DL in a configurable time window. 4. DRX Inactivity timer starts only after UE receives data in PDCCH, once it receives data it starts DRX_Inactivity_Timer. 5. If onduration timer is running without any data then drxinactivity timer can't run. 6. DRX minimum active time is OnDurationTimer and maximum Active time is Infinity. HARQ RetransmissionTimer: If UE fails to decode PDSCH then HARQ RTT timer will start. On expiry of HARQ RTT then Retransmission timer will start(In DRX active). Still HARQ RTT timer is running, UE wakes up with retransmission timer and searches for DL data till timer expires. Once timer expires again it comes on Expiry of HARQ RTT timer. HARQ RTT timer runs still UE receives DATA in DLSCH. |<..................Long DRX Cycle..............................>| |______|_____|____________|______________________________________| 0 A 1 B C 0> Long DRX Cycle Start. 0 to 1> OnDurationTimer Timer will start(It comes in CDRX Configuration Ex: 6 or etc) While running OnDurationTimer, If UE decodes any data then Inactivity Timer will RUN. If Inactivity timer runs once then OnDurationTimer and Inactivity Timer will expire at a time. On expiry of Inactivity timer UE goes to sleep state from B to C. HARQ: It is a retransmission technique used in LTE to retransmit errored data. HARQ = ARQ + FEC(Coding) + SOFT COMBINING Soft combining Soft combining is divided in to 2 types: 1. Chase Combining Data packets which are not possible to decode are not discarded anymore. The received signal is stored in a 'buffer', and combined with next re transmission. In CC same data and same parity bits will send. 2. Incremental Redendency Increase the RV (Redundancy Value) (or Coding) Basically coding may varry from 0, 2, 3, 1. It requires larger Buffer size. Here it will use Diff symmetric data bits will use. Normally In LTE FDD 8 parallel HARQ processes are running, where as in TDD 16 HARQ processes are running. Which HARQ process to use comes in DCI format in PDCCH. HARQ process id in DCI format is 3 BITS. FEC: In LTE it uses 1/3 coding for all the transport channels. For only CFI it uses 1/16 coding. Different HARQ techniques in both UL and DL: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 15/43 2017624 LTE In UL synchronous + Non adaptive process will use. In DL asynchronous + Adaptive process will use. HARQ Feedback: HARQ process will send feedback in two ways. Periodically : Send Feedback in PUCCH. APeriodically: Send Feedback on PUSCH. REFERENCE SIGNALS: Two types of RS in LTE: 1. UL DMRS: It is used for eNB for the UL Channel Estimation to demodulate UL channels like PUSCH and PUCCH. Transmitted in the same band width as PUCCH or PUSCH. 2. UL SRS: It is used for the eNB for the Channel Estimation to support UL channel dependent to support Scheduling and Link Adaption. Based on the SRS report from UE, eNB schedules UL RESOURCE to UE via DCI format 0. Transmitted over the entire uplink cell bandwidth. SRS transmission is of two types: 1. Periodic SRS Transmission: Available from Rel8. 2. APeriodic SRS Transmission: Introduced in LTE release 10 PDCCH triggers this. Location and frequency of SRS transmission: Frequency Domain: Start RBs and Num of RBs used for SRS transmission is given by, SRS bandwidth configuration (SIB2) SRS Bandwidth (RRC Message) Time domain: SRS resource in resource in time domain is given by, SRSConfigIndex (RRC message) It gives, periodicity and subframe offset. Difference between DMRS and SRS: DMRS: 1. Transmission in the same frequency of PUCCH and PUSCH. 2. PUCCH: As RS transmitted over a single PRB hence UL DMRS should be 12. PUSCH: Length of RS should be a multiple of 12, As UL RAllocation is done in PRBs(1PRB =1 2SC). SRS: 1. Transmission in the entire UL cell bandwidth. 2. Used to estimate the UL channel quality at different frequencies. 3. Enables UL channel quality evaluation. 4. It mainly transmitted in areas where no user data is transmitted i.e, last symbol of every SF. 5. SRS bandidths are always a multiple of 4 RBs.UE is explicitly configured to use one of SRS bandwidth available in the cell. Difference between UL and DL RS: UL RS: UL RS are time Multiplexed, (Some symbols are dedicated for RS) In PUSCH, UL RS is transmitted in 4th symbol of each UL slot, i.e twice in 1 SF.(2 RS per each SF, 1 per 1 slot) http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 16/43 2017624 LTE Bandwidth of UL RS should be same as the bandwidth PUSCH and PUCCH. DL RS: DL RS are frequency multiplexed with other DL transmission. NOTE: 1. Multiple UEs within the same cell can transmit on the uplink using the same frequency resource with the help of Cyclic Shift. More info in SRS @ http://lteshare.blogspot.in/2013/12/SRSLTE.html DL RS: 1. Cell Specific RS 1. Transmitted in every DL SF and span the entire DL bandwidth. 2. Used for channel estimation for coherent demodulation of any DL transmission except when non codec based Beamforming is used. 3. Inserted in 1 and 3 last OFDMA symbol of each slot, with frequency domain spacing of SIX SFs. So 1 slot have 1 PRB=12 SC, thus we have 4 RSymbols 4. Estimation of channel: need to use multiple reference signals(interpolation/averaging). Like: 1. within certain RB 2. In freq domain, neighbor RB 3. Previously received in previous slot/subframe 2. UE Specific RS 1. Transmitted only in RBs assigned for DLSCH transmission to specific UE. 2. Mainly used for coherent demodulation of DLSCH it supports Non codec based BEamforming also. 3. MNSFN RS: 1. Used for coherent demodulation of signals transmitted by MBSFN. OFDMA: FDM In FDM all the signals are by default orthogonal to each other. they are like, __/```\/''\/''\__ 0 f 2f 3f Intigration of sin(2#f1t).sin(2#f2t)dt =0 But in OFDMA: __/''/\''/\''\ 0 f 2f 3f Hence bandwidth saving will occur. f1 = m*fs and f2 = n*fs Integration of 0 to Ts (sin(2#f1t).sin(2#f2t)dt = o if m!=0 and Ts if m=n) How to achieve Orthogonality? 1. Assume BPSK, 4 Sub carriers. 2. Data comes in Serial from Upper layers. 3. Convert serial data to parallel, by using first data to 1 sc and 2 data to 2 cc and 3 data to 3 cc and 4 data to 4 cc and again 5 data to 1 cc. 4. Convert them to Symbols using BPSK modulation. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 17/43 2017624 LTE 5. Then convert entire SC symbols(SC1..4) to produce a OFDMA wave form by using IDFT algorithm(Inverse Discreat Forier Transfer) 6. If different SCs with different modulation is added to single OFDMA wave form then peak to avg power ratio will increase. 7. Then add CP to reduce ISI/ICI it also makes orthogonal from 1 SC to other SC. CP: In this last symbol position is added to front position. CP is added to each and every OFDMA symbol. 8. Then tr Advantages of OFDMA: 1. Spectral efficient: Allows SC to overlap 2. Fexible bandwidth: SC can be added and removed dynamically. 3. With CP, ISI is reduced. 4. Diff users have Diff tones, so no Intra Cell Interference Disadvantages: 1. Higher sensitivity to frequency offset and phase noise . 2. High PAR ratio, leads expensive amplifier, increase equipment cost. Difference between SCFDMA vs OFDMA: SCFDMA: In SCFDMA each SC contains all transmitted symbols, i.e information related to all symbols is present. Here same modulation and coding technique is used on different SCs. PAR is less. OFDMA: Where as in OFDMA, each SC carries information related to one specific symbol, information related to specfic symbol is present. Diff mod and coding techniques used diff SC. PAR is more. Difference between Distributed and Localized modes: Distributed Mode: SubCariers are non contigeous. More immune to errors due to frequency diversity. Localized mode: SC are contineous. RS: reference signal. Pilot signal for synchronization. RSRP: reference signal received power. Measured power for selected cell. In idle mode, this is a single measurement; in connected mode, this is a running average. RSRQ: reference signal received quality. Designed as a combined metric that incorporates both signal strength and interference levels. RSSI: received signal strength indicator. Wide band signal power (as opposed to RS power for RSRP) RSRQ = Nrb(RSRP*RSSI) SIB: system information block, broadcast on PDSCH. SIB1: Cell access information + scheduling of further SIBs (PLMN list, SI periodicity, etc). SIB2: Access parameters and channel configuration (RACH config, UL carrier frequency, etc). SIB3: Cell reselection information (Qhyst, Sintrasearch, etc). SIB4: Intrafrequency cell reselection information (neighboring cell IDs, blacklisted cell IDs, etc). SIB5: Interfrequency cell reselecction information. Similar to SIB4, but includes interfrequency carrier info (DL carrier frequency, priority, etc). SIB6: parameters for reselecting to UTRAN. SIB7: parameters for reselecting to GERAN. SIB8: parameters for reselecting to CDMA2000. SIB9: Home eNB Id. SIB10: Primary ETWS SIB11: Secondary ETWS SIB12: CMAS http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 18/43 2017624 LTE SIB13: EMBMS. SON: self organized network, interchangeable with ANR. In connected mode, the UE reports the CGI of any cells it finds to the serving cell, so that the serving cell can tell the UE to handover to the new cell if necessary. SRS: sounding reference signal. Provide eNBs reference after RACH. SSS: secondary synchronization signal. In conjunction with PSS, uniquely identifies UE. Jordartskocksoppa Enables to decode Downlink Control Information (DCI) from hexadecimal in 0xB130 log packet (LTE LL1 PDCCH Decoding results) NoPussyfooting Tool to decode RRC messages from hexadecimal input for the 3GPP protocol family: WCDMA and LTE > RRC connection release It has 2 causes 1. loadBalancingTAUrequired 2. Other > Why in Counter Check Procedure only MSB bits are checked and not LSB ? It has 2 reasons, > { In all cases the bits appear ordered from MSB to LSB when read in the PDU } 1. In CounterCheck procedure eNB is verifying, that the UE and eNB are in sync with respect to the packet count; and there hasn’t been any packet insertion by an intruder. The least 7 bits aren’t sent by the eNB because a discrepancy of 128 packets can be tolerated (Or) Enb and UE are insync with the packet count, so LSB is not send. 2. The packet count is input to the encryption/integrity check functions. So, the eNB may not want to let out its exact count value to the UE. But eNB wants to send enough bytes (MSBs) to verify the count is in valid range (Or) Packet count is used to encrypt/integrity check. So enb can't send the exact full count value to UE. > RLF causes ? 1. i> On monitoring PDCCH if BLER > 10% with in 200ms then RLF indication(Qout sync) sends to Upper layers and starts n310 timer then upper layers starts T310 timer. ii> If the quality recovers back to higher i.e Qin=2 %, in 100ms it starts n311 and indicates QInsync to higher layers, hence T310 stops. 2. Integrity check failure. 3. Random access problems in connected state. 4. RLC max retransmassions are exceeded. 5. Handover failure(T304 expires). 6. RRCconnection Reconfiguration failure. 7. RLF due to max RACH transmissions. IMPT: If AS security has been completed before RLF then UE may enters to RRC connected once RL is successful. If AS Security has not been completed and RLF occured and UE recovers from that then UE moves to RRC Idle state. RRCConnection reestablishment has { cRNTI '00000000 00001110'B, physCellId 397, shortMACI '00000000 00000000‘B }, reestablishmentCause handoverFailure, } Measurement Information: RSRP > Avg power of RE that carry cell specific RS. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 19/43 2017624 LTE RSSI > Total received wide band power. 1. RSSI of the cell should normally be between 30 and 90 dBm. An RSSI below 90 dBm will be very close to the senistivity limit of the UE 2. SNR > High SNR is > 18dB Medium SNR is > 10 dB Low SNR is < 3dB 3. RSRP > Near Cell RSRP > 85 dBm Mid Cell RSRP 85 dBm < RSRP < 105 dBm Far Cell RSRP RSRP < 105 dBm 4. RSSI > less than 90 and 30 dbm. 4. PRACH_TX_Power = min{ Max_UE_TX_Power, (Power_Level + Pathloss_Estimate) } Power_Level = Preamble_Initial_Power (SIB 2) + (Number_of_Preambles – 1) * PowerRampingStep (SIB 2) Range of Preamble_Initial_Power is [120, 90] dBm // PRACH tramsmission Power : MIN(UEmax, PL+Preamble_tramsmission_power) // Where preamble_transmission_power = Initial_Rx_target_power(SIB2) + Preamble_Delta + (Preamble_count 1)*Ramping_Step(Normally 2db). OTA messages UE side: RRCConnectionRequest RRCConnectionSetup RRCConnectionSetupComplete > Attach Request + PDN connectivity Request DLInformationTransfer > Auth Reque ULInformationTransfer > Auth Respo DLInformationTransfer > SM cmd ULInformationTransfer > SM cmplte ESM Information request ESM ESM Information response Identity request EMM Identity response SecurityModecommand SecurityModecomplete UECapabilityEnquiry UECapabilityInformation RRCConnectionReconfiguration > Attach Response + Activate default EPS bearer context request RRCConnectionReconfigurationComplete ULInformationTransfer > > Attach complete + Activate default EPS bearer context accept Random Access: Guard Time = Round Trip delay time(RTD) RTD > additional power required for ue to transmit its premable sequence to eNB. Preamble sequence size(1ms/2ms/3ms) depends on preamble format(0/1/2/3). Preamble format 0 is 1ms. Preamble format 1 is 2ms Preamble format 2 is 2ms Preamble format 3 is 3ms Preamble transmission format is as follows, { CPPreamble_sequenceGT } Cell Radius calculation http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 20/43 2017624 LTE S= UT + (at^2)/2, But a =0. U> Speed T> Time we know, T= 3*10^8 m/s where as T=> Guard time = RTD, SF_size => GT + CP + SeqNo So, GT = SF_Size CP Seq_No Radius of Cell => S=UT/2 => U*GT/2 Hence, S=UT/2 => (3*10^8)*GT/2 On calculating these we get, Cell radius as, Format 0 ~14.5 Format 1 ~77 Format 3 ~30 Format 4 ~107 SRS Sounding Reference Signal SRS is a UL reference signal which is used to estimate the UL channel condition. USES: Based on SRS UL frequency is scheduled by eNB to a particular UE. eNB can also use SRS for the UE to UL time aligned with eNB,when PUCCH and PUSCH resource are not available. Types: In Rel8: Single SRS Periodic SRS In Rel10: Aperiodic SRS Rel: 8 SRS are called "Trigger type0 ", and is configured and controlled by RRC. Rel: 10 SRS are called "Trigger type1" and is configured by RRC and controlled by DCI formats. Ue Specific SRS transmission SRS configurations : SRS_UL_config_common : SRS_Bandwidthconfig SRS_Subframe_config ackNack_SRS_simulataneousTransmission SRS_MaxUpPts SRS_UL_config_Dedicated srs_bandwidth SRS_hopping_bandwidth freq_Domain_position Duration Srs_config_index Transmission_Comb Cyclicshift The parameter duration in the UE specific SRS configuration informs the UE whether single or periodic SRS transmission to be used. If SRS parameter duration False > then Single SRS is triggered. If SRS parameter duration True > then Periodic SRS is triggered > periodically it transmits PSRS unless it is disable. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 21/43 2017624 LTE Transmissions Modes in LTE There are 9 TM in LTE as of Rel 10. 1. Single antena transmission 2. Open loop transmit diversity 3. Open loop spatial Multiplexing 4. Closed loop spatial Multiplexing 5. Multi user MIMO 6. Closed loop transmit diversity 7. Beamforing 8. Dual layer beamforming 9. Eight layer beamforming/ SMux. > UL feedback indication 1. CQI > TModes 1 to 9 2. PMI > TModes 4, 5, 6 3. RI > TModes 3, 4 In TM1 & 2 only 1 TB will transmits in same SF. In TM3 & 4 > 2 TBs will transmit in same SF. Reference Signal Types DL Ref signals are divided in to the following types 1. CSIRS > CSI Channel state Information It is used for Channel state feedback computation. CQI, PMI, RI, PTI measurement. CSIRS is mainly used to support 8x8MIMO spatial multiplexing, it is transmitted in PDSCH. Up to 4x4 SMux Channel State Information is transmitted on CRS, On on impleminting 8x8 SMux it may create a over head on other channels. Which may create interference in the cell.Hence CSIRS is introduced to estimate the DL channel quality like CQI, PMI, RI. 2. UERS > It is used for DEMAP and DEMOD of PDSCH. 3. CRSRS > Cell specific Reference Signal Used for the Demod of CCH and PBCH and mobility measurements. It is used for Channel estimation, Cell selection, Reselection and to perform HO. In logs CQI is measured based on RLM > CSI RS. Types of Reference Signals (RS) in LTE Demodulation of different channels (control, data) Channel state feedback (CQI/PMI/RI/PTI) RLM and RRM (RSRP, RSRQ) Frequency/Time tracking loops, COM CQI : CSI Channel State Information. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 22/43 2017624 LTE It is a combination of CQI + PMI(for Closed Loop) + RI CQI Channel Quality Indicator. CQI is reported in UL direction, and calculated from DL channel condition from SINR/SNR by RLMonotoring. CQI reporting is 4 bit value, so 16 posibilities are there. 06 > QPSK, 710 > 16 QAM, 1115 > 64 QAM, these table changes on implementing 256 QAM. CQI reporting modes: Wide band CQI reporting: Periodic/ Aperiodic reporting modes wideband report provides one CQI value for the entire downlink system bandwidth Sub band CQI reporting: The UE selected subband CQI report divides the system bandwidth into multiple subbands, selects a set of preferred subbands (the best M subbands), then reports one CQI value for the wideband and one differential CQI value for the set (assume transmission only over the selected M subbands) Simply, 1 for Wideband and 1 for SUbband(Calculate CQI on all SBands and average and combine and send). Subband CQI is computed over contiguous subset of RBs, may be used by eNB to provide UE max PRBs to give max Tput. Higher layer SUB band CQI reporting. The higher layer configured subband report provides the highest granularity. It divides the entire system bandwidth into multiple subbands, then reports one wideband CQI value and multiple differential CQI values, one for each subband. It uses only APeriodic Reporting mode and transmitted in PUSCH(as data is Huge) Subband CQI Index = differential CQI + wideband CQI Index. CQI reporting modes: Periodic In PUCCH/PUSCH(If any data) In PUSCH because a UE can't transmit PUCCH and PUSCH at a time. APeriodic PUSCH (Triggered by RAResp / DCI F0) CQI Reporting Formats: Format1: Wideband reporting Format2: Subband reporting Format3: Higher layer config Sub band reporting. What is ANR ? > ANR Automatic Neighbour Request > It is a SON feature, in this based on UE's measurement report eNB configures/adds new cells to Neighbour list. This dynamic neighbour list management helps in Network planning. How ANR works ? > UE sends measurement reports of all available PCI to eNB through measurement report. Then eNB requests to send CGI(Cell Global Id) for reported PCI through RRCConnectionReconfiguration. Then UE goes to Measurement Gap and reads the required CGI from SIB information, associated with that PCI. Then UE returns to Serving cell and send the measured signal strength of neighbour PCI. Then eNB grants HO with RRCReconfig message. Measurement Event A3 is reported int his case, A3 > Neighbour becomes offset better than serving cell. Resource Allocation In LTE Resource allocation is done by using DCI and UCI. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 23/43 2017624 LTE In UL the resource allocation is in contineous, in order to support single Carrier property. But in DL the allocated RBs need not be in contineous. In LTE Resource allocaion Type0, 1 and 2 are defined. RA Type 0 and 1 > DL > Not Contineous > DCI1, 2, 2A, 2B RA Type 2 > DL > Contineous > DCI 1A, 1B, 1C, 1D RA Type 0 > UL > Contineous > DCI0 In contineous Resource Allocation type 0 and 2, of DCI formats like 1A, 1B, 1D one bit flag indicates weather Localozed VRBs > 0 Distributed VRBs > 1 Resource Allocation types: DL Scheduling: Type 0: Resource are allocated on "RBG(Resoure Block Group)" based. It means selected RBG's are allocated to one User. DCI Formats like, 1, 2, 2A are used. Type 1: Resource are allocated on "Selected RBG subsets", we know RBG = 4 REs, Hence resource are scheduled on RE basis. Selected RE are assigned from RBG to a user. DCI Formats like, 1, 2, 2A are used. Type 2: This is called Virtual Resource Allocation Scheme. It devided into 2 types Localized RAllocation Distributed RAllocation RIV value is used to identify the Starting and Number of these RBlocks. Resource are allocated on "VRB" basis. DCI Formats like, 1A, 1B, 1C, 1D UL Scheduling: VRB Based UL Scheduling. It means resource are scheduled on contineous PRB basis. Type 2: Resource Allocaation Type 2 is used to schedule UL resource, decoding of this is done by RIV. RIV: Resource Indication Value The RIV is used for signaling the resource allocation from the base station to the terminal. For allocation of Resource, eNB must send 1. Starting of the resource block. 2. Allocated number of resource blocks to configure the above 2 parameters to UE, eNB must use a lot of PDCCH resources. So instead of using that many resources, eNB configures RIV. Note: RIV is mainly used to identify the Resource allocation Type 2's starting and No.of Resource blocks., It is mainly Used for UL Resource Assignment. Time Alignment Timer: It is used to UL time aligned with eNB. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 24/43 2017624 LTE UE is UL time aligned up to the timer ramains running. Time Alignment Timer is divided in to 2 types, TimeAlignmentTimerCommon: It comes in SIB2 It is a cell specific timer. TimeAlignmentTimerDedicated: It is a UE specific timer and managed through dedicated signaling. In above both cases Timer restarts when ever it receives the TACMD value from eNB. First it restarts UE specific timer if configured. else It configures Cell specific timer. When to start/restarts Time alignment timer ? 1. When Time alignment timer is not running. 2. Time alignment timer expires. 3. Initial access from RRC_IDLE, during RRC Connection Reestablishment procedure If contention is not successful then Time alignment timer will stops. 4. On reception of TACMD in Noncontention based Rach. On expiry of time alignment timer UE initiates Rach procedure. PUSCH transport block IE's: 1. Number of records 2. Subframe number 3. Num Antenna 4. Total TX Power 5. Freq Hopping Flag 6. Cyclic Shift DMRS 7. Modulation Type 8. Resource Block Start 9. Number of Resource Blocks 10. PUSCH Hopping Payload > Used to determine VRB to PRB mapping Range: 0..3 11. UL ACK/NAK Present Flag 12. CSF Present Flag 13. SRS Present Flag 14. SRS Cyclic Shift > For Cell Specific SRS scheduling Range: 0…7 15. n_1_pucch > PUCCH Resource Range: 0…2083 16. TIMING ADVANCE COMMAND: Timing advance command is expressed in multiple of 16Ts. Timing Advance cmd is sends to UE in two stages, 1. Random access procedure on RA Response. 2. Through MAC control element. 1. RAResp : In this TACmd is of 11 bits. so we have values range from 0..1282. Ta = 16 * Ts. Ts = 16 *Ta * 1/(15000*2048) Ta value ranges from 0..1282 TA CMD from RA Resp can't be negative 2. Through MAC control element: TA CMD indication through MAC control element is indicated by using, 6 bits value, so its value ranges from 0..63. Nta_new = Nta_old + (Ta31)*16 TA cmd from MAC CE may be ve or +ve. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 25/43 2017624 LTE PDCCH: 1 Pdcch consists of 1 or 2 or 4 or 8 Aggregation levels in CCEs. 1 CCE = 9 REG.(9 consequetive Resource Elements Groups without any Reference Signal) 1 REG = 4 REs > 8 bits if QPSK 1 REs = 2 bits in QPSK modulation technique. 1 PRB = 12 SCarriers, 1 PRB = 12*7= 84 Synmbols in NCP = 12*6=72 Symbols in ECP. In total 1 CCE = 36RE => 36*2 = 72 symbols in QPSK modulation. There are 4 different PDCCH formats mapped to 4 different CCE aggregation levels. UE specific search space can take Aggrigation Levels from, UE Specific Search Space 1, 2, 4, 8 Aggrigation level. Cell Specific Search Space 4, 8. Aggrigation levels, has following sizes, UE Specific: PDCCH DCI 0 1 > 6 CCEs > 6 PDCCH Candidates. PDCCH DCI 1 2 > 12 CCEs > 6 PDCCH DCI 2 4 > 8 CCEs > 2 PDCCH DCI 3 8 > 16 CCEs > 2 Common Specific: 4 > 16 CCEs > 4 8 > 16 CCEs > 2 Note: CIF will present for only UE Specific search space. Aggregation 4 is easy to decode and aggregation 1 is harder to decode. Reasons for low throughput: 1. Power levels at UE. 2. High BLER. 3. Low CQI reporting/Improper CQI reporting. 4. Low MCS and High coding. 5. SNR, Scheduling rate, No. of PRBs. 6. RSRP/RSSI 7. If MAC padding is contineous then something might happen at APP level. 8. BSR and TB size. 9. Does SRS and CQI are transmitting at required power level. Scheduling Request(SR): It is mainly used when UE have limited UL grants or No UL grants to send PUSCH data from UE to eNB(UL). SR will trigger only if 1. Regular BSR triggers 1. Sends SR or 2. Initiates RACH procedure. 2. Short BSR triggers. It only triggers SR. SR is mainly configured in rrcconnectionsetup macmain config http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 26/43 2017624 LTE dsr trans max Max number of SR can trigger if eNB fails to decode the data On expiry of this UE triggers RACH procedure with CRNTI. Pucch resource index It indicates the frequency domain(PRBs) and time domain resources(SFs) sr Config index Once SR is triggered then, UE calculates the, 1. SR Periodicity and Time difference between one SR to next SR. SR peridodities as per Rel8 are, 5, 10, 20, 40, 80 ms In Rel9, short periodities of 1 and 2ms are introduced. 2. Offset. SRProbhit timer: In Rel9, SRProbhit timer is introduced to reduce latency. It mainy used in VoIP traffic, uses: Reduce unnecessary traffic Reduce load on PUCCH. It takes values from 0..7. It is measured in SR periods. o No SR transmission timer 1 1*SR periods 2 2*SR periods . . 7 7*SR Periods When this timer is running UE won't transmit any SR. Note: SR periodicity depends on the SR Configuration, If SR Connfig_Index is, 0 4 > 5ms SR Periodicity. 5 14 > 10ms SR Periodicity. 15 34 > 20 35 74 > 40 . . 155 156 > 2 157 1 How to configure SR Sub frames in one full SFN: (SFN*10 + SF Noffset,SR) MOD SR_periodicity = 0 Frequency Hopping: It is used in UL LTE, by using this technique UE transmits data in UL to eNB by using different Sub carriers.(SCs) MAC CE in LTE: UL: 1. CRNTI:(16 Bits): It is used in Non Contention based RACH procedure. When Max SRequests fails, then it uses CRNTI only. On RLF also it uses this. 2. BSR(6 or 24): There are 3 types of MAC CE for BSR. They are, 1. Truncated BSR: When UE has limited number of resource to send MAC PDU, then this will trigger. 2. Short BSR: When high priority data or new data arrives then this trigger. It is 2 bytes (1 CE + 1 sub Header) 3. Long BSR When data belongs to more than one logical group arrived then this will trigger. It has 4 Bytes of CE (3 bytes of MAC CE + 1byte of Sub header) Long BSR has 4 LCG with LCG # 0 ..3. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 27/43 2017624 LTE BSR TIMERS: 1. retransmission BSR Timer Once BSR report will send to eNB then this timer will start. and stops on receiving UL grants. used to avoid dead lock situation. ue transmitted bsr and never received Ack or Nack is received as Ack then it is used. On expiry of this timer regular BSR trigger 2. Periodic BSR timer It provides the eNB about the Updated buffer status. BSR Trigger types: 1. Regular BSR Regular BSR > SR / RACH procedure SR triggers only with Regular BSR. In SPS resource allocation for IMS calls, BSR will contineously fills up, so Regular BSR triggers, leads to send SR. to avoid this, LogicalChannelConfig logicalChannelSRMaskr9 (This IE prevents SR triggering from Logical channels) 2. Padding BSR When data is less than the header then this BSR will trigger. 3. Periodic BSR For specified time UE reports about its UL Data. Note: BSR precedence, Regular BSR > Periodic BSR > Padding BSR. 3. PHR(6 Bits) DL: 1. TA CMD(6 Bits) (11 Bits in Random access Response) Time alignment timer 2. DRX(6 Bits) Connected mode running timers, DrxInactivityTimer OnDurationTimer RetransmissionTimer Idle mode timers HarQRTT(Round Trip Timer) timer 3. Contention Resolution(48 Bits) ContentionResolutionTimers This timer starts when UE sends msg3. UE is in contineous Active state when this timer runs untill it receives msg4, on expiry of this timer UE again sends Msg3. 4. Activation/DeAct(8 Bits) SCellDeactivationTimer Authentication : In LTE Mutual Authentication will done, i.e Authentication performs in both UE side and MME side. Once MME receives the InitialUEMessage from S1AP of eNB, then MME receives in that message like, Serving Network id, IMSI, UE Network Capabilities like UE supported Auth and Security Algorithms for LTE and other RATs CSFB support SRVCC HO support. 1xSRVCC Support LTE positioning Protocol support etc. MME transfers these IMSI and SN id to HSS. Based on this HSS generates Auth Vector and sends to MME. How to generate Auth Vector ? SQN generated by HSS and Incremented by one every time. LTE K generated based on IMSI by HSS. RAND HSS chooses one random number. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 28/43 2017624 LTE {SQN, LTEK, RAND} >(passes through) [Crypto Function] > (gives) > {AUTN, XRES,Ik, Ck } These { Ik, Ck, AUTN, SN id } > passed through [KDF] > (gives) > Kasme. These Authentication Vector is transfered to MME by using Authentication Information Response. AV > {AUTN, XRES, RAND, Kasme} Where MME transfers {AUTN and RAND with KSIasme} to UE. With the help of AUTN UE generates SQN. AUTN and RAND > SQN LTEK, SQN, RAND > Ck, Ik, AUTN, XRES Compares AUTN of UE with Received AUTN from MME. If comparision pass, then generates Kasme and sends "RES" in Auth Response message. PICS/PIXIT: Pics and Pixit is configured by using QPNG(Qualcomm Pixit Nv Genarator) Uses: It totally removes the manual work in configuring Nv items from PICS by writing nv items to FFA. Used in setting Pics/Pixit on test equipment in lab confermence process to provide ease and accuracy to customers. This tool creates PIXIT file and Nv script file to configure the device from the PICS document of 3GPP/Non 3GPP techs. Input: Get PICS Spreadsheet from agile. Default PIXIT sheet will be there for TBS(Anite, RNS, Anritsu), these default PICS will be compared with the values currently set in PICS document. If they are diff then the new value will be over ridden. Requirements to generate PICS: Note: Anite PICS file is in .XML Anritsu PICS file is in .txt RNS PICS file is in .TSP formats. How to calculate MAX throughput in LTE: Tput:= TB size * 8 bits/Byte * Num of layers * 1000 m/s For ex we get 60 Mbps. Then decrease BLER from that, assume BLER is 10 %, so BLER = 0.1 BLER should always be < 10%, if above 10% then n310 timer will start, on expiry RLF occur. Final Tput = 60 Mbps 0.1*60 = 60 6 = 54 TEST CASES ON CA: Random Access Procedure: eNB have PCELL(CC1) and SCEll(CC2), PCELl is in Serving cell. eNB Adds SCELL by RRC_CONN_RECONFIG Activates by MAC CE. Sends the PDCCH order DCI 1A (raPreambleIndex and PRACHMaskIndex) on SCELL. UE sends Random Access Request on SCell. eNB sends Random Access Responsce on the PCell. For contention based Random Access Procedure MAC selectes the raPreambleIndex and is http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 29/43 2017624 LTE equal to zero(000000) For Non contention bases RACH procedure eNB explicitly signals the raPreambleIndex and PRACHMask_Index. If MAC won't selects the raPreambleIndex then UE applies the TACMD coming in RAResponse. When did UE's MAC selects raPreambleIndex ? Case1 UE receives a paging message, and the size of msg3 is less than the threshold. Then UE selects the preamble from groupA which indicated in SIB2. Case2 eNB does not respond untill contention resolution timer expires, then UE again transmits the preamble of same group. Case3 eNB does not respond untill contention resolution timer expires, and preamble trans max is expired and UE uses the same preamble group. Case4 UE has data to send and that data is geater than the messagesizeGroupA, then UE uses GroupB preamble. Hand Overs in LTE: UE Old eNB New eNB MME < RrcConnectionReconfiguration > RrcConnectionReconfigurationcomplete > HO Request(sgw_s1ap_id, old_eNB_X2AP_id, ERAB_to_mod_list Identities in LTE: 1. EPS Bearer Id Between UE and Pgw It is allocated by MME 4 Bit value, 0 15 0 > Not assigned 14 > reserved 515 > Available for Use. If UE is allocated with 1 dedicated bearer then it has 1 EPS Bearer Id(Same as Default bearer) and 1 LB Id(New LBI). 2. DRB Bearer Id Between UE and eNB It is allocated by eNB 3. ERAB Between UE and Sgw It is allocated by MME 4. LBI Identify default bearer associated with Dedicated bearer. It is allocated by MME 5. S1 TEID Between eNB and Sgw 6. S5 TEID Between Sgw and Pgw 7. GUTI(80 Bits) MCC + MNC + MMEGI + MMEC + MTMSI http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 30/43 2017624 LTE MCC 3 Digits MNC 3 Digits MMEGI 16 Bits MMEC 8 Bits MTMSI 32 Bits 8. STMSI(40 Bits) MMEC + MTMSI 9. In paging, STMSI or IMSI will present, STMSI = MMEC + MTMSI 10. CRNTI(16 Bits) identifies UE uniquely on a cell for PDCCH. Measurement Gaps : Measurement Gap is used when UE is to perform Inter frequency or Intra RAT frequency measurements, > Measurement gap is configured in rrcConnectionReconfiguration MeasGapConfig It has Gap Pattern Type 0 and 1. By using GP, UE can calculate 1. Periodicity: Starting of measurement Gap. 2. GAP Offset Total time for measurement Gap. GP0: Its periodicity is 40ms. GP0 is used when, 1. If UE is compatable with current cell, and no hurry to do a measurenent gap. 2. When multiple inter frequency cells are there to complete measurenent then gp0 is used. 3. If UE is using hogh data rates and need to measure other frequency. GP1: Its periodicity is 80 ms. What actually measurement GAP is ? Answer: Measurement GAPs main intention is to send eCGI (EUTRAN CELL GLOBAL Identity to eNB), eCGI info has, 1. CGI 2. TAC 3. PLMN Id To read eCGI UE must switch to other frequency and should read PSS, SSS, MIB and SIB1 which requires a lot of time. eNB can send this info in two forms, which are, 1. Autonomous GAPs: In UE capability info UE sends weather is supports AUTONOMOUS GAPs are not, If UE supports AUTONOMOUS GAPS then it set, siRequestForHO =1, if it won't sent then second method should trigger(DRX method). What is AUTONOMOUS GAPS ? It is a technique where eNB halt the UE the Tx and Rx of any data. In this state eNB assigns specific time to perform measurement GAPS, UE must read the required info by switching on that frequency and send the measurement report. 2. On going to DRX state If siRequestforHO =0 then eNB configures this method. UE requires so much time to perform measurement on the other frequency because it have to PSS,SSS,MIB and SIB1. So eNB configures the UE to perform other freq measurement in CDRX modes and Reconfigures the CDRX parameters. On these idle time UE moves to other frequency and read the required eCGI and send to eNB once that timer expires. On these time eNB should not schedule any UL grants and Data to UE. Note: What is intra frequency ? Cell with different band width and same Carrier frequency(Same EARFCN). http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 31/43 2017624 LTE Measurement GAP configuration is for Inter and Inter RAT frequencies only but not for intra frequecny(Same EARFCNs). GAPs have high priority than data Tx/Rx. UL Grants have high priority than DRX. In measurement report RSRP and RSRQ of neighbour and Serving cell is triggered. NOTE: 1. High BLER in downlink (DL) causing outofsync 2. High BLER in UL causing RLC max retransmissions. 3. RLF due to max RACH attempts. 4. For low throughput, Check the code rate on DL subframes where there is BLER. Code rate > .93 may not be decodable 5. SRBs 1 and 2 uses resource blocks(RB Config Index) above 32, where all DRBs(1..32) are used for data. 6. PDCP is mapped to RLC by using EPS id to LC id 7. If Msg3 is sent and UE receives ACK, and No DL MAC TB, then it leads to Contention Failure. 8. Check if UE RSSI is reasonable and not close to sensitivity (RSSI < 90 dBm, or RSRP < 105 dBm) 9. PCFICH has values 1, 2, 3 if it is equal to 1 then RE/PRBs are 150, 2 > 138, 3 > 126. 10. CQI table gives info about, 1. Modulation(QPSK, 16 QAM, 64 QAM, 256 QAM) 2. Code rate 3. efficiency 11. MCS table gives info about, 1. Modulation Order (2, 4, 6, 8) 2. TBS Index (To find TB Size) 12. Rel 12(Includes 256 QAM) or Rel 8, CQI table is identified by using 1. altCQITable r12 13. CIF(It is used to decode Cross carier scheduled UEs PDCCH DCI info for PUSCH/PDSCH for SCEll) value is the same as ServCellIndex. 14. CIF is present on only PCELL. 15. SNR is calculated in connected mode with RLMonitoring, and these SNR is used for CQI reporting, In sync and Out Sync determination. 16. If PDCCH decode is unsuccessful then there is no log packet for that SF. 17. Smaller energy metric and large SER(Symbol Error Rate) are indicative of poor channel condition these are present in DCCH. 18. ‘Discarded Retx Present’ field in PDSCH indicates whether UL ACKs from UE are reaching NW 19. SDF(service data flow) are used to map packets to the TFT(traffic flow template) based on 5 tuples and TFT is responsible for maping packet to the respective bearer which matches the QOS of bearer and the packet. 20. If contentionResolution fails then UE initiates RACH procedure. 21. Why in Counter Check Procedure only MSB bits are checked and not LSB? [Answer] : With CounterCheck procedure eNB is verifying that the UE and eNB are in sync with respect to the packet count; and there hasn’t been any packet insertion by an intruder. The least 7 bits aren’t sent by the eNB because a discrepancy of 128 packets can be tolerated. Another reason is that the packet count is input to the encryption/integrity check functions. So, the eNB may not want to let out its exact count value to the UE. But eNB wants to send enough bytes (MSBs) to verify the count is in valid range. The UE however sends the exact count in the cases where there is discrepancy… to let the eNB know how much of a discrepancy there is; to let eNB figure out the action to be taken… i.e. release the connection or report the difference in COUNTs to MME or an O&M server. 22. For Common search space PDCCH candidates are, Aggregation level PDCCH candidates Size in CCEs 1 6 6*1 = 6 2 6 6*2 = 12 4 2 4*2 = 8 8 2 8*2 = 16 UE Specific search space PDCCH candidates are, Aggregation level PDCCH candidates Size in CCEs 4 4 4*4 =8 8 2 8*2 = 16 23. One HARQ process can have its own HARQ Id + RV + NDI 24. In contention based random access procedure, UE sends Random access Procedure, then eNB sends RAResponse. Its MAC header is as follows http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 32/43 2017624 LTE (R) (T) (RAP_id) 1 1 6 If T= 1 RAResp T= 0 Back Off Indicator. 23. APeriodic CQI or CSI request is triggered, and is of 2 Bits, 00 No CSI 01 CSI for Serving cells 10 CSI for 1 set of serving cells 11 CSI for 2 set of Serving cells 1. Random Access Response 2. DCI format. 24. Periodic CQI info is configured in, (pdschconfigdedicated) 1. rrcConnectionsetup 2. rrcConnectionReconfiguration. 25. In measurement, event A3 is used for PCell replacement. event A6 is used for SCell replacement. SCell also reports A3 measurement to PCell(If that measurement report is good then SCell is converted as PCell). This situation is mainly used in cell edge situation, to reduce interference among diff cells. http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 33/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 34/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 35/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 36/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 37/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 38/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 39/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 40/43 2017624 LTE http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 41/43 2017624 LTE Posted by varadamohan reddy at 20:38 Recommend this on Google No comments: http://lte3gpp.blogspot.in/2015/11/carrieraggregation1.html 42/43 2017624 LTE Post a Comment Enter your comment... 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