For internal use only 1 © Nokia Siemens Networks / DL LA and PC
For internal use only 2 © Nokia Siemens Networks / Comparison of DL and UL link adaptation for PSCH • Downlink – fast 1 TTI – channel aware CQI based – MCS selection 1 out of 0-28 – output MCS TBS – UE capabilities support max. TBS per TTI – up to 64QAM support • Uplink – slow periodical ~30ms – channel partly aware average BLER based – MCS adaptation +/- 1 MCS correction – output MCS ATB – UE capabilities support power headroom QoS profile – up to 16 QAM support
For internal use only 3 © Nokia Siemens Networks / DL LA overview UE eNodeB CQI, RI (and PMI) DL Data Outer Link Quality Control (OLQC) •Corrects reported CQI based on Ack/Nack • Target BLER - dlTargetBler (10% by default) UE calculates CQI: •Based on RS and data CE SINR (assumption?) •Wideband and subband CQIs can be reported. UE calculates RI: Based on tx branch correlation (assumption?) HARQ Ack/Nack Dynamic MIMO mode switching •Selects MIMO mode based on CQIcorr and RI •Switching decisions in 100ms intervals •Adds additional compensation to CQIcorr based on RI and MIMO mode MCS selection •Based on CQI corrected by OLQC and MIMO switching
For internal use only 4 © Nokia Siemens Networks / DL LA - input parameters description • CQI values (from OLQC) – corrected wideband/frequency selective CQIs • Scheduling information (from DL SCH) – list of PRBs/RBGs assigned to the UE – upper or lower downlink rate limit • HARQ feedback (from DL HARQ) – ack/nack information • UE capabilities (from RAC) – maximum allowed number of bits for single(all) DL SCH transport block(s) within a TTI according to 3GPP-36.306 • MiMo mode selection (from MiMo-MC) – single/double code word case • Rank indicator (from OLQC)
For internal use only 5 © Nokia Siemens Networks / DL LA – algorithm overview • Algorithm has a UE scope and is working on TTI basis • Performed separately for each code word if only code word specific CQI is available (from RL20) Retrieve Default MCS Start End Yes Dynamic AMC active? Determine averaged CQI value for allocated PRBs Use same MCS as for initial transmission Determine MCS No HARQ retransmission? Yes No Use default MCS Link adaptation disabled Retransmission Start with default MCS
For internal use only 6 © Nokia Siemens Networks / • Select CQI values related to the PRBs/RBGs which have been assigned to UE by DL SCH • Map these CQIs to CIRs values by means of R&D look-up table • Calculate average CIR value • Map average CIR to average CQI (possible interpolation between full CQI steps defined by 3GPP) • If only wideband CQI is available above procedure is obsolete CQI index Modulation Coding Rate x 1024 Efficiency 0 out of range 1 QPSK 78 0.1523 2 QPSK 120 0.2344 3 QPSK 193 0.3770 4 QPSK 308 0.6016 5 QPSK 449 0.8770 6 QPSK 602 1.1758 7 16QAM 378 1.4766 8 16QAM 490 1.9141 9 16QAM 616 2.4063 10 64QAM 466 2.7305 11 64QAM 567 3.3223 12 64QAM 666 3.9023 13 64QAM 772 4.5234 14 64QAM 873 5.1152 15 64QAM 948 5.5547 4-bit CQI table, 3GPP 36.213, table 7.2.3-1 DL LA – determine average CQI for assigned PRBs 2/2 If 64QAM modulation is not enabled in the cell CQI index is limited to 9
For internal use only 7 © Nokia Siemens Networks / OLQC – CQI Adaptation • Outer Link Quality Control (OLQC) adapts the channel quality information that is used by the scheduler and link adaptation to achieve target block error ratio (BLER) for the first transmission of a Transport Block • OLQC compensates any non-idealities of the link adaptation : • CQI estimation error of the UE • CQI quantization error • CQI reporting error • Time delay between CQI measurement and the reception of the subsequent data block • CQI interpolation error • Errors due to CQI averaging of PRBs • dlOlqcEnable parameter is used to enable/disable the outer link quality control. When outer link quality control is disabled then the corrected CQI values correspond to the reported CQI values.
For internal use only 8 © Nokia Siemens Networks / OLQC algorithm – input parameters description • CQI reports (from UL L1/L2 sig): – wideband – frequency selective – code word specific (starting from RL20) • HARQ feedback (from DL HARQ) – ack/nack information • MiMo mode selection (from MiMo-MC) – single/double code word case OLQC algorithm – output parameters description • Corrected CQI reports (to DL LA): – wideband – frequency selective – code word specific (starting from RL20)
For internal use only 9 © Nokia Siemens Networks / CQI adaptation/correction algorithm • OLQC adds a CQI offset ( ) to the wideband/frequency selective and code word specific (starting from RL20) CQI values • Delta CQI is initialized in the following way CQI CQI ( , , ) CQI ( , , ) CQI( ) corrected rep reported rep x f t x f t t CQI ( , ) CQI ( , ) CQI( ) corrected reported x t x t t setup ΔCQIinit ΔCQI(t )
For internal use only 10 © Nokia Siemens Networks / CQI adaptation/correction algorithm • Delta CQI calculation – single code word case – double code word case – balance condition CQI( 1), for first HARQ feedback N/A. max( CQI( 1) CQI , CQI ), for first HARQ feedback NACK, min( CQI( 1) CQI , CQI ), for first HARQ feedback ACK, CQI( ) stepdown min stepup max t t t t target CQIstepup BLERtarget CQIstepdown (1 BLER ) CQI( 1), for first HARQ feedbacks N/A N/A. max( CQI( 1) CQI , CQI ), for first HARQ feedbacks NACK N/A, min( CQI( 1) CQI , CQI ), for first HARQ feedbacks ACK N/A, for first HARQ feedbacks ACK NACK, CQI ), CQI ), min(max( CQI( 1) (CQI CQI )/ 2, max( CQI( 1) CQI , CQI ), for first HARQ feedbacks NACK NACK, min( CQI( 1) CQI , CQI ), for first HARQ feedbacks ACK ACK, CQI( ) stepdown min stepup max min max stepup stepdown stepdown min stepup max t t t t t t t
For internal use only 11 © Nokia Siemens Networks / CQI adaptation/correction algorithm • Provide DL LA with: – corrected wideband CQI – corrected frequency selective CQI – code word specific (from RL20) CQI ( , , ) CQI ( , , ) CQI( ) corrected rep reported rep x f t x f t t CQI ( , ) CQI ( , ) CQI( ) corrected reported x t x t t
For internal use only 12 © Nokia Siemens Networks / OLQC - O&M configuration Parameter, abbreviated Name (mand) Description (mand) Access RW R (mand) Parameter Type O: operator configurable V: vendor configurable (mand) Range, Stepsize/Granul arity, Units, Special Value (e.g. "not defined") (mand) Default Value (opt) Parameter Scope (PLMN, RAN, Nb, Cell, Chl) Proposed MOC (mand) Reference e.g. 3GPP name or other (opt) Multiplicity dlOlqcEnable Switch to enable/disable OLQC RW O Boolean (0/1) 0=True 1=False True Cell - 1 dlOlqcDeltaCqiIni Initial value of CQI offset R V -15 to +15 in steps of 0.1 -0.5 BTS - 1 dlOlqcDeltaCqiMax Maximum value of CQI offset R V 0 to 15 in steps of 0.1 1 BTS - 1 dlOlqcDeltaCqiMin Minimum value of CQI offset R V -15 to 0 in steps of 0.1 -3 BTS - 1 dlTargetBler Target block error ratio of transport blocks for 1st transmission RW O 0.001 to 0.999 in steps of 0.001 0.10 Cell - 1 dlOlqcDeltaCqiStepUp CQI offset increase for an ACK R V 0.001 to 1 in steps of 0.001 0.125 BTS - 1
For internal use only 13 © Nokia Siemens Networks / Dynamic MIMO mode (RL10) Depending on Radio Conditions: switch between Diversity and Spatial Multiplexing - Open loop MIMO Switch Algorithm - Open loop adaptive MIMO Algorithm - Support of UE Capabilities - UE basis - CQI and Rank Information: used as switching criteria Diversity x Spatial Multiplex
For internal use only 14 © Nokia Siemens Networks / Dynamic MIMO mode Simulation Results (Source 4GMAX)
For internal use only 15 © Nokia Siemens Networks / Dynamic MIMO mode Inactivity : aging RI Time CQI Time Inactivity : Aging applied Filtered Filtered: cqi, ri • Switching decision based on CQI, RI • Frequency: rather low (100 msec..seconds) Downgrade Switch:: If mimoCQI <= mimoOlCqiThD or mimoRANK <= mimoOlRiThD Upgrade Switch : If mimoCQI > mimoOlCqiThU and mimoRANK > mimoOlRiThU mimoOlCqiThD mimoOlCqiThU mimoOlRiThU mimoOlRiThD
For internal use only 16 © Nokia Siemens Networks / MIMO CQI COMPENSATION EXAMPLE, (dlMimoMode=3) CQI TIME Compensated CQI CQI and RI reported by UE Transmission mode changed to OL-SM by MIMO mode control RI=1 RI=1 RI=2 RI=2 RI=2 RI=2 RI=2 RI=2 cqiCompTdRi2Ol UE-reported RI changes to 2, TM is still tx diversity cqiCompSmRi1Ol RI=1 RI=1 UE starts reporting RI=1, but OL-MIMO still in use Default cqiCompTdRi2Ol = 3 Default cqiCompSmRi1Ol =-3
For internal use only 17 © Nokia Siemens Networks / Generic Parameters RL20
For internal use only 18 © Nokia Siemens Networks / OL MIMO – Parameters (not modifiable mostly)
For internal use only 19 © Nokia Siemens Networks / CL MIMO – Parameters (for RL20)
For internal use only 20 © Nokia Siemens Networks / PDCCH Scheduling
For internal use only 21 © Nokia Siemens Networks / Introduction to PDCCH • Physical channel for Downlink Control Information (DCI) i.e. resource assignments, PC commands • DCI can be dedicated for a group of UEs (common signaling) or to a specific UE (dedicated signaling) • Allocation rules – 0…3 OFDM symbols per subframe – 2…4 OFDM symbols per subframe (1.4 MHz; RL20) – Aggregated on CCEs – QPSK only but different aggregation levels (AGG levels) Cell-specific RS (port 0) Cell-specific RS (port 1) Resource Element Group (REG) = 4 REs Control Channel Element (CCE) = 9 REGs t f Physical Resource Block (PRB) PDCCH format Number of CCEs Number of Resource Element Groups Number of PDCCH bits 0 1 9 72 1 2 18 144 2 4 36 288 3 8 72 576
For internal use only 22 © Nokia Siemens Networks / 1-CCE 8-CCE 2-CCE 4-CCE • Macro cell case #1 • Uniform UE distribution Main target of DL-AMC-CCH • Similar to data transmission, it is necessary to make a signaling (PDCCH) robust enough for poor UEs (low SINR, e.g. at the cell-edge) • Transmission with low ECR (Effective Coding Rate) leads to increased resource utilization which reduces the number of scheduled UEs; thus good UEs should occupy less PDCCH resources and operate with lower number of CCEs (higher ECR) – 7 UEs (5 MHz), 10 UEs (10 MHz), 20 UEs (20 MHz) • Any Link Adaptation technique must deal with a trade-off between signaling robustness (coverage) and signaling capacity
For internal use only 23 © Nokia Siemens Networks / CQI Measurements filtering pdcchCQI(t) = (1-pdcchCqiAvg)*pdcchCQI(t-1) + pdcchCqiAvg*newCqi • DL-AMC-CCH requires to operate with CQI reports filtered based on the historical reporting and newly calculated CQI. • Initial value of pdcchCQI(0) corresponds to CQI which is required to set the default AGG level for DCI format 1. pdcchCQI(0) = F-1(pdcchAggDefUe) • CQI filter ages last CQI report every 10 ms if no new ones are available. pdcchCQI(t) = rdPdcchCqiAge*pdcchCQI(t-1) CQI1 t 10ms 10ms 10ms 10ms CQI2 CQI3 CQI4 More robust AGG levels… • Filtered CQI might be shifted according to cell-specific CQI shift. E.g. all UEs in the cell may be forced to switch to higher AGG levels at the cost of PDCCH capacity. pdcchCQI(t) = pdcchCQI(t) + pdcchCqiShift • CQI filter operates with wideband CQI reports and Rank Information. The effect of OLLA/OLQC can be disabled. • MIMO compensation is needed because the reported CQI is smaller than for single codeword transmission, however if Rank Information is not available, Rank=1 is assumed (no compensation). • For open loop MIMO (RL10) CQI for Stream1 equals Stream2 Rank=1 newCQI = WIDEBAND_CQI_Stream1 + DELTA_CQI*rdPdcchOllaUsed Rank=2 newCQI = (WIDEBAND_CQI_Stream1 + WIDEBAND_CQI_Stream2)/2 + pdcchXXComp + DELTA_CQI*rdPdcchOllaUsed To CQI-to-Aggregation Mapping unit… pg1 pg2
Slide 23 pg1 CQI-Ageing is stopped when pdcchCQI(t)=0 or pdcchCQI(t) falls below the threshold determines by DCI format 1 with the default AGG level (taken from Piotr Godziewski, 1/18/2010 pg2 Reverse function F-1(pdcchAggDefUe) can be calculated using the formula: CQI= Piotr Godziewski, 1/18/2010
For internal use only 24 © Nokia Siemens Networks / CQI-to-Aggregation Mapping unit CQI from DL-AMC/DL-OLQC CQI filtering/processing Filtered, compensated and shifted CQI All DCI formats… 1 CQI-to-Aggregation Mapping REQUIRED_AGG_LIST = { UE-1: pdcchCQI, AGG-DCI0, AGG-DCI1, …; UE-2: pdcchCQI, AGG-DCI0, AGG-DCI1, …; …; UE-k: ...; } DLS_INPUT_LIST = { Broadcast, Tag, DCI-format, CSS, Prio-A; Paging, Tag, DCI-format, CSS, Prio-B; RACH Response, Tag, DCI-format, CSS, Prio-C; Preamble Assignment, Tag, DCI-format, CSS, Prio-D; Message 4 Assignment, Tag, DCI-format, CSS, Prio-E; UE-1, Tag, DCI-format, USS, Prio-X; UE-2, Tag, DCI-format, USS, Prio-Y; …; UE-k: ...; } ULS_IINPUT_LIST = { UE-1, Tag, USS, Prio-X; UE-2, Tag, USS, Prio-Y; …; UE-k: ...; } • CQI-to-Aggregation Mapping unit relies on UEspecific CQI information to build the list of required AGG levels for all possible DCI formats for every active UE (UE which appears on the DL/UL scheduling list). • REQUIRED_AGG_LIST must refer to all active UEs so that the schedulers know how many resources are needed to allocate them. • Common signaling (e.g. Broadcast, Paging, etc.) is not considered at this step; the mapping affects UE Search Space (USS) only. 1a …
For internal use only 25 © Nokia Siemens Networks / CQI-to-Aggregation Mapping unit rdPdcchAggTables • SINR-vs-BLER tables have been obtained from 4GMax LL simulator (EPA05, 2x2MIMO) for two representative payload sizes of 45 bits and 60 bits. • The PDCCH performance should aim at 1% target BLER. • SINR targets have to be translated to CQI thresholds. • The mapping table is not sufficient. R&D in-built table must consist of thresholds for all possible DCI formats (various payload size). A scaling factor (SF) is applied. CQI = 0.51*SINR + 5.3 Mapping table for 45/60 bits payload composed based on CQI-to-SINR formula (4GMax) SFsmallDCI = 10*log10(DCI_size/45) SFlargeDCI = 10*log10(DCI_size/60)
For internal use only 26 © Nokia Siemens Networks / CQI-to-Aggregation Mapping unit rdPdcchAggTables • After post-processing of 4GMax output, the table is ready to be used by the CQI-toAggregation Mapping unit. • The table is valid for 10MHz bandwidth, however the operator can adjust the thresholds by using O&M parameter pdcchCqiShift. • If PDCCH AMC is disabled or CQI is outdated, pdcchAggDefUe will be applied to all DCI formats of all UEs. Mapping table for 45/60 bits payload composed based on CQI-to-SINR formula (4GMax) Full rdPdcchAggTables for all available DCI formats (10MHz system bandwidth) CQI = 0.51*SINR + 5.3 SFsmallDCI = 10*log10(DCI_size/45) SFlargeDCI = 10*log10(DCI_size/60)
For internal use only 27 © Nokia Siemens Networks / PDCCH Scheduling - Parameters Short Name Description Range/ Step Default Value Parameter Scope Remark enableAmcPdcch Enable/disable CQI-based AMC for PDCCH. In case the parameter is disabled, the default AGG level is used. true/false true Cell Changing parameter requires object locking. Operator configurable. pdcchAggDefUe Default AGG level for PDCCH in case enableAmcPdcch==false or (enableAmcPdcch==true and there are no valid CQIs available). 1 (0), 2 (1), 4 (2), 8 (3) 4 (2) Cell Changing parameter requires object locking. Operator configurable. pdcchCqiAvg Averaging constant for CQI measurement filter. 0.05...1, step 0.05 0.5 BTS Not modifiable. Vendor configurable. pdcchCqiShift The fine-tuning parameter to adjust measured and averaged CQI. -10...10, step 0.1 - BTS Changing parameter requires object locking. Operator configurable. pdcchOlComp CQI compensation for open loop MIMO mode. 0...10, step 0.1 3 BTS Not modifiable. Vendor configurable. pdcchClComp CQI compensation for closed loop MIMO mode. 0...10, step 0.1 3 BTS Not modifiable. Vendor configurable. pdcchCqiHist The time which old CQI is remembered for (than fallback to the default AGG level). 0...1000 ms, step 1 ms 30 ms BTS Not modifiable. Vendor configurable.
For internal use only 28 © Nokia Siemens Networks / DL power control, RL10 RL10: (static) Cell Power Reduction • based on single parameter CELL_PWR_RED = 0.0, 0.1 … 10.0 dB • cell size adjustment and coverage control • flat Power Spectral Density (PSD) • semi-static MIMO_COMP (if enabled) PSD Frequency PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs) Allocated DL PRBs DL Pilots PSD Time PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs) PDCCH PDSCH, PCH BCH, SCH PSD Frequency PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs) Allocated DL PRBs DL Pilots PSD Time PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs) PDCCH PDSCH, PCH BCH, SCH LNCEL: dlCellPwrRed 0..10dB, default = 0 dB
For internal use only 29 © Nokia Siemens Networks / Power allocations Channel Cell / User 1 TX Mode TX Diversity Mode MIMO SM Mode BCCH (PBCH+PDSCH) Cell PSD_0 PSD_MIMO PSD_MIMO PDCCH User PSD_0/ PC PSD_MIMO/ PC PSD_MIMO/ PC PCFICH Cell PSD_0 PSD_MIMO PSD_MIMO PHICH User PSD_0 PSD_MIMO PSD_MIMO PDSCH User PSD_0 PSD_MIMO PSD_MIMO RS Cell PSD_0 PSD_0 PSD_0 SYNC Cell PSD_0 PSD_0 / PSD_MIMO PSD_0 / PSD_MIMO PCH Cell PSD_0 PSD_MIMO PSD_MIMO At system setup the eNodeB shall claculate the following PSD values: PSD_0 = (pMax - CELL_PWR_RED) - 10*log10( # PRBs_DL *12) PSD_MIMO = (pMax - CELL_PWR_RED) - 10*log10( # PRBs_DL *12) - MIMO_COMP PDCCH power control can be enabled by parameter Depends if Sync diversity is enable/disabled.
For internal use only 30 © Nokia Siemens Networks / DL basic power parameters Name Object Abbreviation Range Description Default Cell Power Reduce LNCEL dlCellPwrRed 0...10 dB, step 0.1 dB CELL_PWR_RED: Sets the power reduction from a antenna maximum Tx power 0 dB MIMO Compensation LNCEL dlpcMimoComp 0...10 dB, step 0.1 dB When TxDiv or 2x2 MIMO SM is used, gain applies in downlink. Parameter shall be set according to known gain (typically 3dB). 0 dB
For internal use only 31 © Nokia Siemens Networks / Impact of Cell Tx power •Increasing cell Tx power will improve DL performance •Impact is biggest in noise limited case (empty network or isolated cells) LTE max cell power 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 10 20 30 40 50 60 70 80 Phy DL Tput (Mbps) Cumulative % 20W 40W 60W Max Average Max Average Max Average RSRP (dBm) -72 -88.61 -68 -86.04 -65 -84.12 SINR (dB) 29 23.38 31 23.83 28 23.63 CQI Metric 0 15 11.23 15 11.44 15 11.26 CQI Metric 1 15 11.17 15 11.34 15 11.18 Phy DL Tput (Mbps) 62.34 28.98 70.78 33.31 63.39 34.24 20W 40W 60W Example results (RL10, 10MHz bw, 3HK trial)
For internal use only 32 © Nokia Siemens Networks / dlpcMimoComp parameter •Reduces power of all other Channel elements, except Reference Signal CEs => works like RS boosting RSRP vs. throughput 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 -130 -128 -126 -124 -122 -120 -118 -116 -114 -112 -110 -108 -106 -104 -102 -100 -98 -96 -94 -92 -90 -88 -86 -84 -82 -80 -78 -75 dBm Mbps MIMOcomp 0dB MIMOcomp 3dB SINR vs. throughput 0 10 20 30 40 50 60 70 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 dB Mbps MIMOcomp 0dB MIMOcomp 3dB
For internal use only 33 © Nokia Siemens Networks / PDCCH power control • DL Power Control for PDCCH is an additional mechanism interacting with DL AMC for PDCCH in order to make the signaling as robust as possible • DL-PC-CCH aims at 1% target BLER but cannot modify AGG assignments • Main actions performed by DL-PC-CCH – Power reduction on CCEs with assigned AGG level higher than required (or equal) – Power boosting on CCEs with assigned AGG level lower than required – Equal power relocation among all scheduled CCEs 1-CCE 8-CCE 2-CCE 4-CCE • Macro cell case #1 • Uniform UE distribution Very good CCEs (CQI highly above 1% BLER target) Bad CCEs (AGG level too high to meet 1% BLER target) If still some power available, relocate equally among all CCEs
For internal use only 34 © Nokia Siemens Networks / Principles of DL-PC-AMC • PDCCH Power Control can be enabled/disabled by O&M switch • Maximum transmit power of the Power Amplifier cannot be exceeded (pMax; O&M) • Reduction and boosting range is strictly defined and is always considered as the limit for power level modification • DL-PC-CCH operates together with DL-AMC-CCH on TTI basis • DCI messages with more than one CCE (AGG-…>1) have a flat PSD, thus all CCEs belonging to one scheduled UE are transmitted with the same power Short Name Description Range/ Step Default Value Parameter Scope Remark enablePcPdcch Enabling/disabling PC for PDCCH. In case the parameter is disabled, a flat downlink PSD is used. true, false true Cell Changing parameter requires object locking. Operator configurable. pdcchPcBoost Maximum power boost per CCE. 0...10 dB, step 0.1 dB 4 dB BTS Not modifiable. Vendor configurable. pdcchPcRed Maximum power reduction per CCE. 0...10 dB, step 0.1 dB 6 dB BTS Not modifiable. Vendor configurable. pdcchPcReloc Maximum limit on the equal power relocation per CCE. 0...10 dB, step 0.1 dB 3 dB BTS Not modifiable. Vendor configurable.
For internal use only 35 © Nokia Siemens Networks / General algorithm OUTPUT_LIST_DL_AMC_CCH from DL-AMC-CCH • required AGG levels per UE per DCI format • assigned AGG levels per UE per DCI format • pdcchCQI per UE • calculated TOTAL_NUM_CCEs (all available CCEs; PHICH&PCFICH considered) Build the Power Basket (“free unused” power on PDCCH) Count unused power from unscheduled CCEs Decrease the power for all UEs with assigned AGG level equal to the required AGG level to meet the 1% BLER target and count the amount to the Power Basket Increase the power for all UEs with the assigned AGG level lower than the required AGG level to meet the 1% BLER target. Modify the Power Basket according to the amount of power used for boosting. If the Power Basket is still not empty, relocate the excess power equally among all scheduled UEs. OUTPUT_LIST_DL_PC_CCH from DL-PC-CCH • power levels to be applied for all scheduled UEs …to DL-PHY
For internal use only 36 © Nokia Siemens Networks / Power reduction • Power reduction is always limited by the threshold (pdcchPcRed) • CQI_UEi is the output CQI derived based on the assigned AGG level • CQI_TARGETi is the target CQI for the 1% BLER target for the given DCI format PWR_REDi = min(pdcchPcRed, 1.96*(CQI_UEi – CQI_TARGETi)) [dB] CQI_UEi ≥ CQI_TARGETi This can happen to UEs: with the assigned AGG-1 although the CQI is still much higher than required for 1% BLER with AGG-2, -4 or -8 with the CQI slightly above 1% BLER target with AGG level perfectly matching the requirement for 1% BLER target • The factor of 1.96 has been obtained from 4GMax • The Power Basket PWR_BASKET is correspondingly modified but the detailed calculation will depend on the implementation • Finally the power correction must be stored in OUTPUT_LIST_DL_PC_CCH PWR_BASKET += f(AGG-Xi, PWR_REDi) PSDi = PSD_UE_CTRL – PWR_REDi
For internal use only 37 © Nokia Siemens Networks / Power boosting • Power boosting is always limited by the threshold (pdcchPcBoost) • CQI_UEi is the output CQI derived based on the assigned AGG level • CQI_TARGETi is the target CQI for the 1% BLER target for the given DCI format PWR_BOOSTi = min(pdcchPcBoost, 1.96*(CQI_TARGETi – CQI_UEi )) [dB] CQI_UEi ≤ CQI_TARGETi It can happen if all the following conditions are true: enableLowAgg=true & enablePcPdcch=true & PDCCH Utilization > pdcchLowAggTh …then: all AGG-8AGG-4 & all AGG-4AGG-2 • The factor of 1.96 has been obtained from 4GMax • The Power Basket PWR_BASKET is correspondingly modified but the detailed calculation will depend on the implementation • Finally the power correction must be stored in OUTPUT_LIST_DL_PC_CCH PWR_BASKET –= f(AGG-Xi, PWR_REDi) PSDi = PSD_UE_CTRL + PWR_BOOSTi DL-PC-CCH “will take care of” the UEs which are assigned with too low AGGlevels (lowering AGG levels cannot be performed w/o PC for PDCCH enabled).
For internal use only 38 © Nokia Siemens Networks / Power relocation • Power relocation is always limited by the threshold (pdcchPcReloc) however the total power increase due to boosting and relocation cannot exceed pdcchPcBoost PWR_RELOCi = min(pdcchPcReloc, 10*log10(1+PWR_BASKET/(TOTAL_NUM_CCES*CCE_UTILIZATION))) PSDi = PSD_UE_CTRL + min(pdcchPcBoost, - PWR_REDi + PWR_BOOSTi + PWR_RELOC) …however it will never happen that the one and the same CCE is decided to be boosted and reduced at the same time (TTI).
For internal use only 39 © Nokia Siemens Networks / CQI reporting
For internal use only 40 © Nokia Siemens Networks / Several CQI Reporting Modes have been defined in 3GPP: •Periodic and Aperiodic CSI (Channel Status Indicator) •Aperiodic CSI reports are sent on PUSCH only •Periodic CSI reports can be setn either on PUCCH or PUSCH •The reporting mode of CSI also depends on DL transmission mode – Single Stream, Dual Tx (Alamouti), open loop spatial Mux, closed loop spatial mux) • CQI can be reported the follwing way – a) Wideband – over whole frequency range (like in UMTS HSDPA) – b) UE selected sub-band reporting – c) L3 configured sub-band reporting b) and c) needed to support „Downlink Frequency Domain Scheduling - DFDS“ DL Scheduler: CQI Reporting Modes
For internal use only 41 © Nokia Siemens Networks / DL Scheduler: CQI Reporting Modes CQI Reporting Aperiodic Periodic PUSCH PUSCH or PUCCH Wideband UE selected sub-band L3 configured sub-band Wideband UE selected sub-band 1-2 2-0 2-2 3-0 3-1 1-0 1-1 2-0 2-1 4,6 1,2,3,7 4,6 1,2,3,7 4,5,6 1,2,3,7 4,5,6 1,2,3,7 4,5,6 Rep Mode Trans Mode
For internal use only 42 © Nokia Siemens Networks / Aperiodic Reporting: (on PUSCH only) •Aperiodic reporting can be enabled/disabled on LNCEL level: cqiAperEnable •Reporting Mode can be controlled with LNCEL: cqiAperMode – FBT1 means UE selected sub-band reporting is used – FBT2 means L3 selected sub-band reporting is used • eNB can poll CQIs out of UE based on certain timer LNBTS: cqiAperPollT Periodic Reporting: (on PUCCH or PUSCH [multiplexed with data]) • cqiPerSimulAck controls whether UE need to report CQI simulatneous with HARQ ACK-NACK info • For combined wideband and sub-band reporting operator can instruct UE how many sub-band reports of a the bandwidth parts should be included between 2 consecutive wideband CQI reports: cqiPerSbCycK • cqiPerNb controls the frequency when UE shall deliver the periodic CQI reports • For transmission modes 3 and 4 UE needs to know where is the position to send Rank Indicator realtive to CQI report LNCEL: riPerM (default is „1“) defines multiplier for LNCEL: riPerOffset (default is „-1“) – Current default is „Rank Indicator shall be sent exactely 1 TTI before CQI is sent“ • eNB controls mode of reporting with LNBTS: cqiPerMode (Wideband only or Wideband and sub-band) DL Scheduler: CQI Reporting Modes
For internal use only 43 © Nokia Siemens Networks / • Periodic on PUCCH – Mode 1-0 wideband CQI rank indicator • Aperiodic on PUSCH – Mode 2-0 aperiodic on PUSCH wideband CQI one average CQI for M best subbands of size k – Mode 3-0 only for first codeword (in case of dual stream) wideband CQI one CQI for each subband (higher layer configured) CQI/RI/PMI reporting modes in RL10 System Bandwidth DL NRB Subband Size k (RBs) M 6 – 7 NA NA 8 – 10 2 1 11 – 26 2 3 27 – 63 3 5 64 – 110 4 6 System Bandwidth Subband Size DL NRB (k) 6 - 7 NA 8 - 10 4 11 - 26 4 27 - 63 6 64 - 110 8 Example: 10 MHz channel bandwidth (different colours stands for different reported CQI values) Mode 1-0 Mode 2-0 Mode 3-0 RL10 default config: Mode 1-0 + Mode 3-0
For internal use only 44 © Nokia Siemens Networks / Aperiodic (PUSCH) reporting 2-0 versus 3-0 • Mode 2-0 reports only average CQI over M best UE-selected subbands – Example: System bandwidth =10 MHz average CQI over the best 5x3=15 PRBs reported, no subband info for remaining 35 PRBs • Mode 3-0 reports the whole band for a set of subbands System Bandwidth DL N RB Subband Size k (RBs) M 6 – 7 NA NA 8 – 10 2 1 11 – 26 2 3 27 – 63 3 5 64 – 110 4 6 M = 3 best Subbands are selected and an average CQI value is reported Channel SINR Subband index 1 2 3 4 5 6 7 8 PRB index 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Best-M scheme Best-M scheme (2-0) Full subband CQI (3-0) System Bandwidth Subband Size DL NRB (k) 6 - 7 NA 8 - 10 4 11 - 26 4 27 - 63 6 64 - 110 8
For internal use only 45 © Nokia Siemens Networks / Memory rule for CQI report names • Reporting Mode x-y: – x denotes CQI frequency reporting type x=1 (wideband) x=2 (UE-selected best-M subbands) x=3 (eNB-selected subband size, reporting over entire band) – y denotes Precoding Matrix Indication frequency reporting type y=0 (no PMI reported) x=1 (one PMI reported, wideband) x=2 (multiple PMI reported, subband) • Rank Indicator is always wideband, i.e., single RI value per report • Example: Report 3-0 @20MHz system means that full-band CQI reporting using subband size of 8 PRBs ROUNDUP(100/8)=13 CQI values are reported. No PMI is reported. • PMI reporting only needed with closed-loop MIMO and rank-1 precoding transmission modes System Bandwidth DL N RB Subband Size k (RBs) M 6 – 7 NA NA 8 – 10 2 1 11 – 26 2 3 27 – 63 3 5 64 – 110 4 6 Best-M scheme (2-0) Full subband CQI (3-0) System Bandwidth Subband Size DL NRB (k) 6 - 7 NA 8 - 10 4 11 - 26 4 27 - 63 6 64 - 110 8