LTE DL Operation Highlights: Similarities to HSPA

• Shared Channel Operation

• CDS (Channel Dependent Scheduling)
–Requires Channel Quality Information (CQI) sent on the UL
–Requires Pre-coding and Rank information sent on the UL for MIMO
• AMC (Adaptive Modulation and Coding)
–Requires informing the UE about allocated Resources
–Requires informing the UE about Modulation and Coding Schemes (MCS)
• HARQ (Hybrid ARQ)
–Uses Asynchronous adaptive retransmissions
–Uses Synchronous ACK/NAKs
–Requires ACK/NAK sent on the UL
• DL Modulation: QPSK, 16-QAM, 64-QAM

• Multiple Access Dimensions:
• DL Scheduler:
–Assigns Time/Frequency resources, rather than Time/Code resources
–May coordinate with neighbor Base Stations for interference management.
• DL Reference Signals (Pilots):
–Have fixed time duration and frequency sub-band allocations.
• ARQ runs at E-NodeB
–ARQ architecture is conceptually similar to HSPA. (It supports TM, UM, and
AM modes and retransmissions are based on status reports.)
–Optional HARQ assisted ARQ operation is possible in LTE.
• Multiple PDSCH Tx Modes
- Requires different Channel Quality Reporting, acknowledging and scheduling mechanisms

LTE ACK/NACK for PDSCH Transmissions

The UE shall, upon detection of a PDSCH transmission in subframe n-4 intended for the UE and for which an ACK/NACK shall be provided, transmit the ACK/NACK response in subframe n.

CQI/PMI/RI and ACK/NACKs multiplexing on PUCCH is possible:
• Format 2:
– CQI/PMI/RI not multiplexed with ACK/NAK
• Format 2a/2b
– CQI/PMI/RI multiplexed with ACK/NAK (normal CP)
• Format 2:
– CQI/PMI or RI multiplexed with ACK/NAK (extended CP)
ACK/NACK for PDSCH Transmissions
The UE shall, upon detection of a PDSCH transmission in subframe n-4
intended for the UE and for which an ACK/NACK shall be provided,
transmit the ACK/NACK response in subframe n.
ACK/NACKs alone can be delivered PUCCH format 1a and 1b

LTE E-UTRA UL Channels and Signals

Signals

• Demodulation Reference Signal (DM-RS)
• Sounding Reference Signal (SRS) Control
• ACK, CQI, Rank Indicator (RI), Precoding support (PMI)
• Scheduling Request (SR)
• Single “control” channel
- Physical Uplink Control Channel (PUCCH) Data
• Unicast data and data + control
• Single “data” channel
- Physical Uplink Shared Channel (PUSCH) Random access
• Preamble sequences in Physical Random Access Channel (PRACH)

LTE E-UTRA Uplink Reference Signals

•Two types of E-UTRA/LTE Uplink Reference

Signals:
• Demodulation reference signal
– Associated with transmission of PUSCH or PUCCH
– Purpose: Channel estimation for uplink coherent demodulation/detection of the uplink control and data channels
– Transmitted in time/frequency depending on the channel type (PUSCH/PUCCH), format, and cyclic prefix type
• Sounding reference signal
– Not associated with transmission of PUSCH or PUCCH
– Purpose: Uplink channel quality estimation feedback to the uplink scheduler (for Channel Dependent Scheduling) at the e-NodeB
– Transmitted in time/frequency depending on the SRS bandwidth and the SRS bandwidth configuration (some rules apply if overlap with PUSCH and PUCCH)

Notes
•The same set of base sequences is used to generate demodulation and sounding reference signals
•The base sequences and the reference signals are derived from Zadoff-Chu sequences
•Cyclic shifts can be applied to a base sequence to obtain multiple reference signal sequences

LTE Physical Uplink Control Channel (PUCCH)

Physical Uplink Control Channel (PUCCH)

The physical Uplink control channel, PUCCH, carries Uplink control information (UCI), and is never transmitted simultaneously with the PUSCH from the same UE.
A maximum of 4 resource blocks are reserved for PUCCH in this example. The physical resources used for PUCCH depend on parameters given by higher layers.
The following combinations of Uplink control information (UCI) are supported on PUCCH:

  > HARQ-ACK using PUCCH format 1a or 1b
  > Scheduling request (SR) using PUCCH format 1
  > HARQ-ACK and SR using PUCCH format 1a or 1b
  > CQI/PMI or RI using PUCCH format 2
  > CQI/PMI or RI and HARQ-ACK using PUCCH format
       – 2a or 2b for normal cyclic prefix
       – 2 for extended cyclic prefix

LTE Sounding Reference Signals (SRS)

 

SRS shall be transmitted at the last symbol of the subframe.

PUSCH:
• The mapping to resource elements only considers those not used for transmission of reference signals.
PUCCH Format 1a and 1b (HARQ-ACK):
• One SC-FDMA symbol on PUCCH shall be punctured.
PUCCH Format 1 (SR) and 2, 2a, 2b (CQI):
• A UE shall not transmit SRS whenever SRS collide with PUCCH format 1 (SR), and 2, 2a and 2b (CQI).

 

Sounding Reference Signals
Details about UE sounding procedure can be found in TS36.211 and TS36.213 §8.3.
The reference signal sequence shall be multiplied with the amplitude scaling factor and mapped
resource elements. The resource element mapping shall be in increasing order of first k, then l, and finally the slot number.

There are many FDD sounding reference signal subframe configurations as per TS36.211 §5.5.3.3.
The sounding reference signal shall be transmitted at the last symbol of the subframe according to 36.211.
A UE shall not transmit SRS whenever SRS and CQI transmissions happen to coincide in the same subframe.
A UE shall not transmit SRS whenever SRS and SR transmissions happen to coincide in the same subframe.
When a UE is configured by higher layers to support both A/N and SRS transmissions in the same subframe, then the UE shall transmit A/N using a shortened PUCCH format where the A/N symbol corresponding to the SRS location is punctured.

LTE relation with CDMA2000 Parameter

Parameter Name	Parameter Description	Default Value
Cdma2000CellRelationId	The value component of the Relative Distinguished Name (RDN).
externalCdma2000CellRef	Reference to a ExternalCdma2000Cell.
includeInSystemInformation	Indicates if the CDMA2000 cell referred to is included in System Information. When the includeInSystemInformation is set to false, the CDMA2000 cell is not  included in SIB8. A maximum of 32 CDMA2000 cells can be included in SIB8.	true
freqCdma	Identifies the carrier frequency within a CDMA2000 Band.
Cdma2000FreqId	The value component of the Relative Distinguished Name (RDN).
reservedBy	Contains a list of MO instances that reserve this MO instance.
Cdma2000FreqBandId	The value component of the Relative Distinguished Name (RDN).
hrpdBandClass	The CDMA-HRPD frequency band in which the HRPD carrier is located.
reservedBy	Contains a list of MO instances that reserve this MO instance.
Cdma2000FreqBandRelationId	The value component of the Relative Distinguished Name (RDN).
cdma2000FreqBandRef	Reference to the Cdma2000 frequency band MO, Cdma2000FreqBand.
threshXHighHrpd	The threshold used in reselection towards a high priority CDMA2000 HRPD band class, expressed as an unsigned binary number equal to FLOOR ([-2 x 10 x log10 Ec/Io]) in units of 0.5 db. If sNonServingCell > threshXHighHrpd, reselection is considered towards the band class with higher priority. The condition must be valid during the period defined by attribute tReselectionCdmaHrpd. sNonServingCell is the RX-level value of a neighboring cell.	63
threshXLowHrpd	The threshold used in reselection towards a low priority CDMA2000 HRPD band class expressed as an unsigned binary number equal to FLOOR ([-2 x 10 x log10 Ec/Io]) in units of 0.5 db. If sServingCell < threshServingLow and sNeighbor > threshXLow (see corresponding attribute), reselection towards this lower prioritized band class is considered. The condition must be valid during the period defined by attribute tReselectionCdmaHrpd. sServingCell is the RX level value of the serving cell and sNeighborCell is the RX level value of a neighbor frequency.	63
cellReselectionPriority	Absolute priority of the RAT (0 means: lowest priority).	6
Cdma2000FreqRelationId	The value component of the Relative Distinguished Name (RDN).
connectedModeMobilityPrio	Prioritizes CDMA2000 frequencies among all frequencies related to the cell for UEs in connected mode. (0 means the lowest priority)	6
qOffsetFreq	Indicates a frequency-specific offset to apply when evaluating triggering conditions for measurement reporting.	0
cdma2000FreqRef	Reference to the Cdma2000Freq MO
Cdma2000NetworkId	The value component of the Relative Distinguished Name (RDN).

LTE ANR Parameter

Parameter Name	Parameter Description	Default Value
AnrFunctionId	The value component of the Relative Distinguished Name (RDN).
cellAddRankLimitEutran	Threshold value for reported rank for a cell to be automatically added as neighbor.	1
cellAddRsrpOffsetEutran	Threshold offset value for reported power for a cell to be automatically added as neighbor.	-10
cellAddRsrpThresholdEutran	Threshold value for reported power for a cell to be automatically added as neighbor.	-1440
cellAddRsrqOffsetEutran	Threshold offset value for reported quality for a cell to be automatically added as neighbor.	-10
cellAddRsrqThresholdEutran	Threshold value for reported quality for a cell to be automatically added as neighbor.	-1920
hoAllowedEutranPolicy	Starting value of the attribute isHoAllowed when a EUtranCellRelation is created by Automated Neighbor Relations (ANR).	true
removeNcellTime	The length of time that neighbor cells without any neighbor relations remain in the RBS. 1000 means no automatic removal is performed. If set to 0, the neighbor cell MO is removed within 1 minute.	30
removeNenbTime	The length of time that neighbor RBSs without any neighbor cells remain in the RBS. 1000 means no automatic removal is performed. If set to 0, the neighbor RBS MO is removed within 1 minute.	7
removeNrelTime	The length of time that neighbor relations without any communication to the neighbor cell remain in the RBS. 1000 means no automatic removal is performed. If set to 0, the neighbor relation MO is removed within 1 minute.	30
x2SetupPolicy	Indicates if X2 is set up when an ExternalEnbFunction not in the x2BlackList is created by Automated Neighbor Relations (ANR).	true
anrUesEUtraIntraFMax	The maximum target number of UEs in each cell that are assigned Automated Neighbor Relations (ANR)-specific thresholds for E-UTRAN intra-frequency neighbor cell reports. The actual number of UEs with these thresholds may deviate from the target.	20
anrUesEUtraIntraFMin	The minimum target number of UEs in each cell that are assigned Automated Neighbor Relations (ANR)-specific thresholds for E-UTRAN intra-frequency neighbor cell reports. The actual number of UEs with these thresholds may deviate from the target.	1
anrUesEUtraIntraFDecr	The decrease in the target number of UEs in each cell that are assigned Automated Neighbor Relations (ANR)-specific thresholds for E-UTRAN intra-frequency neighbor cell reports, every time a neighbor cell report is received with only known neighbor cells.	10
anrUesEUtraIntraFIncrHo	The increase in the target number of UEs in each cell that are assigned Automated Neighbor Relations (ANR)-specific thresholds for E-UTRAN intra-frequency neighbor cell reports, every time a neighbor cell report for handover is received with unknown neighbor cells.	100
anrUesEUtraIntraFIncrAnr	The increase in the target number of UEs in each cell that are assigned Automated Neighbor Relations (ANR)-specific thresholds for E-UTRAN intra-frequency neighbor cell reports, every time a neighbor cell report for ANR is received with unknown neighbor cells.	20

LTE Paging Parameter

Parameter Name	Parameter Description	Default Value
PagingId	The value component of the RDN.
maxNoOfPagingRecords	The maximum allowed number of paging records included in one Radio Resource Control (RRC) paging message. It is the allowed maximum number of UE that can be paged per paging occasion.	3
defaultPagingCycle	The paging cycle (also referred to as T) used by the RBS and broadcast in system information type 2. If the UE-specific Discontinuous Reception (DRX) cycle is provided in S1AP paging and has a smaller value than defaultPagingCycle, the UE-specific DRX cycle overrides defaultPagingCycle.	128
nB	Used to calculate the number and position of Paging Occasions (PO) and Paging Frames (PF). The numerical value of nB depends on the value of the defaultPagingCycle (T) and can be set to one of the following values: 4T, 2T, T, 1/2T,1/4T, 1/8T, 1/16T, 1/32T When nB is set to T, 2T or 4T, it determines the number of POs per PF, and the PO position in PF. When nB is set to a value smaller than T, it affects the System Frame Number of the PF, the position of PO in the PF, and also distribution of UE into groups with the same PF. When nB is set to a  smaller value, the groups are fewer but larger, or more but smaller.	T
pagingDiscardTimer	The length of time a received paging is retained or queued in the RBS before it is discarded. The timer should be set to the same (or smaller) value as the paging resend timer in MME (T3413). This setting  prevents the RBS from retaining or sending an old paging after the re-sent copy is received from the MME.	3

LTE Admission Control Parameter

Parameter Name	Parameter Description	Default Value
paArpOverride	Allocation Retention Priority level received from the Core Network that eNB interprets as the identifier for Privileged Access. The value zero will disable Privileged Access ARP override.	7
ulNonGbrRatio	This parameter sets the wanted uplink resource utilization ratio of Non-GBR bearers, e.g. for Mobile Broadband users, on transport network. The value given in this parameter specifies the Non-GBR part of the total bandwidth and the remaining part (1-ulNonGbrRatio) sets the GBR part of the total bandwidth. The parameter will be used by the Admission Control to balance GBR and Non-GBR use of resources.	500
dlNonGbrRatio	This parameter sets the wanted downlink resource utilization ratio of Non-GBR bearers, e.g. for Mobile Broadband users, on transport network. The value given in this parameter specifies the Non-GBR part of the total bandwidth and the remaining part (1-dlNonGbrRatio) sets the GBR part of the total bandwidth. The parameter will be used by the Admission Control to balance GBR and Non-GBR use of resources.	500
AdmissionControlId	The value component of the Relative Distinguished Name (RDN).
emergencyArpLimit	ARP (Allocation Retention Priority) value limit used for identifying ARP values that are considered to be part of the emergency (high priority) group. This limit value and all values below are considered to be of high priority. The value zero is introduced to turn off ARP handling.	7
nrOfBearersReserved	Number of bearers reserved for high priority group (bearers with low ARP values, Allocation Retention Priority values). Setting a high value for the reservation means low priority bearers will always be rejected.	0
nrOfRrcConnectedReserved	Number of RRC connections reserved for high priority UEs (handovers and where establishment cause is emergency). Setting a high value means non emergency UEs will always be rejected.	0
dlGbrAdmThresh	Admission threshold for load due to Guaranteed Bit Rate (GBR) bearers in the downlink, expressed as a fraction of the available resources.	1000
dlTransNwBandwidth	Downlink transport network bandwidth for LTE.	1000
ulGbrAdmThresh	Admission threshold for load due to Guaranteed Bit Rate (GBR) bearers in the uplink, expressed as a fraction of the available resources.	1000
ulTransNwBandwidth	Uplink transport network bandwidth for LTE.	1000