eNodeB Sleeping Algorithms

The Problem

An operator requested 3DB CONSULT experts to provide details on different algorithms, their use cases, benefit and impact to network KPI’s.

Explanation / 3dB consult recommendation

Using eNodeB sleep mode can noticeably decrease the energy consumption of LTE networks, especially in dense urban environments. There are different triggers for the eNodeB to enter hibernation: Power-aware, Traffic-aware and User Distance-aware algorithms.

Sleep Mode impact to network KPI’s:

  • Accessibility KPI: No impact
  • Retainability KPI: No impact, since the UEs that are moved by the Cell Soft Lock feature do not count towards the retainability KPI
  • Integrity KPI: End user performance quality in terms of latency, throughput and packet loss may be impacted, on those UEs being pushed out of a capacity cell entering sleep mode. After move to another cell, the UEs may be served by a cell that provides sub-optimal performance. However, once the capacity cell enters sleep state, and inter-cell interference is reduced, the performance of the UEs may benefit from decreased interference
  • Mobility KPI: No impact
  • Availability KPI: No impact. Cell sleep time will be excluded from pmCellDowntimeAuto, and therefore will not impact the Availability KPI. However, the new pmCellSleepTime counter will be introduced

The following tables explain Sleeping Mode parameters counters and events

MO name

Attribute name

Valid values

Description

CellSleepFunction SleepMode (RW) Activated, Deactivated.
(default Deactivated)
To turn on the feature per cell.
CellSleepFunction CoverageCellDiscovery (RW) True, false
(default false)
This indicates the Automatic Coverage Cell Discovery capability for sleep mode support. EUtranCellRelations with SleepModeCoverageCandidate=AUTO and ALLOWED will be considered as part of discovery. EUtranCellRelations found applicable as coverage cells will have SleepModeCoverageCell set to true. Note: EUtranCellRelations with SleepModeCoverageCandidate=NOT_ALLOWED will not be considered as coverage cells.
CellSleepFunction sleepStartTime (RW) Format in ASCII-code: hh:mm hh = 00-23 mm = 00-59
(default 02:00)
RBS daily start time to perform antenna muting detection or switching.
CellSleepFunction sleepEndTime (RW) Format in ASCII-code: hh:mm hh = 00-23 mm = 00-59
(default 05:00)
RBS daily end time to stop antenna muting detection or switching.
CellSleepFunction CapCellDlPrbSleepThreshold (RW) 0-100
(default 10)
This is a threshold to sleep the capacity cell. The capacity cell must be below this DL PRB Usage percentage threshold to enter sleep state.
CellSleepFunction CapCellRrcConnSleepThreshold (RW) 0-3000
(default 5)
This is a threshold to sleep the capacity cell. The capacity cell must be below this number of active RRC connections to enter sleep state.
CellSleepFunction CapCellSleepMonitorDurTimer (RW) 5-120
(default 15)
Minimum duration for this cell to satisfy the configured load thresholds before entering sleep state. Used in the Cell Sleep Mode feature. (minutes)
CellSleepFunction CovCellDlPrbWakeUpThreshold (RW) 0-100
(default 60)
This is a threshold to wake-up the capacity cell. At least one of the coverage cells must exceed this DL PRB Usage percentage threshold to wake-up this capacity cell.
CellSleepFunction CovCellRrcConnWakeUpThreshold (RW) 0-3000
(default 500)
This is a threshold to wake-up the capacity cell. At least one of the coverage cells must exceed this number of active RRC connections to wake-up this capacity cell.
CellSleepFunction CovCellWakeUpMonitorDurTimer (RW) 5-120
(default 15)
Minimum duration for coverage cell to satisfy the configured load thresholds before the capacity cell can wake-up. Used in feature Cell sleep mode. (minutes)
EUtranCellRelation SleepModeCovCellCandidate (RW) ALLOWED, NOT_ALLOWED or AUTO.
(default AUTO)
Sleep Mode Coverage Cell candidate status. The value indicates whether the cell indicated by this cell relation can be used as coverage cell for cell sleep mode support.
ALLOWED for basic sleep support.
ALLOWED/ AUTO for coverage cell discovery evaluation.
EUtranFreqRelation cellSleepCovCellMeasOn (RW) true, false
(default true)
Cell Sleep Mode performs measurement on the referenced frequency for coverage cell discovery if this parameter is set to true. Otherwise, Cell Sleep Mode does not perform any measurements on this frequency. 
CellSleepNodeFunction csmEutranInterFMeasReportMax (RW) 0…1000 decMeasurementReports
(default 800)
Defines the maximum target number of cell sleep mode measurement reports per hour for each EutranFreqRelation. The number of measurement reports may deviate from the target. 
CellSleepNodeFunction csmEutranInterFMeasReportMin (RW) 0…1000 decMeasurementReports
(default 40)
Defines the minimum target number of cell sleep mode measurement reports per hour for each EutranFreqRelation. The number of measurement reports may deviate from the target. 
CellSleepNodeFunction csmEutranInterFMeasReportIncr (RW) 0…1000 decMeasurementReports
(default 10)
Defines the increase in the target number of periodic measurement reports for each EutranFreqRelation when the required hit-rate to identify cell sleep mode coverage cells is not achieved yet. 
CellSleepNodeFunction csmEutranInterFMeasReportDecr (RW) 0…1000 decMeasurementReports
(default 20)
Defines the decrease in the target number of periodic measurement reports for each EutranFreqRelation when the required hit-rate to identify cell sleep mode coverage cells is achieved. 
CellSleepFunction SleepState (RO) Activated, Deactivated.
(default Deactivated)
This indicates if the sleep state of the cell. 
EUtranCellRelation SleepModeCapacityCell (RO) True, false.
(default false)
The value indicates whether the cell of this relation is a dependent capacity cell for cell sleep mode support.
EUtranCellRelation CovCellDlPrbWakeUpThreshold (RO) 0-100
(default 60)
This is a minimum threshold to wake-up the capacity cell, as sent by the capacity cell.
EUtranCellRelation CovCellRrcConnWakeUpThreshold (RO) 0-3000
(default 500)
This is a minimum threshold to wake-up the capacity cell, as sent by the capacity cell.
EUtranCellRelation SleepModeCoverageCell (RO) True, false
(default false)
The value indicates whether the cell of this relation is a coverage cell for cell sleep mode support.

Counters:

PM counter

Description

Use case

pmCellSleepTime

This counter reports the amount of time the cell is in cell sleep state.  Unit: 1 sec. Counter Type is ACC (or PEG).

Length of time the cell has been disabled due to sleep mode support (operational state set to disabled). The counter is only incremented when the RBS is operational and the cell sleep mode feature has been activated.

Events:

PM event

Description

Use case

INTERNAL_PROC_CELL_SLEEP_TRIGGERED

Triggered whenever the cell is about to enter sleep state. This event is reported on capacity cells enabled with cell sleep mode.

This indicates the time a cell enters sleep state.

INTERNAL_EVENT_CELL_WAKEUP_TRIGGERED

Triggered whenever the cell is about to exit sleep state. This event is reported on capacity cells enabled with cell sleep mode.

This indicates the time a cell exits sleep state. Could be used to conclude the amount of time a cell stay in sleep state, use to collect relevant power measurements.

INTERNAL_EVENT_CELL_WAKEUP_DETECTED

Triggered whenever the cell has found opportunity to wake-up a sleeping capacity cell. This event is reported on coverage cells supporting cell sleep mode.

This indicates coverage cell has detected wake-up opportunity and therefore signals dependent capacity cells to activate.

X2_CELL_ACTIVATION_REQUEST

X2_Cell_Activation_Request message received or sent. See 3GPP 36.423

This indicates the occurrence of the X2 message.

X2_CELL_ACTIVATION_RESPONSE

X2_Cell_Activation_Response message received or sent. See 3GPP 36.423

This indicates the occurrence of the X2 message.

X2_CELL_ACTIVATION_FAILURE

X2_Cell_Activation_Failure message received or sent. See 3GPP 36.423

This indicates the occurrence of the X2 message.

X2_PROPRIETARY_CELL_SLEEP_START_REQUEST

A EAB (Proprietary) X2 Cell Sleep Request message with Start indicator was sent/received

This indicates the occurrence of the X2 message.

X2_PROPRIETARY_CELL_SLEEP_STOP_REQUEST

A EAB (Proprietary) X2 Cell Sleep Request message with Stop indicator was sent/received

This indicates the occurrence of the X2 message.

X2_PROPRIETARY_CELL_SLEEP_RESPONSE

A EAB (Proprietary) X2 Cell Sleep Response message was sent/received

This indicates the occurrence of the X2 message.

X2_PROPRIETARY_CELL_SLEEP_FAILURE

A EAB (Proprietary) X2 Cell Sleep Failure message was sent/received

This indicates the occurrence of the X2 message.

INTERNAL_EVENT_COV_CELL_DISCOVERY_START

Triggered when coverage cell discovery starts for a particular capacity cell.

This indicates the coverage cell discovery for a capacity cell has started.

INTERNAL_EVENT_COV_CELL_DISCOVERY_UPDATE

Triggered when an operational cycle for coverage cell discovery ends (i.e. 24 hours) for a particular capacity cell.

This provides an update to whether coverage cells have been discovered or updated successfully for a capacity cell to provide cell sleep mode support.

INTERNAL_EVENT_COV_CELL_DISCOVERY_END

Triggered when coverage cell discovery is stopped, due to feature reconfiguration.

This indicates the coverage cell discovery for a capacity cell has stopped.

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