KPI Impact:
Throughput: high values increase the throughput for near cell and mid-cell conditions.
Capacity - high values allow reaching the capacity for a wider range of propagation conditions.
Coverage - high values might reduce the coverage if the target is not dynamically adjusted based on propagation conditions.
Mobility - might negatively impact the throughput during handover if the threshold is set too high.
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8.3.1 T115590- SUPPORT OF MULTI-RRH PER CELL (ONE LOGIC CELL) FOR INDOOR COVERAGE
8.3.1.1 HIGH LEVEL DESCRIPTION AND BENEFITS:
Traffic and Capacity in Hotspots are increased very fast, which makes it very important to improve coverage and capability in Hotspots, this is real challenge.
Indoor scenario is a typical Hotspot with high traffic and capacity requirements but hard to provide good coverage and satisfied QoE.
Figure 8.3-1: Typical wireless network example
Figure 8.3-2: Key challenges of wireless network - coverage and capacity
The feature T115590 Multi-RRH in one cell can be applied for indoor environment typically. It can enlarge the coverage of indoor within one logical cell and reduce frequent handover opportunity.
And this feature also can be applied for the tiding service scenario between different areas.
This is also for CMCC requirements on multi-RRH connected to one cell feature for indoor deployment. In order to satisfy customer’s requirements, we plan to support multi-RRH with one cell in TLA6.0.
One BBU with 1~3 bCEM boards, up to 4 RRH 2x20w (10M or 20M) for one cell (1 bCEM); up to 6 RRH2x20w (10M or 20M) for one BBU.
Dense Outdoor Hot Spots
Indoor Hot Spots
Rural Areas Residential
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LTE/IRC/APP/032749 V06.03 / EN Approved Standard 28/Oct/2013 Page 59/290 Figure 8.3-3: One logical cell typical architecture
8.3.1.2 HOW TO ACTIVATE:
The feature is license controlled by O&M with parameter isMultiRrhEnabled set to “true”.
For feature activation, the initial step is to ensure that the following parameters are set as exemplified:
Table 8-18: Parameters to activate feature
8.3.1.3 FEATURE IMPACTS ON ENB & TUNABLE PARAMETERS:
Feature Impacts on eNB
In TLA6.0, the architecture for this feature shall be based on 1S8A package on bCEM, DLS and ULS are performed as 2A case.
The main eNB impacted Subsystems are summarized below:
Callp:
Object Attribute Value
CellActivationService isMultiRrhEnabled true
CellActivationService isInterTransmissionModeSwitchingEnable
d disabled
LteCellTDD spare3 . bit #2 (isOneLogicCellEnabled) 1 (true)
CellL1ULConfTDD antSubArrayGroupingScheme {0,1,2,3,4,5,6,7
}
CellL1ULConfTDD l1ReceiverMethod MRC
LteCellTDD numberOfDLAntennas dlAntenna2
LteCellTDD numberOfULAntennas ulAntenna2
LteCellTDD transmissionMode TM2/3/4
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L2 DL scheduler:
Same as 2A processing + add 1 bitmap in scheduling info (RRH index for ACK/NACK receiving on PUCCH)
UE RRH index table, based on PRACH or SRS report Use 2A power setting, ignore real antenna number
Reset to initial status if change of RRH index (SINR, RI, CQI, MCS, BLER control…) L2 UL scheduler:
UE RRH index table from L1 report, PRACH or SRS
Power Control, ulTxPowerIncreasedFor2Rrh – add on target SINR or subtracted from estimated SINR used by power control if multi RRH
RRH index change – reset to initial status (PUCCH SINR, PUSCH SINR, SRS SINR…) L1:
RRH area detection modules are added in SRS processing and selected RRH index(es) for each UE shall be reported to L2 ULS
Related thresholds about PUSCH processing shall be updated according to the number of receive antennas for the UE
For PUCCH receiver in DSP, perform PUCCH signal as 2A or 4A case for each UE and corresponding thresholds, shall also be read from corresponding tables (2A table or 4A table) according to RRH index information of the UE. DSP also handles the processing of ACK/NACK, PCQI/SR on PUCCH based on RRH index information (got from SRS processing or PRACH reporting).
The detail impacts on eNB please refer to doc [4].
This feature focuses on improving coverage and capacity for Indoor LTE deployments.
Tuneable Parameters
Ideally some exercise should be defined for tuning some of the parameters… in this case; (default values presented below).
Object Attribute Value Range Default
Value
MultiRrh areaIsolationForMultiRrh [0,…,9] 6
ulTxPowerIncreasedFor2Rrh [0.0,…,5.0] 0.0 LteCellTDD spare4 . bits #28~29
(servingRrhPowerGapMargin) [1,2,3] 2 Table 8-19: Tuneable parameters
9 ACCESS OPTIMIZATION HINTS
In this chapter it will be highlighted the main focus of testing and the primary steps that will allow to optimize a specific domain and the most important /priority parameters; in this case the domain addressed is access in LTE.
Normally some questions arise, such as:
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What method to apply?
Which parameters can help improving access to the network?
Mainly the Access optimization can occur when the attach success rate is below the ALU KPI As main indicator to evaluate the performance several tests to access the network should be performed; although before starting playing with the parameterization; usually is part of best practice rules for in Near Cell /Mid Cell & Cell Edge test to follow up simple steps as:
Check the CQI
Evaluate RSSI vs. SNR relation Evaluate RSRP vs. RSRQ
If we could guarantee that these values are “normal”, the chances to have performance issues are much less difficult to occur.
If regardless of the correct values, still facing some performance issues, the below parameters can be used in order to correct the situation.
When changing parameters; you can adopt a more error-free approach, meaning that a parameter is changed at each time. If three or four parameters are changed same time… it could be difficult to understand which one is bringing the improvement in performance.
As note; please remember that this can be a static test in each position, or can be a moving test…
the same principles can be applied in both situations.