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Transcript of Co Bcch Cell
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
www.huawei.com
Huawei Dualband Co-BCCH
Cell Introduction
Huawei RNP & RNO
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Basis
Why
How
3.
1.
2. What
4.
5. Risk
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Basis
Distance from
cell antenna
S
ignalStrength
(dBm)
-95
-75
0.5 km 1 km
GSM900
DCS1800
MS REPORTED RXLEV
GSM900
GSM1800
MS Can't Measure RXLEV
Different path loss
Co-BCCH Introduct ion
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What
Concentric Cell
Enhanced Concentric Cell
Co-BCCH Cell
Common BCCH Cell , also cal led GSM900&DCS1800, Mult i -band cel l ;
Based on Enhanced Concentr ic Cell Algo r i thm;
UL provid es BCCH, SDCCH,PDCH and TCH channels,
wh i le OL on ly prov ides the TCH channels
UL(GSM 900) carries BCCH, SDCCH, PDCH & TCH, For Coverage
OL(DCS 1800) contains only TCH, For Traffic Load
Co-BCCH Introduct ion
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Why
Frequency restrict:
The frequency resource doesnt support high configuration
Improve capability:
UL and OL share the BCCH, SDCCH, PDCH, and the TCH
channels will be increased accordingly Simplify network structure:
Reduce number of cells in the network
Reduce number of neighboring cells
Simplify multi-layer network into one layer network
Co-BCCH Introduct ion
GSM900 BCCH
SDCCH/TCH
DCS1800 TCH
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How
TCH Assignment procedure
Handover procedure
Base on: RxlevRxqualTA
Specially: Classmark 3 which has higher priority than TA\Lev\Qual
If did not know classmark 3, only assign the BCCH GSM900 BCCH
SDCCH/TCH
DCS1800 TCH
Co-BCCH Introuct ion
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5 steps
CellType Co-CellProperty
Avoid blind assignment failurearose by single band MSSet Enhanced
Co-cell Allowed
Be adjacent to itself
automatically
Enable BSC
getting MRs of UL
when MS is
occupying TCH
on OL.
Cell Parameter Sett ing
Activate Co-BCCH Cell
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Assign Optimum Layer
System optimization is recommended in Co-BCCH Cell, which indicates thesystem selects the optimum layer for TCH assignment as according to uplink
signal strength in MRs provided through the UL's SDCCH
Assign-Optimum-Level Thrsh.
Range: 0~63, (-110dBm~-47dBm). 28-35 is recommended
TA Thrsh. of Assignment Pref. Range: 0~255. 63 is recommended
UL Rx-Lev > Assign-Optimum-Level Thrsh. &
TA < TA Thrsh. Of Assignment Pref.
UL Re-Lev < Assign-Optimum-Level Thrsh. Or
TA > TA Thrsh. Of Assignment Pref.
OL ULSystem
optimization
Mode
Cell Parameter Sett ing
Assignment
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Handover
Parameters Value
UL to OL HO Allowed Yes
OL to UL HO Allowed Yes
Rx_Lev for Concentric Cell HO Allowed Yes
OL to UL HO received level Thrsh. 20
UL to OL HO received level Thrsh. 30
Rx_Qual for Concentric Cell HO Allowed No
Receiving Quality Thrsh. 60
TA Concentric Cell HO Allowed No
TA Thrsh. 63
TA hysteresis 0
UL to OL Traffic HO Allowed No
Traffic Thrsh. of underlaid 70
Underlaid HO Step period 5
Underlaid HO Step level 5
OL subcell UL subcell
DL Rx-Lev >= U to O HO received level Thrsh.&
DL RxQual < Receiving Quality Thrsh. &
TA < (TA Thrsh. - TA Hysteresis) &
Traffic in Underlay > Traffic Thrsh. of underlay
DL Rx-Lev < O to U HO received level Thrsh. or
DL Rx-Qual >= Receiving Quality Thrsh. or
TA > (TA Thrsh. + TA Hysteresis)
Cell Parameter Sett ing
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Pref. subcell in HO of intra-BSC
Range: System Optimization, OL, UL
Recommended: UL. UL is preferred during the intra-BSC HO.
Incoming-to-BSC HO optimum layer
Range: UL, OL
Recommended: UL. UL is preferred during the incoming-to-BSC HO.
ULOL
UL configured for incoming
handover
Setp1: Handover into UL is
preferred
Setp2: If UL is busy enough, handover
into OL is performed
Setp3:DLRx-Lev of OL is weak,
return to source cell
Cell Parameter Sett ing
Handover
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Properly setting OL to UL HO received level Thrshand UL to OL HO received
level Thrsh.
Penalty Time of UL to OL HO (s): When handed over from UL to OL, If "Penalty
allowed" set to "Yes", system will forbidden MS to handover back to the UL during
the "Penalty Time of UL to OL HO (S)". Range:0~255(s)
Disable intra-cell handover
OL
ULUL to OL HO received level Thrsh.
OL to UL HO received level Thrsh.
Hysteresis1800M users
900M & 1800M users
900M users RX_LEV_ACCESS_MIN
Hysteresis (typical value is 8-12dB) =
UL to OL received level Thrsh. -OL toUL received level Thrsh.
The higher the hysteresis, the fewer the
ping-pong HO between UL and OL, also
traffic distribution will be changed.
Cell Parameter Sett ing
Protection against Ping Pong HO
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Summary
Parameters for Assignment Control
ParametersRecommended
ValueDetails
Assign optimum
layer
System
optimization
1.system optimization: traffic distribution can be changed to adapt real traffic
model by tuning Assign-Optimum-Level Thrsh, which can preventing
congestion on UL, while make good use of OL.
2.UL: calls will be assigned to UL.3.OL: calls will assigned out of OL coverage
Assign-Optimum-
Level Thrsh.23-28
1.Valid if Assign optimum layer is setSystem optimization.
2.The lower the parameter, the more calls assigned in OL. However, TCH
Assignment success rate may decrease.
TA Thrsh. ofAssignment Pref.
63 Valid if Assign optimum layer is setSystem optimization.
Optimization for Assignment
Traffic Optimization Strategy
Optimization ResultsUL OL
Assign optimum
layer
Assign-Optimum-
Level Thrsh.
congested idle System optimization Congestion HSR Ass-Succ may
normalSlightly
congestedSystem optimization Congestion HSR Ass-Succ
idle congested Underlaid subcell Congestion HSR Ass-Succ
Cell Parameter Sett ing
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Parameters for Handover Control
ParametersRecommended
ValueDetails
Pref. subcell in HO of intra-BSCsystem
optimization
UL: keep good handover performance
system optimization: balance UL and OL traffic
Incoming-to-BSC HO optimum layer ULUL: keep good handover performance
OL: maybe out of OL coverage, risk exists.
Rx_Lev for Concentric Cell HO Allowed YesDetermine whether the receiving level or quality of
downlink, or TA is taken as the judgment condition in
the Concentric Cell handover judgment. Rx_Lev isabsolutely necessarily. Quality and TA is optional.
Rx_Qual for Concentric Cell HO Allowed Yes
TA Concentric Cell HO Allowed No
UL to OL Traffic HO Allowed NoDetermines whether the traffic in UL is one of conditions
for OL to overlaid handover.
Optimization for handover
Issues of Co-BCCH CellPref. subcell in HO of intra-BSC Optimization Results
UL OL
congested idle System optimization Congestion Ass-Succ
idle congested UL Congestion Ass-Succ HSR
SummaryCell Parameter Sett ing
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Parameters for Concentric Handover
ParametersRecommended
ValueDetails
OL to UL HO
received level
Thrsh.
20~30
1.The parameter is DL RxLev.
2.Keep at least 10dB difference between OL to UL HO received level Thrsh
and UL to OL HO received level Thrsh in order to avoid Ping Pong HO.
UL to OL HO
received level
Thrsh.
30~40
1.The parameter is DL RxLev.
2.The value should be greater than Assign-Optimum-Level
Thrsh. ,because the difference between uplink RxLev and downlink RxLev.
Optimization of concentric handover
Issues of Co-BCCH Cell
Optimization Strategy
Optimization ResultsUL to OL HO
received level
Thrsh.
OL to UL HO
received level
Thrsh
UL is congested, OL is idle Congestion HSR DCR
UL is idle, OL is congested
Congestion HSR DCR
UL >OL HSR is low
HSR DCR
OL >UL HO times is low, DCR is high
Congestion HSR DCR
OL>
UL HSRs are low.
Congestion HSR DCR
SummaryCell Parameter Sett ing
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2. Have to constantly adjust handover parameters to minimize inter-layer
handovers (different cells have different RF environment, morphologyand traffic load).
Solution : For a period Operation & Maintain of COBCCH network, we
can provide formula base on traffic and Key counters.
3. When GSM900 cell experience outage (faulty BCCH TRX, faulty circuit
packs), DCS1800 cell cannot absorb the traffic (lost revenue).
Solution: Configure more than one 900M TRX in the underlay sub-cell,
if BCCH TRX fault, another 900M TRX will replace it.
Co-BCCH Introduct ion
Risk
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Restriction
Dont support different band frequency in one frequency hopping
sequence
Support GPRS in each band, but PDCH must be allocated on TRX
whose frequency band is same to BCCH
Flexibility is not so good as 900-1800 co-site cell
Co-BCCH Co-Site
Co-BCCH Introduct ion
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Thank You