planning for radio coverage & capacity 2.0
TRANSCRIPT
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HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com
Huawei Confidential
Security Level:2013/4/19
Planning for RadioCoverage
&Capacity
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Content
Coverage planning
Three terms
Tool and case
Capacity planning
Three terms
Method and case
Relationship
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EIRP
BTS Set-top power
Balance of Uplink and Downlink
UL DL
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Propagation Model
Propagation model of free space (Lp=32.4+20logf+20logd)
Okumura-Hata model (Applying to forecast of 900M macro cell)
COST231-Hata model (Applying to forecast of 1800M macro cell)
COST231 Walfish Ikegami model
(Applying to forecast of 900M and 1800M micro cells)
Keenan-Motley model
(Indoor propagation model, applying to 900M and 1800M cells)
Common propagation model
Path Loss = f (frequency, distance)
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Communication Probability
Concept of communication probability
Success call rate of MS on the radio coverage border or in the cell
Category of communication probability
Edge coverage probability
Area coverage probability
margin
ProbabilityDistribution
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Tool
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Case
To construct a 900MHz Network in the suburb that requires about
100 square kilometer coverage acreage, -94dBm minimum
receiving level, and 91% edge coverage probability, forecast the
coverage distance and calculate the required quantity of BTSs.
Useful input information
Band: 900MHz
Network environment: suburb
Coverage acreage: 100km2
Efficient receiving level: -94dBm
Edge coverage probability: 91
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Traffic -Traffic Load
)(3600
TimeHoldingCallAvg.BHCABH@LoadTrafficAvg. Erlang
BHCA: Busy Hour Call Attempt
Definition:
Call exchange volume of a subscriber in a particular time
Unit:
Erlang
If traffic in 15 min is 0.2 Erl, then traffic in one hour is also about 0.2 Erl
when distribution of traffic is even
If traffic in 15 min is 0.2 Erl, then traffic in one hour is 0.240.8Erl
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GoS - Grade of Service
It is the probability of a call in a circuit group being blocked or
delayed for more than a specified interval.
Erlang-B equation of GoS
GOS=2% Urban GOS=5% Suburb
N
0K
K
N
K!A
N!A
ServiceofGrade
A = Expected traffic intensity in Erlangs N = Number of circuits in group
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Erlang-B
GOSElang
TRXNumber
1. The relation between
number of TCH and
expected traffic is not linear
2. Because the channel is
shared
3. This share condition
happed in cell.
So the number of channel is in
one cell and correspond to the
traffic load of per cell.
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Capacity Planning
Coverage
estimationNumber of site
Traffic model
Subscribers
Distribution
Traffic Load ofsystem
Channel
Configuration
Traffic Load
per site
Traffic Load
per cell
Erlang-BTRX
Configuration
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Case
A local network will be constructed. After two years, the number
of subscribers may attain 100,000. Provide that the traffic per
subscriber is 0.02Erl, 120 BTSs are required, and the call loss
rate is 2%.
Useful information
Subscriber quantity: 100,000
Call loss rate: 2%
Traffic model: 0.015Erl
Number of BTSs: 120
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Case Roaming factor (traffic and developing trend): 10%; dynamic factor
(burst traffic): 15%
Network capacity: 100,000(1+10%+15%)=125,000 In terms of congestion, use 85% to calculate the bearer capability for
traffic. Thus, the design capacity of network is: 125,000/(85%)=147100,
that is 150,000 approximately.
According to the provided traffic model, that is average 0.015Erl traffic,forecast the busy-hour traffic of the whole network: 150000
0.015=2250Erl. The average traffic per BTS is: 2250/120=18.75Erl, average traffic per cell:
18.75/3=6.25Erl.
Based on 2% call loss rate, query the Erlang-B to find the number ofvoice channels: 12channels/every cell
The number of control channels: 14 channels/every cell, 2TRX/every cell
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Relation
Pay attention to both coverage and capacity:
Coverage
Dimensioning
Coverage
area per Site
Traffic model
Subscribers
Distribution
Traffic Load
pre Site
TRX/Channel/
Configuration
Limitation
Judgment
Figure out the
max. configuration
Frequency
Planning
ChannelConfiguration
END
Traffic Load
per Site
Coverage
area per Site
Coverage
limitation
BTS Quantity
Capacity
limitation
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Method to enhance coverage
Increase the transmission power of BTS
Reduce the loss of combiner
Reduce the loss of feeder
Increase the gain of antenna
Add TMA
Improve Rx. sensitivity
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No balance
Allowed loss is greateron
downlink than on uplink Cannot access
Allowed loss is greater on
uplink than on downlink.
No signal to
MS
when uplink and downlink are not on balance,
Coverage areais equivalent tothe worse one.
Coverage of downlink
Coverage of uplink
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Channel Configuration 8 channels (i.e. time slots) per TRX
BCCH Configuration Only 1 BCCH per cell; TS0 of TRX0
TCH Configuration
No.SDCCH-No.BCCH8TCHofNo. n
SDCCH configuration suggestion
TRX No.Without CBCH With CBCH
Normal cell Inner cell Edge cell Normal cell Inner cell Edge cell
1 SDCCH/4 SDCCH/8
2 SDCCH/8 SD/8 + SD/4
3 SDCCH/8 + SDCCH/4
4 2*SDCCH/8 SD/8 + SD/4 2*SDCCH/8
5 2*SDCCH/8 2*SDCCH/8 + SDCCH/4
6 2*SDCCH/8 + SDCCH/4 2*SDCCH/8 2*SDCCH/8 + SDCCH/4
7 2*SDCCH/8 + SDCCH/4 3*SDCCH/8 2*SDCCH/8 + SDCCH/4 3*SDCCH/8
8 3*SDCCH/8 3*SDCCH/8 + SDCCH/4
Simply calculating:1 SDCCH/8 per 2 TRXs