RND Guidelines900-1800

8/3/2019 RND Guidelines900-1800

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Radio NW Design

Guidelines GSM900

Link Budget & Coverage Thresholds


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Agenda

Equipment Characteristics

Cell Coverage Definition

Margins

Design Levels

Coverage acceptance tests

Cell Planning

Propagation Model Power Budget

Power Balance

Cell Size


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Site Equipment

Base StationMaximum Range Standard High Capacity

Max Output power Hybrid comb Filter comb

46.5 dBm 41.5 dBm 44.5 dBm

2 TRU/ant 4 TRU/ant Up to 12 TRU/ant

Mobile Station

MS power class Output power [dBm] Sensitivity [dBm]

2 39 -106

3 37 -106

4 33 -104

5 29 -104


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Site Equipment

Base Station Antenna

Mobile Station Antenna


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Apart from feeders, additional losses arise in jumpers and connectors

Typical values are 0.5 dB for every jumper and 0.1 dB per connector

Site Equipment

Feeders & jumpers

External Diplexer 0.3 dB


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Additional losses to be accounted for include body loss,interference loss, & Rayleigh fading

Cell Coverage

When planning the coverage of a cell it is not sufficient toconsider the MS/BTS sensitivity as planning criterion


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Cell Coverage

Design levels are chosen according to the environment andclutter type


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Cell Coverage

Apart from fast fading, the signal fluctuates in a way that deviatesfrom the global mean according to a normal distribution, thuscalled Log-Normal distribution


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Cell Coverage


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Cell Coverage

Log Normal fading margins for indoor environments

LNF(o+i) = (LNF(o)2 +LNF(i)2)

For Indoor coverage:
http://coverage-cellsize.xls/


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Cell Coverage

Coverage Acceptance Tests

The aim of such tests is to measure signal strength (SS) and estimatewhether the received signal corresponds to requiredSS

Note that power control downlink should be switched off during test

Make sureyou drivetest withpowercontrol

off


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Cell Planning

Propagation model

The standard model is Okumura Hata model:

Lb = 69.55 + 26.16 logf13.82 logHBa(HM) + (44.96.55 logHB) log d

Valid for: 150 f 1500 MHz

HB = base station antenna height [m]

1 d 20 km R = distance from transmitter [km]

30 hb 200 m HM = mobile station antenna height [m]

1 hm 10 m a(HM) = 3.2(log11.75HM)2 - 4.97; a (1.5) = 0

The cell range is the distance R corresponding to maximum allowed pathloss Lpathmax:

R = 10^a, where a = [Lpathmax - Kr + 13.82logHB + a(HM)]/[44.9 - 6.55logHB]


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Cell Planning

Propagation model

For Urban cells (range less than 1km), COST 231 model is used:

Lpath = 143.2 + 38logR18log(HB 17) [dB]

According to Walfish-Ikegami, the cell range is :

R = 10^a, where a = [Lpathmax - 143.2 + 18log(HB17)]/38


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Cell Planning

Power Budget

Power budget calculates how much power enters a receiver from

a set output power at the transmitter

DL: PinMS = PoutBTS Lf+jLTMA + GantLslantLpath

UL: PinBTS = PoutMS Lpath + Gant + Gdiv Lf+j


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TMA case

Assuming path loss on uplink equals path loss on downlink :

PoutBTS

= PoutMS

+ Gdiv

+ Lf+j

+ LTMA

+ Lslant

+ PinMS

- PinBTS

Cell Planning

Power Balance

When uplink is stronger, the output power of the BTS should be set to maximum. If downlink

is stronger then BTs output power should be adjusted to calculated balanced output power.

sens= Mssens BTSsens= PinMS PinBTS

Path balance implies that

the coverage on uplink path is

equal to coverage on the

downlink path


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Cell Planning

Power Balance

No TMA case

PoutBal = PoutMS + Gdiv + Lslant + sens

The corresponding EIRP is calculated as:

EIRP = PoutBal- Lf+j + Gant- Lslant
http://thingstodo/PBalanceb1.xls


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Cell Planning

Cell Size

R = 10^ ,

where = [LpathmaxA + 13.82logHB + a(HM)]/[44.96 .55logHB]

Lpathmax = EIRP

SSdesign


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Questions & Answers

RND Guidelines900-1800

Documents