mtm’99 workshop heidelberg, 25 february 1999 how big is a passive picocell ? david wake bt...
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![Page 1: MTM’99 Workshop Heidelberg, 25 February 1999 How big is a passive picocell ? David Wake BT Laboratories UK](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e3a5503460f94b2c797/html5/thumbnails/1.jpg)
MTM’99 Workshop
Heidelberg, 25 February 1999
How big is a passive picocell ?
David Wake
BT Laboratories
UK
![Page 2: MTM’99 Workshop Heidelberg, 25 February 1999 How big is a passive picocell ? David Wake BT Laboratories UK](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e3a5503460f94b2c797/html5/thumbnails/2.jpg)
MTM’99 Workshop
Heidelberg, 25 February 1999
introduction
• work is based on results of EURESCOM Project P816
– evaluation of technology for hybrid optical - radio networks
• passive picocell is one potential technology identified in this project
– novel concept using unpowered remote optical - radio transceiver
• important question: what is the radio range without amplifiers ?
– i.e. how big is a passive picocell ?
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MTM’99 Workshop
Heidelberg, 25 February 1999
outline
• what is a passive picocell ?
• how does it work ?
• what are the benefits ?
• what are the potential applications ?
• how big is a passive picocell ?
– second generation cellular (DCS1800)– third generation cellular (UMTS)
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MTM’99 Workshop
Heidelberg, 25 February 1999
what is a passive picocell ?
• a small radio cell formed using a fibre-supported antenna unit that is :
– small, light and unpowered
– multiband capable– upgradable and
reconfigurable from central location
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MTM’99 Workshop
Heidelberg, 25 February 1999
how does it work ?
• electroabsorption modulator transceiver
– acts as photodiode for downlink
– acts as modulator for uplink
– connected directly to antenna
– can operate without bias voltage
laserdownlink fibre
photodiode
EAM
uplink fibre
CENTRAL SITE REMOTE SITE
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MTM’99 Workshop
Heidelberg, 25 February 1999
demonstration system
central site
dual fibre link
Ethernet
PSTNpicocell
passive optical transceiver passive base station
radio LANaccess point
opticalreceiver
opticalsource
mul
tiple
xer
+ c
ircu
lato
rDECTbase unit
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MTM’99 Workshop
Heidelberg, 25 February 1999
what are the benefits ?
• simple installation
• low maintenance
• multiband, multisystem
• easily reconfigured and upgraded
• simple dynamic radio resource control
• low total network cost ?
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MTM’99 Workshop
Heidelberg, 25 February 1999
what are the potential applications ?
• indoor and outdoor
• public and private
• cellular, cordless, fixed radio access, wireless LAN
• picocells, microcells
• urban, in-building
• offices, factories, warehouses, railway stations, airports, sports stadia, ...
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MTM’99 Workshop
Heidelberg, 25 February 1999
how big is a passive picocell ?
• relies only on rf power available after photodetector
– optical system parameters used to compute power
• cell size depends on propagation environment and sensitivity of terminal
• two systems analysed (DCS1800 and UMTS)
• two propagation environments considered
– open, line-of-sight (power reduces with square of distance)
– cluttered, non line-of-sight (power reduces with cube of distance)
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MTM’99 Workshop
Heidelberg, 25 February 1999
important optical parameters
• EAM responsivity 0.3 A/W
• EAM efficiency 0.5 /V
• EAM insertion loss 7 dB
• photodiode responsivity 1 A/W
• fibre insertion loss 3 dB
• source optical power main variable
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MTM’99 Workshop
Heidelberg, 25 February 1999
important radio parameters
DCS1800 UMTS
• terminal transmit power +20 dBm +20 dBm
• terminal sensitivity -100 dBm -110 dBm
• optical modulation depth 20% pc 50% pc
• antenna gain 8.5 dB 8.5 dB
• fade margin 10 dB 10 dB
• path loss exponent secondary variable
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MTM’99 Workshop
Heidelberg, 25 February 1999
cell size equations
n
mr
amdmfod
fp
cgZMRgpr
/1
22
22222
....32
......
n
br
pmpmmfoamtu
fp
ZZRggpgcpr
/1
22
222422
....16
.........
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MTM’99 Workshop
Heidelberg, 25 February 1999
results - DCS1800
10.0
100.0
1000.0
0 10 20
optical power, mW
range,
m
NLOS
LOS
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MTM’99 Workshop
Heidelberg, 25 February 1999
results - UMTS
10.0
100.0
1000.0
0 10 20
optical power, mW
range,
m
NLOS
LOS
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MTM’99 Workshop
Heidelberg, 25 February 1999
conclusions
• emerging new technology for picocells
• important benefits
– installation, maintenance, upgrading, reconfiguring, dynamic resource allocation
• how big is the picocell ?
– DCS1800: 52m LOS 14m NLOS– UMTS: 374m LOS 52m NLOS
• powered version for larger range ?
• next major question - cost