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How big is a passive picocell ?

How big is a passive picocell ?. David Wake BT Laboratories UK. 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

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How big is a passive picocell ?

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  1. How big is a passive picocell ? David Wake BT Laboratories UK

  2. 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 ?

  3. 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)

  4. 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

  5. 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 CENTRAL SITE REMOTE SITE laser downlink fibre E A M photo diode uplink fibre

  6. demonstration system PSTN DECT base unit optical source picocell multiplexer + circulator dual fibre link radio LAN access point optical receiver Ethernet central site passive base station passive optical transceiver

  7. what are the benefits ? • simple installation • low maintenance • multiband, multisystem • easily reconfigured and upgraded • simple dynamic radio resource control • low total network cost ?

  8. 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, ...

  9. 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)

  10. 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

  11. 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

  12. cell size equations

  13. results - DCS1800

  14. results - UMTS

  15. 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

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