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Feasibility of White Space in Metropolis Cities: A Case Study in Hong Kong

Feasibility of White Space in Metropolis Cities: A Case Study in Hong Kong. Lichao YAN CUHK Minghua CHEN CUHK Ranveer Chandra Microsoft. What are White Spaces?. -60. “White Spaces” are unoccupied TV channels Primarily UHF ~ 470-806 MHz (channel 21-62 )

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Feasibility of White Space in Metropolis Cities: A Case Study in Hong Kong

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  1. Feasibility of White Space in Metropolis Cities: A Case Study in Hong Kong Lichao YAN CUHK Minghua CHEN CUHK RanveerChandra Microsoft

  2. What are White Spaces? -60 • “White Spaces” are unoccupied TV channels • Primarily UHF ~470-806 MHz (channel 21-62) • Must protect TV and wireless microphone “White spaces” dbm 470 MHz 800 MHz -100 Covered by TV signal TV “White Space” Frequency Department of Information Engineering, CUHK

  3. Previous Measurement Work Goal of white space network: meet the rapidly increasing demands for spectral capacity Dynamically identify currently unused portions of spectrum Configure radio to operate in available spectrum band Dublin Chicago Washington New York Guangzhou More Spectrum up to 3x of 802.11g • Foundation of white space deployment: identify which bands are underutilized Singapore Signal Strength Longer Range at least 3 - 4x of Wi-Fi Signal Strength • 1. Field measurement: accurate, but high cost • 2. Propagation modeling: low cost, but may suffer white space lost Frequency Frequency Large amount of white spaces exist in TV band Department of Information Engineering, CUHK

  4. Previous Measurement Work Dublin Chicago Washington New York Guangzhou Singapore Limitations: • Focus on the time-varying nature of spectrum usage • Measured a few and fixed locations Department of Information Engineering, CUHK

  5. Distributed Measurement in Hong Kong • Complex geographical environment in HK • We obtained informative data from 31 locations • Both outdoor and indoor environments have been measured • In indoor environment, we explored more white space opportunities Department of Information Engineering, CUHK

  6. Hardware Device : USRP + Antenna + Laptop Department of Information Engineering, CUHK

  7. Software Defined Radio : Feature Detection Department of Information Engineering, CUHK

  8. Software Defined Radio : Analog TV Feature Detection Analog TV signal (PAL) is identified by the location of its video carrier in frequency domain Department of Information Engineering, CUHK

  9. Software Defined Radio : Digital TV Frame header structure, PN420 (PN945) The front and rear synchronizations are cyclic extensions of the PN255 sequence with the length of 217 symbols PN correlation method is adopted for DTV detection Department of Information Engineering, CUHK

  10. White Spaces Lost by Propagation Modeling Department of Information Engineering, CUHK

  11. TV Signal Occupancy Summary Outdoor Indoor Department of Information Engineering, CUHK

  12. Outdoor TV signal Occupancy Summary Urban area : occupancy rate from 57 to 69% Suburban area:occupancy rate from 43 to 52% Rural area: occupancy rate below 40% Department of Information Engineering, CUHK

  13. Indoor White Space Opportunity Analysis Outdoor occupancy rate statistics Remote area Urban area Indoor occupancy rate statistics Remote area Urban area Department of Information Engineering, CUHK

  14. Indoor White Space Opportunity Analysis Remote area Urban area • Counter-intuitively, indoor white space rate doesn’t decrease in urban area, which is the area has most spectrum demands Conclusion: There are plenty of indoor spectrum resource that has not been fully explored • Approximately 80% of spectrum demands come from indoor environment Department of Information Engineering, CUHK

  15. The Fraction of Contiguous Available Channels • These indoor white spaces have commercial value, for it is a potential methodto solve spectrum shortage problem. • Currently, we are trying to find possible solutions to make the indoor white space fully utilized. • More contiguous channels emerge indoors which provide a much better communication environment. Department of Information Engineering, CUHK

  16. Discussions of the Digital Switch-Over in HK • After the transition, about 40% of TV channels will be released in urban area and this percentage is 30% and 15% in suburban and rural area • Spectrum pattern can be rearranged to be more neat and make the available channels contiguous. Department of Information Engineering, CUHK

  17. White space rate in HK, Europe and USA Department of Information Engineering, CUHK

  18. White Space Rates by Thresholds Department of Information Engineering, CUHK

  19. Spectrum Usage Rates VS Population Densities Department of Information Engineering, CUHK

  20. Conclusions • Outdoor occupancy rate distributes unevenly in Hong Kong. The closer to the urban area, the less white spaces • The indoor white spaces have different pattern characteristics with outdoor environment. Business potential exists in this area • Currently digital channels only occupy a small fraction of whole spectrum. Much more spectrum resource will be released after the digital switch over Department of Information Engineering, CUHK

  21. Thanks! Department of Information Engineering, CUHK

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