Amendment Proposal for TV White Spaces Operation

1. Amendment Proposal for TV White Spaces Operation Date:March 18, 2010 Authors:

2. Introduction The technical issues raised in this proposal Spectral Efficiency Issue based on IEEE 802.11n Channelization Issue Scanning Issue Slide 2

3. Technical Issues Available Spectrum VHF (54~72, 76~88, 174~216 MHz), UHF (470~698Mhz) Advantages of TVWS Smaller propagation loss than 2.4GHz or 5GHz Robust against diffraction loss Lower Doppler  Extended Coverage, Low Power Consumption, Robust Link Quality Application Scene Home multimedia streaming Seamless WLAN WLAN service for Public Area(e.g, Airport, Hotel, Conference Hall , Campus area, or Church) Slide 3

4. Technology Throughput enhancement Required for home multimedia streaming Spectral Efficiency Channelization (e.g., 5MHz/10MHz/20MHz) Low power consumption Required for seamless WLAN Scanning Submission Slide 4

5. Spectral Efficiency IEEE 802.11n-based standard In order to improve spectral efficiency Utilizing 802.11n features A-MPDU that leads to reduce PHY overhead should be applied, especiallynecessary for 5MHz channel bandwidth in TVWS Advanced FEC coding such as LDPC can be employed Number of utilizing tones should be 56 (52 data tones and 4 pilot tones) Submission Slide 5

6. Bandwidth Adaptation 802.11af shall support 5MHz/10MHz/20MHz Channelization Center frequency at the center of 6MHz TVWS channel Optimal for 5MHz channel bandwidth But, for 10MHz/20MHz, available number of channels should be 3/5, respectively * Reference: R. Chandra, R. Mahajan, T. Moscibroda, R. Raghavendra, and P. Bahl, “A Case for Adapting Channel Width in Wireless Networks” ACM SIGCOMM 2008. Submission Slide 6

7. Bandwidth Adaptation • Channelization of TVWS spectrum • Center frequency at the boundary of 6MHz TVWS channel • Not appropriate for 5MHz channel bandwidth • However, 2/4 TVWS channels are enough for 10MHz/20MHz operation, respectively • Therefore, AP should choose the carrier frequency and the channel bandwidth according to the available spectrum • STA should scan AP with the frequency raster of 3 MHz Submission Slide 7

8. Scanning Number of scanning channels in TVWS The candidate channels are almost 30 (=180MHz/6MHz) when one channel bandwidth is 5 MHz Considering 10MHz/20MHz channel bandwidth, the number of channels that STA should scan are tripled (around 90). Large initial access delay of Passive Scanning Scanning time might be around 9,000ms i.e., 3 (Number of candidate bandwidth) x 30 (Number of candidate channels) x 100ms (Beacon Interval) Power consumption Power consumption depends on the number of scanning channels Submission Slide 8

9. Scanning • Multi-band mode • STA can use other links and TVWS link as well as a control link to discover AP and get the TVWS MAP information • White Space Map specifies the channel list unoccupied by the primary users • They can be 802.11a/b/g/n/cellular link or TVWS link • TVWS MAP transmission • Within beacon frame • Within response frame requested by STA • Can be transmitted in 802.11a/b/g/n/cellular or TVWS link

10. Scanning • Multi-band mode • Coverage difference between other links and TVWS link • Due to carrier frequency characteristics • There are often coverage holes of 2.4GHz WLAN • Relative link budget difference is around 9~12dB (TVWS link vs. 2.4GHz link) • Due to System parameter

11. Scanning • Multi-band mode • - Seamless WLAN service

12. Scanning Cold Start mode In a very initial state, or after certain elapsed time, in which STAs do not have TVWS channel information, STAs scan whole TVWS channels Or STAs get TVWS channel information from other than TVWS link Warm Start mode STAs scan TVWS channels from the last operation with available TVWS channel list, i.e. warm start mode STAs need not always scan whole TVWS channels STAs need not receive control information via 2.4GHz/5GHz link In a warm start mode, STA shall scan TVWS channels based on TVWS information received from AP during last operation

13. Scanning • White space map within Beacon Frame • White space map is provided by beacon frame • White Space Map specifies the channel list unoccupied by the primary users • Once STA listens to beacon frame, STA doesn’t need to scan channels occupied by incumbent users • By skipping the channels occupied by incumbent users , initial access delay and power consumption problem can be resolved a little. • However, it can be some overhead for beacon frame. Submission Slide 13

14. Scanning • White space map within Response Frame • AP provides White Space Map information to STA for reducing the scanning overhead • White Space Map is transmitted within Response Frame • Response frame can be probe response frame

15. Scanning Extended Measurement pilot Enabling message contains TVWS map and power constraint information Enabling message can be measurement pilot with TVWS MAP and power constraint information Measurement pilot transmission with shorter interval than beacon interval Submission Slide 15

16. Conclusion • Public safety band, unlicensed band, cellular band and TVWS band are allowed to be used for control signaling for TVWS operation • TVWS MAP information is proposed to be transmitted to STA within beacon frame, probe response, and/or measurement pilot • Measurement pilot is proposed to be extended to contain TVWS MAP information and power constraint information

17. Straw Poll 1 Do you support public safety bands, unlicensedbands, cellular bands and TVWS bands are allowed to be used for control signaling of TVWS bands operation? Yes No

18. Straw Poll 2 Do you support enabling STA/enabling AP that act as a master devices transmit TVWS MAP information to dependent STA? Yes No

19. Straw Poll 3 Do you support measurement pilot is required to be extended to contain TVWS MAP information and power constraint information? Yes No