1. Amendment Proposal for TV White Spaces Operation
Month Year
doc.: IEEE yy/xxxxr0
Amendment Proposal for TV White Spaces Operation
Date: February 28, 2010
Authors:
Name
Company
Address
Phone
Eunsun Kim
LG Electronics
Mobile Comm. Lab, LG R&D Complex 533, Hogye1, Dongan, Anyang, Korea
Yongho Seok
Mobile Comm. Lab, LG R&D Complex 533, Hogye1, Dongan, Anyang , Korea
Soonjoon Park
John Doe, Some Company

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

3. Technical Issues Available Spectrum Advantages of TVWS
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
Slide 3

4. Technology Throughput enhancement Low power consumption
Required for home multimedia streaming
Spectral Efficiency
Bandwidth Adaptation (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 n features
A-MPDU that leads to reduce MAC overhead should be applied, especially necessary for 5MHz channel bandwidth in TVWS
FEC coding 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 should 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
November 2009
Accelerate Contribution
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
Page 7
LG Electronics, Inc.

8. Bandwidth Adaptation
STA should dynamically change the channel bandwidth according to the service coverage and the supported channels
STA should also protect incumbent user signal by bandwidth adaptation
In order to support the bandwidth adaptation, the protection mechanism is required
Submission
Slide 8

9. 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, channels that STA should scan are tripled (around 90).
With 3MHz frequency raster for channelization, scanning channel list is doubled (around 180).
Massive initial access delay of Passive Scanning
Scanning time might be around 18,000ms
i.e., 3 (Number of candidate bandwidth) x 60 (Number of candidate channels with 3MHz frequency raster) x 100ms (Beacon Interval)
Power consumption
Power consumption depends on the number of scanning channels
Submission
Slide 9

10. 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, enhanced scanning mechanism is still desired such as active scanning
White space map within Probe Response
AP provides White Space Map information to STA for reducing the scanning overhead
White Space Map is transmitted within Probe Response Frame
However, probe request transmission power is constrained to 50mW
Submission
Slide 10

11. Scanning Limitation of active scanning
Active scan does not support complete scanning because EIRP is constrained to 50mW before associating with AP
Advanced scanning is required in TV Whitespace spectrum
Submission
Slide 11

12. Scanning Relaying probe request frame
Probe request frame can be relayed by other STAs in the vicinity of the STA transmitting probe request frame
By the help of other STAs, probe requesting STA can discover AP
However, data traffic could be possibly interrupted by the excessive probe request relaying frames, which are asked by STAs out of the service coverage of AP
Submission
Slide 12

13. Scanning Enhanced Scanning Mechanism
Power constraint information element should be transmitted with shorter interval than Beacon Interval
AP transmits Probe Setup Frame frequently than BI, which contains power constraint information element
STA can transmit probe request frame with max. allowable power according to power constraint information element within probe setup frame
Submission
Slide 13