1. RF Feasibility of 120 MHz Channelization for China
January 2010
doc.: IEEE /0084r3
RF Feasibility of 120 MHz Channelization for China
Date:
Authors:
Brian Hart, Cisco Systems

2. January 2010
doc.: IEEE /0084r3
Brian Hart, Cisco Systems

3. Abstract
In this presentation, we analyze the RF feasibility of 120 MHz channelization in China and show it totally meets the 5 GHz RF regulation of China.
Based on huge market demands, we strongly propose ac to support an efficient channelization for China.

4. Motivation
Different from other regions, China has a unique 125 MHz bandwidth (5,725 ~ 5,850 MHz). The channelization schemes for other regions are obviously inefficient for China.
A 120MHz channelization can significantly improve the frequency utilization in China.
However, if 120MHz channelization is adopted, only 5 MHz bandwidth can be used as guard sidebands, which may produce too much out-of-band radiation.
In the following, we will analyze the RF feasibility of 120 MHz channelization.

5. China’s RF regulation in 5 GHz band
June 2010
doc.: IEEE /xxxxr0
China’s RF regulation in 5 GHz band
The major RF requirements are as follows:
Frequency range: 5,725 ~ 5,850 MHz
Total transmit power: ≤ 27dBm (500mW)
The maximum PSD: ≤ 13dBm/MHz , ≤ 19dBm/MHz (EIRP)
Out-of-band radiation (EIRP): ≤ -80dBm/Hz (-20dBm/MHz)
According to the EVM document, the total TX power shall be limited to no more than 17 dBm (50mW), which is 10 dB lower than China’s requirement (27dBm). It means
there is a 10dB back-off advantage for the PSD of ac signals, so it is much easier for 120MHz transmission to meet the spectral mask of China.
Brian Hart, Cisco Systems

6. 5GHz spectral mask in China
The maximum PSD (EIRP) ≤ 19 dBm/MHz
6dB
The maximum PSD ≤ 13 dBm/MHz
7dB
The average PSD ≤ 6 dBm/MHz
10dB
The average PSD of 11ac ≤ -4 dBm/MHz
16dB
Out-of-band radiation
≤ -20dBm/MHz
125 MHz
5,725 MHz
5,850 MHz

7. 802.11n spectral mask for 40 MHz channel
The n spectral mask is much sharper than the Chinese requirement.
120MHz transmission can directly meet the Chinese regulation without any additional operations.

8. Simulation parameters
For further study, we need a specific 120 MHz channelization scheme. In our simulation, we simply assume it consists of three 40 MHz 11n channels.
According to the EVM document, the total transmit power is 17dBm (50mW), and the resulting average PSD over 125MHz is -4 dBm/MHz.
The power amplifier (PA) model and the phase noise model given in the EVM document are adopted.
Different OFDM symbols have different frequency-domain characteristics. We consider three kinds of OFDM symbols with different guard intervals.
Normal GI: TGI = TDFT/4 = 0.8 us
Short GI: TGIS = TDFT/8 = 0.4 us
Double GI: TGI2 = TDFT/2 = 1.6 us

9. PSD of 120 MHz transmission using normal GI
June 2010
doc.: IEEE /xxxxr0
PSD of 120 MHz transmission using normal GI
Brian Hart, Cisco Systems

10. PSD of 120 MHz transmission using short GI

11. PSD of 120 MHz transmission using double GI

12. Maximum TX power of 120 MHz transmission
The out-of-band radiation of 120MHz transmission is 7.5 ~ 8.5 dB lower than the China’s RF requirement.
If necessary, the total TX power (EIRP) can be further increased to improve performance and coverage by
employing directional antennas, or
simply increasing transmit power
If the PA model remains unchanged, then we have
Normal GI
Short GI
Double GI
Max. TX power growth
8.0 dB
7.5 dB
8.5 dB
Max. of average PSD (EIRP)
4 dBm/MHz
3.5 dBm/MHz
4.5 dBm/MHz
Max. TX power (EIRP)
25.0 dBm
24.5 dBm
25.5 dBm

13. Why 802.11 needs 120 MHz channelization
June 2010
doc.: IEEE /xxxxr0
Why needs 120 MHz channelization
China is the biggest potential market for
More than 700 million mobile phone users
More than 400 million Internet users
More than 400 million TV screens (wireless display applications)
To develop the Chinese market, a very fundamental requirement is to make standards compatible with the Chinese spectrum regulation.
120 MHz channelization provides a really good opportunity to significantly increase the entire industry’s revenue.
Brian Hart, Cisco Systems

14. June 2010
doc.: IEEE /xxxxr0
Conclusion
It is shown that 120 MHz channelization completely meets the Chinese spectrum regulation.
We reemphasize how important the Chinese market is for standards.
We strongly propose ac to support an efficient channelization for China, where the total available channel bandwidth is up to 120 MHz.
Brian Hart, Cisco Systems

15. References 11-10-0778-01-00ac-120-mhz-phy-transmission
IEEE n standard
ac-proposed-specification-framework-for-tgac
ac-tgac-functional-requirements-and-evaluation-methodology

16. Strawpoll #1-1
Do you support adding the following item into Section 3.1 “Channelization” in the specification framework document, 11-09/0992r13?
R3.1.E: The draft specification shall include support for an efficient channelization in China’s (5,725 ~ 5,850 MHz) spectrum.
Yes:
No:
Abstain:

17. Strawpoll #1-2
Do you support adding the following item into Section 3.1 “Channelization” in the specification framework document, 11-09/0992?
The total bandwidth of the channels defined for China shall be equal to or not less than 120 MHz.
Yes:
No:
Abstain: