RF Feasibility of 120 MHz Channelization for China January 2010 doc.: IEEE 802.11-10/0084r3 RF Feasibility of 120 MHz Channelization for China Date: 2010-09-14 Authors: Brian Hart, Cisco Systems

January 2010 doc.: IEEE 802.11-10/0084r3 Brian Hart, Cisco Systems

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 802.11ac to support an efficient channelization for China.

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.

China’s RF regulation in 5 GHz band June 2010 doc.: IEEE 802.11-10/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 802.11ac signals, so it is much easier for 120MHz transmission to meet the spectral mask of China. Brian Hart, Cisco Systems

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

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

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

PSD of 120 MHz transmission using normal GI June 2010 doc.: IEEE 802.11-10/xxxxr0 PSD of 120 MHz transmission using normal GI Brian Hart, Cisco Systems

PSD of 120 MHz transmission using short GI

PSD of 120 MHz transmission using double GI

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

Why 802.11 needs 120 MHz channelization June 2010 doc.: IEEE 802.11-10/xxxxr0 Why 802.11 needs 120 MHz channelization China is the biggest potential market for 802.11 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 802.11 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

June 2010 doc.: IEEE 802.11-10/xxxxr0 Conclusion It is shown that 120 MHz channelization completely meets the Chinese spectrum regulation. We reemphasize how important the Chinese market is for 802.11 standards. We strongly propose 802.11ac to support an efficient channelization for China, where the total available channel bandwidth is up to 120 MHz. Brian Hart, Cisco Systems

References 11-10-0778-01-00ac-120-mhz-phy-transmission IEEE 802.11n standard 11-09-0992-11-00ac-proposed-specification-framework-for-tgac 11-09-0451-14-00ac-tgac-functional-requirements-and-evaluation-methodology

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:

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: