1. 120 MHz PHY Transmission Date: 2010-07-12 Authors: January 2010
doc.: IEEE /0084r3
120 MHz PHY Transmission
Date:
Authors:
Brian Hart, Cisco Systems

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

3. Abstract
The 120 MHz PHY transmission is proposed for ac to efficiently support the 5 GHz spectrum of China.

4. Background
802.11ac will support wider bandwidth than n in 5 GHz frequency band.
In the May 2010 Beijing meeting, the 160 MHz PHY transmission is accepted in the ac specification framework.
Compared with 40/80 MHz transmisstion, 160 MHz PHY transmission has the following advantages
Reduce the complexity requirement which allows wider range of devices to achieve Gigabit wireless throughput.
Achieve more efficient data transmissions
Increase the coverage of ac networks
Enable more applications

5. only 125 MHz availabe in China
Motivation
Unfortunately, 160MHz bandwidth around 5 GHz is not available worldwide.
In China, the total bandwidth available for WLAN systems around 5 GHz is 125 MHz (5,725 ~ 5,850 MHz). Obviously, the 160 MHz transmission cannot be used in China.
Chinese users cannot enjoy the advantages of wider bandwidths, which may reduce the competitiveness of 11ac.
Compared with other regions’ users, Chinese users have to experience higher complexity, worse performance, less device types, and less applications.
160 MHz PHY Transmission
only 125 MHz availabe in China
5,725 MHz
5,850 MHz
35 MHz

6. Motivation China is the biggest potential market of 802.11ac
More than 700 million mobile phone users
More than 400 million Internet users
More than 400 million TV sets, which is the potential market of wireless display applications.
Chinese telecommunication operators are promoting 3G + WLAN programs into practice, and have deployed a large number of WLAN hotspots in China.
Therefore, it is very necessary for ac to define a PHY transmission which is suitable for the Chinese 5GHz spectrum.

7. 120 MHz PHY transmission
Following the Chinese spectrum and the existing 11ac tone allocations, we propose ac to support the 120 MHz PHY transmission.
The 120 MHz PHY transmission can be realized by multiple approaches (need to be further studied)
Combine three 40 MHz channels
Combine an 80 MHz channel with a 40 MHz channel
Design a single 120 MHz channel …

8. Achieving 1 Gbps and higher throughput
120 MHz transmission can achieve 1 Gbps throughput with lower order MIMO and MCS.
# Streams
MCS BW
#data tones / symbol
MAC Throughput* 8
256-QAM 3/4
40 MHz
108
1.01 Gbps
16-QAM 3/4
80 MHz
234
1.09 Gbps 6
64-QAM 2/3 4
16-QAM 1/2
120 MHz
324
16-QAM 2/3 3
1.13 Gbps
In this Table, we assume the 120 MHz bandwidth is composed of three 40 MHz channels.
More than 3 Gbps throughput can be obtained when 8 streams, 256 QAM, and 3/4 channel code are adopted.

9. Main advantages
120 MHz PHY transmission has the following major advantages:
Achieve better and more robust performance
Increase the coverage of ac networks
Reduce the implementation cost
Allow additional types of devices to achieve 1 Gbps throughput and thus may enable new applications
Increase the data throughput by 50%, compared with 80 MHz transmission
Achieve more than 3 Gbps and support uncompressed 1080p video transmission.

10. Summary
A 120 MHz PHY transmission mode is proposed for ac to efficiently support the 5 GHz spectrum of China, which is very important to promote ac applications in China.
The 120 MHz PHY transmission mode can
achieve 1 Gbps throughput with lower order MIMO and MCS,
increase data throughput by 50%, compared with 80 MHz transmission,
support more than 3 Gbps data transmission, e.g., uncompressed 1080p video stream.
The 120 MHz PHY transmission can be implemented by multiple solutions, which need to be further studied.
three 40 MHz channels
an 80 MHz channel + a 40 MHz channel
a single 120 MHz channel …

11. Strawpoll #1
Do you support adding the following section and item into the specification framework document, 11-09/0992?
Section MHz PHY Transmission
R3.1.2.A: The draft specification shall include support for 120 MHz PHY transmission.
Yes:
No:
Abstain:

12. References 11-10-0378-01-00ac-160-mhz-phy-transmission
ac-proposed-specification-framework-for-tgac