1. LB97 CID 170 20-40 Coex Date: 2007-05-14 Authors: May 2007 May 2007
doc.: IEEE /0707r0
May 2007
LB97 CID Coex
Date:
Authors:
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John R. Barr, Motorola
John R. Barr, Motorola

2. May 2007
doc.: IEEE /0707r0
May 2007
Abstract
Summary of rational for not allowing use of 40 MHz channels in 2.4 GHz spectrum.
John R. Barr, Motorola
John R. Barr, Motorola

3. May 2007
CID 170
Comment: Allowing operation with 40 MHz channels in 2.4 GHz spectrum will not coexist with over 1 billion Bluetooth (IEEE a) devices present around the world. In addition, operation of 40 MHz channels in 2.4 GHz spectrum will be subject to high levels of interference from Bluetooth devices. With only 80 MHz allocated in 2.4 GHz spectrum allocation of half of that spectrum to a single WLAN limits access by other radios sharing that spectrum. Coexistence analysis shows a significant degradation of n performance in the presense of Bluetooth devices, even with significant separation. Many devices include both Bluetooth and making inteference even more significant. AFH defined in IEEE was designed to allow IEEE devices to reasonably avoid 20 MHz wide devices. None of the billion Bluetooth devices deployed at this time have been designed to avoid 40 MHz n devices.
Proposed Change:
Change “When using 40 MHz channels, it can operate in the channels defined in (Channel allocation in the 2.4 GHz Band) and (Channel allocation in the 5 GHz band)."
To "When using 40 MHz channels, it can only operate in the channels defined in (Channel allocation in the 5 GHz band)."
Also change other places in the draft that imply operation with 40 MHz channels in 2.4 GHz spectrum.
John R. Barr, Motorola

4. May 2007
Coexistence History
IEEE (IEEE Std ™-1999) was the incumbent wireless standard when IEEE (Bluetooth) was proposed as the first WPAN standard. (IEEE Std ™-2002)
IEEE Coexistence Task Group formed to resolve coexistence issues between and resulting in IEEE Std ™-2003 (Coexistence of Wireless Personal Area networks with Other Wireless Devices Operating in Unlicensed Frequency Bands):
“Because both IEEE Std b-1999 and IEEE specify operations in the same 2.4 GHz unlicensed frequency band, there is mutual interference between the two wireless systems that may result in severe performance degradation.”
AFH (Adaptive Frequency Hopping) implemented by the Bluetooth SIG to improve coexistence with devices:
Detects presence of 20MHz transmissions
Removes hopping channels overlapping with that 20MHz
John R. Barr, Motorola

5. Bluetooth® Wireless Technology Deployment
May 2007
Bluetooth® Wireless Technology Deployment
As of November 2006, over 1 Billion Bluetooth-enabled devices have been shipped.
Over 13 million new Bluetooth-enabled devices are being produced every week.
In 2009, over 1 Billion new Bluetooth-enabled devices are expected to be shipped.
All of these Bluetooth-enabled devices shipped since release of the v1.2 Bluetooth specification include AFH.
A typical high-tech mobile phone user typically owns four Bluetooth-enabled devices (phone, headset, laptop, automobile)
John R. Barr, Motorola

6. Bluetooth Use Case Example
May 2007
Bluetooth Use Case Example
Typical airport lounge (SFO Admirals Club):
In an 100x100 foot area there are the following:
5-10 people using their laptops on a T-Mobile Hot-Spot
1-2 of the laptop users are also talking on their mobile phones using a Bluetooth headset while they are typing
5-10 other people talking on their mobile phones using a Bluetooth headset.
None of the Bluetooth-enabled devices are co-located with an device
Laptop users and Bluetooth headset users do not notice any significant interference due to use of AFH by the Bluetooth devices.
John R. Barr, Motorola

7. Issues with 40 MHz 802.11n Channels
May 2007
Issues with 40 MHz n Channels
Bluetooth AFH only designed to detect and avoid 20 MHz channels. 1 Billion devices and counting…
If Bluetooth devices do not detect 40 MHz n channels due to lower power levels, then there are twice as many opportunities for a Bluetooth device to interfere with the n signal
Use of 40 MHz n in an area where Bluetooth-enabled devices are operating will significantly degrade their performance
John R. Barr, Motorola

8. May 2007
Recommendation
The Bluetooth SIG implemented AFH in their v1.2 release based on IEEE Std ™-2003 in order to peacefully coexist with IEEE deployments.
If n does not remove the ability to use 40 MHz channels in the 2.4 GHz spectrum, n should implement a non-collaborative method of detecting the presence of Bluetooth-enabled devices to prevent the use of 40 MHz channels in order to peacefully coexist with Bluetooth-enabled devices.
It is probably easier to just not allow use of 40 MHz channels in the 2.4 GHz spectrum.
John R. Barr, Motorola

9. References IEEE Std 802.11™-1999 IEEE Std 802.15.1™-2002
May 2007
References
IEEE Std ™-1999
IEEE Std ™-2002
IEEE Std ™-2003
John R. Barr, Motorola