Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: Why Bad Channels Should Not Be Used In The Adapted Hop Sequence Date Submitted: 12 November 2001 Source: Vitaliy Sapozhnykov, HongBing Gan, Bijan Treister, Greg Ellard , Efstratios Skafidas Bandspeed Inc. AddressLevel 9, 500 Collins St., Melbourne 3000, Victoria, Australia Voice:+61 3 9614 6299 FAX: +61 3 9614 6699 E-Mail:{v.sapozhnykov, h.gan, b.treister, e.skafidas}@bandspeed.com.au gellard@bandspeed.com Re: [] Abstract: Reasons why bad channels should not be present in the adapted hop sequence are provided Purpose:This document may be used for a discussion on whether Bad channels should or shouldn’t be used in the adapted hop set. Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Bandspeed Inc.

2. Why Bad Channels Should Not Be Used In Adapted Hop Sequence V. Sapozhnykov H. Gan B. Treister G. Ellard E. Skafidas Bandspeed Inc.

3. Outline of presentation • Introduction • Definitions • Channel Usage Regulations • Theoretical Benefit From Bad Channels Usage • Example: Inquiry Scan/ Inquiry. Time to Hear A Wake-Up Frequency • Added Complexity From Bad Channels Usage • Summary Bandspeed Inc.

4. Introduction The objective of this document is to describe the reasons why Bad channels should not be used in an Adaptive Frequency Hopping system. Bandspeed Inc.

5. Definitions • NBN : Number of Bad channels to be removed legally from the hopping sequence • NG : Number of Good channels Bandspeed Inc.

6. Channel Usage Regulations • US : Frequency hopping device must hop over minimum 75 hop channels (NBN = 4) • Europe : Frequency hopping device must hop over minimum 20 hop channels (NBN = 59) • Japan : No restriction on the minimum number of hop channels NPRM proposal : Frequency hopping device must hop over minimum 15 hop channels (NBN = 64) So, the Intelligent Usage of Bad channels (IUB) is for the cases when 0 < NG < 15 Bandspeed Inc.

7. Theoretical Benefit From Bad Channels Usage Percentage of GG channel pairs (NBN = 64) % NG Bandspeed Inc.

8. Theoretical Benefit From Bad Channels Usage (2) • To get somehow reasonable benefit from IUB the NG must be significantly smaller than 15, but • For new members of the piconet: establishing a new connection becomes problematic (reminder: AFH is accomplished in the CONNECTION state only) Bandspeed Inc.

9. Theoretical Benefit From Bad Channels Usage (3) • For current members of the piconet (members of AFH session): all the members of AFH session must periodically return to the original (non- adapted) hop set to reclassify the hop channels and to perform mutual exchange of their channel classification tables. This exchange becomes problematic using original hop set when the NG < 15. Bandspeed Inc.

10. Example: Inquiry Scan/ Inquiry.Time To Hear A Wake-Up Frequency (FH sample data. Second set. Bluetooth Baseband Spec.) Channels 1 - 68 are Bad Good channels 74, 78, and 76 appear in time instances 0xD000, 0xE000 and 0x11000. Bandspeed Inc.

11. Example: Inquiry Scan/ Inquiry.Time To Hear A Wake-Up Frequency (2) Scanning device would hear a wake- up frequency in ~33.283s. There is a possibility that a page/ inquiry hop set does not contain any good channelswhen the number of Good channels is less than 15: (inquiry hop set spans 32 frequencies out of 64) – an example is a 1st set of frequency hopping sample data, Bluetooth Baseband Specification v.1.1. Bandspeed Inc.

12. Added Complexity From Bad Channels Usage Implementation of an IUB algorithm adds extra complexity in terms of: • Extra gates • Extra time • time for understanding/ modeling (to support different links- ACL, SCO and states- sniff, park, hold an IUB algorithm may become extremely complex) • time for implementing (coding, debugging etc) • time for testing Bandspeed Inc.

13. Summary • The FCC laws are likely to be changed • According to NPRM proposal up to 64 Bad channels may be replaced by Good channels • To justify an IUB, the number of Good channels must be significantly smaller than 15 • When NG < 15 communications through the original (non- adapted) hop set becomes very complicated. So establishing a new connection for new members of the piconet and mutual exchange of channel classification tables Bandspeed Inc.

14. Summary (2) • for the current members of the piconet becomes • problematic • Implementation of an IUB adds extra complexity in terms of additional gates (hardware) or code (software) and development time Usage of Bad channels in the adapted hop sequence is not feasible. Bandspeed Inc.