1. September, 2001
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Adaptive Frequency Hopping - An Simple Instant Channel Replacement Approach for both ACL and SCO Links]
Date Submitted: [September, 2001]
Source: [H. Gan, V. Sapozhnykov, B. Treister, E. Skafidas, et. al.] Company [Bandspeed Inc.]
Address [Level 9, 500 Collins Street, Melbourne, Victoria, Australia]
Voice:[ , FAX: [ ]
[h.gan, b.treister,
Re: [A Simple Approach for Adaptive Frequency Hopping, as a non-collaborative coexistence mechanism]
Abstract: [This document describes a new simple approach for adaptive frequency hopping, an instant channel replacement to intelligently use bad channels in the hopping sequence]
Purpose: [Introducing a new approach for adaptive frequency hoping to include in ]
Notice: This document has been prepared to assist the IEEE P 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 P
H. Gan, V. Sapozhnykov, et. al.

2. September, 2001
Adaptive Frequency Hopping (AFH) - A Simple Instant Channel Replacement Approach for both ACL and SCO
Hongbing Gan, Vitaliy Sapozhnykov, Bijan Treister, Stan Skafidas, et. al.
Bandspeed Inc.
H. Gan, V. Sapozhnykov, et. al.

3. Benefits of the Simple AFH Approach Mechanism
<month year>
doc.: IEEE <doc#>
September, 2001
Benefits of the Simple AFH Approach Mechanism
Channel replacement on a per channel pair basis instantly, NO complicated ACL and SCO partition sequence generator is needed.
A simple AFH mechanism to cover all traffic types (ACL, SCO, Mixed ACL/SCO), high priority traffic such as SCO can get more good channels
A simple AFH to cover both low power and high power modes
Better backward compatibility with legacy devices
Master’s Transmitting channels are kept in the original positions in the hoping sequence, good for piconet synchronization, broadcast, Park mode, Sniff mode, beacon channel, etc.
Legacy devices also benefits from the new AFH approach
Random number generator seamlessly integrated
A harmonized simple AFH mechanism
H. Gan, V. Sapozhnykov, et. al.
<author>, <company>

4. Definition of Channel Pair
September, 2001
Definition of Channel Pair
A Channel Pair is comprised of two channels:
First channel, Master Tx/Slave Rx channel, at even-numbered timeslot
Second channel, Slave Tx/Master Rx, i.e., Slave return channel, at odd-numbered timeslot
Channel Pair
Channel Pair
Master Tx Rx Tx Rx f1 f3 f2 f4
Slave Rx Tx Rx Tx
Even-numbered
Timeslot
Odd-numbered
Timeslot
Even-numbered
Timeslot
Odd-numbered
Timeslot
H. Gan, V. Sapozhnykov, et. al.

5. Definitions N: Total number of hopping channels
September, 2001
Definitions
N: Total number of hopping channels
Nmin: Minimum number of channels to be used, set
by regulations such as FCC
G: Good channel
B: Bad channel
BN: Bad channel to be removed legally from the hopping sequence
BK: Bad channel to keep in the hopping sequence
NG, NB, NBN, NBK: Number of good channel, Number of bad channel, Number of bad channel to remove, Number of bad channel to keep, respectively
N = NG + NB
NB = NBK + NBN
H. Gan, V. Sapozhnykov, et. al.

6. AFH Covers All Possible Channel Classification Scenarios
September, 2001
AFH Covers All Possible Channel Classification Scenarios
Scenario 1: NBN > 0, NBK = 0 (Ideal scenario)
All Bad channels are replaced with Good channels in the new hopping sequence
(e.g., in lower power mode, all bad channels removed )
Scenario 2: NBN > 0, NBK > 0,
AFH removes BN , replaces it with randomly selected good channels G or BK (to maintain equal channel usage of G and BK),
AFH intelligently use BK in the new hoping sequence
(e.g., in high power mode, a maximum of 4 channels can be removed, the rest bad channels if any have to be kept)
H. Gan, V. Sapozhnykov, et. al.

7. AFH Covers All the Traffic Types
<month year>
doc.: IEEE <doc#>
September, 2001
AFH Covers All the Traffic Types
H. Gan, V. Sapozhnykov, et. al.
<author>, <company>

8. (Details in IEEE 802.15 Document 01/435r0, 01/438r0)
September, 2001
AFH Approach
- Standard Instant Channel Replacement (Standard ICR)
(Details in IEEE Document 01/435r0, 01/438r0)
H. Gan, V. Sapozhnykov, et. al.

9. Principle of Standard ICR
September, 2001
Principle of Standard ICR
Pass
Re-transmission
Blocked
Blocked
Original G G B B G B
New G G B B
Pass
Pass
Blocked
Blocked
Original ‘Good Good’ and ‘Bad Bad’ channel pairs are kept in their original positions in the hopping sequence
‘Good Bad’ channel pairs are instantly replaced to ‘Good Good’ channel pairs
‘Bad Good’ channel pairs are instantly replaced to ‘Bad Bad’ channel pair
Throughput improved due to newly created ‘Good Good’ channel pairs
H. Gan, V. Sapozhnykov, et. al.

10. September, 2001
Flowchart A:
Used for Master Tx/Slave Rx timeslots, i.e., Even-numbered timeslot
H. Gan, V. Sapozhnykov, et. al.

11. September, 2001
Flowchart B:
Used for Slave Tx/Master Rx timeslots, i.e., Odd-numbered timeslot
H. Gan, V. Sapozhnykov, et. al.

12. Standard ICR Processing Table
September, 2001
Standard ICR Processing Table
In case Master TX BN
replaced with a G
In case Master TX BN
replaced with a BK
When NO BK, Case 1, 3 ,4, 6 are processed
When NO BN, Case 1, 2, 10, 11 are processed
H. Gan, V. Sapozhnykov, et. al.

13. Example Portion of Original and AFH Hopping Sequence
September, 2001
Example Portion of Original and AFH Hopping Sequence G G BK G BN BN G BN BK BN G BK G BK BN BK G BK BN G G BN G
AFH G G G G G G G BK BK BK G BK G G
In this example, 7 more ‘Good Good’ channel pairs are created
H. Gan, V. Sapozhnykov, et. al.

14. - ‘Fit Best’ Instant Channel Replacement (Fit Best ICR)
September, 2001
AFH Approach
- ‘Fit Best’ Instant Channel Replacement (Fit Best ICR)
The only difference from Standard ICR is that higher priority traffic such as SCO voice link can have more good channels
H. Gan, V. Sapozhnykov, et. al.

15. September, 2001
How Fit Best ICR works
At higher priority timeslots such as reserved HV2 SCO timeslots:
Case 1: ‘Good Good’ ‘Good Good’
Case 2: ‘Good Bad’ ‘Good Good’
Case 3: ‘Bad Good’ ‘Good Good’
Case 4: ‘Bad Bad’ ’Good Good’
For every Case 3 replacement, a Good Channel Usage Debt (GUD) Counter is incremented by 1; For every Case 4 replacement, the GUD Counter is incremented by 2.
At lower priority timeslots, if there is any GUD debt, it must be repaid
‘Good Bad’ ‘Bad Bad’ , to repay the GUD by 1;
‘Good Good’ ‘Bad Bad’, to repay the GUD by 2.
If No GUD debt, just do standard ICR.
GUD balance is always towards ZERO, to maintain equal channel usage
H. Gan, V. Sapozhnykov, et. al.

16. Fit Best ICR Processing Table
September, 2001
Fit Best ICR Processing Table
At timeslots for higher priority traffic, such as voice HV2
Repay the debt
At timeslots for lower priority traffic
Repay the Good Channel Usage Debt (GUD)
H. Gan, V. Sapozhnykov, et. al.

17. General Principle of Fit Best ICR
September, 2001
General Principle of Fit Best ICR
For HV2 and HV3 link:
Fit the best channels to channel pairs of the reserved SCO Timeslots
For mixed SCO + ACL:
Fit the best channels to channel pairs of the reserved SCO Timeslots, if SCO has higher priority
Fit the best channels to channel pairs of the ACL Timeslots, if ACL has higher priority
Use Standard ICR if neither ACL nor SCO has higher priority
H. Gan, V. Sapozhnykov, et. al.

18. Mixed SCO (HV2, HV3) and ACL Links
September, 2001
Mixed SCO (HV2, HV3) and ACL Links T R T R T R T R T R T R
HV2
ACL
HV2
ACL
HV2
ACL
HV2 reserves half Timeslots, transmits every four Timeslots T R T R T R T R T R T R
HV3
ACL
ACL
HV3
ACL
ACL
HV3 reserves one third Timeslots, transmits every six Timeslots
H. Gan, V. Sapozhnykov, et. al.

19. How Fit Best ICR works (Assuming HV2 has higher priority)
September, 2001
How Fit Best ICR works (Assuming HV2 has higher priority)
HV2
ACL
HV2
ACL
HV2
ACL
HV2 G G BK G BK BK G BK G G BK BK
ACL
HV2
ACL
HV2
ACL
HV2
ACL G G BK BK G BK G G BK G
AFH
HV2
ACL
HV2
ACL
HV2
ACL
HV2 G G G BK G BK G
ACL
HV2
ACL
HV2
ACL
HV2
ACL BK G BK G G G BK
H. Gan, V. Sapozhnykov, et. al.

20. Summary: AFH Approach v.s. Traffic Type
<month year>
doc.: IEEE <doc#>
September, 2001
Summary: AFH Approach v.s. Traffic Type
H. Gan, V. Sapozhnykov, et. al.
<author>, <company>

21. September, 2001
Conclusion
A simple AFH mechanism to cover all traffic types (ACL, SCO, Mixed ACL/SCO), high priority traffic such as SCO can get more good channels
A simple AFH to cover both low power and high power modes
AFH removes as many Bad channels as legally possible
Kept Bad channels are intelligently used in the hopping sequence
The AFH channel replacement works on a per channel pair basis instantly, NO complicated ACL and SCO partition sequence generator is needed.
Better backward compatibility with legacy devices. Master’s Tx channels are kept in the original positions in the hoping sequence, good for piconet synchronization, broadcast, Park mode, Sniff mode, beacon channel, etc.
Legacy devices also benefits from the new AFH approach
A harmonized simple AFH mechanism
H. Gan, V. Sapozhnykov, et. al.