September 2001 doc IEEE 802 15 01435 r

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Project: IEEE P 802. 15 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: [61 3 9614 6299 , FAX: [61 3 9614 6699] E-Mail: [h. gan, b. treister, v. sapozhnykov@bandspeed. com. au] 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 802. 15. 2] Notice: This document has been prepared to assist the IEEE P 802. 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 P 802. 15. Submission 1 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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. Submission 2 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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 Good 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 Submission 3 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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 Master Tx Channel Pair Rx Tx f 1 f 3 f 2 Slave Submission Rx Even-numbered Timeslot Rx f 4 Tx Odd-numbered Timeslot 4 Rx Even-numbered Timeslot Tx Odd-numbered Timeslot H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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, NBN, NBK: Number of good channel, Number of bad channel to remove, Number of bad channel to keep, respectively • N = N G + NB • NB = NBK + NBN Submission 5 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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 low power mode, all bad channels removed, or once FCC law changed for high power devices) • 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) Submission 6 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 AFH Covers All the Traffic Types Submission 7 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 AFH Approach - Standard Instant Channel Replacement (Standard ICR) (Details in IEEE 802. 15 Document 01/435 r 0, 01/438 r 0) Submission 8 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Principle of Standard ICR Pass Original New G G Pass Re-transmission G B G G Pass Blocked B B G B B Blocked • Original ‘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’ channel pairs • ‘Bad Good’ channel pairs are instantly replaced to ‘Bad Bad’ channel pair • Throughput improved due to newly created ‘Good’ channel pairs Submission 9 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Flowchart A: Used for Master Tx/Slave Rx timeslots, i. e. , Even-numbered timeslot Submission 10 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Flowchart B: Used for Slave Tx/Master Rx timeslots, i. e. , Odd-numbered timeslot Submission 11 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Standard ICR Processing Table In case Master TX BN replaced with a G In case Master TX BN replaced with a BK Submission • When NO BK, Case 1, 3 , 4, 6 are processed • When NO BN, Case 1, 2, 10, 11 are processed 12 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Example Portion of Original and AFH Hopping Sequence G G G BK G BN BN G BK BN BK BK BN BN G BK BN G G G BN G AFH G G G G G BK BK BK G G G G In this example, 7 more ‘Good’ channel pairs are created Submission 13 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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 Submission 14 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 How Fit Best ICR works • At higher priority timeslots such as reserved HV 2 SCO timeslots: • Case 1: ‘Good’ • Case 2: ‘Good Bad’ ‘Good’ • Case 3: ‘Bad Good’ ‘Good’ • Case 4: ‘Bad Bad’ ’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’ ‘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 Submission 15 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Fit Best ICR Processing Table At timeslots for higher priority traffic, such as voice HV 2 Repay the debt At timeslots for lower priority traffic Repay the Good Channel Usage Debt (GUD) Submission 16 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Guaranteed GUD Convergence • If Number of Good Channels (NG) is enough to fill high priority traffic such as HV 2, GUD converges. – For example, NG > NBK, as HV 2 take 50% of timeslots, then all HV 2 slots are filled with Good channels. • If Number of Good Channels (NG) is NOT enough to fill high priority traffic such as HV 2, GUD STILL converges. – Why GUD still converges? By saving Good channel usage first at ACL timeslots, then use the Good channels in the HV 2 timeslots – Just like a Savings account – For example, 40% of channels are Good, 60% are Bad, HV 2 takes 50% timeslots, all Good channels are fitted to HV 2 slots, then 80% of HV 2 slots are fitted with Good channels Submission 17 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 In Case Not Enough Good Channels • At lower priority timeslots, save good channel usage for high priority timeslots • ‘Good Bad’ ‘Bad Bad’, Decrease GUD by 1, i. e. save 1 good usage; • ‘Good’ ‘Bad Bad’, Decrease GUD by 2, i. e. save 2 good usage; • ‘Bad Good’ ‘Bad Bad’ • At higher priority timeslots such as reserved HV 2 SCO timeslots: • Case 1: ‘Good’ • Case 2: ‘Good Bad’ ‘Good’ • Case 3: ‘Bad Good’, if GUD < -1, ‘Good’, increment GUD by 1 if GUD > -1, • ‘Bad Bad’ Case 4: ‘Bad Bad’, if GUD < -1, ’Good’, increment GUD by 2 if GUD > -1, ‘Bad Bad’ • GUD is always converged towards ZERO, to maintain equal channel usage Submission 18 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 General Principle of Fit Best ICR • • For HV 2 and HV 3 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 Submission 19 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Mixed SCO (HV 2, HV 3) and ACL Links T R HV 2 T R ACL T R T HV 2 R ACL T R HV 2 T R ACL HV 2 reserves half Timeslots, transmits every four Timeslots T R HV 3 T R ACL T R T ACL R HV 3 T R ACL HV 3 reserves one third Timeslots, transmits every six Timeslots Submission 20 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 How Fit Best ICR works (Assuming HV 2 has higher priority) HV 2 ACL G G G BK 1 2 3 4 5 6 7 ACL HV 2 ACL G BK G 13 14 G G 8 HV 2 G BK BK G G BK BK BK 9 ACL 10 HV 2 ACL BK G HV 2 G BK BK BK 11 12 HV 2 ACL HV 2 AFH ACL G G G BK BK G G 1 2 3 4 5 6 7 ACL HV 2 ACL BK BK G G G G BK BK 8 Submission 9 10 11 21 12 13 14 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 Summary: AFH Approach v. s. Traffic Type Submission 22 H. Gan, V. Sapozhnykov, et. al.

September, 2001 doc. : IEEE 802. 15 -01/435 r 3 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 Good 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 Submission 23 H. Gan, V. Sapozhnykov, et. al.