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

October, 2001 doc.: IEEE 802.15-01/442r0

Submission

Integrated Programmable Communications, Inc. and Texas Instruments, Inc.Slide 1

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

Submission Title: Comparison of TI-IPC's AFH Mechanism and Bandspeed's ICR ProposalDate Submitted: October 1, 2001

Source: (1) HK Chen, YC Maa, and KC Chen (2) Anuj Batra, Kofi Anim-Appiah, and Jin-Meng Ho

Company: (1) Integrated Programmable Communications, Inc. (2) Texas Instruments, Inc.Address: (1)Taiwan Laboratories Address: P.O. Box 24-226, Hsinchu, Taiwan 300

(2) 12500 TI Boulevard, Dallas, TX 75243TEL(1) +886 3 516 5106, FAX: +886 3 516 5108, E-Mail: {hkchen, ycmaa, kc}@inprocomm.com (2) +1 214 480 4220, FAX: 972 761 6966, E-Mail: {batra, kofi, jinmengho}@ti.comRe: []

Abstract: This presentation shows the comparisons of TI-IPC's AFH Mechanism and Bandspeed's ICR Proposal

Purpose: Submission to Task Group 2 for comparing the two mechanisms.

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.


Submission


Comparison of TI-IPC's AFH Mechanism and Bandspeed's ICR Proposal

HK Chen, YC Maa, and KC ChenIntegrated Programmable Communications

Anuj Batra, Kofi Anim-Appiah, and Jin-Meng HoTexas Instruments


Submission


ACL Link QoS Definition

BLUETOOTH Specification Version 1.1, Part C:

3.20 QUALITY OF SERVICE (QoS)The Link Manager provides Quality of Service capabilities. A poll interval, which is defined as the maximum time between subsequent transmissions from the master to a particular slave on the ACL link, is used to support bandwidth allocation and latency control. The poll interval is guaranteed in the active mode except when there are collisions with page, page scan, inquiry and inquiry scan. The poll interval is also known as Tpoll. These PDUs can be sent at anytime after connection setup is completed.


Submission


QoS Consideration in AFH

The maximum length of the continuous window of bad channels should be bounded. This bound (BWmax) should minimized for

best QoS.It is very useful if the ACL packet

scheduling algorithm can easily predict the position and length of every bad window.


Submission


QoS Comparison: ACL Link (1)

Partition SequenceGuaranteed and minimized BWmax.

Well-structured superframe, easy to predict the position and length of each bad window.

ICRThe length of bad window depends on the

underlying hopping sequence. It can create much longer bad window.

Unable to predict the position and length of each bad window


Submission



Numerical ExampleScenario 1:

• One 802.11b BSS at Channel 1– SBK={0,1,2,…,22}, SG={23,24,…,77,78}

– NBK=23, NG=56

Scenario 2:• Two 802.11b BSSes, at Channel 1 and 11

– SBK={0,1,2,…,22,49,50,…,70,71}, SG={23,24,…,47,48,72,73,…77,78}

– NBK=46, NG=33


Submission



The superframe structure of ACL partition sequence:

Guaranteed BWmax = Rb(1)

Adjust Rb(1) to a large value also creates larger good

windows => Helps protect multi-slot packets.

Rg(1) Rg

(1) Rg(1) Rg

(2)Rb(1) Rb

(1) Rb(1) Rb

(2)

n of Rg(1) and Rb

(1)


Submission



Partition Sequence, Scenario-1A few sets of parameters

BWmax can be as low as 2 hops, orAllow higher BWmax to have larger good window.

Rb(1) n Rb

(2) Rg(1) Rg

(2)

2 23 0 4 20

4 11 2 8 24

6 7 4 14 14

8 5 6 18 22


Submission



Partition Sequence, Scenario-2A few sets of parameters

BWmax can be as low as 4 hops, orAllow higher BWmax to have larger good window.

Rb(1) n Rb

(2) Rg(1) Rg

(2)

4 23 0 2 20

6 15 2 4 6

8 11 4 4 22

10 9 2 6 12


Submission



ICR performance evaluation method:Bluetooth hop selection kernel of the connection

state is fully implement.Run through the whole CLK cycle

• CLK27-0 = 0x0000000 ~ 0xFFFFFFF

ULAP: take the three values • 0x00000000, 0x2a96ef25, 0x6587cba9

The distribution of bad window length is plotted (Number of occurrence v.s. Length )


Submission



0 5 10 15 20 25 3010

0

101

102

103

104

105

106

107

Bad window length (hops)

Num

ber

of

occurr

ance

ICR for ACL: Scenario-1

ULAP=0x00000000ULAP=0x2a96ef25ULAP=0x6587cba9


Submission



0 10 20 30 40 50 60 7010

0

101

102

103

104

105

106

107

Bad window length (hops)

Num

ber

of

occurr

ance

ICR for ACL: Scenario-2



Submission


QoS Comparison: mixed SCO+ACL (1)

Numerical example:Scenario-1 and Scenario-2 are the same

as previously described.SCO traffic: one HV3 link, Dsco=0.

Here the SCO link has higher priority to have full protection, and we consider the dead window for the ACL traffic. The dead window includes the SCO slots and the bad ACL slots.


Submission



Partition sequenceScenario-1

• Each frame has at least two good MAUs, and there is only one HV3 link to protect. Hence each frame have at least one good MAU for the ACL link.

• DWmax (max dead window) = one frame = 6 hops

Scenario-2• Each frame has at least one good MAU to protect the

HV3 link. The residue MAUs are distributed evenly, with “interFrameSpacing” = 4.

• DWmax = 4 frames = 24 hops.


Submission



0 10 20 30 40 50 60 70 8010

1

102

103

104

105

106

107

ACL dead window length (hops)

Num

ber

of

occurr

ance

ICR for mixed SCO+ACL: Scenario-1



Submission



0 50 100 150 200 250 30010

0

101

102

103

104

105

106

ACL dead window length (hops)

Num

ber

of

occurr

ance

ICR for mixed SCO+ACL: Scenario-2



Submission


AFH Synchronization (1)

AFH synchronization Master and Slaves must share some common information to

produce the same adaptive hopping sequence

Information includes: Quasi-static information: it is kept constant within a session

of AFH, but can be changed at the next session.• Channel classification: the sets of good/bad-kept/bad-not-used

channels– SG, SBK, SBN. NG, NBK, NBN

• Traffic related parameters:

– The bad-window size, protected SCO streams, priority/non-priority slots


Submission



Information includes (cont’d):Time-varying information:

• it can change from hop to hop.• It will bring challenges to AFH synchronization. We have

to – Obtain the information value – Know which hop the information value applies to– Obtain the information value in time (old information is

useless)

• Bluetooth CLK is time-varying, but it is already synchronized.

• GUD counter of Fit-Best ICR is time-varying, and it needs some scheme to get synchronized.


Submission



It is a consensus in AFH group to use LMP for AFH synchronization. Perfect place for control information exchange in the Bluetooth

design. Simply extend the command set by defining new commands for

AFH.

LMP is not able to handle time-critical information There is no guarantee how many slots it takes for the LMP packet

to get through. If the transmission of this LMP packet is failed, the LC layer will

retransmit, but the value of time-varying information has changed already.

LMP can not be used for the synchronization of GUD counter in Fit-Best ICR.


Submission



Join AFH in the midwayWhen a slave joins a pico-net, or the slave

is waked up from some low-power mode, it could request to enter an existing AFH session.

An AFH session can last from a few seconds to less than 30 seconds. Not allowing to join AFH in the midway could create bad user experience.


Submission



Partition SequenceAll parameters are quasi-static within an AFH

session.Slaves can switch to AFH anytime during AFH.

Fit-Best ICRThe GUD counter can change for each hop, and it

is a time-varying and time-critical parameter.The GUD counter can not be transmitted through

the LMP message since LMP can not can not handle time-critical information.

Slaves can not join AFH in the midway of AFH.


Submission


Conclusions

Compared to the partition sequence approach, ICR could create much longer bad/dead window for ACL link or mixed SCO-ACL traffic, which dramatically reduces the QoS capabilities.

Fit-Best ICR uses a time-varying GUD counter, and it can not be synchronized through LMP.

With Fit-Best ICR, the slaves can not join AFH in the midway, leading to bad user experience.

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

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