Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, 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: A Wise AFH Solution for WPANDate Submitted: November 1, 2001

Source: YC Maa, HK Chen, Shawn Liu and KC Chen

Company: Integrated Programmable Communications, Inc. Address: Taiwan Laboratories Address: P.O. Box 24-226, Hsinchu, Taiwan 300TEL +886 3 516 5106, FAX: +886 3 516 5108, E-Mail: {ycmaa, hkchen, shawnliu, kc}@inprocomm.com Re: [IEEE 802.15-00/367r1, IEEE 802.15-01/082r1, IEEE 802.15-01/246r1, IEEE 802.15-01/252r0, IEEE 802.15-01/366r1, IEEE 802.15-01/382r0, IEEE 802.15-01/385r0, IEEE 802.15-01/386r0, IEEE 802.15-01/443r0, IEEE 802.15-01/471r0, IEEE 802.15-01/491r0]

Abstract: This document presents a wise AFH scheme for 802.15 TG2 Coexistence Mechanism .

Purpose: Submission to TG2 for AFH draft consideration.

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.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 2

A Wise AFH Solution for WPAN

KC Chen,YC Maa, HK Chen, and Shawn LiuIntegrated Programmable Communications, Inc.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 3

Outline

Review on Channel NamingConsiderations

Regulation Change EffectImplementation and Complexity

Conclusion and RecommendationAppendix: Complexity Estimation for

AFH

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 4

Review on Channel Naming

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 5

Channels are classified into 3 groups: (dynamic classification) Usable channel set SU: uninterfered or “good” channels (size = NU) Kept channel set SK: interfered channels kept for AFH (size = NK) Removed channel set SR : interfered channels left out in AFH (size = NR) NU + NK + NR = 79

Define Nmin to be the minimum number of channels that a Bluetooth device must hop over.

Usable and Kept need to be considered, based on Nmin, NU: Nmin NU: only use usable channels in the hopping sequence Nmin > NU: require kept channels in addition to usable channels in the new

hopping sequence, where kept channels NK = Nmin–NU

When kept channels are required, both “partition sequence” and “mapping” mechanisms are executed. Mode L uses usable and “fill-in” channels blindly

When kept channels are not required, only “mapping” mechanism is executed.

Review of AFH Channel Naming

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 6

Considerations

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 7

Worldwide Regulations United States (FCC):

Currently FH devices must hop over a minimum of 75 channels. NPRM suggests a new minimum hopset of 15 channels.

• Two other proposed rule changes on the same NPRM– DSSS processing gain– new Digital Transmission Technologies (DTS)

• Decision for ruling may drag on Europe (ETSI):

FH devices must hop over a minimum of 20 channels, • France allows operation at 2.4465-2.4835 GHz, a total of 37MHz, but

Bluetooth devices only use 23 channels.• Spain recently increased to a total of 79 channels

Japan: No restriction on the minimum number of channels today.

Asia (especially China) Rule change usually falls behind US or Europe by 2+ years.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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Mode H & L under FCC/Global Regulation

Mode H works under current FCC regulation Works for all Bluetooth devices (type 1, 2, 3) today Will always work under FCC regulation, regardless what Nmin

may be.

Mode L may not always work under current FCC Does not work for type 1 & 2 Bluetooth devices (high power) May work only for type 3 device (low power constraints) May work better under future FCC regulation (if Nmin= 15)

Mode H always complies with current and future FCC/global regulation, while mode L does not

As the ISM band gets more crowded, the benefit of Mode H is more significant.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 9

Important Usage Scenarios: Three 802.11b APs (01/443r0)

Agreed by all, including TI and Bandspeed, as very important scenario in Mar01 meeting. Three collocated access points (on channel 1, 6, 11) will be

common in the enterprise environment.• The three networks will occupy a total (30-dB) bandwidth of 66 MHz,

which implies that these networks occupy 67 Bluetooth channels.• only 12 Bluetooth channels are free of interference (NU = 12).• if Nmin = 15, then we are forced to use 3 kept channels in the

adapted hopping sequence.• if Nmin = 20 then we are forced to use 8 kept channels in the adapted

hopping sequence. Kept channels must be used intelligently, otherwise -

• Higher packet error rate, which leads to unacceptable voice quality• Lower throughput.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 10

Effects of the NPRM (01/443r0)

Proposed rules in NPRM are less strict than the current rules. NPRM was issued to allow new modulation schemes,

such as PBCC-22 and OFDM, into the 2.4 GHz band. An OFDM signal has a larger bandwidth than the current

IEEE 802.11b signals. Spectral mask 20dB-Bandwidth: 22MHzSpectral mask 28dB-Bandwidth: 40MHz

Thus, spectrum free of interference will become even more difficult to find!

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 11

Regulation Change Effect

New NPRM seems to justify Mode L. Yet new application scenarios, enabled by NPRM -

Booming enterprise WLAN deployments New technologies, such as OFDM, PBCC-22

will lead to a more crowded ISM band spectrum, which will not leave enough Usable channels for Mode L or FH schemes with small hopset!

Mode H is significantly more effective in a more crowded ISM band.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 12

Implementation and ComplexityImplementation

One shot design vs. Incremental redesign• One-shot design

– Design right at the first time– Works under any regulation

• Incremental redesign – Occurs as regulation changes– Overwhelming effort and complexity at a great cost

ComplexityRelative complexity

• In % gates to a typical implementation• In % MIPS to a typical C processing power

Much cheaper than the incremental redesign cost!!

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 13

Complexity Estimates for mode H & L(01/471r0)

Examined: Mapping & Partition functions Software and hardware realizations

Left out: Channel classification algorithm Pseudo-random number generator

Assumption: The basic time unit for AFH mechanisms is one slot

– 625 us.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 14

AFH Complexity Estimation Summary Hardware complexity

mode H - 5.1K gates mode L - 3.1K gates

• Difference of 2k gates, or• 2% for a typical 100K-gate Bluetooth design, or • 0.4% for a typical 500K-gate co-located Bluetooth/WLAN design

Software complexity mode H - 0.19~0.64 MIPS mode L - 0.17 MIPS

• up to 1.18% more, based on a 40-MIPS micro-controller

The added complexities are miniscule Compared to today’s HW & SW design overall complexity Compared to the overwhelming incremental-redesign costs

For details, please refer to Appendix

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 15

Conclusion &

Recommendation

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 16

Conclusion and Recommendation (1)

NPRM leads to more crowded ISM band useBooming enterprise WLAN deployments & new

technologies, such as OFDM, PBCC-22 Insufficient usable channels for mode LMode H not only conforms to current and future

FCC regulation, but also adapts to future ISM band wireless boom.

Only < 2% complexity added by Partition Sequence, a universal design spares a lot of re-design/re-spin cost and efforts.works all over the world.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 17

Conclusion and Recommendation (2)

AFH merger proposal (01/382r0) and AFH draft (01/491r0)-

Wise AFH Solution for WPANTechnically, intelligent AFH SchemeProduct-wise, deal with current and future

market needs while avoiding re-design cost Industry-wise, a wise decision to

harmonize AFH schemes in 802.15 TG2 and Bluetooth SIG Coexistence WG

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 18

Appendix :

Complexity Estimation for AFH

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 19

Appendix:Complexity Estimation for AFH

Examined: Mapping & Partition functions Software and hardware realizations

Left out: Channel classification algorithm Pseudo-random number generator

Assumption: The basic time unit for AFH mechanisms is one slot – 625

us.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 20

Software Implementation Assumption(1)

Division/Mod operationA=B*Q+R, Q=floor(A/B), R = A mod B It can be implemented in software by long-division.

Each iteration requires 8 operations:– Two shift operations– One compare– One conditional jump– One subtraction, and one addition– Two instructions for loop: one subtraction, and one

conditional jump

• Number of iterations required is equal to the width ( number of bits) of A, WA.

• The total instruction cycles required is roughly 8* WA.

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 21

Software Implementation Assumption(2)

MultiplicationMany processors have special instruction for

multiplication (C=A*B). If not, it can be implemented in software

• Each iteration requires 5 operations:– Two shift operation– One conditional addition– Two instructions for loop: one subtraction, and one

conditional jump

• Number of iterations required is equal to min{WA ,WB}• The total instruction cycles required is roughly

5*(min{WA ,WB})

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 22

Software Implementation: Mode L Mapping

InstructionsMod operation x 1:

• Assume 12-bits pseudo-random signal, thus 12-bit mod operation

• 96 instruction cyclesMisc. instructions

• Add/if-then-else/table-lookup/load-store variables• 10 instruction cycles

Totally 106 instruction cyclesLoad

106/625us = 0.1696 MIPS

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 23

Software Implementation: Mode H Partition Sequence-SCO (1)

For the first MAU (master-slave pair)Distribution unit: Variables initial calculations

• Six div/mod operations– 27bits x 1, 9bits x 1, 8bits x 1, 7bits x 3– 8*(27+9+8+7*3)= 520 instruction cycles

• Two multiplications – 2bits x 2– 2*5*2=20 instructions cycles

• Misc instructions(logic/compare/jump/add-sub/load)– 30 instruction cycles

Arrangement unit: • if-then-else/table-lookup

– 10 instruction cycles

Totally 580 instruction cycles

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 24

Software Implementation: Mode H Partition Sequence-SCO (2)

For the remaining MAUs within one superframe Distribution unit:

• Variables update• 25 instructions cycles

Arrangement unit: • if-then-else/table-lookup• 10 instruction cycles

Totally 35 instruction cycles

For MAUs after one superframe The partition sequence is periodic with superframe The maximum length of superframe is 3*79 MAUs Require 237 bits (about 30 bytes) to store one period Table-lookup/index update: 10 instructions

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 25

Software Implementation: Mode H Mapping

InstructionsMod operation x 1:

• Assume 12-bits pseudo-random signal, thus 12-bit mod operation

• 96 instruction cyclesMisc instructions

• Add/if-then-else/table-lookup/load-store variables• 15 instruction cycles

Totally 111 instruction cyclesLoad

• 111/625us = 0.1776 MIPS

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 26

Software Implementation: Mode H

The complexity of mode H is the sum of mapping and partition sequenceNote that partition sequence is not calculated

every slot, but every MAU (two slots)For the first MAU:

• 0.1776MIPS + 580/(625us*2) = 0.6416 MIPS

For the remaining MAUs within one superframe• 0.1776MIPS + 35/(625us*2) = 0.2056 MIPS

After one superframe• 0.1776MIPS + 10/(625us*2) = 0.1856 MIPS

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

Submission

YC Maa et al., InProComm, Inc.Slide 27

Hardware Implementation Assumption(1)

Unit of gate count: NAND gate. Use one hardware block for multiple occurrences of the

same operation. Ex: there may be several mod operations, but only one

div/mod hardware is needed. Variable storage/mapping table: 4 gates per bits. Division/Mod operation

A=B*Q+R, Q=floor(A/B), R = A mod B It can be implemented in hardware by long-division:

• Multiple clock implementation, shift-in one bit of operand “A” at each clock.

• Require WA clocks to finish one operation.• Gate count required is in proportional to WB .

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 28

Hardware Implementation: Mode L Mapping

Hardware blocks:Adder

• 12-bits• Gate count = 0.1K

Mod • WB=7 • Gate count = 1K

Mapping table• 79*7 bits• Gate count = 2K

Total gate count = 3.1K

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 29

Hardware Implementation: Mode H Mapping

Hardware blocks:Adder

• 12-bits• Gate count = 0.1K

Mod • WB=7 • Gate count = 1K

Mapping table• 79*7 bits• Gate count = 2K

Misc• 0.2 K

Total gate count = 3.3K

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 30

Hardware Implementation: Mode H Partition Sequence

Hardware blocks: Multiplier: 8bit x 8 bit, parallel multiplier

• Gate count = 0.5K

Division/Mod • WB=8 • Gate count = 1K

Add/Sub• Gate count = 0.1K

Variable storage and procedure control• Gate count = 1K

Misc• Gate count = 0.2K

Total gate count = 2.8 K

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 31

Hardware Implementation: Mode H

The complexity of mode H is the sum of mapping and partition sequenceDirect summation of the two gate count numbers:

3.3K + 2.8K = 6.1KNote that the mod/division block can be further

shared• Gate count can be reduced to 5.1K

Integrated Programmable Communications, Inc.November, 2001 doc.: IEEE 802.15-01/501r0

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YC Maa et al., InProComm, Inc.Slide 32

Complexity Considerations with Reference Numbers for Bluetooth

The hardware implementation of LC is about 70K-100K gates

The computation power required for LMP, L2CAP, and HCI is about 10 ~ 20 MIPs, while typical processors can easily provide up to 40 MIPs.

The complexity added, in software or hardware, is miniscule!