Doc.: IEEE 802.15-04-0586-05-004b Submission Nov 2004 Francois Chin, Institute for Infocomm Research (I 2 R) Slide 1 Project: IEEE P802.15 Working Group

Nov 2004

Francois Chin, Institute for Infocomm Research (I2R)Slide 1

doc.: IEEE 802.15-04-0586-05-004b

Submission

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

Submission Title: [IEEE 802.15.4b High Rate Alt-PHY proposals - Further Performance Comparison]

Date Submitted: [10 Nov, 2004]

Source: [Francois Chin] Company: [Institute for Infocomm Research, Singapore]

Address: [21 Heng Mui Keng Terrace, Singapore 119613]

Voice: [65-6874-5687] FAX: [65-6774-4990] E-Mail: [[email protected]]

Re: [Response to the call for proposal of IEEE 802.15.4b, Doc Number: 15-04-0239-00-004b]

Abstract: [This presentation compares all proposals for the IEEE802.15.4b PHY standard.]

Purpose: [Proposal to IEEE 802.15.4b Task Group]

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.

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Background

– Main contribution of current doc is to provide further simulation results based on 1000 channel realisation, for the PHY proposals using coherent detection

– Previous comparison used 100 channel realisation, as in IEEE Doc 15-04-0507-04-004b

– Performance comparison herein done with• {0,1,2} cyclic chip extension• {1,2,3} RAKE fingers

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doc.: IEEE 802.15-04-0586-05-004b

Submission

Updates

– Corrected 3-RAKE multipath performance for all proposals (due to programme bug in previous version)

– Included PSSS performance with Precoding

– Determined RMS Delay Spread threshold below which cyclic chip extension is not necessary

– Include 868 MHz multipath performance with raised cosine filter (roll-off factor = 0.2)

– Stated Recommendation based on realistic channel RMS delay spread

– 915MHz Transmit PSD for COBI-16

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Candidates for Multipath Performance Comparison (using Coherent Chip Despreading)

Code Set E16 G16 C8 F31

Candidate for 915MHz 915MHz 868MHz 868MHz

Description Orthogonal 16-DSSS

16-chip for Coh. Chip Despreading


PSSS

Proposer Helicomm I2R I2R Dr. Wolf & Assoc.

Doc # 04-314 04-507 04-507 04-121

Sym-Chip mapping

Orthogonal Cyclic & Odd Bit Inversion

Cyclic & Odd Bit Inversion

Multi-code

Bit/sym 4 4 4 15

Chip/Sym 16 16 8 31+1 cyclic extension

Bit/chip 0.25 0.25 0.50 ~0.47

Root Sequence

N.A. 2F53 5C 08B3E375Source: 15-04-0507-04-004b

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

System Parameters for low GHz Bands

Ch #0 868MHz band

Ch #1-10906 – 924 MHz

Band

Bandwidth 600 kHz 2 MHz

Code Set Candidate

8-chip COBIC8

PSSS F31

8-chip COBIC8

PSSS F31

8-chip COBIC8

PSSS F31

16-chip COBIG16

DSSS E16

Chip rate 300kcps 400kcps 500kcps 1Mcps 1Mcps

Pulse shape

Raised cosine (roll off = 1)

Raised cosine (roll off = 0.5)


Half-sine

Half-sine

Modulation BPSK BPSK/ASK

BPSK BPSK/ASK

BPSK BPSK/ASK

OQPSK

OQPSK

Data rate 150 kbps

140.6 kbps

200 kbps

187.5 kbps

250 kbps

234.3 kbps

250 kbps

250 kbps

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Comparison Methodology

– Multipath robustness performance• Investigation done with

– Zero, one and two Cyclic chip(s) extension – One, two & three RAKE fingers

– Bandwidth efficiency (bps / Hz)– RF requirement– Memory requirement

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Multipath Realisations1000 Channel Realisations at each RMS Delay Spread

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Multipath Realisations1000 Channel Realisations at each RMS Delay Spread

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

The sequences are related to each other through cyclic shifts and/or conjugation (i.e., inversion of odd-indexed chip values)

Proposed Symbol-to-Chip Mapping (8-chip Code Set C8)

Decimal Value Binary Symbol Chip Value

0 0000 0 1 0 1 1 1 0 0 (Root – 5C)

1 1000 0 0 1 0 1 1 1 0

2 0100 0 0 0 1 0 1 1 1

3 1100 1 0 0 0 1 0 1 1

4 0010 1 1 0 0 0 1 0 1

5 1010 1 1 1 0 0 0 1 0

6 0110 0 1 1 1 0 0 0 1

7 1110 1 0 1 1 1 0 0 0

8 0001 0 0 0 0 1 0 0 1

9 1001 1 0 0 0 0 1 0 0

10 0101 0 1 0 0 0 0 1 0

11 1101 0 0 1 0 0 0 0 1

12 0011 1 0 0 1 0 0 0 0

13 1011 0 1 0 0 1 0 0 0

14 0111 0 0 1 0 0 1 0 0

15 1111 0 0 0 1 0 0 1 0

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Other Root Sequences (8-chip C8 for Coherent Despreading only)

• The following Root Sequences are found through exhaustive search with identical low cross correlation and autocorrelation, in base 10:

9 18 23 29 33 36 46 58 66 71 72 92 111 113 116 123 132 139 142 144 163 183 184 189 197 209 219 222 226 232 237 246

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

DSSS Sequence E16Decimal Symbol

Binary Symbol Chip Values

0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 0 0 0 1 0 0

1 1 0 0 0 0 1 1 0 0 0 0 1 0 0 0 1 0 0 0 1

2 0 1 0 0 0 0 0 0 0 1 1 1 0 1 1 1 0 1 1 1

3 1 1 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 0 1 0

4 0 0 1 0 0 0 1 1 1 0 1 1 0 1 0 0 1 0 1 1

5 1 0 1 0 0 1 1 0 1 1 1 0 0 0 0 1 1 1 1 0

6 1 1 1 0 0 0 0 0 1 0 0 0 0 1 1 1 1 0 0 0

7 0 1 1 1 0 1 0 1 1 1 0 1 0 0 1 0 1 1 0 1

8 0 0 0 1 0 0 1 1 0 1 0 0 1 0 1 1 1 0 1 1

9 1 0 0 1 0 1 1 0 0 0 0 1 1 1 1 0 1 1 1 0

10 0 1 0 1 0 0 0 0 0 1 1 1 1 0 0 0 1 0 0 0

11 1 1 0 1 0 1 0 1 0 0 1 0 1 1 0 1 1 1 0 1

12 0 0 1 1 0 0 1 1 1 0 1 1 1 0 1 1 0 1 0 0

13 1 0 1 1 0 1 1 0 1 1 1 0 1 1 1 0 0 0 0 1

14 0 1 1 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 1 1

15 1 1 1 1 0 1 0 1 1 1 0 1 1 1 0 1 0 0 1 0

Source doc.: IEEE 802.15-04-0314-02-004b

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

PSSS Sequence F31 (15 bit/32 chip)

Source doc.: IEEE 802.15-04-0121-04-004b

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Proposed Symbol-to-Chip Mapping (16-chip Code Set G16)

The sequences are related to each other through cyclic shifts and/or conjugation (i.e., inversion of odd-indexed chip values)

Decimal Value Binary Symbol Chip Value

0 0000 0 0 1 0 1 1 1 1 0 1 0 1 0 0 1 1 (Root - 2F53)

1 1000 1 1 0 0 1 0 1 1 1 1 0 1 0 1 0 0

2 0100 0 0 1 1 0 0 1 0 1 1 1 1 0 1 0 1

3 1100 0 1 0 0 1 1 0 0 1 0 1 1 1 1 0 1

4 0010 0 1 0 1 0 0 1 1 0 0 1 0 1 1 1 1

5 1010 1 1 0 1 0 1 0 0 1 1 0 0 1 0 1 1

6 0110 1 1 1 1 0 1 0 1 0 0 1 1 0 0 1 0

7 1110 1 0 1 1 1 1 0 1 0 1 0 0 1 1 0 0

8 0001 0 1 1 1 1 0 1 0 0 0 0 0 0 1 1 0

9 1001 1 0 0 1 1 1 1 0 1 0 0 0 0 0 0 1

10 0101 0 1 1 0 0 1 1 1 1 0 1 0 0 0 0 0

11 1101 0 0 0 1 1 0 0 1 1 1 1 0 1 0 0 0

12 0011 0 0 0 0 0 1 1 0 0 1 1 1 1 0 1 0

13 1011 1 0 0 0 0 0 0 1 1 0 0 1 1 1 1 0

14 0111 1 0 1 0 0 0 0 0 0 1 1 0 0 1 1 1

15 1111 1 1 1 0 1 0 0 0 0 0 0 1 1 0 0 1

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Other Root Sequences (8-chip G16 for Coherent Despreading only)• The following Root Sequences are found through

exhaustive search with identical low cross correlation and autocorrelation, in base 10:

1915 3566 12115 21038 22715 31238 34297 42820 44497 53420 61969 63620

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Multipath Performance (COBI 16-chip)

@ 1Mcps using O-QPSKFor 16-chip COBI Sequence, No cyclic chip is needed when 3 RAKE is used.

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Multipath Performance (COBI 8-chip)

For 8-chip COBI Sequence, 1 Chip Extension is needed even with 3-RAKE, due to weaker despreading strength (shorter code length).

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Multipath Performance (DSSS)

For DSSS, No cyclic chip is needed when 3 RAKE is used.

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Multipath Performance (PSSS)

For PSSS, best performance with 2 RAKE fingers + 1 chip extension. Precoding (according to 15-04-0121-04-004b) & 3rd RAKE do not seem to help.

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

What happened to PSSS?

While other schemes enjoy better multipath performance with more RAKE fingers, PSSS can only use up to 2 fingers as the 3rd RAKE is dominated by adjacent parallel bit sequence. PSSS is inter-parallel sequence interference limited

Neighbouring parallel

sequence is using M-Seq with 2 cyclic shifts in

PSSS parallel sequence

construction

Source doc.: IEEE 802.15-04-0121-04-004b

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

915 MHz Coherent Receiver Performance Under Various Channel Delay Spread

Even upto 1.33us RMS Delay Spread

•1 chip extension is NOT necessary for 16-chip sequence (COBI-16 & DSSS) if sufficient RAKE fingers (at least 3) are used, even in dense multipath environment

•General performance comparison:COBI sequence (16 chip) > DSSS Sequence (16 chip)

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission


Raised cosine filter (roll-off factor = 1.0)Gives 300 kcps


•1 chip extension is NOT necessary for COBI-8 if sufficient RAKE fingers (at least 3) are used, even in dense multipath environment

•General performance comparison:COBI sequence (8 chip) > PSSS Sequence

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission


Raised cosine filter (roll-off factor = 0.2)Gives 500 kcps


•1 chip extension is NOT necessary for COBI-8 if sufficient RAKE fingers (at least 4) are used, even in dense multipath environment

•General performance comparison:COBI sequence (8 chip) > PSSS Sequence

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Summary of ComparsionCode Set E16

G16 C8 F31

Candidate for 915MHz 915MHz 868MHz 868MHz

Description Orthogonal 16-DSSS



PSSS

Proposer Helicomm I2R I2R Dr. Wolf & Assoc.

Doc # 04-314 04-507 04-507 04-121

Sym-Chip mapping

Orthogonal Cyclic & Odd Bit Inversion

Cyclic & Odd Bit Inversion

Multi-code

Bit/sym 4 4 4 15

Chip/Sym 16 16 8 31+1 cyclic extension

Bit/chip 0.25 0.25 0.50 15/32 ~0.47

Multipath performance

Good Best Better Good

Memory requirement

High16 sequence

LowSingle sequence

Low Single sequence

Low Single sequence

RF linearity requirement

Low Low Low Moderate ~ high

Note : Red - desirable

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Can Non-Coherent Detection be used for COBI-16?

The COBI are designed to give best performance with coherent detection receiver. Can receiver employs Differential Chip detection?:

•Yes, COBI sequence (16 chip) can handle multipath channels with RMS delay spread upto 0.15us for 915MHz bands using 1Mcps, which normally corresponds to short range indoor environment

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

The COBI are designed to give best performance with coherent detection receiver. Can receiver employs Differential Chip detection?:

•Yes, COBI sequence (8 chip) can handle multipath channels with RMS delay spread upto 0.1us for 868MHz band using both 300kcps (roll-off factor = 1,0) and 500kcps (roll-off factor = 0.2), at even shorter range

Can Non-Coherent Detection be used for COBI-8?

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

•To combat inter-chip interference due to realistic channel delay spread with RMS delay spread upto 1.33us (e.g. industry application space):

•COBI 16-chip is recommended for 915MHz bands;•COBI 8-chip is recommended for 868MHz bands.

•RAKE combining (with at least 3 fingers) is necessary in receiver to combine path diversity; (this does not affect standard)•Chip extension is NOT necessary to avoid inter-symbol interference, if sufficient RAKE fingers are employed

•Differential chip despreading can also be used in shorter transmission range environment,e.g. residential space, where multipath channel RMS delay spread is upto 0.15us

Multipath Performance Summary (Coherent Chip Despreading)

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

System Parameters for low GHz Bands

Ch #0 868MHz band

Ch #1-10906 – 924 MHz

Band

Bandwidth 600 kHz 2 MHz

Code Set Candidate

8-chip COBIC8

PSSS F31

8-chip COBIC8

PSSS F31

8-chip COBIC8

PSSS F31

16-chip COBIG16

DSSS E16

Chip rate 300kcps 400kcps 500kcps 1Mcps 1Mcps

Pulse shape

Raised cosine (roll off = 1)



Half-sine

Half-sine

Modulation BPSK BPSK/ASK

BPSK BPSK/ASK

BPSK BPSK/ASK

OQPSK

OQPSK

Data rate 150 kbps

140.6 kbps

200 kbps

187.5 kbps

250 kbps

234.3 kbps

250 kbps

250 kbps

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

Beyond fc +/- 1.2 MHz, the highest sidelobe level is ~39 dB below the total transmit power and ~30 dB below the highest point in the PSD•Therefore, ~10 dB of margin to the -20 dBr spec.•For a device transmitting +10 dBm, there is ~9 dB of margin to the -20 dBm absolute spec.•Propose to be same as existing 915MHz Mask

915 MHz Band Transmit PSD (COBI-16)

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doc.: IEEE 802.15-04-0586-05-004b

Submission

Supporting Materials

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Submission

What leads to Multipath robustness?

Frequency selectivity leads to Inter-chip interference, and that is the killer….To overcome, code must have good autocorrelation properties, i.e. low sidelodes

Coherent Receiver Multipath Performance

Nov 2004


doc.: IEEE 802.15-04-0586-05-004b

Submission

•COBI, maintain constant module, can at best achieve zero auto-correlation within 2 chips from cor. Peak; that is good enough to handle ICI of upto 2 chip periods

•DSSS, comprising Walsh sequences, is not designed with auto-correlation sidelodes in mind

•PSSS, uses flexibility in amplitude to achieve low (zero?) auto-correlation throughout for each parallel sequence. However, it is inter-parallel sequence interference limited

How these codes achieve Multipath robustness?

COBI 8-chip autocorrelation matrix

COBI 16-chip autocorrelation matrix

Documents

Doc.: IEEE 802.15-04-0586-05-004b Submission Nov 2004 Francois Chin, Institute for Infocomm Research (I 2 R) Slide 1 Project: IEEE P802.15 Working Group