Jan 2005

Torbjorn LarssonSlide 1

doc.: IEEE 802.15-05/0039r0

Submission

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: [Impact of MB-OFDM and DS-UWB Interference — Part 2]Date Submitted: []Source: [Torbjorn Larsson] Company [Paradiddle Communications]Address [13141 Via Canyon Drive, San Diego, CA 92129, USA]Voice:[+1 858 538-3434], FAX: [+1 858 538-2284], E-Mail:[tlarsson@san.rr.com]

Re: [Analysis of the impact of MB-OFDM and DS-UWB interference on a DTV receiver made in earlier contributions, in particular 802.15-04/0412r0, 802.15-04/547r0 and 04/451/r2]

Abstract: [The impact of MB-OFDM and DS-UWB interference on a C-band DTV receiver is investigated by simulation]

Purpose: [To present an unbiased comparison of the impact of MB-OFDM and DS-UWB interference based on a minimal set of universally accepted assumptions]

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.

Jan 2005

Torbjorn LarssonSlide 2

doc.: IEEE 802.15-05/0039r0

Submission

Impact of MB-OFDM and DS-UWB Inteference — Part 2

Torbjorn Larsson

Paradiddle Communications, Inc.

Jan 2005

Torbjorn LarssonSlide 3

doc.: IEEE 802.15-05/0039r0

Submission

Motivation and Objective• Motivated by the following three contributions:

1) 04/0412r0, In-band Interference Properties of MB-OFDM, by C. Razell, Philips

2) 04/547r0, Responses to “In-Band Interference Properties of MB-OFDM”, by C. Corral, G. Rasor and S. Emami, Freescale Semiconductor

3) 04/451/r2, “Multiband OFDM Interference on In-band QPSK Receivers Revisited”, by C. Corral, S. Emami and G. Rasor, , Freescale Semiconductor

• The above contributions focused on the impact of MB-OFDM interference on a DTV victim receiver

• In contrast, the objective here is to quantify the difference in the impact of interference from MB-OFDM and DS-UWB

Jan 2005

Torbjorn LarssonSlide 4

doc.: IEEE 802.15-05/0039r0

Submission

C-Band DTV Systems• The C-band downlink spans 3.7 – 4.2 GHz

• C-band antennas are typically 6 – 12 feet in diameter

• Based on the DVB-S (Digital Video Broadcasting – Satellite) standard (EN 300 421)

• DVB-S was designed for MPEG-2 broadcasting in the Ku-band, but is also used in the C-band

• DVB-S does not specify a unique set of data rates or symbol rates; However…

• Typical transponder bandwidth is 36 MHz (33 MHz also used)

• Typical symbol rate 27 – 29 Msps

• DVB-S2 is the next generation with improved bandwidth efficiency and FEC

Jan 2005

Torbjorn LarssonSlide 5

doc.: IEEE 802.15-05/0039r0

Submission

DVB-S

RSEncoder

Inter-leaver

204 bytes

188 bytes

Rate-1/2Conv

EncoderPuncturing

QPSKModulation

RRCPulse

Shaping

RadioTX

Code rates: 1/2, 2/3, 3/4, 5/6, 7/8

RSDecoder

De-Interleaver

De-Puncturing

Soft-InputViterbi

Matched Filter

RadioRX

188 bytes

204 bytes

Required BER = 2·10-4

Jan 2005

Torbjorn LarssonSlide 6

doc.: IEEE 802.15-05/0039r0

Submission

Typical C-Band Downlink Channelization

Horizontal Polarization Vertical Polarization

Channel Center Frequency (GHZ) Channel Center Frequency (GHz)

1A 3.720 1B 3.740

2A 3.760 2B 3.780

3A 3.800 3B 3.820

4A 3.840 4B 3.860

5A 3.880 5B 3.900

6A 3.920 6B 3.940

7A 3.960 7B 3.980

8A 4.000 8B 4.020

9A 4.040 9B 4.060

10A 4.080 10B 4.100

11A 4.120 11B 4.140

12A 4.160 12B 4.180

(Telesat satellite Anik F2. Footprint: North America)

• Total of 24 channels

• Each polarization has 12 channels

• Transponder bandwidth is 36 MHz with a 4 MHz guard band

• The center frequencies are separated by 40 MHz

• The center frequencies for the two polarizations are offset by 20 MHz

• The result is 24 center frequencies separated by 20 MHz

Jan 2005

Torbjorn LarssonSlide 7

doc.: IEEE 802.15-05/0039r0

Submission

DTV Simulation Model

• Excludes Reed-Solomon coding and interleaving– Impossible to simulate error rates with RS coding

• Symbol rate: 28 Msps

• No quantization (including input to Viterbi decoder)

• Ideal pulse shaping/matched filters (0.35 roll-off)

• No nonlinarity

• No frequency offset

• No phase noise

• Pre-computed phase error and time offset

• Receiver noise figure: 4 dB

• Code rates 2/3 and 7/8

Jan 2005

Torbjorn LarssonSlide 8

doc.: IEEE 802.15-05/0039r0

Submission

MB-OFDM Transmitter Model

• Based on the Jan. 2005 release of the MB-OFDM PHY spec

• Complete Matlab implementation of the specifications

• System operating in band-hopping mode

• Includes (5-bit) DAC and realistic filter characteristics

• Spectral pre-shaping to compensate for non-ideal filter characteristics (=> worst-case in this context!)

• Channel number 9 (Band group 1, TFC 1)

• Data rate “110” Mbps (106.7 Mbps)

Jan 2005

Torbjorn LarssonSlide 9

doc.: IEEE 802.15-05/0039r0

Submission

DS-UWB Transmitter Model• Based on the July 2004 release of the DS-UWB PHY specifications

(P802.15-04/0137r3)

• Complete Matlab implementation of the specifications

• No DAC

• Ideal RRC pulse shaping filter truncated to 12 chip periods (=> worst-case)

• Channel number 1 (chip rate: 1313 Mcps)

• Data rate: “110” Mbps (109.417 Mbps)

• BPSK modulation

• Spreading code for preamble and header (PAC): -1 0 +1 -1 -1 -1 +1 +1 0 +1 +1 +1 +1 -1 +1 -1 +1 +1 +1 +1 -1 -1 +1

• Spreading code for frame body: +1 0 0 0 0 0

Jan 2005

Torbjorn LarssonSlide 10

doc.: IEEE 802.15-05/0039r0

Submission

Interference Spectra

• Transmit power is set so as to push each spectrum as close as possible to the FCC limit (worst-case condition)

• MB-OFDM transmit power is -10.3 dBm• DS-UWB transmit power is -10.8 dBm (data rate dependent)

2 2.5 3 3.5 4 4.5 5 5.5 6-90

-80

-70

-60

-50

-40

-30

GHz

dB

m

Power over 1 MHz Bandwidth

MB-OFDMDS-UWBFCC Mask

Resolution: 10 kHz

PSD averaged over 10 packets (roughly 0.9 ms)

Jan 2005

Torbjorn LarssonSlide 11

doc.: IEEE 802.15-05/0039r0

Submission

Interference Spectra – Close Up

• Both spectra exhibit substantial variations• Solution: run simulation for multiple DTV center frequencies

3 3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8 5

-45

-44

-43

-42

-41

-40

GHz

dB

m

Power over 1 MHz Bandwidth

MB-OFDMDS-UWBFCC Mask

DTV center frequencies

Jan 2005

Torbjorn LarssonSlide 12

doc.: IEEE 802.15-05/0039r0

Submission

0 0.05 0.1 0.15 0.20

0.05

0.1

0.15

0.2

0.25MB-OFDM

0 0.05 0.1 0.15 0.20

0.05

0.1

0.15

0.2

0.25DS-UWB

Amplitude Histogram: Wideband (without Multipath)

PAR = 11.9 dB PAR = 12.0 dB

Data rate: 110 kbps

Jan 2005

Torbjorn LarssonSlide 13

doc.: IEEE 802.15-05/0039r0

Submission

0 0.05 0.1 0.15 0.20

0.02

0.04

0.06

0.08

0.1

0.12MB-OFDM

0 0.05 0.1 0.15 0.20

0.02

0.04

0.06

0.08

0.1

0.12DS-UWB

Amplitude Histogram: Wideband (with Multipath)

PAR = 14.1 dB PAR = 14.2 dBData rate: 110 kbps

100 multipath channel realizations

Jan 2005

Torbjorn LarssonSlide 14

doc.: IEEE 802.15-05/0039r0

Submission

Amplitude Histogram: Output of DTV Matched Filter (with Multipath)

Center frequency = 4 GHz

100 multipath channel realizations

0 0.1 0.2 0.3 0.40

0.1

0.2

0.3

0.4

0.5

0.6MB-OFDM

0 0.1 0.2 0.3 0.40

0.1

0.2

0.3

0.4

0.5

0.6DS-UWB

Jan 2005

Torbjorn LarssonSlide 15

doc.: IEEE 802.15-05/0039r0

Submission

Output of Matched Filter (Close-Up)

0.2 0.3 0.4 0.5 0.60

0.005

0.01

0.015MB-OFDM

0.2 0.3 0.4 0.5 0.60

0.005

0.01

0.015DS-UWB

Jan 2005

Torbjorn LarssonSlide 16

doc.: IEEE 802.15-05/0039r0

Submission

Changes Since November 2004

• All simulations carried out with center frequencies according to channelization plan on slide 6 3.72 GHz to 4.18 GHz in steps of 20 MHz

• Added multipath (CM3, no shadowing)

• Increased symbol rate from 27 to 28 Msps

Jan 2005

Torbjorn LarssonSlide 17

doc.: IEEE 802.15-05/0039r0

Submission

Simulation Block Diagram

• Attenuation 1 is set so that the received DTV power is 3 dB above sensitivity

• Each simulation is performed with all 24 DTV center frequencies

• Simulation results are plotted as a function of center frequency and attenuation 2

DTVTransmitter

3 dB above sensitivity

Atten 2

PDTV

MB-OFDMTransmitter

DS-UWBTransmitter

Atten 1 + DTVReceiver

BERCounter

RandomData

CenterFrequency

CenterFrequency

PMB-OFDM

PDS-UWB

Re-Sample

fs = 21.6 GHz

204 byte packets

Multi-path

fs = 21.6 GHz

Jan 2005

Torbjorn LarssonSlide 18

doc.: IEEE 802.15-05/0039r0

Submission

DTV Sensitivity (NF = 4 dB)

Defines sensitivity

-96 -95 -94 -93 -92 -91 -90 -89 -88 -87 -8610

-6

10-5

10-4

10-3

10-2

10-1

100

BER After Viterbi Decoder (NF = 4 dB)

PDTV

[dBm]

BE

RCode Rate 1/2Code Rate 2/3Code Rate 3/4Code Rate 5/6Code Rate 7/8

Jan 2005

Torbjorn LarssonSlide 19

doc.: IEEE 802.15-05/0039r0

Submission

DTV Sensitivity (NF = 4 dB)

Code Rate Sensitivity [dBm]

1/2 -92.3

2/3 -90.5

3/4 -89.5

5/6 -88.5

7/8 -87.9

(Symbol rate: 28 Msps)

Jan 2005

Torbjorn LarssonSlide 20

doc.: IEEE 802.15-05/0039r0

Submission

BER versus Center Frequency

Interference attenuation = 67 dB

Code Rate 1/2, without multipath

3.7 3.75 3.8 3.85 3.9 3.95 4 4.05 4.1 4.15 4.210

-4

10-3

10-2

BER After Viterbi Decoder versus Center Frequency (Rate 1/2)

Center Frequency [GHz]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 21

doc.: IEEE 802.15-05/0039r0

Submission

BER versus Center Frequency

Interference attenuation = 71 dB

Code Rate 1/2, with multipath

3.7 3.75 3.8 3.85 3.9 3.95 4 4.05 4.1 4.15 4.2

10-4

10-3

10-2

BER After Viterbi Decoder versus Center Frequency (Rate 1/2)

Center Frequency [GHz]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 22

doc.: IEEE 802.15-05/0039r0

Submission

Two Performance Metrics

1. Compute average error rate over the 24 center freqeuencies

2. Select maximum error rate from the 24 center frequencies

Jan 2005

Torbjorn LarssonSlide 23

doc.: IEEE 802.15-05/0039r0

Submission

Average BERCode Rate 1/2, with multipath

67 68 69 70 71 72 73 74 75

10-4

10-3

10-2

10-1

Average BER After Viterbi Decoder (Code Rate 1/2)

Interference Attenuation [dB]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 24

doc.: IEEE 802.15-05/0039r0

Submission

Maximum BERCode Rate 1/2, with multipath

67 68 69 70 71 72 73 74 75

10-4

10-3

10-2

10-1

Maximum BER After Viterbi Decoder (Code Rate 1/2)

Interference Attenuation [dB]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 25

doc.: IEEE 802.15-05/0039r0

Submission

BER versus Center Frequency

Interference attenuation = 71 dB

Code Rate 7/8, with multipath

3.7 3.75 3.8 3.85 3.9 3.95 4 4.05 4.1 4.15 4.2

10-4

10-3

10-2

10-1

BER After Viterbi Decoder versus Center Frequency (Rate 7/8)

Center Frequency [GHz]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 26

doc.: IEEE 802.15-05/0039r0

Submission

Average BERCode Rate 7/8, with multipath

64 66 68 70 72 74 76

10-4

10-3

10-2

10-1

100

Average BER After Viterbi Decoder (Code Rate 7/8)

Interference Attenuation [dB]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 27

doc.: IEEE 802.15-05/0039r0

Submission

Worst-Case BERCode Rate 7/8, with multipath

64 66 68 70 72 74 76

10-4

10-3

10-2

10-1

100

Maximum BER After Viterbi Decoder (Code Rate 7/8)

Interference Attenuation [dB]

BE

R

MB-OFDMDS-UWB

Jan 2005

Torbjorn LarssonSlide 28

doc.: IEEE 802.15-05/0039r0

Submission

Conclusions

• For DTV code rate 1/2, there is practically no difference between the two interfering waveforms

• The difference increases with code rate– MB-OFDM interference is more bursty in nature and thus

has more impact for higher code rates

• For DTV code rate 7/8, MB-OFDM is ≈ 1.3 dB worse than DS-UWB @ BER 2·10-4