Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS) Submission Title:...

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

Submission Title: [The relationship between DAC and TX LPF to satisfy the transmit PSD mask of MB-OFDM]

Date Submitted: [July 2004]Revised: []

Source: [Sang-sung Choi, Cheol-Ho Shin] Company [Electronics and Telecommunications Research Institute] Address [161 Gajeong-dong, Yuseong-gu, Daejeon, 305-350 Korea] Voice : [+82-42-860-6722], FAX : [+82-42-860-5199], E-mail [[email protected]]

Re: [Technical contribution]

Abstract: [This presentation presents the performance according to several TX LPF used to satisfy the Transmit PSD mask of MB-OFDM UWB system]

Purpose: [Technical contribution to analyze the relationship between DAC and TX LPF to satisfy the transmit PSD mask proposed for MB-OFDM UWB system]

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 or organization. The material in this document is subject to change in form and content after further study. The contributor reserves 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.

July 2004 doc.: IEEE 802. 15-04-0322-00-003a

July 2004

ETRISlide 2Submission

doc.: IEEE 802.15-04-0322-00-003a

The relationship between DAC and TX LPFto satisfy the transmit PSD mask of MB-

OFDM

Sang-Sung Choi ([email protected])

Cheol-Ho Shin ([email protected])

E T R I

www.etri.re.kr

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Introduction

128IFFT

128FFT

AddZP,

Guardinterval

RemoveZP,

Guardinterval

Time DomainFreq. Domain Freq. Domain

DAC ADC

UWB Channel

TX LO RX LO

TX LPF

The TX LPF is very important to determine the transmit PSD mask of MB-OFDM UWB system.

Two methods are considered to design the TX LPF satisfying the transmit PSD mask. - fix 528MHz sampling rate of DAC , and design high order TX LPF

- increase sampling rate of DAC, and reduce the order of TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Transmit PSD mask of MB-OFDM UWB system

A: 260 MHz -> 0 dBr bandwidth not exceeding 260MHz B: 285 MHz -> -12 dBrC: > 330 MHz -> -20dBr

-12 dB

-20 dB

A B C

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Power spectral density at 128 IFFT output

0 dBr

- 12 dBr

- 20 dBr

285MHz 330MHzf

Transmit PSD mask

PSD at IFFT output

The TX LPF design is not easy to satisfy the Transmit PSD mask of MB-OFDM.

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Power spectral density at DAC output

0 dBr

- 12 dBr

- 20 dBr

285MHz 330MHzf

Transmit PSD maskPSD at DAC output

The characteristic of DAC is similar to that of LPF, it can help to design the TX LPF.

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Measurement for DAC Characteristic

The characteristic of DAC as LPF is verified from PSD of OFDM system, the OFDM system used 2 over-sample rate at DAC.

PSD between DAC and TX LPF

PSD after TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

The PSD characteristics of several TX LPFs

The PSD characteristics of Several 5th order LPFs used to satisfy the Transmit PSD mask.Three types all don’t satisfy the transmit PSD mask by itself

Butterworth 5차

Chebyshev Type I 5 차

Chebyshev Type II 5 차

July 2004


doc.: IEEE 802.15-04-0322-00-003a

5th order Butterworth

Ideal

Before TX LPF

After TX LPF

3dB Bandwidth = 260MHz

July 2004


doc.: IEEE 802.15-04-0322-00-003a

5th order Chebyshev Type I

Ideal

3dB Bandwidth = 260MHzThe passband ripple = 0.5dB

Before TX LPF

After TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

5th order Chebyshev Type II

Ideal

3dB Bandwidth = 260MHzThe stopband ripple = 10 dB

Before TX LPF

After TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Summary of the 9th order TX LPFs

Chebyshev Type I 9 차

Butterworth 9 차

Chebyshev Type II 9 차

Ideal

After TX LPF : 9th order Butterworth

Apply several 9th order TX LPF to satisfy the transmit PSD mask

Before TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

2 times over-sampling at DAC

Ideal

2 times over sample rate is used at DAC to design TX LPF easily.In this case, the degradation of performance is about 1 dB compared to Ideal condition for BER 10-5.

Before TX LPF

After TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Summary of simulations

5th 9th2 times

over-sampling

Butterworth 10.7 dB 8.54 dB

7.6 dB

ChebyShev Type I 8.0 dB 8.05 dB

ChebyShev Type II 8.3 dB 9.8 dB

BER 10-5 기준

The higher order LPF is not always superior to the lower order LPF in the performance of system.In case of Chebyshev Type I , the system performance using 5th TX LPF is almost analogous to that using 9th TX LPF

July 2004


doc.: IEEE 802.15-04-0322-00-003a

Summary• There are two methods to satisfy the Transmit PSD

mask of MB-OFDM 1) Fix the DAC sample rate as 528MHz, then give burden to TX

LPF design.

- the higher order TX LPF is necessary

- but 5th order TX LPF is enough to satisfy the transmit PSD

mask considering the characteristic of DAC.

2) Use 2 times over-sample rate at DAC to design the TX LPF.

- Reduce the order of TX LPF

- It has advantage of the performance compared to method 1).

• There are trade-offs between two methods for considering power consumption and gate size etc.

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS) Submission Title:...

Documents

Transcript of Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS) Submission Title:...