Doc.: IEEE 802.15 03111r1_TG3a Submission May 2003 Molisch et al., Time Hopping Impulse Radio...

May 2003

Molisch et al., Time Hopping Impulse Radio

doc.: IEEE 802.15 03111r1_TG3a

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: Mitubishi Electric Proposal Time-Hopping Impulse RadioDate Submitted: May 5th, 2003Source: Andreas F. Molisch et al., Mitsubishi Electric Research LaboratoriesAddress MERL, 201 Broadway Cambridge, MA, 02139, USA Voice: +1 617 621 7558, FAX: +1 617 621 7550 , E-Mail: [email protected]

Re: [Response to Call for Proposals]

Abstract: We present a standards proposal for a high-data-rate physical layer of a Personal Area Network, using ultrawideband transmission. The air interface is based on time-hopping impulse radio, using BPSK for the modulation, and in addition polarity randomization of the pulses within the symbol. Combinations of delayed and weighted pulses allow an efficient shaping of the spectrum. This provides good suppression of interference, and guarantees fulfillment of coexistence requirements. The system is designed to have A/D conversion and digital processing only at the symbol rate, not the chip rate. Costs are comparable to Bluetooth.

Purpose: [Proposing a PHY-layer interface for standardization by 802.15.3a]

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.

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Ultra WideBand

Mitsubishi Electric Proposal

Time-Hopping Impulse Radio

A. F. Molisch, Y.-P. Nakache, P. Orlik, J. ZhangMitsubishi Electric Research Lab

S. Y. Kung, Y. Wu, H. Kobayashi, S. Gezici, E. Fishler, V. PoorPrinceton University

Y. G. LiGeorgia Institute of Technology

H. Sheng, A. HaimovichNew Jersey Institute of Technology

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Contents

– System overview – Physical-layer details– Performance evaluation

– Signal robustness

– Coexistence

– Cost analysis

– Summary and conclusions

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Goals and Solutions

• Commonly used technology Time hopping impulse radio

• Fulfillment of spectral mask, but full exploitation of allowed power. Interference suppression Linear combination of basis pulses

• Cheap implementation, robustness to multipath Few Rake fingers, all A/D conversion and computation done at

200MHz

• Scalability Multi-code transmission

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Creation of Proposal

• Proposal based on

– Scientific experience of leading research groups (Princeton, Georgia Tech, MERL, MELCO)

– Practical experience of high-quality product development team of Mitsubishi in USA and Japan

– Experience in hardware (RF components, antennas, semiconductor, applications,…..) and applications design

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Data Source

Demultiplexer

Convolutional Code

Sync. & Training Sequence

Timing Logic

Timing Logic

Central Timing Control

Pulse Gen.TH Seq.-1

Pulse Gen.TH Seq.-N

PolarityScrambler

PolarityScrambler

Convolutional Code

Power Control

Multiplexer

Multiplexer

Transmitter Structure

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Receiver Structure

Synchronization

Rake ReceiverFinger Np

AGC

Demultiplexer Rake ReceiverFinger 2

Rake ReceiverFinger 1

Summer

Timing Control Channel Estimation

MMSEEqualizer

Convolutional Decoder Data

Sink

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Contents

– System overview – Physical-layer details

– acquisition

– channel estimation

– polarity hopping

– spectral shaping

– Rake structure

– Performance evaluation– Summary and conclusions

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Fast acquisition

• template signal and received signal need to be aligned

• standard method: serial search (chip by chip)• but: chip duration very short in UWB, takes

long time• our solution:

– Beacon provides rough timing estimation (within runtime of the piconet diameter)

– new “block search” methods for actual acquisition

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Block Search Algorithms

• Steps in acquisition:– Find delay region where signal is likely to exist

– After finding it, search in more detail for first significant path

• Block search algorithm– Sequantial block search (SBS): integrate output of

detector over delay region (block), search for block with significant energy. Best for LOS

– Average block search (ABS): average over absolute values of detector output. Best for NLOS

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Sequential Block Search

1) Check the bth block using the first template signal (t).

2) If the output of the bth block is not higher than a block threshold, τb, then, go to step 6.

3) If the output of the bth block is higher than the block threshold, τb, then search the block in more detail, i.e., cell-

by-cell serial search with a signal threshold τs, using the

second template signal (t).

4) If no signal cell is detected in the block, go to step 6.

5) If the signal cell is detected in the block, DONE.

6) Set b = (b mod B) + 1 and go to step 1.

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Average Block Search

1) Check difference between successive averages wi mod B - w(i-

1) mod B.2) If the difference is not higher than a first threshold go to

step 6.3) If the difference is higher than, check

z(i mod B)K+1, …, z(i mod B)+1)K serially, comparing to a second threshold, .

4) If no signal cells detected, go to step 6. 5) If signal cell(s) are detected, DONE. 6) Set i = (i + 1) mod B, and go to step 1.

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Channel Estimation

• Swept delay correlator

• Principle: estimating only one channel sample per symbol. Similar concept as STDCC channel sounder of Cox (1973).

• Sampler, AD converter operating at SYMBOL frequency

• Requires longer training sequence

• Three-step procedure for estimating coefficients:– With lower accuracy: estimate at which taps energy is significant

– With higher accuracy: determine tap weights

– Determine effective channel seen by equalizer

• “Silence periods”: for estimation of interference

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Channel Estimator – Block Diagram

Σ

Adj.Weight

ReceiverFront End

Programmable Training Waveform Gen.

Timing Controller

Programmable Training Waveform Gen.

Programmable Training Waveform GEN.

Multiplier & Low-Pass Filter

Multiplier &Low-Pass Filter

Multiplier &Low-Pass Filter

Adj.Weight

Adj.Weight

MMSE Equalizer

Equalizer Estimator

Channel Estimator

EQ TrainingSequence

Coefficients

EQ Output

Rake receiver OutputRake Finger 1

Rake Finger 2

Rake Finger N

Channel Estimation Output

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Estimator algorithm

510

0

1.

511c k t c f ck

h nT b y nT kN T

evaluation of one sample per 5ns interval, offset by Tc

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Estimator

• Multi-step procedure1. estimate which taps have significant weights

2. estimate tap weights for L significant taps

3. determine Rake receiver weights via minimum mean square error criterion

4. determine equivalent (symbol-spaced) channel from transmitter to output Rake receiver

5. find equalizer for this equivalent channel (MMSE)

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Modulation and Multiple Access

• Multiple access:– Combination of pulse-position-hopping and polarity hopping for multiple

access– More degrees of freedom for design of good hopping sequence than pure

pulse-position-hopping– Short hopping sequences, to make equalizer implementation easier

• Modulation: BPSK

• Channel coding: – rate ½ convolutional code; – requires 4dB SNR for 10^-5 BER– Improvement by 3dB possible by turbo codes

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Spectral Shaping & Interference Suppression

• Basis pulse: fifth derivative of Gaussian pulse

• Drawbacks:– Loses 3dB compared to FCC-allowed power

– Strong radiation at 2.45 and 5.2 GHz

Time (s) frequency (Hz)

Monocycle, 5th derivative of gaussian pulse Power spectral density of the monocycle

Ma

gn

itud

e o

f p

(t)

10

log

10|P

(f)|

2 d

B

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Linear Pulse Combination

• Solution: linear combination of delayed, weighted pulses– Adaptive determination of weight and delay

– Number of pulses and delay range restricted

– Can adjust to interferers at different distances

(required nulldepth) and frequencies

• Weight/delay adaptation in two-step procedure• Initialization as solution to quadratic optimization problem (closed-

form)

• Refinement by back-propagating neural network

• Matched filter at receiver good spectrum helps coexistence and interference suppression

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Initialization

• find “modified” mask that follows FCC and required interference suppression (e.g., 20dB for 802.11a

• approximate “optimum filling of mask” as

• solution of this in closed form (eigenvector belonging to largest eigenvalue)

2

[ , ]

| ( ) |min max , 1.

( )T

s

S jsubject to s Rs

M

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Iterative Refinement

• backpropagating neural network

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Rake Receiver

• Main component of Rake finger: pulse generator

• A/D converter: 3-bit, operating at 220Msamples/s

• No adjustable delay elements required

adj.weight

low-passfilter

programmablepulse gen.



rake finger

low-passfilter

low-passfilter

adj.weight

adj.weight

sample& A/D

sample& A/D

sample& A/D

sample timingcontroller

pulse sequencecontroller

Demultiplexer

Demultiplexer

Demultiplexer

Summer

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Contents

– System overview – Physical-layer details– Performance evaluation

– Signal robustness

– Coexistence

– Cost analysis

– Summary and conclusions

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Link BudgetParameter Value

Throughput (Rb) > 110 Mb/s 200Mb/s 480Mbit/s

Average Tx power ( TP ) -4.3 dBm -4.3 dBm -4.3 dBm

Tx antenna gain ( TG ) 0 dBi 0 dBi 0 dBi

maxmin' fff c : geometric center frequency of

waveform ( m inf and m axf are the -10 dB edges

of the waveform spectrum)

5.73GHz 5.73GHz 5.73GHz

Path loss at 1 meter ( )/4(log20 '101 cfL c )

8103c m/s

47.6 dB 47.6 dB 47.6 dB

Path loss at d m ( )(log20 102 dL ) 20 dB at d=10 meters

12 dB at d=4 meters

20 dB at d=4 meters

Rx antenna gain ( RG ) 0 dBi 0 dBi 0 dBi

Rx power ( 21 LLGGPP RTTR (dB)) -71.9 dBm -63.9 dBm -63.9 dBm

Average noise power per bit ( )(log*10174 10 bRN )

-93.6 dBm -91.0 dBm -87.2 dBm

Rx Noise Figure Referred to the Antenna Terminal ( FN )1

11 dB 11 dB 11 dB

Average noise power per bit ( FN NNP ) -82.6 dBm -80.0 dBm -76.2 dBm

Minimum Eb/N0 (S) 4 dB 4 dB 4 dB

Implementation Loss2 (I) 3 dB 3 dB 3 dB

Link Margin ( ISPPM NR ) 3.7 dB 9.1 dB 5.3 dB

Proposed Min. Rx Sensitivity Level3 -78.9 dBm -70.9 dBm -70.9 dBm

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

PER as Function of Distance

0 2 4 6 8 10 12 14 16 18 200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Distance (m)

PE

R

AWGN

CM1

CM2

CM3

CM4

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

0 2 4 6 8 10 12 14 16 18 200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Distance (m)

Pro

ba

bili

ty o

f Lin

k S

ucc

ess

CM1

CM2

CM3

CM4

Probability of Link Success

Sensitivities:

AWGN 13m

cm1 6.8

cm2 6.2

cm3 5.3

cm4 5.0

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Outage vs. SNR

0 5 10 15 200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

90% outage PER function of the Eb/No

Eb/N0 dB

90%

out

age

prob

abili

ty

CM1

CM2

CM3

CM4

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

0.5 1 1.5 20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Interfering Piconet Separation Distance (m)

PE

RAverage PER over 4 channel models with one interfering piconet from cm1

test link: 20 first realizations of cm120 first realizations of cm220 first realizations of cm320 first realizations of cm4

Specified PER = 8%

Single co-channel interferer separation distance

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission


0.5 1 1.5 20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Interfering Piconet Seperation Distance (m)

PE

RAverage PER over 4 channel models With One Interfering Piconet Throught CM3

CM4

CM3

CM2

CM1

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission


0.5 1 1.5 20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Interfering Piconet Seperation Distance (m)

PE

R

Average PER over 4 Channel Models With One Interfering Piconet Through CM4

CM1

CM3

CM4

CM2

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Test link uncoordinated piconet dint AWGN AWGN < 0.5 m

20 first realizations of cm1 21st realization of cm1 0.9 m 20 first realizations of cm2 21st realization of cm1 0.9 m 20 first realizations of cm3 21st realization of cm1 1.1 m 20 first realizations of cm4 21st realization of cm1 1.4 m 20 first realizations of cm1 21st realization of cm3 0.9 m 20 first realizations of cm2 21st realization of cm3 0.9 m 20 first realizations of cm3 21st realization of cm3 1.2 m 20 first realizations of cm4 21st realization of cm3 1.4 m 20 first realizations of cm1 21st realization of cm4 0.95 m 20 first realizations of cm2 21st realization of cm4 1.0 m 20 first realizations of cm3 21st realization of cm4 1.4 m 20 first realizations of cm4 21st realization of cm4 1.4 m


May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Susceptibility to Interference

• Piconets– 20 first realizations of the 4 channel model and AWGN

– Desired user: 6dB above sensitivity

• admissible distance of interferer: between 0.5 and 1.5m

• 802.11a: influence only when interferer less than 0.4m distance, in CM2

• 802.11b: no noticeable influence (even at 0.3m distance of interferers) in all cases

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Coexistence (at 1m)

System

Desired

Achieved

FCC Mask

802.11a

- 88 dBm

- 90 dBm

- 75 dBm

802.11b

- 82 dBm

- 85 dBm

- 70 dBm

802.15.1

- 76 dBm

- 95 dBm

- 80 dBm

802.15.3

- 81 dBm

- 85 dBm

- 70 dBm

802.15.4

- 91 dBm

- 95 dBm

- 80 dBm

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Cost Estimates (for 110Mbit/s mode)

• TX– Digital:

• Coders 100k gates

• timing logic <100k gates

– RF

• Pulse generators (4): 0.6mm2

• Polarity scramblers 0.04mm2

• Summers 0.04mm2

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Cost Estimates (for 110Mbit/s mode)

• RX– Digital:

• Viterbi Decoder 100k gates

• timing logic <100k gates

• MMSE equalizer 50k gates

• Rake finger weighting and summing <50k gates

– RF

• LNA (11dB SNR) 0.05mm2

• Pulse generators (2*10): 3.2mm2

• Polarity descramblers 0.04mm2

• Low-pass filters 0.48mm2

• Summers 0.04mm2

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Cost Estimates - Summary

• RF part: – total die size <10mm2 – less than Bluetooth

– 0.18mu CMOS technology sufficient

• Digital part:– Less than 500k gates

– Operation at 220Mbit/s

• Antenna: cavity-backed spiral antenna• Total costs comparable to Bluetooth

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Self-Evaluation (I)

CRITERIA REF. IMPORTANCE

LEVEL PROPOSER RESPONSE

Unit Manufacturing Complexity (UMC)

3.1 B Comparable to Bluetooth

Signal Robustness

Interference And Susceptibility

3.2.2 A No noticeable impact by interferers

Coexistence 3.2.3 A Does not disturb at 1m distance

Technical Feasibility

Manufacturability 3.3.1 A Cost comparable to Bluetooth

Time To Market 3.3.2 A Uses technology that is available now

Regulatory Impact 3.3.3 A Fulfills FCC requirements

Built-in flexibility for future European and Japanese standards

Scalability (i.e. Payload Bit Rate/Data Throughput, Channelization – physical or coded, Complexity, Range, Frequencies of Operation, Bandwidth of Operation, Power Consumption)

3.4 A Scalability by variable spreading factor (for data rates 110Mbit/s)

Multicode transmission (for >110Mbit/s)

Location Awareness 3.5 C Could be added

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Self-Evaluation (II)CRITERIA REF.

IMPORTANCE LEVEL PROPOSER RESPONSE

Size And Form Factor 5.1 B Determined by antenna: 65*40mm

and battery

PHY-SAP Payload Bit Rate & Data Throughput

Payload Bit Rate 5.2.1 A 110Mbit/s (?)

PHY-SAP Data Throughput 5.2.2 A 80Mbit/s

Simultaneously Operating Piconets

5.3 A Minimum distance

Signal Acquisition 5.4 A <12 microseconds

Link Budget 5.5 A 3dB link margin in AWGN at 10m

Sensitivity 5.6 A -73dBm

Multi-Path Immunity 5.7 A Multipath penalty <7dB

Power Management Modes 5.8 B (i) active

(ii) standby

Power Consumption 5.9 A

Antenna Practicality 5.10 B Suggested antenna in use today

May 2003


doc.: IEEE 802.15 03111r1_TG3a

Submission

Summary and Conclusions

• TH-IR based standards proposal– Meets targets of 802.15.3a for LOS

• Innovative way to manage spectrum– Meet FCC requirements

– Improve performance in interference environment

– Decrease interference to other systems

• Allows cheap implementation– All digital operations at symbol rate, not chip rate

• Scaleable– Multicode / multirate system.

Doc.: IEEE 802.15 03111r1_TG3a Submission May 2003 Molisch et al., Time Hopping Impulse Radio...

Documents

Transcript of Doc.: IEEE 802.15 03111r1_TG3a Submission May 2003 Molisch et al., Time Hopping Impulse Radio...