UWB Channel Impulse Response Acquisition G.C. Ferrante , Y. - - PowerPoint PPT Presentation

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UWB Channel Impulse Response Acquisition G.C. Ferrante , Y. - - PowerPoint PPT Presentation

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UWB Channel Impulse Response Acquisition G.C. Ferrante , Y. Elhillali , M.-G. Di Benedetto , F. Boukour , R. Atika Sapienza, Rome, Italy Ecole Sup erieure dElectricit e, Gif-sur-Yvette, France Univ.

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SLIDE 1

UWB Channel Impulse Response Acquisition

G.C. Ferrante⋆†, Y. Elhillali∗, M.-G. Di Benedetto⋆, F. Boukour•, R. Atika∗

⋆ Sapienza, Rome, Italy †´

Ecole Sup´ erieure d’Electricit´ e, Gif-sur-Yvette, France

∗ Univ. Valenciennes, Valenciennes, France

  • IFSTTAR, Lille, France

October 9, 2013

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 1 / 14

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SLIDE 2

Introduction

Outline

1 Introduction 2 Coherence time 3 MISO UWB systems with TR

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 2 / 14

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Introduction

Introduction

Goal

  • report on experimental activities on UWB;
  • show examples of collected data;
  • future post-processing works aimed at studying:

1 coherence time in UWB; 2 TR MISO-UWB insensitivity to lack of correlation between channels.

Equipment

  • waveform generator (DAC up to 10 GHz);
  • receiver front-end (ADC up to 20 GHz, quantization 8 bits);
  • antennas (2 directive, 1 omni, up to 18 GHz);
  • anechoic chamber, reflectors.

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 3 / 14

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SLIDE 4

Coherence time

Outline

1 Introduction 2 Coherence time 3 MISO UWB systems with TR

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 4 / 14

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SLIDE 5

Coherence time

Introduction

  • time interval Tc during which the channel remains “unchanged”;
  • in narrowband communications, fading remains constant during Tc;
  • in UWB communications, multipath remains correlated during Tc;
  • important for estimating the blocklength and the training repetition period;
  • Novelty: no available measurements beyond 1.5 GHz.

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 5 / 14

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SLIDE 6

Coherence time

Description on how to study coherence time in UWB

  • 1 tx antenna, 1 rx antenna (distance ≈ 4 meters);
  • pulse bandwidth: W ∈ (0, 3] GHz.
  • pulse repetition time: 400 ns;
  • 500 realizations of sampled and quantized rx signal averaged and saved;
  • 200 times with interval of 5 secs.

Scheme .

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 6 / 14

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SLIDE 7

Coherence time

Example of collected data

12 14 16 18 20 22 24 26 28 30 −0.04 −0.03 −0.02 −0.01 0.01 0.02 0.03 time (ns) 200 s 100 s 0 s

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 7 / 14

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SLIDE 8

MISO UWB systems with TR

Outline

1 Introduction 2 Coherence time 3 MISO UWB systems with TR

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 8 / 14

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SLIDE 9

MISO UWB systems with TR

Multi-antenna TR

Scheme of single-antenna TR . Scheme of multi-antenna TR (Nt = 2) .

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 9 / 14

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SLIDE 10

MISO UWB systems with TR

Description on how to study MISO UWB systems with TR

  • recent result: SNR with TR is insensitive to lack of correlation between

channels;

  • why is this important?

.

  • decorrelate LOS channels by increasing the distance between tx antennas:

decorrelation was negligible up to ≈ 1 m;

  • decorrelate channels in an anechoic chamber by introducing reflectors:

channels were totally different

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 10 / 14

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SLIDE 11

MISO UWB systems with TR

Signals

  • tx signal: y = Hp b + n = x b + n;
  • power constraint: E
  • p b2

= Ep2 = E;

  • channel model:

hT(ℓ) = √vℓ ·

  • κ

1 + κρhT

0δℓ0 +

  • 1

1 + κρhT

w(ℓ)Θ1/2

  • ;

Example: identical channels Θ = 11T; uncorrelated channels: Θ = I.

  • rx signal after detection: z wTy = wTx b + wTn = ζ + ν;

Example:

  • one-finger Rake (tap i): w = ei;
  • All-Rake: w = Jx (J reflection matrix);
  • performance measure: SNR E
  • |ζ|2

E[ |ν|2 ] = E σ2

N

· (wTHp)2 w2 ,

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 11 / 14

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SLIDE 12

MISO UWB systems with TR

Signals

Given h:

  • All-Rake: SNR =

E Ntσ2

N L

  • ℓ=0
  • hT(ℓ)1
  • 2
  • TR, one-finger: SNR = E

σ2

N

hr2 = E σ2

N L

  • ℓ=0

h(ℓ)2. On average:

  • All-Rake: E[ SNR ] =

EG Ntσ2

N

  • κρ

1 + κρ · (hT

01)2 +

1 1 + κρ · (1TΘ1)

  • .

Example:

  • identical channels: E[ SNR ] = EGNt/σ2

N;

  • uncorrelated channels: E[ SNR ] =

EG Ntσ2

N

  • κρ

1 + κρ · Nt + 1 1 + κρ

  • < EG

σ2

N

;

  • TR, one-finger: E[ SNR ] = EG

σ2

N

Nt ← − Goal (future): to be verified experim.

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 12 / 14

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SLIDE 13

MISO UWB systems with TR

Further investigations with the data set

  • Diversity order.

Sub-linear behavior at very high bandwidth (tens of GHz) by studying the rank of the sample-covariance matrix.

  • Sparsity.

Confirm measurements suggesting non-sparse behavior up to 3 GHz by evaluating power-delay profile.

  • Non-Gaussianity.

Verify the validity of the Ricean uncorrelated scatter model beyond 3 GHz.

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 13 / 14

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SLIDE 14

MISO UWB systems with TR

Thank you for your attention!

Ferrante et al. UWB Channel Impulse Response Acquisition October 9, 2013 14 / 14