Transmission Analysis of Digital TV Signals over a Radio ... Generation FSO system=Direct coupling between optical fiber and free-space Free Space Optics (FSO)… refers to the transmission

Cape Town, South Africa 12–14 December 2011

Chedlia Ben Naila1, Kazuhiko Wakamori1, Mitsuji Matsumoto1

and Katsutoshi Tsukamoto2

¹GITS, Waseda University, Japan

²Graduate School of Engineering, Osaka University, Japan

[email protected]

Transmission Analysis of Digital TV Signals over a Radio-on-FSO Channel

ITU Kaleidoscope 2011 The fully networked human?

Innovations for future networks and services

Outline

Introduction

Overview of Radio over FSO Technology

Experimental Evaluation of ISDB-T based

Wireless Services Transmission over RoFSO

Channel

Conclusion

Cape Town, South Africa, 12-14 December 2011 ITU Kaleidoscope 2011 – The fully networked human? Innovations for future networks and services

Introduction

Overview of Radio over FSO Technologies



Channel

Conclusion


Outline

Introduction

The need to communicate, exchange and share information prompted the deployment of devices and applications such as:

MOBILE PHONES, HOME PHONES, BROADBAND,

OFFICE PHONES, DIGITAL TV, VIDEO CONFERENCING,

TELEMEDICINE, TELE-TEACHING AND MANY OTHERS

ARE EMERGING BY THE DAY

These applications and the emerging ones

all have one “common effect” on the end

users/businesses…

…increased Bandwidth requirement!

Deployment of optical fiber in the backbone and metro networks have made huge bandwidth available to within one mile of businesses/homes in most places.

How can users have access to the required high bandwidth?

But… time consuming, digging, need for permission…

Optical fiber

4 4


Radio over FSO (RoFSO)… RoFSO = FSO + RoF

Next Generation FSO system=Direct coupling between optical fiber and free-space

Free Space Optics (FSO)…

refers to the transmission of visible and infrared (IR) beams through the atmosphere to obtain optical communications.

Overview of RoFSO systems


5 5

Proposed DWDM RoFSO system

Uses 1550nm wavelength

Transport multiple RF signals using

DWDM FSO channels

Realize heterogeneous wireless

services e.g. WLAN, Cellular,

terrestrial digital TV broadcasting etc Heterogeneous wireless service signals

RoF RoF DWDM RoFSO channel

Free-space beam directly coupled to optical fiber

RoFSO antenna

Free Space Optics Standards Start!


In March 2006, the first ITU-T Recommendation has been published: Entitled “Co-location longitudinally compatible interfaces for free space optical systems”, ITU-T Recommendation G.640 (ex G.fso) means that users of FSO systems will be able to co-locate FSO solutions provided by different manufacturers for the first time. Calculations of the conditions required to be met to prevent interference in some examples of co-located FSO systems are also included.

Need for a ITU-T standardization study for maturity and rapid adaptation of the newly developed RoFSO technology.

6 6

Introduction




Channel

Conclusion


Outline

Vx Vy

2-axis gimbal

PID

controller

Rough tracking sensor

with 850 nm beacon

Fine tracking

sensor with QD

SMF Signal light

Direct coupling between

Space and SMF

Collimator & Fine

Pointing Mirror

Q1 Q2

Q3 Q4

x

P1 P2 P3 P4

QD

y

Forward / Backward

beam on single axis

Error evaluation

electronics

Beacon (850 nm)

Parameter Value

Communication wavelength 1550 nm

Beacon wavelength 850 nm

Antenna aperture 80 mm

Beam divergence

Optical transmit power

Coupling losses

47.3μrad

20 dBm

5 dB

DWDM RoFSO antenna specifications

PID：proportional-integral-derivative

RoFSO antenna optical path and device layout

Key features:

Optimized for transmission of RF

signals.

Can suppress most of effects induced

from atmospheric turbulence like

beam wander, AOA fluctuations.

Experimental Setup of RoFSO System


8 8

2.5 Gbps

Opt. Rx

RoFSO antenna

SM-Fiber

Optical IF-unit

RF-IF-unit

ISDB-T Signal analyzer

Opt. Spectrum Analyzer

Power meter

3dB coupler

RF-IF-unit

Data logging PC

ISDB-T Signal generator

Data logging PC

BERT

BERT

Output monitor

RoFSO antenna

Optical IF-unit

Site2: Bldg. 55S Okubo Campus Site1: Bldg. 14 Nishi Waseda Campus

1 km

2.5 Gbps

Opt. Rx

FSO link

EDFA EDFA

Atmospheric turbulence, rain, fog,…

Schematic Diagram of RoFSO system 9 9


Layer A (LDTV, Audio,

Data)

Layer B (HDTV or 3 SDTV

with data)

13 segments (6 MHz bandwidth)

frequency

Fixed and mobile reception (HDTV, etc)

Handheld reception (1seg service)

ISDB-T channel segments and services

ISDB-T Signal Transmission: Introduction

Integrated Service Digital Broadcasting - Terrestrial (ISDB-T) is one of international standard for terrestrial DTV broadcasting format developed and adopted in Japan and in almost all the South American countries.


10 10

Countries and territories using ISDB-T in green (Wikipedia)

The bandwidth is divided into 50 channels numbered from 13 to 62. Each channel is further divided into 13 OFDM segments which includes a single segment, (Layer_A or 1seg) for mobile receivers (LDTV, audio and data) and the remainder can be allocated as one 12-segments (Layer_B) for high definition television (HDTV) programs.

Parameter Value

Mode 3

Layer A B

Number of segments 1 12

Modulation scheme 16 QAM 64 QAM

Information bit rate 624.13 19660

Required CNR/MER (dB)

11.5 22.2

ISDB-T Transmission parameters

Received ISDB-T signal spectrum

6 MHz offset

Movie Clip

Test pattern

Ch 13 Ch 14

ISDB-T Signal Transmission Characteristics

11 11


ISDB-T Modulation analysis and Received Optical Power Characteristics

ISDB-T Constellation Map

1seg (MER= 23dB), 12seg (MER= 23dB),

1seg (MER= 35dB), 12seg (MER= 35dB)

ISDB-T Signal Transmission: MER Evaluation (1/2)

12 12


Ideal Symbol

(Ij,Qj) dQj

dIj I

Q Q

I

(Ij,Qj)

RMS Error Magnitude

Average Symbol Magnitude

Modulation Error Rate (MER) Definition:


13 13 ISDB-T Signal Transmission:

MER Evaluation (2/2)

Variation of the MER versus the received optical power

Variation of Average and Variance of ISDB-T MER with the

refractive index 2

nC

Test Signal : ISDB-T_16QAM_1_2 (Layer A 1seg 16QAM, Layer B 12seg 64QAM)

The CDF Layer A and Layer B BER ISDB-T BER and Rx. optical power characteristics

Error Free

Error Correction limit 4102

4102

ISDB-T Signal Transmission: BER Evaluation


14 14

Introduction




Channel

Conclusion


Outline

An experimental evaluation on transmission of ISDB-T service signals using a newly developed advanced DWDM RoFSO system under real operational environment has been presented.

Transmission performance evaluation of the proposed RoFSO system has demonstrated consistent performance in terms of specified quality metric parameters for the OFDM based digital TV signals in the absence of severe weather conditions and using properly design interface units.

The obtained results confirm the technical feasibility and practicality of utilizing the RoFSO system as a universal platform for providing ubiquitous wireless services.

The presented work on the newly developed RoFSO system can offer guidelines for an ITU-T standardization study for rapid adaptation of such technology.

Conclusion


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Thank you for your attention!

This work was supported by a grant from the National Institute of

Information and Communications Technology (NICT) of Japan.


Chedlia Ben Naila

Waseda University, Tokyo, Japan

[email protected]

mailto:[email protected]

Documents

Transmission Analysis of Digital TV Signals over a Radio ... Generation FSO system=Direct coupling between optical fiber and free-space Free Space Optics (FSO)… refers to the transmission