S-Band Digital Multimedia Satellite Broadcasting Services

for

Personal & Mobile Users in Japan

Yoshitake YAMAGUCHI

Mobile Broadcasting Corporation 5-2-1, Ginza, Chuo-ku, Tokyo 104-0061 JAPAN

E-mail: yama@mbco.co.jp

Abstract World’s first S-band satellite digital broadcasting services for personal and mobile users by use of 2.6GHz radio

frequency band is planned to be launched in 2004 in Japan and also in Korea. The satellite is co-owned by Mobile

Broadcasting Corporation in Japan and SK Telecom in Korea. This service consists of a large number of various multimedia

broadcasting programs such as high quality digital audio programs and video programs and is able to be received with small

portable receivers and vehicular at any time and anywhere Nation-wide. In order to realize this “with Me” service, a

geostationary satellite with high power transponders and a high gain 12-m large deployable antenna is used. Terrestrial

repeaters, called Gap Fillers, which transmit broadcasting signal to the areas where the satellite signal is blocked by obstacles,

are also used in urban areas. The “System E” registered in ITU has been applied to this satellite broadcasting system, which

has employed CDM (Code Division Multiplex) technology and RAKE receivers for effective utilization of spectrum as well as

mitigation of multi-path fading. The satellite, MBSAT, has been launched successfully by Atlas-IIIA and variety verification tests

have been carried out to evaluate the total system performance. In this paper, recent development status of both the system

and services is described.

Keyword Satellite, Broadcasting, Mobile, S-band, System E, CDM, RAKE receiver

1. Introduction Mobile Broadcasting Corporation (MBCO) will

launch the Worlds’ first satellite digital multimedia

broadcasting services from July of 2004 in Japan.

The new S-band digital multimedia broadcasting

services is the real ubiquitous broadcasting system

and the most significant characteristics of the system

are as followings:

- Mobile users on car, train, in outfield, home and

office can enjoy nationwide multimedia

broadcasting services containing 7~10 channels of

TV and Data programs with 30~60 channels of

audio programs using small omni directional

receiving antenna.

- A High EIRP GSO satellite and ground repeater

system, so called “Gap Filler” will enable a

seamless reception even in the shadowing area

where the satellite signal would be blocked by high

tall buildings in urban area.

This service has also had feature of a joint project

between Japan and Korea so that the S-DMB service

will open the promising era in Asia. The S-band GEO

satellite is co-owned by MBCO and SK Telecom, and

TU Media Co. will launch their S-DMB (Satellite

Digital Multimedia Broadcasting) service in Korea at

the same time of Japan’s MBCO service.

This brand-new multimedia mobile broadcasting

service is expected to be a large growing market

both in Japan and Korea.

2. Mobile Broadcasting System The system of mobile multimedia broadcasting is

the first system to use 25MHz bandwidth that ranges

from 2630MHz to 2655MHz that is allocated for

satellite digital sound broadcasting service in WARC

92 (World Administrative Radio Conference).

Figure 1 shows the outline diagram of the entire

broadcasting System. The broadcast waves delivered

from the broadcasting center are transmitted � to

22nd AIAA International Communications Satellite Systems Conference & Exhibit 20049 - 12 May 2004, Monterey, California

AIAA 2004-3213

Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

2

MBSAT (Mobile Broadcasting Satellite), our exclusive

satellite using Ku band where they get converted to S

band of 2.6GHz and on amplifying the power are

broadcasted throughout Japan with the help of a

large-sized deployable transmit antenna.

To generate enough EIRP for mobile reception, the

satellite is needed to be equipped with a large

deployable transmit antenna and a high-power

transponder.

Users of this service can receive the broadcasting

signal via the satellite using receivers equipped with

small and low directivity antennas.

Figure-1 System Configuration

The broadcast from the MBSAT enables to cover

throughout Japan with a single frequency, but in

cities where the broadcast cannot be received

directly due to the blockage caused by buildings,

terrestrial repeaters (Gap- Fillers) are installed to

improve the reception in those areas. The Gap Fillers

transmit the same signal as the satellite signal to

cover the area where the satellite signal is blocked

by the obstacles.

3

Table 1 shows the parameters of this system.

Table 1 System Parameters

3. Features of Broadcasting System Programs are sent to broadcasting satellite

(MBSAT) using Ku band of 14GHz from the

broadcasting center after encoding and multiplexing.

After converting to S band of 2.6425GHz in the

MBSAT, the programs are broadcasted as the

amplified broadcast waves throughout Japan by use

of large S band deployable antenna.

The stable reception of the broadcasting signal can

be performed even in mobile environment by using

CDM, RAKE technique, error correction and

interleave technology described in the followings.

3.1. Base Band Multiplexing / Coding

Method For the base band multiplexing method, MPEG-2

System (ISO/IE 13818-1) is adopted and also for

audio coding, MPEG-2 AAC is adopted. In multimedia

data broadcasting, the coding method adopted for

image is MPEG-4 Visual.

3.2. CDM Modulation Method By using CDM (Code Division Multiplex) technology,

the satellite signal and Gap-Filler signals can be

allocated to the same frequency so that effective

frequency utilization can be achieved. Numbers of

broadcasting signals are spread by their own Walsh

codes and a pseudo random signal, and then

multiplexed on the same frequency and transmitted

as a broadcasting signal. These spread data

sequences are modulated into a QPSK signal.

The broadcasting signal transmitted from a gap-filler

is reflected and refracted in diverse directions by

various objects like buildings and then arrives at

receivers. This type of reception environment is

known as “multipath environment”.

CDM technology has a feature and advantage to

be suitable for receiving a broadcasting signal in

such multipath environment [2].

RAKE receiver is also indispensable to accomplish

stable reception of the broadcasting signal in the

multipath environment.

3.3. Error Correction and Interleave To improve the reception tolerance due to the

multipath fading environment, convolution code as

inner code and Reed Solomon code (RS [204, 188])

as outer code are adopted as forward error

correction codes [2].

Further adoptions of byte-wise interleave and

bit-wise interleave as interleave methods for the

system has enabled proper reception under the

mobile environment.

The bit-wise interleave enables to recover up to

1.3 seconds blackout of received signals.

4. Development Status

4.1. Satellite and Launch Vehicle To realize the system, the MBSAT of a

geostationary satellite with high power S band

transponders and a 12m-diameter S band high gain

antenna is required.

The MBSAT was launched successfully by the

Atlas-IIIA from Cape Canaveral Air Force Station,

Florida at 14:41(JST) in 13 th of March, 2004.

Figure 3 shows our launch and on-orbit

configuration of the MBSAT. The MBSAT receives Ku

band uplink signal transmitted from the Broadcasting

center and transmits it by S band and Ku band

downlink signals to service areas all over Japan. The

MBSAT is a three-axis attitude stabilized satellite

designed and manufactured by Space Systems/Loral

(SS/L), USA.

The 12m-diameter deployable antenna and power

combination tree of numbers of TWTAs are equipped

with to achieve S-band high EIRP toward Japan. The

satellite also has a Ku-band transponder, which is

used to transmit the signal for Gap-Fillers.

1 Carrier Frequency 2.6425GHz (Bandwidth: 25MHz)

2 Modulation CDM 3 Chip rate 16.384Mcps

4 Processing gain 64 5 Spreading Code (1) Walsh Code

(2) Truncated M-sequence 6 Error Correction (1) Convolutional Coding

(2) RS Coding 7 Interleaving (1) Byte Interleaving

(2) Bit Interleaving 8 Audio Source

Coding MPEG-2 AAC

9 Video Source Coding

MPEG-4

4

The MBSAT is now under operation on orbit.

Figure 2 (a) MBSAT Launch by the Atlas-IIIA

Figure 2 (b) MBSAT On-Orbit Configuration

4.2. Terrestrial Repeaters (“Gap-Fillers”) Gap-Filler is an instrument for delivering the S

band broadcast signals to receivers. The Gap-Filler

consists of receiving antenna, signal-processing unit,

distributor, transmission amplifier and antenna. There

are three transmission amplifiers and antennas in

one set of the Gap-Filler to cover directions of 360

degrees around the installed Gap-Filler.

Figure 3 shows the block diagram of a Gap-Filler.

The signals used for Gap-Filler are sent from the

Broadcasting center using TDM signals, and relayed

by the satellite. The TDM modulated signals for the

Gap-Filler from the satellite is once demodulated and

then CDM modulated so that it become the same

signal as the S-band satellite signal directly received

by receivers.

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Figure 3 Block Diagram of a Gap-Filler

Typically Wide range Gap-Filler covers the radius

of 1km – 3km and Narrow range Gap-Filler covers

the places such as tunnels, underground areas or

interiors of shopping malls, storages, etc.

Installation of the commercial Gap-Fillers has

started from January 2003. Gap-Fillers have been

deployed mainly in Metropolitan area like Tokyo,

Osaka and Nagoya. Following the metropolitan area

it will be extended over the country.

4.3. Broadcasting Center Broadcasting center carries out 24-hour

transmission of broadcasting RF signals. The

Broadcasting center equipped the main antenna with

7.6m-diameter will be completed by the end of June

2003.

5

Figure 3(a) and 3(b) shows the artist view of the

broadcasting center and the up-to-date digital

operation center located in Tokyo metropolitan area.

Figure 3 (a) Broadcasting Center

Figure 3 (b) Digital Operation Room

4.4. Receivers Receivers for Mobile Broadcasting should be

smaller and should have low power consumption. In

order to meet these requirements, LSI employed for

the Mobile Broadcasting receivers has been

developed under the cooperation of Toshiba

Semiconductor Company.

Figure 4 shows a palm-top TV-style prototype

receiver made by the second-generation LSI chip

sets. The size of the receiver is 75mm x 112mm x

22mm. The weight of the receiver is about 200g

including the battery and two antennas. Vehicular

and portable receivers will be available at the

beginning of the service.

Figure 4 Prototype Receiver

4.5. Programs Mobile Broadcasting channel service plan includes

a variety of music and sound programs as an audio

service, and also news, sports and entertainment

programs together with various informative and

interactive contents as a multimedia service.

At the beginning of our service, 7 video, 30 audio

channels and data channel will be provided. Then it

is also planed to expand the contents, which means

the number of channels, to meet the subscribers ’

demands,

5. Conclusion Mobile Broadcasting Corporation realizes the new

Broadcasting service which provides the mobile and

personal users with wide variety of program contents,

e v e n wh e n t h e y a r e m o v i n g a t h i g h s p e e d .

The World’s first multimedia mobile and personal

broadcasting services will start in summer of 2004.

References [1] ITU-R Recommendation, “Systems for digital

satellite broadcasting to vehicular, portable and fixed receivers in the bands allocated to BSS (sound) in the frequency range 1400-2700 MHz,” Rec. ITU-R BO.1130-4, 2001

[2] Hideo KIKUCHI, Yoshitake YAMAGUCHI,

“Satellite Digital Sound Broadcasting System for Mobile Users in Japan”, 2002 Joint Conference on Satellite Communications (JC-SAT 2002), October 10-11, 2002