ON THE DVB-SH SYSTEM ARCHITECTURE

INCORPORATING T-DMB

Min-Su Shin, Duk-Gil Oh

ETRI, Daejeon-Si, Euseong-Gu,Gajeongro, Korea

Un-Rak Choi, Bo-Seok Seo

Chungbuk National University, Chungbuk Cheong-Si, Heungduk-Gu, Korea

Keywords: DVB-SH, T-DMB, satellite multimedia service.

Abstract: In this paper, we investigate the transmission system architecture to incorporate the terrestrial digital

multimedia broadcasting (T-DMB) service contents into the DVB-SH systems. The T-DMB is operating in

Korea to provide a TV-like service in mobile or static environments. The DVB-SH system provides a

variety of mobile multimedia services through hybrid satellite and terrestrial links and has a universal

coverage. We propose two methods to provide the T-DMB contents to handheld or mobile terminals via

DVB-SH architectures and investigate the features of them.

1 INTRODUCTION

In February 2007, DVB-SSP working group has

approved the DVB-SH (digital video broadcasting

for satellite services to handhelds) specification

(ETRI, 2007). The DVB-SH, which is a new name

of DVB-SSP, is defined as a system which is able to

deliver IP based multimedia contents to handheld

terminals like mobile phones and PDAs via satellite

link at frequencies below 3 GHz. A typical DVB-SH

system is based on a hybrid architecture combining a

satellite component and a complementary terrestrial

component. In satellite link, data is transmitted by

orthogonal frequency division multiplexing (OFDM)

and/or time division multiplexing (TDM)

transmission modes, while only OFDM transmission

mode is used in terrestrial link. The OFDM

transmission mode is based on the DVB-H air

interface, which is originally based on the DVB-T

system, and slightly modified for satellite

application. On the other hand, the TDM mode is

based on DVB-S2 air interface. In both cases, strong

channel coding and time interleaving techniques are

applied for overcoming the nonlinear effect of the

high power amplifier operating near saturation.

Terrestrial digital multimedia broadcasting (T-

DMB) is in service successfully in Korea. The T-

DMB is based on Eureka-147 digital audio

broadcasting (DAB) system. Through the stream

mode data channel of DAB system, multimedia

contents such as video, audio and data are

transmitted with maximum rate of 1.062 Mbits/s.

In this paper, we investigate the architectures of

the DVB-SH system to deliver the T-DMB contents

via satellite and terrestrial links.

2 DVB-SH ARCHITECTURE

INCORPORATING T-DMB

2.1 Structure of the T-DMB System in

Korea

The main service of T-DMB is to provide TV

broadcasting to handheld or mobile terminals such

as mobile phones, PDAs and car TVs. Multimedia

data including audio and video (AV) signal are

transmitted through the Eureka-147 DAB system

(Lee, 2005). The standard structure of the T-DMB

system is shown in Figure 1.

Encoded multimedia data are multiplexed into

MPEG-2 transport stream (TS) and then encoded for

forward error correction (FEC) by using Reed

Solomon (RS) coding and convolutional interleaving.

166

Shin M., Oh D., Choi U. and Seo B. (2007).

ON THE DVB-SH SYSTEM ARCHITECTURE INCORPORATING T-DMB.

In Proceedings of the Second International Conference on Wireless Information Networks and Systems, pages 166-168

DOI: 10.5220/0002150401660168

 SciTePress

The encoded stream is then transmitted through the

stream mode channel of the existing Eureka-147

DAB system. RS encoder use RS(204, 188, t=8)

shortened code derived from the original systematic

RS(255, 239, t=8) code as in the DVB-T system

(ETSI, 2001). By adding the additional FEC and

interleaving, the target bit error rate (BER) of the

system is improved from the level of

−

and by which high quality mobile video service is

possible through the Eureka-147 DAB system which

is originally designed for CD quality audio data

transmission. Fig. 2 shows the total transmission

system for T-DMB including the Eureka-147

transmission blocks.

Stream mode data channel

OFDM

Modulator

Multi-

plexer

Fast information channel

Service information

DAB audio frame channel

Packet mode data channel

Eureka-147 transmission system

Convolutional

interleaver

encoder

MPEG-2 TS

multiplexer

Encoded

data

T-DMB processor

MPEG-2 TS

Figure 1: Structure of the T-DMB system.

T-DMB

Encoder

Outer

interleaver

Outer

Coder

MPEG-2 TS

Scrambler

Conv.

Encoder

Time

Interleaver

MSC

Multiplexer

OFDM

Modulator

Frame

Multiplexer

Eureka - 147

Figure 2: Transmission system of T-DMB.

2.2 DVB-SH System Architecture

The DVB-SH system is developed to provide

multimedia services over hybrid satellite and

terrestrial networks to a variety of fixed or mobile

terminals including handheld, vehicle-mounted,

nomadic and stationary terminals at frequencies

below 3 GHz. It has a universal coverage by

combining a satellite component and a

complementary ground component. In the DVB-SH

system, there are two architectures applying two

modulation methods: SH-A for OFDM terrestrial

and OFDM satellite transmission mode, and SH-B

for OFDM terrestrial and TDM satellite transmission

mode.

Figure 3 shows the two architectures for different

modulation method (ETSI, 2007). As shown in the

figure, the two transmission systems are designed to

maximize the commonalities between them. OFDM

transmission mode is mainly based on the existing

DVB-T or DVB-H systems, while TDM

transmission mode is mainly based on DVB-S2

system. Main blocks newly introduced by DVB-SH

includes strong FEC and longer time interleaver

which aims to overcome long fading events under

the low signal-to-ratio mobile satellite and terrestrial

environments. The final sentence of a caption should

end with a period.

2.3 DVB-SH System Incorporating the

T-DMB

One of the purpose in incorporating the T-DMB

system into DVB-SH systems is to maximize the

commonalities between the existing T-DMB and

DVB-SH systems in order to maximize hardware

reuse. The DMB processor in the T-DMB system

correspond to the IP encapsulator in the DVB-SH

system. However, MPEG-2 TS data are processed

by RS encoder in a DMB processor while the output

of the encapsulator, which performs RS coding and

interleaving, has the form of MPEG-2 TS. Moreover

the error correction capability in the two systems are

different. In DVB-H, by passing the multi-protocol

encapsulation (MPE) with RS(255, 191) coding, the

RS decoder allows correcting up to 32 erroneous

bytes (Balaguer , 2005). Instead RS decoder gives 8-

byte correcting capability in T-DMB system by

using RC(204, 188) code (Lee, 2005). Therefore, we

cannot input the output of the DMB processor

instead of the output of the IP encapsulator in the

DVB-SH system.

One method to provide T-DMB contents

simultaneously or similarly via DVB-SH network is

input the DMB processor output as an input to the

DVB-SH, that is, as an input of the IP encapsulator.

In this case, the Eureka-147 transmission part in the

T-DMB system is replaced with the DVB-SH

architecture. Therefore, modularization of the

common hardware block is possible between the T-

DMB and DVB-SH systems.

Another method to provide T-DMB contents is

input the MPEG-4 sync layer (SL) encapsulated data

of DMB processor, designated by encoded data in

Figure 1, to the input of the IP encapsulator. In this

ON THE DVB-SH SYSTEM ARCHITECTURE

167

case any block in T-DMB is not common in the

DVB-SH system. However, total hardware

complexity of DVB-SH architecture is decreased

compared to the former method. In Figure 4, the two

proposed architectures are represented.

3 CONCLUSIONS

In this paper we have investigated the strategy for

constructing the DVB-SH system architecture to

provide T-DMB contents broadcasting

simultaneously or similarly via DVB-SH network.

We have presented two architectures for DVB-SH

system. By using the proposed architectures, the

modification from the standard DVB-SH system will

be minimized.

REFERENCES

ETSI EN 102 585, Feb. 2007. System Specification for

Satellite services to Handheld devices (SH) below 3

GHz.

ETSI EN 302 583, Feb. 2007. Digital Video Broadcasting

(DVB); Framing structure, channel coding and

modulation for satellite transmission to handheld

(DVB-SH).

Lee, G., et al., Feb. 2005. Development of terrestrial DMB

transmission system based on Eureka-147 DAB

system. In IEEE Trans. on Consumer Electronics, Vol.

51, No. 1, pp. 63 - 68.

ETSI EN 300 744, Jan. 2001. Digital Video Broadcasting

(DVB); Framing Structure, Channel Coding and

Modulation for Digital Terrestrial Television.

Balaguer, E. de Diego, et al., 2005. Performance

Evaluation of Power Saving Strategies for DVB-H

Services using Adaptive MPE-FEC Decoding. In Proc.

of The 16th International Symposium on Personal,

Indoor and Mobile Radio Communication, PIMRC'05,

pp. 2221-2226.

Figure 3: Architectures of the DVB-SH systems.

DVB-SH IP

encapsulator

OFDM DVB-SH

modulator

TDM DVB-SH

modulator

Convolutional

interleaver

encoder

MPEG-2 TS

m u ltiplexe r

Encoded

data

T-DM B processor

MPEG-2 TS

DVB-SH IP

encapsulator

OFDM DVB-SH

modulator

TDM DVB-SH

modulator

Encoded

T-DMB data

(a)

(b)

Figure 4: Two architectures of the DVB-SH systems incorporating T-DMB contents.

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