Advanced digital broadcasting services · channels, such as broadcast and communication networks. Components can be reliably delivered with a fixed delay on broadcast channels, but

By the end of FY2011, the switch-over to digi-tal broadcasting had been completed in Japan, in-cluding the three prefectures hit by the Great East Japan Earthquake. Digital television continues to spread, and Internet usage is also growing quickly. There is a demand for new broadcast services us-ing the digital infrastructure both for viewers and for revitalizing industry. Accordingly, STRL is con-tinuing its research and development on advanced and user-friendly digital broadcasting technology.

In FY2010, STRL proposed the Hybridcast sys-tem, a platform for increasing the convenience and sophistication of broadcast programs by utilizing the complementary characteristics of broadcasting and communications. In FY2011, we implemented functionalities including precise syn-chronization, sophisticated linkage with mobile terminals and with social services, and security functions, and we developed prototype receivers with manufacturers. We studied possible services with the functionalities. In addition, we actively promoted the system at the STRL Open House, and we gave demonstrations and presentations in Japan and internationally. We also published over-views of technical specifications in conjunction with the STRL Open House, and we are at present studying the detailed specifications and contribut-ing to standardization efforts.

In anticipating the age of integrated broadcast-ing and communications, i.e., the all-IP era, we are developing the ATS scheme, which is a new multiplexing method to replace the current MPEG-2 Systems, and we are working toward standard-ization with the MPEG MMT.

We have gained new insights regarding the ef-fectiveness of the “teleda” social television system and the behavior of viewers in field trials. We are extending the system’s functionality by making it able to link with external SNSs and testing its ef-fectiveness in field trials. We have also begun re-search and development on a "senior's cloud" to promote use of this service platform by the elderly.

We are making progress on virtualization of video content production, which is promising

for Consumer Generated Media (CGM), by using TVML technology to enable computer graphics (CG) to be generated easily from various termi-nals over the Internet. This year, we prototyped a viewer-participation program called the Connect-ed Studio, and demonstrated the effectiveness of the system.

To simplify the operations of using the Inter-net services, we made progress in developing ID management and authentication technologies for linked services. We also developed an application authentication scheme using a key-insulated sig-nature method and studied how this scheme can be applied to services linking broadcasting and communications. We also worked on a down-loadable CAS scheme, incorporating the current B-CAS format, by which the digital receiver CAS function can be updated by downloading from a broadcast and verified its effectiveness.

Distributing live streaming video content related to a broadcast program over the Internet causes network congestion, so an efficient transmission scheme is required. We focused on peer-to-peer (P2P) technology for this purpose. We also dem-onstrated an effective scheme for distributing live video of the qualifying rounds of Kosen Robocon, the national technical college robotics contest.

We have been studying the technical require-ments for service-area limited broadcasting sys-tems, using the white spaces in the UHF televi-sion broadcasting bands. As a trial application of service-area-limited One-Seg broadcasting, we conducted experiments to provide essential infor-mation in disaster stricken areas in collaboration with the Engineering Administration Department. We also made progress on Mobile Multimedia Broadcasting (MMB) on VHF band channels 1 to 3, previously used for analog television broadcast-ing, studied transmission technology to expand the mobile reception area, evaluated the reception performance of storage-based broadcasting, and made mock-up receivers for studying services to make society safer and more secure.

2.1 Technologies for fusing broadcasting and communications

2.1.1 Hybridcast®

We have progressed with our research on Hybridcast®, which makes possible new services that meet the needs of viewers by combining broadcasting and communications.

■ Hybridcast platformHybridcast makes broadcasting more advanced, flexible and

extensible by taking advantage of the complementary charac-teristics of broadcasting and communications. The NHK three-year administrative plan beginning in FY2012 sets a priority target of developing new services suited to the era of integrated broadcasting and communications (Figure 1). In line with this plan, we aim to make Hybridcast a reality within two years.

At the STRL Open House, we introduced prototype television

Hybridcast® and its logotype are registered trademarks of the NHK Engineering Service Inc.

16　｜　NHK STRL ANNUAL REPORT 2011　

2 Advanced digital broadcasting services

and set-top-box (STB) receivers developed by television manu-facturers and a STB with highly accurate synchronization tech-nology to present multi-view or stereo 3D television. Various services for prototype mobile devices that communicate with TVs were also introduced. These efforts demonstrated that it will be possible to provide such Hybridcast services very soon (Figure 2). We also exhibited a screen display control technolo-gy that can reliably give priority to emergency information from broadcasts such as earthquake early warnings.

We widely promoted the possibilities of these services, do-mestically and internationally by exhibiting Hybridcast and making presentations at CEATEC2011, IMC2011, IBC2011, and others. In particular, our Hybridcast presentation won the Best Paper Award at NAB2011(1).

We continued work on prototype test receivers in coopera-tion with television manufacturers toward the early launch of Hybridcast.

We published technical descriptions summarizing the over-all architecture, service models, and technical requirements of Hybridcast at the time of the Open House. After that, we con-tinued to study the detailed specifications. Since these speci-fications are for a browser-based system, NHK is participat-ing in W3C, which is a community standardizing web-related

technologies including HTML5. In particular, NHK proposed a set of requirements for services combining broadcasting with communications which should be satisfied by a browser in a TV and HTML5 language. We are also participating in the HTML5 working group at the IPTV Forum, which is developing technical specifications for combining broadcasting and com-munications in Japan.

In the future, we will complete these specifications by test-ing prototype receivers equipped with HTML5 browsers devel-oped by television manufacturers and conduct field trials using these receivers. Part of this research was conducted in coop-eration with Sony Corporation and NTT Corporation.

■ Security for receivers combining broadcasting and communications functionsWe are researching and developing security technology

for Hybridcast, to provide services that link broadcasting and communications safely and securely. In FY2011, we developed control schemes for presenting communications applications on television screens and for accessing broadcast resources and receiver functions.

Hybridcast enables new services that cannot be realized with

Broadcasting station

Network

Supplementary content for broadcast programs

On-demand programs Program

recommendations

Social networks

Make broadcasts more interesting and more understandable broadcasts by the addition of content from communications network

View programs more conveniently by linking TVs with PCs or mobile terminals

Use social/personal services, only possible with communications, linked to broadcasts

Provide information linked to the broadcast

View program information and control the TV on a second screen

Figure 1. Hybridcast overview

Figure 2. Hybridcast prototype receivers exhibited at the STRL Open House

NHK STRL ANNUAL REPORT 2011　｜　17

2 Advanced digital broadcasting services　｜　2.1　Technologies for fusing broadcasting and communications

broadcasting alone and that are to be implemented through use of communications applications; a problem is that there is a possibility that important information about the broad-cast content could be obscured by these applications. Thus, it is important to have a mechanism that ensures that priority information is conveyed while also considering the needs of viewers. Accordingly, we developed a screen display control scheme(2) for when broadcast content and communication ap-plications are combined on the screen. It sends a presentation policy reflecting the broadcaster's intentions to the receiver so that important information such as Earthquake Early Warn-ings can be given higher display priority (Figure 3). Tests of Hybridcast prototype receivers confirmed that this scheme is effective and that receivers so equipped can quickly and ap-propriately control the display of applications according to the broadcast information such as Earthquake Early Warnings.

Hybridcast assumes that receivers will provide a specialized application programming interface (API) that will allow com-munications applications to use receiver functions and broad-cast resources. The API will allow applications to easily refer-ence and control receiver functions and broadcast resources such as channel tuning, program specific information and ser-vice information (PSI/SI). However, allowing all communica-tions applications to use these APIs unconditionally presents security risks, so we have developed a scheme for API access

control to be used in Hybridcast receivers, to protect viewer information and broadcast content according to application authentication and the viewer’s intentions.

■ Multiplexing schemes for hybrid deliveryHybridcast realizes varied and versatile services by com-

bining video, audio, and data components on various delivery channels, such as broadcast and communication networks. Components can be reliably delivered with a fixed delay on broadcast channels, but there is a delay variation on com-munication networks and a portion of components sent may be lost. This means the multiplexing technology must reliably transport these components on the various delivery channels with the appropriate timing.

To achieve this, we are developing an advanced multiplex-ing scheme based on MPEG-2 Transport Stream (TS), which combines components on the current digital broadcast system with components on Internet Protocol (IP) based communi-cation networks. We are also developing an IP-based multi-plexing scheme for when broadcasting and communications become based on IP in the future.

With the MPEG-2 TS based multiplexing scheme, both com-ponents from broadcast channel and communication net-works are synchronized with the system-clock delivered on

Station A

Station B

Video, audio

Broadcast medium A

System clock A

Video, audio, system clock A

Communication networkCaptions, system clock A

Synthesize captions using time adjustment data

and system clock BSystem clock B

Communication

network

Receiver

Receiver

Synthesize captionsusing system clock A

Broadcast medium B

Video, audio, system clock B

Time adjustment data

Video, audioafter conversion

Clock conversion

Additional component (captions)

Figure 4. Synchronization using time adjustment data

Normally, applications are displayedat the same time as the broadcast content

When receiving an Earthquake Early Warning, applications are not displayed

Hybridcastprototype receiver

Earthquake Early Warning

Broadcaster

Earthquake Early Warning

Communications application

Figure 3. Screen presentation control



the broadcast channel. However, when a broadcast station (Station B in Figure 4) receiving a TV program from the origi-nal broadcast station (Station A in Figure 4) and retransmits it, the system-clocks on the both stations are not the same. In this case, because of the difference in the system clocks, a receiver receiving the components from Station B cannot syn-chronize components in the same way as a receiver receiving the components from Station A does. To deal with this prob-lem, we developed a system that calculates and corrects the difference between the system clocks. Our system enables ev-ery receiver to synchronize any set of components.

In the future, when broadcasting and communications are based on IP, much more flexible and integrated services will be possible. However, in the case of IP, neither transmission delay nor delivery quality is fixed, so reliability cannot be maintained by simply transmitting MPEG-2 TS in IP packets. Because of this, MPEG-2 TS has been extended many times in various ways. As a result of the extensions, MPEG-2 TS has become too complicated.

Recognizing the necessity of an IP-friendly media trans-port mechanism, we have developed the Advanced Transport Scheme (ATS), which is an IP-based multiplexing scheme on heterogeneous networks(3). We proposed it to MPEG as a can-didate technology for the next-generation MPEG Media Trans-port (MMT) and are actively promoting standardization of the scheme. MMT will be a system technology that will enable media transport over heterogeneous networks and will be a

system part of the new MPEG multimedia standard, MPEG-H.

■ Future directionsGoing forward, we will contribute to standardization of

technologies that integrate broadcasting and communica-tions in Japan, based on specifications proposed by NHK and through discussions with other broadcasters and manufactur-ers. We will work toward early field trials at events such as the London Olympics.

We will also pursue standardization of our new multiplexing scheme, using IP for both broadcasting and communications, at MPEG.

[References](1) A. Baba, K. Matsumura, S. Mitsuya, M. Takechi, Y. Kanatsugu, H.

Hamada and H. Katoh: “Advanced Hybrid Broadcast and Broadband System for Enhanced Broadcasting Services,” NAB Broadcast Engi-neering Conference, pp. 343-350 (2011)

(2) K. Otsuki, H. Ohmata, A. Fujii, K. Majima and T. Inoue: “A Presen-tation Control Method of Applications in Hybridcast,” ITE Annual Convention, 11-11 (2011) (in Japanese)

(3) S. Aoki, K. Aoki, H. Hamada, Y. Kanatsugu, M. Yamamoto and K. Aizawa: “A New Transport Scheme for Hybrid Delivery of Content over Broadcast and Broadband,” IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, mm11-11 (2011)

2.1.2 SNS, CGM

We are assessing a social networking service (SNS) about broadcasting and consumer generated media (CGM) that helps viewers in publishing their own video content.

■ Social television systemTo increase the proportion of people viewing television con-

tent through the Internet, we have made progress on the teleda social television system, which encourages viewers to com-municate with each other through television programs. The teleda system combines a program-video distribution service and a social networking service, and it uses television pro-grams and viewers’ reviews as a vehicle for creative encoun-ters. It has various functions for a social television system,

such as analysis of viewer tendencies and video processing functions(1) (Figure 1).

The teleda platform has been in development since FY2009. In FY2011, we introduced functions to enliven communication and encourage interaction with programs. For example, users can now communicate with other users through external SNS such as Twitter and Facebook, as well as within teleda. Com-ments entered on teleda can also appear on the other SNSs. This overcomes the limits of individual SNSs and expands the connections between people. We have also developed ways of inferring user preferences from their viewing history, op-eration history, and comments they have entered on external SNSs. A television program recommendation service and a user recommendation service generate are customized with the users’ preferences. We have also created a space for view-ers to share their thoughts in real time, not only on programs currently being broadcast, but also past broadcasts. We envi-sion people using this space to be similar to a family talking and watching a program together in their living room.

We held a field trial with a teleda test system incorporating these new functions for three months, from mid-December to mid-March, with on the order of 1000 users, to analyze viewer behavior and test functionality. The trial confirmed that teleda is effective as a service, forming communities through TV pro-grams and promoting a variety of interactions with them. We plan to analyze the results in detail in the next fiscal year.

From the results of testing in FY2010, we found that the younger and senior generations extensively engage these kinds of communication service. In FY2011, we began research and development on ways of encouraging seniors to communicate using teleda. This research has two aims: gather knowledge and experience, and support meaningful engagements. With this in mind, we conducted various experiments to explore the possibilities of teleda in FY2011. We conducted experiments on formation of communities around the common focus of TV programs; i.e., we tried to determine whether TV programs can provide a good start for communication. We found that wide range of associations and remembrances stimulate con-versation in a community. The associations and remembranc-es were often inspired by the extra-linguistic information of TV

Figure 1. teleda test site



programs. We also conducted experiments on three styles of communication: face-to-face, video phone, and teleda, and we found that a benefit of teleda is that users can control their own pace of communication. On the other hand, most users said they feel uncomfortable conversing with strangers.

To gather knowledge and experience from teleda comments, we selected activity logs from senior teleda users of 65 or older and analyzed trends in their access, program viewing, com-ments, and other factors. We found that there is a strong desire among seniors to use IT systems and that we may be able to draw out more of their knowledge and experience by providing a more suitable program lineup for them(2). We also found that the amount of knowledge and experience gained from users varies greatly depending on the content of the program.

■ Virtualization of video content productionWe have begun research toward virtualization of video con-

tent production based on server-side video production, to en-able production of simple video content without depending on the performance of the user's terminal or what software is installed.

In FY2011, we added several functions to the cloud-based video production system developed in the previous year, ex-panded the user base, and built a system that allows ordinary viewers to participate in program production over the network. The system, called Connected Studio(3), allows viewers to par-ticipate in programs as CG characters. We developed a quiz show program and a public viewing program, which were ex-hibited together with the system at the STRL Open House. The Connected Studio terminal (Figure 2) allows users to view the broadcast video, give instructions for actions of their CG char-acters (the performers), enter comments, and generate their individual videos from their preferred viewpoints. We have also reduced the delay for generating video at the server, stud-ied how to write scripts to control the timing of video genera-tion, and implemented sign-language animations on mobile

terminals.TVML (TV program Making Language) related technology,

Adlib System, was used for programs and events. TVML was also used in many regional station open house events with the newly developed exhibition systems, Four-frame Televi-sion, and Voice Play! Silhouette Quiz. It was also linked with a simple motion capture system and used at the Akita station open house.

[References](1) M. Miyazaki, N. Hamaguchi and H. Fujisawa: “User Behavior in the

`teleda’ Social TV Service - Achieving a Public Forum on the Net-work -,” Proceedings of the IEEE International Symposium on Mul-timedia, pp. 345-350 (2011)

(2) M. Miyazaki, H. Fujisawa and M.Sano: “A Study on Activity of Senior in TV Social site,” FIT2011, D-002 (2011) (in Japanese)

(3) M. Doke, H. Kaneko, N. Hamaguchi and S. Inoue: “Connected Stu-dio - Massively Multiplayer Virtual Appearances Service-,” FIT2011, K-070 (2011) (in Japanese)

2.1.3 Security platform

We are developing security technologies to protect rights related to broadcast content, to make service federation be-tween broadcasting and various communications services easier, and to provide safe and secure broadcast and commu-nications services.

■ ID management and authentication data sharing schemes for service federationHybridcast receivers are both broadcast receivers and com-

munication devices, and because of this, Hybridcast viewers can receive services finely tuned to their individual needs and interests. Hybridcast also makes possible a variety of new ser-vices, such as social network-linked broadcasting, and VOD. With the aim of making such services safe and secure, we are researching account management on receivers. In FY2010, we developed a prototype multi-account receiver which can provide different users with individualized services. This year, we extended its functionality and developed a device-linking system that passes authentication information between the re-ceiver and an individual user's mobile device(1) (Figure 1).

We clarified the requirements for safely linking user attribute data between services and tested the linkage in a field trial of the teleda social television service. We also clarified require-ments for authorizing external services, based on agreement from the user, so that user attribute data held by broadcasters and related to programs can be used safely. For administer-ing an authorization protocol with good Web compatibility, we developed a prototype authorization server, studied specifica-tions of a safe mash-up scheme between a VOD service that

uses the authorization functions and external services, and developed a prototype system.

■ Advanced conditional access systemWe developed a downloadable Conditional Access System

(CAS) whose functions will be implemented within the system LSIs of receivers. This CAS can perform secure access control and copyright protection, and it has security functions such as key data processing and encryption algorithms that can be updated through broadcasting or communications functions(2).

We developed an FPGA receiver incorporating this down-loadable CAS technology to prove that it can be used with cur-rent broadcasting systems and exhibited it at the STRL Open House (Figure 2). To implement downloadable CAS technol-ogy that does not depend on the system LSI hardware specifi-cations, we developed a mechanism for describing CAS func-tions in software using an intermediate language and running it within the system LSI. We studied its operation by using the prototype equipment.

■ Encryption and authenticationWe made progress on encryption and authentication tech-

nology for providing secure and reliable hybrid broadcasting and communications services such as Hybridcast(3).

We have been researching a broadcast encryption scheme for protecting content distributed through communications networks. In FY2011, we clarified the issues for applying a broadcast encryption scheme to an application launched when

Broadcast video

Individualvideos

Cameraoperations

Performeractions

Comment input

Figure 2. Connected Studio screen



a broadcast program starts. We developed a smart-phone ap-plication for the teleda social television system with a provider authentication function to ensure the reliability of submitted reviews and comments on a program. We also confirmed that it can perform authentication quickly. This application was ex-hibited at the STRL Open House (Figure 3).

[References](1) C. Yamamura, K. Otsuki, A. Fujii and K. Ishikawa: “Identity Man-

agement Architecture for Integrated Personalized Service on TV,” IEEE International Conference on Internet Technology and Secured Transactions, TD-04.7 (2011)

(2) H. Kawakita, Y. Nishimoto, Y. Endo and T. Inoue: “A Downloadable Conditional Access System for Broadcasting,” ITE Technical Report, Vol. 36, No. 6, BCT2012-26, pp. 59-62 (2012) (in Japanese)

(3) G. Ohtake and K. Ogawa: “Application authentication for hy-brid services of broadcasting and communications networks,” Proceedings of The 12th International Workshop on Infor-mation Security Applications, LNCS 7115, pp. 171-186 (2011)

Household user

Householdrelated information




Individualrelated information









Cloud

Network

Receiver

Individual user

Service Provider Afor Household

Service Provider Bfor Household

Service Provider Afor Household

Service Provider Bfor Individual

Application Application Application Application

Group viewing

Distinguish conditions

Individual user

Log

in

Figure 1. Multi-account receiver operation overview

Broadcast receiverDownloadable CAS board

Figure 2. Receiver with downloadable CAS

Figure 3. Screen of a smart-phone application with a provider authentica-tion function



2.1.4　IP content delivery technology

We are researching content delivery over IP, with the goal being low-cost implementation of large-scale, stable content distribution over communication networks.

■ IP content delivery platformWe are continuing with research and development on a live

content streaming system using peer-to-peer (P2P) technol-ogy, which can stream video inexpensively over the Internet on a large scale.

P2P technology enables efficient data distribution by having users’ PCs automatically relay data they receive to other us-ers’ PCs. However, P2P systems have issues with stability and availability because the terminals belonging to users may be-come disconnected from the network.

In FY2011, we evaluated the stability of connection and dis-connection algorithms in such relay terminals in order to draw up guidelines for a stable live stream distribution system. We also developed a high-availability scheme that enables termi-nals to receive seamless services by receiving only still images with sound whenever the status of the connection deteriorates.

To make distribution equipment scalable to the amount of content, we developed an efficient scheme to adjust the scale

of the delivery servers dynamically in accordance with the amount of traffic by linking them with external cloud services.

We developed a live P2P content streaming system combin-ing these two schemes, and with the cooperation of NHK’s Program Production, Programming, and Broadcast Engineer-ing Departments, we held field trials in October, streaming live content from the regional qualifier events of Kosen Robocon, the national technical college robotics contest(1). These trials used a commercial cloud server, a patching server to provide data when other terminals were interrupted, and a P2P distri-bution server (Figure 1). For terminals that cannot use P2P be-cause of their configuration or network environment, we cre-ated a functionality for automatically using a content delivery network (CDN) with uni-cast delivery.

There were a total of over 16,369 accesses during the field trial, and through use of P2P at all venues, the distribution server load was reduced by more than 80%. The field trial con-firmed that the P2P live streaming system is feasible.

[References](1) S. Nishimura, K. Ishikawa and M. Yamamoto: “Content Distribution

Trial of Kosen Robocon on P2P Network,” ITE Winter Annual Con-vention, 3-2 (2011) (in Japanese)

2.2　Enhanced ISDB-T

■ Study of UHF television broadcasting band usage

In FY2011, we participated in a working group of the Infor-mation and Communications Council studying the feasibility of broadcast systems using white spaces in the UHF television broadcasting band. In particular, as a possible use of these white spaces, we studied the technical requirements for a ser-vice-area-limited broadcasting system using a transmission system similar to digital terrestrial television broadcasting system. We devised a new approach to determining interfer-ence-to-noise ratio (I/N) criteria for protecting digital terres-

trial television broadcasting from interference from service-area-limited broadcasting, whereby I/N must be -10 dB or less.

We developed software for simulating the interference from service-area-limited broadcasting on digital terrestrial televi-sion broadcasting and did a study on the number of service-area-limited broadcasting stations that could be used under different output conditions while meeting the interference pro-tection criteria described above.

To confirm that the protection criteria can be satisfied, the signal strength must be measured in an additive white Gauss-ian noise environment. Therefore we studied a methodology

Encoder PC

Event venue Service operation and managementCommercial cloud server

P2P terminal group(groups of 300 machines)

Control PCClient

registration server

Patching server P2P video distribution server

CDN(uni-cast distribution)

Figure 1. P2P live streaming system overview



of extremely low level signal measurement(1). We prototyped low-electric-field measurement equipment for ISDB-T signals and conducted laboratory and field tests to verify its effective-ness (Figure 1).

In September, we established a test station for service-area-limited broadcasting in the ISDB-T format at the Nabeta radio station in Aichi Prefecture. In particular we tested service-area-limited One-Seg broadcasting in disaster-hit areas con-forming to the white space zone model selected by the “Vi-sion for Uses of Radio Waves” Study Team of the Ministry of Internal Affairs and Communications. The basic transmission tests revealed the effects of the service-area-limited system on digital terrestrial broadcasting, and we developed a disaster information collection and transmission system.

■ VHF-Low band mobile multimedia broadcastingWe are advancing research toward deployment of mobile

multimedia broadcasting for handheld terminals using VHF TV band channels 1 to 3 (in the VHF-Low band). These chan-nels were reallocated after the end of analog television broad-casting. In FY2011, we developed prototype receiver equipment supporting the services of the VHF-Low band mobile multi-media broadcasting and studied transmission and reception technologies for expanding the mobile reception area. We also evaluated reception performance in relation to storage-based broadcasting and made detailed mock-up receivers for study-ing services to make society safer and more secure.

In our studies on transmission and reception technology for expanding the mobile reception area, we developed VHF-band test receivers with functions to support long time-interleav-ing lengths(2), iterative error correction decoding using Viterbi and Reed-Solomon decoder, and two-branch space diversity. We conducted field tests using the STRL VHF-Low band ex-perimental transmission station to verify the effects of each

function. We also established a VHF-Low-band experimental transmission station at the Odawara FM transmitter station site with the same transmitter power as the FM station, 100 W, and completed preparations for tests comparing it with the FM station.

To evaluate the reception performance for storage-based broadcasting, we conducted laboratory tests that yielded a range of transmission parameters to offer efficient storage broadcasting service in mobile reception environments(3). For mobile multimedia broadcasting in the VHF-Low band, con-tent is partitioned into download data blocks (DDB) for trans-mission and storage and these blocks are broadcasted using a data carousel transmission method. Thus, for each anticipated size of storable content, we calculated the relationship be-tween DDB size and storage success rate and determined the DDB size at which the content can be transmitted and stored efficiently.

We manufactured a receiver very similar to our concept for safety and security (Figure 2) that could receive both disaster information radio and One-Seg. We also studied services such as automatic launches triggered by earthquake early warnings.

[References](1) M. Okano, M. Nakamura, H. Sanei, S. Nakahara and M. Takada: “A

Study of ISDB-T Spectrum Detection Method Based on Periodicity of Scattered Pilot,” ITE Technical Report, Vol. 35, No. 41, BCT2011-76, pp. 45-48 (2011) (in Japanese)

(2) M. Nakamura, M. Okano, H. Sanei, S. Nakahara and M. Takada, “Time Interleaving Effect on the Mobile Reception for Mobile Mul-timedia Broadcasting in the VHF-Low Band,” ITE Technical Report, Vol. 35, No. 41, BCT2011-66, pp. 1-4 (2011) (in Japanese)

(3) H. Sanei, M. Nakamura, M. Okano, S. Nakahara and M. Takada: “A Study of Relationship Between File Size and the Successful Re-ceiving Probability of the File-casting Content Using Data Carou-sel Transmission Method in the V-Low Mobile Multimedia Broad-casting,” ITE Technical Report, Vol. 35, No. 41, BCT2011-67, pp. 5-8 (2011) (in Japanese)

Figure 1. Low-electric-field experimental measurement equipment

Figure 2. Prototype receiver for study of services (mock-up)


2 Advanced digital broadcasting services　｜　2.2　Enhanced ISDB-T

Documents

Advanced digital broadcasting services · channels, such as broadcast and communication networks. Components can be reliably delivered with a fixed delay on broadcast channels, but