Hyung-Yoon Seo

Delays and Resource Analysis for Next-Generation Digital Broadcasting Systems

This paper analyzes delays and resource efficiency when DASH segment files are transmitted through IP-based next-generation broadcasting systems such as ATSC 3.0. DASH segment files are designed to support media content of various qualities in the DASH system. The size of a DASH segment file can vary even though they may have the same quality and playback time. As the quantity of media content such as UHD (4k, 8k) increases in the next-generation broadcasting system, so does the variability of the segment file size. The resources available to broadcasters have increased with technology development however these are still limited and fixed. Accordingly, transferring segment files with large variability has resulted in problems of delays and with resource efficiency. This paper proposes a virtual structure to analyze delays and resource efficiency during DASH segment file transfer, and shows the simulation result by modeling the virtual structure.

A Study of Transmission Structure for IP-based Digital Broadcast Systems

IP-based, next generation digital broadcast systems transmit DASH segment files. Designed by the DASH system, DASH segment files provide variable quality of contents, while the size of DASH segment files varies even if the file has the same quality. Delays and inefficient use of resources are major challenges in the transmission of variable size DASH segment files in broadcasting systems. Traditional broadcasting transmission systems are designed according to characteristics of physical layer of broadcast, and thus, delay and inefficient resources use is difficult to find. Yet, transmission content quantities continue to rise in the next-generation broadcasting systems (e.g. FHD, UHD (4k, 8k)) with variability of the segments file size as well. Resources for next-generation broadcast are more abundant than traditional broadcast with recent development, but continue to be limited and fixed. Resource delay and inefficiency are important but has not been extensively studied. We propose a transmission structure solution to analyze the delay and efficiency of the resource as each DASH segment file is transmitted, and have further performed simulation studies.

IP based convergence service for Terrestrial DMB

As several current and emerging Mobile TV systems are made to transparently and efficiently integrate with IP starting from the design phase, Terrestrial Digital Multimedia Broadcast (T-DMB), or DMB also is required to evolve as the IP based service. In the paper, we propose the IP based convergence service for DMB, and the IP based DMB gateway and agents for achieving easy and transparent integration of DMB and IP. And also, we verify the feasibility and benefits of our proposals by implementing some example services.

CLOF: Contribution-level-based opportunistic flooding for multihop wireless networks

In this study, we propose a contribution-level-based opportunistic flooding for multihop wireless networks. Traditional flooding techniques typically use fixed routing and predetermined relay nodes based on the assumption of fixed and reliable links. However, because of the inherent instability of wireless links, these approaches typically lead to fragile and unreliable broadcasting. To overcome this problem, we adopt an opportunistic routing where the relay node is determined by the transmission result. In addition, we introduce a new criterion: a contribution level defined as packet infectiousness, and it represents the transmission priority. Namely, contribution level implies the degree of contagiosity determined by the distribution of uninfected entities. It also falls with an increase in the number of infected entities. Thus, the contribution level of a node is initially determined by the number of neighbors and distances to the neighbors. Once a node receives a packet, it waits a certain amount of time according to the initial priority. The node changes its own contribution level when it overhears a packet while waiting. If the contribution level reaches near zero, it discards the received packet such that unnecessary duplicates are removed. Consequently, higher reliability and efficiency can be achieved.

S-DASH: A new transmission mechanism for IP-based digital broadcasting systems

ATSC 3.0 is a next-generation terrestrial broadcast standard that transmits UHD media content by DASH segment file, not media frame unit. The size of DASH segment files varies even though they have the same quality and playback time. In other words, the sizes of DASH segment files basically burst. Moreover, a DASH segment file size burst more due to the amount of UHD media, which is larger than HD media. However, the bandwidth of broadcast system is limited and transmits media as CBR. Therefore, there are problems of delays and resource efficiency when the segment files with large variability are transmitted through the terrestrial broadcasting. In order to reduce delays, this paper proposes Server DASH (S-DASH). S-DASH selects and transmits the proper quality of a DASH segment file among the various qualities of DASH dataset by a broadcast server. Simulation results show that S-DASH can reduce delays.

Transmission model for next-generation digital broadcasting systems

Next-generation digital broadcasting system transmits the DASH segment files. Delays and inefficient use of resources are the major challenges in the transmission of DASH segment files in broadcasting systems. Because the size of DASH segment files varies even though the files have the same quality, and broadcasting systems uses the fixed resource. Delay is an important problem in broadcasting systems because these are real-time systems. Therefore, next-generation digital broadcasting systems should minimize delays and use resource efficiently. This paper proposes a transmission model that can analyze delays as well as efficient use of resources.

A Transmission Method to Improve the Quality of Multimedia in Hybrid Broadcast/Mobile Networks

This paper proposes the method through the mobile communication network when broadcast contents occur receiving errors in the Hybrid Broadcast/Mobile Network. Generally, the characteristic of the mobile communication network is pay network and peer-to-peer mobile. Therefore, it is necessary to reduce the amount of retransmission data in order to reduce the load of users and networks for recovery. This paper proposes the method to recovery for Hybrid DMB System which combines the T-DMB of the major mobile TV standard with the mobile communication network. The proposed method utilizes the Reed-Solomon techniques based on cross-layer. The proposed method transmits the additional information for recovery when errors are detected. It can reduce by % the resource compared with the retransmission of the original MPEG2-TS.

Unequal Loss Protection Mechanism for Wi-Fi based Broadcasting system using a Video Quality Prediction Model

The Wi-Fi based broadcasting system is mobile Internet Protocol Television (IPTV) technology, which transmits the multimedia content to a lot of local mobile users in real time. Unlike conventional Wi-Fi based multimedia streaming systems that use a separate unicast packets to serve each user, the Wi-Fi broadcast system uses the broadcast packets for scalability because one broadcast packet can serve many users simultaneously. However, it must use the FEC technology to recover the broadcast packet loss because an IEEE 802.11 does not support the packet loss recovery method for the broadcast packet. Considering the feature of multimedia data, equally adding FEC packet to video source is not efficient. For better efficiency Unequal Loss Protection (ULP) technology, for example, has been developed. This paper is going to modelling the characteristics of quality deterioration from effect of broadcasting packet losses in Wi-Fi based broadcasting system and suggest newly developed ULP system based on the model of quality deterioration. The system will be implemented and experimented to demonstrate its superiority.

An Efficient Hierarchical Error Recovery Method for Hybrid Broadcast/Communication Networks

ABSTRACT This paper proposes a hierarchical error recovery method for the hybrid mobile broadcast/communication networks. The mobile broadcast network (e.g., DVB-T/H, T-DMB) transmits the base forward error correction (FEC) and the multimedia content at the same time for the error recovery. However, the occurrence of errors is different due to the receiving environment of the individual mobile broadcast network, and not all the base FECs can recover errors. The server retransmits the enhanced-FEC (E-FEC) to a terminal through the individual mobile communication network and a terminal can try to recover the packet with errors which the base FEC cannot recover. If there are more retransmitted source data to a user, the overhead of a user and the communication network will increase because the individual mobile communication is a subscription-based network. Therefore, this paper proposes a hierarchical error recovery method, and the E-FEC with higher channel coding rate than base FEC is generated and transmitted. The proposed method in this paper transmits only the redundancy data for the error recovery when errors occur, and reduces the resource by 50%–80% compared with the retransmission of the source. If the source bit rate is 800 kbps, for instance, the packet error ratio is 10%, and if a user watches a broadcast content for one hour, the amount of retransmitted data is 80 kbps × 3600 = 36 MBytes, but that of the proposed method in this paper is 7.2–18 MBytes.

Design and Implementation of Multi-Rate Broadcast Based Link Quality Measurement for Wireless Mesh Network

capture link quality more accurately than the existing techniques.