Keio University, Graduate School of Media and Governance
MAUI Project
Ph.D. Dissertation

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TITLE IP Network Architecture Over Uni-directional Broadcast Media

This dissertation discusses a network architecture to utilize uni-directional broadcast media in the Internet. On the network architecture, this dissertation proposes to operate the uni-directional broadcast media as Bi-directional Broadcast-capable Multiple Access (B-BMA), which is transparent to data link layer in the Internet. Contributions of this dissertation are the deployment of IP networking over uni-directional broadcast media, that accelerates the convergence of communication and broadcasting: large-scale multicast in the Internet, IP-based end-to-end services to broadcasting subscribers, and an alternative IP network connectivity that can be selected as one of generic paths in the Internet.

Uni-directional link (UDL) is a network topology where one-way transmission is enabled from a transmitter to one or more receivers. Effective bandwidth utilization and scalability are vital issues on IP networking over a large-scale UDL. To cover an extraordinary number of receivers that communicate using Link-layer Tunneling Mechanism (LLTM), we propose to (1) decrease the traffic load of LLTM at the upstream of UDL, (2) coordinate data link layer and network layer of Receivers without communications via UDL, and (3) enable neighbor discovery for direct communication between Receivers via BDL. These approaches are achieved by accumulating receivers' state at the upstream of UDL. Simulation results showed that our approach reduces by more than 90% of control messages to be sent via UDL compared with IPv6 address auto-configuration on the existing network architecture. Our proposal improves the order of UDL bandwidth consumption from O(N) to O(1), so that the bulk of bandwidth can be utilized for delivering services, not for network configuration of Receivers. Also, communication path between receivers can be optimized based on good path selection that is aware of both UDL and BDL.

Communication infrastructure that can involve a wide-area broadcast media is highly potential for future IP services beyond the existing broadcasting services like TV or Radio programs. However, the considerable experience of operating the broadcast systems as transparent data links for the Internet has not been accumulated yet. This dissertation implements a prototype of IP over ISDB-TSB system that can be operated under the current operational guideline in Japan. We propose to use LLTM to emulate B-BMA in the data link layer, and IPv6 for the network layer protocol. Also, to enable IP transmission over the ISDB-TSB system, we introduce IP Encapsulator (IPE) that bridges Ethernet LAN and MPEG-2 TS. The prototype was tested using the broadcast transmitter of Tokyo Tower, and IPv6 communications where successfully enabled using unicast and multicast.

In terms of operational engineering, a lot of efforts have been made to make IP networks using UDL sustainable. This dissertation proposes the operational approaches that are based on efficient utilization of bandwidth, scalability, and routing strategy in the scenario that both UDL and BDL are available. Our proposal includes using UDLs to reduce costs, IP multicast to leverage the broadcast nature of satellite links, QoS, audio-video application gateway to adapt to the limited bandwidth of UDLs. These proposals are implemented in an operational satellite-based IP network connecting 13 countries and supporting a distance learning project.

Considering the behavior of LLTM, the bandwidth limitation of UDL, and the its expected scale, we discuss a network architecture that can facilitate end-to-end Internet transparency for IP network using UBM. This dissertation research provides the network architecture proposed in this dissertation is expected to enable and sustain potential end-to-end information services that are creative and efficient by leveraging the nature of uni-directional broadcast media in the Internet.

Uni-directional Broadcast Media, Internet Transparency, Scalability, System Deployment, Operation

CONTACT To obtain the whole paper, please contact;
KATAOKA, Kotaro (kotaro at

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