On the convergence and applications of broadcast and broadband: system and network design perspectives

Abstract

and an altitude-dependent tradeoff between the shadowing possibility and source proximity. This part highlights the physics-related effects on moving network's coverage, and balances the movement of UAV to achieve power-efficient data transmission at the UAV transmitter. Furthermore, we propose a pilot-data power distribution optimization technique to ensure physical layer security in the protection area of small broadcast/broadband networks.

The media industry has recently focused on services that combine broadcasting and mobile communications to reduce network burden and maximize user experience. Unlike in the past, compatibility issues between terrestrial broadcasting and cellular telecom protocols have been resolved, leading to practical discussions on various forms of broadcast-broadband convergence. The new terrestrial broadcasting and broadband cellular standards, ATSC 3.0 and 5G, are both designed based on Internet Protocol (IP), making efficient interconnection possible. In addition, 5G aims to include all heterogeneous networks within the 5G platform by building various inter-network interfaces. Furthermore, 5G is showing movement towards standardizing multicast broadcast services (MBMS) within its own protocol, which is expected to accelerate broadcasting-broadband convergence in a broad sense.

This study proposes various implementation methods for the still-developing concept of broadcast-broadband convergence, often referred to as broadcasting-broadband interworking, and discusses practical use cases for each convergence solution. In part, a scalable video transmission system is proposed, which combines broadcasting and broadband networks at the transport layer and above. This system, the so-called cooperative casting system, is based on the handover and cooperation mechanisms between the two networks, coordinated by the central studio server and driven by terminal-side decisions. The presented cooperative casting system is a ready-developed solution that can be readily deployed in the real world. It is emphasized that the proposed cooperative casting is an effective solution to provide a seamless video experience in the mobile environment, e.g., infotainment in vehicles, which is foreseen to be essential in the upcoming era of autonomous vehicles. In parallel with the theoretical study in this dissertation, the working prototype of this cooperative casting platform has been actually implemented and demonstrated to the public. In this dissertation, the reliability gain of cooperative casting is analytically verified, specially for mobile video streaming scenarios. In parallel, a tower-overlay method of broadcast-broadband convergence transmission is introduced, in which convergence occurs at the physical layer. This part highlights that 5G and modern broadcasting systems have evolved to a similar architecture, i.e., the cloud radio access network (C-RAN) of 5G and the single frequency network (SFN) of the latest broadcast systems. From this point, this dissertation proposes a network form that overlays C-RAN and multimedia broadcast SFN (MBSFN) and combines the broadcast and unicast downlink transmissions by means of non-orthogonal multiplexing. Based on this system formulation, the precoding, fronthaul compression, and injection level are jointly optimized to maximize the sum throughput of unicast users while promising the quality of broadcast signals. In addition, we propose some new ideas of broadcasting-broadband convergence, the overlaid transmission of ATSC 3.0 and 5G Broadcast, and the retransmission of broadcast signals based on wireless caching in mobile networks. We also propose a wireless positioning system facilitated by the cooperative casting network, as an application beyond the communication domain. Considering viability and compatibility, all of the mentioned proposals are designed based on the latest existing standards.

Simultaneously, this dissertation also addresses the topics related to network formulations in the broadcast-broadband convergence era. Particularly, SFN and flexible small-scale network configurations are explored, which are the common direction of changes in broadcasting networks and mobile cellular networks, i.e., which the broadcast and broadband networks are converging into, in other words. The SFN and coordinated multipoint (CoMP) transmissions are discussed from the perspective of large-scale network. Accordingly, we investigate a channel model reflecting the practical propagation characteristics of SFN in urban areas for ease of network configuration and management. Specifically, an adaptive modification method is proposed to extend the existing SFN channel model to a parametric form reflecting the antenna characteristics at the receiver. On the other hand, one part of the presented research on flexible small-scale networks focuses on unmanned aerial vehicle (UAV)-based transmission systems. This part proposes an optimization algorithm to determine the velocity vector of the UAV transmitter to maximize the net throughput, while revealing that there are two distinct tradeoffs contributing to the network throughput: A speed-dependent tradeoff between inter-carrier interference and crowd chasing