Integrating packet‐level FEC with data carousels for reliable content delivery in satellite broadcast/multicast systems

Abstract

SUMMARYOne key aspect of digital multimedia broadcasting is the reliable point-to-multipoint distribution of content. Since the capacity and energy constraints in wireless environments do not favour the provision of a return channel for user feedback, the use of partial reliability techniques is often the only realistic option for the reliable transport layer design. In this paper, we focus on the two main reliable transport mechanisms in unidirectional, point-to-multipoint systems, namely packet-level forward error correction (FEC) and data carousels. We approach them as building components of an integrated scheme and investigate its performance via analytical means. Our analysis demonstrates that the network responsiveness, expressed by the average content access time, is optimized for certain packet-level FEC redundancy values. This is clearly different from setting FEC without considering the data carousel dimension, where the FEC redundancy is determined from the probability of recovering the whole file versus FEC overhead trade-off curves. We describe design alternatives for both scheme components, such as different FEC code types, rules for assigning FEC redundancy per carousel item, and ways to retrieve items from the data carousel, and evaluate their impact on the performance of the scheme. Our results suggest that the superposition of FEC on data carousels mitigates the otherwise significant impact of the data item retrieval technique on performance, at least for close-to-optimal FEC settings. On the contrary, the careful selection of FEC code and FEC redundancy assignment rule for data carousel items results in performance gains of up to 11 and 18% for the average content access time and FEC overhead, respectively, depending on the item demand and length distributions.

Cross‐layer protocol optimization for satellite communications networks: a survey

“…It is important to note that when lower layer and higher layer coding are employed a joint optimization (implicit cross-layer approach) has to be performed to maximize system efficiency. Chipeta et al [26] consider the same approach, for reliable point-to-multipoint distribution of contents in the digital multimedia broadcasting. Radio transmission errors due to the impairments of wireless links and intermittent connectivity during handoffs are the main reasons for data loss.…”

“…The adoption of such an approach is often the only realistic option for the design of a reliable transport layer, since the capacity and power constraints in wireless environments preclude the use or even the provision of a return channel for user feedback. In such a context we consider References [25,26] where reliable multicast and multimedia broadcasting are, respectively, addressed. Reference [25] proposes a cross-layer technique for geostationary-based systems where most of packet discarding at lower layers is removed and additional protocol header protection is introduced.…”

“…Low redundancy may result in high data download times, whereas increasing redundancy beyond the optimum value not only wastes the network capacity, but also increases the data download times. Reference [26] provides an analytical expression for the FEC redundancy levels that result in minimum average content download time.…”

Network coding and its applications to satellite systems

“…Standard approaches use scheduling mechanisms to provide reliability to these heterogeneous receivers [17], namely by using FEC techniques and data carousels. An essential service provided by some satellite systems is the broadcast transmission (e.g., video, TV, radio) to multiple, potentially heterogeneous, terminals.…”

Sustainable framework for a geostationary satellite control earth station system using parallel configuration

“…Malfunctions that cause system irregularities and failures are expected in the earth station system. A typical case of a failure that could be brought by distorted wireless communication and intermittent connection during cell handovers in cellular networks is data loss in systems [2]. Subsystem redundancies, extensive testing during the development stage, and the usage of only the best components may increase the reliability of an earth station system [3].…”