Random Linear Network Coding for Wireless Layered Video Broadcast: General Design Methods for Adaptive Feedback-Free Transmission

Abstract

This paper studies the problem of broadcasting layered video streams over heterogeneous single-hop wireless networks using feedback-free random linear network coding (RLNC). We combine RLNC with unequal error protection (UEP) and our main purpose is twofold. First, to systematically investigate the benefits of UEP+RLNC layered approach in servicing users with different reception capabilities. Second, to study the effect of not using feedback, by comparing feedbackfree schemes with idealistic full-feedback schemes. To these ends, we study 'expected percentage of decoded frames' as a key content-independent performance metric and propose a general framework for calculation of this metric, which can highlight the effect of key system, video and channel parameters. We study the effect of number of layers and propose a scheme that selects the optimum number of layers adaptively to achieve the highest performance. Assessing the proposed schemes with real H.264 test streams, the trade-offs among the users' performances are discussed and the gain of adaptive selection of number of layers to improve the trade-offs is shown. Furthermore, it is observed that the performance gap between the proposed feedback-free scheme and the idealistic scheme is very small and the adaptive selection of number of video layers further closes the gap.

Instantly decodable network coding for real-time scalable video broadcast over wireless networks

“…In fact, the GOP in Fig. 3 is a closed GOP, in which the decoding of the frames inside the GOP is independent of frames outside the GOP [18]. Based on the figure, we can see that a receiver can decode 1, 2, 4, or 8 frames upon receiving first 1, 2, 3, or 4 video layers, respectively.…”

“…Fountain codes such as random linear network codes (RLNC) [13][14][15][16][17][18], raptor codes [19], and LT codes [20][21][22] have been studied extensively for efficient data delivery in wireless networks. These codes offer significant performance gains compared to conventional channel codes since channel protection is not pre-determined [21][22][23][24][25].…”

“…The works in [13,17,18,33] designed expanding window-based RLNC strategies for scalable video transmission such that coded packets are formed across different numbers of video layers. In particular, the authors in [17] used a probabilistic approach for selecting coding windows and included the packets in the lower video layers into all coded packets to obtain high decoding probabilities for the lower layers.…”

“…In particular, the authors in [17] used a probabilistic approach for selecting coding windows and included the packets in the lower video layers into all coded packets to obtain high decoding probabilities for the lower layers. Moreover, the authors in [18] considered a scalable video transmission with a hard deadline and used a deterministic approach for selecting coding windows over all transmissions before the deadline. Another work in [33] continued the work in [17] and addressed the problem of jointly determining the coding strategy and the scheduling decisions when receivers obtain layered video data from multiple servers.…”

“…Our work is inspired by the recent works on scalable video transmission using RLNC in [13,17,18,33]. In this work, we adopt XOR-based instantly decodable network coding (IDNC) to investigate its performance for scalable video transmission.…”