An occupancy-based and channel-aware multi-level adaptive scheme for video communications over wireless channels

Abstract

Video streaming over wireless channels is challenged with the time-varying nature of the underlying channels and the stringent requirements of video applications. In particular, video streaming has strict requirements on bandwidth, delay, and loss rate while wireless channels are dynamic and error-prone by nature. In this article, we propose a novel multilevel adaptive scheme that is designed to mitigate the challenges facing video streaming over unreliable channels. This is done while preventing potential playback discontinuities and guaranteeing a graceful degradation of the rendered video quality. Scalable video coding, adaptive modulation, and adaptive channel coding are integrated to achieve the objectives of the proposed scheme. If adaptive modulation and channel coding are not enough to guarantee the on-time delivery of decodable video frames, we adopt scalable coding. Simulation results show that the proposed adaptive scheme achieves an improvement of about 2.5 dB in the peak signal-to-noise ratio over a nonadaptive one. In addition, the proposed scheme reduces the number of starvation instances by 50 and 90% in the cases of Stop-and-Wait and Go-Back-N automatic repeat requests, respectively.

Link Adaptation for Wireless Video Communication Systems

“…2.6. The transmission efficiency of SW, GBN, and SR is studied in [28]. In hybrid ARQ, FEC is used to correct errors in the received packets.…”

“…Hence, when the channel is in a bad state, robust low-level modulation schemes such as binary phase shift keying (BPSK) can be used whereas when the channel is in a good state higher level modulation schemes such as 64-quadrature amplitude modulation (64-QAM) can be used to achieve higher data rates. Adaptive modulation can be jointly designed with FEC while it could also be integrated with the source encoder to achieve effective video transmission [26,28].…”

“…While this is an acceptable assumption in wireless environments with small RTT, it is typically not a plausible one for wireless networks with large RTT. An adaptive transmission scheme is proposed in [28] to enhance video streaming over wireless channels by integrating scalable video coding, adaptive channel coding and adaptive modulation. The proposed scheme monitors the playback buffer occupancy through a feedback channel and implements frame-type-dependent scaling at the transmitter to prevent potential playback discontinuities.…”

“…The target encoding bit rate is initially set at ω = (120 2 /128 2 ) χ where χ is assumed to be 2 Mbps. For particular video communication systems [25,28], the source encoding bit rate is adjusted to match the offered system throughput in an attempt to ensure timely delivery of video frames at the receiver. Adjusting the source encoding bit rate in accordance to the offered system throughput affects the average PSNR.…”

“…Two VBR (variable bit rate) video sequences are considered in the evaluation, namely, the NBC News (frames 7505 to 8405) and Sony (frames 12305 to 13205) video sequences[146]. Both sequences are encoded using H.264 encoder with quantization parameters(28,28,30) for I, P, and B frames, respectively. Moreover, the sequences are encoded using a GoP size of 16 frames with 3 B frames in between I/P key frames.…”