Adaptive cross-layer protection strategies for robust scalable video transmission over 802.11 wlans

Abstract

Abstract-Robust streaming of video over 802.11 wireless local area networks poses many challenges, including coping with bandwidth variations, data losses, and heterogeneity of the receivers. Currently, each network layer (including physical layer, media access control (MAC), transport, and application layers) provides a separate solution to these challenges by providing its own optimized adaptation and protection mechanisms. However, this layered strategy does not always result in an optimal overall performance for the transmission of video. Moreover, certain protection strategies can be implemented simultaneously in several layers and, hence, the optimal choices from the application and complexity perspective need to be identified. In this paper, we evaluate different error control and adaptation mechanisms available in the different layers for robust transmission of video, namely MAC retransmission strategy, application-layer forward error correction, bandwidth-adaptive compression using scalable coding, and adaptive packetization strategies. Subsequently, we propose a novel adaptive cross-layer protection strategy for enhancing the robustness and efficiency of scalable video transmission by performing tradeoffs between throughput, reliability, and delay depending on the channel conditions and application requirements. The results obtained using the proposed adaptive cross-layer protection strategies show a significantly improved visual performance for the transmitted video over a variety of channel conditions. Index Terms-adaptive cross-layer error protocol, robust scalable video transmission, IEEE 802.11 WLAN.

Joint Uplink and Downlink Optimization for Real-Time Multiuser Video Streaming Over WLANs

“…By adaptively utilizing the retry limit of the MAC layer with priority queueing, a wireless video scheme exploring unequal importance of video bitstreams was proposed in [19]. With cross-layer system integration, including application layer FEC, MAC retransmission, and adaptive packet size selection, a cross-layer error protection scheme was proposed to transmit video over IEEE 802.11a network [20].…”

“…The loss of a FGS layer packet containing significant bitplanes will make the following successfully received FGS layer packets containing lower bitplanes useless. Since we can know which packet arrives successfully at the application layer by checking the transmission index in the packet header, this wireless channel can be modelled as a packet erasure channel [16], [19], [20]. Applying FEC in the application layer across packets, such as systematic Reed-Solomon (RS) codes, has been shown as an effective way to alleviate the problem caused by packet loss [20].…”

“…Since we can know which packet arrives successfully at the application layer by checking the transmission index in the packet header, this wireless channel can be modelled as a packet erasure channel [16], [19], [20]. Applying FEC in the application layer across packets, such as systematic Reed-Solomon (RS) codes, has been shown as an effective way to alleviate the problem caused by packet loss [20]. An encoder will generate parity symbols for source symbols, and a corresponding RS decoder can recover the original source symbols if it receives at least out of symbols successfully when the locations of the erased symbols are known.…”

Cross-Layer Optimized Video Streaming Over Wireless Multihop Mesh Networks

“…Following the HCCA specification [12], this bandwidth is linked with the traffic specification parameters by [14]: (5) where is the transmission opportunity duration provided by the HCCA admission control for the video flow traffic of link is the nominal MAC service data unit (MSDU) size, 4 is the specified duration of the service interval [12] for the video flow traffic at link is the physical-layer rate, and represents the duration of the required overheads corresponding to polling and acknowledgment policies. As demonstrated by (5), even though the negotiated transmission opportunity duration is constant per link, the guaranteed bandwidth depends on the provided physical-layer rate , which in turn makes it dependent on the chosen modulation 5 . Finally, depending on the chosen modulation, may change for each MSDU.…”

“…The problem of multihop video streaming has recently been studied under a variety of scenarios [2]- [4]. However, the majority of this research does not consider the protection techniques available at the lower layers of the protocol stack and/or optimizes the video transport using purely end-to-end metrics, thereby excluding a significant amount of improvement that can occur by cross-layer design [5]- [7]. Consequently, the inherent network dynamics occurring in a multihop wireless mesh network as well as the interaction among the various layers of the protocol stack are not fully considered in the existing video streaming literature.…”