The inherent characteristics of the wireless channel, such as broadcast communication and high variability in channel quality, make it difficult to achieve high throughput in wireless mesh networks (WMNs). However, some innovative techniques like wireless inter-flow network coding and opportunistic routing leverage the broadcast nature of the wireless channel to improve the throughput. In addition, in order to cope with channel quality variation, the transmission rate can be adjusted using a rate adaptation algorithm. In this paper, we study how these fundamental techniques collaborate and how they can be combined into an integrated solution. We suggest Multi Rate Opportunistic Routing-aware Network Coding (MRORNC) as an integrated cross-layer approach that jointly determines the coded packet, potential next hops, and transmission rate using a novel metric. The simulation results demonstrate that the suggested approach can achieve higher throughput compared to the rateoblivious opportunistic routing-aware network coding solutions.

In this letter, we propose a novel model and corresponding algorithms to address the optimal utility max-min fair link adaptation in Downlink Multi-User (DL-MU) feature of the emerging IEEE 802.11ac WLAN standard. Herein, we first propose a simple yet accurate model to formulate the max-min fair link adaptation problem. Furthermore, this model guarantees the minimum utility gain of each receiver according to its requirements. In the second step, we show that the optimal solution of the proposed model can be obtained in polynomial time, and then the solution algorithms are proposed and analyzed. The simulation results demonstrate the significant achievement of the proposed utility-aware link adaptation approach in terms of max-min fairness and utility gain compared to utility-oblivious schemes.Index Terms-IEEE 802.11ac, DL-MU, utility max-min fairness, link adaptation

By exploiting the inherent nature of the H.264 encoded video streams, a practically optimal scheme that is devised to address the videocognizant link adaptation problem in the IEEE 802.11ac downlink multiuser (DL-MU) is proposed. To maximise the received video quality of the downlink users, it selects and allocates the modulation and coding scheme and power in a manner of minimising the expected video distortion caused by transmission failures. The objectives and constraints are set such that the users gain max-min fair opportunities to perceive, at least, the required video quality. The proposed scheme is analysed, and its efficiency is validated by experiments with respect to fairness and video quality compared with the video-oblivious methods.

In this paper, we propose a novel scheme for efficient video broadcasting on WLAN using IEEE 802.11e HCCA MAC protocol and H.264/SVC video compression technology. We rearrange an outgoing sequence of H.264/SVC NAL units according to the prioritization of their dimension, temporal, and quality scalability. In addition, our proposed scheme broadcasts the prioritized NAL units as various data-rates of PHY. Our scheme is implemented in the NCTUns ver. 4.0 network simulator, and is evaluated in terms of the numerical results. A real video clip is used as the input to our simulation, and is compressed as VBR. In terms of throughput within delay bound of 1 second, all wireless stations by the proposed scheme receive 25~30% more video data than simple broadcast schemes with various data-rates. Moreover, the proposed scheme improves throughput during contention period of 8.4% as compared to the simple broadcast scheme which has a longer contention period. In the end-to-end delay examination, the proposed scheme controls under 5~10% of the simple broadcast scheme. Finally, the proposed scheme enhances the video quality that improves SSIM up to 6~7% than the simple broadcast scheme. Keword-802.11e, HCCA, H.264/SVC, Video, Broadcast

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