In traditional communication system, information of APP (Application) layer, transport layer and MAC (Media Access Control)layer has not been fully interacted,which inevitably leads to inconsistencies among TCP congestion state, clients'requirements and resource allocation. To solve the problem, we propose a joint optimization framework, which consists of APP layer, transport layer and MAC layer, to improve the video clients'playback experience and system throughput. First, a client requirement aware autonomous packet drop strategy, based on packet importance, channel condition and playback status, is developed to decrease the network load and the probability of rebuffering events. Further, TCP (Transmission Control Protocol) state aware downlink and uplink resource allocation schemes are proposed to achieve smooth video transmission and steady ACK (Acknowledgement) feedback respectively. For downlink scheme, maximum transmission capacity requirement for each client is calculated based on feedback ACK information from transport layer to avoid allocating excessive resource to the client, whose ACK feedback is blocked due to bad uplink channel condition. For uplink scheme, information of RTO (Retransmission Timeout) and TCP congestion window are utilized to indicate ACK scheduling priority. The simulation results show that our algorithm can signficantly improve the system throughput and the clients'playback continuity with acceptable video quality.

中文翻译：

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长期演进系统中视频客户端的APP、传输和MAC层的跨层优化回放体验驱动

在传统的通信系统中，APP（应用）层、传输层和MAC（媒体访问控制）层的信息没有充分交互，这不可避免地导致TCP拥塞状态、客户端需求和资源分配之间的不一致。针对该问题，我们提出了一种由APP层、传输层和MAC层组成的联合优化框架，以提高视频客户端的播放体验和系统吞吐量。首先，基于数据包重要性、信道条件和播放状态，开发了一种客户端需求感知自主丢包策略，以减少网络负载和重新缓冲事件的概率。更多，提出了TCP（传输控制协议）状态感知下行链路和上行链路资源分配方案，以分别实现流畅的视频传输和稳定的ACK（确认）反馈。对于下行方案，根据传输层反馈的ACK信息计算每个客户端的最大传输容量要求，以避免为客户端分配过多的资源，因为上行信道条件不好导致ACK反馈被阻塞。对于上行方案，利用RTO(Retransmission Timeout)和TCP拥塞窗口信息来指示ACK调度优先级。仿真结果表明，在可接受的视频质量下，我们的算法可以显着提高系统吞吐量和客户端的播放连续性。根据传输层反馈的ACK信息计算每个客户端的最大传输容量要求，以避免为客户端分配过多的资源，其ACK反馈由于上行信道条件不好而被阻塞。对于上行方案，利用RTO(Retransmission Timeout)和TCP拥塞窗口信息来指示ACK调度优先级。仿真结果表明，我们的算法可以显着提高系统吞吐量和客户端的播放连续性，并且视频质量可以接受。根据传输层反馈的ACK信息计算每个客户端的最大传输容量要求，以避免为客户端分配过多的资源，其ACK反馈由于上行信道条件不好而被阻塞。对于上行方案，利用RTO(Retransmission Timeout)和TCP拥塞窗口信息来指示ACK调度优先级。仿真结果表明，在可接受的视频质量下，我们的算法可以显着提高系统吞吐量和客户端的播放连续性。利用RTO(Retransmission Timeout)和TCP拥塞窗口信息来指示ACK调度优先级。仿真结果表明，在可接受的视频质量下，我们的算法可以显着提高系统吞吐量和客户端的播放连续性。利用RTO(Retransmission Timeout)和TCP拥塞窗口信息来指示ACK调度优先级。仿真结果表明，在可接受的视频质量下，我们的算法可以显着提高系统吞吐量和客户端的播放连续性。