Collaborative Research: Opportunistic Scheduling for Multimedia Wireless Systems

这个合作项目的重点是网络级的解决方案，利用无线环境的时变特性，以提高系统的整体性能，同时考虑到服务质量（QoS）和多媒体无线系统的公平性。所提出的算法被归类为“机会主义”，因为它们考虑了信道条件（以及每用户效用的相关定义）。以下研究活动将特别追求：有和没有明确的延迟要求，以及在频域的机会调度的机会调度。与机会调度没有明确的延迟要求的目标是开发调度算法，利用随时间变化的性质的无线信道，以优化网络性能下不同的公平性要求。特别是，信道估计问题将探讨快速的方法，有效地跟踪系统参数，通过随机近似类型的技术将开发。对于具有明确延迟要求的机会调度，目标将是开发用于实时应用（例如语音和视频）的调度机制，其中目标不仅是基于信道条件和公平性约束来调度用户，而且还基于其截止日期。特别是，机会调度没有个人的QoS约束和机会调度与个人的QoS要求的问题将被研究。为此，离线优化调度解决方案，提供基准评估其他计划将被开发。另一方面，考虑到网络流量统计的在线算法将被开发和验证的实用性。最后，与频域中的机会调度相关的活动将考虑利用无线系统中的时域和频域分集。特别是，将探讨的问题，其目标将是最大限度地提高系统的性能，功率可以是一个明确的约束或惩罚函数。这里将探讨的其他类型的问题将处理最小化受到性能约束的发射功率。

This collaborative project focuses on network-level solutions for exploiting the time-varying nature of the wireless environment to increase the overall performance of the system taking into account quality of service (QoS) and fairness for Multimedia Wireless Systems. The proposed algorithms are classified "opportunistic" since they consider channel conditions (and related definitions of per-user utility). The following research activities will be particularly pursued: opportunistic scheduling with and without explicit delay requirements as well as opportunistic scheduling in the frequency domain. The objective related to opportunistic scheduling without explicit delay requirements is to develop scheduling algorithms that exploit the time-varying nature of the wireless channel to optimize network performance under different fairness requirements. In particular, the channel estimation problem will be explored for which fast methodologies to effectively track the system parameters through stochastic approximation types of techniques will be developed. For opportunistic scheduling with explicit delay requirements, the goal will be to develop scheduling mechanisms for real-time applications such as voice and video where the objective is not only to schedule users based on their channel conditions and fairness constraints, but also based on their deadlines. In particular, the problems of opportunistic scheduling without individual QoS constraints and problems of opportunistic scheduling with individual QoS requirements will be studied. For that purpose, the off-line optimal scheduling solutions that provide benchmarks in evaluating other schemes will be developed. On the other hand, the on-line algorithms that take into account network traffic statistics will be developed and proven on practicability. Finally, the activities related to opportunistic scheduling in the frequency domain will consider taking advantage of both time-domain and frequency-domain diversity in wireless systems. In particular, the problems will be explored where the objective will be to maximize the system performance where power could be an explicit constraint or a penalty function. Other types of problems that will be explored here will deal with minimizing the transmitted power subject to performance constraints.