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Joint Adaptive Rate and Scheduling in Cellular Wireless Networks

  • Author(s): Chang, Hung-Bin
  • Advisor(s): Rubin, Izhak
  • et al.
Abstract

We consider adaptive-rate scheduling algorithms for multicast and unicast transmissions of data and messages and video streams across cellular wireless systems. To achieve higher spectral efficiency, small cells that are managed by micro base station nodes are deployed. Often, both micro and macro cells are used, forming heterogeneous cellular network layouts. We also integrate into the networking mechanisms that are developed effective methods for mitigating inter-cell signal interference effects. For this purpose, we design optimized scheduling mechanisms, including fractional frequency reuse (FFR) and Multicast-broadcast single-frequency network (MBSFN)) methods.

For effective multicast message distributions, whereby a high fraction of user mobiles must be covered, we determine the critical positions at which a cell's mobiles experience the lowest SINR levels. We consider a wide range of reuse-k FDMA and TDMA based adaptive rate scheduling mechanisms, for k = 1,3,4,7. For such systems, we determine the joint modulation/coding set and spatial scheduling mechanisms that maximize the system's throughput capacity rate, under prescribed user fairness coverage conditions. For effective unicast message distributions, we propose optimal configurations of downlink and uplink FFR scheduling mechanisms used by densely deployed (macro or micro) BS nodes in cellular wireless networks under absolute and proportional fairness requirements. For this purpose, we propose an optimal intra-cell classification of interior and exterior mobiles, coupled with optimal bandwidth allocation to each class to maximize the system's spectral efficiency.

We develop and study adaptive rate scheduling schemes for downlink transmissions of multicast and unicast video streams over wireless cells. We consider a service under which most mobile clients receive video streams at specified base Quality of Experience (QoE) levels, even when these users experience low channel quality conditions. We employ a proxy video manager and resource controller which is placed at the base station facility. The manager classifies cell users into two groups, based on their experienced communications channel conditions. Users that experience higher quality reception states can be provided video streams at higher video quality levels. We develop adaptive rate and scheduling mechanisms that serve to minimize the average bandwidth per stream required for the support of video streams, hence allowing the support of a higher number of users. To demonstrate the design of such a system, we consider a utility function that accounts for the willingness of users to provide excess payments when they receive a video stream at a sufficiently high quality level.

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