Elements of Next-Generation Wireless Video Systems: Millimeter-Wave and Device-to-Device Algorithms

This dissertation explores the possible issues and proposes promising solutions in next generation wireless video systems.;We investigated a joint compression and relaying algorithm for outdoor video applications. Transmission of high-definition (HD) video is a promising application for millimeter-wave wireless links, since very high transmission rates are possible. In particular we consider a sports stadium broadcasting system where signals from multiple cameras are transmitted to a central location. Due to the high path-loss of 60 GHz radiation over the large distances encountered in this scenario, the use of relays might be required. The proposed algorithm analyzes the joint selection of the routes and the compression rates from the various sources for maximization of the overall video quality. Extensive simulations demonstrate that high-quality transmission is possible for at least ten cameras over distances of 300 m. Furthermore, optimization of the video quality gives results that can significantly outperform algorithms that maximize data rates.;For beam training in millimeter-wave wireless systems, we investigated a fast beam training algorithm with receive beamforming. Both IEEE standards and the academic literature have generally considered beam training protocols involving exhaustive search over all possible beam directions for both the beamforming initiator and responder. However, this operation requires a long time (and thus overhead) when the beamwidth is quite narrow such as for mm-wave beams (1 degree in the worst case). To alleviate this problem, we propose two types of adaptive beam training protocols for fixed and adaptive modulation, respectively, which take into account the unique propagation characteristics of millimeter waves. For fixed modulation, the proposed protocol allows for interactive beam training, stopping the search when a local maximum of the power angular spectrum is found that is sufficient to support the chosen modulation/coding scheme. We furthermore suggest approaches to prioritize certain directions determined from the propagation geometry, long-term statistics, etc. For adaptive modulation, the proposed protocol uses iterative multi-level beam training concepts for fast link configuration that provide an exhaustive search with significantly lower complexity.;For next generation mobile systems, direct communication between mobile stations, i.e., called device-to-device communications, is actively discussed in next generation 3GPP cellular mobile systems. In addition, one of major applications of device-to-device mobile systems is adaptive video streaming. Video streaming is becoming the dominant application for wireless data transmission. Its spectral efficiency can be greatly enhanced by caching and device-to-device (D2D) communications. In this dissertation, we consider a system where each device pre-caches a subset of video files from a library, and users requesting a file that is not in their own library gets it delivered through D2D communication. We develop and analyze centralized and distributed algorithms for the delivery phase, encompassing a link scheduling and a streaming component. The centralized scheduling is based on the max-weighted independent set (MWIS) principle, and uses message-passing to determine max-independent sets. The distributed scheduling is based on the FlashLinQ link scheduling algorithm enhanced by max-weight scheduling. The streaming component for both centralized and distributed algorithms makes use of a quality-aware stochastic optimization approach for which users place sequential requests for video "chunks" into a request queue, and adapt the video quality according to the state of such a queue. The streaming and the scheduling components are coupled by the length of the users' request queues, which provide the weights of the objective function in the max-weighted independent set problem that the scheduler must solve at each scheduling time slot. The per-chunk quality adaptation is reminiscent of current DASH technology (Dynamic Adaptive Streaming over HTTP), considered in 3GPP for such applications. We evaluate the performance (PSNR and stall probability) of the proposed algorithms by extensive simulation and compare with a baseline scheme formed by the FlashLinQ D2D protocol for scheduling and DASH for streaming. We find that our proposed algorithms provide sizeable performance gains in terms of user satisfaction and queue stability. (Abstract shortened by UMI.).