Delay-constrained streaming in hybrid cellular and cooperative ad hoc networks

Wireless real-time video is frequently used in multimedia applications to provide interactive mobile streaming services. However, delivering real-time video when a cluster of adjacent smartphones attempts to access the same content is challenging because the existing schemes are not fully compatible with limited cellular resources under stringent delay constraints. When the resources of a cellular network are shared by many clients, the available bandwidth allocated to each device is inevitably insufficient. This inadequacy also leads to large end-to-end delays, which degrades video quality. To address the problem, we propose a cooperative scheme called delay-constrained streaming in hybrid networks (DCSHN), which focuses on effective real-time traffic with delay constraints, i.e., goodput. First, a mathematical model is introduced to describe the maximization problem of goodput utility when a group of devices is watching the same real-time video. Second, a data-flow distribution mechanism is developed to obtain a close-to-optimal result to the optimization problem with fast convergence for efficient online operation. Then, a prototype on the Android platform involving real-time video encoded with the H.264 codec is constructed to test the performance. The real-world test shows that the proposed approach yields reasonably improved outcomes, including a better video peak signal-to-noise ratio (PSNR), end-to-end delay, and goodput.