Abstract
Abstract Smartphones have been equipped with the cameras that can shoot HD videos, and the video chat apps such as Skype are becoming popular. We can, therefore, intuitively predict the trend that users are expecting to enjoy HD video chats via utilizing their smartphones. Most of the current Internet services, however, cannot support the live HD video transmissions because of their low uplink rate. In order to overcome this limit, we propose to offload the uplink transmissions to cooperative users via cognitive radio networks. Specifically, we first divide the video stream into several substreams according to the H.264/SVC standard and the cooperative users’ uplink rates. Then, the cooperative users are selected by employing our proposed optimal multiple stopping method. Finally, the substreams are assigned to the selected cooperative users by a 0-1 Knapsack-based allocation algorithm. The simulation results demonstrate that our proposed scheme can successfully support 720P HD video chats.
Highlights
High-definition cameras are currently available on popular smartphones
In order to enable the smartphone-based HD video chat, we propose to utilize cooperative users to help with the uplink transmission in cognitive radio networks (CRNs)
The total time for transmission between primary user (PU) transmitter and the relay nodes is denoted by Tsr, which is the sum of T1, T2, · · ·, Tm
Summary
High-definition cameras are currently available on popular smartphones. These cameras have been physically ready to support HD video shootings (such as 720P and 1,080P). In order to enable the smartphone-based HD video chat, we propose to utilize cooperative users to help with the uplink transmission in cognitive radio networks (CRNs). To the best of our knowledge, this is the first work to formulate an optimal multiple stopping model to solve the problem of relay selection for supporting HD video chat via cooperative transmission. Et al 2013 [13] studies the relay selection problem in cognitive networks by applying optimal stopping theory. This approach does not look at the information from all the candidate relay nodes as it scans the candidate secondary user (SU) relays one by one and stops when a suitable relay is identified. We design an optimal multiple stopping rule to find out the relays with good performance and within a short observation time
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