A Study of Real-time Transmission and Content Protection for TV News Gathering via Wireless Internet Networks
Date Issued
2011
Date
2011
Author(s)
Liu, Hsing-Shao
Abstract
Facing the intense competition resulted from the emerging multimedia services such as mobile TV and Internet TV, tranditional news TV stations are forced to rebuild the processes of news coverage, editing, and broadcasting to deliver their TV services more efficiently but in a low-cost manner. According to the context of traditional news TV media and the endeavor which news TV stations have made to use novel wireless communication technology WiMAX to facilitate above processes, we propose two research issues to assist such development.
The first issue is based on the requirement of live news transmission for TV stations. Traditionally, it is done by satellite network which is greatly expensive. Currently, it is possible to be completed by using cost-effective transmission technology WiMAX. However, to maintain the standard-definition (SD) quality, the video of live news content will normally have data rate of 2.5Mbps encoded by modern compression technique MPEG4. Given that one WiMAX base station usually has uplink bandwidth of 2 to 3Mbps, it is difficult for WiMAX to guarantee the service quality for delivering live news video program. Besides, transmiting one SD program almost exhausts the uplink bandwidth of one WiMAX base station and thus prevents other mobile applications from using this base station. It is also difficult for WiMAX operators to dedicate one WiMAX base station only to single service. Therefore, we propose the multi-link transmission approach, which aggregates bandwidth resources from multiple wireless base stations to share the load of transmitting one SD program and have the benefit of link backup for network dynamics. After surveying and literature review, we use concurrent multipath transfer (CMT) which has been embedded into the module of stream control transmission protocol (SCTP) in FreeBSD 7.1. We futher build up and fine-tune CMT system to fulfill the bandwidth aggregation and conduct experiments for evaluating this system’s performance. After several experiments, we have identified several critical parameters which can enable CMT system more suitable for real-time transmission applications. Meanwhile, we also recognize the problem of throughput degradation in CMT. Thus, we further propose a novel approach called VC-CMT (VC stands for virtual connection) to improve the throughput gains obtained from aggregated links in CMT. By using NS-2.31 (Network Simulator with Version 2.31), we can investigate VC-CMT performance. The result shows VC-CMT can more effectively aggregate the link’s bandwidth than CMT.
The second research issue is based on the requirement of delivering mobile video service and Internet video service in TV stations. We propose a solution to protect the video services from eavesdropping. Given that mobile video servces are always rendered in a pulic wireless network environment, the risk of content leakage and eavesdropping is raised and thus the content providers’ interests are easy to be infringed. However, tradidtional encryption approaches often sacrifice the security level to attain the demand of real-time transmission. Thus, the risk of content leakage and eavesdropping still exists. Besides, given that the capability of mobile devices used by clients is enhanced very soon and can play out with richer video content, to transmit richer video content will not only consumes more network bandwidth but also increase the protection difficulty. Furhtermore, due to the diversity of mobile TV devices nowadays, the performance difference between them is large. It requires further examination for current encryption approaches to realize if they can be applied for various kinds of mobile TV devices. To maintain multiple encryption approaches to protect video content due to the diversity of mobile TV devices will be a difficult task for Internet TV service providers. Therefore, we propose an encryption mechanism called SVOD (Secure Video on Demand) with one-time pad feature, which can not only be applied in different types of video content and mobile devices, but also adapt to the network dynamics. It can also leverage the requirements between real-time transmission and content security levels to effectively guarantee the service quality of mobile video applications. SVOD uses the information of playback buffer occupancy (PBO) which is fed back by client periodically to determine the encryption complexity to intervene the video server’s sending rates. We implement SVOD system and investigate its performance. The experiments show that this SVOD system can achieve the advantages mentioned above and can leverage the quality of service (QoS) and quality of protection (QoP) for mobile video services.
Subjects
Live News Broadcasting
Bandwidth Aggregation
Concurrent Multipath Transfer (CMT)
Secure Video on Demand (SVOD)
Playback Buffer Occupancy (PBO)
Quality of Service (QoS)
Quality of Protection (QoP)
Type
thesis
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