Real time video distribution is performed through unicast and multicast. Unicast video distribution uses multiple point to point connections, while multicast video distribution uses point to multipoint transmission. Unicast and multicast are important building blocks of many Internet multimedia applications such as videoconferencing, distance learning, multi-receiver video programs.
Multimedia applications are growing rapidly. Real time video distribution is an important IP multicast application. However, there is no guarantee for quality of service to real time video in current best effort networks because of the dynamic network conditions.
Bandwidth adaptability is the main requirement of real time video distribution due to varying network conditions. Real time video distribution has requirement of bandwidth adaptability, due to dynamic network conditions. The flows which are non- adaptive to bandwidth suffer from:
- Under utilization or over utilization of the available bandwidth
- Unfair bandwidth allocation
The first type of deficiency degrades the video quality while the second one shows the unfairness between the adaptive and non-adaptive traffic.
Real time video adaptation approaches
Video multicast approaches can be classified through two distinct properties (Jiangchuan Liu, Bo Li at al., 2003)
- Video rate: existing approaches generally fall into two categories
- Single rate
- Multi rate
- End system (end-to-end)
- Active service (intermediate network nodes)
Existing end system (end-to-end) approaches are classified according to these properties such as (Jiangchuan Liu at al., 2003)
- Single-rate adaptation (single-rate, end-to-end)
- Simulcast (multi-rate, end-to-end)
- Layered adaptation (multi-rate, end-to-end)
The main focus of this research activity is to analyze different Adaptive Real-time Video Multicast techniques and to compare them in different network conditions.
According to initially survey, following issues have been identified in the existing schemes of real time video distributions:
- Rate Adaptation: In the same multicast session, different receivers may have different processing capabilities because internet is the heterogeneous network.
- Network Congestion
- Fair Bandwidth Allocation
Adaptive smooth multicast protocol is the recently proposed single rate multicast congestion control protocol. Packet pair receiver driven cumulative layer multicast is the receiver driven layered multicast congestion control protocols. Lot of research has been carried out to evaluate the performance of PLM (Puangpronpitag et al., 2008). There is no known study that evaluates these protocols in comparison. However, we evaluate these protocols in comparison using evaluation criteria such as TCP-friendliness, responsiveness, throughput, packet loss, end-to-end delay and jitter.
The main goal of this research activity is to evaluate theoretically and practically adaptive real-time video multicast techniques. This research activity will identify the characteristics of real-time video multicast protocols and will identify the best adaptive technique for multicast streaming. This work will try to provide some guidelines to enhance existing protocols and may provide suggestions to overcome the limitation of these protocols.
In order to accomplish the goals stated in this thesis, a thorough literature survey of the existing work regarding the individual performance evaluation of Adaptive Smooth Multicast Protocol (ASMP) and Packet-pair Receiver Driven Cumulative Layer Multicast (PLM) has been carried out and these mechanisms have been implemented in NS2 simulator. The aim of the literature study is to give a deep understanding about the ASMP and PLM mechanisms and discuss their limitations. This research has been limited to software based simulations. Simulations have been performed on Network Simulator 2 (NS2). NS2 is used to generate the network traffic with different configurations.
The main focus of this research activity is to provide a performance evaluation of Adaptive Smooth Multicast Protocol (ASMP) in comparison with Packet-pair Receiver Driven Cumulative Layer Multicast Protocol (PLM). This research activity shall enable us to determine the best technique for adaptive real time video streaming multicast in varying network conditions. This research activity identified the limitations and capabilities of both protocols.
Rest of the thesis is organized as follows: In chapter 2 provides a survey of adaptive real-time video multicast techniques, in chapter 3 discussed about multicast congestion control protocols, chapter 4 defines the simulation setup and results and chapter 5 provides the conclusion and future work.