Real-time video streaming traffic and related applications have witnessed significant growth in recent years. However, this has been accompanied by some challenging issues, predominantly resource utilization. IP multicasting, as a solution to this problem, suffers from many problems. Using scalable video coding could not gain wide adoption in the industry, due to reduced compression efficiency and additional computational complexity. The emerging software-defined networking (SDN)and network function virtualization (NFV) paradigms enable re-searchers to cope with IP multicasting issues in novel ways. In this paper, by leveraging the SDN and NFV concepts, we introduce a cost-aware approach to provide advanced video coding (AVC)-based real-time video streaming services in the network. In this study, we use two types of virtualized network functions (VNFs): virtual reverse proxy (VRP) and virtual transcoder (VTF)functions. At the edge of the network, VRPs are responsible for collecting clients’ requests and sending them to an SDN controller. Then, executing a mixed-integer linear program (MILP) determines an optimal multicast tree from an appropriate set of video source servers to the optimal group of transcoders. The desired video is sent over the multicast tree. The VTFs transcode the received video segments and stream to the requested VRPs over unicast paths. To mitigate the time complexity of the proposed MILPmodel, we propose a heuristic algorithm that determines a near-optimal solution in a reasonable amount of time. Using theMiniNet emulator, we evaluate the proposed approach and show it achieves better performance in terms of cost and resource utilization in comparison with traditional multicast and unicast approaches.

1. On Optimizing Resource Utilization in AVC-based
Real-time Video Streaming
Alireza Erfanian, Farzad Tashtarian, Reza Farahani, Christian Timmerer, Hermann Hellwagner
29 June-3 July 2020
Ghent, Belgium(Virtual Conference)
This research has been supported in part by the Christian Doppler Laboratory ATHENA:
https://athena.itec.aau.at/

2. • Introduction
• Motivation example
• Proposed approaches
• Proposed MILP model
• Proposed heuristic algorithm
• Results
• Conclusion and future works
2
Outline

3. 3
Introduction
Source :https://www.sandvine.com/

4. • Unicast approach:
• Redundant streams
• Waste network resources
• Multicast approaches like Multicast ABR:
• Impose the packet changing in the multicast
source and the edge
• Each router has to maintain the state of the
multicast group
• Need to special router with multicast support
• Routers do not have a global view of the
network status
4
Introduction

5. Our Proposed Approach
• Employ the SDN and NFV paradigm to mitigate
the Multicast ABR problems.
• Introduce the VRP (Virtual Reverse Proxy) to
aggregate the clients requests
• VTF (Virtual Transcoding Function) to
transcoding a video quality to the requested
quality by clients in the network
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6. Motivation Example – Multicast ABR
• Each requested quality should be transferred through a
separate multicast tree
• Determining the optimal multicast tree for a subset of
nodes is a NP-hard problem.
• Total bandwidth consumption: 138.2Mbps
6

7. Motivation Example – Multicast SVC
• Advantage:
• Using Scalable video coding (SVC) could reduce
bandwidth consumption.
• Disadvantages:
• Maintenance multiple trees
• SVC inefficiency and overhead(about 10% per each
enhancement layer)
• It is not Scalable
• Total bandwidth consumption: 136.8Mbps
7

8. Motivation Example – Our Approach
• Transfer the highest requested quality to some point-of-
presence (PoP) nodes in the network.
• Transcoding it to other requested qualities by clients
• Total bandwidth consumption: 112.2Mbps
8

9. Motivation Example – Our Approach
• More VTFs ⇒ Closer to edge (clients) ⇒ Save more bandwidth
• Increase the transcoding cost
• Problem: Determine
the optimal number and locations of the VTFs
• Determining an appropriate multicast tree
• Total bandwidth usage 107.8Mbps
9

10. 10
• We leverage the SDN concept and NFV technology to efficiently serve DASH clients’ requests in AVC real-
time streaming.
• We propose an MILP model to jointly construct the optimal multicast tree and VTFs’ placement with the
objective of minimizing the resource utilization and VTFs’ costs.
• We propose a heuristic approach to achieve a near optimal solution in polynomial time.
• We evaluate the performance of the proposed framework using MiniNet and compare it with other SVC-
and AVC based multicast and unicast approaches.
Our Contribution

11. Proposed MILP Model. Objective function
We formulated the mentioned problem as the following MILP model:
𝑀𝑖𝑛. 𝛼1 𝑡,𝑓
𝐹 𝑡,𝑓 𝜋 𝑡,𝑓
𝐹∗ + 𝛼2( 𝑖,𝑗,𝑡,𝑥
𝑑 𝑖,𝑗
𝑡,𝑥
𝜋 𝑖,𝑗
′
𝐷∗ + 𝑖,𝑗
𝐿 𝑖,𝑗 𝜋𝑖,𝑗
′
𝐿∗ )
s. t. Constraints 1 − 15
For more details please refer to the paper
11

12. 12
Proposed heuristic Algorithm
• Proposed MILP model is NP-hard and is not
scalable.
• To mitigate MILP time complexity we propose a
heuristic algorithm in polynomial time complexity.

13. 13
Evaluation Setup
• Consider three real network topologies in a small-, medium-, and large-scale consisting of 11, 47 and 113
PoP nodes and 5, 15 and 30 VRPs, respectively.
• Use MiniNet as the emulation system and Floodlight as the SDN controller.
• Consider different VTF instance types as follow:

14. Results-Scenario I
Comparing the proposed MILP and heuristic approaches in term of number of selected VTFs and
measured total transcoding costs for small scale topology.
14

15. Results- Scenario I
15
Comparing the proposed MILP and heuristic approaches in term of consumed bandwidth and
generated OF commands for small scale topology.

16. Results- Scenario II
16
Comparing proposed heuristic algorithm with other studied approaches in terms of bandwidth
consumption and generated OF commands in different network size.

17. Results- Scenario III
17
Comparing the performance of the proposed approaches with other methods in terms of bandwidth
consumption and generated OF commands for different homogeneity levels of VRPs’ requests in small
scale topology.

18. Results: Execution time of proposed heuristic algorithm.
18

19. Conclusion and future works
19
• Leveraging the SDN and NFV paradigms to propose an AVC-based real-time video multicast
streaming framework.
• Employ two types of VNFs named VRP and VTF.
• Proposing the heuristic algorithm to address time complexity of the proposed MILP model.
• Evaluating the proposed approaches by using MiniNet and Floodlight as the SDN controller and
compared with other unicast and multicast approaches.
• Improving the MILP and heuristic approaches performance and considering E2E delay are the open
challenges for the future works.

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