HyunYong Lee

Enhanced UPnP QoS Architecture for Network-adaptive Streaming Service in Home Networks

The existing versions of UPnP QoS architecture have several limitations associated with how they provide QoS-guaranteed streaming service over dynamically time-varying networks. In this paper, an enhanced UPnP QoS architecture is proposed to support network-adaptive media streaming in home networks. The proposed streaming scheme is verified by realizing a prototype implementation over an UPnP streaming testbed.

Simplified clique detection for collusion-resistant reputation management scheme in P2P networks

Reputation management systems have been proposed to provide helpful information for reliable peer selection in an environment where honest peers coexist with malicious peers. The reputation management systems generally seek to generate an accurate assessment in the face of various factors including but not limited to potentially adversarial environments. Thus, performance of the reputation management systems mainly depends on an effectiveness of detection of various malicious attacks. In this paper, we focus on a detection of colluders who usually form a clique among various malicious attacks since only heuristic-based approaches which are still vulnerable to sophisticated colluding attacks have been proposed due to a NP-completeness of the detection of colluders forming a clique. For collusion-resistant reputation management, we introduce a simplified clique detection that can be applied to the reputation management system so that the colluders forming a clique can be easily detected. Then, we introduce a way to calculate a collusion probability-weighted reputation to reduce falsely cumulated reputation by malicious collusions. Through simulations, we show that our approach is enough to detect colluders forming a clique and shows better performance than heuristic-based approach in terms of authentic file download and reputation management.

Multi-View 3D Video Transport using Application Layer Multicast with View Switching Delay Constraints

This paper proposes an efficient method to deliver multi-view 3D video in a synchronous manner for nodes that frequently switch views by employing application layer multicast (ALM) trees. The proposed method attempts to bound inter-view delay variation by managing ALM trees with delay and delay variation constraints. The resulting view-switching between selected nodes of different ALM trees can thus provide synchronized view of multi-view videos and improve the immersive experience of end users.

Multi-Swarm Collaboration for Improving Content Availability in Swarming Systems

Despite its great success, BitTorrent suffers from a content unavailability problem where peers can not complete their content downloads due to some missing chunks, which is caused by an absence of seeders. Multi-swarm collaboration approach is a natural choice for improving the content avail- ability, since the content unavailability can not be managed by one swarm easily. Most existing multi-swarm collaboration approaches, however, show content-related limitations, which limit their application scopes. In this paper, we introduce a new kind of multi-swarm collaboration utilizing a swarm as a temporal storage. In a nutshell, the collaborating swarms cache some chunks of each other that are likely to be unavailable when the seeders are online and share the cached chunks when the content unavailability happens. Our approach enables any swarms to collaborate with each other without the content-related limitations. Simulation results show that our approach improves the number of download completions by over 50% compared to vanilla BitTorrent with low caching overhead. The results also show that our approach enables the peers participating in our approach to enjoy better performance than other peers, which can be an peer incentive.

BiCo: Network operator-friendly P2P traffic control through bilateral cooperation with peers

The volume of P2P application traffic has increased so much that network operator-friendly traffic control techniques are recently proposed to localize the P2P traffic. In the existing approaches, the network operator provides network information as a guidance to peers so that the P2P traffic will flow as they intend, thus, realizing unilateral interaction from the network operator to the peers. In this paper, we propose bilateral cooperation between the network operator and the peers, in short BiCo. In BiCo, both parties participate in the P2P traffic control actively to improve a network efficiency while solving the identified limitations of existing work. In a nutshell, the peers provide peer-level information to the network operator, which would otherwise require the network operator to perform a flow-level measurement and analysis. We divide measurement work into two parts, letting the peers collect fine-grained traffic information and enabling the network operator to grasp macroscopic information in order to issue useful guidances (including allowable traffic volume missing in the existing work) to the peers. Our simulation results show that BiCo improves the network efficiency by distributing the traffic evenly over intra-domain links and by trying to fully utilize inter-domain links with given constraints while showing similar download completion time compared to the existing unilateral interaction.

SeederTrading: Trading Swarm Capacity for Improving Content Distribution

A surplus seeding capacity is often observed in large swarms with many seeders while small swarms with few seeders suffer from low download performance. In this paper, we propose a multi-swarm collaboration approach, called textit{Seeder Trading} to improve overall content distribution performance by exploiting non-uniform distribution of seeders over swarms. In a nutshell, we enable the over-seeded swarms to share their surplus seeding capacity with the under-seeded swarms. To realize the Seeder Trading, we resolve several issues including estimation of swarm capacity, selection of swarms to be matched, and seeder trading across the selected swarms. Our extensive measurement shows that 12.9% of under-seeded swarms can achieve their maximum download throughput by utilizing the surplus seeding capacity. Simulation results show that the under-seeded swarms can improve the download performance by over 20% while retaining the content distribution performance of over-seeded swarms. We also show that the trading seeding capacity across swarms can be done within 60 seconds.

Multi-swarm collaboration for improved content availability in BitTorrent-like systems

In spite of its success, BitTorrent is facing a content unavailability problem where peers can not finish their content download due to an absence of seeders. Although some approaches have been proposed to improve the content availability, the prior conditions such as a downloaded content and a set of related contents to be bundled limit their application scopes. Our main contribution is a multi-swarm collaboration to improve the content availability of the BitTorrent-like systems without the content-related limitations. The multi-swarm collaboration enables the collaborating swarms cache some chunks that are likely to be unavailable in near future of each other when the seeders are online and share the cached chunks when the content unavailability happens. Our approach enables any swarms that have appropriate amount of resources to collaborate with each other for the improved content availability. Through simulations, we show that the multi-swarm collaboration improves the peer performance as well as the content availability.

Traffic control through bilateral cooperation between network operators and peers in P2P networks

The volume of P2P application traffic has increased so much that network-operator-driven traffic control techniques such as P4P for localizing the P2P traffic are recently proposed. The gist of the existing approach is that the network operators provide traffic and topology information as a guidance to peers so that P2P traffic will flow as the network operators intend, thus, realizing unilateral interaction from the network operators to the peers. Thus, this paper proposes bilateral cooperation between the network operators and the peers in P2P networks so that both parties may enjoy even further benefit in reducing cross-domain traffic and in optimizing content download time. In a nutshell, the peers provide peer-level network information to the network operators, which would otherwise require the network operators to perform costly flow-level analysis.We divide measurement work into two parts, letting the peers collect fine-grained traffic information and enabling the network operators to grasp macroscopic information in order to issue a useful guidance to peers including traffic bound missing in the existing work. Our simulation result shows that the bilateral cooperation reduces maximum link utilization of intra links by 34.41%, cross-network traffic by 23.02%, and content download time by 4.65% compared to the existing unilateral interaction.

Trading seeder bandwidth for efficient content distribution in swarming system

Although BitTorrent scales well to support large peer populations, the non-uniform seeder distribution over swarms leads to suboptimal content distribution. In this paper, we propose SeederTrading enabling the over-seeded swarms to trade the seeder bandwidth with the under-seeded swarms to examine the potential improvement through trading seeder bandwidth across swarms. Simulation results show that the under-seeded swarms can improve the content download performance while retaining the performance of over-seeded swarms, which means the content distribution performance and efficiency are improved. We also show that the trading seeder bandwidth across swarms can be done within short time (i.e., 60 seconds in our simulation).

A performance study of network operator-friendly P2P traffic control technique

In the network operator-friendly P2P traffic control technique such as P4P, peers are supposed to select their communication partners by following a guidance issued by the network operator. Thus, the guidance has significant impact on the traffic control. However, detailed performance study of available guidances is missing. Most existing work does not show how they affect intra-domain traffic control in detail while mostly focusing on inter-domain traffic control. In this paper, we try to understand how the guidances affect the intra and inter-domain traffic control for better guidance improving the traffic control. Through simulations, we reveal followings. The performance-based guidance reflecting the networking status shows attractive results in distributing the traffic over intra-domain links and in reducing the cross-domain traffic and the charging volume of inter-domain link compared to the distance-based guidance enforcing simple localization. However, the performance-based guidance shows one limitation that can cause unstable traffic control. To overcome the identified limitation, we propose peer-assisted measurement and traffic estimation approach. Then, we verify our approach through simulations.