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96 results on '"Lee, Jack Y. B."'

1. Device-to-Device Load Balancing for Cellular Networks

Author

Deng, Lei, He, Yinghui, Zhang, Ying, Chen, Minghua, Li, Zongpeng, Lee, Jack Y. B., Zhang, Ying Jun, and Song, Lingyang

Subjects
Computer Science - Networking and Internet Architecture
Abstract

Small-cell architecture is widely adopted by cellular network operators to increase network capacity. By reducing the size of cells, operators can pack more (low-power) base stations in an area to better serve the growing demands, without causing extra interference. However, this approach suffers from low spectrum temporal efficiency. When a cell becomes smaller and covers fewer users, its total traffic fluctuates significantly due to insufficient traffic aggregation and exhibiting a large "peak-to-mean" ratio. As operators customarily provision spectrum for peak traffic, large traffic temporal fluctuation inevitably leads to low spectrum temporal efficiency. In this paper, we advocate device-to-device (D2D) load-balancing as a useful mechanism to address the fundamental drawback of small-cell architecture. The idea is to shift traffic from a congested cell to its adjacent under-utilized cells by leveraging inter-cell D2D communication, so that the traffic can be served without using extra spectrum, effectively improving the spectrum temporal efficiency. We provide theoretical modeling and analysis to characterize the benefit of D2D load balancing, in terms of total spectrum requirements of all individual cells. We also derive the corresponding cost, in terms of incurred D2D traffic overhead. We carry out empirical evaluations based on real-world 4G data traces to gauge the benefit and cost of D2D load balancing under practical settings. The results show that D2D load balancing can reduce the spectrum requirement by 25% as compared to the standard scenario without D2D load balancing, at the expense of negligible 0.7% D2D traffic overhead.

Published
2017

5. Adaptive Video Streaming With Automatic Quality-of-Experience Optimization

Author

Zhang, Guanghui, Zhang, Jie, Liu, Yan, Hu, Haibo, Lee, Jack Y. B., and Aggarwal, Vaneet

Abstract

Video streaming has grown tremendously in recent years and it is now one of the main applications on the Internet. Due to the networks’ inherent bandwidth fluctuations, various rate-adaptive streaming algorithms have been developed to compensate for such fluctuations to improve Quality-of-Experience (QoE). However, in practice, the preference for QoE typically differs significantly across different viewers and there is no systematic way so far to comprehensively incorporate different sets of conflicting QoE objectives into the algorithm design. Thus, it is not surprising that the QoE performance achieved by the existing algorithms is in fact far from optimal. This work aims at attacking the heart of the problem by developing a novel framework called Post Streaming Quality Analysis (PSQA) that can maximize the QoE under any preference through automatically tuning the adaptation logic of the streaming algorithms. Evaluation results show that the QoE achieved by PSQA is substantially better than the existing approaches and in some scenarios even close to optimal. Moreover, PSQA can be readily implemented into real streaming platforms, offering a practical and reliable solution for high-performance streaming services.

Published
2023
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24. Buffer Management and Dimensioning for a Pull-Based Parallel Video Server

Author

Lee, Jack Y. B.

Subjects
Buffering (Computers) -- Methods, Video equipment -- Design and construction, Scalable processor architecture -- Evaluation, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Recently, there has been a trend toward designing video-on-demand systems using parallel-server architectures. By exploiting server-level parallelism, researchers can break through the performance limit of a single server, while keeping the system cost low by leveraging on commodity hardware platforms. A number of studies have demonstrated the feasibility of building parallel video servers around the client-pull architecture and one can even incorporate data redundancy into the system to sustain server-level failures. However, due to randomness of request arrivals and server processing time, dimensioning the server resource requirement is often difficult. This paper tackles the problem of buffer management and dimensioning for such a pull-based parallel video server. Using a generic buffer-pool model with worst-case analysis, upper bounds on the server buffer requirement are derived for a parallel-server design with multiple disks per server. The obtained bounds are independent of placement policy, video bit-rate, disk-scheduling discipline, and even number of servers in the system, making it applicable to a wide range of server designs. The analytical results also proved that the scalability of this pull-based server design will not be limited by the server buffer requirement. Index Terms--Buffer management, parallel video server, scalability, server design, system dimensioning, video-on-demand.

Published
2001

25. Supporting Server-Level Fault Tolerance in Concurrent-Push-Based Parallel Video Servers

Author

Lee, Jack Y. B.

Subjects
Fault tolerance (Computers) -- Testing, Video equipment -- Product development, File servers -- Testing, Pay-per-view television -- Product development, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Parallel video servers have been proposed for building large-scale video-on-demand (VoD) systems from multiple low-cost servers. However, when adding more servers to scale up the capacity, system-level reliability will decrease as failure of any one of the servers will cripple the entire system. To tackle this reliability problem, this paper proposes and analyzes architectures to support server-level fault tolerance in parallel video servers. Based on the concurrent push architecture proposed earlier, this paper tackles three problems pertaining to fault tolerance, namely redundancy management, redundant data transmission protocol, and real-time fault masking. First, redundant data based on erasure codes are introduced to video data stored in the servers, which are then delivered to the clients to support fault tolerant. Despite the success of distributed redundancy striping schemes such as RAID-5 in disk array implementations, we discover that similar schemes extended to the server context do not scale well. Instead, we propose a redundant server scheme that is both scalable, and with lower total server buffer requirement. Second, two protocols are proposed to manage the transmission of redundant data to the clients, namely forward erasure correction which always transmits redundant data, and on-demand correction which transmits redundant data only after a server failure is detected. Third, to enable ongoing video sessions to maintain nonstop video playback during failure, we propose using fault masking at the client to recompute lost video data in real-time. In particular, we derive the amount of client buffer required so that nonstop, continuous video playback can be maintained despite server failures. Index Terms--Concurrent push, fault tolerance, parallel video server, scheduling algorithm, server failure, server push, video-on-demand.

Published
2001

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