Minimizing server throughput for low-delay live streaming in content delivery networks

Rosenberg

IEEE J. Select. Areas Commun.

et al. 2014

Self Cite

Abstract-The growth of Internet video traffic imposes a severe capacity problem in today's Content Delivery Network (CDN). Rate-adaptive streaming technologies, such as the Dynamic Adaptive Streaming over HTTP (DASH) standard, reinforces this problem in the core CDN infrastructure since delivering one video means delivering multiple representations for an aggregated bit-rate that is commonly over 10 Mbps. In this paper, we explore better trade-offs between CDN infrastructure cost and Quality of Experience (QoE) of the end-users for live broadcast video streaming applications. We consider in particular underprovisioned CDN networks, our goal being to maximize the QoE for the population of heterogeneous end-users despite the lack of resources in the intermediate CDN equipments. We show that previous theoretical models based on elastic bit-rates do not fit for this context. We propose a user-centric discretized streaming model where the satisfaction of end-users is related to the context and where a stream has to be either delivered in its entirety, or not delivered at all. We first formulate an Integer Linear Program (ILP) that achieves the optimal delivery through a multi-tree delivery overlay. The evaluation of the ILP shows the benefits of this model. We then design a practical system by revisiting the three main algorithms implemented in CDN: userto-server assignment, content placement and content delivery. At last, we use a realistic trace-driven large-scale simulator to study the performances of our system. In particular, we show that the population of users is reasonably well served (three quarters of the population do not experience degradation) even when the CDN infrastructure experiences a severe underprovisioning (less than half of the required infrastructure).

Section: B Live Video Streaming In a Cdnmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal Delivery of Rate-Adaptive Streams in Underprovisioned Networks

Rosenberg

IEEE J. Select. Areas Commun.

et al. 2014

Self Cite

“…Like all previous works [3,4,11], we consider that the outbound capacity of equipment is the only constraint.…”

Section: A Live Video Streaming In a Cdnmentioning

confidence: 99%

“…The previous theoretical works related to live streaming in CDNs have highlighted the main characteristics of these networks, in particular the 3-tier topology (origin servers, reflectors and edge-servers) [2], and the restriction on the upload capacity of the equipment [3,4]. The goal of these previous works is to reduce the transmission cost of video delivery.…”

Section: Introductionmentioning

confidence: 99%

Fast Near-Optimal Algorithm for Delivering Multiple Live Video Channels in CDNs

2013 22nd International Conference on Computer Communication and Networks (ICCCN)

2013

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Abstract-Content Delivery Networks (CDNs) are confronted with a sharp increase in traffic related to live video (channel) streaming. Previous theoretical models that deal with streaming capacity problems do not capture the emerging reality faced by today's CDNs. In particular, a modern CDN has to deliver a large set of independent non-divisible data streams, which need to be either delivered in whole, or not delivered at all. This constraint is not addressed in previous works.In this paper we identify a new, discretized streaming model for live video delivery in CDNs. For this model we formulate a general optimization problem and show that it is NP-complete. Then we study a practical scenario that occurs in real CDNs. We present a fast, easy to implement, and near-optimal algorithm with performance approximation ratios that are negligible for large network. To our knowledge, these are the first results for the discretized streaming model, and have both practical and theoretical importance in a topic of growing criticality.

“…Several techniques have been developed for the construction of an overlay for one live channel over CDNs. In particular, multi-tree overlays that leverage rateless codes (e.g., Raptor codes [8]) enable video stream delivery with optimal bandwidth utilization [7], [9], [10]. This solution however performs well for one channel while the traffic that a CDN should carry for a platform like twitch.tv consists of a large number of simultaneous channels.…”

mentioning

confidence: 99%

Joint Optimization for the Delivery of Multiple Video Channels in Telco-CDNs

Zhou

IEEE Trans. Netw. Serv. Manage.

et al. 2015

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Abstract-The delivery of live video channels for services such as twitch.tv leverages the so-called Telco-CDN-Content Delivery Network (CDN) deployed within the Internet Service Provider (ISP) domain. A Telco-CDN can be regarded as an intra-domain overlay network with tight resources and critical deployment constraints. This paper addresses two problems in this context: (1) the construction of the overlays used to deliver the video channels from the entrypoints of the Telco-CDN to the appropriate edge servers; and (2) the allocation of the required resources to these overlays. Since bandwidth is critical for entrypoints and edge servers, our ultimate goal is to deliver as many video channels as possible while minimizing the total bandwidth consumption. To achieve this goal, we propose two approaches: a two-step optimization where the optimal overlays are firstly computed, then an optimal resource allocation based on these pre-computed overlays is performed; and a joint optimization where both optimization problems are simultaneously solved. We also devise fast heuristic algorithms for each of these approaches. The conducted evaluations of these two approaches and algorithms provide useful insights into the management of critical Telco-CDN infrastructures.