Cross-layer design for improved QoE in content distribution networks

In this article, we present the challenges faced by communication networks in delivering high-quality video content to mobile and stationary devices serving CDN users. Starting with Content Distribution Network types, an overview is given in order to show how this field develops on the research as well as on the commercial side. Research or academic CDNs, new aspects and features are tested to add scalability and functional features to known systems and prototypes. On the other hand, commercial CDNs serve alternatively customers that use broadcasting services. We also show which performance metrics such as quality of experience (QoE) and time to first byte (TTFB) best capture the dynamics of traffic and services in CDNs. The core of this paper is our proposed network architecture for CDN providers/operators. The architecture combines video multicast optimized trees and cross-layer coordination between the physical DWDM layer (L1) and network layer (L3) for achieving higher efficiency and lower latency values for live streaming and on demand (VoD) video. Due to the pilot implementation of the presented concept being limited in scale, we use simulations in order to perform proof-of-concept on a sufficiently large environment. Results show that there is a strong correlation between the TTFB and QoE metrics with the former taking on values as low as 75 msec in a national 3-tier network. Ultimately, our aim is to familiarize readers with the field of CDNs and also to help them see how network research especially in the architectural, protocol design, and cross-layer design help bring applications in this field to a quality level acceptable by a large community of users.In this article, we present the challenges faced by communication networks in delivering high-quality video content to mobile and stationary devices serving CDN users. Starting with Content Distribution Network types, an overview is given in order to show how this field develops on the research as well as on the commercial side. Research or academic CDNs, new aspects and features are tested to add scalability and functional features to known systems and prototypes. On the other hand, commercial CDNs serve alternatively customers that use broadcasting services. We also show which performance metrics such as quality of experience (QoE) and time to first byte (TTFB) best capture the dynamics of traffic and services in CDNs. The core of this paper is our proposed network architecture for CDN providers/operators. The architecture combines video multicast optimized trees and cross-layer coordination between the physical DWDM layer (L1) and network layer (L3) for achieving higher efficiency and lower latency values for live streaming and on demand (VoD) video.Due to the pilot implementation of the presented concept being limited in scale, we use simulations in order to perform proof-of-concept on a sufficiently large environment. Results show that there is a strong correlation between the TTFB and QoE metrics with the former taking on values as low as 75 msec in a national 3-tier network. Ultimately, our aim is to familiarize readers with the field of CDNs and also to help them see how network research especially in the architectural, protocol design, and cross-layer design help bring applications in this field to a quality level acceptable by a large community of usersGodkänd; 2013; 20130330 (karand)NIMO - Nordic Interaction and Mobility Research Platfor