The end user quality of experience (QoE) of content delivered over a radio network is (mainly) influenced by the radio parameters in the radio access net‐work. This paper will present a QoE model for video delivered over a radio network (e.g., Long Term Evolution (LTE)) using HTTP (Hypertext Transfer Protocol) adaptive streaming (HAS). The model is based on experiments performed in the context of the Next Generation Mobile Networks (NGMN) project P‐SERQU (Project Service Quality Definition and Measurement). In the first phase, a set of representative HAS profiles were selected based on a lab experiment where scenarios with typical radio impairments (fading, signal‐to‐interference‐plus‐noise ratio, round trip time and competing traffic) were investigated in a test network. Based on these HAS profiles, video files were prepared by concatenating chunks of the corresponding video quality. In a second phase, these video files were downloaded, viewed, and rated by a large number of volunteers. Based on these user scores a mean opinion score (MOS) was determined for each of the video files, and hence, the HAS profiles. Several QoE models that predict the MOS from the HAS profile have been analyzed. Using the preferred QoE model, a range of MOS values can be obtained for each set of initial radio impairments. It is argued that a QoE model based on the radio parameters is necessarily less accurate than a QoE model based on HAS profiles and an indication is given of how much the performance of the former is less than the latter. © 2014 Alcatel‐Lucent.

In order to cope with the rapidly increasing video traffic (both downloaded and streamed) during which the user reads or thinks about the content just downloaded-in the former, the content is consumed (i.e., watched, heard) as it is downloading. It follows that video cannot rely on statistical multiplexing as much as data can, and this, consequently, puts even more stress on the network. Both types of services (i.e., data and video) can benefit from a content distribution network (CDN). The principle of a CDN is that objects that require a large (and sustained) bit rate to be delivered are cached in a CDN point of presence (PoP) close to the end user. For data services this decreases the download time and hence improves the user's quality of experience. Moreover, CDNs also offload traffic requests from the origin servers and, hence, provide

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Of all the services offered over a worldwide public network, digital videobased

Application Enablement. Location services have been among the first to be utilized in Application Enablement deployments; three papers in this issue are focused on location services. The most significant area represented, with nine papers, is content delivery/ transport. One interpretation of this predominance could be that this area has the most potential. The growth in smartphone usage maps well to maturing options for content delivery control. However, future opportunities for payment services, personalization services, and perhaps some heretofore unknown services cannot be discounted. Payment service, a concept for a content recommendation service, and support for developer communities also each have a corresponding paper in this issue.The following sections preview the papers and letters in this issue. We hope it serves as a good guide to getting the most out of the variety of new work in this area represented in this issue. Location ServicesLocation services can range from requesting location information for a buddy or service, to having information downloaded based on the user's location, to advertising and coupon applications offering information to users in a specific region. In "A Unified Location Sharing Service With End User Privacy Control," Xie and Wang provide a good overview of location mechanisms, services, and standards as a preface to the core of the paper, which introduces a Bell Labs prototype location service. This prototype service is similar to existing location services in that it provides a Web interface to share location information, but it has two innovations: a sophisticated and IntroductionApplication enablement opens the door to higher value experiences for users and higher revenue opportunities for providers of communication services. The concept is to expose elements that have value-whether information or control or a task/ service-to application developers for the purpose of enabling richer applications, which can be Web-based, mobile handset-based, or a combination.We are witnessing a rapid increase in data traffic from applications and end user devices delivered overthe-top. Application enablement allows network operators to be part of the value chain by providing services to enhance these applications with improved end user experiences. These services fall into two categories. Firstly, there are services to expose mechanisms that improve the delivery and distribution of traffic from the application (e.g., pipes for guaranteed quality of service (QoS)). Secondly, there are services to expose network-based information (e.g., location, identity). Access to traditional messaging services, address books, and secure payment mechanisms can also be made available to application developers.An important factor is the ease with which new applications can be brought on line. This can be accomplished by providing application programming interfaces (APIs) allowing application and content providers (ACPs) to build and deploy new applications quickly. This mechanism frees application develope...