Bill Krogfoss

Analytical Model for Hierarchical Cache Optimization in IPTV Network

In an IPTV network, video on demand and other video services generate large amount of unicast traffic from video hub office (VHO) to subscribers and, therefore, require additional bandwidth and equipment resources in the network. To reduce this traffic and overall network cost, a portion of the video content (the most popular titles) may be stored in caches closer to subscribers, e.g., in a digital subscriber line access multiplexer (DSLAM), a central office (CO), or in an intermediate office (IO). The problem becomes to minimize cost by optimizing cache memory placement and amount. We present an analytical model of hierarchical cache optimization. This model depends on several basic parameters: traffic volume, cache hit rate as a function of memory size, topology (i.e. number of DSLAMs, service routers at CO, service switches at IO locations), and cost parameters. Some reasonable assumptions about a network cost structure and a hit rate function allow us to obtain an analytically optimal solution for the problem. We then analyze the factors that affect this solution.

Impact of consumer traffic growth on mobile and fixed networks: Business model and network quality impact

The growth of Internet Protocol (IP) traffic per subscriber on fixed and mobile networks is growing at phenomenal rates of 30 percent to 100 percent per annum due to the development and use of manifold new web applications and services. However, the average revenue per subscriber to broadband access service providers is flat for both wireline and wireless. Thus it would appear that there is an essential economic conundrum in which the investment in infrastructure required to support continued innovation and expansion in access to such web services by more users on more devices can no longer be financially supported by the network providers, if these providers are to remain fiscally viable according to any normal economic metric. In this paper, we investigate the validity of this argument by comparing the cost of the network expansion required to match the traffic growth with the revenue potential projected by simple extrapolation from current trends. We find that indeed this dichotomy is real, with trends indicating the cost of network expansion per subscriber may exceed revenue per subscriber in the next two to three years. We propose a solution based on “managed services” in which subscribers are offered a higher quality of service for content and applications they value, and charged an appropriate fee for this enhanced service treatment. We also advocate a model where the selection of services for enhanced delivery is at the discretion of the subscriber and their willingness to pay, so that end user satisfaction or quality of experience is the driving force in the network evolution and associated economics.

Dimensioning of active broadcast channels in access IPTV network

The number of active broadcast TV channels between central office and access node and its sensitivity to channel popularity distribution and to the number of set top boxes simultaneously tuned to broadcast channels is investigated.

U-turn caching optimization in IPTV networks

In an IPTV network, a large amount of unicast traffic from the Video Head Office (VHO) to subscribers requires significant BW and equipment resources in the network. Caching of video content allows reduction of bandwidth and IPTV network cost. In this paper, we consider a caching architecture in which part of the content is cached at the edge of the network (e.g., at DSLAMs), and the remaining part is stored in server(s) at the VHO. We assume that the community of subscribers subtended at each cache location (DSLAM) may have unique interests. Therefore, the list of cached items is customized for each cache location (e.g., individual DSLAM), and different cache locations should store different content. We consider U-turn caching where titles cached at a given DSLAM may serve the requests of subscribers that are subtended not only at this DSLAM but also from those subtended at neighboring DSLAMs. We discuss how the U-turn caching architecture allows increased cache effectiveness (hit rate) by sharing cache resources in the access nodes (DSLAMs).