Erwin Alfons Constant Six

Calculation of bending losses in dielectric waveguides using eigenmode expansion and perfectly matched layers

In this letter, we present a different approach to accurately calculate the bending losses in curved dielectric waveguides. It is based on the well-known conformal transformation of the index profile and on vectorial eigenmode expansion, but this time with perfectly matched layer (PML) boundary conditions to accurately model radiation losses. The modal spectrum of these waveguides in the presence of PML is discussed and the method is validated by comparing it to previously published results.

Co-operative Proxy Caching Algorithms for Time-Shifted IPTV Services

The increasing popularity of multimedia streaming applications introduces new challenges in content distribution networks. Streaming services such as video on demand (VoD) or digital television over the Internet (IPTV) are very bandwidth-intensive and cannot tolerate the high delays and poor loss properties of todays Internet. To solve these problems, caching (a sliding segment of popular streams at proxies could be envisaged. This paper presents a novel caching algorithm and architecture for time-shifted television (tsTV) and its implementation using the IETFs real-time streaming protocol (RTSP). The algorithm uses sliding caching windows with sizes depending on content popularity and/or distance metrics. The caches can work in stand-alone mode as well as in co-operative mode. This paper shows that the network load can already be reduced considerably using small diskless caches, especially when using cooperative caching. A brief overview of the functionality of a prototype proxy implementation is presented as well

Proxy caching algorithms and implementation for time-shifted TV services

The increasing popularity of multimedia streaming applications introduces new challenges in content distribution networks (CDNs). Streaming services such as Video on Demand (VoD) or digital television over the Internet (IPTV) are very bandwidth-intensive and cannot tolerate the high start-up delays and poor loss properties of todays Internet. To solve these problems, caching (the initial segment of) popular streams at proxies could be envisaged. This paper presents a novel caching algorithm and architecture for time-shifted television (tsTV) and its implementation, using the IETFs Real-Time Streaming Protocol (RTSP). The algorithm uses sliding caching windows with sizes depending on content popularity and/or distance metrics. The caches can work in stand-alone mode as well as in co-operative mode. This paper shows that the network load can already be reduced considerably using small diskless caches, especially when using co-operative caching. A prototype implementation is detailed and evaluated through performance measurements. Copyright

Dynamic address resolution for enhanced configurability in packet-based TDMA GPONs

Packet-oriented PONs will offer an efficient way to transfer IP traffic, providing at the same time flexible Quality of Service mechanisms to support a great variety of services. To allow provisioning of connections from customer sites to ISP sub-networks across packet-based PONs, it is necessary to correlate the Ethernet MAC address used in the customer terminals to the ISP interfaces and the MAC addresses used in the shared PON system. Automatic address resolution mechanisms are needed to allow for automatic dynamic reconfiguration without manual intervention. The address resolution mechanism impacts on the design of the MAC local address since it should allow for identification of the client interfaces on both ends of the PON. This paper investigates the relevant issues and proposes a solution extending the widely used address resolution protocol.