Video on demand

Summary

Video on demand (VOD) is a media distribution system that allows users to access to videos, television shows and films without a traditional video playback device and a typical static broadcasting schedule. In the 20th century, broadcasting in the form of over-the-air programming was the most common form of media distribution. As Internet and IPTV technologies continued to develop in the 1990s, consumers began to gravitate towards non-traditional modes of content consumption, which culminated in the arrival of VOD on televisions and personal computers. Unlike broadcast television, VOD systems initially required each user to have an Internet connection with considerable bandwidth to access each system's content. In 2000, the Fraunhofer Institute IIS developed the JPEG2000 codec, which enabled the distribution of movies via Digital Cinema Packages. This technology has since expanded its services from feature-film productions to include broadcast television programmes and has led to low

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Single Sink with non-simultaneous Demand

Joël Clivaz

2010

26.3 A pin- and power-efficient low-latency 8-to-12Gb/s/wire 8b8w-coded SerDes link for high-loss channels in 40nm technology

Harm Cronie, Klaas Lammert Hofstra, Kia Salimi, Mohammad Amin Shokrollahi, Anant Pratap Singh, Christoph Walter

The continuing demand for higher bandwidth in serial interconnects has pushed the symbol rate of differential lanes into the high-insertion-loss region of channels. Multi-level signaling such as differential PAM-4 [1] has been used to mitigate the loss of electrical channels by lowering the signal spectrum. Such an approach suffers from lower SNR tolerance as well as higher susceptibility to crosstalk and ISI as compared to differential signaling (DS). Coded differential approaches have been reported [2] to mitigate ISI. Our approach is a generalization of DS in which ternary values are transmitted on an 8-wire bus. The set of transmitted values belongs to a code consisting of 256 code-words called the 8b8w-code (8-bits-on-8-wires) [3]. The specific correlations in the code-words of the 8b8w-code eliminate transmit common-mode and simultaneous switching output (SSO) noise and allow for detection via self-referencing comparators (unlike PAM-4), which provides additional noise immunity. Compared to DS, the 8b8w-code offers twice the throughput at 50% of the line power. Compared to PAM-4, the code offers better SNR (3dB) at 38% of the line power with enhanced tolerance of ISI and lower crosstalk generation. The design and experimental verification of an 8b8w transceiver in 40nm CMOS is described. Transmission is achieved up to 12Gb/s per wire over 55cm of Rogers with up to 15dB loss.

2014

Cloud computing has been experiencing sharp development over the last years, leading to an increased demand for application migration to the cloud. Cloud providers, in an effort to attract more customers and earn their confidence, offer to tenants the illusion of an isolated network, exposing familiar abstractions. At the same time, creating this illusion poses challenging problems for the providers, as one tenant's traffic may interfere with another's in complicated, unpredictable ways. First, new challenges have arisen in administering access-control rules (ACLs). On the one hand, installing ACLs at the server is incompatible with bare-metal support and introduces unnecessary performance overhead. On the other hand, offloading the most popular ACLs on the limited hardware memory in Top-of-Rack (ToR) switches should not be conducted naïvely, as the existence of wildcard rules presents inter-rule dependencies that must be respected. Second, tenants' demands have evolved beyond requesting hardware resources; for instance, tenants may require bandwidth provisions between their resources or optimized access to a specific cloud service, e.g., a Mail server or a Database. Cloud providers have not adequately adapted to these expanding demands, therefore elevating hardware resources to "first class citizens," as non-hardware constraints are not considered during resource allocation, instead they are applied afterwards. In this thesis we propose two architectures that facilitate cloud providers in managing their shared network resources in a flexible way. First, we demonstrate virtual flow tables, a ToR architecture that handles ACLs using a two-level memory hierarchy. The most popular ACLs are stored in the limited hardware memory, respecting any dependencies between wildcard rules, while the ToR's supervisor engine maintains access to the entire ACL rule-set. Second, we present a two-tiered architecture for scheduling cloud resources, consisting of a resource-agnostic scheduling layer and a resource-specific enforcement layer. Network resources and constraints are taken into consideration during resource scheduling, instead of afterwards, while resource provisioning, as well as general network-management policies, are delegated to the resource-specific tier.

EPFL2018