7/28/2023 0 Comments Moca network diagramVideo packets cannot generally be delayed or dropped and must either have their data rate fully supported at PER 1e-6 or better, or else the video will be degraded. Prioritization, for example using 802.1p, must be used to delay or drop lower priority traffic (typically data traffic). When the aggregate content's data rate exceeds, on a peak or average basis, the home networking data rate, then some content must be delayed and/or dropped. Such buffers must be a fraction of the total allowed delay. Jitter must be smoothed out in buffers at the transmitter and receiver. Voice applications would like to see the delay budget allocated to home networking to be 10 msec or less. Gamers claim to be able to sense delays between 10 and 20 msec. In addition to a PER less than 1e-6, the home network must deliver delay and jitter consistent with the services it carries. This requirement still has not been met by any wireless technology operating in an unlicensed band, nor powerline technology, nor phoneline technology. This must be true for both the subscriber's other devices as well as the neighbor's devices, in order to be reliable and maintainable for a service provider. The home network should deliver a ubiquitous 100 Mbps and not degrade due to other networking devices or typical electronic devices and appliances such as cordless phones, wireless laptops, wireless hot spots, vacuum cleaners, power drills, hair dryers and microwave ovens. Reliability from appliance and neighbor interference requirements A fully coordinated MAC, collision free, is practically a necessity for currently reasonable home networks to achieve this PER for the desired data rates. A home network with potential collision access will have a very difficult time achieving 1e-6 PER with any significant loading of its data rate. When supporting UDP and 1394 protocols there is no request and retransmission of packets above the Link/MAC layer, so that this PER must be constantly maintained at the MAC layer by the home network. The home network should have similar or better performance so as not to degrade viewing. Some systems boost the data rate an additional 30% or more at channel change times in order to fill IP STB buffers and reduce channel change times.ĭigital cable programming is delivered with threshold PER of below 1e-6. Fast forward and reverse increase the peak data rate by a factor of 3 to 5 for continuous looking video, and 1 to 2 for decimated, fast slide show looking video. The vast majority of broadcast content in the USA today is still MPEG2 SDTV. The home network must support the peak data re per stream, for each stream, since independent streams can peak simultaneously. Key requirement drivers: Data rate requirements Next: Key requirement drivers - data rate, reliability, quality of service, bandwidth management Futureproof to higher data rates, up to 400Mbps, or even 1 Gbps.Service provider may open the home network to CE devices or keep it closed.No degradation due to other in-home networking products or general appliances.No degradation due to neighbor's home networking or general appliances.Data rate net (MAC) greater than 100 Mbps.No changes to wiring or splitters or other medium specific devices.Here, then, are the essential requirements: The addition of low jitter and low delay for voice and gaming then covers it. With multiple HDTV and SDTV streams requiring the vast majority of data rate and the best packet error rate (PER), plus security, a home network that can support multiple HDTV streams meets the main requirements. >95% solution, with reasonable remediation for the remaining.The fundamental home networking requirement to have a: Even 100 Mbps Ethernet over cat-5 has been shown not to be a 100% solution with issues including that rate negotiation problems can drop or bounce networks to 10 Mbps, many of the devices being deployed in homes can not in reality support more than 40 to 60 Mbps of real video, consumers can add hubs and collision domain devices to the network, and most devices lack QoS. There does not exist any reasonable home networking solution that provides 100% immediate penetration and ubiquity. The key requirements are reliability and ubiquity, without which deployment is not feasible.
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