networkZONE Products for the week of October 8, 2007
Ikanos Communications Says…
Rapid Rate Adaptation Technology Ensures Always-On Reliability for IPTV and Triple Play
RRA reduces service interruptions, improves system uptime
Ikanos Communications, Inc. has introduced its Rapid Rate Adaptation (RRA) technology, which is designed to optimize the user experience of IPTV and triple play by minimizing noise-induced service interruptions. Sudden, large noise changes on the DSL line can potentially cause dropped connections and interruptions of service. RRA minimizes such link drops by rapidly and dynamically adapting data rates to accommodate the additional noise without dropping the connection, thus improving service availability and the user experience.
“Over the next four years IPTV subscribers will grow at an annual CAGR of 73% reaching 80.3 million by 2011. Carriers cannot afford interruptions to their triple play services,” said Steve Rago, principal analyst of Broadband and Digital Home at iSuppli. “RRA is an enabling technology that can help to minimize service interruptions and, when coupled with other noise mitigation techniques, is the key to delivering robust ‘always on’ advanced broadband services.”
Ikanos’ RRA technology allows service providers to maintain link connectivity, even when signal-to-noise ratio (SNR) margin drops below normal operating levels. The technology enables transceivers to monitor line conditions and dynamically adapt the data rate without interrupting service for retraining, as long as there is adequate bandwidth to absorb the impact of the noise. Ikanos’ solution also uses on-chip QoS capabilities to enhance RRA by prioritizing traffic and quickly communicating the status of the link to other layers in the network.
“Ikanos’ RRA technology provides us with a significant competitive differentiator,” said Hiromitsu Awai, general manager of technical marketing at Sumitomo Electric Networks, Inc. “When sudden, large noise profiles appear on the DSL line, most DSL links are broken, thus interrupting service. RRA ensures that premium services such as triple play and interactive broadband over VDSL2 are not interrupted in such noisy conditions, which results in a significantly improved user experience. RRA is therefore enormously beneficial for carriers that are planning to offer triple play services and compete with cable providers.”
“In today’s highly competitive market, service providers strive to deliver exemplary video services to ensure customer satisfaction and prevent churn,” said Piyush Sevalia, vice president of marketing for Ikanos’ Access Products Group. “By significantly reducing service interruptions, Ikanos’ innovative VDSL2 RRA technology is expected to promote more widespread deployment of IPTV and triple play services worldwide.”
Ikanos’ RRA technology is available in demonstration mode today. Production releases are expected to be available early next year.
EN-Genius Says…
It’s great to see Ikanos understands that raw speed isn’t enough to win the fierce competition for broadband customers that’s raging in North America, Europe and parts of Asia. Last month (September 2007) for example, the intermittent service and random data rates I was experiencing caused me to cancel my ADSL service in favor of Verizon’s FiOS optical network (despite the fact that I hate doing business with a company that willingly participates in unconstitutional warrantless wiretap activity). Since I’m not planning on getting streaming IP-HDTV (I don’t even have cable), the extra 2 Mbit/s Verizon claimed to deliver was not the issue, but the possibility of a service that did not suffer the drop-outs and slow-downs I regularly experienced with the ADSL was. While Ikanos variable-rate adaptation technology cannot cure the boneheaded mismanagement of DNS servers and other network-related foul-ups I’ve experienced with several DSL providers, it will go a long way towards making the last mile a much more reliable link in a carrier’s broadband delivery system.
The product Ikanos is releasing is a software upgrade that works with its current generation of Fx100100-5 and Fx100100S-5 VDSL silicon (reviewed here July 2006). It uses a few simple hardware hooks in the chips to let them employ variable rate adaptation that helps them cope with variable line conditions and interference from adjacent lines.
By taking advantage of the DSP capabilities embedded in their chipsets, they seem to have come up with a good method of dealing with the gradual changes in a cable bundle’s noise floor that occurs as subscribers hop on or off the network as well as the impulse noise, ambient microwave activity and other external sources that can add their share of electronic crud to a line. The software has several weapons in its arsenal that can be deployed depending on the kinds of interference it’s dealing with. Here’s a sampling of some of the tricks it has up its sleeve:
For sudden changes in line noise margins, their rapid-rate adaptation (RRA) technique uses the on-chip signal processor that’s normally used to do the OFDM processing and it can be harnessed to calculate and monitor line SNR, negotiate a new rate and adjust the modem in under 750 ms. RRA uses its own in-band signaling protocol with dedicated tones on the edge of the DSL spectrum (with low data rate and high SNR to ensure a reliable link) to let both transceivers exchange information in real-time. Although RRA is currently a proprietary technology, a modified version is under consideration by the ITU as part of the VDSL cannon of standards. Known in its ITU incarnation as SOS, it’s not identical to Ikanos RRA but they are fairly confident that their current silicon will be able to support the standard when/if it emerges as a standard.
In addition to RRA, you can also add to immunity from sudden noise bursts by leaving some extra margin in the channel instead of trying to cram as many OFDM tones and constellation points on it as possible. This is accomplished by having the chip DSPs to do some extremely fancy channel analysis using a so-called virtual noise technique. During the line probing and handshake activity that happens when a DSL link is established, both the CO and CPE chips work together to analyze the noise conditions and other factors to come up with an estimate of the potential interferers it’s likely to encounter. It then uses these estimates to come up with a simulated interference profile that it injects into the line during the training sequence, causing the modems to use more conservative data rates. The result is a link that’s much less susceptible to problems caused by moderately varying noise with the only downside being that it keeps line rates artificially low.
Another part of the software is designed to overcome the stationary noise sources (stuff like radio stations with fixed spectrum and power) that can sometimes plague DSL using a combination of its own bit loading algorithms, carrier-programmable PSD shaping, and a simple version of the Dynamic Spectral Management (DSM L-1) technology that’s being developed by folks like John Cioffi (one of DSL’s inventors). This inter-channel adaptation capability is also used to support an upstream power backoff scheme that helps drop crosstalk between wire pairs even further.
Ikanos is betting that using this new software to tap the intelligence in their chips will give copper-based VDSL much higher data rates and reliability that allow it to compete with fiber. Given how much of the nation is still served only by copper pairs and the current rate of fiber deployment, this looks like a smart move that will help carriers greatly extend the life of their VDSL infrastructures. In fact, if I’d had something like this on my DSL line, I might not have switched to fiber.
RRA is available for demonstration, with a Beta version in late 2007. Production of the software is scheduled for Q1 of 2008. Fx100100-5 chipsets are in production with pricing at $22.34 per port (10-k port lots) without RRA; adding RRA software takes the price to $25 per port.
Data Sheet Fx100100-5
Data Sheet Fx100100S-5
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