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networkZONE Products for the week of January 7, 2008
DS2 Says…
DSS9101/7800: Chipset Delivers 200 Mbit/s Over Home, Office and Industrial Electrical Wiring
DS2 has unveiled Aitana, its state-of-the-art integrated 200 Mbits/s chipset, the powerline industry's most innovative and cost-efficient design that further integrates external components into the silicon to deliver the best consumer multi-media experience.
Each Aitana chipset has an embedded processor, an Ethernet bridge, an IP stack, a powerful API (Applications Program Interface) and value-added software capabilities which make it a self-contained, flexible, adaptable, programmable and very easy to embed robust powerline solution. The size, performance and price-point of DS2´s new Aitana powerline chipsets are forging the path for reliable embedded networking in today's most popular consumer electronics such as XDSL gateways, computers, televisions, set-top boxes and games consoles.
Aitana technology has been designed with Quality of Service protocols in mind, so that the chipset manages multiple priority levels within the network. Data, VoIP, IPTV and video on-demand services are all assigned sufficient network resources to operate simultaneously.
“DS2 was the first to bring 200 Mbits/s powerline networking to global consumers. Now with Aitana and through the addition of new software features and more aggressive integration especially on the analog front end, we are again the first to develop the most integrated chipset solution for high-performance, low-cost networking applications” commented Victor Dominguez, Director of Sales, DS2.
In terms of technology readiness third party tests by major service providers show that DS2 products are at a level of maturity that supports prime time multi-media applications Major operators including British Telecom, Telefónica, Telecom Italia, Telia Sonera and others deploy DS2-based 200Mbits/s technology in their commercial IPTV services. Mr Dominguez added,“ with Aitana we have focused on reducing costs and developing applications that consumers and businesses alike will really benefit from.
This new DS2 Aitana chipset that includes a powerful API makes the process of developing lower cost solutions to deliver secure and uninterrupted IPTV, VoIP and video streaming throughout the home much easier for organizations around the world.” “Making Moore's Law a self-fulfilling prophesy we have reduced the component count down to a minimum, and embedded many more of those components onto our silicon including memory, filters, drivers, and lower cost power supplies. This not only retains the high performance it also reduces cost and makes the device easier to integrate into a wide range of consumer products, all of which are connected to powerline networks today. The chipset is based on UPA DHS standards, which will help to make it future-proof, as the UPA is highly cooperative with ETSI and the IEEE’s developments of international standards for powerline communications,” commented, Jose Calero, Director of Technology, DS2.
The new Aitana chipset is fully compliant with the Universal Powerline Association’s (UPA) Digital Home Standard (DHS) for compatibility with the world’s best selling and most widely adopted 200Mbits/s powerline technology. This ensures coexistence and interoperability with other DHS-compliant in-home and access products requiring a share of bandwidth.
Technical Information
The Aitana chipset (DSS9101 and DSS7800) has UPA DHS compliant MAC and PHY layers, with a powerful embedded media network processor. The technology includes an 802.1D Ethernet bridge with packet detect and redirect capabilities – that can learn up to 64 MACs and discover the network topology – and a 32-bit microcontroller with an embedded TCP/IP networking stack, allowing data packets to be examined, prioritised and forwarded. The unique TDMA based MAC enhances uninterrupted video-streaming, and is today the only solution able to handle video multi-streaming, neighbour networks and multiple VLANs efficiently by reducing the congestion on the network often associated with CSMA systems.
The analog component (the DSS7800), drives the integration beyond the state-of-the-art, including filtering and power devices, it includes a 48 pin QFN package that runs off a single 5V supply, with individual power down control for each block of the transmission. The highly integrated two-chip solution has configurable frequency notching to support global regulatory compliance. It has hardware-based encryption at strengths of 128-bit AES, 256-bit AES and 3-DES. The chipset includes SPI, GPIO, TDM/I2S and UART interfaces.
EN-Genius Says…
Even though a third of the DS2 Aitana chip set's 200 Mbit/s capacity is eaten up by network overhead and you won’t get all of the remaining 130-odd Mbit/s in many real-world environments, it still delivers more than enough reliable bandwidth to make it a great way to get data and streaming multimedia around a home or small office. That’s because the folks at DS2 have used a combination of powerful techniques at the MAC and PHY layers to deliver as much capacity as is possible over the harsh powerline environment in a reliable manner. Equally important, they have provided their chips with the capability to make sure their bandwidth is efficiently managed and can deliver the tight latency control required for multimedia services.
With all the other established networking technologies available, it’s hard to get excited about powerline data – until you start to think about the many real-world applications where Wi-Fi is impractical or inadequate to the task. I have nothing against 802.11n, but if I was going to be routinely streaming HD video across my house I’d want it done over a hard wire. Most US broadband carriers feel the same way and are using MOCA or some other coax technology to get their data from their CPE to the desired rooms, but that usually involves a costly truck roll – and in many cases (including my house when I recently got Verizon FIOS), running new wires. Powerline would seem like the obvious alternative to running new wires but, until recently, the lossy, noisy characteristics of the wires behind your walls limited data rates to a few Mbit/s at best. This has changed recently as DS2 and several other manufacturers have developed products that work better in this tough environment than I’d have ever expected they could.
 The DS2 Aitana two-device chipset consists of the DSS7800 AFE and the DSS9101 digital front end/ MAC/application processor. The new AFE integrates line drivers and filters that were external components in earlier products. DS2 says that its line drivers are adequate for home networking but can be boosted with an external amp for demanding industrial applications or long-haul public utility networks. Its companion digital front end uses a DSP-like core to perform the DMT processing and hardware cores for the lower-level MAC functions.
The chip also has a 160 MHz Tensillica processor to handle higher-level protocol and bandwidth management tasks. Customers can take advantage of unused processing power to customize application software; or write their own applications; or support remote management protocols such as SNMP or TR069. In many CPE applications it can eliminate the need for an external host processor. Power consumption for the AFE is 1.7 W in transmit with its line drivers active, 685 mW in receive mode, and 15 mW in standby mode. The baseband/MAC/controller draws 1.35 W maximum.
 The chipset uses a 1536-carrier OFDM scheme operating at 2 - 32MHz and a token-based TDMA MAC. While the OFDM scheme has many similarities to the one used by VDSL, it has several unique twists that optimize it to the peculiar channel impairments and noise sources found in the power wires that lie behind your outlet. For example, each OFDM tone bit loading (0 - 10 bits) is adjusted on a per-carrier basis using an estimate of the channel’s SNR – updated on a per-frame basis. This is calculated using information gathered from each data frame and fine tuned using information acquired from special frames that are transmitted every few seconds.
The transceiver also probes the line to identify any permanent or recurring noise sources. Depending on how strong an interferer is, the transmitter can reduce the bit loading or even turn off the tones that lie within the noise source spectrum. It’s even smart enough to synchronize itself to periodic bursts from switch-mode power supplies or other cyclic events so that it only transmits affected tones in the time slots where the noise is at a minimum. The same intelligence and per-carrier power control allows it to create arbitrary frequency notches to fit power spectral masks for any country or turn off the tones that fall within amateur radio bands.
At the data transport layer, incoming Ethernet frames are broken down or concatenated as necessary and encapsulated with a powerline frame header that includes address, content type/priority, and a block identifier to maintain proper sequence. The header also contains error detection/correction information which uses a combination of Reed-Solomon and 4-D Trellis coding (future versions may use LDPC techniques). Packet size is adjusted according to line conditions, with packets being shortened as line conditions grow worse. Protocol and error correction overhead varies but is around 32% in best case – significantly better than Wi-Fi which typically spends 50% of its advertised bandwidth handshaking, error checking, and managing the channel.
The token-based MAC divides the available bandwidth into deterministic time slots that can support latency-sensitive telephony and video applications, even on heavily-used networks. The smart MAC adjusts its token scheme to varying load conditions so that nodes which do not use their full time slot duration turn back the token early to free up the bandwidth. Time slot length can be varied according to the application to trade off between more efficient long transfers and shorter, lower-latency transfers for VoIP or streaming video. If you need to support multiple networks on the same wiring plant, the same time-slotting mechanism can also be used to sub-divide the band into several independent channels.
DS2 says that their token-based time-slotting system is especially useful for managing latency in networks with repeaters. Links which require 2 hops or more are allocated longer time slots to allow communication with remote node.
Actual performance of the powerline transceiver is very dependent on the channel loss and noise levels it encounters. It can support around 120 Mbit/s with 30 dB worth of channel loss, around 100 Mbit/s at 50 dB and around 25 Mbit/s at 70 dB. DS2 research indicates that channel losses in a typical house range between 30 dB and 60 dB, with most around 50 dB. Adding a noisy switched-mode cell phone charger to the adjacent outlet socket can add 20 - 30 dB to the noise floor, creating a significant degradation on data rates. The performance degradation due to noisy power supplies and other non-obvious noise sources is one of the only serious problems I can see with DS2 technology.
On the whole, DS2 seems to have come up with a very viable solution for broadband powerline networking which is more reliable than wireless technologies and does not require any new wires to be installed. The $15 volume pricing for the chip set is a tad high compared to the many Wi-Fi solutions on the market today but the fact that it can eliminate a separate host processor takes some of the sting out of the cost differential. I’d also speculate that any additional CPE costs are repaid many times over by allowing consumers to install their own broadband network without the need for an expensive service call.
My only other concern is whether the system’s tendency to lose capacity in the presence of external noise will require more service calls than broadband carriers would like or otherwise limit its acceptance in consumer applications Given the wide performance margins the chipset delivers, delivering a one or two HD video streams, VoIP and plain old data and should not be a problem in all but a few worst-case scenarios. Nevertheless, nothing’s certain until there’s more data back from the field.
The Aitana chipset is in production with volume pricing under $15.
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