VDSL2 vectoring explained
Several system vendors including Adtran, Alcatel-Lucent and ZTE have announced vectoring technology that boosts the performance of very-high-bit-rate digital subscriber line (VDSL2) broadband access technology. Vectoring is used to counter crosstalk - signal leakage between the telephony twisted wire pairs that curtails VDSL2's bit rate performance – as is now explained.
Technology briefing
There is a large uncertainty in the resulting VDSL2 bit rate for a given loop length. With vectoring this uncertainty is almost removed
Paul Spruyt, Alcatel-Lucent
Two key characteristics of the local loop limit the performance of digital subscriber line (DSL) technology: signal attenuation and crosstalk.
Attenuation is due to the limited spectrum of the telephone twisted pair, designed for low frequency voice calls not high-speed data transmission. Analogue telephony uses only 4kHz of spectrum, whereas ADSL uses 1.1MHz and ADSL2+ 2.2MHz. The even higher speed VDSL2 has several flavours: 8b is 8.5MHz, 17a is 17.6MHz while 30a spans 30MHz.
The higher frequencies induce greater attenuation and hence the wider the spectrum, the shorter the copper loop length over which data can be sent. This is why higher speed VDSL2 technology requires the central office or, more commonly, the cabinet to be closer to the user, up to 2.5km away - although in most cases VDSL2 is deployed on loops shorter than 1.5km.
The second effect, crosstalk, describes the leakage of the signal in a copper pair into neighbouring pairs. “All my neighbours get a little bit of the signal sent on my pair, and vice versa: the signal I receive is not only the useful signal transmitted on my pair but also noise, the contributed components from all my active VDSL2 neighbours,” says Paul Spruyt, xDSL technology strategist at Alcatel-Lucent.
Typical a cable bundle comprises several tens to several hundred copper pairs. The signal-to-noise ratio on each pair dictates the overall achievable data rate to the user and on short loops it is the crosstalk that is the main noise culprit.
Vectoring boosts VDSL2 data rates to some 100 megabits-per-second (Mbps) downstream and 40Mbps upstream over 400m. This compares to 50Mbps and 20Mbps, respectively, without vectoring. There is a large uncertainty in the resulting VDSL2 bit rate for a given loop length. "With vectoring this uncertainty is almost removed," says Spruyt.
Vectoring
The term vectoring refers to the digital signal processing (DSP) computations involved to cancel the crosstalk. The computation involves multiplying pre-coder matrices with Nx1 data sets – or vectors – representing the transmit signals.
The crosstalk coupling into each VDSL2 line is measured and used to generate an anti-noise signal in the DSLAM to null the crosstalk on each line.
To calculate the crosstalk coupling between the pairs in the cable bundle, use is made of the ‘sync’ symbol that is sent after every 256 data symbols, equating to a sync symbol every 64ms or about 16 a second.
Each sync symbol is modulated with one bit of a pilot sequence. The length of the pilot sequence is dependent on the number of VDSL2 lines in the vectoring group. In a system with 192 VDSL2 lines, 256-bit-long pilot sequences are used (the next highest power of two).
Moreover, each twisted pair is assigned a unique pilot sequence, with the pilots usually chosen such that they are mutually orthogonal. “If you take two orthogonal pilots sequences and multiply them bit-wise, and you take the average, you always find zero,” says Spruyt. "This characteristic speeds up and simplifies the crosstalk estimation.”
A user's DSL modem expects to see the modulated sync symbol, but in reality sees a modulated sync symbol distorted with crosstalk from the modulated sync symbols transmitted on the neighbouring lines. The modem measures the error – the crosstalk – and sends it back to the DSLAM. The DSLAM correlates the received error values on the ‘victim’ line with the pilot sequences transmitted on all other ‘disturber’ lines. By doing this, the DSLAM gets a measure of the crosstalk coupling for every disturber – victim pair.
The final step is the generation of anti-noise within the DSLAM.
This anti-noise is injected into the victim line on top of the transmit signal such that it cancels the crosstalk signal picked up over the telephone pair. This process is repeated for each line.
Source: Alcatel-Lucent
VDSL2 uses discrete multi-tone (DMT) modulation where each DMT symbol consists of 4096 tones, split between the upstream (from the DSL modem to the DSLAM) and the downstream (to the user) transmissions. All tones are processed independently in the frequency domain. The resulting frequency domain signal including the anti-noise is converted back to the time domain using an inverse fast Fourier transform.
The above describes the crosstalk pre-compensation or pre-coding in the downstream direction: anti-noise signals are generated and injected in the DSLAM prior to transmission of the signal on the line.
For the upstream, the inverse occurs: the DSLAM generates and adds the anti-noise after reception of the signal distorted with crosstalk. This technique is known as post-compensation or post-coding. In this case the DSL modem sends the pilot modulated sync symbols and the DSLAM measures the error signal and performs the correlations and anti-noise calculations.
Challenges
One key challenge is the amount of computations to be performed in real-time. For a fully-vectored 200-line VDSL2 system, some 2,600 billion multiply-accumulates per second - 2.6TMAC/s - need to be calculated. A system of 400 lines would require four times as much processing power, about 10TMAC/s.
Alcatel-Lucent’s first-generation vectoring system that was released end 2011 could process 192 lines. At the recent Broadband World Forum show in October, Alcatel-Lucent unveiled its second-generation system that doubles the capacity to 384 lines.
For larger cable bundles, the crosstalk contributions from certain more distant disturbers to a victim line are negligible. Also, for large vectoring systems, pairs typically do not stay together in the same cable but get split over multiple smaller cables that do not interfere with each other. “There is a possibility to reduce complexity by sparse matrix computations rather than a full matrix,” says Spruyt, but for smaller systems full matrix computation is preferred as the disturbers can’t be ignored.
There are other challenges.
There is a large amount of data to be transferred within the DSLAM associated with the vectoring. According to Alcatel-Lucent, a 48-port VDSL2 card can generate up to 20 Gigabit-per-second (Gbps) of vectoring data.
There is also the need for strict synchronization – for vectoring to work the DMT symbols of all lines need to be aligned within about 1 microsecond. As such, the clock needs to be distributed with great care across the DSLAM.
Adding or removing a VDSL2 line also must not affect active lines which requires that crosstalk is estimated and cancelled before any damage is done. The same applies when switching off a VDSL2 modem which may affect the terminating impedance of a twisted pair and modify the crosstalk coupling. Hence the crosstalk needs to be monitored in real-time.
Zero touch
A further challenge that operators face when upgrading to vectoring is that not all the users' VDSL2 modems may support vectoring. This means that crosstalk from such lines can’t be cancelled which significantly reduces the vectoring benefits for the users with vectoring DSL modems on the same cable.
To tackle this, certain legacy VDSL2 modems can be software upgraded to support vectoring. Others, that can't be upgraded to vectoring, can be software upgraded to a ‘vector friendly’ mode. Crosstalk from such a vector friendly line into neighbouring vectored lines can be cancelled, but the ‘friendly’ line itself does not benefit from the vectoring gain.
Upgrading the modem firmware is also a considerable undertaking for the telecom operators especially when it involves tens or hundreds of thousands of modems.
Moreover, not all the CPEs can be upgraded to friendly mode. To this aim, Alcatel Lucent has developed a 'zero-touch' approach that allows cancelling the crosstalk from legacy VDSL2 lines into a vectored lines without CPE upgrade. “This significantly facilitates and speeds up the roll-out of vectoring” says Spruyt
Further reading:
Boosting VDSL2 Bit Rates with Vectoring
DSL: Will phantom channels become real deployments
Tackling the coming network crunch
"In the end you run out of the ability to transmit more information along a single-mode fibre"
Ian Giles, Phoenix Photonics
The project, dubbed MODE-GAP, is part of the EC's Seventh Framework programme, and includes system vendor Nokia Siemens Networks (NSN), as well as optical component, fibre firms and several universities.
Current 100 Gigabit-per-second (Gbps) dense wavelength division multiplexing (DWDM) systems are able to transmit a total of 10 terabits-per-second of data across a fibre (100 channels, each at 100Gbps). System vendors have said that with further technology development, 25Tbps will be transported across fibre.
But IP traffic in the network is growing at over 30% each year. And while techniques are helping to improve overall transmission, the rate of progress is slowing down. A view is growing in the industry that without some radical technological breakthrough, new transmission media will be needed in the next two decades to avoid an inevitable capacity bottleneck.
"The Shannon Limit - the amount of information that can be transmitted - depends on the signal-to-noise and the amount of power you can put down a fibre," says Ian Giles, CEO of Phoenix Photonics, a fibre component specialist and one of the companies taking part in the project. "You can enhance transmission capacity by modulation techniques to increase bit rate, WDM and polarisation multiplexing but in the end you run out of the ability to transmit more information along a single-mode fibre."
This 'network crunch' is what the MODE-GAP project is looking to tackle.
Project details
One of the approaches that will be investigated is exploiting the multiple paths light travels down a multimode fibre to enable the parallel transmission of more than one channel.
These multiple paths light takes traveling in a multimode fibre disperses the signal. "The proposal we are making is that we take a low-moded fibre and select specific modes for each channel, or a high-moded fibre and select modal groups that are very similar," says Giles. The idea is that by identifying such modes in the multimode fibre, the dispersion for each mode or model groups will be limited.
But implementing such a spatially modulated system is tricky as the modes need to be identified and then have light launched into them. In turn, the modes must be kept apart along the fibre's span.
The project will tackle these challenges as well as use digital signal processing at the output to separate the transmitted channels. The project consortium believes that up to 10 channels could be used per fibre.
The second approach the MODE-GAP project will explore involves using specialist or photonic bandgap fibre. "The problem with solid core fibre is that the core will scatter light, and with higher intensity, you start to see non-linear scattering," says Giles. "So there is a limit to how much power you can put down a fibre without introducing these non-linear effects."
Photonic bandgap fibre has an air core that doesn't create scattering. As a result the non-linear threshold is some 100x higher, meaning that more power can be put into the fibre.
What next?
The MODE-GAP project is still in its infancy. The goal is to develop a system that allows the multiplexing and demultiplexing of the spatially-separated channels on the fibre. That will be done using multimode fibre but Giles stresses that it could eventually be done using photonic bandgap fibre. "You then enhance capacity: you increase the number of channels, and decrease the non-linearities which means you can increase the amount of information sent per channel," says Giles.
"Up till the spatial modulation part, the system is the same as you have now," he adds. "It is only the spatial modulation part that needs new components." NSN will use any prototype developed within its test-bed where it will be trailed. "They don't want to reinvent their equipment at each end," says Giles.
The project will also look to develop a fibre-amplifier that will boost all the fibre's spatial separated channels.
The project's goal is to demonstrate a working system. "The ultimate is to show the hundredfold improvement," says Giles. "We will do that with multiple channel transmission along a single photonic bandgap fibre and higher capacity [data transmission] per channel."
Project partners
In addition to NSN's systems expertise and test-bed, Eblana Photonics will be developing lasers for the project while Phoenix will address the passive components needed to launch and detect specific modes. OFS Fitel is providing the fibre expertise, while the University of Southampton's Optoelectronics Research Centre is leading the project.
The other universities include the COBRA Institute at the Technische Universiteit Eindhoven which has expertise in the processing and transmission of spatial division multiplexed signals, while the Tyndall National Institute of University College Cork is providing system expertise, detectors, transmitters and some of the passive optics and planar waveguide work.
ESPCI ParisTech, working with the University of Southampton, will provide expertise in surface finishes. "The key here is that for the fibres to be low loss, and to maintain the modes in the fibre, they have to have very good inside surfaces," says Giles.
Oclaro points its laser diodes at new markets
“To succeed in any market ... you need to be the best at something, to have that sustainable differentiator”
Yves LeMaitre, Oclaro
Now LeMaitre is executive vice president at Oclaro, managing the company’s advanced photonics solutions (APS) arm. The APS division is tasked with developing non-telecom opportunities based on Oclaro’s high-power laser diode portfolio, and accounts for 10%-15% of the company’s revenues.
“The goal is not to create a separate business,” says LeMaitre. “Our goal is to use the infrastructure and the technologies we have, find those niche markets that need these technologies and grow off them.”
Recently Oclaro opened a design centre in Tucson, Arizona that adds packing expertise to its existing high-power laser diode chip business. The company bolstered its laser diode product line in June 2009 when Oclaro gained the Newport Spectra Physics division in a business swap. “We became the largest merchant vendor for high-power laser diodes,” says LeMaitre.
The products include single laser chips, laser arrays and stacked arrays that deliver hundred of watts of output power. “We had all that fundamental chip technology,” says LeMaitre. “What we have been less good at is packaging those chips - managing the thermals as well as coupling that raw chip output power into fibre.”
The new design centre is focussed on packaging which typically must be tailored for each product.
Laser diodes
There are three laser types that use laser diodes, either directly or as ‘pumps’:
- Solid-state laser, known as diode-pumped solid-state (DPSS) lasers.
- Fibre laser, where the fibre is the medium that amplifies light.
- Direct diode laser - here the semiconductor diode itself generates the light.
All three types use laser diodes that operate in the 800-980nm range. Oclaro has much experience in gallium arsenide pump-diode designs for telecom that operate at 920nm wavelengths and above.
Laser diode designs for non-telecom applications are also gallium arsenide-based but operate at 800nm and above. They are also scaled-up designs, says LeMaitre: “If you can get 1W on a single mode fibre for telecom, you can get 10W on a multi-mode fibre.” Combining the lasers in an array allows 100-200W outputs. And by stacking the arrays while inserting cooling between the layers, several hundreds of watts of output power are possible.
The lasers are typically sold as packaged and cooled designs, rather than as raw chips. The laser beam can be collimated to precisely deliver the light, or the beam may be coupled when fibre is the preferred delivery medium.
“The laser beam is used to heat, to weld, to burn, to mark and to engrave,” says LeMaitre. “That beam may be coming directly from the laser [diode], or from another medium that is pumped by the laser [diode].” Such designs require specialist packaging, says LeMaitre, and this is what Oclaro secured when it acquired the Spectra Physics division.
Applications
Laser diodes are used in four main markets which Oclaro values at US$800 million a year.
One is the mature, industrial market. Here lasers are used for manufacturing tasks such as metal welding and metal cutting, marking and welding of plastics, and scribing semiconductor wafers.
Another is high-quality printing where the lasers are used to mark large printing plates. This, says LeMaitre, is a small specialist market.
Health care is a growing market for lasers which are used for surgery, although the largest segment is now skin and hair treatment.
The final main market is consumer where vertical-cavity surface-emitting lasers (VCSELs) are used. The VCSELs have output powers in the tens or hundreds of milliwatts only and are used in computer mouse interfaces and for cursor navigation in smartphones.
“These are simple applications that use lasers because they provide reliable, high-quality optical control of the device,” says LeMaitre. “We are talking tens of millions of [VCSEL] devices [a year] that we are shipping right now for these types of applications.”
Oclaro is a supplier of VCSELs for Light Peak, Intel’s high-speed optical cable technology to link electronic devices. “There will be adoptions of the initial Light Peak starting the end of this year or early next year, and we are starting to ramp up production for that,” says LeMaitre. “In the meantime, there are many alternative [designs] happening – the market is extremely active – and we are talking to a lot of players.” Oclaro sells the laser chips for such interface designs; it does not sell optical engines or the cables.
Is Oclaro pursuing optical engines for datacom applications, linking large switch and IP router systems? “We are actively looking at that but we haven’t made any public announcements,” he says.
Market status
LeMaitre has been at Oclaro since 2008 when Avanex merged with Bookham (to become Oclaro). Before that, he was CEO at optical component start-up, LightConnect.
How does the industry now compare with that of a decade ago?
“At that time [of the downturn] the feeling was that it was going to be tough for maybe a year or two but that by 2002 or 2003 the market would be back to normal,” says LeMaitre. “Certainly no-one expected the downturn would last five years.” Since then, nearly all of the start-ups have been acquired or have exited; Oclaro itself is the result of the merger of some 15 companies.
“People were talking about the need for consolidation, well, it has happened,” he says. Oclaro’s main market – optical components for metro and long haul transmission – now has some four main players. “The consolidation has allowed these companies, including Oclaro, to reach a level of profitability which has not been possible until the last two years,” says LeMaitre.
Demand for bandwidth has continued even with the recent economic downturn, and this has helped the financial performance of the optical component companies.
“The need for bandwidth has still sustained some reasonable level of investment even in the dark times,” he says. “The market is not as sexy as it was in those [boom] days but it is much more healthy; a sign of the industry maturing.”
Industry maturity also brings corporate stability which LeMaitre says provides a healthy backdrop when developing new business opportunities.
The industrial, healthcare and printing markets require greater customisation than optical components for telecom, he says, whereas the consumer market is the opposite, being characterised by vastly greater unit volumes.
“To succeed in any market – this is true for this market and for the telecom market – you need to be the best at something, to have that sustainable differentiator,” says LeMaitre. For Oclaro, its differentiator is its semiconductor laser chip expertise. “If you don’t have a sustainable differentiator, it just doesn’t work.”
The InfiniBand roadmap gets redrawn
“We can already demonstrate in silicon a 30Gbps transmitter."
Marek Tlalka, Luxtera
“Our June 2008 roadmap originally projected 4x EDR at less than 80Gbps data rate for 2011,” says Skip Jones, director of technology at QLogic and co-chair of the IBTA’s marketing working group. “The IBTA has increased the data speeds for 2011 due to demand for higher throughput.” A 26Gbps channel rate - or 104Gbps for 4x EDR - is to accommodate the overhead associated with 64/66bit encoding.
The IBTA has also added an interim speed, dubbed Fourteen Data Rate (FDR), operating at 14Gbps per channel or 56Gbps for 4x FDR. This, says the IBTA, is to address midrange enterprise applications in the data centre. “Many server OEMs’ backplanes can support speeds up to 56Gbps,” says Jones. “For those OEMs doing a server refresh using existing backplanes, 56Gbps will be the solution they’ll be looking to implement.”
The IBTA dismisses claims by some industry voices that the re-jigged roadmap is to stop InfiniBand falling behind 100 Gigabit Ethernet (GbE) while FDR is to advance InfiniBand while laser vendors grapple with the challenge of developing 26Gbps vertical-cavity surface-emitting lasers (VCSELs) for EDR.
Jones points out that 4x Quad Data Rate (QDR) InfiniBand (4x10Gbps) now accounts for between 60 and 70 percent of newly deployed InfiniBand systems, and that 100Gbps EDR will appear in 2011/ 2012. “The IBTA has a good track record of releasing products on time; as such, 100Gbps InfiniBand will come out much faster than 100 Gigabit Ethernet.” FDR, meanwhile, will benefit from 14Gbps VCSELs for Fibre Channel that will be available next year. Jones admits that developing a 26Gbps VCSEL poses a challenge but that “InfiniBand markets are mostly electrical interconnects”.
“The 4x25G short reach is not going to rise and dominate for quite awhile."
Scott Schube, LightCounting
“VCSELs are going to have a tough time at 26Gbps per lane, though they'll get there,” says Scott Schube, senior analyst and strategist at optical transceiver market research firm, LightCounting. “There's definitely a push to go to 26Gbps per lane to reduce pin counts, and the chip guys look like they will be ready before the VCSELs.”
One company looking to benefit from the emerging market for EDR is Luxtera. The silicon photonics specialist says its modulator has already been demonstrated at 30Gbps. This is fast enough to accommodate EDR, 100 Gigabit Ethernet (a 4-channel design) and the emerging 28Gbps Fibre Channel standard.
“We can already demonstrate in silicon a 30Gbps transmitter using the same laser as in our existing products and modulated in our silicon waveguides,” says Marek Tlalka, vice president of marketing at Luxtera. “That allows us to cover 14Gbps, 26Gbps EDR, parallel Ethernet as well as 28Gbps for serial Fibre Channel.”
Luxtera will need to redesign the transistor circuitry to drive the modulator beyond the current 15Gbps before the design can be brought to market. It will also use an existing silicon modulator design though the company says some optimisation work will be required.
There are two main product offerings from Luxtera: QSFP-based active optical cables and OptoPHY, one and four-channel optical engines. Luxtera’s OptoPHY product is currently being qualified and is not yet in volume production.
For multi-channel designs, Luxtera uses a continuous-wave 1490nm distributed feedback (DFB) laser fed to the modulated channels. Addressing 28Gbps Fibre Channel, an SFP+ form factor will be used. Luxtera may offer a transceiver product or partner with a module maker with Luxtera providing the optical engine. “It’s an open question,” says Tlalka.
“The IBTA has a good track record of releasing products on time; as such, 100Gbps InfiniBand will come out much faster than 100 Gigabit Ethernet.”
Skip Jones, IBTA
The company has said that the single-channel and four-channel 10Gbps OptoPHY engine consumes 450mW and 800mW respectively. Going to 26Gbps will increase the power consumption but only by several tens of percent, it says.
The first product from Luxtera will be a pluggable cable followed by a companion OptoPHY. The pluggable active optical cable from Luxtera will support 100GbE and EDR Infiniband. “I’d still place my bets on InfiniBand deploying first followed by 100GbE,” says Tlalka.
But Schube warns that Luxtera faces a fundamental challenge “Leading-edge designs based on proprietary technology to solve commodity problems - more bandwidth for out-of-the-box connections - are never going to get widely adopted, though Luxtera can fill a niche for awhile," he says.
There is also much work to be done before 100Gbps interfaces will be deployed. “The 4x25G short reach is not going to rise and dominate for quite awhile, no matter what the component availability is,” says Schube. That is because switch ASICs, backplanes, connectors and line cards will all first need to be redesigned.
Meanwhile the IBTA has also announced two future placeholder data rates on its InfiniBand roadmap: High Data Rate (HDR) due in 2014 and the Next Data Rate (NDR) sometime after. “We will refrain from identifying the exact lane speed until we are closer to that timeframe to avoid confusion and the possibility - and probability - of changing future lane speeds,” says Jones.
And Luxtera says its modulator can go faster still. “I think we can easily go 40 and 50Gbps,” says Tlalka. “After 50Gbps we’ll have to look at new magic.”
Video compression: Tackling at source traffic growth
The issue is the same whether it is IPTV services and over-the-top video sent over fixed networks, or video transmitted over 3G wireless networks or even video distributed within the home.
According to Cisco Systems, video traffic will become the dominant data traffic by 2013. Any technology that trims the capacity needed for video streams is thus to be welcomed.
"The algorithm uses a combination of maths and how images are perceived to filter out what is not needed while keeping the important information.
Angel DeCegama, ADC2 Technologies
Massachusetts-based start-up ADC2 Technologies (ADC2 stands for advanced digital compression squared) has developed a video processing technology that works alongside existing video coder/decoders (codecs) such as MPEG-4 and H-264 to deliver a 5x compression improvement.
ADC2 uses wavelet technology; a signal processing technique that for this application extracts key video signal information. “We pre-process video before it is fed to a standard codec,” says Angel DeCegama, CEO and CTO of ADC2 Technologies. “The algorithm uses a combination of maths and how images are perceived to filter out what is not needed while keeping the important information.”
The result is a much higher compression ratio than if a standard video codec is used alone. At the receiving end the video is decoded using the codec and then restored using ADC2’s post-processing wavelet algorithm.
DeCegama says the algorithm scales by factors of four but that any compression ratio between 2x to 8x can be used. As for the processing power required to implement the compression scheme, DeCegama says that a quad-core Intel processor can process a 2Gbit/s video stream.
ADC2 Technologies envisages several applications for the wavelet technology. Added to a cable or digital subscriber line (DSL) modem, operators could deliver IPTV more efficiently. And if the algorithm is included in devices such as set-top boxes and display screens, it would enable efficient video transmission within the home.
The technology can also be added to smart phones with the required wavelet processing executed on the phone's existing digital signal processing hardware. More video transmissions could be accommodated within the wireless cell and more video could be sent from phones via the upstream link.
ADC2 Technologies demonstrated the technology at the Supercomm trade show held in Chicago in October. Established in 2008, the 5-staff start-up is looking to develop hardware prototypes to showcase the technology.
The first market focus for the company is content delivery. Using its technology, operators could gain a fivefold improvement in network capacity when sending video. Meanwhile end users could receive more high-definition video streams as well as greater content choice. “Everyone benefits yet besides some extra hardware and/or software in the home, the network infrastructure remains the same,” says DeCegama.
Digital Home: Services, networking technologies and challenges facing operators
Source: Microsoft
The growth of internet-enabled devices and a maturing of networking technologies indicate the digital home is entering a new phase. But while operators believe the home offers important new service and revenue opportunities, considerable challenges remain. Operators are thus proceeding cautiously.
Here is a look at the status of the digital home in terms of:
- Services driving home networking
- Wireless and wireline home networking technologies
- Challenges
Services driving home networking
IPTV and video delivery are key services that place significant demands on the home network in terms of bandwidth and reach. Typically the residential gateway that links the home to the broadband network, and the set-top box where video is consumed are located apart. Connecting the two has been a challenge for telcos. In contrast, cable operators (MSOs) have always networked video around the home. The MSOs’ challenge is adding voice and linking home devices such as PCs.
Now the telcos are meeting the next challenge: distributing video between multiple set-tops and screens in the home.
Other revenue-generating home services interesting service providers include:
- A contract to support a subscriber’s home network
- E-health: remote monitoring a patient’s health
- Home security using video cameras
- Media content: enabling a user to grab home-stored content when on the move
- Smart meters and energy management
One development that operators cannot ignore is ‘over-the-top’ services. Users can get video from third parties directly over the internet. Such over-the-top services are a source of competition for operators and complicate home networking requirements in that users can buy and connect their own media players and internet-enabled TVs. Yet any connectivity issues and it is the operator that will get the service call.
However, over-the-top services are also an opportunity in that they can be integrated as part of the operator’s own offerings and delivered with quality of service (QoS).
Wireless and wireline home networking technologies
Operators face a daunting choice of networking technologies. Moreover, no one technology promises complete, reliable home coverage due to wireless signal fades or wiring that is not where it is needed.
As a result operators must use more than one networking technology. Within wireline there are over half a dozen technology options available. And even for a particular wireline technology, power line for example, operators have multiple choices.
Wireless:
- Wi-Fi is the technology of choice with residential gateway vendors now supporting the IEEE 802.11n standard which extends the data rate to beyond 100 megabits-per-second (Mbps). An example is Orange’s Livebox2 home gateway, launched in June 2009.
- The second wireless option is femtocells, that is now part of the define features of the Home Gateway Initiative’s next-generation (Release 3) platform, planned for 2010. Mass deployment of femtocells is still to happen and will only serve handsets and consumer devices that are 3G-enabled.
Wireline
- If new wiring of a home is possible, operators can use Ethernet Category-5 cabling, or plastic optical fibre (POF) which is flexible and thin.
- More commonly existing home wiring like coaxial cable, electrical wiring (powerline) or telephone wiring is used. Operators have adopted HomePNA which supports phone wiring; the Multimedia over Coax Alliance (MoCA) that uses coaxial cabling; and the HomePlug Powerline Alliance’s HomePlug AV, a powerline technology that uses a home’s power wiring over which data is transmitted.
- Gigabit home networking (G.hn) is a new standard being developed by the International Telecommunication Union. Set to appear in products in 2010, the standard can work over three wireline media: phone, coax and powerline. AT&T, BT and NTT are backing G.hn though analysts question its likely impact overall. Indeed one operator says the emerging standard could further fragment the market.
Challenges
- Building a home network is complex due to the many technologies and protocols involved.
- Users have an expectation that operators will solve their networking issues yet operators only own and are interested in their own home equipment: the gateway and set-top box. Operators risk getting calls from frustrated users that have deployed a variety of consumer devices. Such calls impact the operators’ bottom line.
- Effective tools and protocols for home networking monitoring and management is a must for the operators. The Broadband Forum’s TR-069 and the Universal Plug and Play (UPnP) diagnostic and QoS software protocols continue to evolve but so far only a fraction of their potential is being used.
Operators understandably are proceeding with care as they cross the home's front door to ensure their offerings are simple and reliable. Otherwise any revenue-potential home networking promises as well as a long-term relationship with the subscriber will be lost.
To read more:
- A full article including interviews with operators BT and Orange; vendors Cisco Systems, Alcatel-Lucent’s Motive division, Ericsson and Netgear; chip vendors Gigle Semiconductor and Broadcom; the Home Gateway Initiative and analysts Parks Associates, TelecomView and ABI Research will appear in the January 2010 issue of Total Telecom.
- Can residential broadband services succeed without home network management? Analysys Mason’s Patrick Kelly.