HomePNA Blog

G.hn Home Network Standard – Not Quite Smooth Sailing

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

Well fun times for all you ITU G.hn watchers. As I wrote back in June, G.hn has settled on some "Baseline Text" for most of the protocol pieces that lie upstream of the G.9960 G.hn PHY (which anybody that follows G.hn can tell you was consented last December). So … here’s to more smooth sailing in the standards body. Did I hear a “not quite”? True, the group is moving briskly toward consent at the September 28 to October 9 meeting in Geneva , however it seems everyone isn’t running in the same direction.

So what’s happening? It’s gotten more contentious, that's what. At the G.hn meeting in Concord, Ca last week, some of the attendees (guess who) introduced a contribution to add compatibility between HomePlug and G.hn. If you’ve been following the evolution of the standard, you probably remember the decision made long-ago to work for co-existence with existing technologies, not compatibility. That decision was pragmatic and probably prevented a HomePlug-UPA-HD-PLC-MOCA-HomePNA (did I leave anyone out?) shootout that could have killed, or at least maimed, the new G.hn all-wire standard effort. The changes proposed last week would have affected both the MAC and PHY in fairly significant ways and may have posed a problem for the one chip-all wire goal.

Anyway, to make a long story short, the group’s historical reticence to require compatibility with other home networking technologies combined with major angst over anything that could delay completion of the final drafts caused even some participants who planned to stay neutral at the meeting to dissent. The contribution was presented, debated, dissected, debated some more and, in the end, fell far short of consensus for technical and practical reasons. Is it smooth sailing from here on? Can’t say for sure as all eyes (or at least the ones that care enough to read this blog) turn to Geneva. It’s not over till it’s over and then the market will decide.

IEEE P1901 Has a Draft Standard

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

Well the IEEE P1901 Working Group certainly got its act together. Last week they approved the first IEEE P1901 Draft Standard with more than an 82% majority -- which represents some great consensus building.

This doesn’t mean that all the work is done but it certainly is a big step in the right direction. According to Wikipedia, some P1901 watchers attribute this to inclusion of the ITU G.hn MAC as one of the supported MACs (yes, one of them -- P1901 still carries a lot of baggage) but it’s not clear to me whether that’s a done deal or not. I heard there is still some work to be done on the MACs and of course the draft standard has to go through the IEEE’s letter ballot/comment period/resolution process to resolve any open issues. Comments are resolved at P1901 meetings and the next opportunity will be the Boston meeting at the end of October).

Standardization is good for the industry. That’s why HomePNA decided to standardize its technology under the ITU years ago. It levels the playing field and insures that the technology is available to everyone. The market will decide the winners.

Gigle First to Claim the Really High Ground

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

You’ve probably heard that Gigle Semiconductor has claimed the high ground; launching the “World's First Gigabit Home Networking Chip”. No doubt about it, they are good. So what’s Gigle’s all-important user throughput. I don’t know BUT I heard that Belkin adapters, the first products using the chip, are available so we’ll know soon. We’ll also know more about Gigle’s proprietary “mediaxtream”, the technology giving them the boost over Homeplug AV data rates.

The big question is whether Gigle will be able to convince large service providers to use proprietary technology (especially with all the service provider interest in ITU G.hn’s Gigabit standard). If they want it to be selected they really need an open standard. I remember way-back-when that Gigle proposed something to G.hn but it wasn’t included in the G.9960 PHY standard.  There are other standards groups in the world so if they are willing then who knows.

On to the small print. Gigle claims speeds up to 1000Mbps but there’s an asterisk and a note that 1000Mbps is the “ideal physical data rate” and actual data throughput and distance will be lower, depending on interference, network traffic, building materials, and other conditions”.

OK, we all play marketing games. That’s why I use phrases like “up to” when I write about data rates. It’s not my fault. Editors and analysts make me do it. Speed sells and it’s a lot easier than trying to explain user throughput. So … what it means is that the chip produces Gigabit speeds in the lab and maybe on a tester. In the real world you start with the real data rate which is pretty much guaranteed to be lower than a Gigabit and then start subtracting off the overhead.

The overhead depends on the encoding technology – the ways the digital data bits are “encoded” for transmission. Usually some user data bits are encoded into more bits for transmission on the media; be it phone wire, coax, powerline, Ethernet cable or air. There are other transmission taxes related to the way the technology deals with interference and other real world nasties. And then you subtract the MAC overhead – the gaps, address fields, error correction etc. Some MACs (like HomePNA 3.1) are very efficient. Others aren’t. What you have left is the real data throughput. And if you are lucky it will be stable. If you are unlucky it will vary all over the place depending on interference etc.

So the devil is in the details.  But this is old news – it’s the reason that major North American service providers prefer coax and phone wires over wireless Wi-Fi and powerline for distributing triple play services in the home. And while we’re on the subject, the ITU G.hn is meeting this week. What’s on the agenda? Cleaning up the draft and converging toward final consent in Geneva. Gigle is first but that may or may not be important in the long run.

New Home Networking Market Report

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

Like any good marketing dweeb (yes there are many definitions of “dweeb, none of them complimentary) I read the announcement of a new home networking market study by In-Stat analyst Joyce Putscher with both interest and fear. Interest because she may have succeeded in distilling a few nuggets of wisdom from the hype we marketing types throw at her; and fear that she gave sweeter ink to the competition (and also joy that she didn’t spell out the HomePNA acronym – we’ve been trying squelch it since the turn of the century when it became apparent that the initial interest driving the use of HomePNA in North America was COAX and then phone wires in that order).

“Over the next few years, service providers will drive the growth of in-home networks” and “Two segregated home networks (HN) have been evolving – a service provider-centric network, and a PC-centric network. Each is leveraging different business models and technologies” caught my eye. I believe the first – and not just because it gives my life meaning. The second, I’m not so sure.

As I blogged last week, trade groups focused on the transmission media, such as HomePNA, MOCA, HomePlug, and Wi-Fi (often referred to as the PHY for Physical Interface layer) and industry groups focused on higher layers such as the Broadband Forum and DLNA often work together and may share representatives driving a lot of information sharing. And remember, those representatives are employees of stakeholders -- communication companies, consumer electronics manufacturers, service providers, and other interested parties. 

Given that a home network such as HomePNA incorporates guaranteed quality of service which, as discussed many blogs ago, is designed for triple-play and can transport a variety of data types without degrading time sensitive revenue bearing services like IPTV and VoIP, the technology is there waiting for those cross-pollinating standards people to build the usage models and recommendations to simplify your networked life.  And going on it is, but that doesn't mean it will be adopted.  So, my take is an assertive maybe. 

Non-debate over G.hn?

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

If you saw Rick Merritt's EE Times column yesterday "Debate breaks out over home net standards; HomePlug group raises issues about ITU G.hn effort" you may have been confused. I know I was. After all, debate didn't just break out. The ITU G.hn group has been constructively debating this for the last two years. And the HomePlug technology companies were in the thick of it along with almost everyone else in the Who's Who of existing wire home networking. G.hn considered a lot of encoding schemes before approving G.9960 (including HomePlug's turbo code which was given very serious consideration for a long time before the group settled on LDPC).

OK, so is LDPC better technology? Well the consensus from G.hn is that it is a better choice for a single all-wire standard. Will it be harder to license than turbo code? Don't think so. The ITU has a strict IP policy (IP as in Intellectual Property like patents). Companies with relevant IP have to sign a document stating that they will or will not license it. The owner of the LDPC incorporated into G..9960 has recently agreed to license it. Concern resolved.

Is a new standard over powerline bad for the market? You could make a similar argument about G.hn not being interoperable with the millions of HomePNA devices deployed over coax. But, and it's an important but, we set out to create a single world-wide all wire standard. It was apparent from the beginning that interoperability with existing technologies wasn't practical if we wanted to succeed so a coexistence path with existing technologies was chosen as the best long-term solution for the industry. And it worked.

ITU G.hn Stays On Track

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

Time to get back to work. The G.hn crowd wrapped up another meeting last week – the first meeting of the year and the first since releasing the G.9960 standard last December. The group is continuing to move at the fast pace they set last year with lots of technical contributions, monthly meetings, a goal of closing comments on the next standard before the summer, and wrapping up this phase by Sept. Although I don’t expect products this year or early next, I wouldn’t be surprised if there were some very limited field trials of the technology around this time next year.

With G.9960 released last December as promised, G.hn is building an enviable track record. Remember, it’s only been two years since the same group released the world’s first two wire home networking standard (that’s right, I mean HomePNA 3.1/G.9954) -- which was only two years after they released the HomePNA 3.0 standard which set the bar for this generation of high performance triple-play-ready multimedia home networking standards (or in less self-indulgent terms, HomePNA 3.0 was released before MoCA 1 or HomePlug AV). A major release every two years. Not too shabby for a standards group.

People that follow this blog know that HomePNA members support the G.hn effort and that some have been working on it since the HomePNA 3.1 standardization wrapped up. We feel that the more cooperation and support the work has the better the end result will be and that the advantages of a single standard will increase the revenue opportunity for everyone. In that spirit, HomePNA and HomeGrid announced a liaison agreement making it easier for our organizations to cooperate more closely to better support the great work.

IEEE P1901 – Is the Opera Truly Over?

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

Well the season finale of my favorite soap, how the IEEE turns, has aired. And what a season it was! Now it’s time for everyone to live happily ever after (at least they would if I wrote the script, three years to get to a draft spec is enough).

If you’re familiar with how the IEEE developed the elegant two PHY P1901 proposal, then you may not be surprised that the approved version includes not two but three PHYs. That’s right. Despite defeating a previous bid to use the ITU’s G.hn PHY for P1901, the final compromise proposal includes G.hn in addition to Intellon’s HomePlug AV Panasonic’s HD-PLC PHYs.

The inside story is that the P1901 proposals squeaked by and may well have been headed for another defeat. The addition of the G.hn PHY saved the day by drawing new supporters (including G.hn pioneer Coppergate Communications who voted yes for the first time).

So this is great for everyone, right, a real win-win? I certainly hope so but there are nasty rumors circulating about it being a political ruse and behind the scenes efforts taking place to remove G.hn from the IEEE P1901 draft standard. The industry took a giant step forward when G.hn was added to P1901 and now it’s time for the IEEE to walk the walk and do the right thing for everyone.

G.hn, a PHY For All Seasons

By Rich Nesin, General Manager and Resident Philosopher, HomePNA 

Back last May we bloged a bit about what makes G.hn different. One caveat, set down at the time by the service providers, required G.hn to start with a clean slate.  They were told to choose the technology based on best of breed rather than interoperability with existing technologies. With evangelical zeal and no existing triple-wire home networking industry specification, it seemed like a good idea at the time.  I think this decision more than anything else helped G.hn stay the course and finish on time

So it wasn't a huge surprise that G.hn didn't pick one of the dominant wired home networking codes used by HomePNA 3.1, HomePlug AV or MOCA. Instead, G.hn used a Low-Density Parity-Check code (LDPC code) which Wikipedia correctly notes is an error correcting code used to transmit messages over a "noisy" transmission channel. Wikipedia goes on to say that that it wasn't practical to implement an LDPC code when it was developed in 1963 however in theory it is the most effective code developed to date.  This doesn't mean the other codes are bad even over noisy channels.  It only means that after evaluating the alternatives, LDPC was the best match to their requirements.

So G.hn selected a code for all seasons, allowing technologists to design one universal wired home networking chip. Selecting the code type was just part of the job (although a fairly contentious part). G.hn standardized a complete PHY specification; in addition to the LDPC coding scheme they selected modulation parameters and other specifications required to actually make it work. The three media types – powerline, coax and phone wires – are not the same. Far from it. G.hn developed different modulation parameters to provide robust operation over each medium.

The result is a PHY standard ready for the chip designers. A PHY standard is not the same as a chip specification so expect different implementations from different vendors. For example, there is no physical interface to the PHY defined; just a logical interface allowing each vendor to design its own optimized product. Should you expect to see stand-alone G.hn PHY chips? I don’t -- any more than I expect to see stand-alone 802.11 WiFi PHY chips. Integrated PHY/MAC products make a lot of sense for a number of reasons (not the least being cost). Should you expect chip vendors to be hard at work putting the finishing touches on their G.hn PHY designs now that the standard is complete? You betcha.

ITU G.hn Delivers a Spec

By Rich Nesin, General Manager and Resident Philosopher, HomePNA

Have you noticed the press coverage that high performance home networking over existing wires is getting? It makes me nostalgic for the days when analysts dismissed us with a quick ‘the world is going wireless”. It probably is, but installations in millions of IPTV homes over the last couple years say that it isn’t always the best solution. Last week’s ITU announcement about completing the first G.hn standard seems to have gotten the most coverage yet (possibly due to how extraordinarily rare it is for a standards group to deliver a standard on time). So you may be wondering what actually happened and how?

If you have been following my ramblings about home networking standardization in the IEEE P1901; and ITU Q4/15 you may already have a good idea of what happened. If you’re not familiar with the ITU, standards can only be approved during special ITU “plenary” meetings. A plenary is a formal two week meeting of the entire SG 15 (not just the Q4/15 group that is part of SG 15 or the even smaller G.hn group that is part of Q4/15 and has been meeting every couple weeks for the last year to get the work done on time). Like the other meetings, the plenary was very technical with lots of informal working meetings during the evenings to refine the contributions and achieve consensus on the contributions (or in the words of one engineer, “lots of real work was done”). This is the “how”. This and a lot of hands-on direction from some of the world’s largest telcos.  Being the customer has its advantages and these customers see the advantages of a single open world-wide existing-wire home networking standard.

So what happened? I wrote a little about MACs and PHYs back in a June post about HomePNA's guaranteed QoS. Like most other home networking technologies, G.hn is built of two components; a MAC and a PHY. The MAC part, short for medium access control, manages the communication between devices on the home network. The PHY part, short for physical interface, encodes and decodes the data from the MAC – encoding it so that it can be carried efficiently over the media (which in the case of G.hn can be powerlines, phone wires or coax) and decoding the data that is received from the media so it can be processed by the MAC. Every product featuring a G.hn interface will have a MAC and PHY. So what is G.hn’s new G.9960 standard? It’s the new G.hn PHY. The companion G.hn MAC spec is scheduled to be completed in September.

More soon …

Powerline Home Networking Update - The IEEE P1901 Work Creeps On

By Rich Nesin, General Manager, HomePNA

Last summer I attended an IEEE P1901 standards meeting - the group standardizing home networking and broadband access over powerlines - and was inspired to post a couple blogs about the experience.

Well, half a year has passed and if you haven’t been following the play by play action you haven’t missed much.  If you recall, the current P1901 “compromise” proposals (there are 3) came about after HomePlug and HD-PLC supporters broke the three-way deadlock by combining their proposals at the expense of UPA. The new proposal, constructed by gluing together large chunks of HomePlug AV and HD-PLC along with some new “coexistence” circuitry, will allow them to coexist with HD-PLC and HomePlug AV as well as with other existing powerline home networking technologies (or at least the existing technologies that implement the new coexistence mechanism). It will coexist with some technologies – and you can guess which ones -- better than with others.  At least it will if they can ever get past the proposal stage and start working on the actual draft standard.

Anyway, six months later and the drama continues.  The joint proposal was voted down at the Madrid meeting which, in theory, should've sent everyone back to their drawing boards to draft a new proposal.  That’s the theory.  In fact what happened was that the same compromise proposal is being voted on again.

Now, and this is hearsay (but juicy hearsay), the rumor is that a certain party has been very active adding voting supporters to P1901. Some of these supporters, the rumor goes, have little to do with home networking or access over powerlines.  As we discussed in the past, a new member must attend a couple of P1901 meetings to vote on a proposal so this is where the rumor gets juicier.  The proposal supporters have asked for a telephone conference on December 9th, before the next face to face meeting in Japan on December 16th, to review the “no” comments made subsequent to the last meeting in San Francisco.  Speculation is that they have requested that this teleconference be considered a working group meeting so that it counts toward the new members’ voting qualification. 

Wouldn’t it be better if we all just tried to get along?