re: Nextel Flashes With FlarionIt seems that the ownership of much of Flarion's technology is disputed. The application of OFDM to frequency hopping has been well known for quite some time. For example, U.S. Phillips patented similar "flash-OFDM" technology in the early 1990s. That probably explains why the claims in Flarion's patents seem so narrow as to be practically useless.
Many of Flarion's patent applications (especially those in which Rajiv Laroia is the claimed inventer) seem to be written by people who have little knowledge of the field. Many of the so-called innovations are well known. With regards to the content that appears to be novel, one could make a strong case for IP theft. I am certain that this is one of many credibility problems faced by Flarion. In fact, those who are familiar with Rajiv Laroia might agree that he has made a career of claiming credit for other people's innovations.
Furthermore, Flarion's use of frequency hopping in conjunction with OFDM appears to offer no benefit in neither cost nor performance compared to well-known coded OFDM techniques. Flash-OFDM's so-called spread-spectrum benefits are achieved via channel coding in the same way that conventional coded-OFDM achieves its spread-spectrum capabilities. The main difference is that flash-OFDM requires additional hardware and control features due to frequency hopping. It also presents significant interoperability and compatibility problems compared to competing types of OFDM that are also being ommercialized.
re: Nextel Flashes With FlarionThose appear to be quite some claims you have there. Do you have any proof for any of this?
I don't have any direct experience with Flarion's tech, but I know several people who work there, and they are brilliant people of exemplary character. I would believe them over a bulletin-board poster any day.
So here it is: I accuse of you of being one of: a) A troll. b) Full of it. c) Someone who has a vested interest in discrediting Flarion.
Here is your chance to prove me wrong. Post some references that prove any of your claims.
It is so obviously pathetic that you either work for a competitor or have no idea what you are talking about. Or both.
>>It seems that the ownership of much of >>Flarion's technology is disputed.
By whom, other than you.
>>The application of OFDM to frequency hopping >>has been well known for quite some time.
Flarion does not take credit for OFDM, just Flash-OFDM.
>>In fact, those who are familiar with Rajiv >>Laroia might agree that he has made a career >>of claiming credit for other people's >>innovations.
Dispariging personal attacks without facts or substance, make you look like an idiot.
>>Furthermore, Flarion's use of frequency >>hopping in conjunction with OFDM appears to >>offer no benefit in neither cost nor >>performance compared to well-known coded OFDM >>techniques.
How do you know? Where are your cost/performance calculations/approximations?
From what I have read, if it saves spectrum it is a good thing economically. If it has a reuse factor of 1, it is good both economically and performance-wise.
>>The main difference is that flash-OFDM >>requires additional hardware and control >>features due to frequency hopping.
Additional hardware compared to what? All new solutions require new hardware.
>>It also presents significant interoperability >>and compatibility problems compared to >>competing types of OFDM that are also being >>commercialized.
There are no other OFDM competitors. OFDM is used in Wi-fi, but this is complementary since it is not in the same market, i.e., LAN reach, not WAN reach as Flarion does.
How can you comment on interoperability if no published results exist?
It is published that Flash-OFDM technology will interoperate with Wi-Fi in the future.
Tybalt, do some research before embarrasing yourself on this board again.
P.S.: I do not work for either Flarion, Nextel, or their competitors.
I will agree that the 802.16 spec is futher along in the standardizaton process, but 802.20 is not far behind (late 2004-ish). For fixed wireless, 802.16 is clearly superior in cost and performance today.
The sweet spot of the market will be the purely mobile play at DSL/Cable modem prices. Flarion says that their technology has this.
The real crux of the matter will come down to how well applications run on the network.
If I do not have to change anything (TCP window size)in my applications, it will clearly be an advantage. As you know, TCP is inherently delay sensitive, so a large pipe is not sufficient if your TCP acks encounter so much delay variability that the application server will throttle the client back. In Asia, some wireless companies have a different protocol to handle this, Mobile-TCP/IP. But guess what, if you have to wait or Bill Gates to support it, or if you have to modify it everytime Microsoft puts out a new OS, good luck!
The trick is to minimize or eliminate the packet delay variability in the most most susceptible link, the airlink, without changing the application or OS.
So in the end, the 802.x standard that provides mobility with the best application experience to the user will win. Who wouldn't buy it if it works at home, on a train, or in the local neighborhood?
I have heard that Flash-OFDM (802.20) is superior in minimizing the packet loss across the mobile airlink and it makes EV-DO pale in comparison. I have yet to see mobile 802.16e and wonder how it behaves in a real delay sensitive setting (DOOM).
But that is where the rubber meets the road for us road-warriors!
You certainly raise some issues: could you give a little more detail or provide some references? For example, are there contributions in the 802.20 discussion area?
Perhaps better if you separate the technical/commercial matters from ad hominem comments.
It is clear that Flarion have had some aggressive PR and some of their claims are a little "forward leaning". Nothing wrong with that, so long as we exercise a little healthy cynicism.
The Laws of Physics apply everywhere, despite the hopes of some VCs and PR hacks :)
G-man said: "There are no other OFDM competitors. That is not the case. There are a number of propriatary OFDM products, but much more importantly, WiMax (with heavy Intel backing) uses the OFDM mode of 802.16. For fixed wireless, this is an existing standard, and therfore has a big advantage over propriatary solutions. Mobility is still in process (802.16e) but companies like Runcom have it now & are promoting it.
Flarion are trying to get their technology standardised with 802.20.
It will be interesting to see how things shape out.
re: Nextel Flashes With FlarionI agree that there are a NUMBER of OFDM competitors. It's silly to suggest otherwise. Now when it comes to all of the discussions about mobility and TCP window size, this is a bit over my head. But - I do recognize that the method of encoding data at the physical layer should be irrelevant to this problem (correct me, please, if I'm wrong).
So given that 802.16a has already been defined, why would the IEEE want to make any MAJOR changes to the physical layer? Sure the MAC will change and a bunch of other stuff (that again, is over my head) will change ... but if Flarion didn't get their technology into 16a why would they have any more success in 20? Can anyone explain? I'm open to all comments.
In the end, my understanding is that Wi-MAX will be the word used to describe outdoor wireless standards just like Wi-Fi describes indoor LANs. It won't necessarily be specific to one technology (ie, we now call 802.11g Wi-Fi even though it was originally a term that applied only to 11b). So is Nextel betting that Flarion's tech will be the Wi-MAX of the future, or are they just using Flarion to test out OFDM technology in general?
>So given that 802.16a has already been defined, why would the IEEE want to make any MAJOR changes to the physical layer?
At the time that 802.20 was proposed, I do not think that the mobility draft of 802.16 was on the table. At that time, the IEEE must have seen enough difference between the two to allow both.
> if Flarion didn't get their technology into 16a why would they have any more success in 20?
802.20 is not compatible with 802.16 so this technology could not just be added to the 802.16 spec. It is my understanding that Flarion is driving the 802.20 through the IEEE, and licensing it to others.
> So is Nextel betting that Flarion's tech will be the Wi-MAX of the future, or are they just using Flarion to test out OFDM technology in general?
I think that Nextel is betting that Flarion's technology will the fully mobile Wi-Max of TODAY, not the future. It must be working now for them to solicit friendly users on that website.
Has anyone heard from anyone in NC about their experience?
re: Nextel Flashes With FlarionDear Physical_layer, To answer your questions:
1. PHY effects on TCP The is a nasty interaction between physical and mac with the TCP timers due to the total delay under normal transmission artifically increasing the TCP estimate of the path length. The delay is due to the channel coding/interleaving in the phy, the MAC ARQ process and its own window length and the delay in return channel for the NACKs, etc. To build a "TCP friendly" phy and mac then you need to minimise these delays even if it means sub-optiminal physical layer performance. This is nothing to do with the choice of OFDM vs. CDMA, etc. but lots to do with the parameterisation of your specific system design.
2. 802.16e vs. 802.20 The 802.16e PAR basically says they are meant to work on an extension of 802.16a to add some nomadic/mobility feature while the 802.20 is designing a fundamentally different phy/mac which is to be optimised for mobile.
Two big issues here are the delay to require a new base station (some existing fixed link radio systems take seconds to do this and by then you can forget about handover going around a corner!) and the design assumptions about Doppler which effect burst lengths and channel estimation, etc.
The big 802.20 story for me though is whether or not this group will ever agree to anything. Flarion made lots of noise last year but the "dark forces" seem to have arrived now....
3. WiMAX The great 802 tradition is each group has an associate "interop forum" with a fancy name. 802.11 has WiFi (just as 802.3ae had 10GEA) and now 802.16 has WiMAX. I guess that the 802.20 will have to launch a "WiMOB" forum some time....
When 802.20 was proposed, .16 was fixed only, and 3G was, well, it wasn't .
But now, the situation looks different. The .20 timeline has slipped, with dates of 4Q05 now being discussed.
But .16e offers a very similar spec - with a lot more to offer in terms of backing, interoperability and existence.
From the other side, EVDO is demonstrating success, more & more operators are launching WCDMA (interestingly, for example, VODA have launched it as an EVDO style service). HSDPA is imminent - with DoCoMo committed to a service launch next year.
There is a lot of standards politics in all this. Just as in UWB, these are proxies for corporate fights. So INTEL have their weight behind WiMax, Moto are pushing .20.
I do love standards bodies: a bizarre mix of high technology with low political cunning & deals in smoke filled rooms :)
In terms of technology & spectrum efficiency, there really isn't much in it.
Latency, packet ARQ algorithms & the like are important, but they are complex and subtle; that makes them hard to get excited about, and hard to really say how things will work till after you've deployed & optimised. As standardsarefun points out - many of these are parameters, and a lot ore independent of the standard per se.
"Show me the money" -- I think Motorola & Nextel are indeed precursors of the future for Flarion and .20. It may well be the next iDEN - a nice little earner, but not really that interesting on the world stage.
btw Justin where does this "three times the efficiency of 3G" come from? Flarion claim 1.5Mbps-3Mbps in 1.25MHz. That isn't too different to EVDO offering 2Mbps - and that is in widespread commercial service now. It is less than HSDPA with 14Mbps in 5MHz. There's a good reason for this, called Shannon's limit. None of them (none of them) will deliver those data rates in the majority of cases.
Many of Flarion's patent applications (especially those in which Rajiv Laroia is the claimed inventer) seem to be written by people who have little knowledge of the field. Many of the so-called innovations are well known. With regards to the content that appears to be novel, one could make a strong case for IP theft. I am certain that this is one of many credibility problems faced by Flarion. In fact, those who are familiar with Rajiv Laroia might agree that he has made a career of claiming credit for other people's innovations.
Furthermore, Flarion's use of frequency hopping in conjunction with OFDM appears to offer no benefit in neither cost nor performance compared to well-known coded OFDM techniques. Flash-OFDM's so-called spread-spectrum benefits are achieved via channel coding in the same way that conventional coded-OFDM achieves its spread-spectrum capabilities. The main difference is that flash-OFDM requires additional hardware and control features due to frequency hopping. It also presents significant interoperability and compatibility problems compared to competing types of OFDM that are also being ommercialized.