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Australian WiMax Pioneer Calls It a Disaster
Anonymous Coward writes "Garth Freeman, CEO of Australia's first WiMax operator, sat down at the recent International WiMax Conference in Bangkok and unleashed a tirade about the failings of the technology, leaving an otherwise pro-WiMax audience stunned. His company, Buzz Broadband, had deployed a WiMax network over a year ago, and Freeman left no doubt about what conclusions he had drawn. He claimed that 'its non-line of sight performance was "non-existent" beyond just 2 kilometres from the base station, indoor performance decayed at just 400m and that latency rates reached as high as 1000 milliseconds. Poor latency and jitter made it unacceptable for many Internet applications and specifically VoIP, which Buzz has employed as the main selling point to induce people to shed their use of incumbent services.' We've previously discussed the beginnings of WiMax as well as recent plans for a massive network in India.
There is no technical excuse for spectrum regulation in it's current form. If wimax has faults, the cause is poor spectrum allocation. Why is it that we still have broadcast TV and AM radio? Nothing short of spectrum liberation is just or acceptable.
No calls now, I'm
>Not all WiMAX operators are unhappy.
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>Internode says an Airspan-supplied network is providing consistent average speeds of 6Mbps at >distances up to 30km, with CEO Simon Hackett describing the platform as "proven."
So where exactly lies the problem? Implementation?
WIMAX isn't going to be the success that it should be because I think it was driven more by marketing than technology.
I'm going to fiddle my fingers until they have a few more disasters till they get it working. In the meantime mesh will definitely deflate the momentum WIMAX needs right now.
Maybe someone can clear this up- does Clearwire use WiMax or not? Wikipedia didn't make it clear. My experience with them was that they didn't either have the infrastructure or the bandwidth to support their meager customer base. The thing worked just fine during the day when nobody really used it, but during busier hours you had significant lag and flow problems- however, the download rate was still good, but you can't play games with a ping of over a second.
To me, WiMax is the future version of 56k.
you should look into the Bell/Rogers WiMax service.. we're right at the fringe area of coverage(the antenna software claims we're linking up from about 11km away), and yet for the most part it's stable at it's 2mbit link speed.
The 10 gb a month bandwidth limits are horrible though.
If you have line of sight, everything is just fine. 30km is easily do-able. If you don't, then physics is just a bitch, my friends. At 3.5Ghz, you aren't going to get through much no matter what you do... the waves (or particles, depending on how you observe them) are going to be like bullets hitting water, the larger the calibre, the less far you can get the bullet with any real force.
700Mhz spectrum should be interesting. It has monstrous value and application - however the performance will be an issue since it can go so far, but doesn't have that many cycles to use for bandwidth compared to multi-Ghz radios. The temptation to put 1,000 people on a single 54Mbps (my wild-ass best estimate for performance) access point will be extremely hard to avoid.
...Steve
Ok, but WiMAX normally doesn't depend on a collision/backoff system for voice traffic.
WiMAX has a central scheduler at the base station (BS). For best-effort (BE) traffic, the CPEs use a contention region to send a bandwidth request asking for the needed amount of bytes. The BS considers all requests and their QoS and allocates resource accordingly. Once a BE flow has had an initial grant, the other requests can be piggy-backed with sent data to avoid contention. So you typically only have to go through contention for the initial packet of a stream, even for BE.
For voice, WiMAX can use UGS (Unsollicited Grant Service). Based on the voice codec used, the BS will sponaneusly grant the needed amount of air resource at the needed period to the CPE. There's no latency problem anymore (the WiMAX frame is at 5 ms) and it's totally predictable. Of course, this requires tying the voice system to the WiMAX back-end so that the proper scheduling is applied to the voice flows. WiMAX has everything needed to support this.
So when the CEO of Bozzos Networks complain about 1000 ms latency for voice, it can only happen if they took some severe short cuts and use BE for voice traffic in a severely overloaded (under dimensionned) cell. It's easier to put the blame on the technology than to admit you don't really have a clue about what you're deploying...
I'm ready to bet that the vendor they used didn't have the backbone support ready to use UGS for voice. The CEO says that wireless DOCSIS worked fine. Hear this: the WiMAX QoS framework is directly derived from DOCSIS! There's UGS in both case, same name, same mechanism! Except that with DOCSIS, the back-end integration is well ready (PacketCable). And from someone knowing both DOCSIS and WiMAX, the later is better suited for wireless.
Lastly, the average cell size for NLOS deployment is typically ~1 km (this depends on the frenquency). If you deploy indoor-outdoor devices you're line of sight and can go much higher. The 70 Mbps and 70 km that some WiMAX marketroids have hyped have been a joke for all wireless techies since day one. Anybody serious knows what to expect in term of cell size / coverage, and plan accordingly. Hearing a CEO discovering this and publicly whining about it is a bit embarassing indeed. He may be the only guy in the industry that took these figures at face value!
I'm eager to see some wireless big boys deploying, we can hope to see better results. Small operators should wait until the technology has been cleaned-up by the big boys before moving into the field. Wireless is extremelly complex, and has in everything it always take some time to get to a stable, production level quality.
Actually, all half-duplex ethernet, regardless of physical media, even up to 100 Mbps (Gig-E doesn't support half-duplex), uses CSMA/CD
And any system that uses a "contention" based method to determine who can transmit, will be prone to jitter, due to the randomness of when a device wants to transmit. This includes 802.11, which uses CSMA/CA (collision advoidance, not collision detect like ethernet).
Most wireless technology that has to guarantee specific latency to multiple clients uses some sort of static TDMA or TDD
WiMax / 802.16e does support QOS (and dynamic TDMA), including realtime polling service for VoIP applications. Perhaps the telco was just using Best Effort configuration.
I used to deploy a lot outdoor wireless gear from Proxim (and previously Orinoco). Most of their gear either used a proprietary MAC in the same band as 802.11 (ie, 2.4 GHz ISM band), or some completely proprietary concoction, such as some of their circular-polarised gear in the 5 GHz ISM band.
Orinoco were one of the first companies to solve 802.11's "hidden node" problem, where peers could be NLOS (and thus unable to hear when other TX'ed), by using a polling system, controlled by a master node that could see all peers. A standard 802.11 would have performed very badly in such a scenario, due to frequent collisions. This proprietary system was essentially TDMA, and ensured relatively consistent latency (apart from dropped frames due to RF noise).
Proxim Tsunami MP gear used a strict TDMA system to ensure that peers could only TX when they were given permission to. The base stations had a 60 degree beam width, and to get 360 degree coverage, you simply put six of them together in a pod, on alternate channels. They used GPS time signals to sync all units in the pod, ensuring that all of them had synchronised TX slots - they'd all transmit at the exactly the same time, then go into RX mode at the same time.
They also had a similar system called a QuickBridge, which could run at up to 54 Mbps aggregate bandwidth - and unlike 802.11g, this did actually have a throughput of 54 Mbps, not 20 Mbps (which is the best I ever saw from 802.1g). It used a TDD system, as it was only two units in a configuration. Using some simple traffic shaping, we successfully blasted a 2 meg voice circuit across it, had terminal server traffic running (even fancy screensavers within the terminal session to stress it out a bit), while copying large files in BOTH directions across it. All performed perfectly, and voice was crystal clear. Ok, the traffic shaping was partially responsible, since it policed bandwidth and prioritised the voip - but the main thing to take note of, is that TDD/TDMA systems can have heavy traffic in both directions without causing massive amounts of retransmits.
There's nothing magical about WiMax. Other frequency ranges, other protocols, that's about it.
The only interesting thing about it is that it's not operated by traditional telcos.
But remember, what traditional telcos sell is not telecom, they're SELLING UBIQUITOUS telecom.
An untraditional telco would have to sell at a nonzero price ubiquitous. If they sell at zero price (or truly flat rate), a smartass will monopolize all access and resell it at real market price (what people are truly willing to pay). If the service is only sporadically available, no one will want to pay for it, or they would be better off setting up a fix line connection at the only place it works. If they comply to the two conditions, they are definitely traditional telcos.
In the long run, WiMax is bad for the consumer. As I explained above, the business model behind WiMax can only be the "traditional telco model". But now we have two technologies with incompatible end user hardware, incompatible operator hardware. Nokia and Alcatel Lucent will sell less copies of their products to operators, thus the price will rise. Nokia and Alcatel Lucent will ask for higher fees from the opco, guess who will pay the bill. Nokia and Motorola will sell less copies of their products to end users, guess who will pay for the relatively higher cost.
Furthermore, with WiMax vs 3G, there are now not one, but two markets for mobile data and voice. Barrier to jump from one to the other market is nonzero for the consumers. Each of the individual markets is also smaller, hence less competitive.
Fuck WiMax
If it's not the broad spectrum de-regulators, it will the digital spectrum land grab speculators. I was talking to a friend who is a broadcast TV engineer and some European countries have switched analogue TV off entirely. Some number of people with 1991 TV sets just couldn't switch to digital or if they could afford it, couldn't grok the new user interface. A significant percentage of elderly folk just said "fsck it" and gave up on TV entirely.
Over here in Australia, our FM band is being switched off to make space for digital allocations. The "big picture" will be far more important than individual circumstance. Presumably sets will drop in price as the user base grows.
The open spectrum people are the least of your problems, the digital spectrum people have a lot more cash and backing to take over your AM spectrum.
Too true. But maybe not in the way you expect...
Xix.
"Everything is adjustable, provided you have the right tools"