The Mobile WiMAX takes on 3G (as 6th standard)
WSIL News & Views October 22nd. 2007, 2:10pmI just heard that the mobile WiMAX standard (IEEE 802.16e) was approved as the sixth international standard for the IMT-2000 third-generation (3G) telecommunication platform, by the International Telecommunication Union (ITU) today. The decision may accelerate the transition from the 2.XG to the 3.XG, but it depends on the operators. Also, the competitor for the mobile WiMAX will be, in my point of view, the legacy WiFi or the IEEE 802.11n standard.
When I came to Austin permanently in July and took a metro bus, I was so surprised about the wireless internet accessibility in a moving bus. At first I thought it was the mobile WiMAX, but it was not. Still I am not sure it is the EDGE (2.5G) or the WiFi (APs along the path), but it is fast enough (for a grad-student) to check my email, and moreover, it is FREE. For me, there’s no demand to use the mobile WiMAX, especially if I pay for it. I can use free WiFi on the campus, in a bus and even in my home (thanks to my reckless neighbor).
I am curious how the operator (such as Sprint, who is implementing the Mobile WiMAX around DC area) take advantage of the official approval today. They may combine it with legacy system to reduce the deployment cost, but the money for the FCC to license the band (5 - 20MHz) will be huge. if they convince some potential users (including me) to pay some money for the service, the money doesn’t matter. But if they don’t, I think they may not win in the 3G game - a step stone to the promising 4G, regardless of the new technological features in itself.
What is your opinion?
October 23rd, 2007 at 3:32 pm
Insoo…I think this is an intriguing topic.
Personally I do think WiMax will be successful. I know that I would be a willing subscriber to mobile broadband as long as the link was not handicapped like current mobile internet applications (i.e. unlimited usage without application restrictions at a monthly fee). Sure, you can access wireless hotspots virtually everywhere you go in major cities. However, it’s not always reliable (equipment failure, interference, etc.), and many times hotspots are operated by TMobile, AT&T, etc ask for a ridiculous per hour usage fee. I know I’m a bit more stingy than the average consumer, but I refuse to pay anything more than a buck or two for a service I’m already paying for at home. Additionally, the US is a big place, most of which is not within a city. For these rural areas, WiMax is perfect for internet-on-the-go.
Mobile broadband may never deliver the rates that wired internet service providers supply. More than likely we’ll get at best 100-1000kbps connections with WiMax. However, in the US, cable modems and DSL don’t do much better. I’d get rid of my cable modem faster than you can say “Adios Time-Warner” if someone offered me a mobile internet connection that guaranteed 250+kbps at the same price as my current cable modem. Those of you that need the internet for high-bandwidth multimedia content may feel otherwise, but there are a significant amount of us who just need the internet for information (at any time we want it).
I can’t speak for Asia or any other continent for that matter, but in North America I think WiMax makes sense.
October 24th, 2007 at 12:02 pm
From reading a recent DailyWireless post, it looks like Sprint will deploy WiMAX in the Austin area by next April. As my wireless connection at home is quite slow, I am quite curious as to whether or not my apartment complex will switch over to WiMAX…
On a slightly different note, I read in the same post that Nortel isn’t high on beamforming (they claim that beams can’t stay focused in urban multipath environments), and they believe that “MIMO is the way to go.”
This raises two questions for me: first, is it true that beamforming isn’t a viable transmission/reception strategy in an urban environment? Second, is it common in industry to distinguish between “beamforming” and “MIMO” (it seems as if spatial multiplexing and space-time coding are lumped into the latter category)?
October 24th, 2007 at 2:12 pm
Surely they mean the classic definition of beamforming….?
October 24th, 2007 at 3:09 pm
Actually Steve, I think at some (high) level both “classical” beamforming and “digital” beamforming are very similar. Both need information about the multiple-antenna wireless channel at the transmitter to improve signal reception. When they say that “beams can’t stay focused” they’re simply stating that wireless channel information changes very quickly, quicker than can be compensated for without channel prediction algorithms. For indoor wireless systems the coherence time of the channel allows us to use feedback easily, but outdoor channels with high Doppler really have short feasible durations for channel feedback. If you can’t use feedback, you’re left with open loop diversity algorithms and spatial multiplexing. Channel prediction algorithms are one solution and have been debated for a while. That’s one of those things I’d really like to demonstrate on our Hydra prototype.
The statement “MIMO is the way to go” really is difficult to decode, since the definition of MIMO depends on who you are talking to. I’m guessing the person you quoted was referring to spatial multiplexing and stating that if you can’t use beamforming then you might as well use spatial multiplexing. Unfortunately, we all know things aren’t that simple.
Caleb, I think it’s safe to say that your apartment complex will continue to use 802.11 style wireless connectivity with a fundamental wired source. Current WiMax chips are very power hungry with less throughput than 802.11. In order to leverage WiMax, you really have to be in that mobile application space.
October 24th, 2007 at 5:34 pm
Dear Caleb
I think Bob got the exact point. In addition to that, the 3GPP LTE defined beamforming and precoding (SM MIMO) as follows:
It has been agreed that beamforming is one of the three MIMO modes in the 3GPP LTE (The other two MIMO modes are spatial multiplexing and single steam transmit diversity). It is obvious that beamforming is a different MIMO mode other than spatial multiplexing or transmit diversity. But when precoding is considered to apply to spatial multiplexing, confusion may occur between beamforming and precoding. This is because they are very similar in form, i.e. mapping stream to antennas. But in principle there are some differences between them, as written in fig 13.
For high spatial correlation channel, beamforming can be used to mitigate inter-user interferences, especially intercell interferences for E-UTRA, to increase link reliability. Further beam-forming can also be used to increase data rates and only one received antenna is needed. It is also pointed out that increased cell edge throughput and coverage are very important requirements for the E-UTRA. To achieve this, beam-forming at the Node B using multiple antennas with narrow antenna spacing is promising.
The weight estimation principle for beamforming is also different from precoding. Beamforming can use DOA (degree of arrival) to construct the beamforming weight. The DOA can be estimated from the uplink signal which only requires one uplink RF (radio frequency) chain at UE. This kind of spatial signature can keep common for a short interval of observation, and it is insensitive to the used subcarriers. One can use the uplink signal from upper band of subcarriers in TDD operation (or from uplink band in FDD operation) to estimate the DOA, and use it to decide the beam-forming weight for which uses the lower band of subcarriers in TDD operation (or for which uses the downlink band in FDD operation).