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).

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.

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)?

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.