I think it should be fair to call it "heavily distributed multi-user MIMO". In fact they are forming the beam by relating to the multiple AP as a dezentralized antenna array, a concept that should be well known in radar applications and acoustic beamforming.
Btw. an interessting press release about NSN's centralized-RAN solution:
Interesting. I would have said that the main difference is their reliance on aggreagating multiple APs signal to make the desired signal. This could be considered MIMO, I suppose, but only very loosely. It would be feasible to have this and MIMO operating together, if I understand the system.
Note that any MIMO system also has to do channel estimation, and especially if the MIMO is used by mobile devices, the channel estimation has to be done quickly. So even this aspect is not new.
I think the main differences between this DIDO and MIMO are that the different APs may be a lot further apart with DIDO than your typical single MIMO antenna, and the propagation paths are used individually by each client system.
Here is a good viewgraph tutorial which explains how the signals are decorrelated in MIMO. I think you will note the similarities between the two schemes.
What we see here offered is a distributed MU-MIMO technology, similar to LTE-A's centralized CoMP. And thus it will inevitably face the same problems, e.g. cell edge performance, low mobility, unfavorable channel correlation, etc. Despite of this the claimed spectral efficiency gains and the promised scalability in my opinion do not hold for the LTE latency requirements and this will be sharpened further with 5G.
But one truly intriguing aspect of this product is the opportunity to provide a low cost solution to one of the Telco's problems, namely how to cover temporary events attracting huge amounts of users. A comparison of the power consumption, size and price of the offered AP to a state of the art base station should ring the bells for a nice niche market opportunity.
Anyway the future of beamforming in celuar is more than bright and the guys deserve kudos for the work they do. Regarding the statements made in the press... well, we all know that maketing doesn't go with engineering very well =)
It will be interesting to see how this compares to dense deployments of small cells operating under SON, particularly with carrier aggregation and LTE over unlicensed bands. I think the band width density on that kind of deployment will challenge this, with no change to existing mobiles, no change to exiting protocols. The deployment will require more difficult backhaul engineering, but even that, using microwave aggregation is not that difficult. Small cells are small enough to build into building facades or into street lighting fixtures, so siting them is not an issue as it is with conventional towers.
I still think that what Artemis has achieved is very interesting, I just don't know if it makes commercial sense. Small cells have evolved rapidly under LTE, which was engineered to take small cells and Self Organizing Networks into account. I think you are going to see the results of that in 2015, particularly in regards to Heterogenous networks.
The technology will probably be better for static devices such as TV live streaming either through dedicated hardware or through some kind of mobile device. The spectrum loading is already difficult with poor network in moving devices. Also in congested areas the technology will be difficult to implement as there will be too much interference.
What is the processing load to handle handsets that are moving? Say at 25 MPH on a bus. Do you have to have an overlay network with traditional towers handling clients moving above a certain rate and this network handling more stationary clients?
It's not just about the data center, there's plenty in the channel model matrix that has to be performed outside of the data center. The requirements for this kind of thing are massive. It's a major undertaking.