While I have blogged in detail about the technical challenges of the deployment of 802.11a/b/g, and now "n" over a distributed antenna system model over the years, I have never really discussed the financial and upgradable cost factors. This definitely needs to be looked at.
The whole premise of combining these services was marketed, at least in healthcare; that you only had to break into the ceiling once. All the WLAN access points could be co-located in the IDF (wiring closet), and essentially the passive or hybrid DAS was "future proof"...you never had to touch it again. Sounds good from a pure marketing spin to the executive ranks; but is again reality when you have to make it work. So some implementations went forward, others felt that this was not technically, risk wise, or financially attractive. Thus some made the decision to install a DAS, but to install the WLAN separate from the DAS. Others said, we we will install a WLAN (802.11a/b/g), with a DAS. For the sake of this blog, I have left WMTS off regarding discussions, but this is a whole another topic.
Fast forward, now 2011
That has all changed with the approval and adoption of 802.11n
Remember a DAS was never really designed for diversity, this was simply not needed for cellular or PCS (the model and frequency range), but in the case of WiFi; diversity overcomes multi path. Multipath is a bad thing for RF. Diversity simply helps overcomes nulls "dropouts". So in the sake of having the access points connected to a DAS via a diplexer/triplexer, or combiner in the IDF, the secondary attenna for diversity was often simply terminated by a physical antenna block on the "b" side. a, primary, b, secondary. For 802.11a/b/g, yes this may not be a big deal, however see my previous blog regarding 802.11a.(link budget challenges)
Now the question comes up how do those existing installations that went with a combination of of 802.11a/b/g, upgrade to 802.11n? Well they are in my opinion going to have to go into the ceiling "again" and install a lot of coaxial cable to support MIMO. (Multiple Antenna elements are required for MIMO). Oh yes, let I forget, you will need a whole new propagation model to be developed. So this whole issue of a "future proof", argument is pretty much blown out of the saddle. I guess some CIO(s), that bought into this previous model and spin, will have to convince their executives to obtain both more CAPEX and OPEX $$ for a further redesign.
If a hospital installed say Cisco Systems and/or Aruba Networks previous discrete (meaning stand alone and separate from the DAS), and wanted to upgrade from 802.11a/b/g to 802.11n, yes they would have to change out AP(s), maybe move a few around, but they would not from the IDF, then have to run extra coaxial infrastructure, (depending upon say 3x2 MIMO) to support 802.11n WLAN over a DAS. For this model to perhaps even to work means not changing out AP(s), yes, but breaking into the ceiling big time to design and install a duplicate entire previous DAS installation (passive coaxial infrastructure). It becomes a whole proprietary business model.
In previous, the whole marketing business model was that everything could be done from the wiring closet. Remember, hospitals like to control infection, re-installing coaxial cable to antenna end points is not good.
It seems that some technical integrators make the claim that 802.11n can actually work on "new" implementations from a technical factor. That word "technical" has to be defined as per the attached from Cisco Systems. You would think as the world wide leader in networking and wireless, they would know a few things.
Also, I should say when comparing business and financial models the price deta for RTLS services, with 802.11n over a DAS is 50% higher than simply just installing discrete (stand-alone) Cisco CWAPP to include the location based controller. Makes a lot of financial sense to simply install the DAS for what was intended for and keep the WLAN simply separate. Again, this is my opinion.
So you have to ask yourself from an upgradability standpoint or new implementations, does it really make business or financial sense to stil drive forward with the messaging to combine 802.11a/b/g and now "n" to the healthcare market in 2011? Especially when an industry is under huge financial pressures to save costs..and to decrease risks. What do you think?
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