Friday, July 13, 2012

DAS Deployments for Public Safety Broadband...the forgotten piece to the puzzle.

So New York wants to modify all their existing phone booths into Free Wifi Hotspots. This must be a push for equality because the last I heard only the drug dealers and prostitutes used the booths. Now the drug dealers and prostitutes can also get smart phones with data access. That means your common drug dealer can now open up and manage his Craiglist postings with relative ease and unrestricted geographical locations and the prostitute will be able to geo-locate Johns for easy access and corner positioning.

Funniness aside though, DAS (Digital Antenna System) deployments have nothing to do with Wifi. They are actually based on extending the cellular signal (2G, 3G) throughout a restricted location (for the Tier 1 carriers most of the 2G is being replaced with 4G). In essence, if you have a lousy cellular connection at your work…then you can put up a DAS antenna to extend the coverage, buts its primarily used for your cell phone…not your data connection. Although some of the solutions do come with Wifi built-in as well. Of course maybe Femto Cells or some type of homogenous DAS solution could be used. 

As with the complexities of integrating LMR and LTE together for Public Safety, so will extending the digital signal of cellular. As it stands today the LTE technology is mainly driven with IP packet designs, not cellular TDM, therefore one must make design considerations to include them. Although, I believe that most OEMs see this feature as doable; I would imagine that, initially, most of the extended network scenarios forLTE with DAS would be a bandaid of LTE dongles, or hotspots -- filling the need for a type of DAS solution -- unless the intended DAS deployments are intended to only interface for cellular commercial connectivity. In short, you need your DAS solution to integrate and extend LTE. 

These LTE hotspot tools are different than a DAS cellular extender. They basically extend the LTE signal which is primarily an OFDM (Orthogonal frequency-division multiplexing) signal with a little TDM, and based primarily off IP traffic making it data driven...not voice packet driven. Of course I may be wrong, and would love the more technical savvy to educate us, but for now it will have to do. But, either way, building the Public Safety Network based off LTE we will need to cover many such aspects and I don’t believe the Technical Advisory Committee to the FCC, nor the Interoperability Board, have brought these types of ancillary technical design issues to light…yet. 

Case in point: The LA-RICS RFP calls for an LMR, LTE and DAS deployment.

It would be nice to see the tactical and technical plans for deploying the three solutions together. From what I can see their will be no holistic design encompassing an LMR, LTE and DAS solution; which ultimately results in a complex design that requires a wide girth of a footprint and power requirements exploding the initial cost and equipment estimates for the deployments. Plus, what will the management center look like in running simultaneous LMR, LTE and DAS (2G, 3G) technology layers? Could you imagine having swivel chair assignments between three distinct telecommunication solutions that are a business in itself? And we haven't even started talking about the NOCs or data centers yet.

Just some guy and a blog…..

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