Kirt's Cogitations™ #230
These original Kirt's Cogitations™ may be reproduced (no more than
5, please) provided proper credit is given to me, Kirt Blattenberger.
Please click here
to return to the Table of Contents.
Cog·i·ta·tion [koj-i-tey'-shun] – noun: Concerted thought or
reflection; meditation; contemplation.
Kirt [kert] – proper noun: RF Cafe webmaster.
is the moniker given to the U.S. Marines’ "Code Talkers" in World War II. Windtalkers were Native American, Navajo
Indians who employed their very exclusive tribal language to encode/decode messages in the Pacific Theater, where
secure communications were utterly essential but difficult to maintain. Since few people knew the Navajo language
– and especially not the Japanese – breaking the code was impossible.
My borrowing of Windtalkers to create
the new word “Windowtalkers™” is based on the very common occurrence of indoor cellphone users being drawn like
flies to building windows in desperate attempts to make calls. This phenomenon can be observed in the workplace,
airports, grocery stores, and just about anywhere else steel and concrete structures are present. Where I
work(ed), we had a glass-domed atrium in the center of the building, and there was almost always at least one
person standing on the upstairs deck exploiting the open sky exposure to conduct a call. I don’t quite know why,
but talkers tended to pace the atrium area while Windowtalkers™ stood in one place against the panes.
first inclination is to ask, “Why, in the year 2007, is Windowtalking™ still necessary?” Then, I realize that I am
referring to a technology that is really only about fifteen years old, so the situation does not seems so
ridiculous. Help is on the way, however, times two.
There are two completely different approaches to solving the Windowtalkers’ dilemma. The official term given to
the solutions is Fixed/Mobile Convergence (FMC). One scheme, dubbed “unified mobile access” (UMA) solves the
problem by creating gazillions of “femtocells” that are deployed in homes, offices, laboratories, stores,
airports, bus stations, terrorist caves, and any other environment where poor cellphone reception is experienced.
These femtocells operate in the same frequency bands as existing cell bands (GDM850/900, DCS1800, PCS1900,
UMTS2100, etc.) for both GSM and (W)CDMA. Effectively, the femtocells are miniature cell towers with all the
necessary Rx/Tx capability and applicable upstream and downstream switching and call processing functionality.
This system allows all existing phones to be used without the need to deploy a whole new population of dual-mode
(or multimode) handsets, PDAs, etc. Theoreticians have done the math and say such a complex, dense operational
environment will work (I seem to remember similar levels of confidence for Bluetooth up until that 2001
CeBit trade show in Germany, when
the network crashed with only 100 devices active).
The second concept, termed "integrated multimedia
system" (IMS), exploits the already deployed WiFi hotspot network (and its rapidly growing base) to work with
phones and PDAs that have WiFi connectivity built into them. Automated handoffs between VoIP and cell towers would
occur as users move between coverage areas. The grand hurdle for this system is convincing people to shell out
money for new phones with dual- or multi-mode capability. Nokia, Motorola, Samsung, et al, have been producing
some of these phones, but the prices are typically much higher than standard models.
Of course, there is
passionate debate from both camps as to which route makes the most sense. The pro femtocell (UMA) people argue
that since bandwidths are already increasing to accommodate Internet data streaming, and components are evolving
rapidly to become even more accommodating, it does not make sense to add another radio to phones already running
quadband GSM, dualband WCDMA, Bluetooth, Global Positioning System (GPS), FM radio, and near field communications
WiFi advocates (IMS) dismiss the “additional radio in the phone” argument based on the
fact that all the technology already exists, and mass adoption would drive prices down. Besides, not all phones
and PDAs would need to have every other radio type. Also, broad coverage WiFi networks are already installed, work
just fine (excepted in the densest of environments), and already support much higher data rates than do cellphone
Personally, I am in the IMS camp at this point. The concept is still young, and at least there is
enough infrastructure in place between cell towers and WiFi hotspots to implement a system today without adding
any hardware other than a dual-mode phone. Even the IP software exists. In fact, there are prototype
implementations running today. Over time, as the entire technology matures and people replace their phones when
renewing plans, the WiFi equipped phones can be phased in.
It just occurred to me that there seems to be
one other unique spot in every building that cellphone signals seem to propagate perfectly that could obviate the
need for this new technology at all – the bathroom. It seems there are always people chatting away while in the
stalls or standing at the urinals with no reception problems. Maybe it’s the copper plumbing acting as a resonant
Windowtalkers™ and Windowtalking™ are trademarks of RFCafe.com
|More than 8,000 searchable pages indexed.
Your RF Cafe
Progenitor & Webmaster
Blattenberger ... single-handedly redefining what an engineering website should be.
(Seize the Day!)
My USAF radar shop
Airplanes and Rockets:
My daughter Sally's
horse riding website