Apr 15, 2003 10:15 PM
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(Updated Apr 23, 2003 12:09 PM)
With the launching of CDMA based mobiles, a few new abbreviations have flooded the market and 2 of the prominent ones amongst them are: CDMA and WLL. Though, thanks to the marketing_tactics_, their introduction was done in such a careful manner that made a lot of people believe that WLL with CDMA go hand in hand. Here, I shall attempt to resolve this confusion along with giving a brief overview of GSM and CDMA w.r.t. WLL.
WLL, which stands for Wireless in Local Loop, is nothing but a SYSTEM that connects subscribers to the Public Switched Telephone Network(PSTN) using radio signals as a substitute for copper(i.e. the conventional land-lines) for all or part of the connection between the subscriber and the switch/exchange. Local Loop is better known as the User Access Network, and so in layman terms, WLL is like being wireless in the network, closest to the user.
WLL can be implemented across 4-5 categories of wireless technology, the important one being Digital Cellular in Indian context. Further in this category, there are technologies like TDMA(forming the basis of GSM), and CDMA along with a few others. Each of these technologies have a mix of strengths and weaknesses for WLL applications. Although GSM currently dominates mobile digital cellular(around 2/3rd share), there has been little activity in using GSM on WLL platforms. This is because of design of GSM Architecture was to handle international roaming, as a consequence of which, it carries a large amount of overhead making it unwieldy and costly for WLL applications. Off late, though, there have been some developments to introduce GSM in WLL as well.
On the other hand, CDMA, a spread-spectrum modulation technique, employs a wide range of frequency for transmission and the system's low-power signal is spread across wide-frequency band. It offers higher capacity than the other digital standards and relatively high-quality voice. An additional advantage is that CDMA is inherently secure. GSM on the other hand has to use 2 levels of encryption, and with regards to India, the variant of the encryption algorithm(A4.1/A4.2) that is allowed, has been proven to be weak and prone to a variety of attacks.
Thus, the bottomline is though that WLL is related to CDMA as much as it is related to GSM, but as far as deployment is concerned, CDMA definitely has the upper hand. It now totally hinges on to the service providers on how to make the best use of it.
