Mar 11, 2003 06:11 AM
80219 Views
(Updated Mar 11, 2003 06:12 AM)
GSM Versus CDMA
The Global Standards for Mobile is based on Time Divided Multiple Access and CDMA/WiLL is based on Code division. OK. What does this all mean for a common person? I put below my understanding and the results on seeing websites and opinions of my friends(including many MS brethren)
Superior Technology
GSM and CDMA are apples and Oranges. Both offer the same quality and data access speed. Saying one is superior still gets debated(like the Microsoft or Java debates – never ending and never getting conclusive).
The Packet Divided access in Japan(i-mode) is technologically the most superior with Voice, Data and Pictures travel in the same channel in different packets. Of course this makes sense when you have the infrastructure in place. Japanese have their own chain of Japanese Content Providers, Switch/Infrastructure Providers, and Handset Providers. So, they have become a hi-tech cocoon in their own way.
Relevance of Technology
Now, this is where CDMA has a clear advantage. They use the entire frequency spectrum and hence can have the broadcast happen at very high signal strength spread over bigger radius. For a city like chennai(a typical Indian city), the GSM grids requires something like 130 base stations to cover the city. The time slicing circuit is indeed costly and my friend working in BATATA tells me it costs 96 Lakhs for a base station.
WiLL requires some 10 base stations in chennai as they beam all frequencies received by everyone(something similar to Ethernet broadcast in LAN where every computer listens to every packet and the intended recipient makes sense of message and acts upon it). Only the Handset, which incorporates the code, can decipher the signal and transmit too. WLL uses CDMA to loop to mobile phones.
CDMA is a proprietary of Qualcomm and is in use where the Mobile service provider will have to serve bigger area like US. GSM is preferred where concentration of mobile phone providers across geographic area is more(More than 2 Service Providers in a 500 Km radius) and individual base stations are the best option – Europe.
WiLL is invented by Ashok Jhunjhunwala a professor of IIT who is noted for his indianisation of technologies.
Cost
The GSM calls for heavy capital investment in the form of costly base stations with negligible operating cost. All the cost we pay them is their capital cost. WiLL have very less base stations, cheaper equipment and Shared costs on linking stations like optical fibres etc. This reduction in initial investment enables them to offer mobile outgoing at 1.20 per minute and incoming free(better position to negotiate calling-party-pays formula). In WiLL, the mobile handset cannot be reused when you switch suppliers. You are getting an unwritten commitment from the subscriber, which leads to further reduction of charges.
This tells us why Skycell went out of business because they cannot manage funds to counter reducing prices and how Reliance is pumping funds from RIL reserves to Infocomm and of course BSNL(Hee Hee unlimited tax payer’s funds J They have fixed line profits diverted) Since capital costs are manipulated in the era of diminishing interest rates, we will never get true picture.
Data Transfer
Negligible difference in data transfers rates between a GPRS(GSM) and CDMA. In India CDMA have not started data services yet. In fact, if you get a GPRS phone and activate 4 inward and one outward channel, the instrument is very fast in accessing WAP sites.
Security
Every software developer will vouch for this. More open a standard, more chances of bugs being pointed out and rectified. This applies for security. More open the security framework, less chances of a hole in it.
GSM has this 800 page key encryption algos a secret. Basically there are 2 levels of encryption, one is for the frequency(so that any guy with a radio transmitter cannot detect the frequency which is set dynamically) and the other is for content(Even if you receive the frequency, you cannot demodulate to voice). The algos are noted as A3 and Kc respectively. It is POSSIBLE for someone to put fake base station(Employees of GSM provider?) and it is only a matter of time before a good hacker cracks these mathematical algos. Just like internet is hackable, GSM is clonable. This means somebody can then recreate the SIM card codes and can make and receive calls on your behalf. This prevents development of m-commerce in a big way.
CDMA on the other hand says it plainly. I have the code. You can crack this provided you try ‘1 followed by 33 zeros’ times. Since it uses entire spectrum, base station snooping is not possible.
I am not saying somebody can make over-the-air hack attack and clone your Airtel phone but GSM refused to give a declaration saying it CANNOT be done. This I would say is a fundamental flaw on the part of standards governing body.
Bottom line
Cut the jargons man. Tell me do I go for CDMA or GSM. Simple question but I ‘m afraid the answer may not be one.
If you already have a GSM – don’t invest on new handset(Hope you are not gullible to read between the lines of reliance offer of free handset) The Plan of RPG/Airtel/Hutch allows you to have free receiving, mobile to mobile free and mobile to land line 2 Rs/min with 350 Rs/month. It’s a good offer
If you don’t already have a GSM, go for Cell One or Reliance. But note that GSM prices are expected to comedown next year as you are just paying capital cost. Sticking to Reliance(according to me) may not be prudent. But then you never know.
