Expert: Cezar L. Palconet - 5/5/2010

Question
why  channel  bandwidth  is 200khz.  in  case  of  GSM , why  its  not more  tan  that as we  know  that  by  increasing  it  we  can  increase  our  data  rate ,  capacity.

Answer
Hi Vikash,

GSM was originaly conceived as a pan european mobile phone system, so focus on increased troughput as a fully data centric system was never a major part of its conceptualization, it was the number of call traffic and roaming mobility (pan european) that was the primary goal of GSM, however since GSM was concived with a high efficiency on access (Due to handover) and modulations (GMSK)simple data, like SMS and MMS was easy to implement trough GSM, if you will look at the bandwidth of the earlier analog, it uses 12.5 and 25 KHz. per channel, that is not further away true for GSM, where the 200KHz. x 8 Timeslots = 25 KHz.

The initiative to move towards datacentric mobility is best exhibited by the evolution of the mobile phone system.

systems like CDMA ,Wimax, and LTE are data centric systems and voice is just secondary and not the other way around.

regards.