1)why can waves with very low frequency follow earth surface?why are they not used for data transmission in computer networks?

2)what are the two different approaches in regulation regarding mobile phone system in EUROPE and USA and what are the consequences?

3)why in the international availability of same ISM bands important?

4)what are the main problems of signal propogation?

5)why do radiowaves not always follow a straight line?

6)why is reflection both useful and harmful?

7)what are the main reason for using cellular system?

8)How is SDM typically realised and combined with FDM?

9)What limits the number of simultaneous users in TDM/FDM system compared to FDMA system?

10)which type of services does GSM with example offer?

11)compare the current situation of mobile phone network in INDIA

12)what are the efforts to find a common system or atleast interoperable system?