===Power control and QoS===
Transmission power of mobile station is proportional to power control law, which is a function of distance from the base station, transmission rates, interference level (number of active users). In this method , the Bit Error probability of the multi -rate CDMA mobile station is calculated at the Base station using transmission rates of the mobile.The Optimal optimal power control functions are derived based on the Bit bit error probability at the base station and these power control functions are transmitted to the mobilehandset. The mobile calculates the optimum power using DYNAMIC PROGRAMMING dynamic programming and transmits its data at this power level. It is of interest to note that the optimum power level is related to power index which will determine the spreading gain and hence the overall bit rate. Thus the optimum power level is acheived by transmitting the data at the calculated bit rate.[[Media:IEEE-2.pdf]]
==Conclusion==
Substantial amount of research has been done in the field of QoS in CDMA communication system in the year 1998-99 and this has led to the invention of multitude of methodologies ranging from power control to Rate matching and so on with the sole aim of improving QoS.