Survey and Challenges of Carrier Aggregation in LTE-Advanced
The technology evolution in mobile communications in last few years, has led to an exponential growth in video downloads and the increase in data usage due to smart phones. This resulted in requirement of larger air interface bandwidths. Hence, the spectrum aggregation has recently received much attention due to the quick increasing of services. The first release of 3GPP LTE provided extensive support for deployment in spectrum allocations of various characteristics, with transmission bandwidths ranging from 1.4MHz up to 20MHz in both paired and unpaired bands.