Carrier aggregation in power limited devices over Rayleigh fading channels

In this paper we analyze, both theoretically and through simulations, the aspect of carrier aggregation in power limited devices over Rayleigh fading for use in future wireless systems. We derive analytical expressions for the probability of transmitting over KK carriers, as well as an upper bound on the gain achieved with carrier aggregation and the probability of carrier aggregation yielding a certain gain over single carrier allocation. These analytical expressions are verified through simulations. The analysis gives insight to the average SNR one needs to obtain the desired gain with carrier aggregation. As suspected, carrier aggregation does not increase the spectral efficiency in the uplink of a wireless system and in the low SNR regime one does not achieve any gain with carrier aggregation. However, carrier aggregation can be employed to achieve the 4G bit-rates as stated by 3GPP, given that certain users have very good channel conditions.