An analytical approach for evaluating the correlation properties of subchannel fading for carrier aggregation

摘要

Carrier aggregation (CA) has been proposed as a key feature of the 4G cellular networks to achieve the very high data rates. It is known that the correlation between the subchannels, including both small- and large-scale fading, is critical in determining the performance gain we can obtain from the multicarrier transmission. However, due to the prohibitively high complexity and cost in simultaneously probing multiple non-contiguous subchannels by a channel sounder, this issue is less explored yet. In this paper, we develop an analytical model to study the correlation of the small-scale fading (SSF) between two arbitrarily separated subchannels. We first propose a new propagation model for the Nakagami-m fading of the subchannels, based on the delay spread property and exponential power decaying of the multipath components (MPCs). Then the level-cross-rate (LCR) of the subchannel received power with respect to frequency is defined and derived. Third, a Markov chain describing the variation of the received power among different subchannels is proposed, based on which the correlation coefficient between two subchannels is obtained. The developed analytical model and the acquired new insights on the subchannel correlation could provide further understanding on the spatial and frequency properties of the multicarrier channels, and help to guide the efficient designs of the CA communication systems.