Investigation of rate-loss due to limited feedback in LTE-Advanced distributed antenna systems

In wireless communications, interference is known as a major restriction in achieving system capacity. Recently, distributed antenna system (DAS) has received considerable attention due to its potential to mitigating interference and path-loss. In LTE-A system, a transmitter and a receiver are collaborated together to tackle the interference. To do so in the frequency division duplex system, channel state information (CSI) of the downlink channel must be shared amongst transceivers via a limited feedback technique. In this regard, this article evaluates and compares the performance of DAS and centralized antenna system (CAS) under imperfect downlink CSI, where practical system restrictions such as out-of-cell interference, path-loss, and small-scale fading are taken into account. The system performance is evaluated in term of cell throughput, where a LTE-A standard compliant simulator is utilized for simulation. The results reveal high dependency of system performance to the accuracy of CSI, where system throughput severely degrades under imperfect CSI. In contrast to CAS, DAS is more robust again imperfect CSI, where under imperfect CSI, DAS significantly outperforms CAS in term of cell-throughput.