Closed Access OFDMA Femtocells under Timing Misalignment

In the uplink, while macrocell mobile stations (mMSs) are synchronized to the macrocell base station (mBS), their signals will arrive asynchronously at the femtocell base station (fBS). For OFDMA, if the timing misalignment among the mMSs is greater than the cyclic prefix duration, intersymbol interference (ISI) and intercarrier interference (ICI) will occur in the received signal at the femtocell. In this paper, we show that the average performance of closed access OFDMA femtocell under timing misalignment depends on its distance to the mBS and on the number of mMSs. Simulation results show performance degradations in ergodic capacity and symbol error rate due to ISI and ICI induced by timing misalignment of the mMSs.