Uplink Timing Misalignment in Open and Closed Access OFDMA Femtocell Networks

We focus on an uplink network composing of femtocell access points (FAPs), macrocell users (MUs) and a macrocell base station (MBS) employing orthogonal frequency division multiple access (OFDMA) signaling. Synchronization of MUs at the MBS results in asynchronous signal arrivals at the FAPs which may induce intercarrier interference (ICI). Given a fixed distance between an FAP and the MBS, we derive a closed-form expression for the probability of an MU causing ICI to the FAP. Then, we extend this to obtain the probability of an open and closed access FAP experiencing ICI in the presence of a fixed number of MUs, and the average number of open and closed access FAPs experiencing ICI.

[1]  Nicola Laurenti,et al.  Analysis of the uplink of an asynchronous multi-user DMT OFDMA system impaired by time offsets, frequency offsets, and multi-path fading , 2000, Vehicular Technology Conference Fall 2000. IEEE VTS Fall VTC2000. 52nd Vehicular Technology Conference (Cat. No.00CH37152).

[2]  Tony Q. S. Quek,et al.  Closed Access OFDMA Femtocells under Timing Misalignment , 2010, 2010 IEEE Global Telecommunications Conference GLOBECOM 2010.

[3]  Ismail Güvenç,et al.  Statistics of Macrocell-Synchronous Femtocell-Asynchronous Users' Delays for Improved Femtocell Uplink Receiver Design , 2009, IEEE Commun. Lett..

[4]  Jie Zhang,et al.  Access control mechanisms for femtocells , 2010, IEEE Communications Magazine.

[5]  Ismail Güvenç,et al.  ICI-Minimizing Blind Uplink Time Synchronization for OFDMA-Based Cognitive Radio Systems , 2009, GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference.

[6]  David Choi,et al.  Dealing with Loud Neighbors: The Benefits and Tradeoffs of Adaptive Femtocell Access , 2008, IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference.

[7]  Ismail Güvenç,et al.  Opportunity detection for OFDMA-based cognitive radio systems with timing misalignment , 2009, IEEE Transactions on Wireless Communications.

[8]  Ismail Güvenç,et al.  Handling CCI and ICI in OFDMA femtocell networks through frequency scheduling , 2009, IEEE Transactions on Consumer Electronics.