Impact of time and frequency offsets on cooperative multi-user MIMO-OFDM systems

We study impacts of frequency and time offsets on cooperative multi-user MIMO-OFDM systems. In such systems, frequency offsets cause multi-user interference in addition to the inter-carrier interference effects typically seen in traditional MIMO-OFDM systems. Also, the impact of time offsets is more severe since the time offsets are larger due to transmitter synchronization imperfections and different propagation delays from the transmitters to the receivers. We derive an expression for the SINR seen at the receiver, showing especially how frequency offsets rotate the equivalent channel, thereby causing precoding imperfections. We simulate the interference impacts in the context of LTE-Advanced with realistic assumptions. Simulation results clearly show that the impacts of time and frequency offsets are more severe in cooperative MIMO-OFDM systems than in traditional MIMO-OFDM systems.

[1]  Jun Zhang,et al.  Coordinated Multi-cell MIMO Systems with Cellular Block Diagonalization , 2007, 2007 Conference Record of the Forty-First Asilomar Conference on Signals, Systems and Computers.

[2]  Emre Telatar,et al.  Capacity of Multi-antenna Gaussian Channels , 1999, Eur. Trans. Telecommun..

[3]  Huaiyu Dai,et al.  Cochannel Interference Mitigation and Cooperative Processing in Downlink Multicell Multiuser MIMO Networks , 2004, EURASIP J. Wirel. Commun. Netw..

[4]  Donald C. Cox,et al.  Mathematical analysis of the impact of timing synchronization errors on the performance of an OFDM system , 2006, IEEE Transactions on Communications.

[5]  Marc Moeneclaey,et al.  BER sensitivity of OFDM systems to carrier frequency offset and Wiener phase noise , 1995, IEEE Trans. Commun..

[6]  Wei Zhang,et al.  SINR Analysis for OFDMA Systems with Carrier Frequency Offset , 2007, 2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications.

[7]  James K. Cavers,et al.  Carrier Frequency Offset in Coordinated Multibase MIMO Narrowband Systems , 2008, VTC Spring 2008 - IEEE Vehicular Technology Conference.

[8]  V. Jungnickel,et al.  Synchronization of cooperative base stations , 2008, 2008 IEEE International Symposium on Wireless Communication Systems.