Auto Inter-Carrier Frequency Offset Rectification Using Conjugate Cancellation in Multi-carrier CDMA Broadband Communications
Mohamed Essam Khedr, Entesar Gemeay, Said Elnoubi, MOHAMED E. M. NASR · International Journal of Computer and Electrical Engineering · 2011
Self cancellation schemes confirmed its effectiveness for mitigating the intercarrier interference (ICI) in orthogonal frequency multiplexing (OFDM) system.The main source of ICI is the carrier frequency offsets (CFO) in mobile radio channel which destroys the carrier's orthogonality.In this paper, we employ a self cancellation scheme known as the conjugate self cancellation scheme to reduce the impact the ICI in Multicarrier CDMA systems that use Time-Frequency domain (TF or Hybrid) spreading and are used in broadband wireless communications.We show with proof that TF-domain spreading Multicarrier CDMA system with conjugate cancellation (CC) works significantly better than conventional MC-CDMA system if the normalized frequency offset is less than 0.3 in the fading channels and in additive white Gaussian channel.The CC algorithm provides a high carrier to interference power ratio (CIR) in the small frequency offset compared with other self cancellation schemes and uses low cost receiver without increase in the system complexity.The drawback of this algorithm is the reduction in bandwidth efficiency, which can be compensated by using larger signal alphabet sizes.Simulation results show good agreement with the numerical results.