The Research Of The GFDM Synchronization Technology

With the complexity of communication environment and the diversification of application requirements,communication technology is being developed to the Fifth Generation(5G)wireless communication.The requirements of the new generation communication networks for the physical layer interface have also changed.At present,OFDM systems are widely adopted in modern mobile communication systems because of its easy implementation and robustness against frequency selective multipath channels.But high out-of-band(OOB)radiation and low band utilization of OFDM make it questionable in applications of the 5G.Recently,a new alternative multicarrier modulation scheme-generalized frequency division multiplexing(GFDM)has been proposed as a candidate for the next generation wireless communication systems.The GFDM has the advantages of low OOB radiation and high spectrum efficiency.However,the analysis of the synchronization errors in this paper shows that synchronization error is an important factor affecting the performance of GFDM system and need reasonable synchronization schemes to remove its effect.Now there are only a few synchronization schemes for GFDM,among which the scheme based on preamble is one of the best performance schemes.However,timing ambiguity caused by a plateau exists in the preamble scheme,which requires additional algorithms to eliminate it.In this paper,two improved scheme are proposed for the problem and simplify the design of the receiver.The simulation results show that the proposed conjugate preamble scheme has better mean square error(MSE)performance than the existing preamble scheme.In addition,the paper also proposes two superimposed synchronization schemes that can meet the requirement of the OOB emission.These method have no plateau,and compared with the existing data-aided schemes,because they don’t transmit data-aided alone,they have higher frequency band utilization.The simulation results show that the schemes can maintain same OOB property with GFDM and can perform well in acquiring timing synchronization and frequency synchronization in Rayleigh multipath channel.