Research And Simulation On Lte-A DL CoMP Joint Transmission

LTE-A standards making and theoretical studies have been gradually completed. While keeping compatibility with LTE, more features are added into LTE-A, such as carrier aggregation. Among those new features, CoMP is proposed and developed as an important approach to enhance the cell-edge user experience.According to the participation of base stations in the cooperating set, CoMP is generally divided into two categories, namely CoMP-JP and CS/CB. While considering whether there are paired users, CoMP can be divided into CoMP-SU-MIMO and CoMP-MU-MIMO. Basically, CoMP is closely related to MIMO. CoMP can be treated as a kind of distributed MIMO transmission.In this paper, implementation of CoMP-JT on GPP platform is mainly studied. Coordinated beamforming matrix selection algorithms based on zero-forcing and minimum mean square error criterion are analyzed. Simulation on SLNR of cell edge users shows that MMSE has better performance than ZF. Meanwhile, MMSE has almost the same complexity with ZF. Therefore MMSE is chosen as the coordinated beamforming algorithm on GPP. When transmission with CoMP and without CoMP both take MMSE beamforming algorithm, transmission with CoMP outperforms traditional base station transmission.Software defined radio on general-purpose processor has advantages of easy to transplant, maintain and upgrade, which makes it receives much attention in recent years. This paper introduces development on GPP platform and describes various optimization methods in the physical layer of LTE-A. The last part of the paper shows the implementation of CoMP-JT. Matrix inversion, matrix multiplication and other operations can be optimized with SIMD, processing time is greatly reduced. After calculation optimization, this CoMP-JT system meets with LTE-A’s time requirement on feedback. Simulation results show that, after coordination, signal reception level of cell edge users has been improved significantly.