應用補充下行鏈路於TDD-LTE系統作為緩和2.5 GHz之N-Star與LTE異系統干擾

Abstract

Mobile traffic from 2010 to 2020 is expected to increase by a factor of a thousand. In order to cope with this increasing demand, one solution is to utilize exhaustively all the International Mobile Telecommunications (IMT) spectrum resources defined by International Telecommunication Union (ITU). However, due to the difficulty of controlling coverage areas of N-Star Mobile Satellite Service (MSS), some East Asia countries could not release the spectrum affected by MSS N-Star for Long Term Evolution (LTE) deployment. So far the researchers reuse the MSS spectrum for LTE under the scenarios limited by the indoor environments. Although this method can moderate the interferences from MSS in indoor, it is still ineffective in terms of spectrum efficiency. In this thesis, we proposed a novel method to mitigate the mutual interferences between MSS N-Star’s S-band and LTE’s Band 41 by leveraging the technique of supplementary downlink (SDL). This proposed strategy ensures the coexistence of LTE and MSS and also maintains a satisfactory system performance through the interference management. The principle of this strategy is providing only downlink transmission for the LTE system under the coverage of N-Star MSS. Such band of LTE is utilized as SDL of primary downlink by employing carrier aggregation technique. Because the N-Star MSS can only cause minor interference on the LTE downlink, for both indoor and outdoor usage, the overlapped band can be reused for LTE downlink transmission. By 3D emulation, we simulate the SINR of the TDD-LTE SDL under the co-existence with N-star system. Numerical results reveal that the N-star only induce little degradation on the SINR. That means such method not only enhances the spectrum efficiency and user experience, but also brings lots of economic benefits.