Research On The Key Technology Concerning The Electromagnetic Feature Of Mutual Interference On Multi-mode Multi-link UE

From the perspective of TD-LTE multi-mode terminal, this paper mainly deals withthe coexistence of Multi-mode Multi-link UE (M~3L-UE) under mutual interference andthe problem of electromagnetics security assessment. We constructed the two settingsseparately with EGSM/DCS1800+TD-LTE and with EGSM+TD-LTE+WiFi in order toresearch on M~3L-UE radio frequency (RF) mutal interference. Then we simulated andevaluated the influence of such interference on bit error rate (BER). We also proposedequivalent interference source method for higher simulation efficiency. The results showa sound coexistence of EGSM+TD-LTE and EGSM+TD-LTE+WiFi models, while thecoexistence between DCS1800and TD-LTE calls for the equivalent isolation over23dBat RF transceiver port.Three solutions are proposed in this document to the problem of M~3L-UEinterference. Among them, the way of no common ground antennas and passive phasereversal method both apply microwave theory. They aim at reducing the electromagneticcoupling between interfering antenna and interfered antenna. On the other hand, theactive signal canellation method applies extra anti-interference path to cancel localinterference. At last we evaluated the feasibility of three solutions from the outcomes,miniaturization, and their technological crafts. Considering the features of M~3L-UEmulti-task, we studied the electromagnetic security problem. SAR（Specific AbsorptionRate）demonstrates the human body absorption nearby and we hence calculated the electromagnetic distribution of M~3L-UE SAR in body. To reduce SAR, we simulated theSAR of bi-antenna and tri-antenna settings and found out a way of changing feed sourcepower distribution and phase distribution to lower SAR.