Research And Analysis About Impacts Of SIR On Full Duplex System

Full duplex is a new emerging technology in recent years, which can greatlyimprove the utilization rate of spectrum in theory. Since the spectrum resources arelimited today, full duplex draws more and more attention. However, in the actual fullduplex system, self-interference has become one of the most critical fators that limitits performances. So researching on the performacnces of the full duplex systemwith self-interference, and comparing with the conventional half duplex system turnto be a very significant subject.This thesis starts with the simple single-antenna system, and analyses theperformances of the conventional half duplex system, including ergodic capacity,outage probability, outage capacity, bit error rate and throughput. Based on these,this thesis focuses on the performances of the full duplex system, and comparesthem with that of the half duplex system. Two single-antenna full duplex systemsignal models are proposed in the thesis: the signal model considering the channelgain of intereference signals and the signal model regarding interefernce signals asthe white Gaussian noise. The formulas are derived and the results are simulated forthe two signal models respectively. The analytical expression of the signal-to-intereference ratio threshold, when the outage capacity of the full duplex system issuperior to that of the half duplex system, is obtained from the derived fomulas. Theempirical formula of the signal-to-intereference ratio threshold, when the ergodiccapacity of the full duplex system is superior to that of the half duplex system, isalso summarized from the simulated results. Meanwhile, the full duplex system canachieve the same maximum throughput as the half duplex system with a smallerbandwith under a proper signal-to-intereference ratio threshold. Besides, the twosignal models are compared in the thesis, and signal model I is proved to performbetter than signal model II.Secondly, this thesis extends researches from the single-antenna system to themulti-antenna system, and further studies are carried in the conventionalmulti-antenna half duplex system and multi-antenna full duplex system. Similarly,two multi-antenna full duplex signal models are proposed. The formulas are derivedand the results are simulated for the two signal models respectively, and theirperformances are compared with the multi-antenna half duplex system. Theempirical formulas of the signal-to-intereference ratio threshold, when the ergodiccapacity of the full duplex are superior to that of the half duplex system, aresummarized from the simulated results. Besides the thesis compares the multi-antenna full duplex system and the single-antenna full duplex system, and theresults reveal that the multi-antenna system can lower the signal-to-intereferenceratio threshold, and takes more advantages of full duplex technology under the sameconditions. Researching on the multi-antenna full duplex system is supposed to bethe future direction.