Research On Blind Interference Alignment In The Multi-user Communication Systems

Blind Interference Alignment (referred to as BIA) is an improvement oninterference alignment algorithm based on MIMO technology to suppressinterference. This algorithm can divide channel into the compressed channelinterference subspace and the subspace mixed with the desired signal and theinterference signal, and then eliminate the impact of interference on the desiredsignal. Its effect is very significant, and the application condition is also morerelaxed compared to interference alignment algorithm. But the algorithm cannotagainst the gauss noise and get poor robustness, thus that is not only affected bynoise in the signal transmission, but also leakage for interference and decreasesinterference suppression. While in certain applications, BIA still has the potentialto further improve the user receives the signal and againsts depth of the declineof channel. This paper intends to channel noise impact on BIA algorithms toanalyze for the first, and to study its anti-noise, and then proposes an improvedalgorithm based on BIA to improve the user receives the signal in certain systemand resist depth fading.Firstly, we give quantitative analysis to the alignment block-core of theproposed algorithm for the BIA-affected by channel noise, the result is given bythe loss different parts of the degree of freedom because of noise. Then, for theproblem BIA itself with the nature of the interference blocks and were combinedwith other anti-noise technology-channel coding two theories propose twoimprovement programs, and simulation. With contrasting bit error rate, we wouldgive comparison the advantages and disadvantages of the two programs.Secondly, in the broadcast channel (referred to as BC) with MIMOtechnology, this article intends to establish a kind of BIA improved algorithm,the transmitter is known channel state for several receivers, which will no longereliminate the interference signal in other users, but get out of the interferencesignal as a desired signal, thereby increasing the amount of information of totalreceivers to improve the transmission efficiency. And the receivers with MIMOtechnology allows this algorithm to decrease random errors by noise and brusterrors by deep fading channel. This paper shows the transmitter knows state ofthe channel of one user algorithm and transmitter knows state of the channel oftwo user algorithm. A comparison of bit error rate of these two algorithms andconventional algorithm BIA in MIMO BC, and this simulation comparison of thesimulation results of last chapter. In summary, this paper analyzes the BIA algorithm to noise immunity andgives effective anti-noise program, and it has a more practical application. BIAalgorithm under MIMO BC channel make improvements in the received signal, atthe same time make the algorithm has resistance to noise.