| In a wireless communication system, the quality of transmission is affectedseriously by signal fading caused by multipath propagation, and the capacity of thesystem is limited greatly. Multi-antenna diversity technology is a kind of methodthat can confront a fading effectively, however, due to the restrictions of volume,power consumption and hardware complexity, mobile terminals of somecommunication system are difficult to configure multiple antennas. In this context,cooperative diversity technology is put forward and receives widespread attentionincreasingly.Cooperative diversity is also called cooperative MIMO in some literature, it isa kind of new way of spatial diversity, which makes the mobile terminal with singleantenna can achieve the result of diversity by sharing each other’s antenna. Due tothe distance between the mobile terminal is usually several times far greater than thewavelength, the correlations between channels are reduced greatly, which canmaximize the channel capacity. However, multi-antenna of mobile terminals is theinevitable trend of development, and there still exists collaboration problem in thewireless network of multiple antenna terminal, cooperative MIMO with multipleantenna terminal can improves the performance of the system further more. In thispaper, surrounding by the multiple antenna terminal cooperative MIMO usingdecoding retransmission way, its collaborative approach, power distribution andcooperation partner selection problem based on the cognitive are studied.First of all, the collaboration partner selection method of multi-antennaterminal cooperative MIMO system is studied. Four classic users grouping methodsare introduced, and their performances are compared. As the performance andfeasibility of the worst link priority algorithm are both better, the specific processesof the worst link priority algorithm are futher analyzed. And on the basis of this, thechannel priority matching algorithm between users based on the worst link priorityalgorithm is studied. Thus, in this paper, the energy gain of the channel preferredmatching algorithm between users in multi-antenna terminal system are analyzed intheory, and the corresponding formulas are deduced. In the last part of the content,the performance of the channel priority matching algorithm between users inmulti-antenna terminal system is simulated, and the simulation results are analyzedconnecting with the theory. The rationality of selecting the user is analyzedcomparatively by random selection algorithm and the performance of this algorithmin a single antenna system is also simulated and analyzed in order to show its changeof properties in the multiple antenna system. In addition, it also involves the change of users in the neighborhood ang threshold of algorithm to study simulation analysisof the algorithm itself performance.Second, the power allocation methods of multi-antenna terminal cooperativeMIMO are studied, several typical power allocation algorithms are proposed, theirprinciples are illustrated, related theoretical formulas are derived, and theperformances of different power allocation algorithm are compared through thesimulation analysis. Then, the basic concept of cooperative diversity, signaltime-division transmission scheme and the way of signal processing of relay nodeare introduced simply, and the system model of cooperative MIMO on the basis ofthe traditional MIMO, a few power allocation methods of provenance node andrelay node are introduced, the expressions of channel capacity of the system aregiven aiming at different methods, and deduced the judgment method of theinterrupt probability of relay and the interrupt of system channel capacitytheoretically. Finally, on the basis of the interrupt probability of system channelcapacity, the performance of the system channel capacity with different powerallocation methods are compared through software simulation, and suitable powerallocation methods under the different conditions are sum up. By the simulationresults, the effect of collaboration is better in in the conditions of small SNR or withthe relay node near the source node. In the collaboration system, the outageprobability of the relay of water anti-injection and the optimal water injectionsystem are lowest; and when signal-to-noise ratio is large or relay is far from thesource node, the collaboration system is inferior to the non-collaboration system, itis appropriate to use traditional MIMO system at this moment.Finally, with the development of wireless communication technology, spectrumresource becomes more and more scarce, cognitive radio (Cognitive Radio, CR)technology has been recognized as the effective solution to increase the resourceutilization problems of networks spectrum. Although collaborative communicationtechnology can improve the antifading ability of the system and cognitive radiotechnology can improve the efficiency of the use of wireless spectrum, these are notenough to solve the two problems existing in the wireless communication which arementioned above. Collaborative communication technology and cognitive radiotechnology have become a research hot topic in recent years. Combining with twokinds of technology will provide a possible solution to improve fading resistance,channel capacity, spectral efficiency of system at the same time. Cognitive networkcooperative diversity technology at coexistence type (underlay) of spectrum sharingmode is researched, and the collaboration strategies of CR system under the peaktransmission power constraints is analyzed on its performance. The existing analysisof cooperative diversity capacity, interrupt probability and bit error rate (BER) aremainly aiming at fixed spectrum allocation. The performance of cognitive radio single node collaboration system is analyzed under the environment of coexistencetype spectrum sharing, and the approximate expressions of interruption probabilityof cognitive system cooperative based on the pattern of decode forward is obtained,the simulation results verify the correctness of theoretical analysis. |
PDF Full Text Request