| IA(Interference Alignment) is a method which can validly enhance the throughput of the wireless communication network, through monitoring the channel coefficients and exploiting them, the pretreatment is done to make the interferences be aligned in the subspaces in the receivers, the left subspaces can be used to receive the desired symbols. In an interference channel with multiuser pairs, each user pair is simultaneously able to send symbols at a rate which is equal to the half of his interference-free channel capacity to his desired receiver.CR(Cognitive Radio) network is composition of two kinds of users which are known as primary users and cognitive users. The primary user is the user whose demand must be satisfied, and the cognitive users can employ their cognitive abilities to communicate without harming the primary users or even helping the primary users to communicate within the spectrum holes, CR has the ability to exploit the scarce spectrum resources expeditiously.In this thesis, we research the classic interference alignment methods and the features of the cognitive network. At the same time we combine the IA method and cognitive network, and we propose a new paradigm called the parallel-separate which is based on the classic K+1 user model, In addition to that, we get the out-bounder of the SISO network’s degree of freedom(DOF) and extend to the MIMO situation. In the MIMO situation(including the SISO situation), the cognitive user can get:(1) half when the DOF of the primary user are less than half;(2) the left DOF when the DOF of the primary use are more than half. But in the paradigm above, the primary get no benefit and instead, they need to participate in the pretreatment. So we also propose the antenna-assist transmission(AAT) paradigm, in AAT, the cognitive user help the primary user to transmit.At last, we point out some further research issues including the situation that MIMO with unequal antenna and the situation that multiple primary user. |
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