Research On The Capacity Problem Of The Interference Channel With Relay Model

Relay technique is one of the key-techniques in the future wireless net-work system. It plays an important role in the aspects of the coverage enhance-ment, the cell-edge spectrum efficiency improvement and the mutual interfer-ence management. When a relay node is introduced into the interference chan-nel model, it forms the interference channel with relay (ICR) model. The ICR model take account of not only the mutual interference problem between mul-tiple transmission pairs and also the affect of the relay technique to the trans-mission in the model. This makes the ICR model a fundamental and important building block for the future wireless network system. And the research on the capacity problem of the ICR model has been one of the new key problems in field of the network information theory research.The thesis researched the capacity problem of the ICR model. It analyzed the problem from two aspects. The first aspect was the types of the ICR model. Three specific types of ICR model were investigated. The second aspect was the detail of the capacity problem. For each of the models mentioned above, the model’s ability of transmission by means of degrees-of-freedom (DOF) and the transmission reliability measured by the diversity gain were studied.For the one-side interference channel with signal cognitive relay model, the achievable DOF and the diversity gain were derived. In the research of the ability of transmission, the transmission scheme for the weak interference condition and the corresponding achievable DOF of the model were studied. In the research of the transmission reliability, in both strong and weak interference regime, the outage probability and the diversity-multiplexing tradeoff (DMT) were studied. And the numerical simulation shown the changes on the DMT with the respect of the channel gain and the implementation of the relay node respectively.A more general case with non-cognitive relay node named the interference channel with non-cognitive relay model was studied, the DOF and the diver-sity gain of this channel model were given, a power allocation algorithm that optimizing the sum-rate was also proposed. In the research of the transmission ability of this channel model, a transmission scheme that was not affected by the interference strength was proposed and the achievable DOF corresponding to this transmission scheme was derived. Moreover, the outage probability and the DMT of this model were studied. The numerical simulation of the DMT shown the relationship between the DMT and the channel gain of the different channels. With the result on the ability of transmission, a sources-and-relay jointly power allocation algorithm for maximizing the sum-rate was proposed. Within the numerical analysis, the proposed optimum power allocation algo-rithm was verified, the effect of the cognitive feature of the relay node to the proposed power allocation algorithm was analyzed and the effects of channel parameters to the power allocation were also investigated.Further generalizing the model, the thesis studied the interference channel with orthogonal relay model. The generalized DOF (GDOF) and the diversity gain were derived and a power allocation algorithm for optimizing the GDOF was proposed. In the research of the transmission ability of this channle model, a transmission scheme and the corresponding achievable GDOF were derived and the results could be applied to a class of models using orthogonal resources. Then the outage probability of this model was researched and the DMT was studied later. The numerical results shown the change of the DMT with the respect of the channel gains and they also indicated that the method that the relay node forwarding the message of the source would affect the DMT as well. The optimization problem of the achievable GDOF was also studied. It was proved that the power allocation factor could be used to maximize the achievable GDOF and the source power allocation algorithm for maximizing the GDOF was proposed. In the numerical analysis, the effects of the channel parameters to the optimum power allocation algorithm were studied. It was later concluded that the power allocation result at source could be used to measure the ability of using transmission power to improve the transmission rates.