Degree of freedom of MIMO ICR under power allocation with optimized interference alignment

The interference channel of multi-antenna source-destination pairs with a multiple-input-multiple-output relay, which is named as MIMO ICR, is the general network structure in the wireless relay networks. This paper investigates degree of freedom (DOF) of K source-destination pairs MIMO ICR under the power allocation with an optimized interference alignment scheme. In the MIMO ICR, each destination aligns the interference of two hops and uses zero-forcing to eliminate the interference, and the power of the relay is an exponential function of the source´s transmitted power P_x with the coefficient α. The properties of capacity of the channel can be described by the sum-rate and scaled by the DOF. It has been proved that, the DOF with optimized IA and the exponential power allocation of the relay is proportional with the number of the source-destination pairs K and the coefficient α. The simulation results show that in the condition P_x >;0 dB, both the increasing of the source transmitted power and the coefficient α make the sum-rate rising. Meanwhile, the value of DOF of MIMO ICR approaches the value of Kα.