The inter-cell interference (ICI) may considerably degrade the system performance of heterogeneous networks (HetNets) and is generally tackled by the transmitters, which often leads to lower spectrum efficiency. To avoid such disadvantage, this work presents a new receiver function that identifies the precoders assigned to active users in interfering cells, and thus enables more effective ICI mitigation. We theoretically derive the design criterion and analyze the performance of the receiver equipped with the proposed active precoder identification (API) scheme. We also propose two low-complexity techniques: the recursive structure based on the Sherman-Morrison formula/matrix determinant lemma, and the mode-switching technique adapting the search space on-the-fly. Numerical simulations demonstrate that such receiver can achieve error rate performance close to a receiver with perfect knowledge of the active precoders. The recursive structure achieves 68% complexity saving, while the mode-switching technique further increases the saving to 83%.
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