The performance of heterogeneous networks (Het-Nets) is strongly affected by inter-cell interference. Instead of relying on coordination among base stations, this study presents a new receiver block that identifies the precoders assigned to active users in an adjacent cell. Equipped with this proposed active precoder identification (API), the inter-cell interference at the receiver becomes feasible. The low complexity API is based on the maximum likelihood (ML) criterion and Sherman-Morrison formula. Moreover, by leveraging the fact that the list of active precoders often changes one precoder at a time, an efficient mode-switching API algorithm is proposed for further complexity reduction. Demonstrated by numerical results, the proposed API enables the receiver to achieve error rate performance close to that of the receiver with perfect knowledge of the active precoders used for transmission in the adjacent cell.