LMMSE-IRC). Such receivers explicitly consider the interferer's channel estimates in the process of interference suppression. If precoding is used by the interferer, then the effective channel knowledge is utilized, that is the precoded/effective channel. Such a receiver structure reconstructs the effective channel of the interferer and suppresses the interference. A more powerful receiver category is based on interference cancellation and such receivers are non-linear by nature. Their processing is based on maximum likelihood (ML) principle or iterative/successive cancellation. The ML receivers consist of joint detection of desired and interfering layers and are as such complex, especially if the joint detection operation is applied to a large number of layers. As a consequence, reduced complexity ML (RML) receivers are more implementation friendly and they may make use of sphere decoding, QR-MLD (a combination of ML detection and QR decomposition) or other complexity reduc- tion principles. In terms of knowledge of the interference structure, the RML needs, in addition to the effective channel of the dominant interferer (also needed by the enhanced LMMSE- IRC mentioned above), also information of the modulation used by the interferer. The RML receiver operates on symbol level, that is, decoding of the interferer is not needed. Another class of non-linear receivers is based on successive interference cancellation and since they operate on a modulation symbol basis, this category is abbreviated as SLIC (sym- bol level IC). Successive cancellation receivers are utilizing successive application of linear detection, reconstruction of the interfering signal and cancellation. In terms of interference knowledge, their operation is similar to RML; however, they may be more robust in face of imperfect interference reconstruction. A more advanced and complex version of symbol-based IC is the codeword SIC (CWIC). This receiver structure, in addition to detecting the interfer- ing signal, also decodes it. In other words, th