gle-BS precoding with multi-BS coordination is mainly an interference mitigation and coordination mechanism. These interference mitigation techniques are applicable to downlink MIMO modes 2 and 4 with codebook-based feedback mode with additional inter-BS coordination mechanisms and interference measurement support. The inter-BS coordination mechanisms do not require data forwarding between different base stations. Two types of single-BS precoding techniques with Multi-BS coordination are supported in IEEE 802.16m: (1) PMI coordi- nation, supported by codebook-based feedback; and (2) interference nulling, supported by codebook- based feedback or uplink sounding. Single-BS precoding with multi-BS coordination may be enabled CHAPTER 10 The IEEE 802. 16m Physical Layer (Part II) FIGURE 10-47 Illustration of inter-cell and intra-cell coordinated transmission by the BS for one or several mobile stations when closed-loop MIMO precoding with downlink MIMO modes 2 or 4 are used in the serving and neighboring cells. The inter-cell interference can be mitigated by coordinating the precoders applied in the neigh- boring cells using higher layer signaling and based on feedback from mobile stations to their respective serving base stations. The PMI coordination with codebook-based feedback can be used in the form of PMI recommendation or PMI restriction, depending on the instructions by the BS through the Feedback Polling A-MAP IE. If the Interference Coordination Type parameter is set to 0b00 in the Feedback Polling A-MAP IE, then the MS finds the PMI which demonstrates the strongest interference for the neighboring cell in the frequency resource unit indicated by the Target Resource Unit field signaled in Feedback Polling A-MAP IE; otherwise, the MS finds the PMI which demonstrates the weakest interference for the neighboring cell in the frequency resource unit. Restricting or recom- mending the usage of rank-1 codebook elements as a response to the neighboring cell's request is performed by the BS transmission of BC_SI fiel