ation. The mobile station is required to support both base and transformation modes, and it may optionally support a differential mode. The transformation and differential feedback modes are applied to the base codebook or to a subset of the base codebook. CHAPTER 10 The IEEE 802. 16m Physical Layer (Part II) Table 10-26 Downlink MIMO Parameters Type of Information Description of the Parameter Value Broadcast Number of transmit antennas at the BS which is 2,4,8 indicated in S-SFH SP3 IE Open-loop MIMO region, which is used to indicate the Refer to AAI_SCD location of the open-loop MIMO region and the message number of MIMO streams (1 or 2). This parameter is sent via an AAI_SCD MAC management message. Rank-1 base codebook subset indication bitmap for 8 bits if Nt = 2 interference mitigation with PMI coordination. 16 bits if Nt = 4,8 Rank-1 codebook element restriction or recommendation information (This parameter is enabled by Codebook_Mode or Codebook_Coordination parameters). Unicast MIMO encoder format which is indicated in DL basic assignment A-MAP IE, DL sub-band assignment Vertical encoding A-MAP IE, or DL persistent A-MAP IE. Horizontal encoding Number of MIMO streams in transmission which is 1 to 8 indicated in DL basic assignment A-MAP IE, DL sub-band assignment A-MAP IE, or DL persistent A-MAP IE. Index of allocated pilot stream which is indicated if 1 to 4 MIMO encoder format is horizontal encoding. This parameter is signaled in DL basic assignment A-MAP IE, DL sub-band assignment A-MAP IE, or DL persistent A-MAP IE. MIMO feedback mode in order to decide the feedback See Table 10-25 content and the related MS measurements and reporting process. This parameter is indicated in feedback allocation A-MAP IE, or feedback polling A-MAP IE. Maximum number of spatial streams depending on the Ns < min(Nt,Nr) MIMO mode and the minimum number of transmit and receive antennas depending on MIMO feedback mode (this parameter is signaled through the feedback allocation A-MAP IE, or feedback polling A-MAP IE. Codebook