E 802.1 link-level and system-level performance In the downlink, and concerning the InH and UMi test cases, the sub-band CRU subchannelization scheme was utilized, whereas in the UMa and RMa scenarios, mini-band CRU subchannelization was utilized since the latter subchannelization scheme provides more frequency diversity gain compared to the former in higher mobility. Furthermore, in InH and UMi cases, the 6-bit transformed codebook- based MU-MIMO scheme with a configuration was used, i.e., adaptive switching among rank-1, rank-2, rank-3, and rank-4 transmission, while in the UMa and RMa scenarios, MU-MIMO with long- term beamforming was utilized using a 4 2 antenna configuration, i.e., adaptive switching among rank-1, rank-2, rank-3, and rank-4 transmission. The MMSE receiver was employed in the MS for both channel estimation and data detection. The chase combining HARQ with maximum re-transmission delay of four frames and up to four re-transmissions was used in the simulations. The signaling error for the Assignment A-MAP and HARQ Feedback A-MAP were explicitly modeled in the simulations. The sounding estimation error has also been modeled for the midamble sequence. The dynamic overhead due to the Assignment A-MAP and HARQ Feedback A-MAP were modeled and the static overhead corresponding to non-user specific A-MAP, downlink synchronization channels, and superframe headers were taken into consideration in the simulations. In the uplink, and with reference to the InH and UMi test cases, sub-band CRU subchannelization, as well as the 3-bit codebook-based MU-MIMO scheme with adaptive switching between single-user, and collaborative spatial multiplexing based on a 2 X 4 antenna configuration were used, whereas in UMa and RMa scenarios, mini-band CRU subchannelization in conjunction with MU-MIMO scheme with long-term beamforming and adaptive switching between single-user and collaborative spatial multiplexing with a 2 4 antenna configuration was utilized. The MMSE receiver was employed in the BS for both channel esti