nimum code rate of 1/3 rate of 1/3 and repetition coding and rate matching (Continued) Table 1 Comparison of the Legacy Mobile WiMAX Features with IEEE 802.16m Continued Legacy Mobile WiMAX based Feature on Release 1.0 IEEE 802.16m Convolutional Codes Tail-Biting Convolutional Codes with minimum Tail-Biting Convolutional Codes with minimum code rate of 1 1/5 code rate of 1/2 DL HARQ Asynchronous Chase Combining Asynchronous Incremental Redundancy (Chase Combining as a special case) UL HARQ Asynchronous Chase Combining Synchronous Incremental Redundancy Downlink Open-loop Space-Time Block Coding, Spatial Multiplexing; Space Frequency Block Coding, Spatial Multiplexing, Non- Single-user MIMO Cyclic Delay Diversity for more than two transmit adaptive precoding for more than two transmit antennas antennas Downlink Closed-loop Sounding-based Transformed codebook-based scheme using sub-band logical Single-user MIMO resource unit, Long-term covariance matrix or codebook based using mini-band logical resource units Sounding-based using sub-band or mini-band logical resource units Uplink Open-loop Not Supported Space-Frequency Block Coding/Spatial Multiplexing, Non- Single-user MIMO adaptive precoding for more than two transmit antennas with distributed logical resource units Uplink Closed-loop Not Supported Codebook-based precoding using sub-band or mini-band Single-user MIMO logical resource units Downlink Multi-user Not Supported Multi-User Zero-Forcing precoding based on transformed codebook or sounding Uplink Multi-User Single-transmit-antenna Collaborative MIMO Collaborative MIMO for up to four transmit antennas (codebook- based or vendor-specific precoding for more than one transmit antenna) Uplink Power Control Basic open-loop power control, Message- Improved open-loop power control (SINR-based) and signaling- based closed-loop power control based closed-loop power control Fractional Frequency Basic Fractional Frequency Reuse Advanced Fractional Frequency Reuse support with up to 4 Reuse frequency partitions (1 re