ed individually in a synchronous manner. Transmission of Assignment A-MAP IE, the downlink/uplink HARQ sub-packets, and the corresponding feedbacks are according to predefined timing. The transmission times are defined based on frame index and subframe index. The integer frame index F is between 0 and 3, since there are four radio frames per superframe (as will be described in Chapter 9). In FDD mode, the index of DL or UL subframe ranges from 0 to SF - 1, where SF is the number of subframes per frame, determined based on the radio frame configuration. In TDD mode, the index of DL subframe ranges from 0 to D - 1, where D is the number of DL subframes per frame, and the index of UL subframe is between 0 and U - 1, where U is the number of UL subframes per frame. The value of parameters D and U depend on specific frame configuration [2]. In FDD mode, as shown in Figure 7-9, the DL HARQ sub-packet transmission corresponding to a DL Basic Assignment A-MAP IE in the 1th subframe of the ith DL frame begins in the 1th subframe of the ith DL frame. Note that the DL Assignment A-MAPs point to DL allocations over the same 7.2 Hybrid automatic repeat request functions Frame N Frame N+1 Subframe Assignment Assignment + HARQ Feedback S0SS2S3S4S5S6S UL Burst UL Burst Example FDD UL HARQ Timing Frame N Frame N+1 Subframe Assignment Assignment + HARQ Feedback UL Burst UL Burst Example TDD UL HARQ Timing FIGURE 7-8 An example of FDD and TDD uplink HARQ timing for 5, 10, and 20 MHz channel bandwidths [2] subframe. A HARQ feedback for the DL HARQ sub-packet is transmitted in the nth subframe of the jth UL frame. The subframe indices m, n, and frame index j are determined by using l and i according to the following equation [2]: (7-1) j=(i+[ mod 4 Where [.]and L. denote ceil and floor functions, respectively, and modulo 4 operation is due to the fact that the frame index F ranges between 0 and 3. The parameter Toffset is used to ensure that the HARQ feedback is not generated earlier than the minimum processing time of three subframe