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Parameter          Value

            SCS                120 KHz

            No. of Tx antennas   1

            No. of Rx antennas   1
            No. of PRBs        198

            No. of subcarriers   12
            per PRB

            Bandwidth          120
            expansion (2v)

            Number of symbols   1                             (b). High speed train channel model

            Modulation         pi/2-BPSK, QPSK, 16-QAM,       Figure 7 – BLER performance with OTFDM waveform
                               64-QAM, 256-QAM
                                                                     In summary, OTFDM is shown to be an excellent
            Channel model      TDL-D 10nsec, High Speed       candidate  in  meeting  the  Hyper  Latency,  High  Power
                               Train                          Efficiency  and  High  Data rate  requirements  of IMT 2030
                                                              applications.  Further  evaluation  of  this  waveform  will  be
           Table 7 – Simulation parameters                    conducted  with  prototype  systems  operating  in  the  target
                                                              frequency bands of IMT 2030 systems.

                                                                      3.  STRUCTURAL MIMO (S-MIMO)

                                                                 Traditional 5G networks rely on two-dimensional (2D)
                                                              antenna  arrays,  featuring  antenna  elements  distributed  in
                                                              both  azimuth  (horizontal)  and  elevation  (vertical)
                                                              dimensions. These arrays consist of patch antennas or sub-
                                                              arrays, referred to as ports, each providing sectoral coverage
                                                              of 120 degrees in azimuth and approximately 60 degrees in
                                                              elevation. In 5G MIMO deployments, up to 64-antenna ports
                                                              are  utilized.  These  deployments  typically  involve  three
                                                              sectors, each with a 64-port 2D rectangular array operating
                                                              at  a  carrier  frequency  of  around  3.5  GHz  [13]-[16].  To
                                                              achieve a significant increase in network capacity, the base
                                                              station employs precoding or beamforming in the downlink
                                                              (DL),  serving  multiple  users  on  the  same  time-frequency
           (a). TDL-D channel model                           slots.  The  selection  of  users  for  multi-user  MIMO  (MU-
                                                              MIMO)  transmission  is  based  on  spatial  separation  and
                                                              channel state information (CSI) of active users, which can be
                                                              obtained  through  various  methods  such  as  CSI  feedback,
                                                              estimations  on  sounding  reference  signals  (SRS)  in  the
                                                              uplink (UL), and TDD reciprocity calibration.

                                                                 In the DL, the base station pairs users based on DL CSI
                                                              and formulates precoder weights for the paired users, while
                                                              in  the  UL,  channel  estimations  on  the  reference  signals
                                                              associated with the 64-antenna ports are used to combine the
                                                              received data in the uplink equalizer. However, due to the
                                                              limited directivity resulting from the low number of antenna
                                                              elements per port, the signal power received at each port in
                                                              the  uplink  is  low.  This  leads  to  poor  channel  estimation
                                                              quality, particularly for users at cell boundaries (cell-edge
                                                              users)  or  for  SRS  channel  estimation.  Consequently,  DL





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