Multidimensional Arrays

Before orthogonal frequency-division multiplexing (OFDM) or single-carrier frequency-division multiple access (SC-FDMA) modulation, the physical channels and signals in LTE must be mapped to different portions of the resource grid. You can represent the resource grid as a multidimensional array, which the toolbox refers to as aresource array. The first dimension of this array represents the subcarrier. The second dimension represents the OFDM or SC-FDMA symbols in the downlink or uplink, respectively. The third dimension represents the antenna ports.

The resource array spans a subframe, equivalent to two slots, in the time domain, except for narrowband internet of things (NB-IoT) uplink transmissions, in which the resource grid spans a slot. Thesubframe resource arrayis a three-dimensional array of size 12N_RB-by-2N_sym-by-P, whereN_RB是啊f resource blocks spanning the available bandwidth,N_sym是啊f OFDM or SC-FDMA symbols per slot, andP是啊f antenna ports. For the single-antenna case, you can use a matrix of size 12N_RB-by-2N_sym. Theslot resource arrayis an array of size 12N_RB-by-N_sym-by-P. Because NB-IoT uplink transmissions use only one antenna port, you can use a matrix of size 12N_RB-by-N_sym. Because a resource block contains 12 subcarriers, the resource array represents a slot for NB-IoT uplink configurations or a subframe for any other configuration and whole bandwidth.

Create Empty Resource Array

Create an empty downlink resource array by using two different methods. You can create valid and equivalent subframe resource arrays by using thelteDLResourceGridfunction or thezerosfunction.

enb = struct('CyclicPrefix','Normal','NDLRB',9,'CellRefP',1);

symbolsPerSlot = 7;

resourceGrid1 = lteDLResourceGrid(enb); resourceGrid2 = zeros(enb.NDLRB*12,symbolsPerSlot*2,enb.CellRefP);

isequal(resourceGrid1,resourceGrid2)

ans =logical1