rriers (CCs), as each one of them is 100 MHz. For this last case, a different set of SS blocks can be configured for each of the 100 MHz CCs, SO the devices accessing the network in this CA mode can consider each of these CCs. SS block composition Now, we will take a deeper look at the SS block structure. As shown in the following figure, the SS block is composed of four consecutive OFDM symbols that span over 20 PRBs. frequency SC number 192-239 DMRS in every fourth subcarrier for PBCH. 56-182 Can be shifted mod 4 between adjacent cells for interference management. ssb-SubcarrierOffset (MIB) symbols OffsetToPointA(SIB 1) SSB slots Point A and subcarrier 0 in the common resource block 0 (CRB 0) grid Half frame (5 ms) slots SSB periodicity = 2 frames (20 ms) (at initial access) Figure 5.6 - A detailed SS block structure 5G Air Interface and Physical Layer Procedures - Part 2 The PSS is transmitted on the central 127 subcarriers of the SS block in the first OFDM symbol. The SSS is transmitted in the same resource elements or subcarriers in the third OFDM symbol. The PBCH uses the entire 20 PRBs of the second and fourth OFDM symbols, as well as four PRBs at each side of the SSS symbol. The devices perform matched filtering to find PSS. PSS and SSS together indicate an Physical Cell ID (PCI): 3 X SSS [range is {0, 1....335}] + PSS [range is {0,1,2}]= 1,008 PCIs [range is {0, 1....1,007}] The SS block has a frequency offset to the Common Resource Block (CRB) grid. The device is informed of the offset or is given the Absolute Radio-Frequency Channel Number (ARFCN). As mentioned before, the SS block is sent periodically, and its default value is 20 milliseconds. It is possible to sweep the SS block with different indexes in different beams. Devices decode the Master Information Block (MIB) in the PBCH. SS block mapping locations Now, we will see the location in time of different SS blocks for the case of frequency bands below GHz. If you recall from the beginning of the section, the SS blocks for below 6 GHz are transmi