switching to the connected mode (RRC Connected), the UE terminal receives the configuration of the CSI-RS. The CSI-RS signal configuration allows the probing of up to 32 antenna ports. Even though the 32 CSI-RS are mobile-specific, multiple terminals can measure the common CSI-RS. An antenna port is a concept of logical antenna perceived by the mobile and corresponds to one or more physical antennas. The NZP-CSI-RS signal is a 31-bit pseudo-random Gold sequence which is transmitted to an antenna port. The CSI-RS is generated by the following formula: is initialized with: is the number of the slot in the frame, 1 is the OFDM symbol position in the slot and n ID is a parameter given by the RRC layer. Like PBCH, c(n) is a Gold sequence constructed with the following two M-sequences: c(n) = (x(n+N)+x(n+N)) mod c(n+31) )=(x,(n+3)+x,(n))mod2 = x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+ x2(n))mod = 2 5G-NR Radio Interface - The Physical Layer The CSI-RS occupies, at most, one single resource element (RE) per slot, per RB, and per antenna port at position (k, 1), except for the antenna port 3000, for which three resource elements can be used. The density of the reference signal can be reduced by only transmitting CSI-RS per RB, every two slots. Thus, the density of the reference signal per antenna port, per RB and on a slot is 0.5, 1 (or 3 for only the first antenna port). In order to measure propagation channels over multiple antenna ports simultaneously, resource elements are reserved for each antenna port, with a limitation to 32 antenna ports per mobile. The antenna ports carrying the CSI-RS signals are numbered from 3000 to 3031. The mobile should be able to separate the CSI-RS specific to each antenna port. Multiplexing order Index number Code Wf Code W [+1 +1] [+1 -1] [+1 +1] [+1 +1] [+1 -1] [+1 +1] [+1 +1] [+1 -1] [+1 -1] [+1 -1] [+1 +1] [+1 +1 +1 +1] [+1 -1] [+1 +1 +1 +1] [+1 +1] [+1 -1 +1 -1] [+1 -1 [+1 -1 +1 -1] [+1 +1] [+1 +1 -1 -1] [+1 -1] [+1 +1 -1 -1] [+1 +1] [+1 -1 -1 +1] [+1 -1] [+1 -1 -1 +1] Table 4.8. CDM mult