I saw the definition of half duplex in wiki,and it said
half-duplex (HDX) system provides communication in both directions, but only one direction at a time (not simultaneously). Typically, once a party begins receiving a signal, it must wait for the transmitter to stop transmitting, before replying.
However,i saw a paper: http://jultika.oulu.fi/files/nbnfi-fe2019040110636.pdf ,its system model is a transmitter transmit the $x_1$ and $x_2$ information to the user1(U1),then U1 transmit $x_2$ to the user2(U2),and it said this is half-duplex.
So in fact,the definition of half duplex is that device can transmit and receive,but no need to transmit and receive at the same time?
I mean,$A$ give $x$ to $B$,then $B$ give $x$ to $C$,this is also called half-duplex?I thought this is called simplex duplex before,because i thought the half-duplex is $A$ give $x$ to $B$,then $B$ give $x$ back to $A$.
So i want to ask that $A$ give $x$ to $B$,then $B$ give $x$ to $C$,this is also half-duplex?