$5.(20$ pts$)$ As discussed in class, CDMA is a direct$-$sequencing method that allows simultaneous transmission of data$-$bits by multiple stations. Given a group of N stations $($N $1),$ CDMA maps each station$$s data$-$bit $0/1$ onto a unique sequence of discrete changes in signal$-$levels over multiple time$-$intervals called chips. The signal sequencing is determined by distinct Walsh$-$codes assigned to the N stations in a way to meet orthogonality properties during the signal$-$mixing on physical transmission medium$4.$ Consider two stations S$1$ and S$2$ with Walsh$-$codes $++$ and $++$ respectively$5.$ Suppose another station S$3$ is considered with a CDMA code of $++.$

B: Consider the simultaneous pair$-$wise communication sessions: S$1-$S$3$ and S$2-$S$4,$ where S$1$ sends $110$ and S$2$ sends $011.$ Show how S$3$ extracts its data from the combined signal resulting from the simultaneous transmissions of S$1$ and S$2.$ Note that S$3$ knows the Walsh code of S$1($and vice versa$)$ when the S$1-$S$3$ session is active.