$5.(20$ 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 $++.$

medium. In a real$-$world scenario, synchronization and noise could affect the extraction process.

C: Show that S$3$s CDMA code cannot recover the data of station S$2$ even though S$3$ overhears signals generated in the S$2-$S$4$ communication session $($i$.$e$.,$ S$3$s attempt to use its own Walsh$-$code $++$ on the combined signal will yield a blank at $0$ volt$).$