Write a program to implement CDMA. Assume that the length of a chip sequence is eight and the number of stations transmitting is four. Your program consists of three sets of processes: four transmitter processes (to, $\mathrm{t} 1$, $\mathrm{t} 2$, and $\mathrm{t} 3$ ), one joiner process, and four receiver processes (ro, $\mathrm{r} 1, \mathrm{r} 2$, and $\mathrm{r} 3$ ). The main program, which also acts as the joiner process first reads four chip sequences (bipolar notation) from the standard input and a sequence of 4 bits (1 bit per transmitter process to be transmitted), and forks off four pairs of transmitter and receiver processes. Each pair of transmitter/receiver processes ( $t 0,0 ; t 1, r 1 ; 12, r 2 ; t 3, r 3$ ) is assigned one chip sequence and each transmitter process is assigned 1 bit (first bit to to, second bit to t1, and so on). Next, each transmitter process computes the signal to be transmitted (a sequence of 8 bits) and sends it to the joiner process. After receiving signals from all four transmitter processes, the joiner process combines the signals and sends the combined signal to the four receiver processes. Each receiver process then computes the bit it has received and prints it to standard output. Use pipes for communication between processes.