1. Consider the CDMA cellular technique with 3 stations assigned the following Walsh codes A1-1-11-111-1-11 1-1 1 -1 -1 1 -1 -1 1 -1 -1 B 1 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 C 1 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 Answer the following questions 0-2 a. (2 points) Prove that code for A and code for C are valid Walsh codes. b. (9 points) Consider the above mentioned codes represent 1-bit logic 1 for each station. The following code is received: -20-200-202202 0 0 2 At the receiver, using calculations, show which stations transmitted that resulted in the above mentioned received code word and what logic level is received for each station. Show all steps for full credit c. Consider each station is a voice channel (4 KHz bandwidth), which is sampled using PAM and PCM encoded with 8-bits/sample. i. (2 points) What is the data rate, for each station, before CDMA implementation? ii. (2 points) What is the required channel BW, if baseband transmission is carried out, without further CDMA modulation and wireless transmission? Assume 2-level digital transmission. iii. (5 points) If CDMA technique is now used for the PCM generated data, along with baseband transmission, what is the new data rate of transmission and required bandwidth, but without wireless modulation, for each station?