(4) Suppose a synchronous CDMA network has one base station and three mobile users [10] Alice, Bob, and Carol. Below are the chip sequences of the three users Alice: (1,1,1,1) Bob: (1,1,1,1) Carol: (1,1,1,1) (a) Base station has received the bits (1,1,1,3,1,1,3,1). Which mobile user(s) 7' transmitted and what bits they have each transmitted? (d) Another mobile user Ted wants to join the CDMA network. Design a chip sequence 3' for Ted so that transmission of Ted will not interfere with others