Figure 1 depicts a simplified scheme for CDMA encoding and decoding. There are seven logical channels,all using DSSS with a spreading code of 7 bits. Assume that all sources are synchronized. If all seven sources transmit a data bit, in the form of a 7-bit sequence, the signals from all sources combine at the receiver so that two positive or two negative values reinforce and a positive and negative value cancel. To decode a given channel, the receiver multiplies the incoming composite signal by the spreading code for that channel, sums the result, and assigns binary 1 for a positive value and binary 0 for a negative value.
1) What are the spreading codes for the seven channels?
2) Determine the receiver output measurement for channel 1 and the bit value assigned.
3) Repeat the previous part for channel 2.