Question

Assume two transmitters with cdma encoding. these transmitters are sending some data over the channel at the same time. according to the spreading sequence for chips and symbols on the channel, answer the questions below:

(the symbols and sequences are left to right)
channel symbols: 0,-2,0,2,0,0,2,2,2,0,2,0,2,-2,0,0

transmitter 1 spreading sequence: 1,1,1,-1,1,-1,-1,-1
transmitter 2 spreading sequence: 1,-1,1,1,1,-1,1,14 -

how many bits are transmitted according to the channel symbols?

Answer 1

According to the CDMA encoding, each transmitter sent 2 bits of information, resulting in a total of 4 bits transmitted over the channel.

Step-by-step explanation:

The question revolves around Code Division Multiple Access (CDMA), a digital data transmission method where multiple transmitters can send information simultaneously over a single communication channel.

In CDMA, each bit of user data is encoded with a unique spreading sequence which allows the separation of multiple signals in the receiver end. To determine the number of bits transmitted, we decode the channel symbols using the respective spreading sequences of the transmitters.

To decode the transmitted data, each channel symbol sequence is to be correlated with the spreading sequence of each transmitter. Considering the spreading sequences provided, a single symbol results from the summation of 8 chips.

As we have 16 channel symbols, and knowing that 8 chips encode 1 bit, we can conclude that for each transmitter, the number of transmitted bits is 16 symbols divided by 8 chips per symbol, which equals to 2 bits per transmitter. Therefore, a total of 4 bits were transmitted (2 bits from each transmitter).