Weaker Link-FWD or Reverse

Question

Do you be familiar with CDMA, which is the weaker Link: FWD or Reverse? Why? Briefly illustrate the reason.

Answer 1

The reverse link is weak in CDMA since of the use of PN Long codes as compared to Walsh codes in the forward link. As, walsh codes are absolutely orthogonal in nature there is less interference in the forward link. PN long codes on the other hand are non-orthogonal in nature. However, we cant use walsh codes for the reverse link as it may seem from the above as the best possible solution. This is because walsh codes are very small in number (64/128/512 max), and hence are not sufficient for identification of large number of users in the reverse link for which the PN long codes are employed.