The spectrum of direct sequence spread of discovery alters the statistics of a communication system. The result is interference averaging property we assumed when making estimates of system capacity. The intent here is to make the correct mathematical model, or at least to outline the steps of the analysis.
The CDMA quadrature spread is the commercial and reverse channels. As a prelude to the analysis of this system we first consider the BPSK spreading. The extension to the case of QPSK is easy once we have the BPSK results.
Pseudo
Extends random succession in this section we approximate the actual binary PN spreading sequences for an ideal Bernoulli, the succession with the likely outcome. That is Pr [0] = Pr [1] = 1 / 2, with all independent trials. Charting the (0, 1) the succession to a (+1, -1) the succession of discrete modulation (unn), the auto-correlation of the latter is a function that is. The real estate have not - time correlations of the order of 1 / N, where N is the length of the sequence.
Synchronization
The forward CDMA Funnel. QPSK model considered here is similar to CDMA Forward Funnel except that orthogonal channel was neglected. We assume here that the extended sequences are completely correlated among users. There are two consequences of this statement. First, it means that users active in several of the channels of a base station interfering with each other. Second, it means that expectations for the discovery of chip amplitudes depend only forward the user who is directed, and has no contribution from other users.
None of this is true in real CDMA Forward Funnel. First, not only that the extended sequences are set in correlation, they are specifically designed to be above the plane orthogonal 64-chip, which is the plane of an FEC code symbol.
This means that are correlated interference conditions in such a way that when the amplitudes sum to make a soft code symbol. Second, there is a contribution to the amplitude of all the code channels. It is this property that allows us to separate the code channels in the receiver. The effect of channeling angle is to reduce the mutual interference among users. While the cancellation is not perfect in a real system, support, and contributes a little to the capacity front.
