 on this bit error probability that allows us to avoid computing probability densities for the interference I. This bound uses the step function U-1(x) given by (3B.2) and the inequality for any r = 0. (3B.3) The above inequality is used to obtain an upper bound on the bit error prob- ability [-A+IZ0]=EU_1(-A+I)] < E[er-A+1) e-r-E[e"], (3B.4) where the expectation, E, is taken over all the random variables in the inter- ference term I. When all data bits are equally likely and I has a probability density sym- metric about the origin, another factor of 1/2 can be applied to the final aver- age bit error probability to yield the final Chernoff bound (3B.5) where the expectation, E, is taken over all random variables in the inter- ference term I and r is any positive real number. Commercial Applications Outbound Channel Consider a mobile unit and a base station with an active voice channel. The outbound channel is the TDD burst originating from the base station to the mobile unit. During this outbound burst, the mobile unit is assumed to be synchronized with and receiving a coherent DS/BPSK signal from the base station. Since it uses orthogonal codewords, the mobile unit receives no inter- ference from this base station at the output sample time of its codeword- matched filter. However, this mobile unit will receive interference from other base sta- tion transmissions (see Figure 3.6), which appear at the output sample of the mobile unit's codeword-matched filter. If we consider only one interference base station, interference has the form (3B.6) where Ck is the cross-correlation owing to the k-th codeword used by the interfering base station in its in-phase coordinate and Dj is the cross-cor- relation owing to the j-th codeword used by the same interfering base sta- tion in its quadrature coordinate. Here, we mean the cross-correlation with the codeword of the mobile unit taken at the time corresponding to the time delay difference between the two base stations and the mobile unit. Here, is a fixed arbitrary phase 