A WCDMA system with a chip rate of 3.84 Mcps and an information data rate of 9.6 kbps serves two kinds of users: gold users who require a bit-energy-to-interferencespectral-density ratio threshold of...

A WCDMA system with a chip rate of 3.84 Mcps and an information data rate of 9.6 kbps serves two kinds of users: gold users who require a bit-energy-to-interferencespectral-density ratio threshold of 10 dB and silver users who require a bit-energy-tointerference-spectral-density ratio threshold of only 7 dB. a) Consider the uplink situation in a single-cell system and denote by x the number of gold users and by y the number of silver users. Derive the required received power, at the base station, from each terminal as a function of x and y. b) Show that the capacity of this WCDMA system, denoted by η = x + y, is a surface in the (x, y) signal space. Make a plot of this signal space and identify the capacity region for which the signal quality can be maintained for all active users.