The design of mobile satellite broadcast architectures requires complex tradeoffs involving technical, economical, and regulatory aspects. A satisfactory quality of service in terms of the number of receivers successfully receiving the broadcasted cervices can be ensured using space, terrestrial, and time diversity techniques. The amount of applied diversity affects the system's spectral efficiency and performance. In addition, dedicated satellite and terrestrial networks represent significant investments, and regulatory limitations on terrestrial deployment may further complicate the system design. Herein, we provide insights into the technical aspects of the aforementioned tradeoffs by deriving an efficient method to estimate what system resources in terms of spectrum and delay are required to provide a satisfactory number of end users with mobile broadcast services using space, terrestrial, and time diversity techniques. The presented results are based on statistical models of the mobile satellite channel for which efficient analytical design and error rate estimation methods are derived. To provide a coded space and time diversity, a generalized approach is taken that includes most transmission schemes in use, or considered for use, for mobile satellite broadcast as special cases. As a side result, it is shown that for optimal error rate performance, the provided time diversity should be designed by taking into account channel statistics. An efficient yet simple method of enumerating time-varying Markov chains is also included. The proposed techniques and results are illustrated with numerical examples using temporal Ku-band channel statistics. The examples include a wide range of possible transmission schemes in system configurations with and without space and terrestrial diversity and, thus, demonstrate how different transmission schemes and infrastructure configurations can be compared.