This paper is concerned with evaluating, the performance of a direct sequence spread-spectrum with two types of diversity copmbining techniques, namely, Selection diversity (SDC) and maximal ratio combining (MRC), in a land mobile satellite transmission system, using 16-ary Quadrature Amplitude modulation (16mYQAM). It is assumed that the channel consists of a Nakagami shadowed line-of-sight signal plus Rayleigh distributed multipath signals, as well as additive white Gaussian noise. Fading and shadowing cause both envelope and phase variations of the received signal. The paper derives upper bounds of the probability of error due to both of these variations, and closed form expressions are found for L branch diversity using both MRC and SDC in a realistic (practical) operating environments with independent but not identically distributed diversity paths. Assuming a Gaussian approximation for the interference, numerical results are obtained for both spread spectrum and spread spectrum with diversity eception in land mobile satellite communication systems with 16arYQAM for light and average shadowing and fading