ABSTRACT: This paper describes analyzes of the Space Division Multiple Access (SDMA) technique and their hybrids with other Multiple Access Technique (MAT) such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA) for implementation in Global Mobile Satellite Communications (GMSC). In fixed satellite communication systems, as a rule, especially in mobile satellite systems many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users, however, can be solved by using different MAT schemes. Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with a complete charge and to create a different MAT scheme to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.

KEYWORDS: Multiple Input, Multiple Output (MIMO), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Global Mobile Satellite Communications (GMSC), Multiple Access Technique (MAT), Orthogonal Channels of Transmission, Space Division Multiple Access (SDMA), Mobil Eart Station (MES)

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