Space Division Multiple Access
Space Division Multiple Access
SDMA utilizes the spatial separation of the users in order to optimize the use of the frequency spectrum. A primitive form of SDMA is when the same frequency is reused in different cells in a cellular wireless network. The radiated power of each user is controlled by Space division multiple access. SDMA serves different users by using spot beam antenna. These areas may be served by the same frequency or different frequencies. However for limited co-channel interference it is required that the cells be sufficiently separated. This limits the number of cells a region can be divided into and hence limits the frequency re-use factor. A more advanced approach can further increase the capacity of the network. This technique would enable frequency re-use within the cell. In a practical cellular environment it is improbable to have just one transmitter fall within the receiver beam width. Therefore it becomes imperative to use other multiple access techniques in conjunction with SDMA. When different areas are covered by the antenna beam, frequency can be re-used, in which case TDMA or CDMA is employed, for different frequencies FDMA can be used.
Function of Space Division Multiple Access
» All users can communicate at the same time using the same channel.
» SDMA is completely free from interference.
» A single satellite can communicate with more satellites receivers of the same frequency.
» The directional spot-beam antennas are used and hence the base station in SDMA, can track a moving user.
» Controls the radiated energy for each user in space.