4. Using OFDM as an access technique

We have presented OFDM as a transmission technique. It is often necessary to transmit several data streams over the same medium. For example, a base station in a cellular network transmits several data streams simultaneously to several terminals. OFDM can be combined with Time Division Multiple Access (TDMA). A time slot structure consisting of several OFDM symbols is defined. A single information stream is transmitted at each time slot (see figure 21 ).

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