## TDMA in a wireless environment

Just as for FDMA, the wireless environment provides particular challenges to TDMA operation. Again, the 'near-far' effect comes into play, with signals from a distant user taking longer to arrive at the base-station than those from a near user. In order to accommodate these delays, guard-times are required between time slots (cf. frequency guard-bands in FDMA) both to accommodate the variable delay between near and far users, and also to allow for timing errors in the start of a time slot transmission by any individual user. |

The near-far problem also gives rise to the same signal strength fluctuations in the base-station receiver as identified for FDMA, but in this case there is no problem with adjacent channel interference as no user is operating concurrently with another. The receiver, is however, required to react very rapidly to the changing power level from users in different time slots, and power control of each user is commonly applied to alleviate this problem.

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