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.
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