The effect of time and frequency offsets in the uplink of an asynchronous multi-user system for wireless communications deploying discrete multi-tone modulation and demodulation is studied through analysis. We give analytical expressions for the multiple access interference generated in such a scenario, we study its statistics, and we emphasize its dependency on the tone assignment algorithm used to multiplex the users. Based on our analysis, we also show that an effective way of counteracting these impairments is to insert time and frequency guard intervals, so that a proper trade off with spectral efficiency can be met to optimize system performance.
On the Effect of Time and Frequency Offsets in the Up-link of an Asynchronous Multi-user DMT OFDMA System
LAURENTI, NICOLA;PUPOLIN, SILVANO
2000
Abstract
The effect of time and frequency offsets in the uplink of an asynchronous multi-user system for wireless communications deploying discrete multi-tone modulation and demodulation is studied through analysis. We give analytical expressions for the multiple access interference generated in such a scenario, we study its statistics, and we emphasize its dependency on the tone assignment algorithm used to multiplex the users. Based on our analysis, we also show that an effective way of counteracting these impairments is to insert time and frequency guard intervals, so that a proper trade off with spectral efficiency can be met to optimize system performance.
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