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24 4.0 RESOURCE ALLOCATION IN OFDMA SYSTEMS Adaptive resource allocation is done in order to optimize the performance of OFDMA systems. High performance can be achieved by assigning the best set of subcarriers for each user for the duration of one or more OFDM symbols. The power and modulation scheme for each subcarrier can also be modified to further optimize performance. After a few symbols have been transmitted, the transmitter will have to estimate the Channel State Information (CSI) again in order to figure the best way to allocate resources in the future. Thus all adaptive resource allocation algorithms depend upon recalculating the CSI periodically. Recent resource allocation algorithms also take the precision of the available CSI into account. There are two key approaches to adaptive resource allocation in OFDMA systems: system- centric and application-centric. System-centric approaches tend to optimize system metrics, such as data rate and transmission power. On the other hand, application-centric approaches try to
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This note was uploaded on 09/27/2009 for the course ECE 399 taught by Professor Prof during the Spring '09 term at University of Texas at Austin.

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