26 4.1.2 Margin Adaptive Approach As mentioned before, MA usually focuses on minimizing the total transmission power while requiring a minimum user data rate . In general terms, MA minimizes the total transmit power while maintaining a minimum quality of service (QoS) for each user. The QoS requirements can be data rate, bit error rate, jitter and delay. In this sub-section, I first define the MA approach using the simple case of a single user. Next, I define the MA approach for the multi-user system described in section 4.1.1. After that, I will survey some algorithms that use this approach. Finally, I will simulate a few MA algorithms in MATLAB and verify the results. To understand MA better, consider the simple case of a single-user system. The OFDMA system has N subcarriers and a total bandwidth of B Hz. The goal of MA is to assign the minimum possible power p n (where n is an integer ranging from 1 to N) to each subcarrier n such that the number of bits transmitted in (1/ T s ) OFDM symbols (OFDM symbol time is
This is the end of the preview. Sign up
access the rest of the document.
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.