OFDMA feedback optimization in 4G-LTE systems

The feedback load is an important parameter with a large impact in Orthogonal Frequency Division Multiple Access (OFDMA) techniques, as a feedback over each one of the subcarriers will induce a non-acceptable signalling load in the system, so that some optimization and feedback reduction strategies are required to meet practical systems demands. The decision over the best strategy for feedback optimization highly depends on the number of available users in the system. We obtain the users' effect on the system through a feedback strategy over a subset of the subcarriers showing the best channel conditions, where a closed form expression of the obtained data rate is formulated to exactly indicate the effect of the number of users, the operating SNR and/or the available number of feedback bits in the system. The performance of the presented scheme is compared to the One-bit feedback strategy in terms of the resultant data rate, where interesting conclusions are obtained.