Reducing Symbol Loss Probability in the Downlink of an OFDMA Based Wireless Network

Throughput Improvement through Precoding in OFDMA Systems with Limited Feedback

“…In this paper, we will consider this precoding class and study its ability to improve the overall PRU throughput compared to the conventional scheme in such multicarrier environment with limited channel quality feedback. We show that we can indeed achieve throughput improvement for practical WiMAX and B3G systems using this precoding scheme proposed in [1].…”

“…In this paper, we proposed the use of the precoding scheme, we suggested in [1], to increase the MCS level employed in the PRUs of OFDMA based wireless systems with limited feedback. We derived a formula for the number of original distinct data symbols that should be coded in each PRU as well as the sufficient conditions for our proposed scheme to outperform the conventional scheme.…”

“…In [1], we defined different classes of precoding matrices that satisfy the symmetry property, defined in Section I, and proved that a specific class of precoding matrices A * achieves the lowest symbol error probability among these classes. The matrices of this class must include all the columns of the U ×U identity matrix and the rest of the columns must be linearly independent vectors having no zero entries.…”

“…The allowed constellations are (BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM) corresponding to spectral efficiencies of (1,2,4,6,8), respectively. The value for P th b is set to 10 −3 or 10 −4 for which N u > 501, 1001 TUs respectively.…”

“…The former property is justified by the fact that the stronger the ability of the scheme to reduce the symbol error probability, the lower the number of TUs needed to introduce redundancy and thus the higher the achieved throughput. In [1], we proved that a specific class of symmetric precoding schemes outperforms most other known symmetric precoding classes. In this paper, we will consider this precoding class and study its ability to improve the overall PRU throughput compared to the conventional scheme in such multicarrier environment with limited channel quality feedback.…”