Cross-layer optimization for OFDMA system with imperfect CSIT in quasi static channel

摘要

Asymptotic performance analysis of orthogonal frequency division multiple access (OFDMA) is conducted in this work. We take a cross-layer approach and analyze how the system performance scale with some important parameters such as number of user, CSIT quality and order of diversity. It is well studied that system goodput scale with number of user K in the order of O(log logK) due to multiuser diversity (system goodput gain) under perfect CSIT assumption. However, in quasi static fading channels with imperfect CSIT, channel outage happens even if capacity achieving coding is applied at the base station. In this case, cross-layer scheduler can protect the packet by increasing the order of diversity (packet outage diversity). So, there is a trade-off between system goodput gain and packet outage diversity.