ARQ by Subcarrier Assignment for OFDM-Based Systems

We consider two automatic repeat request (ARQ) schemes based on subcarrier assignment in orthogonal frequency-division multiplexing (OFDM)-based systems: single ARQ subcarrier assignment (single ARQ-SA) and multiple ARQ-SA. In single ARQ-SA, data transmitted on a subcarrier in a failed transmission are repeated on a single assigned subcarrier in the ARQ transmission. In multiple ARQ-SA, the data are repeated on multiple assigned subcarriers in the ARQ transmission. At the receiver, maximum ratio combining is performed on subcarriers that carry the same data. Our goal is to optimize certain system utility functions (such as to minimize bit error rates or to maximize sum capacity) through the choice of the subcarrier assignment. We show that a large class of reasonable system utility functions that we wish to maximize are characterized as Schur-concave. For this class of utility functions, we obtain the optimum subcarrier assignment for single ARQ-SA and propose a suboptimum (heuristic) ...

• Type: Journal
• Year: 2008
• Where: TSP
• Authors: Chin Keong Ho, Hongming Yang, Ashish Pandharipande, Jan W. M. Bergmans
• Keywords: Single Arq-sa, Subcarrier, Subcarrier Assignment, TSP 2008