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We consider the multi-user discrete bit loading problem in OFDMA systems with objective and constraints in terms of ergodic rates and powers. This differs from most existing techniques, which allocate rate and power according to instantaneous constraints and channel conditions. The maximum weighted ergodic sum-rate optimization problem is non-convex in general, but a dual decomposition results in...
We consider the discrete bit loading problem in OFDM systems with objective and constraints in terms of ergodic rates and powers. This differs from almost all existing techniques, which allocate rates and powers using instantaneous channel gains. The resulting optimization problem is still convex in the single user case, and a dual decomposition is employed along with a tailored approach to the discrete...
We consider active constellation extension to reduce the PAPR in CO-OFDM systems. We find that the nonlinearity threshold is improved by 1.5 dB at a reach of 400 km SSMF fiber.
This paper considers the discrete bit loading problem in OFDMA downlink systems where each user has a minimum-rate constaint. Whereas OFDMA loading problems are generally non-convex and combinatorial, their optimal solutions can be approximated with a dual decomposition. The dual approach in the per-user minimum-rate case has a K-dimensional Lagrange search space for K users, and as a result is a...
This paper proposes a flexible, efficient approach to discrete rate and power allocation for OFDMA systems. We consider the weighted-sum-rate maximization problem, and utilize the Lagrange dual decomposition (as done in some recent works) along with our previous single-user approach to simplify the non-convex, combinatorial optimization problem. The result is an optimal algorithm (up to a very small...
In this paper, we present an active-set approach for peak-to-average power ratio (PAR) reduction via tone reservation in complex-baseband orthogonal frequency division multiplexing (OFDM) systems. In the complex-baseband model, the optimization problem of tone reservation turns out to be a quadratically constrained quadratic program (QCQP), which is computationally prohibitive for a practical implementation...
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