4 problems

Global optimality of OFDM over the almost-sure set. Under the same assumptions as the preceding asymptotic and local optimality theorems, OFDM is the global minimizer of the rangin…

Let $N$ be the number of signaling dimensions, let $\mathbf{U}\in\mathbb{U}(N)$ denote the unitary signaling basis, and let $\mathbf{F}_N$ be the normalized $N$-point discrete Four…

Linear-eigenvalue-growth conjecture. There exists an upper bound on the largest eigenvalue of $\mathbf{T}$ that grows linearly with $N$:

Maximum-efficiency conjecture. The maximum efficiency is $d_{\max}=1.4998$, achieved when there are $K=3$ users using $N=2{,}001$ subcarriers.