TDMA is optimal for all-unicast DoF region of TIM if and only if topology is chordal bipartite
- Author(s): Yi, X
- Sun, H
- Jafar, SA
- Gesbert, D
- et al.
Published Web Locationhttps://doi.org/10.1109/TIT.2018.2795019
The main result of this paper is that an orthogonal access scheme, such as time division multiple access achieves the all-unicast degrees of freedom (DoF) region of the topological interference management problem if and only if the network topology graph is chordal bipartite, i.e., every cycle that can contain a chord, does contain a chord. The all-unicast DoF region includes the DoF region for any arbitrary choice of a unicast message set, so e.g., the results of Maleki and Jafar on the optimality of orthogonal access for the sum-DoF of one-dimensional convex networks are recovered as a special case. The result is also established for the corresponding topological representation of the index coding problem.