Network Coherence Time Matters—Aligned Image Sets and the Degrees of Freedom of Interference Networks With Finite Precision CSIT and Perfect CSIR
| Autor: | Syed A. Jafar, Arash Gholami Davoodi |
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| Rok vydání: | 2018 |
| Předmět: |
Coherence time
Computer science 020206 networking & telecommunications 02 engineering and technology Library and Information Sciences Interference (wave propagation) Topology Computer Science Applications Channel state information 0202 electrical engineering electronic engineering information engineering Random variable Computer Science::Information Theory Information Systems Communication channel Coherence (physics) |
| Zdroj: | IEEE Transactions on Information Theory. 64:7780-7791 |
| ISSN: | 1557-9654 0018-9448 |
| Popis: | This paper obtains the first degrees of freedom (DoFs) bound that is provably sensitive to network coherence time, i.e., coherence time in an interference network, where all channels experience the same coherence patterns. This is accomplished by a novel adaptation of the aligned image sets bound and settles various open problems noted previously by Naderi and Avestimehr and by Gou et al. For example, a necessary and sufficient condition is obtained for the optimality of 1/2 DoF per user in a partially connected interference network, where the channel state information at the receivers (CSIRs) is perfect, the channel state information at the transmitters (CSITs) is instantaneous but limited to finite precision, and the network coherence time is $T_{c}=1$ . The surprising insight that emerges is that even with perfect CSIR and instantaneous finite precision CSIT, the network coherence time matters, i.e., it has a DoF impact. |
| Databáze: | OpenAIRE |
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