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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Capacity Bounds for the KUser Gaussian Interference Channel
 IEEE transactions on information theory 63 (2017), No.10, pp.64166439 ISSN: 00189448 

 English 
 Journal Article 
 Fraunhofer HHI () 
Abstract
The capacity region of the Kuser Gaussian interference channel (GIC) is a longstanding open problem and even capacity outer bounds are little known in general. A significant progress on degreesoffreedom (DoF) analysis, a firstorder capacity approximation, for the Kuser GIC has provided new important insights into the problem of interest in the high signaltonoise ratio (SNR) limit. However, such capacity approximation has been observed to have some limitations in predicting the capacity at finite SNR. In this paper, we develop a new upperbounding technique that utilizes a new type of genie signal and applies time sharing to genie signals at K receivers. Based on this technique, we derive new upper bounds on the sum capacity of the threeuser GIC with constant, complex channel coefficients and then generalize to the Kuser case to better understand sumrate behavior at finite SNR. We also provide closedform expressions of our upper bounds on the capacity of the Kuser symmetric GIC easily computable for any K. From the perspectives of our results, some sumrate behavior at finite SNR is in line with the insights given by the known DoF results, while some others are not. In particular, the wellknown K/2 DoF achievable for almost all constant real channel coefficients turns out to be not embodied as a substantial performance gain over a certain range of the crosschannel coefficient in the Kuser symmetric real case especially for large K. We further investigate the impact of phase offset between the directchannel coefficient and the crosschannel coefficients on the sumrate upper bound for the threeuser complex GIC. As a consequence, we aim to provide new findings that could not be predicted by the prior works on DoF of GICs.