scholarly journals A Unified Scheme to Achieve the Degrees-of-Freedom Region of the MIMO Interference Channel With Delayed Channel State Information

2016 ◽  
Vol 64 (3) ◽  
pp. 1068-1082 ◽  
Author(s):  
Mohsen Rezaee ◽  
Peter J. Schreier ◽  
Maxime Guillaud ◽  
Bruno Clerckx
Keyword(s):  
Channel State Information ◽  
Degrees Of Freedom ◽  
Interference Channel ◽  
Channel State ◽  
State Information

Degrees of Freedom of 2-Tier Networks Without Channel State Information at the Transmitter

2019 ◽  
Vol 26 (2) ◽  
pp. 382-386
Author(s):  
Maximo Morales-Cespedes ◽  
Luc Vandendorpe ◽  
Ana Garcia Armada
Keyword(s):  
Channel State Information ◽  
Degrees Of Freedom ◽  
Channel State ◽  
State Information

scholarly journals MISO Broadcast Channel under Unequal Link Coherence Times and Channel State Information

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 976
Author(s):  
Mohamed Fadel Shady ◽  
Aria Nosratinia
Keyword(s):  
Channel State Information ◽  
Degrees Of Freedom ◽  
Entropy Inequality ◽  
Block Length ◽  
Broadcast Channel ◽  
Node Mobility ◽  
Channel State ◽  
State Information ◽  
Number Of Factors ◽  
Outer Bounds

The broadcast channel may experience unequal link coherence times due to a number of factors including variation in node mobility or local scattering conditions. This means the block fading model for different links may have nonidentical block length, and the channel state information for the links may also not be identical. The faster the fading and the shorter the fading block length, the more often the link needs to be trained and estimated at the receiver, and the more likely that channel state information (CSI) is stale or unavailable at the transmitter. This paper investigates a MISO broadcast channel where some receivers experience longer coherence intervals and other receivers experience shorter coherence intervals and must estimate their receive-side CSI (CSIR) frequently. We consider a variety of transmit-side CSI (CSIT) conditions for the abovementioned model, including no CSIT, delayed CSIT, or hybrid CSIT. To investigate the degrees of freedom region, we employ interference alignment and beamforming along with a product superposition that allows simultaneous but noncontaminating transmission of pilots and data to different receivers. Outer bounds employ the extremal entropy inequality as well as a bounding of the performance of a discrete, memoryless, multiuser, multilevel broadcast channel. For several cases, inner and outer bounds are established that either partially meet, or the gap diminishes with increasing coherence times.

scholarly journals Secure Retrospective Interference Alignment

Entropy ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. 1092
Author(s):  
Mohamed Seif ◽  
Ravi Tandon ◽  
Ming Li
Keyword(s):  
Degrees Of Freedom ◽  
Interference Alignment ◽  
Square Root ◽  
Interference Channel ◽  
Channel State ◽  
State Information ◽  
Two Phases ◽  
Constrained Models ◽  
User Interference ◽  
Previous Phase

In this paper, the K-user interference channel with secrecy constraints is considered with delayed channel state information at transmitters (CSIT). We propose a novel secure retrospective interference alignment scheme in which the transmitters carefully mix information symbols with artificial noises to ensure confidentiality. Achieving positive secure degrees of freedom (SDoF) is challenging due to the delayed nature of CSIT, and the distributed nature of the transmitters. Our scheme works over two phases: Phase one, in which each transmitter sends information symbols mixed with artificial noises, and repeats such transmission over multiple rounds. In the next phase, each transmitter uses the delayed CSIT of the previous phase and sends a function of the net interference and artificial noises (generated in previous phase), which is simultaneously useful for all receivers. These phases are designed to ensure the decodability of the desired messages while satisfying the secrecy constraints. We present our achievable scheme for three models, namely: (1) K-user interference channel with confidential messages (IC-CM), and we show that 1 2 ( K - 6 ) SDoF is achievable; (2) K-user interference channel with an external eavesdropper (IC-EE); and 3) K-user IC with confidential messages and an external eavesdropper (IC-CM-EE). We show that for the K-user IC-EE, 1 2 ( K - 3 ) SDoF is achievable, and for the K-user IC-CM-EE, 1 2 ( K - 6 ) is achievable. To the best of our knowledge, this is the first result on the K-user interference channel with secrecy constrained models and delayed CSIT that achieves an SDoF which scales with K , square-root of number of users.

Sign in / Sign up

Export Citation Format

Share Document