Partial Interference Alignment Schemes for the K-User MIMO Interference Channel

2014 ◽  
Vol 548-549 ◽  
pp. 1368-1376
Author(s):  
Xue Lei Lv ◽  
Guo Mei Zhang ◽  
Guo Bing Li ◽  
Gang Ming Lv ◽  
Chao Zhang
Keyword(s):  
Mimo Systems ◽  
Interference Alignment ◽  
Signal Subspace ◽  
Interference Signal ◽  
Interference Channel ◽  
Precoding Matrix ◽  
Partial Interference ◽  
Chordal Distance ◽  
Simulation Results ◽  
User Interference

Partial interference alignment (PIA) strategies for the K-user interference channel are considered. Two schemes are proposed to align the partial interference for the downlink interference channel in the case ofK>3. In the first scheme, strong interferences are limited as much as possible by aligning the two strongest interferers into a same subspace at the receiver. While the second scheme is to design its precoding matrix (or vector) by selecting the precoder pair which maximizes the chordal distance between designed signal subspace and interference signal subspace in the set of pecoding matrices (or vectors) at each transmitter. Simulation results show that compared with the existing schemes which don’t optimize the precoder, such as Fixed-PIA, the proposed schemes can improve the sum rates significantly by selecting IA forms in multi-input multi-output (MIMO) systems.

scholarly journals Hybrid Precoding Algorithm for Millimeter-Wave Massive MIMO Systems with Subconnection Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xue Zhang ◽  
Feng Zhao
Keyword(s):  
Channel State Information ◽  
Massive Mimo ◽  
Optimization Problem ◽  
Mimo Systems ◽  
High Energy ◽  
Channel State ◽  
State Information ◽  
Hybrid Precoding ◽  
Precoding Matrix ◽  
Simulation Results

In mmWave massive MIMO systems, traditional digital precoding is difficult to be implemented because of the high cost and energy consumption of RF chains. Fortunately, the hybrid precoding which combines digital precoding and analog precoding not only solves this problem successfully, but also improves the performance of the system effectively. However, due to the constant mode constraint introduced by the phase shifter in the analog domain, it is difficult to solve the hybrid precoding directly. There is a solution which divides the total optimization problem into two stages to solve, that is, first fix the digital precoding matrix, solve the analog precoding matrix, and then optimize the digital precoding matrix according to the obtained analog precoding matrix. In this paper, a high energy-efficient hybrid precoding scheme is proposed for the subconnection structure. In the first stage, the optimization problem can be decomposed into a series of subproblems by means of the independent submatrix structure of the analog precoding matrix. When the optimized analog precoding matrix is obtained, the digital precoding matrix can be solved by the minimum mean error (MMSE). Finally, the digital precoding matrix is normalized to satisfy the constraint conditions. The simulation results demonstrate that the performance of the proposed algorithm is close to that of fully digital precoding based on subconnection structure and better than that of the existing algorithms. In addition, this paper presents the simulation analysis of the algorithm performance under imperfect channel state information. Simulation results show that when the estimation accuracy of channel state information is 0.8, the spectral efficiency of the proposed algorithm can already be maintained at a good level.

scholarly journals On the Energy Efficiency of Interference Alignment in the $K$ -User Interference Channel

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 97253-97263 ◽  
Author(s):  
Xiaqing Miao ◽  
Shaoshi Yang ◽  
Changhong Wang ◽  
Shuai Wang ◽  
Lajos Hanzo
Keyword(s):  
Energy Efficiency ◽  
Interference Alignment ◽  
Interference Channel ◽  
User Interference

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.

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