The Feasibility of Interference Alignment for Reverse TDD Systems in MIMO Cellular Networks

Abstract

The feasibility conditions of interference alignment (IA) are analyzed for reverse TDD systems, i.e., one cell operates as downlink (DL) but the other cell operates as uplink (UL). Under general multiple-input and multiple-output (MIMO) antenna configurations, a necessary condition and a sufficient condition for one-shot linear IA are established, i.e., linear IA without symbol or time extension. In several example networks, optimal sum degrees of freedom (DoF) is characterized by the derived necessary condition and sufficient condition. For symmetric DoF within each cell, a sufficient condition is established in a more compact expression, which yields the necessary and sufficient condition for a class of symmetric DoF. An iterative construction of transmit and received beamforming vectors is further proposed, which provides a specific beamforming design satisfying one-shot IA. Simulation results demonstrate that the proposed IA not only achieve lager DoF but also significantly improve the sum rate in the practical signal-to-noise ratio (SNR) regime.

arXiv comment12 pages; 5 figures

References in corpus (7)

• Feasibility Conditions for Interference Alignment
• On the Degrees of Freedom Achievable Through Interference Alignment in a MIMO Interference Channel
• Interference alignment for the MIMO interference channel
• On the Feasibility of Linear Interference Alignment for MIMO Interference Broadcast Channels with Constant Coefficients
• The Feasibility Conditions for Interference Alignment in MIMO Networks
• On the Spatial Degrees of Freedom of Multicell and Multiuser MIMO Channels
• Cellular Interference Alignment