A Distributed Interference Alignment Approach Based on Grouping in Heterogeneous Network

Abstract

To effectively mitigate interference and improve the performance, we propose a grouping-based two-stage distributed interference alignment (GTDIA) scheme for a two-layered heterogeneous network (HetNet) in multi-user multiple-input-multiple-output (MIMO) Gaussian downlink transmission scenario. In this paper, we first extend the grouping-based interference alignment (GIA) scheme, which is suitable in single-layer multi-cell scenario to a two-layered HetNet. Then, in order to improve the system performance and reduce the computational complexity, we propose a new interference alignment (IA) scheme (i.e., GTDIA) by grouping pico users (PUEs) to align inter-layer interference (inter-layer IF) and design the receive beamforming matrices of PUEs. Since the macro users (MUEs) are located randomly under the coverage of macro base station, the inter-layer IF is between some pico base stations and MUEs. Specifically, two-stage (i.e., a composite of two cascade matrices) transmit beamforming matrices of base stations are designed to cancel both of the inter-layer and intra-layer interference among MUEs. Furthermore, because of the reciprocity of time-division duplex system, a distributed algorithm is used when designing the second stage transmit beamforming matrices. Analysis and simulation results demonstrate that the proposed scheme outperforms the extended GIA and other conventional IA schemes.

Keywords

• Interference alignment
• grouping
• MIMO
• downlink
• heterogeneous network
• multi-user