Iterative interference alignment in macrocell-femtocell networks: A cognitive radio approach

Abstract

The deployment of femtocells in current and future communication systems promises an effective solution for limited indoor coverage problem and a possible gateway for mobile data offloading. In this paper, we cast a cognitive interference align ment approach (IA) suitable for heterogeneous cellular networks with a mixed macrocell and femtocell deployment Specifically, in our approach a restricted waterfflling (RWF) algorithm is used to maximize the downlink data rate, while reserving some eigenmodes for giving the femtocell basestations the opportunity to do their transmissions even at high signal-to-noise power ratio (SNR) for the macrocell basestation. Additionally, both the cross-tier and co-tier interference is to be aligned at each femtocell user's receiver using an Iterative Reweighted Least Squares(IRLS) algorithm. The simulation results show that the proposed IA approach provides an improved sum rate for the femtocell users, compared to the conventional IA techniques, Uke, the leakage minimization approach and the nuclear norm based rank constraint rank minimization approach.

Resource Allocation for Energy Efficiency in 5G Wireless Networks

“…Due to the scarcity of frequency resources and exponential increase of terminal devices in cellular network, the spectrum must be shared between the SBSs and the MBS to serve many users simultaneously [9,46]. As a result, a critical challenge of the alignment intra-and inter-tier interference should be effectively addressed for the successful deployment of HetNets.…”

Interference Mitigation and Sum Rate Optimization for MIMO Downlink Small Cells

“…Such an overlaid cell deployment may lead to co-channel interference [4], [5]. Due to simultaneous transmission of multiple cells, HetNets may suffer from interference caused by the cells in the same tier (co-tier interference) and from the cells in different tiers (cross-tier interference) [6]. Then, the system performance can be significantly degraded if interference is not properly managed.…”

“…It is worth noting that such a system model is similar to that in [1], [6], however, the models in [1], [6] are restricted to one user equipment (UE) per cell. Herein, we consider the scenario that there are multiple UEs per cell and the user scheduling is carried out at the BSs.…”

Iterative reweighted least squares interference alignment approach for multicell MIMO networks

“…Thus, we are aiming to find an efficient approach which converges with large networks with suitable computational complexity [2]. In [4,5], an iterative reweighted least square algorithm for IA (IRLS-IA) have been concatenated with the restricted waterfilling algorithm (RWF) to deal with both the co-tier and cross-tier downlink interference signals originated in macrocell-femtocell heterogeneous systems. In this scenario, we assumed a single cell which includes some macrocell-users and other users that served by femtocell-basestations, where all the interference is inter-user interference (IUI).…”

“…Unlike [4,5], our target is to mitigate inter-cell interference (ICI) between cells in multicell multiuser MIMO downlink and clarify its achievable performance.…”