Selective Interference Alignment for MIMO Cognitive Femtocell Networks

Abstract

This paper presents a novel cross-tier interference management solution for coexisting two-tier networks by exploiting cognition and coordination between tiers via the use of agile radios. The cognitive users sense their environment to determine the receivers they are interfering with, and adapt to it by designing their precoders using interference alignment (IA) in order to avoid causing performance degradation to nearby receivers. The proposed approach judiciously chooses the set of users to be aligned at each receiver as a subset of the crosstier interferers, hence is termed selective IA. The proposed solution includes identification of the subspace in which cross-tier interference signals would be aligned followed by a distributed algorithm to identify the precoders needed at the selected interferers. The intra-tier interference is then dealt with using minimum mean squared error (MMSE) interference suppression. Numerical results demonstrate the effectiveness of selective IA for both uplink and downlink interference management.

Spatial Sensing and Cognitive Radio Communication in the Presence of a <inline-formula> <tex-math notation="TeX">$K$</tex-math></inline-formula>-User Interference Primary Network

“…In these papers, authors present an opportunistic scheme to utilize the unused eigenmodes of the primary channel, and introduce pre-and post-processing schemes. Recently, using the IA techniques in CR networks has been considered [17]- [26]. In [17], authors consider a point-to-point MIMO primary network and propose an iterative algorithm to efficiently design the precoding and decoding matrices for IA in the secondary network.…”

“…Recently in [22], the problem of cooperative spectrum leasing based on a game theoretical approach in an IA network composed of primary and secondary users has been studied. In [23]- [25], authors study the use of IA in underlay CR systems, while the application of IA in CR femtocell networks has been studied in [26].…”

Transmission Cooperative Strategies for MIMO-OFDM Heterogeneous Networks

“…Furthermore, the concept of IA has been jointly used with CR in order to mitigate interference in two-tiered networks [24], [25]. In [24] the authors proposed a novel overlay cognitive interference alignment scheme to increase the spectral efficiency of the two-tiered networks.…”

“…In [24] the authors proposed a novel overlay cognitive interference alignment scheme to increase the spectral efficiency of the two-tiered networks. In [25] a novel cross-tier IA scheme in conjunction with CR to mitigate the interference in heterogeneous networks was derived. In [26] a joint IA and cognitive communication technique in order to mitigate interference of small-cell user terminals (UTs) towards the macro base station was proposed.…”

Opportunistic Sub-channel and Transmit Power Allocation in an OFDMA Based Cognitive Femtocell Network

“…In [11] an efficient frequency assignment scheme has been proposed for femtocells considering the practical issues such as hand off and coverage along with interference. Several other research works have been carried out on various interference management schemes for femtocell networks such as using power control [12,13], spectrum allocation [14], multiple antennas [15][16][17], adaptive resource allocation [18], cognitive radio [19,20] and many others.…”