Cross-tier interference mitigation for self organized-self optimized femtocells

Abstract

Maximizing frequency reuse is of high interest to multi-tier wireless cellular networks. The coexistence of macrocell and femtocell requires advanced cross-tier interference mitigation to satisfy the spectral efficiency sought for the evolution of cellular networks. In this paper, our proposal combines an opportunistic cancellation of the interference at the base station of the femtocell(HeNB) which mitigates dead zone occurrences at the femtocell premises in closed access regime, and a transmit power limitation on the femtocell mobile user for interference avoidance at the base station of the macro cell. Our proposed com bination profits from the network infrastructure where successive interference cancellation does not apply, and neighbor discovery enabled at the HeNBs. Through simulation results and analysis, our proposal improves the underlay network performance with implementation of a self organized-self optimized network. I1Idex Terms-Macrocell, femtocell, two-tier networks MMSE Cross-tier interference mitigation, power control, SON ' ,

Cross-tier interference management with a distributed antenna system for multi-tier cellular networks

“…Given the distribution of the DAS elements within the macrocell-tier, such cross-tier interference management can be performed in different clusters. This concept generalizes the interference cancellation scheme in [16].…”

“…In [16], the interference cancellation considered information exchange directly between MBS and FBS. Because of the number of femtocells in a macrocell, we consider DAS cooperation as a solution to address the drawbacks such as signal decoding complexity and the traffic constraint on a single MBS.…”

“…As represented in Figure 5, hm1r1 is not required at the RLS input, therefore is not necessary in the following matrix representation of the signals for modeling the interference cancellation process. Such interference cancellation scheme has been proposed in our previous work in [16]. In Figure 5, the signals received by the CPU can be represented as follows: …”

“…We consider MUE1 and MUE2 in Figure 3 for the analysis of the S 0 recovery under the interference of two MUEs. We assume that the estimation process of S 0 can be performed as described in [16] by considering the signal feedback from the feedback system to the FBS that receives the combined signal S 0 h ff +S 1 h m1f +S 2 h m2f . The interference case that must be considered before the recovery of S 0 by the FBS is described as follows: (h m1r2 S 1 + h m2r2 S 2 ) Figure 5 Feedback system with two RAUs.…”

“…Instead of exchanging the related information of the strongly interfering terminal as performed in [14] or resorting to network MIMO as done in [7], our proposed interface directly forwards the MUE transmitted symbols where needed in the femtocell cluster. The traditional MBS-FBS direct connection can be used for interference cancellation [16]; however, as the number of femtocell clusters increases, the macrocell off-loading role of the femtocells [6] is compromised by the induced traffic delay in the backhaul. Furthermore, the signal decoding complexity individually involves each femtocell that requests interference cancellation, in contrast to the schemes in [7,14].…”