Inter-cell Interference Reduction Research Articles

Online Probabilistic Activation Control of Base Stations Utilizing Temporal System Throughput and Activation States of Neighbor Cells for Heterogeneous Networks

In this paper, we propose an online probabilistic activation/deactivation control method for base stations (BSs) in heterogeneous networks based on the temporal system throughput and activation states of neighbor BSs (cells). The conventional method iteratively updates the activation/deactivation states in a probabilistic manner at each BS based on the change in the observed system throughput and activation/deactivation states of that BS between past multiple consecutive discrete times. Since BS activation control increases the system throughput by improving the tradeoff between the reduction in inter-cell interference and the traffic off-loading effect, the activation of a BS whose neighbor BSs are deactivated is likely to result in improved system performance and vice versa. The proposed method newly introduces a metric, which represents the effective ratio of the activated neighbor BSs considering their transmission power and distance to the BS of interest, to the update control of the activation probability. This improves both the convergence rate of the iterative algorithm and throughput performance after convergence. Computer simulation results, in which the mobility of the user terminals is taken into account, show the effectiveness of the proposed method.

Fair Channel Allocation Scheme for Base Station Cooperative Communication in LTE Mobile Network

Unjust provision of channels by base station greatly affects Mobile subscribers. A standard cluster, would be able to serve Many User Equipments (UEs). A typical cluster would contain 3, 7 19, or 21 cells. An issue of ambiguity exist in the demarcation boundary of adjacent cells, thus, radio transmission in a cell from a particular eNode Base Station (eNBs) may leak into neighbouring cells, which causes interferences. Furthermore, the eNBs geographical location is sensitive to obstructions such as towering buildings. The absence of line of sight has a major impact on radio signals, as this would amplify the loss of propagated radio signals, leading to weaken signal strength at the transmitter, that ultimately affecting current the Fixed Channel Allocation (FCA) technique. Despite the effort for fair channel through the current mechanism, users on the edge of the cell experience unfairness. The primary cause for this can be traced to poor received signal power. There are two considered UEs clustered in this simulation scenarios, which is proposed in this paper: (i) random fixed UEs and (ii) 5 step move UEs. A combination of static and dynamic clustering is proposed, thus leading to enhanced channel allocation. From the results, there is a drastic reduction in inter-cell interference, which would increase the performance of the cellular network to become ideal.

Centralized dynamic frequency allocation for cell-edge demand satisfaction in fractional frequency reuse networks

Fractional frequency reuse (FFR) has emerged as a well-suited remedy for inter-cell interference reduction in the next-generation networks by allocating frequency reuse factor (FRF) of unity for the cell-center (CC) and higher FRF for the cell-edge (CE) users. However, this strict FFR comes at a cost of equal partitioning of frequency resources to the CE which most likely has varying demands in current networks. In order to mitigate this, we propose a centralized dynamic resource allocation scheme which allocates demand-dependent resources to CE users. The proposed scheme therefore outperforms the fixed allocation scheme of strict FFR for both CC and CE users. Complexity analysis provides a fair means of analyzing the suitability of proposed algorithm. We have also compared the proposed methodology with a reference dynamic fractional frequency reuse (DFFR) scheme. Results show maximum performance gain of up to 30% for 3 reference cells employing Rayleigh fading—through normalized area spectral efficiency (ASE) analysis for both fixed allocation and DFFR. Spectral efficiency analysis also indicates per-cell performance gain for both CC and CE users. Further, detailed three-dimensional ASE plots give insights into the affects to other cells. Due to dynamic nature of traffic loads, the proposed scheme is a candidate solution for satisfying the demands of individual cells.

Inter-cell Interference Mitigation through Flexible Resource Reuse, LP-OFDM and Coordination techniques for LTE Advanced in Dense Urban Area

<p><em>The inter-cell interference problem is a key issue in LTE Advanced system especially in dense urban environments. This paper present a new inter-cell interference reduction technique for LTE Advanced downlink system in dense urban area based on a new coordination algorithm with the use of linear precoding OFDM, coordination between cells and power management techniques. The objective of our new technique is to improve cell edge and centre capacity in LTE Advanced downlink system. For this purpose, we prove with real time simulations using Matlab that the S.F.R and P.F.R scheme with our algorithm is a good candidate to enhance the average cell capacity and edge user experience, without sacrificing the average cell throughput.</em><br /><strong></strong></p>

Inter-Cell Interference Reduction in Green Cellular Networks using Improved Hand Offs Techniques

Inter-Cell Interference Reduction in Green Cellular Networks using Improved Hand Offs Techniques

Downlink Resource Management Scheme for Next Generation Wireless Networks with Rank Scheduling

Abstract Next generation wireless networks aim to meet the rising demands on cellular networks by supporting higher throughput data applications and efficient usage of the spectrum. In wireless communications, radio spectrum is becoming a limited resource since it is shared by all nodes in the range of its transmitters. Orthogonal frequency division multiple access (OFDMA) technique is the chosen channel accessing in next generation wireless cellular networks for attaining high spectrum efficiency and to reduce frequency-selective fading. Compared to present generation wireless networks, there is a denser cellular deployment in next generation wireless networks. In the multi-cell scenario, Inter Cell Interference (ICI) has become a major issue of concern since it leads to performance degradation. This paper presents a radio resource management (RRM) scheme which includes resource allocation involving ICI reduction, power control based on optimal power allocation solutions which emphasize energy consumption and scheduling which enhances cell edge user's performance in future wireless networks.

A Multi-user Receiver for Inter-Cell Interference Reduction in LTE PUCCH Signaling

In 3rd generation partnership project (3GPP) long term evolution (LTE) systems, when no resources has been assigned in the uplink to a given user equipment (UE), the control information associated with layers 1 and 2 in the protocol stack is conveyed back to the base station through the so-called physical uplink control channel (PUCCH). In PUCCH, the data streams transmitted by multiple UEs are multiplexed in the time-domain and in the frequency-domain with the aid of spreading codes. Although the spreading codes associated with UEs within the same cell can be assumed to be orthogonal, the presence of inter-cell interference (ICI) in multi-cell scenarios severely limits receiver performance. In particular, the Format 1 of PUCCH, which is associated with the transmission of hybrid automatic repeat request acknowledgements (ACK/NACK) and scheduling requests, has a major impact on system performance, since an incorrectly decoded ACK/NACK message may introduce significant delay in data transmission. In this contribution, we propose a new multi-user receiver for ICI reduction in PUCCH LTE that operates both in cooperative and non-cooperative multi-cell architectures. The proposed receiver relies on a constrained tensor modeling of the received signal in PUCCH signaling, and affords an iterative joint channel estimation and symbol detection by simultaneously exploiting the energy of the data symbols and the pilot tones present in PUCCH. The formulation of the proposed algebraic receiver model incorporates symbol-basis hopping and slot-basis hopping signaling schemes, which are interference randomization techniques existing in the 3GPP specifications of LTE system. Computer simulation results show the remarkable performance gains of the proposed receiver compared to the conventional time-frequency decorrelator based receiver.

Self-optimization of LTE networks utilizing Celnet Xplorer

In order to meet demanding performance objectives in Long Term Evolution (LTE) networks, it is mandatory to implement highly efficient, autonomic self-optimization and configuration processes. Self-optimization processes have already been studied in second generation (2G) and third generation (3G) networks, typically with the objective of improving radio coverage and channel capacity. The 3rd Generation Partnership Project (3GPP) standard for LTE self-organization of networks (SON) provides guidelines on self-configuration of physical cell ID and neighbor relation function and self-optimization for mobility robustness, load balancing, and inter-cell interference reduction. While these are very important from an optimization perspective of local phenomenon (i.e., the eNodeB's interaction with its neighbors), it is also essential to architect control algorithms to optimize the network as a whole. In this paper, we propose a Celnet Xplorer-based SON architecture that allows detailed analysis of network performance combined with a SON control engine to optimize the LTE network. The network performance data is obtained in two stages. In the first stage, data is acquired through intelligent non-intrusive monitoring of the standard interfaces of the Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) and Evolved Packet Core (EPC), coupled with reports from a software client running in the eNodeBs. In the second stage, powerful data analysis is performed on this data, which is then utilized as input for the SON engine. Use cases involving tracking area optimization, dynamic bearer profile reconfiguration, and tuning of network-wide coverage and capacity parameters are presented.