The future wireless Fifth Generation (5G) communication network required a higher bandwidth in order to achieve greater data rate. It will be largely characterized by small cell deployments, typically in the range of 200 meters of radius/cell, at most. The implementation of small size networks delivers various advantages such as high data rate and low signal delay. However, it also suffers from various issues such as inter-cell, intra-cell, and inter-user interferences. This paper discusses the issues related to interference management for 5G network from the perspective of Heterogeneous Network and Device-to-Device communication, by using enabling techniques, such as Inter-cell Interference Coordination, Coordinated Multipoint, and Coordinated Scheduling. Furthermore, several pertinent issues have been critically reviewed focusing on their methodologies, advantages and limitations along with the future work. Future directions proposed by the 3rd Generation Partnership Project for interference mitigation has also been outlined. This review will act as a guide for the researchers to comprehend various existing and emerging enabling interference mitigation techniques for further exploration and smooth implementation of 5G wireless network.

Interference management issues for the future 5G network: a review

Time-domain enhanced inter-cell interference coordination (eICIC) is an effective technique to reduce the cross-tier inter-cell interference (ICI) in long term evolution (LTE)-based heterogeneous small cell networks (HetSCNs). This paper first clarifies two main communication scenarios in HetSCNs, i.e., macrocells deployed with femtocells (macro-femto) and with picocells (macro-pico). Then, the main challenges in HetSCNs, particularly the severe cross-tier ICI in macro-femto caused by femtocells with closed subscribe group (CSG) access or in macro-pico caused by picocells with range expansion are analyzed. Based on the prominent feature of dominant interference in HetSCNs, the main idea of time-domain interference coordination and two basic schemes in the eICIC standardization, i.e., almost blank subframe (ABS) and orthogonal frequency division multiplexing symbol shift are presented, with a systematic introduction to the interactions of these techniques with other network functions. Then, given macro-femto and macro-pico HetSCNs, an overview is provided on the advanced designs of ABS-based eICIC, including self-optimized designs with regard to key parameters such as ABS muting ratio, and joint optimized designs of ABS-based eICIC and other radio resource management techniques, such as user association and power control. Finally, the open issues and future research directions are discussed.

Time-domain ICIC and optimized designs for 5G and beyond: a survey

To solve interference in a heterogeneous network, LTE-A uses almost blank subframe (ABS) to improve channel quality of picocells at the expense of macrocell’s transmission. Many studies find the ABS ratio based on user number or traffic load. However, the issue of real-time (RT) packet delay is not well studied. We thus develop a delay-aware ABS adjustment (DA3) method to improve performance and lower packet dropping. DA3 estimates cells’ capacity to decide the ratio, and analyzes queue content to alleviate packet discard. Simulation results show that DA3 increases cells’ goodput while reducing RT packet dropping.

Delay-Aware ABS Adjustment to Support QoS for Real-Time Traffic in LTE-A HetNet

With the ever-growing popularity of wireless multimedia services, wireless network base stations are increasingly likely to overload in high population density areas. An economical means exists for operators to establish more picocells in order to reduce the user traffic load on base stations and increase system capacity; however, inter-cell interference is a challenge in such heterogeneous networks. This study proposes a novel scheme that integrates dynamic cell range expansion (CRE) and dynamic almost blank subframe (ABS) schemes based on 3GPP R10 eICIC. The proposed scheme can automatically adjust the CRE bias value according to the cell traffic load, thereby ensuring that users have access to sufficient resources to transmit data when they are offloaded to a smaller cell. Furthermore, the proposed ABS scheme can determine the ABS ratio that yields the highest system capacity. The proposed CRE scheme ensures that offloaded users always have access to sufficient resources. The proposed CRE and ABS scheme can improve network system capacity by more than 13.9% of 3GPP R10 and 11.7% of the competing algorithm.

A dynamic CRE and ABS scheme for enhancing network capacity in LTE-advanced heterogeneous networks

Efficient management of interference and power by jointly configuring ABS and DRX in LTE-A HetNets

In this paper, we present an interference-aware slot allocation technique to improve system performance of the hierarchical picocell/macrocell system, where low-power picocells are underlying a high-power macrocell. Although a hierarchical picocell/macrocell system can improve capacity, it also poses a challenging inter-cell interference (ICI) issue. To control the ICI between pico-cells and macro-cells, one enhanced inter-cell interference coordination (eICIC) technique, called almost blank subframes (ABS), was proposed in the 3rd Generation Partnership Project (3GPP) Long-Term Evolution-Advanced (LTE-A) system. Nevertheless, the current ABS mechanism in 3GPP only defines the fixed ABS ratio, which is not very spectrum efficient and can affect the macrocellular system performance. In this paper, we propose an interference-aware ABS ratio adaptation technique to enhance the total spectrum efficiency of the hierarchical picocell/macrocell system. Compared with the current fixed ABS ratio approach, the proposed method can improve the spectral efficiency of pico-cells and macro-cells by 13% and 7% at the cell edge, respectively.

Time domain coordination for inter-cell interference reduction in LTE hierarchical cellular systems

Edge computing is to deploy micro data centers (MDCs) at the edge nodes of the network to provide services nearby, using the bandwidth of the edge network while reducing network delay. We propose the Greedy-based Resource Orchestration for IoT Edge Computing (GROTEC) mechanism that runs in edge computing environment. The GROTEC mechanism uses a global resource orchestrator to orchestrate the resources of the MDCs with a greedy strategy. The GROTEC mechanism includes a request dispatching algorithm, a request offloading mechanism and a service migration mechanism. The experiment results show that the request offloading mechanism of GROTEC reduces the duration of MDC being overloaded by 97.9%, decreases the network traffic of overloaded MDC by 91.9%, and improves the latency of requests by 12.6%. From the experiment results, the service migration mechanism of GROTEC can ease the load of the cloud data center and improve the latency of requests by 26.8%.

Wen-Pin Lai

Papers

Time domain coordination for inter-cell interference reduction in LTE hierarchical cellular systems

Leveraging Edge Computing Resource Orchestration to Improve QoS for IoT