Efficient Load Balancing Algorithm in Long Term Evolution (LTE) Heterogeneous Network Based on Dynamic Cell Range Expansion Bias

The traditional scheme for load balancing in a homogeneous Long Term Evolution (LTE) Network where User Equipment (UEs) associate to a node with the strongest received signal strength is not practical for LTE Heterogeneous Network (LTE HetNet) due to power disparity between the nodes. Therefore, dynamic Cell Range Expansion (CRE) based load-balancing schemes were employed by several scholars to address the challenges in the LTE HetNet. However, the fairness index in achieving the desired average user throughput and UE offloading effect is relatively low. In this work, an efficient load-balancing algorithm for LTE HetNet based on dynamic Cell Range Expansion (CRE) was developed to improve the fairness of the network for the desired throughput and UE offloading effect. The simulation results achieve a throughput gain improvement of up to 11%, while the fairness index improves by 6% compared to the existing algorithm. Further, the UEs offloading effect shows a significant improvement of 3% relative to the existing algorithm. Keywords: Fairness Index; Cell Range Expansion; Load Balancing; LTE Heterogeneous Network; Throughput

Personal Picocell Scheme Using Adaptive Control CRE in Heterogeneous Mobile Networks

Heterogeneous networks (HetNets), which are combined with a macrocell and picocell in the same coverage, are expected to further increase the system capacity in fifth-generation mobile systems and beyond. In HetNets, the cell range expansion (CRE) technique plays an important role and can allow more user equipment (UE) to access the picocell, i.e., virtually expand the picocell coverage. However, conventional CRE techniques that provide a fixed cell selection offset (CSO) for all UE may worsen user throughput if UE is forced to connect to the picocell because the received signal-to-interference plus noise ratio of the UE becomes lower. Therefore, we propose a personal picocell scheme using an adaptive control CRE technique to improve user throughput in which different CSOs are assigned to UE to form each optimal picocell for each UE. In this paper, we first describe the aspects and algorithm of the proposed scheme. Then, we show the user throughput for adaptive control CRE in comparison with conventional CRE by using system-level computer simulations for the two types of HetNets, i.e., single-band and multi-band HetNets. In the simulations, we first clarify the optimal parameters of the adaptive control CRE. We then show the average and 5-percentile user throughput of the optimized adaptive control CRE in comparison with that of conventional CRE. From these results, we confirmed that the personal picocell scheme using the adaptive control CRE can improve the 5-percentile user throughput while maintaining the average user throughput compared with that of conventional CRE.

Joint optimization on resource allocation with coordinated scheduling-based transmission for interference handling in Femtocell networks

Background: The most challenging problem in femtocell networks is alleviating the Inter-Cell Interference (ICI) between the macro and femtocells while broadcasting the video streams in the Heterogeneous Networks (HetNets). It degrades the spectral efficacy and throughput significantly. To alleviate this problem, a Joint dynamic Layer, Channel and Power assignment with Further enhanced ICI Coordination (JLCP-FeICIC) method was recommended to assign the resources within every User Equipments (UEs) and enhance the throughput in a two-tier HetNets. Nonetheless, it schedules only the Cell Range Expansion (CRE) UEs of femtocells while the center UEs are not assigned and so the fairness of Resource Block (RB) allocation is reduced. Objective: Therefore in this study, JLCP-FeICIC is further enhanced with the Coordinated Multipoint Transmission (CMT) method (JLCP-FeICIC-CMT) for maximizing the efficiency of the HetNetcenter UEs. Methods: In this method, RBs are assigned by a primary scheduler. Also, the UE is detected in every eNodeBs (eNBs) according to the determination of the interference from the adjacent cells. Then, the Modulation and Coding Scheme (MCS) level is selected in all eNBs for UEs with and without the support of CMT according to the interference-free RB allocation. So, a higher level of spectral efficiency is achieved for corresponding RBs. Findings: Finally, the experimental results exhibit the JLCP-FeICIC-CMT achieves an increased efficacy than the JLCP-FeICIC.The efficiency is analyzed based on the average of Peak Singal-to-Noise Ratio (PSNR) per Femtocell UE (FUE), utility, monetary cost, and Playback Interruption Rate (PIR). Keywords: Femtocell network; HetNet; JLCPFeICIC; coordinated multipoint transmission; modulation and coding scheme