Ibraheem Shayea

Advanced handover techniques in LTE- Advanced system

There are always increasing demands of high speed data applications in wireless systems with fast and seamless access to voice and multimedia services and QoS guaranteed such as in Fourth Generation (4G) Long Term Evolution (LTE)-Advanced system. Moreover, as mobility speeds support is expected to reach up to 500 km/h, the handover will occur more frequent, thus the system performance in terms of delay and packet loss will be degraded. Hence, efficient radio resource management including handover techniques, load balancing and interference management are essential. In this paper, we present a comprehensive survey on the advanced handover techniques, requirements and features for LTE-Advanced system. Also, advanced handover techniques are highlighted and discussed such as Fractional Soft Handover (FSHO), Semi Soft Handover (SSHO) and multi-carrier handover (MCHO) that incorporate backward compatibility to the existing system. Meanwhile, FSHO technique based on CA with 5CCs are investigated in term of cell throughput and users handover numbers. The result shows that, FSHO with 5 CCs improves LTE-Advanced system in term of cell throughput and numbers of user handover better than Non-CA. Consequently, the existing handover techniques that have been proposed have several advantages, but they are not sufficient to solve hard handover problems. Therefore, a new handover technique is essential required to support fast and seamless handover in LTE-Advanced system. As a result, an advanced handover technique is proposed by combining FSHO, SSHO, and MCHO techniques that can enhance the system performance in term of latency, outage probability and handover reliability especially at cell boundary. Also, the expected output from this hybrid technique can reduce transmission overhead on the network cells by balancing the traffic load in the network cells.

Capacity evaluation of Carrier Aggregation techniques in LTE-Advanced system

In Long Term Evaluation (LTE)-Advanced system, Carrier Aggregation (CA) technique that provide substantial enhancement in data rate transmission for downlink and uplink over wider bandwidth have been proposed. The basic idea of CA technique is to aggregate several smaller contiguous or noncontiguous components, thus concurrent radio resources across multiple carriers are utilized. This paper overview CA technique including data aggregation schemes, bandwidth structure, and CA implementation in LTE-Advanced systems. A simulation model for LTE-Advanced in the downlink has been developed to investigate the impact of CA using up to five Component Carriers (CCs) on the system performance in terms of average throughput and number of active users per cell with respect to non-CA. Simulation show that CA improves the system performance in term of average user throughput within the cell coverage area as CCs increases. Furthermore, CA implementation can enhance the system capacity in term of number of active users in each cell.

Downlink spectral efficiency evaluation with carrier aggregation in LTE-Advanced system employing Adaptive Modulation and Coding schemes

High spectral efficiency is considered as one of the most significant requirements that should be achieved in LTE-Advanced standard in order to fulfil the requirements of IMT-Advanced technology. Carrier Aggregation (CA) and Adaptive Modulation and Coding (AMC) techniques are considered as two potential techniques that can provide high spectral efficiency in wireless communication systems. In this paper, CA technique employing AMC scheme will be implemented to further enhance spectral efficiency performance. Meanwhile, this paper is targeted to simplify a mathematical formulation for calculating spectral efficiency when CA technique is implemented employing AMC scheme. Simulation results show that, the CA technique employing AMC scheme based on the formulated mathematical expression significantly achieve the best possible performance in terms of spectral efficiency in the downlink transmission compared to the performance of Non-CA based on single Component Carrier (CC) employing AMC scheme.

Spectral efficiency of mobile WiMAX networks employing adaptive modulation and coding

Mobile WiMAX technology is based on IEEE 802.16e standard and considered as one of the most prominent solutions capable to provide high speed access in metropolitan areas. Due to limited radio resources, it is necessary to consider radio resource efficiency. This paper investigates the spectral efficiency gain achieved when applying link adaptation techniques on the downlink (DL) of the IEEE 802.16e-based mobile WiMAX networks. The performance evaluation is carried out using a system-level simulation. Evaluation results show that system using adaptive modulation and coding (AMC) significantly outperforms systems using fixed modulation (FM) and adaptive modulation (AM) schemes alone in terms of the spectral efficiency and percentage of successful links.

Handover Performance over a Coordinated Contiguous Carrier Aggregation Deployment Scenario in the LTE-Advanced System

Although various carrier aggregation deployment scenarios (CADSs) have been introduced in the LTE-Advanced system, issues related to insufficient eNB coverage that leads to low throughput and high drop call have yet to be solved. This paper proposes a new deployment scenario called coordinated contiguous-CADS (CC-CADS), which utilizes two-component carriers (CCs) that operate on two frequencies located in a contiguous band. Each CC antenna is directed to a cell boundary of the other CC. The handover performance of users with various mobility speeds under CC-CADS has been investigated and compared with various deployment scenarios proposed by 3GPP. Simulation results show that the received signal reference power (RSRP) enhancement and performed handover, ping-pong, drop call, and outage probabilities reductions in CC-CADS outperformed the 3GPP’s CADSs, thus leading to reduced interruption time, improved spectral efficiency, and seamless handover.

Novel Handover Optimization with a Coordinated Contiguous Carrier Aggregation Deployment Scenario in LTE-Advanced Systems

The carrier aggregation (CA) technique and Handover Parameters Optimization (HPO) function have been introduced in LTE-Advanced systems to enhance system performance in terms of throughput, coverage area, and connection stability and to reduce management complexity. Although LTE-Advanced has benefited from the CA technique, the low spectral efficiency and high ping-pong effect with high outage probabilities in conventional Carrier Aggregation Deployment Scenarios (CADSs) have become major challenges for cell edge User Equipment (UE). Also, the existing HPO algorithms are not optimal for selecting the appropriate handover control parameters (HCPs). This paper proposes two solutions by deploying a Coordinated Contiguous-CADS (CC-CADS) and a Novel Handover Parameters Optimization algorithm that is based on the Weight Performance Function (NHPO-WPF). The CC-CADS uses two contiguous component carriers (CCs) that have two different beam directions. The NHPO-WPF automatically adjusts the HCPs based on the Weight Performance Function (WPF), which is evaluated as a function of the Signal-to-Interference Noise Ratio (SINR), cell load, and UE’s velocity. Simulation results show that the CC-CADS and the NHPO-WPF algorithm provide significant enhancements in system performance over that of conventional CADSs and HPO algorithms from the literature, respectively. The integration of both solutions achieves even better performance than scenarios in which each solution is considered independently.

SINR performance for steerable beamforming techniques in LTE-Advanced system

In 5G wireless communication systems, steerable beamforming techniques will become one of the techniques that will draw high attention in telecommunication industries. The steerable beamforming technique not only provides high throughput, but also increases the capacity of the system. Furthermore, steerable beamforming techniques hold the potential to overcome the interference problem in dense deployment of the serving cell in heterogeneous networks. Since the LTE Advanced system has been proposed by the 3rd Generation Partnership Project (3GPP), which is based on OFDMA, it will eliminate the intra-cell interference. However, the cell edge users suffer from inter-cell interference (ICI) coming from adjacent cells in the same frequency channel. This effects the system performance and degrades the Quality of Service (QoS). In this paper, the main focus is on the performance of the steerable beamforming techniques in terms of signal-to-interference-plus-noise ratio (SINR) result and its based on the user density. At first, this study will discusses brief overview about the beamforming. Then, the detail overview of the techniques is covered.

Adaptive Handover Decision Algorithm Based on Multi-Influence Factors through Carrier Aggregation Implementation in LTE-Advanced System

Although Long Term Evolution Advanced (LTE-Advanced) system has benefited from Carrier Aggregation (CA) technology, the advent of CA technology has increased handover scenario probability through user mobility. That leads to a user’s throughput degradation and its outage probability. Therefore, a handover decision algorithm must be designed properly in order to contribute effectively for reducing this phenomenon. In this paper, Multi-Influence Factors for Adaptive Handover Decision Algorithm (MIF-AHODA) have been proposed through CA implementation in LTE-Advanced system. MIF-AHODA adaptively makes handover decisions based on different decision algorithms, which are selected based on the handover scenario type and resource availability. Simulation results show that MIF-AHODA enhances system performance better than the other considered algorithms from the literature by 8.3 dB, 46%, and 51% as average gains over all the considered algorithms in terms of SINR, cell-edge spectral efficiency, and outage probability reduction, respectively.