Handover Requests Research Articles

Hidden Markov models for predicting cell-level mobile networks performance degradation

The ubiquitous deployment of Fourth-generation (4G) and Fifth-generation (5G) networks, while expanding user connectivity over a larger geographic area, presents significant challenges for mobile network management. The surge in connected devices increase cell congestion, while user mobility, fading, and interference further deteriorate channel quality. The combined effect of these factors contribute to a gradual degradation in cell and network performance, straining the capabilities of Mobile Network Operators (MNOs) to maintain optimal service quality. The degradation progresses through distinct stages, and ultimately leading to cell outages. Existing cell degradation detection methods, such as key performance indicators (KPIs) monitoring and drive tests, rely on indicators such as signal strength (like reference signal received power (RSRP)), network measurements (like traffic volume and handover requests), and user complaints. However, these methods may not provide real-time insights, leading to delays in identifying and addressing performance issues. This paper proposes a Hidden Markov Model (HMM) approach for proactive cell degradation prediction using real-time time-series KPIs data collected from a telecom operator’s network management system. The NetMax system, a network management system specifically designed for ZTE networks, was used for KPIs data collection. RSRP, 3GPP-recommended signal strength metrics for degradation measure, defines hidden states, while traffic volume and handover requests represent the observable states. The HMM achieves an average prediction accuracy of 93.12%, F1 score of 91.81%, and precision of 92.82% with 23 observation lengths, demonstrating the models’s effectiveness in predicting mobile network’s cell degradation severity.

Evaluation of the QoS policy model of an ordinary 5G smart city cluster with predominant URLLC and eMBB traffic

A typical element of the smart city’s information and communication space is a 5G cluster, which is focused on serving both new and handover requests because it is an open system. In an ordinary 5G smart city cluster, Ultra-Reliable Low-Latency Communications (URLLC) and enhanced Mobile BroadBand (eMBB) traffic types prevail. The formation of an effective QoS policy for such an object (taking into account the potentially active slicing technology) is an urgent problem. As a baseline, this research considers a Quality of Service (QoS) policy with constraints for context-defined URLLC and eMBB classes of incoming requests. Evaluating the QoS policy instance defined within the framework of the basic concept requires the formalization of both a complete qualitative metric and a computationally efficient mathematical apparatus for its calculation. The article presents accurate and approximate methods of calculating such quality parameters as the probability of loss of typed requests and the utilization ratio of the communication resource, which depend on the implementation of the estimated QoS policy. At the same time, the original parametric space includes both fixed characteristics (amount of available communication resources, load according to request classes) and controlled characteristics due to the specifics of the implementation of the basic QoS concept. The paper empirically proves the adequacy of the presented mathematical apparatus for evaluating the QoS policy defined within the scope of the research. Also, in the proposed qualitative metric, a comparison of the author’s concept with a parametrically close analogue (the well-known QoS policy scheme, which takes into account the phenomenon of reservation of communication resources), determined taking into account the reservation of communication resources, was made. The results of the comparison testify in favour of the superiority of the author’s approach in the proposed metrics.

Machine Learning-Based Solutions for Handover Decisions in Non-Terrestrial Networks

The non-terrestrial network (NTN) is a network that uses radio frequency (RF) resources mounted on satellites and includes satellite-based communications networks, high altitude platform systems (HAPS), and air-to-ground networks. The fifth generation (5G) and NTN may be crucial in utilizing communication infrastructure to provide 5G services in the future, anytime and anywhere. Based on the outcome of the Rel-16 study, the 3rd generation partnership project (3GPP) decided to start a work item on an NTN in 5G new radio (NR) Rel-17, and the focus of the study was on mobility management procedures, due to the movements of NTN platforms; especially, low earth orbit (LEO) satellites. Handover enhancements were discussed to tackle the frequent handover due to the fast satellite movement. Therefore, the major problem of handover in LEO satellite systems was the signaling storm created by handing over all user equipment (UE) in a cell to a new cell because when the UE crosses the boundary between the neighboring cell of a satellite, an intra-satellite or cell handover occurs; thus, all users in a cell are expected to experience a change of cell due to handover every few seconds. In addition, UE location is not easy to define due to moving cell/beam situations. In this study, we propose machine learning-based solutions for handover decisions in non-terrestrial networks for cell handovers or intra-satellite handovers to reduce signaling storms during handovers where the handover requests will be executed by clustered users. First, the dataset was generated by the simulator that simulates communication between users and satellites. Second, we preprocessed the data, and also used the feature creation technique to create the distance feature using the Haversine formula, and then applied clustering and classification algorithms. The experimental results show that the distance between a user and its cell center is an important parameter for handover decisions in NTN, and the random forest outperforms all models with a higher accuracy of 99% along with a better F1-score of 0.9961.

Authentication and Key Agreement Algorithm for Handover of Next-Generation High-Speed Railway

In order to solve the problems that the handover key in the handover authentication protocol of 5 G-R wireless communication system under the next-generation high-speed railway does not have forward security and authentication efficiency is low, a novel 5 G-R handover authentication and key agreement algorithm is proposed. First, the authentication information is used to replace the identity information in the handover request message, which overcomes the shortcomings of the clear text transmission of the identity information. Second, a handover key update strategy based on lattice theory is designed. The dynamic update and forward and backward security of the handover key are realized by using the feature function and the auxiliary module function on the lattice. Third, the message authentication code is added to realize mutual authentication between communication parties, which can effectively prevent replay, the man in the middle, and other malicious attacks. Finally, the strand space formalization method is used for security verification. The results show that the proposed method not only has higher security and efficiency than other comparison methods but also can meet the high-security requirements of the next-generation 5 G-R handover authentication.

Beyond 5G: Reducing the handover rate for high mobility communications

The fifth-generation (5G) and beyond cellular networks are expected to support a huge number of mobile devices, roaming seamlessly across very small cells. Consequently, the handover rate for these extremely dense networks is expected to be very high. To reduce the burden caused by rapid handover requests, and to support a massive number of highly mobile devices in 5G and beyond networks, this study suggests using proximity-based clusters as nomadic cells integrated with Aerial Access Networks (AANs). These nomadic cells are formed by two-levels hierarchical partitioning of the mobile devices into proximity-based clusters. Previous distributed mobility management schemes are not sufficiently efficient to support the handover rate expected for 5G and beyond networks. Due to their high computational complexity, previous group-based methods are not applicable for real-time services. In contrast to these schemes, the proposed scheme is scalable with the number of devices. Moreover, the creation of a mobility group raises practical as well as security and privacy issues that were overlooked by previous schemes. These issues are addressed in this study.

EMMM: Energy-efficient mobility management model for context-aware transactions over mobile communication

The rapid advancements in wireless technology and enhanced computing power of handheld devices, enable the users to perform transactions anywhere, anytime during roaming. Carrying out ongoing transactions during roaming is a crucial field for research in the field of mobile communication. In order to ensure a high quality of service (QoS), an energy-efficient handover process is essential for accomplishing the ongoing transaction. The performance of mobile communication is mainly deteriorated by the roaming and low battery power requirement of mobile host. Due to limited channel availability, most of the handover requests are failed. Energy-efficient enhanced mobility management queuing model is proposed by combining two existing schemes GE/GE/C/N/FCFS and scheme GE/GE/C/N/PR to strengthen the performance. In this research, EMMM scales down the dropping rate of handover transaction request (HTR) and new transaction request (NTR).The proposed model has achieved the enhancement of channel utilization along with the reduction in handover failure and low drop and blocking rate of HTR and NTR, respectively.

Mobility Management in Small Cell Cluster of Cellular Network

The installation of small cells in a 5G network extends the maximum coverage and provides high availability. However, this approach increases the handover overhead in the Core Network (CN) due to frequent handoffs. The variation of user density and movement inside a region of small cells also increases the handover overhead in CN. However, the present 5G system cannot reduce the handover overhead in CN under such circumstances because it relies on a traditionally rigid and complex hierarchical sequence for a handover procedure. Recently, Not Only Stack (NO Stack) architecture has been introduced for Radio Access Network (RAN) to reduce the signaling during handover. This paper proposes a system based on NO Stack architecture and solves the aforementioned problem by adding a dedicated local mobility controller to the edge cloud for each cluster. The dedicated cluster controller manages the user mobility locally inside a cluster and also maintains the forwarding data of a mobile user locally. To reduce the latency for X2-based handover requests, an edge cloud infrastructure has been also developed to provide high-computing for dedicated controllers at the edge of a cellular network. The proposed system is also compared with the traditional 3GPP architecture and other works in the context of overhead and delay caused by X2-based handover requests during user mobility. Simulated results show that the inclusion of a dedicated local controller for small clusters together with the implementation of NO Stack framework reduces the significant amount of overhead of X2-based handover requests at CN.

Handoff Control in Satellite Communication Applying Multi Billboard Manager Method

LEO satellites play an important role in global communication system. LEO satellites have some advantages over GEO and MEO satellites, in respect of power requirement, end-to-end delay & more efficient frequency spectrum. But the main problem of LEO satellite, is that they have large relative speed than the speed of mobile nodes (MN) and earth, so that the handover occurrence is more. As a result, the call blocking probability (Pb) and force call termination probability (Pf) is higher. To overcome this problem, Billboard manager based handover (BMBHO) was introduced to reduce the scanning time significantly and also to reduce the Pf. But the main problem of single billboard manager (BM) is that, since all handover requests have to be processed from a single point. In this paper, we have proposed the concept of multi-billboard manager based handover (MBMHO) method to resolve this problem. Thus, handover request will be served more efficiently so that both Pb and Pf are minimized than the BMBHO method.

Priority Management of the Handoff Requests in Mobile Cellular Networks

Due to the motion of mobile station with respect to the base station, the handover is required frequently in the communication process. In this paper, assuming that the user location and speed can be determined, we propose a suitable scheme for managing a queuing of handover requestes in wireless cellular network. The principle of the proposed method is the use of a separate queue for each transceiver in the cell (3TRX per cell) instead of using a single one and we consider that handover request to cell is queued with dynamic priority discipline; highest priority (head of the queue), least priority (joins the end of the queue). Fixed channel allocation is considered and call blocking probability (CBP), handover failure probability (HFP) are obtained as a results. In order to choose the best model which reduces significantly the handover failure probability, a comparison between the proposed model and the classical one is considered. Simulation results highlight that the newly proposed architecture can guarantee superior performance with respect to its competitor.

Performance Evaluation of Vertical Hard Handovers in Cellular Mobile Systems

With the rapid increase of new and diverse cellular mobile services, the overlapping of cells has become typical in the majority of the coverage area of the network. Vertical handovers occur between two layers of cells when a user is switched from one layer to the other. In this paper we investigate the influence of network parameters on vertical hard handover performance in a cell environment. The work considers two layers of cells: a layer of macrocells and a layer of microcells. Handover requests enter the macrocell from neighbor macrocells and from microcells that belong to a different layer. Using Markov chain analysis and simulation we calculate network performance parameters such as mean queue delay, handover dropping probability and channel utilization. We also compare the handover performance for the macrocell and macrocell traffic separately. Our results show the influence of total channels, maximum queue size and handover request arrival rate on handover performance. They also show that when the traffic from each layer is treated with equal priority in the system, the performance of each layer is comparable.

Performance Evaluation of Vertical Hard Handovers in Cellular Mobile Systems

With the rapid increase of new and diverse cellular mobile services, the overlapping of cells has become typical in the majority of the coverage area of the network. Vertical handovers occur between two layers of cells when a user is switched from one layer to the other. In this paper we investigate the influence of network parameters on vertical hard handover performance in a cell environment. The work considers two layers of cells: a layer of macrocells and a layer of microcells. Handover requests enter the macrocell from neighbor macrocells and from microcells that belong to a different layer. Using Markov chain analysis and simulation we calculate network performance parameters such as mean queue delay, handover dropping probability and channel utilization. We also compare the handover performance for the macrocell and macrocell traffic separately. Our results show the influence of total channels, maximum queue size and handover request arrival rate on handover performance. They also show that when the traffic from each layer is treated with equal priority in the system, the performance of each layer is comparable.

Mobile relay deployment in multihop relay networks

In multihop relay networks such as LTE-Advanced and the mobile WiMAX network, subscribers move in and out of the Fixed Relays’ (FRs) coverage in different periods. Frequent handover requests generated by population mobility lead to low data rate and load imbalances among FRs. To fulfill the requirement of subscribers, Mobile Relays (MRs), are considered to patrol FRs to offload their relay task which can improve the efficiency of the access network. In this paper, we define and study the Minimum Mobile Relay Path selection problem (MMRP), whose objective is to deploy minimum MRs to patrol FRs when they are “busy”. First, Markov chains are used to predict FRs’ busy period which is then transformed into a busy period graph. Based on this busy period graph, we propose solutions to different relaying scenarios. Maximum matching and the maximum flow technologies are adopted to find heuristic algorithms for these different scenarios respectively. Theoretical analysis and simulation results show that, compared with traditional search algorithms, solutions based on the maximum matching and the maximum flow technologies have O(n2) complexity, where n is the number of FRs, and they perform better than traditional ways on the number of paths and system overhead. Moreover, the solution using predicted busy periods is more efficient than that when FRs’ busy periods are presupposed.

Selection of handoff method for serving air traffıc control communication in Leo satellite constellation

Due to the satellite motion with respect to the earth’ s surface and the aircraft’s mobility, it is required to handover frequently in the process of communicating , In This paper ,assuming that the aircraft’s location and speed can be determined , we proposes a suitable study for managing handover in satellite constellations for serving air traffic communication . The main objective of This study is selecting the best scheme which reduce significantly contact failure Probability ,this techniques are: non priority, priority, and queuing handoff schemes ,in this paper we are interested only in schemes that prioritize handover request in particular handoff queuing schemes. Channel allocation strategy (FCA) is employed, and the simulation results obtained concern: call blocking probability, handover failure probability, and average waiting time in the queue. Also simulation results are compared to choose the best one which reduces the contacts failureownership ratios. That supports more firm specific information is incorporated into stock prices as the ratio of foreign ownership increases.

A cloud-assisted handover optimization strategy for mobile nodes in industrial wireless networks

Connectivity restoration is an important aspect of the survivability strategies of wireless networks. In industrial wireless networks, especially with mobile nodes, connectivity restoration and maintenance directly determines the overall performance of the network. Handover strategies are research hotspots in this field. However, current common handover strategies have many disadvantages, such as frequent handover requests, latency and the lack of consideration of the network performance. These drawbacks are harmful to IoT (Internet of Things) networks. Although studies on wireless networks have proposed many solutions, the proposed schemes are not intended to meet the demands of industrial wireless applications, where real-time and stable performance are required. Therefore, this paper proposes a novel fixed-path mobile node handover strategy (CAFP), which is assisted by cloud services and an ants-colony algorithm. Our approach uses optimization for industrial wireless node handover sequences, execution and handover schemes in different cases. Compared to other traditional handover strategies, our simulation results show that the CAFP has advantages in terms of handover times, latency and the network's average payload. Additionally, this algorithm can decrease the processing capacity of mobile wireless nodes.

Modelling and simulation of predictive handover control mechanisms for fast moving mobile nodes in wireless networks

When a mobile node (MN) is moving at a high speed from one network to another network, internet connectivity is degraded as MN cannot complete the handover within the required time owing to delayed triggering of handover request. To ensure seamless connectivity without performance degradation, traditional handover mechanism needs to be enhanced. In this paper, a media independent handover (MIH)-based handover triggering scheme is proposed based on the mobility prediction of MN. Handover triggering is predicted by calculating link expiration time that depends on velocity, direction and distance of MN from the access point. Scanning process required for traditional MIH networks is eliminated using information server (IS) that estimates the received signal strength (RSS) of candidate networks based on the location of MN. Simulation results show that the proposed scheme reduces the handover latency and improves the throughput in homogenous networks at varying velocities of MN.

A Dual-Parameter Adaptive Timer Decision Algorithm for Load Balancing and Ping-Pong Handover Control in LTE Networks

Background/Objectives: In order to increase spectral efficiency and lower handover signaling overhead in long term evolution network, load balancing optimisation and ping-pong handover avoidance is important. Methods/Statistical Analysis: Here, an algorithm that uses an adaptive timer was developed to run on the network. The network comprises of seven cells numbered 1, 2, 3, 4, 5, 6 and 7 respectively. Each cell is powered by a centrally placed cell equipped with omni-directional antennas to covers its cell area and neighboring cell-edge users. Receive signal strength and cell load estimates were jointly used to model the handover adaptive timer for decision accuracy. Findings: Findings were made the validation of the Key Performance Indicators (KPIs) using computer simulations. The KPIs of attention in this research were load balancing index of the network, number of unsatisfied users, cumulative number of ping-pong handover request, cumulative number of non-ping-pong handover request and average throughput of the cell. The results of our proposal out perform two other references cited in literature. In terms of load distribution index specifically, a 95% level was achieved after only 150 load balancing cycles. Conclusion/Improvements: The propose solution proves great for its ability to effectively detect ping-pong handover request and non-ping-pong handover request while load balancing decision process is in progress.

Ad hoc cooperative vertical handover for next-generation heterogeneous networks

We propose a new vertical handover scheme that uses cooperative ad hoc nodes, instead of interworking via backhaul, for the fast handover of mobile nodes (MN) in next-generation heterogeneous network environments. An MN requiring a vertical handover requests an adjacent ad hoc node to undertake some of the handover procedures that require latency, such as authentication and registration procedures, and to process them in place of the requested MN before the handover completion. A vertical handover procedure that uses this takeover technique is described in detail and its performance is analyzed by investigating the success probability of takeover. The results confirm that the proposed vertical handover scheme using takeover reduces both connection disruption time and packet loss compared with conventional vertical handover schemes without takeover.

Resource Reservation to Support Service Continuity in OFDMA Systems

When the load in a multi-cell orthogonal frequency division multiple access (OFDMA) system is allowed to excessively increase in face of frequent handover, the cell area becomes smaller than the designed size, and thus continuity of quality of service (QoS) for handover requests cannot be guaranteed. To efficiently support the mobility of a mobile terminal (MT), we should adaptively cope with the resource demand of handover calls. This paper proposes a twofold resource-reservation scheme for OFDMA systems to guarantee continuity of QoS for various mobile multimedia services during MT handover from lightly to heavily loaded cells. Our twofold scheme attempts to guarantee service continuity for handover and to maximize resource allocation efficiency. We performed a simulation to evaluate our scheme in terms of outage probability, handover failure rate, total throughput, and blocking rate.

Interference management via access control and mobility prediction in two-tier heterogeneous networks

Two-tier heterogeneous networks (HetNets), where the current cellular networks, i.e., macrocells, are overlapped with a large number of randomly distributed femtocells, can potentially bring significant benefits to spectral utilization and system capacity. The interference management and access control for open and closed femtocells in two-tier HetNets were focused. The contributions consist of two parts. Firstly, in order to reduce the uplink interference caused by MUEs (macrocell user equipments) at closed femtocells, an incentive mechanism to implement interference mitigation was proposed. It encourages femtocells that work with closed-subscriber-group (CSG) to allow the interfering MUEs access in but only via uplink, which can reduce the interference significantly and also benefit the marco-tier. The interference issue was then studied in open-subscriber-group (OSG) femtocells from the perspective of handover and mobility prediction. Inbound handover provides an alternative solution for open femtocells when interference turns up, while this accompanies with PCI (physical cell identity) confusion during inbound handover. To reduce the PCI confusion, a dynamic PCI allocation scheme was proposed, by which the high handin femtocells have the dedicated PCI while the others share the reuse PCIs. A Markov chain based mobility prediction algorithm was designed to decide whether the femtocell status is with high handover requests. Numerical analysis reveals that the UL interference is managed well for the CSG femtocell and the PCI confusion issue is mitigated greatly in OSG femtocell compared to the conventional approaches.

Location-Based Knowledge Handover Optimization (LBKHO) Algorithm for mobile Network

Handover is a very important process in any mobile communication network because it allows the call continuation with high mobility and to supply Quality of Service (QoS) to the users. However the handover increases the signaling load in the network and increase the mobile battery consumption. Location based service offered a great opportunity for application development in the mobile field. In this paper Location- Based Knowledge Handover Optimization algorithm (LBKHO) is proposed, the location based knowledge is used to improve the network performance by reducing the number of handover request, which reduces the signaling load in the network. From our the simulation results show that the proposed algorithm (LBKHO) has reduced the number of handover requests and the number of failed handovers, and when compared with the model (Adaptive Handover Initialization Region) proposed in a previous study, found that requests for handover in the proposed in our algorithm much less. Which reduces the signaling load in the network so that network performance can be improved.