International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 08 Issue: 04 | Apr 2021 www.irjet.net p-ISSN: 2395-0072 © 2021, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 3094 Optimization of Adaptive Call Admission Control Schemes for LTE Networks with Bandwidth Reservation Deepak Kumar Mahato 1 , Prof. Amrita Khera 2 1 Research scholar, Electronics & Communication Department, Trinity Institute of Technology & Research, Bhopal 2 Professor, Electronics & Communication Department, Trinity Institute of Technology & Research, Bhopal ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Consumers of 4G wireless networks have grown exponentially in recent years as they discover how user-friendly the service is. Due to the large number of users and their regular requests, it is important to make use of the limited network resources available to ensure the highest level of service quality (QoS). In 4G networks, the call admission control (CAC) scheme has a significant effect on ensuring QoS for different users with different QoS specifications. Reservation-based schemes and bandwidth degradation schemes have recently been proposed with the aim of making efficient use of network resources and ensuring that admitted calls meet QoS requirements. In this paper, we propose a novel CAC scheme that makes efficient use of network resources while avoiding traffic starvation. The scheme has an adaptive threshold value that changes network capacity when there is a lot of traffic. In terms of admitting several calls and guaranteeing QoS to all traffic types in the network, simulation results show that the proposed scheme greatly outperforms the reservation-based scheme and bandwidth degradation schemes. Key Words: Call admission control, call blocking probability, calls dropping probability, Handoff, Quality of service. 1. INTRODUCTION The implementation of promising technology by the 3rd Generation Partnership Project (3GPP) Long Term Evolution was necessitated by the rapid growth of cellular networks across various technologies (LTE). To increase user data rates, provide wide area coverage, and boost spectral performance, LTE uses Orthogonal Frequency Multiple Access (OFDMA) and Multi-user Multiple-Input Multiple-Output (MU-MIMO) technologies [1]. There are significant challenges in meeting Quality of Service (QoS) standards and reducing network congestion in order to achieve these goals. It is essential to have an efficient radio resource management system in order to solve the problems listed above (RRM). One of the most basic RRM techniques is Call Admission Control (CAC). The CAC scheme is a method of accepting a new call or handoff call into the network while maintaining the QoS of current calls without causing any call drops. The process of moving an ongoing call or data session from one channel to another in a cellular network without violating QoS specifications is referred to as a handoff call [2]. The CAC scheme arranges handoff calls to the network based on available bandwidth to meet consumer QoS requirements. As a result, some bandwidth is set aside for incoming handoff calls, and the remaining bandwidth is assigned to new calls. An successful CAC scheme must provide efficient network resource usage as well as excellent QoS to admitted users at the same time. The work in [3] suggested a channel-borrowing scheme in which best effort (BE) traffic borrows bandwidth from high-priority calls. For the rest of this article, we'll refer to [3] as the Reservation Based scheme. For its CAC scheme, the Reservation Based scheme used modeling and approximation methods. However, due to the lack of user traffic, individual modeling and approximation of key device parameters is inefficient for the wireless network. Additionally, the scheme used time-varying status to dynamically reserve some network bandwidth for handoff calls. However, if some bandwidth is borrowed and reserved for handoff calls, but the network only receives a few or no handoff calls, those network resources can be underutilized or wasted, resulting in inefficient network resource utilization. To address the inefficiency of Reservation Based CAC, we propose An Adaptive Call Admission Control with Bandwidth Reservation for Downlink LTE Networks in this paper. To begin, the mechanism establishes new CAC requirements based on the types of traffic. When networks have insufficient resources under a heavy load situation, the latest CAC criteria incorporate a bandwidth loss strategy to generate opportunities for new calls. Following that, based on the traffic strength intensity, an adaptive threshold value is used to reserve sufficient bandwidth for handoff calls. This paper makes three significant contributions. The first goal is to increase the throughput of BE traffic, which is currently being slowed due to inefficient network resource use. The second contribution is the use of an adaptive threshold value that changes the network status to reduce call blocking probability (CBP) and call dropping probability (CDP). Finally, an analytical model based on a two-level Markov chain was created to evaluate the proposed scheme's results.