Modified Largest Weighted Delay First Research Articles

LTE Cellular Networks Packet Scheduling Algorithms in Downlink and Uplink Transmission: A Survey

This survey paper provides a detailed explanation of Long Term Evolution (LTE) cellular network’s packet scheduling algorithms in both downlink and uplink directions. It starts by explaining the difference between Orthogonal Frequency Division Multiple Access (OFDMA) that is used in downlink transmission, and Single Carrier – Frequency Division Multiple Access (SC-FDMA) is used in uplink. Then, it explains the difference between the LTE scheduling process in the donwlink and uplink through explaining the interaction between users and the scheduler. Then, it explains the most commonly used downlink and uplink scheduling algorithms through analyzing their formulas, characteristics, most suitable conditions for them to work in, and the main differences among them. This explanation covers the Max Carrier-toInterference (C/I), Round Robin (RR), Proportional Fair (PF), Earliest Deadline First (EDF), Modified EDF-PF, Modified-Largest Weighted Delay First (M-LWDF), Exponential Proportional Fairness (EXPPF), Token Queues Mechanism, Packet Loss Ratio (PLR), Quality Guaranteed (QG), Opportunistic Packet Loss Fair (OPLF), Low Complexity (LC), LC-Delay, PF-Delay, Maximum Throughput (MT), First Maximum Expansion (FME), and Adaptive Resource Allocation Based Packet Scheduling (ARABPS). Lastly, it provides some concluding remarks.

Enhanced PF Scheduling Algorithm for LTE Networks

Scheduling Algorithm is a key Radio ResourceManagement (RRM) mechanism to achieve Quality of Service(QoS) requirements and to optimize system performance of LongTerm Evolution (LTE) network. The LTE standard does notspecify a scheduling algorithm and some schedules have beenproposed in the literature. Most of them consider the channelstate or some QoS metric, however, they do not consider thePF characteristics and the delay required by the user. Then, anenhanced scheduling algorithm was proposed based on Latency-Rate (LR) server theory and system characteristics specifiedby the LTE standard. Properties of this proposal have beeninvestigated theoretically and through simulations. A simulationis presented with video traffic and also performance comparisonswith Proportional Fairness (PF) and Modified Largest WeightedDelay First (MLWDF) schedulers. The results show that theproposed schedule has a better performance compared with theabove schedulers.

Design of dynamic resource allocation scheme for real-time traffic in the LTE network

The 5G wireless technology is recently standardized for meeting intense demand. The Long Term Evolution (LTE) technology provides an easy, time-saving, and low-cost method for deploying a 4G/5G network infrastructure. To support multimedia service and higher bandwidth data delivery, an LTE MAC layer has Quality of Service (QoS) support with several QoS class indicator (QCI) levels. Based on LTE current QCI priority and QoS requirements in UEs, the original Max-Rate scheduler, Proportionally Fair (PF) and Modified Largest Weighted Delay First (M-LWDF) algorithms could not achieve their goal owing to the UE’s dynamic physical capacity with a different Channel Quality Indicator (CQI) at run time. For better QoS service than LTE networks, per UE’s CQI state for each resource block (RB) must be considered simultaneously in LTE MAC layer resource allocation with cross-layer support. As downlink real estimated capacity is dynamic owing to a UE’s periodic CQI reporting, the CQI state in LTE scheduling must be considered. This study proposes a smart and flexible scheme for Enhanced Utilization Resource Allocation (EURA) including three novel mechanisms that can dynamically fit UEs’ CQI states. The simulation results in this study demonstrate that the proposed EURA scheme outperforms the contrast schemes (Max-Rate, EXP/PF and M-LWDF), can save more rare radio capacity, and improve the utilization of radio resource assignment.

Delay threshold scheduling algorithm for LTE downlink systems

This paper proposes a delay threshold scheduling (DTS) algorithm for the scheduling of requests in real-time multimedia applications using LTE downlink systems, which takes into account channel conditions as well as the packet waiting time. Delay thresholds were adopted to enable the differentiation of packets in conjunction with proportional weighting between channel conditions and packet waiting time for the prioritisation of real-time services. Simulation results demonstrate that compared to the results obtained using Modified Largest Weighted Delay First (M-LWDF), Exponential Proportional Fair (EXP/PF), and Channel Dependent Earliest Due Date (CD-EDD), the proposed DTS algorithm is able to increase video traffic throughput and decrease packet delays and the packet loss ratio for real-time services.

Delay threshold scheduling algorithm for LTE downlink systems

This paper proposes a delay threshold scheduling (DTS) algorithm for the scheduling of requests in real-time multimedia applications using LTE downlink systems, which takes into account channel conditions as well as the packet waiting time. Delay thresholds were adopted to enable the differentiation of packets in conjunction with proportional weighting between channel conditions and packet waiting time for the prioritisation of real-time services. Simulation results demonstrate that compared to the results obtained using Modified Largest Weighted Delay First (M-LWDF), Exponential Proportional Fair (EXP/PF), and Channel Dependent Earliest Due Date (CD-EDD), the proposed DTS algorithm is able to increase video traffic throughput and decrease packet delays and the packet loss ratio for real-time services.

A Quality of Service (QoS) Aware Scheduling Algorithm to Boost QoS of Cell-Edge Users in LTE Networks

LTE is the abbreviation of Long Term Evolution. LTE networks are developed to provide enhanced Quality of Service (QoS), as today’s cellular world and its high speed multimedia applications demand variety of QoS along with a high speed data rate. Scheduling is a key feature of any network to achieve QoS requirements. The QoS widely depends on the distance of user from the Evolved- Node-B (eNB). The user near eNB experience good QoS and the user far away from eNB experiences poor QoS. The system performance is widely affected due to this. Hence, the ultimate and supreme goal of this research work is to enhance the QoS of the cell edge user and improve network performance. Proposed scheduling algorithm i.e. Improved Extended Modified Largest Weighted Delay First (IE-MLWDF) improves the cell edge throughput along with QoS of the cell - edge users. The paper compares IE-MLWDF with its previous versions namely Modified Largest Weighted Delay First (MLWDF) and Extended - MLWDF in terms of various network parameters. This paper presents a detailed analysis of a scheduling algorithm to enhance QoS of cell edge users to provide better network goals. This algorithm can further be extended or improved to make it more effective.

A new long‐term evolution downlink delay based lean scheduler

A new delay‐based long‐term evolution scheduler is proposed in this paper. The scheduler allows sharing of radio and base station resources between different radio bearers. It provides a trade‐off between user fairness and system performance. The proposed algorithm is based on the scheduler having knowledge of the age of real‐time (RT) applications packets. By considering the age of the packet with the lean production concept, the scheduler can determine different types of RT application packets and must be scheduled within their packet delay budget. The proposed algorithm is called the delay‐based lean scheduler (DBLS). Simulation results shows that the proposed DBLS algorithm provides superior throughput and delay performance to the modified largest weighted delay first (M‐LWDF) algorithm irrespective of the number of users. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Exponential MLWDF (EXP-MLWDF) Downlink Scheduling Algorithm Evaluated in LTE for High Mobility and Dense Area Scenario

Nowadays, with the advent of smartphones, most of people started to make voice and video conference calls continuously even in a high mobility scenario, the bandwidth requirements have increased considerably, which can cause network congestion phenomena. To avoid network congestion problems and to support high mobility scenario, 3GPP has developed a new cellular standard based packet switching, termed LTE (Long Term Evolution). The purpose of this paper is to evaluate the performance of the new proposed algorithm, named Exponential Modified Largest Weighted Delay First ‘EXP-MLWDF’, for high mobility scenario and with the presence of a large number of active users, in comparison with the well-known algorithms such as a proportional fair algorithm (PF), Exponential Proportional Fairness (EXP/PF), Logarithm Rule (LOG-Rule), Exponential Rule (EXP-Rule) and Modified Largest Weighted Delay First (MLWDF). The performance evaluation is conducted in terms of system throughput, delay and PLR. Finally, it will be concluded that the proposed scheduler satisfies the quality of service (QoS) requirements of the real-time traffic in terms of packet loss ratio (PLR), average throughput and packet delay. Because of the traffic evolution, some key issues related to scheduling strategies that will be considered in the future requirements are discussed in this article.

Enhanced Quality of Service of Cell-Edge User by Extending Modified Largest Weighted Delay First Algorithm in LTE Networks

Long Term Evolution (LTE) is the prominent technology in Fourth Generation (4G) communication standards, which provides higher throughput and better Quality of Service (QoS) to all users. However, users in the cell-edge area are receiving comparatively low QoS due to the distance from eNodeB (eNB) and bad channel conditions. The Conventional Modified Largest Weighted Delay First (MLWDF) algorithm is unable to resolve this issue, as it does not consider the location of the user. This paper proposes an extended MLWDF (EMLWDF) downlink scheduling algorithm to provide better services to the cell-edge user as well as to the cell-center user. The proposed algorithm divides the eNB cell area into inner and outer regions. It includes the distance of the user from attached eNB, received Signal to Interference plus Noise Ratio (SINR) and error probability into the original algorithm. The simulated results are compared with other well-known algorithms and the comparison shows that the proposed algorithm enhances overall 56.23% of cell-edge user throughput and significantly improves the average user throughput, fairness index, and spectral efficiency.

New Combined Downlink Scheduling Algorithm for LTE Networks

Considered as the 4th generation network, the LTE (Long Term Evolution) was defined by the 3GPP consortium as a succession of these predecessors, allowing the improvement of the QoS offered to the customers. Due to the limitations at the bandwidth, Radio Resource Management (RRM) remains one of the important aspects in cellular networks. The Packet Scheduling is an essential mechanism of the RRM procedure. It is used to define the distribution method of radio resources. The main objective of these mechanisms is the improvement of the performance of the LTE system for all users. This is why scheduling algorithms are of great importance in the resources management. And since they are not defined in 3GPP specifications, they become a vital subject of research. In this paper, we proposed a new downlink scheduling algorithm named Combined PF-MLWDF-EXP/PF (CPMEP) and we compared its performances in a Single Cell with Interference scenario with the well-known schedulers such as Proportional Fair (PF), Modified Largest Weighted Delay First (MLWDF) and Exponential Proportional Fairness (EXP/PF). The simulation results show that the combined algorithm is more efficient for different applications, despite it has limitations in terms of Fairness Index and Throughput for Non Real-Time services.

WE-MQS: A new LTE Downlink Scheduling Scheme for Voice Services based on User Perception

The Long Term Evolution (LTE) is a high data rates and fully All-IP network. Scheduling and resource allocation are very important tasks in LTE network. So that, the optimization of the real-time services transmission is very essential. However, there are many challenges when deploying the live multimedia services such as VoIP, Video, etc. This paper proposes a new scheduling scheme which based on the Wideband (WB) E-model, Channeland QoS-Aware (known as WE-MQS scheduler) for voice traffic in LTE downlink direction. The voice traffic flow is very sensitive to network impairments such as delay, packet loss, jitter, etc. The proposed scheduling scheme is based on the extension of the WB E-model and the consideration of Maximum Queue Size (MQS) as a factor for the metric. Since this scheduling scheme considers Mean Opinion Score (MOS) values, thus, it gets higher user perception. The simulation results show that the proposed scheme has the performance which not only satisfies QoS requirements of voice services but also outperforms well-known schedulers such as Frame Level Scheduler (FLS), Modified Largest Weighted Delay First (MLWDF) and Exponential/Proportional Fair (EXP/PF) schedulers in terms of delay for all the number of user (NU) and Packet Loss Rate (PLR) when the NU is more than 47. For the cell throughput, Fairness Index (FI), and Spectral Efficiency, the proposed scheduler is always in the middle of the remaining schedulers. The performance evaluation is compared in terms of Delay, PLR, Throughput, FI, and FI for FLS, M-LWDF, EXP/PF schedulers and the proposed one.

Interference Mitigation Techniques Using Receiver Processing and Resource Allocation

Heterogeneous network consists of the pico cells overlaid over the macro cell coverage area in a wireless cellular network. The pico cells are deployed to increase the capacity of the homogeneous network by reusing the spectrum further. However, more users will tend to be associated to the macro cell due to the fact that the transmit power of the pico cell is low. In order to increase the number of users associated to the pico cell, range extension techniques like biased association are used. This will cause severe interference to cell edge users of the pico cell from the macro cell causing degradation in throughput performance in the cell range extension area. In this paper, interference mitigation using receiver processing along with different scheduling techniques is proposed to improve the throughput, average delay, and the packet delivery ratio performance of the system. The performance comparison of the round robin, proportional fair and modified largest weighted delay first (MLWDF) algorithm for resource allocation using interference suppressing receiver is done, and analyzed. It is shown that the MLWDF algorithm achieves the highest throughput with minimum average delay of packets with the best delivery ratio.

WE-MQS-VoIP Priority: An enhanced LTE Downlink Scheduler for voice services with the integration of VoIP priority mode

The Long Term Evolution (LTE) is a high data rates and fully All-IP network. It is developed to support well to multimedia services such as Video, VoIP, Gaming, etc. So that, the real-time services such as VoIP, video, etc. need to be optimized. Nevertheless, the deployment of such live stream services having many challenges. Scheduling and allocating radio resource are very important in LTE network, especially with multimedia services such as VoIP. When voice service transmitted over LTE network, it is affected by many network impairments where there are three main factors including packet loss, delay, and jitter. This study proposes a new scheduler which is based on VoIP priority mode,Wideband (WB) E-model, QoS- and Channel-Aware (called WE-MQS-VoIP Priority scheduler) for voice services in LTE downlink direction. The proposed scheduling scheme is built based on the WB E-model and Maximum Queue Size (MQS). In addition, we integrate the VoIP priority mode into our scheduling scheme. Since the proposed scheduler considers the VoIP priority mode and user perception, thus, it improves significantly the system performance. The results demonstrate that the proposed scheduler not only meets QoS demands of voice calls but also outperforms Modified Largest Weighted Delay First (M-LWDF) in terms of delay, Packet Loss Rate (PLR) for all number of user (NU) and excepting NU equals 30, respectively. For Fairness Index (FI), cell throughput, and Spectral Efficiency (SE), the difference among the packet schedulers is not significant. The performance evaluation is compared in terms of Delay, PLR, Throughput, FI, and SE.

New Scheduling Algorithm Proposed for Real Time Traffic Over LTE Femto-Cell

Due to the inadequate indoor signal penetration, the indoor environment coverage becomes poor, which diminishes the quality of voice and video applications and slows down high-speed data services, which leads to customer churn, who expect high quality of service. To keep customers satisfied, Long Term Evolution (LTE) has developed a new advanced technology called FemtoCell, conceived to boost cellular network performance and is achieved with the use of access points installed by home users. The purpose of this paper is to analyze the performance of new proposed algorithm for voice and video over LTE FemtoCell, and to compare its performances with some well-known algorithms such as the proportional fair algorithm (PF), Exponential Proportional Fairness (EXP/PF), Logarithm Rule (LOG-Rule), Exponential Rule (EXP-Rule) and Modified Largest Weighted Delay First (MLWDF), The performance evaluation is conducted in terms of system throughput, delay, and Packet Loss Ratio. Finally it will be concluded that the proposed scheduler satisfies the quality of service (QoS) requirements of the real-time traffic in terms of packet loss ratio (PLR), average throughput and packet delay. This paper also discusses the key issues of scheduling algorithms to be considered in future traffic requirements.

A New Downlink Scheduling Algorithm Proposed for Real Time Traffic in LTE System

Abstract The Third Generation Partnership Project (3GPP) has developed a new cellular standard based packet switching allowing high data rate, 100 Mbps in Downlink and 50 Mbps in Uplink, and having the flexibility to be used in different bandwidths ranging from 1.4 MHz up to 20 MHz, this standard is termed LTE (Long Term Evolution). Radio Resource Management (RRM) procedure is one of the key design roles for improving LTE system performance, Packet scheduling is one of the RRM mechanisms and it is responsible for radio resources allocation, However, Scheduling algorithms are not defined in 3GPP specifications. Therefore, it gets a track interests for researchers. In this paper we proposed a new LTE scheduling algorithm and we compared its performances with other well known algorithms such as Proportional Fairness (PF), Modified Largest Weighted Delay First (MLWDF), and Exponential Proportional Fairness (EXPPF) in downlink direction. The simulation results shows that the proposed scheduler satisfies the quality of service (QoS) requirements of the real-time traffic in terms of packet loss ratio (PLR), average throughput and packet delay. This paper also discusses the key issues of scheduling algorithms to be considered in future traffic requirements.

A novel LTE scheduling algorithm for green technology in smart grid.

Smart grid (SG) application is being used nowadays to meet the demand of increasing power consumption. SG application is considered as a perfect solution for combining renewable energy resources and electrical grid by means of creating a bidirectional communication channel between the two systems. In this paper, three SG applications applicable to renewable energy system, namely, distribution automation (DA), distributed energy system-storage (DER) and electrical vehicle (EV), are investigated in order to study their suitability in Long Term Evolution (LTE) network. To compensate the weakness in the existing scheduling algorithms, a novel bandwidth estimation and allocation technique and a new scheduling algorithm are proposed. The technique allocates available network resources based on application’s priority, whereas the algorithm makes scheduling decision based on dynamic weighting factors of multi-criteria to satisfy the demands (delay, past average throughput and instantaneous transmission rate) of quality of service. Finally, the simulation results demonstrate that the proposed mechanism achieves higher throughput, lower delay and lower packet loss rate for DA and DER as well as provide a degree of service for EV. In terms of fairness, the proposed algorithm shows 3%, 7 % and 9% better performance compared to exponential rule (EXP-Rule), modified-largest weighted delay first (M-LWDF) and exponential/PF (EXP/PF), respectively.

Performance Analysis of Service Based Scheduler in LTE OFDMA System

Long Term Evolution (LTE) is the wireless broadband technology developed by Third Generation Partnership Project (3GPP) to support higher data rate. Resource scheduling in LTE plays an important role in deciding the overall network performance. In this paper, a new scheduling approach called Service Based Scheduler (SBS) is proposed that is suitable for real time services. In this method, two tag values called maximum tag value (Tmax) and minimum tag value (Tmin) are estimated for the packets based on the type of bearers. Tmax is calculated for Guaranteed Bit Rate (GBR) bearers and Tmin is calculated for non GBR bearers. Then, separate ascending sorted lists are formed for Tmax and Tmin. The packets from the Tmax list are allocated first in spite of users' channel condition. After the allocation of packets from Tmax list, if the current Transmit Time Interval (TTI) has more resources, then packets from Tmin list are allocated strictly based on users' channel conditions. The proposed scheduling approach provides better performance for real time services compared to other schemes like Proportional Fairness (PF), Modified Largest Weighted Delay First (MLWDF), Exponential rule (EXP rule) and Logarithmic rule (LOG rule).

Resource Allocation in OFDMA Wireless Communications Systems Supporting Multimedia Services

Abstract. We design a resource allocation algorithm for downlink of orthogonal frequency division multiple access (OFDMA) systems supporting real-time (RT) and best-effort (BE) services simultaneously over a time-varying wireless channel. The proposed algorithm aims at maximizing system throughput while satisfying quality of service (QoS) requirements of the RT and BE services. We take two kinds of QoS requirements into account. One is the required average transmission rate for both RT and BE services. The other is the tolerable average absolute deviation of transmission rate (AADTR) just for the RT services, which is used to control the fluctuation in transmission rates and to limit the RT packet delay to a moderate level. We formulate the optimization problem representing the resource allocation under consideration and solve it by using the dual optimization technique and the projection stochastic sub gradient method. Simulation results show that the proposed algorithm well meets the QoS requirements with the high throughput and outperforms the modified largest weighted delay first (M-LWDF) algorithm that supports similar QoS requirements.

QoS-aware composite scheduling using fuzzy proactive and reactive controllers

We consider in this paper downlink scheduling for different traffic classes at the MAC layer of wireless systems based on orthogonal frequency division multiple access (OFDMA), such as the recent 3rd Generation Partnership Project (3GPP) long-term evolution (LTE)/LTE-A wireless standard. Our goal is to provide via the scheduling decisions quality of service (QoS), but also to guarantee fairness among the different users and traffic classes (including delay-sensitive and best-effort traffic). QoS-aware scheduling strategies, such as modified largest weighted delay first (M-LWDF), exponential (EXP), exponential proportional fair (EXP-PF), and the log-based scheduling rules, prioritize delay-sensitive traffic by considering rules based on the head-of-line (HoL) packet delay and the tolerated packet loss rate, whereas they serve best-effort traffic by considering the classical proportional fair (PF) rule. These scheduling rules do not prevent resource starvation for best-effort traffic. On the other side, if both traffic types are scheduled according to the PF rule, then delay-sensitive flows suffer from delay bound violations. In order to fairly distribute the resources among different service classes according to their QoS requirements and channel conditions, we employ the concept of fuzzy logic in our scheduling framework. By employing the fuzzy logic concept, we serve all the traffic classes with one priority rule. Simulation results show better intra-class and inter-class fairness than state-of-the-art scheduling rules. The proposed scheduling framework enables to appropriately balance delay requirements of traffic, system throughput, and fairness.

Low Complexity in Exaggerated Earliest Deadline First Approach for Channel and QoS-aware Scheduler

Long Term Evolution (LTE) is a Quality of Service (QoS) provisioning wireless network for today’s technology and as well as for future demands. There is a high demand for better network performance over LTE network, either for real-time or non-real-time traffic. Specifically, the existing scheduling algorithms for real-time application, Exponential/Proportional Fair (EXP/PF), Proportional Fair (PF), and Modified-Largest Weighted Delay First (M-LWDF) have not fully optimized in LTE network. Hence, this paper aims to deliver new scheduling algorithm in the LTE network which overcomes several QoS and channel concerns. Several algorithms were studied, tested and compared which includes EXP/PF, PF, and M-LWDF, which are the popular scheduling algorithms for real-time application in today’s deployment. A typical LTE network is simulated and several experiments were conducted. Extensive simulation results showed that our proposed scheduling algorithm, Exaggerated Earliest Deadline First (E2DF), has outperformed the three existing scheduling algorithms. The proposed algorithm is a LTE compliance module and it able to provide great performance improvement as compared to the other algorithms for real-time application. 