Long Term Evolution Cellular Networks Research Articles

Evaluación del desempeño de una HetNet de caravanas, caso de estudio: centro histórico de Quito

In the Quito historical center, due to its narrow streets, vehicular congestion is very frequent. Intelligent vehicles can be used, which have fully automatic driving, but need to interact with each other. The manner in which smart vehicles interact is through vehicle networks, which require the installation of an infrastructure called RSU (Road Side Unit) that uses the IEEE 802.11p standard and the RSU allows sending vehicle information to more distant places. However, installing RSUs requires an economic investment, so, as an alternative, it can be combined with an already deployed infrastructure such as the LTE (Long Term Evolution) cellular network, forming a heterogeneous network (HetNet). This paper seeks to analyze the behavior of the platooning HetNet through the analysis of physical and technical parameters of two network scenarios within of the Quito historical center.

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.

Analysis of Factors Affecting the Use of the 64QAM Modulation on the Long-Term Evolution Network by Using Random Forest Method

Nowadays internet traffic using cellular telecommunication network is increasing very rapidly. Good LTE (Long-Term Evolution) cellular network performance is very important for any telecommunication operator to maintain customer satisfaction. Poor network performance can also cause customers to switch to other operators. One of the indicator variables in observing the radio quality of the LTE cellular network is Penetration using 64QAM Modulation. 64QAM modulation can transmit higher bitrates with lower power usage. 64QAM modulation will be used if the Channel Quality Index (CQI) condition is very good. Network quality improvement can be done by adding new BTS or optimizing existing BTS. The addition of new BTS will increase coverage, quality, and capacity but cost is high, and the time required to build BTS is also long, while improving network quality by optimizing BTS can be done by purchasing LTE features and costs incurred still relatively low. In increasing the penetration of using 64QAM modulation, it is necessary to analyze the other variables. The traditional method to improve this Key Performance Indicator (KPI) requires an expert and professional but is often inaccurate and spends a lot of time finding the factors that cause it. To solve this problem, Random forest method is proposed. By knowing the variables that have a significant effect on network quality, the capital costs incurred by cellular operators for improving network quality will be more effective and efficient because the capital costs invested only focus on influencing variables such as purchasing LTE network features only done for those related to these variables. The results of this study, we make CQI improvement flow based on the classification of the random forest method that produces feature/variable importance.

Small-Cell Assisted Group Paging for Massive MTC in LTE Networks: Design and Analysis

Long-Term Evolution cellular networks are the main enabler for the massive Machine-Type Communications service and therefore must handle a large number of Machine-Type Devices (MTDs). To control the number of devices allowed to contend on the Physical Random Access Channel (PRACH), the group paging scheme that divides the MTDs into smaller groups and lets the network sequentially trigger the groups has been studied. However, as the number of PRACH preambles is limited, a group’s size must be kept relatively small compared to the MTD population. This paper exploits the possibility that a significant portion of the MTDs is also covered by densely deployed small-cells such that a Small-cell Base Station (SBS) may act as a representative for its MTDs during the preamble transmission step to reduce the load on PRACH. Once the SBS succeeds, its MTDs then contend locally to send their own signaling messages on the corresponding reserved uplink resources. Computer simulations show that the manageable group size can be significantly increased at a reasonable cost on the Physical Uplink Shared Channel. A theoretical model to quickly predict the effect of the ratio of MTDs that are under the coverage of the SBSs is also derived and verified.

Performance evaluation of LTE and UMTS cellular networks in Iraq with multiple terrains

Cellular network planning is an essential stage that precedes implementation phase. The planning performance is widely dependent on the terrestrial features of the environment where a network is planned to be implemented in. This work involves the cellular planning of three networks applied in two cities, namely Baghdad and Shaqlawa, with different terrains. Two networks are planned in a flat terrain (Baghdad city) using universal mobile telecommunications system (UMTS) and long term evolution (LTE) technologies and one network is designed in a hilly terrain (Shaqlawa city) utilizing UMTS technology. In this study, several calculation themes are applied to evaluate the performance of the proposed planning such as coverage, power level, carrier to interference ratio, best server and elevation calculations. Also, some clients and points are positioned across networks to measure power levels, interference and coverage at different locations more precisely. The measurements show that the UMTS networks cover an area of 63.62 km2 compared with 81 km2 coverage area in the LTE network with different quality of service graduating from quadrature amplitude modulation (QAM16) and quadrature phase shift keying (QPSK) to voice services. In addition, comparisons between the networks are discussed and enhancement suggestions are presented in this paper.

Mobility analysis of Modified Proportional Fair scheduler in LTE/LTE-Advanced system

Packet scheduling is one of the key schemes used in Radio Resource Management (RRM) for Long Term Evolution (LTE) cellular network. It serves as the resource allocation for each time and frequency dimensions in LTE baseband processing. In previous research, a new scheduling algorithm was developed, namely the Modified-Proportional Fair (PF) scheduler that splits a single subframe into multiple time slots and allocates the resource block (RB) to the identified User Equipment (UE) in some chosen time slots and it is done continuously for each subframe depending on the instantaneous Channel Quality Indicator (CQI) feedback received from UEs. Results have shown that the Modified-PF scheduler produces the most outstanding overall performance in terms of spectral efficiency and throughput with comparable fairness as compared to other state-of-the-art schedulers, namely, Round Robin and Proportional Fair schedulers. However, the performance of the new scheduler is not analysed in UE mobility scenario. Hence, this research will determine the type of response by the scheduler towards different mobility condition by simulating the throughput and the spectral efficiency of the three schedulers for various UE velocities. It is observed that the Modified-PF again shows significant performance improvement for various mobility condition in terms of average UE throughput and average UE spectral efficiency in both single cell omnidirectional and tri-sector eNodeB. This shows that Modified-PF can be considered as one of the packet scheduling options for the LTE cellular network.

Narrowband Internet of Things: Evolutions, Technologies, and Open Issues

We are on the threshold of the explosive growth in the global Internet-of-Things (IoT) market. Comparing with the legacy human-centric applications, machine type communication scenarios exhibit totally different characteristics, such as low throughput, delay insensitivity, occasional transmission, and deep coverage. Meanwhile, it also requires the terminal devices to be cheap enough and sustain long battery life. These demands hasten the prosperity of low power wide area (LPWA) technologies. Narrowband IoT (NB-IoT) is the newest Long Term Evolution (LTE) specification ratified by the third generation partner project as one of the LPWA solutions to achieve the objectives of super coverage, low power, low cost, and massive connection. Working in the licensed frequency band, it is designed to reuse and coexist with the existing LTE cellular networks, which endows it with outstanding advantages in decreasing network installation cost and minimizing product time-to-market. In this backdrop, it has been extensively regarded as one of the most promising technologies toward the IoT landscape. However, as a new LTE standard, there are still a lot of challenges that need to overcome. This paper surveys its evolutions, technologies, and issues, spanning from performance analysis, design optimization, combination with other leading technologies, to implementation and application. The goal is to deliver a holistic understanding for the emerging wireless communication system, in helping to spur further research in accelerating the broad use of NB-IoT.

ANALYSIS OF VOIP TRAFFIC SERVICE IN 4G LTE CELLULAR NETWORKS

Background: In these days, Voice over Internet Protocol (VoIP) technology is in great demand because one cannot bear delay in voice communication. To present the services of VoIP in Long Term Evolution (LTE) systems with appropriate services of quality, it is obligatory to investigate the effectiveness of such administrations and advance the system parameters. Objectives: To study and review 4G LTE cellular networks; to analyze the performance of VoIP throughput in 4G LTE cellular networks by incorporating voice codecs and to evaluate the VoIP latency, and jitter in 4G LTE cellular networks inside voice codecs. Methods / Analysis: The projected study highlighted the examination of VoIP traffic service in 4G LTE cellular networks, using three Quality of Service (QoS) parameters; throughput, latency, and jitter by contrasting the value with three promising voice codecs (G.711, G.729, and EVS). The metrics performance was measured using simulation tool NS2. After running TCL scripts for different network scenarios trace files are formed. These trace files are so large in size and occupy more memory space. The PERL scripts are used to extract these trace files. Results achieved from simulations have been plotted on graphs with the help of MS-Excel. Findings: The overall performance analysis of VoIP traffic carrier has been analyzed by way of comparing three different codecs (G.711, G.729, and EVS) in three different network scenarios based on three key performance indicators: Throughput, Latency, and Jitter by varying the network density and varying call load. Results achieved from simulations demonstrate how a number of performance metrics such as throughput, latency, and jitter are affected by change in factors like number of nodes, voice codecs, distance between BS and SS. With all these conclusions and considering the different scenarios under which the graphs have been plotted, Environmental Studies (EVS) codec is better than other codecs in terms of higher throughput, lower latency, and lower jitter over VoIP traffic in LTE networks by stabilizing the quality of service requisites for multimedia services. Novelty / Improvement: Earlier, the overall efficiency of VoIP changed into measured over the 3G systems. On the other hand, currently there is a need to suit the necessities for higher-speed data. Thus, new standards are intended to meet these prospects that led to the promising of LTE systems. In this study, LTE module is patched with NS2 that is not supported or included by default in NS2. Another novelty is the use of EVS voice codec that is launched as a result of 3GGP. EVS codec is compared with other voice codecs such as G.711, G.729. After all, it is suggested that EVS codec is better than other codecs when using multimedia services. Keywords: EVS, LTE, VoIP, G.711, G.729

A Bandwidth Variation Pattern-Differentiated Rate Adaptation for HTTP Adaptive Streaming Over an LTE Cellular Network

Currently, HTTP adaptive streaming (HAS) is the state-of-the-art technology for mobile video streaming. The rate adaptation of HAS has been designed to make a trade-off between two contrasting requirements, i.e., enhancing the quality of a video, and reducing the probability of video freezes, by adaptively switching between different video bitrates during a video playback session. This process becomes more challenging when moving onto an long term evolution (LTE) cellular network due to the unstable nature of the wireless channel. In this paper, we propose the bandwidth variation pattern-differentiated rate adaptation (BVPDRA) algorithm for LTE cellular networks. Unlike prior works, BVPDRA does not strike a balance between the stableness and responsiveness of bitrate switching in the case of bandwidth capacity variations. BVPDRA differentiates between bandwidth variation patterns of the LTE cellular network as either constant bandwidth fluctuations or instantaneous bandwidth hopping. Accordingly, BVPDRA operates with a dual character: for the constant bandwidth fluctuations, BVPDRA performs smoothed bandwidth prediction and conservative rate switching to minimize video quality version oscillations; for the instantaneous bandwidth hopping, BVPDRA performs positive bandwidth prediction and aggressive rate switching to maximize the bandwidth utilization and minimize the risk of playback stalling. We empirically evaluate the performance of BVPDRA on an LTE cellular network testbed. The results demonstrate that BVPDRA achieves a higher average bitrate, and lower rebuffering ratio with a reduced bitrate switching frequency.

A Fast and Reliable Broadcast Service for LTE-Advanced Exploiting Multihop Device-to-Device Transmissions

Several applications, from the Internet of Things for smart cities to those for vehicular networks, need fast and reliable proximity-based broadcast communications, i.e., the ability to reach all peers in a geographical neighborhood around the originator of a message, as well as ubiquitous connectivity. In this paper, we point out the inherent limitations of the LTE (Long-Term Evolution) cellular network, which make it difficult, if possible at all, to engineer such a service using traditional infrastructure-based communications. We argue, instead, that network-controlled device-to-device (D2D) communications, relayed in a multihop fashion, can efficiently support this service. To substantiate the above claim, we design a proximity-based broadcast service which exploits multihop D2D. We discuss the relevant issues both at the UE (User Equipment), which has to run applications, and within the network (i.e., at the eNodeBs), where suitable resource allocation schemes have to be enforced. We evaluate the performance of a multihop D2D broadcasting using system-level simulations, and demonstrate that it is fast, reliable and economical from a resource consumption standpoint.

User Association and Resource Allocation Optimization in LTE Cellular Networks

As the demand for higher data rates is growing exponentially, homogeneous cellular networks have been facing limitations when handling data traffic. These limitations are related to the available spectrum and the capacity of the network. Heterogeneous networks (HetNets), composed of macro cells (MCs) and small cells (SCs), are seen as the key solution to improve spectral efficiency per unit area and to eliminate coverage holes. Due to the large imbalance in transmit power between MCs and SCs in HetNets, intelligent user association (UA) is required to perform load balancing and to favor some SCs attraction against MCs. As long term evolution (LTE) cellular networks use the same frequency sub-bands, user equipment may experience strong intercell interference (ICI), especially at cell edge. Therefore, there is a need to coordinate the resource allocation (RA) among the cells and to minimize the ICI. In this paper, we propose a generic algorithm to optimize UA and RA in LTE networks. Our solution, based on game theory, permits to compute cell individual offset and a pattern of power transmission over frequency and time domain for each cell. Simulation results show significant benefits in the average throughput and also cell edge user throughput of 40% and 55% gains respectively. Furthermore, we also obtain a meaningful improvement in energy efficiency.

A Cross-Layer Bandwidth Allocation Scheme for HTTP-Based Video Streaming in LTE Cellular Networks

This letter investigates the benefits of flexible resource allocation when performing HTTP-based adaptive streaming (HAS) across cellular systems such as long-term evolution (LTE). To guarantee video fluidity in the presence of fluctuations of the instantaneous video source rate and channel capacity, we consider an HAS-based proxy video manager and resource controller located at the cellular base station. Based on the channel quality observed by mobile clients, the manager allocates the wireless bandwidth to mobile clients for transmitting the video streams. We propose a cross-layer bandwidth allocation scheme that takes into account the channel quality as well as the video quality requirements and encoding rate fluctuations of the HAS video stream and minimizes the transmission delays experienced by users. This cross-layer bandwidth allocation achieves the optimum in terms of HAS streams delays and it outperforms different bandwidth allocations procedures and state-of-the-art LTE schedulers.

Advanced coordinated beamforming for the downlink of future LTE cellular networks

Modern cellular networks in traditional frequency bands are notoriously interference-limited especially in urban areas, where base stations are deployed in close proximity to one another. The latest releases of Long Term Evolution (LTE) incorporate features for coordinating downlink transmissions as an efficient means of managing interference. Recent field trial results and theoretical studies of the performance of joint transmission (JT) coordinated multi-point (CoMP) schemes revealed, however, that their gains are not as high as initially expected, despite the large coordination overhead. These schemes are known to be very sensitive to defects in synchronization or information exchange between coordinating bases stations as well as uncoordinated interference. In this article, we review recent advanced coordinated beamforming (CB) schemes as alternatives, requiring less overhead than JT CoMP while achieving good performance in realistic conditions. By stipulating that, in certain LTE scenarios of increasing interest, uncoordinated interference constitutes a major factor in the performance of CoMP techniques at large, we hereby assess the resilience of the state-of-the-art CB to uncoordinated interference. We also describe how these techniques can leverage the latest specifications of current cellular networks, and how they may perform when we consider standardized feedback and coordination. This allows us to identify some key roadblocks and research directions to address as LTE evolves towards the future of mobile communications.

Broadcasting Free-Viewpoint Television Over Long-Term Evolution Networks

Recent advances in mobile device technology, cellular networks, and multimedia coding have paved the way for a wide range of innovative multimedia services that can be delivered to mobile users. An interesting application is free-viewpoint television (FTV), which allows the viewer to interactively select the scene viewing angle. Conveying this service over cellular networks is very challenging due to the large bandwidth requirements and limitations in computational power, memory, and battery resources on mobile terminals. Moreover, providing FTV over mobile systems necessitates new means for quality evaluation, which consider cellular network parameters. To address these challenges, we propose a scalable FTV broadcast architecture for long-term evolution cellular networks. To alleviate complex processing on mobile receivers, depth maps are estimated in the cloud and transmitted along the multiview video. Moreover, a novel depth image-based rendering technique is developed to improve quality while minimizing processing load on the mobile terminal, giving typical peak signal-to-noise ratio gains of 2 dB. Experimental results reveal that, for a satisfactory rendering quality, bit-rate savings of more than 70% are achieved compared with simulcast transmission. Furthermore, subjective tests indicate that this solution improves the perceived quality considerably. Finally, we study the impact of handovers induced in mobile systems on the quality of experience.

Enabling Device to Device Broadcast for LTE Cellular Networks

In recent years, the public safety community has been aligning behind Long Term Evolution (LTE) technology as the basis for next generation public safety networks. Correspondingly, the 3rd Generation Partnership Project (3GPP) standards body has started multiple technical work initiatives on LTE enhancements to better support public safety use cases and requirements. Of particular importance to the public safety community is the addition of direct device-to-device (D2D) broadcast capability that can enable off-network push-to-talk (PTT) group communications in a manner equivalent to existing public safety communication systems. In this paper, we briefly explore the design objectives for, and challenges associated with, providing a D2D broadcast service. We then present and analyze a new distributed media access control (MAC) scheme for interference-aware coordination of both unicast and broadcast transmission. System-level simulation results are provided to validate the performance and the effectiveness of our approach, using a CSMA-based approach as a basis for comparison.

Theoretical expression of link performance in OFDM cellular networks with MIMO compared to simulation and measurements

The objective of this paper is to establish a theoretical expression of the link performance in the downlink of a multiple input multiple output (MIMO) cellular network and compare it to the real Long-Term Evolution (LTE ) performance. In order to account for the interference, we prove that the worst additive noise process in the MIMO context is the white Gaussian one. Based on this theoretical result, we build an analytic expression of the link performance in LTE cellular networks with MIMO. We study also the minimum mean square error (MMSE) scheme currently implemented in the field, as well as its improvement MMSE-SIC (successive interference cancellation) known to achieve the MIMO capacity. Comparison to simulation results as well as to measurements in the field shows that the theoretical expression predicts well practical link performance of LTE cellular networks. This theoretical expression of link performance is the basis of a global analytic approach to the evaluation of the quality of service perceived by the users in the long run of their arrivals and departures.

Performance Analysis of FLS, EXP, LOG and M-LWDF Packet Scheduling Algorithms in Downlink 3GPP LTE System

Long-Term Evolution (LTE), an emerging and promising fourth generation mobile technology, is expected to offer ubiquitous broadband access to the mobile subscribers. In this paper, the performance of Frame Level Scheduler (FLS), Exponential (EXP) rule, Logarithmic (LOG) rule and Maximum-Largest Weighted Delay First (M-LWDF) packet scheduling algorithms has been studied in the downlink 3GPP LTE cellular network. To this aim, a single cell with interference scenario has been considered. The performance evaluation is made by varying the number of UEs ranging from 10 to 50 (Case 1) and user speed in the range of [3, 120] km/h (Case 2). Results show that while the number of UEs and user speed increases, the performance of the considered scheduling schemes degrades and in both case FLS outperforms other three schemes in terms of several performance indexes such as average throughput, packet loss ratio (PLR), packet delay and fairness index.

Cooperation Management Among Base Stations Based on Cells Switch-Off for a Green LTE Cellular Network

The sudden increase in subscribers and demand for high-speed data has prompted cellular operators to increase the number of base stations to fulfill the needs of mobile subscribers. This increase has subsequently increased the overall energy consumption, operational costs and carbon footprint of cellular networks. Accordingly, improving the energy efficiency of wireless networks has become a compelling challenge for researchers, vendors, and mobile operators, not only to reduce the operational costs, but to also reduce the environmental effects. The focus is on creating green cellular networks at base stations because base stations consume most of the energy. In this paper, we investigate how much energy is saved based on a Long Term Evolution (LTE) network by reducing the number and size of active macro-cells according to traffic load conditions. The proposed methodology is simulated on a set of real-sized LTE networks. The simulation results show that there are savings of up to 48 % in terms of both energy savings and operational expenditure with a 90 % cell coverage condition.

On the impact of D2D traffic offloading on energy efficiency in green LTE‐A HetNets

AbstractIn this paper, the interplay between cooperative device‐to‐device (D2D) communications and green cellular communications in the long term evolution (LTE) and LTE‐advanced (LTE‐A) cellular systems is investigated. An efficient approach for grouping mobile terminals (MTs) into cooperative clusters is described. In each cluster, MTs cooperate via D2D communications to share content of common interest. In addition, an energy‐efficient approach for putting base stations in sleep mode in an LTE‐A heterogeneous network is presented. Finally, both methods are combined in order to ensure green communications for both the users' MTs and the operator's base stations. The presented techniques are investigated in the framework of orthogonal frequency division multiple access‐based state‐of‐the‐art LTE cellular networks, while taking resource allocation and intercell interference into account. Results show that the proposed approach leads to energy savings for both the operator and the MTs, while leading to enhanced quality of service for mobile users. Copyright © 2014 John Wiley & Sons, Ltd.

LTE Cellular Network Planning for Urban Area

Due to the advancement of telecommunication platform, users are now demanding new applications such as Online Gaming, mobile TV, Web 2.0, and to meet this requirement operators needed to design more flexible network. To fulfill the requirements, 3rd Generation Partnership Project (3GPP) works on the Long Term Evolution (LTE) and propose a system which has larger bandwidths (up to 20 MHz), low latency and packet optimized radio access technology having peak data rates of 100 Mbps in downlink and 50 Mbps in the uplink (Magdalena, 2007; Motorola, 2007; Skold, 2009). Offering a greater coverage by providing higher data rates over wider areas and flexibility of use at existing and new frequency bands plan is a major challenge. In this paper, we are analyzing practical coverage scenario in an urban area (i.e. Kolkata) in terms of received signal levels, total noise, interference, throughput, and quality factor for downlink signal level.