Long Term Evolution Downlink Research Articles

Optimized Downlink Scheduling over LTE Network Based on Artificial Neural Network

Long-Term Evolution (LTE) technology is utilized efficiently for wireless broadband communication for mobile devices. It provides flexible bandwidth and frequency with high speed and peak data rates. Optimizing resource allocation is vital for improving the performance of the Long-Term Evolution (LTE) system and meeting the user’s quality of service (QoS) needs. The resource distribution in video streaming affects the LTE network performance, reducing network fairness and causing increased delay and lower data throughput. This study proposes a novel approach utilizing an artificial neural network (ANN) based on normalized radial basis function NN (RBFNN) and generalized regression NN (GRNN) techniques. The 3rd Generation Partnership Project (3GPP) is proposed to derive accurate and reliable data output using the LTE downlink scheduling algorithms. The performance of the proposed methods is compared based on their packet loss rate, throughput, delay, spectrum efficiency, and fairness factors. The results of the proposed algorithm significantly improve the efficiency of real-time streaming compared to the LTE-DL algorithms. These improvements are also shown in the form of lower computational complexity.

Multipath tracking with LTE signals for accurate TOA estimation in the application of indoor positioning

ABSTRACT Indoor positioning with high accuracy plays an important role in different application scenarios. As a widely used mobile communication signal, the Long-Term Evolution (LTE) network can be well received in indoor and outdoor environments. This article studies a method of using different reference signals in the LTE downlink for carrier phase time of arrival (TOA) estimation. Specifically, a solution is proposed and a multipath tracking Software Defined Receiver (SDR) is developed for indoor positioning. With our SDR indoor positioning system, the pilot signals of the LTE signals are firstly obtained by the coarse synchronization and demodulation. Then, with the assistance of the pilot signals, the time delay acquisition, the multipath estimating delay lock loop (MEDLL) algorithm, and the multipath anomaly detection are sequentially carried out to obtain navigation observations of received signals. Furthermore, to compare the performance of different pilot signals, the Secondary Synchronous Signals (SSS) and Cell Reference Signals (CRS) are used as pilot signals for carrier phase-based TOA estimation, respectively. Finally, to quantify the accuracy of our multipath tracking SDR, indoor field tests are carried out in a conference environment, where an LTE base station is installed for commercial use. Our test results based on CRS show that, in the static test scenarios, the TOA accuracy measured by the 1-σ error interval is about 0.5 m, while in the mobile environment, the probability of range accuracy within 1.0 m is 95%.

QoS-Aware Scheduling Algorithm Enabling Video Services in LTE Networks

The Long-Term Evolution (LTE) system was a result of the 3rd-Generation Partnership Project (3GPP) to assure Quality-of-Service (QoS) performance pertaining to non-real-time and real-time services. An effective design with regards to resource allocation scheduling involves core challenges to realising a satisfactory service in an LTE system, particularly with the growing demand for network applications. The continuous rise in terms of the number of network users has resulted in impacts on the performance of networks, which also creates resource allocation issues when performing downlink scheduling in an LTE network. This research paper puts forward a review of optimisation pertaining packet scheduling performance through the LTE downlink system by introducing a new downlink-scheduling algorithm for serving video application through LTE culler networks, and also accounts for QoS needs and channel conditions. A comparison of the recommended algorithms’ performances was made with regards to delay, throughput, PLR, and fairness by utilising the LTE-SIM simulator for video flow. On the basis of the outcomes obtained, the algorithms recommended in this research work considerably enhance the efficacy of video streaming compared against familiar LTE algorithms.

Effect of Nonlinear Detection Response Characteristics of Electric Field Probe on LTE Signal Measurement and Statistical Evaluation of Its Detection Response

To improve the calibration accuracy of an electric field (E-field) probe loaded with a diode detector for digital wireless communication signals with complex waveforms, the effect of the nonlinear characteristics of the E-field probe on the detection response of a long-term evolution (LTE) signal is investigated. In this article, we focused on single-carrier frequency division multiple access (SC-FDMA) and orthogonal frequency-division multiplexing access (OFDMA) signals used for LTE uplink and downlink, respectively. First, we investigated the effect of the nonlinear characteristics of the E-field probe on the detection response of continuous SC-FDMA and OFDMA signals simulating frequency division duplexing LTE. Then, intermittent SC-FDMA and OFDMA signals simulating time-division LTE were also investigated. Furthermore, we proposed a method of estimating the detection response of SC-FDMA and OFDMA signals using the probability density function of the envelope amplitude. When the envelope variation of the LTE signal is fully covered within the response time of the E-field probe, the estimated detection response agrees well with the measured result. In addition, the detection response of an intermittent LTE signal with a typical repetition period can be calculated with the proposed approximation formula by separately considering the probability density functions of the envelope amplitude for the burst and nonburst periods.

AN OVERVIEW OF MIMO OFDM SYSTEM FOR WIRELESS COMMUNICATION

In modern days, we are using wireless modern communication systems, which require high data rates and more band width efficiencies. The most well-known 4G technology of wireless standard is Long Term Evolution (LTE) which espoused OFDMA (Orthogonal Frequency Division Multiple Access) and MIMO (Multi Input Multi Output) techniques. These techniques are employed on downlink of LTE. A MIMO system utilizes numerous antennas at both the transmitter and receiver to work on the performance of the correspondence system using diversity and multiplexing methods. MIMO framework gives higher phantom effectiveness, further develops unwavering quality, decreases fading and further develops protection from interference. In this paper we give an overview of the MIMO, OFDM and MIMO-OFDM system for wireless communication.

Optimized two‐level scheduler for video traffic in LTE downlink framework

SummaryThe most challenging issue in long‐term evolution (LTE) mobile networks is the design of an optimal scheduler. The main target of the LTE scheduling strategy is to guarantee a certain level of quality of service (QoS) in order to satisfy users' needs. In this work, a novel queue‐optimized two‐level scheduling strategy is introduced. The queue‐optimized scheduler has the ability to support both real‐time (RT) and non‐RT (NRT) services in the LTE downlink framework. The first level of the proposed scheduler depends on an optimized queue length threshold that is dynamically adapted to adjust the assigned resources for the video traffic to maintain the throughput around its average value. The proposed scheduling strategy is utilized to efficiently enhance the radio resource allocation process for video traffic by minimizing the allocation of any excess unwanted resources, which consequently facilitates the support of more video connections and enhances the overall network spectral efficiency. The distribution of the resources among users for RT and NRT applications is actually performed at the second level of the scheduling process. The physical resource blocks (PRBs) are assigned according to the enhanced earliest due date first (EEDDF) mechanism. The proposed scheduling strategy prioritizes users according to their service requirements, to improve the QoS provision. The proposed scheduler maximizes the video applications throughput, and generally, minimizes the packet delay and the packet loss rate (PLR) for RT applications.

Optimized Broadband Load Network for Doherty Power Amplifier Based on Bandwidth Balancing

This letter presents an optimized broadband load network for the Doherty power amplifier (DPA) based on bandwidth balancing between low- and peak-power levels. The optimized broadband load network is composed of a quasi-lumped $\lambda $ /4 impedance transformer (ITF), a modified multiple resonance circuit (MMRC), and a broadband postmatching network (PMN). The quasi-lumped ITF at the carrier amplifier has an optimized characteristic impedance for bandwidth balancing between low- and peak-power levels. The MMRC provides the quasi-lumped ITF with an appropriate susceptance for optimized bandwidth. It also matches the impedance for the peaking amplifier. To validate this design concept, the broadband DPA was implemented using 30-W gallium–nitride high electron mobility transistor (GaN-HEMT) for both carrier and peaking amplifiers. For the down-link long-term evolution (LTE) signal with a channel bandwidth of 10 MHz and a peak-to-average power ratio (PAPR) of 6.5 dB at the frequency range of 1.15–2.45 GHz, DE ranging from 38.4% to 52.2%, and the adjacent channel leakage power ratio (ACLR) ranging from −23.9 to −35.0 dBc at an average output power of from 39.7 to 41.7 dBm were achieved.

Implementation of Downlink Physical Channel Processing Architecture for NB-IoT Using LTE/5G Networks

The monumental success over the years, in wireless communication and mobile communication have overcome the challenges such as fading, multipath, interferences and spectrum limitations due to the advancement in the communication system with higher peak data rate with reduced latency thus most of research work are being focused from long term evolution (LTE) along with reduced delay, area and power consumption. Narrowband Internet of Things (NB-IoT) is an emerging domain with a vast range of applications. The conventional NB-IoT network uses orthogonal frequency division multiplexing (OFDM) for data transmission over the communication channel. LTE downlink physical layer has three control channels which are PCFICH, PDCCH, and PHICH uses in channel processing. The processing step involves scrambling, modulation, layer mapping, precoding and resource element mapping at the transmitter. The receiver end comprising of demapping from the source elements and detection of data occurs in physical downlink channels of LTE. 5G will make sure that, one can download an app of any MB in size at greater speed when compared with existing system. The entire scheme has been simulated using Model sim and realized in Plan Ahead Tool in Virtex 5 tool.

Downlink scheduling algorithm over LTE networks using genetic algorithm

ABSTRACT The Third Generation Partnership Project (3GPP) has introduced the Long-Term Evolution (LTE) to handles the increasing demand for the wireless network setup. In the LTE setup, radio resource management scheduling algorithms are employed to distribute radio resources to users that have diverse Quality of Service (QoS) requirements. QoS Class identifier radio resource allocation algorithm for LTE downlink uses QoS requirements and channel conditions to decide the transmission order of users. However, this resulted in poor network performance by deteriorating the network data throughput and an increase in average delay due to the lack of proffer use of genetic algorithms (GA). In this paper, a new scheduling algorithm is proposed to improve the poor performance degradation of the network by introducing the idea of GA before radio resources are allowed to users. Simulation is used to test the performance of the proposed algorithm and the results obtained show that it considerably beats the other algorithm according to the measured metrics. An improvement of 65.76% was observed in terms of spectral efficiency, an increase of throughput and the average delay was minimised.

LTE‐based multistatic passive radar system for UAV detection

Using the frequency-division duplex long-term evolution (LTE)-based multistatic passive radar system for unmanned aerial vehicle (UAV) detection is considered. The typical outdoor terrestrial LTE eNodeBs and the broadband direct air-to-ground communications network eNodeBs are used to cover the UAVs at the low altitude and at the medium-high altitude, respectively. The bistatic range measurements are obtained from multiple eNodeBs, and the hyperbolic positioning technique is used for target localisation. Since the existing LTE downlink signals are more suitable for the transmission of the communication data rather than target detection, a new LTE downlink signal feature termed as target localisation reference signals (TLRS) is designed exclusively for the passive radar application using the Costas frequency coding and the P4 phase coding. Compared with the existing LTE downlink signal features, the TLRS have better waveform properties and could potentially provide much higher target detection accuracy. Meanwhile, the TLRS occupy only 0.266% LTE downlink time–frequency resources within a time frame of 1 s when the bandwidth is 10 MHz and have no negative impact on the normal LTE downlink data transmission.

Enhanced fair earliest due date first scheduling strategy for multimedia applications in LTE downlink framework

SummaryGuaranteeing a certain delay threshold for delay‐sensitive applications in long term evolution (LTE) cellular communication system is a very challenging mission. By implementing an optimal scheduling strategy, this mission will be achieved. In this article, a novel scheduler is introduced in order to meet a predefined level of service quality by guaranteeing a specific delay threshold for delay‐sensitive applications in LTE cellular systems. The proposed scheduler assigns the available resource blocks (RBs) to active user equipments (UEs) tacking into consideration several attributes. The expiration date of each packet, the channel quality, the average data rate previously achieved by each UE, and the number of dropped packets for each UE compared with the average number of packets totally dropped are all considered in the proposed scheduler working mechanism. Consequently, the proposed scheduling strategy reduces the number of packets dropped for multimedia applications, and at the same time maximizes the overall throughput of the network. Simulation results are provided to study and evaluate the performance of the proposed scheduling strategy. A comparative study is presented between the proposed strategy and the most recent scheduling techniques. The obtained results prove that the proposed scheduling strategy has considerably acceptable and appreciated results compared with the results of the state‐of‐the‐art scheduling techniques.

Channel aware optimized proportional fair scheduler for LTE downlink

Long Term Evolution (LTE) mobile networks, time-frequency radio resources are allotted with respect to Quality of Service (QoS) requirements using scheduling algorithms. Buffer Occupancy (BO), Average Cellular Throughput (ACT), Average User Throughput (AUT), Blocking Probability (BP) and Fairness Index (FI) are the parameters to be considered when designing a scheduler. A new scheduling policy is proposed in this paper, called “Channel Aware Optimized Proportional Fair (CAOPF)” to optimize the channel behavior based on Channel Quality Indicator (CQI). The performance of the introduced scheduler is investigated and compared with the other schedulers such as Round Robin (RR) and Proportional Fair (PF). Simulation results indicate that the new scheduler gives the best level of QoS performance in terms of the above said parameters when compared with the other schedulers taken into account. It provides no pending data of users in good channel condition, higher ACT, higher improvement in user throughput in good and average channel conditions. In addition, very low blocking of user data in good channel condition and optimized FI and resource block (RB) allocated to the users in all channel conditions are seen.

A Hybrid Downlink Scheduling Approach for Multi-Traffic Classes in LTE Wireless Systems

The developments in wireless technology and applications in recent years have increased the interest in downlink scheduling and resource allocations among researchers. Moreover, fair scheduling and balanced Quality of Service (QoS) delivery for various forms of traffic are needed for Long-Term Evolution (LTE) wireless systems. This paper proposes hybrid QoS-aware downlink scheduling approaches that aim to address different traffic classes and balance the QoS delivery with improvements to the overall system performance under channel and bandwidth constraints. Moreover, this research introduces a taxonomy that classifies the scheduling algorithms into four main classes: delay aware, queue aware, target bit-rate aware and hybrid aware. The latter class is the scheduling class that is proposed in this paper; it considers channel, queue and delay parameters in its scheduling metric. Using simulations, we compare and analyze different downlink scheduling rules for their network-centric performance metrics, e.g., average packet loss ratio, average throughput, average packet delay, system fairness, and system spectral efficiency. The simulation results show that the queue-aware and delay-aware scheduling rules deliver the best QoS performance for video traffic classes, whereas our proposed hybrid scheduling rules deliver balanced QoS for various types of traffic classes. Employing QoS balancing scheduling rules in an LTE downlink is suggested to provide high QoS delivery for different traffic classes.

Dragonfly-Based Joint Delay/Energy LTE Downlink Scheduling Algorithm

Managing radio resources in Long Term Evolution (LTE) networks is considered as one of the essential design factors for enhancing the overall system performance. Common approaches are introduced to either achieve fairness between network users or attain maximum spectral efficiency. However, these approaches do not consider optimizing energy consumption. Therefore, in this paper, a novel resource allocation algorithm based on the Dragonfly metaheuristic technique is proposed to allocate bandwidth to users. The new algorithm is called Dragonfly-based Joint Delay/Energy (DJDE) and considers the Quality of Services (QoS) requirements of the users while achieving a high level of energy efficiency. The proposed solution utilizes the Dragonfly algorithm to optimize the integration process of different scheduling policies. To evaluate the proposed algorithm, an extensive set of experiments are conducted to compare the proposed solution to the state-of-the-art techniques. Also, to assess the energy efficiency of the proposed method, another set of experiments are simulated to compare it with various algorithms that optimize energy consumption. The obtained results prove that the DJDE algorithm can satisfy the QoS requirements of the users while improving the overall system performance.

A Countermeasure against Smart Jamming Attacks on LTE Synchronization Signals

Long-Term Evolution (LTE) is one of the most frequently used wireless communication technology. As every wireless network, LTE is vulnerable to physical layer (PHY) jamming attacks due to the broadcast nature of channels. Since the jammer attacks are getting smarter and energy efficient, they can target a specific region or physical channel instead of entire band. Targeting the physical LTE downlink Synchronization Signals (SS) could be the most dangerous objective. In this paper, we investigate LTE PHY jamming attack against only primary and secondary synchronization signals. Jammer detection is performed by using Neyman-Pearson theorem. Then, a countermeasure method is proposed. Simulation results show that the proposed countermeasure can achieve lower pollution and better correct cell id performances during smart jamming attack against SS.

A Novel Scheme for CP-Length Detection and Initial Synchronization for the LTE Downlink

In long-term evolution (LTE) systems, there is an option to extend the size of the cyclic-prefix (CP) when the propagation environment is characterized by severe time dispersion. Such a peculiar feature makes the system more resilient against multipath distortions, but inevitably complicates the downlink synchronization task, which cannot be accomplished through conventional techniques devised for a specified CP size. In this paper, we study the problem of CP length detection in the LTE downlink in the presence of a timing uncertainty and frequency offset. In contrast to previous investigations based on heuristic arguments, our approach relies on the maximum likelihood (ML) estimation criterion. Furthermore, it accounts for the irregular LTE symbol (characterized by a different CP size), which is present in the normal CP operation mode. The resulting scheme operates in the time-domain and computes a different metric for each possible position of the irregular symbol within the observation window. Due to its flexibility, the proposed ML approach can be applied to any future multicarrier standard for the design of a CP length detection algorithm, either in the presence or in the absence of irregular symbols.

LTE Downlink 2x2MIMO in Channel-B Indoor Model with SFBC: Design and BER Analysis

The wireless technology, Long Term Evolution (LTE) allocates radio resources efficiently for its high data rate and Quality of Service (QoS) guarantee. The function of LTEDownlink (DL) is mainly depend on the channel quality between the Evolved NodeB (eNB) and User Equipment (UE) and how effectively the modulation schemes are adopted. Therefore it is very essential to design and verify the Bit Error Rate (BER) performance of a LTE DL to utilize the system resources efficiently. In this paper we present a design of MATLAB based 2x2 Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing (MIMO-OFDM)DL with Space Frequency Block Coding (SFBC) by adopting International Telecommunication Union-Recommended (ITU-R) path loss model of Channel-B Indoor model, its BER performance with Adaptive Modulation Coding Schemes (AMCS) of LTEbased on standard LTE parameters.The BER performance of the 1x1 Single Input Single Output (SISO), 2x1 Multiple Input Single Output (MISO) and 2x2 MIMO are investigated in comparison with Additive White Gaussian Noise (AWGN) channel performance in this research. The simulation results shows that the BER performance of the channel model is good in minimum Signal to Noise Ratio (SNR) values when applying 4-Quadrature Amplitude Modulation/Quadrature Phase Shift Keying (4-QAM /QPSK) modulation, good in medium SNR with 16-QAM modulation and good in high SNR with 64-QAM modulation for different LTE bandwidths. It is concluded that the designed MIMO-OFDM DLis best suitable for different LTE operating bandwidths to support different services and gives a way to the future research direction to test with 4x4 and 8x8 MIMO systems.

Performance of LTE downlink communication system in presence of electronic warfare spot jamming

Wireless communication is one of the principally active zones of tools development and has become necessary part of everyday life. Simulation of wireless communication systems accurately is very important for predicting its performance under different scenarios. Long-Term Evolution (LTE) is named by next generation wireless communications. It is a standard for high-speed wireless communication for mobile phones and data terminals. In this paper, the performance of standard single-input-single-output (SISO) LTE Frequency Domain Duplex (FDD) downlink (DL) signal in additive white Gaussian noise (AWGN) channel is evaluated in two scenarios without jamming and in presence of electronic warfare spot jamming. Firstly, the performance of the standard LTE communication system in absence of jamming is investigated by calculating the probability of Bit Error Rate (BER) and Frame Error Rate (FER) versus Signal Noise Ratio (SNR). Secondly, the performance in presence of electronic warfare spot jamming scheme is investigated by constant Jamming to Signal Ratio (JSR) and different values of the normalized jamming bandwidth. In order to illustrate the impact of jamming on the standard LTE DL wireless communication system, the measurement is evaluated by using the aid of SystemVue software program.

A Channel and Queue-Aware Scheduling for the LTE Downlink Based on Service Curve and Buffer Overflow Probability

In this letter, we propose a joint channel and queue-aware resource block allocation algorithm for the long-term evolution (LTE) downlink based on buffer overflow probability estimation. To this end, we first derive an equation for the buffer overflow probability bound. Furthermore, we propose a novel service curve in order to estimate maximum delay for LTE system users considering the Effective exponential signal-to-noise ratio mapping to the SNR values of the LTE sub-bands. Simulation results reveal that in general, compared to other approaches, the proposed scheduling algorithm provides lower delay and buffer overflow rate while maximizing throughput.

Vehicle detection and classification using LTE‐CommSense

We demonstrated a vehicle detection and classification method based on Long Term Evolution (LTE) communication infrastructure based environment sensing instrument, termed as LTE-CommSense by the authors. This technology is a novel passive sensing system which focuses on the reference signals embedded in the sub-frames of LTE resource grid. It compares the received signal with the expected reference signal, extracts the evaluated channel state information (CSI) and analyzes it to estimate the change in the environment. For vehicle detection and subsequent classification, our setup is similar to a passive radar in forward scattering radar (FSR) mode. Instead of performing the radio frequency (RF) signals directly, we take advantage of the processing that happens in a LTE receiver user equipment (UE). We tap into the channel estimation and equalization block and extract the CSI value. CSI value reflects the property of the communication channel between communication base station (eNodeB) and UE. We use CSI values for with and vehicle and without vehicle case in outdoor open road environment. Being a receiver only system, there is no need for any transmission and related regulations. Therefore, this system is low cost, power efficient and difficult to detect. Also, most of its processing will be done by the existing LTE communication receiver (UE). In this paper, we establish our claim by analyzing field-collected data. Live LTE downlink (DL) signal is captured using modeled LTE UE using software defined radio (SDR). The detection analysis and classification performance shows promising results and ascertains that, LTE-CommSense is capable of detection and classification of different types of vehicles in outdoor road environment.