LTE Downlink System Research Articles

A novel BCS code in a downlink LTE system over an LTE-MIMO channel

In general, a concatenated RS/BCH code consists of an outer RS code and an inner BCH code with separation by an interleaver. We create a novel BCS code using a new methodology by combining an outer BCH code with an inner RS code appended by an interleaver to randomize burst errors and help the RS code in correcting the errors. Generally, BCH codes handle binary data, whereas RS codes handle non-binary data. Hence, RS (7, 1) inner code is proposed to achieve compatibility with BCH (15, 5) outer codes and ultimately create a novel BCS code to handle binary data. The proposed BCS code is compared with familiar concatenated RS/BCH codes and single codes (RS and BCH) for BPSK and QPSK modulation schemes. Results show the downlink LTE system performance using the proposed BCS code is significantly better than the uncoded LTE system and single codes (RS and BCH). Moreover, the proposed BCS code also outperforms familiar concatenated RS/BCH codes for both schemes. In contrast, the system performance is improved further when the number of antennas in the MIMO channel is increased from $$2 \times 2$$ to $$4 \times 4$$ . Therefore, the proposed BCS code can be considered a stronger code with high reliability in wireless communication systems.

Performance Analysis of Scheduling with Combined Unicast and Multicast Services in Downlink LTE System

Multicasting is an efficient solution for transmitting data to a group of users, which leads to the minimal network requirements. However, in real scenario both type of users (unicast and multicast) will exist in the network. Therefore, an appropriate resource allocation method is necessary to satisfy the Quality of Service (QoS) requirements of each user using these services. This paper proposes a resource allocation method to improve the performance of real time service users in spite of their transmission mode is unicast or multicast. If the user is in unicast transmission, the transmission rate is chosen based on the feedback from the user and if the user is in multicast transmission, then the resource allocation is done by subgrouping and adopting different transmission rates. Genetic algorithm is performed on subgroup formation such that the overall rate of the group should be maximized. From the simulation results, it is inferred that there is 46% increase in the average throughput and 10% reduction in delay for the real time users when compared to conventional resource allocation method.

Energy Efficiency Improvement in Mobile Communication System by Reducing the PAPR

Peak to average power ratio (PAPR) is a great issue in multicarrier systems especially in the LTE/LTEA communication system, so there is still a wide range that handles the PAPR problem. Orthogonal frequency division multiple access (OFDMA) technique is used in the downlink LTE system as it has many advantages over multipath propagation system. On the other side it suffers from a high PAPR that will affect the energy efficiency. In this paper, a new hybrid scheme is proposed in the downlink mobile communication system to overcome this issue. Besides reducing the PAPR, the proposed scheme did not have a significant increase in the system complexity but also it had nearly the same bit error rate (BER) system performance as OFDM system. Also we introduce a combination of different pre-coding techniques in OFDM system that improve the BER such as (Discrete Hartley Transform, Discrete Cosine Transform and Discrete Sine Transform) with the companding techniques that have a good ability in reducing the PAPR with a little increase in system complexity such as (Absolute exponential, Tangent rooting and Logarithmic) companding techniques. We tested the system performance for different techniques combination, and according to the analysis and the simulations done, it was found that the hybrid technique that is composed from the Discrete Hartley transform pre-coding technique and the Logarithmic companding technique in the downlink system outperforms all other hybrid techniques combinations.

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.

Delay-based and QoS-aware packet scheduling for RT and NRT multimedia services in LTE downlink systems

Guaranteeing Quality of Service (QoS) for heterogeneous traffic is a major challenge in the Fourth Generation (4G) mobile networks. Therein, the absence of sophisticated resources allocation process at the base station jeopardizes QoS in terms of latency data transfer. It has been observed from the literature that low delay bounds might be ensured, however, at the expense of other QoS aspects; for example, throughput and data loss. Therefore, in this article, we propose an effective Delay–based and QoS–Aware Scheduling (DQAS) scheme with a low complexity overhead as an efficient solution for the resource allocation issue in LTE Medium Access Control (MAC) layer. The ultimate aim of DQAS is to minimize delay for Real-Time (RT) traffic while still offering a good level of QoS. Complying with QoS of different traffic types, we effectively analyze the queue buffer of each user flow by developing an algorithm called Efficient Delay Control (EDC) that weights each flow priority in terms of delay. Then, this weight is utilized as a principle for the scheduling decision on the attending flows. Furthermore, the Least Delay Increase (LDI) algorithm is developed to tune the scheduler behavior to maintain a balance between delay and system throughput. Simulation results considering different user mobility levels reveal that DQAS significantly guarantees a low end-to-end delay trend that is independent of increased RT load, and moreover, a reasonable throughput and data drop levels compared to other existing schedulers.

Investigation on Interference Mitigation Schemes for Next Generation Cellular Communications

The fanciful quick development and exponential increment of advanced mobile phones the remote info activity request is additional within the returning years. That forces reexamining current remote cell arranges thanks to the shortage of the accessible vary. 2 noteworthy difficulties for advancing future Evolution (LTE) systems area unit to accomplish improved cell scope and framework limit contrasted and broadband Code Division Multiple Access (WCDMA) framework. Powerful use of radio assets and thick vary use is at the middle to realize these objectives. Be that because it might, thick repeat use might increment between cell electric resistance, that so extraordinarily restricts the limit of shoppers within the framework. Between cell obstruction will limit general framework execution as so much as output and preternatural productivity, significantly for the shoppers set at the cell edge region. later on, cautious administration of between cell obstructions finishes up vital to boost LTE framework execution. during this paper, obstruction alleviation plans for LTE downlink systems area unit investigated. The eNB and also the Mobile-Femto as each provide similar assets and transfer speed. This has created AN electric resistance issue from the downlink signs of every alternative to their UEs. this examination has adjusted a adept repeat use conspire that worked powerfully finished separation and accomplished increased outcomes within the flag quality and output of Macro and Mobile-Femto UE once contrasted with past electric resistance administration plans e.g. Partial Frequency use factor1 (NoFFR-3) and uncomplete Frequency use factor3 (FFR-3). Keywords: The fanciful quick development and exponential increment of advanced mobile phones the remote info activity request is additional within the returning years. That forces reexamining current remote cell arranges thanks to the shortage of the accessible vary. 2 noteworthy difficulties for advancing future Evolution (LTE) systems area unit to accomplish improved cell scope and framework limit contrasted and broadband Code Division Multiple Access (WCDMA) framework. Powerful use of radio assets and thick vary use is at the middle to realize these objectives. Be that because it might, thick repeat use might increment between cell electric resistance, that so extraordinarily restricts the limit of shoppers within the framework. Between cell obstruction will limit general framework execution as so much as output and preternatural productivity, significantly for the shoppers set at the cell edge region. later on, cautious administration of between cell obstructions finishes up vital to boost LTE framework execution. during this paper, obstruction alleviation plans for LTE downlink systems area unit investigated. The eNB and also the Mobile-Femto as each provide similar assets and transfer speed. This has created AN electric resistance issue from the downlink signs of every alternative to their UEs. this examination has adjusted a adept repeat use conspire that worked powerfully finished separation and accomplished increased outcomes within the flag quality and output of Macro and Mobile-Femto UE once contrasted with past electric resistance administration plans e.g. Partial Frequency use factor1 (NoFFR-3) and uncomplete Frequency use factor3 (FFR-3).

Analysis of enhanced complex SVR interpolation and SCG-based neural networks for LTE downlink system

In this article, we operate and evaluate the performance of radial basis function (RBF)-based support vector machine regression (SVR) and scaled conjugate gradient back propagation (SCG)-based artificial neural network (ANN), to estimate the channel deviations in frequency domain using the standardised pilot symbols structure for LTE downlink system. We apply complex SVR and ANN to estimate the real vehicular a channel environment well-defined by the International Telecommunications Union (ITU). The suggested procedures use data obtained from the received pilot symbols to estimate the overall frequency response of the frequency selective multipath fading channel in two stages. In the first stage, each technique learns to adjust to the channel fluctuations, then, in the second stage, it predicts all the channel frequency responses. Lastly, in order to assess the abilities of the considered channel estimators, we deliver performance of complex SVR and ANN, which are compared to traditional least squares (LS) and decision feedback (DF) methods. Computer simulation results demonstrate that the complex RBF-based SVR approach has a better precision than other estimation methods.

Analysis of enhanced complex SVR interpolation and SCG-based neural networks for LTE downlink system

In this article, we operate and evaluate the performance of radial basis function (RBF)-based support vector machine regression (SVR) and scaled conjugate gradient back propagation (SCG)-based artificial neural network (ANN), to estimate the channel deviations in frequency domain using the standardised pilot symbols structure for LTE downlink system. We apply complex SVR and ANN to estimate the real vehicular a channel environment well-defined by the International Telecommunications Union (ITU). The suggested procedures use data obtained from the received pilot symbols to estimate the overall frequency response of the frequency selective multipath fading channel in two stages. In the first stage, each technique learns to adjust to the channel fluctuations, then, in the second stage, it predicts all the channel frequency responses. Lastly, in order to assess the abilities of the considered channel estimators, we deliver performance of complex SVR and ANN, which are compared to traditional least squares (LS) and decision feedback (DF) methods. Computer simulation results demonstrate that the complex RBF-based SVR approach has a better precision than other estimation methods.

Performance Analysis of Channel Capacity and Throughput of LTE Downlink System

Performance Analysis of Channel Capacity and Throughput of LTE Downlink System

Support Vector Machine Regression and Artificial Neural Network for Channel Estimation of LTE Downlink in High-Mobility Environments

In this paper we apply and assess the performance of support vector machine regression (SVR) and artificial neural network (ANN) channel estimation algorithms to the reference signal structure standardized for LTE Downlink system. SVR and ANN where applied to estimate real channel environment such as vehicular A channel defined by the International Telecommunications Union (ITU) in the presence of nonlinear impulsive noise.The proposed algorithms use the information provided by the received reference symbols to estimate the total frequency response of the time variant multipath fading channel in two phases. In the first phase, each method learns to adapt to the channel variations, and in the second phase it predicts all the channel frequency responses. Finally, in order to evaluate the capabilities of the designed channel estimators, we provide performance of SVR and ANN, which is compared with traditional Least Squares (LS) and Decision Feedback (DF). The simulation results show that SVRhas a better accuracy than other estimation techniques.

Erratum to: Analysis of Full Volterra and Sparse Volterra Nonlinear Equalization for Downlink LTE System

Erratum to: Analysis of Full Volterra and Sparse Volterra Nonlinear Equalization for Downlink LTE System

Improvement of downlink LTE system performances using nonlinear equalization methods based on SVM and Wiener–Hammerstein

In this paper, we present versatile nonlinear equalizer based on support vector machine for a standard downlink LTE link. The nonlinear effects are introduced through a solid state power amplifier. The equalizer is compared with a linear RLS and nonlinear Wiener–Hammerstein (W–H) for 16QAM–MIMO–OFDM transmission, revealing improved performance at 1 Mb/s, by 3 and 2 dB in SNR, respectively, when targeting a EVM (dB) of −60 dB. SVM equalization also outperforms the Wiener–Hammerstein by 1 dB in SNR.

Analysis of Full Volterra and Sparse Volterra Nonlinear Equalization for Downlink LTE System

In this work, we propose Full Volterra and Sparse Volterra channels equalization algorithms for downlink LTE system. For estimation purpose, the LTE standard provides known data as pilot symbols an...

Improvement of LTE Downlink Channel Estimation Performance by Using an Adaptive Pilot Pattern

This paper proposes an adaptive pilot pattern to improve channel estimation performance for LTE downlink system with high mobility. The downlink pilot positions are predefined in the time and frequency domain with fixed pilot pattern in LTE standard. However, that pilot structure is not efficient in a fast time varying channel, and leads to a decrease of channel estimation performance. The authors propose and evaluate the performance of LTE downlink channel estimation using an adaptive pilot scheme to optimally use pilot tones over time varying channels. It is shown that only seven bits of additional wide-band feedback per frame and per user are required to optimally support adaptive pilot pattern. Simulation results show that the proposed method allows high performance in terms of throughput and channel estimation error. This analysis shows that LTE downlink throughput could be increased over 4%.

Modeling and Performance Evaluation of Novel Scheduling Algorithm for Downlink LTE Cellular Network

Long term evolution is standardized by the 3rd Generation Partnership Project to provide a high data rate up to 100 and 50 Mbps for downlink and uplink transmission respectively and can operate in different bandwidths ranging from 1.4 up to 20 MHz. Downlink LTE system is based on the OFDMA technique and uses several enhanced techniques in order to increase the spectral efficiency and aggregate the cell throughput. The incorporated scheduling mechanisms can significantly contribute to this goal. Scheduling mechanism is the process of allocated the resources (time and frequency) to users transmitting different flows in same time. In this paper, we propose a novel scheduling algorithm for downlink transmission in LTE system. The performances of the newly scheduler are simulated and compare to the performances of three basic scheduler such as Round Robin, Proportional Fair and Max Rate.

Improvement of LTE Downlink System Performances Using the Lagrange Polynomial Interpolation

To achieve a high speed data rate, higher spectral efficiency, improved services and low latency the 3rd generation partnership project designed LTE standard (Long Term Evolution).the LTE system employs specific technical as well the technical HARQ, MIMO transmission, OFDM Access or estimation technical. In this paper we focus our study on downlink LTE channel estimation and specially the interpolation which is the basis of the estimation of the channel coefficients. Thus, we propose an adaptive method for polynomial interpolation based on Lagrange polynomial. We perform the Downlink LTE system MIMO transmission then compare the obtained results with linear, Sinus Cardinal and polynomial Newton Interpolations. The simulation results show that the Lagrange method outperforms system performance in term of Block Error Rate (BLER) , throughput and EVN(%)vs. Signal to Noise Ratio (SNR).

Scheduling Algorithm for High-Mobility User in LTE Downlink System

Frequency diversity scheduling allocates whole system bandwidth to a user in order to conquer deep fading of the sub-band when user with high-mobility. Though OFDMA technology mitigates interference of users in same cell, it increases interference of cell edge user as base stations use same frequency. Thus, we developed a frequency diversity fairness scheduling algorithm to balance fairness of cell center user and cell edge user. It is demonstrated by computer simulation that the proposed algorithm increases user fairness of the system with same system throughput and fairness between cell edge user and cell center user. It also points out that the algorithm proposed has the same complexity with the frequency diversity scheduling algorithm.

User Classification and Scheduling in LTE Downlink Systems with Heterogeneous User Mobilities

In LTE systems with heterogeneous user mobilities, low-mobility users favor frequency selective scheduling while high-mobility users benefit from frequency diversity scheduling. To benefit both low- and high-mobility users simultaneously, scheduling exploiting frequency selectivity and diversity is desired. To enable the scheduling, low-complexity user mobility classification to distinguish these two types of users is required. In this paper, we first propose a user mobility classification algorithm, which is robust to different channel delay profiles (CDPs), for single-transmit-antenna systems. Then, we extend it to multiple-input multiple-output (MIMO) systems. A low-complexity scheduling algorithm, exploiting both frequency-selectivity and diversity for low- and high-mobility users simultaneously, is also developed. As demonstrated by the simulation results, the proposed user classification algorithm is robust to different CDPs and the proposed scheduling algorithm is effective.

Complexity Effective Integer Frequency Offset and Sector Cell Detection Scheme for LTE Downlink System

This paper proposes a low-complexity integer frequency offset (IFO) and sector cell index (CID) detection scheme in a long term evolution downlink system. In the proposed detection scheme, the IFO and CID are estimated in a decoupled manner. In doing so, the detection scheme is designed to first estimate IFO without a priori knowledge of cell-specific reference signals and then detect the CID consecutively. We show via simulations that such a design achieves not only a low computational load but also comparable performance, when compared to the conventional detection scheme.