LTE physical layer Research Papers (original) (raw)

2024, River Publishers

In an OFDM system, radio resources are allocated and managed to ensure optimum channel quality for customers. Using a subgroup approach, subscribers have been categorized into different groups based on channel quality. The resources allocated to a subgroup’s consumers are power allocation, capacity, and data rate. A simple algorithm, the OFDMA multicast method, Frequency domain Subgroup Algorithm (FAST), is required to reduce the dimensionality of either subgroup creation problem and also the performance restrictions of basic multiplex data delivery strategies. FAST increases the number of allowable subgroups as well as seeks the best subgroup that outperforms the previous iteration. Throughput increases as a result of this approach due to increased system capacity. The simulation results demonstrate that such a system achieves near-optimal achievement with such a restricted computational load, and therefore, the greater the spectral efficiency, the more resources are assigned.

2024, Elektronika ir Elektrotechnika

Long Term Evolution (LTE) and beyond networks offer high bitrates with low latencies which makes them the best choice to handle the growing demand on multicast mobile services such as video streaming, and news broadcasting. In Conventional Multicast Scheme (CMS), the gain of multicast is exploited by transmitting data to all users simultaneously using the rate of Worst Channel Gain (WCG), which wastes network resources. In this paper, to better balance the tradeoff between the multicast gain and multiuser diversity, we propose a mechanism to select a threshold to split users into two subgroups and exploits the Opportunistic Multicast Scheme (OMS) to transmit the data. Simulation results show that the proposed mechanism improves the multicast performance in terms of increased throughput, decreased delay and Packet Loss Ratio (PLR) compared to existing mechanisms from the literature.

2024

Heterogeneous networks with dense small cell deployment cause high inter-cell interference. To mitigate inter-cell interference, many dynamic interference coordination (IC) approaches have been proposed. For dense deployment with high interference among cells, traditional forward link dynamic IC can cause high air-link packet error rate (PER), due to changing RF conditions and inaccurate channel quality indication (CQI), reducing or even eliminating any improvements achieved by interference coordination. This research describes dynamic centralized interference coordination approaches to improve forward link performance for both infinite buffer (i.e., FTP download) and delay sensitive (i.e., VOIP) traffic for Enterprise LTE femto cell networks. These approaches employ a two-level scheme: at the central level, the algorithm aims to maximize the network utility, by partitioning the network into clusters and exhaustively searching for optimized resource allocation solutions among femtocells (femto access points) within each cluster; at femtocell level, the algorithm employs existing static approaches, such as soft frequency reuse (SFR), partial frequency reuse (PFR) to reduce air-link PER, thus called utilitybased SFR (USFR) and utility-based PFR approach (UPFR). The cell throughput and UE's cell edge throughput (Tput) of infinite buffer traffic, packet loss rate (PLR) of VOIP traffic, have been characterized and compared between proposed approaches and previously proposed methods.

2024, EURASIP Journal on Wireless Communications and Networking

A 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system uses the concept of two-tier heterogeneous networks (HetNets), where low-power and short-range femtocells are laid under macrocells to fulfill the quality of service (QoS) requirements of users and to boost overall network capacity. However, co-channel interference is one of the major issues that need to be resolved for the successful deployment of HetNets. To overcome this problem, fractional frequency reuse (FFR) schemes have been proposed that can efficiently utilize the available spectrum. Nevertheless, these schemes waste limited frequency resources owing to their static allocation and lack of following QoS requirements, network loading conditions, and service priority of users. In this paper, a QoS-based dynamic FFR (QoS-DFFR) scheme is proposed that efficiently allocates the non-occupied center-zone frequency bands, i.e., bonus bandwidth (BBW), to cell-edge users by considering their QoS requirements...

2023

Long Term Evolution (LTE) network offers high throughput with low latency, clearly making it the best choice for multicast services such as; news broadcast, video conferencing, weather reports and much more. In Conventional Multicast Scheme (CMS), data is concurrently transmitted to multicast users over the same channel using the lowest rate. As a result, the CMS performance is bind to the user with the lowest rate. Such scheme is unsatisfactory to users with stronger channels. Thus, an effective Multicast Resource Management (MRM) is needed to utilize all available bandwidth efficiently. This study aims to optimize the MRM policy by exploiting the multiuser diversity technique besides the multicast gain. A new Framed-based QoS-aware MRM (FQMRM) model with three main mechanisms was introduced. The first mechanism is used to enhance the CMS network by determining users who are expensive to cover. In this mechanism, the Opportunistic Multicast Scheme (OMS) is involved; thus, users wit...

2023, International journal of digital enterprise technology

LTE broadcast or evolved multimedia broadcast multicast service (eMBMS) enables operators to efficiently launch media services over LTE to meet mobile users' demand on multimedia services. This paper introduces two mechanisms that use the standard deviation (StD) of eMBMS user's modulation and coding scheme (MCS) level group operated on single cell mode to select its optimal MCS level efficiently. Typically, MCS level is selected on the basis of users' worst channel condition, which results in wasting network resources. Since the eMBMS performance directly depends on the selected MCS level, an efficient adaptive modulation and coding (AMC) scheme is essentially needed. The proposed mechanisms are simulated using LTE simulator, and the results show that the proposed mechanisms increase the eMBMS performance in terms of throughput, delay and packet loss ratio, compared to the worst channel gain and averaging mechanisms.

2023, International Journal of Digital Enterprise Technology

2023

Nowadays LTE (Long Term Evaluation) network becomes more popular and main issue regarding LTE network is indoor coverage. In LTE spectrum is limited so to increase spectral efficiency most of the operator deploy single frequency network but this also increase level of interference. Femtocell deployment inside Macrocell network can reduce indoor coverage issue but unplanned placing of Femtocells as per user requirements may create interference between Femtocells which is called as "Co-tier interference" which may have an impact on the overall performance of Femtocells. Avoiding such interference is very important for Femtocells to work properly. Hence this research survey seeks to analyze various techniques used for Co-tier interference reduction in LTE Femtocell networks are discussed in this review paper.

2023, International Journal of Advanced Computer Science and Applications

Underwater or Acoustic propagation is characterized by three major factors: attenuation that increases with signal frequency, time-varying multipath propagation, and low speed of sound. The background noise, often characterized as Gaussian, is not white, but has a decaying power spectral density. Channel capacity depends on the distance, and may be extremely limited. As acoustic propagation is best supported at low frequencies, an acoustic communication system is inherently wideband and bandwidth is not negligible with respect to its center frequency. The channel has a sparse impulse response, where each physical path acts as a time-varying low-pass filter, and motion introduces Doppler spreading and shifting. Surface waves, internal turbulence and fluctuations in sound speed, contribute to random signal variations. Till date, there are no standardized models for acoustic channel fading. Experimental measurements are often made to assess the statistical properties of the underwater channel.

2023, 2014 IEEE 5th Control and System Graduate Research Colloquium

In cellular system, Fractional Frequency Reuse (FFR) is partition each cell into two regions which are the cell center region and cell edge region. The dissimilar frequency band is owed to each region in cell. The FFR method may reduce channel interference and achieve large system capacity and hence increases the throughput. Long Term Evolution (LTE) has developed a femtocell for indoor coverage extension. However, the development of femtocell in macrocell area will having interference problem and it ought to be answered in move ahead. This paper proposes an interference management scheme in the LTE femtocell systems using FFR proposed method. In detail, the proposed method is the FFR of six sectors and it selects the optimal size of the fraction center radius as well as the system bandwidth fraction. Simulation results show that the proposed method improve the average throughputs in overall network.

2023, Wireless Personal Communications

Underwater Wireless Sensor Networks (UWSNs) are playing a vital role in exploring the unseen underwater (UW) natural resources. However, performance evaluation of UWSNs is still a challenging research problem. Various techniques such as, in-field testing, simulation and emulation have been used for the purpose but they all have limitations. For example, in-field testing is expensive as well as extensive; similarly, a simulation model based on assumptions may not provide precise results. Consequently, it is crucial to have a solution that is reliable, inexpensive and requires less effort to validate the functionality of UWSNs and their components. In this paper, a testbed is proposed that evaluates the UW communication system in a controlled aquatic environment and simulates the UW channel and sound propagation models. The constraint of physical access to the testbed facility is resolved by using a web-based monitoring and controlling graphical user interface. Preliminary results obtained by using the testbed in evaluating the performance of UW communication systems and the simulations done show that the proposed solution is indeed superior to existing solutions as it is cost-effective, requires less effort and is reliable.

2023, Advances in Science, Technology and Engineering Systems Journal

With the introduction of new services and new more sophisticated mobile devices the radio network operators are faced with new challanges to increase the system performance. The most recent standards introduced by 3GPP for the new architectures of the Long Term Evolution network address these issues and outline possibilities for optimizing network performance and user QoS. A major instrument in that respect is the resource scheduling and allocation procedure. So far many different algorithms have ben proposed. Uplink resource allocation however is less covered, beacsue it poses additional constraints which make it difficult to balance the optimization between channel state information, system throughput and user perceived throughput. In this paper we propose a novel algorithm for resource allocation which balances the advantages of two previously suggested ones, specifically Round Robin and Best-CQI. We also define a new parameter, the user ratio, which allows us to explicitly quantify the trade-off between fairness, system throughput and user throughput for different channel conditions.

2023, Elektronika ir Elektrotechnika

2023

This paper investigates the concept of Mobile Femtocell with considering the feasibility of deploying Mobile Femtocells in public transportation vehicles such as trains, buses or private cars that form its own cell inside vehicles to serve vehicular and mobile User Equipments. This study is the launch of cell-edge mobile users who have always suffered degradation in the Quality of Service (QoS). Therefore, an investigation on the performance of LTE cell-edge mobile User Equipment e.g. users’ throughput, SINR, SNR, SIR, spectral efficiency and Handover performance, have been considered with deploying Fixed Femtocells and Mobile Femtocells in Long Term Evolution network. Two scenarios have been proposed in this study; Fixed Femtocells with mobile users and Mobile Femtocells with mobile users. More scenarios maybe considered in the case of Mobile Femtocell’s handover procedure. MATLAB simulation has been used for the purpose of simulating the designed scenarios and implementing the int...

2023, Journal of Multimedia

This work aims at studying the indoor deployment of small cells, also known as femtocells, to provide coverage to a 5×5 grid geometry. The number of deployed HeNBs is 4, 5, or 6. An updated version of LTE-Sim is considered to extract values for Exponential Effective SINR Mapping (EESM), Packet Loss Ratio (PLR), maximum number of supported users, goodput and delay. Results reveal that the use of four HeNBs corresponds to the highest values of EESM. For the considered geometry, 3GPP suggested a maximum of five HeNBs. However, this deployment shows worser performance compared to the topology with four HeNBs. The geometry with six HeNBs is the one with the best overall performance results for the 5×5 grid of apartments.

2023, Wireless Personal Communications

High Peak-to-average power ratio (PAPR) is one of the main issues in multicarrier modulation systems. PAPR is mainly caused due to the summation of various signals having high amplitude values. Several PAPR reduction techniques were employed, out of which Selective Mapping (SLM) proved to be one of the most effective schemes. Some drawbacks in SLM technique are high computational complexity and phase search complexity. Selection of phase sequences in SLM plays a major role in the reduction of PAPR as well as the computational complexity. Modified SLM was introduced to reduce computational complexity in SLM technique. In this paper, we apply various phase sequences such as Riemann, Centering, Centered Riemann and New Centered to Modified SLM technique and their effect on PAPR reduction are analyzed. From the simulation results, it can be inferred that the modified SLM with New Centered scheme achieves a significant PAPR reduction of the range 8.3-9.3 dB with respect to Conventional OFDM and 3-5.5 dB with respect to Conventional SLM technique. The Modified SLM-New Centered scheme is most suitable for 64-QAM applications as it provides good PAPR reduction performance at lower computational complexity.

2023, International Journal of Electrical and Computer Engineering (IJECE)

When an area is highly populated with Machine-to-Machine devices and all these devices attempt to access the Random Access Network Simultaneously, congestion is created on the network which degrades the performance of the network to other users. In this paper, the researchers are seeking to improve network accessibility by deploying more Femtocell into the network. They engaged the use of Extended Access Barring to restrict the M2M devices from accessing the network via macrocell eNB when a minimum load threshold is attained, thereby preventing the macrocell eNB from being congested. Deploying these Femtocells underneath the macrocell eNB comes with the issue of Inter-Cell Interference which nullifies any gains made by this deployment. The researchers employed Fractional Frequency Reuse and Complete Frequency Reuse schemes to mitigate the negative effects of ICI to augment the throughput of the network, improve the system capacity and enhanced the user experience within the network.

2023

Ponencia presentada en: XXX Simposium Nacional de la Unión Científica Internacional de Radio, los dias 2 y 4 septiembre 2015, en Pamplona (españa).Video services are expected to become more than 70% of the mobile traffic in 2020. Broadcast and multicast service is the most efficient mechanism to deliver the same content to many users. Not only focusing on venue casting, but also distributing many other media such as software updates and breaking news, 5G broadcasting is a key driver to achieve the spectral efficiency needed for the 1,000 times traffic growth that is expected for the upcoming years. Improvements in some areas, such as resource allocation techniques for broadcast/multicast services, are needed. The utilization of the Conventional Multicast Scheme (CMS) approach for multicast resource allocation presents intrinsic inefficiencies, because of the different channel conditions of the users which demand the service. This paper presents some resource allocation strategies ba...

2023, 2011 28th National Radio Science Conference (NRSC)

In this paper a comparative study between L TE and WiMAX, the two leading wireless broadband technologies, is introduced. The performance metrics used for the evaluation are the response time and the throughput derived from OPNET modeler release 16 system level simulator. To perform the comparison 4 scenarios were developed the fIrst two are for 7 cell LTE and 7cell WiMAX networks while the second two are for 19 cell L TE and 19cell WiMAX networks. The numerical results are obtained for links between mobiles at fIxed relative positions in the four scenarios. Through this analysis we found that LTE networks gave shorter response time than WiMAX. The throughput is also compared and results showed that WiMAX outperformed L TE in this respect.

2023, International Journal of Electrical and Computer Engineering (IJECE)

Handover is a process that allows a mobile node to change its attachment point. A mobile node connected to a network can, in order to improve the quality of service, have the need to leave it to connect to a cell either of the same network or of a new network. The present paper introduce three techniques using adaptive Variable Step-Size Least Mean Square (VSSLMS) filter combined with spectrum sensing probability method to detect the triggering of handover in heterogeneous LTE networks. These techniques are Normalized LMS (NLMS), Kwong-NLMS and Li-NLMS. The simulation environment is composed of two femtocells belonging to a macrocell. Five User Equipements (UEs) are positioned in one femtocell and are assumed closest to its circumference. Simulation results show that sensing probability with Li-NLMS algorithm has a better performance compared with classical NLMS and Kwong-NLMS

2023

Power and Coverage Based Performance Analysis for Femtocells Network Muhammad Jamshed Abbas, Muhammad Awais**, Waqas Ahmad Mirza, Jibran Hashim, Sohail Abbas, Arsalan Hameed Department of Electrical Engineering, Riphah International University Islamabad, Pakistan Transmission and Distribution Systems Research Institute, North China Electric Power University Beijing, China Emails: jamshed.abbas@outlook.com, m.awais.warraich@outlook.com, waqasmirza@hotmail.com, ABSTRACT The study of mobile communication/ cellular network in the industry of telecommunication is the fast-growing technology of this era. Demands of higher data rates in the indoor environment is increasing day by day. To achieve this demand femtocells are the best option for indoor environment. In the coming future, Femtocell is most important and best case for low power and low-cost base stations for indoor users. It is widely acceptable that by providing better quality in indoor environment, there will be a great revenue...

2023, AEU - International Journal of Electronics and Communications

Generalized frequency division multiplexing (GFDM) is the foremost contender for physical layer of 5G communication. The flexible nature of GFDM allows multiple symbols in time domain to superimpose, thereby creating high peak to average power ratio (PAPR). The idea of selective mapping (SLM) is to use a sequence of phase rotation vectors for generating alternatives using original GFDM signal. Among them, signal with lowest PAPR is selected for transmission. This procedure requires mandatory side information (SI) estimation or transmission which in turn decreases data reliability or efficiency. To address these issues, authors present a modified approach of pilot-assisted GFDM SLM system without need of SI transmission and to enable joint PAPR reduction and data recovery. In the proposed approach, we utilize a common modulating phase to modulate all subcarriers in a subsymbol assuming that each subsymbol consists of at least two pilots. This creates an inherent SI cancellation mechanism using the pilots which are employed for channel estimation. For practical validation of proposed concepts, we used software-defined radio (SDR) experimental setup employing universal software radio peripheral USRP) 2953R as hardware and Labview as software. Experimental results show a significant reduction in out-of-band spectral leakage without disturbing the estimated channel response.

2023

Zero padded single carrier spatial modulation system is an effective method of data transmission. This system achieves full multipath diversity and imposes a relatively low maximum likelihood detection complexity. However the main drawback of this system is that it suffers from high Peak-to-Average problem. In this paper, we propose an effective reduction scheme that combines Discrete Cosine transform and Selective mapping technique along with zero padding. The scheme is composed of the Discrete Cosine transform followed by the Selective mapping using the Riemann matrix to obtain phase sequences for the Selective mapping technique. The simulation results shows that the PAPR can be greatly reduced by applying the proposed system with low complexities computation and the bit error rate performance is significantly better than the zero padded spatial modulation technique. This approach also avoids randomness in phase sequence selection to provide easier decoding at the receiver. Also t...

2023, Second International Conference on Future Generation Communication Technologies (FGCT 2013)

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2022

Binary sequences such as chaotic-binary (CB) sequences derived from an iterative chaotic equation have been used in selected mapping (SLM) methods to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Though CB sequences have been shown to produce good PAPR reduction performance, their implementation requires a significant number of complex computations which may increase both design costs and energy requirements. This paper presents an alternative form of binary sequences derived from a Fibonacci series and referred to as Fibonacci-Binary (FB) sequences. Simulations show that although CB sequences produce slightly improved PAPR reduction performance over the proposed FB sequences for larger numbers of applied SLM vectors, both forms of binary sequences produce similar bit-error-rate (BER) performance even in the presence of non-linear power amplifier distortion. In terms of computational complexity however, it is shown that FB sequences have significantly reduced computational requirements over CB sequences and thus may be considered as preferred option for reducing PAPR in SLM based OFDM systems.

2022, International Journal of Information and Electronics Engineering

Performance of pilot-aided channel estimation techniques such as the Least Squares (LS) method depends on not only on the signal-to-noise ratio (SNR), channel conditions and pilot ratio, but also on the choice of interpolation method for deriving channel estimates at non-pilot subcarriers. This paper investigates the bit-error-rate (BER) performance of linear, spline and Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) interpolation methods in LS channel estimation over the three extended ITU channel profiles defined for Long Term Evolution (LTE) testing. Simulation results show that applying the linear interpolation method produces the best BER performance over the fading channel with the smallest multipath delay spread. It is also shown that the choice of best interpolation method actually depends on the SNR in some of the fading channel profiles.

2022, 2014 IEEE 5th Control and System Graduate Research Colloquium

2022, International Journal of Science and Engineering

With high speed access network technology like WIMAX, there is the need for efficient management of radio resources where the throughput and Qos requirements for Multicasting Broadcasting Services (MBS) for example TV are to be met. An enhanced feedback-base downlink Packet scheduling algorithm that can be used in IEEE 802.16d/e networks for mobile TV "one way traffic"(MBS) is needed to support many users utilizing multiuser diversity of the broadband of WIMAX systems where a group of users(good/worst channels) share allocated resources (bandwidth). This paper presents such enhanced downlink packet scheduler for mobile TV traffics in IEEE 806.16, whereby network Physical Timing Slots (PSs) resource blocks are allocated in a dynamic way to mobile TV subscribers considering the Channel State information CSI (CQI) feedback. It also considers users with worst/weak channels with the aim of improving system throughput while system coverage is being guaranteed. Change in the PSs bandwidth allocation to users and different number of users per cell sector are use to check the algorithm. Simulation results show our proposed algorithm performed better than other algorithms (blind algorithms) in terms of improvement in system throughput performance. Further work like above can be done for another traffic e.g. gaming traffics utilizing broadband technology of WIMAX.

2022

2. Proposed Work Wireless Sensor Networks (WSNs) have become an important means of gathering environmental and physical information from a wide range of areas. WSNs could be used in underground, aboveground and underwater applications. In this work, we propose a new solution for underwater Wireless Sensor Networks to overcome the problem caused by the ionized nature of seawater. This work presents a methodology to improve the lifetime of WSNs. The wireless sensors have three main functions: sensing, processing and transmitting. The first two consume very less power compared to the third. Thus, we need to guarantee the successful transmission of signal with nominal and efficient use of power to improve the lifetime of the sensors. Improving the lifetime of these sensors will improve the experience of the end user, as the information-gathering lifetime of the sensors increases. Our validated results showed reduction in the power consumption, thus improving the lifetime and the signal loss rate.

2022, Journal of Communication and Information Systems

The increasing exploitation of natural resources under water, particularly in the sea, has ignited the development of many technological advances in the domains of environmental monitoring, oil and gas exploration, warfare, among others. In all these domains, underwater wireless communications play an important role, where the technologies available rely on radiofrequency, optical, and acoustic transmissions. This paper surveys key features inherent to these communication technologies, putting into perspective their technical aspects, current research challenges, and to-be-explored potential. I. INTRODUCTION Underwater wireless communications present new and distinct challenges when compared to wired and wireless communications through the atmosphere, requiring sophisticated communication devices to achieve relatively low transmission rates, even over short distances. Indeed, the underwater environment possesses a number of distinguishing features that make it unique and rather different from terrestrial radio propagation where traditional communication systems are deployed. Under water, several phenomena may influence communications, such as salt concentration, pressure, temperature, amount of light, winds and their effects on waves, just to mention a few [1], [2]. Despite all challenges, wireless communications certainly play an important role in practical underwater systems. Monitoring different phenomena in underwater environment is relevant in many different applications, such as oil and gas exploration, coastal security, environmental impact surveillance, navigation, and ocean-pollution control [3]. Specific examples include transmission of data among devices, such as AUV (autonomous underwater vehicle) to AUV and buoy to AUV, particularly those employing wireless links. In fact, an entire underwater wireless communication network could

2022, Materials Research Bulletin

The NixZn1-xFe2O4 thin films have been prepared using a simple spray pyrolysis technique. The X-ray diffraction studies reveal that, the films are polycrystalline with spinel structure. The lattice parameters vary in the range of 8.35 to 8.48 Å with composition (x) obeying Vegard's rule. SEM and AFM studies show that the surface of the films exhibit a smooth, compact and a pin hole free morphology. Raman spectra indicate first order Raman active modes; A1g (λ = 334 cm-1); Eg (λ = 148 cm-1) and T2g (λ = 699) of the NixZn1-xFe2O4. The investigation on dielectric constant, dielectric loss tangent and ac conductivity was carried out in the frequency range 20 Hz-1 MHz at room temperature. The linear nature of the AC conductivity shows small polaron type of hopping mechanism. The saturation magnetization increases up to the x = 0.4 (143 emu/cm 3), which decreases for higher x.

2022

In present paper, the analysis on the reliable performance of the acoustic wave based underwater wireless sensor network communication is done. Underwater wireless sensor network deployment is increasing day by day because of immense use in different applications such as earthquake and tsunami pre-warning, climate and ocean natural resources investigations, and water pollution monitoring etc. In this paper, A discussion will be done on system propagation channel modelling of acoustic communication network in underwater and its corresponding challenges. In ocean bottom and surface of oceans, the sensor nodes, surface stations, and global positioning system form underwater acoustic sensor network that serve as gateways and provide radio communication links to on-shore base stations. This force to characterize a path loss in underwater acoustic channel that can be calculated on basis of signal frequency travelling in oceans and transmission distance, absorption loss and attenuation, Si...

2022, IEEE Open Journal of the Communications Society

The ever-increasing demand for applications with stringent constraints in device density, latency, user mobility, or peak data rate has led to the appearance of the last generation of mobile networks (i.e., 5G). However, there is still room for improvement in the network spectral efficiency, not only at the waveform level but also at the Radio Resource Management (RRM). Up to now, solutions based on multicast transmissions have presented considerable efficiency increments by successfully implementing subgrouping strategies. These techniques enable more efficient exploitation of channel time and frequency resources by splitting users into subgroups and applying independent and adaptive modulation and coding schemes. However, at the RRM, traditional multiplexing techniques pose a hard limit in exploiting the available resources, especially when users' QoS requests are unbalanced. Under these circumstances, this paper proposes jointly applying the subgrouping and Non-Orthogonal Multiple Access (NOMA) techniques in 5G to increase the network data rate. This study shows that NOMA is highly spectrum-efficient and could improve the system throughput performance in certain conditions. In the first part of this paper, an in-depth analysis of the implications of introducing NOMA techniques in 5G subgrouping at RRM is carried out. Afterward, the validation is accomplished by applying the proposed approach to different 5G use cases based on vehicular communications. After a comprehensive analysis of the results, a theoretical approach combining NOMA and time division is presented, which improves considerably the data rate offered in each use case.

2022

this paper explores the recent applications of wireless sensor networks (WSNs), especially Underwater WSNs (UWSN), by International Oil Companies (IOCs) in monitoring underwater oil pipelines in Nigerian oil rich Niger Delta region. It examined the different architectures for monitoring underwater pipelines, their challenges and how to overcome them. The paper also looked at how underwater WSNs can be used together with their measurement and communication devices such as GSM modem and Global Positioning System (GPS) to transfer sensed data from underwater network to control station far away from the pipeline.

2022, International Journal of Computer Theory and Engineering

Terrestrial and airborne Wireless Sensor Networks rely on radio frequencies as their communication medium for transmitting data and information. However, sensing and subsequent transmission in sub-sea environment e.g. deep sea exploration requires all together a different approach for communication that has to be done under water. There's no escaping the fact that a huge amount of unexploited resources lies in the 70% of the earth covered by oceans. Yet, the aquatic world has mainly been unaffected by the recent advances in the area of Wireless Sensor Networks (WSNs) and their pervasive penetration in modern day research and industrial development. The current pace of research in the area of Underwater Acoustic Sensor Networks (UASNs) is at a snail's pace due to the difficulties arising in transferring most of the land and air based WSNs' state-of-the-art to their underwater equivalent. Maximum underwater deployments rely on acoustics for enabling communication combined with special sensors having the capacity to take on harsh environment of the oceans. This paper particularly focuses on gathering most recent developments and experimentation related to key underwater sensor network applications and UASNs deployments for monitoring and control of underwater domains.

2022, Wireless Engineering and Technology

To provide quality-of service (QoS) guarantees for heterogeneous applications, most recent wireless communications technologies and standards combine the error-correcting capability of hybrid automatic repeat request (HARQ) schemes at the data link layer (DLL) with the adaptation ability of the adaptive modulation and coding (AMC) modes at the physical layer (PHY) layer. This paper aims to investigate the aggregated system capacity as well as the breakdown of this capacity for different ACM modes in each HARQ scheme. This investigation was done by using maximum weighted capacity (MWC) resource allocation at the PHY layer in conjunction with a novel packet error rate (PER)based scheduling at the medium access control (MAC) layer. As a result, the dominant AMC mode corresponding to channel SNR was available.

2022, Journal of Advanced Research

Signal to interference and noise ratio (SINR) Fractional frequency reuse (FFR) Soft frequency reuse (SFR) Heterogeneous network performance of the different methods. Therefore, this paper introduces general expressions for the SINR in homogeneous and in heterogeneous networks. In homogeneous networks, the expression was applied for the most common types of frequency reuse techniques: soft frequency reuse (SFR) and fractional frequency reuse (FFR). The expression was examined by comparing it with previously developed ones in the literature and the comparison showed that the expression is valid for any type of frequency reuse scheme and any network topology. Furthermore, the expression was extended to include the heterogeneous network; the expression includes the problem of co-tier and cross-tier interference in heterogeneous networks (HetNet) and it was examined by the same method of the homogeneous one.

2022

Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by means of simulation or by means of analytical models with simplified back-off rule assumptions. Binary Exponential Back-off (BEB) is the widely used back-off mechanism in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hoc network and some new back-off schemes such as Multiplicative Increase and Linear Decrease (MILD) and Double Increment Double Decrement (DIDD) were proposed. This paper, investigate the performance of collision avoidance MAC protocol in multi-hop wireless ad-hoc network by adopting MILD back-off mechanism. A three state Markov chain is used to model the channel states and node states. These models were used to derive the duration time, steady-state probabilities of the states of node and throughput of Mobile Ad-hoc NETwork (MANET). Simulation results show no matter the value of average number of neighbors , transmission range , and length of DATA frames , the throughput of MANET always achieves the maximum value at some point of persistent probability and also the throughput of a MANETs increases with increase in persistent probability which is influenced by the number of neighbors, transmission range and length of DATA frame. On the other hand the throughput decreases with increase in sensing range which is also influenced by the number of neighbors, transmission range and length of DATA frame.

2022

2022, Vehicular Communications

Mobile computing is fast becoming a vital part of everyday life in which User Equipment (UE) demand being reachable anywhere and at anytime, as they spend much time travelling from one place to another, often by trains or buses. The ultimate aim of passengers is the ability to be connected to the Internet while they are moving from one place to another with their mobile devices. Providing indoor coverage the high density of use and path losses in the LTE network. This limitation can result in poor signal quality inside the train, and offering broadband services is not always possible. Clearly improvement and bus routes and terminals. However, this solution is not ideal for the Internet Service Providers (ISPs) due to the high investment needed to deploy many more BSs. In addition, such a solution will introduce additional complexity by increasing the number of Handovers (HOs). This issue has focused the research community effort on developing solutions that take advantage of the existing wireless infrastructure without increasing the number of BSs. One method being considered is the development of more efficient methods and technologies to manage the UE's mobility in seamless ways. In this paper we propose adoption of Mobile Femtocell (Mobile-Femto) technology as a solution to mitigate the Vehicular Penetration Loss (VPL) and Path Loss, with consequent improvement to the vehicular UE's performance in LTE networks. Our results, using a Matlab simulation model, showed a noticeable improvement in the achieved Ergodic capacity by 5% under a VPL of 40 dB while 90% of vehicular UEs spectral efficiency has improved by 1.3 b/cu under a VPL of 25 dB. In addition, 80% of vehicular UEs have improved their throughput and SINR by 300 kb/s and 4 dB respectively after implementing the Mobile-Femto into the Macrocell in LTE networks.

2022

Using simulation tools save the construction cost of the wireless system. It is not necessary to establish the system and test whether it is working properly or not. Therefore, simulation tools are required to be accurate, simple and with the minimum time. From the accuracy perspective, the stacked femtocells built in most available simulators in the literature are widely deployed horizontally. However, this is not the case in the indoor environment where femtocells have to be arranged vertically; such as, in residential towers where apartments are on the top of each other. In this paper, the state of the art of link and system level simulators is introduced. In addition, a three-dimensional (3D) system level simulator is developed in order to help the researcher in the Long Term Evolution (LTE) femtocell field to analyze and investigate more real scenarios of femtocell deployment. The developed simulator allows the researcher to locate a multi-story building in the region of intere...

2022, Advances in Science, Technology and Engineering Systems Journal

2022

The huge capacity requirements for the next generation mobile network is defining the technologies that will drive the future system. The trio of millimeter wave, massive MIMO and small cell are emerging as the tripod upon which the upcoming network is expected to thrive. With about 80% indoor mobile usage, small cell and by extension, femtocell is projected to deliver the bulk of the predicted mobile traffic. This paper takes an overview of the future 5G network and advances solutions to the most anticipated interference challenges as a result of cell densification.

2021

The fourth-generation networks based on OFDMA (3GPP LTE) (3rd Generation Partnership Project Long Term Evolution) offer high bit rate and takes into account in their mechanisms the simplicity and efficiency of the radio transmission. But with the volume of traffic constantly increasing, especially in high density population environments, the reuse of bandwidth is the only effective way to increase the capacity in LTE system. The conventional approach to improve the spectrum efficiency is to reuse the same frequency band in multiple geographic areas or cells. However, inter-cell interference (ICI) will inevitably disadvantageous, when the mobile stations or users in adjacent cells share the same spectrum. High mobility makes the situation worse. The SINR at the Cell-edge may be so poor that even the most robust control channel PDCCH cannot function properly. This is one of the major problems limiting the performance of LTE (Long Term Evolution). This work studies the impact of inter-...

2021

Initial downlink synchronization for orthogonal frequency division multiple access (OFDMA) network access involves timing and frequency synchronization. The frequency offset is produced by oscillator drifts and time-varying Doppler shifts. In mobile WiMAX 802.16e carrier frequency offset (CFO) can be divided into: integral carrier frequency offset (ICFO) and fractional carrier frequency offset (FCFO). There are mainly three methods for CFO estimation: data-aided method, blind and semi-blind. This paper is based on the semi-blind method presented in "Joint detection of integral carrier frequency offset and preamble index in OFDMA WiMAX downlink synchronization", IEEE, 2007 , see [2]. We simplify the algorithm presented in that paper by (a) using an adder-subtractor instead of using squares to estimate power and (b) by using a XNOR instead of complex multiplier; thereby reducing hardware gates by a factor of 676. Simulation results show only a slight degradation in performance with a considerable reduction in complexity.

2021, International Journal of Future Generation Communication and Networking

Today's era people have grown in every field, such that their needs are also growing linearly with their advancement. This rapid development of broadband wireless access technologies in recent years was the result of growing demand for mobile Internet and wireless multimedia applications. Now it is becoming difficult to meet the demands of these data hungry people. So, the wireless network is advancing after 3G and providing better coverage, higher data rate and by reducing Latency. It uses the frame structure as Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD).LTE technology uses different channels in both uplink and downlink. This paper mainly focuses on the Downlink channels named as PDCCH, PBCH, PCFICH, PHICH and downlink Signals i.e., PSS and S-SS. The individual Downlink Channels are analyzed using Agilent SystemVue platform further it is synchronized with the Agilent Vector Signal Analyzer (VSA) to the check the Output Response of the individual downlink channels.

2021, International Journal of Electrical and Computer Engineering (IJECE)

2021, International Journal of Computer Applications

The key characteristic of a cellular network is the ability to reuse frequencies to increase both coverage and capacity. Fractional frequency reuse (FFR) is considered to be an efficient inter-cell interference coordination technique wellsuited for OFDMA based on wireless communication networks where the cells are partitioned into spatial regions with different frequency reuse factors. In this paper, evaluating strict FFR which represents a type of FFR deployments is presented with four different system models by changing the inner-cell shape for each model. System simulations are used to compare and evaluate the effect of changing the inner-cell shape based on strict FFR performance which performed using dense Monte Carlo simulations. In addition, the effects of some system model parameters are discussed.

2021, Journal of Communications

Mobile networks use femtocells as low-power nodes to improve indoor coverage and thus achieve a high network capacity. In this paper, we focus on a combination of macrocells and femtocells in Long-Term Evolution (LTE) networks. In order to achieve a high LTE network performance, we investigate the influence of power allocated to Evolved Node B (eNodeB) and Home eNodeB (HeNodeB). Using the Round-Robin scheduling, while decreasing the eNodeB's transmit power and increasing the HeNodeB's transmit power, improves the user's throughput significantly. We further demonstrate, by simulations, that applying other scheduling algorithms under the low eNodeB transmit power and high eNodeB transmit power results in a significantly increased performance in the LTE network.