scholarly journals Analysis of Synchronization Impairments for Cooperative Base Stations Using OFDM

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Konstantinos Manolakis ◽  
Christian Oberli ◽  
Volker Jungnickel ◽  
Fernando Rosas
Keyword(s):  
Carrier Frequency ◽  
Joint Effect ◽  
Sampling Frequency ◽  
Base Station ◽  
Base Stations ◽  
Intercarrier Interference ◽  
Mean Power ◽  
Actual System ◽  
Frequency Offsets ◽  
The Impact

Base station cooperation is envisioned as a key technology for future cellular networks, as it has the potential to eliminate intercell interference and to enhance spectral efficiency. To date, there is still lack of understanding of how imperfect carrier and sampling frequency synchronization between transmitters and receivers limit the potential gains and what the actual system requirements are. In this paper, OFDM signal model is established for multiuser multicellular networks, describing the joint effect of multiple carrier and sampling frequency offsets. It is shown that the impact of sampling offsets is much smaller than the impact of carrier frequency offsets. The model is extended to the downlink of base-coordinated networks and closed-form expressions are derived for the mean power of users’ self-signal, interuser, and intercarrier interference, whereas it is shown that interuser interference is the main source of degradation. The SIR is inverse to the base stations’ carrier frequency variance and to the square of time since the last precoder update, whereas it grows with the number of base stations and drops with the number of users. Through user selection, the derived SIR upper bound can be approached. Finally, system design recommendations for meeting synchronization requirements are provided.

scholarly journals Dynamic access class barring and relay assisted radio resource allocation methods for cellular M2M networks

2021 ◽  
Author(s):  
Lilatul Ferdouse
Keyword(s):  
Resource Allocation ◽  
Load Balancing ◽  
Transmission Rate ◽  
Random Access ◽  
Base Station ◽  
Base Stations ◽  
Radio Resource Allocation ◽  
Radio Resource ◽  
Selection Probability ◽  
The Impact

Cellular based M2M systems generate massive number of access requests which create congestion in the cellular network. The contention-based random access procedures are designed for cellular networks which cannot accommodate a large number of M2M traffic. Moreover, M2M systems share same radio resources with cellular users. Resource allocation problem becomes a challenging issue in cellular M2M systems. In this thesis, we address these two problems by analyzing a contention-based slotted Aloha random access procedure for M2M networks using different performance metrics. The impact of massive M2M traffic over cellular traffic is studied based on different arrival rate, random access opportunity and throughput. An analytical model of selecting a base station (eNB) along with load balancing is developed. Finally, two methods have been presented and evaluated with M2M traffic. First one is dynamic access class barring method which controls RAN level congestion by selecting an appropriate eNB and applying load balancing method. Second one is relay-assisted radio resource allocation method which maximizes the sum throughput of the system by utilizing the available radio resource blocks and relay nodes to the MTC systems. Numerical results show that frame transmission rate influences the selection probability of the base stations. Moreover, the dynamic access class barring parameter along with frame transmission rate improve the overall throughput and access success probability among base stations as well as avoid overload situation in a particular base station.

scholarly journals Performance Analysis of Backhaul-Aware User Association in 5G Ultradense Heterogeneous Networks

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Junpeng Yu ◽  
Hongtao Zhang ◽  
Yuqing Chen ◽  
Yaduan Ruan
Keyword(s):  
Heterogeneous Networks ◽  
Association Scheme ◽  
Coverage Probability ◽  
Network Performance ◽  
Performance Metrics ◽  
Density Ratio ◽  
Base Station ◽  
Base Stations ◽  
User Association ◽  
The Impact

In 5G ultradense heterogeneous networks, wireless backhaul, as one of the important base station (BS) resources that affect user services, has attracted more and more attention. However, a user would access to the BS which is the nearest for the user based on the conventional user association scheme, which constrains the network performance improvement due to the limited backhaul capacity. In this paper, using backhaul-aware user association scheme, semiclosed expressions of network performance metrics are derived in ultradense heterogeneous networks, including coverage probability, rate coverage, and network delay. Specifically, all possible access and backhaul links within the user connectable range of BSs and anchor base stations (A-BSs) are considered to minimize the analytical results of outage probability. The outage for the user occurs only when the access link or backhaul link which forms the link combination with the optimal performance is failure. Furthermore, the theoretical analysis and numerical results evaluate the impact of the fraction of A-BSs and the BS-to-user density ratio on network performance metric to seek for a more reasonable deployment of BSs in the practical scenario. The simulation results show that the coverage probability of backhaul-aware user association scheme is improved significantly by about 2× compared to that of the conventional user association scheme when backhaul is constrained.

scholarly journals Stochastic Geometry Analysis of Downlink Spectral and Energy Efficiency in Ultradense Heterogeneous Cellular Networks

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Jiaqi Lei ◽  
Hongbin Chen ◽  
Feng Zhao
Keyword(s):  
Energy Efficiency ◽  
Cellular Networks ◽  
Stochastic Geometry ◽  
Density Ratio ◽  
Base Station ◽  
Small Cell ◽  
Base Stations ◽  
Heterogeneous Cellular Networks ◽  
Downlink Throughput ◽  
The Impact

The energy efficiency (EE) is a key metric of ultradense heterogeneous cellular networks (HCNs). Earlier works on the EE analysis of ultradense HCNs by using the stochastic geometry tool only focused on the impact of the base station density ratio and ignored the function of different tiers. In this paper, a two-tier ultradense HCN with small-cell base stations (SBSs) and user equipments (UEs) densely deployed in a traditional macrocell network is considered. Firstly, the performance of the ultradense HCN in terms of the association probability, average link spectral efficiency (SE), average downlink throughput, and average EE is theoretically analyzed by using the stochastic geometry tool. Then, the problem of maximizing the average EE while meeting minimum requirements of the average link SE and average downlink throughput experienced by UEs in macrocell and small-cell tiers is formulated. As it is difficult to obtain the explicit expression of average EE, impacts of the SBS density ratio and signal-to-interference-plus-noise ratio (SINR) threshold on the network performance are investigated through numerical simulations. Simulation results validate the accuracy of theoretical results and demonstrate that the maximum value of average EE can be achieved by optimizing the SBS density ratio and the SINR threshold.

scholarly journals Determining the optimal site location of GNSS base stations

2012 ◽  
Vol 18 (1) ◽  
pp. 154-169 ◽  
Author(s):  
Jen-Yu Han ◽  
Yu Wu ◽  
Rou-Yu Liu
Keyword(s):  
Integrated Approach ◽  
Satellite System ◽  
Base Station ◽  
Base Stations ◽  
Relative Positioning ◽  
Site Location ◽  
Efficient Manner ◽  
Global Navigation Satellite ◽  
The Impact ◽  
Optimal Site

The relative positioning technique plays an essential role in Global Navigation Satellite System (GNSS) surveys. Simultaneous observation at base and rover stations eliminates the majority of error sources thus the quality of a positioning solution can be substantially improved. However, topographic obstruction is still a key issue affecting positioning quality. In this study, an integrated approach for analyzing the impact of topographic obstruction on GNSS relative positioning has been developed. By considering varied satellite geometry according to actual terrain variation, this approach can be used to realistically determine satellite visibility condition for a specific base station with respect to any rover station. Furthermore, a base station quality index (BSQI) is proposed as an explicit indication of the sufficiency in a relative positioning. By incorporating the proposed approach, one can immediately identify an optimal site location for a GNSS base station with subsequent GNSS field survey thus achieved in a more reliable and cost-efficient manner.

scholarly journals Dynamic access class barring and relay assisted radio resource allocation methods for cellular M2M networks

2021 ◽  
Author(s):  
Lilatul Ferdouse
Keyword(s):  
Resource Allocation ◽  
Load Balancing ◽  
Transmission Rate ◽  
Random Access ◽  
Base Station ◽  
Base Stations ◽  
Radio Resource Allocation ◽  
Radio Resource ◽  
Selection Probability ◽  
The Impact

Cellular based M2M systems generate massive number of access requests which create congestion in the cellular network. The contention-based random access procedures are designed for cellular networks which cannot accommodate a large number of M2M traffic. Moreover, M2M systems share same radio resources with cellular users. Resource allocation problem becomes a challenging issue in cellular M2M systems. In this thesis, we address these two problems by analyzing a contention-based slotted Aloha random access procedure for M2M networks using different performance metrics. The impact of massive M2M traffic over cellular traffic is studied based on different arrival rate, random access opportunity and throughput. An analytical model of selecting a base station (eNB) along with load balancing is developed. Finally, two methods have been presented and evaluated with M2M traffic. First one is dynamic access class barring method which controls RAN level congestion by selecting an appropriate eNB and applying load balancing method. Second one is relay-assisted radio resource allocation method which maximizes the sum throughput of the system by utilizing the available radio resource blocks and relay nodes to the MTC systems. Numerical results show that frame transmission rate influences the selection probability of the base stations. Moreover, the dynamic access class barring parameter along with frame transmission rate improve the overall throughput and access success probability among base stations as well as avoid overload situation in a particular base station.

scholarly journals Impact of Base Station Site, Antenna Configuration and Power Control in LTE Network

2019 ◽  
pp. 1-8
Author(s):  
Alhassan Shilo Shekwonya ◽  
Lebe Nnanna
Keyword(s):  
Power Control ◽  
Beam Width ◽  
Base Station ◽  
Google Earth ◽  
Base Stations ◽  
Network Simulator ◽  
Lte Network ◽  
Data Rates ◽  
Antenna Configuration ◽  
The Impact

This study analyzed the impact of spatial distribution of APs/Base stations, antenna configuration and power control in a dense populated area like Owerri (Nigeria), using link planner network simulator and Google-Earth Software. High-effective data capacity at hotspots in conjunction with bandwidth and the predicted power at the receiver for LTE network are required to capture some  number of users and provide high data rates over the Wi-Fi interface. The data rates are influenced by the terrain, which loses throughput due to delays, path loss and interference. The hotspot range which determines the number of users, that can associate, is limited by the power of the client and the access point. The variables that affect link performance, such as: band, region, equipment, antenna, height, terrain and obstructions towards providing enhanced capacity and coverage are measured by the link planner. The characteristics like gain, beam, width and frequency, for evaluation of results in terms of coverage and capacity for different antenna configurations, receive-Power, terrain, bandwidth and distances are also observed respectively. The results show that pathloss increases or decreases with these factors between nodes. The strategy to place the transmitter in the highest position has also proven better performance for implementation of the LTE system and its long run operation.

scholarly journals Carrier Frequency Offsets Problem in DCT-SC-FDMA System: Investigation and Compensation

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Faisal S. Al-kamali ◽  
Moawad I. Dessouky ◽  
Bassiouny M. Sallam ◽  
Farid Shawki ◽  
Fathi E. Abd El-Samie
Keyword(s):  
Carrier Frequency ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Minimum Mean Square Error ◽  
Multiple Access Interference ◽  
Low Complexity ◽  
Estimation Errors ◽  
Carrier Frequency Offsets ◽  
Frequency Offsets ◽  
The Impact

The Single-Carrier Frequency Division Multiple Access (SC-FDMA) system is a well-known system, which has recently become a preferred choice for uplink channels. In this system, the Carrier Frequency Offsets (CFOs) disrupt the orthogonality between subcarriers and give rise to Intercarrier Interference (ICI), and Multiple Access Interference (MAI) among users. In this paper, the impact of the CFOs on the performance of the Discrete Cosine Transform (DCT) SC-FDMA (DCT-SC-FDMA) system is investigated. Then, a new low-complexity joint equalization and CFOs compensation scheme is proposed to cancel the interference in frequency domain. The Minimum Mean Square Error (MMSE) equalizer is utilized in the proposed scheme. A hybrid scheme comprising MMSE equalization, CFOs compensation, and Parallel Interference Cancellation (PIC) is also suggested and investigated for further enhancement of the performance of the DCT-SC-FDMA system with interleaved subcarriers assignment. For simplicity, this scheme will be referred to as the MMSE+PIC scheme. From the obtained simulation results, it is found that the proposed schemes are able to enhance the system performance, even in the presence of the estimation errors.

scholarly journals 3D Deployment of Unmanned Aerial Vehicle-Base Station Assisting Ground-Base Station

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Khaled F. Hayajneh ◽  
Khaled Bani-Hani ◽  
Hazim Shakhatreh ◽  
Muhammad Anan ◽  
Ahmad Sawalmeh
Keyword(s):  
Base Station ◽  
Path Model ◽  
Base Stations ◽  
Three Dimension ◽  
Available Bandwidth ◽  
Special Event ◽  
Proposed Model ◽  
Aerial Vehicle ◽  
The Impact

Unmanned aerial vehicles (UAVs), also named as drones, have become a modern model to provide a quick wireless communication infrastructure. They have been used when conventional base stations’ capacity is suffering in some extreme cases such as congestion inside the cell or a special event. This paper proposes an efficient three-dimension (3D) placement of a single UAV-assisted wireless network in such cases. Our proposed model assists the ground base station (GBS) using the UAV to serve arbitrary distributed users considering the impact of the obstacle blockage over the well-known air-to-ground (A2G) path model. This work is aimed at optimizing the percentage of available bandwidth that must be provided to the UAV in order to maximize the number of served users. In addition, it finds the 3D placement of the UAV base station (UAVBS) that maximizes the number of served users, each with maximum quality-of-service (QoS). The exhaustive search and particle swarm optimization (PSO) algorithms are used to find the problem’s solution.

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