yusuke1997/dblp-id-title huggingface dataset:
A Robust Bias Reduction Method with Geometric Constraint for TDOA-Based Localization
CLACK: Cross-layer ACK-Aided Opportunistic Transmission in Wireless Networks
A PDF/PMF Function Based Frequency Allocation Scheme in Fractional Frequency Reuse Aided OFDMA Networks
Detection and Isolation of Selfish Nodes in MANET Using Collaborative Contact-Based Watchdog with Chimp-AODV
Wireless COVID-19 Telehealth: Leukocytes Encryption Guided by Amino Acid Matrix
Cognitive Bidirectional Buffer-Aided DF Relay Networks: Protocol design and Power Allocation
Evaluation of Clustering Algorithms in Ad Hoc Mobile Networks
On the Error Performance of M-ary Modulation Schemes on Rician-Nakagami Fading Channels
Design and Enactment of Diverse Low Power Techniques Based Schmitt Trigger
Performance of antenna diversity multiuser receivers in CDMA channels with imperfect fading estimation
Interference Cancellation with Space Diversity for Downlink MC-CDMA Systems
Cloud System for User-Customized Mobile Interface Sharing in Wireless Environment
Certificateless based Quantum Cryptosystem for Ad-Hoc UWB-IR
Physical Layer Security of Non Orthogonal Multiple Access Using Reconfigurable Intelligent Surfaces
Robust Transmit Antenna Selection with Phase Feedback Over Correlated Fading Channels
A Cat-Shaped Patch Antenna for Future Super Wideband Wireless Microwave Applications
Correction to: EEG Signal Based Human Emotion Recognition Brain-computer Interface using Deep Learning and High-Performance Computing
Development of a Reconfigurable and Miniaturized CPW Antenna for Selective and Wideband Communication
Pulmonary Diffuse Airspace Opacities Diagnosis from Chest X-Ray Images Using Deep Convolutional Neural Networks Fine-Tuned by Whale Optimizer
Development of a Smart Application for Indoor Navigation (INMaps)
Alignment of Heterogeneous Packet Lengths for Random Access in 5G Massive Machine Type Communication
Enhancing the Quantum Communication Channel Using a Novel Quantum Binary Salt Blowfish Strategy
Mobile Tracking in Mixed Line-of-Sight/Non-Line-of-Sight Conditions: Algorithm and Theoretical Lower Bound
A Novel Human Computer Interaction Aware Algorithm to Minimize Energy Consumption
Security Performance of Underlay Cognitive Relaying Networks with Energy Harvesting
Adaptive Power Allocation for Maximizing the Sum Rate of Multiple Interfering Links Under Minimum Rate Constraints
FDRF: Fault Detection and Recovery Framework for Seamless Data Transmission in Remote Health Monitoring Using WBAN
Priority Aware and Spectrum Efficient Scheduling of Co-existing Wireless Body Area Networks
W-CDMA Uplink Capacity and Interference Statistics of a Long Tunnel Cigar-shaped Microcells Using the Hybrid Model of Propagation with Imperfect Power Control
Energy-Efficient and Improved eWALL: e2WALL
Novel Generalized max* Approximation Method for Simplified Decoding of Turbo and TTCM Codes
Measurement and Statistical Analysis of the Temporal Variations of a Fixed Wireless Link at 3.5 GHz
Correction to: Fishbone Diagram: Application to Identify the Root Causes of Student-Staff Problems in Technical Education
Two-Element Quad-Band MIMO Antenna Employing Meandered Arm Printed Inverted-F Antenna
Performance of MMSE Receiver Based CDMA System with Higher Order Modulation Formats in a Fading Channel
Filter-Bank Modulation Based Signal Design and Transmission Techniques for Intensity Modulated MIMO Visible Light Communication Systems
A Provably Secure and Lightweight Patient-Healthcare Authentication Protocol in Wireless Body Area Networks
Design and Beamforming Performance of the Compact ESPAR Antenna for the Beam Space MIMO System
Symbol Timing Synchronization Using Interpolation-Based Matched-Filters
BTSDN: BGP-Based Transition for the Existing Networks to SDN
Radio Wave Attenuation due to Clouds from Traditional Models to ML Models - A State of Art
Enhancing the Error Performance of 5G New Radio Using Hierarchical and Statistical QAM
Erratum to: Cooperative Communication Protocols in Wireless Networks: Performance Analysis and Optimum Power Allocation
Meta-heuristic Ant Colony Optimization Based Unequal Clustering for Wireless Sensor Network
Analysis of a Combined Parameter-Based Multi-objective Model for Performance Improvement in Wireless Networks
Internet of Vehicles Communication Technologies for Traffic Management and Road Safety Applications
Demystifying Cognitive Informatics and its Applications in Brain-Computer Interface
A taxonomy of ubiquitous computing applications
Absorption Enhancement of GaAs Thin-Film Solar Cells Using Tapered Metal Nanoantenna Structures
A Strategic Framework for Searching Mobile Targets Using Mobile Sensors
AI and ML Powered IoT Applications for Energy Management in Electric Vehicles
A Comprehensive Survey of Various Approaches on Human Fall Detection for Elderly People
Alamouti-Based Space-Frequency Coding for OFDM
PCB Planar and Filamentary Planar Spiral Coils based Underground Magnetic Induction Communication with Enhanced Channel Model
Dynamic Range Normal Bisector Localization Algorithm for Wireless Sensor Networks
Sequential Decoding of Convolutional Codes for Rayleigh Fading Channels
Optimal Energy Efficiency Distributed Relay Decision in UAV Swarms
Hybrid Gradient Descent Golden Eagle Optimization (HGDGEO) Algorithm-Based Efficient Heterogeneous Resource Scheduling for Big Data Processing on Clouds
Performance of receive diversity and LMMSE chip equalization in WCDMA HSDPA network
Improving Positioning Accuracy Using Optimization Approaches: A Survey, Research Challenges and Future Perspectives
Some New Expressions for Nakagami Fading Based on Order Statistics
Introduction to Special Issue "Intelligent Telecommunication Infrastructures and Beyond"
Design and Implementation of an Inclusive Ubiquitous Access
Compact and Hexaband Rectangular Microstrip Patch Antenna for Wireless Applications
Device Discovery Signal Design for Proximal Devices in D2D Communication
Bio-inspired Patrolling Scheme Design in Wireless and Mobile Sensor and Robot Networks
Adaptive Generator Sequence Selection in Multilevel Space-Time Trellis Codes
Enhanced WSN Routing Protocol for Internet of Things to Process Multimedia Big Data
Analyzing Throughput of MANET with Reduced Packet Loss
Analysis and Implementation of High Performance Reconfigurable Finite Impulse Response Filter Using Distributed Arithmetic
Full Duplex DD for In-Band D2D Communication
RTDGPS Accuracy Improvement Using PSO-LSWSVM and Low-Cost GPS Receivers
Retraction Note: Encrypted Network Traffic Classification and Resource Allocation with Deep Learning in Software Defined Network
Memory Forwarding Algorithm in Multiple Communities Delay Tolerant Networks
Beamspace MIMO System Using Chaos BPSK Modulation
Design and Analysis of Multiband Antenna for Wireless Communication
Reliable Routing Algorithm Based on Clustering and Mobile Sink in Wireless Sensor Networks
Design and Analysis of UWB Filter with Single Notch Band
Performance Evaluation of Cost-Effective Multicast-Unicast Key Management Method
Exact Outage Probability Analysis of a Dual-Hop Cognitive Relaying Network Under the Overhearing of an Active Eavesdropper
A Coding Theory Based Ultralightweight RFID Authentication Protocol with CRC
Design of Compact Dual Wideband Bandpass Filter Based on Transversal Signal Interaction Concepts
A channelized digital receiver design for UWB systems in a multi-path indoor environment
A Novel Spectrum Sensing Method Based on Tri-Stable Stochastic Resonance and Quantum Particle Swarm Optimization
A Noble UWB Array with Band Notch Characteristics
A Decorrelating-MRC Based Space-Time Multiuser Receiver for Time-Hopping UWB System
PAPR Reduction in VLC-OFDM System Using a Combination of Shuffled Frog Leaping Algorithm and Hill-Climbing Algorithm
Verification of OFDM Error Floor Prediction in Time-Dispersive LTE FDD DL Channel
Performance Analysis of Location Based Smart Catastrophe Monitoring System Using WSN
Time Synchronization for Cooperative Communication in Wireless Sensor Networks
Hybrid Beamforming in Large-scale Antenna Array for 5G Indoor Communication Network Deployments
Performance Enhancement of Fast Handover for MIPv6 by Reducing Out-of-Sequence Packets
A Novel Chaotic Maps-Based User Authentication and Key Agreement Protocol for Multi-server Environments with Provable Security
High Altitude Platform Station (HAPS): A Review of New Infrastructure Development for Future Wireless Communications
Design and Validation of Android Based Wireless Integrated Device for Ubiquitous Health Monitoring
Broadband Stacked Microstrip Antennas with Different Radiating Patch
Machine Learning-Based PHY-Authentication Without Prior Attacker Information for Wireless Multiple Access Channels
Monitoring, Control and Energy Management of Smart Grid System via WSN Technology Through SCADA Applications
Differentially Coherent Blind Adaptive Receiver for Rayleigh Fading CDMA Channels
Two Phased Routing Protocol Incorporating Distributed Genetic Algorithm and Gradient Based Heuristic in Clustered WSN
Multi-Hop Cooperative Communication Technique for Cognitive DF and AF Relay Networks
Safety Evaluation of Construction Based on the Improved AHP-Grey Model
Optimizing Relay Selection in D2D Communication for Next-Generation Wireless Networks Using Multi-Agent Reinforcement Learning: A Novel Approach
Performance Analysis Over Unified Generalized Composite Fading Model
A Multi-objective Disjoint Set Covers for Reliable Lifetime Maximization of Wireless Sensor Networks
Enabling LTE Services Under Interference from Mobile Satellite Service System
Cognitive Radio Concept and Challenges in Dynamic Spectrum Access for the Future Generation Wireless Communication Systems
Review of Deep Learning Techniques for Neurological Disorders Detection
Adaptive Modulation and Coding for Performance Enhancement of Vehicular Communication
Modifying Polyphase Codes to Mitigate Range Side-lobes in Pulse Compression Radar
A GMSK Receiver with Beamformer Weight Refinement
Improved Performance of Maximum Likelihood Decoding Algorithm with Efficient Use of Algebraic Decoder
An Ant-based Multipath Routing Algorithm for QoS Aware Mobile Ad-hoc Networks
Sigma-Delta Modulation Based Adaptive Channel Equalizer Based on Wiener-Hopf Equations
GSHMAC: Green and Secure Hybrid Medium Access Control for Wireless Sensor Network
Characteristics of Channels of IEEE 802.15.4 Compliant Sensor Networks
An Enhanced Multi-target Multi-Bernoulli Particle Filtering for Direction of Arrival Tracking in the Presence of Impulsive Noise
Modified Design and Analysis of a CMOS LNA for Wireless Sensor Network Applications
Capacity analysis of MIMO MRC systems in correlated rayleigh fading environments
Transmit Antenna Selection in the Alamouti-Coded MIMO Relay Systems
Analytical Evaluation of Directional-Location Aided Routing Protocol for VANETs
Combination of Fitness-Mated Lion Algorithm with Neural Network for Optimal Query Ordering Data Aggregation Model in WSN
An Intelligent Session Key-Based Hybrid Lightweight Image Encryption Algorithm Using Logistic-Tent Map and Crossover Operator for Internet of Multimedia Things
The Enriched Feature Enhancement Technique for Satellite Image Based on Transforms Using PCNN
A Comparative Analysis of Machine and Deep Learning Techniques for EEG Evoked Emotion Classification
Design and Optimization of Wideband Microwave Amplifier Using Nonlinear Technique
Jamming for Securing NOMA with Energy Harvesting: Performance Analysis
An Analytical Model for LoS Probability and Area Transport Efficiency of Millimeter Wave Cellular Network
Concentric Circular Arrays for Stratospheric High-Altitude Platforms Wireless Sensor Networks
Dynamic Power Control and Scheduling in Full Duplex Cellular Network with D2D
Design of Sierpinski Knopp Inspired Fractal Antenna for Public Safety Applications
Reinforcement Learning Based on Contextual Bandits for Personalized Online Learning Recommendation Systems
Visible Light Communications (VLC) for Ambient Assisted Living
A Simple Analytical Model for Expected Frame Waiting Time Evaluation in IEEE 802.11e HCCA Mode
Enhancing Smart Home Security Using Deep Convolutional Neural Networks and Multiple Cameras
A Novel SVM Based IDS for Distributed Denial of Sleep Strike in Wireless Sensor Networks
A Target Position Decision Algorithm Based on Analysis of Path Departure for an Autonomous Path Keeping System
FBDR-Fuzzy Based DDoS Attack Detection and Recovery Mechanism for Wireless Sensor Networks
Two Energy Harvesting Protocols for SWIPT at UAVs in Cooperative Relaying Networks of IoT Systems
Midhaul Performance Modelling Using Commodity Hardware C-RAN Testbed
Spectral Efficiency Analysis and Optimization in Hybrid RIS Systems Under Nonlinear Power Amplifier Effects
Spectrum Allocation for Enhanced Cross-Tier Interference Mitigation with Throughput Improvement for Femtocells in a Heterogeneous LTE Cellular Network
Swarm and Fuzzy Based Cooperative Caching Framework to Optimize Energy Consumption Over Multimedia Wireless Sensor Networks
On Optimal Threshold Selection in Cooperative Spectrum Sensing for Cognitive Radio Networks: An Energy Detection Approach Using Fuzzy Entropy Maximization
UWB Transmission and MIMO Antenna Systems for Nomadic Users and Mobile PANs
A Study on Characteristics of MSAV Based on SAL-F Algorithm
Secrecy Outage Probability and Strictly Positive Secrecy Capacity of Cognitive Radio Networks with Adaptive Transmit Power
A New Range-Free and Storage-Efficient Localization Algorithm Using Neural Networks in Wireless Sensor Networks
The Optimal Spectrum Sensing Time for Maximizing Throughput of 802.11-Based MAC Protocol for Cognitive Radio Networks Under Unsaturated Traffic Conditions
Low Complexity Maximum Likelihood FBMC QAM for Improved Performance in Longer Delay Channels
UAV Assisted SWIPT Enabled NOMA Based D2D Network for Disaster Management
DE-BAR: Device Energy-Centric Backlight and Adaptive Region of Interest Mechanism for Wireless Mobile Devices
Substrate Integrated Isosceles Trapezoid with Extended Ground Antenna for X-band Applications
Minimizing End-to-End Delay on Real-Time Applications
The Intelligent Street Light Control System for Preventing Heavy Fog of Expressway Based on ZigBee
Fast One-Bit Feedback Beamforming Algorithms with Stage-Threshold Mechanism
Differential Game for Distributed Power Control in Device-to-Device Communications Underlaying Cellular Networks
Trust Based DoS Attack Detection in Wireless Sensor Networks for Reliable Data Transmission
Effect and Compensation of Colored Timing Jitter in Pulsed UWB Systems
Performance Analysis of the Cooperative ZP-OFDM: Diversity, Capacity and Complexity
A Low Complexity Near Optimal Signal Detection for Large Scale MIMO SC-FDMA Uplink System
2D Pose-Invariant Face Recognition Using Single Frontal-View Face Database
Distributed Discrete Power Control in Cellular PCS
Game Theoretic Resource Allocation for D2D MIMO Heterogenous Networks
Connectivity-Preserved and Force-Based Deployment Scheme for Mobile Sensor Network
Joint Precoder and Decoder for MIMO Dual-Hop Relay Systems in Delay Spread Channels
Dynamic Authentication Protocol Using Multiple Signatures
Digital Joint Equivalent Channel Hybrid Precoding for Millimeter Wave Massive MIMO Systems
Design and Implementation of Smart IoT System Based Bidirectional Converter
Video Face Detection Based on Deep Learning
Multipath Diversity for OFDM Based Visible Light Communication Systems Through Fractional Sampling
Building an Adaptive Cooperative Transmission Mechanism for Multimedia Convergence System
5G Based on Cognitive Radio
Bandwidth and Gain Enhancement of Rectangular Microstrip Patch Antenna (RMPA) Using Slotted Array Technique
Towards the Functional Enhancement of 3GPP Networks with Reconfiguration Capacities
An Efficient FrWT and IPCA Tools for an Automated Healthcare CAD System
Experimental Evaluation of HOA in Terms of Flat Gain in C-Band for Super Dense Optical Communication System
Network Control System (NCS) for Performance Improvement of Dual Converter Power Supply System Using Adaptive Inverse Dynamic Mode (AIDMC) Control Technique
Implementing Billing as a Service by an IPDR Aggregator System
Reverse Link Performance of DS-CDMA Cellular Systems through Closed-Loop Power Control, Base Station Assignment, and Antenna Arrays in 2D Urban Environment
An Adaptive Lossly Quantization Technique for Key Extraction Applied in Vehicular Communication
Decision Making in the Battlefield-of-Things
Prioritized New Call Threshold Policy for Wireless Cellular Networks
Self Clock-Gating Scheme for Low Power Basic Logic Element Architecture
A New Method to Enhance SC-FDMA Communication with Channel Estimation Errors
Cache-Aware Network Coding-Based Scheduling for SVC Multicast in Wireless Networks with Hard Deadline Constraints
A Comprehensive Review on Device-to-Device Communication Paradigm: Trends, Challenges and Applications
Investigations on the Design of Compact Flexible Wearable Fractal Patch Antenna for Body Area Networks Applications
RDAD: An Efficient Distributed Multi-Layered Resource Handler in Jungle Computing
A Joint CAC and Dynamic Bandwidth Allocation Technique for Capacity and QoS Analysis in Heterogeneous LTE based BWA Network: Few Case Studies
Detection, Localization and Analysis of Oil Spills in Water Through Wireless Thermal Imaging and Spectrometer Based Intelligent System
Energy Efficiency for Underlay Cognitive Multiuser Two-Way Relay Networks
GCCR: An Efficient Grid Based Clustering and Combinational Routing in Wireless Sensor Networks
A Novel Cognitive Method for Throughput Improvement of Mobile Multi-hop Ad Hoc Networks
A Study on Basketball Techniques and Tactics Based on Apriori Algorithm
Communication Void Free Routing Protocol in Wireless Sensor Network
Hybrid NOMA for Future Radio Access: Design, Potentials and Limitations
An Uplink Short-Term Fading Prediction-Based Power Control Method for DS/CDMA Cellular Radio Systems
Participant Density-Independent Location Privacy Protection for Data Aggregation in Mobile Crowd-Sensing
An Improved DV-Hop Scheme Based on Path Matching and Particle Swarm Optimization Algorithm
Design of FPGA Soft Core Based WSN Node Using Customization Paradigm
A Threshold-Free LLR-Based Scheme to Minimize the BER for Decode-and-Forward Relaying
Design and Simulation of an Efficient Image Communication Scheme Via DS-CDMA
Carrier Frequency Offset (CFO) Synchronization and Peak Average Power Ratio (PAPR) Minimization for Energy Efficient Cognitive Radio Network (CRN) for 5G Wireless Communication
Spatial-DoF Improvement of MIMO Cognitive Network Through Interference Fusion in Conjunction with Alignment
Integration of Prediction Based Hybrid Compression in Distributed Sensor Network
Review of the Techniques Against the Wormhole Attacks on Wireless Sensor Networks
User Authentication Algorithm Guaranteeing Reusability of Biometric Data in BioPKI System
A Survey of QoS-aware Routing Protocols for the MANET-WSN Convergence Scenarios in IoT Networks
Performance Evaluation of IEEE 802.15.4 Sensor Chains in an Integrated Water Monitoring Framework
Secure Persuasive Business Models and Business Model Innovation in a World of 5G
Optimised Complex Constellations for Transmitter Diversity
Improved Method of Direction Finding for Non Circular Signals with Wavelet Denoising Using Three Parallel Uniform Linear Arrays
Energy Efficient and Delay Aware Optimization Reverse Routing Strategy for Forecasting Link Quality in Wireless Sensor Networks
Blockchain Assisted Disease Identification of COVID-19 Patients with the Help of IDA-DNN Classifier
Reliable TOA and TDOA Location Estimation Under Multipath Fading Channel Conditions in Wideband Wireless Networks for Indoor Factory Applications
A Pragmatic Business Approach to a Novel C5 Concept ATMAN
The Cooperative-Communication Based Underwater Layered Routing Protocol for Underwater Wireless Sensor Network
Lessons from SmartCampus: External Experimenting with User-Centric Internet-of-Things Testbed
On the Performance of TETRA Short Data Service-Transport Layer
Design of V-Cut Patch MIMO Antenna for the 5.4 GHz Band
Design of Wideband Flower-Shaped Microstrip Patch Antenna for Portable Applications
Pre-equalization Schemes for MIMO CC-CDMA Systems Over Frequency-Selective Fading Channels
Design of Compact Hybrid Branch Line Coupler (BLC) for GSM Application
An Accurate Indoor RSSI Localization Algorithm Based on Active RFID System with Reference Tags
Traditional and Blockchain Based IoT and IIoT Security in the Context of Agriculture: A Survey
Measurements at 2.4, 3.4, 5.2, 28 and 60 GHz for Device-to-Device Wireless Communications
Message Scheduling for Personal Biomedical Sensing System in a Health Care Center
Location-Free Void Avoidance Routing Protocol for Underwater Acoustic Sensor Networks
Securing E-health Networks from Counterfeit Medicine Penetration Using Blockchain
On the Use of Okumura-Hata Propagation Model on Railway Communications
Improved Turbo Decoding Using Soft Combining Principle
A Novel Multi-carrier Order Division Multi-access Communication System Based on TDCS with Fractional Fourier Transform Scheme
Fast and Secure Handover Authentication Scheme Based on Ticket for WiMAX and WiFi Heterogeneous Networks
Analysis of the CFO Successive Interference Cancellation for the OFDMA Uplink
Application of AHP for Ranking of Total Productive Maintenance Pillars
Distributed User Association with Resource Partitioning in Heterogeneous Cellular Networks
Secrecy Enhancement in AF Relaying Assisted SWIPT-NOMA via Power Optimization and Control-Jamming
Efficient Online Lecture Platform: Design and Implementation of Optimized Temporal Masking Technique for Compressed Video Streaming
A Conceptual Design of Job Pre-processing Flow for Heterogeneous Batch Systems in Data Center
Multi Parameter Based Robust and Efficient Rogue AP Detection Approach
Dynamic Channel Assignment with Flexible Reuse Partitioning in Cellular Systems
Correction to: Deep Neural Network Routing with Dynamic Space Division for 3D UAV FANETs
Performance of phase-shift keying communication systems with partial fading channel statistical information
1-0-1 Cascaded Sigma-Delta Modulator with Internal Feedback
Dual Band-Notched Small Monopole Antenna with Enhanced Bandwidth for UWB Applications
Joint Resource Allocation of UAV Aided Communication System Based on Multi-coding Artificial Bee Colony Algorithm
Design of 5-bit Flash ADC Using 180 nm Technology for Medical Applications
SPIS: Signal Processing for Integrated Sensing Technologies Using 6G Networks with Machine Learning Algorithms
WECRR: Weighted Energy-Efficient Clustering with Robust Routing for Wireless Sensor Networks
A Novel AEB-AODV Based AADITHYA Cross Layer Design Hibernation Algorithm for Energy Optimization in WSN
A Three-Party Dynamic Identity-Based Authenticated Key Exchange Protocol with Forward Anonymity
Distributed Joint Rate Control, Resource Allocation, and Congestion Control for Throughput Optimization in Multirate Multiradio Multichannel Wireless Network with Intersession/Intrasession Network Coding
Metaheuristic Channel Assignment in DVB-T Networks in Conformity with Digital Dividend Requirements
GSMAC: Group-Scheduled MAC Protocol with Energy Beamforming in M2M Networks
On a Speech Multiple System Implementation for Speech Synthesis
Energy Efficient Static Node Selection in Underwater Acoustic Wireless Sensor Network
Embedding the MRC and SC Schemes into Trust Management Algorithm Applied to IoT Security Protection
Wireless Distributive Personal Communication for Early Detection of Collateral Cancer Using Optimized Machine Learning Methodology
Defeating the Eavesdropper: On the Achievable Secrecy Capacity Using Reconfigurable Antennas
Impact of Random Packet Arrival on the Performance of Video Streaming over OFDMA Downlink Systems
Always Best Connected Heterogeneous Network Concept
Development of a Web Dictionary System Using SOFL
Design and Simulation of a Broadband Bandpass Filter Based on Complementary Split Ring Resonator Circular "CSRRs"
Nonconvex Optimization for Power Control in Wireless CDMA Networks
Enhancement of the Dynamic Computation-Offloading Service Selection Framework in Mobile Cloud Environment
Analytical Model of Deployment Methods for Application of Sensors in Non-hostile Environment