This document summarizes key points from a lecture on TCP over wireless networks and mobility. It discusses how mobility can impact the protocol stack and cause packet loss. It then describes TCP basics like congestion control and retransmissions. It explains challenges like burst errors and random errors in wireless causing unnecessary timeouts or fast retransmits. It presents several approaches to adapt TCP for wireless like link layer mechanisms, split connection, snoop protocol, and delayed ACKs. It also discusses issues like handoffs causing packet loss and proposals like fast retransmit and FreezeTCP to handle disconnections due to mobility.
This document provides an agenda and overview of topics related to the transport layer and networking essentials. The agenda includes discussions of the transport layer, UDP overview, TCP communication process, the socket API, and tools and utilities. Specific topics that will be covered include the role and functions of the transport layer, UDP features and headers, TCP reliability mechanisms like connection establishment and termination, sequence numbers and acknowledgments, window sliding, and data loss/retransmission. The document also provides brief overviews and usage examples for common networking tools like ifconfig, nmcli, route, ping, traceroute, netstat, dig, ncat, nmap, tcpdump, and wireshark.
This document outlines the transport layer and its goals and protocols. It discusses how the transport layer provides logical communication between application processes running on different hosts. It describes the two main Internet transport protocols: UDP, which provides connectionless and unreliable data transfer, and TCP, which provides connection-oriented and reliable data transfer. TCP also implements congestion control. The document then discusses in more detail the principles of reliable data transfer, including error detection, acknowledgments, negative acknowledgments, and retransmissions. It presents finite state machine models for simple and more advanced reliable data transfer protocols to handle bit errors and lost packets over an unreliable channel.
UDP is a transport layer protocol that provides an unreliable datagram service. It is positioned directly above IP in the TCP/IP protocol stack. UDP packets contain a header with source and destination port numbers as well as length fields, but do not establish connections, provide sequencing, or guarantee delivery like TCP. Well-known ports are assigned to common UDP applications like DNS, time synchronization, and trivial file transfer.
The document provides an overview of network infrastructure components including networking hardware, software, and services. It then discusses several key network protocols including TCP, IP, routing protocols, and DNS. It provides details on the OSI model and describes each layer including typical functions, protocols, and vulnerabilities. For TCP and IP, it outlines the basic operation including packet formatting, connection establishment, flow control, congestion control, and error handling.
The document summarizes Chapter 6 of Andrew S. Tanenbaum's book "Computer Networks", which discusses the transport layer. It focuses on the User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP), the two main transport protocols used in the Internet. UDP is a connectionless protocol that provides basic data transport, while TCP provides reliable, sequenced delivery of data streams through the use of connections, flow control, error control, and retransmissions. Real-time applications often use UDP, while most Internet applications require the reliability of TCP.
The document provides an agenda and lesson plan for a networking class. It includes:
- An agenda with various activities lasting 5-20 minutes each, including warm ups, videos, teacher demonstrations, and reflections.
- Classroom norms on taking notes and being prepared for quizzes.
- An essential question on the TCP/IP protocol and links to online and offline content on networking topics like TCP/IP, ports, DHCP, and IP addressing.
- Information on IP addressing including address classes, subnets, subnet masks, and examples of IP address allocation.
- Suggestions for further information on TCP/IP topics.
This document discusses the Transmission Control Protocol (TCP) which provides reliable, connection-oriented data transmission over the internet. TCP establishes a virtual connection between endpoints, ensuring reliable delivery through mechanisms like positive acknowledgement and retransmission. It uses a sliding window algorithm to guarantee reliable and in-order delivery while enforcing flow control between sender and receiver. Key aspects of TCP include connection establishment and termination, port numbers, segments, headers, and addressing end-to-end issues over heterogeneous networks.
This document provides an agenda and overview of topics related to the transport layer and networking essentials. The agenda includes discussions of the transport layer, UDP overview, TCP communication process, the socket API, and tools and utilities. Specific topics that will be covered include the role and functions of the transport layer, UDP features and headers, TCP reliability mechanisms like connection establishment and termination, sequence numbers and acknowledgments, window sliding, and data loss/retransmission. The document also provides brief overviews and usage examples for common networking tools like ifconfig, nmcli, route, ping, traceroute, netstat, dig, ncat, nmap, tcpdump, and wireshark.
This document outlines the transport layer and its goals and protocols. It discusses how the transport layer provides logical communication between application processes running on different hosts. It describes the two main Internet transport protocols: UDP, which provides connectionless and unreliable data transfer, and TCP, which provides connection-oriented and reliable data transfer. TCP also implements congestion control. The document then discusses in more detail the principles of reliable data transfer, including error detection, acknowledgments, negative acknowledgments, and retransmissions. It presents finite state machine models for simple and more advanced reliable data transfer protocols to handle bit errors and lost packets over an unreliable channel.
UDP is a transport layer protocol that provides an unreliable datagram service. It is positioned directly above IP in the TCP/IP protocol stack. UDP packets contain a header with source and destination port numbers as well as length fields, but do not establish connections, provide sequencing, or guarantee delivery like TCP. Well-known ports are assigned to common UDP applications like DNS, time synchronization, and trivial file transfer.
The document provides an overview of network infrastructure components including networking hardware, software, and services. It then discusses several key network protocols including TCP, IP, routing protocols, and DNS. It provides details on the OSI model and describes each layer including typical functions, protocols, and vulnerabilities. For TCP and IP, it outlines the basic operation including packet formatting, connection establishment, flow control, congestion control, and error handling.
The document summarizes Chapter 6 of Andrew S. Tanenbaum's book "Computer Networks", which discusses the transport layer. It focuses on the User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP), the two main transport protocols used in the Internet. UDP is a connectionless protocol that provides basic data transport, while TCP provides reliable, sequenced delivery of data streams through the use of connections, flow control, error control, and retransmissions. Real-time applications often use UDP, while most Internet applications require the reliability of TCP.
The document provides an agenda and lesson plan for a networking class. It includes:
- An agenda with various activities lasting 5-20 minutes each, including warm ups, videos, teacher demonstrations, and reflections.
- Classroom norms on taking notes and being prepared for quizzes.
- An essential question on the TCP/IP protocol and links to online and offline content on networking topics like TCP/IP, ports, DHCP, and IP addressing.
- Information on IP addressing including address classes, subnets, subnet masks, and examples of IP address allocation.
- Suggestions for further information on TCP/IP topics.
This document discusses the Transmission Control Protocol (TCP) which provides reliable, connection-oriented data transmission over the internet. TCP establishes a virtual connection between endpoints, ensuring reliable delivery through mechanisms like positive acknowledgement and retransmission. It uses a sliding window algorithm to guarantee reliable and in-order delivery while enforcing flow control between sender and receiver. Key aspects of TCP include connection establishment and termination, port numbers, segments, headers, and addressing end-to-end issues over heterogeneous networks.
Computer networks Module 3 Transport layerclaudle200415
The document discusses the transport layer and provides an overview of key concepts. It introduces transport layer services including multiplexing, demultiplexing, and reliable data transfer. It describes the two main Internet transport protocols - UDP which provides connectionless unreliable data transfer, and TCP which provides connection-oriented reliable transfer. The document outlines the concepts that will be covered in more detail, including multiplexing, demultiplexing, the transport protocols UDP and TCP, and congestion control.
The document discusses various concepts related to understanding router throughput, including:
- Throughput is a measure of how much data a system can process in a given time period. For routers, it refers to successfully transferred data.
- Wire speed refers to the maximum possible data transfer rate of a physical connection like Ethernet.
- Factors like packet headers, gaps between packets, and protocol overhead mean the theoretical maximum throughput is typically not achievable.
- Tools like speedtest.net aim to measure "real" throughput by accounting for these factors and using techniques like multi-threaded transfers.
- Features in RouterOS like FastPath and FastTrack can help optimize routing performance by reducing unnecessary processing for some traffic.
Slides supporting the "Computer Networking: Principles, Protocols and Practice" ebook. The slides can be freely reused to teach an undergraduate computer networking class using the open-source ebook.
This document provides information about MobileComm Technologies' drive test process for UMTS networks. It includes documentation on tools used for tuning and optimization, parameters measured, call flows, key performance indicators, examples of coverage and interference issues identified, and tips for network tuning. The document contains 47 slides covering topics like coverage verification using P-CPICH measurements, identifying interference and overshooting issues, analyzing call drops, tuning for voice and data calls, and comparing mechanical vs electrical antenna tilts.
The document discusses the differences between packets and frames, and provides details on the transport layer. It explains that the transport layer is responsible for process-to-process delivery and uses port numbers for addressing. Connection-oriented protocols like TCP use three-way handshaking for connection establishment and termination, and implement flow and error control using mechanisms like sliding windows. Connectionless protocols like UDP are simpler but unreliable, treating each packet independently.
High performance browser networking ch1,2,3Seung-Bum Lee
Presentation material including summary of "High Performance Browser Networking" by Ilya Grigorik. This book includes very good summary of computer network not only for internet browsing but also multimedia streaming.
Dccp evaluation for sip signaling ict4 m Agus Awaludin
This document discusses evaluating the performance of using the Datagram Congestion Control Protocol (DCCP) for SIP signaling compared to the traditional UDP. It describes developing a DCCP agent and SIP traffic for the NS-2 network simulator to simulate SIP call setup over DCCP and UDP. The simulation results show that DCCP has lower call drop rates than UDP and less variation in call setup delays, indicating DCCP may be a preferable transport for SIP signaling over UDP.
This document discusses a computer networks course taught by Dr. Shivashankar at RRIT. The course aims to help students understand networking concepts and protocols. It covers topics like network architectures, protocols at different layers, and basic network configurations. The document provides details of transport layer protocols like TCP and UDP, explaining their services, operation mechanisms, and applications.
This paper proposes Core-Stateless Fair Queueing (CSFQ), a scheme that achieves approximately fair bandwidth allocation across high-speed networks without per-flow state in core routers. CSFQ decomposes routers into edge and core roles, with edge routers maintaining per-flow state to estimate rates and label packets, while core routers use these labels and estimated fair rates to probabilistically drop packets. Evaluation shows CSFQ provides fairness comparable to other schemes like FRED while significantly reducing complexity for core routers.
The document discusses flow control in TCP. It explains that TCP uses a sliding window mechanism for flow control to balance the sender's transmission rate with the receiver's reception rate. The sliding window allows packets within the window to be transmitted, and slides to the right when acknowledgments are received, making room for more packets. Problems like delayed acknowledgments, silly window syndrome, and solutions like Nagle's algorithm are also covered. TCP provides reliable data transfer using error control mechanisms like checksums, acknowledgments, and retransmissions of lost packets.
WIRELESS NETWORKS _ BABU M_ unit 3 ,4 & 5 PPT
EC 6802 WIRELESS NETWORKS PPT
POWER POINT PRESENTAION ON WIRELESS NETWORKS
BABU M
ASST PROFESSOR/ ELECTRONICS AND COMMUNICATION ENGINEERING,
RMK COLLEGE OF ENGINEERING AND TECHNOLOGY
CHENNAI, THIRUVALLUR DISTRICT
Get into Networking by Clearing Comptia Network+ Testcertblaster
The document summarizes key aspects of the OSI model, including:
1) The OSI model breaks network communication into 7 layers (physical, data link, network, transport, session, presentation, application) to standardize network components and allow different hardware/software to communicate.
2) Each layer has a specific role like physical addressing (data link), logical addressing (network), and ensuring reliable data transmission (transport).
3) The TCP/IP model is similar to OSI but combines some layers. It uses IP addresses, TCP/UDP, and port numbers to route packets between applications running on devices.
4) Common network devices operate at different layers, with cables and wireless access points at layer 1
This document summarizes vulnerabilities in network protocols like TCP/IP, ARP, IP, TCP, FTP, Telnet, and SMTP. It outlines issues like spoofing, flooding attacks, lack of authentication and encryption. It discusses how protocols work at different layers and security problems associated with each, such as spoofing of addresses, hijacking connections, sniffing cleartext data, and denial of service attacks. Prevention methods are also briefly covered.
Pre-Con Education: Recognizing Your Network's Key Performance Indicators Th...CA Technologies
Understanding key network metrics that impact end-user experience and how to leverage these key performance indicators is imperative for troubleshooting issues and restoring optimal network performance.
In this presentation, you will learn how to establish fundamental metrics for technology communications, gain an understanding of key concepts attributed to communication processes, gain an understanding of network performance metrics that actually impact end users, understand five sources of network latency and learn to use reference models as a troubleshooting tool.
For more information on DevOps solutions from CA Technologies, please visit: http://bit.ly/1wbjjqX
presentationphysicallyer.pdf talked about computer networksHetfieldLee
The document discusses TCP congestion control and the TCP Reno algorithm. It explains how TCP Reno implements additive increase multiplicative decrease (AIMD) using slow start, fast retransmit, and fast recovery to quickly repair single segment losses without requiring a timeout. TCP Reno uses duplicate ACKs to infer segment losses and retransmits the lost segment. It then sets the congestion window to half the original size for multiplicative decrease. This allows TCP to realize AIMD and avoid timeouts after single losses.
The document summarizes mobile ad hoc networks (MANETs) and some of the key challenges in designing protocols for them. It covers medium access control protocols, routing protocols, and some examples. Specifically, it discusses MACA for medium access, reactive routing protocols like DSR, proactive protocols like DSDV, and hybrid protocols like ZRP. It also outlines some of the tradeoffs between proactive and reactive routing approaches for mobile networks.
This document summarizes a tutorial on mobile ad hoc networks. It first discusses the characteristics and challenges of mobile ad hoc networks, including frequent topology changes and limited bandwidth. It then covers various aspects of designing protocols for mobile ad hoc networks, including medium access control, routing, and transport. For medium access control, it describes MACA and IEEE 802.11. For routing, it discusses reactive, proactive, and hybrid routing protocols and the tradeoffs between them. The document provides an overview of key considerations and approaches for building mobile ad hoc network protocols.
Communication over the kinds of Data-Links used for unmanned vehicles presents important challenges dues to the low bandwidth, intermittent, and lower reliability of these links. Classic network protocols such as TCP do not operate well in this environment forcing application developers to implement their own reliability and session management. This presentation describes he issues and alternatives.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Computer networks Module 3 Transport layerclaudle200415
The document discusses the transport layer and provides an overview of key concepts. It introduces transport layer services including multiplexing, demultiplexing, and reliable data transfer. It describes the two main Internet transport protocols - UDP which provides connectionless unreliable data transfer, and TCP which provides connection-oriented reliable transfer. The document outlines the concepts that will be covered in more detail, including multiplexing, demultiplexing, the transport protocols UDP and TCP, and congestion control.
The document discusses various concepts related to understanding router throughput, including:
- Throughput is a measure of how much data a system can process in a given time period. For routers, it refers to successfully transferred data.
- Wire speed refers to the maximum possible data transfer rate of a physical connection like Ethernet.
- Factors like packet headers, gaps between packets, and protocol overhead mean the theoretical maximum throughput is typically not achievable.
- Tools like speedtest.net aim to measure "real" throughput by accounting for these factors and using techniques like multi-threaded transfers.
- Features in RouterOS like FastPath and FastTrack can help optimize routing performance by reducing unnecessary processing for some traffic.
Slides supporting the "Computer Networking: Principles, Protocols and Practice" ebook. The slides can be freely reused to teach an undergraduate computer networking class using the open-source ebook.
This document provides information about MobileComm Technologies' drive test process for UMTS networks. It includes documentation on tools used for tuning and optimization, parameters measured, call flows, key performance indicators, examples of coverage and interference issues identified, and tips for network tuning. The document contains 47 slides covering topics like coverage verification using P-CPICH measurements, identifying interference and overshooting issues, analyzing call drops, tuning for voice and data calls, and comparing mechanical vs electrical antenna tilts.
The document discusses the differences between packets and frames, and provides details on the transport layer. It explains that the transport layer is responsible for process-to-process delivery and uses port numbers for addressing. Connection-oriented protocols like TCP use three-way handshaking for connection establishment and termination, and implement flow and error control using mechanisms like sliding windows. Connectionless protocols like UDP are simpler but unreliable, treating each packet independently.
High performance browser networking ch1,2,3Seung-Bum Lee
Presentation material including summary of "High Performance Browser Networking" by Ilya Grigorik. This book includes very good summary of computer network not only for internet browsing but also multimedia streaming.
Dccp evaluation for sip signaling ict4 m Agus Awaludin
This document discusses evaluating the performance of using the Datagram Congestion Control Protocol (DCCP) for SIP signaling compared to the traditional UDP. It describes developing a DCCP agent and SIP traffic for the NS-2 network simulator to simulate SIP call setup over DCCP and UDP. The simulation results show that DCCP has lower call drop rates than UDP and less variation in call setup delays, indicating DCCP may be a preferable transport for SIP signaling over UDP.
This document discusses a computer networks course taught by Dr. Shivashankar at RRIT. The course aims to help students understand networking concepts and protocols. It covers topics like network architectures, protocols at different layers, and basic network configurations. The document provides details of transport layer protocols like TCP and UDP, explaining their services, operation mechanisms, and applications.
This paper proposes Core-Stateless Fair Queueing (CSFQ), a scheme that achieves approximately fair bandwidth allocation across high-speed networks without per-flow state in core routers. CSFQ decomposes routers into edge and core roles, with edge routers maintaining per-flow state to estimate rates and label packets, while core routers use these labels and estimated fair rates to probabilistically drop packets. Evaluation shows CSFQ provides fairness comparable to other schemes like FRED while significantly reducing complexity for core routers.
The document discusses flow control in TCP. It explains that TCP uses a sliding window mechanism for flow control to balance the sender's transmission rate with the receiver's reception rate. The sliding window allows packets within the window to be transmitted, and slides to the right when acknowledgments are received, making room for more packets. Problems like delayed acknowledgments, silly window syndrome, and solutions like Nagle's algorithm are also covered. TCP provides reliable data transfer using error control mechanisms like checksums, acknowledgments, and retransmissions of lost packets.
WIRELESS NETWORKS _ BABU M_ unit 3 ,4 & 5 PPT
EC 6802 WIRELESS NETWORKS PPT
POWER POINT PRESENTAION ON WIRELESS NETWORKS
BABU M
ASST PROFESSOR/ ELECTRONICS AND COMMUNICATION ENGINEERING,
RMK COLLEGE OF ENGINEERING AND TECHNOLOGY
CHENNAI, THIRUVALLUR DISTRICT
Get into Networking by Clearing Comptia Network+ Testcertblaster
The document summarizes key aspects of the OSI model, including:
1) The OSI model breaks network communication into 7 layers (physical, data link, network, transport, session, presentation, application) to standardize network components and allow different hardware/software to communicate.
2) Each layer has a specific role like physical addressing (data link), logical addressing (network), and ensuring reliable data transmission (transport).
3) The TCP/IP model is similar to OSI but combines some layers. It uses IP addresses, TCP/UDP, and port numbers to route packets between applications running on devices.
4) Common network devices operate at different layers, with cables and wireless access points at layer 1
This document summarizes vulnerabilities in network protocols like TCP/IP, ARP, IP, TCP, FTP, Telnet, and SMTP. It outlines issues like spoofing, flooding attacks, lack of authentication and encryption. It discusses how protocols work at different layers and security problems associated with each, such as spoofing of addresses, hijacking connections, sniffing cleartext data, and denial of service attacks. Prevention methods are also briefly covered.
Pre-Con Education: Recognizing Your Network's Key Performance Indicators Th...CA Technologies
Understanding key network metrics that impact end-user experience and how to leverage these key performance indicators is imperative for troubleshooting issues and restoring optimal network performance.
In this presentation, you will learn how to establish fundamental metrics for technology communications, gain an understanding of key concepts attributed to communication processes, gain an understanding of network performance metrics that actually impact end users, understand five sources of network latency and learn to use reference models as a troubleshooting tool.
For more information on DevOps solutions from CA Technologies, please visit: http://bit.ly/1wbjjqX
presentationphysicallyer.pdf talked about computer networksHetfieldLee
The document discusses TCP congestion control and the TCP Reno algorithm. It explains how TCP Reno implements additive increase multiplicative decrease (AIMD) using slow start, fast retransmit, and fast recovery to quickly repair single segment losses without requiring a timeout. TCP Reno uses duplicate ACKs to infer segment losses and retransmits the lost segment. It then sets the congestion window to half the original size for multiplicative decrease. This allows TCP to realize AIMD and avoid timeouts after single losses.
The document summarizes mobile ad hoc networks (MANETs) and some of the key challenges in designing protocols for them. It covers medium access control protocols, routing protocols, and some examples. Specifically, it discusses MACA for medium access, reactive routing protocols like DSR, proactive protocols like DSDV, and hybrid protocols like ZRP. It also outlines some of the tradeoffs between proactive and reactive routing approaches for mobile networks.
This document summarizes a tutorial on mobile ad hoc networks. It first discusses the characteristics and challenges of mobile ad hoc networks, including frequent topology changes and limited bandwidth. It then covers various aspects of designing protocols for mobile ad hoc networks, including medium access control, routing, and transport. For medium access control, it describes MACA and IEEE 802.11. For routing, it discusses reactive, proactive, and hybrid routing protocols and the tradeoffs between them. The document provides an overview of key considerations and approaches for building mobile ad hoc network protocols.
Communication over the kinds of Data-Links used for unmanned vehicles presents important challenges dues to the low bandwidth, intermittent, and lower reliability of these links. Classic network protocols such as TCP do not operate well in this environment forcing application developers to implement their own reliability and session management. This presentation describes he issues and alternatives.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
artificial intelligence and data science contents.pptxGauravCar
What is artificial intelligence? Artificial intelligence is the ability of a computer or computer-controlled robot to perform tasks that are commonly associated with the intellectual processes characteristic of humans, such as the ability to reason.
› ...
Artificial intelligence (AI) | Definitio
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
Discover the latest insights on Data Driven Maintenance with our comprehensive webinar presentation. Learn about traditional maintenance challenges, the right approach to utilizing data, and the benefits of adopting a Data Driven Maintenance strategy. Explore real-world examples, industry best practices, and innovative solutions like FMECA and the D3M model. This presentation, led by expert Jules Oudmans, is essential for asset owners looking to optimize their maintenance processes and leverage digital technologies for improved efficiency and performance. Download now to stay ahead in the evolving maintenance landscape.
An improved modulation technique suitable for a three level flying capacitor ...IJECEIAES
This research paper introduces an innovative modulation technique for controlling a 3-level flying capacitor multilevel inverter (FCMLI), aiming to streamline the modulation process in contrast to conventional methods. The proposed
simplified modulation technique paves the way for more straightforward and
efficient control of multilevel inverters, enabling their widespread adoption and
integration into modern power electronic systems. Through the amalgamation of
sinusoidal pulse width modulation (SPWM) with a high-frequency square wave
pulse, this controlling technique attains energy equilibrium across the coupling
capacitor. The modulation scheme incorporates a simplified switching pattern
and a decreased count of voltage references, thereby simplifying the control
algorithm.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
Use PyCharm for remote debugging of WSL on a Windo cf5c162d672e4e58b4dde5d797...shadow0702a
This document serves as a comprehensive step-by-step guide on how to effectively use PyCharm for remote debugging of the Windows Subsystem for Linux (WSL) on a local Windows machine. It meticulously outlines several critical steps in the process, starting with the crucial task of enabling permissions, followed by the installation and configuration of WSL.
The guide then proceeds to explain how to set up the SSH service within the WSL environment, an integral part of the process. Alongside this, it also provides detailed instructions on how to modify the inbound rules of the Windows firewall to facilitate the process, ensuring that there are no connectivity issues that could potentially hinder the debugging process.
The document further emphasizes on the importance of checking the connection between the Windows and WSL environments, providing instructions on how to ensure that the connection is optimal and ready for remote debugging.
It also offers an in-depth guide on how to configure the WSL interpreter and files within the PyCharm environment. This is essential for ensuring that the debugging process is set up correctly and that the program can be run effectively within the WSL terminal.
Additionally, the document provides guidance on how to set up breakpoints for debugging, a fundamental aspect of the debugging process which allows the developer to stop the execution of their code at certain points and inspect their program at those stages.
Finally, the document concludes by providing a link to a reference blog. This blog offers additional information and guidance on configuring the remote Python interpreter in PyCharm, providing the reader with a well-rounded understanding of the process.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
1. Session: 15 Prof. Sridhar Iyer 15.1
IT 601: Mobile Computing
TCP over wireless
TCP and mobility
Slides from Prof. Sridhar Iyer’s lecture
IIT Bombay
2. Session: 15 Prof. Sridhar Iyer 15.2
Effect of Mobility on Protocol Stack
• Application: new applications and adaptations
• Transport: congestion and flow control
• Network: addressing and routing
• Link: media access and handoff
• Physical: transmission errors and interference
3. Session: 15 Prof. Sridhar Iyer 15.3
TCP basics
• Reliable, ordered delivery
– uses sequence numbers, acknowledgements,
timeouts and retransmissions
– End-to-end semantics (ACK after data recd)
• Provides flow and congestion control
– uses sliding window based buffers and feedback
from receiver/network to adjust transmission rate
4. Session: 15 Prof. Sridhar Iyer 15.4
Window based flow control
• Window size minimum of
– receiver’s advertised window - determined by
available buffer space at the receiver
– congestion window - determined by sender, based on
network feedback
2 3 4 5 6 7 8 9 10 11 13
1 12
Sender’s window
Acks received Not transmitted
5. Session: 15 Prof. Sridhar Iyer 15.5
Timeouts and retransmission
• TCP manages four different timers for each
connection
– retransmission timer: when awaiting ACK
– persist timer: keeps window size information flowing
– keepalive timer: when other end crashes or reboots
– 2MSL timer: for the TIME_WAIT state
6. Session: 15 Prof. Sridhar Iyer 15.6
TCP: retransmission scenarios
Host A
loss
timeout
lost ACK scenario
Host B
X
Host A
Seq=92
timeout
premature timeout,
cumulative ACKs
Host B
Seq=100
timeout
7. Session: 15 Prof. Sridhar Iyer 15.7
RTT estimation
Exponential Averaging Filter:
• Measure SampleRTT for segment/ACK pair
• Compute weighted average of RTT
• EstimatedRTT = α PrevEstimatedRTT + (1 – α)
SampleRTT
– RTO = β * EstimatedRTT
• Typically α = 0.9; β = 2
8. Session: 15 Prof. Sridhar Iyer 15.8
Ideal window size
• Ideal size = delay * bandwidth
– delay-bandwidth product
• If window size < delay*bw
– Inefficiency (wasted bandwidth)
• If window size > delay*bw
– Queuing at intermediate routers (increased RTT)
– Potentially, packet loss
9. Session: 15 Prof. Sridhar Iyer 15.9
Congestion control
• On detecting a packet loss, TCP sender assumes
that network congestion has occurred
• On detecting packet loss, TCP sender drastically
reduces the congestion window
• Reducing congestion window reduces amount of
data that can be sent per RTT
11. Session: 15 Prof. Sridhar Iyer 15.11
0
2
4
6
8
10
0 2 4 6 8 10 12 14
Time (round trips)
Window
size
(segments)
advertised window
After fast recovery
Fast retransmit and Fast recovery
12. Session: 15 Prof. Sridhar Iyer 15.12
Typical mobile wireless scenario
• FH: Fixed Host
• MH: Mobile Host
• BS: Base Station (gateway)
13. Session: 15 Prof. Sridhar Iyer 15.13
Burst errors may cause Timeouts
• If wireless link remains unavailable for extended
duration, a window worth of data may be lost
– driving through a tunnel; passing a truck
• Timeout results in slow start
– Slow start reduces congestion window to 1 MSS,
reducing throughput
• Reduction in window in response to errors
unnecessary
14. Session: 15 Prof. Sridhar Iyer 15.14
Random errors may cause
Fast Retransmit or Timeout
• If a packet is lost due to transient link conditions
– Channel noise leading to CRC error
• Fast retransmit results in fast recovery
– Fast recovery reduces congestion window to 1/2
• If multiple packets losses happen in a window,
– Results in timeout
• Reduction in window in response to errors
unnecessary
16. Session: 15 Prof. Sridhar Iyer 15.16
TCP and wireless/mobility
TCP assumes congestion if packets dropped
• typically wrong in wireless networks
– often packet loss due to transmission errors
• mobility itself can cause packet loss
– nodes roam from one access point or foreign agent
to another with packets in transit
17. Session: 15 Prof. Sridhar Iyer 15.17
Motivation for TCP adaptation
Performance of an unchanged TCP degrades severely
for wireless/mobile environments
• TCP cannot be changed fundamentally
– Widely deployed in the fixed network
– Internet interoperability requirement
• TCP for wireless/mobility has to be compatible with
“standard” TCP
18. Session: 15 Prof. Sridhar Iyer 15.18
Adaptation for TCP over wireless
Several proposals to adapt TCP to wireless
environments
• Modifications to TCP implementation at
– Fixed Host
– Base Station
– Mobile Host
• Approaches
– Hide error losses from the sender
– Let sender know the cause of packet loss
19. Session: 15 Prof. Sridhar Iyer 15.19
Ideal behavior
• Ideal TCP behavior: TCP sender should simply retransmit a
packet lost due to transmission errors, without taking any
congestion control actions
– Ideal TCP typically not realizable
• Ideal network behavior: Transmission errors should be
hidden from the sender
– Errors should be recovered transparently and efficiently
• Proposed schemes attempt to approximate one of the
above two ideals
20. Session: 15 Prof. Sridhar Iyer 15.20
Link Layer mechanisms
• Forward Error Correction (FEC)
– Can be use to correct small number of errors
– Incurs overhead even when errors do not occur
• Link Level Retransmissions
– Retransmit a packet at the link layer, if errors are
detected
– Retransmission overhead incurred only if errors occur
21. Session: 15 Prof. Sridhar Iyer 15.21
Link Level Retransmissions
wireless
physical
link
network
transport
application
physical
link
network
transport
application
physical
link
network
transport
application
rxmt
TCP connection
Link layer state
22. Session: 15 Prof. Sridhar Iyer 15.22
Issues
• How many times to retransmit at the link level
before giving up?
• What triggers link level retransmissions?
• How much time is required for a link layer
retransmission?
• Should the link layer deliver packets as they arrive,
or deliver them in-order?
23. Session: 15 Prof. Sridhar Iyer 15.23
Split connection approach
• End-to-end TCP connection is broken into one
connection on the wired part of route and one over
wireless part of the route
• FH-MH = FH-BS + BS-MH
FH MH
BS
Base Station Mobile Host
Fixed Host
24. Session: 15 Prof. Sridhar Iyer 15.24
I-TCP: Split connection
wireless
physical
link
network
transport
application
physical
link
network
transport
application
physical
link
network
transport
application
rxmt
Per-TCP connection state
TCP connection TCP connection
Source: Vaidya
25. Session: 15 Prof. Sridhar Iyer 15.25
I-TCP advantages
• No changes to TCP for FH
• BS-MH connection can be optimized independent of
FH-BS connection
– Different flow / error control on the two connections
– Faster recovery due to relatively shorter RTT on
wireless link
26. Session: 15 Prof. Sridhar Iyer 15.26
I-TCP disadvantages
• End-to-end semantics violated
– ack may be delivered to sender, before data
delivered to the receiver
• BS retains hard state
– Buffer space required at BS on a per-TCP-
connection basis
– BS failure can result in permanent loss of data
(unreliability)
– Hand-off latency increases
27. Session: 15 Prof. Sridhar Iyer 15.27
Hand-off in I-TCP
• Data that has been ack’d to sender, must be moved to new
base station
FH MH
BS
40
39
37
38
37
41
MH
New base station
Hand-off
40
39
28. Session: 15 Prof. Sridhar Iyer 15.28
Snoop Protocol
• Retains local recovery of Split Connection approach
and uses link level retransmission
• Improves on split connection
– end-to-end semantics retained
– soft state at base station, instead of hard state
29. Session: 15 Prof. Sridhar Iyer 15.29
Snoop Protocol
• Buffers data packets at the base station BS
– to allow link layer retransmission
• When duplicate ACK received by BS from MH
– retransmit on wireless link, if packet present in buffer
– drop duplicate ACK
• Prevents fast retransmit at TCP sender FH
FH MH
BS
30. Session: 15 Prof. Sridhar Iyer 15.30
Snoop Protocol
FH MH
BS
wireless
physical
link
network
transport
application
physical
link
network
transport
application
physical
link
network
transport
application
rxmt
Per TCP-connection state
TCP connection
Source: Vaidya
31. Session: 15 Prof. Sridhar Iyer 15.31
Snoop : Example
FH MH
BS
40 39 37
38
37
35
36
37
38
35 TCP state
maintained at
link layer
33. Session: 15 Prof. Sridhar Iyer 15.33
Snoop advantages
• Local recovery from wireless losses
• Fast retransmit not triggered at sender despite out-of-
order link layer delivery
• High throughput can be achieved
• End-to-end semantics retained
• Soft state at base station
– loss of the soft state affects performance, but not
correctness
34. Session: 15 Prof. Sridhar Iyer 15.34
Snoop disadvantages
• Link layer at base station needs to be TCP-aware
• Not useful if TCP headers are encrypted (IPsec)
35. Session: 15 Prof. Sridhar Iyer 15.35
Delayed Dupacks
• Attempts to imitate Snoop, without making the base
station TCP-aware
• Delayed Dupacks implements the same two
features
– at BS : link layer retransmission
– at MH : reducing interference between TCP and link
layer retransmissions (by delaying dupacks)
36. Session: 15 Prof. Sridhar Iyer 15.36
Delayed Dupacks
• TCP receiver delays dupacks for interval D, when
out-of-order packets received
– Dupack delay intended to give link level retransmit
time to succeed
• Benefit: can result in recovery from a transmission
loss without triggering a response from the TCP
sender
37. Session: 15 Prof. Sridhar Iyer 15.37
Delayed dupacks advantages
• Link layer need not be TCP-aware
• Can be used even if TCP headers are encrypted
• Works well for relatively small wireless RTT
(compared to end-to-end RTT)
– relatively small delay D sufficient in such cases
38. Session: 15 Prof. Sridhar Iyer 15.38
Delayed dupacks disadvantages
• Right value of dupack delay D dependent on the
wireless link properties
• Mechanisms to automatically choose D needed
• Delays dupacks for congestion losses too, delaying
congestion loss recovery
39. Session: 15 Prof. Sridhar Iyer 15.39
Mobility and handoff
• Hand-offs may result in temporary loss of route to MH
– with non-overlapping cells, it may be a while before the
mobile host receives a beacon from the new BS
• While routes are being reestablished during handoff,
MH and old BS may attempt to send packets to each
other, resulting in loss of packets
40. Session: 15 Prof. Sridhar Iyer 15.40
Impact of handoff
• Split connection approach
– hard state at base station must be moved to new
base station
• Snoop protocol
– soft state need not be moved
– while the new base station builds new state, packet
losses may not be recovered locally
41. Session: 15 Prof. Sridhar Iyer 15.41
Handoff issues
• During the long delay for a handoff to complete
– a whole window worth of data may be lost
• After handoff is complete
– acks are not received by the TCP sender
• Sender eventually times out, and retransmits
– If handoff still not complete, another timeout will occur
• Performance penalty
– Time wasted until timeout occurs
– Window shrunk after timeout
42. Session: 15 Prof. Sridhar Iyer 15.42
Using Fast Retransmit
• When MH is the TCP receiver:
– after handoff is complete, it sends 3 dupacks to the
sender
– this triggers fast retransmit at the sender
• When MH is the TCP sender:
– invoke fast retransmit after completion of handoff
43. Session: 15 Prof. Sridhar Iyer 15.43
Mobile TCP (M-TCP)
• Handling of lengthy or frequent disconnections
• M-TCP splits as I-TCP does
– unmodified TCP for FH to BS
– optimized TCP for BS to MH
• BS (Foreign Agent)
– monitors all packets, if disconnection detected
• set advertised window size to 0
• sender automatically goes into persistent mode
– no caching, no retransmission at the BS
• If a packet is lost on the wireless link, it has to be
retransmitted by the original sender
44. Session: 15 Prof. Sridhar Iyer 15.44
M-TCP
• BS does not send an ack to FH, unless BS has received
an ack from MH
– maintains end-to-end semantics
• BS withholds ack for the last byte ack’d by MH
• When BS does not receive ACK for sometime, it chokes
sender by setting advertise window to 0
FH MH
BS
Ack 1000
Ack 999
45. Session: 15 Prof. Sridhar Iyer 15.45
M-TCP
• When a new ack is received with receiver’s advertised
window = 0, the sender enters persist mode
• Sender does not send any data in persist mode
– except when persist timer goes off
• When a positive window advertisement is received, sender
exits persist mode
• On exiting persist mode, RTO and cwnd are same as
before the persist mode
46. Session: 15 Prof. Sridhar Iyer 15.46
M-TCP
• Avoids reduction of congestion window due to
handoff, unlike the fast retransmit scheme
• Is not reducing the window a good idea?
– When host moves, route changes, and new route
may be more congested
– It is not obvious that starting full window after handoff
is right
47. Session: 15 Prof. Sridhar Iyer 15.47
FreezeTCP
• M-TCP needs help from base station (BS)
– BS withholds ack for one byte
– BS uses this ack to send a zero window advertisement
when MH moves to another cell
• FreezeTCP
– Receiver sends zero window advertisement (ZWA),
upon impending disconnection
– Receiver sends full window advertisement (FWA),
upon reconnection
48. Session: 15 Prof. Sridhar Iyer 15.48
FreezeTCP
• TCP receiver determines if a handoff is about to
happen
– determination may be based on signal strength
• Receiver should attempt to send ZWA 1 RTT before
handoff
• Receiver sends 3 dupacks when route is
reestablished
• No help needed from the base station
50. Session: 15 Prof. Sridhar Iyer 15.50
TCP Issues
• Route changes due to mobility
• Wireless transmission errors
– problem compounded with multiple hops
• Out-of-order packet delivery
– frequent route changes may cause out-of-order
delivery
• Multiple access protocol
– choice of MAC protocol can impact TCP
performance significantly
51. Session: 15 Prof. Sridhar Iyer 15.51
TCP over multi hop wireless
• When contention-based MAC protocol is used,
connections over multiple hops are at a
disadvantage compared to shorter connections
– because they have to contend for wireless access at
each hop
– extent of packet delay or drop increases with number
of hops
52. Session: 15 Prof. Sridhar Iyer 15.52
Impact of Multi-Hop Wireless Paths
0
200
400
600
800
1000
1200
1400
1600
1 2 3 4 5 6 7 8 9 10
Number of hops
TCP Throughtput
(Kbps)
TCP Throughput using 2 Mbps 802.11 MAC
53. Session: 15 Prof. Sridhar Iyer 15.53
mobility causes
link breakage,
resulting in route
failure
TCP data and acks
en route discarded
Impact of mobility
TCP sender times out.
Starts sending packets again
Route is
repaired
No throughput
No throughput
despite route repair
54. Session: 15 Prof. Sridhar Iyer 15.54
Positive impact of mobility
C
B
D
A
C
B
D
A
C
B
D
A
1.5 second route failure
Route from A to D is broken for ~1.5 second.
When TCP sender times out after 1 second, route still broken.
TCP times out after another 2 seconds, and only then resumes.
Throughput improves because number of hops reduced.
55. Session: 15 Prof. Sridhar Iyer 15.55
Improving throughput
• Network feedback
• Inform TCP of route failure by explicit message
• Let TCP know when route is repaired
– Probing
– Explicit notification
• Reduces repeated TCP timeouts and backoff
56. Session: 15 Prof. Sridhar Iyer 15.56
Network Feedback
• Network feedback beneficial
• Need to modify transport & network layer to
receive/send feedback
• Need mechanisms for information exchange
between layers
57. Session: 15 Prof. Sridhar Iyer 15.57
References
• Bakre, A., Badrinath, B., “I-TCP: Indirect TCP for mobile hosts”- IEEE ICDCS 1995.
• Balakrishnan, H., Srinivasan, S., Amir, E., and Katz, R., “Improving TCP/IP
Performance over Wireless Networks” – ACM Mobicom 1995.
• Brown, K., Singh, S., “M-TCP: TCP for mobile cellular networks” – ACM Computer
Communication Review, 27 (5), 1997.
• Goff, T. Moronski, J. Phatak, D.S. Gupta, V. “Freeze-TCP: a true end-to-end TCP
enhancement mechanism for mobile environments” – IEEE Infocom 2000.