Persistence Methods in CSMA

Duration: 11 min

This video lesson is available to enrolled students.

Return to /learn/DSSSB-TGT-COMPUTER-SCIENCE-COMPLETE-COURSE/computer-network/dll-access-control/csma-variants/asset-persistence-methods-in-csma after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Section A: General Awareness: Polity, Physics, Biology, Chemistry, Static General Knowledge, History, Geography, Indian Economy, GK- Current Affairs, Evolution of Indian Banking (Banking & Financial Awareness), Environment
  3. Section A: General Intelligence & Reasoning ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analytical Reasoning (Counting Figures Reasoning), Blood Relations, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Directions (Direction Test), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Crypt Arithmetic, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, TCS NQT Advanced Reasoning Ability
  4. Section A: Arithmetical & Numerical Ability: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Powers and Exponents (Surds and Indices), Algebra, Probability, Mental Ability, Age Problems, Partnership, Statistics, Arithmetic, Speed Mathematics and Basic Mathematics, Miscellaneous
  5. Section A: English Language & Comprehension: Vocabulary, Subject Verb Agreement (Verb Noun Agreement), Adjectives, Tenses, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Articles, Sentence Construction, Preposition, Direct and Indirect Speech, Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Modals, Active Passive Voice (Voice), Sentence Correction (Error Correction), Adverb, Conjunction, Cloze Test (Cloze Passage)
  6. Section A: Hindi Language & Comprehension: भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
  7. Section B: Programming, Data Structures, OOP & Java: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Java, OOPS with C++, Language Design, Intro to Compilers, Visual Basics, Syntax Analysis: Bottom-Up, Object Oriented Technology
  8. Section B: Computer Networks, TCP/IP & Network Security: Introduction to CN, Data Communication, DLL: Flow Control, DLL: Access Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Access Technologies, Network Security, Society, Law & Ethics, Mobile Computing, Net Layer:Routing Protocol, Cyber Safety and Security
  9. Section B: Teaching Methodology: Child Development, Concept of Pedagogy, Theories, Inclusive Education, Experiential Pedagogy, Assessment & Evaluation, Curriculum Framework & Reforms, National Education Policy (NEP) 2020, Psychology, Teaching-Learning Process, Personality Development, Teaching Methods & Strategies, Learning and Motivation, Learners & Learning Process, Factors Affecting Teaching, Methods of Teaching, Nature, Objectives & Characteristics of Teaching, Teaching-Learning Aids & ICT Integration, Classroom Management & Communication, Evaluation, Assessment & Measurement, Curriculum & School Environment, Inclusive Education & Special Needs, Professional Development & Ethics
  10. Section B: Digital Electronics / Boolean Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Analog-Digital Conversion
  11. Section B: Operating Systems & Linux: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, File Management, Disc Scheduling, Unix OS, Linux OS, Distributed Systems, Windows OS
  12. Section B: Data Base Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, File Organization & Indexing, Transaction Management, Concurrency Control, Database Security & Authorization, Database Recovery, Data Warehousing & Mining
  13. Section B: Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, HTML Basics, CSS, Emerging Technologies, JavaScript-Basics, .Net Programming, Electronic Data Interchange and E-Commerce, XML
  14. Section B: Computer Fundamentals, IT Basics & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer, Terms & Abbreviations, MS Office Applications, Instr Formats & Modes, Floating Point Rep
  15. Section B: Python Language: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  16. Section B: Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, extras, Fundamentals of Systems and Information Systems
  17. Section B: Design & Analysis of Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  18. Section B: Mathematics: Linear Algebra, Calculus, Trigonometry, Vectors, Set Theory, Functions, Relations, Propositional and Predicate Logic, Research Process Steps, Graph Theory
  19. Section B: Computer Graphics, Multimedia & Mobile Computing: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing, Multimedia
  20. Section B: Emerging Trends: Emerging Tech Trends, Knowledge Representation, Natural Language Processing
  21. DSSSB Previous Year Paper:
  22. Business Studies and Management: Business Communication, Business Organization and Management, Financial Accounting, Business Economics, Management Information System (MIS), Knowledge Management & New Economy
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture introduces Persistence Methods in CSMA (Carrier Sense Multiple Access), focusing on how stations behave when the channel is busy versus idle. The instructor systematically presents three primary methods: 1-persistent, Non-persistent, and P-persistent. The session begins by defining the core problem of channel access contention and then details each method's logic through flowcharts, timeline diagrams, and probability constraints. Key distinctions include the immediate transmission strategy of 1-persistent methods versus the random wait times in Non-persistent approaches, and the probabilistic transmission of P-persistent protocols. The lecture emphasizes trade-offs between collision probability and channel efficiency, using visual aids to illustrate decision loops and time slot behaviors.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with an introduction to Persistence Methods in CSMA, posing the fundamental question of station behavior when the channel is busy or idle. The instructor lists three specific methods devised to answer this: 1-persistent, Non-persistent, and P-persistent. Visual focus shifts to a detailed slide on the 1-persistent method, highlighting its simplicity and high collision probability. On-screen text explicitly asks 'What should a station do if the channel is busy?' and lists the three methods. The instructor begins explaining that in the 1-persistent method, a station sends its frame immediately with probability 1 after finding the line idle.

  2. 2:00 – 5:00 02:00-05:00

    The lecture transitions to the Non-persistent CSMA method, contrasting it with the previously discussed 1-persistent approach. The instructor uses a flowchart and timeline diagram to illustrate how stations wait randomly if the channel is busy before sensing again. Key visual elements include a decision loop labeled 'Channel ?' with branches for 'Busy' and 'Idle'. The text on screen notes that the nonpersistent approach reduces collision chances because it is unlikely for two stations to wait the same random amount of time. The instructor demonstrates this by writing S1, S2, and S3 on the screen to represent different stations with varying wait times.

  3. 5:00 – 10:00 05:00-10:00

    The session moves to the P-Persistent CSMA method, which combines elements of persistence and probability. The slide displays a flowchart showing that upon finding the line idle, a station transmits with probability p or waits with probability q = 1 - p. Handwritten notes on the right side specify constraints like '0 <= p <= 1' and example slot values such as 'S1 = 3' and 'S2 = 8'. The instructor points to the flowchart elements, highlighting the sensing phase and probability outcomes. A timeline diagram illustrates channel sensing over discrete time slots, emphasizing how stations must wait for the next slot if they choose not to transmit immediately.

  4. 10:00 – 10:55 10:00-10:55

    The lecture concludes with a detailed review of the P-Persistent protocol steps and probability logic. The presenter explains the method's decision-making process using a flowchart that includes options to 'Wait a slot' or transmit. The slide displays a timeline diagram illustrating channel sensing and time slots, alongside handwritten notes showing probability constraints (0 <= p <= 1) and specific slot values like S1 = 3. The presenter gestures towards the flowchart to explain idle and busy channel conditions, reinforcing how stations navigate these states to minimize collisions while maintaining efficiency.

The lecture provides a structured comparison of three CSMA persistence methods, each addressing the challenge of channel access contention. The 1-persistent method is characterized by immediate transmission upon finding an idle line, which maximizes efficiency but incurs a high collision risk when multiple stations sense the channel simultaneously. In contrast, the Non-persistent method introduces a random wait time when the channel is busy, significantly reducing collision probability at the cost of potential idle channel periods. The P-persistent method offers a middle ground by dividing time into slots and using a probability p to determine transmission, balancing collision avoidance with channel utilization. Visual aids such as flowcharts and timeline diagrams are central to explaining these concepts, illustrating decision loops, sensing behaviors, and the impact of probability constraints on network performance.

Loading lesson…