Persistence Methods in CSMA

Duration: 11 min

This video lesson is available to enrolled students.

Return to /learn/SSC-JE-IMD-SCIENTIFIC-ASSISTANT-COMPUTER-SCIENCE/computer-networks/dll-access-control/csma-variants/asset-persistence-methods-in-csma after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. General Intelligence & Reasoning: Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Syllogisms, Venn Diagram, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Data Sufficiency, Puzzle Solving (Puzzles), Data Arrangement, Cubes & Dices, Calendar, Clock, Arithmetic, Number System, HCF LCM, Verbal Analogy (Word Based Analogy), Visual Recognition and Figure Completion, Paper Folding and Cutting, Transformation of Shapes, Clocks and Calendars, Direction Sense, Cubes and Dice, Patterns in Two-Dimensional Figures, Seating Arrangements, Analogy and Classification, Logical Deduction and Induction, Alphabet and Word Tests, Mathematical Operations, Series Completion, Simplification and Approximation, Coding and Decoding, Numerical Reasoning, Assembling and Grouping of Shapes, Three-Dimensional Patterns and Visualization, Vocabulary, Number System, Averages, Mixtures and Alligation, Simple and Compound Interest, Percentages, Algebra, Speed, Time and Distance, Seating and Arrangement Puzzles, Traverse Surveying, Order, Ranking and Sequence, Constraint Puzzles, Syllogisms and Venn Diagrams, Reading Comprehension, Critical Reasoning, Permutations and Combinations, Narrative Sequencing, Project Monitoring, Resources and Safety, Profit, Loss and Discount, Ratio and Proportion, Time and Work, Mensuration, Data Interpretation, Powers, Surds and Logarithms, Sequences and Series, Articles and Determiners, Sentence Completion, Data Sufficiency, Blood Relations, Simple Interest and Compound Interest, Mixture and Alligation, Sequence and Series (Series), Speed Time and Distance, Algebra, Profit and Loss, Powers and Exponents (Surds and Indices), Permutation and Combination
  2. General Awareness: Physics, Chemistry, Biology, History, Geography, Polity, Indian Economy, Environment, Static General Knowledge, GK- Current Affairs, Artificial Intelligence, MS Office Applications, Terms & Abbreviations, Keyboard Shortcuts, Evolution of Indian Banking (Banking & Financial Awareness), Emerging Tech Trends
  3. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus, Probability, Statistics, Signal Space and Optimum Detection, Probability, Statistics
  4. Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep, Number Systems and Codes, Registers and Counters, Boolean Algebra and Logic Gates, Microprocessors and Microcontrollers, Logic Families and CMOS Logic, Microprocessors, Logic Gates and Boolean Algebra, Minimization of Boolean Functions, Timing, Hazards and Testing, Logic Families, Combinational Logic Design, Arithmetic Circuits, Waveform Generators and Timer Circuits, Semiconductor Memories and Programmable Logic Devices, Combinational Logic Circuits, Latches and Flip-Flops, Finite State Machines, Sequential Circuits and State Machines, Minimization of Boolean Functions, Arithmetic Circuits, Latches and Flip-Flops, Number Systems and Codes, Registers and Counters
  5. Computer Organisation & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer, Register Transfer and Microoperations, Semiconductor Memories and Programmable Logic, Processor Organization and Instructions, Memory Hierarchy and Input/Output, Registers and Counters
  6. Programming & Data Structures: 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, HTML Basics, OOPS with C++, Java, Object Oriented Technology
  7. Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization
  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  9. Theory of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory
  10. Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  11. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Security, Windows OS, Distributed Systems, Unix OS, Linux OS
  12. Computer Networks: Introduction to CN, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware Basics, Data Communication, Website, Browser & Services, Web Design & Development, Network Security, Cyber Threats and Malware Attacks, Cyber Safety and Security
  13. Full Length Mock Tests:
  14. Sectional Tests:
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…