Efficiency of Stop and Wait Protocol - ARQ

Duration: 6 min

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Module outline

  1. Quantitative Ability: Percentage, Profit and Loss, Ratio and Proportion (Ratios), Average, Time and Work, Speed Time and Distance, Simple Interest and Compound Interest, Age Problems, Number System, Divisibility Rules, HCF LCM, Algebra, Permutation and Combination, Probability, Data Interpretation, Logarithm, Sequence and Series (Series), Powers and Exponents (Surds and Indices), Speed Mathematics and Basic Mathematics
  2. Logical Reasoning: Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Data Sufficiency, Venn Diagram, Inequality, Series (Number and Letter Series) (Numerical Relations and Reasoning), Logical Sequence Of Words, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Subject Verb Agreement (Verb Noun Agreement), Tenses, Articles, Preposition, Conjunction, Modals, Active Passive Voice (Voice), Direct and Indirect Speech, Vocabulary, Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Completion (Fill in the blanks), Sentence Correction (Error Correction), Cloze Test (Cloze Passage), Facts, Inference and Judgements
  4. Programming Fundamentals (Technical): C Fundamentals
  5. Data Structures (Technical): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  6. Algorithms (Technical): Algorithm Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Time Complexity Analysis, Advanced Algorithms
  7. OOPs (Technical): Object Oriented Programming (OOPS)
  8. DBMS (Technical): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  9. SQL (Technical): SQL
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  11. Computer Networks (Technical): Introduction to CN, Data Communication, 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, Network Security, Cloud Computing and IoT, Cyber and Info Security
  12. Software Engineering (Technical): Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  13. Coding/Automata Round: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir, Pseudo Codes
  14. Personality / Behavioral Assessment: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
  15. Writing Assessment: English Writing Ability
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture explains the efficiency of the Stop and Wait ARQ protocol, deriving the formula η = 1 / (1 + 2a) and calculating effective bandwidth. The instructor begins by defining efficiency as the ratio of useful transmission time (Tt) to total cycle time, which includes waiting periods for acknowledgments. Through algebraic simplification, the formula is reduced to a function of 'a', representing the ratio of propagation delay (Tp) to transmission time. The session concludes with a numerical example calculating throughput based on efficiency and bandwidth.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the concept of efficiency for Stop and Wait ARQ, displaying a slide titled "Efficiency(n):" with the initial formula Useful Time / Total Cycle time = Tt / (Tt + 2 * Tp). He explains that useful transmission time is Tt, while the remaining 2 * Tp represents waiting time for processing. The derivation proceeds by dividing both numerator and denominator by Tt, resulting in the simplified expression n = 1 / (1 + 2 * Tp/Tt). The variable 'a' is defined as the ratio Tp / Tt, leading to the final efficiency formula η = 1 / (1 + 2a).

  2. 2:00 – 5:00 02:00-05:00

    The lecture continues with the derivation of the efficiency formula η = 1 / (1 + 2a), emphasizing that total time consists of transmission and propagation delays while queuing and processing delays are negligible. A handwritten note on the slide identifies 2 * Tp as Round Trip Time (RTT). The instructor then transitions to defining Throughput or Effective Bandwidth using the formula: Throughput = η * B. This section solidifies the relationship between efficiency and actual data transfer rates, preparing for a numerical application.

  3. 5:00 – 5:43 05:00-05:43

    The instructor calculates the effective bandwidth for a Stop and Wait protocol by substituting values into the formula Throughput = η * B. With an efficiency (η) of 0.5 and bandwidth (B) of 10 Mbps, the calculation yields a final throughput of 5 Mbps. The result is written and underlined on screen as "5 x 10 Mbps = 5 Mbps". The instructor then begins to illustrate the concept with a diagram representing data frames, visualizing how efficiency impacts frame transmission.

The lecture systematically derives the efficiency metric for Stop and Wait ARQ, starting from fundamental time components. The core formula η = 1 / (1 + 2a) highlights how propagation delay relative to transmission time degrades performance. By defining 'a' as Tp/Tt, the instructor simplifies complex timing relationships into a single variable. The final application demonstrates that even with high bandwidth, low efficiency significantly reduces effective throughput, as shown in the 5 Mbps result from a 10 Mbps link. This progression from theoretical derivation to practical calculation reinforces the importance of minimizing propagation delay in network design.

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