wireless 무선이동통신 수업

created : 2021-04-20T10:23:19+00:00
modified : 2021-06-03T22:10:19+00:00
wireless lectures

NS3

정보통신기술용어 해설 정리

Probability Theory and Statistics Theory

Discrete Random Variables

Continuous Random Varaibles

Cumulative Distribution Function

Probability Density Function

Expected Value, nth Moment, nth Central Moment, and Variance

Some Important Discrete Random Distributions

Poisson

Geometric

Binomial

Normal

Uniform

Exponential

Multiple Random Variables

Indpendence and Conditional Probability

Bayes Theorem

Importatnt Properties of Random Variables

Central Limit Theorem

Queueing Theory

Poisson Arrival Model

Properties of a Poisson Process

Interarrival Times of Poisson Process

Memoryless and Merging Properties

Basic Queuing Systems

Kendall’s Notation

Little’s Law

Markov Process

Birth-Death Process

State Transition Diagram

M/M/1/inf or M/M/1 Queuing System

Queuing Model and State Transition Diagram

Equilibrium State Equations

Traffic Intensity

Queuing System Metrics

Queuing System Metrics

M/G/1/inf Queuing Model

Basic Queuing Model

Queuing System Metrics

Fourier Transform

Dirac Delta Function

Unit Step Function

Sinc Function

Rectangular Function

Triangular Function

LTI System

Taylor Series

Fouerier Transform Properties

Fourier Transform of Various Function

Chapter 3. Radio Propagation, Sampling & Quantization

Information, Signals, and Communications

Radio Frequency Bands

| Classification Band | Initials | Frequency Range | Characteristics | | ——————- | ——– | ————— | ————— | | Extremely low | ELF | < 300 Hz | Ground wave | | Infra low | ILF | 300 Hz ~ 3 kHz | Ground wave | | Very low | VLF | 3kHz ~ 30 kHz | Ground wave | | Low | LF | 30 kHz ~ 300 kHz | Ground wave | | Medium | MF | 300 kHz ~ 3 MHz | Ground/Sky | | High | HF | 3 MHz ~ 30 MHz | Sky wave | | Very high | VHF | 30 MHz ~ 300 MHz | Space wave | | Ultra high | UHF | 300 MHz ~ 3 GHz | Space wave | | Super high | SHF | 3 GHz ~ 30 GHz | Space wave | | Extremely high | EHF | 30 GHz ~ 300 GHz | Space wave | | Tremendously high | THF | 300 GHz ~ 3000 GHz | Space wave |

Propagation Mechanisms

Free-space Propagation

Antenna Gain

Land Propagation

Path Loss (Free-space)

Path Loss (Land Propagation)

Path Loss

Slow Fading

Fast Fading

Characteristics of Instantaneous Amplitude

Doppler Shift

Delay Spread

Intersymbol Interference (ISI)

Digital Communications

General Structure of a Communication Systems

Digital versus Analog

Advantages of Digital Communications over Analog

Formatting and Transmission of Signal

Sampling

Sampling of Analog Signal

Aliasing effect & Nyquist Rate

Sampling Theorem

Quantization

PCM

Quantization error

Non-uniform quantization

Baseband transmission

Chapter 4, 7

Source and Channel Coding

Source - Info -> Transmitter (Formatter -> Source encoder -> Channel encoder -> modulator -> Multiplexer) - Transmitted signal -> Channel (With noise) - Received Signal -> Receiver(Demultiplexer -> Demodulator -> Channel decoder -> Source decoder -> Formmater) - Received Info -> Destination

Source Coding vs. Channel Coding

Source Coding

Introduction

  1. Source symbols encoded in binary
  2. The average codelength must be reduced
  3. Remove redundancy -> reduces bit-rate
    • Consider a discrete memoryless source on the alphabet
    • \[S = \{s_0, s_1, ... s_k\}\]
    • Let the corresponding probabilities be \(\{p_0, p_1, ... , p_k\}\)
    • and codelengths be \(\{ l_0, l_1, ..., l_k \}\)
    • Then, the average codelength (average number of bits per symbol) of the source is defined as
    • \[L = \sum_{k=0}^{K-1} p_k l_k\]
    • If \(L_{min}\) is the minimum possible value of \(\bar L\), then the coding efficiency of the source is given by \(\eta\)
    • \[\eta = \frac{L_{min}}{\bar L}\]
    • Data Compaction:
  4. Removal of redundant information prior to transmission.
  5. Loseless data compaction - no information is lost.
  6. A source code which represents the output of a discrete memoryless source should be uniquely decodable.

Source Coding Schemes for Data Compaction

Huffman Coding

Channel Coding

Forward Error Correction(FEC)

Block Codes

Block Codes: Linear Block Codes

Convolutional Codes

Interleaving

Information Capacity Theorem (Shannon Limit)

Turbo Codes

Modulation

Signal transmission through linear systems

Bandwidth of signal

Bandwidth of signal

Modulation

Modulation and Demodulation

Basic Modulation Techniques

Amplitude Modulation (AM)

Frequency Modulation (FM)

Frequency Shift Keying (FSK)

Phase Shift Keying (PSK)

Receiver job for Demoulation

Receiver structure

Signal Space Concept

Signal space

Orthogonal signal space

Signal space

Quadrature Amplitude Modulation (QAM)

Chapter 6.

Network Software

Terminologies

Service Primitives

Reference Models

Multiple Radio Access

Multiple Access

Contention-free protocols

FDMA (Frequency Division Multiple Access)

TDMA (Time Division Multiple Access)

Combining TDMA and FDMA

CDMA (Code Division Multiple Access)

Types of Channels

Frequency Division Duplex(FDD)

Time Division Duplex (TDD)

Frequency Hopping Spread Spectrum (FHSS)

Direct Sequnce Spread Spectrum (DSSS)

Contention-Based Protocols

ALOHA analysis

Summary of Aloha

CMSA (Carrier Sense Multiple Access)

Non-persistent / x-persistent CSMA Protocols

How to select probability p?

CSMA/CD (CSMA with Collision Detection)

CSMA/CA (CSMA with collision Avoidance)

CSMA/CA with ACK

Hidden node problem

CSMA/CA with RTS/CTS

Exponential Backoff

Backoff Interval

Chapter 13, 5, 10

Network Layer Protocols

Why Wireless?

Wireless vs. Mobile

Wireless Routing

Chracteristics of Ad Hoc Networks

Routing in MANETS - Goals

Routing Classification

Table Driven Routing Protocols

Destination Sequenced Distance Vector Routing (DSDV)

Cluster-head Gateway Switch Routing (CGSR)

Source-Initiated On-Demand Routing (Reactive)

Dynamic Source Routing (DSR)

### Ad-hoc On Demand Distance Vector (AODV)

The Cellular Concept

Cell Capacity

Erlang B and Erlang C

Efficiency (Utilization)

Cell Structure

Frequency Reuse

Reuse Distance

Cochannel Interference

Cell Splitting

Cell Sectoring by Antenna Design

Cellular SYstem

Registration

Steps for Registration

Handoff

Time for Handoff

Handoff initiation

Types of Handoff

Roaming