UNIT-2 CSE-306.pdf

💻 CSE-306 YouTube—>WhyCodeMrbean (for explanation of this notes) MODULE 2:- PHYSICAL LEVEL: —>This layer comes under the category of Hardware Layers. —>The physical Layer is the bottom layer in the (OS...

💻 CSE-306 YouTube—>WhyCodeMrbean (for explanation of this notes) MODULE 2:- PHYSICAL LEVEL: —>This layer comes under the category of Hardware Layers. —>The physical Layer is the bottom layer in the (OSI) Model. —>physical layer sends data bits from one device to another device. —>physical layer is responsible for sending raw data (like 1s and 0s) through wires or air. without worrying about what the data means or how it's organized. Signal: Electrical or electromagnetic representation of data that is transmitted over a communication medium called signal. Types of signal: Analog Signals: —>Analog signals are continuous waveforms that can represent a range of values over time. —>Phones Radio and TV speakers CSE-306 1  Digital Signals: —>Digital signals represent data in discrete values, typically as binary code (0s and 1s), making them suitable for computer processing. —>Used in computer networks for data transmission, including internet communication, file transfers, and video streaming. CSE-306 2  Digital to Digital Conversion : —>convert digital data into digital signals. —>digital-to-digital encoding can be done by a technique called line coding. —>The sender side encrypts digital data into digital signals, while the receiving side decodes the digital signal to regenerate the digital data Unipolar Encoding: CSE-306 3  —> binary '1' for positive voltage (+V), while '0' is represented zero voltage (0V). Polar: —>binary '1' for positive voltage (+V), while '0' is represented for negative voltage (-V). —>Polar Non-Return to Zero (Polar NRZ) CSE-306 4  —>Return to Zero (RZ): RZ uses three voltage levels, positive voltage to represent 1, negative voltage to represent 0 and zero voltage for none. Signals change during bits not between bits. Bipolar: —>Bipolar encoding, three voltage level is used that is positive, negative and zero. —>zero by 0, positive and negative voltage by alternatives 1’s. CSE-306 5  Analog to Digital Conversion: 1. Sampling: —>In this process, the continuous analog signal is measured at small intervals. 2. Quantization: —>Here, the sampled values are converted into fixed levels. —>Some information may be lost in this process. CSE-306 6  Encoding: —>In this last step, the quantized values are converted into binary numbers (0s and 1s). Example. 1. Digital Audio Recording (e.g., music tracks) 2. Digital Photography (e.g., cameras) 3. Medical Imaging (e.g., MRI scans) 4. Voice Recognition Systems (e.g., virtual assistants) 5. Telecommunications (e.g., mobile phone calls) CSE-306 7  Analog to Analog conversion: —>Analog modulation means changing an analog signal to show analog data Amplitude Modulation (AM): —>Changes the height (amplitude) of the carrier signal to represent the data. Frequency Modulation (FM): CSE-306 8  —>Changes the frequency of the carrier signal based on the original signal's voltage levels. Phase Modulation (PM): —>Changes the phase of the carrier signal to reflect changes in the original signal's voltage. Example: CSE-306 9  1. AM Radio 2. FM Radio 3. Television Broadcasting 4. Walkie-Talkies Digital to Analog conversion: Amplitude Shift Keying (ASK) Definition: A modulation technique where an analog carrier signal's amplitude is modified to represent digital data. Key Characteristics: Binary data: 0 = zero amplitude, 1 = carrier amplitude. Frequency and phase of the carrier remain constant. Advantages: Suitable for transmitting digital data over optical fiber. Simple and inexpensive design for receivers and transmitters. Offers high bandwidth efficiency with lesser bandwidth usage compared to Frequency Shift Keying (FSK). CSE-306 10  Disadvantages: Susceptible to noise interference, risking loss of entire transmissions. Lower power efficiency. Frequency Shift Keying (FSK) Definition: A modulation technique where the frequency of an analog carrier signal is modified to represent binary data. Key Characteristics: High frequency for binary high input, low frequency for binary low input. Amplitude and phase of the carrier remain constant. Advantages: Better noise immunity compared to Amplitude Shift Keying (ASK). Lower error rates. High signal-to-noise ratio. CSE-306 11  Simple transmitter and receiver design for low data rate applications. Disadvantages: Requires larger bandwidth than ASK, leading to lower bandwidth efficiency. Lower power efficiency. Phase Shift Keying (PSK) Definition: Modulation technique where the phase of an analog carrier signal is modified to represent binary data, with constant amplitude and frequency. Types: 1. Binary Phase Shift Keying (BPSK): Simplest form of PSK, also known as phase reversal keying or 2PSK. Uses a 180-degree phase shift to represent binary 1 and 0. Robust for long-distance wireless communication. 2. Quadrature Phase Shift Keying (QPSK): Increases bit rate by encoding two bits per symbol. Utilizes four phases (90-degree shifts). Offers double the data rate compared to BPSK. Advantages: More power-efficient than Amplitude Shift Keying (ASK) and Frequency Shift Keying (FSK). Lower error rates. More efficient data transmission compared to FSK. Disadvantages: Low bandwidth efficiency. CSE-306 12  Complex detection and recovery algorithms for binary data. Non-coherent reference signal. Multiplexing: Multiplexing is a technique that allows multiple signals to be sent over a single communication channel. 1. Multiplexer (MUX): This device combines multiple input signals into one output signal for transmission. 2. De-multiplexer (DEMUX): At the receiving end, this device separates the combined signal back into the original individual signals. 1. Bandwidth Efficiency: Multiplexing lets many data streams use the same channel, making the most of available bandwidth. 2. Cost Reduction: It lowers costs by reducing the number of physical connections needed. CSE-306 13  3. Improved Performance: Multiplexing allows multiple connections to happen simultaneously, leading to faster data transfer. Bandwidth :—>is the maximum data transfer rate of a network Four part: 1. Time Division Multiplexing (TDM) 2. Frequency Division Multiplexing (FDM) 3. Wavelength Division Multiplexing (WDM) 4. Code Division Multiplexing (CDM) (1).Time Division Multiplexing (TDM): Definition: TDM is a digital technique that allocates time slots for users to transmit data over a single frequency channel. Time Slots: Each user is assigned a specific time interval (time slot) for data transmission, with data sent one at a time in frames. Types of TDM: 1. Synchronous TDM CSE-306 14  Preassigned Slots: Time slots are allocated to devices regardless of whether they have data to send. Inefficient Utilization: This can lead to wasted channel capacity due to empty slots. 2. Asynchronous TDM Dynamic Allocation: Time slots are assigned only to devices that have data to send. Efficiency: This approach makes better use of available slots, reducing the time needed for transmission. Slot Count: The number of time slots can be fewer than the number of devices, meaning not every device needs a slot all the time. CSE-306 15  Advantages: Efficient use of bandwidth. Ability to multiplex both digital and analog signals (primarily digital). Disadvantages: Synchronous TDM can waste bandwidth with empty slots. Asynchronous TDM requires dynamic allocation mechanisms. (2).Frequency Division Multiplexing (FDM): Definition: FDM is a technique that allows multiple signals to be transmitted simultaneously over a single communication medium by dividing the available bandwidth into distinct frequency channels. Analog Technology: FDM is primarily an analog technology used for transmitting analog signals. Channel Division: The total bandwidth is divided into smaller, non-overlapping frequency channels, each allocated to a different CSE-306 16  user. Exclusive Access: Each user has exclusive access to their assigned frequency channel, allowing them to transmit and receive data independently. Non-Overlapping Channels: Channels are designed to avoid overlap, ensuring that signals do not interfere with one another. Guard Bands: To prevent interference between adjacent channels, guard bands (unused frequencies) are placed between them, providing a buffer zone. Applications: Commonly used in radio broadcasting, television, and traditional telephone systems. CSE-306 17  (3).Wavelength Division Multiplexing (WDM): 1. Definition: WDM is a technology that allows multiple optical signals to be transmitted simultaneously over a single optical fiber, each using a different wavelength of light. 2. Signal Combination: Different wavelengths are combined onto one optical fiber for transmission, enabling efficient use of the fiber's capacity. 3. Types of WDM: Dense Wavelength Division Multiplexing (DWDM): Supports many channels (up to 80) with narrow spacing (0.8 nm or less), suitable for high-capacity applications. Coarse Wavelength Division Multiplexing (CWDM): Supports fewer channels (up to 18) with wider spacing (20 nm), used for lower-capacity needs. CSE-306 18  4. Advantages: WDM offers higher data rates, lower power consumption, and simplified equipment compared to other multiplexing methods like TDM, along with easy upgrades for network expansion. 5. Applications: WDM is widely used in telecommunications, cable TV, internet service providers, and data centers, enabling efficient long-distance data transmission with high speed. (4).Code Division Multiplexing (CDM): Definition: Technique allowing multiple users to transmit data simultaneously over one channel using unique codes. Unique Codes: Each user has a distinct code that spreads their signal. Spread Spectrum: The data signal is expanded for wider bandwidth. Applications: Used in cellular and satellite communications. Security: Harder to intercept or jam due to unique codes. Advantages of Multiplexing Efficient Bandwidth Use: Multiple signals share one channel. Increased Data Capacity: More data can be sent at once. CSE-306 19  Scalability: Easy to add more users without major changes. Flexibility: Different types (TDM, FDM, WDM, CDM) for various needs. Disadvantages of Multiplexing Synchronization Issues: Keeping data streams aligned can be tricky. Latency: Combining signals can introduce delays. Signal Degradation: Long distances can weaken signals. Resource Management: Requires careful planning to avoid congestion Basics of Data Communications Data Communication: The exchange of data between devices through a transmission medium. It involves sending and receiving information in the form of signals. Components: The main components include the sender, receiver, and the transmission medium (like cables, fiber optics, or wireless). Transmission Media: —>Media" refers to the physical (pathway) medium through which data is transmitted. CSE-306 20  Guided Media: —>Physical media that guide the signal 1. Copper Cables: Such as twisted pair cables (Ethernet cables) and coaxial cables, which use electrical signals to transmit data. 2. Fiber Optic Cables: These use light signals to transmit data over long distances with high bandwidth. Unguided Media: —>Wireless transmission through the air 1. Wireless Media: This includes radio waves, microwaves, and infrared signals used in wireless communication technologies like Wi-Fi and cellular networks. Radio Waves: Used in wireless communication, including Wi-Fi and cellular networks. 2. Satellite Communication: Utilizing satellite signals for data transmission over large distances. CSE-306 21  Microwaves: Used for point-to-point communication and satellite transmission. Infrared : for short distance. like tv remote. Transmission Impairments and Performance: Transmitted data can get corrupted or damaged during data transmission due to many reasons. 1.Attenuation: —>Attenuation is generally decreased in signal strength intensity. —>the farther a signal has to travel, the weaker it becomes. CSE-306 22  2. Distortion: Distortion in networking occurs when signals change during transmission, making data unclear or incorrect. It can happen due to poor cables, network devices, or environmental factors. 3. Noise: any unwanted signal gets added to the transmitted signal. CSE-306 23  Data Rate: —>its refers to the amount of data that can be transmitted in a given amount of time. —>It is typically measured in bits per second (bps). —>Higher data rates indicate the ability to send more data in a shorter period Measurement Units bps (bits per second): The basic unit of data rate. Kbps (kilobits per second): 1,000 bits per second. Mbps (megabits per second): 1,000,000 bits per second. Gbps (gigabits per second): 1,000,000,000 bits per second. 1. Raw Data Rate 2. Effective Data Rate Cabling Standards: Cabling standards are guidelines and specifications that define the types of cables, connectors, and installation practices used in networking and. CSE-306 24  These standards ensure compatibility, performance, and safety in network cabling. Key Cabling Standards 1. ANSI/TIA-568 Overview: This standard outlines the requirements for commercial building cabling, including specifications for twisted pair and fiber optic cables. Categories: Category 5e (Cat 5e): Supports speeds up to 1 Gbps (Gigabit Ethernet). Category 6 (Cat 6): Supports speeds up to 10 Gbps over short distances. Category 6a (Cat 6a): Enhanced version of Cat 6, supporting 10 Gbps up to 100 meters. Category 7 (Cat 7): Supports higher frequencies and better shielding, suitable for high-speed networks. 2. ISO/IEC 11801 Overview: An international standard for generic cabling systems in commercial buildings. It complements ANSI/TIA-568 and provides guidelines for cabling design and installation. Categories: Similar to ANSI/TIA-568 but includes additional specifications for fiber optic cabling. 3. IEEE 802.3 Overview: This standard defines the physical layer and data link layer specifications for Ethernet networks. Relevance: Specifies the use of various cabling types for different Ethernet speeds (e.g., 10BASE-T, 100BASE-TX, 1000BASE-T). 4. BICSI Standards CSE-306 25  Overview: The Building Industry Consulting Service International (BICSI) provides guidelines for the design and installation of cabling systems. Focus: Emphasizes best practices for cabling infrastructure, including pathways, spaces, and installation techniques. 5. NEC (National Electrical Code) Overview: A set of regulations in the U.S. that governs electrical wiring and installations, including networking cabling. Importance: Ensures safety and compliance with electrical standards. Types of Cabling 1. Twisted Pair Cables: Unshielded Twisted Pair (UTP): —>Commonly used in networking (e.g., Cat 5e, Cat6). Shielded Twisted Pair (STP): —>Offers additional shielding to reduce interference. 2. Coaxial Cables: Used for cable television and broadband internet connections. 3. Fiber Optic Cables: Single-Mode: Used for long-distance communication. Multi-Mode: Used for shorter distances, typically within buildings. CSE-306 26