Telecommunication & Wireless Communication MCQ Quiz - Objective Question with Answer for Telecommunication & Wireless Communication - Download Free PDF

The Correct answer is All of these.

Key Points

Data Link Layer (Layer 2):

• Role: Ensures reliable data transfer between two directly connected nodes over the physical layer. It manages error detection and MAC addressing.
• Devices: Switch, Bridge
• Sub-layers:
  • LLC (Logical Link Control)
  • MAC (Media Access Control)
• Functions:
  • Framing: Divides packets into frames with identifiable boundaries.
  • Physical Addressing: Adds MAC addresses to frame headers.
  • Error Detection and Correction: Detects and retransmits lost or damaged frames.
  • Flow and Access Control: Prevents data loss and manages channel access.

Additional Information

• OSI divides Telecommunications into Seven Layers:
  • Physical Layer.
  • Data Link Layer.
  • Network Layer.
  • Transport Layer.
  • Session Layer.
  • Presentation Layer.
  • Application Layer.
• Layer 1: The Physical Layer:
  • The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. 
  • It provides: 
    • Data encoding
    • Transmission technique
    • Physical medium transmission.
• Layer 2: The data-link layer:
  • The data link layer ensures reliable data frame transfer between nodes over the physical layer. 
  • To do this, the data link layer provides: 
    • Frame Traffic Control:
    • Frame Sequencing
    • Frame Acknowledgment
    • Frame Delimiting
    • Link Establishment and Termination
    • Frame Error Checking
• Layer 3: The Network Layer:
  • The network layer facilitates transferring variable-length data sequences between a source host on one network and a destination host on another network.
  • This layer is concerned with two functions
    • Routing and
    • Fragmentation / Reassembly: 
•  Layer 4: The Transport Layer:
  • The transport layer enables seamless data transfer between end users, offering dependable services to upper layers.
  • The Basic Transport Layer Services are: 
    • Resource Utilization (multiplexing).
    • Connection Management (establishing & terminating):
    • Flow Control (Buffering / Windowing):
• Layer 5: The Session Layer:
  • The session layer initiates, oversees, and concludes sessions between applications on various hosts in a network.
  • It is Responsible for dialog control and synchronization
  • Its primary role is to manage service requests and responses between hosts for applications.
  • The established session between hosts can be Simplex, half duplex, or full duplex.
• Layer 6: The Presentation Layer:
  • ​The presentation layer transforms data into the form that the application accepts.
  •  This layer is sometimes called the syntax layer or Translation layer.
  • The Presentation Layer is responsible for the following services: 
    • Data representation:
    • Data security:
    • Data compression:
    • Translation:
• Layer 7: The Application Layer:
  • ​The application layer is in direct contact with end users and software applications.
  • It interacts with applications that implement communication.
  • It's the top layer, responsible for introducing data into the OSI stack.
  • The Application Layer functions include:
    • Resource sharing and device redirection
    • Remote file and printer access
    • Network management
    • Directory services
    • Electronic messaging (e.g., mail)

The Correct answer is Teleservices.

Key Points 

• ISDN Services:
  • ​The purpose of the ISDN is to provide fully integrated digital services to users.
  • These services fall into categories- bearer services, teleservices, and supplementary services
  • Bearer Services:
    • Bearer services provide the means to transfer information (voice, data, and video) between users without the network manipulating the content of that information.
    • The network does not need to process the information and therefore does not change the content.
    • Bearer services belong to the first three layers of the OSI model and are well-defined in the ISDN standard.
    • They can be provided using circuit-switched, packet-switched, frame-switched, or cell-switched networks (ATM).

• Teleservices:
  • In teleservices, the network may change the contents of the data.
  • These services correspond to layers 4-7 of the OSI model.
  • Teleservices relay on the facilities of the bearer services and are designed to accommodate complex user needs, without the user having to be aware of the details of the process. 
  • Teleservices include telephony, teletex, telefax, videotex, telex, and teleconferencing. 

• Supplementary Service:
  • ​Supplementary services are those services that provide additional functionality to the bearer services and teleservices.
  • Examples of these services are reverse charging, call waiting, and message handling, all familiar from today's telephone company services

Additional Information

• ISDN:
  • Integrated Services Digital Network (ISDN) involves the integration of both circuit-switched and packet-switched networks within public telephone networks (PSTN) and carriers.
  • Various telephone and service equipment can link to the cloud network via public carriers using their respective equipment
  • Analog phones, facsimile machines, modems, and other devices can connect to the nearest Local Exchange Carrier (LEC), which, in turn, is linked to public carriers.
  • The choice of carrier for each transmission is determined by the technologies employed.
  • Circuit-switched networks facilitate analog phone calls, while packet-switched networks handle data transmission over the same carrier channels.
  • This integrated approach allows for diverse communication needs to be met efficiently.
• ATM:
  • ​Asynchronous Transfer Mode (ATM) is an ITU standard for high-speed networking, akin to the technologies mentioned earlier, facilitating voice, video, and data communications.
  • Unlike some other technologies, ATM networks are connection-oriented, aiming to enhance utilization and Quality of Service (QoS) in high-traffic networks.
  • Operating at the data link layer (Layer 2 in the OSI model), ATM technology plays a crucial role in optimizing network performance.

The Correct answer is (i), (ii) and (iv) are correct

Key Points

• The Session Layer is the 5th layer of the OSI (Open Systems Interconnection) model, responsible for establishing, managing, and terminating sessions between applications on different systems.
• It ensures structured and reliable communication between devices over a network.

Key Functions of the Session Layer:

• Session Establishment and Termination
  • Sets up and tears down communication sessions between systems.
  • Can support both connection-oriented and connectionless communications.
• Dialog Management
  • Controls dialogue direction (who sends and receives).
  • Supports half-duplex (token-based control) and full-duplex (simultaneous exchange).
• Communication Synchronization
  • Adds checkpoints (sync points) during long data transfers to allow recovery in case of failure.
• Activity Management
  • Divides data into independent logical units (activities) that can be processed separately.
• Data Transfer Control
  • Manages and monitors the orderly exchange of data across the session.
• Resynchronization
  • Restores tokens or session states to previous sync points using operations like set, abandon, or restart.
• Token Management:
  • In systems where only one side can send at a time, token management ensures mutual exclusion, avoiding data collision or conflict.

Additional Information

• Layer 1: The Physical Layer:
  • The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. 
  • It provides: 
    • Data encoding
    • Transmission technique
    • Physical medium transmission.
• Layer 2: The data-link layer:
  • The data link layer ensures reliable data frame transfer between nodes over the physical layer. 
  • To do this, the data link layer provides: 
    • Frame Traffic Control:
    • Frame Sequencing
    • Frame Acknowledgment
    • Frame Delimiting
    • Link Establishment and Termination
    • Frame Error Checking
• Layer 3: The Network Layer:]
  • The network layer facilitates transferring variable-length data sequences between a source host on one network and a destination host on another network.
  • This layer is concerned with two functions
    • Routing and
    • Fragmentation / Reassembly: 
•  Layer 4: The Transport Layer:
  • The protocols involved in the transport layer manage the end-to-end communication.
  • The TCP is used in many situations.
  • It provides a connection-oriented service with reliable transmission since TCP packets that are lost or erroneous are transmitted again. 
  • The Basic Transport Layer Services are: 
    • Resource Utilization (multiplexing).
    • Connection Management (establishing & terminating):
    • Flow Control (Buffering / Windowing):
• Layer 5: The Session Layer:
  • The session layer initiates, oversees, and concludes sessions between applications on various hosts in a network.
  • It is Responsible for dialog control and synchronization
  • Its primary role is to manage service requests and responses between hosts for applications.
  • The established session between hosts can be Simplex, half duplex, or full duplex.
• Layer 6: The Presentation Layer:
  • ​The presentation layer transforms data into the form that the application accepts.
  •  This layer is sometimes called the syntax layer or Translation layer.
  • The Presentation Layer is responsible for the following services: 
    • Data representation:
    • Data security:
    • Data compression:
    • Translation:
• Layer 7: The Application Layer:
  • ​The application layer is in direct contact with end users and software applications.
  • It interacts with applications that implement communication.
  • It's the top layer, responsible for introducing data into the OSI stack.
  • The Application Layer functions include:
    • Resource sharing and device redirection
    • Remote file and printer access
    • Network management
    • Directory services
    • Electronic messaging (e.g., mail)

The Correct answer is A, B, and C.,

Key Points

• A network port is a number used by Transport Layer protocols (such as TCP and UDP) to facilitate communication between two computers.
• It helps direct incoming traffic to the correct protocol or service on a system.
• Port numbers enable a single IP address to run multiple services, with each port serving a distinct function.
• A system can have up to 65,535 ports per IP address.
• The Internet Assigned Numbers Authority (IANA) manages the assignment and use of these ports.
• IANA defines three categories of ports:
  • Well-Known Ports (0 to 1023): These ports are reserved for common services:
    • 20,21: FTP (TCP)
    • 23: Telnet (TCP)
    • 25: SMTP (TCP)
    • 53: DNS (TCP/UDP)
    • 110: POP3 (TCP)
    • 123: NTP (UDP)
  • Registered Ports (1024 to 49151): IANA assigns these ports based on requests for specific services.
  • Dynamic or Private Ports (49152 to 65535): These are used for private services or temporary connections.
• Important Port Numbers:

The Correct answer is Asynchronous TDM.

Key Points

• Statistical Time-Division Multiplexing (TDM) is a more efficient alternative to synchronous TDM, also known as Asynchronous TDM or Intelligent TDM.
• Unlike synchronous TDM, where time slots are fixed and unused slots are wasted, statistical TDM dynamically allocates time slots based on demand, optimizing channel capacity.
• n statistical TDM, multiplexers have multiple I/O lines with buffers. During data transmission, the multiplexer scans the buffers, collects data, and fills the frame for transmission.
• The demultiplexer at the receiver end then distributes the data to the corresponding buffers.
• Unlike synchronous TDM, which often leaves slots unutilized, statistical TDM ensures better bandwidth utilization by fully utilizing the available slots, reducing transmission time.
• Each data slot in statistical TDM includes an address to identify the source of the data, as data arrives unpredictably.
• This adds overhead, but relative addressing can help reduce it, ensuring efficient delivery of data.

Additional Information Time Division Multiplexing (TDM)

• Time Division Multiplexing (TDM) is a technique that divides bandwidth into fixed time slots, allowing multiple data streams to share a single channel.
• Time Slots: Each source transmits data in its designated slot.
• Synchronization: Ensures accurate time slot allocation between sender and receiver.
• Applications: Widely used in telephony to transmit multiple voice calls over one line

Frequency Division Multiplexing (FDM)

• Divides the bandwidth of a communication medium into multiple frequency channels.
• Used in radio and television transmission.
• Requires guard bands to prevent inter-channel cross-talk.

Time Division Multiplexing (TDM):

• Allocates time slots to different data streams instead of dividing bandwidth.
• Used in digital communication systems.
• Types of TDM:
  • Synchronous TDM: Assigns fixed slots, leading to inefficiency if no data is available.
  • Statistical (Asynchronous) TDM: Dynamically allocates slots, improving bandwidth efficiency.

Wavelength Division Multiplexing (WDM):

• Enhances optical fiber capacity by transmitting multiple signals at different wavelengths.
• Used in telecommunications, ISPs, and data centers.
• Types of WDM:
  • Dense WDM (DWDM): Supports up to 80 channels with narrow wavelength spacing.
  • Coarse WDM (CWDM): Supports up to 18 channels with wider wavelength spacing.

The correct answer is A OR B

Key Points

•  Boolean operators:
  • ​Boolean Operators are simple words (AND, OR, NOT, or AND NOT) used as conjunctions to combine or exclude keywords in a search, resulting in more focus and productivity.
  • When Boolean operators are used for searching it is known as Boolean search
  • This kind of searching is also known as Combinatorial search.
  • The basic operations of Boolean algebra are conjunction, disjunction, and negation.
• AND:
  • This operator will retrieve all the documents which contain all the keywords occurring at both ends of the AND operator.
    • Syntax: AND
      Example: Library AND Information
    • The above query will retrieve only those documents which contain both the terms Library and Documentation. The precision in search is more. The number of documents retrieved will be less hence less is the recall value.
• OR:
  • This operator will retrieve all the documents which contain all the keywords occurring at both ends of the OR operator.
    • Syntax: OR
      Example: Library OR Information
    • The above query will retrieve all documents which contain both the terms Library and Documentation. The recall in search is more. The number of documents retrieved will be more but the precision of retrieved documents will be less.
• NOT or AND NOT:
  • These operators increase the precision of the search result. The query can be made more specific by using these operators. Using the capitalized AND NOT operator preceding a search term eliminates documents that contain that term.
    • Syntax AND NOT

Additional Information

•  Boolean algebra:
  • ​Boolean algebra was introduced by George Boole in his first book The Mathematical Analysis of Logic (1847)
  • According to Huntington, the term "Boolean algebra" was first suggested by Sheffer in 1913,

The correct answer is Full Duplex;

Key Points

•  Full Duplex:
  • ​It is the mode of transmission that is used in computing networks when there is simultaneous information flow in both directions, from sender to receiver.
  •  In this mode of transmission, the channel capacity is shared between the two devices.
  •  The Full Duplex mode features two simplex channels. One channel has traffic flowing in one direction, while the other channel has traffic flowing in the other way.
  • The full duplex mode is used when communication in both directions is required.
  • Examples: A telephone network and In a messaging app.

• Simplex:
  • The Simplex transmission mode is used in computing networks when there is a single or one-way flow of information from sender to receiver
  • In this mode of transmission, communication occurs only in one direction,
  • A basic example of a simplex transmission mode is communication between a computer and a keyboard and The radio station is a simplex channel.

​

• Half Duplex;
  • The half-duplex mode of transmission is used in computer networks when there is a way to flow information from sender to receiver but only one at a time.
  • In this mode, the connected devices can transmit or receive the data but not simultaneously.
  • The half-duplex mode is used when communication in both directions is not required at the same time.

​

• Examples; Walkie-talkie
• Bandwidth;
  • In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth.
  • The MOSFET (metal-oxide-semiconductor field-effect transistor) is the most important factor enabling the rapid increase in bandwidth
  • Edholm's law, proposed by and named after Phil Edholm in 2004, holds that the bandwidth of telecommunication networks doubles every 18 months
  • The MOSFET (MOS transistor) was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959

Additional Information

• Transmission mode, also known as a communication mode, is the transfer of data between two devices via a communication channel that includes an optical fiber, wireless channels, copper wires, and other storage media.
• The Physical Layer in the Open System Interconnection (OSI) Layer Model is dedicated to data transmission in the network.
• The data transmission method was initially used in modems in a computer networking system in the 1940s1940s, then in LANs, WANs, repeaters, and other networking systems.
• Based on the direction of the exchange of information. The transmission mode is classified into three types: simplex, half duplex, and full duplex.

The Correct answer is MSC:

Key Points

• Wireless communication
  • ​It is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices
  • To provide wireless communication within a particular geographic region, an integrated network of base stations must be deployed to provide sufficient radio coverage to all mobile users. The base station, in turn, must be connected to a central hub called MSC (mobile switching center).

Additional Information

• PSTN:
  • ​PSTN stands for the public switched telephone network.
  • The PSTN forms the global telecommunication grid which connects conventional telephone centers with MSCs throughout the world.
• PBX:
  • Private Branch eXchange, a hardware system that handles routing and switching of calls between a business location and the telephone network
•  PABX:
  • ​Private automated branch exchange is synonymous with modern-day business telephone systems. It connects external and internal callers to an internal network via a switchboard without the need for manual operation in the middle, unlike its ancestor PMBX.
• The history of wireless communication is discussed below:
  • The first telegraph was invented (1600 – 1833)
  • The invention of the radio from the telegraph (1867-1896)
  • The birth of radio (1897 – 1898)
  • Transoceanic Communication (1901 –1909)
  • Voice over Radio and the First Television Transmissions (1914 – 1940)
  • Commercial Television and the Birth of Mobile Telephony (1946 – 1976)
  • Cellular Mobile Telephony and Steps toward Wireless Internet (1979 – 1994)
  • The Wireless Data Era (1997 – 2009)
  • PCS (1995-2008)

The Correct answer is C, D, and E only.

Key Points

• A Network Interface Card (NIC) is commonly referred to as an interface card, allows devices to connect to a network.
• A NIC is a hardware component that enables network communication between computers.
• The main types of modems include DSL, Cable, Dial-up, and Fiber modems.
• A network card (NIC) is not an end port; rather, it acts as a connector between a computer and a network.
• NICs are not classified by 4-bit, 12-bit, or 20-bit formats. Instead, they are typically defined by speed (e.g., 10/100 Mbps, Gigabit, 10 Gbps) and communication standards (e.g., Ethernet, Wi-Fi, Bluetooth).

Additional Information

• A Network Interface Card (NIC) is a hardware component, either a circuit board or chip, that enables a computer to connect to a network.
• Modern NICs support input/output interrupts, direct-memory access, data transmission, and network traffic management.
• NICs provide a dedicated network connection, handling physical layer communication for standards like Ethernet and Wi-Fi.
• They facilitate data preparation, transmission, and flow control.
• Using the OSI model, NICs send signals at the physical layer, transmit data packets at the network layer, and function as an interface at the TCP/IP layer.

The correct answer is Asynchronous.

Key Points

• Asynchronous Transmission,
• It is also known as character-based transmission and conveys data in the form of individual bytes or characters.
• This mode of transmission operates as a half-duplex communication method, meaning that data can flow in one direction at a time.
• It employs the inclusion of start and stop bits along with the data to facilitate proper framing. 
  • START Bit: The transmission begins with the transmission of a START bit, which is always a logic 0 (low voltage level).
    • This START bit alerts the receiving device that data is about to be transmitted, and it helps the receiver synchronize its internal clock with the sender's clock.
  • Data Bits: Following the START bit, the actual data bits (typically 8 bits, but they can vary) are sent one by one.
    • These represent the actual information being transmitted, such as a character or a piece of data.
  • STOP Bit(s): After the data bits, one or more STOP bits are sent.
    • The STOP bit(s) indicate the end of the data character.
    • In most cases, one or two STOP bits are used, depending on the system configuration.
    • These STOP bits are always logic 1 (high voltage level).

Additional Information

• Synchronous Transmission,
  • It is characterized by the transfer of data in the form of blocks or frames, and operates in full-duplex mode, enabling simultaneous two-way communication between sender and receiver.
  • This mode mandates precise synchronization between the communicating devices.
  • Synchronous transmission maintains a continuous flow of data without any gaps.
  • It is recognized for its efficiency and reliability, making it the preferred choice for transferring substantial volumes of data.

The correct answer is 1992:

Key Points

• SMS:
  • S​hort Message/Messaging Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet, and mobile device systems.
  • The first SMS message was sent over the Vodafone GSM network in the United Kingdom on 3 December 1992, from Neil Papworth.
  • The text of the message was "Merry Christmas.
  • According to Matti Makkonen, the Nokia 2010, which was released in January 1994, was the first mobile phone to support composing SMSes easily
  • The first commercial deployment of a short message service center (SMSC) was by Aldiscon part of Logica (now part of CGI) with Telia (now TeliaSonera) in Sweden in 1993 followed by Fleet Call (now Nextel) in the US, Telenor in Norway and BT Cellnet (now O2 UK) later in 1993.

The correct answer is Bits.

Key Points

• Bandwidth is traditionally expressed in bits per second (bps)
• Modern network links now have far greater capacity, which is why bandwidth is now more often expressed as Mbps or Gbps.
• Bandwidth connections can be symmetrical, which means the data capacity is the same in both directions -- upload and download.
• Asymmetrical, which means download and upload capacity is not equal.
• In asymmetrical connections, the upload capacity is typically smaller than the download capacity.
• Enterprise-grade WAN and DIA links more commonly have symmetrical bandwidth.

The correct answer is photo phone:

Key Points

• The photophone, invented by Alexander Graham Bell and Charles Sumner Tainter on February 19, 1880, in Washington, D.C., allowed speech transmission on a beam of light.
• Bell considered it his most significant invention, with four patents dedicated to it.
• The photophone resembled a traditional telephone of its time, with the key difference being that it utilized modulated light for wireless transmission, whereas conventional telephones relied on modulated electricity transmitted through conductive wire circuits.

Additional Information

• Photo diode:
  • A photodiode is a semiconductor diode that generates current when exposed to light.
  • Its package allows various types of radiation, such as light, infrared, ultraviolet, or X-rays, to reach its light-sensitive region, which may incorporate optical filters or lenses.
• Photo recorder;
  • ​A "photo recorder" typically refers to a device or instrument that records or captures photographs or images.
  • It can encompass various types of equipment, including digital cameras, film cameras, or specialized imaging devices used for scientific or industrial purposes. 
• Smartphone:
  • ​A smartphone is a mobile phone that goes beyond the traditional functionality of voice calls and text messaging. Smartphones are highly versatile and offer a wide range of features and capabilities,

The correct answer is A, B and E only

Key Points

• OSI divides Telecommunications into Seven Layers:
  • Physical Layer.
  • Data Link Layer.
  • Network Layer.
  • Transport Layer.
  • Session Layer.
  • Presentation Layer.
  • Application Layer.
• Layer 6: The Presentation Layer:
  • ​The presentation layer transforms data into the form that the application accepts.
  •  This layer is sometimes called the syntax layer or Translation layer.
  • The Presentation Layer is responsible for the following services: 
    • Data representation:
    • Data security:
    • Data compression:
    • Translation:​

Additional Information

• Layer 1: The Physical Layer:
  • The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. 
  • It provides: 
    • Data encoding
    • Transmission technique
    • Physical medium transmission.
• Layer 2: The data-link layer:
  • The data link layer ensures reliable data frame transfer between nodes over the physical layer. 
  • To do this, the data link layer provides: 
    • Frame Traffic Control:
    • Frame Sequencing
    • Frame Acknowledgment
    • Frame Delimiting
    • Link Establishment and Termination
    • Frame Error Checking
• Layer 3: The Network Layer:]
  • The network layer facilitates transferring variable-length data sequences between a source host on one network and a destination host on another network.
  • This layer is concerned with two functions
    • Routing and
    • Fragmentation / Reassembly: 
•  Layer 4: The Transport Layer:
  • The transport layer enables seamless data transfer between end users, offering dependable services to upper layers.
  • The Basic Transport Layer Services are: 
    • Resource Utilization (multiplexing).
    • Connection Management (establishing & terminating):
    • Flow Control (Buffering / Windowing):
• Layer 5: The Session Layer:
  • The session layer initiates, oversees, and concludes sessions between applications on various hosts in a network.
  • Its primary role is to manage service requests and responses between hosts for applications.
  • The established session between hosts can be Simplex, half duplex, or full duplex.
• Layer 7: The Application Layer:
  • ​The application layer is in direct contact with end users and software applications.
  • It interacts with applications that implement communication.
  • It's the top layer, responsible for introducing data into the OSI stack.
  • The Application Layer functions include:
    • Resource sharing and device redirection
    • Remote file and printer access
    • Network management
    • Directory services
    • Electronic messaging (e.g., mail)

The Correct answer is Time Division Multiplexing (TDM).

Key Points

• Time Division Multiplexing (TDM) is a technique that divides bandwidth into fixed time slots, allowing multiple data streams to share a single channel.
• Time Slots: Each source transmits data in its designated slot.
• Synchronization: Ensures accurate time slot allocation between sender and receiver.
• Applications: Widely used in telephony to transmit multiple voice calls over one line.

Additional Information

• Multiplexing is a technique that allows multiple signals from different sources to share a single communication channel, optimizing bandwidth utilization.

Frequency Division Multiplexing (FDM)

• Divides the bandwidth of a communication medium into multiple frequency channels.
• Used in radio and television transmission.
• Requires guard bands to prevent inter-channel cross-talk.

Time Division Multiplexing (TDM):

• Allocates time slots to different data streams instead of dividing bandwidth.
• Used in digital communication systems.
• Types of TDM:
  • Synchronous TDM: Assigns fixed slots, leading to inefficiency if no data is available.
  • Statistical (Asynchronous) TDM: Dynamically allocates slots, improving bandwidth efficiency.

Wavelength Division Multiplexing (WDM):

• Enhances optical fiber capacity by transmitting multiple signals at different wavelengths.
• Used in telecommunications, ISPs, and data centers.
• Types of WDM:
  • Dense WDM (DWDM): Supports up to 80 channels with narrow wavelength spacing.
  • Coarse WDM (CWDM): Supports up to 18 channels with wider wavelength spacing.