Wireless Communication Exam questions and answers

What is wireless communication?
Answer: Transfer of information between two or more devices without physical connections using electromagnetic waves.

What are the types of wireless communication?
Answer: Radio waves, microwaves, infrared, Bluetooth, Wi-Fi, satellite communication, and cellular networks.

Define frequency and its role in wireless communication.
Answer: Frequency is the number of wave cycles per second, measured in Hertz (Hz), and determines signal strength and bandwidth.

What is the speed of electromagnetic waves in free space?
Answer: Approximately $3 \times 10^8$ m/s (speed of light).

What is modulation in wireless communication?
Answer: Process of varying a carrier signal’s properties (amplitude, frequency, phase) to transmit data.

Differentiate between AM and FM.
Answer: AM varies amplitude, FM varies frequency for transmitting signals.

What is a cellular network?
Answer: A wireless network divided into cells, each with a base station, providing communication via radio frequencies.

What is attenuation?
Answer: Loss of signal strength as it propagates through a medium.

Explain line-of-sight communication.
Answer: Wireless communication where the transmitter and receiver must have a clear path without obstructions.

What is the role of antennas in wireless communication?
Answer: Antennas transmit and receive electromagnetic waves.

What is bandwidth in wireless communication?
Answer: Range of frequencies a signal occupies, measured in Hertz (Hz).

Define signal-to-noise ratio (SNR).
Answer: Ratio of signal power to noise power, indicating communication quality.

What are base stations?
Answer: Fixed stations in cellular networks that facilitate communication between devices and the network.

Explain the concept of frequency reuse.
Answer: Using the same frequency in different cells separated by sufficient distance to minimize interference.

What is interference in wireless communication?

Answer: Unwanted signals that disrupt communication.

Define handoff in cellular networks.
Answer: Transfer of an active call from one base station to another as a user moves.

What is Bluetooth?
Answer: A short-range wireless technology for exchanging data over short distances (up to 100 meters).

What is the range of Wi-Fi?
Answer: Typically 30–50 meters indoors and up to 300 meters outdoors.

What is RFID?
Answer: Radio Frequency Identification, used for tracking and identification using radio waves.

What is NFC?
Answer: Near Field Communication, a short-range wireless technology for data exchange within a few centimeters.

What are 802.11 standards?
Answer: A set of Wi-Fi standards defining wireless LAN (WLAN) communication.

Differentiate between 4G and 5G.
Answer: 5G offers higher speeds, lower latency, and supports more connected devices compared to 4G.

What is CDMA?
Answer: Code Division Multiple Access, a channel access method that allows multiple users to share the same frequency band.

What is OFDM?
Answer: Orthogonal Frequency Division Multiplexing, a digital transmission technique dividing a signal into multiple sub-signals.

What is GSM?
Answer: Global System for Mobile Communications, a standard for cellular networks.

Explain LTE.
Answer: Long Term Evolution, a 4G standard for high-speed wireless communication.

What is WiMAX?
Answer: Worldwide Interoperability for Microwave Access, a wireless communication standard for long-range internet access.

Define Zigbee.
Answer: A wireless communication protocol for low-power IoT devices.

What is LoRaWAN?
Answer: Low Power Wide Area Network protocol for IoT and M2M applications.

What is MIMO?
Answer: Multiple Input Multiple Output, a technology to use multiple antennas to improve communication performance.

What is the frequency range of 5G?
Answer: 5G operates in two ranges: Sub-6 GHz and mmWave (24–100 GHz).

What is Wi-Fi 6?
Answer: The latest Wi-Fi standard (802.11ax) offering faster speeds and improved capacity.

Explain HSPA.
Answer: High-Speed Packet Access, a 3G technology for faster data transmission.

What is Edge Computing in wireless communication?
Answer: Processing data closer to devices rather than in centralized servers, reducing latency.

What is the function of the MAC layer in wireless communication?
Answer: Handles channel access and data packet framing.

What is IPv6?
Answer: The latest internet protocol providing a larger address space than IPv4.

What is SSID in Wi-Fi networks?
Answer: Service Set Identifier, the name of a Wi-Fi network.

What is VoLTE?
Answer: Voice over LTE, enabling voice calls over a 4G LTE network.

What is backhaul in wireless networks?
Answer: A network that connects access points or base stations to the core network.

What is beamforming in 5G?
Answer: A technology to direct signals to specific devices for improved efficiency and performance.

What is a femtocell?
Answer: A small cellular base station used to extend coverage indoors for better connectivity.

What is an ad hoc network?
Answer: A decentralized wireless network without fixed infrastructure, where devices communicate directly.

Define QoS in wireless communication.
Answer: Quality of Service refers to the ability of a network to ensure reliable performance for specific applications (e.g., VoIP, video streaming).

What is latency in wireless communication?
Answer: The time delay between sending and receiving data over a network.

What is carrier frequency?
Answer: The frequency of the unmodulated signal that carries the data in wireless communication.

What are smart antennas?
Answer: Antennas that use signal processing to dynamically adjust their directionality for better performance.

What is a mesh network?
Answer: A network where devices (nodes) are interconnected, allowing communication through multiple paths for redundancy.

Explain cognitive radio.
Answer: A smart radio system that detects unused spectrum and adjusts its transmission to use the available bandwidth efficiently.

What is white space in spectrum?
Answer: Unused portions of the radio spectrum in a specific geographical area, often repurposed for other applications.

Explain the difference between uplink and downlink.
Answer: Uplink refers to communication from the device to the base station, while downlink is from the base station to the device.

What is the use of spread spectrum in wireless communication?
Answer: Spread spectrum techniques, such as FHSS and DSSS, increase security and reduce interference by spreading the signal over a wider bandwidth.

What is the typical range of a femtocell?
Answer: Between 10–50 meters, depending on the environment and configuration.

What is the main advantage of MIMO in wireless systems?
Answer: MIMO improves data rates and reliability by using multiple antennas for simultaneous transmission and reception.

What is the significance of the Nyquist rate?
Answer: The Nyquist rate is twice the maximum frequency of a signal, ensuring accurate sampling without aliasing.

What is the role of Handover in cellular networks?
Answer: It maintains an active call or data session when a user moves from one cell to another.

Explain the concept of cooperative communication.
Answer: Wireless devices work together by relaying each other's data to improve communication quality and coverage.

What is the impact of path loss in wireless communication?
Answer: Path loss decreases signal strength as it propagates through the medium, impacting coverage and quality.

What is a relay in wireless networks?
Answer: A device that retransmits signals to extend coverage or improve connectivity.

How is adaptive modulation used in wireless communication?
Answer: The system adjusts modulation schemes (e.g., QPSK, QAM) based on channel conditions to optimize performance.

What is wireless sensor networking (WSN)?
Answer: A network of spatially distributed sensors used to monitor and collect data from the environment.

What are the common sources of interference in wireless communication?
Answer: Neighboring devices, overlapping frequencies, physical obstructions, and electromagnetic noise.

What is fading in wireless communication?
Answer: Variations in signal strength caused by the interference of multiple propagation paths.

What are multipath effects?
Answer: Signal propagation via multiple paths causing constructive or destructive interference at the receiver.

Explain shadowing in wireless networks.
Answer: Signal degradation due to obstructions like buildings or trees, causing uneven signal strength.

What is the hidden node problem?
Answer: A situation in wireless networks where two nodes cannot detect each other, causing transmission collisions.

How do wireless networks address security concerns?
Answer: By using encryption (WPA2, WPA3), secure protocols, and authentication mechanisms.

What is the significance of beamforming in modern wireless networks?
Answer: Beamforming directs signals toward the intended receiver, improving efficiency and reducing interference.

What is frequency planning?
Answer: Allocating frequencies to avoid interference and optimize network performance in cellular systems.

What is the role of error correction codes in wireless systems?
Answer: They detect and correct errors in transmitted data to ensure reliability. Examples include Hamming and Reed-Solomon codes.

What are the main challenges of 5G networks?
Answer: Deployment cost, high power consumption, coverage in dense urban areas, and device compatibility.

What is millimeter-wave technology in 5G?
Answer: High-frequency bands (24 GHz and above) offering faster speeds and lower latency but with limited range.

What is Massive MIMO?
Answer: An advanced form of MIMO with hundreds of antennas for higher capacity and better spectral efficiency.

What are the key features of Wi-Fi 7?
Answer: Faster speeds, reduced latency, and multi-link operation for simultaneous data transmission across bands.

What is device-to-device (D2D) communication?
Answer: Direct communication between devices without relying on a central network.

What is NB-IoT?
Answer: Narrowband IoT, a low-power wide-area network technology for IoT devices.

What is Li-Fi?
Answer: A wireless communication technology using light waves instead of radio waves.

What is 6G, and how does it differ from 5G?
Answer: A future wireless standard promising ultra-high speeds, AI-driven networks, and improved coverage compared to 5G.

What is quantum communication?
Answer: A secure communication method using quantum mechanics principles like quantum entanglement.

What is the role of AI in wireless communication?
Answer: AI optimizes spectrum usage, predicts network traffic, and enhances QoS by dynamically managing resources.

What is edge computing in wireless networks?
Answer: Processing data at the network edge close to devices, reducing latency and improving efficiency.

What is the function of a baseband processor?
Answer: Handles signal processing tasks like modulation, demodulation, and error correction in communication devices.

What is duplexing in wireless communication?
Answer: Simultaneous bidirectional communication, implemented as Time Division Duplex (TDD) or Frequency Division Duplex (FDD).

Explain carrier aggregation in LTE.
Answer: Combining multiple frequency bands to increase bandwidth and data rates.

What is dynamic spectrum access?
Answer: Adaptive allocation of spectrum resources to improve efficiency.

What is orthogonality in OFDM?
Answer: Subcarriers are orthogonal, avoiding interference and improving spectral efficiency.

How does a satellite communication system work?
Answer: Transmits signals via satellites orbiting the Earth, covering large areas for broadcasting and global communication.

What is WiGig?
Answer: Wireless Gigabit Alliance technology for high-speed communication at 60 GHz.

What is a pico-cell?
Answer: A small cell used to improve coverage in areas like shopping malls or airports.

What is the Doppler effect’s impact on wireless communication?
Answer: It causes frequency shifts in signals due to relative motion, impacting performance in mobile environments.

What is a smart grid in wireless networks?
Answer: A communication-enabled electricity grid that monitors and optimizes energy distribution in real-time.