Question

As a mobile node gets farther and farther away from a base station, what are two actions that a base station could take to ensure that the loss probability of a transmitted frame does not increase?

Short answer

Increase transmission power and use error correction codes to reduce loss probability.

Step-by-step solution

Understand the Problem Context

A mobile node is a device, like a cell phone, that communicates with a base station, such as a cell tower. As the mobile node moves away from the base station, the signal can weaken, increasing the chance of transmission errors or lost frames. We need to identify actions that a base station might take to mitigate this issue.

Action 1 - Increase Transmission Power

One approach a base station can take is to increase its transmission power. By boosting the signal strength, the base station can maintain adequate communication quality with the mobile node even as it moves farther away. This ensures that the signal can reach the mobile node with sufficient strength to reduce the loss probability of the transmitted frame.

Action 2 - Adjust Coding and Modulation Schemes

Another approach is for the base station to employ more robust error correction codes and adjust modulation schemes. By using stronger error correction algorithms or reducing the data rate, the base station can ensure that frames are less likely to experience errors during transmission even at longer distances, thereby maintaining low loss probability.

Key concepts

Base Station

In mobile communication, the base station serves as a critical component in maintaining connectivity between mobile devices and the network. Think of it like a large tower you might see when driving on the highway. These towers are responsible for handling voice calls, text messages, and data traffic.
Base stations facilitate communication by transmitting and receiving signals to and from multiple mobile devices within a specific area, known as the cell. As such, they play a pivotal role in ensuring mobile users remain connected, especially when moving from one place to another. To manage network traffic effectively and adjust to varying signal demands, base stations utilize sophisticated technologies and algorithms.

• Acts as a transmitter and receiver between mobile devices and the network.
• Ensures efficient communication through coverage of designated areas.
• Adapts to changing environmental conditions and user movements.

Signal Strength

Signal strength is a measure of how well a mobile device is receiving signals from a base station. Imagine the signal strength like the volume of a conversation--it needs to be loud enough for clear communication.
When a mobile device is far from a base station, the signal weakens, similar to how a voice becomes softer as you walk away from someone. To maintain a strong connection, the base station might alter the signal strength to reach distant devices.
Factors affecting signal strength include distance from the base station, obstacles like buildings or trees, and even weather conditions. It's vital for maintaining call quality and data speeds, ensuring users enjoy seamless mobile service.

• Represented by bars on a phone or a numerical value.
• Influenced by physical obstructions and network load.
• Essential for maintaining clear and uninterrupted communication.

Transmission Power

Transmission power refers to the amount of power a base station uses to send signals to mobile devices. A stronger transmission power is like speaking louder to make sure everyone can hear you.
When a mobile node (e.g., your smartphone) moves away from a base station, the station might increase its transmission power. This ensures that the signal reaches the device with enough strength to sustain the connection and reduce the risk of losing transmitted data or voice signals.
However, setting transmission power is a balancing act. If too high, it can interfere with other signals and waste energy. Therefore, base stations adjust power levels to meet current demands effectively.

• Enhances signal reach and connectivity over longer distances.
• Helps overcome signal degradation due to distance and obstacles.
• Requires careful management to avoid interference and energy waste.

Error Correction

Error correction is crucial in ensuring data sent over wireless networks is received accurately, even when imperfections occur. Think of it as proofreading a document to catch and fix typos before submission. In mobile communication, this process involves encoding data with additional information that helps in detecting and correcting any errors encountered during transmission.
When a base station needs to communicate over long distances or through challenging environments, robust error correction schemes might be employed to ensure information integrity. This reduces the likelihood of retransmissions, enhancing efficiency.
Common error correction techniques include:

• Parity checks, which add simple checksums to identify errors.
• Forward Error Correction (FEC), which corrects errors without needing retransmission.
• Cyclic Redundancy Checks (CRC), used in conjunction with other methods to ensure data accuracy.

Modulation Schemes

Modulation schemes in mobile communication are akin to different ways of packaging and sending parcels. Each scheme optimizes how data is transmitted over radio waves from the base station to mobile devices.
By altering the amplitude, frequency, or phase of a signal, modulation schemes ensure that information is efficiently and effectively transmitted, even over vast distances.
Adapting modulation schemes based on network conditions allows continued high-quality communication by balancing speed and reliability. For example, a simpler modulation might be chosen in weaker signal conditions to ensure the data gets through accurately, albeit at a potentially lower speed.

• Key schemes include Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM).
• Advanced techniques, like Quadrature Amplitude Modulation (QAM), combine adjustments in amplitude and phase for higher data rates.
• Dynamic adaptation of schemes helps manage varying quality and coverage challenges.