Signal-to-Noise Ratio (SNR)

Owned by Patrick H
Last updated: Oct 11, 2023

When Vivi is deployed in classrooms and connected via Wi-Fi, it is crucial to maintain a high-quality network connection to enable a high-quality wireless screen mirroring experience. Occasionally, IT admins may encounter issues with Wi-Fi connections related to low Signal-to-Noise Ratio (SNR), which can impact the performance of the Vivi hardware device. This knowledgebase article aims to provide IT admins with an understanding of SNR, signal strength, and background noise/interference, along with troubleshooting steps to address low SNR issues effectively using the tools provided within Vivi Central. 

Understanding SNR 

The Signal Strength and the Noise are used to calculate the SNR which is a measure of the strength of the signal relative to the background noise level. SNR is a critical metric for ensuring clear and stable wireless connectivity for Vivi in classrooms. Higher SNR values indicate a stronger and more reliable signal, while lower SNR values may result in connectivity issues and poor screen mirroring performance. 

Signal Strength refers to the power of the wireless signal received by the Vivi device from the network. It is typically measured in decibels (dBm) and represents the intensity or amplitude of the wireless signal. A stronger signal strength implies a more robust connection and better SNR. 

Noise represents any interference or background radio frequencies that can degrade the quality of the wireless signal. Common sources of noise in a classroom environment may include other wireless devices, electronic equipment, or physical obstructions. 

Antenna Diversity and Placement 

Each Vivi device is equipped with two antennas, which are positioned to achieve antenna diversity. Antenna diversity allows for improved signal reception by leveraging the strengths of both antennas. To optimise SNR and signal strength, it is generally recommended to position the antennas at a 45-degree angle or 90-degree angles from each other depending on your environment.

Positioning

  1. Extend and orient both antennas of the Vivi device at 45-degree angles or at 90-degrees from each other for optimal performance. 

  2. Avoid blocking or obstructing the antennas with physical objects or materials. 

High-Density Wi-Fi Environments  

Schools often operate in high-density Wi-Fi environments, where multiple devices simultaneously connect to the network. These environments can present challenges that impact SNR and overall network performance. Here are some considerations: 

  1. Wi-Fi Channel Selection

    • In high-density environments, neighbouring Wi-Fi networks may interfere with each other. Choose Wi-Fi channels with minimal interference and overlap. 

  2. Access Point Placement

    • Strategically position access points throughout the school to ensure even coverage and minimise signal interference. 

    • Evaluate the number and placement of access points based on the school's layout, size, and expected device density. 

  3. Bandwidth Allocation

    • In high-density environments, distribute available bandwidth effectively to ensure fair and sufficient connectivity for all devices. 

    • Configure Quality of Service (QoS) settings to prioritise Vivi traffic to ensure a smooth screen mirroring experience. 

Optimising SNR and Performance 

  1. Utilise 5GHz Wi-Fi

    • Connect Vivi devices to a 5GHz Wi-Fi network whenever possible to take advantage of higher bandwidth and reduced interference compared to 2.4GHz networks. 

  2. Separate SSIDs for 2.4GHz and 5GHz

    • Set up separate SSIDs for the 2.4GHz and 5GHz networks to enable Vivi devices to connect directly to the desired 5GHz band. If you have a dedicated SSID for Vivi, then consider only enabling only one of these frequencies.

  3. Band Steering

    • Implement band steering functionality on the Wi-Fi network infrastructure to encourage devices to connect to the 5GHz network automatically. 

    • Band steering directs capable devices, such as Vivi devices, to connect to the 5GHz band, optimising performance and SNR. 

  4. Line of Sight and Placement

    • Ensure that the Vivi device has a clear line of sight to the access point (AP). Avoid placing the device behind objects, such as TVs or furniture, that may obstruct the wireless signal. 

    • Consider repositioning the Vivi device to a location that provides direct visibility to the AP, minimising obstructions and improving signal reception. 

  5. Reduce Interference and Noise

    • Minimise sources of interference and noise in the classroom environment that can degrade the wireless signal. 

    • Keep Vivi devices away from other electronic equipment, such as microwave ovens or cordless phones, that can cause signal interference. 

    • Avoid placing Vivi devices near walls or metal objects that may reflect or block the Wi-Fi signal. 

  6. Regular Maintenance and Monitoring

    • Continuously monitor the performance of Vivi devices using Vivi Central's analysis tools to identify any fluctuations in SNR or signal strength. 

    • Conduct periodic site surveys to assess coverage, identify dead zones, and make necessary adjustments to optimise the Wi-Fi environment. 

Reference SNR Benchmarks 

It's important to assess the SNR values to determine the quality of the wireless connection.  

Vivi follows the following SNR benchmarks for reference: 

  • SNR 40+: Good signal quality with excellent performance and reliability. 

  • SNR 25-40: Average signal quality that should still provide satisfactory performance. 

  • SNR below 25: Poor signal quality with a higher likelihood of experiencing connectivity issues and degraded screen mirroring performance. 

Monitoring and Troubleshooting 

To effectively troubleshoot and address low SNR issues, utilise the analysis and monitoring tools available in Vivi Central. These tools allow IT administrators to monitor SNR values, signal strength, and other relevant metrics for each Vivi device deployed in the classroom. By regularly monitoring the performance, IT administrators can identify fluctuations in SNR and take necessary steps to optimise the Wi-Fi environment.