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low energy wifi

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Low Energy Wi-Fi typically refers to a variant of the traditional Wi-Fi standard that is optimized for power consumption. The primary goal is to enable battery-operated devices to communicate over Wi-Fi for extended periods without requiring frequent recharging or replacement of batteries. This is particularly crucial for Internet of Things (IoT) devices, wearable devices, and other battery-powered applications where energy efficiency is paramount.

1. PHY (Physical Layer) Modifications:

  • Sub-GHz Operation: Low Energy Wi-Fi often operates in sub-GHz frequencies (e.g., 900 MHz) instead of the 2.4 GHz or 5 GHz bands commonly used in traditional Wi-Fi. Lower frequencies can propagate over longer distances and penetrate obstacles more effectively, potentially reducing the power required for transmission.
  • Narrower Bandwidth: To save energy, Low Energy Wi-Fi typically uses narrower channel bandwidths compared to traditional Wi-Fi. For instance, instead of 20 MHz or 40 MHz channels, it might use 1 MHz or 2 MHz channels, reducing the data rate but also decreasing power consumption.

2. MAC (Medium Access Control) Layer Enhancements:

  • Duty Cycling: Devices can enter low-power sleep modes and wake up periodically to check for incoming data or to transmit data. This duty cycling technique allows devices to conserve energy by spending more time in sleep mode.
  • Frame Aggregation: Instead of transmitting data in many small frames, Low Energy Wi-Fi allows for aggregating multiple frames into a single transmission. This minimizes the overhead associated with transmitting separate acknowledgment frames, thus saving energy.

3. Advanced Power Management:

  • Power Save Mechanisms: Low Energy Wi-Fi devices utilize advanced power-saving mechanisms. For example, they can negotiate sleep schedules with the access point (AP) or use techniques like Target Wake Time (TWT) to specify when they need to wake up to send or receive data.

4. Reduced Complexity:

  • Simplified Protocols: Low Energy Wi-Fi standards might simplify some of the complex protocols and features present in traditional Wi-Fi standards. By eliminating unnecessary features, the standard reduces both computational complexity and power consumption.

5. Trade-offs:

  • While Low Energy Wi-Fi offers advantages in terms of power efficiency, it often comes with trade-offs such as reduced data throughput, limited range due to lower frequencies, and potential compatibility issues with existing Wi-Fi infrastructure.

Standards and Protocols:

Several standards and protocols aim to achieve low-power Wi-Fi communication. Examples include:

  • Wi-Fi HaLow (IEEE 802.11ah): Designed for IoT and operates in the sub-1 GHz spectrum.
  • Wi-Fi 6 (802.11ax) Power Save: While not strictly a low-energy standard, Wi-Fi 6 introduces power-saving features that improve energy efficiency compared to previous Wi-Fi generations.