WiFi HaLow: Advantages and Disadvantages (IEEE 802.11ah)

This page explores the pros and cons of WiFi HaLow (IEEE 802.11ah), outlining its benefits and drawbacks.

What is WiFi HaLow (IEEE 802.11ah)?

Introduction: Traditional WiFi standards aren’t always the best fit for IoT applications because they tend to consume a lot of power and have a larger frame overhead. To address this, the WiFi Alliance developed WiFi HaLow, designed for lower power consumption and a longer operating range. It’s defined under the IEEE 802.11ah standard.

IEEE 802.11ah operates in the sub-GHz band (around 900 MHz). It has different PHY and MAC layer designs, making 802.11ah hardware more power-efficient compared to previous WiFi generations.

Here are some technical features of WiFi HaLow, as defined in the 802.11ah standard:

• Frequency Band: 900 MHz (US), 850 MHz (Europe), 700 MHz (China)
• Bandwidth: 1, 2, 4, 8, 16 MHz
• Modulation type: BPSK to 256 QAM
• Channel Architecture: SC, OFDM
• Maximum Data Rate: 40 Mbps
• Coverage range: Approximately 1 Km
• Max. transmit power: 100 mWatt
• Security: WPA

For more detailed information, refer to a WiFi HaLow basics resource, which describes the functions of the PHY and MAC layers defined in IEEE 802.11ah.

Benefits or Advantages of WiFi HaLow

Here are the key benefits of WiFi HaLow:

• Low Power Consumption: It consumes less power than traditional WiFi, allowing devices with coin cell batteries to operate for months or even years.
• Extended Range: It offers a longer coverage range, reaching about 1 Km – almost double that of traditional WiFi.
• Improved Penetration: The WiFi HaLow signal penetrates walls and other obstacles more easily because its lower frequency (900 MHz) compared to the higher frequencies (2.4 GHz/5 GHz) used by traditional WiFi.
• No Proprietary Hubs: It doesn’t require any proprietary hubs or gateways.
• Reliable Wireless Link: It offers a more reliable wireless connection due to the use of a less congested frequency band, coupled with higher sensitivity and link margin.
• Ideal for IoT: WiFi HaLow is well-suited for the short, bursty data common in IoT (Internet of Things) applications. It doesn’t consume excessive power and can transmit data over longer distances. This makes it useful for smart building applications like smart lighting, security, parking, HVAC, and even for smart cities.
• High Device Density: The MAC layer is designed to support thousands of connected devices. A single WiFi HaLow Access Point (AP) can support up to 8191 devices.
• Cellular Offloading: It can be used for offloading cellular traffic because of its extended outdoor range.
• Reduced Interference: The sub-GHz frequency used in 802.11h experiences less interference compared to the crowded 2.4 GHz band.

Drawbacks or Disadvantages of WiFi HaLow

Despite its advantages, WiFi HaLow has some drawbacks:

• Lack of Global Standard: There’s no global standard for the 900 MHz band like there is for 2.4 GHz. WiFi HaLow is currently more US-centric.
• Larger Antennas: Antennas in the sub-GHz range are generally larger than those used in 2.4 GHz WiFi systems.
• Potentially Higher Latency: WiFi HaLow might have higher latency compared to some other IoT protocols, making it less suitable for applications that require real-time communication.
• Spectrum Availability: The availability of sub-1 GHz spectrum varies by country, which could limit the global applicability of WiFi HaLow. Regulatory differences can impact the deployment and performance of WiFi HaLow networks.
• Limited Device Support: As a newer standard, WiFi HaLow has limited support in consumer devices. Many existing IoT devices might not be compatible, which could slow down adoption.
• Power Consumption Compared to Other LPWANs: Although designed for low power consumption, it may still consume more power compared to other low-power wireless technologies like Zigbee or Bluetooth Low Energy (BLE), which are specifically designed for very low energy usage.
• Security Concerns: As with any wireless technology, security is a concern. Ensuring robust security measures in low-power IoT devices can be challenging, and vulnerabilities in WiFi HaLow could be exploited if not properly addressed.

Conclusion

Overall, WiFi HaLow (IEEE 802.11ah) offers a promising solution for various IoT applications, offering significant advantages like extended range, low power consumption, improved penetration through obstacles, and high device density support. These features make it particularly suitable for large-scale deployments in smart cities, industrial IoT, and agricultural monitoring.