How is Wi-Fi HaLow different from traditional Wi-Fi?
2024-10-11 09:36:55
ANJIELOSMART Wi-Fi HaLow is essentially a low-power, long-range, versatile version of Wi-Fi that operates on the license-free 1 gigahertz spectrum. The Wi-Fi HaLow standard combines energy efficiency, long-range connectivity, low latency, HD video quality data rates, security features and native IP support, making it the ideal protocol choice for wirelessly connected, battery-powered IoT devices. Let’s look at some of the key differences between Wi-Fi HaLow and traditional Wi-Fi, and why the 802.11ah protocol is well suited to the connectivity requirements of IoT applications.
| Function | wi-Fi 4/5/6(IEEE 802.11n/ac/ax) | Wi-Fi HaLow（IEEE 802.1lah) |
| Operating frequency band | 2.4 GHz, 5 GHz, 6 GHz | Sub-1 GHz(902 -928 MHz in the USA) |
| Channel width selection | 20.40.80.160 MHz | 1,2,4,8,(16 optional) MHz |
| Maximum number of addressable sites per access point | 2007 | 81989 |
| Single stream MCS data rate range | 6.5 Mbps-150 Mbps(11n. Wi-Fi 4) | 150 Kbps - 86.7 Mbps |
| usual range | about 100 meters | More than 1 km;10 times farther range;100 times wider area;1000 times larger capacity(compared to 802.11n 20 MHz) |
| Link budget improvements (1 MHz channel) | _ | 15-24dBm |
A power-saving protocol
ANJIELOSMART Wi-Fi HaLow provides excellent energy efficiency for power-hungry IoT devices. The various complex sleep modes specified by IEEE 802.11ah enable HaLow devices to be in an extremely low power state for a long time, saving battery energy:
Target wake time (TWT): This allows stations (STA) and access points (AP) to pre-arrange a time for sleeping stations to wake up and listen for beacons.
Restricted access window (RAW): An access point can grant permission to a subset of stations to transmit their data, while other stations are forced to sleep, buffer non-urgent data, or both.
Extended maximum Basic Service Set (BSS) idle period: This extends the site's "allowed idle period" to five years.
Hierarchical Traffic Indication Mapping (TIM): Group and encode TIM more efficiently to save beacon transmission time.
Short MAC header: This reduces header overhead, transmission time and power consumption, and frees up spectrum.
Null Data PHY Protocol Data Unit (NPD): This embeds MAC-like ACKs/NACKs into the PHY layer to reduce time and power consumption.
Short Beacons: Short (limited) beacons are sent frequently to synchronize sites, while full beacons are sent less frequently.
BSS coloring mechanism: Color assignment represents the BSS group of a specific access point, while stations can ignore other colors.
Bi-directional TXOP (BDT: Bi-directional TXOP) (formerly Speed Frame): This reduces the number of medium accesses when a station wakes up and sees the presence of uplink and downlink frames for transmission. BDT uses a response indication in the Signal (SIG) field of the Physical Layer Protocol Data Unit (PPDU) to add TXOP duration protection to third-party station transmissions.
The protocol’s efficient sleep and power management modes enable IoT devices to run on batteries for years, as well as multiple flexible power and battery size options, from coin-cell batteries for short-range IoT devices, to higher powers transmitting over a kilometer. , applications using larger batteries. Compared with Wi-Fi protocols in the 2.4 GHz and 5 GHz frequency bands, the sub-GHz narrowband signal used by this protocol has a longer transmission distance and lower energy consumption, allowing more data to be transmitted per unit of energy consumption.
As a result, ANJIELOSMART Wi-Fi HaLow chips require only a fraction of the power of traditional Wi-Fi chips. While the higher data rates of traditional Wi-Fi allow users to quickly transmit high-definition video and download large files using wideband channels in the 2.4 GHz, 5 GHz and 6 GHz bands, these Wi-Fi connections have a short range and battery Drains quickly and requires frequent recharging or battery replacement, or preferably a mains connection. For these reasons, Wi-Fi HaLow is a better choice for power-constrained IoT devices that need to reach greater distances and run on batteries for years while still delivering high data throughput.