The bandwidth of 802.11ac (Wi-Fi 5) is variable and depends on the specific hardware, configuration, and environment.
The theoretical maximum data rate can reach nearly 7 Gbps, but this is rarely achieved in real-world conditions. Typical real-world speeds are significantly lower, ranging from 100 Mbps to over 700 Mbps.
What is 802.11ac?
Introduced in 2013, 802.11ac is a wireless networking standard, also known as Wi-Fi 5, that significantly improved upon its predecessor, 802.11n (Wi-Fi 4). It operates exclusively in the less-crowded 5 GHz frequency band to deliver higher speeds, greater capacity, and enhanced performance, especially for streaming and other high-bandwidth applications.
The bandwidth improvements in 802.11ac were achieved through several key enhancements over previous Wi-Fi standards:
Wider channels
802.11ac increased the available channel bandwidth to allow more data to pass through simultaneously.
- Wider channel options: The standard supports channel widths of 20, 40, 80, and 160 MHz, up from the 20 and 40 MHz options in 802.11n.
- Contiguous and non-contiguous channels: In addition to bonding adjacent channels to create a 160 MHz channel, Wave 2 devices can also bond two non-adjacent 80 MHz channels (80+80 MHz).
- Wave 1 vs. Wave 2: The initial Wave 1 devices supported a maximum channel width of 80 MHz, while later Wave 2 devices extended this to 160 MHz.
More spatial streams
MIMO technology uses multiple antennas to send and receive data simultaneously, and 802.11ac significantly increased the number of streams.
- Stream count: While 802.11n supported up to four spatial streams, the 802.11ac standard expanded this to eight, doubling the potential throughput.
- Hardware limitations: The actual number of spatial streams used in a network depends on the hardware of both the access point and the client device. Many access points support 2x2 or 4x4 streams, and most client devices, such as smartphones, are typically 1x1.
Higher modulation density
Quadrature Amplitude Modulation (QAM) is a method for encoding data onto radio waves. 802.11ac improved upon this technology to increase data transfer rates.
- Modulation increase: 802.11ac uses 256-QAM, an improvement over 802.11n's 64-QAM, allowing it to squeeze 256 different signals onto one frequency by shifting and twisting each into a slightly different phase.
- Throughput improvement: This higher-density modulation can provide up to a 33% increase in data transfer rate over 802.11n, especially over shorter distances with strong signal strength.
Multi-User MIMO (MU-MIMO)
A feature introduced with 802.11ac Wave 2, MU-MIMO allows an access point to communicate with multiple client devices at the same time.
- Efficient broadcasting: Instead of serving one device at a time, MU-MIMO can create and serve separate data streams to up to four client devices simultaneously, which increases overall network capacity and efficiency.
- Downlink only: In 802.11ac, MU-MIMO is limited to the downlink (from the access point to the clients).
Performance in the real world
While the theoretical bandwidth of 802.11ac is impressive, real-world performance is often lower due to several factors.
- Hardware compatibility: Achieving the highest speeds requires both the router and the client device to support the same advanced features, such as 160 MHz channels and multiple spatial streams.
- Environmental factors: Interference from physical obstacles like walls and furniture, as well as other wireless devices, can significantly slow down speeds.
- Wi-Fi congestion: As a shared medium technology, performance can degrade in crowded environments with many competing networks.
- Half-duplex communication: Wi-Fi is a half-duplex technology, meaning it can only transmit or receive data at a given time, not both simultaneously. This further reduces the achievable throughput.
Comparison with other standards
802.11ac has since been superseded by newer standards like 802.11ax (Wi-Fi 6) and 802.11be (Wi-Fi 7), which offer even greater bandwidth and efficiency.
- 802.11ax (Wi-Fi 6): Supports higher theoretical maximum speeds (up to 9.6 Gbps), operates on both 2.4 GHz and 5 GHz bands, and introduces advanced features like OFDMA to improve performance in high-density environments.
- 802.11be (Wi-Fi 7): Operates on the 2.4, 5, and 6 GHz bands with significantly higher speeds, wider channels (up to 320 MHz), and Multi-Link Operation (MLO).