This is a common and great question. Simply answered, a wider channel in Wi-Fi results in higher bandwidth and throughput because it allows more data to be transmitted simultaneously.
Here’s a breakdown of why:
Channel Width and Frequency Space
- Wi-Fi transmits data over radio frequency channels.
- Each channel has a specific width: 20 MHz, 40 MHz, 80 MHz, 160 MHz or 320 MHz.
- Wider channels occupy more frequency spectrum, which provides more capacity for data transmission.
More Subcarriers = More Data Streams
- Wi-Fi uses something called Orthogonal Frequency Division Multiplexing (OFDM) or OFDMA in newer standards.
- Wider channels allow more subcarriers, each capable of carrying a part of the data.
- Example:
- A 20 MHz channel may use 64 subcarriers.
- An 80 MHz channel may use 256 subcarriers.
More specifically, in a 20 MHz channel, there are 64 subcarriers, with 52 used for data transmission and 12 unused (pilot and null). In an 80 MHz channel, there are 256 subcarriers, with 234 used for data transmission and the remainder unused.
More subcarriers = more parallel data streams = higher throughput.
Higher Theoretical Data Rates
Not to worry – you won’t see these. Think of them as potential because every Wi-Fi environment is different and unique.
- The theoretical PHY data rate increases with channel width.
- For example, in Wi-Fi 6 (802.11ax):
- 20 MHz: up to ~286 Mbps per spatial stream.
- 80 MHz: up to ~1.2 Gbps per spatial stream.
- 160 MHz: up to ~2.4 Gbps per spatial stream.
Caveats
As hinted above, every environment and radio therein is going to be unique.
- Interference increases with wider channels due to overlapping with other networks.
- Wider channels may not always be practical in crowded environments (e.g., apartment buildings).
- Some devices or regulatory domains limit the use of 80 MHz or 160 MHz.
In Summary
Generally speaking, wider Wi-Fi channels provide more frequency space, allowing more subcarriers and data streams, which increases the total bandwidth and throughput — assuming conditions allow efficient use.
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