In the age of universal internet access, Wi-Fi is essential every day. Today, let's explore Wi-Fi speeds.
Routers currently on the market often claim wireless transmission speeds of 300Mbps, 450Mbps, or even higher. However, these are theoretical speeds! High speeds such as 1.75GHz advertised by some wireless routers refer to the theoretical Wi-Fi air interface speed. In reality, wireless speeds are affected by media, weather, transmit power, signal strength, line attenuation, and frequency of use, making it impossible to achieve the advertised speeds.
So how do these wireless routers achieve the high speeds they claim?
What factors contribute to this?
1. Wi-Fi speeds continue to improve with each new Wi-Fi protocol update
Wi-Fi speeds weren't always this impressive. The original theoretical wireless transmission rate was only 11 Mbps. It took several generations of upgrades to achieve the current level of speed.
Note: The theoretical air interface rate only indicates the rate value under ideal conditions and is not equal to the actual data transmission rate.
2. Wi-Fi speeds are further improved with the application of MIMO technology
The following table shows the theoretical air interface rates achievable by 802.11n/11ac at different spatial stream numbers:
The high speeds advertised by some dual-band routers on the market are calculated this way.
MIMO (multiple-input multiple-output) mentioned in the table above stands for Multiple-Input Multiple-Output. An antenna system consisting of m transmit antennas and n receive antennas enables signals to be transmitted and received via multiple antennas at both the transmitter and receiver ends, thereby improving communication quality. This fully utilizes spatial resources, enabling multiple transmissions and multiple receptions through multiple antennas. This significantly increases system channel capacity without increasing spectrum resources or antenna transmit power, demonstrating significant advantages and being considered a core technology for next-generation mobile communications.
3. Wi-Fi speeds are limited by the bandwidth provided by the carrier and the performance of the network card in the downstream device.
Currently, the broadband provided by service providers generally does not exceed 100 Mbps. Therefore, the 300 Mbps and 450 Mbps wireless transmission speeds we often talk about refer to transmission speeds within the local area network (LAN). Internet speeds primarily depend on the external network bandwidth (that is, the bandwidth provided by the service provider).
When a wireless device (such as a mobile phone or laptop) connects to a wireless signal, it negotiates a wireless transmission rate with the router. The higher the rate supported by the device's wireless network card, the higher the negotiated wireless transmission rate.
Currently, most mobile phone wireless network cards support speeds of 54Mbps or 72Mbps, while most laptops come with built-in wireless network cards that support 144Mbps. This means that even when connected to a 450Mbps wireless router, the theoretical maximum wireless transmission rate a laptop can achieve is 150Mbps.
In addition, the oldness of the wireless network card driver may also affect the wireless transmission rate! Generally speaking, this does not affect our Internet use. It will only be more obvious when the devices in the local area network transfer files to each other.
4. Wi-Fi speed is affected by Wi-Fi signal strength and quality.
Wi-Fi signal strength and speed are correlated; better signal strength results in higher speeds. Therefore, while 802.11ac improves speed, it also employs MIMO to enhance signal strength. Before each transmission, a channel measurement is performed. Based on the channel quality, an appropriate transmission rate is selected from the MCS table, enabling real-time rate adaptation.
The above is what we will introduce today about Wi-Fi speed.
