Why is the 802.11g Wi-Fi throughput speed on my smartphone slow?

Why is the 802.11g Wi-Fi throughput speed on my smartphone slow?

Recently purchased a smartphone with Wi-Fi (802.11g) but found video over Wi-Fi to be pretty choppy. I checked SpeedTest and I don't get anywhere near 54 Mbps when connected to Wi-Fi. Why not?

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Throughputs reported by Internet-based measurement tools like SpeedTest are influenced by many factors, including the target measurement server, your phone's Wi-Fi connection, and everything else in between.
Measure smartphone Wi-Fi throughput
To read more about smartphone Wi-Fi throughput measurement, see Lisa Phifer's Sprint HTC Hero review and Verizon Wireless Motorola DROID review.

For example, if your phone is connected to your home network's Wi-Fi router, and that router is connected to the Internet by a residential broadband service, SpeedTest could actually be measuring the download/upload capacity of your broadband connection. Broadband download speeds of 4-15 Mbps are not uncommon, even if your phone's Wi-Fi connection is actually operating at 54 Mbps.

Furthermore, when your phone's Wi-Fi is connected at a data rate of 54 Mbps, its maximum possible application throughput is actually far less. A typical 802.11g laptop client can experience sustained throughput of 25-30 Mbps if there is no Wi-Fi channel competition or RF interference. But the 802.11g chipsets used by smartphones don't always reach those speeds due to internal data transfer rate limitations, lower transmit power outputs, and less sensitive antennas. As a result, when you use Wi-Fi on a smartphone, throughput might increase noticeably as compared to 3G but still not top out anywhere close to 25 Mbps.

By the way, issues like power draw, size, and cost are also why smartphones have been slower to upgrade to 802.11n than laptops. However, new 1x1 802.11n chipsets designed for small footprint devices like smartphones are now emerging. For example, the new Atheros AR6003 chipset consumes 20% less power than the older AR6002, while reportedly achieving throughputs up to 48 Mbps in the 2.4 GHz band (20 MHz channel width) and 85 Mbps in the 5 GHz band (40 MHz channel width).

This was first published in December 2009