Saturday, 4 May 2013

Samsung Galaxy S4 WiFi Capabilities


With all of the excitement around 802.11ac that is currently unfolding, I was very interested to hear about the support for 11ac by the recently released  Saumsung Galaxy S4. Having a quick scan of the reviews across the web about the new handset, I was intrigued to see claims that it supports 802.11ac, allowing speeds up to 1.3Gbps! Feeling a little sceptical that it would support anything close to those speeds, I did a bit of digging to see what I could find.

My first port of call was a product tear-down over at TechInsights.com. They revealed that the WiFi chip in the S4 is the Broadcom BCM4335


A quick look around the Broadcom site soon revealed the product page for the BCM4335, with an overview of the chipset specification. In summary, it supports:

  • Single stream IEEE 802.11ac solution with data rates up to 433.3 Mbps
  • Full IEEE 802.11a/b/g/n legacy compatibility with enhanced performance
  • Supports 20, 40, and 80 MHz channels with optional SGI (256 QAM modulation)
  • The BCM4335 features advanced idle power consumption performance, which significantly extends mobile device's battery life
  • Broadcom's TurboQAM™ technology implements the highest data-rate 256-QAM mode in 2.4 GHz and enables devices equipped with the BCM4335 to deliver 10 percent faster throughputs than 802.11n speeds when communicating with other 5G WiFi devices
  • Key high-throughput mobility interfaces, including SDIO 3.0, PCIe and HSIC, make it suitable for smartphone, tablet and computing platforms
  • Advanced beamforming (IEEE 802.11ac/n), Low-Density Parity Check (LDPC) code and Space-Time Block Code (STBC) support for better coverage and more reliable connectivity
  • Built-in media processing to off-load host processor
  • Integrated support for Wi-Fi Direct™, Wi-Fi Certified Miracast™ and Wi-Fi Certified Passpoint™ technologies
Some very interesting facts and figures here, but this pretty much quashed the outlandish claims in some articles around the 1.3Gbps top speed, as the chipset cannot go beyond 433mbps.Even so, these potential performance gains over other non-11ac handsets are very impressive. 

Although the chipset itself may support up to 443.3 Mbps, primarily through the 80Mhz-width channel capability, this doesn't mean that the Samsung implementation has actually taken advantage of the full 80Mhz channel width. I still needed more information to find out what the S4 itself was actually capable of.
 
The next stop was the FCC web site (A3L/GTI9505 if you want to take a look yourself) to have a look to see if I could see what speeds and channel widths had been tested during the FCC approval testing process.  


The WLAN testing report shows that the handset was tested on both 2.4GHz (802.11b/g/n) and 5GHz (802.11a/n/ac). Interestingly, it was tested up to 433.3mbps, using an 80Mhz width channel! 


There were also some interesting power levels presented, which seem to suggest that the transmit power level of the device was averaging around 11-13dBm on 5GHz, depending on the data rate and channel. On 2.4GHz, it looks like it has a slightly higher power output, showing figures averaging 12-15dBm.

So, in summary, the S4 is a single stream device, supporting up to 80MHz channels (for 802.11ac ) and has a top speed of around 433Mbps. Don't forget
 these figures will assume ideal conditions (i.e. short guard interval, close proximity to AP, good SNR values etc.), and that these are connection speeds, not throughput speeds that you would see when transferring data. Actual throughput is likely to be a little over half of the top-speed of 433Mbps. 

Also, don't forget that 802.11ac is only supported on the 5GHz band. If you are using it on 2.4GHz, the best you are going to get is the top speed for a single stream 802.11n device  on a 20MHz channel (around 72Mbps connection speed).

All we need now are some 802.11ac APs to use the S4 with :)