Update: Sunday June 2, 2013 Motorola has responded with the following analysis and explanation of the problem.

The Association Request from the Samsung Galaxy S4 phone has the RRM (Radio Resource Management/802.11k) capability element missing, but the Capabilities Info Bitmap in the Association Request says that the client can do RRM, so there is a mismatch and we deny association in WiNG4.x. In WiNG5.x, the RRM implementation is different and we don’t enforce such a strict check to avoid situations such as these where clients might not be following the 802.11k specification properly. In WiNG 3.x, there is no support for RRM, so there are no such checks enforced.

Thanks to Motorola for providing the quick analysis and explanation. Just to summarize the problem is not present in WiNG 3.x or WiNG 5.x but is definitely present in WiNG 4.x. As for a workaround or fix I’m still waiting to hear if Motorola will issue a patch (software release) or if they will leave it to Samsung and Google to resolve.

Update: Thursday May 30, 2013 It seems that the problem is not evident when the Samsung Galaxy S4 associates with a Motorola WS5100 (v3.3.2.0-010Ri) with AP300s as access ports.

It would seem that the recently released Samsung Galaxy S4 is having difficulty connecting to our public wireless network which is provided by a pair of Motorola RFS 7000 Wireless LAN Switches (v4.4.2.0-001R) with about 24 AP650s (v2.2-1592R). While I’ve personally observed this problem in our office, I’ve also received similar reports from users in our hospitals which are running RFS7000s with either AP300s or AP650s for Access Ports/Points.

Our public wireless network has no authentication or encryption, however, the Samsung Galaxy S4 will display “Authentication error occurred” when it tries to connect. I performed a quick wired packet trace on the captive portal server and found no frames with the associated MAC address of the Galaxy S4 so I setup WireShark with 3 AirPcap adapters, one for each channel in the 802.11b/g  2.4Ghz range, to perform a wireless packet trace.

I was able to observe the Galaxy S4 making repeating probe requests and association requests but every association attempt appears to fail with an Unspecified error. As a reference I also captured my Motorola Droid 3 connecting to our public network for comparison.

WireShark AirPcap Captures

• First run of Samsung Galaxy S4 – failed to connect
• Second run of Samsung Galaxy S4 – failed to connect
• Working run of Motorola Droid 3 – working

Looking at the wireless packet trace I can see where the Galaxy S4 is failing to associate to the network. In frame 341 we can see “Unspecified failure” in the Association Response from the Access Port. I’m not an expert here but I’m going to guess that there’s something in the Association Request that is causing the wireless infrastructure to choke on the response.

Looking at the last wireless packet trace of the working Motorola Droid 3 we can see that it quickly probes, associates and makes a DHCP request without any problems or issues.

My Thoughts

As I’ve mentioned before I’m no expert here but I can see quite a few additional tags in the Association Request from the Samsung Galaxy S4. I’m going to guess that it’s one of these tags that is causing the wireless infrastructure to choke. Looking at the screenshot below you can see all the tags.

I’m hoping some wireless experts can step up here, or perhaps Motorola with an explanation and workaround/fix?

Cheers!