Marriott wifi blocking

Tue Oct 7 12:05:48 UTC 2014

On Oct 6, 2014, at 11:53 AM, Clay Fiske <clay at bloomcounty.org> wrote:

> 
> On Oct 6, 2014, at 8:41 AM, Owen DeLong <owen at delong.com> wrote:
> 
>> 
>> Actually, in multiple situations, the FCC has stated that you are responsible
>> when deploying a new unlicensed transmitter to insure that it is deployed in
>> such a way that it will not cause harmful interference to existing operations.
> 
> I recognize that you were making this statement in the context of colliding SSIDs, but to me this could be an interesting point in another way.
> 
> Suppose from Marriott’s perspective that your personal wifi network is interfering with the throughput of their existing network. After all, if you fire up your personal AP, with a non-colliding SSID, and start downloading multi-GB files, that’s bound to impact[1] anything else using that channel. While there are at least a few non-overlapping channels on most wifi networks, if Marriott(’s third party network operators) had any sense they likely would have situated their APs and channels to provide the most range with the least amount of frequency overlap. Now here your personal AP on one of those channels consuming enough of its bandwidth to significantly degrade performance for anyone else, and they may not have access to (or usable signal strength or bandwidth on) another channel from their hotel room.

The FCC has specifically stated that sharing of the spectrum bandwidth in this manner is not considered “harmful interference” in at least a few rulings. This is the “normal and expected result of deployment of multiple networks onto limited spectrum”.

> During a big convention for example, the hotel network is probably at its busiest while the number of guests using personal APs is likely also at its peak. This may be a stickier case, as no one user is causing the issue but one could make the case that, in aggregate, they are very much interfering with existing operations.

Yes, but not in a manner the FCC fits into the definition of “harmful interference” under 15.3 and/or 15.5.

> There are probably a couple of different angles to consider, but I’m thinking in terms of the “first come, first served” concept. At what point is the extra bandwidth consumed by your personal wifi network considered to be harmfully interfering with an existing network?

It isn’t (unless you run afoul of 47CFR333 and are consuming bandwidth for the sole purpose of denying it to others).

> FWIW I am not defending Marriott’s actions, nor even positing that this was the reason for them. I just want to gain understanding.

Yep. Understood. Hope the above helps.

> -c
> 
> [1] This is of course assuming you’re getting decent throughput from your 3G/4G provider’s network. But even though it’s almost certainly slower than wifi it’s probably generating enough packets in a collision-based medium to impact other flows.

Actually, I usually get better 4G service on my LTE devices than I get from most hotel WiFi networks. It’s one of the reasons I wish Apple would let me choose the interface preference order rather than locking me to “if Wifi is on and can find an AP, then I won’t use LTE”.

Owen