Tuesday, September 13, 2011

Why Serval is getting involved in the 802.11ah standards process

Serval is getting involved in the IEEE 802.11ah (WiFi on ISM bands below 1GHz) to try to make sure that it is well suited to infrastructure-independent ad-hoc and mesh networking at the IEEE meeting in Okinawa next week.

Here is our submission:


Basically we are asking for two things:

1. Improvements to ad-hoc mode (or provision of a new "packet radio" mode) that remove some of the problems currently faced when creating wifi-based ad-hoc mesh networks.


2. That the 802.11ah standard consider speeds below 1mbit and using cell phone baseband radios as a supported transport so that even cheap cell phones can form relatively long range mesh networks without any supporting hardware.

This second point is really important, because compared with 2.4GHz WiFi a mesh running in the ISM 915MHz band gains about +9db just from the change in frequency, which alone improves range by almost 3x.  If it supports lower bit rates, then further significant gains are possible, e.g., allowing 100kbit communications gives another +10db, for a total of 8x range versus WiFi.

There are some significant protocol challenges to be addressed, but if the standard doesn't support the use-case, then there will be no hardware and no chance.

These measures have the potential to push the indoor range up from WiFi's "about one house wide" to "about a block wide" and clear line-of-sight range up to a few km, which suddenly makes the formation of suburban ad-hoc mesh networks possible, which has profound impact for creating resilient infrastructure-independent communications solutions, for example for sustaining communications during disaster or enabling communications for rural and remote or developing populations.

We admit that we are very green to this process which we frankly find to be daunting.

But we feel compelled to try, regardless of what we perceive to be the odds of success.

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