Miscellaneous HSMM

For those not aware, a normal 802.11 channel is about 20 MHz wide.



The Atheros Chipset used in some of the professional grade 802.11/Wifi products (like Ubiquiti) can support half (10 MHz) and quarter rate (5 MHz) channel widths.



Obviously the maximum data rate (normally 54 Mbps for a conventional 20 MHz wide channel) drops, but even at quarter rate is still very usable with a maximum data rate of 13.5 Mbps.

The open Atheros driver talks directly to the hardware abstraction layer (HAL), and is also capable of frequencies outside of the Part 15 band.

[For a while no open source HAL's existed that can let you do 5/10 MHz mode. You had to use MikroTik, StarOS, IkarusOS, DD-WRT and a few others for these modes. As of June 2010, it appears that 5/10 Mhz support seems to be implemented in ath5k now.]

You can see the feasible channel selection overlay here:
http://www.qsl.net/kb9mwr/projects/wireless/allocations.html
The channels in light blue fall into overlapping amateur band space. And are acceptable for HSMM operation.

As you can see you can squeeze seven 5 MHz wide channels below the first Part 15 channel on 2.4 GHz, two of which are completely outside of the Part 15 overlap. (Thus, should have quieter noise floors)

On the 5 GHz band, there are thirteen channels that are completely outside of the Part 15 overlap.

And even more interesting is that that within the Atheros chip it is possible for licensed developers to enable a local oscillator generation for a direct conversion radio transceiver. This is Not an open function, but irregardless, this is how 802.11 products on 900 MHz (Ubiquiti XR9), and 3 GHz (XR3) (as well as other places) are possible and on the market.

Open source drivers unlocked the possibility of additional frequency support. It allows programmers to be able to write a driver. In summary; Atheros has allowed a third party to create a layer between the low-level functions of its chips and high-level drivers via the madwifi/ath5k development.

So what about unlocking additional channels in other chipsets/hardware?

Broadcom is the the chipset of most common Linksys WRT54G routers.

Broadcom has for a long time declined to provide non-licensed access to it's chips. A project that has been working to reverse engineer access using legal means had released its first working drivers for Broadcom 4300 series chips a few years ago.

If you are into the nitty-gritty, a recently released (2010) Broadcom wireless driver seems to have structures which imply the PHY in the chips can be directly controlled to program HSMM channels.

Also see:
http://lwn.net/Articles/456762/

http://linuxwireless.org/en/users/Drivers/brcm80211

For a slightly less technical overview of the various aspects of Modifying Consumer Off the Shelf Wireless LAN devices for specialized Amateur use, have a look here:
http://www.qsl.net/kb9mwr/projects/wireless/modify.html

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I was recently asked my opinion about the use of Amateur Radio Networks like HamMesh, HamWan and BCWarn.

The question is pretty generic.  It all seems to stem from the ARRL HSMM working group from a number of years ago.  Despite that group falling apart, independently amateurs all over the place have embraced the technology.  It's great in my opinion.  As interest in voice  repeaters continues to wane, multi-media networks do make perfect sense.  These more modern types of networks have the potential to draw new blood into the hobby.  New hams who have software skills that can help the community with software defined radio and so forth.

Outside ham radio, as consumers were now live in a world where to keep thing interesting and new we have a flexible application space.  Be that apps on our phones, software on our PCs, and even firmware updates to our more hardware like devices.

That that has been notable absent in ham radio.  I.e. What it is when you buy it, is what it will be 5 years from now unless you want to totally replace it for the tune of several hundred dollars.

Ham radio used to be a good starting place for many who later entered broadcast and electronics careers.  Today those positions are few and far between due to disposable electronics and consolidation of engineers with mega broadcast groups.  What is the most notable/abundant "tech" career today is IT (information technology) work.

In my humble and simple opinion: These types of networks are long over due, and I am glad they are continuing to grow.  It helps ham radio stay relevant.

73'
Steve, KB9MWR
 

70 CM HSMM?

What you are looking at is Ubiquiti's 2.4 GHz bullet. It's their simplest, and cheapest ($40) 802.11 device. It's basically a ethernet->N converter. Now imagine if it was capable of 420-450 MHz.  (Realistically something for this band would likely first start off in a mini-PCI configuration.)

Ubiquiti products are based on the Atheros chipset which allows you to reduce your channel width with to 5 MHz. This would fit in the lower 12 MHz of the band where ATV is allowed, and can still yield up to a 10 Mbps signaling rate. That kind of throughput can support live video feeds from IP cameras, Asterisk / IP telephony, and just about anything you can dream up.

When WiMAX platforms for operation around 3 GHz were in their planning stage, Ubiquiti acted quickly to provide a 3 GHz 802.11 solution for direct competition. That worked out well for us hams, as there is a 3 GHz ham allocation.    

WiMAX is much like ordinary Wifi except it uses licensed spectrum. Its for last mile connectivity, and the potential of mobile operations. Verizon wireless broadband is probably the most best example that most might be familiar with.
There are certified WiMAX platforms emerging for operation between 400-1000 MHz, covering the 70 and 33 cm bands, with selectable channel widths from 1.5 MHZ to 7 MHz. So a 400 MHz capable product from Ubiquiti or someone else doesn't seem that far fetched. 

If you have experimented on 2.4 GHz, you know how frustrating it can be trying to combat the high noise floor and plethora of Part 15 devices. When you utilize the channels unshared with Part 15, you still at best, are limited by the line of site propagation of those microwave bands. HSMM experimenters are usually few and far between so an organized approach to commercial tower sites is likely not the case. This is what would make a 420-450 MHz capable device ideal.

If the idea of 70 cm HSMM appeals to you, I encourage you to vocalize your interest. (Section managers and Ubiquiti sales seem like logical places to start :)

{Edit 4/11/10}
http://www.xagyl.com/store/product.php?productid=16450&cat=0&page=1

XAGYL FLR4G30 450MHz 1000mW miniPCI

3.5 GHz HSMM

High Speed Multi Media (HSMM) is often referred to as being the Hinternet (Ham Internet), as it is primarily used under FCC Rules & Regulations Part 97. Under Part 97 commercial off-the-shelf equipment can be used at higher power and higher gain than the more common Part 15 802.11a/b/g operations.

The primary purpose for HSMM and Hinternet is to augment emergency communications via long range high speed wireless data networks that can handle voice, data and video communications. HSMM can also be used in the day-to-day aspects of Amateur Radio Communications.

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One direction the High Speed Multi-Media Working group had was to develop in collaboration with TAPR, 3.3-3.5-GHz transverters suitable for use with 802.11 gear.

The thought is with the seemingly infinite amount of consumer wireless devices being deployed worldwide, the shared 2.4 GHz and 5.8 GHz noise floors are rising. The 3 GHz ham allocations are from 3.3 to 3.5 GHz yielding over 30 better suited non-overlapping full-width channels unshared with Part 15 unlicensed devices.

Ubiquiti Networks is a new company founded in 2005. Their "frequency freedom technology, seems to lead the way and promise integrated radio technology which uses an advanced RF integration and firmware design to provide a powerful platform capable of operation in any frequency imaginable. Basically Ubiquiti radios are Atheros chipsets with transverters onboard.

There are three different Ubiquiti XR3 frequency ranges that are version dependant (hardware limited ranges): XR3-2.8 (2.70-2.90 GHz), XR3-3.5 (3.40-3.70 GHz), and XR3-3.7.

The Ubiquiti XR3 XtremeRange3 is a mini-PCI Adapter 3.5GHz 400mW and lists for $240. The price is still considerably lower that an Icom ID-1 implementation and yields much higher throughput.

I few months back I blogged about their Nanostation. I have been finding the Atheros chipset ability to utilize 5 MHz channels very handy for side-stepping interference.

Well, they have out done themselves. At a starting MSRP of $49, NanoStation Loco provides a breakthrough in cost, reliability, & performance. It also is supported by a Linux SDK to encourage open source development.

NanoStation2/5 “LOCO” - This dual-polarity (auto-switching/diversity) 8db antenna has 100mw output and POE (18V). The 5ghz version comes with 13dbi integrated antenna. The NS2/NS5 “LOCO” does not have external antenna connector like the standard NS2/NS5. It's also a little less powerful, only 20 dBm (100 mW) instead of 26. (400 mW).. Keep in mind after market firmware hacks let you do nearly one watt with the normal NS2, so this is likely a low ended report of what is actually capable of.

If you need an external antenna, never fear http://ubnt.com/products/bullet.php

For the curious, here are some internal pictures of some Ubiquiti products

{Edit}
Check out Steve Ford's (WB8IYM) Eclectic Technology Column in QST June 2009
Titled "High Speed Multimedia at 3.5 GHz"