Subject: [manet] Power Control Algorithm Deployment in real ad-hoc nodes

From: Brahim Bensaou <[email-masked]>
Date: Thu, 16 Jun 2005 17:00:47 +0800

Hi there,

I am curious to know if there is any hardware platform out there
in the market that allows us to test our own MAC protocol and/or
power control algorithms in a real system without having to design the 
chips
or assemble the hardware.

 From what I know, (thanks to/because of the FCC) off the shelf 
WLAN cards come with a binary firmware (which prevents any fiddling
with the transmit power) and the MAC protocol window adjustment etc
are hardwired.
On the other hand, the motes allow such modifications but the transceiver
data rates and the range of power are so small that the effects of such
modifications would fall within the variation range of the original 
protocols
and thus cannot be observed conclusively.

Any experience/Information in this area is very welcome.

Thanks

- BB.

-- 
--
Brahim Bensaou            | Computer Science Department
Assistant Professor       | Hong Kong University of Science & Technology
[email-masked]          | Clear Water Bay, Kowloon, Hong Kong
http://www.cs.ust.hk/~csbb| Ph: +852 23587014, Fax: +852 23581477

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From: David Young <[email-masked]>
Date: Thu, 16 Jun 2005 12:20:02 -0500

> or assemble the hardware.

There are two types of 802.11 MACs, the microcontroller-based ones,
and the silicon state machines.  The two types support different kinds
of experimentation.

The host computer can control the transmit power on virtually all silicon
MACs, and on some of the microcontroller MACs.  Also, some of the silicon
MACs have very versatile controls for the contention window and such.
Microcontroller-based MACs usually do not expose very versatile controls
to the host.

If you want to radically alter the 802.11 MAC, I believe you can probably
do that by reprogramming the MAC microcontroller.  The problem is to get
documentation for the microcontroller.  Both Atmel and TI 802.11b MACs
are ARM microcontrollers.  Both Atmel and TI hold onto their documentation
very tightly.

Here is a taxonomy of 802.11 MACs, with examples:

        * microcontroller-based MAC, "generation 1": an embedded
          CPU (usually an ARM) runs the MAC protocol.  On the same die as
          the CPU, there may be circuits for PCI bus-mastering, crypto
          acceleration, and a wireless modem.  The microcontroller
          is attached to a RAM and a Flash ROM.  Examples in this
          category are Cisco/Aironet 802.11b, Intersil Prism 802.11b,
          Lucent WaveLAN 802.11b, Atmel 802.11b.

        * microcontroller-based MAC, "generation 2": same as last,
          but without the Flash ROM.  There may be more integration
          of the RF front-end.  The host feeds the firmware to the
          wireless adapter; the adapter loads its RAM with the firmware.
          Examples in this category: Texas Instruments ACX-100, Intel
          Centrino 802.11b, Intersil Prism 3.

        * silicon state machine: a MAC state machine, etched into silicon,
          is responsible for real-time work: updating the NAV,
          transmission backoff, sending ACK/CTS packets and beacons.
          The host CPU is responsible for keeping high-level state
          (authentication/association status) and driving non-realtime
          processes.  Adapters with a MAC ASIC need no RAM or ROM.
          Silicon state machines are replacing microcontroller-based MACs
          because they are cheaper to manufacture.  Examples: ADMtek,
          Atheros, Ralink, Realtek.

> with the transmit power) and the MAC protocol window adjustment etc

The FCC does not require 802.11 MAC software/firmware to be distributed
in binary form.

Dave

-- 
David Young             OJC Technologies
[email-masked]      Urbana, IL * (217) 278-3933