[Tinyos-help] error while incorporating interface CC2420Packet;

[Urs Hunkeler]

Hi Vijayant,

When a mote m1 sends a packet to another mote m2, and m2 replies with an
ack, the ack will most likely be sent with the default tx power
programmed on m2. So if you send a packet from m1 to m2 with your own
power, and you program the simulation to let the other mote respond with
the same tx power, then this differs from what would actually happen if
you would use real hardware. So what you should do instead is call the
send function with the first tx power being the tx power with which you
want to send the message from m1 to m2, and the second tx power being
the default tx power from m2. You probably would have to find out the
default tx power from m2 each time you do this because a mote could
change the default tx power at runtime.

Cheers,
Urs


Vijayant Bhatnagar schrieb:
> Hi,
> I referred to the data sheet. The data sheet says that programmable
> output power range is -24 to 0 dBm (in steps of 3). There is no
> mention about reverse link gain. Do we have straightaway assume that
> it is less than that of tx ?
> 
> How do I model reverse gain ? I am a bit confused.
> 
> Any help  is appreciated.
> 
> Thanks,
> vijayant
> 
> On 12/4/07, Philip Levis <pal at cs.stanford.edu> wrote:
>> On Dec 3, 2007, at 10:01 PM, Vijayant Bhatnagar wrote:
>>
>>> Hi,
>>> Since we have started working on TinyOS a week back, I may be
>>> wrong. The following is the change I made:
>>> Please correct me if I am wrong :
>>>
>>>
>>>
>>>     call GainRadioModel.putOnAirTo(destNode, sending, metadata-
>>>> ack, evt->time, power, power);      //Modified by Vijayant
>> This is problematic. You are setting the TX power of the receiver's
>> ACK to be the same TX power as the transmitter. The reason this is
>> problematic is because the two might not have the same TX powers, and
>> if the receiver's power is lower than the transmitters you might get
>> lots of false negative acks. By setting it in this way, you assume a
>> perfectly consistent TX power setting scheme, which is not achievable
>> in practice. It would make your results fictional and unachievable in
>> reality.
>>
>> As for what those values can be, you should consult chip data sheets
>> (e.g., CC1000, CC2420).
>>
>> Phil