Re: contiki data transmission speed
Hi David, thanks for your help !
I will try to test again later.
In my project , There are about 10 data nodes to send data as a data stream to pc ,
every data node sent data about as an average rate of 0.5kb/s .
the border router is rpl root .
while in my contiki system , if the data have a hop , the largest packet only 64 data bytes . More than this
number ,the packet can not be sent . so I can only package of 64 bytes for one pakcet .
at the really project , the data come from serial , while in my test , the data is generated in contiki .
I use cc2530dk platform .
thanks .
------------------
Tom
2012-06-19
-------------------------------------------------------------
From："David Kopf" <dak664 <at> embarqmail.com>
Time：2012-06-18 21:22
To：Contiki developer mailing list
Theme：Re: [Contiki-developers] contiki data transmission speed
I would try a packet rate of once every second or even 10 seconds to eliminate any possibility of collisions
(other than RPL
messages? Border router suggests you are using RPL). Packet loss there would indicate low signal quality.
Then graph the loss as a
function of rate. 8 times per second with one hop is 16 packets per second, 64 bytes is about 2/3 of a full 4.2
msec packet = 50
msec, plus 16*0.5 = 8 msec for acks, call it 60 msec of tx time per second. Three data nodes would mean 20% tx
time, getting close
to where collisions would begin to greatly reduce throughput. Try it with and without the third node (and
make sure the csma is
working!)
-----Original Message-----
From: Tom
Sent: Monday, June 18, 2012 8:11 AM
To: Contiki developer mailing list
Subject: Re: [Contiki-developers] contiki data transmission speed
Thank you for you reply !
I hava a simple description of the test way i used :
I send the data invoke the function : uip_udp_packet_send(struct uip_udp_coon, const void *data, int
len) ;
and 8 times per second to send for 64bytes to pc;
i hava 4 nodes , the node1, node2, node3 is data node, send data to pc ; node4 is border router ;
if i start nodes(node 1,node2,node3,node4) very close ,i can collected about 95% of the data on the
computer , when i put the
node1 far, about 500 meters, i have ensured the i can not receive its data. then i placed the node2 between
node1 and border root ,
i can receive the data both of node1 and node2 ,but node1 lost packet above 90% and node2 also lost packet 60%.
i donot know why
.
i use cc2530 chip.
thanks for your help
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