ORBIT-USER: Questions about analyzing results and OML

[Zhibin Wu]

On 11/20/06, Yang  Chen <yangchen at cc.gatech.edu> wrote:
> hi, all:
>
> From the introduction of OML, there would be two tables at the 
> sender/receiver side respectively.
> On the sender side, there would be a time-triggered measurement on the

> summation of the pkt size sent; On the receiver side, there would be 
> time-triggered measurement on the summation of the pkt size received;
>
> I have the following questions:
>
> 1) How to compute the throughput at each side?
> From sender.rb and receiver.rb,  the measurement interval seems to be 
> 1 seocnd. But the value of pkt_size_sample_sum and 
> rcvd_pkt_size_sample_sum are in terms of what? Byte? Bit? Does it 
> include headers' size or it is just the payload?
>
it is in bytes, payload only. Check the user manual of OTG in wiki pages
as:
http://orbit-lab.org/wiki/Documentation/OTG/UserManual

> 2) How to compute the average delay?
> In senderport table, there are three columns, two of them are integers

> and one of them is float.
> | timestamp  | gen_timestamp | tx_timestamp |
> How to interpret each of them?
>

Check the above wiki page too.

> On each side's table, there is a column called pkt_seqno, but none of 
> the records has the same pkt_seqno. So how can I know which packet I 
> should track for its sending time and receiving time?
>

The measurements is averaged over all packets sent/received in one
second. But the sequence number cannot be averaged. So it only takes the
sequence  number of the packet received first during this minute.
If you want to compare the measurement with the same packet, another
filter has to be used instead.

> 3) In my helloworld experiment, both rssi and xmitrate in the receiver

> table are always 0 while a certain amount of pkts are received. Is
this correct?
>
I think not if u specify "udp_libmac" in the protocol property in the
"receiver definition" of the script.

> Any comments and suggestions are appreciated.
>
> rgds,
> Yang
>
>


--
Zhibin Wu
Graduate Research Assistant
WINLAB, Rutgers University
Technology Centre of New Jersey
671 Route 1 South
North Brunswick, N.J. 08902-3390
Phone: 732-932-6857 x653
Fax:   732-932-6882