Hello,
This is Nazmul, a PhD student of Rutgers University. I am using a modified
form of 'benchmark_Tx.py' and 'benchmark_Rx.py' for my research. I am
transmitting a random binary sequence and calculating the bit error rate at
the receiver (BER). Basically, I am generating a long binary sequence,
grouping them into different packets and then transmitting the packets using
'benchmark_Tx' program. I receive the packets using 'benchmark_Rx.py' and
then find the BER. The program works at high transmitter amplitude, i.e.,
when channels are good. However, when I start lowering the transmitter
amplitude, i.e. create bad channels, at some point, I get the following
error:
*Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
self.run()
File "/usr/local/lib/python2.6/dist-packages/gnuradio/blks2impl/pkt.py",
line 164, in run
self.callback(ok, payload)
File "./rec_randombingen.py", line 97, in rx_callback
(ide,pktno,) = struct.unpack('!cH', payload[0:3])
error: unpack requires a string argument of length 3*
After showing this error, the whole programs. Let's assume that I am
transmitting 100 packets. If this error occurs at 20-th packet, the
benchmark_rx does not receive the next 80 packets. This really hampers the
calculation of packet loss probability and bit error rate.
I guess, for very bad channels, noise is acting as erasure, i.e., some part
of the packet header is getting erased. Ideally, I would like the program to
assume this packet to be 'lost' and move on to receiving the remaining
packets. It is OK with me if I lose a packet due to this type of error but
how can I make sure that the whole program does not stop due to this error?
Your feedback will be very appreciated.
Thanks,
Nazmul
--
Muhammad Nazmul Islam
Graduate Student
Electrical & Computer Engineering
Wireless Information & Networking Laboratory
Rutgers, USA.
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