Bug 1924

Summary:	sensing radius and CCA
Product:	ns-3	Reporter:	Tom Henderson <tomh>
Component:	lr-wpan	Assignee:	Sascha Jopen <jopen>
Status:	NEEDINFO ---
Severity:	enhancement	CC:	jopen, ns-bugs
Priority:	P5
Version:	pre-release
Hardware:	PC
OS:	Linux
Attachments:	Fix bug with watts not being converted to dB in CCA. Added CCA test.

Description Tom Henderson 2014-06-10 21:56:05 EDT

Described here:
https://groups.google.com/forum/#!searchin/ns-3-users/sensing$20radius/ns-3-users/C75VZTPbSkg/h0KiQIdo-asJ

1) m_ccaPeakPower should be initialized to a nonzero value.

2) calculating the CCA energy detection threshold
in dB from values given in watts

Comment 1 Sascha Jopen 2014-06-12 03:03:11 EDT

Created attachment 1846 [details]
Fix bug with watts not being converted to dB in CCA. Added CCA test.

1)
Initializing m_ccaPeakPower to zero is not a problem. It will be overwritten with the actually measured power in any case. The question is, should we add the noise power to the measured signal powers? In the end we compare the ccaPeakPower to the receiver sensitiviy, which also implicitly depends on noise. The same has to be considered for energy detection, not only CCA. For now i will leave it as is.

2)
I fixed the bug with the missing conversion from watts to dB.

Additionally i provided a new test case for CCA with a very simple scenario. For this scenario, CCA seems to work as expected. See the attached patch.

Comment 2 Tom Henderson 2014-06-12 15:48:26 EDT

the db to watts bug was fixed in 10811:31dbab5c8a28

Need more info as to whether/how to address the 1) issue in Sascha's comment.