[srslte-users] srsUE sufferd scheduling request failed.

[David Yu ( III )]

Hi Ismael,
We found that PUSCH was good with QPSK modulation when srsUE just ping to external server. No "scheduling request failed" arose.
But in every time, PUSCH was bed with QPSK modulation when srsUE play youtube. And after 2~4 mins, "scheduling request failed" arose.

1. What "scheduling request failed" stands for? Is it MAC layer issue?
2. Have you ever suffered "scheduling request failed" on your srsUE?
3. What is the possible cause for "scheduling request failed"? except for UL/DL signal quality.
Many Thanks.

Regards,
David

-----Original Message-----
From: Ismael Gomez [mailto:ismael.gomez at softwareradiosystems.com] 
Sent: Thursday, May 19, 2016 4:15 PM
To: David Yu ( III ); srslte-users at lists.softwareradiosystems.com
Subject: Re: [srslte-users] srsUE sufferd scheduling request failed.

Hi David, 

Looking at your logs I see a problem with the Uplink. The Downlink is OK, the SNR is very good and most of the packets are received OK. In the UL however there are many NACKs on the PHICH, more or less ~50%, which means that the signal is very poor at the ENB. Every once a while, the ENB does not receive the SR signal from the UE (there are up to 4 attempts) and does not allocate the corresponding UL grant therefore the UE assumes the connection is lost and restarts RA procedure. 

You can try to increase the maximum number of SR attempts at the ENB, but I'd rather suggest that you improve the signal received at the ENB. How does the constellation look like? You could try increasing the tx power at the ue (param tx_power in ue.conf). 

Cheers
Ismael

On Thu, 19 May 2016 at 10:11 David Yu ( III ) <wcyu at iii.org.tw <mailto:wcyu at iii.org.tw> > wrote:


	Hi SRS,
	We successfully connected to OAI network and to internet.
	But for a while, tt disconnected and show "scheduling request failed" almost every time.
	Could you help me analyze this issue?
	Thanks.
	Regards,
	David
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