LTE: Scheduling Request Timing Calculator for FDD and TDD


SR configuration table is given below (Table 10.1.5-1 from 3GPP TS 36.213). SR transmission instances are the uplink subframes satisfying (10*SFN + subframe ‒ Noffset,SR) mod SRperiodicity = 0
Scheduling Request procedure in detail is presented here
SR configuration Index ISR
SR Periodicity (ms)
SRperiodicity
SR subframe offset Noffset,SR
0 ‒ 4
5
ISR
5 ‒ 14
10
ISR ‒ 5
15 ‒ 34
20
ISR ‒ 15
35 ‒ 74
40
ISR ‒ 35
75 ‒ 154
80
ISR ‒ 75
155 ‒ 156
2
ISR ‒ 155
157
1
ISR ‒ 157

One can use the below ‘SR calculator’ to calculate subframes for transmitting SR on PUCCH

sr-ConfigIndex (0-157):          TDD UL-DL Config:

         Is TDD?

SR timing will be displayed here

Full details of Scheduling Request subframes within one full SFN cycle

Posted by KP
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5 comments:

  1. DINESH - I Hate LoveNovember 10, 2014 at 12:06 PM

    I got good amount of info

    But I have some queries to be clarified.

    Q1. What happen when SR is configured/transmitted in DL subframe.

    Q2. When SR Config index is 17 (Periodicity 20ms) and SR-prohibit timer value as 2.
    If first SR is received on rfn: 2000 sfn: 2, then the second SR will be in
    rfn: 2004 sfn: 2 (as " 2*SR Periodicity ")
    or
    rfn: 2006 sfn: 2 (as " 2*SR Periodicity+SR Periodicity " - where SR prohibit timer expires and actual SR periodicity starts).
    Q3. If dsr-TransMax=4 and UL Grant is received by UE after SR transmission. then pending 2 SRs are droped or they will transmitted. If they are transmitted is their any change in the behavior of pending SRs?

    ReplyDelete
    Replies
    1. KPNovember 10, 2014 at 1:00 PM

      Hi Dinesh,

      Answer for Q1: The UE can't transmit anything in DL subframe, SR is not transmitted...It will be transmitted in the next UL subframe where SR equation is satisfied

      Answer for Q2:
      rfn: 2006 sfn: 2
      Effectively the UE should prohibit two SRs as SR-prohibit timer = 2.

      Answer for Q3: As soon as the grant is received, all pending SRs will be cancelled...
      All pending SR(s) shall be cancelled and
      sr-ProhibitTimer shall be stopped when a MAC PDU is assembled and this PDU includes a BSR which contains buffer status up to (and including) the last event that triggered a BSR, or when the UL grant(s) can accommodate all pending data available for transmission.

      Delete
    2. DINESH - I Hate LoveNovember 11, 2014 at 6:19 AM

      Thanks Swamy.

      For Q1, Is this type of configuration (SR in DL) will effect the behavior?

      Delete
    3. KPNovember 11, 2014 at 9:35 AM

      In General it would work as explained below...
      The MAC would schedule SR according to configuration...L1 would block transmissions if the PUCCH transmission falls in DL subframe...eventually, MAC should trigger RA procedure after reaching dsr-TransMax...

      This is very unlikely scenario...where the NW configuring SR to fall in DL subframe all the time...

      Delete
  2. AnonymousMarch 13, 2017 at 12:01 PM

    Good one. How do you do it for Narrow band IOT UE, Suppose If I am a UE and want to transmit data, how can i send the scheduling request. The format 2 in NB-IOT is for only ACK/NACK transmission

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