LTE: SPS Calculator

SPS Occasions can be calculated using the below tool.

Full details about Semi-Persistent Scheduling can be found here

When calculating SPS occasions for TDD, UL-DL configuration needs to be selected whereas for the FDD, the tool ignores UL-DL Config value.

activation-SFN and activation-Subframe need to be selected based on the SPS (UL or DL) activation SFN and subframe respectively.

For uplink SPS, PUSCH occasions will be displayed.

From 36.321, section 5.10.1, for downlink SPS,

After a Semi-Persistent downlink assignment is configured, the UE shall consider that the assignment recurs in each subframe for which

(10 * SFN + subframe) = [(10 * SFN_{start time} + subframe_{start time}) + N * semiPersistSchedIntervalDL] modulo 10240 for all N>0

Where SFN_start time and subframe_start time are the SFN and subframe, respectively, at the time the configured downlink assignments were (re-) initialised

Similarly, section 5.10.2 for Uplink SPS,

After a Semi-Persistent Scheduling uplink grant is configured, the UE shall consider that the grant recurs in each subframe for which:

(10 * SFN + subframe) = [(10 * SFN_{start time} + subframe_{start time}) + N * semiPersistSchedIntervalUL Subframe_Offset * (N modulo 2)] modulo 10240 for all N>0

Where SFN_start time and subframe_start time are the SFN and subframe, respectively, at the time the configured uplink grant were (re-) initialized. Subframe_Offset should be obtained from Table 7.4-1 in 36.321 if twoIntervalsConfig (only for TDD) is enabled, otherwise, Subframe_Offset is set to 0.

sps-Interval           activation-SFN           activation-Subframe          UL-DL Config
10 20 32 40 64 80 128 160 320 640                                                         0 1 2 3 4 5 6

uplink SPS?            downlink SPS?             Is TDD?             twoIntervalConfig?

SPS Occasions will be displayed here