Data transmission and retransmission for semi-persistent scheduling
A method, wireless device and network node are disclosed. According to one aspect, a wireless device includes a radio interface configured to obtain a timer value, T, for measuring time elapsed from a start of a semi-persistent scheduled, SPS, uplink, UL, data transmission. The wireless device includes processing circuitry configured to perform an SPS UL data transmission associated with a hybrid automatic repeat request, HARQ, process identification, ID, wherein the HARQ process ID is one of a plurality of HARQ process IDs. The processing circuitry is configured to perform a new data transmission or autonomous retransmission with said HARQ process ID at the next available time for said HARQ process ID after elapsed time T.
1. A host computer, comprising:
processing circuitry configured to provide user data; and
a network interface configured to initiate transmission of the user data from a network node in a cellular network to a user equipment (UE), the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform operations comprising:
receiving, from the UE, a semi-persistent scheduled, SPS, uplink, UL, data transmission associated with a hybrid automatic repeat request, HARQ, process, a SPS transmission being a transmission performed without a dynamic grant and the HARQ process being one of a plurality of HARQ processes;
measuring a time, T, subsequent to receipt of the SPS UL data transmission;
attempting a decoding of the SPS UL data transmission and not sending, to the UE, an ACK for the received SPS UL data transmission when the attempted decoding is successful; and
receiving, after time T has elapsed, for a HARQ process identification, ID, one of a new SPS UL data transmission and a retransmission of the previously received SPS UL data transmission with a HARQ process ID selected based on a relationship between time T and a time, τ, during which the UE cycles through the plurality of HARQ, processes.
2. The host computer of claim 1 , wherein:
if the timer value, T, is shorter than or equal to the total time, τ, to cycle through the plurality of HARQ process IDs for SPS UL data transmissions, the UE transmits the new SPS UL transmission after the total time, τ; and
if the timer value, T, is greater than the total time τ to cycle through the plurality of HARQ process IDs for SPS UL data transmissions, the UE retransmits the previously received SPS UL data transmission at the total time, τ.