Methods of retransmission in semi-persistent scheduling without explicit HARQ feedback

Abstract

Example techniques for data retransmission in systems that do not utilize explicit hybrid automatic repeat request (HARQ) feedback are presented, including an example method (400) by a wireless device(102) that includes starting (402) a timer for a hybrid automatic repeat request (HARQ) process associated with a transport block (TB) transmission (105) by the wireless device (102) to the network node (106). The method (400) includes identifying (404) a HARQ policy (113) for the HARQ process, the HARQ policy (113) governing whether the wireless device (102) is to retransmit the TB or transmit anew TB where no HARQ feedback responsive to the TB transmission (105) is received from the network node (106) before the timer expires. Furthermore, the method (400) includes retransmitting (406) theTB or transmitting the new TB according to the HARQ policy (113) at a next periodic transmission occasion (307) for the HARQ process after the timer expires. Methods at a network node (106) and related apparatuses and computer programs are also presented.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS [0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 476,641, filed March 24, 2017, entitled "Methods of Retransmission in Semi-Persistent Scheduling Without Explicit HARQ Feedback,". technical field [0003] The subject matter of this application relates generally to wireless communications. More specifically, this topic focuses on techniques for data retransmission in fifth generation (5G) wireless communication systems. Background technique [0004] In Long Term Evolution (LTE), resources for uplink (UL) transmissions are granted by network nodes (eg, base stations, evolved Node Bs (eNBs), next generation Node Bs (gNBs), etc.). This grant scheduling process can be done dynamically (such as when the network node schedules UL transmissions every Transmission Time Interval (TTI)). Alternatively, a semi-persistent scheduling (SPS) framework can be utilized. When SPS is utilized, uplink grants...

AI Technical Summary

Problems solved by technology

The UL HARQ process in 5G aims to be asynchronous in design, which means that ACK or NACK can be transmitted sporadically, making HARQ feedback timing unpredictable

However, in case of asynchronous HARQ, multiple PHICH channels will be required, and NR does not provide these channels or a mechanism for their creation

Thus, since NR is to use UL semi-persistent scheduling without explicit HARQ feedback, a UE implementing the NR protocol will not be able to determine whether it should send a new data packet according to the SPS period or whether it should send a retransmission of a previous packet

Therefore, there is a need for a solution to the problems caused by this ambiguity, since the resulting uncertainty about what UEs in NR are to transmit may drive per-UE and system-wide scale Severe performance and reliability degradation on

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