US 11,812,416 B2
Coherent detection of large physical random access control channel (PRACH) delays
Johan Axnäs, Solna (SE); Henrik Sahlin, Mölnlycke (SE); Andres Reial, Malmö (SE); and Naga Vishnu Kanth Irukulapati, Gothenburg (SE)
Assigned to Telefonaktiebolaget LM Ericsson (Publ), Stockholm (SE)
Appl. No. 16/484,044
Filed by Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)
PCT Filed Feb. 6, 2018, PCT No. PCT/SE2018/050104
§ 371(c)(1), (2) Date Aug. 6, 2019,
PCT Pub. No. WO2018/143892, PCT Pub. Date Aug. 9, 2018.
Claims priority of provisional application 62/455,526, filed on Feb. 6, 2017.
Prior Publication US 2020/0092871 A1, Mar. 19, 2020
Int. Cl. H04W 72/04 (2023.01); H04W 72/044 (2023.01); H04W 56/00 (2009.01); H04W 74/08 (2009.01)
CPC H04W 72/044 (2013.01) [H04W 56/0055 (2013.01); H04W 74/0891 (2013.01)] 23 Claims
OG exemplary drawing
 
1. A method in a radio network node for processing a preamble used in a wireless communication system, the method comprising:
receiving, from a user equipment (UE), the preamble including a plurality of identical short sequences, the preamble being split into two portions, a first of the two portions transmitted by the UE using a first transmission characteristic, and a second of the two portions transmitted by the UE using a second transmission characteristic that is different from the first transmission characteristic, and a difference between the first transmission characteristic and the second transmission characteristic being based on a predefined time offset inserted by the UE between the first portion and the second portion, the time offset being generated by the UE omitting the transmission of one or more sequence elements;
determining, by a preamble detector, a fractional-symbol delay (Tfrac) of at least one of the plurality of short sequences; and
based at least in part on the determined Tfrac, using at least one of a first part of the preamble detector, the first part used to detect portions of the preamble arriving during an early time window of a plurality of time windows, and a second part of the preamble detector, the second part used to detect portions of the preamble arriving during a late time window of the plurality of time windows, to process at least one short sequence of the plurality of short sequences as part of calculating a propagation delay between the UE and the radio network node.