US 9,814,068 B2
System and method for beam-based physical random-access
Mattias Frenne, Uppsala (SE); Håkan Andersson, Linköping (SE); Johan Furuskog, Stockholm (SE); Stefan Parkvall, Bromma (SE); Henrik Sahlin, Mölnlycke (SE); and Qiang Zhang, Täby (SE)
Assigned to Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)
Appl. No. 14/400,579
Filed by Telefonaktiebolaget L M Ericsson (publ), Stockholm (SE)
PCT Filed Aug. 27, 2014, PCT No. PCT/SE2014/050986
§ 371(c)(1), (2) Date Nov. 12, 2014,
PCT Pub. No. WO2015/147717, PCT Pub. Date Oct. 1, 2015.
Claims priority of provisional application 61/970,145, filed on Mar. 25, 2014.
Prior Publication US 2016/0157267 A1, Jun. 2, 2016
Int. Cl. H04W 72/00 (2009.01); H04W 74/00 (2009.01); H04B 7/08 (2006.01); H04W 16/28 (2009.01); H04W 72/04 (2009.01); H04L 5/00 (2006.01); H04B 7/0408 (2017.01); H04B 7/06 (2006.01)
CPC H04W 74/008 (2013.01) [H04B 7/0408 (2013.01); H04B 7/0617 (2013.01); H04B 7/086 (2013.01); H04L 5/0048 (2013.01); H04W 16/28 (2013.01); H04W 72/046 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A method in a wireless device for performing random access to a network node, the method comprising:
receiving a set of downlink beam-specific reference signals, BRSs, from the network node;
determining a preferred BRS based on the received signal power for each BRS of said set of downlink beam-specific reference signals (BRSs);
selecting, based on the preferred BRS, a random-access resource to be used for transmitting a random-access attempt to the network node according to one or more pre-defined association rules defining an association between a random-access resource and a BRS; and
using the selected random-access resource when transmitting a random-access attempt to the network node, whereby the selection of random-access resource indicates to the network node which downlink beam is preferred by the wireless device to be used for downlink transmissions;
wherein the random access resource comprises a random-access preamble, wherein the selecting comprises selecting from a set of preambles the random-access preamble to be used for transmitting the random-access attempt, the selecting using information that is in a look-up table, specified in a manual or standard, given by prior broadcast signaling, or configured by dedicated signaling on an assisting legacy network of the wireless device, or the selecting using a function that uses the preferred BRS as an input and provides the selected random-access preamble as an output, the function being specified in a manual or standard, given by prior broadcast signaling, or configured by dedicated signaling on an assisting legacy network of the wireless device.