Method and apparatus for random access in mobile communication system

Patent metadata

Field	Value
Publication number	US-10820355-B2
Application number	US-201815934320-A
Country	US
Kind code	B2
Filing date	Mar 23, 2018
Priority date	Mar 24, 2017
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

A method and an apparatus for random access in a mobile communication system are provided. A terminal receives a synchronization signal block, obtains beam index information from the received synchronization signal block, and transmits a preamble message occupying a plurality of preamble resources including a preamble resource corresponding to the beam index information to a base station. A random access resource includes a plurality of preamble resources, and the synchronization signal block is specified for one beam and corresponds to one preamble resource of the random access resource.

First claim

What is claimed is:

1. A method for random access in a multi-beam-based mobile communication system, comprising:
receiving, by a terminal, a plurality of synchronization signal blocks from a base station;
obtaining, by the terminal, a beam index and a beam group index included in one synchronization signal block among the received plurality of synchronization signal blocks;
identifying, by the terminal, a random access resource associated with the beam group index which indicates a first beam group to which a first beam used for transmitting the one synchronization signal block belongs;
identifying, by the terminal, a plurality of preamble resources included in the random access resource based on the beam index indicating the first beam; and
transmitting, by the terminal, a preamble message using the plurality of preamble resources to the base station,
wherein each of the plurality of synchronization signal blocks is specified for one beam and the plurality of preamble resources are used for transmitting the preamble message by the terminal.

2. The method of claim 1 , wherein the terminal recognizes the first beam corresponding to the obtained beam index as an optimal downlink transmission beam, and
the plurality of preamble resources includes a central preamble resource corresponding to the beam index and preamble resources which are located prior to and after the central preamble resource corresponding to the beam index.

3. The method of claim 1 , wherein a beam specified for a preamble resource located in a middle among the plurality of preamble resources on which the preamble message is transmitted is recognized by the base station as an optimal downlink transmission beam for the terminal.

4. The method of claim 1 , wherein, when beam grouping is performed, a burst including the plurality of synchronization signal blocks corresponds to one random access resource, and the plurality of synchronization signal blocks of the burst correspond to different preamble resources in the random access resource.

5. The method of claim 1 , wherein the obtaining of the beam index and the beam group index comprises:
selecting, by the terminal, the one synchronization signal block corresponding to a direction of the terminal from among the plurality of synchronization signal blocks; and
decoding, by the terminal, the selected one synchronization signal block to obtain the beam index and the beam group index.

6. The method of claim 1 , wherein the random access resource includes the plurality of preamble resources and a guard time (GT) resource, and
wherein the transmitting of the preamble message comprises, when an optimal beam recognized according to the beam index is an initial or last beam and a length of the preamble message is predetermined, selecting preamble resources from a first preamble resource or a last preamble resource of the random access resource by the length of the preamble message and transmitting the preamble message by using the selected preamble resources.

7. The method of claim 1 , further comprising: after the transmitting of a preamble message,
receiving, by the terminal, at least one random access response (RAR) transmitted on RAR resources selected through a RAR selection procedure from the base station;
selecting, by the terminal, a RAR from among a plurality of RARs when receiving the plurality of RARs; and
recognizing, by the terminal, that a beam corresponding to the selected RAR is an optimal uplink reception beam.

8. The method of claim 7 , wherein a RAR resource is specified to one beam and corresponds to one preamble resource of the random access resource, and
wherein the selecting of a RAR from among a plurality of RARs comprises,
when a plurality of terminals are respectively located in different cover ridges and each terminal transmits a preamble message including a different preamble sequence, selecting one RAR from among the plurality of RARs based on a preamble sequence used in the preamble message transmission.

9. The method of claim 7 , wherein a RAR resource is specified to one beam and corresponds to one preamble resource of the random access resource, and
wherein the selecting of a RAR from among a plurality of RARs comprises,
when a plurality of terminals are respectively located in different cover ridges and each terminal transmits a preamble message including a same preamble sequence, selecting one RAR having maximum reception power.

10. The method of claim 7 , wherein the RAR selection procedure at the base station is performed based on a preamble message having maximum reception power among a plurality of preamble messages, and a beam corresponding to a preamble resource on which the preamble message having maximum reception power is transmitted is selected as an optimal beam, and wherein the RAR from the base station is transmitted on RAR resources corresponding to the selected optimal beam.

11. A method for random access in a multi-beam-based mobile communication system, comprising:
transmitting, by a base station, a plurality of synchronization signal blocks;
monitoring, by the base station, a plurality of preamble resources associated with each of the plurality of synchronization signal blocks;
receiving, by the base station, a preamble message in the plurality of preamble resources associated with one synchronization signal block among the plurality of synchronization signal blocks from a terminal; and
recognizing, by the base station, a first beam specified to the one synchronization signal block corresponding to the plurality of preamble resources, the preamble message being received on the plurality of preamble resources, as an optimal downlink transmission beam for the terminal,
wherein a random access resource includes the plurality of preamble resources, the one synchronization signal block is specified for one beam, the plurality of preamble resources are used for transmitting the preamble message by the terminal, each of the plurality of synchronization signal blocks includes a beam index and a beam group index, the beam index included in the one synchronization signal block indicates the first beam, the beam group index included in the one synchronization signal block indicates a first beam group to which the first beam belongs, the first beam group is associated with the random access resource, and the first beam is associated with the plurality of preamble resources included in the random access resource.

12. The method of claim 11 , wherein the recognizing comprises recognizing the first beam specified for the one synchronization signal block corresponding to a preamble resource located in a middle among the plurality of preamble resources on which the preamble message is received as the optimal downlink transmission beam for the terminal.

13. The method of claim 11 , wherein the plurality of preamble resources includes a preamble resource corresponding to the beam index included in the one synchronization signal block and preamble resources which are located prior to and after the preamble resource corresponding to the beam index.

14. The method of claim 11 , further comprising:
after the recognizing,
selecting, by the base station, an optimal uplink reception beam for the terminal by beam sweeping; and
transmitting, by the base station, a random access response (RAR) on RAR resources corresponding to the selected beam,
wherein a RAR resource is specified to one beam and corresponds to one preamble resource of the random access resource.

15. The method of claim 14 , wherein the selecting of the optimal uplink reception beam comprises

Assignees

• Electronics & Telecommunications Res Inst

Inventors

• Hui Bing
• Kim Il Gyu
• Kim Junhyeong
• Noh Gosan
• Chung Hee Sang
• Choi Sung Woo

Classifications

• H04B7/06952

  Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping · CPC title

• H04W74/0833

  Random access procedures, e.g. with 4-step access · CPC title

• H04W56/001 Primary

  Synchronization between nodes · CPC title

• H04L5/0007

  the frequencies being orthogonal, e.g. OFDM(A) or DMT · CPC title

• H04W74/085 Primary

  collision avoidance · CPC title