Network access of a wireless device to a communications network

Patent metadata

Field	Value
Publication number	US-10728930-B2
Application number	US-201716084334-A
Country	US
Kind code	B2
Filing date	Mar 10, 2017
Priority date	Mar 16, 2016
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A communications network is being accessed by a wireless device associated with a coverage class selected from a set of coverage classes. The wireless device performs a method comprising initiating network access to the communications network by transmitting a preamble sequence for random access on a physical random access channel during a starting opportunity defined by the coverage class of the wireless device. Each coverage class may be associated with a unique number of repetitions of the preamble sequence transmission.

First claim

The invention claimed is:

1. A method, performed by a user equipment (UE), to access a communications network, wherein the UE is associated with a coverage class from a set of two or more coverage classes, each coverage class being associated with transmission of a different number of repetitions of a random access preamble sequence for performing network access, the set of two or more coverage classes sharing a frequency band, the method comprising the UE:
generating a Single-Carrier Frequency-Division Multiple Access (SC-FDMA) random access preamble signal comprising two or more consecutive preamble symbol groups, each preamble symbol group comprising a cyclic prefix portion and a plurality of symbols occupying a single subcarrier of the SC-FDMA random access preamble signal, wherein the single subcarrier for at least one of the preamble symbol groups corresponds to a first subcarrier frequency and the single subcarrier for an immediately subsequent one of the preamble symbol groups corresponds to a second subcarrier frequency; and
initiating network access by transmitting the random access preamble signal at a starting opportunity related to the coverage class of the user equipment, such that each coverage class of the set of two or more coverage classes has a different starting opportunity, and such that collision in the shared frequency band is avoided between one coverage class and a different coverage class in the set of two or more coverage classes.

2. The method of claim 1 , wherein the starting opportunity for transmitting the random access preamble signal is based at least on restrictions given by subframes occupied by PRACH resources related to a higher coverage class than the coverage class of the transmitting UE, the higher coverage class corresponding to a greater number of repetitions of a random access preamble sequence.

3. The method of claim 1 , further comprising the UE:
receiving one or more parameters indicating at least one of the following:
a periodicity;
a subframe containing a starting opportunity; and
a number of repetitions per preamble transmission attempt;

determining, based at least in part on the received one or more parameters, one or more starting opportunities.

4. The method of claim 1 , further comprising the UE:
receiving parameters indicating:
a periodicity;
a subframe containing a starting opportunity; and
a number of repetitions per preamble transmission attempt;

determining, based at least in part on the received parameters, one or more starting opportunities.

5. The method of claim 3 , further comprising the UE receiving a parameter, the parameter indicating one of the following:
a periodicity,
a subframe containing a starting opportunity, and
a number of repetitions per preamble transmission attempt,
for at least one higher coverage class than the coverage class associated with the UE, the higher coverage class corresponding to a greater number of repetitions of a random access preamble sequence.

6. The method of claim 5 , wherein one or more starting opportunities are determined by identifying possible starting opportunities related to the coverage class associated with the UE and avoiding those possible starting opportunities which may be used by UEs of the at least one higher coverage class.

7. The method of claim 6 , wherein one or more starting opportunities are further determined by backing off from identified possible starting opportunities which may be used by a UE of the at least one higher coverage class.

8. The method of claim 3 , wherein the received one or more parameters indicate a subframe containing a starting opportunity, by indicating a starting subframe common to all coverage classes in the set of coverage classes, from which the subframe containing the starting opportunity may be determined.

9. The method of claim 8 :
wherein each coverage class in the set of coverage classes has a different offset for initiating the network access in relation to the common starting subframe; and
wherein the network access is initiated according to the offset.

10. The method of claim 3 :
wherein the received one or more parameters indicates a number of repetitions per preamble transmission attempt; and
wherein the received one or more parameters have a unique value for each coverage class in the set of coverage classes.

11. The method of claim 1 , wherein each coverage class in the set of coverage classes is associated with UEs having a respective received power level.

12. The method of claim 1 , wherein the two or more coverage classes in the set of coverage classes are ranked and the UE backs off from initiating network access at a possible starting opportunity used by UEs associated with a higher coverage class.

13. A base station for enabling a user equipment (UE) to access a communications network, wherein the UE is associated with a coverage class from a set of two or more coverage classes, each coverage class being associated with transmission of a different number of repetitions of a random access preamble sequence for performing network access, the set of two or more coverage classes sharing a frequency band, the base station comprising:
a communication interface comprising one or more transmitters and one or more receivers; and
processing circuitry configured to cause the base station to:
transmit network access information to the UE, wherein the network access information specifies a starting opportunity at which the user equipment may initiate network access by transmitting a random access preamble, such that each coverage class of the set of two or more coverage classes has a different starting opportunity, and such that collision in the shared frequency band is avoided between one coverage class and a different coverage class in the set of two or more coverage classes; and
receive, at a starting opportunity related to the coverage class associated with the UE, a Single-Carrier Frequency-Division Multiple Access (SC-FDMA) random access preamble signal comprising two or more consecutive preamble symbol groups, each preamble symbol group comprising a cyclic prefix portion and a plurality of symbols occupying a single subcarrier of the SC-FDMA random access preamble signal, wherein the single subcarrier for at least one of the preamble symbol groups corresponds to a first subcarrier frequency and the single subcarrier for an immediately subsequent one of the preamble symbol groups corresponds to a second subcarrier frequency.

14. A user equipment (UE) configured to access a communications network, wherein the UE is further configured to be associated with a coverage class from a set of two or more coverage classes, each coverage class being associated with transmission of a different number of repetitions of a random access preamble sequence for performing network access, the set of two or more coverage classes sharing a frequency band, the user equipment comprising:
a communication interface comprising one or more transmitters;
processing circuitry configured to cause the UE to:
generate a Single-Carrier Frequency-Division Multiple Access (SC-FDMA) random access preamble signal comprising two or more consecutive preamble symbol groups, each preamble symbol group comprising a cyclic prefix portion and a plurality of symbols occupying a single subcarrier of the SC-FDMA random access preamble signal, wherein the single subcarrier for at least one of the preamble symbol groups corresponds to a first subcarrier frequency and the single subcarrier for an immediately subsequent one of the preamble symbol groups corresponds to a second subcarrier frequency; an

Assignees

• Ericsson Telefon Ab L M

Inventors

• Lin Xingqin
• Adhikary Ansuman
• Bergman Johan Mikael
• Blankenship Yufei
• Grövlen Asbjörn
• Shokri Razaghi Hazhir
• Sui Yutao
• Wang Yi-Pin Eric

Classifications

• H04W74/0858

  collision detection · CPC title

• H04W74/0841

  with collision treatment · CPC title

• H04W48/12 Primary

  using downlink control channel · CPC title

• H04L27/2636

  with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM] · CPC title

• H04L27/2614

  Peak power aspects · CPC title