METHOD AND APPARATUS FOR COVERAGE ENHANCEMENT FOR A RANDOM ACCESS PROCESS

• US 20150016312A1
• Filed: 06/30/2014
• Published: 01/15/2015
• Est. Priority Date: 07/10/2013
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Li, Ying, Papasakellariou, Aris, Ng, Boon Loong
• Granted Patent: US 9,451,639 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

Methods and apparatus are provided for a User Equipment (UE) and a base station in communication with each other to determine parameters for a Random Access (RA) process. The base station informs the UE through a System Information Block (SIB) of a number of resource sets for RA preamble transmission by the UE. Each resource set is associated with a number of repetitions for a RA preamble transmission, with a maximum number of RA preamble transmissions, and with a number of repetitions the base station transmits a response to a RA preamble reception. The SIB also informs an association between a range of path-loss values and a number of RA preamble repetitions. The UE determines a number of repetitions for a first RA preamble transmission from its path-loss measurement.

Claims

1. A method comprising:

receiving, by a User Equipment (UE) from a base station, a signal providing a system information block that informs a number of resource sets for Random Access (RA) preamble transmission in a resource from a resource set, wherein each resource set includes time, frequency, and code resources and is associated with a number of repetitions for a RA preamble transmission and with a maximum number of RA preamble transmissions, wherein, in response to the UE receiving the SIB, the UE determines the first number of repetitions for a transmission of a RA preamble, a corresponding first resource set, and a corresponding first maximum number of transmissions and a second number of repetitions for a transmission of a RA preamble, a corresponding second resource set, and a corresponding second maximum number of transmissions, and wherein the second number of repetitions is larger than the first number of repetitions;

and

transmitting, by the UE;

the RA preamble, in a resource from the first resource set and with the first number of repetitions, until the UE receives a response for a RA preamble transmission with the first number of repetitions or until the first maximum number of RA preamble transmissions is reached; and

the RA preamble, in a resource from the second resource set and with the second number of repetitions, after the first maximum number of RA preamble transmissions is reached.

2. The method of claim 1, wherein for each resource set, the system information block further informs an association between a range of path-loss values and a number of RA preamble repetitions and the UE is configured to determine the first number of repetitions as the one corresponding to the range of path-loss values that includes a path-loss value measured by the UE.

3. The method of claim 1, wherein the system information block further informs a path-loss value and the UE is configured to determine the first number of repetitions as the smaller number of repetitions that is larger than one when a path-loss value measured by the UE is larger than the path-loss value informed by the system information block.

4. The method of claim 1, wherein the first resource set and the second resource set have at least one common code resource and have no common frequency resource.

5. The method of claim 1, wherein each resource set includes two subsets and wherein a UE with one receiver antenna transmits a RA preamble using a resource from the first subset and a UE with two receiver antennas transmits a RA preamble using a resource from the second subset.

6. The method of claim 1, wherein either the signal providing the system information block is transmitted without repetitions and the first number of repetitions for the transmission of the RA preamble is larger than one or the signal providing the system information block is transmitted with repetitions and the first number of repetitions for the transmission of the RA preamble is one.

7. The method of claim 1, wherein for a Time Division Duplex (TDD) system operating with an UL/DL configuration, the system information block further informs of a set of subframes that are UL subframes in every valid UL/DL configuration and the RA preamble is transmitted only in the subframes from the set of subframes.

8. The method of claim 1, wherein for a Time Division Duplex (TDD) system, the RA preamble transmission uses a first RA preamble format for a first repetition and uses a second RA preamble format for a second repetition.

9. A method comprising:

receiving, by a User Equipment (UE) from a base station, a signal providing a system information block that informs a number of resource sets for Random Access (RA) preamble transmission in a resource from a resource set, wherein each resource set includes time, frequency, and code resources and is associated with a number of repetitions for a RA preamble transmission and with a maximum number of RA preamble transmissions;

determining by the UE a number of repetitions for a transmission of a RA preamble and a corresponding resource set;

transmitting by the UE the RA preamble for the number of repetitions in a resource from the resource set; and

receiving, by the UE from the base station, a response to the RA preamble transmission wherein the UE receives the response for a maximum number of repetitions that is associated in the system information block with the number of repetitions for the RA preamble transmission.

10. The method of claim 9, wherein after receiving the response to the RA preamble, the UE transmits to the base station a message with a number of repetitions determined from the number of repetitions for the transmission of the RA preamble.

11. The method of claim 10, wherein the transmission of the message has a first block error rate if the number of RA preamble repetitions is one and has a second block error rate is the number of RA preamble repetitions is larger than one and wherein the first block error rate is larger than the second block error rate.

12. The method of claim 9, wherein if the number of repetitions for the response to the RA preamble is one, the resources for the reception of the response to the RA preamble are informed by downlink control information format in a control channel and if the number of repetitions for the response to the RA preamble is larger than one, the resources for the reception of the response to the RA preamble are informed by the system information block.

13. The method of claim 9, wherein the UE receives from the base station a configuration for a number of repetitions for a subsequent RA preamble transmission and the UE transmits a RA preamble with the configured number of repetitions.

14. A User Equipment (UE) comprising:

a receiver configured to receive from a base station a signal providing a system information block that informs a number of resource sets for Random Access (RA) preamble transmission in a resource from a resource set, wherein each resource set includes time, frequency, and code resources and is associated with a number of repetitions for a RA preamble transmission and with a maximum number of RA preamble transmissions;

a controller configured to;

determine a first number of repetitions for a transmission of a RA preamble, a corresponding first resource set, and a corresponding first maximum number of transmissions; and

determine a second number of repetitions for a transmission of a RA preamble, a corresponding second resource set, and a corresponding second maximum number of transmissions wherein the second number of repetitions is larger than the first number of repetitions; and

a transmitter configured to;

transmit to the base station, in a resource from the first resource set and with the first number of repetitions, the RA preamble until the apparatus receives a response for a RA preamble transmission with the first number of repetitions or until the first maximum number of RA preamble transmissions is reached; and

transmit to the base station, in a resource from the second resource set and with the second number of repetitions, the RA preamble after the first maximum number of RA preamble transmissions is reached.

15. The UE of claim 14, wherein for each resource set, the system information block further informs an association between a range of path-loss values and a number of RA preamble repetitions and the apparatus determines the first number of repetitions as the one corresponding to the range of path-loss values that includes a path-loss value measured by the apparatus.

16. The UE of claim 14, wherein the system information block further informs a path-loss value and the UE determines the first number of repetitions as the smaller number of repetitions that is larger than one when a path-loss value measured by the UE is larger than the path-loss value informed by the system information block.

17. The UE of claim 14, wherein for a Time Division Duplex (TDD) system operating with an UL/DL configuration, the system information block further informs of a set of subframes that are UL subframes in every valid UL/DL configuration and the RA preamble is transmitted only in the subframes from the set of subframes.

18. A User Equipment (UE) comprising:

a receiver configured to receive from a base station

a signal providing a system information block that informs a number of resource sets for Random Access (RA) preamble transmissions wherein each resource set is associated with a number of repetitions for a RA preamble transmission in a resource from the resource set and with a number of repetitions for a response to the RA preamble transmission; and

a response to the RA preamble transmission wherein the response is received for a maximum number of repetitions that is associated in the system information block with the number of repetitions for the RA preamble transmission;

a controller configured to determine a number of repetitions for a transmission of a RA preamble and a corresponding resource set; and

a transmitter configured to transmit the RA preamble for the number of repetitions in a resource from the resource set.

19. The UE of claim 18, wherein after receiving the response to the RA preamble, the apparatus transmits to the base station a message with a number of repetitions determined from the number of repetitions for the transmission of the RA preamble.

20. The UE of claim 18, wherein if the number of repetitions for the response to the RA preamble is one, the resources for the reception of the response to the RA preamble are informed by downlink control information format in a control channel and if the number of repetitions for the response to the RA preamble is larger than one, the resources for the reception of the response to the RA preamble are informed by the system information block.