CA-3042160-C - UPLINK TRANSMISSION PARAMETER SELECTION FOR RANDOM ACCESS INITIAL MESSAGE TRANSMISSION AND RETRANSMISSION

Abstract

Methods, systems, and devices for wireless communication are described that provide for selecting different uplink transmission parameters for transmission or retransmission of a random access message. A user equipment (UE) may retransmit a random access message to a base station during a random access procedure if an initial transmission of the random access message was unsuccessfully received by the base station. The UE may select a different transmission beam, uplink resource, or transmission power for retransmission of the random access message. The selection may be based on path loss associated with synchronization signals or previous transmissions. The selection may also be based on a maximum number of retransmissions.

Inventors

• Muhammad Nazmul Islam
• Sumeeth Nagaraja
• Tao Luo
• Bilal Sadiq
• Junyi Li
• Sundar Subramanian

Assignees

• QUALCOMM INCORPORATED

Dates

Publication Date

20260505

Application Date

20171109

Priority Date

20171108

Claims (13)

1. 85231293 51 CLAIMS: 1. A method for wireless communication, comprising: identifying a first uplink transmission beam for a random access procedure; transmitting, to a base station, a random access message using the first uplink transmission beam; selecting a second uplink transmission beam based at least in part on an absence of a random access response from the base station corresponding to the random access message transmitted using the first uplink transmission beam and a current path loss estimate, the second uplink transmission beam having a different transmission direction than the first uplink transmission beam; determining a path loss difference between the current path loss estimate and a previous path loss estimate; determining an uplink transmission power based at least in part on a power ramping counter value, the path loss difference satisfying a threshold path loss difference, and the selection of the second uplink transmission beam; and retransmitting the random access message to the base station using the second uplink transmission beam and the determined uplink transmission power, wherein the power ramping counter value is based at least in part on a number ofretransmissions of the random access message and a number of times an uplink transmission beam is selected based at least in part on the absence of the random access response.
2. 2. The method of claim 1, wherein determining the uplink transmission power further comprises increasing the uplink transmission power by an additional amount, wherein the additional amount is based at least in part on the number of retransmissions.
3. 3. The method of claim 2, wherein: the additional amount is a function of the power ramping counter value.
4. 4. The method of claim 1, wherein the power ramping counter value is equal to the number of retransmissions minus the number of uplink transmission beam changes. Date re~ue/Date received 2024-01-24 85231293 52
5. 5. The method of claim 1, wherein determining the uplink transmission power further comprises: maintaining the power ramping counter value based at least in part on the second uplink transmission beam being different than the first uplink transmission beam, wherein the uplink transmission power is based at least in part on the maintained power ramping counter value.
6. 6. The method of claim 1, wherein determining the uplink transmission power further comprises: increasing the uplink transmission power by an additional amount, wherein the additional amount is equal to a power ramped amount associated with transmission of the random access message using the first uplink transmission beam.
7. 7. The method of claim 1, further comprising: receiving, from the base station, a maximum retransmission number, wherein retransmitting the random access message is based at least in part on the maximum retransmission number.
8. 8. The method of claim 7, wherein the maximum retransmission number is associated with at least one of a total number of retransmission attempts of the random access message, a number of retransmission attempts of the random access message for each of a plurality of uplink transmission powers, a number ofretransmission attempts of the random access message for each of a plurality of random access resources, or a number of retransmission attempts of the random access message for each combination of uplink transmission powers and random access resources.
9. 9. The method of claim 1, further comprising: selecting a random access resource for retransmission of the random access message, the random access resource corresponding to a lowest uplink transmission power.
10. 10. The method of claim 1, wherein determining the uplink transmission power further comprises: Date re~ue/Date received 2024-01-24 85231293 53 increasing the uplink transmission power by an additional amount based at least in part on determining that the path loss difference is greater than the threshold path loss difference.
11. 11. The method of claim 1, wherein determining the uplink transmission power further comprises: maintaining the uplink transmission power based at least in part on determining that the path loss difference is less than the threshold path loss difference.
12. 12. The method of claim 1, wherein the previous path loss estimate is associated with the transmission of the random access message using the first uplink transmission beam.
13. 13. The method of claim 1, wherein the previous path loss estimate is associated with a previous retransmission of the random access message. Date re~ue/Date received 2024-01-24

Description

WO 2018/111461 PCT/0S2017/060890 1 UPLINK TRANSMISSION PARAMETER SELECTION FOR RANDOM ACCESS INITIAL MESSAGE TRANSMISSION AND RETRANSMISSION CROSS REFERENCES [0001] The present Application for Patent claims priority to U.S. Patent Application No. 15/807, 132 by Islam et al., entitled "Uplink Transmission Parameter Selection for Random Access Initial Message Transmission and Retransmission," filed November 8, 2017; and U.S. Provisional Patent Application No. 62/435,463 by Islam et al., entitled "Uplink Transmission Parameter Selection for Random Access Initial Message Transmission and Retransmission," filed December 16, 2016; each of which is assigned to the assignee hereof BACKGROUND [0002] The following relates generally to wireless communication, and more specifically to uplink transmission parameter selection for transmission or retransmission of a random access initial message. [0003] Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multipleaccess systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system, or a New Radio (NR) system). A wireless multiple-access communications system may include a number of base stations or access network nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE). [0004] In some wireless systems, a UE may utilize a directional transmission to gain access to a medium. In some cases, the UE may retransmit the directional transmission if the UE does not receive an appropriate response from a base station ( e.g., due to interference, the base station may not receive the transmission from the UE). However, retransmitting the directional transmission in the same direction and using the same resources may not improve the probability of reception at the base station. WO 2018/111461 PCT/0S2017/060890 [0005] 2 SUMMARY The described techniques relate to improved methods, systems, devices, or apparatus that support uplink transmission parameter selection for random access initial message transmission or retransmission. In a wireless communications system, such as a millimeter wave (mmW) system, a base station and a user equipment (UE) may utilize directional transmissions during a random access channel (RACH) procedure. In some cases, after transmitting a directional initial RACH message, the UE may not receive an appropriate response from a base station and may then retransmit the directional initial RACH message, which may be referred to as a directional RACH request message. During retransmission, the UE may select different parameters (e.g., transmission power, RACH resources, beam) than those used in an initial transmission or in previous transmissions (e.g., if the UE is retransmitting multiple times). In a system with beam reciprocity, the UE may select the parameters based on a path loss estimate and a number of retransmissions. In some cases, the UE may have maximum numbers of retransmissions associated with a RACH resource, a beam, a transmission power, or a combination thereof. In a system without beam reciprocity, the UE may select the parameters based on the path loss estimate and a maximum difference in array gain for the base station between uplink and downlink beams. [0006] A method of wireless communication is described. The method may include identifying a first uplink transmission beam for a random access procedure, transmitting, to a base station, a random access message using the first uplink transmission beam, selecting a second uplink transmission beam based at least in part on an absence of a random access response from the base station corresponding to the random access message transmitted using the first uplink transmission beam, determining an uplink transmission power based at least in part on the selection of the second uplink transmission beam, and retransmitting the random access message to the base station using the second uplink transmission beam and the determined uplink transmission power. [0007] An apparatus for wireless communication is described. The apparatus may include means for identifying a first uplink transmission beam for a random access procedure, means for transmitting, to a base station, a random access message using the first uplink transmission beam, means for selecting a second uplink transmission beam based at least in part on an absence of a random access response from the base station corresponding to the random access message transmitted using the first up