US-12621875-B2 - Access method and related device

US12621875B2US 12621875 B2US12621875 B2US 12621875B2US-12621875-B2

Abstract

A network device sends a contention resolution message to a terminal device, and in instances when the network device determines that a target ACK sent by the terminal device is not received on an uplink carrier, the network device sends a first uplink grant message to the terminal device on a data transmission carrier. The terminal device may send a first message to the network device on the data transmission carrier based on the first uplink grant message. In this way, the network device can determine, based on the first message received on the data transmission carrier, whether the terminal device successfully resolves a contention problem, to avoid an access failure caused by missing detection of the target ACK, and improve an access success rate of the terminal device.

Inventors

Hai Huang

Assignees

HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230323
Priority Date: 20200924

Claims (9)

1 . An access method, comprising: sending, by a network device, a contention resolution message to a terminal device; determining, by the network device, that a target acknowledge (ACK) character sent by the terminal device indicating successful resolution by the terminal device of a contention problem is not received on an uplink carrier; sending, by the network device on a data transmission carrier, a first uplink grant message to the terminal device, the first uplink grant message instructing the terminal device to send a first message to the network device on the data transmission carrier instructing the network device to determine whether the terminal device has successfully resolved the contention problem; demodulating, by the network device, the first message; and sending, by the network device on the data transmission carrier, a second uplink grant message to the terminal device when the network device successfully demodulates the first message, the second uplink grant message instructing the terminal device to send a second message to the network device on the data transmission carrier.
2 . The access method according to claim 1 , wherein the first message comprises a buffer status report (BSR) indicating a size of the second message.
3 . The access method according to claim 1 , the network device resending the contention resolution message to the terminal device on the data transmission carrier when the network device fails to demodulate the first message.
4 . A network device, comprising: at least one processor; and one or more memories including computer instructions that, when executed by the at least one processor, cause the network device to perform operations comprising: sending a contention resolution message to a terminal device; determining that a target acknowledge (ACK) character sent by the terminal device indicating successful resolution by the terminal device of a contention problem is not received on an uplink carrier; sending on a data transmission carrier a first uplink grant message to the terminal device, the first uplink grant message instructing the terminal device to send a first message to the network device on the data transmission carrier instructing the network device to determine whether the terminal device has successfully resolved the contention problem; demodulating the first message; and sending on the data transmission carrier, a second uplink grant message to the terminal device when the network device successfully demodulates the first message, the second uplink grant message instructing the terminal device to send a second message to the network device on the data transmission carrier.
5 . The network device according to claim 4 , the first message comprising a buffer status report (BSR) indicating a size of the second message.
6 . The network device according to claim 4 , execution of the instructions by the at least one processor further causing the network device to perform operations comprising: resending the contention resolution message to the terminal device on the data transmission carrier when the network device fails to demodulate the first message.
7 . A terminal device, comprising: at least one processor; and one or more memories including computer instructions that, when executed by the at least one processor, cause the terminal device to perform operations comprising: receiving a contention resolution message sent by a network device; receiving, on a data transmission carrier, a first uplink grant message sent by the network device, the first uplink grant message instructing the terminal device to send a first message to the network device on the data transmission carrier instructing the network device to determine whether the terminal device has successfully resolved a contention problem; sending the first message to the network device on the data transmission carrier; sending on the data transmission carrier, a second uplink grant message sent by the network device when the network device successfully demodulates the first message, receiving, the second uplink grant message instructing the terminal device to send a second message to the network device on the data transmission carrier; and sending the second message to the network device.
8 . The terminal device according to claim 7 , the first message comprising a buffer status report (BSR) indicating a size of the second message.
9 . The terminal device according to claim 7 , execution of the instructions by the at least one processor further causing the network device to perform operations comprising: receiving, on the data transmission carrier, the contention resolution message resent by the network device when the network device fails to demodulate the first message.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/CN2021/118115 filed on Sep. 14, 2021, which claims priority to Chinese Patent Application No. 202011017630.1 filed on Sep. 24, 2020. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD Embodiments of this disclosure relate to the communication field, and in particular, to an access method and a related device. BACKGROUND Narrowband internet of things (NB-IoT) is a technology that can be widely used around the world, and is also an important branch of internet of everything. The NB-IoT features wide coverage, a large quantity of connections, a high rate, low costs, low power consumption, an excellent architecture, and the like. A terminal device having a multi-carrier random access channel (RACH) access capability selects an available physical random access channel (PRACH) resource, namely, a physical resource block (PRB), between an anchor carrier and an uplink non-anchor carrier. If the resource block selected by the terminal device is a PRB 1, a corresponding downlink non-anchor (DL non-anchor) carrier of the PRB 1 in a configuration of a system information block (SIB) 22 is a PRB 2. A base station configures, through a message 4 (msg4), the terminal device on another carrier PRB 3 to transmit a message 5 (msg5). In addition, subsequent service-related signaling and data between the base station and the terminal device are all transmitted on the PRB 3. In the foregoing RACH procedure, after the base station sends the msg4 to the terminal device, to ensure that the terminal device successfully receives the msg4, the terminal device returns a msg4 acknowledge character (ACK) to the base station. If the base station does not receive the msg4 ACK sent by the terminal device, the base station considers that the terminal device has not resolved a contention problem, and still retransmits the msg4 to the terminal device on the PRB 2. If the terminal device has received the msg4, but the network device does not receive the msg4 ACK from the terminal device due to factors such as a poor uplink signal, strong uplink interference, or the like, the base station retransmits the msg4 on the PRB 2. However, the terminal device needs to send the msg5 on the PRB 3, so the terminal device monitors a narrowband physical downlink control channel (NPDCCH) on the PRB 3. If the PRB 2 and the PRB 3 are different PRBs, the terminal device cannot receive the msg4 retransmitted and delivered by the base station, and does not return the msg4 ACK again. When retransmission of the msg4 reaches a maximum quantity of retransmissions in the base station or exceeds time specified by a contention resolution timer in the base station, access by the terminal device fails. SUMMARY Embodiments of this disclosure provide an access method and a related device. A network device can determine, based on a first message received on a data transmission carrier, whether a terminal device successfully resolves a contention problem, to avoid an access failure caused by missing detection of a target ACK, and improve an access success rate of the terminal device. A first aspect of this disclosure provides an access method. A network device sends a contention resolution message to a terminal device; the network device determines that a target acknowledge character ACK sent by the terminal device is not received on an uplink carrier, where the target ACK is used by the network device to determine whether the terminal device successfully resolves a contention problem; and the network device sends a first uplink grant message to the terminal device on a data transmission carrier, where the first uplink grant message indicates the terminal device to send a first message to the network device on the data transmission carrier, and the first message indicates the network device to determine whether the terminal device successfully resolves the contention problem. After the network device sends the contention resolution message to the terminal device, if the network device determines that the target ACK sent by the terminal device is not received on the uplink carrier, the network device sends the first uplink grant message to the terminal device on the data transmission carrier. The terminal device may send the first message to the network device on the data transmission carrier based on the first uplink grant message. In this way, the network device can determine, based on the first message received on the data transmission carrier, whether the terminal device successfully resolves the contention problem, to avoid an access failure caused by missing detection of the target ACK, and improve an access success rate of the terminal device. In a possible implementation of the first aspect, the method further includes: The network device demodulates the first message. In this possible i