Intra-cell switching method

Abstract

The present invention discloses an intra-cell handover method, comprising: a base station responding to an intra-cell handover request triggered by a terminal, establishing a new RLC entity and a new MAC entity; wherein the new MAC entity uses a newly allocated C-RNTI, the base station sends an RRC reconfiguration message to the terminal, the terminal validates the C-RNTI as the newUE-Identity information element value based on the newUE-Identity information element carried in the reconfiguration message, updates the AS layer key, the base station receives an RRC reconfiguration completion message sent by the terminal that is encrypted and secured using the AS layer key, the base station decrypts and decrypts the RRC reconfiguration completion message using a newly derived key configured by the PDCP entity, and deletes the new RLC entity and the new MAC entity. This method can solve the problem of service discontinuity caused by the time difference between the key and the new C-RNTI between the base station and the terminal.

Description

Technical Field

[0001] The present invention relates to the technical field of LTE and NR wireless communication, and more specifically to an intra-cell handover method. Background Art

[0002] LTE (Long Term Evolution) and NR (New Radio) wireless communication technologies are now widely used in China and some countries abroad, with NR, in particular, expanding its application across various fields. Intra-cell handovers are often triggered by factors such as PDCP short sequence number overflow and TAU-triggered security changes. Currently, intra-cell handovers are typically handled by sending an RRC reconfiguration message to the terminal, carrying the necessary handover configuration information. After the RRC reconfiguration message is sent, the base station's PDCP entity is notified to update the encryption and security keys and the MAC entity is notified of the new C-RNTI. Because the transmission of the RRC reconfiguration message between the base station and the terminal takes time, and there may be a time difference between the encryption keys and the new C-RNTI taking effect between the base station and the terminal, when the base station receives the new C-RNTI for the handover MSG1, the base station scheduler may continue to schedule downlink buffered data packets and retransmitted data and signaling packets in scenarios where services are in progress or air interface quality is poor. These packets use the encryption and security keys from before the handover, but the terminal may already have the new keys in effect. Consequently, decryption and security will fail and re-establishment will occur, resulting in service discontinuity. Summary of the Invention

[0003] An embodiment of the present invention provides an intra-cell handover method, including:

[0004] The base station responds to the intra-cell handover request triggered by the terminal and establishes a new RLC entity and a new MAC entity;

[0005] The base station RRC entity constructs an RRC reconfiguration message, the message body of which carries the fullConfig information element, the newUE-Identity information element, and the masterKeyUpdate information element;

[0006] The base station PDCP entity encrypts the RRC reconfiguration message and sends it to the terminal through the old RLC and old MAC entities;

[0007] The base station triggers the PDCP entity to be reestablished and configures the PDCP with a new key for the intra-cell handover.

[0008] The terminal completes entity reconstruction based on the fullConfig information element, newUE-Identity information element, and masterKeyUpdate information element, changes the C-RNTI to the value of the newUE-Identity information element, updates the AS layer key, and then generates an RRC reconfiguration complete message, which is sent to the base station through the new MAC entity and the new RLC entity.

[0009] The base station decrypts and decodes the RRC reconfiguration complete message according to the newly derived key configured by the PDCP entity;

[0010] The base station deletes the new RLC entity and the new MAC entity, completing the intra-cell handover.

[0011] Preferably, the fullConfig information element is used to instruct the terminal to reestablish the PDCP, RLC and MAC entities, and clear the PDCP short sequence number.

[0012] Preferably, the newUE-Identity information element complies with TS 38.331 Radio Resource Control RRC protocol specification.

[0013] Preferably, after the PDCP entity of the base station encrypts and secures the RRC reconfiguration message, the PDCP entity sends the DLDCCHDATA carrying the RRC reconfiguration message to the old RLC;

[0014] The old RLC sends a New DL SRB Data message carrying an RRC reconfiguration message to the terminal, and at the same time continues to send buffered data and signaling packets to the terminal from the old RLC.

[0015] Preferably, the new MAC entity adopts the newly allocated C-RNTI.

[0016] Preferably, after the terminal validates the C-RNTI as the value of the newUE-Identity information element, it sends a MSG1 data packet carrying the new C-RNTI to the new MAC entity;

[0017] The new MAC entity verifies the new C-RNTI, takes effect on the new C-RNTI, and sends a MSG2 message to the terminal.

[0018] The embodiment of the present invention provides an intra-cell handover method, which has the following beneficial effects compared with the prior art:

[0019] The examples of the present invention can effectively improve the success rate of intra-cell handover and ensure service continuity, especially in the scenario of doing business or the intra-cell handover triggered by the scenario of poor air interface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A flow chart of an intra-cell handover method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] When intra-cell handover is triggered, the base station side creates new RLC and MAC entities, and then triggers the terminal to rebuild PDCP, RLC and MAC entities and clear the PDCP short sequence number (SN) by carrying the fullConfig (TS 38.331) information element in the RRCReconfiguration message sent to the terminal; the C-RNTI used by the new MAC entity on the base station side is consistent with the newUE-Identity (TS38.331) information element in the RRCReconfiguration message, ensuring that the reconfiguration completed MSG1 message is received on the new MAC.

[0023] See also Figure 1 An embodiment of the present invention provides an intra-cell handover method, which includes: when a base station performs an intra-cell handover, first creating a new RLC and MAC entity, wherein the newly created MAC entity uses the newly allocated C-RNTI for this handover; after the new RLC and MAC entities are created, the base station RRC entity constructs an RRCReconfiguration message, and the message body carries information such as fullConfig, newUE-Identity, masterKeyUpdate, etc. to notify the terminal that this handover requires full configuration, the base station PDCP entity encrypts the message and then sends it to the terminal through the old RLC and MAC entities; after the sending is successful, the base station side triggers the PDCP entity to rebuild and configures the PDCP with a new key for this intra-cell handover, and the PDCP entity uses the new key to decrypt and decrypt the RRCReconfigurationComplete message; after the base station side successfully receives the RRCReconfigurationComplete message, it deletes the old RLC and MAC entities, and this intra-cell handover is completed.

[0024] Step 1: When an intra-cell handover is triggered, the base station creates a new RLC and MAC entity respectively. The C-RNTI of the new MAC entity is the newly allocated C-RNTI for this intra-cell handover.

[0025] Step 2: The PDCP entity on the base station side encrypts and secures the RRCReconfiguration message using the key before the intra-cell handover and sends it to the terminal. The fullConfig information element carried in the RRCReconfiguration message instructs the terminal to perform full configuration and re-establish the PDCP, RLC, and MAC entities; the newUE-Identity (TS 38.331) information element carried is the newly allocated C-RNTI for this intra-cell handover; and the masterKeyUpdate information element carried in the message instructs the terminal to update the AS layer key.

[0026] Step 3: The base station triggers the PDCP entity to reestablish and configures a newly derived key for the PDCP entity so that the PDCP entity can use the new key to decrypt and decode the RRCReconfigurationComplete message for intra-cell handover.

[0027] Step 4. After receiving the above RRCReconfiguration message, the terminal derives the new AS layer key, rebuilds the MAC, RLC and PDCP entities on the terminal side, and validates the C-RNTI as the newUE-Identity information element value carried in the RRCReconfiguration message, and then uses the newly derived key to encrypt and complete the RRCReconfigurationComplete message.

[0028] Step 5: After the terminal successfully processes the RRCReconfiguration, it sends the MSG1 message. After the new MAC entity on the base station matches the MSG1, the new C-RNTI is effective and the terminal is replied with the MSG2 message.

[0029] Step 6: During this process, if the old MAC entity on the terminal side has untransmitted downlink data or retransmitted signaling messages, the terminal side cannot detect these messages; this is because the old MAC entity on the base station side is scrambled using the C-RNTI before the switch.

[0030] Step 7: After receiving the MSG2 message, the terminal sends an RRCReconfigurationComplete message. After successfully receiving the RRCReconfigurationComplete message, the base station deletes the old RLC and MAC entities.

[0031] The above disclosure is only a few specific embodiments of the present invention. Those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. However, the embodiments of the present invention are not limited to these. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A method for intra-cell handover, characterized in that: include: The base station responds to the intra-cell handover request triggered by the terminal and establishes a new RLC entity and a new MAC entity; The base station RRC entity constructs an RRC reconfiguration message, the message body of which carries the fullConfig information element, the newUE-Identity information element, and the masterKeyUpdate information element; The base station PDCP entity encrypts the RRC reconfiguration message and sends it to the terminal through the old RLC and old MAC entities; The base station triggers the PDCP entity to be reestablished and configures the PDCP with a new key for the intra-cell handover. The terminal completes entity reconstruction based on the fullConfig information element, newUE-Identity information element, and masterKeyUpdate information element, changes the C-RNTI to the value of the newUE-Identity information element, updates the AS layer key, and then generates an RRC reconfiguration complete message, which is sent to the base station through the new MAC entity and the new RLC entity. The base station decrypts and decodes the RRC reconfiguration complete message according to the newly derived key configured by the PDCP entity; The base station deletes the old RLC entity and the old MAC entity to complete the handover within the cell; The new MAC entity adopts the newly allocated C-RNTI; After the terminal validates the C-RNTI as the value of the newUE-Identity information element, it sends a MSG1 data packet carrying the new C-RNTI to the new MAC entity; The new MAC entity verifies the new C-RNTI, takes effect on the new C-RNTI, and sends a MSG2 message to the terminal.

2. The intra-cell handover method according to claim 1, wherein: The fullConfig information element is used to instruct the terminal to re-establish the PDCP, RLC and MAC entities, and clear the PDCP short sequence number.

3. The intra-cell handover method according to claim 1, wherein: The newUE-Identity information element complies with TS 38.331 Radio Resource Control RRC protocol specification.

4. The intra-cell handover method according to claim 1, wherein: After the base station PDCP entity encrypts and secures the RRC reconfiguration message, the PDCP entity sends the DL DCCH DATA carrying the RRC reconfiguration message to the old RLC; The old RLC sends a New DL SRB Data message carrying an RRC reconfiguration message to the terminal, and at the same time continues to send buffered data and signaling packets to the terminal from the old RLC.

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