KR100538836B1 - Data transmission confirmation in a wireless communication system - Google Patents

Abstract

The present invention provides a data discard signaling procedure in a wireless communication system. Radio Link Control (RLC) checks PDCP in order. Ordered acknowledgment means that the acknowledgment is passed to the PDCP in the same order that the PDCP PDUs are provided by the PDCP. The transmitting RLC acknowledgment mode (AM) entity identifies PDCP service data units (SDUs) having a sequence number (SN) that has been confirmed and acknowledged by the corresponding receiving RLC AM entity. In this way, PDCP PDUs and corresponding PDCP SDUs with SNs not specifically acknowledged will not be deleted by the transmitting PDCP entity. Another solution provided by the present invention is that if the SN of a PDCP SDU delivered to a PDCP PDU identified by RLC is greater than the lowest SN of an unidentified PDCP SDU, then the SN of the PDCP SDU indicated by the confirmation is the lowest or the first. PDCP deletes the corresponding SDU identified by the PDCP PDU and the RLC until the SN is. Accordingly, the present invention provides a data transmission confirmation procedure that effectively eliminates the problems present in lossless SRNS relocation and synchronization of PDCP sequence numbers and improves the performance of a wireless communication system.

Description

DATA TRANSMISSION CONFIRMATION IN A WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a wireless communication protocol. More specifically, the present invention discloses a procedure for confirming data transmission.

Wireless communication systems have been developing rapidly. New wireless communication methods, services, and standards are being developed worldwide. In particular, over the last few years, this development has been accelerated, during which the mobile wireless communications industry has grown significantly. Various technological advances have made portable wireless installations smaller, cheaper and more reliable. The exponential growth of mobile phones will continue in the next decade, and these wireless networks will interact with and eventually outpace existing wired networks.

Conventional wired systems provide a communication path between a source and a destination. This technique connects or allocates resources of the system between the base station and the mobile terminal. Such a connection is useful for maintaining voice communication, but data is usually transmitted after a long period of inactivity, resulting in a waste of resources.

In addition, the resources of the system may be wasted due to unnecessary disposal of data or unnecessary retransmission of data. In addition, the integrity of a wireless communication system can be compromised due to data loss or synchronization issues. Therefore, there is a need for an improved communication protocol that reduces waste of system resources and improves the performance of a wireless communication system.

In order to achieve at least the aforementioned advantages and to overcome the disadvantages of the prior art methods in accordance with the object of the invention as embodied and generally described herein, the invention provides a relocation and packet data convergence of a lossless serving radio network subsystem (SRNS). It provides a data transmission verification procedure that effectively eliminates the problems seen in synchronizing protocol (PDCP) sequence numbers and improves the performance of wireless communication systems.

Packet Data Convergence Protocol (PDCP) provides its services to higher layers, such as IP and PPP. PDCP provides the following functions: compression and decompression of the IP data stream headers (e.g. TCP / IP and RTP / UDP / IP headers for IPv4 and IPv6), transmission of user data, And maintains a PDCP sequence number (SN) for a radio bearer configured to support lossless SRNS relocation. PDCP utilizes the services provided by the radio link control (RLC) sublayer.

Relocation of lossless SRNS can be applied only if the RLC is configured for in-sequence delivery mode and acknowledgment mode (AM). Support for lossless SRNS relocation is configured by higher layers. PDCP sequence numbering applies if lossless SRNS relocation is supported. The PDCP sequence number serves to acknowledge before relocating PDCP Service Data Units (SDUs) sent in advance. The value of the PDCP sequence number is in the range of 0 to 65535. The size of the PDCP SN window indicates the maximum number of PDCP SDUs that were not confirmed successfully transmitted to the sibling entity by the RLC layer, which may be numbered at any given time. The window size of PDCP SN is configured by higher layer. The PDCP sequence number is set to "0" when the PDCP entity is first set up.

Since the radio bearer is configured to support lossless SRNS relocation, when the PDCP requests the AM RLC to send a PDCP Protocol Data Unit (PDU), the AM RLC needs to confirm receipt of the PDCP PDU by the sibling-RLC AM entity. There is. Once all acknowledgment mode data (AMD) PDUs forming the PDCP PDU are acknowledged by the receiving AM RLC entity once, the sending AM RLC entity notifies the PDCP. The confirmation delivered by the RLC may or may not be the same as the order in which the PDCP PDUs are provided to the RLC. When the PDCP receives an RLC acknowledgment, the PDCP saves memory space by deleting the PDCP PDU and the corresponding PDCP SDU indicated by the acknowledgment from the buffer. If PDCP deletes the PDCP PDU and the corresponding PDCP SDU indicated by the RLC check, problems appear in lossless SRNS relocation and PDCP sequence number synchronization.

Note that the transmitting PDCP entity is a PDCP entity that transmits PDCP PDUs provided to the RLC. The receiving PDCP entity is a PDCP entity that receives PDCP PDUs delivered from the RLC. The transmitting RLC AM entity is an RLC AM entity that transmits RLC PDUs. The receiving RLC AM entity is an RLC AM entity that receives RLC PDUs.

Assume that the transmitting PDCP entity transmits 10 PDCP data PDUs that convey a compressed or uncompressed PDCP SDU to its data field. The sequence number of these 10 PDCP SDUs is 0-9. Also assume that the transmitting PDCP entity receives a transmitting RLC AM entity confirmation indicating that PDCP data PDUs conveying PDCP SDUs with SN = 0, 1, 5, 7, 8, 9 were successfully received by the receiving RLC AM entity. . Thus, these PDCP PDUs and corresponding SDUs identified by the transmitting RLC AM entity are deleted from the buffer, and PDCP data PDUs and corresponding PDCP SDUs with SN = 2, 3, 4, 6 are still in the buffer.

Because it is configured to deliver in order, the receiving RLC AM entity delivers only PDCP data PDUs conveying PDCP SDUs with SN = 0, 1 to the receiving PDCP entity. AMD PDUs forming PDCP data PDUs carrying PDCP SDUs with SN = 5, 7, 8, 9 are in the RLC buffer.

However, following the scenario described above can cause problems. When a lossless SRNS relocation occurs, the transmitting RLC AM entity and the receiving RLC AM entity are reset. The receiving RLC AM entity discards all AMD PDUs, and the sending PDCP entity and the receiving PDCP entity exchange receiving SNs during SRNS relocation. The transmitting PDCP entity receives the next expected receiving PDCP (SN = 2) sent by the receiving PDCP entity, and starts sending PDCP data PDUs carrying the PDCP SDUs from SN = 2. PDCP data PDUs conveying PDCP SDUs with SN = 2, 3 ... 9 are intended to be retransmitted, but this means that PDCP data PDUs conveying PDCP SDUs with SN = 5, 7, 8, and 9 are relocated by the sending PDCP entity It is impossible because it has been deleted.

Following the above scenarios can lead to other problems. When the RLC is reset, the receiving RLC AM entity discards all received AMD PDUs. According to the foregoing description, the transmitting PDCP entity must provide one PDCP SeqNum PDU, which, after the reset of the RLC, has the first unidentified PDCP SDU as its data field as its sequence number field after the reset of the RLC. Pass the SN of the SDU to the sending RLC AM entity. In this case, the first unidentified PDCP PDU is a PDCP SDU with SN = 2. PDCP data PDUs carrying PDCP SDUs with SN = 3 ... 9 are intended to be retransmitted, but this is deleted by PDCP entities with PDCP data PDUs carrying PDCP SDUs with SN = 5, 7, 8, and 9 before the RLC reset. It is impossible.

Accordingly, the present invention provides a solution that overcomes at least the aforementioned problem.

RLC checks PDCP in-sequence. Ordered acknowledgment means that the acknowledgment is delivered to the PDCP in the same order that the PDCP PDUs are sent by the PDCP. In the above scenario using the present invention, the transmitting RLC AM entity only identifies PDCP SDUs with SN = 0, 1, and does not identify PDCP SDUs with SN = 5, 7, 8, and 9. In this manner, PDCP PDUs and corresponding PDCP SDUs with SN = 5, 7, 8, 9 will not be deleted by the transmitting PDCP entity. The transmitting RLC AM entity does not acknowledge the PDCP PDUs and corresponding SDUs with SN = 5 until the corresponding SDUs with SN = 2, 3, 4 have been confirmed and acknowledged by the sibling RLC AM entity. Similarly, until the PDCP PDUs and corresponding PDCP SDUs with SN = 2, 3, 4, 6 are positively acknowledged by the corresponding receiving RLC AM entity, the transmitting RLC AM entity is assigned with PDCP PDUs and SN = 7, 8, Do not check the corresponding PDCP SDUs.

Another embodiment of the present invention provides another solution to at least the aforementioned problem.

If the SN of the PDCP SDU conveyed to the PDCP PDU identified by the RLC is greater than the lowest SN of the unidentified PDCP SDU, then the PDCP is assigned to the PDCP PDU until the SN of the PDCP SDU indicated by the confirmation is the lowest or first SN. And the corresponding SDU identified by RLC shall not be deleted. Referring to the above-described scenario using the present invention, the transmitting RLC AM entity identifies PDCP PDUs and corresponding SDUs with SN = 0, 1, 5, 7, 8, and 9, and the lowest SN of the unidentified PDCP SDU is 2. PDCP PDUs and corresponding PDCP SDUs with SN = 0, 1 are deleted. PDCP PDUs and their corresponding PDCP SDUs with SN = 5, 7, 8, and 9 are not deleted immediately. PDCP PDUs and corresponding SDUs with SN = 5 are not deleted until the corresponding SDUs with SN = 2, 3 and 4 are identified. PDCP PDUs and corresponding PDCP SDUs with SN = 7, 8, and 9 are not deleted until the corresponding PDCP SDUs with SN = 2, 3, 4, 6 are identified.

The present invention provides a data transmission verification procedure that effectively eliminates problems in lossless SRNS relocation and PDCP sequence number synchronization and improves the performance of a wireless communication system.

Those skilled in the art will clearly understand the foregoing and other objects of the present invention by reading the following detailed description of the preferred embodiments.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and intended to further explain the invention claimed herein.

The accompanying drawings are included to provide a further understanding of the invention, and are an integral part of the description. The drawings illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

The preferred embodiments of the invention are now described in detail, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the specification to refer to the same or similar parts.

Packet Data Convergence Protocol (PDCP) provides its services to higher layers, such as IP and PPP. PDCP provides the following functions: compression and decompression of IP data stream headers (e.g., TCP / IP and RTP / UDP / IP headers for IPv4 and IPv6) and transmission of user data on each of the transmitting and receiving entities. Function and maintenance of PDCP sequence numbers for radio bearers configured to support lossless SRNS relocation. PDCP utilizes the services provided by the radio link control (RLC) sublayer.

Lossless SRNS relocation can be applied only if the RLC is configured for sequential delivery mode and acknowledgment mode (AM). Support for lossless SRNS relocation is configured by higher layers. If lossless SRNS relocation is supported, PDCP sequence numbering should be applied. The PDCP sequence number serves to acknowledge before relocating the PDCP SDUs transmitted in advance. The value of the PDCP sequence number is in the range of 0 to 65535. The size of the PDCP SN window indicates the maximum number of PDCP SDUs that were not confirmed to have been successfully transmitted to an sibling entity by the RLC layer, which may be numbered at any given time. The size of the PDCP SN window is configured by the higher layer. The PDCP sequence number is set to "0" when the PDCP entity is first set up.

Hereinafter, "receive from lower layer of PDCP SDU / receive from lower layer" means receiving from lower layer of PDCP data PDU or PDCP SeqNum PDU that carries a compressed or uncompressed PDCP SDU into its data field. It is used in the same sense. The PDCP sequence number is applied to each radio bearer.

On your equipment (UE):

The UL_Sending PDCP Sequence Number should be set to "0" for the first PDCP SDU transmitted to the lower layer.

-The UL_Sending PDCP Sequence Number shall be incremented by "1" for the next PDCP SDU provided to the lower layer.

The DL_Receive PDCP Sequence Number should be set to "0" for the first PDCP SDU received from the lower layer.

DL_Receive PDCP Sequence Number shall be incremented by "1" for the next PDCP SDU received from the lower layer.

In the land radio access network (UTRAN) of a comprehensive mobile communication system:

DL_Sending PDCP sequence number should be set to "0" for the first PDCP SDU transmitted to the lower layer.

DL_Sending PDCP sequence number shall be incremented by "1" for the next PDCP SDU transmitted to the lower layer.

The UL_Receiving PDCP Sequence Number should be set to "0" for the first PDCP SDU received from the lower layer.

The UL_Receive PDCP Sequence Number shall be incremented by "1" for the next PDCP SDU received from the lower layer.

The PDCP sequence number is not decremented at the PDCP entity.

For radio bearers that are configured to support lossless SRNS relocation, the PDCP entity

The PDCP entity must synchronize the PDCP SN after the RLC reset or RLC reset not caused by SRNS relocation;

If an invalid "order number of the next expected UL / DL received PDCP" is received from the higher layer after relocation:

The UE / UTRAN PDCP entity triggers a synchronization procedure of the PDCP SN by sending one PDCP SeqNum PDU to the lower layer;

Consider that the synchronization procedure is completed by confirming successful transmission of the PDCP SeqNum PDU by the lower layer.

In UE / UTRAN, "Next expected UL / DL_receive PDCP sequence number" is the transmit PDCP of the first PDCP SDU that is less than or equal to the transmit PDCP SN of the first PDCP SDU whose value has been transmitted but not yet acknowledged. If greater than SN, it is considered invalid.

In the transmission of the PDCP SeqNum PDU:

The UE PDCP entity,

   Set the value of the DL_Receive PDCP sequence number to the value indicated in the PDCP SeqNum PDU;

-UTRAN PDCP entity,

   -Set the value of the UL_Receive PDCP sequence number to the value indicated in the PDCP SequNum PDU.

For lossless SRNS relocation procedure:

The UTRAN shall send the next expected UL_receive PDCP sequence number to the UE;

-UE shall transmit the next expected DL_receiving PDCP sequence number to UTRAN.

This information exchange synchronizes the sequence numbers of the UE and UTRAN PDCP entities.

When the information exchange is requested by the higher layer, each radio bearer is configured to support lossless SRNS relocation, so that the PDCP sublayer of the source RNC should transmit the following to the target RNC.

UL_receiving PDCP SN of the next PDCP SDU expected to be received from the UE;

The DL_sending PDCP SN of the first PDCP SDU transmitted but not yet acknowledged;

DL_transmitting PDCP SNs associated with PDCP SDUs transmitted but not yet acknowledged; And

PDCP SDUs not yet transmitted.

Reference is made to FIG. 1, which illustrates a RLC sublayer structure, and FIG. 2, which illustrates a PDCP PDU structure.

Since the radio bearer is configured to support lossless SRNS relocation, when the PDCP requests the AM RLC to send the PDCP PDU 130, the AM RLC sends the reception of the PDCP PDU 130 to the sibling RLC AM entity 150. It is necessary to confirm by. Once all the AMD PDUs 210 forming the PDCP PDU 240 are acknowledged by the receiving AM RLC entity 150 once, the sending AM RLC entity 120 notifies the PDCP. The confirmation delivered by the RLC may or may not be the same order in which the PDCP PDUs 130 are sent to the RLC. When the PDCP receives the RLC acknowledgment, the PDCP saves memory space by deleting the PDCP PDU 240 and the corresponding PDCP SDU indicated by the acknowledgment from the buffer. If PDCP deletes the PDCP PDU 240 and the corresponding PDCP SDU indicated by RLC check, problems appear in lossless SRNS relocation and PDCP sequence number synchronization. See the scenarios and issues below.

Before discussing the scenarios and problems described below, terms used in the description of the scenarios and problems are defined.

The transmitting PDCP entity is a PDCP entity that transmits PDCP PDUs provided to the RLC.

The receiving PDCP entity is a PDCP entity that receives PDCP PDUs delivered from the RLC.

The transmitting RLC AM entity is an RLC AM entity that transmits RLC PDUs 210.

The receiving RLC AM entity is an RLC AM entity that receives the RLC PDUs 210.

Assume that the transmitting PDCP entity transmits 10 PDCP data PDUs 240 carrying a compressed or uncompressed PDCP SDU into its data field. The sequence number SN of these 10 PDCP data SDUs 240 is 0-9. The sending PDCP entity receives a sending RLC AM entity confirmation indicating that PDCP data PDUs 240 conveying PDCP SDUs with SN = 0, 1, 5, 7, 8, 9 were successfully received by the receiving RLC AM entity. do. Thus, the corresponding SDUs identified by the PDCP PDUs 240 and the sending RLC AM entity are deleted from the buffer and the PDCP data PDUs 240 and corresponding PDCP SDUs with SN = 2, 3, 4, 6 are still in the buffer.

Because it is configured to deliver in order, the receiving RLC AM entity delivers only PDCP data PDUs 240 conveying PDCP SDUs with SN = 0, 1 to the receiving PDCP entity. The AMD PDUs forming PDCP data PDUs 240 conveying PDCP SDUs with SN = 5, 7, 8, 9 are in an RLC buffer.

However, following the scenario described above can cause problems. When a lossless SRNS relocation occurs, the transmitting RLC AM entity and the receiving RLC AM entity are reset. The receiving RLC AM entity 150 discards all AMD PDUs, and the sending PDCP entity and the receiving PDCP entity exchange receiving SNs during SRNS relocation. Transmitting PDCP entity 120 receives the next expected received PDCP (SN = 2) sent by receiving PDCP entity 150 and begins transmitting PDCP data PDUs 240 that carry PDCP SDUs from SN = 2. PDCP data PDUs 240 conveying PDCP SDUs with SN = 2, 3 ... 9 are intended to be retransmitted, but this is because PDCP data PDUs conveying PDCP SDUs with SN = 5, 7, 8, and 9 This is not possible because) was deleted prior to SNRS relocation.

Following the above scenarios can lead to other problems. When the RLC is reset, the receiving RLC AM entity 150 discards all received AMD PDUs. According to the foregoing description, the transmitting PDCP entity 120 should provide one PDCP SeqNum PDU, which one PDCP SeqNum PDU is the first unidentified PDCP SDU as its data field after the reset of the RLC. The furnace passes the SN of this SDU to the transmitting RLC AM entity 120. In this case, the first unidentified PDCP PDU is a PDCP SDU with SN = 2. PDCP data PDUs 240 conveying PDCP SDUs with SN = 3 ... 9 are intended to be retransmitted, but this is because PDCP data PDUs 240 conveying PDCP SDUs with SN = 5, 7, 8, and 9 are sent to the sending PDCP entity. This is not possible because it was deleted before the RLC reset.

Accordingly, the present invention provides the following solution which overcomes at least the aforementioned problem.

RLC checks PDCP in-sequence. Ordered acknowledgment means that the acknowledgment is passed to the PDCP in the same order that the PDCP PDUs are provided by the PDCP. In the above-described scenario using the present invention, the transmitting RLC AM entity only identifies PDCP SDUs with SN = 0, 1 and does not identify PDCP SDUs with SN = 5, 7, 8, and 9. In this manner, PDCP PDUs and corresponding PDCP SDUs with SN = 5, 7, 8, 9 will not be deleted by the transmitting PDCP entity. The transmitting RLC AM entity does not acknowledge the PDCP PDUs and corresponding SDUs with SN = 5 until the corresponding SDUs with SN = 2, 3, 4 have been acknowledged by the corresponding receiving RLC AM entity. Similarly, until the PDCP PDUs and corresponding PDCP SDUs with SN = 2, 3, 4, 6 are positively acknowledged by the corresponding receiving RLC AM entity, the transmitting RLC AM entity is assigned with PDCP PDUs and SN = 7, 8, Do not check the corresponding PDCP SDUs.

Embodiments of the present invention provide another solution to at least the above-mentioned problem.

If the SN of the PDCP SDU conveyed to the PDCP PDU identified by the RLC is greater than the lowest SN of the unidentified PDCP SDU, then the PDCP is assigned to the PDCP PDU until the SN of the PDCP SDU indicated by the confirmation is the lowest or first SN. And the corresponding SDU identified by RLC shall not be deleted. Referring to the above-described scenario using the present invention, the transmitting RLC AM entity identifies PDCP PDUs and corresponding SDUs with SN = 0, 1, 5, 7, 8, and 9, and the lowest SN of the unidentified PDCP SDU is 2. PDCP PDUs and corresponding PDCP SDUs with SN = 0, 1 are deleted. PDCP PDUs and their corresponding PDCP SDUs with SN = 5, 7, 8, and 9 are not deleted immediately. PDCP PDUs and corresponding SDUs with SN = 5 are not deleted until the corresponding SDUs with SN = 2, 3 and 4 are identified. PDCP PDUs and corresponding PDCP SDUs with SN = 7, 8, and 9 are not deleted until the corresponding PDCP SDUs with SN = 2, 3, 4, 6 are identified.

Accordingly, the present invention provides a data transmission verification procedure that effectively eliminates problems in lossless SRNS relocation and PDCP sequence number synchronization and improves the performance of a wireless communication system.

Note that the present invention has been described with examples of PDCP and RLC applications. However, when the present invention is implemented in other applications, systems or apparatuses, it is possible to enjoy the benefits and advantages of the present invention. The invention is not limited to PDCP or RLC applications. For example, in the above example, a higher layer may be used in place of PDCP. Embodiments of the invention also include applications in other systems or environments. The present invention can be used in a wide variety of applications, protocols, systems and devices, and as a result has the advantage of improving the performance and integrity of the applications in which the present invention is used.

According to the data transmission confirmation procedure of the present invention, the problems appearing in lossless SRNS relocation and PDCP sequence number synchronization are effectively excluded and the performance of the wireless communication system is improved.

Those skilled in the art will clearly appreciate that various modifications and variations can be made without departing from the scope and spirit of the invention. In view of the foregoing, it is intended that the present invention include modifications and variations of this invention and equivalents thereof which are intended to be within the scope of the invention.

1 illustrates an RLC sublayer structure in accordance with an embodiment of the present invention.

2 illustrates a PDCP PDU structure in accordance with an embodiment of the present invention.

Claims (7)

delete As a method of improving the performance of a wireless communication system, Sending, by the PDCP entity, a plurality of Packet Data Convergence Protocol (PDCP) protocol data units (PDUs); Receiving by the RLC entity the plurality of PDCP PDUs; Sending, by the RLC entity, an acknowledgment that each of the plurality of PDCP PDUs has been received correctly; Receiving the confirmation by the PDCP entity; Deleting, by the PDCP entity, the PDCP PDU associated with the verification; If support for lossless SRNS relocation is configured for the PDCP entity, confirmations are sent in the same order that the PDCP PDUs were sent by the PDCP entity. 3. The method of claim 2, further comprising deleting a PDCP SDU associated with the deleted PDCP PDU. As a method of improving the performance of a wireless communication system, Sending, by the PDCP entity, a plurality of Packet Data Convergence Protocol (PDCP) protocol data units (PDUs); Receiving by the RLC entity the plurality of PDCP PDUs; Sending, by the RLC entity, an acknowledgment that each of the plurality of PDCP PDUs has been received correctly; Receiving the confirmation by the PDCP entity; Deleting, by the PDCP entity, the PDCP PDU associated with the verification; If support for lossless SRNS relocation is configured for the PDCP entity, confirmations are sent in the same order that PDCP SDUs are sent by the PDCP entity. 5. The method of claim 4, further comprising deleting a PDCP SDU associated with the deleted PDCP PDU. As a method of improving the performance of a wireless communication system, Sending, by the PDCP entity, a plurality of Packet Data Convergence Protocol (PDCP) protocol data units (PDUs); Receiving by the RLC entity the plurality of PDCP PDUs; Sending, by the RLC entity, an acknowledgment that each of the plurality of PDCP PDUs has been received correctly; Receiving the confirmation by the PDCP entity; Deleting, by the PDCP entity, the PDCP PDU associated with the verification; If support for lossless SRNS relocation is configured for the PDCP entity and the sequence number of the unidentified PDCP SDU is not less than the sequence number for the PDCP SDU indicated by the acknowledgment, the PDCP entity is assigned the PDCP PDU indicated by the acknowledgment. The method of improving the performance of a wireless communication system. 7. The method of claim 6, wherein the PDCP entity deletes a PDCP SDU associated with the deleted PDCP PDU.