HK1079363B - System for efficient recovery of node-b buffered data following mac layer reset - Google Patents

Description

Efficient recovery system for node-B buffered data after MAC layer reset

Technical Field

The present invention relates to the field of wireless communications. More particularly, the present invention relates to efficient reply to data transmissions between peer entities of a second Layer (Layer 2) automatic repeat request (ARQ) after a Medium Access Controller (MAC) Layer reset at an intermediate node through which the data transmissions are distributed. An example of such a transition scenario is a system that utilizes hybrid automatic repeat request (H-ARQ) and adaptive modulation and coding (AM & C) techniques.

Background

A third generation (3G) Universal Terrestrial Radio Access Network (UTRAN) has a plurality of Radio Network Controllers (RNCs), wherein each RNC is associated with one or more node Bs, and wherein each node B is associated with one or more cells.

Typically, these third generation (3G) Frequency Division Duplex (FDD) and Time Division Duplex (TDD) systems utilize the Radio Network Controller (RNC) to distribute (i.e., buffer and schedule) data transmissions to corresponding User Equipments (UEs). However, for the high speed channels of third generation (3G) mobile telephone systems, data is distributed using this node B. An example of these high speed channels is the high speed downlink shared channel (HS-DSCH). Since data is distributed by the node B, the data must be buffered for transmission by the node B. When the distribution entity (node B) associated with the User Equipment (UE) changes, the buffered data of the distribution entity may be lost. Since data is distributed by the intermediate node (node B), the RNC cannot know the latest transmission status of Packet Data Units (PDUs). Accordingly, the User Equipment (UE) has to detect data loss and request retransmission of the missing Packet Data Unit (PDU), such as with a status Packet Data Unit (PDU), via the Radio Network Controller (RNC). If the generation of the status Packet Data Unit (PDU) is delayed, the delay of data retransmission may become large and the quality of service (QoS) requirements may not be met.

In the case of the high speed downlink shared channel (HS-DSCH), the problem may be exacerbated because each Radio Network Controller (RNC) is associated with several node bs, and because of the handover of User Equipment (UE) cells, a mobile User Equipment (UE) has a greater chance of changing a node B (as compared to the chance of changing the Radio Network Controller (RNC)).

The high speed downlink shared channel (HS-DSCH) utilizes adaptive modulation and coding (AM & C) techniques for high speed data transmission and hybrid automatic repeat request (H-ARQ) techniques to increase the likelihood of successful data delivery. A serving high speed downlink shared channel (HS-DSCH) cell is changed when the User Equipment (UE) must change the cell associated with the Universal Terrestrial Radio Access Network (UTRAN) access point that performs transmission and reception of the serving high speed downlink shared channel (HS-DSCH) radio link. In addition, the serving high speed downlink shared channel (HS-DSCH) cell is changed when another cell achieves improved physical channel conditions and/or improved physical capacity.

Service high speed downlink shared channel (HS-DSCH) cell changes are of two types. When the User Equipment (UE) changes between two cells associated with the same Node B, the change is referred to as an Intra-Node B serving high speed downlink shared channel (HS-DSCH) cell change. In addition, when the User Equipment (UE) changes between two cells associated with different Node bs, the change is referred to as an outer Node B serving high speed downlink shared channel (HS-DSCH) cell change. When a serving high speed downlink shared channel (HS-DSCH) cell change occurs at an outer Node B, the Node B prior to the serving high speed downlink shared channel (HS-DSCH) cell change is referred to as the source Node B and the Node B after the serving high speed downlink shared channel (HS-DSCH) cell change is referred to as the target Node B.

Both the Radio Network Controller (RNC) and the User Equipment (UE) have peer Radio Link Controller (RLC) entities. The sending Radio Link Controller (RLC) entity sends a Sequence Number (SN) in the Packet Data Unit (PDU) header, which is provided to the receiving Radio Link Controller (RLC) entity to confirm that all Packet Data Units (PDUs) of the transmission are not missing. If a Packet Data Unit (PDU) loss occurs during the transmission (which can be detected by out-of-sequence delivery of the Packet Data Unit (PDU)), the receiving Radio Link Controller (RLC) entity transmits a status report Packet Data Unit (PDU) to inform the transmitting Radio Link Controller (RLC) entity of the loss of the Packet Data Unit (PDU). The status report Packet Data Unit (PDU) describes the status of successful and/or failed data transmissions. In addition, the status report Packet Data Unit (PDU) also indicates the number of missing or received sequence of Packet Data Units (PDUs). If a Packet Data Unit (PDU) is missing, the transmitting Radio Link Controller (RLC) entity retransmits a copy of the missing Packet Data Unit (PDU) to the receiving Radio Link Controller (RLC).

The transmitting Radio Link Controller (RLC) entity may also poll a status report Packet Data Unit (PDU) via the receiving Radio Link Controller (RLC) entity. The poll function provides a mechanism for the transmitting Radio Link Controller (RLC) entity to request the status of Packet Data Unit (PDU) transmissions. Although such hybrid automatic repeat request (H-ARQ) operations may eliminate partial failure transmissions and increase the likelihood of successful delivery of data, the Radio Link Controller (RLC) protocol layer is ultimately the primary key to ensuring successful delivery of data.

Due to dynamic changes in the transmission conditions, the high speed downlink shared channel (HS-DSCH) cell change must be achieved quickly in order to maintain a comparable quality of service (QoS). When the serving high speed downlink shared channel (HS-DSCH) cell changes, the User Equipment (UE) may stop transmission and reception from the source node-B until all existing Packet Data Units (PDUs) from the source node-B are successfully transmitted. Since the source node-B performs scheduling and buffering of data, and since the data rates are very high (e.g., 10Mb/sec or higher), considerable buffered data from the source node-B may be lost when the User Equipment (UE) performs a serving high speed downlink shared channel (HS-DSCH) cell change, particularly when performing inter-node-B handovers. The reasons for this data loss are: in the Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN) architecture, there is no mechanism for the source node B to buffer data for transfer to the target node B. When a serving high speed downlink shared channel (HS-DSCH) cell changes, the Radio Network Controller (RNC) cannot know how much data is lost in total when a data loss occurs, because the RNC does not know the source node B's buffered data.

Currently, conventional systems may employ two approaches for handling the buffered data recovery of the source node-B. After a high speed downlink shared channel (HS-DSCH) cell change, (1) the RNC specifically polls a status Packet Data Unit (PDU) via the UE, or (2) the RNC can transmit in the target cell, and out-of-order delivery understood by the UE will generate the status Packet Data Unit (PDU).

In the first case, where the RNC specifically polls for a status Packet Data Unit (PDU), first, the RNC must wait until the physical channel is established in the new cell. The status Packet Data Unit (PDU) request is then transmitted and received and processed by the User Equipment (UE). The User Equipment (UE) generates the status Packet Data Unit (PDU) and returns the status Packet Data Unit (PDU) to the RNC, which processes the status Packet Data Unit (PDU) and determines which Packet Data Units (PDU) require retransmission.

In the second case, where the RNC begins transmitting Packet Data Units (PDUs) directly from the stop location of the source cell, the User Equipment (UE) recognizes the out-of-sequence delivery of data and generates a status Packet Data Unit (PDU) for transmission back to the RNC. The Radio Network Controller (RNC) processes the status Packet Data Units (PDUs) and learns which Packet Data Units (PDUs) need to be retransmitted.

In both cases, if the source node-B buffered data needs to be recovered, a status Packet Data Unit (PDU) is processed, but proper reception of the retransmitted data by the User Equipment (UE) is delayed to a considerable extent. This is due to the delay of the User Equipment (UE) generating the status Packet Data Unit (PDU) and the reception of the status Packet Data Unit (PDU) by the Radio Network Controller (RNC). If the transmission is in the Radio Link Controller (RLC) acknowledged mode, the data will not be passed to the higher layer (layer) until in-sequence data transfer can be achieved. Therefore, the User Equipment (UE) will need to buffer the out-of-sequence data until the missing PDUs

(PDU) can be retransmitted. Not only does this result in transmission delays, but the User Equipment (UE) also requires an additional data buffer for continuous data reception until the missing data can be successfully retransmitted. Otherwise, the effective data transmission rate will be reduced, thereby affecting the quality of service (QoS). This design is also not practical due to the high cost of memory requirements.

Another problem with the transfer is the buffered data of the User Equipment (UE). Within the Medium Access Controller (MAC) layer, there are typically several hybrid automatic repeat request (H-ARQ) processors that perform H-ARQ processes. As shown in fig. 1, hybrid automatic repeat request (H-ARQ) processing is a method comprising: transmission endpoint (P1)_BTo P1_E) A plurality of parallel hybrid automatic repeat request (H-ARQ) processors, and a receiving endpoint (P1)_UETo P1_UE) A plurality of corresponding parallel hybrid automatic repeat request (H-ARQ) processors. Pairs of processors (e.g., P1)_BAnd P1_UE) A data block is repeatedly and sequentially attempted to be transmitted until the transmission is successful, thereby ensuring that each data block is received without error. The time required to achieve successful hybrid automatic repeat request (H-ARQ) transmissions varies from data block to data block. Since several data blocks are processed in parallel, the transmission order may not be maintained. Accordingly, when the receiving hybrid automatic repeat request (H-ARQ) processor successfully receives a data block, the data block is forwarded to a recording buffer for in-sequence delivery to the Radio Link Controller (RLC) layer. The recording buffers may rearrange the data blocks based on the transmission sequence numbers assigned to the data blocks before forwarding to the Radio Link Controller (RLC) layer.

These Radio Resource Controller (RRC) messages typically carry a Medium Access Controller (MAC) layer reset pointer to the User Equipment (UE) when the external Node B (Inter-Node B) or the internal Node B (Intra-Node B) moves. Upon receiving a Medium Access Controller (MAC) layer reset indicator, the User Equipment (UE) performs a number of functions including, but not limited to: flushing all buffers for which hybrid automatic repeat request (H-ARQ) is configured (i.e., breaking all high-speed media access controller (MAC-hs) layer Packet Data Units (PDUs) of the record buffers into dedicated media access controller (MAC-d) layer Packet Data Units (PDUs) and sending all dedicated media access controller (MAC-d) layer Packet Data Units (PDUs) to the dedicated media access controller (MAC-d) layer and its associated Radio Link Controller (RLC) entity to flush the record buffers. at external node-B transfers (including partial internal node-B transfers), the high-speed media access controller (MAC-hs) layer must be reset at the User Equipment (UE) to enable all hybrid automatic repeat request (H-ARQ) processes and all record buffers to be reset, thereby achieving data reception by a new high speed medium access controller (MAC-hs) layer entity of the target node-B.

After a serving high speed downlink shared channel (HS-DSCH) cell change, the correct status of successfully or unsuccessfully received Packet Data Units (PDUs) is not available until the procedure of the Medium Access Controller (MAC) layer reset is completed and the data blocks have been processed by the Radio Link Controller (RLC).

It is therefore a primary objective of the claimed invention to provide a system and method in which buffered data of the User Equipment (UE) can be compensated to properly maintain quality of service (QoS) requirements.

Disclosure of Invention

The present invention is a method and system in which the User Equipment (UE) and Radio Network Controller (RNC) perform a system action to reduce transmission delay and to avoid Packet Data Unit (PDU) loss during a Medium Access Controller (MAC) layer reset. The generating of the status Packet Data Unit (PDU) by the User Equipment (UE) is coupled to the Medium Access Controller (MAC) layer reset. After the Medium Access Controller (MAC) layer is reset, all Packet Data Units (PDUs) in the User Equipment (UE) MAC layer record buffer are cleared to the Radio Link Controller (RLC) entity due to the reception of a Medium Access Controller (MAC) layer reset request, and processed by the Radio Link Controller (RLC) entity before a Packet Data Unit (PDU) status report is generated. The Packet Data Unit (PDU) status report provides the status of all successfully received Packet Data Units (PDUs) to the Radio Network Controller (RNC). Thus, a Packet Data Unit (PDU) status report can be generated quickly. After the Radio Network Controller (RNC) receives a Packet Data Unit (PDU) status report, the missing Packet Data Unit (PDU) is interpreted and retransmitted to the User Equipment (UE).

Drawings

FIG. 1 is a block diagram illustrating hybrid automatic repeat request (H-ARQ) processing according to the prior art;

FIG. 2 is a flow chart showing fast recovery of User Equipment (UE) buffered data after a high speed downlink shared channel (HS-DSCH) cell change in accordance with the preferred embodiment of the present invention;

FIG. 3 is a flow chart illustrating a first alternative method of the present invention, wherein the Radio Network Controller (RNC) waits for a status Packet Data Unit (PDU) before beginning a new transmission of the target cell; and

fig. 4 is a flow chart illustrating a second alternative method of the present invention, wherein the Radio Network Controller (RNC) waits for a trigger signal before starting a new transmission of the target cell.

Detailed Description

The preferred embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements.

Please refer to the flowchart shown in fig. 2, which shows a first preferred embodiment of the present invention. The preferred embodiment includes: a method 10 of determining the status of the transmission of Packet Data Units (PDUs) to the User Equipment (UE) after a Medium Access Controller (MAC) layer reset condition, and the preferred embodiment has minimal delay. In this procedure, first, the Radio Network Controller (RNC) understands the need to reset the User Equipment (UE) Medium Access Controller (MAC) layer reset (step 12).

A possible cause of a User Equipment (UE) Medium Access Controller (MAC) layer reset is a serving high speed downlink shared channel (HS-DSCH) cell change. In the event that an outer node-B serving high speed downlink shared channel (HS-DSCH) cell change and in the event that an inner node-B serving high speed downlink shared channel (HS-DSCH) cell change in which the source node-B is equal to the target node-B but the transmission queue cannot be rerouted from the source cell to the target cell, the Radio Network Controller (RNC) notifies the node-B of the serving high speed downlink shared channel (HS-DSCH) cell change (step 14). In either case, a Medium Access Controller (MAC) layer reset is required. With the high speed downlink shared channel (HS-DSCH) cell change indication, the User Equipment (UE) is informed of the Radio Network Controller (RNC) Medium Access Controller (MAC) layer reset requirements such as: indicated via some radio data controller (RRC) information (step 16). It should be noted that step 16 may also be activated before step 14 and does not have any negative impact.

It will be appreciated by those skilled in the art that a Medium Access Controller (MAC) layer reset may have a number of reasons other than the HS-DSCH cell change, and that the method 10 may be adapted to determine the Packet Data Unit (PDU) transmission status by the RNC after the Medium Access Controller (MAC) layer reset. For example, the preferred embodiment may ensure a Medium Access Controller (MAC) layer reset whenever hybrid automatic repeat request (H-ARQ) processing by the node-B requires reactivation.

An identification code is present within the Radio Resource Controller (RRC) message, whereby the Medium Access Controller (MAC) layer can perform a reset. The identifier may be part of the serving high speed downlink shared channel (HS-DSCH) cell change, or the identifier may be part of a procedure to reset the Medium Access Controller (MAC) layer of the node B and User Equipment (UE) during an outer node B cell change or an inner node B cell change. Those skilled in the art will appreciate that the Medium Access Controller (MAC) layer has many features, including: a high speed medium access controller (MAC-hs) layer and a dedicated medium access controller (MAC-d) layer. For ease of explanation of the present invention, the preferred embodiment system is referred to as the Medium Access Controller (MAC) layer.

The high speed downlink shared channel (HS-DSCH) is a data transmission channel. Each data transport channel has several instances (instances) of the Radio Link Controller (RLC). These Radio Link Controller (RLC) instances (instances) are essentially logical channels, which may be mapped to the same transport channel; for example, several Radio Link Controller (RLC) entities may be mapped to a high speed downlink shared channel (HS-DSCH) of a single transport channel. One Radio Link Controller (RLC) instance (instance) is referred to as an Acknowledgement Mode (AM) if correct transmissions between peer Radio Link Controller (RLC) instances (instances) utilize automatic repeat request (ARQ) acknowledgements. A pair of Acknowledged Mode (AM) Radio Link Controller (RLC) entities use status Packet Data Units (PDUs) to enable the receiver to indicate to the sender the status of successful transmission of the Packet Data Units (PDUs). After the high speed downlink shared channel (HS-DSCH) cell change and a Medium Access Controller (MAC) layer reset, each Acknowledged Mode (AM) Radio Link Controller (RLC) instance associated with a particular high speed downlink shared channel (HS-DSCH) may generate a status Packet Data Unit (PDU).

Following the Medium Access Controller (MAC) layer reset indication, the Radio Resource Controller (RRC) message is received and processed by the Radio Resource Controller (RRC) of the User Equipment (UE) (step 18). The Radio Resource Controller (RRC) of the User Equipment (UE) checks whether a Medium Access Controller (MAC) layer reset indication is set, and informs the MAC layer of the Medium Access Controller (MAC) layer reset request after the MAC layer reset indication is set (step 20). Upon receiving the Medium Access Controller (MAC) layer reset request, the MAC layer resets and clears all Packet Data Units (PDUs) in the recording buffer to the Radio Link Controller (RLC) entity mapped to the high speed downlink shared channel (HS-DSCH) (step 22). All clear Packet Data Units (PDUs) are then processed using the Radio Link Controller (RLC) instance (instance) mapped to the high speed downlink shared channel (HS-DSCH) before generating a Packet Data Unit (PDU) status report (step 26).

The buffered delayed Packet Data Units (PDUs) require Radio Link Controller (RLC) processing to provide accurate and complete transmission status to the Radio Network Controller (RNC) before a Packet Data Unit (PDU) status report is generated. If a Packet Data Unit (PDU) status report can be generated early (i.e., before all buffered Packet Data Units (PDUs) in the Medium Access Controller (MAC) record queue are processed by the Radio Link Controller (RLC) instances), some of the Packet Data Units (PDUs) may be mistaken for not being received, and thus the Radio Network Controller (RNC) may generate unnecessary Packet Data Unit (PDU) retransmissions.

Several methods are known to ensure that all Packet Data Units (PDUs) have been processed by the Radio Link Controller (RLC), so that the Acknowledged Mode (AM) Radio Link Controller (RLC) entities can obtain the correct status of all successfully received Packet Data Units (PDUs). First, the Medium Access Controller (MAC) layer must forward Packet Data Units (PDUs) from each record queue in sequence, and then generate an "end of Packet Data Unit (PDU)" indication for each record queue.

In a second alternative, the last Packet Data Unit (PDU) of each record queue may have a special indication. These special indications are status reports of the receiving Radio Link Controller (RLC) Packet Data Units (PDUs) of the User Equipment (UE).

In a third alternative, the Radio Link Controller (RLC) acknowledges to the Medium Access Controller (MAC) layer the time to process Packet Data Units (PDUs), and, after processing all Packet Data Units (PDUs), the Medium Access Controller (MAC) layer also generates a Packet Data Unit (PDU) status request to the Radio Link Controller (RLC). It should be appreciated that many methods may be used to coordinate the Medium Access Controller (MAC) layer and the Radio Link Controller (RLC) to ensure that all Packet Data Units (PDUs) have been processed before the Packet Data Unit (PDU) status information is generated.

After receiving and processing the Packet Data Units (PDUs), the Acknowledged Mode (AM) Radio Link Controller (RLC) generates a Packet Data Unit (PDU) status report (step 26) indicating all successfully or unsuccessfully received Packet Data Units (PDUs). Each Acknowledged Mode (AM) Radio Link Controller (RLC) instance (instance) mapped to the high speed downlink shared channel (HS-DSCH) generates a Packet Data Unit (PDU) status report. In addition, the Acknowledged Mode (AM) Radio Link Controller (RLC) instance generates a Packet Data Unit (PDU) status report even though the RLC instance does not forward any Packet Data Units (PDUs) from the MAC layer. The User Equipment (UE) may then send Packet Data Unit (PDU) status reports for each Acknowledged Mode (AM) Radio Link Controller (RLC) instance (instance) associated with the high speed downlink shared channel (HS-DSCH) to the RNC.

In the Radio Network Controller (RNC), it is assumed that the Acknowledged Mode (AM) Radio Link Controller (RLC) and Medium Access Controller (MAC) entities are not informed: because the Medium Access Controller (MAC) layer reset must stop transmitting Packet Data Units (PDUs), the RNC continues to transmit Packet Data Units (PDUs) regardless of the Medium Access Controller (MAC) layer reset. Upon receiving Packet Data Unit (PDU) status reports for each Acknowledged Mode (AM) Radio Link Controller (RLC) instance (instance) associated with the high speed downlink shared channel (HS-DSCH), the RLC instance (instance) of the RNC processes the status reports (step 28) to determine missing Packet Data Units (PDUs) and generates Packet Data Unit (PDU) retransmissions as necessary to ensure successful data delivery. These retransmissions must take precedence over the existing transmission process in order to meet quality of service (QoS) requirements.

It should be noted that the need for a Medium Access Controller (MAC) layer reset is common to the need to generate a Packet Data Unit (PDU) status report. A request indication (or some common indication) may be sent to the User Equipment (UE) to simultaneously activate the Medium Access Controller (MAC) layer reset and generate the Packet Data Unit (PDU) status report. This User Equipment (UE) will then be able to perform the respective functions according to the following sequence.

According to a first preferred embodiment of the present invention, as shown in fig. 2, the Radio Network Controller (RNC) is capable of continuously transmitting Packet Data Units (PDUs) to the User Equipment (UE) when the data path is switched from one radio link to another. However, according to two alternative preferred embodiments of the present invention, as shown in fig. 3 and 4, when a high speed downlink shared channel (HS-DSCH) cell change or other event requiring a Medium Access Controller (MAC) layer reset occurs, data transmission is suspended until the next event occurs. It should be noted that in fig. 3 and 4, the steps having the same reference numerals as those in fig. 2 are identical. Therefore, the detailed description of these steps will not be repeated in the detailed description of fig. 3 and 4.

The second preferred embodiment of the present invention, as shown in fig. 3, has a method 10 of determining the status of the Packet Data Unit (PDU) transmissions to the User Equipment (UE) after a Medium Access Controller (MAC) layer reset condition, and has minimal delay. After the Radio Network Controller (RNC) understands the need for a Medium Access Controller (MAC) layer reset (step 12) and informs the node B and User Equipment (UE) (steps 14 and 16), the Radio Network Controller (RNC) suspends all downlink transmissions on the high speed downlink shared channel (HS-DSCH) (step 17). It should be noted that step 17 may also occur before step 14 or 16, and does not cause any negative effects. The Radio Network Controller (RNC) then receives the Packet Data Unit (PDU) status report (step 32). The Packet Data Unit (PDU) status report indicates that in the event of a change in a high speed downlink shared channel (HS-DSCH) cell, a Media Access Controller (MAC) layer reset caused Packet Data Unit (PDU) loss and other Packet Data Units (PDUs) loss at the source node-B. The Packet Data Unit (PDU) status report is then processed (step 34), and the missing Packet Data Units (PDUs) are retransmitted to the User Equipment (UE) (step 36). By scheduling the retransmission of lost Packet Data Units (PDUs) that need to be retransmitted first, the Radio Network Controller (RNC) initiates the retransmission of new cells. The Radio Network Controller (RNC) then continues Packet Data Unit (PDU) transmission (step 38) from the previous transmission position where step 17 stopped. It should be noted that steps 36 and 38 may be performed simultaneously.

Referring now to FIG. 4, therein is shown a method 50 in accordance with a third preferred embodiment of the present invention. This method 50 is similar to the method 40 shown in fig. 3. However, the method 50 does not resume downlink transmission of the high speed downlink shared channel (HS-DSCH) to the User Equipment (UE) in response to receipt of a Packet Data Unit (PDU) status report (as shown in step 32 of fig. 3). In contrast, the method 50 of the third preferred embodiment of the present invention restarts the downlink transmission of the high speed downlink shared channel (HS-DSCH) after receiving a certain "trigger" (or a certain predetermined event) (step 19). In a first example, this trigger signal may include: transport channel establishment in the Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN) can be accomplished using a new "target" node B transmission procedure by a Radio Network Controller (RNC), as is known in the art. An acknowledgement signal (generated by the node B) received by the Radio Network Controller (RNC) may be used as the trigger signal.

In a second example, the trigger signal may have the receipt and detection of the "sync" indication. When dedicated resources are established in the target node B, the node B may decide to "synchronize" when the assigned physical channels are decided to be available for node B transmission. An indication of this event is communicated to the Radio Network Controller (RNC) and may be used as a trigger.

In a third example, the trigger may have the Radio Resource Controller (RRC) procedure completed (i.e., the Radio Network Controller (RNC) receives an acknowledgement signal with the User Equipment (UE) Radio Resource Controller (RRC) message). In step 16, the Radio Resource Controller (RRC) message generates a Radio Resource Controller (RRC) acknowledgment message, which is generated by the User Equipment (UE) and may be sent to the Radio Network Controller (RNC). When the Radio Network Controller (RNC) receives this information, it can also act as a trigger.

It should be noted that there are many different signaling between the User Equipment (UE) and the Radio Network Controller (RNC), and that any signal may be selected by the user to serve as the trigger signal in the present invention. Accordingly, the three examples described above are intended to be illustrative only and not limiting. Regardless of the trigger, downlink transmission of the high speed downlink shared channel (HS-DSCH) may be resumed (step 21) after the Radio Network Controller (RNC) receives the trigger.

Claims (24)

1. A system for fast recovery of node B buffered data, the system having a Radio Network Controller (RNC) associated with at least one node B, the at least one node B further associated with at least one User Equipment (UE), the at least one UE having at least one record buffer for buffering Packet Data Units (PDUs) transmitted through the RNC, the system comprising:

the Radio Network Controller (RNC) for generating a Media Access Controller (MAC) layer reset notification;

a control unit, located within the User Equipment (UE), for receiving the Medium Access Controller (MAC) layer reset notification and for clearing the at least one recording buffer;

state means internal to the User Equipment (UE) for determining a state of the User Equipment (UE) receiving a Packet Data Unit (PDU) after the logging buffer is cleared, and generating a status report based on the determined state; and

means for transmitting the status report to the Radio Network Controller (RNC).

2. The system of claim 1 wherein the means for determining is responsive to a control signal indicating that the record buffer has cleared all Packet Data Units (PDUs).

3. The system of claim 2 wherein the control signal is an end of Packet Data Unit (PDU) indication generated after clearing all of the PDU's of the recording buffer.

4. The system of claim 2 wherein the last Packet Data Unit (PDU) of the recording buffer has a special indication indicating a status report of the Packet Data Unit (PDU) and the control signal has the special indication.

5. The system of claim 2 wherein the control unit generates the control signal when the record buffer is cleared of all Packet Data Units (PDUs).

6. The system of claim 1 wherein said Radio Network Controller (RNC) interrupts data transmission after generating said Medium Access Controller (MAC) layer reset notification.

7. The system of claim 6 wherein said Radio Network Controller (RNC) reactivates data transmission after receiving said status report.

8. The system of claim 6 wherein said Radio Network Controller (RNC) reactivates data transmission upon receipt of a predetermined trigger.

9. The system of claim 8 wherein the predetermined trigger is receipt of the status report.

10. The system of claim 8 wherein the User Equipment (UE) generates a synchronization indication and the predetermined trigger is receipt of the synchronization indication.

11. In a system having a remote Radio Network Controller (RNC) coupled to at least one node B, the at least one node B further coupled to at least one User Equipment (UE), the at least one User Equipment (UE) having at least one record buffer for buffering Packet Data Units (PDUs) transmitted via the Radio Network Controller (RNC), a method for high speed downlink shared channel (HS-DSCH) cell change, the method comprising:

detecting a need for a high speed downlink shared channel (HS-DSCH) cell change at the Radio Network Controller (RNC);

notifying the User Equipment (UE) to perform a reset;

resetting at the User Equipment (UE), including clearing the at least one logging buffer;

determining, at the User Equipment (UE), a status of receiving a Packet Data Unit (PDU) after the resetting step;

generating a status report based on the determining step; and

the status report is transmitted from the User Equipment (UE) to the Radio Network Controller (RNC).

12. The method of claim 11 wherein the determining step is performed in response to a control signal indicating that the at least one recording buffer has cleared all Packet Data Units (PDUs).

13. The method of claim 12 wherein the control signal is an end of Packet Data Unit (PDU) indication generated when the at least one recording buffer clears all Packet Data Units (PDUs).

14. The method of claim 12 wherein the last Packet Data Unit (PDU) of the at least one recording buffer has a special indication indicating a status report of the PDU and the control signal has the special indication.

15. The method of claim 12, further comprising: the control signal is generated when the recording buffer has cleared all Packet Data Units (PDUs).

16. The method of claim 11, further comprising: after the detecting step, the data transmission is interrupted.

17. The method of claim 16, further comprising: upon receipt of the status report, data transmission is reactivated.

18. The method of claim 16, further comprising: and after receiving a preset trigger signal, reactivating data transmission.

19. The method of claim 18, wherein the predetermined trigger is receipt of the status report.

20. The method of claim 18, further comprising: a synchronization indication is generated at the User Equipment (UE) and the predetermined trigger is the receipt of the synchronization indication.

21. A User Equipment (UE) for expediting a high speed downlink shared channel (HS-DSCH) cell change from a source cell to a target cell, the UE having at least one record buffer for buffering received Packet Data Units (PDUs) of the UE, the UE comprising:

means for detecting a reset indication and clearing the at least one recording buffer in response to the reset indication;

state means for determining a status of data reception of the User Equipment (UE) after clearing the at least one logging buffer;

means for generating a status report based on the determining step; and

means for transmitting the data status report.

22. The User Equipment (UE) of claim 21 wherein the means for determining is responsive to a control signal indicating that the recording buffer has been cleared of all Packet Data Units (PDUs).

23. The User Equipment (UE) of claim 22 wherein the control signal is an end of Packet Data Unit (PDU) indicator generated when all Packet Data Units (PDUs) in the recording buffer are cleared.

24. The User Equipment (UE) of claim 22 wherein the last Packet Data Unit (PDU) of the recording buffer has a special indication indicating a status report of the Packet Data Unit (PDU), and wherein the control signal has the special indication.