HK1157991B - Method and apparatus for performing serving high speed downlink shared channel cell change - Google Patents

Description

Method and apparatus for performing serving high speed downlink shared channel cell change

Technical Field

The present application relates to wireless communications.

Background

High Speed Downlink Packet Access (HSDPA) is a feature that is referenced to release 5 of the third generation partnership project (3GPP) specifications. HSDPA uses three key concepts to achieve maximum spectral efficiency: adaptive Modulation and Coding (AMC), fast physical layer retransmission implementing hybrid automatic repeat request (HARQ), and fast node B scheduling.

Handover is the process by which a wireless transmit/receive unit (WTRU) transitions from one cell to another without the need to service an interruption. In HSDPA, a WTRU monitors a high speed shared control channel (HS-SCCH) in a single cell, referred to as a "serving high speed downlink shared channel (HS-DSCH) cell". When a handover occurs, the WTRU needs to transition to the new serving HS-DSCH cell (the target cell) and stop communicating with the old serving HS-DSCH cell (the source cell). This procedure is called serving HS-DSCH cell change.

There are two types of handovers: synchronous handover and asynchronous handover. In an unsynchronized handover, the network and the WTRU do not activate resources and transitions at the same time. The activation time of the WTRU is set to "now". This may reduce the delay associated with the handover procedure but may increase the chance of losing data.

In synchronous handover, the network and the WTRU perform resource changes simultaneously. The network must set the activation time to a conservative value to account for any type of delay such as scheduling delay, retransmission, configuration time, etc. Even though synchronous handover minimizes data loss, it may still result in higher latency.

Typically, a Radio Resource Control (RRC) handover message is sent to the WTRU via the source cell. Delays associated with serving HS-DSCH cell changes may cause handover message failures, thereby resulting in an unacceptable dropped call rate.

In order to improve the reliability of the serving HS-DSCH cell change procedure, pre-configuration of target cell information or parameters has been proposed. The pre-configuration of the target cell information or parameters adds robustness in the serving HS-DSCH cell change procedure by allowing the network to send a serving HS-DSCH cell change command on the source cell or the target cell. The network configures the use of target cell pre-configuration during the active set update procedure.

The WTRU continuously measures the signal strength of neighboring cells. Based on the measurements on the neighboring cells, the WTRU sends a measurement REPORT (measurement REPORT)1A or 1C message to the active set that contains additional intra-frequency measurement results requesting a new cell. As part of the active set update procedure, the SRNC establishes a new radio link for the dedicated physical channel in the target node B. The SRNC then sends an active set UPDATE (ACTIVE SET UPDATE) message to the WTRU. The active set update message includes information required for establishing a dedicated physical channel in the added radio link. If the SRNC decides to pre-configure the target cell, the active set update message also includes the serving HS-DSCH cell related configuration (e.g., H-RNTI, HS-SCCH configuration, etc.) for the target cell. When the WTRU has added a new radio link, the WTRU returns an ACTIVE set update COMPLETE (ACTIVE setup COMPLETE) message.

When the WTRU detects a change in the best cell, the WTRU sends a measurement report 1D message to request a HS-DSCH serving cell change to the target cell. The report contains the measured values and a cell Identification (ID). The WTRU then begins monitoring one of the HS-SCCH pre-configured in the target cell and the HS-SCCH in the source cell.

Upon receiving the event, the serving rnc (srnc) decides to perform a handover to the new cell. The SRNC requests the controlling rnc (crnc) to allocate HS-DSCH resources (e.g., HS-DSCH radio network temporary identity (H-RNTI), HS-SCCH coding, HARQ resources, etc.) for WTRUs in the target cell via Radio Network Subsystem Application Part (RNSAP) and Node B Application Part (NBAP) messages. Once the HS-DSCH resources are reserved, the CRNC provides all information to the SRNC, which sends an RRC handover message to the WTRU via the source cell.

The SRNC may send a RADIO BEARER SETUP (RADIO BEARER SETUP) message, a RADIO BEARER RECONFIGURATION (RADIO BEARER RECONFIGURATION) message, a TRANSPORT CHANNEL RECONFIGURATION (TRANSPORT CHANNEL RECONFIGURATION) message, or a physical CHANNEL RECONFIGURATION (PHYSICAL CHANNEL RECONFIGURATION) message to the WTRU, the physical CHANNEL RECONFIGURATION message indicating the target HS-DSCH cell and optionally the activation time. The RRC message may also include a configuration of transport channel related parameters for the target HS-DSCH cell including an indication to reset the MAC-HS or MAC-ehs entity.

In parallel, the target node B may send an HS-SCCH order in the target cell to initiate a serving HS-DSCH cell change. The HS-SCCH order may be referred to as an HS-DSCH serving cell change order or a target cell HS-SCCH order. If the WTRU does not receive an RRC message (i.e., a radio bearer setup message, a radio bearer reconfiguration message, a transport channel reconfiguration message, or a physical channel reconfiguration message), the WTRU will perform a serving HS-DSCH cell change upon receiving an HS-SCCH order in the target cell.

When the WTRU has completed the serving HS-DSCH cell change, the WTRU returns a radio bearer setup complete message, a radio bearer reconfiguration complete message, a transport channel reconfiguration complete message, or a physical channel reconfiguration complete message to the network regardless of whether the cell change was triggered by receipt of an RRC message in the source cell or by receipt of an HS-SCCH order in the target cell.

When using enhanced serving cell change, the network will be configured to send an RRC message to the WTRU via the source cell or an HS-SCCH order via the target cell (if configured). However, RRC messages may not be successfully delivered due to degradation of radio conditions in the source cell. In addition, a problem arises when the WTRU receives the RRC message and the target cell HS-SCCH order and they collide with each other. For example, upon receiving the target cell HS-SCCH order, the RRC entity in the WTRU is considered to perform a serving HS-DSCH cell change for a required period of time (i.e., 40 ms). The RRC message may contain a Connection Frame Number (CFN) which is an activation time that occurs much later than the 40ms deadline. In addition, the RRC message may contain new configuration parameters that conflict with the pre-configured HS-DSCH parameters. This may lead to unclear problems in the WTRU. On the network side, this may cause problems because the network may not know which configuration the WTRU is using and when to perform the reconfiguration (i.e., 40ms after the target cell HS-SCCH order or at the activation time given in the RRC message) when the network considers the WTRU to be ready and rerouted data to the target cell. This is because the WTRU may not have received the RRC message yet and may have used the old pre-configured parameters for reconfiguration. Furthermore, in case both messages are received, the WTRU behavior of how and which messages are handled in the RRC entity must be defined.

Disclosure of Invention

A method and apparatus for serving HS-DSC cell change is disclosed. The WTRU receives pre-configured serving cell information or parameters for the target cell from the network. The WTRU reports the measurement report and starts monitoring the HS-SCCH from the target cell. The WTRU may receive an HS-SCCH order on the target cell and/or an RRC reconfiguration message on the source cell indicating a serving HS-DSCH cell change to the target cell. The WTRU may act according to all information elements of the RRC reconfiguration message if the RRC reconfiguration message is received before the target cell HS-SCCH order, and may act according to the preconfigured serving cell parameters if the target cell HS-SCCH order is received before the RRC reconfiguration message. The WTRU may stop monitoring the HS-SCCH on the target cell on the condition that the RRC reconfiguration message is received before receiving the target cell HS-SCCH order. The WTRU may ignore the received RRC reconfiguration message after receiving the target cell HS-SCCH order.

Drawings

A more detailed understanding can be obtained from the following description, given by way of example, in conjunction with the accompanying drawings, in which:

fig. 1 illustrates a wireless communication system;

figure 2 is a functional block diagram of a WTRU and a node-B of the wireless communication system of figure 1;

figure 3 is a flow diagram of an example process for handling an RRC message according to one embodiment, where the WTRU ignores the RRC message after receiving a target cell HS-SCCH order; and

figure 4 is a flow diagram of an example process for processing an RRC message according to one embodiment, where the WTRU ignores the target cell HS-SCCH order after receiving the RRC message.

Detailed Description

The term "WTRU" as referred to below includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a Personal Digital Assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. The term "node B" as referred to hereinafter includes, but is not limited to, a base station, a site controller, an Access Point (AP), or any type of interfacing device capable of operating in a wireless environment.

The term "pre-configured serving cell information" hereinafter refers to serving cell parameters or information elements provided to the WTRU as part of the active set update procedure, including, but not limited to, HS-DSCH parameters (e.g., HS-SCCH coding, HARQ information, H-RNTI, etc.), and optionally enhanced dedicated channel (E-DCH) parameters (e.g., E-DCH absolute grant channel (E-AGCH), E-DCH radio network temporary identity (E-RNTI), and serving cell E-DCH relative grant channel (E-RGCH), E-DCH HARQ indicator channel (E-HICH), etc.). The pre-configured serving cell information will allow the WTRU to perform a fast serving cell change to the target cell upon receiving the HS-SCCH order for the handover through the target cell. The terms "parameter" and "information" or "information element" may be used interchangeably. The terms "HS-SCCH order", "HS-DSCH serving cell change order", and "target cell HS-SCCH order" may be used interchangeably hereinafter.

Fig. 1 shows a wireless communication system 100, the wireless communication system 100 including a plurality of WTRUs 110, a node B120, a Controlling Radio Network Controller (CRNC)130, a Serving Radio Network Controller (SRNC)140, and a core network 150. Together, the node B120 and the CRNC 130 may be referred to as a Universal Terrestrial Radio Access Network (UTRAN).

As shown in fig. 1, the WTRU110 communicates with the node B120, and the node B120 communicates with the CRNC 130 and the SRNC 140. Although three WTRUs 110, one node B, one CRNC 130, and one SRNC 140 are shown in fig. 1, it should be noted that any combination of wired and wireless devices may be included in the wireless communication system 100.

Figure 2 is a functional block diagram of a WTRU110 and a node-B120 of the wireless communication system 100 of figure 1. As shown in fig. 2, the WTRU110 communicates with the node-B120 and both are configured to perform the method for performing a serving HS-DSCH cell change.

In addition to the components that may be found in a typical WTRU, the WTRU110 includes a processor 115, a receiver 116, a transmitter 117, a memory 118, and an antenna 119. Memory 118 is provided for storing software including operating systems, applications, and the like. The processor 115 is provided for performing a method of serving HS-DSCH cell change according to the embodiments disclosed below, alone or in combination with software. The receiver 116 and the transmitter 117 are in communication with the processor 115. An antenna 119 is in communication with the receiver 116 and the transmitter 117 to facilitate the transmission and reception of wireless data.

In addition to the components that may be found in a typical base station, node B120 includes a processor 125, a receiver 126, a transmitter 127, a memory 128, and an antenna 129. The processor 125 is configured to support a method of serving HS-DSCH cell change according to embodiments disclosed below. The receiver 126 and the transmitter 127 are in communication with the processor 125. An antenna 129 is in communication with the receiver 126 and the transmitter 127 to facilitate the transmission and reception of wireless data.

As part of the serving HS-DSCH cell change procedure, the network sends an RRC message to the WTRU through the source cell, commanding the best cell change and providing the configuration parameters (i.e., information elements) required by the WTRU. The RRC message may be, but is not limited to, a radio bearer reconfiguration message, a radio bearer setup or release message, a transport channel reconfiguration message, or a physical channel reconfiguration message. Hereinafter, these RRC messages are referred to as "RRC reconfiguration messages".

The RRC reconfiguration message may include a set of serving cell information (e.g., HS-DSCH and E-DCH parameters) and optionally an activation time for the serving HS-DSCH cell change that is not "now". The serving cell information included in the RRC reconfiguration message may be the same as the preconfigured serving cell information or may include new information different from the preconfigured serving cell information. The new serving cell information may include radio bearer information elements, transport channel parameters, or physical channel parameters.

The WTRU behavior during a serving HS-DSCH cell change is disclosed below.

In the case where the WTRU receives an RRC reconfiguration message via the source cell before receiving an HS-SCCH order via the target cell, the WTRU may perform reconfiguration according to information contained in the RRC reconfiguration message and may ignore the subsequently received HS-SCCH order of the target cell. If the activation time is specified in the RRC reconfiguration message, the WTRU may stop monitoring the HS-SCCH in the target cell until the activation time expires and the WTRU reconfigures to a new cell.

Alternatively, even if the WTRU receives an RRC reconfiguration message with an activation time (not "now"), once the WTRU receives the HS-SCCH order, the WTRU may initiate a reconfiguration to the target cell even if the activation time has not been reached. If new parameters are included in the RRC reconfiguration message, the WTRU may apply these parameters before the activation time if the HS-SCCH order is received.

In the case where the WTRU receives the HS-SCCH order through the target cell before receiving the RRC reconfiguration message through the source cell, the WTRU may act upon the target cell HS-SCCH order and initiate a reconfiguration procedure to the target cell. Upon receiving the RRC reconfiguration message, the WTRU decodes the RRC reconfiguration message, and if the serving cell information included in the RRC reconfiguration message is different from the preconfigured serving cell information, the WTRU may stop the reconfiguration procedure and apply the serving cell information provided in the RRC reconfiguration message. If the activation time is provided in the RRC reconfiguration message, the WTRU may ignore the activation time and perform reconfiguration. Alternatively, the WTRU may stop the ongoing reconfiguration, return to the source cell and wait for the activation time to expire.

Alternatively, the WTRU may act on the target cell HS-SCCH order only and ignore the subsequent RRC reconfiguration message. The WTRU may reconfigure according to the preconfigured serving cell information and may ignore new parameters or information provided in the RRC reconfiguration message.

Alternatively, the WTRU may act on the target cell HS-SCCH order, reconfigure on the preconfigured serving cell information (even if the RRC reconfiguration message contains conflicting parameters or information), and act on any new parameters or information in the RRC reconfiguration message that is not part of the preconfigured serving cell information for the target cell.

In the case where the WTRU does not receive an RRC reconfiguration message due to degradation of channel conditions in the source cell, the WTRU acts in accordance with the target cell HS-SCCH order and performs reconfiguration upon receiving the target cell HS-SCCH order. Once the reconfiguration is completed, the WTRU prepares and sends an RRC complete message. The WTRU may indicate to the network that only the target cell HS-SCCH order was received. Upon receiving the RRC complete message and the indication together, the network may retransmit the RRC reconfiguration message to ensure that the WTRU performs the appropriate reconfiguration if additional configuration parameters are sent in the RRC reconfiguration message. Optionally, the WTRU may also indicate when the handover occurs. This may help the network determine the last packets sent and received from the source cell and retransmit these packets.

Message priorities may be defined so that the WTRU may process the RRC reconfiguration message and the target cell HS-SCCH order according to the priorities.

According to one embodiment, the WTRU may be configured to process the RRC reconfiguration message and the target cell HS-SCCH order according to the order of reception. More specifically, if one of the RRC reconfiguration message and the target cell HS-SCCH order has initiated the serving HS-DSCH cell change procedure, the WTRU may ignore the later received message (i.e., the target cell HS-SCCH order or the RRC reconfiguration message) and continue execution of the current procedure. For example, if the WTRU first receives the target cell HS-SCCH order, the WTRU may ignore and reject the RRC reconfiguration message received later, or vice versa.

Alternatively, the RRC reconfiguration message may replace the pre-configured serving cell configuration. More specifically, the WTRU may be configured to always give priority to RRC reconfiguration messages even though the target cell HS-SCCH order may have initiated the serving HS-DSCH cell change procedure. If the WTRU has an ongoing serving HS-DSCH cell change procedure initiated by HS-SCCH order reception by the target cell at the time the RRC reconfiguration message is received, the ongoing serving HS-DSCH cell change procedure may be stopped and actions related to the RRC reconfiguration message may be performed. If the RRC reconfiguration message is received first, the WTRU may ignore the target cell HS-SCCH order received later and act upon the RRC reconfiguration message only.

The transaction identifier mechanism may be used to ensure that the network is made aware of what messages the WTRU processes. The transaction identifier mechanism is used to ensure that the WTRU RRC entity ignores the reception of the RRC reconfiguration message on the condition that the target cell HS-SCCH order has been received, or vice versa.

In general, an Information Element (IE) "transaction identifier" in the RRC message may be used with the IE "message type" of the RRC message to identify invocation of downlink procedures. The WTRU obtains the RRC transaction identifier through a first downlink RRC message (e.g., radio bearer reconfiguration). The WTRU may accept or reject the transaction based on the IEs "message type" and "RRC transaction identifier" in the received RRC message. The IE "RRC transaction identifier" is added to RRC messages and later RRC messages are rejected if they have the same RRC transaction identifier. In the case of a reconfiguration message, if the RRC messages are of the same type, the RRC message, even with a different RRC transaction identifier, is rejected. Once the RRC procedure is complete, the WTRU sends the RRC transaction identifier of the initial message in an RRC complete message.

Currently, the IEs "message type" and "RRC transaction identifier" in the variables transport are stored only when a downlink RRC message is received. According to one embodiment, the WTRU stores the IE "message type" and the "RRC transaction identifier" in the variables TRANSACTIONS upon receiving the HS-SCCH order by the target cell. The "message type" is set to one of the following: (1) a new message type, e.g., "HS-SCCH order", (2) an existing RRC reconfiguration message type, e.g., "physical channel reconfiguration" or "transport channel reconfiguration", or (3) active set update. Since the conventional HS-SCCH order cannot contain the value "RRC transaction identifier", the WTRU RRC entity must implicitly set the "RRC transaction identity" as part of the target cell HS-SCCH order reception procedure. For example, the "RRC transaction identifier" may be set to any value (e.g., 0) or other value that the network does not use and is reserved for the target cell HS-SCCH order.

If the WTRU receives the target cell HS-SCCH order before receiving the RRC reconfiguration message, and the WTRU detects that a transaction indicated by the "RRC transaction identifier" and the "message type" of the received RRC reconfiguration message is occurring due to a previous reception of the target cell HS-SCCH order, the WTRU ignores the RRC reconfiguration message and continues the ongoing reconfiguration process. Otherwise, the WTRU accepts the transaction.

If an RRC RECONFIGURATION message is received before the target cell HS-SCCH order is received and the WTRU detects that the transaction requested by the target cell HS-SCCH order is occurring (i.e., ORDERED _ RECONFIGURATION is set to true), and optionally the "message type" in the variable transport is set to one of the RRC RECONFIGURATIONs, the WTRU ignores the transaction requested by the target cell HS-SCCH order and continues the ongoing process as if no target cell HS-SCCH order was received. Otherwise, the transaction requested by the target cell HS-SCCH order is accepted, and the WTRU sets the "message type" and "RRC transaction identifier" in the variable TRANSACTIONS to be applicable to the target cell HS-SCCH order. Optionally, the WTRU sets the variable ORDERED _ RECONFIGURATION to true after receiving and accepting the transaction requested by the target cell HS-SCCH order.

Once the reconfiguration process is complete, the WRTU prepares an RRC complete message. If the transaction corresponds to the target cell HS-SCCH order, the WTRU adds its RRC transaction identifier for the HS-SCCH order only or an alternative additional IE to the RRC complete message. Alternatively, a new RRC message (e.g., HS-SCCH Serving Cell Change (SCC) complete message) may be defined and used when a serving HS-DSCH cell change occurs due to the target cell HS-SCCH order.

An example procedure for accepting or ignoring a transaction for handling a serving HS-DSCH cell change is disclosed below.

Figure 3 is a flow diagram of an example process for handling an RRC message according to one embodiment, where the WTRU ignores the RRC message after receiving a target cell HS-SCCH order. The WTRU receives an RRC message from the network (step 302). If the IE "RRC transaction identifier" is included in the received RRC message, the WTRU determines whether the received RRC message is one of a radio bearer setup message, a radio bearer reconfiguration message, a radio bearer release message, a transport channel reconfiguration message, or a physical channel reconfiguration message (step 304). If so, in step 306, the WTRU determines whether the following conditions are met:

(1) the variable ORDERED _ RECONFIGURATION is set to FALSE;

(2) the variable CELL _ UPDATE _ STARTED is set to FALSE;

(3) the received message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE;

(4) the table of "accepted TRANSACTIONS" in the variable transport does not contain an entry with the IE "message type" set to active set update;

(5) the table of "accepted transaction" in the variable transport does not contain an entry with "message type" set to HS-SCCH order (if a new message type "HS-SCCH order" is defined); and

(6) the table of "accepted TRANSACTIONS" in the variable transport does not contain an entry with the "RRC transaction identifier" set to the reserved transaction ID for the HS-SCCH order (if a new RRC transaction identifier is defined to distinguish from the HS-SCCH order transaction).

If all conditions (1) - (6) are met, the WTRU accepts the transaction and stores the IE "message type" and "RRC transaction identifier" in the received RRC message in a table of "accepted TRANSACTIONS" in the variable TRANSACTIONS (step 308). If any of conditions (1) - (6) are not met, the WTRU may, for example, ignore the transaction and continue with the ongoing process and procedure as if no RRC message was received (step 310).

Figure 4 is a flow diagram of an example process for processing an RRC message according to one embodiment, where the WTRU ignores the target cell HS-SCCH order after receiving the RRC message. The WTRU receives the HS-SCCH through the target cell (step 402). The WTRU looks at the variable "transport" to see if there is an ongoing reconfiguration. Upon receiving the target cell HS-SCCH order, the WTRU determines whether all of the following conditions (1) - (6) are met in step 404:

(1) the variable ORDERED _ RECONFIGURATION is set to FALSE;

(2) the variable CELL _ UPDATE _ STARTED is set to FALSE;

(3) the received message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE;

(4) the table of "accepted TRANSACTIONS" in the variable transport does not contain an entry with the IE "message type" set to active set update;

(5) the table of "accepted transaction" in the variable transport does not contain an entry with "message type" set to HS-SCCH order (if a new message type "HS-SCCH order" is defined); and

(6) the table of "accepted TRANSACTIONS" in the variable transport does not contain an entry with the "RRC transaction identifier" set to the reserved transaction ID for the target cell HS-SCCH order (if a new RRC transaction identifier is defined to distinguish HS-SCCH order TRANSACTIONS).

If all conditions (1) - (6) are met, the WTRU accepts the transaction and stores the IE "message type" and "transaction identifier" for the HS-SCCH order in a variable TRANSACTIONS (step 406). If any of conditions (1) - (6) are not met, the WTRU ignores the transaction and continues with ongoing procedures and procedures as if no target cell HS-SCCH order was received (step 408).

If no activation time is provided in the RRC reconfiguration message, the network will assume that the reconfiguration to the target cell will be ready within, for example, 40ms of the target cell HS-SCCH order transmission or transmissions. The network may start transmission through the target cell at this point, but if the RRC reconfiguration message already provides a new set of HS-DSCH parameters, the network does not know at this time whether the WTRU is acting upon the RRC message or upon the target cell HS-SCCH order. This may result in the network using a wrong configuration and the WTRU may not receive the desired data.

To solve this problem, a restriction may be imposed whereby a collision between the preconfigured serving cell information and the serving cell information provided in the RRC reconfiguration message is not allowed. If the WTRU detects conflicting information, an invalid configuration occurs. This requires the network RRC entity to send the same serving cell configuration provided in the active set update pre-configuration. The network sends an RRC reconfiguration message but the fields of the preconfigured IEs contained in the active set update procedure may be left empty. The RRC reconfiguration message may be a simplified message that confirms to the WTRU that the handover has been approved by the network. The RRC reconfiguration message may contain these parameters if additional IEs are needed (e.g., other reconfigurations of radio bearers or transport channels that are not part of the preconfigured resources). The RRC reconfiguration message may contain all required IEs to allow the WTRU to perform handover to the target cell if the network has decided to perform handover to the target cell.

Alternatively, no such restriction may be imposed, and the network may determine which configuration the WTRU is using by waiting for an RRC complete message indicating whether the WTRU acts according to an RRC message or an HS-SCCH order. This can delay path switching times and increase service interruption delays. Alternatively, the network attempts both configurations and detects which configuration the WTRU is using by sending data in both configurations and detecting which configuration the WTRU correctly receives the data in, thereby determining which configuration the WTRU is using.

The RRC procedure may be denied use of the transaction identifier mechanism if a conflicting reconfiguration occurs and the WTRU is not allowed to have a conflicting reconfiguration. More specifically, if there is a conflicting configuration, the WTRU sets the "RRC transaction identifier" in the table of "reject transaction" in the variable transport. The WTRU then sends an RRC failure message to the network.

The network has the option to perform a synchronous handover for the serving HS-DSCH cell and provides the activation time in the RRC reconfiguration message. In this case, the WTRU does not perform the serving HS-DSCH cell change prior to the activation time. However, if the WTRU RRC entity first receives the HS-SCCH order, it is unclear which activation the WTRU should use. In addition, the network may not know whether the WTRU received the RRC reconfiguration message and whether the WTRU performed the handover at the specified activation time or 40ms after the HS-SCCH order. The foregoing process may result in additional delay and potential data loss if the network reconfiguration is too early.

According to one embodiment, the synchronous handover may not be allowed for the serving HS-DSCH cell change. More specifically, if the target cell configuration is preloaded, the WTRU does not expect an activation time other than "now" after the triggering event 1D. If an activation time other than "now" is provided in the RRC reconfiguration message, the WTRU behavior is a result of unspecified or invalid configuration. Alternatively, if the activation time is different than "now," the WTRU may ignore the activation time and perform a handover after receiving the target cell HS-SCCH order. The network may only perform non-synchronized handovers.

Alternatively, the network is allowed to send the activation time, but the network configures the target node B to send the target cell HS-SCCH order X ms before the given activation time or expiration of the activation time, where X is determined based on the time required for reconfiguration (i.e. 40ms) and the number of repetitions of the optional target cell HS-SCCH order.

The RRC reconfiguration message may include a set of radio bearer parameters that are not given at all as part of the pre-configured serving cell parameters. This can occur, for example, when a SRNC relocation occurs. In this case, the WTRU must apply these new parameters as soon as possible or at a given activation time (if any). If the WTRU does not receive the RRC reconfiguration message, or the RRC reconfiguration message is ignored due to the transaction identifier mechanism, the network does not know whether the WTRU is configured with these parameters. Instead of waiting for the RRC complete message to determine whether reconfiguration with new parameters has occurred, the network may retransmit the RRC reconfiguration message through the target cell if it contains additional serving cell parameters as long as the network determines that reconfiguration is complete. This may be the same message sent over the source cell using the same RRC transaction identifier. If the WTRU has received the message and performed reconfiguration, the WTRU should ignore the message and not perform actions in accordance with the message.

Examples

1. A method implemented in a WTRU for serving HS-DSCH cell change.

2. The method of embodiment 1, comprising receiving preconfigured serving cell information for a target cell.

3. The method of embodiment 2, comprising reporting a measurement report.

4. A method as in any of embodiments 2-3 comprising monitoring the HS-SCCH on the target cell.

5. A method as in any of embodiments 2-4 comprising receiving one of an HS-SCCH order on the target cell and an RRC reconfiguration message on a source cell indicating a serving HS-DSCH cell change to the target cell.

6. The method of embodiment 5 comprising performing an action according to all received information elements of the RRC reconfiguration message if the RRC reconfiguration message is received before the HS-SCCH order, and performing an action according to the preconfigured serving cell information if the HS-SCCH order is received before the RRC reconfiguration message.

7. The method as in any of embodiments 4-6 wherein the WTRU stops monitoring the HS-SCCH on the target cell on a condition that the RRC reconfiguration message is received before the HS-SCCH order is received.

8. The method as in any one of embodiments 5-7 wherein the WTRU ignores RRC reconfiguration messages received after receiving the HS-SCCH order.

9. The method as in any one of embodiments 5-8 wherein the RRC reconfiguration message is one of a radio bearer setup message, a radio bearer release message, a radio bearer reconfiguration message, a transport channel reconfiguration message, and a physical channel reconfiguration message.

10. The method as in any one of embodiments 5-9, further comprising: accepting a transaction of the HS-SCCH request upon receipt of the HS-SCCH order on the target cell, and storing an IE "message type" and an "RRC transaction identifier" for reservation of the HS-SCCH order in a table of "accepted transactions" if the following conditions are satisfied: the variable ORDERED _ RECONFIGURATION is set to FALSE; the variable CELL _ UPDATE _ STARTED is set to FALSE; the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE; the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update; the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and the table of "accepted transactions" does not contain an entry of "RRC transaction identifier" with the transaction identifier set to be reserved for HS-SCCH orders.

11. The method as in any one of embodiments 5-9, further comprising: accepting the transaction requested by the RRC reconfiguration message and storing the IE "message type" and the "RRC transaction identifier" of the RRC reconfiguration message in a table of "accepted transactions" if the following conditions are met: (1) the variable ORDERED _ RECONFIGURATION is set to FALSE; (2) the variable CELL _ UPDATE _ STARTED is set to FALSE; (3) the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE; (4) the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update; (5) the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and (6) the table of "accepted transactions" does not contain an entry for "RRC transaction identifier" with the transaction identifier set to be reserved for the HS-SCCH order.

12. The method as in any of embodiments 6-11 wherein the WTRU performs an action based on serving cell parameters received in an RRC reconfiguration message that does not conflict with the preconfigured serving cell information.

13. The method as in any one of embodiments 6-12 wherein the WTRU ignores an activation time included in the RRC reconfiguration message on a condition that the HS-SCCH order is received before the RRC reconfiguration message.

14. The method as in any one of embodiments 6-13, further comprising: sending an RRC complete message and an indication that the WTRU received only the HS-SCCH order on a condition that the WTRU did not receive the RRC reconfiguration message.

15. The method as in any one of embodiments 6-14, further comprising: setting a variable ORDERED _ RECONFIGURATION to TRUE upon receiving the HS-SCCH order.

16. A WTRU configured to perform an HS-DSCH cell change.

17. The WTRU of embodiment 16, comprising: a transmitter configured to transmit wireless data.

18. A WTRU as in any one of embodiments 16-17 comprising a receiver configured to receive wireless data.

19. A WTRU as in any one of embodiments 16-18 comprising a processor in communication with the transmitter and the receiver, the processor configured to receive pre-configured serving cell information for a target cell; reporting a measurement report; monitoring the HS-SCCH on the target cell; receiving one of an HS-SCCH order on the target cell and an RRC reconfiguration message on a source cell indicating a serving HS-DSCH cell change to the target cell; and performing an action according to all information elements of the RRC reconfiguration message if the RRC reconfiguration message is received before the HS-SCCH order, and performing an action according to the preconfigured serving cell information if the HS-SCCH order is received before the RRC reconfiguration message.

20. The WTRU of embodiment 19 wherein the processor stops monitoring the HS-SCCH on the target cell on a condition that the RRC reconfiguration message is received before the HS-SCCH order is received.

21. The WTRU as in any one of embodiments 19-20 wherein the processor ignores RRC reconfiguration messages received after receiving the HS-SCCH order.

22. The WTRU as in any one of embodiments 19-21 wherein the RRC reconfiguration message is one of a radio bearer setup message, a radio bearer release message, a radio bearer reconfiguration message, a transport channel reconfiguration message, and a physical channel reconfiguration message.

23. The WTRU as in any one of embodiments 19-22 wherein the processor accepts a transaction of the HS-SCCH request after receiving the HS-SCCH order on the target cell and stores an IE "message type" and an "RRC transaction identifier" for reservation of the HS-SCCH order in a table of "accepted transactions" if the following conditions are met: the variable ORDERED _ RECONFIGURATION is set to FALSE; the variable CELL _ UPDATE _ STARTED is set to FALSE; the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE; the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update; the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and the table of "accepted transactions" does not contain an entry of "RRC transaction identifier" with the transaction identifier set to be reserved for HS-SCCH orders.

24. The WTRU as in any one of embodiments 19-22 wherein the processor accepts the requested transaction of the RRC reconfiguration message and stores an IE "message type" and an "RRC transaction identifier" of the RRC reconfiguration message in a table of "accepted transactions" if the following conditions are met: (1) the variable ORDERED _ RECONFIGURATION is set to FALSE; (2) the variable CELL _ UPDATE _ STARTED is set to FALSE; (3) the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE; (4) the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update; (5) the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and (6) the table of "accepted transactions" does not contain an entry for "RRC transaction identifier" with the transaction identifier set to be reserved for the HS-SCCH order.

25. The WTRU as in any one of embodiments 19-24 wherein the processor performs an action based on serving cell parameters received in an RRC reconfiguration message that does not conflict with the preconfigured serving cell information.

26. The WTRU as in any one of embodiments 19-25 wherein the processor ignores an activation time included in the RRC reconfiguration message on a condition that the HS-SCCH order is received before the RRC reconfiguration message.

27. The WTRU as in any of embodiments 19-26 wherein the processor sends an RRC complete message and an indication that the WTRU has received only the HS-SCCH order on a condition that the WTRU has not received the RRC reconfiguration message.

28. The WTRU as in any one of embodiments 19-27 wherein the processor sets a variable order _ RECONFIGURATION to true after the HS-SCCH order is received.

Although the features and elements of the present invention are described in the particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of the computer-readable storage medium include Read Only Memory (ROM), Random Access Memory (RAM), registers, buffer memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and Digital Versatile Disks (DVDs).

For example, suitable processors include: a general-purpose processor, a special-purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any Integrated Circuit (IC), and/or a state machine.

A processor in association with software may be used to implement a radio frequency transceiver for use in a Wireless Transmit Receive Unit (WTRU), User Equipment (UE), terminal, base station, Radio Network Controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a video phone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, and BluetoothA module, a Frequency Modulation (FM) radio unit, a Liquid Crystal Display (LCD) display unit, an Organic Light Emitting Diode (OLED) display unit, a digital music player, a media player, a video game player module, an internet browser, and/or any Wireless Local Area Network (WLAN) or Ultra Wideband (UWB) module.

Claims (20)

1. A method implemented in a wireless transmit/receive unit, WTRU, for serving high speed downlink shared channel, HS-DSCH, cell change, the method comprising:

receiving pre-configured serving cell information for a target cell;

reporting a measurement report;

monitoring a high-speed shared control channel HS-SCCH on the target cell;

receiving one of an HS-SCCH order on the target cell and a Radio Resource Control (RRC) reconfiguration message on a source cell indicating a serving HS-DSCH cell change to the target cell; and

performing an action according to all received information elements of the RRC reconfiguration message if the RRC reconfiguration message is received before the HS-SCCH order, and performing an action according to the preconfigured serving cell information if the HS-SCCH order is received before the RRC reconfiguration message.

2. The method of claim 1 wherein the WTRU stops monitoring the HS-SCCH on the target cell on a condition that the RRC reconfiguration message is received before the HS-SCCH order is received.

3. The method of claim 1 wherein the WTRU ignores RRC reconfiguration messages received after receiving the HS-SCCH order.

4. The method of claim 1, wherein the RRC reconfiguration message is one of a radio bearer setup message, a radio bearer release message, a radio bearer reconfiguration message, a transport channel reconfiguration message, and a physical channel reconfiguration message.

5. The method of claim 1, further comprising:

accepting a transaction requested by the HS-SCCH order upon receipt of the HS-SCCH order on the target cell, and storing information elements IE 'message type' and 'RRC transaction identifier' for reservation of HS-SCCH order in a table of 'accepted transactions' if:

the variable ORDERED _ RECONFIGURATION is set to FALSE;

the variable CELL _ UPDATE _ STARTED is set to FALSE;

the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE;

the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update;

the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and

the table of "accepted transactions" does not contain an entry with the "RRC transaction identifier" set as the transaction identifier for the reservation of the HS-SCCH order.

6. The method of claim 1, further comprising:

accepting the transaction requested by the RRC reconfiguration message and storing the IE "message type" and the "RRC transaction identifier" of the RRC reconfiguration message in a table of "accepted transactions" if the following conditions are met:

the variable ORDERED _ RECONFIGURATION is set to FALSE;

the variable CELL _ UPDATE _ STARTED is set to FALSE;

the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE;

the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update;

the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and

the table of "accepted transactions" does not contain an entry with the "RRC transaction identifier" set as the transaction identifier for the reservation of the HS-SCCH order.

7. The method of claim 1 wherein the WTRU performs an action according to serving cell parameters received in an RRC reconfiguration message that does not conflict with the preconfigured serving cell information.

8. The method of claim 1 wherein the WTRU ignores an activation time contained in the RRC reconfiguration message on a condition that the HS-SCCH order is received before the RRC reconfiguration message.

9. The method of claim 1, further comprising:

sending an RRC complete message and an indication that the WTRU received only the HS-SCCH order on a condition that the WTRU did not receive the RRC reconfiguration message.

10. The method of claim 1, further comprising:

setting a variable ORDERED _ RECONFIGURATION to TRUE upon receiving the HS-SCCH order.

11. An apparatus implemented in a wireless transmit/receive unit (WTRU) for serving high speed downlink shared channel (HS-DSCH) cell change, the apparatus comprising:

means for receiving preconfigured serving cell information for a target cell;

means for reporting a measurement report;

means for monitoring a high speed shared control channel, HS-SCCH, on the target cell;

means for receiving one of an HS-SCCH order on the target cell and a Radio Resource Control (RRC) reconfiguration message on a source cell indicating a serving HS-DSCH cell change to the target cell; and

means for performing an action according to all information elements of the RRC reconfiguration message if the RRC reconfiguration message is received before the HS-SCCH order, and means for performing an action according to the preconfigured serving cell information if the HS-SCCH order is received before the RRC reconfiguration message.

12. The apparatus of claim 11, wherein the apparatus comprises means for stopping monitoring the HS-SCCH on the target cell if the RRC reconfiguration message is received before the HS-SCCH order is received.

13. The apparatus of claim 11, wherein the apparatus comprises means for ignoring RRC reconfiguration messages received after receiving the HS-SCCH order.

14. The apparatus of claim 11, wherein the RRC reconfiguration message is one of a radio bearer setup message, a radio bearer release message, a radio bearer reconfiguration message, a transport channel reconfiguration message, and a physical channel reconfiguration message.

15. The apparatus of claim 11, wherein the apparatus comprises means for accepting a transaction requested by the HS-SCCH order after receiving the HS-SCCH order on the target cell, and means for storing an information element IE "message type" and an "RRC transaction identifier" for reservation of the HS-SCCH order in a table of "accepted transactions" if the following conditions are met:

the variable ORDERED _ RECONFIGURATION is set to FALSE;

the variable CELL _ UPDATE _ STARTED is set to FALSE;

the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE;

the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update;

the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and

the table of "accepted transactions" does not contain an entry with the "RRC transaction identifier" set as the transaction identifier for the reservation of the HS-SCCH order.

16. An apparatus according to claim 11, wherein the apparatus comprises means for accepting a transaction requested by the RRC reconfiguration message, and means for storing IEs "message type" and "RRC transaction identifier" of the RRC reconfiguration message in a table of "accepted transactions" if the following conditions are met:

the variable ORDERED _ RECONFIGURATION is set to FALSE;

the variable CELL _ UPDATE _ STARTED is set to FALSE;

the RRC reconfiguration message does not contain a PROTOCOL ERROR and the variable PROTOCOL _ ERROR _ REJECT is set to FALSE;

the table of "accepted transactions" does not contain an entry with the IE "message type" set to active set update;

the table of "accepted transactions" does not contain an entry with the IE "message type" set as the message type for the reservation of the HS-SCCH order; and

the table of "accepted transactions" does not contain an entry with the "RRC transaction identifier" set as the transaction identifier for the reservation of the HS-SCCH order.

17. The apparatus of claim 11, wherein the apparatus comprises means for performing an action according to serving cell parameters received in an RRC reconfiguration message that does not conflict with the preconfigured serving cell information.

18. The apparatus of claim 11, wherein the apparatus comprises means for ignoring an activation time contained in the RRC reconfiguration message if the HS-SCCH order is received before the RRC reconfiguration message.

19. The apparatus of claim 11, wherein the apparatus further comprises means for sending an RRC complete message and an indication that the apparatus received only the HS-SCCH order if the apparatus did not receive the RRC reconfiguration message.

20. The apparatus of claim 11, wherein the apparatus comprises means for setting a variable order _ RECONFIGURATION to true upon receipt of the HS-SCCH order.