TWI475910B - Triggering a method from cell time alignment process - Google Patents

Description

Method of triggering a time alignment process from a cell

The present invention is based on carrier aggregation technology for wireless communication, and more particularly to a method of triggering a time alignment process from a cell.

A user terminal can perform correct uplink feedback only after its uplink transmission time is synchronized. Therefore, in order to receive downlink data from the base station, the user terminal must establish uplink synchronization. Conversely, if a user terminal wishes to transmit uplink data to the base station, it should also establish uplink synchronization with the base station.

In the case of a non-same site, for example, to support a remote radio head (RRH) or a frequency-selected relay scenario, the RAN 51 has agreed to support multiple time alignments of carrier aggregation (CA, Carrier Aggregation). / Time alignment/Time Advancement. That is, the supporting base station and the user terminal perform signaling and data transmission according to different uplink times on multiple carrier components. Hereinafter, the carrier component that the user terminal successfully accesses for the first time is called a primary cell (Primary Cell, Pcell). The other spare carrier component is called a secondary cell (Scell). Of course, the user terminal can also change the selection of the primary cell and the secondary cell according to the trigger of the base station.

RAN2 73bis has determined to study the Scell-based Physical Random Access Channel (PRACH) scheme to solve the time alignment of Scell. For time alignment, for example, up time alignment That is, the time calibration of the uplink transmission is performed, and the timing advance is used on the UE side to cancel the transmission delay and the like.

For Scell-based PRACH, the primary problem to solve is how to trigger the time alignment problem of Scell.

For R11 (version 11), multiple time advances will be supported. Some slave cells need to be in an up time aligned state before any up/down operations. According to the current state, there are two schemes for triggering the Scell uplink time alignment process: Option 1: After receiving the RRC (Resource Radio Control) configuration message for the Scell setting purpose, the UE automatically triggers the PRACH process; Solution 2: The PRACH process is triggered by, for example, a Physical Downlink Control Channel (PDCCH order information) from an eNB. The PDCCH order signaling includes a dedicated preamble sequence, that is, a random access preamble, for indicating that the user terminal performs a non-contention random access procedure.

An advantage of the first scheme is that no additional PDCCH order signaling is required, but the current RRC configuration message must be enhanced, such as adding a time alignment requirement indication, a dedicated preamble indication, thus resulting in additional RRC message overhead.

The advantage of the second scheme is that it has no effect on the current RRC configuration message, but requires additional PDCCH order signaling, which is not a big problem. In this way, there are two implementation methods: Mode 1: Sending a PDCCH order transmission before the Scell starts, that is, Sending a PDCCH order transmission before the base station sends a start MAC CE (Media Access Control Control Element); Method 2: Sending a PDCCH order transmission after the Scell is started, that is, sending a MAC CE transmission The PDCCH order transmission is sent after the message.

The main disadvantages of the mode 1 are that the UE needs to try to receive the PDCCH order transmission from the newly configured Scell, which is not allowed in the current standard specifications. And cause extra power consumption. The reason is that after the Scell is configured, the UE needs to start detecting the PDCCH order signaling from the Scell or the PDCCH order signaling for the Scell until the PDCCH order transmission is received. In this way, the RF front end of the Scell has to be in the startup state until the eNB triggers the PDCCH order signaling. If the eNB does not intend to use this configured Scell in the short term, this will consume the power of the UE. (This may not be a disadvantage in the case where cross-carrier scheduling of PDCCH order signaling is allowed, but the current specification does not allow this, in the current specification the UE will discard any PDCCH signaling directed to the non-starting Scell); Disadvantage 2: Some Scells may be in an uplink out-of-synchronization state for a period of time (ie, in a transient state in which the Scell is configured but not activated and uplinks out of sync). If there are multiple timing advance timers Then, this situation may be more common; disadvantage 3: additional PDCCH signaling is required after the RRC reconfiguration procedure.

For mode 2, after receiving the MAC CE to initiate the transmission, the UE needs to wait for the PDCCH order to send a message, and then, after receiving the PDCCH order signaling, perform time alignment accordingly. There are also some concerns about this approach:

Concern 1: The user equipment cannot comply with the operation defined by R10 for Scell startup. In the existing operation of R10, the UE must start uplink transmission after 8ms (that is, waiting for 8 subframes). The reason is that after receiving the start MAC CE, the UE has to wait for an additional PDCCH order to transmit to trigger the PRACH, after which the UE can start normal uplink transmission.

Concern 2: The received PDCCH order transmission after receiving the start MAC CE signaling is completely redundant downlink signaling. The reason is that according to the MAC CE signaling, the UE already knows that the eNB wants to schedule the Scell, and does not need to further notify by PDCCH order signaling.

According to a first aspect of the present invention, there is provided a method of communicating in a user terminal of a wireless communication network, wherein the user terminal is configured with a primary cell and at least one secondary cell, wherein the at least one from the cell A method in which the slave cell is in a configured state and is not uplink synchronized, the method includes: not performing downlink channel measurement.

In an embodiment, the method further includes the steps of: receiving a media access control layer from the base station to send a message, wherein the media access control layer Controlling the signaling to instruct the user terminal to activate the first slave cell; performing an entity random access procedure on the first slave cell to implement uplink time synchronization on the first slave cell; modifying the first slave cell to boot status.

In another embodiment, the method further includes: determining whether a physical downlink control channel order signaling for the first slave cell is detected; and when detecting the physical downlink control channel order for the first slave cell The entity random access process is performed to implement uplink synchronization.

In still another embodiment, it is determined whether a media access control layer from the base station controls the signaling or receives a physical downlink control channel ordering from the base station for the first slave cell. When receiving the media access control layer control signaling to initiate to the first slave cell, performing an entity random access procedure on the first slave cell to implement uplink time synchronization on the first slave cell; The first from the cell is modified to the startup state. When receiving the order of the physical downlink control channel for the first slave cell, an entity random access procedure is performed to implement uplink synchronization.

According to a second aspect of the present invention, a method for instructing a user terminal to perform uplink synchronization in a base station includes: transmitting, to a user terminal, an entity downlink control channel order signaling, where the entity downlink control channel order signaling is used to indicate synchronization a first slave cell in a configured and uplink out-of-synchronization state; a media access layer control signaling is sent to the user terminal, and the media access layer controls signaling to activate the first slave cell.

According to a third aspect of the present invention, a method for instructing a user terminal to perform uplink synchronization in a base station includes: transmitting a media access layer control signaling to a user terminal, and the media connection In the inbound control transmission, the first slave cell that is configured and in the uplink out-of-synchronization state is set to be deactivated; the entity downlink control channel is sent to the user terminal, and the entity downlink control channel sequence signaling is used to indicate that the synchronization is in the The first slave cell that is configured and up-synchronized.

With the solution of the present invention, a mechanism for triggering uplink time alignment is provided.

1 shows a state transition diagram of a user terminal in accordance with an embodiment of the present invention.

Hereinafter, the terminology involved in the present invention will be briefly introduced first.

The slave cell is configured: when the user terminal receives the RRC Connection Reconfiguration message from the base station, the slave cell of the user terminal is in a configured but deactivated state.

Starting from the cell: After the slave cell is activated, the slave cell is activated when the user terminal receives the MAC CE message from the base station.

The present invention proposes to define a new Scell state in R11, wherein the state of the Scell is configured but out-of-synchronization (out-of-sync), that is, state A in FIG. For this state A, the following user terminal behavior is defined: 1. In order to save power, the UE does not perform any downlink measurement on the Scell, that is, the first slave cell. For example, the user terminal does not perform CSI measurements. 2. The user terminal will ignore any start/destart commands involving this slave cell and will not perform the R10 defined start/destart operation, ie the UE ignores the start/destart state in receiving the MAC CE, eg, the user The terminal does not perform corresponding Reference Signal Receiving Power (RSRP) measurement, or does not perform RSRP/RSRQ (Reference Signal Receiving Quality) measurement of the Reference Signal (CRS) because The operations defined in R10 can be found in the prior art and, therefore, will not be described herein. In addition, since the Scell still has no uplink time alignment, the UE does not perform uplink transmission after 8 ms (that is, 8 subframes).

Scheme A: Based on the definition of the new state A, the MAC CE is used to trigger the time alignment process for the Scell in this new state A. The process is described as follows: First, in step S20, when the user terminal receives When a MAC CE is used to start a configured but not synchronized Scell, the user terminal will automatically trigger the time alignment process, that is, perform an entity random access procedure to achieve uplink time alignment; After the alignment process is successfully completed, in step S21, the user terminal directly transitions the Scell to the startup state, that is, the state D shown in FIG. 1, because the user terminal knows that the base station now wants to schedule the Scell; then, In step S22, the user terminal immediately starts a normal startup operation without waiting for an additional 8 ms time.

In another embodiment, if in step S20', when the user terminal Upon receiving a MAC CE, when the MAC CE is used to start the Scell that is configured but not synchronized, the user terminal ignores the indication of the de-start, that is, does not perform RSRP/RSRQ measurement of the reference signal.

For the new technical solution proposed by the present invention, the UE has the following advantages: the UE does not have to detect the PDCCH order signaling for the Scell before receiving the start command, thereby saving the UE power; due to the new state definition, the UE does not violate the UE. The active operation principle defined by R10; no additional PDCCH order signaling for time alignment triggering is required, which shortens the delay; after time alignment, Scell directly transitions to the startup state, shortening the delay for true uplink/downlink operation.

As can be seen in Figure 1, state C is also passed from state A to state C, but the state C is transient, which is used to trigger an entity random access procedure on the slave cell, therefore, State C can be ignored.

Scheme B: On the basis of defining a new state A, the base station may first send a PDCCH order transmission to the user terminal, and then send the MAC CE to the user terminal. Correspondingly, before receiving the MAC CE, the user terminal first receives the PDCCH order signaling from the base station for synchronizing the slave cells. After receiving the PDCCH order, the user terminal receives the MAC CE from the base station. Or, if the base station needs to send the MAC CE before sending the PDCCH order signaling, the base station is in the In the MAC CE, the information for the first slave cell must be set to the deactivated state.

Those skilled in the art can understand that the base station can know the state of the user terminal on the slave cell, including whether the user terminal is configured, activated, or deactivated on the cell, whether it is uplink synchronization or uplink out synchronization. Because the slave cell must be deactivated when it is initially configured from the cell. If the user terminal successfully completes the random access procedure on the slave cell, the user terminal is uplink synchronized on the slave cell; otherwise, the user terminal is uplink out-of-synchronization on the slave cell.

The base station may send a PDCCH order signaling on the Scell in the state A, or send a physical downlink control channel order signaling to the Scell in other priming cells, for example, a carrier indication field in the PDCCH signaling (Carrier Indication) Field, CIF) points to the Scell in state A.

Still referring to Figure 1. First, in step S30, the user terminal should detect the PDCCH order transmission on the Scell, or detect the PDCCH transmission on other activated cells. After the user terminal receives a PDCCH order, the PDCCH is used to synchronize the Scell trigger time alignment process, that is, the entity random access process is performed to achieve uplink time alignment, and the user terminal enters the state B, and the user terminal is Configuring and uplink synchronization, but deactivated; after the time alignment process is successfully completed, in step S31, the user terminal receives the MAC CE from the base station, and then according to the received MAC CE, the user terminal changes the Scell state. To the start state, that is, State D, because the user terminal knows that the base station now wants to schedule the Scell; then, in step S22, the user terminal immediately starts a normal startup operation.

Solution C: On the basis of defining a new state A, the user terminal first triggers the PDCCH order signaling or first receives the MAC CE information, and can respectively trigger the user terminal to enter different states.

Similar to the above scheme B, the base station may send a PDCCH order transmission on the Scell in state A, or send a PDCCH order signaling to the Scell in other priming cells.

Still referring to Figure 1. First, in step S40, the user terminal detects the PDCCH order transmission and waits for the MAC CE information.

If the user terminal first receives a PDCCH order signaling, the PDCCH is used to trigger the Scell time alignment process, that is, the entity random access procedure is performed to achieve uplink time alignment, then the user terminal enters the state B, and the user terminal is Configure and uplink synchronization, but deactivated;

The user terminal should transmit the PDCCH order in the deactivated slave cell detection, or detect the PDCCH signaling on the activated slave cell, and the Carrier Indication Field (CIF) in the PDCCH signaling points to the start. From the cell.

After the time alignment process is successfully completed, the user terminal then receives the MAC CE from the base station, and then according to the received MAC CE, the user terminal transitions the Scell state to the startup state, that is, the state D, because the user terminal knows The base station now wants to schedule the Scell.

If the user terminal first receives a MAC CE, and the MAC CE is used to start the Scell that is configured but not synchronized, the user terminal will automatically trigger the time alignment process, that is, perform the physical random access process to reach the uplink time. Alignment; after the time alignment process is successfully completed, the user terminal directly shifts the Scell to the startup state, because the user terminal knows that the base station now wants to schedule the Scell; then, the user terminal immediately starts the normal startup operation without Wait for an extra 8ms.

Other variations to the disclosed embodiments can be understood and effected by those of ordinary skill in the art. The word "comprising" does not exclude other elements and steps, and the word "a" does not exclude the plural. In the practical application of the invention, a part may perform the functions of the plurality of technical features recited in the claims. Any reference signs in the claims should not be construed as limiting the scope.

Other features, objects, and advantages of the present invention will become apparent from the Detailed Description of the Description.

Figure 1 shows a state transition diagram in accordance with an embodiment of the present invention.

Wherein, the same or similar reference numerals indicate the same or similar step features or devices/modules.

Claims (11)

A method of communicating in a user terminal of a wireless communication network, wherein the user terminal is configured with a primary cell and at least one secondary cell, wherein the at least one secondary cell of the secondary cell is configured and not uplink synchronized The method includes: - no downlink channel measurement, A. receiving a media access control layer from the base station to send a message, wherein the media access control layer controls signaling to indicate that the user terminal activates the first slave cell B. performing a physical random access procedure on the first slave cell to achieve uplink time synchronization on the first slave cell; C. modifying the first slave cell to an activated state. The method of claim 1, further comprising the steps of: receiving a media access control layer from the base station to control the sending, wherein the medium access control layer sends a message indicating the user terminal To initiate the first slave cell; II. ignore the start-up indication. The method of claim 1, wherein the method further comprises: a. determining whether a physical downlink control channel ordering for the first slave cell is detected; b. when detecting the first When the physical downlink control channel of the cell is sent in order, the entity random access process is performed to implement uplink synchronization. The method of claim 3, wherein the step b further comprises: c. receiving a media access control layer control signaling from the base station, wherein the media access control layer controls the signaling indication The user terminal activates the first slave cell; d. starts the first slave cell according to the media access control layer controlling the signaling information. The method according to claim 3, wherein the received media access control layer controls the start indication information of the sent message before detecting that the entity downlink control channel sequentially sends a message and implements uplink synchronization. The method of claim 3, wherein the physical downlink control channel order signaling for the first slave cell comprises a physical downlink control channel order signaling detected on the first slave cell, or The physical down-regulation channel directed to the first slave cell detected in the other promoter cells is sent in sequence. The method of claim 1, wherein the method further comprises: determining whether a media access control layer from the base station is received to control signaling or detecting an entity from the base station for the first slave cell The downlink control channel sequentially sends a message; when receiving the media access control layer to control the sending to initiate to the first slave cell, performing an entity random access procedure on the first slave cell to the first slave cell Upstream synchronization is implemented on the uplink; - modifying the first slave cell to an active state; when detecting the physical downlink control channel ordering for the first slave cell, - performing an entity random access procedure to achieve uplink synchronization. The method of claim 7, wherein the physical downlink control channel order signaling for the first slave cell comprises a physical downlink control channel order signaling detected on the first slave cell, or The physical down-regulation channel directed to the first slave cell detected in the other promoter cells is sent in sequence. A method for instructing a user terminal to perform uplink synchronization in a base station, comprising: i. transmitting a physical downlink control channel order transmission to a user terminal, where the entity downlink control channel order signaling is used to indicate that uplink synchronization is configured and uplink is out of synchronization. a first slave cell of the state; ii. transmitting a media access layer control signaling to the user terminal, and the media access layer controls signaling to activate the first slave cell. The method of claim 9, wherein the step i further comprises: - transmitting a physical downlink control channel order transmission on the first slave cell; or - transmitting the first to the first initiator cell The channel is sent from the physical downlink control channel of the cell. A method for indicating uplink synchronization of a user terminal in a base station, including: Transmitting, by the user access terminal, a media access layer control signaling, and the media access layer controls the first slave cell in the configured and uplink out-of-synchronization state to be set to start; and transmitting the physical downlink control to the user terminal The channel order signaling, the entity downlink control channel order signaling is used to indicate that the uplink synchronization is in the first slave cell that is configured and uplink out of sync state.