SYSTEMS AND METHODS FOR INDICATING TIMING DIFFERENCE BETWEEN DIFFERENT CELLS

A system and method for indicating timing difference between different cells. In one aspect, a wireless method may include measuring, by a wireless communication device, a current timing difference between a first time unit used in a first cell and a second time unit used in a second cell. In some embodiments, the method may include sending, by the wireless communication device to a wireless communication node, a message indicating the current timing difference.

TECHNICAL FIELD

The disclosure relates generally to wireless communications and, more particularly, to systems and methods for indicating timing difference between different cells.

BACKGROUND

The standardization organization Third Generation Partnership Project (3GPP) is currently in the process of specifying a new Radio Interface called 5G New Radio (5G NR) as well as a Next Generation Packet Core Network (NG-CN or NGC). The 5G NR will have three main components: a 5G Access Network (5G-AN), a 5G Core Network (5GC), and a User Equipment (UE). In order to facilitate the enablement of different data services and requirements, the elements of the 5GC, also called Network Functions, have been simplified with some of them being software based, and some being hardware based, so that they could be adapted according to need.

SUMMARY

At least one aspect is directed to a system, method, apparatus, or a computer-readable medium. In one embodiment, a wireless communication device (e.g., user equipment) may measure a current timing difference between a first time unit used in a first cell and a second time unit used in a second cell. In some embodiments, the wireless communication device may send a message indicating the current timing difference, or a composition of a time interval, or an information of a switching period to a wireless communication node (e.g., base station). In certain embodiments, each of the first time unit and the second time unit may include one of: a symbol, a sub-slot, a slot, a sub-frame, or a frame.

In another aspect, the message may include in at least one of: a Radio Resource Control (RRC) signaling, a Medium Access Control (MAC) Control Element (CE), or a Uplink Control Information (UCI). In some embodiments, the current timing difference can be a difference between a first transmission timing corresponding to the first time unit and a second transmission timing corresponding to the second time unit.

In another aspect, the second time unit, along a time domain, can be closest to the first time unit than any other time unit used in the second cell. In some embodiments, the first time unit and second time unit may have an identical index. In some embodiments, the wireless communication device may periodically send the message to the wireless communication node.

In some embodiments, the wireless communication device may determine that a difference between the current timing difference and a previous timing difference can be equal to or greater than a threshold so as to send the message. In certain embodiments, the previous timing difference can be indicated by a last message reported by the wireless communication device to the wireless communication node.

In some embodiments, the wireless communication device may determine to switch uplink transmission from the first cell to the second cell. In some embodiments, the wireless communication device may identify that a switching period can be located in the first cell.

In some embodiments, the wireless communication device may determine to switch uplink transmission from a first cell group including the first cell to a second cell group including the second cell. In some embodiments, the wireless communication device may identify that a switching period can be located in the first cell group. In some embodiments, the wireless communication device may determine that a current composition/configuration of a current time interval, during which downlink reception and/or the uplink transmission is interrupted based on the switching period, may have changed from a previous composition/configuration of a previous time interval so as to send the message.

In certain embodiments, the current time interval and the previous time interval can be determined based on the switching period that has a same location within respective time units. In some embodiments, the previous time interval can be determined based on a previous timing difference.

In some embodiments, each of the current time interval and the previous time interval can be constituted of a plurality of time units, a starting one of which partially or fully overlaps with the switching period in a time domain. In some embodiments, the message may further include the information of the switching period that includes the first time unit or a last time unit.

At least one aspect is directed to a system, method, apparatus, or a computer-readable medium. In some embodiments, a wireless communication node may receive a message indicating a current timing difference, or a composition of a time interval, or a information of a switching period from a wireless communication device. In some embodiments, the current timing difference can be measured by the wireless communication device between a first time unit used in a first cell and a second time unit used in a second cell.

DETAILED DESCRIPTION

A. Network Environment and Computing Environment

FIG.1illustrates an example wireless communication network, and/or system,100in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure. In the following discussion, the wireless communication network100may be any wireless network, such as a cellular network or a narrowband Internet of things (NB-IoT) network, and is herein referred to as “network100”. Such an example network100includes a base station102(hereinafter “BS102”) and a user equipment device104(hereinafter “UE104”) that can communicate with each other via a communication link110(e.g., a wireless communication channel), and a duster of cells126,130,132,134,136,138and140overlaying a geographical area101. InFIG.1, the BS102and UE104are contained within a respective geographic boundary of cell126. Each of the other cells130,132,134,136,138and140may include at least one base station operating at its allocated bandwidth to provide adequate radio coverage to its intended users.

For example, the BS102may operate at an allocated channel transmission bandwidth to provide adequate coverage to the UE104. The BS102and the UE104may communicate via a downlink radio frame118, and an uplink radio frame124respectively. Each radio frame118/124may be further divided into sub-frames120/127which may include data symbols122/128. In the present disclosure, the BS102and UE104are described herein as non-limiting examples of “communication nodes,” generally, which can practice the methods disclosed herein. Such communication nodes may be capable of wireless and/or wired communications, in accordance with various embodiments of the present solution.

FIG.2illustrates a block diagram of an example wireless communication system200for transmitting and receiving wireless communication signals, e.g., OFDM (orthogonal frequency division multiplexing)/OFDMA (orthogonal frequency division multiplexing access) signals, in accordance with some embodiments of the present solution. The system200may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one illustrative embodiment, system200can be used to communicate (e.g., transmit and receive) data symbols in a wireless communication environment such as the wireless communication environment100ofFIG.1, as described above.

System200generally includes a base station202(hereinafter “BS202”) and a user equipment device204(hereinafter “UE204”). The BS202includes a BS (base station) transceiver module210, a BS antenna212, a BS processor module214, a BS memory module216, and a network communication module218, each module being coupled and interconnected with one another as necessary via a data communication bus220. The UE204includes a UE (user equipment) transceiver module230, a UE antenna232, a UE memory module234, and a UE processor module236, each module being coupled and interconnected with one another as necessary via a data communication bus240. The BS202communicates with the UE204via a communication channel250, which can be any wireless channel or other medium suitable for transmission of data as described herein.

In accordance with some embodiments, the UE transceiver230may be referred to herein as an “uplink” transceiver230that includes a radio frequency (RF) transmitter and a RF receiver each comprising circuitry that is coupled to the antenna232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in time duplex fashion. Similarly, in accordance with some embodiments, the BS transceiver210may be referred to herein as a “downlink” transceiver210that includes a RF transmitter and a RF receiver each comprising circuitry that is coupled to the antenna212. A downlink duplex switch may alternatively couple the downlink transmitter or receiver to the downlink antenna212in time duplex fashion. The operations of the two transceiver modules210and230can be coordinated in time such that the uplink receiver circuitry is coupled to the uplink antenna232for reception of transmissions over the wireless transmission link250at the same time that the downlink transmitter is coupled to the downlink antenna212. In some embodiments, there is close time synchronization with a minimal guard time between changes in duplex direction.

The UE transceiver230and the base station transceiver210are configured to communicate via the wireless data communication link250, and cooperate with a suitably configured RF antenna arrangement212/232that can support a particular wireless communication protocol and modulation scheme. In some illustrative embodiments, the UE transceiver230and the base station transceiver210are configured to support industry standards such as the Long Term Evolution (LTE) and emerging 5G standards, and the like. It is understood, however, that the present disclosure is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver230and the base station transceiver210may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

The network communication module218generally represents the hardware, software, firmware, processing logic, and/or other components of the base station202that enable bi-directional communication between base station transceiver210and other network components and communication nodes configured to communication with the base station202. For example, network communication module218may be configured to support internet or WiMAX (World Interoperability for Microwave Access) traffic. In a typical deployment, without limitation, network communication module218provides an 802.3 Ethernet interface such that base station transceiver210can communicate with a conventional Ethernet based computer network. In this manner, the network communication module218may include a physical interface for connection to the computer network (e.g., Mobile Switching Center (MSC)). The terms “configured for,” “configured to” and conjugations thereof, as used herein with respect to a specified operation or function, refer to a device, component, circuit, structure, machine, signal, etc., that is physically constructed, programmed, formatted and/or arranged to perform the specified operation or function.

B. Indicating Timing Difference Between Different Cells

A wireless communication device (e.g., UE) may be equipped/provided with fixed number of transmission/communication ports. In some embodiments, a UE can be equipped/provided with two transmission/communication ports. The UE may transmit signal(s)/message(s)/information to two wireless communication nodes (e.g., serving cells). When (e.g., in response to) the UE is configured more than two serving cells or carriers, the uplink (UL) transmission can be switched between these cells or carriers with the purpose that the UE can transmit signal(s)/message(s)/information to all the serving cells or carriers at different times. The UL transmission switching may lead to a downlink (DL) reception interruption and/or an uplink (UL) transmission interruption. When (e.g., in response to) a UL transmission timing is not aligned between these serving cells or carriers, the network may not know the UL transmission interruption time and/or the DL reception interruption time. In certain embodiments, some methods/approaches are provided in such a way that the network can know such information/message(s) and perform more efficient scheduling of transmissions/communications.

In some embodiments, a UE can be configured with a plurality of serving cells. A serving cell may include one or more uplink carriers. The UE can be configured with a plurality of uplink carriers. In addition, the UE can be configured with a plurality of serving cell groups/sets, or uplink carrier groups/sets. Each serving cell group may comprise one or more serving cells of the plurality of serving cells. Each uplink carrier group may comprise one or more uplink carriers of the plurality of uplink carriers.

The network may configure uplink transmission switching from one serving cell to another serving cell among the plurality of serving cells, or from one uplink carrier to another uplink carrier among the plurality of uplink carriers. For the uplink transmission switching between a first serving cell and a second serving cell, the network may configure that a switching period can be located in one serving cell (e.g., in the first serving cell or in the second serving cell). In addition, the network may configure that which one may be carrier 1 and/or which one may be carrier 2. If a serving cell is configured to be carrier 1, all the uplink carriers of this serving cell can be carrier 1. If a serving cell is configured to be carrier 2, all the uplink carriers of this serving cell can be carrier 2. A length of the switching period may be reported/determined/obtained/configured via/by the UE or configured by the network. In some embodiments, the length of the switching period may be sum of a value reported by the UE and a first value. The first value may be configured by a network and/or specified by a protocol. In certain embodiments, the first value can be equal to the timing difference between one (serving) cell and another (serving) cell.

For example, for the uplink transmission switching between a first uplink carrier and a second uplink carrier, the network may configure that switching period can be located in one uplink carrier (e.g., in the first uplink carrier or the second uplink carrier). The network may configure that which one can be carrier 1 and/or which one can be carrier 2.

The network may configure an uplink transmission switching from one serving cell group to another serving cell group among a plurality of serving cell groups, or from one uplink carrier group to another uplink carrier group among a plurality of the uplink carrier groups. For the uplink transmission switching between a first group and a second group, the network may configure that the switching period can be located in one group (e.g., in the first group or in the second group). In addition, the network can configure that which one can be carrier 1 and/or which one can be carrier 2. The group can be a serving cell group or an uplink carrier group. If the serving cell group or the uplink carrier group is configured to be carrier 1, all the uplink carriers of the serving cell group or all the uplink carriers of the uplink carrier group can be carrier 1. If the serving cell group or the uplink carrier group is configured to be carrier 2, all the uplink carriers of the serving cell group or all the uplink carriers of the uplink carrier group can be carrier 2.

During the switching period, the UE may not be allowed/enabled/supported to transmit any signal(s)/message(s)/information to the serving cells. If a configured transmission/communication overlaps with the switching period, the transmission/communication can be dropped. For a nominal physical uplink shared channel (PUSCH) repetition that may overlap with the switching period, the nominal PUSCH repetition can be segmented to actual PUSCH, where orthogonal frequency division multiplexing (OFDM) symbols overlapping with the switching period can be considered as invalid symbols. The dropped transmission/communication or the segmented PUSCH repetition can be transmitted on the carrier in which the switching period can be located.

In certain embodiments, a UE may be configured with 4 serving cells, denoted by cell 0, cell 1, cell 2 and cell 3, respectively. Each serving cell only may comprise one uplink carrier. The network may configure that the switching period can be located in the cell 0 for the uplink transmission switching between the cell 0 and cell 1. The network may configure that cell 0 can be carrier 1 and/or cell 1 can be carrier 2. The other configurations are shown in Table 1.

The network may further configure/incorporate that group 0 may comprise cell 0 and/or cell 1. The group 1 may comprise cell 2 and/or cell 3. The group 2 may comprise cell 0 and/or cell 3. The group 3 may comprise cell 1. For the uplink transmission switching between group 0 and group 1, the network may configure that the switching period can be located in group 0 (e.g., in the cell 0 and/or cell 1). The network may configure that the group 0 can be carrier 1 and/or group 1 can be carrier 2. In some embodiments, cell 0 and/or cell 1 can be carrier 1 and cell 2 and/or cell 3 can be carrier 2 for the uplink transmission switching between group 0 and group 1. The other configurations for the uplink transmission switching are shown in Table 2.

In some embodiments, a UE may measure/calculate a timing difference between two (serving) cells. The timing difference can be a UL transmission timing difference between two cells. In one aspect, the timing difference can be the UL transmission timing difference between a first time unit boundary of a first (serving) cell and a second time unit boundary of a second (serving) cell. The timing difference can be a period of time between a timing when (e.g., in response to) the UE transmits the first time unit boundary of the first (serving) cell and another timing when (e.g., in response to) the UE transmits the second time unit boundary of the second (serving) cell. The time unit can be one of orthogonal frequency division multiplexing (OFDM) symbol, sub-slot, slot, sub-frame, or frame. The time unit boundary can be the starting boundary of the time unit or the ending boundary of the time unit. In some embodiments, the UE may send a signal/message/information indicating the timing difference, or a composition of a time interval, or a information of a switching period to a wireless communication node (e.g., base station).

In some embodiments, the second time unit can be a time unit of the second (serving) cell that may be the most close to the first time unit. The timing difference can be the UL transmission timing difference between a time unit of the first (serving) cell and the closest time unit of the second (serving) cell.

The second time unit may have the same time unit index (e.g., symbol, sub-slot, slot, sub-frame, and frame) with the first time unit. If the time unit is frame, the second frame and the first frame may have the same frame number. If the time unit is slot, the second slot may have the same slot number and/or the same frame number with the first slot. The timing difference can be the UL transmission timing difference between a time unit of the first (serving) cell and the closet time unit of the second (serving) cell with the same time unit index.

Referring now toFIG.3, for a UE, there can be 8 frames in (serving) cell 0,302, and (serving) cell 1,304, each of which includes 8 frames that are denoted by frame 0˜7, respectively. The UE may measure/calculate the timing difference between a frame in (serving) cell 0,302, and the closest frame in (serving) cell 1,304. For frame 2 in (serving) cell 0,302, the closest frame in (serving) cell 1,304, can be frame 0. The timing difference can be the difference between the transmission time of the starting boundary of frame 2 in (serving) cell 0,302, and the transmission time of the starting boundary of frame 0 in (serving) cell 1,304. The UE may transmit the starting boundary of the frame 0 in (serving) cell 1,304at t1. The UE may transmit the starting boundary of the frame 2 in (serving) cell 0,302, at t2. The timing difference (T1) can be t1−t2 or t2−t1.

The UE may measure/calculate the timing difference between a frame in (serving) cell 0,302, and the closet frame in (serving) cell 1,304, with the same frame number. The timing difference can be the difference between the transmission time of the starting boundary of the frame 4 in (serving) cell 0,302, and the transmission time of starting boundary of the frame 4 in (serving) cell 1,304. The UE may transmit the starting boundary of the frame 4 in (serving) cell 0,302, at t3. The UE may transmit the starting boundary of the frame 4 in (serving) cell 1,304, at t4. The timing difference (T2) can be t4−t3 or t3−t4. In certain embodiments, the UE may report/indicate/send the timing difference via a message/signal to the wireless communication node. The message/signal can be reported/indicated/sent by Radio Resource Control (RRC) signaling, Medium Access Control (MAC) Control Element (CE), or Uplink Control Information (UCI).

For a UL transmission switching, a DL reception interruption within a first time interval for a carrier may be caused by a switching period. The first time interval may comprise a plurality of OFDM downlink symbols. For example, the first time interval may comprise Y downlink OFDM symbols, where Y can be an integer larger than 0. The first time interval may start from a first symbol that fully or partly can overlap with the switching period for the UL transmission switching. The value of Y can be indicated by a network and/or specified by a protocol. The UE may not attempt to perform/provide a DL reception on these symbols (of the first time interval) in the carrier.

The UE may report/indicate/send the composition/configuration of the first time interval to the wireless communication node. For example, the UE may report a plurality of OFDM symbols comprised/included in the first time interval to the wireless communication node. The plurality of OFDM symbols of the first time interval can be determined, by the UE, by using a switching period that starts from the boundary of a certain time unit and/or by using a switching period that ends by the boundary of a certain time unit. The UE may report, to the wireless communication node, the plurality of OFDM symbols of the first time interval corresponding to one or more switching periods. The information of the switching period (e.g., the index of the starting time unit and/or the ending time unit of the switching period) may be reported together with the composition/configuration of the first time interval to the wireless communication node. If the switching period used for determining the plurality of OFDM symbols of the first time interval starts from a boundary of a time unit, the index of the first time unit within the switching period can be reported/indicated/sent to the wireless communication node. If the switching period used for determining the plurality of OFDM symbols of the first time interval ends by a boundary of a time unit, the index of the last time unit within the switching period can be reported/indicated/sent to the wireless communication node.

Referring now toFIG.4, for a UE, there can be three carriers, which can be denoted by carrier 0,402, carrier 1,404, and carrier 2,406, respectively. For carrier 0,402, an uplink transmission timing is illustrated. For carrier 1,404, and carrier 2,406, a downlink reception timing is illustrated. The subcarrier spacing (SCS) of carrier 0,402, and carrier 2,406, can be 15 kHz. The SCS of carrier 1,404, can be 30 kHz. The length of OFDM symbol of 15 kHz is two times of the OFDM symbol of 30 kHz. A slot may comprise 14 OFDM symbols, which can be denoted by symbol 0˜13, respectively. A first time interval may comprise a plurality of OFDM downlink symbols. In carrier 1,404, the first time interval may comprise 6 symbols. In carrier 2,406, the first time interval may comprise 3 symbols.

The switching period can be located in the carrier 0,402. The switching period can start at any time. In one example, two switching periods are illustrated. The first switching period may end by the ending boundary of OFDM symbol 13 (or the ending boundary of the slot 8, or the starting boundary of the slot 9, or the starting boundary of OFDM symbol 0). In carrier 1,404, the first symbol that fully or partly overlaps with the first switching period is symbol 5. The first time interval may comprise symbol 5, 6, 7, 8, 9, and 10 in carrier 1,404. In carrier 2,406, the first symbol that fully or partly overlaps with the first switching period is symbol 12. The first time interval may comprise symbol 12, 13 and 0 in carrier 2,406.

The second switching period may start from the starting boundary of symbol 2 (or ending boundary of symbol 1) in carrier 0,402. In carrier 1,404, the first symbol that fully or partly overlaps with the second switching period is symbol 0. The first time interval may comprise symbol 0, 1, 2, 3, 4, and 5. In carrier 2,406, the first symbol that fully or partly overlaps with the second switching period is symbol 2. The first time interval may comprise symbol 2, 3, and 4.

The UE may report/indicate/send, to a wireless communication node, that the first time interval can comprise symbol 5, 6, 7, 8, 9, and 10 in carrier 1,404, and/or symbol 12, 13, and 0 in carrier 2,406, for the switching period located in carrier 0,402, that ends by an ending boundary of symbol 13, and/or the first time interval may comprise symbol 0, 1, 2, 3, 4, and 5 in carrier 1,404, and/or symbol 2, 3, and 4 in carrier 2,406, for the switching period located in carrier 0,402, that starts from the starting boundary of symbol 2.

For an uplink transmission switching, a UE may report/indicate/send a plurality of serving cells with a DL reception interruption caused by a switching period. The UE may report a composition/configuration of a first time interval in the plurality of serving cells. In certain embodiments, if more than one serving cells belong to a timing advance group (TAG), the UE may report the composition/configuration of the first time interval corresponding to only one of the more than one serving cells. In some embodiments, the UE may report the composition/configuration of the first time interval in the carrier affected/influenced by the uplink switching between each one carrier and another carrier among a plurality of carriers.

The UE may report/indicate/send at least one of: the timing difference or the composition/configuration of the first time interval message/information, or the message/information of the switching period used for determining the composition/configuration of the first time interval to the wireless communication node. In various embodiments, information (e.g., length, starting boundary, ending boundary, index of corresponding starting time unit, and index of corresponding ending time unit) of the switching period can be reported together with the composition/configuration of the first time interval. The UE may periodically send/report/indicate at least one of: the timing difference, the composition/configuration, or the message/information of the switching period to the wireless communication node. In some embodiments, the UE may report/send/indicate at least one of: the timing difference or the composition/configuration of the first time interval or the message/information of the switching period used for determining the composition/configuration of the first time interval to the wireless communication node when (e.g., in response to) the change of the measured/calculated timing difference is equal to or larger than a threshold Z (Z>0) compared to the last timing difference that the UE may report to the wireless communication node. The value of the threshold Z can be configured by a network and/or specified by a protocol. If a timing difference is reported/updated by the UE successfully, the reported/updated timing difference can be used/applied as a reference for a subsequent timing difference change determination.

Referring now toFIG.5, at one moment, a UE may transmit a starting boundary of frame 4 in (serving) cell 0,502, at t3. The UE may transmit the starting boundary of frame 4 in (serving) cell 1,504, at t4. The timing difference (T2) can be t3−t4 or t4−t3. The timing difference T2 may be sent to the wireless communication node. At another moment, the timing difference (T2′) can be t5−t6 or t6−t5, since the UE may transmit the starting boundary of frame 4 in (serving) cell 0,512, at t5, and the UE may transmit the starting boundary of frame 4 in (serving) cell 1,514, at t6. If the difference between T2 and T2′ is equal to or larger than Z, the UE may report/indicate/send/update at least one of: the new timing difference (e.g., T2′) or the composition/configuration of the first time interval, or the message/information of the switching period used for determining the composition/configuration of the first time interval to the wireless communication node. After reporting/updating the timing difference, the reported/updated timing difference (e.g., T2′) can be used as a reference for determining/estimating/calculating the timing difference change between (serving) cell 0 and (serving) cell 1 subsequently.

In some embodiments, the UE may report at least one of the timing difference or the composition/configuration of the first time interval, or the message/information of the switching period used for determining the composition/configuration of the first time interval to the wireless communication node when the composition/configuration of the first time interval changes. The composition/configuration of the first time interval may change due to a UL transmission timing difference. If the composition/configuration of the first time interval is reported/indicated/sent by the UE successfully, the reported composition/configuration of the first time interval can be used/applied as a reference for the subsequent composition/configuration of the first time interval change determination subsequently. When determining the change of the composition/configuration of the first time interval, the same location of the switching period in the time unit can be used.

Referring now toFIG.6, for a UE, a switching period located in carrier 0,602, may end by the ending boundary of slot 8. For the switching period, at the first moment, the first time interval may comprise symbol 5, 6, 7, 8, 9, and 10 in carrier 1,604, and/or symbol 12, 13 and 0 in carrier 2,606.

At the second moment, in carrier 1,614, the first symbol that fully or partly overlaps with the starting boundary of switching period in carrier 0,612, is symbol 6. The first time interval may comprise symbol 6, 7, 8, 9, 10 and 11 in carrier 1,614. The composition/configuration of the first time interval in carrier 1 may change from symbol 5˜10 to symbol 6˜11. The UE can report/indicate/send at least one of: the timing difference or composition/configuration of the first time interval in carrier 1,614or the ending time unit of the switching period in carrier 0,612. After successful reporting, the reported composition/configuration of the first time interval (e.g., symbol 6˜11) can be used for determining/estimating/calculating the composition/configuration of the first time interval change in carrier 1 subsequently.

At the third moment, in carrier 2,624, the first symbol that fully or partly overlaps with the starting boundary of switching period in carrier 0,622, is symbol 11. The first time interval comprises symbol 11, 12, and 13 in carrier 2,624. The composition/configuration of the first time interval in carrier 2 may change from symbol 12, 13, and 0 to symbol 11, 12, and 13. The UE can report/indicate/send at least one of: the timing difference or composition/configuration of the first time interval in carrier 2,624or the ending time unit of the switching period in carrier 0,622. After successful reporting, the reported composition/configuration of the first time interval (e.g., symbol 11, 12, 13) can be used for determining/estimating/calculating the composition/configuration of the first time interval change in carrier 2 subsequently.

A composition/configuration of a first time interval can be affected/influenced by a location of a switching period and/or a timing difference. The switching period can be anywhere. For example, there are two switching periods with different locations in a slot inFIG.4. The composition/configuration of the first time intervals corresponding to the two switching period can be different. In certain embodiments, the location of the switching period may remain unchanged in such a way that the only factor that may lead to the change of composition/configuration of the first time interval is timing difference. The switching period location is not changed inFIG.6.

A UE can be configured by a network with a plurality of serving cells. At least a first serving cell of the plurality of serving cells may belong to a first timing advance group (TAG). At least a second serving cell of the plurality of serving cells may belong to a second TAG. When (e.g., in response to) a control information/configuration carried in a downlink transmission transmitted in the first serving cell schedules a uplink transmission in the second serving cell, a uplink transmission timing difference between the first serving cell and the second serving cell (or between the first TAG and the second TAG) can be taken into account for a second time interval between the uplink transmission and a downlink transmission.

The control information/configuration can be a downlink control information (DCI), a MAC CE, or a RRC signaling. The uplink transmission can be a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). The downlink transmission can be a physical downlink control channel (PDCCH) carrying the control information or a physical downlink shared channel (PDSCH) scheduled by the control information.

A PDSCH scheduled by a downlink control information (DCI) and corresponding to a PUCCH transmitted on a second serving cell, may be transmitted on a first serving cell. The PUCCH may carry a Hybrid Automatic Repeat Request Acknowledge (HARQ-ACK) for the PDSCH. If the time interval between the PDSCH and the PUCCH should be larger than X1 when the first (serving) cell and the second (serving) cell belong to the same TAG, the time interval between the PDSCH and the PUCCH should be larger than X1+D when the first (serving) cell and the second (serving) cell belong to different TAGs, where D can be the uplink transmission timing difference between the first (serving) cell and the second (serving) cell. The value of X1 can be configured by the network or specified by a protocol.

For example, if a first uplink symbol of a PUCCH which carries a HARQ-ACK information, as defined by the assigned HARQ-ACK timing K1and the PUCCH resource to be used, including the effect of the timing advance, starts no earlier than at symbol L1, where L1can be defined as a next uplink symbol with its Cyclic Prefix (CP) starting after Tproc,1=(N1+d1,1+d2)(2048+144)·κ2−μ·Tc+Text+Tdeltaafter the end of the last symbol of the PDSCH carrying the transport block (TB) being acknowledged, the UE can provide a valid HARQ-ACK message, where Tdeltacan be the uplink transmission timing difference between the (serving) cell for PDSCH transmission and the (serving) cell for the PUCCH transmission. The value of Tproc,1, N1, d1,1, d2, Tc, and Textcan be configured by the network or specified by a protocol.

A DCI transmitted on a first (serving) cell may schedule a PUSCH transmitted on the second (serving) cell. If the time interval between the PDCCH carrying the DCI and the PUSCH should be larger than X2 when the first (serving) cell and the second (serving) cell belong to the same TAG, the time interval between the PDCCH carrying the DCI and the PUSCH should be larger than X2+D when the first (serving) cell and the second (serving) cell belong to different TAGs, where D can be the uplink transmission timing difference between the first (serving) cell and the second (serving) cell. The value of X2 can be configured by the network or specified by a protocol.

For example, if a first uplink symbol in a PUSCH allocation for a transport block, including a demodulation reference signal (DM-RS), as defined by a slot offset K2and a start S and a length L of the PUSCH allocation indicated by Time domain resource assignment of a scheduling DCI, including a effect of a timing advance, is no earlier than at symbol L2, where L2can be defined as the next uplink symbol with its CP starting after Tpro,2=max((N2+d2,1+d2)(2048+144)·κ2−μ+Text+Tswitch+Tdelta, d2,2) after the end of a reception of the last symbol of the PDCCH carrying the DCI scheduling the PUSCH, the UE may transmit the transport block, where Tdeltacan be the uplink transmission timing difference between the (serving) cell for PDCCH transmission and the (serving) cell for the PUSCH transmission. The value of Tpro,2, N2, d2,1, d2, Text, Tswitch, and d2,2can be configured by the network or specified by a protocol.

FIG.7illustrates a flowchart diagram illustrating a method700for indicating timing difference between different (serving) cells, in accordance with some embodiments of the present disclosure. Referring toFIGS.1-6, the method700can be performed by a wireless communication device (e.g., a UE), in some embodiments. Additional, fewer, or different operations may be performed in the method700depending on the embodiment.

A wireless communication device may measure/calculate a current timing difference between a first time unit used in a first (serving) cell and a second time unit used in a second (serving) cell (705). The wireless communication device may send a message indicating the current timing difference to a wireless communication node (710). A wireless communication node may receive a message indicating a current timing difference (720).

In one embodiment, a wireless communication device (e.g., user equipment) may measure a current timing difference between a first time unit used in a first (serving) cell and a second time unit used in a second (serving) cell. In some embodiments, the wireless communication device may send a message indicating the current timing difference, or a composition of a time interval, or a information of a switching period to a wireless communication node. The message may include in at least one of: a Radio Resource Control (RRC) signaling, a Medium Access Control (MAC) Control Element (CE), or a Uplink Control Information (UCI). Each of the first time unit and the second time unit may include one of: a symbol, a sub-slot, a slot, a sub-frame, or a frame.

In some embodiments, the current timing difference can be a difference between a first transmission timing corresponding to the first time unit and a second transmission timing corresponding to the second time unit.

In some embodiments, the second time unit, along a time domain, can be closest to the first time unit than any other time unit used in the second (serving) cell. In some embodiments, the first time unit and second time unit may have an identical index. In certain embodiments, the wireless communication device may periodically send the message to the wireless communication node.

In some embodiments, the wireless communication device may determine that a difference between the current timing difference and a previous timing difference can be equal to or greater than a threshold so as to send the message. In certain embodiments, the previous timing difference can be indicated by a last message reported by the wireless communication device to the wireless communication node.

In some embodiments, the wireless communication device may determine to switch uplink transmission from the first (serving) cell to the second (serving) cell. In some embodiments, the wireless communication device may identify that a switching period can be located in the first (serving) cell.

In some embodiments, the wireless communication device may determine to switch uplink transmission from a first (serving) cell group including the first (serving) cell to a second (serving) cell group including the second (serving) cell. In some embodiments, the wireless communication device may identify that a switching period can be located in the first (serving) cell group. In some embodiments, the wireless communication device may determine that a current composition/configuration of a current time interval, during which downlink reception and/or the uplink transmission is interrupted based on the switching period, may have changed from a previous composition/configuration of a previous time interval so as to send the message.

In certain embodiments, the current time interval and the previous time interval can be determined based on the switching period that has a same location within respective time units. In some embodiments, the previous time interval can be determined based on a previous timing difference.

In some embodiments, each of the current time interval and the previous time interval can be constituted of a plurality of time units, a starting one of which partially or fully overlaps with the switching period in a time domain. In some embodiments, the message may further include the information of the switching period that includes the first time unit or a last time unit.

At least one aspect is directed to a system, method, apparatus, or a computer-readable medium. In some embodiments, a wireless communication node may receive a message indicating a current timing difference, or a composition of a time interval, or a information of a switching period from a wireless communication device. In some embodiments, the current timing difference can be measured by the wireless communication device between a first time unit used in a first (serving) cell and a second time unit used in a second (serving) cell.