Timing advance determination without random access channel (RACH)

Abstract

This disclosure provides systems, methods, and apparatus for determining a target base station timing advance value between a user equipment (UE) and a target base station in conjunction with a handover procedure without a random access channel (RACH). In one aspect, the UE may determine the target base station timing advance based at least in part on a timing difference between the target base station and the source base station and at least in part on timing offsets associated with the UE's uplink and downlink. In some aspects, the target base station may use the UE's uplink reference signal to determine the timing advance. In some aspects, the UE may report the timing difference between the target base station and the source base station, and the source cell may determine the timing advance based at least in part on the timing difference.

Description

[0001] This application is a divisional application of application filed on August 20, 2021, with application number 202080015704.X and invention title "Advance Timing Determination without Random Access Channel (RACH)". Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 808,151, filed February 20, 2019, entitled “RANDOM ACCESS CHANNEL (RACH) - LESS TIMING ADVANCE DETERMINATION”; and U.S. Non-Provisional Patent Application No. 16 / 794,091, filed February 18, 2020, entitled “RANDOM ACCESS CHANNEL (RACH) - LESS TIMING ADVANCE DETERMINATION”, both of which are assigned to the assignee of this application. The disclosures of these earlier applications are considered part of this patent application and are incorporated herein by reference. Technical Field

[0003] In general, aspects of this disclosure relate to wireless communications, and more specifically, aspects of this disclosure relate to techniques and apparatus for advance timing determination for a random access channel (RACH). Background Technology

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunications services such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / Improved LTE is an enhanced set of the Universal Mobile Telecommunications System (UMTS) mobile standard released by the 3rd Generation Partnership Project (3GPP).

[0005] Wireless communication networks may include multiple base stations (BSs) capable of supporting communication for multiple user equipments (UEs). UEs can communicate with base stations (BSs) via downlink (DL) and uplink (UL). DL (or forward link) refers to the communication link from the BS to the UE, while UL (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, an LTE Evolved Node B (eNB), a gNB, an Access Point (AP), a Radio Headend, a Transmit / Receive Point (TRP), a New Radio (NR) BS, or a 5G Node B.

[0006] The above multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different user equipment to communicate at the city, country, region, and even global levels. NR (which can also be referred to as 5G) is an enhancement set of the LTE mobile standard released by the 3rd Generation Partnership Project (3GPP). NR is designed to better integrate with other open standards by improving spectrum efficiency, reducing costs, improving service, utilizing new spectrum, and using OFDM with cyclic prefix (CP-OFDM) on DL, and using CP-OFDM or SC-FDM (e.g., also known as Discrete Fourier Transform Spread Spectrum OFDM (DFT-s-OFDM)) (or combinations thereof) on UL, thereby better supporting mobile broadband internet access, and supporting beamforming, multiple-input multiple-output (MIMO) antenna technologies and carrier aggregation. However, with the continued growth in demand for mobile broadband access, there is a need for further improvements to LTE and NR technologies. Summary of the Invention

[0007] The systems, methods, and apparatuses disclosed herein are innovative in several ways, but no single aspect is solely responsible for the desired properties disclosed herein.

[0008] One innovative aspect of the subject matter described in this disclosure can be implemented in a method of wireless communication performed by a device of a user equipment (UE). The method may include: receiving information identifying timing offsets associated with uplink (UL) and downlink (DL) communications of the UE. The method may include: determining a target base station timing advance value for handover to a target base station based at least in part on at least one of the following: the information identifying the timing offset, a timing difference between the target base station and a source base station associated with the UE, or a source base station timing advance value associated with the source base station.

[0009] In some implementations, the timing difference is at least partially based on a reference signal timing difference between the target base station and the source base station. In some implementations, the method may include determining the timing difference between the target base station and the source base station based at least partially on reference signaling received from the source base station and the target base station. In some implementations, the timing offset is at least partially based on switching time, propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

[0010] In some implementations, the granularity of the timing offset is at least partially based on at least one of the target base station's digital scheme or time slot length. In some implementations, the information identifying the timing offset is received in a handover command. In some implementations, the target base station timing advance value is determined without performing a random access procedure. In some implementations, the target base station timing advance value is determined at least partially based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

[0011] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for a UE for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: receive information identifying timing offsets associated with UL and DL communications of the UE; and determine a target base station timing advance value for handover to a target base station based at least in part on: the information identifying the timing offset, a timing difference between the target base station and a source base station associated with the UE, or a source base station timing advance value associated with the source base station. In some aspects, the UE may perform or implement any one or more of the aspects described above or elsewhere herein in conjunction with the methods.

[0012] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium may store one or more instructions for wireless communication. When executed by one or more processors of the UE, the one or more instructions may cause the one or more processors to: receive information identifying a timing offset associated with the UE's UL and DL communications; and determine a target base station timing advance value for handover to a target base station based at least in part on at least one of the following: the information identifying the timing offset, a timing difference between the target base station and a source base station associated with the UE, or a source base station timing advance value associated with the source base station. In some aspects, the non-transitory computer-readable medium may implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0013] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: units for receiving information identifying timing offsets associated with UL and DL communications of the apparatus; and units for determining a target base station timing advance value for handover to a target base station based at least in part on: the information identifying the timing offset, a timing difference between the target base station and a source base station associated with the UE, or a source base station timing advance value associated with the source base station. In some aspects, the apparatus may include units for performing or implementing any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0014] One innovative aspect of the subject matter described in this disclosure can be implemented in a method of wireless communication performed by a device of a UE. The method may include: transmitting at least one of: information identifying a timing difference between a target base station and a source base station associated with a handover, or an uplink reference signal; and receiving information identifying a timing advance value of the target base station, wherein the information identifying the timing advance value of the target base station is at least partially based on the timing difference between the target base station and the source base station or the uplink reference signal.

[0015] In some implementations, the handover is performed without a random access procedure. In some implementations, the information identifying the timing difference between the target base station and the source base station is a quantization of the timing difference between the target base station and the source base station. In some implementations, the information identifying the timing difference between the target base station and the source base station is provided in a radio resource management report. In some implementations, the uplink reference signal includes a sounding reference signal.

[0016] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for a UE (User Equipment) for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: transmit at least one of the following: information identifying a timing difference between a target base station and a source base station associated with a handover, or an uplink reference signal; and receive information identifying a timing advance value of the target base station, wherein the information identifying the timing advance value of the target base station is at least partially based on the timing difference between the target base station and the source base station or the uplink reference signal. In some aspects, the UE may perform or implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0017] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium may store one or more instructions for wireless communication. When executed by one or more processors of the UE, the one or more instructions may cause the one or more processors to: transmit at least one of the following: information identifying a timing difference between a target base station and a source base station associated with handover, or an uplink reference signal; and receive information identifying a timing advance value of the target base station, wherein the information identifying the timing advance value of the target base station is at least partially based on the timing difference between the target base station and the source base station or the uplink reference signal. In some aspects, the non-transitory computer-readable medium may implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0018] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include units for performing at least one of the following: transmitting information identifying a timing difference between a target base station and a source base station associated with a handover, or an uplink reference signal; and receiving information identifying a timing advance value of the target base station, wherein the information identifying the timing advance value of the target base station is at least partially based on the timing difference between the target base station and the source base station or the uplink reference signal. In some aspects, the apparatus may include units for performing or implementing any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0019] Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of wireless communication performed by a device of a target base station. The method may include: receiving from a UE at least one of: information identifying a timing difference between the device of the target base station and a source base station, or an uplink reference signal, wherein the device of the target base station and the source base station are associated with a handover of the UE; and providing to the UE information identifying a timing advance value of the target base station, wherein the timing advance value of the target base station is at least partially based on the information identifying the timing difference or the uplink reference signal.

[0020] In some implementations, the information identifying the timing difference between the device identifying the target base station and the source base station is a quantization of the timing difference between the device identifying the target base station and the source base station. In some implementations, the information identifying the timing difference between the device identifying the target base station and the source base station is received in a radio resource management report. In some implementations, the uplink reference signal includes a sounding reference signal. In some implementations, the method may include determining a timing advance value for the target base station based at least in part on the information identifying the timing difference between the device identifying the target base station and the source base station or the uplink reference signal.

[0021] In some implementations, the method may include selecting a technique for determining the timing advance value of the target base station based at least in part on the information or the uplink reference signal identifying the timing difference between the means identifying the target base station and the source base station. In some implementations, the technique is selected from a plurality of techniques including at least one of: determining the timing advance value of the target base station to zero, determining the timing advance value of the target base station based on a timing advance value of the source base station associated with the source base station, or determining the timing advance value of the target base station using the uplink reference signal.

[0022] In some implementations, the method may include: providing the source base station with the information identifying the timing advance value of the target base station to the UE. In some implementations, the handover is performed without performing a random access procedure.

[0023] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for a target base station for wireless communication. The BS may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: receive from a UE at least one of the following: information identifying a timing difference between the target base station and a source base station, or an uplink reference signal, wherein the target base station and the source base station are associated with handover; and provide to the UE information identifying a timing advance value of the target base station, wherein the timing advance value of the target base station is at least partially based on the information identifying the timing difference or the uplink reference signal. In some aspects, the target base station may perform or implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0024] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium may store one or more instructions for wireless communication. When executed by one or more processors of a target base station, the one or more instructions may cause the one or more processors to: receive from a UE at least one of the following: information identifying a timing difference between the target base station and a source base station, or an uplink reference signal, wherein the target base station and the source base station are associated with handover; and provide to the UE information identifying a target base station timing advance value associated with the target base station, wherein the target base station timing advance value is at least partially based on the information identifying the timing difference or the uplink reference signal. In some aspects, the non-transitory computer-readable medium may implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0025] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: unit for receiving from a UE at least one of: information identifying a timing difference between the apparatus and a source base station, or an uplink reference signal, wherein the apparatus and the source base station are associated with handover; and unit for providing the UE with information identifying a target base station timing advance value associated with the apparatus, wherein the target base station timing advance value is at least partially based on the information identifying the timing difference or the uplink reference signal. In some aspects, the apparatus may include unit for performing or implementing any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0026] Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of wireless communication performed by a device of a source base station. The method may include: determining a timing offset of a UE, wherein the timing offset is based at least in part on the difference between a downlink propagation delay and an uplink propagation delay of the UE; and transmitting information identifying the timing offset to the UE in conjunction with a handover of the UE from the device of the source base station to a target base station.

[0027] In some implementations, the timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the apparatus of the source base station, or the target base station. In some implementations, the information identifying the timing offset is transmitted in conjunction with a handover command. In some implementations, the granularity of the timing offset is based at least in part on the digital scheme or time slot length of the target base station.

[0028] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for a source base station for wireless communication. The source base station may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine a timing offset of a UE, wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE; and transmit information identifying the timing offset to the UE in conjunction with a handover of the UE from the apparatus of the source base station to a target base station. In some aspects, the source base station may perform or implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0029] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. When executed by one or more processors of a source base station, the one or more instructions can cause the one or more processors to: determine a timing offset of a UE, wherein the timing offset is based at least in part on the difference between the downlink propagation delay and the uplink propagation delay of the UE; and transmit information identifying the timing offset to the UE in conjunction with a handover of the UE from the source base station to the target base station. In some aspects, the non-transitory computer-readable medium can implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0030] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: unit for determining a timing offset of a UE, wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE; and unit for transmitting information identifying the timing offset to the UE in conjunction with a handover of the UE from the apparatus to a target base station. In some aspects, the apparatus may include unit for performing or implementing any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0031] Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of wireless communication performed by a device of a source base station. The method may include: receiving from a UE information identifying a timing difference between the device of the source base station and a target base station for a handover of the UE, wherein the timing difference between the device of the source base station and the target base station is associated with the handover of the UE; and transmitting information identifying a timing advance value of the target base station based at least in part on the information identifying the timing difference between the device of the source base station and the target base station.

[0032] In some implementations, the information identifying the timing difference between the device at the source base station and the target base station is a quantization of the timing difference. In some implementations, the information identifying the timing difference between the device at the source base station and the target base station is received in a radio resource management report. In some implementations, the information identifying the timing advance value of the target base station is transmitted in conjunction with a handover command.

[0033] In some implementations, the method may include: determining the target base station timing advance value based at least in part on the information identifying the timing difference between the means identifying the source base station and the target base station. In some implementations, the method may include: selecting a technique for determining the target base station timing advance value based at least in part on the information identifying the timing difference between the source base station and the target base station. In some implementations, the technique is selected from a plurality of techniques including at least one of: determining the target base station timing advance value as zero, determining the target base station timing advance value based on a source base station timing advance value associated with the source base station, or determining the target base station timing advance value using an uplink reference signal.

[0034] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for a source base station for wireless communication. The source base station may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: receive from a UE information identifying a timing difference between the source base station and a target base station, wherein the timing difference between the apparatus of the source base station and the target base station is associated with a handover of the UE; and transmit information identifying a timing advance value of the target base station based at least in part on the information identifying the timing difference between the apparatus of the source base station and the target base station. In some aspects, the source base station may perform or implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0035] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. When executed by one or more processors of a source base station, the one or more instructions can cause the one or more processors to: receive from a UE information identifying a timing difference between the source base station and a target base station, wherein the timing difference between the means of the source base station and the target base station is associated with a handover of the UE; and transmit information identifying a timing advance value of the target base station based at least in part on the information identifying the timing difference between the means of the source base station and the target base station. In some aspects, the non-transitory computer-readable medium can implement any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0036] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include units for performing: receiving from a UE information identifying a timing difference between the apparatus and a target base station, wherein the timing difference between the apparatus and the target base station is associated with a handover of the UE; and transmitting information identifying a timing advance value of the target base station based at least in part on the information identifying the timing difference between the apparatus and the target base station. In some aspects, the apparatus may include units for performing or implementing any one or more aspects of the aspects described above or elsewhere herein in conjunction with the methods.

[0037] In general, the aspects include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication equipment, and processing systems as fully described herein with reference to the accompanying drawings and as illustrated by the drawings.

[0038] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the specification, drawings, and claims. It should be noted that the relative dimensions in the following drawings may not be drawn to scale. Attached Figure Description

[0039] Figure 1 This is a block diagram that conceptually illustrates an example of a wireless network.

[0040] Figure 2 This is a block diagram that conceptually illustrates an example of communication between a base station (BS) and a user equipment (UE) in a wireless network.

[0041] Figure 3 This is a diagram illustrating an example of timing advance for the source and target base stations.

[0042] Figure 4 This is a diagram illustrating an example of timing advance determination in the absence of a random access channel (RACH).

[0043] Figure 5 This is a diagram illustrating another example of timing advance determination without RACH.

[0044] Figure 6 This is another example of timing advance determination without RACH.

[0045] Figure 7 This is another example of timing advance determination without RACH.

[0046] Figure 8 This is a diagram illustrating, for example, an example process performed by a user device.

[0047] Figure 9 This is a diagram illustrating, for example, an example process performed by a user device.

[0048] Figure 10 This is a diagram illustrating, for example, an example process performed by the target base station.

[0049] Figure 11 This is a diagram illustrating an example process, such as that performed by the source base station.

[0050] Figure 12 This is a diagram illustrating an example process, such as that performed by the source base station.

[0051] Similar reference numerals and naming conventions in the various figures indicate similar elements. Detailed Implementation

[0052] For the purpose of describing the innovative aspects of this disclosure, the following description relates to certain implementations. However, those skilled in the art will readily recognize that the teachings herein can be applied in a variety of different ways. Some examples in this disclosure are based on wireless and wired local area network (LAN) communications according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless standard, the IEEE 802.3 Ethernet standard, and the IEEE 1901 power line communication (PLC) standard. The described implementations can be implemented in any device, system, or network capable of transmitting and receiving radio frequency signals according to any wireless communication standard including any of the following: IEEE 802.11 standard, Bluetooth, etc. ® Standard, Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Global System for Mobile Communications (GSM), GSM or General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunking Radio (TETRA), Wideband-CDMA (W-CDMA), Evolved Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High-Speed ​​Packet Access (HSPA), High-Speed ​​Downlink Packet Access (HSDPA), High-Speed ​​Uplink Packet Access (HSUPA), Evolved High-Speed ​​Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals used for communication in wireless, cellular, or Internet of Things (IoT) networks (e.g., systems utilizing 3G, 4G, or 5G, or other implementations or technologies thereof).

[0053] Base stations (BS) and user equipment (UE) can be associated with timing advance or transmission timing adjustment. "Timing advance," "transmission timing adjustment," and "timing advance value" are used interchangeably herein. Timing advance can identify the timing offset between the UE and the base station, at least in part, based on propagation delay or other factors. For example, timing advance can identify a negative offset at the UE between the start of a received downlink subframe and a transmitted uplink subframe. This offset at the UE ensures that downlink and uplink subframes are synchronized at the base station.

[0054] Handover is the process of transferring a UE from one cell (called the source cell, where service can be provided by the source base station) to another cell (called the target cell, where service can be provided by the target base station). Some handovers are performed using a Random Access Channel (RACH) procedure (such as a contention-based RACH procedure or a contention-free RACH procedure), in which the UE and the target base station perform the RACH procedure. In a RACH-based handover, the target base station may determine the timing advance for the UE (relative to the target base station) based at least in part on the RACH procedure and may indicate the timing advance to the UE as part of the RACH procedure.

[0055] Some handovers can be performed without using the RACH procedure. This eliminates RACH-related delays in the handover, thus reducing mobility interruption time proportionally to the length of the RACH procedure (in some cases, such as approximately 10–12 milliseconds (ms)). It may be beneficial to use non-RACH-based techniques to determine the target base station timing advance value between the UE and the target base station, since the target base station may not be able to use the RACH procedure to determine the timing advance. In some deployments, RACH-free handovers have been restricted to synchronous deployments or have been subject to various limitations (e.g., setting the target base station timing advance equal to the source cell timing advance, or setting the target base station timing advance to zero, etc.).

[0056] Some of the techniques and apparatus described herein provide methods for determining a target base station timing advance value between a UE and a target base station, for example, in conjunction with a RACH-free handover procedure. For instance, at least one of the UE, the target base station, or the source base station can determine the target base station timing advance value without using a RACH procedure. In some aspects, the UE can determine the target base station timing advance based at least in part on the timing difference between the target base station and the source base station and at least in part on timing offsets associated with the UE's uplink and downlink. In some aspects, the target base station can use the UE's uplink reference signal to determine the timing advance. In some aspects, the UE can report the timing difference between the target base station and the source base station, and the source cell can determine the timing advance based at least in part on this timing difference. In some aspects, the UE can report the timing difference between the target base station and the source base station, and the base station (such as the source base station or the target base station) can determine a technique for timing advance based at least in part on this timing difference. These techniques can be implemented in various deployments, regardless of whether the target base station timing advance is equal to or zero compared to the source base station timing advance.

[0057] Specific implementations of the subject matter described in this disclosure can achieve one or more of the following potential advantages. In some implementations, UE mobility is improved. Furthermore, handover-related interruptions can be reduced by decreasing handover latency. Additionally, support for RACH-less handovers can be improved for base stations that do not share the same timing advance value and for base stations associated with non-zero timing advance values ​​(such as base stations providing cell sizes).

[0058] Figure 1 This is a conceptual diagram illustrating an example of a wireless network 100. Wireless network 100 can be an LTE network or some other wireless network (e.g., a 5G or NR network). Wireless network 100 can include multiple BS 110s (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with a user equipment (UE) and can also be referred to as a base station, NR BS, Node B, gNB, 5G Node B (NB), access point, or Transmit / Receive Point (TRP). Each BS can provide communication coverage for a specific geographic area. In 3GPP, the term "cell" can refer to the coverage area of ​​a BS, the BS subsystem serving that coverage area, or a combination thereof, depending on the context in which the term is used.

[0059] A BS can provide communication coverage for macrocells, picocells, femtocells, another type of cell, or a combination thereof. A macrocell can cover a relatively large geographic area (e.g., a radius of several kilometers) and can allow unrestricted access by UEs with service subscriptions. A picocell can cover a relatively small geographic area and can allow unrestricted access by UEs with service subscriptions. A femtocell can cover a relatively small geographic area (e.g., a residential area) and can allow restricted access by UEs associated with that femtocell (e.g., UEs in a Closed User Group (CSG)). A BS used for macrocells can be referred to as a macro BS. A BS used for picocells can be referred to as a pico BS. A BS used for femtocells can be referred to as a femtocell BS or a home BS. It can be expected that the timing advance value used for the BS increases with the size of the cell provided by the BS. Figure 1 In the examples shown, BS 110a can be a macro BS for macro cell 102a, BS 110b can be a pico BS for pico cell 102b, and BS 110c can be a femto BS for femto cell 102c. A BS can support one or more (e.g., three) cells. The terms “eNB,” “base station,” “NRBS,” “gNB,” “TRP,” “AP,” “Node B,” “5G NB,” and “cell” are used interchangeably herein.

[0060] In some examples, the cell may not be stationary, and the geographical area of ​​the cell may move depending on the location of the mobile BS. In some examples, BSs may interconnect with each other and with one or more other BSs or network nodes (not shown) in the wireless network 100 via various types of backhaul interfaces (e.g., direct physical connections using any suitable transport network, virtual networks, or combinations thereof).

[0061] The wireless network 100 may also include a relay station. A relay station is an entity that can receive data transmissions from an upstream station (e.g., a BS or a UE) and transmit the data transmissions to a downstream station (e.g., a UE or a BS). A relay station can also be a UE capable of relaying transmissions for other UEs. Figure 1 In the example shown, relay station 110d can communicate with macro BS 110a and UE 120d to facilitate communication between BS 110a and UE 120d. A relay station can also be referred to as a relay BS, relay base station, or repeater.

[0062] Wireless network 100 can be a heterogeneous network comprising different types of Base Stations (BSs) (e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs can have different transmit power levels, different coverage areas, and different effects on interference in wireless network 100. For example, macro BSs can have high transmit power levels (e.g., 5 to 40 watts), while pico BSs, femto BSs, and relay BSs can have lower transmit power levels (e.g., 0.1 to 2 watts).

[0063] Network controller 130 can be coupled to a group of base stations (BSs) and can provide coordination and control for these BSs. Network controller 130 can communicate with the BSs via backhaul. BSs can also communicate with each other directly or indirectly, for example, via wireless or wired backhaul.

[0064] UE 120 (e.g., 120a, 120b, 120c) may be distributed throughout the wireless network 100, and each UE may be stationary or mobile. UE may also be referred to as an access terminal, terminal, mobile station, user unit, station, or similar terms. UE may be a cellular phone (e.g., a smartphone), personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet device, camera, gaming device, netbook, smartbook, ultrabook, medical device or apparatus, biometric sensor / device, wearable device (smartwatch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), entertainment device (e.g., music or video device, or satellite radio unit, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, GPS device, or any other suitable device configured to communicate via wireless or wired media.

[0065] Some UEs can be considered Machine-Type Communication (MTC) or Evolved or Enhanced Machine-Type Communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, or similar examples, which can communicate with a base station, another device (e.g., a remote device), or some other entity. Wireless nodes can provide connectivity to or to a network (e.g., a wide area network such as the Internet or cellular networks) via wired or wireless communication links, for example. Some UEs can be considered Internet of Things (IoT) devices, or can be implemented as NB-IoT (Narrowband Internet of Things) devices. Some UEs can be considered Customer Premises Equipment (CPE). UE 120 can be included within a housing that houses the components of UE 120, such as processor components, memory components, similar components, or combinations thereof.

[0066] Typically, any number of wireless networks can be deployed in a given geographical area. Each wireless network can support a specific RAT and can operate on one or more frequencies. A RAT can also be referred to as a radio technology, air interface, or wireless communication technology. A frequency can also be referred to as a carrier, channel, or frequency channel, etc. Each frequency can support a single RAT in a given geographical area to avoid interference between wireless networks using different RATs. In some cases, NR or 5G RAT networks can be deployed.

[0067] In some examples, access to an air interface can be scheduled, where a scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and apparatuses within the scheduling entity's service area or cell. In this disclosure, as further discussed below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, the subordinate entities use the resources allocated by the scheduling entity.

[0068] A base station is not the only entity that can be used as a scheduling entity. That is, in some examples, a UE can act as a scheduling entity, scheduling resources for one or more subordinate entities (e.g., one or more other UEs). In some examples, a UE acts as a scheduling body, and other UEs utilize the resources scheduled by that UE for wireless communication. A UE can act as a scheduling entity in a peer-to-peer (P2P) network, in a mesh network, or another type of network. In the mesh network example, in addition to communicating with a scheduling entity, UEs can optionally communicate directly with each other.

[0069] Therefore, in a wireless communication network with scheduled access to time-frequency resources and with cellular, P2P, and mesh configurations, the scheduling entity and one or more subordinate entities can communicate using the scheduled resources.

[0070] In some respects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using base station 110 as an intermediary for communication with each other). For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, or similar protocols), mesh networks, or similar networks, or combinations thereof. In this case, UE 120 may perform scheduling operations, resource selection operations, and other operations described herein as being performed by base station 110.

[0071] Figure 2 This is a block diagram conceptually illustrating example 200 of communication between base station 110 and UE 120. In some aspects, base station 110 and UE 120 can be respectively Figure 1 One of the base stations and one of the UEs in the wireless network 100. The base station 110 may be equipped with T antennas 234a to 234t, and the UE 120 may be equipped with R antennas 252a to 252r, wherein generally, T ≥ 1 and R ≥ 1.

[0072] At base station 110, transmitting processor 220 can receive data for one or more UEs from data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQI) received from each UE, process (e.g., code and modulate) the data for each UE based at least in part on the MCS selected for each UE, and provide data symbols for all UEs. Transmitting processor 220 can also process system information (e.g., semi-static resource allocation information (SRPI)) and control information (e.g., CQI requests, grants, and upper-layer signaling), and provide overhead symbols and control symbols. Transmitting processor 220 can also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signal (PSS) and secondary synchronization signal (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., precoding) (if applicable) on data symbols, control symbols, overhead symbols, or reference symbols, and can provide T output symbol streams to T modulators (MODs) 232a to 232t. Each modulator 232 can (e.g., for OFDM) process its corresponding output symbol stream to obtain an output sample stream. Each modulator 232 can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a to 232t can be transmitted via T antennas 234a to 234t respectively. According to the aspects described in more detail below, position coding can be used to generate synchronization signals to transmit additional information.

[0073] At UE 120, antennas 252a to 252r can receive downlink signals from base station 110 or other base stations and can provide the received signals to demodulators (DEMODs) 254a to 254r respectively. Each demodulator 254 can adjust (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain an input sample. Each demodulator 254 can further process the input sample (e.g., for OFDM) to obtain a received symbol. MIMO detector 256 can obtain the received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols (if applicable), and provide the detected symbols. Receiver processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to data sink 260, and provide decoded control information and system information to controller or processor (controller / processor) 280. The channel processor can determine the Reference Signal Received Power (RSRP), Received Signal Strength Indicator (RSSI), Reference Signal Received Quality (RSRQ), Channel Quality Indicator (CQI), or other measurements. In some aspects, one or more components of the UE 120 may be included in the housing.

[0074] On the uplink, at UE 120, the transmitting processor 264 can receive and process data from data source 262 and control information from controller / processor 280 (e.g., for reporting including RSRP, RSSI, RSRQ, or CQI). The transmitting processor 264 can also generate reference symbols for one or more reference signals. Symbols from the transmitting processor 264 can be pre-encoded (if applicable) by the TX MIMO processor 266, further processed by modulators 254a to 254r (e.g., for DFT-s-OFDM or CP-OFDM), and transmitted to base station 110. At base station 110, uplink signals from UE 120 and other UEs can be received by antenna 234, processed by demodulator 232, detected by MIMO detector 236 (if applicable), and further processed by receiving processor 238 to obtain decoded data and control information transmitted by UE 120. The receiving processor 238 can provide decoded data to the data sink 239 and decoded control information to the controller or processor (controller / processor) 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller or processor (controller / processor) 290, and a memory 292.

[0075] In some implementations, the controller / processor 240 may be a component of a processing system. A processing system can generally refer to a system or a series of machines or components that receive input and process the input to produce a set of outputs (which can be passed to other systems or components of, for example, UE 120). For example, the processing system of UE 120 may refer to a system that includes various other components or sub-components of UE 120.

[0076] The processing system of UE 120 can interface with other components of UE 120 and can process information (such as inputs or signals) received from other components, output information to other components, and so on. For example, the chip or modem of UE 120 may include a processing system, a first interface for receiving or acquiring information, and a second interface for outputting, transmitting, or providing information. In some cases, the first interface may refer to the interface between the processing system of the chip or modem and the receiver, allowing UE 120 to receive information or signal input, and that information can be transmitted to the processing system. In some cases, the second interface may refer to the interface between the processing system of the chip or modem and the transmitter, allowing UE 120 to transmit information output from the chip or modem. Those skilled in the art will readily recognize that the second interface can also acquire or receive information or signal input, and the first interface can also output, transmit, or provide information.

[0077] In some implementations, the controller / processor 280 may be a component of a processing system. A processing system can generally refer to a system or a series of machines or components that receive and process inputs to produce a set of outputs (which can be passed to other systems or components of, for example, BS 110). For example, the processing system of BS 110 can refer to a system that includes various other components or sub-components of BS 110.

[0078] The processing system of BS 110 can interface with other components of BS 110 and can process information (such as inputs or signals) received from other components, output information to other components, and so on. For example, the chip or modem of BS 110 may include a processing system, a first interface for receiving or acquiring information, and a second interface for outputting, transmitting, or providing information. In some cases, the first interface may refer to the interface between the processing system of the chip or modem and the receiver, allowing BS 110 to receive information or signal input, and that information can be transmitted to the processing system. In some cases, the second interface may refer to the interface between the processing system of the chip or modem and the transmitter, allowing BS 110 to transmit information output from the chip or modem. Those skilled in the art will readily recognize that the second interface can also acquire or receive information or signal input, and the first interface can also output, transmit, or provide information.

[0079] The controller / processor 240 of base station 110, the controller / processor 280 of UE 120 and / or Figure 2 Any other component may perform one or more techniques associated with advance determination of RACH-free timing, as described in more detail elsewhere herein. For example, the controller / processor 240 of base station 110, the controller / processor 280 of UE 120, or... Figure 2 Any other component (or combination of components) can execute or direct, for example... Figures 8 to 12 The operation of processes 800 to 1200 and / or other processes as described herein. Memory 242 and 282 may store data and program code for base station 110 and UE 120, respectively. Scheduler 246 may schedule data transmission by the UE on the downlink, uplink, or a combination thereof.

[0080] The stored program code, when executed by the controller / processor 280 or other processors and modules at the UE 120, can cause the UE 120 to perform actions related to... Figure 8 The process 800 Figure 9 The process 900 or other processes described herein. The stored program code, when executed by the controller / processor 240 or other processors and modules at the base station 110, can cause the base station 110 to perform operations related to... Figure 10 Process 1000 Figure 11 Process 1100 Figure 12 The process 1200 or other processes described herein. Scheduler 246 can schedule the UE to transmit data on the downlink, uplink, or a combination thereof.

[0081] In some aspects, UE 120 may include: a unit for receiving information identifying a timing offset associated with UL and DL communications of the UE; a unit for determining a target base station timing advance value for handover to a target base station based at least in part on at least one of the following: information identifying the timing offset, a timing difference between the target base station and the source base station associated with the UE, or a source base station timing advance value associated with the source base station; a unit for determining the timing difference between the target base station and the source base station based at least in part on reference signaling received from the source base station and the target base station; a unit for transmitting at least one of the following: information identifying the timing difference between the target base station and the source base station associated with handover, or an uplink reference signal; a unit for receiving information identifying the target base station timing advance value, wherein the information identifying the target base station timing advance value is based at least in part on the timing difference between the target base station and the source base station or the uplink reference signal; or a combination thereof. In some aspects, such a unit may include a combination of Figure 2One or more components of the UE 120 described (such as devices of the UE 120).

[0082] In some aspects, base station 110 may include: a unit for receiving from a UE at least one of the following: information identifying a timing difference between a target base station and a source base station, or an uplink reference signal, wherein the target base station and the source base station are associated with a handover of the UE; a unit for providing the UE with information identifying a timing advance value of the target base station, wherein the timing advance value of the target base station is at least partially based on the information identifying the timing difference or the uplink reference signal; a unit for determining the timing advance value of the target base station at least partially based on the information identifying the timing difference between the means identifying the target base station and the source base station or the uplink reference signal; a unit for selecting a technique for determining the timing advance value of the target base station at least partially based on the information identifying the timing difference between the means identifying the target base station and the source base station or the uplink reference signal; a unit for determining the timing advance value of the target base station as zero; a unit for determining the timing advance value of the target base station based on the timing advance value of the source base station associated with the source base station; a unit for determining the timing advance value of the target base station using the uplink reference signal; and a unit for using the uplink reference signal. The system comprises: a unit for providing information identifying a target base station timing advance value to a source base station for transmission to a UE; a unit for determining a timing offset of a user equipment (UE), wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE; a unit for transmitting information identifying the timing offset t to the UE in conjunction with a handover of the UE from a device of the source base station to the target base station; a unit for receiving from the UE information identifying a timing difference between a device of the source base station and the target base station, wherein the timing difference between the device of the source base station and the target base station is associated with the handover of the UE; a unit for transmitting information identifying a target base station timing advance value based at least partially on information identifying the timing difference between the device of the source base station and the target base station; a unit for determining a target base station timing advance value based at least partially on information identifying the timing difference between the device of the source base station and the target base station; a unit for selecting a technique for determining the target base station timing advance value based at least partially on information identifying the timing difference between the device of the source base station and the target base station; or a combination thereof. In some aspects, such a unit may include a combination of... Figure 2 One or more components of the described base station 110, such as the apparatus of the base station 110.

[0083] Although Figure 2The boxes in the diagram are shown as different components, but the functions described above with respect to these boxes can be implemented in a single hardware, software, or combined component, or in various combinations of components. For example, the functions described with respect to transmit processor 264, receive processor 258, TX MIMO processor 266, or another processor can be performed by controller / processor 280 or under the control of controller / processor 280.

[0084] Figure 3 This is a diagram illustrating example 300 of timing advance for the source and target base stations. (As shown in...) Figure 3 As shown by reference numerals 310 and 320 in the accompanying drawings, the source BS 110-1 and the target BS 110-2 can provide corresponding reference signals to the UE 120. For example, the corresponding reference signals may include a demodulation reference signal, a phase tracking reference signal, a channel state information reference signal, or another reference signal. The UE 120 can use the corresponding reference signals to identify the timing difference between the source BS 110-1 and the target BS 110-2.

[0085] The corresponding subframe timings of source BS 110-1 and target BS 110-2 are indicated by reference numerals 330 and 340. These subframe timings are provided as examples, and the techniques and apparatus described herein can be used to identify timing differences based at least in part on any set of subframe timings, such as those different from those shown.

[0086] UE 120 can determine the timing difference 350 between source BS 110-1 and target BS 110-2, at least in part, based on the corresponding reference signals. For example, UE 120 can determine the reference signal timing difference (RSTD) value between source BS 110-1 and target BS 110-2 by identifying the start times of the subframes of source BS 110-1 and target BS 110-2, at least in part, based on the corresponding reference signals. In some aspects, UE 120 can determine the timing difference 350 as the difference between the corresponding start times of the subframes of source BS 110-1 and target BS 110-2. For example, RSTD It can be defined as T target – T source ,in, T target It is the start time when UE 120 receives a specific subframe from target BS 110-2, and T sourceThis is the start time at which UE 120 receives the subframe from source BS 110-1 that is temporally closest to a specific subframe. At least one of UE 120, source BS 110-1, or target BS 110-2 can use a timing difference of 350 to determine the timing offset between UE 120 and target BS 110-2, as described in more detail elsewhere in this document.

[0087] Figure 4 This is a diagram illustrating example 400 with pre-determined timing for a random access channel (RACH). As shown, example 400 includes UE 120, source BS 110-1, and target BS 110-2. Figure 4 As shown, and as combined Figure 3 In more detail, source BS 110-1 and target BS 110-2 can provide corresponding reference signals to UE 120. As shown by reference numeral 410 in the attached figures, and in conjunction with... Figure 3 In more detail, UE 120 can use the corresponding reference signals of source BS 110-1 and target BS 110-2 to determine the timing difference (such as timing difference 350 or RSTD) between source BS 110-1 and target BS 110-2.

[0088] As shown in Figure 420, UE 120 can receive information identifying timing offsets from source BS 110-1. Timing offsets can identify the difference between the uplink and downlink timings of UE 120. For example, timing offsets can identify timing discrepancies between the uplink and downlink due to: differences in propagation delays (because the uplink and downlink may propagate via different paths), transition time from transmit to receive (and vice versa), hardware constraints of UE 120 or BS110, propagation delays between transmit and receive, or similar causes of timing discrepancies. Variables may be used in this document. This is used to indicate timing offset. In some aspects, the source BS 110-1 can provide information identifying timing offset in handover commands such as Radio Resource Control (RRC) connection reconfiguration messages.

[0089] In some respects, the granularity of the timing offset can be at least partially based on the digital scheme of the target BS 110-2 (such as the digital scheme for the Physical Uplink Shared Channel (PUSCH) of the target BS 110-2 or the digital scheme for a portion of the uplink bandwidth of the target BS 110-2). For example, the timing offset can use a finer-grained or more precise value for a digital scheme associated with a shorter time slot length compared to a digital scheme associated with a longer time slot length. Therefore, the source BS 110-1 can save signaling resources that would otherwise be used to signal unnecessarily precise timing offsets.

[0090] As shown by reference numeral 430 in the attached figure, UE 120 can determine the target base station timing advance value associated with the target BS 110-2 using a timing offset, a timing difference, and a source base station timing advance value associated with the source BS 110-1. For example, UE 120 can determine the timing advance value for the source BS 110-1 based at least in part on communication with the source BS 110-1 or at least in part on receiving information identifying the timing advance value for the source BS 110-1. The timing advance value for the source BS 110-1 can be represented as... TA source In some aspects, UE 120 can use the timing advance value for source BS 110-1. TA target Determined as .

[0091] As shown by reference numeral 440 in the attached figure, UE 120 can perform a handover to target BS 110-2 based at least in part on the timing advance of target BS 110-2. For example, UE 120 can perform a handover without performing a RACH procedure for target BS 110-2. In this way, UE 120 can determine the timing advance value for target BS 110-2 based at least in part on the timing advance value for source BS 110-1, the timing difference between source BS 110-1 and target BS 110-2, and the timing offset of UE 120. Therefore, UE 120 can determine the timing advance value for target BS 110-2 without receiving explicit signaling identifying the timing advance value for target BS 110-2 and without performing a RACH procedure as part of the handover, thereby reducing handover-related latency and user interruption.

[0092] Figure 5 This is a diagram illustrating another example 500 of timing advance determination without RACH. Example 500 is an example in which the target BS110-2 determines the target BS timing advance at least in part based on the uplink reference signal of UE 120.

[0093] As in Figure 5 As shown by reference numeral 510 in the accompanying drawing, UE 120 can provide an uplink (UL) reference signal to the target BS 110-2. For example, the uplink reference signal may include a sounding reference signal (SRS) (such as an SRS associated with multiple-input multiple-output (MIMO) operation), a reference signal for positioning purposes, or another reference signal.

[0094] As shown by reference numeral 520 in the attached figure, target BS 110-2 can determine target BS timing advance at least in part based on the uplink reference signal. For example, target BS 110-2 can determine the time when the uplink reference signal is transmitted, and can determine the difference between the time when the uplink reference signal is transmitted and the time when target BS 110-2 receives the uplink reference signal. Therefore, target BS 110-2 can determine target BS timing advance without knowing the source BS timing advance and without performing a RACH procedure with UE 120, thereby reducing handover latency.

[0095] As shown by reference numeral 530, source BS 110-1 can provide UE 120 with information indicating that the target BS timing is advanced. For example, target BS 110-2 can provide source BS 110-1 with information indicating that the target BS timing is advanced, and source BS 110-1 can provide this information to UE 120. In some aspects, the information indicating that the target BS timing is advanced can be provided in the handover command. In some aspects, target BS 110-2 can provide source BS 110-1 with information indicating that the target BS timing is advanced. As shown by reference numeral 540, UE 120 can perform a handover to the target BS at least in part based on the advanced target BS timing.

[0096] Figure 6 This is a diagram illustrating another example 600 of timing advance determination without RACH. In example 600, the source BS 110-1 determines the timing advance of the target BS. As in... Figure 6 As shown by reference numeral 610, UE 120 can use the corresponding reference signals of source BS 110-1 and target BS 110-2 to determine the timing difference between source BS 110-1 and target BS 110-2. As shown by reference numeral 620, UE 120 can provide, for example, information identifying the timing difference to source BS 110-1. In some aspects, UE 120 can provide quantization of the timing difference. For example, UE 120 can provide bit-bit quantization or different types of quantization of the timing difference, thereby saving signaling resources that would otherwise be used to provide information identifying the timing difference at the sampling time granularity or another granularity more complex than quantization. In some aspects, UE 120 can provide information identifying the timing difference in a Radio Resource Management (RRM) report.

[0097] As shown by reference numeral 630 in the attached figure, the source BS 110-1 can determine the target BS timing advance using a timing difference and the source BS timing advance used for the UE 120. In some aspects, the source BS 110-1 can be based at least in part on a timing offset ( This method determines the target BS timing advance, which improves the accuracy of the target BS timing advance compared to the source BS 110-1 without considering timing offset. In this case, the source BS 110-1 can determine the target BS timing advance as... In some respects, the source BS 110-1 can determine the target BS timing advance without using timing offset, which simplifies the determination of the target BS timing advance.

[0098] As shown by reference numeral 640 in the attached figure, source BS 110-1 can provide UE 120 with information identifying the timing advance of the target BS. For example, source BS 110-1 can provide information identifying the timing advance of the target BS in the handover command, as described in more detail elsewhere herein. As further shown, UE 120 can perform a handover to target BS 110-2 based at least in part on the target BS timing advance value, thereby reducing handover latency compared to handovers using the RACH procedure to determine the target BS timing advance value.

[0099] Figure 7 This is a diagram illustrating another example 700 of timing advance determination without RACH. In example 700, BS 110 selects the technique for determining the timing advance of the target BS based at least in part on the timing difference between the source BS 110-1 and the target BS 110-2. In some aspects, at least some of the operations described in example 700 can be performed by the source BS 110-1 (e.g., Figure 7 As shown). In some aspects, at least some of the operations described in Example 700 can be performed by target BS 110-2 (as shown). Figure 7 (Not shown in the image).

[0100] As in Figure 7 As shown by reference numeral 710 in the accompanying drawings, UE 120 can provide source BS 110-1 with information identifying the timing difference. For example, and as shown, UE 120 can determine the timing difference at least in part based on reference signals from source BS 110-1 and target BS 110-2. In some aspects, UE 120 can provide quantization of the timing difference to source BS 110-1. In some aspects, UE 120 can provide target BS 110-2 with information identifying the timing difference.

[0101] As shown by reference numeral 720 in the attached figure, the source BS 110-1 (or target BS 110-2) can select a technique for determining the timing advance of the target BS based at least in part on a timing difference. For example, the technique may include: determining the timing advance of the target BS to be zero, determining the timing advance of the target BS based on a source base station timing advance value used for the source BS 110-1, or determining the timing advance of the target BS using an uplink reference signal (as described in more detail in conjunction with Example 400). In some aspects, the source BS 110-1 can select a technique based at least in part on a timing difference. For example, the source BS 110-1 can determine that the timing difference is between 0 and... X1 First range X1 arrive X2 The second range is still greater than X2 Within the third range. When the timing difference is within the first range, the source BS 110-1 can determine to determine the target BS timing advance based on the timing advance value used by the source BS 110-1. When the timing difference is within the second range, the source BS 110-1 can determine to set the target BS timing advance to zero. When the timing difference is within the third range, the source BS 110-1 can determine to use the uplink reference signal to determine the target BS timing advance.

[0102] As shown by reference numeral 730 in the attached figure, the source BS 110-1 (or the target BS 110-2) can provide information identifying the timing advance of the target BS or the technique to be used to determine the timing advance of the target BS. Therefore, the UE 120 can determine the timing advance of the target BS to be zero, or it can determine the timing advance of the target BS to be equal to the timing advance of the source BS. Alternatively, the UE 120 can transmit an uplink reference signal to be used by the target BS 110-2 to determine the timing advance of the target BS. Therefore, the BS 110 (such as the source BS 110-1 or the target BS 110-2) can determine the technique to be used at least in part based on the timing difference between the source BS 110-1 and the target BS 110-2, thereby improving the flexibility of timing advance determination and saving resources that might be used to perform timing advance determination based on the uplink reference signal.

[0103] Figure 8 This is a diagram illustrating, for example, an example procedure 800 performed by a UE. Procedure 800 illustrates an example in which the UE (e.g., UE120) performs a timing advance determination without RACH. In some aspects, procedure 800 may be performed by a device of the UE, which may include one or more interfaces and processing systems, as described elsewhere herein.

[0104] like Figure 8As shown, in some aspects, process 800 may include receiving information identifying timing offsets associated with uplink and downlink communication of the UE (block 810). For example, the UE (e.g., using antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, or controller / processor 280) may receive information identifying timing offsets associated with uplink and downlink communication of the UE. In some aspects, timing offset may be referred to herein as... .

[0105] like Figure 8 As shown, in some aspects, process 800 may include: determining a target base station timing advance value for handover to a target base station based at least in part on at least one of the following: information identifying a timing offset, a timing difference between the target base station and the source base station associated with the UE, or a source base station timing advance value associated with the source base station (block 820). For example, the UE (e.g., using controller / processor 280) may determine the target base station timing advance associated with handover to the target base station. The UE may determine the timing advance based at least in part on at least one of the following: information identifying a timing offset, a timing difference between the target base station and the source base station associated with the UE, or a source base station timing advance value associated with the source base station.

[0106] Process 800 may include additional aspects, such as any single aspect or any combination of aspects described below or elsewhere in conjunction with one or more other processes described herein.

[0107] In the first aspect, the timing difference is based at least in part on the timing difference of a reference signal between the target base station and the source base station. In the second aspect, either alone or in combination with the first aspect, the UE may determine the timing difference between the target base station and the source base station based at least in part on reference signaling received from the source base station and the target base station.

[0108] In the third aspect, either alone or in combination with one or more of the first and second aspects, the timing offset is based at least in part on the transition time (e.g., transmit-to-receive transition time, etc.), the propagation delay between transmit and receive, or the hardware configuration of at least one of the UE, the source base station, or the target base station. In the fourth aspect, either alone or in combination with one or more of the first to third aspects, the granularity of the timing offset is based at least in part on at least one of the target base station's digital scheme or time slot length. In the fifth aspect, either alone or in combination with one or more of the first to fourth aspects, the information identifying the timing offset is received in the handover command. In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the target base station timing advance value is determined without performing a random access procedure (RACH procedure). In the seventh aspect, either alone or in combination with one or more of the first to sixth aspects, the target base station timing advance value is determined at least in part based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

[0109] Although Figure 8 An example box of process 800 is shown, but in some aspects, process 800 may include... Figure 8 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 800 may be executed in parallel.

[0110] Figure 9 This is a diagram illustrating, for example, an example procedure 900 performed by a UE. Procedure 900 illustrates an example in which the UE (e.g., UE120) performs a timing advance determination without RACH. In some aspects, procedure 900 may be performed by a device of the UE, which may include one or more interfaces and processing systems, as described elsewhere herein.

[0111] like Figure 9 As shown, in some aspects, process 900 may include transmitting at least one of the following: information identifying a timing difference for handover between the target base station and the source base station, or an uplink reference signal (block 910). For example, the UE (e.g., using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may transmit information identifying a timing difference for handover between the target base station and the source base station (e.g., from the source base station to the target base station). In some aspects, the UE may transmit an uplink reference signal.

[0112] like Figure 9As shown, in some aspects, process 900 may include: receiving information identifying a timing advance value of a target base station, wherein the information identifying the timing advance value of the target base station is at least partially based on a timing difference or uplink reference signal between the target base station and the source base station (block 920). For example, a UE (e.g., using antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, or controller / processor 280) may receive the information identifying the timing advance value of the target base station. The information identifying the timing advance value of the target base station may be at least partially based on a timing difference or uplink reference signal between the target base station and the source base station.

[0113] Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below or elsewhere in conjunction with one or more other processes described herein.

[0114] In the first aspect, the handover is performed without a random access procedure. In the second aspect, alone or in combination with the first aspect, the information identifying the timing difference between the target base station and the source base station is a quantification of the timing difference between the target base station and the source base station. In the third aspect, alone or in combination with one or more aspects of the first and second aspects, the information identifying the timing difference between the target base station and the source base station is provided in the radio resource management report. In the fourth aspect, alone or in combination with one or more aspects of the first to third aspects, the uplink reference signal includes a sounding reference signal.

[0115] Although Figure 9 An example box of process 900 is shown, but in some aspects, process 900 may include... Figure 9 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 900 may be executed in parallel.

[0116] Figure 10 This is a diagram illustrating, for example, an example procedure 1000 performed by a target base station. Procedure 1000 illustrates an example in which the target base station (e.g., BS 110) performs a timing advance base station without RACH. In some aspects, procedure 1000 may be performed by a device of the UE, which may include one or more interfaces and processing systems, as described elsewhere herein.

[0117] like Figure 10As shown, in some aspects, process 1000 may include receiving from the UE at least one of the following: information identifying a timing difference between means of the target base station and the source base station, or an uplink reference signal, wherein the means of the target base station and the source base station are associated with a handover of the UE (block 1010). For example, the target base station (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, or controller / processor 240) may receive from the UE (such as UE 120) information identifying a timing difference between means of the target base station and the source base station, or an uplink reference signal. The means of the target base station and the source base station may be associated with a handover of the UE (e.g., from the source base station to the target base station).

[0118] like Figure 10 As shown, in some aspects, process 1000 may include: providing the UE with information identifying a target base station timing advance value for a target base station, wherein the target base station timing advance is at least partially based on information identifying a timing difference or an uplink reference signal (block 1020). For example, the target base station (e.g., using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may provide the UE with information identifying the target base station timing advance value. The target base station timing advance value may be at least partially based on information identifying a timing difference between the target base station and the source base station or an uplink reference signal.

[0119] Process 1000 may include additional aspects, such as any single aspect or any combination of aspects described below or elsewhere in conjunction with one or more other processes.

[0120] In the first aspect, the information identifying the timing difference between the means of identifying the target base station and the source base station is a quantification of the timing difference between the means of identifying the target base station and the source base station. In the second aspect, alone or in combination with the first aspect, the information identifying the timing difference between the means of identifying the target base station and the source base station is received in a radio resource management report. In the third aspect, alone or in combination with one or more aspects of the first and second aspects, the uplink reference signal includes a sounding reference signal. In the fourth aspect, alone or in combination with one or more aspects of the first to third aspects, the target base station can determine a target base station timing advance value based at least in part on the information identifying the timing difference between the means of identifying the target base station and the source base station or the uplink reference signal. In the fifth aspect, alone or in combination with one or more aspects of the first to fourth aspects, the target base station can select a technique for determining the target base station timing advance value based at least in part on the information identifying the timing difference between the means of identifying the target base station and the source base station or the uplink reference signal. In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the technique is selected from a plurality of techniques including at least one of the following: determining the target base station timing advance value to zero, determining the target base station timing advance value based on a source base station timing advance value associated with a source base station, or determining the target base station timing advance value using an uplink reference signal. In the seventh aspect, either alone or in combination with one or more of the first to sixth aspects, the target base station may provide information identifying the target base station timing advance value to the source base station for transmission to the UE. In the eighth aspect, either alone or in combination with one or more of the first to seventh aspects, the handover is performed without performing a random access procedure.

[0121] Although Figure 10 An example box of process 1000 is shown, but in some aspects, process 1000 may include... Figure 10 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 1000 may be executed in parallel.

[0122] Figure 11 This is a diagram illustrating, for example, an example process 1100 performed by a source base station. Process 1100 illustrates an example in which the source base station (e.g., BS 110) performs a timing advance determination without RACH. In some aspects, process 1100 may be performed by means of a base station, which may include one or more interfaces and processing systems, as described elsewhere herein.

[0123] like Figure 11As shown, in some aspects, process 1100 may include: determining a timing offset of the UE, wherein the timing offset is based at least in part on the difference between the downlink propagation delay and the uplink propagation delay of the UE (box 1110). For example, a source base station (e.g., using controller / processor 240) may determine the timing offset of the UE. The timing offset may be based at least in part on the difference between the downlink propagation delay and the uplink propagation delay of the UE.

[0124] like Figure 11 As shown, in some aspects, process 1100 may include sending information identifying a timing offset to the UE in conjunction with a handover from the source base station's apparatus to the target base station (block 1120). For example, the source base station (e.g., using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may send the information identifying the timing offset to the UE in conjunction with a handover from the source base station's apparatus to the target base station.

[0125] Process 1100 may include additional aspects, such as any single aspect or any combination of aspects described below or in conjunction with one or more other processes described elsewhere herein.

[0126] In the first aspect, the timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station. In the second aspect, either alone or in combination with the first aspect, information identifying the timing offset is transmitted in conjunction with a handover command. In the third aspect, either alone or in combination with one or more of the first and second aspects, the granularity of the timing offset is based at least in part on the target base station's digital scheme or time slot length.

[0127] Although Figure 11 An example box of process 1100 is shown, but in some aspects, process 1100 may include... Figure 11 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 1100 may be executed in parallel.

[0128] Figure 12 This is a diagram illustrating an example process 1200 performed, for example, by a source base station. Process 1200 illustrates an example in which the source base station (e.g., BS 110) performs a timing advance determination without RACH. In some aspects, process 1200 may be performed by means of a base station, which may include one or more interfaces and processing systems, as described elsewhere herein.

[0129] like Figure 12As shown, in some aspects, process 1200 may include: receiving from the UE information about a timing difference between a means of identifying a source base station and a target base station, wherein the timing difference is associated with a handover of the UE (block 1210). For example, the source base station (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, or controller / processor 240) may receive from the UE information about the timing difference between a means of identifying a source base station and a target base station. The timing difference may be associated with a handover of the UE.

[0130] like Figure 12 As shown, in some aspects, process 1200 may include: transmitting information identifying a timing advance value of a target base station based at least in part on information about the timing difference between the means identifying the source base station and the target base station (block 1220). For example, the source base station (e.g., using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may transmit information identifying a timing advance value of a target base station based at least in part on information about the timing difference between the means identifying the source base station and the target base station.

[0131] Process 1200 may include additional aspects, such as any single aspect or any combination of aspects described below or in conjunction with one or more other processes described elsewhere herein.

[0132] In the first aspect, the information identifying the timing difference between the means of identifying the source base station and the target base station is a quantification of the timing difference. In the second aspect, alone or in combination with the first aspect, the information identifying the timing difference between the means of identifying the source base station and the target base station is received in a radio resource management report. In the third aspect, alone or in combination with one or more of the first and second aspects, the information identifying the timing advance value of the target base station is transmitted in conjunction with a handover command. In the fourth aspect, alone or in combination with one or more of the first to third aspects, the source base station can determine the timing advance value of the target base station based at least in part on the information identifying the timing difference between the means of identifying the source base station and the target base station. In the fifth aspect, alone or in combination with one or more of the first to fourth aspects, the source base station can select a technique for determining the timing advance value of the target base station based at least in part on the information identifying the timing difference between the means of identifying the source base station and the target base station. In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the technique is selected from a plurality of techniques including at least one of the following: determining the target base station timing advance value as zero, determining the target base station timing advance value based on the source base station timing advance value associated with the means of the source base station, or determining the target base station timing advance value using an uplink reference signal.

[0133] Although Figure 12 An example box of process 1200 is shown, but in some aspects, process 1200 may include... Figure 12 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 1200 may be executed in parallel.

[0134] The foregoing disclosure provides explanations and descriptions, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made based on the foregoing disclosure, or modifications and variations may be derived from practice in the aspects.

[0135] As used herein, the term "component" is intended to be interpreted broadly as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented using hardware, firmware, or a combination of hardware and software.

[0136] This article describes several aspects in conjunction with thresholds. As used in this article, satisfying a threshold can refer to a value that is greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, or not equal to the threshold.

[0137] As used in this article, the phrase “at least one of” in a list of items refers to any combination of those items, including a single member. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc.

[0138] The various illustrative logics, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the aspects disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. The interchangeability of hardware and software has been demonstrated by the various illustrative components, blocks, modules, circuits, and processes described above, all centered around functionality. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the entire system.

[0139] Hardware and data processing apparatuses for implementing the various illustrative logics, logic blocks, modules, and circuits described in conjunction with the aspects disclosed herein can be implemented or executed using general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some aspects, a particular process or method can be executed by circuitry specific to a given function.

[0140] In one or more aspects, the described functionality may be implemented in hardware, digital electronic circuits, computer software, firmware (including the structures disclosed in this specification and their structural equivalents), or any combination thereof. Aspects of the subject matter described in this specification may also be implemented as one or more computer programs encoded on a computer storage medium for execution by a data processing apparatus or for controlling the operation of a data processing apparatus; that is, one or more modules of computer program instructions.

[0141] If implemented in software, the functionality can be stored or transmitted as one or more instructions or code in a computer-readable medium. The processes of the methods or algorithms disclosed herein can be implemented in executable software modules that can reside on a computer-readable medium. Computer-readable media include both computer storage media and communication media, wherein the communication media includes any medium capable of enabling the transfer of a computer program from one place to another. Storage media can be any available medium accessible to a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and is accessible to a computer. Furthermore, any connection may be appropriately referred to as a computer-readable medium. As used herein, "disk" and "optical disc" include compact optical discs (CDs), laser discs, optical discs, digital versatile optical discs (DVDs), floppy disks, and Blu-ray discs, wherein disks typically magnetically copy data, while optical discs typically optically copy data using lasers. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the operation of a method or algorithm may reside as any one or any combination or set of code and instructions on a machine-readable and computer-readable medium, which may be incorporated into a computer program product.

[0142] Various modifications to the aspects described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the spirit or scope of this disclosure. Therefore, this claim is not intended to be limited to the aspects shown herein, but rather to be consistent with the widest scope in accordance with this disclosure, the principles disclosed herein, and the novel features.

[0143] Additionally, those skilled in the art will readily recognize that the terms “upper” and “lower” are sometimes used to facilitate the description of the figures and to indicate relative positions on a correctly oriented page corresponding to the orientation of the figures, and may not reflect the correct orientation of any device as implemented.

[0144] Some features described in this specification in the context of a single aspect may also be implemented in combination within that single aspect. Conversely, various features described in the context of a single aspect may also be implemented individually or in any suitable sub-combination in multiple aspects. Furthermore, although features may be described above as functioning in certain combinations and even initially claimed in this way, in some cases, one or more features from the claimed combination may be removed from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0145] Similarly, although operations are depicted in a specific order in the figures, this should not be construed as requiring such operations to be performed in the shown specific order or sequence, or performing all shown operations to achieve the desired result. Furthermore, the figures may schematically depict one or more exemplary processes in the form of flowchart diagrams. However, other operations not depicted may be incorporated into the schematically illustrated exemplary processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous. Moreover, the separation of the various system components in the aspects described above should not be construed as requiring such separation in all aspects, but rather should be understood as meaning that the described program components and systems can generally be integrated together in a single software product, or packaged into multiple software products. Additionally, other aspects are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and the desired result may still be achieved.

Claims

1. A method for wireless communication performed at a user equipment (UE), comprising: In a handover command from a source base station associated with the UE, information identifying a timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE is received, wherein the granularity of the timing offset is at least partially based on at least one of a digital scheme or a time slot length associated with the target base station; and The target base station timing advance value for handover to the target base station is determined based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value associated with the source base station.

2. The method according to claim 1, further comprising: The timing difference between the target base station and the source base station is determined at least in part based on reference signaling received from the source base station and the target base station.

3. The method according to claim 1, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

4. The method according to claim 1, wherein, The target base station timing advance value is determined at least in part based on the sum of the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

5. The method according to claim 1, wherein, The target base station timing advance value is determined without performing a random access procedure.

6. The method according to claim 1, wherein, The target base station timing advance value is determined at least in part based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

7. A method for wireless communication performed at a source base station, comprising: Information associated with a timing offset of a user equipment (UE) is determined, wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE, and wherein the granularity of the timing offset is at least partially based on a digital scheme or time slot length associated with a target base station; and Information identifying the timing offset is sent to the UE in conjunction with the UE's handover from the source base station to the target base station.

8. The method according to claim 7, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

9. The method according to claim 7, wherein, The information identifying the timing offset is sent in conjunction with the switching command.

10. The method of claim 7, further comprising: The timing advance value of the target base station is obtained at least in part based on the timing offset; as well as Send the timing advance value of the target base station.

11. The method according to claim 10, wherein, The target base station timing advance value is sent in conjunction with the handover command.

12. The method according to claim 10, wherein, The timing advance value of the target base station is determined at least in part based on the timing advance value of the source base station.

13. The method of claim 7, further comprising: The timing advance value of the target base station is obtained at least in part based on the timing difference between the target base station and the source base station; as well as Send the timing advance value of the target base station.

14. A method for wireless communication performed at a source base station, comprising: The user equipment (UE) receives information identifying a timing difference between a source base station and a target base station, wherein the timing difference between the source base station and the target base station is associated with a handover of the UE, and wherein the information identifying the timing difference between the source base station and the target base station is a quantization of the timing difference between the source base station and the target base station; and The information identifying the timing advance value of the target base station is sent to the UE based at least in part on the information identifying the timing advance value of the source base station and the information identifying the timing difference between the source base station and the target base station, or at least in part on the information identifying the timing advance value of the source base station, the information identifying the timing difference between the source base station and the target base station, and the information identifying the timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE.

15. The method according to claim 14, wherein, The information identifying the timing difference between the source base station and the target base station is received in a radio resource management report.

16. The method of claim 14, wherein, The information identifying the timing advance value of the target base station is sent in conjunction with the handover command.

17. The method of claim 14, further comprising: The timing advance value of the target base station is obtained at least in part based on the information identifying the timing difference between the source base station and the target base station.

18. The method of claim 14, further comprising: The technique for determining the timing advance value of the target base station is selected based at least in part on the information identifying the timing difference between the source base station and the target base station.

19. The method according to claim 18, wherein, The technology is selected from a plurality of technologies including at least one of the following: The timing advance value of the target base station is set to zero. The target base station timing advance value is determined based on the source base station timing advance value associated with the source base station, or The uplink reference signal is used to determine the timing advance value of the target base station.

20. An apparatus for wireless communication, comprising: A first interface is configured to: obtain, in a handover command from a source base station associated with a user equipment (UE), information identifying a timing offset used to identify the difference between uplink (UL) timing and downlink (DL) timing of the UE, wherein the granularity of the timing offset is at least partially based on at least one of a digital scheme or a time slot length associated with a target base station; and A processing system configured to determine a target base station timing advance value for handover to the target base station based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and a source base station timing advance value associated with the source base station.

21. The apparatus according to claim 20, wherein, The processing system is also configured to: The timing difference between the target base station and the source base station is determined at least in part based on reference signaling received from the source base station and the target base station.

22. The apparatus according to claim 20, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

23. The apparatus according to claim 20, wherein, The target base station timing advance value is determined at least in part based on the sum of the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

24. The apparatus according to claim 20, wherein, The target base station timing advance value is determined without performing a random access procedure.

25. The apparatus according to claim 20, wherein, The target base station timing advance value is determined at least in part based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

26. An apparatus for wireless communication, comprising: A processing system configured to: determine information associated with a timing offset of a user equipment (UE), wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE, and wherein the granularity of the timing offset is at least partially based on a digital scheme or time slot length associated with a target base station; and The first interface is configured to output information identifying the timing offset to the UE in conjunction with the UE's handover from the source base station to the target base station.

27. The apparatus according to claim 26, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

28. The apparatus according to claim 26, wherein, The information identifying the timing offset is sent in conjunction with the switching command.

29. The apparatus according to claim 26, wherein, The processing system is further configured to obtain a target base station timing advance value based at least in part on the timing offset, and wherein the first interface is further configured to output the target base station timing advance value.

30. The apparatus according to claim 29, wherein, The target base station timing advance value is sent in conjunction with the handover command.

31. The apparatus according to claim 29, wherein, The timing advance value of the target base station is determined at least in part based on the timing advance value of the source base station.

32. The apparatus according to claim 26, wherein, The processing system is further configured to obtain a target base station timing advance value based at least in part on the timing difference between the target base station and the source base station, and wherein the first interface is further configured to output the target base station timing advance value.

33. An apparatus for wireless communication, comprising: A first interface is configured to: obtain from a user equipment (UE) information identifying a timing difference between a source base station and a target base station, wherein the timing difference between the source base station and the target base station is associated with the handover of the UE, and wherein the information identifying the timing difference between the source base station and the target base station is a quantization of the timing difference between the source base station and the target base station; and The second interface is configured to output information identifying the timing advance value of the target base station to the UE, based at least in part on information identifying the timing advance value of the source base station and information identifying the timing difference between the source base station and the target base station, or at least in part on information identifying the timing advance value of the source base station, information identifying the timing difference between the source base station and the target base station, and information identifying a timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE.

34. The apparatus according to claim 33, wherein, The information identifying the timing difference between the source base station and the target base station is received in a radio resource management report.

35. The apparatus according to claim 33, wherein, The information identifying the timing advance value of the target base station is sent in conjunction with the handover command.

36. The apparatus of claim 33, further comprising a processing system configured to: The timing advance value of the target base station is obtained at least in part based on the information identifying the timing difference between the source base station and the target base station.

37. The apparatus of claim 33, further comprising a processing system configured to: The technique for determining the timing advance value of the target base station is selected based at least in part on the information identifying the timing difference between the source base station and the target base station.

38. The apparatus according to claim 37, wherein, The technology is selected from a plurality of technologies including at least one of the following: The timing advance value of the target base station is set to zero. The target base station timing advance value is determined based on the source base station timing advance value associated with the source base station, or The uplink reference signal is used to determine the timing advance value of the target base station.

39. A non-transitory computer-readable medium storing one or more instructions for wireless communication, said one or more instructions comprising: One or more instructions that, when executed by one or more processors of a user equipment (UE), cause the one or more processors to perform the following operations: In a handover command from a source base station associated with the UE, information identifying a timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE is received, wherein the granularity of the timing offset is at least partially based on at least one of a digital scheme or a time slot length associated with the target base station; and The target base station timing advance value for handover to the target base station is determined based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value associated with the source base station.

40. The non-transitory computer-readable medium according to claim 39, wherein, When executed by the one or more processors, the one or more instructions also cause the one or more processors to perform the following operations: The timing difference between the target base station and the source base station is determined at least in part based on reference signaling received from the source base station and the target base station.

41. The non-transitory computer-readable medium according to claim 39, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

42. The non-transitory computer-readable medium according to claim 39, wherein, The target base station timing advance value is determined at least in part based on the sum of the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

43. The non-transitory computer-readable medium according to claim 39, wherein, The target base station timing advance value is determined without performing a random access procedure.

44. The non-transitory computer-readable medium according to claim 39, wherein, The target base station timing advance value is determined at least in part based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

45. A non-transitory computer-readable medium storing one or more instructions for wireless communication, said one or more instructions comprising: One or more instructions that, when executed by one or more processors of the source base station, cause the one or more processors to perform the following operations: Information associated with a timing offset of a user equipment (UE) is determined, wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE, and wherein the granularity of the timing offset is at least partially based on a digital scheme or time slot length associated with a target base station; and Information identifying the timing offset is sent to the UE in conjunction with the UE's handover from the source base station to the target base station.

46. ​​The non-transitory computer-readable medium according to claim 45, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

47. The non-transitory computer-readable medium according to claim 45, wherein, The information identifying the timing offset is sent in conjunction with the switching command.

48. The non-transitory computer-readable medium according to claim 45, wherein, When executed by the one or more processors, the one or more instructions also cause the one or more processors to perform the following operations: The timing advance value of the target base station is obtained at least in part based on the timing offset; and Send the timing advance value of the target base station.

49. The non-transitory computer-readable medium according to claim 48, wherein, The target base station timing advance value is sent in conjunction with the handover command.

50. The non-transitory computer-readable medium according to claim 48, wherein, The timing advance value of the target base station is determined at least in part based on the timing advance value of the source base station.

51. The non-transitory computer-readable medium according to claim 45, wherein, When executed by the one or more processors, the one or more instructions also cause the one or more processors to perform the following operations: The timing advance value of the target base station is obtained at least in part based on the timing difference between the target base station and the source base station; and Send the timing advance value of the target base station.

52. A non-transitory computer-readable medium storing one or more instructions for wireless communication, said one or more instructions comprising: One or more instructions that, when executed by one or more processors of the source base station, cause the one or more processors to perform the following operations: The user equipment (UE) receives information identifying a timing difference between a source base station and a target base station, wherein the timing difference between the source base station and the target base station is associated with a handover of the UE, and wherein the information identifying the timing difference between the source base station and the target base station is a quantization of the timing difference between the source base station and the target base station; and The information identifying the timing advance value of the target base station is sent to the UE based at least in part on the information identifying the timing advance value of the source base station and the information identifying the timing difference between the source base station and the target base station, or at least in part on the information identifying the timing advance value of the source base station, the information identifying the timing difference between the source base station and the target base station, and the information identifying the timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE.

53. The non-transitory computer-readable medium according to claim 52, wherein, The information identifying the timing difference between the source base station and the target base station is received in a radio resource management report.

54. The non-transitory computer-readable medium according to claim 52, wherein, The information identifying the timing advance value of the target base station is sent in conjunction with the handover command.

55. The non-transitory computer-readable medium according to claim 52, wherein, When executed by the one or more processors, the one or more instructions also cause the one or more processors to perform the following operations: The timing advance value of the target base station is obtained at least in part based on the information identifying the timing difference between the source base station and the target base station.

56. The non-transitory computer-readable medium according to claim 52, wherein, When executed by the one or more processors, the one or more instructions also cause the one or more processors to perform the following operations: The technique for determining the timing advance value of the target base station is selected based at least in part on the information identifying the timing difference between the source base station and the target base station.

57. The non-transitory computer-readable medium according to claim 56, wherein, The technology is selected from a plurality of technologies including at least one of the following: The timing advance value of the target base station is set to zero. The target base station timing advance value is determined based on the source base station timing advance value associated with the source base station, or The uplink reference signal is used to determine the timing advance value of the target base station.

58. An apparatus for wireless communication, comprising: At least one memory; as well as One or more processors, coupled to the at least one memory, are configured to: In a handover command from a source base station associated with a user equipment (UE), information is received identifying a timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE, wherein the granularity of the timing offset is based at least in part on at least one of a digital scheme or a time slot length associated with a target base station. as well as The target base station timing advance value for handover to the target base station is determined based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value associated with the source base station.

59. The apparatus according to claim 58, wherein, The one or more processors are further configured to: The timing difference between the target base station and the source base station is determined at least in part based on reference signaling received from the source base station and the target base station.

60. The apparatus according to claim 58, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the device, the source base station, or the target base station.

61. The apparatus according to claim 58, wherein, The target base station timing advance value is determined at least in part based on the sum of the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

62. The apparatus according to claim 58, wherein, The target base station timing advance value is determined without performing a random access procedure.

63. The apparatus according to claim 58, wherein, The target base station timing advance value is determined at least in part based on the information identifying the timing offset, the timing difference between the target base station and the source base station, and the source base station timing advance value.

64. A source base station, comprising: transmitter; At least one memory; as well as One or more processors, coupled to the at least one memory, are configured to: Information associated with a timing offset of a user equipment (UE) is determined, wherein the timing offset is at least partially based on the difference between the downlink propagation delay and the uplink propagation delay of the UE, and wherein the granularity of the timing offset is at least partially based on a digital scheme or time slot length associated with a target base station; and In conjunction with the handover of the UE from the source base station to the target base station, information identifying the timing offset is transmitted to the UE via the transmitter.

65. The source base station according to claim 64, wherein, The timing offset is based at least in part on the transition time, the propagation delay between transmission and reception, or the hardware configuration of at least one of the UE, the source base station, or the target base station.

66. The source base station according to claim 64, wherein, The information identifying the timing offset is sent in conjunction with the switching command.

67. The source base station according to claim 64, wherein, The one or more processors are further configured to: The timing advance value of the target base station is obtained at least in part based on the timing offset; and Output the timing advance value of the target base station.

68. The source base station according to claim 67, wherein, The target base station timing advance value is sent in conjunction with the handover command.

69. The source base station according to claim 67, wherein, The timing advance value of the target base station is determined at least in part based on the timing advance value of the source base station.

70. The source base station according to claim 64, wherein, The one or more processors are further configured to: The timing advance value of the target base station is obtained at least in part based on the timing difference between the target base station and the source base station; and Output the timing advance value of the target base station.

71. A source base station, comprising: transmitter; At least one memory; as well as One or more processors, coupled to the at least one memory, are configured to: The user equipment (UE) receives information identifying the timing difference between a source base station and a target base station, wherein the timing difference between the source base station and the target base station is associated with the UE's handover, and wherein the information identifying the timing difference between the source base station and the target base station is a quantization of the timing difference between the source base station and the target base station; and The information identifying the timing advance value of the target base station is transmitted to the UE via the transmitter, based at least in part on the information identifying the timing advance value of the source base station and the information identifying the timing difference between the source base station and the target base station, or at least in part on the information identifying the timing advance value of the source base station, the information identifying the timing difference between the source base station and the target base station, and the information identifying the timing offset used to identify the difference between the uplink (UL) timing and downlink (DL) timing of the UE.

72. The source base station according to claim 71, wherein, The information identifying the timing difference between the source base station and the target base station is received in a radio resource management report.

73. The source base station according to claim 71, wherein, The information identifying the timing advance value of the target base station is sent in conjunction with the handover command.

74. The source base station according to claim 71, wherein, The one or more processors are further configured to: The timing advance value of the target base station is obtained at least in part based on the information identifying the timing difference between the source base station and the target base station.

75. The source base station according to claim 71, wherein, The one or more processors are further configured to: The technique for determining the timing advance value of the target base station is selected based at least in part on the information identifying the timing difference between the source base station and the target base station.

76. The source base station according to claim 75, wherein, The technology is selected from a plurality of technologies including at least one of the following: The timing advance value of the target base station is set to zero. The target base station timing advance value is determined based on the source base station timing advance value associated with the source base station, or The uplink reference signal is used to determine the timing advance value of the target base station.

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