WO2020215340A1

WO2020215340A1 - Random access procedure

Info

Publication number: WO2020215340A1
Application number: PCT/CN2019/084690
Authority: WO
Inventors: Pingping Wen; Wenjian Wang; Tao Yang
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-04-26
Filing date: 2019-04-26
Publication date: 2020-10-29
Also published as: CN113826438A

Abstract

A handover for random access procedure is disclosed. A target network device receives a request for handover from a source network device (220), the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure, and a mobility status of the terminal device. The target network device in response to the request, determines whether the terminal device needs to perform a random access procedure during a handover procedure based on the request (225). The target network device generates an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure. And the target network device transmits the acknowledgement to the source network device (230). In this way, the RA procedure is improved and the access time can be reduced.

Description

RANDOM ACCESS PROCEDURE

FIELD

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to methods, devices, apparatuses and computer readable storage medium for random access (RA) .

BACKGROUND

In recent years, different communication technologies have been proposed to improve communication performances, such as, the New Radio (NR) (also referred to the fifth generation (5G) ) system. Some new network architecture, for example, supporting satellite access, has been proposed. Typically, in such communications system, a network device (for example, gNB) is implemented on the satellite. The movement of the satellite brings a big challenge for the mobility management. More specifically, a user equipment (UE) needs to perform more handovers in such communications system. Therefore, it is now desirable to provide an efficient mechanism for improving the RA procedure.

SUMMARY

In general, example embodiments of the present disclosure provide a solution for a RA procedure.

In a first aspect, there is provided a method implemented at a target network device. The method comprises: receiving at a target network device, a request for handover from a source network device, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device; in response to the request, determining whether the terminal device needs to perform the random access procedure during the handover procedure based on the request; generating an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure; and transmitting the acknowledgement to the source network device.

In a second aspect, there is provided a method implemented at a source network device. The method comprises: generating, at a source network device a request for handover, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate a target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device; transmitting the request to the target network device; in response to receiving an acknowledgement for handover to the request from the target network device, generating a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement; and transmitting the command to the terminal device.

In a third aspect, there is provided a method implemented at a terminal device. The method comprises: receiving at a terminal device, a command for handover from a source network device, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device; and performing the handover procedure based on the determination.

In a fourth aspect, there is provided a device. The device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to receive at a target network device, a request for handover from a source network device, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate a target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device. The device is also caused to in response to the request, determine whether the terminal device needs to perform the random access procedure during the handover procedure based on the request. The device is further caused to generate an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure. And the device is further caused to transmit the acknowledgement to the source network device.

In a fifth aspect, there is provided a device. The device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to generate, at a source network device a request for handover, the request comprising at least one of: first information of a positioning capability indicating information of a positioning capability indicating, second information to indicate a target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device. The device is also caused to transmit the request to a target network device. The device is further caused to in response to receiving an acknowledgement for handover to the request from the target network device, generate a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement. And the device is further caused to transmit the command to the terminal device.

In a sixth aspect, there is provided a device. The device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to receive at a terminal device, a command for handover from a source network device, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device. The device is also caused to perform the handover procedure based on the determination.

In a seven aspect, there is provided an apparatus. The apparatus comprises: means for receiving at a target network device, a request for handover from a source network device, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device; means for in response to the request, determining whether the terminal device needs to perform the random access procedure during the handover procedure based on the request; means for generating an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure; means for transmitting the acknowledgement to the source network device.

In an eighth aspect, there is provided an apparatus. The apparatus comprises: means for generating, at a source network device a request for handover, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate the target device whether a terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device; means for transmitting the request to the target network device; means for in response to receiving an acknowledgement for handover to the request from the target network device, generating a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement; and means for transmitting the command to the terminal device.

In a ninth aspect, there is provided an apparatus. The apparatus comprises: means for receiving at a terminal device, a command for handover from a source network device, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device; and means for performing the handover procedure based on the determination.

In the tenth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to first aspect to the third aspect.

It is to be understood that the summary section is not intended to identify key or essential features of example embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

Fig. 1 illustrates an example communication network in which example embodiments of the present disclosure may be implemented;

Fig. 2 illustrates a schematic diagram of a signaling chart among devices according to some example embodiments of the present disclosure;

Fig. 3 illustrates a schematic element in a command according to some example embodiments of the present disclosure;

Fig. 4 illustrates a schematic diagram of a signaling chart among devices according to some example embodiments of the present disclosure;

Fig. 5 illustrates a schematic diagram of a signaling chart among devices according to some example embodiments of the present disclosure;

Fig. 6 illustrates a schematic diagram of a signaling chart among devices according to some example embodiments of the present disclosure;

[Corrected under Rule 26, 17.06.2019]
Fig. 7 illustrates a schematic diagram of a signaling chart among devices according to some example embodiments of the present disclosure;

[Corrected under Rule 26, 17.06.2019]
Fig. 8 illustrates a flowchart of a method implemented at a target network device according to some example embodiments of the present disclosure;

[Corrected under Rule 26, 17.06.2019]
Fig. 9 illustrates a flowchart of a method implemented at a source network device according to some example embodiments of the present disclosure;

[Corrected under Rule 26, 17.06.2019]
Fig. 10 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

[Corrected under Rule 26, 17.06.2019]
Fig. 11 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure; and

[Corrected under Rule 26, 17.06.2019]
Fig. 12 illustrates a schematic diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these example embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one example embodiment, ” “an example embodiment, ” “an example embodiment, ” and the like indicate that the example embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every example embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same example embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other example embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular device, or other computing or device.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future 5G communication protocols, and/or any other protocols either currently known or to be developed in the future. Example embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system. For the purpose of illustrations, embodiments of the present disclosure will be described with reference to 5G communication system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

Recently, the third-generation partnership project (3GPP) has initiated a study item to extend the applicability to non-terrestrial network (NTN) . More specifically, the communication network is able to use the 5G radio access for satellite links. As an important part of mobility management in radio resource control (RRC) connection mode, the handover mechanism should be studied considering the special characteristics in the NTN communication network.

In such communication network, the deployment scenario includes geostationary network device/satellite, non-geostationary network device/satellite and high-altitude platform (HAPS) network device. The geo-stationary satellite is located at approximately 36,000 Km from the surface of the earth around the equator in a belt known as the “Clark Belt” . But non-geostationary orbit systems/satellites (NGSO) , such as, low earth orbit (LEO) satellite, medium earth orbit (MEO) satellite and HAPS, are not fixed and move rapidly with respect to any given location of terminal device. The cell coverage area moves with a very high speed, which causes more frequent handover and needs large requirement on RA capacity to access the new satellite. Since each of the LEO satellites may have many beams, the terminal device may stay in one beam within several minutes and will perform handover procedure frequently.

Some agreements have been reached for improving the mobility management. One of the agreements is that the location of the terminal device and the ephemeris of the satellite are beneficial for the handover procedure. Another agreement is that conditional handover (CHO) may be supported in the communication system. More specifically, if the CHO is supported, the source network device will configure the handover condition to the terminal device, send the handover request to the target network device, and receive a handover acknowledgement from the target network device. Then, when the handover condition is satisfied, the terminal device will trigger the handover procedure including a RA procedure to the target network device. With the CHO, the handover command can be sent to the terminal device in advance and the target network device will allocate a preamble and an uplink resource for the non-contention based RA procedure. However, such preamble and uplink resource will be reserved for a long time considering the long latency. Therefore, although some agreements have been reached and some proposals have been provided, there are still many issues in mobility need to be solved. One of the pending issues is that how to improve the RA procedure during the handover procedure. Currently there are no solutions to address such issue.

According to example embodiments of the present disclosure, there is proposed an improved solution for RA procedure. First, the present inventors recognized that timing advance (TA) can be derived based on the location of the terminal device and the ephemeris of the satellite, which makes that the RA procedure becomes a non-mandatory procedure in a handover procedure and can be omitted thereby. In addition, the present inventors also recognized that with the position information of the terminal device, the target network device may know when the terminal device will enter its coverage. Therefore, the duration for reserving the preamble and the uplink resource can be predicted. Based on the above considerations, this present disclosure proposed a solution for improving the RA procedure.

In this solution, both the terminal device and the network device can determine whether a RA procedure is needed during the handover procedure with additional information, such as, first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, and a mobility status of the terminal device (such as, a location of the terminal device, a time when the terminal device is positioned at the location, a velocity of the terminal device and so on) , and a random access channel (RACH) load and so on. When the RA procedure is not needed during the handover procedure, the target network device can allocate an uplink resource for data transmission in advance and information of this allocated uplink resource can be included in the handover command. In this way, the RA procedure can be used more efficiently. Meanwhile, since the RA procedure may be saved, the access time can be reduced.

Further, in case that the RA procedure is needed the target network device may reserve a preamble and an uplink resource for the terminal device. Further, the target network device can determine a valid duration of the reserved preamble for a contention free RA procedure. In this way, the valid duration for the preamble is optimized.

Principle and embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Reference is first made to Fig. 1, which illustrates an example communication network 100 in which embodiments of the present disclosure may be implemented. As shown, the communication network 100 includes two network devices 110-1, 110-2 (collectively referred to as network device (s) 110) , and one terminal device 120. The network devices 110-1, 110-2 serve respective areas 130-1, 130-2 (also called as cells 130-1, 130-2) . Only for the purpose of illustration without suggesting any limitations, the network devices 110-1, 110-2 are implemented on different satellites. It is to be understood that the numbers of network devices and terminal devices are only for the purpose of illustration without suggesting any limitations. The communication system 100 may include any suitable numbers of network devices and terminal devices adapted for implementing embodiments of the present disclosure. Only for the purpose of illustration without suggesting any limitations, the network device 110-1 actions as a source network device (referred to as source network device 110-1) and the network device 110-2 actions as a target network device (referred to as target network device 110-2) .

The communications in the communication network 100 may conform to any suitable standards including, but not limited to, Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , New radio (NR) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols.

The present inventors recognize that according to a positioning capability of the terminal device 120, the terminal device 120 can be divided into two types. One type is that the terminal device 120 has the positioning capability, for example, the terminal device 120 may obtain its positioning information through such as global navigation satellite system (GNSS) . The other type is that the terminal device 120 does not have the positioning capability. In case that the terminal device 120 does not have the positioning capability, the source network device 110-1 can obtain the positioning information of the terminal device 120 and provide the positioning information to the terminal device 120. Embodiments of the present disclosure for these two types of users will be discussed separately.

Terminal Device with positioning capability

In case that the terminal device 120 has positioning capability, the terminal device 120 can derive the TA based on a location of the terminal device 120 and an ephemeris of the satellite on which a target network device (such as, network device 110-2) is implemented. Therefore, for this type of terminal device, the RA procedure becomes a non-mandatory procedure in the handover procedure. Both the terminal device 120 and the target network device 110-2 may determine whether the terminal device 120 needs to perform a RA procedure.

Reference is now made to Fig. 2, which shows a schematic diagram of signaling chart 200 in accordance with example embodiments of the present disclosure. The signaling chart 200 may be implemented at any suitable devices. Only for the purpose of illustrations, the signaling chart 200 are described to be implemented at the terminal device 120 and the source network device 110-1 and the target network device 110-2.

It is to be understood that the numbers of terminal devices and network devices shown in Fig. 2 are given for the purpose of illustration without suggesting any limitations. The signaling chart 200 may include any suitable numbers of terminal devices and network devices.

In this example embodiment, the target network device 110-2 determines whether the terminal device 120 needs to perform the RA procedure during a handover procedure.

The terminal device 120 transmits 210 a message to the source network device 110-1 to inform the source network device 110-1 that the terminal device 120 has positioning capability. For example, the message comprises a first indication indicating whether a terminal device can obtain positioning information by itself. The first indication may be one-bit value. In this example, the first indication indicates that the terminal device has the positioning capability. The message may be any suitable message including existing message or new introduced message.

The source network device 110-1 transmits 220 a request for handover to the target network device 110-2. The request for handover comprises the first indication obtained at 210. Only for the purpose of illustration without suggesting any limitations, the request may be handover request defined in the 3GPP standard.

Alternatively, and in addition, the request for handover may further comprise other information, for example, a mobility status of the terminal device (such as, a location of the terminal device, a time when the terminal device is positioned at the location and a velocity of the terminal device) .

As the first indication indicates that the terminal device 120 has the positioning capability, the target network device 110-2 is informed that the terminal device 120 can obtain positioning information. The target network device 110-2 may determine 225 whether the RA procedure is needed based on a RACH load of the target network device 110-2.

Alternatively, and in addition, if the request for handover comprises at least one of the location of the terminal device, the velocity of the terminal device, such information may also be considered when the target network device 110-2 determines whether the RA procedure is needed. If the target network device 110-2 determines that the terminal 120 does not need to perform the RA procedure, the target network device 110-2 allocates an uplink resource for the terminal device as step2 in a RA procedure.

Alternatively, and in addition, if the request for handover comprises at least one of the location of the terminal device, the velocity of the terminal device, such information may also be considered when the target network device 110-2 allocates uplink resource.

In some example embodiments, the target network device 110-2 uses a third indication to indicate whether the terminal 120 needs to perform the RA procedure during the handover procedure. The third indication and the information of the allocated uplink resource may be comprised in an acknowledgement for handover. Only for the purpose of illustration without suggesting any limitations, the acknowledgement may be handover t acknowledgement defined in the 3 GPP standard.

The target network device 110-2 transmits 230 the acknowledgement to the source network device 110-1. The source network device 110-1 generates a command for handover based on the acknowledgement received at 230. Only for the purpose of illustration without suggesting any limitations, the command may be handover command defined in the 3GPP standard.

Reference is now made to Fig. 3, which shows a schematic element 300 in a command according to some example embodiments of the present disclosure. As shown in Fig. 3, the field 310 of “RACH_dedicated_boolean” is used to indicate whether the RA procedure is needed, and the field 320 “Uplink_resources_withoutRACH” is used to indicate the allocated uplink resource when RA procedure is not needed

Further, element 300 can include the same fields as the fields in Random Access Response Grant (e.g., msg2) which is shown in the following Table 1.

Table 1: Random Access Response Grant Content field size

RAR grant field	Number of bits
Frequency hopping flag	1
PUSCH frequency resource allocation	14
PUSCH time resource allocation	4
MCS	4
TPC command for PUSCH	3
CSI request	1

The source network device 110-1 transmits 240 the generated command to the terminal device 120. Then the terminal device 120 can determine whether to perform the RA procedure during the handover procedure.

Further, when the RA procedure is not performed, the terminal device 120 needs to calculate TA based on ephemeris information of the target network device 110-2 and the positioning information (i.e., location) of the terminal device 120. In some example embodiments, the ephemeris information can be obtained from the target network device 110-2 via the source network device 110-1.

In some example embodiments, if the command comprises the third indication indicating the terminal device 120 does not need to perform the RA procedure. The terminal device 120 extracts the information of the allocated uplink resource from the command. When the terminal device 120 switches to the target network device 110-2, the terminal device 120 can transmit uplink data with the allocated uplink resource based on the calculated TA.

In this way, the RA procedure can be used more efficiently. Meanwhile, since the RA procedure may be saved, the time for RA procedure can be reduced thereby.

As discussed above, the terminal device 120 may determine whether to perform a RA procedure by itself. In such case, the RA procedure is not needed for the terminal device 120 since the terminal device 120 knows that it has the positioning capability and can derive the TA based on the location of the terminal device 120 and the ephemeris of the target network device 110-2. Further, such procedure can be pre-configured in the communication network 100. Such scenario may be illustrated by referring Fig. 4.

Fig. 4 shows a schematic diagram of signaling chart 400 in accordance with example embodiments of the present disclosure. The signaling chart 400 may be implemented at any suitable devices. Only for the purpose of illustrations, the signaling chart 400 are described to be implemented at the terminal device 120, the source network device 110-1 and the target network device 110-2.

It is to be understood that the numbers of terminal devices and network devices shown in Fig. 4 are given for the purpose of illustration without suggesting any limitations. The signaling chart 400 may include any suitable numbers of terminal devices and network devices.

The operations of transmitting/receiving 410 and transmitting/receiving 420 are similar with the operations of transmitting/receiving 210 and transmitting/receiving 220 as discussed above. For brevity, the detailed description is not repeated here. As the procedure is pre-configured in the communication network 100, the source network device 110-1 is informed that the terminal device 120 has the positioning capability. The target network device 110-2 allocates uplink resource for the terminal device as step 2 in a RA procedure without reserving the preamble for contention-free random access. In some example embodiments, if the request for handover comprises at least one of the location of the terminal device, the velocity of the terminal device, this information may also be considered when the target network device 110-2 allocates the uplink resource. The information of the allocated uplink resource is comprised in an acknowledgement for handover and transmitted to the source network device 110-1. It should be noted that in this example scenario, the third indication is not necessary and should not be transmitted.

The operations of transmitting/receiving 430 and transmitting/receiving 440 are similar with the operations of transmitting/receiving 230 and transmitting/receiving 240 in Fig. 2 as discussed above. For brevity, the detailed description is not repeated here. The only difference is that the third indication indicating whether the terminal device 120 needs to perform the RA procedure is omitted.

After receiving the command from the source network device 110-1, the terminal device 120 extracts the information of the allocated uplink resource. Further, the terminal device 120 needs to calculate TA based on ephemeris information of the target network device 110-2 and the positioning information (i.e., location) of the terminal device 120. In some example embodiments, the ephemeris information can be obtained from the target network device 110-2 via the source network device 110-1. When the terminal device 120 switches to the target network device 110-2, the terminal device 120 can transmit uplink data with the allocated uplink resource based on the calculated TA.

The terminal device without positioning capability

If the terminal device 120 does not have positioning capability, the source network device 110-1 or the target network device 110-2 can determines whether the terminal device 120 needs to perform the RA procedure. The terminal device 120 can transmit the first indication indicating the terminal device does not have the positioning capability to the target network device 110-2 via the source network device 110-1. In such scenario, the target network device 110-2 can improve the handover procedure if the mobility status of the terminal device is available. Such procedure will be discussed by referring the Fig. 7 in the following.

Fig. 5 shows a schematic diagram of signaling chart 500 in accordance with example embodiments of the present disclosure. The signaling chart 500 may be implemented at any suitable devices. Only for the purpose of illustrations, the signaling chart 500 are described to be implemented at the terminal device 120, the source network device 110-1 and the target network device 110-2.

It is to be understood that the numbers of terminal devices and network devices shown in Fig. 5 are given for the purpose of illustration without suggesting any limitations. The signaling chart 500 may include any suitable numbers of terminal devices and network devices.

As the terminal device 120 does not have positioning capability, the terminal device 120 needs to perform measurement with the source network device 110-1. Therefore, the source network device 110-1 can obtain the positioning information of the terminal device 120 and the positioning information can be transmitted to the terminal device. As shown in Fig. 5, the terminal device 120 receives 510 a configuration for measurement from the source network device 110-1, and transmits 520 measurement data to the source network device 110-1. By this way, the source network device 110-1 may obtain a mobility status of the terminal device (such as, a location of the terminal device, a time when the terminal device is positioned at the location) . Further, the source network device 110-1 can obtain a velocity of the terminal device 120. In some example embodiments, the source network device 110-1 can estimate the velocity from the measurement data. In other example embodiments, the source network device 110-1 can obtain the velocity form a report from the terminal device 120.

Then, the source network device 110-1 determines 525 whether the terminal device 120 needs to perform the RA procedure based on at least one of the location of the terminal device, the velocity of the terminal device, and the time when the terminal device is positioned at the location. For example, if the terminal device 120 is with slow movement, the position of the terminal device 120 remains almost unchanged. Then the source network device 110-1 can send the estimated location of the terminal device 120 as well as the ephemeris of the target network device 110-2 to the terminal device 120. In some example embodiments, the source network device 110-1 obtains the ephemeris from the target network device 110-2. The terminal device 120 can derive the TA based on the location of the terminal device 120 and the ephemeris of the target network device 110-2. But if the terminal device 120 is with fast movement (the terminal device 120 can report the velocity information to the source network device 110-1 or velocity information is estimated at the source network device 110-1) , upon transmission of the estimated location at the source network device 110-1 to the terminal device 120, there will be the difference between the estimated location and the current location due to the long propagation delay. Therefore, terminal device 120 cannot obtain the accurate TA and the RA procedure is still needed for the handover procedure.

In some example embodiments, the source network device 110-1 may determine whether terminal device 120 needs to perform the RA during the handover procedure based on the mobility status of the terminal device (such as, the velocity information, and the time for the location of the terminal device 120) . In some example embodiments, the source network device 110-1 uses second information to inform the target network device 110-2 the determination. The second information indicates whether the terminal device needs to perform the RA procedure during the handover procedure. The source network device 110-1 transmits 530 the request for handover comprising the second information to the target network device 110-2.

Alternatively, and in addition, the request for handover may further comprises some other information, such as, a location of the terminal device, a time when the terminal device is positioned at the location and a velocity of the terminal device.

After receiving 530 the request for handover, the target network device 110-2 extracts the second information from the request and determines whether the terminal device 120 needs to perform the RA procedure. More specifically, if the second information indicates that the terminal device 120 does not need to perform the RA procedure during the handover procedure, the target network device 110-2 allocates an uplink resource for the terminal device. In some example embodiments, if the request for handover comprises at least one of the location of the terminal device, the velocity of the terminal device, this information may also be considered when the target network device 110-2 allocates the uplink resource. The information of the allocated uplink resource is comprised in an acknowledgement for handover and transmitted to the source network device 110-1.

After receiving 540 the acknowledgement for handover from the target network device 110-2, the source network device 110-1 generates a command for handover based on the acknowledgement. Further, a third indication should be comprised in the command for handover. The third indication indicates whether the terminal device needs to perform the RA. The operation of transmitting/receiving 550 in Fig. 5 is similar with the operation of transmitting/receiving 440 in Fig. 4 as discussed above. For brevity, the detailed description is not repeated here.

In some example embodiments, if the command comprises the third indication indicating the terminal device 120 does not need to perform the RA procedure. The terminal device 120 extracts the information of the allocated uplink resource from the command. Further, since the RA procedure is not performed, the terminal device 120 may calculate TA based on ephemeris information of the target network device 110-2 and the positioning information of the terminal device 120. In some example embodiments, the ephemeris information can be obtained from the target network device 110-2 via the source network device 110-1. When the terminal device 120 switches to the target network device 110-2, the terminal device 120 can transmit uplink data with the allocated uplink resource base on the calculated TA.

As discussed above, the target network device 110-2 can determine whether the terminal device 120 needs to perform the RA procedure. Fig. 6 shows a schematic diagram of signaling chart 600 in accordance with example embodiments of the present disclosure. The signaling chart 600 may be implemented at any suitable devices. Only for the purpose of illustrations, the signaling chart 600 are described to be implemented at the terminal device 120, the source network device 110-1 and the target network device 110-2 in Fig. 1.

It is to be understood that the numbers of terminal devices and network devices shown in Fig. 6 are given for the purpose of illustration without suggesting any limitations. The signaling chart 600 may include any suitable numbers of terminal devices and network devices.

The operations of transmitting/receiving 610 and transmitting/receiving 620 are similar with the operations of transmitting/receiving 510 and transmitting/receiving 520 as discussed above. For brevity, these details are not repeated here. In this scenario, after obtains a mobility status of the terminal device 120 (such as, a location of the terminal device, a time when the terminal device is positioned at the location, and a velocity of the terminal device) , the source network device 110-1 transmits 630 this information to the target network device 110-2 via a handover request. Further, the source network device may also transmit a second indication to the target network device 110-2. The second indication is determined by the source network derive 110-1 based on the mobility status of the terminal device 120, and used to indicate whether the source network device can provide the positioning information for the terminal device. In some example embodiments, the if the velocity of the terminal device 120 is below a threshold velocity, the source network device 110-1 determines a second indication indicating the terminal device 120 can obtain positioning information form the source network device 110-1. Alternatively, and in addition, if the velocity of the terminal device 120 exceeding the threshold velocity, the source network device 110-1 determines the second indication indicating the terminal device 120 cannot obtain positioning information form the source network device 110-1.

Then target network device 110-2 determines 640 whether to the terminal device 120 needs to perform the RA procedure based on the mobility status of the terminal device 120, the second indication and the RACH load of the target network device 110-2. Further, if the target network device 110-2 determines that the terminal 120 does not need to perform the RA procedure, the target network device 110-2 needs to allocate uplink resource for the terminal device as step 2 in a RA procedure. Alternatively, and in addition, the mobility status of the terminal device (such as, a location of the terminal device, a time when the terminal device is positioned at the location, and a velocity of the terminal device) may also be considered when the target network device 110-2 allocates uplink resource.

In this scenario, the target network device 110-2 also needs to use the third indication to indicate whether the terminal 120 needs to perform the RA procedure during a handover procedure. The operations of 640 and 650 are similar with the operations of 230 and 240 as discussed above. For brevity, these details are not repeated here.

In this way, an improved RA scheme for handover in NTN system is provided. This scheme enables a more flexible RA procedure according to different types of the terminal device. With this solution, the RA procedure can be used efficiently, and the time for handover can be reduced with the allocated uplink transmission resource.

In addition to providing a solution for improving the RA procedure, some example embodiments of the present discourse also provide a solution for optimizing the valid duration in case that the terminal device 120 needs to perform the RA procedure. Principle and embodiments for this solution will be discussed by referring to Fig. 7.

Fig. 7 shows a schematic diagram of signaling chart 700 in accordance with example embodiments of the present disclosure. The signaling chart 700 may be implemented at any suitable devices. Only for the purpose of illustrations, the signaling chart 700 are described to be implemented at the terminal device 120, the source network device 110-1 and the target network device 110-2.

It is to be understood that the numbers of terminal devices and network devices shown in Fig. 7 are given for the purpose of illustration without suggesting any limitations. The signaling chart 200 may include any suitable numbers of terminal devices and network devices.

The target network device 110-2 determines the terminal device 120 needs to perform the RA procedure. The target network device 110-2 may determine whether to reserve a preamble and an uplink resource for the terminal device 120 based on the mobility status of the terminal device (such as, a location of the terminal device, a velocity of the terminal device, and a time when the terminal device is positioned at the location) .

If the target network device 110-2 determines to reserve the preamble and the uplink resource, the target network device 110-2 reserves the preamble and the uplink resource for the terminal devicel20. As shown in Fig. 7, the source network device 110-1 sends 705 the mobility status of the terminal device (as well as the velocity information, and the time for the location of the terminal device 120) to the target network device 110-2. When the target network device 110-2 receives the handover request which includes such information, the target network device 110-2 will know approximately duration that the terminal device 120 will be under its coverage and access to the target network device 110-2. Then the target network device 110-2 will reserve the preamble for contention free access and send the handover acknowledgement to the source network device 110-1 The target network device 110-2 determines to reserve a preamble and an uplink resource for the terminal device 120 and the target network device 110-2 knows that the terminal device 120 will use this resource in the future.

In some example embodiments, the target network device 110-2 transmits 720 an acknowledgement to the target network device 110-2. The acknowledgement may comprise the reserved preamble. In some example embodiments, the acknowledgement further comprises the valid duration. The source network device 110-1 generates a command comprising the reserved preamble and an optional valid duration. The source network device 110-1 transmits 730 the command to the terminal device.

If CHO is executed 740 at the terminal device 120 side, when the terminal device 120 in the border of the coverage of the two network devices 110 and meet the condition for handover trigger. The terminal device 120 performs 750 the RA procedure with the reserved preamble to the target network device. In some example embodiments, if the command comprises a valid duration for the reserved preamble, the terminal device 120 performs the RA procedure with the reserved preamble within the valid duration. It can be clearly seen that during the period of 760, the preamble and uplink resource can be used by the other terminal device since the target network device 110-2 can know approximately duration that the terminal device 120 will be under its coverage.

Fig. 8 illustrates a flowchart of a method 800 in accordance with example embodiments of the present disclosure. The method 800 may be implemented at any suitable device. Only for the purpose of illustrations, the method 800 is described to be implemented at the target network device 110-2.

At block 810, the target network device 110-2 receives, a request for handover from a source network device 110-2, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device 120 can be obtained, second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device 120. At block 820 in response to the request, the target network device 110-2 determines whether the terminal device 120 needs to perform a random access procedure during a handover procedure based on the request. At block 830, the target network device 110-2 generates an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure. At block 840, the target network device 110-2 transmits the acknowledgement to the source network device 110-2.

In some example embodiments, the first information of the positioning capability comprises: a first indication indicating whether the terminal device 120 has a positioning capability, or a second indication indicating whether the source network device 110-2 can provide the positioning information for the terminal device 120.

In some example embodiments, the mobility status of the terminal device 120 comprises at least one of: a location of the terminal device 120, a time when the terminal device 120 is positioned at the location, and a velocity of the terminal device 120.

In some example embodiments, if the first indication indicating the terminal device has the positioning capability or the second information indicating the target device that the terminal device does not need to perform the random access procedure during the handover procedure, the target network device 110-2 determines that the terminal device 120 does not need to perform the random access procedure. If the first indication indicating the terminal device does not have the positioning capability or the second information indicating the target device that the terminal device needs to perform the random access procedure during the handover procedure, the terminal device 120 determines that the terminal device 120 needs to perform the random access procedure.

In some example embodiments, the target network device 110-2 determines whether the terminal device 120 needs to perform the random access procedure further based on a random access channel load of the target network device and other information.

In some example embodiments, in response to determining that the terminal device 120 does not need to perform the random access procedure, the target network device 110-2 allocates an uplink resource for the terminal device 120, the uplink resource being used for a uplink data transmission when the terminal device 120 switches to the target network device 110-2 and generates the acknowledgement comprising the additional information indicating the allocated uplink resource.

In some example embodiments, the target network device 110-2 allocates an uplink resource is based on the mobility status of the terminal device 120.

In some example embodiments, in response to determining that the terminal device 120 needs to perform the random access procedure, the target network device 110-2 reserves a preamble and an uplink resource for the terminal device 120, and determines a valid duration for the reserved preamble based on the mobility status of the terminal device. The preamble is used for a contention free random access procedure of the terminal device 120, and the uplink resource is used for a uplink data transmission when the terminal device 120 switches to the target network device 110-2.

In some example embodiments, the target network device 110-2 generates the acknowledgement comprising the additional information indicating the reserved preamble and the valid duration.

In some example embodiments, the target network device 110-2 reserves the preamble and the uplink resource is based on the mobility status of the terminal device 120.

In some example embodiments, the target network device 110-2 generates a third indication, the third indication indicating whether the terminal device 120 needs to perform the random access procedure during a handover procedure. The target network device 110-2 and generates the acknowledgement comprising the additional information comprising the third indication.

In some example embodiments, the target network device 110-2 transmits ephemeris information of the target network device 110-2 to the source network device 110-2.

Fig. 9 illustrates a flowchart of a method 900 in accordance with example embodiments of the present disclosure. The method 900 may be implemented at any suitable devices. Only for the purpose of illustrations, the method 900 is described to be implemented at the source network device 110-1.

At block 910, the source network device 110-1 generates a request for handover, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate a target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device 120. At block 920, the source network device 110-1 transmits the request to a target network device 110-2. At block 930, in response to receiving an acknowledgement for handover to the request from the target network device 110-2, the source network device 110-2 generates a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement. At block 940, the source network device 110-1 transmits the command to the terminal device 120.

In some example embodiments, the source network device 110-1 generates the request comprising the first indication comprised in a massage received from the terminal device 120.

In some example embodiments, in response to the first indication indicating the terminal device 120 does not have the positioning capability, the source network device 110-1 generates the request comprising the mobility status of the terminal device 120.

In some example embodiments, in response to the velocity of the terminal device 120 being below a threshold velocity, the source network device 110-1 determines the second indication to indicate that the source network device 110-2 can provide the positioning information for the terminal device 120; the source network device 110-1, and in response to the velocity of the terminal device 120 exceeding the threshold velocity, in response to the velocity of the terminal device 120 exceeding the threshold velocity, determining the second indication to indicate that the source network device 110-2 cannot provide positioning information for the terminal device 120 determines the second indication to indicate that the source network device 110-2 cannot provide positioning information for the terminal device 120. Further, the source network device 110-1 generates the request comprising the second indication.

In some example embodiments, the source network device 110-1 transmits a configuration for measurement to the terminal device 120, receives measurement data from the terminal and obtains the mobility status of the terminal device 120 from the measurement data.

In some example embodiments, the source network device 110-1 transmits the mobility status to the terminal device 120 and transmits ephemeris information received from the target network device 110-2 to the terminal device 120.

Fig. 10 illustrates a flowchart of a method 1000 in accordance with example embodiments of the present disclosure. The method 1000 may be implemented at any suitable devices. Only for the purpose of illustrations, the method 1000 is described to be implemented at the terminal device 120.

At block 1010, the terminal device 120 receives a command for handover from a source network device 110-2, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device 120. At block 1020, the terminal device 120 performs the handover procedure based on the determination.

In some example embodiments, the terminal device 120 transmits a message to the source network device 110-2, the message comprising a first indication indicating whether the terminal device 120 has a positioning capability.

In some example embodiments, in response to the command comprising the additional information indicating an allocated uplink resource, the terminal device 120 performs a handover procedure without performing the random access procedure, the uplink resource being allocated by a target network device 110-2 and being used for a uplink data transmission when the terminal device 120 switches to the target network device 110-2. Further, the terminal device 120 transmits uplink data with the allocated uplink resource based on the calculated TA when the terminal device 120 switches to the target network device 110-2.

In some example embodiments, in response to the command comprising the additional information indicating a reserved preamble and a valid duration for the reserved preamble, the terminal device 120 performs the random access procedure with the reserved preamble to the target network device 110-2 during the handover procedure within the valid duration. The preamble is reserved by a target network device 110-2 and is used for a contention free random access procedure of the terminal device 120.

In some example embodiments, the terminal device 120 receives a configuration for measurement from the source network device 110-2, transmits measurement data to the source network device 110-2 and receives a mobility status of the terminal device 120 from the source network device 110-2.

In some example embodiments, the terminal device 120 receives ephemeris information of a target network device 110-2 from the source network device 110-2.

In some example embodiments, the terminal device 120 obtains a location of the terminal device 120, and calculates a timing advance based on the ephemeris information and the location of the terminal device 120.

In some example embodiments, transmitting uplink data with the allocated uplink resource is based on the timing advance.

In some example embodiments, an apparatus capable of performing any of the method 800 (for example, the target network device 110-2) may comprise means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus further comprises means for receiving at a target network device, a request for handover from a source network device, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device; means for in response to the request, determining whether the terminal device needs to perform the random access procedure during the handover procedure based on the request; means for generating an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure; means for transmitting the acknowledgement to the source network device.

In some example embodiments, the information of the positioning capability comprises: a first indication indicating whether the terminal device has a positioning capability, or a second indication indicating whether the source network device can provide the positioning information for the terminal device.

In some example embodiments, the mobility status of the terminal device comprises at least one of: a location of the terminal device, a time when the terminal device is positioned at the location, and a velocity of the terminal device.

In some example embodiments, means for determining whether the terminal device needs to perform the random access procedure comprises: means for in response to the first indication indicating the terminal device has the positioning capability or the second information indicating the target device that the terminal device does not need to perform the random access procedure during the handover procedure, determining that the terminal device does not need to perform the random access procedure; and means for in response to the first indication indicating the terminal device does not have the positioning capability or the second information indicating the target device that the terminal device needs to perform the random access procedure during the handover procedure, determining that the terminal device needs to perform the random access procedure.

In some example embodiments, wherein means for determining whether the terminal device needs to perform the random access procedure comprises means for determining whether the terminal device needs to perform the random access procedure is further based on a random access channel load of the target network device.

In some example embodiments, means for generating the acknowledgement comprises: means for in response to determining that the terminal device does not need to perform the random access procedure, allocating an uplink resource for the terminal device, the uplink resource being used for a uplink data transmission when the terminal device switches to the target network device; and means for generating the acknowledgement comprising the additional information indicating the allocated uplink resource.

In some example embodiments, means for allocating an uplink resource comprises means for allocating an uplink resource is based on the mobility status of the terminal device.

In some example embodiments, means for generating the acknowledgement comprises: means for in response to determining that the terminal device needs to perform the random access procedure, reserving a preamble and an uplink resource for the terminal device, the preamble being used for a contention free random access procedure of the terminal device, the uplink resource being used for a uplink data transmission based on the calculated TA when the terminal device switches to the target network device; and means for determining a valid duration for the reserved preamble based on the mobility status of the terminal device.

In some example embodiments, means for generating the acknowledgement comprising the additional information indicating the reserved preamble and the valid duration.

In some example embodiments, means for reserving the preamble and the uplink resource comprises means for reserving the preamble and the uplink resource is based the mobility status of the terminal device.

In some example embodiments, means for wherein generating the acknowledgement comprises: means for generating a third indication, the third indication indicating whether the terminal device needs to perform the random access procedure during a handover procedure; and means for generating the acknowledgement comprising the additional information comprising the third indication.

In some example embodiments, an apparatus further comprise: means for transmitting ephemeris information of the target network device to the source network device.

In some example embodiments, an apparatus capable of performing any of the method 900 (for example, the source network device 110-1) may comprise means for performing the respective steps of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for generating, at a source network device a request for handover, the request comprising at least one of: first information of a positioning capability indicating whether positioning information of a terminal device can be obtained, second information to indicate a target device whether the terminal device needs to perform a random access procedure during a handover procedure and a mobility status of the terminal device; means for transmitting the request to the target network device; means for in response to receiving an acknowledgement for handover to the request from the target network device, generating a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement; and means for transmitting the command to the terminal device.

In some example embodiments, means for generating the request comprises: means for in response to the first indication indicating the terminal device does not have the positioning capability, generating the request comprising the mobility status of the terminal device.

In some example embodiments, means for generating the request comprises: mean for in response to the velocity of the terminal device being below a threshold velocity, determining the second indication to indicate that the source network device can provide the positioning information for the terminal device; and means for in response to the velocity of the terminal device exceeding the threshold velocity, determining the second indication to indicate that the source network device cannot provide positioning information for the terminal device; and means for generating the request comprising the second indication.

In some example embodiments, the apparatus further comprises means for generating the request comprising the second indication; and means for receiving measurement data from the terminal; and means for obtaining the mobility status of the terminal device from the measurement data.

In some example embodiments, means for generating the request comprises: means for determining the second information based on the mobility status of the terminal device; and means for generating the request comprising the second information.

In some example embodiments, the apparatus further comprises means for transmitting the mobility status to the terminal device; and means for transmitting ephemeris information received from the target network device to the terminal device.

In some example embodiments, an apparatus capable of performing any of the method 1000 (for example, the terminal device 120) may comprise means for performing the respective steps of the method 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for receiving at a terminal device, a command for handover from a source network device, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device; and means for performing the handover procedure based on the determination.

In some example embodiments, the apparatus further comprises means for transmitting a message to the source ne. twork device. The message comprises a first indication indicating whether the terminal device has a positioning capability.

In some example embodiments, the apparatus further comprises means for in response to the command comprising the additional information indicating an allocated uplink resource, performing a handover procedure without performing the random access procedure and means for transmitting uplink data with the allocated uplink resource when the terminal device switches to the target network device. The uplink resource is allocated by a target network device and being used for an uplink data transmission when the terminal device switches to the target network device.

In some example embodiments, the apparatus further comprises means for in response to the command comprising the additional information indicating a reserved preamble and a valid duration for the reserved preamble, performing the random access procedure with the reserved preamble to the target network device during the handover procedure within the valid duration. The preamble is reserved by a target network device and being used for a contention free random access procedure of the terminal device.

In some example embodiments, the apparatus further comprises means for extracting a third indication from the command, the third indication indicating whether the terminal device needs to perform the random access procedure.

In some example embodiments, the apparatus further comprises means for receiving a configuration for measurement from the source network device. Means for transmitting measurement data to the source network device. And means for receiving a mobility status of the terminal device from the source network device.

The apparatus further comprises means for receiving ephemeris information of a target network device from the source network device.

In some example embodiments, the apparatus further comprises means for obtaining a location of the terminal device. And means for calculating a timing advance based on the ephemeris information and the location of the terminal device. Transmitting uplink data with the allocated uplink resource is based on the timing advance.

Fig. 11 is a simplified block diagram of a device 1100 that is suitable for implementing example embodiments of the present disclosure. The device 1100 may be provided to implement the communication device, for example the device 110 or the terminal device 120 as shown in Fig. 1. As shown, the device 1100 includes one or more processors 1110, one or more memories 1140 coupled to the processor 1110, and one or more transmitters and/or receivers (TX/RX) 1140 coupled to the processor 1110.

The TX/RX 1140 is for bidirectional communications. The TX/RX 1140 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 1110 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1100 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 1120 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1124, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1122 and other volatile memories that will not last in the power-down duration.

A computer program 1130 includes computer executable instructions that are executed by the associated processor 1110. The program 1130 may be stored in the ROM 1020. The processor 1110 may perform any suitable actions and processing by loading the program 1130 into the RAM 1120.

The example embodiments of the present disclosure may be implemented by means of the program 1130 so that the device 1100 may perform any process of the disclosure as discussed with reference to Figs. 8 to 10. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 1130 may be tangibly contained in a computer readable medium which may be included in the device 1100 (such as in the memory 1120) or other storage devices that are accessible by the device 1100. The device 1100 may load the program 1130 from the computer readable medium to the RAM 1122 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. Fig. 12 shows an example of the computer readable medium 1200 in form of CD or DVD. The computer readable medium has the program 1130 stored thereon.

Generally, various example embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of example embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the method 800 to method 1000 as described above with reference to Figs. 8-10. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various example embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular example embodiments. Certain features that are described in the context of separate example embodiments may also be implemented in combination in a single example embodiment. Conversely, various features that are described in the context of a single example embodiment may also be implemented in multiple example embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A method, comprising:

receiving at a target network device, a request for handover from a source network device, the request comprising at least one of:

first information of a positioning capability indicating whether positioning information of a terminal device can be obtained,

second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure, and

a mobility status of the terminal device;

in response to the request, determining whether the terminal device needs to perform the random access procedure during the handover procedure based on the request;

generating an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure; and

transmitting the acknowledgement to the source network device.
The method of claim 1, wherein the first information of the positioning capability comprises:

a first indication indicating whether the terminal device has a positioning capability, or

a second indication indicating whether the source network device can provide the positioning information for the terminal device.
The method of claim 1, wherein the mobility status of the terminal device comprises at least one of:

a location of the terminal device,

a time when the terminal device is positioned at the location, and

a velocity of the terminal device.
The method of claim 2, wherein determining whether the terminal device needs to perform the random access procedure comprises:

in response to the first indication indicating the terminal device has the positioning capability or the second information indicating the target device that the terminal device does not need to perform the random access procedure during the handover procedure, determining that the terminal device does not need to perform the random access procedure; and

in response to the first indication indicating the terminal device does not have the positioning capability or the second information indicating the target device that the terminal device needs to perform the random access procedure during the handover procedure, determining that the terminal device needs to perform the random access procedure.
The method of claim 1, wherein determining whether the terminal device needs to perform the random access procedure is further based on a random access channel load of the target network device.
The method of claim 1, wherein generating the acknowledgement comprises:

in response to determining that the terminal device does not need to perform the random access procedure, allocating an uplink resource for the terminal device, the uplink resource being used for a uplink data transmission when the terminal device switches to the target network device; and

generating the acknowledgement comprising the additional information indicating the allocated uplink resource.
The method of claim 6, wherein allocating an uplink resource is based on the mobility status of the terminal device.
The method of claim 1, further comprising:

in response to determining that the terminal device needs to perform the random access procedure, reserving a preamble and an uplink resource for the terminal device, the preamble being used for a contention free random access procedure of the terminal device, the uplink resource being used for a uplink data transmission when the terminal device switches to the target network device; and

determining a valid duration for the reserved preamble based on the mobility status of the terminal device.
The method of claim 8, wherein generating the acknowledgement comprises:

generating the acknowledgement comprising the additional information indicating the reserved preamble and the valid duration.
The method of claim 8 or 9, wherein reserving the preamble and the uplink resource is based on the mobility status of the terminal device.
The method of claim 1, wherein generating the acknowledgement comprises:

generating a third indication, the third indication indicating whether the terminal device needs to perform the random access procedure during a handover procedure; and

generating the acknowledgement comprising the additional information comprising the third indication.
The method of claim 1, further comprising:

transmitting ephemeris information of the target network device to the source network device.
A method, comprising:

generating, at a source network device a request for handover, the request comprising at least one of:

first information of a positioning capability indicating whether positioning information of a terminal device can be obtained,

second information to indicate a target device whether the terminal device needs to perform a random access procedure during a handover procedure, and

a mobility status of the terminal device;

transmitting the request to the target network device;

in response to receiving an acknowledgement for handover to the request from the target network device, generating a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement; and

transmitting the command to the terminal device.
The method of claim 13, wherein the first information of the positioning capability comprises:

a first indication indicating whether the terminal device has a positioning capability, or

a second indication indicating whether the source network device can provide the positioning information for the terminal device.
The method of claim 13, wherein the mobility status of the terminal device comprises at least one of:

a location of the terminal device,

a time when the terminal device is positioned at the location, and

a velocity of the terminal device.
The method of claim 14, wherein generating the request comprises:

generating the request comprising the first indication comprised in a massage received from the terminal device.
The method of claim 13, wherein generating the request comprises:

in response to the first indication indicating the terminal device does not have the positioning capability, generating the request comprising the mobility status of the terminal device.
The method of claim 14, wherein generating the request comprises:

in response to the velocity of the terminal device being below a threshold velocity, determining the second indication to indicate that the source network device can provide the positioning information for the terminal device; and

in response to the velocity of the terminal device exceeding the threshold velocity, determining the second indication to indicate that the source network device cannot provide positioning information for the terminal device; and

generating the request comprising the second indication.
The method of claim 13, wherein generating the request comprises:

determining the second information based on the mobility status of the terminal device; and

generating the request comprising the second information.
The method of claim 13, further comprising:

transmitting a configuration for measurement to the terminal device;

receiving measurement data from the terminal; and

obtaining the mobility status of the terminal device from the measurement data.
The method of claim 13, further comprising at least one of:

transmitting the mobility status to the terminal device, and

transmitting ephemeris information received from the target network device to the terminal device.
A method, comprising:

receiving at a terminal device, a command for handover from a source network device, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device; and

performing the handover procedure based on the determination.
The method of claim 22, further comprising:

transmitting a message to the source network device, the message comprising a first indication indicating whether the terminal device has a positioning capability.
The method of claim 22, wherein performing the handover procedure comprises:

in response to the command comprising the additional information indicating an allocated uplink resource, performing a handover procedure without performing the random access procedure, the uplink resource being allocated by a target network device and being used for a uplink data transmission when the terminal device switches to the target network device;

and the method further comprising:

transmitting uplink data with the allocated uplink resource when the terminal device switches to the target network device based on the calculated TA.
The method of claim 23, wherein performing the handover procedure comprises: in response to the command comprising the additional information indicating a reserved preamble and a valid duration for the reserved preamble, performing the random access procedure with the reserved preamble to the target network device during the handover procedure within the valid duration, the preamble being reserved by a target network device and being used for a contention free random access procedure of the terminal device.
The method of claim 24 or 25, wherein performing the handover procedure further comprises:

extracting a third indication from the command, the third indication indicating whether the terminal device needs to perform the random access procedure.
The method of claim 22, further comprising:

receiving a configuration for measurement from the source network device;

transmitting measurement data to the source network device; and

receiving a mobility status of the terminal device from the source network device.
The method of claim 27, wherein the mobility status of the terminal device comprises at least one of:

a location of the terminal device,

a time when the terminal device is positioned at the location, and

a velocity of the terminal device.
The method of claim 28, further comprising:

receiving ephemeris information of a target network device from the source network device.
The method of claim 29, further comprising:

obtaining a location of the terminal device; and

calculating a timing advance based on the ephemeris information and the location of the terminal device,

and wherein transmitting uplink data with the allocated uplink resource is based on the timing advance.
A device, comprising:

at least one processor; and

at least one memory including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to perform the method of any of claims 1-12.
A device, comprising:

at least one processor; and

at least one memory including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to perform the method of any of claims 13-21.
A device, comprising:

at least one processor; and

at least one memory including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to perform the method of any of claims 22-30.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 1-12.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 13-21.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by a processor of a device, causing the device to perform the method of any of claims 22-30.
An apparatus, comprising:

means for receiving at a target network device, a request for handover from a source network device, the request comprising at least one of:

first information of a positioning capability indicating whether positioning information of a terminal device can be obtained,

second information to indicate the target device whether the terminal device needs to perform a random access procedure during a handover procedure, and

a mobility status of the terminal device;

means for in response to the request, determining whether the terminal device needs to perform the random access procedure during the handover procedure based on the request;

means for generating an acknowledgement for handover to the request, the acknowledgement including additional information related to the random access procedure; and

means for transmitting the acknowledgement to the source network device.
An apparatus, comprising:

means for generating, at a source network device a request for handover, the request comprising at least one of:

first information of a positioning capability indicating whether positioning information of a terminal device can be obtained,

second information to indicate a target device whether the terminal device needs to perform a random access procedure during the handover procedure, and

a mobility status of the terminal device;

means for transmitting the request to the target network device;

means for in response to receiving an acknowledgement for handover to the request from the target network device, generating a command for handover comprising additional information related to the random access procedure, the additional information being comprised in the acknowledgement; and

means for transmitting the command to the terminal device.
An apparatus, comprising:

means for receiving at a terminal device, a command for handover from a source network device, the command comprising additional information related to a random access procedure during a handover procedure for the terminal device; and

means for performing the handover procedure based on the determination.