CN114258719B

CN114258719B - Switching in communication networks

Info

Publication number: CN114258719B
Application number: CN201980099331.6A
Authority: CN
Inventors: 朱凯; 陈宇; 王文剑
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2019-08-15
Filing date: 2019-08-15
Publication date: 2024-11-22
Anticipated expiration: 2039-08-15
Also published as: WO2021026913A1; CN114258719A

Abstract

Embodiments of the present disclosure relate to handovers in a communication system. According to embodiments of the present disclosure, a terminal device sends a measurement report including information reflecting the state of transport block elimination to the terminal device and a network device determines whether to trigger handover based on the measurement report. In this way, handovers are more accurate, and thus latency is reduced to a great extent by avoiding unnecessary or inappropriate HOs.

Description

Handover in a communication network

Technical Field

Embodiments of the present disclosure relate generally to the field of communications, and more particularly, to a method, apparatus, device, and computer-readable storage medium for handoff in a communication network.

Background

Since resources and infrastructure are limited in remote areas, it is difficult to have a land network provide 5G coverage. The main benefit of introducing non-terrestrial networks (NTNs) is to enable ubiquitous 5G services to terminal devices by extending connectivity in areas of lower population density with very low density devices and the overall cost of deployment can be much less than providing permanent infrastructure on land. The use of a satellite-borne platform or airborne platform may provide reliable coverage in remote areas, which has significant advantages. However, it has also posed some problems in other respects.

Disclosure of Invention

In general, example embodiments of the present disclosure provide a technical solution for handover in a communication network and a corresponding communication device.

In a first aspect, a first device is provided. The first device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to receive, at the first device, information from the second device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, instead of feedback-based retransmissions, the combined TBs being generated based on an original TB on which data to be transmitted is carried. The first device is further caused to send a measurement report to the second device comprising information reflecting the quality of the feedback-free transmission. The first device is further caused to receive an indication from the second device to switch to the third device, the switch being triggered based on information reflecting a quality of the feedback-free transmission.

In a second aspect, a second device is provided. The second device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to transmit information from the second device to the first device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, instead of feedback-based retransmissions, the combined TBs being generated based on an original TB on which data to be transmitted is carried. The second device is further caused to receive a measurement report from the first device including information reflecting the quality of the feedback-free transmission. The second device is further caused to determine whether a handover is triggered based on information reflecting a quality of the feedback-free transmission. The second device is in turn caused to determine a third device for handover in response to a determination that handover is triggered.

In a third aspect, a third device is provided. The third device includes at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the third device to receive a handoff request from the second device at the third device indicating that the first device is to handoff to the third device. The third device is further caused to generate an acknowledgement of the handover request, the acknowledgement comprising information about the configuration of the feedback-free transmission, the feedback-free transmission being generated using one or more combined transport blocks, TBs, based on the original TB on which the data to be transmitted is carried, instead of a feedback-based retransmission. The third device is also caused to send an acknowledgement to the second device. The third device is in turn caused to send a synchronization signal to the first device for handover.

In a fourth aspect, a method is provided. The method comprises the following steps: information is received at the first device from the second device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of feedback-based retransmissions. The method also transmits a measurement report to the second device including information reflecting the quality of the feedback-free transmission. The method also includes receiving an indication from the second device to switch to the third device, the switch being triggered based on information reflecting a quality of the feedback-free transmission.

In a fifth aspect, a method is provided. The method comprises the following steps: information is sent from the second device to the first device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be sent is carried, instead of feedback-based retransmissions. The method also includes receiving a measurement report from the first device including information reflecting a quality of the feedback-free transmission. The method further includes determining whether a handover is triggered based on information reflecting a quality of the feedback-free transmission. The method also includes determining a third device for handover in response to a determination that handover is triggered.

In a sixth aspect, a method is provided. The method includes receiving, at a third device, a handoff request from a second device indicating that the first device is to handoff to the third device. The method further includes generating an acknowledgement of the handover request, the acknowledgement including information regarding a configuration of a feedback-free transmission, the feedback-free transmission being generated using one or more combined transport blocks, TBs, instead of feedback-based retransmissions, the combined TBs being based on an original TB on which data to be transmitted is carried. The method also includes sending an acknowledgement to the second device. The method also includes transmitting a synchronization signal to the first device for handover.

In a seventh aspect, an apparatus is provided. The device comprises: means for receiving, at the first device, information from the second device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of a feedback-based retransmission; means for transmitting a measurement report to the second device comprising information reflecting the quality of the feedback-free transmission; and means for receiving an indication from the second device to switch to the third device, the switch being triggered based on information reflecting the quality of the feedback-free transmission.

In an eighth aspect, an apparatus is provided. The device comprises: means for transmitting information from the second device to the first device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of a feedback-based retransmission; means for receiving a measurement report from the first device comprising information reflecting the quality of the feedback-free transmission; means for determining whether a handover is triggered based on information reflecting the quality of the feedback-free transmission; and means for determining a third device for handover in response to a determination that handover is triggered.

In a ninth aspect, an apparatus is provided. The device comprises: means for receiving, at the third device, a handover request from the second device indicating that the first device is to be handed over to the third device; means for generating an acknowledgement of the handover request, the acknowledgement comprising information about the configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of a feedback-based retransmission; means for sending an acknowledgement to the second device; and means for sending a synchronization signal to the first device for handover.

In a tenth aspect, there is provided a non-transitory computer readable medium comprising instructions for causing an apparatus to perform at least the method according to any one of the fourth to sixth aspects above.

It should be understood that this summary is not intended to identify key or essential features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

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

fig. 1 illustrates the principle of feedback-free transmission;

FIG. 2 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

fig. 3 illustrates a schematic diagram of interactions between communication devices according to some embodiments of the present disclosure;

fig. 4 illustrates a schematic diagram of RSRP varying between cells in accordance with some embodiments of the present disclosure;

fig. 5 illustrates a flowchart of a method implemented at a network device according to some embodiments of the present disclosure;

fig. 6 illustrates a flowchart of a method implemented at a network device according to some embodiments of the present disclosure;

fig. 7 illustrates a flowchart of a method implemented at a network device according to some embodiments of the present disclosure;

FIG. 8 illustrates a simplified block diagram of a device suitable for implementing embodiments of the present disclosure; and

Fig. 9 illustrates a block diagram of an example computer-readable medium, according to some embodiments of the disclosure.

The same or similar reference numbers will be used throughout the drawings to refer to the same or like elements.

Detailed Description

Principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that the principles of this disclosure will now be described with reference to some example embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and practicing the present disclosure, and do not imply any limitation as to the scope of the present disclosure. The disclosure described herein may be implemented in various ways other than those described below.

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

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

It will be understood that, although the terms "first," "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 element. 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 items.

The terminology used herein is for the purpose of describing particular 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, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.

As used in this disclosure, the term "circuitry" may refer to one or more or all of the following:

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

(B) A combination of hardware circuitry and software, such as (if applicable):

(i) Combination of analog and/or digital hardware circuit(s) and software/firmware

(Ii) Hardware processor(s) with software (including digital signal processor (s)), software and any portion of memory(s) that work together to cause a device (such as a mobile phone or server) to perform various functions, and

(C) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware) for operation, but software may not exist when it is not needed for operation.

This definition of circuitry applies to the present application including all uses of that term in any claims. As another example, as used in this disclosure, the term circuitry also encompasses hardware-only circuits or processors (or multiple processors) or portions of hardware circuits or processors and its (or their) accompanying software and/or firmware implementations. For example and if applicable to the particular claim elements, the term circuitry also encompasses baseband integrated circuits or processor integrated circuits for a mobile device or a server, a cellular network device, or similar integrated circuits in other computing or network devices.

As used herein, the term "communication device" refers to a network that complies with any suitable communication standard, such as: long Term Evolution (LTE), LTE-advanced (LTE-a), wideband Code Division Multiple Access (WCDMA), high Speed Packet Access (HSPA), narrowband internet of things (NB-IoT), new Radio (NR), non-terrestrial network (NTN), etc. In addition, communication between a terminal device and a network device in a communication network may be performed according to any suitable communication protocol including, but not limited to: first generation (1G), second generation (2G), 2.5G, 2.85G, third generation (3G), fourth generation (4G), 4.5G, future fifth generation (5G) communication protocols, and/or any other protocol currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Due to the rapid development of communications, there will of course also be future types of communication technologies and systems with which the present disclosure may be embodied. It should not be taken as limiting the scope of the present disclosure to only the above-described systems.

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 from it. A network device may refer to a Base Station (BS) or an Access Point (AP), such as a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a repeater, a low power node (such as a femto, pico, etc.), depending on the terminology and technology of the application.

The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user Equipment (UE), subscriber Station (SS), portable subscriber station, mobile Station (MS), or Access Terminal (AT). The terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIP) phones, wireless local loop phones, tablet computers, wearable terminal devices, personal Digital Assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, smart devices, wireless client devices (CPE), internet of things (loT) devices, watches or other wearable equipment, head Mounted Displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in the context of industrial and/or automated processing chains), consumer electronic devices, devices 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.

As mentioned above, NTN has also posed some problems in other respects. For NTN, the Round Trip Time (RTT) to the terminal device may be much greater than in a terrestrial network. One important deployment feature that can distinguish NTNs from terrestrial networks is that NTN base stations are typically satellites in orbit on earth with an orbit altitude of 600-36000km relative to terminal devices on the earth's surface.

The propagation time for an electromagnetic wave to travel through such a distance is measured in table 1 below.

TABLE 1

It can be seen that the propagation delay of NTN is much higher than that which can be tolerated by the NR physical layer (which is limited by the maximum propagation distance of 300 km). On the other hand, such extended propagation delays will also challenge the technical specifications of legacy systems and robust NTN mobility is among the most important issues.

Similar to conventional terrestrial networks, mobility plays a critical role in NTN systems, enabling continuity of radio connectivity and maintaining consistent quality of service for nomadic terminal devices. Optimal Handover (HO) should generally have minimized Handover Interruption Time (HIT), handover failure (HOF) rate, and ping-pong (PP) rate. However, in NTN scenarios, good mobility mechanisms to achieve the above HO goals become technically difficult due to the greatly increased risk of measurement invalidity. Recall that the Round Trip Time (RTT) of the radio signal in NTN may be several orders of magnitude larger than that of the terrestrial network, and that such cumulative delay incurred may result in UE measurements that are too slow or inaccurate.

The procedure established for most conventional HO schemes follows the guidelines of the "UE-assisted, network-controlled" rule. When the measurement results reported by the terminal equipment become unreliable, it will be difficult for the network to make an appropriate HO decision. The cost of an improper HO in NTN is high because the consequent Radio Link Failure (RLF) recovery procedure will consume a considerable amount of delay and service interruption due to signaling delay. According to recent analysis, the overall interruption can be as much as a few seconds when counting delays for Radio Resource Control (RRC) message processing and other signaling transmission delays.

There may be two areas of interest for RAN 2: propagation delay identifying timing requirements and solutions on layer 2 aspects including Medium Access Control (MAC), radio Link Control (RLC), RRC, and radio link management; handoff, which studies and identifies mobility requirements and measurements that may be needed for handoff between non-GEO satellites that move at high speed but on predictable paths.

In addition, other discussions covering these aspects are in the context of mobility. Although it was determined to focus RAN2 on mobility solutions too early, several observations related to the possible challenges of extending Rel-15 mobility procedures in NTN were captured in 38.821: for GEO NTN: the mobility management procedure requires adjustments to accommodate large propagation delays. In particular, radio link management may require canonical configuration; for LEO NTN: the mobility management procedure should be enhanced to take into account satellite movements related to aspects such as measurement availability, UE speed, direction of movement, large and varying propagation delays and dynamic neighbor cell sets.

In rans2 #105, the following observations were agreed to be captured: the company is not ready to identify and agree to solution options for RRM or HO of NTN; for GEO NTN, large propagation delays are identified as a critical issue and the impact on performing measurements and for measurement configuration should be considered; aspects specific to LEO NTN, such as measurement availability, UE speed, direction of movement, widely varying propagation delays, and satellite movement related aspects of dynamic neighbor cell sets are identified.

To summarize the protocols listed above, satellites in non-GEO orbits move at high speed (for LEO, -7.5 km/s) relative to the earth's surface, a common knowledge currently in 3GPP is that frequent handovers are unavoidable because it is handling a moving new wireless (NR) cell. Due to the measurement validity problems mentioned earlier and the ping-pong effect, improper movement actions are expected to occur more often than NR land networks, and such results are not tolerable given very stringent NTN performance requirements.

To overcome the limited functionality provided by the NR HO mechanism, the incorporation of Make Before Break (MBB) HO appears to be a suitable choice for NTN mobility. MBB HO is discussed in Rel 14 as an evolved improved HO feature for long term evolution LTE. The MBB HO method generally assumes that the data exchange with the serving cell is not "broken" until a new connection with the target cell is established (i.e., "connected").

In addition, the following appears to be a reasonable assumption: downlink transmission from the serving cell occurring after the reception of the HO command may end reception of a large amount of incorrect data caused by the deteriorated channel condition. Handling those incorrect data in a retransmission manner while the HO is being run may require additional complexity on the terminal device and network device sides. This facilitates the merging of another important component into the NTN paradigm to avoid explicit retransmission and HARQ feedback signaling, which is an NTN-specific enhancement named feedback-less transmission scheme.

Fig. 1 shows a TB combining and TB elimination procedure outlined for one example in which two original TBs are transmitted using 3 combined TBs. In the first stage, inputs (e.g., TB301 and TB 302) are "combined," i.e., XOR operations are performed with respect to these TBs. In this example, there are two combinations of TB (TB 301 and TB 3021) of degree-1 and one of degree-2 (TB 301+302), where +represents an XOR operation. In this example, it is assumed that TB301 is missing, while the other two TBs 302 and tb301+302 are successfully received. In the TB elimination phase, the effectively received TB of degree-1 is assumed to have been eliminated and becomes "ripple". In the next stage, "ripple" is used to perform additional TB cancellation with respect to other successfully received TB combinations. This process continues until all original TBs have been restored or all TBs in the ripple have been eliminated from the other TBs.

According to an embodiment of the present disclosure, the terminal device transmits an additional measurement report including information reflecting a status of transmission block cancellation to the network device, and the network device determines whether to trigger handover based on the measurement report. In this way, the handover is more accurate and the delay is reduced.

The principles and embodiments of the present disclosure are described in detail below with reference to the drawings. Reference is first made to fig. 2, which illustrates an example communication system 200 in which embodiments of the present disclosure may be implemented.

Fig. 2 illustrates a schematic diagram of a communication system 200 in which embodiments of the present disclosure may be implemented. The communication system 200 includes a first device 210, a second device 220-1, and a third device 220-2. For purposes of illustration, the first device 210 may be referred to hereinafter as a terminal device 210, and the second device 220-1 and the third device 220-2 may be referred to as network devices 220. It should be noted that the first device, the second device, and the third device are interchangeable. For example, a process described as being implemented at a terminal device may also be capable of being implemented at a network device, and a process described as being implemented at a network device may also be capable of being implemented at a terminal device.

Links from the second device 220-1 and the third device 220-2 to the first device 210 may be referred to as "downlink" and links from the first device 210 to the second device 220-1 and the third device 220-2 may be referred to as "uplink".

Communication system 200, which is part of a communication network, includes terminal devices 210-1,210-2, 210-N (collectively referred to as terminal device(s) 210", where N is an integer). Communication system 200 includes one or more network devices, such as network devices 220-1 and 220-2.

It should be understood that communication system 200 may also include other elements omitted for clarity. It should be understood that the number of terminal devices and network devices shown in fig. 2 is given for illustration purposes and does not imply any limitation. Terminal device 210, network device 220-1, and network device 220-2 may communicate with each other.

It should be understood that the number of network devices and terminal devices is for illustration purposes only and does not imply any limitation. System 100 may include any suitable number of network devices and terminal devices suitable for implementing embodiments of the present disclosure.

Communications in communication system 200 may be implemented according to any suitable communication protocol(s) including, but not limited to: cellular communication protocols of the first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), and fifth generation (5G), etc., wireless local network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc., and/or any other protocols currently known or to be developed in the future. Further, the communication may utilize any suitable wireless communication technology including, but not limited to: code Division Multiple Access (CDMA), frequency Division Multiple Access (FDMA), time Division Multiple Access (TDMA), frequency Division Duplex (FDD), time Division Duplex (TDD), multiple Input Multiple Output (MIMO), orthogonal frequency division multiple access (OFDM), discrete fourier transform spread OFDM (DFT-s-OFDM), and/or any other technique currently known or to be developed in the future.

Fig. 3 illustrates a schematic diagram of interactions 300 in a contention-based system according to an embodiment of the present disclosure. Interaction 300 may be implemented at any suitable device. For illustrative purposes only, the interaction 300 is described as being implemented at the terminal device 210-1, the network device 220-1, and the network device 220-2. By way of example, network device 220-1 may be a source network device and network device 220-2 may be a target network device. It should be noted that the phrases "combination TB" and "TB combination" have the same meaning and they may be used interchangeably in this document, and the phrases "eliminating TB" and "TB eliminating" have the same meaning and they may be used interchangeably in this disclosure.

The network device 220-1 sends 3005 information about the configuration of the feedback-free transmission. The term "feedback-free transmission" as used herein refers to transmission using a combined Transport Block (TB) rather than feedback-based retransmission. The configuration may include one or more of the following: no feedback is transmitted redundancy rate, TB degree, or TB combined mode.

The combined TB may be generated based on the original TB on which the data to be transmitted is carried. The feedback-free transmission redundancy rate may indicate a ratio of the number of original TBs to be communicated to the number of actually transmitted TB combinations. The TB degree may indicate the number of original TBs from which a particular TB combination is generated. The TB combination mode may indicate which original TBs are selected to generate a particular TB combination. It should be noted that the acknowledgement may include any suitable parameters related to the combination and cancellation of TBs.

By way of example only, table 2 below shows a combined mode of feedback-free transmission. It should be noted that the numbers and values shown in table 2 are merely examples and not limiting.

TABLE 2

Transport instance #	TB combination to be transmitted	Buffer ID#)
			1	TB0	1
2	TB1	2
			3	TB2+TB0	3
4	TB3+TB1+TB0	4
			5	TB3+TB2	5
6	TB2	6
			7	TB3	7
8	TB1+TB2	8

The number of original TBs to be communicated from the sender side to the receiver side is 4, tb0, TB1, TB2, TB3. The number of combined TBs actually transmitted over the air interface is 8. Thus, the feedback-free transmission redundancy rate is 4/8.TB degrees (or simply "degrees") is 1, since TB0 is the original TB, which may be denoted as "degree-1". The TB degree of "tb3+tb1+tb0" is 3 because it is generated based on three original TBs, which can be denoted as "degree-3", where +denotes an XOR operation.

In some embodiments, the information may be part of the broadcasted system information. In other embodiments, the information may be downlink control information. Alternatively, the information may be part of dedicated RRC signaling.

In some embodiments, if the terminal device 210-1 is in the rrc_connected state, the terminal device 210-1 and the network device 220-1 may communicate with each other using feedback-free transmission due to the high latency of the air interface. For example, network device 220-1 may send 3010 data to terminal device 210-1 using feedback-free transmission.

In some embodiments, the network device 220-1 may send 3015 signaling to activate the feedback-free transmission. In some embodiments, the signaling may be an RRC message dedicated to the terminal device 210-1. Alternatively or additionally, the signalling may be broadcast to a plurality of terminal devices.

The terminal device 210-2 sends 3020 a measurement report to the network device 220-1. The measurement report includes information reflecting the quality of the feedback-free transmission. In some embodiments, the measurement report includes at least one of: the number of degree-1 TBs obtained from the TB combination transmitted from the second device, the ratio of the original TBs successfully recovered from the TB combination, the ratio of the original TBs failed to be recovered from the TB combination, the index of the original TBs successfully recovered from the TB combination, or the index of the original TBs failed to be recovered from the TB combination. In some embodiments, the process of restoration of the original TB may also be referred to as "TB elimination".

In some embodiments, recovery of the original TB may rely on successful cancellation of the degree-1 TB from the received TB combination. During each cancellation, a freshness-1 TB must be generated to hold another cancellation in progress. When radio link conditions deteriorate or experience an interruption causing too many missing or erroneously received TB combinations, TB cancellation is likely to be suspended in the middle of the process, as the number of degree-1 TBs generated becomes insufficient to maintain the remainder of the cancellation, and a large part of the received TB combinations is therefore unrecoverable.

The network device 220-1 determines 3025 whether a handover is triggered based on the measurement report. The network device 220-1 may evaluate the measurement report and trigger a HO decision if the condition is met. It should be noted that making NTN HO decisions will not be reliable depending on the received power strength alone because of the additional erasure properties of the NTN channel. In contrast, measurement reports related to information reflecting the status of transport block erasures can describe the condition of erasure channels from the erasure probability dimension. In this way, the handover decision is more accurate.

In some embodiments, the network device 220-1 may compare the quality of the feedback-free transmission to a threshold quality. If the quality exceeds a threshold quality, the network device 220-1 may trigger into a handoff state. If the quality is below the threshold quality, the network device 220-1 may not trigger into the handover state. The network device 220-1 may ignore the measurement report and remain monitored. Network device 220-1 may reconfigure feedback-free transmissions such as TB redundancy rate, TB degree, or TB combined mode. The network device 220-1 may also reconfigure other transmission parameters for future transmissions, such as Modulation and Coding Scheme (MCS) and transmit power.

In some embodiments, there may be several different thresholds to avoid "false alarms" in the event that the radio link between terminal device 210-1 and network device 220-1 drops only temporarily and will recover soon. event-X1: the quality of the feedback-free transmission at the serving cell is above a threshold-1 but below a threshold-2. The proposed HO conditions may be described below as shown in table 3.

TABLE 3 Table 3

In some embodiments, the number of degree-1 TBs generated during TB cancellation is critical to maintaining continuous TB cancellation and is more sensitive to channel variations than signal power.

In some embodiments, if the channel conditions are relatively good, the TB combination has no significant benefit, meaning that each of the TB cancellations is successful. In some embodiments, when channel conditions begin to drop, the TB elimination experiences some small degree of failure. The final TB elimination may be successful by waiting for more TB combinations to be received for auxiliary elimination. When channel conditions remain below a certain threshold, TB cancellation experiences so many failures that the degree-1 TB generated during cancellation becomes insufficient to maintain the remaining cancellation, eventually the TB cancellation collapses.

The configuration of feedback-free transmission is shown in the previous table 2 for illustration purposes only. If the channel conditions begin to drop, the first transmission and the second transmission (e.g., TB0 and TB 1) may not be received. Since there is no knowledge that neither TB0 nor TB1 performs TB cancellation, tb2+tb0 and tb3+tb1+tb0 may simply be stored waiting for additional combined TBs to arrive. In this example, TB cancellation may be successful with the following steps: (1) buffer # 6+buffer #3→tb0 (new degree-1 TB); (2) buffer # 6+buffer #5→tb3 (new degree-1 TB); (3) Buffer #4+tb0 (new) +tb3 (new) - > TB1 (new degree-1 TB). Thus, all data on TB0 through TB3 may be successfully recovered and three new degree-1 TB's are generated during this process.

In some embodiments, if the channel condition has fallen below a threshold value. For example, the first, second, fifth and sixth TB combinations are missing, with one degree-1 TB at the beginning of the elimination. And more importantly, no matter how the cancellation is performed, no new degree-1 TB will be generated, so in this example, the generated degree-1 TB is insufficient to maintain the cancellation, which is faulty. It is clear that TB elimination operates in a continuous manner. The degree-1 TB is to maintain continuous TB cancellation and is more sensitive to the state of the channel.

If the network device 220-1 determines to trigger a handover, the network device 220-1 determines 3026 a target network device. The network device 220-1 may search for neighboring network devices whose trajectories may be aligned with the coverage area of the terminal device 210-1 for a given window. For example, the network device 220-1 may determine the target network device based on the speed of the terminal device 210-1, the direction of movement of the terminal device 210-1 and the dynamic neighbor cell set. After the network device 220-1 determines the network device 220-2 as the target network device, the network device 220-1 may send 3030 a handover request to the network device 220-2.

The network device 220-2 generates 3032 an Acknowledgement (ACK) of the handover request. In some embodiments, the ACK may also include configuration information for another feedback-free transmission supported by network device 220-2. For example, the ACK may include one or more of a feedback-free transmission redundancy rate, a TB degree, or a TB combination mode. The TB redundancy rate may indicate a ratio of the number of original TBs to be communicated to the number of actually transmitted TB combinations. The network device 220-2 may send 3035 an ACK for the handover request to the network device 220-1. In some embodiments, the ACK may also include configuration information for another feedback-free transmission supported by network device 220-2. In some embodiments, the network device 220-1 may send 3040 another feedback-free transmission of information to the terminal device 210-1. The network device 220-2 may send 3045 an indication to the terminal device 210-1 to switch to the network device 220-2.

The network device 220-2 sends 3050 a synchronization signal to the terminal device 210-1. In some embodiments, the terminal device 210-1 may perform simultaneous reception of the synchronization signal from the network device 220-2 for initial access purposes while continuing data transmission with the network device 220-1. For example, the terminal device 210-1 may continue to send 3055 data to the network device 220-1. In some embodiments, the terminal device 210-1 may also send a new measurement report to the network device 220-1.

In some embodiments, network device 220-1 may forward 3060 data buffered in network device 220-1 for future transmission from network device 220-1 to network device 220-2. For example, if the number of degree-1 TBs received by terminal device 210-1 decreases, network device 220-1 may forward data that has not yet been transmitted. Alternatively or additionally, if the number of degree-1 TBs received by terminal device 210-1 is below a threshold number, network device 220-1 may forward data that has not yet been transmitted. The threshold number may be predefined. Alternatively or additionally, the threshold number may be set via RRC or system messages or other control signaling. The threshold number may also be dynamically determined by the network device 220-1.

With knowledge of the TB elimination status reported from the terminal device 210-1, the network device 220-1 can keep track of the TB elimination process. The index of TBs that have been successfully eliminated or have not been successfully eliminated will give the network device 220-1 a clear guidance of which data portion should be forwarded so that the received TB combination (partially from network device 220-1 and partially from network device 220-2) provides the maximum TB combination redundancy gain at the cost of forwarding only a relatively small amount of data.

In one example, a 4/8 TB combined redundancy rate is selected, which means that a total of 4 original TBs, denoted as TB0, TB1, TB2, and TB3, can be sent over every 8 transmissions of the physical interface. The combination pattern is shown in table 4 below. It should be noted that the numbers and values shown in table 4 are merely examples and not limiting.

TABLE 4 Table 4

Transport instance #	TB combination to be transmitted	Buffer ID#)
			Network devices 220-1#1	TB0	0
Network devices 220-1#2	TB1	1
			Network devices 220-1#3	TB2+TB0	2
Network devices 220-1#4	TB3+TB1+TB0	3
			Network device 220-2#1	TB3+TB2	4
Network device 220-2#2	TB2	5
			Network device 220-2#3	TB3	6
Network devices 220-2#4	TB1+TB2	7

In the first example, it is assumed that TB0 and TB1 (corresponding to the first transmission and the second transmission from network device 220-1) are not received due to the degraded channel condition of the serving cell. Assume that the third and fourth transmissions from network device 220-1b were successful. Since there is no knowledge that neither TB0 nor TB1 performs TB cancellation, tb2+tb0 and tb3+tb1+tb0 may be stored only in buffers #2 and #3 to wait for additional combined TBs to arrive after switching to target network device 220-2 with the desire for improved wireless quality. In this example, only two of the four TB combinations need to be forwarded to network device 220-2 and sent to terminal device 210-1 after the handover, i.e. tb3+tb2 and TB2 in buffers #4 and #5 or tb3+tb2 and TB3 in buffers #4 and # 6. The corresponding TB elimination at the terminal device 210-1 side may be performed in the following order shown in table 5:

TABLE 5

Forwarding tb3+tb2 and TB2	Forwarding tb3+tb2 and TB3
		Buffer #5+ buffer # 2- > TB0	Buffer #6+ buffer # 4- & gtTB 2
Buffer #5+ buffer # 4- & gtTB 3	Buffer #2+TB2→TB0
		Buffer #3+TB0+TB3→TB1	Buffer #3+TB0+TB3→TB1

In another example, assume that the transmission of tb2+tb0 is absent at the third transmission instance. In this case, both TB0 and TB1 are degree-1 TB, so they are received 'as-is'. TB3 can then be obtained via the following formula: buffer #3+tb0+tb1→tb3. Thus, network device 220-1 may only have to forward one copy of the TB combination to network device 220-2 for the purpose of recovering TB2. The copy may be any of the following: tb3+Tb2; TB2; or Tb1+Tb2.

The terminal device may send 3070 an ACK to network device 220-1. The terminal device 210-1 may also detach 3080 from the network device 220-1. In some embodiments, the terminal device 210-1 may set a timer for the handover. The timer starts during transmission of RRC reconfiguration complete signaling. The duration of such a timer may be configured to be predefined by upper layers, system information, or RRC signaling.

When the timer expires, if the number of degree-1 TBs received by the terminal device 210-1 does not increase above a given boundary, it is considered an unsuccessful handover. The corresponding action of handling the failed HO may be triggered. It may be to return to the original serving cell (ping-pong) or initiate the RLF procedure. For example, at time t1 in fig. 4, terminal device 210-1 detaches from network device 220-1, and the new connection established with target network device 220-2 is expected to be more reliable and should remain improved over time, as illustrated by fig. 4. Under such an assumption, it is intuitive that more TB combinations should be predicted to be received correctly by the terminal device 210-1, whose further increasing number of darkness-1 TBs should be generated after HO. The handover may be more accurately decided, so embodiments of the present disclosure may reduce latency to a large extent, avoiding unnecessary or improper HO.

Fig. 5 illustrates a flowchart of an example method 500 implemented at a terminal device, according to some embodiments of the disclosure. Method 500 may be implemented at any suitable device. For discussion purposes, the method 500 will be described from the perspective of the terminal device 210-1 with reference to fig. 2.

At block 510, the terminal device 210-1 receives information regarding a configuration of a feedback-free transmission. The combined TB may be generated based on the original TB on which the data to be transmitted is carried.

The configuration may include one or more of the following: no feedback is transmitted redundancy rate, TB degree, or TB combined mode. The combined TB may be generated based on the original TB on which the data to be transmitted is carried. The feedback-free transmission redundancy rate may indicate a ratio of the number of original TBs to be communicated to the number of actually transmitted TB combinations. The TB degree may indicate the number of original TBs from which a particular TB combination is generated. The TB combination mode may indicate which original TBs are selected to generate a particular TB combination.

In some embodiments, this information may be part of the broadcast system information. In other embodiments, the information may be downlink control information. Alternatively, the information may be part of dedicated RRC signaling.

At block 520, the terminal device 210-1 sends a measurement report to the network device 220-1. The measurement report includes information reflecting the status of the transport block cancellation. In some embodiments, the measurement report includes one or more of the following: the number of degree-1 TBs obtained from the TB combination transmitted from the second device, the ratio of the original TBs successfully recovered from the TB combination, the ratio of the original TBs failed to be recovered from the TB combination, the index of the original TBs successfully recovered from the TB combination, or the index of the original TBs failed to be recovered from the TB combination. In some embodiments, the process of restoration of the original TB may also be referred to as "TB elimination".

In some embodiments, recovery of the original TB may rely on successful cancellation of the degree-1 TB from the received TB combination. During each cancellation, a freshness-1 TB must be generated to hold another cancellation in progress. When radio link conditions deteriorate or experience an interruption causing too many missing or erroneously received TB combinations, TB cancellation is likely to be suspended in the middle of the process, as the number of generated degree-1 TBs becomes insufficient to maintain the remaining part of the cancellation, most of the received TB combinations are thus not recoverable.

At block 530, the terminal device 210-1 receives an indication of a handover from the network device 220-1. In some embodiments, the terminal device 210-1 may receive information for another feedback-free transmission supported by the network device 220-2. The information may include a TB redundancy rate, a TB degree, or a TB combination mode. The TB redundancy rate may indicate a ratio of the number of combinations of the original TBs and the combined TBs to the number of the original TBs.

In some embodiments, the terminal device 210-1 may receive the synchronization signal of the terminal device 210-1. In some embodiments, the terminal device 210-1 may perform simultaneous reception of the synchronization signal from the network device 220-2 for initial access purposes while continuing data transmission with the network device 220-1. For example, the terminal device 210-1 may continue to send data to the network device 220-1. In some embodiments, the terminal device 210-1 may also send a new measurement report to the network device 220-1.

In some embodiments, the terminal device 210-1 may set a timer for the handover. The timer starts during transmission of RRC reconfiguration complete signaling. The duration of such a timer may be configured to be predefined by upper layers, system information, or RRC signaling. The terminal device 210-1 may detect a failure of handover by comparing the number of original TBs obtained from the third device with a threshold number. When the timer expires, if the number of the obtained original TBs does not increase above a given boundary, it is considered an unsuccessful handover.

Fig. 6 illustrates a flowchart of an example method 600 implemented at a terminal device, according to some embodiments of the disclosure. Method 600 may be implemented at any suitable device. For discussion purposes, the method 600 will be described from the perspective of the network side device 220-1 with reference to fig. 2.

At block 610, the network device 220-1 transmits information regarding the configuration of the feedback-free transmission. The combined TB may be generated based on the original TB on which the data to be transmitted is carried. The configuration may include one or more of the following: no feedback is transmitted redundancy rate, TB degree, or TB combined mode. The combined TB may be generated based on the original TB on which the data to be transmitted is carried. The feedback-free transmission redundancy rate may indicate a ratio of the number of original TBs to be communicated to the number of actually transmitted TB combinations. The TB degree may indicate the number of original TBs from which a particular TB combination is generated. The TB combination mode may indicate which original TBs are selected to generate a particular TB combination.

In some embodiments, the information may be part of broadcast system information. In other embodiments, the information may be downlink control information. Alternatively, the information may be part of dedicated RRC signaling.

In some embodiments, if the terminal device 210-1 is in the rrc_connected state, the terminal device 210-1 and the network device 220-1 may communicate with each other using feedback-free transmission due to the high latency of the air interface. For example, the network device 220-1 may send data to the terminal device 210-1 using feedback-free transmission.

In some embodiments, the network device 220-1 may send signaling to activate the feedback-free transmission. In some embodiments, the signaling may be an RRC message dedicated to the terminal device 210-1. Alternatively or additionally, the signalling may be broadcast to a plurality of terminal devices.

At block 620, the network device 220-1 receives a measurement report from the terminal device 210-1. The measurement report includes information reflecting the quality of the feedback-free transmission. In some embodiments, the measurement report includes one or more of the following: the number of degree-1 TBs obtained from the TB combination transmitted from the second device, the ratio of the original TBs successfully recovered from the TB combination, the ratio of the original TBs failed to be recovered from the TB combination, the index of the original TBs successfully recovered from the TB combination, or the index of the original TBs failed to be recovered from the TB combination. In some embodiments, the process of restoration of the original TB may also be referred to as "TB elimination".

At block 630, the network device 220-1 determines whether a handover is triggered based on the measurement report. The network device 220-1 may evaluate the measurement report and trigger a HO decision if the condition is met.

In some embodiments, the network device 220-1 may compare the quality of the feedback-free transmission to a threshold quality. If the quality exceeds a threshold quality, the network device 220-1 may trigger into a handoff state. If the quality is below the threshold quality, the network device 220-1 may not trigger into the handover state. The network device 220-1 may ignore the measurement report and remain monitored. Network device 220-1 may reconfigure feedback-free transmissions such as TB redundancy rate, TB degree, or TB combined mode. The network device 220-1 may also reconfigure other transmission parameters for future transmissions, such as MCS and transmit power.

At block 640, the network device 220-1 determines the network device 220-2 as the target network device. The network device 220-1 may search for neighboring network devices whose trajectories may be aligned with the coverage area of the terminal device 210-1 for a given window. For example, the network device 220-1 may determine the target network device based on the speed of the terminal device 210-1, the direction of movement of the terminal device 210-1 and the dynamic neighbor cell set. After network device 220-1 determines network device 220-2 as the target network device, network device 220-1 may send a handoff request to network device 220-2.

In some embodiments, network device 220-1 may receive an Acknowledgement (ACK) of the handover request from network device 220-2. In some embodiments, the ACK may also include configuration information for another feedback-free transmission supported by network device 220-2. For example, the ACK may include one or more of a TB redundancy rate, a TB degree, or a TB combined mode. The TB redundancy rate may indicate a ratio of the number of combinations of the original TBs and the combined TBs to the number of the original TBs. In some embodiments, the network device 220-1 may forward information of another feedback-free transmission to the terminal device 210-1. The network device 220-2 may send an indication to the terminal device 210-1 to switch to the network device 220-2.

In some embodiments, network device 220-1 may forward data buffered in network device 220-1 for future transmission from network device 220-1 to network device 220-2. For example, if the number of degree-1 TBs received by terminal device 210-1 decreases, network device 220-1 may forward data that has not yet been transmitted. Alternatively or additionally, if the number of degree-1 TBs received by terminal device 210-1 is below a threshold number, network device 220-1 may forward data that has not yet been transmitted. The threshold number may be predefined. Alternatively or additionally, the threshold number may be set via RRC or system messages or other control signaling. The threshold number may also be dynamically determined by the network device 220-1.

Fig. 7 illustrates a flowchart of an example method 700 implemented at a terminal device, according to some embodiments of the disclosure. Method 700 may be implemented at any suitable device. For discussion purposes, the method 700 will be described from the perspective of the terminal device 220-2 with reference to fig. 2.

At block 710, the network device 220-2 receives a handoff request from the network device 220-1.

At block 720, the network device 220-2 generates an ACK for the handover request. In some embodiments, the ACK may also include configuration information for another feedback-free transmission supported by network device 220-2. For example, the ACK may include one or more of the following: no feedback is transmitted redundancy rate, TB degree, or TB combined mode. The TB redundancy rate may indicate a ratio of the number of original TBs to be communicated to the number of actually transmitted TB combinations.

At block 730, network device 220-2 sends an ACK to network device 220-1. At block 740, the network device 220-2 sends a synchronization signal to the terminal device 210-1.

In some embodiments, an apparatus (e.g., network device 210-1) for performing method 500 may include corresponding components for performing corresponding steps in method 500. These components may be implemented in any suitable manner. For example, it may be implemented by circuitry or software modules.

In some embodiments, the apparatus comprises: means for receiving, at the first device, information from the second device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of a feedback-based retransmission; means for transmitting a measurement report to the second device comprising information reflecting the quality of the feedback-free transmission; and means for receiving an indication from the second device to switch to the third device, the switch being triggered based on information reflecting the quality of the feedback-free transmission.

In some embodiments, the configuration of feedback-free transmission includes at least one of: a feedback-free transmission redundancy rate indicating a ratio of a number of original TBs to be communicated to a number of actually transmitted TB combinations; a TB degree indicating the number of original TBs from which a particular TB combination is generated; or a TB combination pattern indicating which original TBs are selected to generate a particular TB combination.

In some embodiments, the measurement report includes at least one of: the number of degree-1 TBs obtained from the TB combination transmitted from the second device, the ratio of the original TBs successfully recovered from the TB combination, the ratio of the original TBs failed to be recovered from the TB combination, the index of the original TBs successfully recovered from the TB combination, or the index of the original TBs failed to be recovered from the TB combination.

In some embodiments, the means for receiving, from the second device, an indication of a handoff from the second device to the third device comprises: means for receiving further information from the second device regarding a further configuration of a further feedback-less transmission supported by the third device.

In some embodiments, the apparatus further comprises: means for transmitting data to the second device while receiving a synchronization signal from the third device; and means for sending further data to the third device in response to receiving a further indication to perform the handover.

In some embodiments, the apparatus further comprises: means for setting a timer for switching to the third device; means for determining a number of degree-1 TBs obtained from a TB combination transmitted from the third device after expiration of the timer; and means for detecting a failure of the handover by comparing the number of degree-1 TBs obtained from the TB combination transmitted from the third device with a threshold number.

In some embodiments, the first device comprises a terminal device, the second device comprises a network device, and the second device comprises a further network device.

In some embodiments, an apparatus (e.g., network device 220-1) for performing method 600 may include respective components for performing corresponding steps in method 600. These components may be implemented in any suitable manner. For example, it may be implemented by circuitry or software modules.

In some embodiments, the apparatus comprises: means for transmitting information from the second device to the first device regarding a configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of a feedback-based retransmission; means for receiving a measurement report from the first device comprising information reflecting the quality of the feedback-free transmission; means for determining whether a handover is triggered based on information reflecting the quality of the feedback-free transmission; and means for determining a third device for handover in response to a determination that handover is triggered.

In some embodiments, the means for determining whether a handover is triggered comprises: means for determining that a handover is triggered in response to the information indicating that the quality of the feedback-free transmission is below a threshold quality.

In some embodiments, the apparatus further comprises means for forwarding data buffered in the second device for future transmission to the third device in response to at least one of: the number of degree-1 TBs received by the first device is reduced or the number of degree-1 TBs received by the first device is below a threshold number.

In some embodiments, the apparatus further comprises means for receiving, from the third device, additional information regarding additional configurations of additional feedback-free transmissions supported by the third device; and means for forwarding the further information to the first device.

In some embodiments, an apparatus (e.g., network device 220-2) for performing method 700 may include respective components for performing corresponding steps in method 700. These components may be implemented in any suitable manner. For example, it may be implemented by circuitry or software modules.

In some embodiments, the apparatus comprises: means for receiving, at the third device, a handover request from the second device indicating that the first device is to be handed over to the third device; means for generating an acknowledgement of the handover request, the acknowledgement comprising information about the configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks, TBs, generated based on an original TB on which data to be transmitted is carried, instead of a feedback-based retransmission; means for sending an acknowledgement to the second device; and means for sending a synchronization signal to the first device for handover.

Fig. 8 is a simplified block diagram of a device 800 suitable for implementing embodiments of the present disclosure. Device 800 may be provided to implement a communication device, such as network device 120 or terminal device 110-1 as shown in fig. 1. As shown, device 800 includes one or more processors 810, one or more memories 820 coupled to processor 810, and one or more communication modules (e.g., transmitter and/or receiver (TX/RX)) 840 coupled to processor 810.

The communication module 840 is used for two-way communication. The communication module 840 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary to communicate with other network elements.

The processor 810 may be of any type suitable to the local technology network and may include, as non-limiting examples, one or more of the following: general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs), and processors based on a multi-core processor architecture. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to the clock of the synchronous master processor.

Memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memory include, but are not limited to, read-only memory (ROM) 824, electrically programmable read-only memory (EPROM), flash memory, a hard disk, a Compact Disc (CD), a Digital Video Disc (DVD), and other magnetic and/or optical storage devices. Examples of volatile memory include, but are not limited to, random Access Memory (RAM) 822 and other volatile memory that does not persist during shutdown.

The computer program 830 includes computer-executable instructions that are executed by an associated processor 810. Program 830 may be stored in ROM 824. Processor 810 may perform any suitable actions and processes by loading program 830 into RAM 822.

Embodiments of the present disclosure may be implemented by means of program 830 such that device 800 may perform any of the processes of the present disclosure as discussed with reference to fig. 3-6. Embodiments of the present disclosure may also be implemented in hardware or by a combination of software and hardware.

In some embodiments, program 830 may be tangibly embodied in a computer-readable medium that may be included in device 800 (such as in memory 820) or other storage device accessible by device 800. Device 800 may load program 830 from a computer readable medium into RAM 822 for execution. The computer readable medium may include any type of tangible, non-volatile storage device, such as ROM, EPROM, flash memory, hard disk, CD, DVD, and the like. Fig. 9 shows an example of a computer readable medium 900 in the form of a CD or DVD. The computer readable medium has a program 830 stored thereon.

In general, the various embodiments of the 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 the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods 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 comprises computer executable instructions (such as those included in program modules) that are executed in a device on a target real or virtual processor to perform the methods 500 through 700 as described above with reference to fig. 5 through 7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. 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 embodiments. Machine-executable instructions for program modules may be executed within local or distributed devices. In a distributed device, program modules may be located in both local and remote memory storage media.

Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program code 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 code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely or in part on the machine, as a stand-alone software package, partly on the machine, partly on a remote machine, or entirely on the remote machine or server.

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

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is 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 a 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.

In addition, although 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 some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the 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

1. A first device, comprising:

at least one processor; and

at least one memory including computer program code;

The at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to:

receiving, at the first device, from a second device, information about a configuration of a feedback-free transmission using one or more combined transport blocks (TBs) instead of feedback-based retransmissions, the combined TBs being generated based on original TBs on which data to be transmitted is carried;

sending a measurement report including information reflecting the quality of the feedback-free transmission to the second device; and

An indication is received from the second device to switch to a third device, the switching being triggered based on the information reflecting the quality of the feedback-free transmission.

2. The first device according to claim 1, wherein the configuration of the feedback-free transmission comprises at least one of the following:

a no-feedback transmission redundancy ratio indicating a ratio of the number of the original TBs to be communicated to the number of TB combinations actually sent,

a TB degree indicating the number of the original TBs from which a particular TB combination was generated, or

A TB combination mode indicating which original TBs are selected to generate a specific TB combination.

3. The first device according to claim 1, wherein the measurement report comprises at least one of the following:

the number of terabytes obtained from the combination of terabytes sent from the second device,

The ratio of successful recovery of original TB from TB combination,

The rate at which the original TB is not recovered from the TB portfolio,

The index of the original TB successfully restored from the TB combination, or

Index of the original TB that failed to be restored from the TB combination.

4. The first device according to claim 1, wherein the first device is configured to receive the instruction to switch to the third device from the second device by:

Further information is received from the second device regarding further configurations of further feedback-free transmissions supported by the third device.

5. The first device according to claim 1, wherein the first device is further configured to:

sending data to the second device while receiving a synchronization signal from the third device; and

In response to receiving a further indication to perform the handover, further data is sent to the third device.

6. The first device according to claim 1, wherein the first device is further configured to:

Setting a timer for switching to the third device;

After the timer expires, determining the number of degree-1 TBs obtained from the TB combination sent from the third device; and

The failure of the switching is detected by comparing the number of degree-1 TBs obtained from the TB combination sent from the third device with a threshold number.

7. The first device of claim 1, wherein the first device comprises a terminal device, the second device comprises a network device, and the second device comprises another network device.

8. A second device, comprising:

at least one processor; and

at least one memory including computer program code;

The at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to:

sending, from the second device to the first device, information about configuration of a feedback-free transmission, the feedback-free transmission using one or more combined transport blocks TB instead of feedback-based retransmission, the combined TB being generated based on an original TB on which data to be transmitted is carried;

receiving, from the first device, a measurement report including information reflecting the quality of the feedback-free transmission;

determining whether a handover is triggered based on the information reflecting the quality of the feedback-free transmission; and

In response to determining that the handover is triggered, a third device is determined for the handover.

9. The second device according to claim 8, wherein the configuration of the feedback-free transmission comprises at least one of the following:

10. The second device according to claim 8, wherein the measurement report comprises at least one of the following:

The ratio of successful recovery of original TB from TB combination,

The rate at which the original TB is not recovered from the TB portfolio,

The index of the original TB successfully restored from the TB combination, or

Index of the original TB that failed to be restored from the TB combination.

11. The second device according to claim 8, wherein the second device is configured to determine whether the switching is triggered by:

In response to the information indicating that the quality of the feedback-free transmission is below a threshold quality, determining that the handover is triggered.

12. The second device according to claim 8, wherein the second device is further configured to:

In response to at least one of the following being satisfied, forwarding data buffered in the second device for future transmission to the third device:

the number of degree-1TBs received by the first device decreases, or

The number of terabytes received by the first device is below a threshold number.

13. The second device according to claim 8, wherein the second device is further caused to:

receiving, from the third device, further information regarding further configurations of further feedback-free transmissions supported by the third device; and

The further information is forwarded to the first device.

14. The second device of claim 8, wherein the first device comprises a terminal device, the second device comprises a network device, and the second device comprises another network device.

15. A third device, comprising:

at least one processor; and

at least one memory including computer program code;

The at least one memory and the computer program code are configured to, with the at least one processor, cause the third device to:

receiving, at the third device, from the second device a handover request indicating that the first device is to be handed over to the third device;

generating an acknowledgement to the switching request, the acknowledgement including information about a configuration of a feedback-free transmission using one or more combined transport blocks (TBs) instead of feedback-based retransmissions, the combined TBs being generated based on original TBs on which data to be transmitted is carried;

sending the confirmation to the second device; and

A synchronization signal is sent to the first device for the switching.

16. The third device according to claim 15, wherein the configuration of the feedback-free transmission comprises at least one of the following:

17. The third device according to claim 15, wherein the first device comprises a terminal device, the second device comprises a network device, and the second device comprises another network device.

18. A method comprising:

receiving, at the first device, from the second device, information about a configuration of a feedback-free transmission using one or more combined transport blocks (TBs) instead of feedback-based retransmissions, the combined TBs being generated based on original TBs on which data to be transmitted is carried;

19. The method of claim 18, wherein the configuration of the feedback-free transmission comprises at least one of:

20. The method of claim 18, wherein the measurement report comprises at least one of the following:

The ratio of successful recovery of original TB from TB combination,

The rate at which the original TB is not recovered from the TB portfolio,

The index of the original TB successfully restored from the TB combination, or

Index of the original TB that failed to be restored from the TB combination.

21. The method of claim 18, wherein receiving from the second device the indication of switching from the second device to the third device comprises:

22. The method of claim 18, further comprising:

23. The method of claim 18, further comprising:

Setting a timer for switching to the third device;

24. The method of claim 18, wherein the first device comprises a terminal device, the second device comprises a network device, and the second device comprises another network device.

25. A method comprising:

sending, from the second device to the first device, information about a configuration of a feedback-free transmission using one or more combined transport blocks TBs instead of feedback-based retransmissions, the combined TBs being generated based on original TBs on which data to be transmitted is carried;

26. The method of claim 25, wherein the configuration of the feedback-free transmission comprises at least one of:

27. The method of claim 25, wherein the measurement report comprises at least one of the following:

The ratio of successful recovery of original TB from TB combination,

The rate at which the original TB is not recovered from the TB portfolio,

The index of the original TB successfully restored from the TB combination, or

Index of the original TB that failed to be restored from the TB combination.

28. The method of claim 25, wherein determining whether the switching is triggered comprises:

29. The method of claim 25, further comprising:

the number of degree-1TBs received by the first device decreases, or

30. The method of claim 25, further comprising:

The further information is forwarded to the first device.

31. The method of claim 25, wherein the first device comprises a terminal device, the second device comprises a network device, and the second device comprises another network device.

32. A method comprising:

receiving, at a third device, from a second device, a handover request indicating that the first device is to be handed over to the third device;

sending the confirmation to the second device; and

A synchronization signal is sent to the first device for the switching.

33. The method of claim 32, wherein the configuration of the feedback-free transmission comprises at least one of:

34. The method of claim 32, wherein the first device comprises a terminal device, the second device comprises a network device, and the second device comprises another network device.

35. An apparatus comprising:

means for receiving, at the first device, from the second device, information regarding configuration of feedback-free transmissions using one or more combined transport blocks (TBs) instead of feedback-based retransmissions, the combined TBs being generated based on original TBs on which data to be transmitted are carried;

means for sending a measurement report including information reflecting the quality of the feedback-free transmission to the second device; and

means for receiving an indication from the second device to switch to a third device, the switching being triggered based on the information reflecting the quality of the feedback-free transmission.

36. An apparatus comprising:

means for sending, from the second device to the first device, information about a configuration of a feedback-free transmission using one or more combined transport blocks TB instead of feedback-based retransmissions, the combined TB being generated based on an original TB on which data to be transmitted is carried;

for receiving, from the first device, a measurement report including information reflecting the quality of the feedback-free transmission;

means for determining whether handover is triggered based on said information reflecting said quality of said feedback-free transmission; and

Means for determining a third device to use for the handover in response to determining that the handover is triggered.

37. An apparatus comprising:

means for receiving, at a third device, from a second device, a handover request indicating that the first device is to be handed over to said third device;

means for generating an acknowledgement of the handover request, the acknowledgement comprising information about a configuration of a feedback-free transmission using one or more combined transport blocks (TBs) instead of feedback-based retransmissions, the combined TBs being generated based on original TBs on which data to be transmitted are carried;

means for sending said confirmation to said second device; and

Means for sending a synchronization signal to the first device for use in the switching.

38. A computer readable medium having stored thereon instructions which, when executed by at least one processing unit of a machine, cause the machine to perform the method according to any one of claims 18 to 24.

39. A computer readable medium having stored thereon instructions which, when executed by at least one processing unit of a machine, cause the machine to perform the method according to any one of claims 25 to 31.

40. A computer readable medium having stored thereon instructions which, when executed by at least one processing unit of a machine, cause the machine to perform the method according to any one of claims 32 to 34.