WO2018122609A2

WO2018122609A2 - Method and device for feedback of grant-free transmission based on resource unit

Info

Publication number: WO2018122609A2
Application number: PCT/IB2017/001723
Authority: WO
Inventors: Hua Chao
Original assignee: Alcatel Lucent
Priority date: 2016-12-26
Filing date: 2017-12-22
Publication date: 2018-07-05
Also published as: CN108242970A; WO2018122609A3; CN108242970B

Abstract

The present disclosure discloses a method and device for feedback of grant-free transmission based on a resource unit, the feedback method comprising: a network-side device receiving from at least one user terminal uplink data sent on a resource unit for grant-free transmission, and performing data processing on the uplink data; the network-side device sending feedback information on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission according to a result of the data processing. The method proposes feedback based on a resource unit, which can effectively reduce feedback signaling overhead, combine fast feedback and retransmission, improve the feedback efficiency and increase the success rate of retransmission combining.

Description

METHOD AND DEVICE FOR FEEDBACK OF GRANT-FREE TRANSMISSION BASED ON RESOURCE UNIT

FIELD

[0001] Embodiments of the present disclosure generally relate to the field of wireless communication, and more particularly, to a method and device for feedback of grant-free transmission based on a resource unit in the field of wireless communication.

BACKGROUND

[0002] In new research projects on new wireless air interface access technologies in 3GPP 5G, non-orthogonal multiple access technologies of grant-free based uplink are characterized in that uplink transmission of the user terminals (UE) does not need any dynamic or explicit scheduling grant from gNB (that is, 5G base station), which means that the uplink transmission of the UE is grant-free. Multiple UEs may share the same time and frequency resources. 3GPP will continue study the following:

[0003] — Handling of potential collisions of MA signatures; [0004] — Retransmission/repetition and its potential combining, for example Hybrid Automatic Repeat Request (HARQ).

[0005] In 3GPP proposals, the one-step and two-step grant-free transmission solutions are proposed, just as shown in Fig. 1. In this disclosure, feedback of grant- free transmission is referred to as grant-free feedback. Fast HARQ feedback of grant- free transmission may be applied in the one-step transmission procedure. That is, after decoding the preamble, a network-side device, for example a Transmission Reception Point (TRP) may feed the preamble back to UE before decoding data. However, several technical problems in retransmission design need to be solved:

[0006] 1. How to make a certain UE be learned that HARQ feedback from the network is sent to itself?

[0007] 2. How to design feedback signaling for UE and to reduce signaling overhead and latency?

[0008] 3. How to arrange retransmission for possible HARQ combining?

[0009] For the first problem, in the prior art such as LTE or LTE-A systems, HARQ feedback is directed to a UE, and each feedback information carries information of the UE, so that each UE may detect HARQ feedback sent to itself. However, for the grant-free transmission, multiple UEs may share the same time-frequency resources for uplink transmission. If TRP allocates a separate PHICH (that is, physical HARQ indicator channel) or separate feedback information for each UE, signaling overhead will be extremely high.

[0010] For the second problem, the prior art applies fast feedback in one-step transmission. However, the ID of preamble is also included in feedback signaling to indicate which preamble is detected by TRP, and therefore the signaling overhead is also high. In the two-step transmission solution, both the ID of preamble and the user ID must be included in feedback signaling to indicate which preamble is detected by UE and which UE has its user data correctly received. Therefore, signaling overhead is also very high.

[0011] For the third problem, in the existing 3GPP proposal Rl-1609783, "Transmission Options for the mMTC Grant-Free Uplink," it is proposed to set a fixed offset between retransmission and the first transmission to achieve HARQ combining. However, this solution also requires separate preamble feedback and data feedback, which leads to high signaling overhead. For the one-step transmission, this solution is not required. Specifically, this solution does not consider collision conditions; in some cases of the one-step transmission in which for example different UEs send different preambles on the same time-frequency resource and TRP cannot correctly decode data, all retransmission from the UEs with fixed time offsets will collide, and HARQ combining cannot be realized.

SUMMARY

[0012] Regarding grant-free transmission, the present disclosure creatively proposes design of feedback based on a resource unit, making a breakthrough in UE based feedback design in the prior art.

[0013] According to a first aspect of the present disclosure, there is provided a method for feedback of grant-free transmission based on a resource unit. The method comprises a network-side device receiving from at least one user terminal uplink data sent on a resource unit for grant-free transmission; the network-side device performing data processing on the uplink data; the network-side device sending feedback information on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission according to a result of the data processing. [0014] According to one embodiment of the present disclosure, the uplink data comprises data information and preamble of at least one user terminal; the network-side device performing data processing on the uplink data comprises detecting the preamble, and according to a detecting of the preamble, the network-side device determines whether the data information needs to be decoded, and if the network-side device determines the data information needs to be decoded, the network-side device further decodes the data information.

[0015] According to one embodiment of the present disclosure, the network-side device sending feedback information on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission according to a result of the data processing comprises: in response to at least one preamble being detected during detection of the preamble from the uplink data at the network- side device, and data information of at least one user terminal being successfully decoded, sending, at the network-side device, first feedback information on the feedback resource for the grant-free transmission feedback; in response to at least one preamble being detected during detection of the preamble from the uplink data at the network- side device, and data information of at least one user terminal being unsuccessfully decoded, sending, at the network-side device, second feedback information on the feedback resource for the grant-free transmission feedback; in response to at least two preambles being detected during detection of the preamble from the uplink data at the network- side device and that the network- side device determines the data information cannot be correctly decoded, sending, at the network-side device, third feedback information on the feedback resource for the grant- free transmission feedback without decoding the data information; and in response to no preamble being detected during detection of the preamble from the uplink data at the network- side device, sending, at the network- side device, fourth feedback information on the feedback resource for the grant-free transmission feedback without decoding the data information.

[0016] According to one embodiment of the present disclosure, the network-side device, when sending first feedback information, further sends user ID information of the correctly decoded data information.

[0017] According to one embodiment of the present disclosure, the first feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is correctly decoded does not need to re-transmit the uplink data, while a user terminal which transmits uplink data on a resource unit for grant- free transmission and whose data information is not correctly decoded re-transmits the uplink data; the second feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data; the third feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data; the fourth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

[0018] According to one embodiment of the present disclosure, the first feedback information is further used to indicate that a user terminal which transmits uplink data on a resource unit for grant- free transmission and whose data information is not correctly decoded re-transmits the uplink data with fixed time offsets; the second feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data with fixed time offsets; the third feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant- free transmission re-transmits the uplink data with a random backoff; the fourth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a random backoff.

[0019] According to one embodiment of the present disclosure, when the network-side device sends first feedback information, the network-side device sends the first feedback information at fixed time offsets from a current subframe when the uplink data is received; when the network-side device sends the second feedback information, the network-side device sends the second feedback information at fixed time offsets from a current subframe when the uplink data is received; when the network- side device sends third feedback information, the network-side device sends the third feedback information on a subframe next to a current subframe when the uplink data is received; when the network- side device sends fourth feedback information, the network-side device sends the fourth feedback information on a subframe next to a current subframe when the uplink data is received.

[0020] According to one embodiment of the present disclosure, the uplink data comprises data information of at least one user terminal; the network-side device performing data processing on the uplink data comprising decoding data information, and if the network-side device successfully decodes data information of at least one user terminal, the network-side device sends the fifth feedback information on the resource unit for grant-free transmission feedback; if the network- side device fails to decode data information from a user terminal, the network-side device sends the sixth feedback information on the resource unit for grant-free transmission feedback.

[0021] According to one embodiment of the present disclosure, the network-side device, before receiving from at least one user terminal uplink data sent on a resource unit for grant-free transmission, further receives a preamble of at least one user terminal and decodes the preamble.

[0022] According to one embodiment of the present disclosure, if the network-side device correctly decodes a preamble, the network-side device sends seventh feedback information and ID detected from preamble to indicate that a user terminal which has sent the preamble with the ID sends the uplink data information.

[0023] According to one embodiment of the present disclosure, when sending fifth feedback information, the network- side device further sends user ID information of the correctly decoded data information.

[0024] According to one embodiment of the present disclosure, the fifth feedback information is used to indicate that the user terminal whose data information has been correctly decoded does not need to re-transmit the uplink data; the sixth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

[0025] According to one embodiment of the present disclosure, the network-side device sends the fifth feedback information or the sixth feedback information at fixed time offsets from a current subframe when the uplink data is received; the network-side device sends seventh feedback information within a feedback window in which the preamble of the user terminal is received.

[0026] According to a second aspect of the present disclosure, there is provided a method for feedback of grant-free transmission based on a resource unit, comprising: a user terminal sending uplink data on a resource unit for grant-free transmission; receiving from a network-side device feedback information sent on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission; and the user terminal re-transmitting the uplink data which has been sent according to the feedback information.

[0027] According to one embodiment of the present disclosure, the uplink data comprises a preamble and data information.

[0028] According to one embodiment of the present disclosure, if the user terminal receives first feedback information, the user terminal further detects whether its own user ID is received; the user terminal does not perform retransmission if receiving its own user ID; the user terminal re-transmits the uplink data on a resource unit for grant-free transmission if not receiving its own user ID; if the user terminal receives second feedback information, the user terminal re-transmits the uplink data on a resource unit for grant-free transmission; if the user terminal receives third feedback information, the user terminal re-transmits the uplink data on a resource unit for grant-free transmission; and if the user terminal receives fourth feedback information, the user terminal re-transmits the uplink data on a resource unit for grant-free transmission.

[0029] According to one embodiment of the present disclosure, if the user terminal receives first feedback information and does not receive its own user ID, the user terminal re-transmits the uplink data with fixed time offsets on a resource unit for grant-free transmission; if the user terminal receives second feedback information, the user terminal re-transmits the uplink data with fixed time offsets on a resource unit for grant-free transmission; if the user terminal receives third feedback information, the user terminal re-transmits the uplink data with a random backoff on a resource unit for grant-free transmission; and if the user terminal receives fourth feedback information, the user terminal re-transmits the uplink data with a random backoff on a resource unit for grant-free transmission.

[0030] According to one embodiment of the present disclosure, the uplink data comprises data information.

[0031] According to one embodiment of the present disclosure, if the user terminal receives fifth feedback information, the user terminal further detects whether its own user ID is received; the user terminal does not perform retransmission if receiving its own user ID; the user terminal re-transmits the uplink data on a resource unit for grant-free transmission if not receiving its own user ID; and if the user terminal receives sixth feedback information, the user terminal re-transmits the uplink data on a resource unit for grant-free transmission.

[0032] According to one embodiment of the present disclosure, the user terminal re-transmits the uplink data with fixed time offsets on a resource unit for grant-free transmission.

[0033] According to one embodiment of the present disclosure, before the user terminal sending uplink data on a resource unit for grant-free transmission, there is further comprised: sending a preamble andreceiving from the network-side device, feedback information of the preamble.

[0034] According to one embodiment of the present disclosure, if the user terminal receives seventh feedback information, the user terminal further detects whether its own ID of preamble is received; the user terminal sends the uplink data on a resource unit for grant-free transmission if receiving the ID of its own preamble; the user terminal re- sending a preamble if not receiving the ID of its own preamble.

[0035] According to a third aspect of the present disclosure, there is provided a network-side device, the network-side device being used for feedback of grant-free transmission based on a resource unit, comprising: a receiving unit configured to receive from at least one user terminal uplink data sent on a resource unit for grant-free transmission; a data processing unit configured to perform data processing on the uplink data; a feedback unit configured to send feedback information on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission according to a result of the data processing.

[0036] According to one embodiment of the present disclosure, the uplink data comprises data information and a preamble of at least one user terminal; the data processing unit comprises a preamble detecting unit configured for preamble detecting; the network- side device further comprises a determining unit configured to, according to a detecting of the preamble detecting unit, determine whether the data information needs to be decoded; the data processing unit further comprises a data decoding unit configured to decode data information.

[0037] According to one embodiment of the present disclosure, the feedback unit sending feedback information comprises one of the following: when the preamble detecting unit detects at least one preamble and the data decoding unit successfully decodes data information of at least one user terminal, the feedback unit sending first feedback information on the feedback resource for grant-free transmission feedback; when the preamble detecting unit detects at least one preamble and the data decoding unit fails to decode data information, the feedback unit sending second feedback information on the feedback resource for grant-free transmission feedback; when the preamble detecting unit detects at least two preambles and the determining unit determines data information cannot be correctly decoded, the data decoding unit does not decode the data information and the feedback unit sending third feedback information on the feedback resource for grant-free transmission feedback; and when the preamble detecting unit fails to detect any preamble, the data decoding unit does not decode data information and the feedback unit sending fourth feedback information on the feedback resource for grant-free transmission feedback.

[0038] According to one embodiment of the present disclosure, the feedback unit, when sending first feedback information, is further configured to send user ID information of the correctly decoded data information.

[0039] According to one embodiment of the present disclosure, the first feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is correctly decoded does not need to re-transmit the uplink data, while a user terminal which transmits uplink data on a resource unit for grant- free transmission and whose data information is not correctly decoded re-transmits the uplink data; the second feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data; the third feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data; the fourth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

[0040] According to one embodiment of the present disclosure, the first feedback information is further used to indicate that a user terminal which transmits uplink data on a resource unit for grant- free transmission and whose data information is not correctly decoded re-transmits the uplink data with fixed time offsets; the second feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data with fixed time offsets; the third feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant- free transmission re-transmits the uplink data with a random backoff; the fourth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a random backoff.

[0041] According to one embodiment of the present disclosure, when the feedback unit is configured to send first feedback information, the feedback unit is configured to send the first feedback information at fixed time offsets from a current subframe when the uplink data is received; when the feedback unit is configured to send second feedback information, the feedback unit is configured to send the second feedback information at fixed time offsets from a current subframe when the uplink data is received; when the the feedback unit is configured to send third feedback information, the feedback unit is configured to send the third feedback information on a subframe next to a current subframe when the uplink data is received; when the feedback unit is configured to send fourth feedback information, the feedback unit is configured to send the fourth feedback information on a subframe next to current subframe when the uplink data is received.

[0042] According to one embodiment of the present disclosure, the uplink data comprises data information of at least one user terminal; the data processing unit is configured to perform data processing on the uplink data comprising decoding data information, and if the data processing unit successfully decodes data information of at least one user terminal, the feedback unit is configured to send fifth feedback information on the resource unit for grant-free transmission feedback; if the data processing unit fails to decode data information from a user terminal, the feedback unit is configured to send sixth feedback information on the resource unit for grant-free transmission feedback.

[0043] According to one embodiment of the present disclosure, further, the receiving unit is configured to, before receiving from at least one user terminal uplink data sent on a resource unit for grant-free transmission, receive a preamble of at least one user terminal and output the preamble to the preamble detecting unit for preamble decoding.

[0044] According to one embodiment of the present disclosure, if the preamble detecting unit correctly decodes a preamble, the feedback unit is configured to send seventh feedback information and ID detected from the preamble to indicate that a user terminal which has sent the preamble with the ID sends the uplink data information.

[0045] According to one embodiment of the present disclosure, when the feedback unit is configured to send the fifth feedback information, the feedback unit is further configured to further send user ID information of the correctly decoded data information.

[0046] According to one embodiment of the present disclosure, the fifth feedback information is used to indicate that the user terminal whose data information has been correctly decoded does not need to re-transmit the uplink data; the sixth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data. [0047] According to one embodiment of the present disclosure, the feedback unit is configured to send the fifth feedback information or the sixth feedback information at fixed time offsets from a current subframe when the uplink data is received; the feedback unit is configured to send the seventh feedback information within a feedback window in which the preamble of the user terminal is received.

[0048] According to a fourth aspect of the present disclosure, there is provided a user terminal for feedback of grant-free transmission based on a resource unit, comprising: a transmitting unit configured to transmit uplink data on a resource unit for grant-free transmission; a receiving unit configured to receive from a network-side device feedback information sent on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission; anda re-transmitting unit configured to re-transmit the uplink data which has been sent according to the feedback information.

[0049] According to one embodiment of the present disclosure, the uplink data comprises a preamble and data information.

[0050] According to one embodiment of the present disclosure, there is further comprised a user ID detecting unit configured to, if the receiving unit receives first feedback information, detect whether its own user ID is received; if its own user ID is received, the re-transmitting unit does not perform retransmission; if its own user ID is not received, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission; if the receiving unit receives second feedback information, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission; if the receiving unit receives third feedback information, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission;if the receiving unit receives a fourth feedback information, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission.

[0051] According to one embodiment of the present disclosure, if the receiving unit receives the first feedback information and the user ID detecting unit does not detect its own user ID, the re-transmitting unit is configured to re-transmit the uplink data with fixed time offsets on a resource unit for grant-free transmission; if the receiving unit receives the second feedback information, the re-transmitting unit is configured to re-transmit the uplink data with fixed time offsets on a resource unit for grant-free transmission; if the receiving unit receives the third feedback information, the re-transmitting unit is configured to re-transmit the uplink data with a random backoff on a resource unit for grant-free transmission; and if the receiving unit receives the fourth feedback information, the re-transmitting unit is configured to re-transmit the uplink data with a random backoff on a resource unit for grant-free transmission.

[0052] According to one embodiment of the present disclosure, the uplink data comprises data information.

[0053] According to one embodiment of the present disclosure, there is further comprised a user ID detecting unit configured to further detect whether its own user ID is received; where the receiving unit receives fifth feedback information, if the user ID detecting unit detects its own user ID, the re-transmitting unit does not perform retransmission; if the user ID detecting unit does not detect its own user ID, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission; if the receiving unit receives sixth feedback information, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission.

[0054] According to one embodiment of the present disclosure, the re-transmitting unit is configured to re-transmit the uplink data with fixed time offsets on a resource unit for grant-free transmission.

[0055] According to one embodiment of the present disclosure, the sending unit is further configured to send a preamble before ending uplink data on a resource unit for grant-free transmission; the receiving unit is further configured to receive from the network-side device feedback information of the preamble.

[0056] According to one embodiment of the present disclosure, there is further comprised a preamble ID detecting unit; if the receiving unit receives seventh feedback information, the preamble ID detecting unit is further configured to detect whether an ID of its own preamble is received; if the ID of its own preamble is received, the sending unit is configured to transmit the uplink data on a resource unit for grant-free transmission; if the ID of its own preamble is not received, the sending unit is configured to re-send a preamble.

[0057] According to a fifth aspect of the present disclosure, there is provided a resource allocation method in a wireless network, the wireless network comprising a network-side device and at least one user terminal, the network- side device allocating a resource unit for grant-free uplink transmission for the user terminal and allocating a feedback resource for grant-free feedback for the network-side device, the resource unit for grant-free uplink transmission for the user terminal having a corresponding relationship with the feedback resource for grant-free feedback for the network-side device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Other features, objects and advantages of the present disclosure will become more apparent from the following detailed illustration of the non-limiting embodiments, when taken in conjunction with the accompanying drawings:

[0059] Fig. la shows a schematic flowchart of one-step transmission;

[0060] Fig. lb shows a schematic flowchart of two-step transmission;

[0061] Fig. 2 shows a corresponding relationship between resource units for grant-free transmission and resources for grant-free feedback;

[0062] Fig. 3 shows a flowchart of the processing at a network-side device for feedback based on a resource unit in one-step transmission;

[0063] Fig. 4 shows a flowchart of the processing at a network-side device for feedback based on a resource unit in two-step transmission; [0064] Fig. 5 shows a flowchart of the processing at a user terminal for feedback based on a resource unit in one-step transmission;

[0065] Fig. 6 shows a flowchart of the processing at a user terminal for feedback based on a resource unit in two-step transmission;

[0066] Fig. 7 shows a structural block diagram of a network-side device for feedback based on a resource unit;

[0067] Fig. 8 shows a structural block diagram of a user terminal for feedback based on a resource unit; and

[0068] Fig. 9 shows features and meaning of feedback information for grant- free feedback.

DETAILED DESCRIPTION OF EMBODIMENTS

[0069] In the following detailed description of preferred embodiments, reference will be made to the accompanying drawings which constitute part of the present disclosure. The accompanying drawings illustrate specific embodiments which can carry out the present disclosure by way of example. However, the example embodiments are not intended to exhaust all embodiments of the present disclosure. It may be understood that structural or logical modifications may be made using other embodiments without departing from the scope of the present disclosure. Therefore, the following detailed description is not limiting, and the scope of the present disclosure is defined by the claims as appended. It is noteworthy while steps of the method of the present disclosure are depicted in a particular order, this does not require or suggest that such operations be performed in the particular order, or that all illustrated operations be performed, to achieve desirable results. On the contrary, the steps described herein may be performd out of the order. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and/or one step may be split into multiple steps.

[0070] The present disclosure defines that a resource unit is the basic size of resources for grant-free transmission in a wireless transmission system, and the resource unit is the minimum resource granularity of uplink grant-free transmission and it may include time domain and/or frequency domain. The resource unit is a subframe in the time domain and a physical resource block (PRB)in the frequency domain. Of course, such dividing is merely one example, and the system may define smaller or larger resource granularity, which does not effect on the present disclosure.

[0071] The feedback based on a resource unit refers to that the feedback of grant-free transmission is based on each allocated resource unit rather than each UE. In the grant-free transmission mechanism, multiple UEs may share the same time and frequency resources. That is, in each resource unit there may be uplink data from multiple UEs, and the network-side device, after receiving uplink data, performs feedback on the basis of resource unit according to the decoding situation of the uplink data, and the network-side device sends feedback information on corresponding resources for the grant-free feedback. The feedback is performed with respect to all UEs sharing the resource unit. To ensure that all UEs sharing the resource unit to correctly and effectively receive the grant-free feedback information, the present disclosure further proposes that there exist a corresponding relationship between the resources units for grant-free transmission and resources for grant-free feedback. According to the corresponding relationship, UE can read its own feedback information on a correct resource and perform processing accordingly based on the feedback information. Moreover, in many cases, the preamble information of all UEs sharing the resource unit and the ID information of a user do not need to be sent over the feedback information, which may greatly save signaling overhead.

[0072] Fig. 2 schematically illustrates a corresponding relationship between resource units for grant- free transmission and resources for grant-free feedback. In accordance with such a corresponding relationship, all UEs sharing the same resource unit 1 read feedback information on a corresponding feedback resource 1, and accordingly, all UEs sharing the same resource units 2 and 3 read feedback information on corresponding feedback resources 2 and 3 respectively The corresponding relationship between resource units for grant-free transmission and resources for grant-free feedback is set by the system and notified to corresponding UEs and network-side device. How to allocate resources for grant-free transmission and how to design the corresponding relationship are not within the study scope of the present disclosure. For example, a specific physical channel may be designed to carry grant-free feedback; or the grant-free feedback may be carried using existing physical channels, etc.

[0073] Fig. 3 schematically illustrates the processing procedure of a network-side device for feedback based on a resource unit in the one-step transmission. That is, the feedback based on a resource unit of the present disclosure is applied in the one-step transmission. It is assumed that at least one user terminal transmits uplink data on a resource unit allocated for grant-free transmission on the nth subframe, and the uplink data comprises the preamble and user data information. The network-side device receives uplink data on a given resource unit allocated for grant-free transmission on the nth subframe; and processes the uplink data: the network-side device first detects the preamble, for example, in step S301 the network-side device determines whether the preamble is detected; if the preamble is not detected, the network-side device performs step S302 in which the network-side device sends the fourth feedback information. Since the preamble is not detected, the network-side device will not perform further data decoding. That is, the network-side device may perform feedback without further data information decoding. The fourth feedback information is sent on a resource for grant-free feedback corresponding to the given resource unit allocated for grant-free transmission on the nth subframe. Moreover, fast feedback may be applied, that is, the network-side device may send the fourth feedback information in a fast way on the (n+l)th subframe for the resource unit. The fourth feedback information does not need to carry the ID of the preamble and the user ID and The fourth feedback information only needs to notify all user terminals that send uplink data on the resource unit allocated for grant-free transmission on the nth subframe to re-transmit uplink data including the preamble and data information. In this case, HARQ combining is impossible, and in order to avoid collisions among grant-free uplink transmission, the fourth feedback information is further used to instruct all user terminals that send uplink data on the resource unit for grant-free transmission on the nth subframe to re-transmit the uplink data with a random backoff. In a further embodiment, the network-side device does not send any information to indicate this option.

[0074] In step S303, if the network-side device detects more than one preamble (that is, at least two preambles) on the given resource unit allocated for grant-free transmission on the nth subframe, and the network-side device determines that the data information cannot be correctly decodes, then the network-side device does not decode the data information, that is, it may perform feedback without further data information decoding. In step S304, the network-side device sends the third feedback information on a resource for grant-free feedback corresponding to the given resource unit allocated for grant-free transmission on the nth subframe. Moreover, fast feedback may be applied, that is, the network-side device sends the third feedback information in a fast way on the (n+l)th subframe for the resource unit. The third feedback information does not need to carry the ID of preamble and the user ID and it only needs to notify all user terminals that send uplink data on the resource unit allocated for grant-free transmission on the nth subframe to re-transmit uplink data including the preamble and data information. In this case, HARQ combining is impossible, and in order to avoid collisions among grant-free uplink transmission, third feedback information is further used to instruct all user terminals that send uplink data on the resource unit for grant-free transmission on the nth subframe to re-transmit the uplink data with a random backoff. The network- side device discards uplink data which has been received on the resource unit, because the data is worthless for the HARQ combining. In an embodiment, where the network- side device is only provided with single user detection capability, if the number of detected preambles is larger than or equal to 2, then the network- side device will determine this is beyond its processing capability. In the case that the network-side device is provided with multi-user detection capability, if the number of detected preambles exceeds the multi-user detection capability, at this point the network- side device determines that the probability of successful decoding is very low and this is beyond its processing capability. The network- side device then determines that data information cannot be correctly decoded, and without decoding the data information, the network-side device sends fast feedback and discards uplink data received on the resource unit.

[0075] If the network-side device only detects one preamble on the given resource unit allocated for grant- free transmission on the nth subframe, or the number of detected preambles is less than the multi-user detection capability, the network-side device performs step S305 to continue decoding data. If data decoding fails, the network-side device then stores the uplink data received on the resource unit for HARQ combining. The network-side device continues to perform step S306 to send the second feedback information on a resource for grant-free feedback corresponding to the given resource unit allocated for grant-free transmission on the nth subframe, for example send the second feedback information to UE for the resource unit on the (n+k)th subframe. The second feedback information is used to instruct a user terminal that transmits uplink data on a resource unit for grant-free transmission to re-transmit the uplink data. To achieve HARQ combining, the second feedback information is further used to instruct a user terminal that transmits uplink data on a resource unit for grant-free transmission to re-transmit the uplink data with fixed time offsets. That is, the fixed time offsets are set between retransmission and first transmission to achieve HARQ combining. The fixed time offsets may be set by the system and may comprise time and frequency offsets.

[0076] The network-side device performs step S305 to continue decoding data. If data decoding succeeds, the network-side device then stores uplink data that has been received on the resource unit. The network-side device continues to perform step S307 to send feedback information on a resource for grant-free feedback corresponding to the given resource unit allocated for grant-free transmission on the nth subframe, and further to send an ID information of a user whose data information is correctly decoded, for example to send the first feedback information and the ID information of the user to UE for the resource unit on the (n+k)th subframe. The first feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is correctly decoded does not need to re-transmit the uplink data, while a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is not correctly decoded needs to re-transmit the uplink data. The first feedback information is further used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is not correctly decoded needs to re-transmit the uplink data with fixed time offsets, so as to achieve HARQ combining. [0077] Regarding the third feedback information and the fourth feedback information, the network-side device may send feedback information without a need to further decode data information, and at this point fast feedback may be applied. For example, after receiving grant-free uplink transmission on a current subframe, for example the nth subframe, the network-side device sends feedback of the grant-free uplink transmission on a next subframe, for example the (n+l)th subframe. Regarding the first feedback information and the second feedback information, the network- side device needs to further decode data information before sending feedback information, and may send feedback with fixed time offsets, for example the (n+k)th subframe. A time offset parameter k is predefined by the system, and k is 4 in the existing LTE/LTE-A FDD systems. However, in 5G new wireless access FDD systems, if the hardware processing capability can be enhanced significantly, k may be less than 4. By using the design of the present disclosure, fast feedback may be applied as far as possible, and latency may be reduced effectively. [0078] Fig. 9 schematically illustrates specific situations of the above feedback information. As shown in the table, grant-free feedback has 4 options, that is only 2-bit feedback information is required, and two of which are fast feedback. The correctly decoded user ID needs to be fed back only for the first feedback information, which may greatly save the signaling overhead. Regarding the third feedback information, the network instructs the user to re-transmit the information with fixed time offsets, so that the network-side device knows the position of re-transmitted resources and HARQ combining is possible. In a case that HARQ combining is impossible, the network instructs the user to re-transmit the information with a random backoff, which may greatly reduce the possibility of collision occurrence. Similarly, even in multi-user detection, there are still four types of feedback information, and the feedback signaling only needs two bits.

[0079] Fig. 4 schematically illustrates the processing procedure of a network-side device for feedback based on a resource unit in the two-step transmission. That is, the feedback based on a resource unit in the present disclosure is applied in the two-step transmission. It is supposed that at least one user terminal transmits uplink data on a resource unit allocated for grant-free transmission, and the preamble and user data information are sent in two stepsin the two-step transmission. The network-side device receives the uplink data which the user terminal sends on the resource unit allocated for grant-free transmission; and processes the uplink data: the network- side device first detects the preamble, for example, in step S401 the network-side device determines whether the preamble is detected; if the preamble is not detected, the network-side device performs step S402 in which the network-side device sends the ninth feedback information. Since the preamble is not detected, the network-side device will not perform further data decoding. That is, the network-side device may perform feedback without further data information decoding. The ninth feedback information is sent on a resource for grant-free feedback corresponding to the above resource unit allocated by the system for grant-free transmission. Moreover, fast feedback may be applied, that is, the network-side device may send the fourth feedback information in a fast way on the (n+l)th subframe for the resource unit. The ninth feedback information does not need to carry the ID of preamble and the user ID and only needs to notify all user terminals that send uplink data on the resource unit allocated for grant-free transmission on the nth subframe to re-transmit uplink data including the preamble and data information. In this case, HARQ combining is impossible, and in order to avoid collisions among grant-free uplink transmission, the ninth feedback information is further used to instruct all user terminals that send uplink data on the resource unit for grant-free transmission to re-transmit the uplink data with a random backoff. In a further embodiment, the network-side device does not send any information to indicate this option.

[0080] In step S403, if the network-side device detects more than one preamble (that is, at least two preambles) on the resource unit allocated for grant-free transmission, and the network-side device determines that the data information cannot be correctly decodes, the network-side device does not decode the data information, that is, it may perform feedback without further data information decoding. In step S404, the network-side device sends the eighth feedback information on a resource allocated by the system for grant-free feedback corresponding to the above resource unit for grant-free transmission. Moreover, the fast feedback may be applied, that is, the network-side device sends the eighth feedback information in a fast way on a next subframe for the resource unit. The eighth feedback information does not need to carry the ID of preamble and the user ID and only needs to notify all user terminals that send uplink data on the above resource unit for grant-free transmission on to re-transmit uplink data including the preamble and data information. In this case, HARQ combining is impossible, and in order to avoid collisions among grant-free uplink transmission, the eighth feedback information is further used to instruct all user terminals that send uplink data on the above resource unit for grant- free transmission to re-transmit the uplink data with a random backoff. The network-side device discards uplink data received on the resource unit, because the data is worthless to HARQ combining. In an embodiment where the network- side device is only provided with single user detection capability, if the number of detected preambles is larger than or equal to 2, then the network-side device will determine this is beyond its processing capability. In a case that the network-side device is provided with multi-user detection capability, if the number of detected preambles exceeds the multi-user detection capability, at this point the network-side device determines the probability of successful decoding is very low and this is beyond its processing capability The network-side device then determines data information cannot be correctly decoded, and without decoding the data information, the network- side device sends fast feedback and discards uplink data received on the resource unit.

[0081] If the network-side device only detects one preamble on the resource unit allocated for grant- free transmission, or the number of detected preambles is less than the multi-user detection capability, the network-side device performs step S405 to send the seventh feedback information and the ID detected from the preamble to instruct a user that has sent the preamble with the ID, to send uplink data information. The network-side device sends the seventh feedback information and the ID detected from the preamble in a feedback window in which the preamble of the user terminal is received.

[0082] The network-side device receives from the user terminal the grant-free uplink transmission on the resource unit allocated by the system for grant-free transmission in step S406, and it decodes and determines the received data information in step S407. If data decoding fails, the network-side device then stores the uplink data received on the resource unit for HARQ combining. The network- side device continues to perform step S409 to send the sixth feedback information on a resource for grant-free feedback corresponding to the resource unit allocated by the system for grant-free transmission. The sixth feedback information is used to instruct a user terminal that transmits uplink data on a resource unit for grant-free transmission to re-transmit the uplink data. To achieve HARQ combining, the sixth feedback information is further used to instruct a user terminal that transmits uplink data on a resource unit for grant- free transmission to re-transmit the uplink data with fixed time offsets. That is, the fixed time offsets are set between retransmission and first transmission to achieve HARQ combining.

[0083] The network- side device performs step S407 to continue decoding data. If data decoding succeeds, the network- side device then stores uplink data that has been received on the resource unit. The network-side device continues to perform step S408 to send the fifth feedback information on a resource allocated by the system for grant-free feedback corresponding to the above resource unit allocated for grant-free transmission, and further to send user ID information of the correctly decoded data information. The fifth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is correctly decoded does not need to re-transmit the uplink data, while a user terminal which transmits uplink data on a resource unit for grant- free transmission and whose data information is not correctly decoded needs to re-transmit the uplink data. The fifth feedback information is further used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is not correctly decoded needs to re-transmit the uplink data with fixed time offsets, so as to achieve HARQ combining.

[0084] Regarding the seventh feedback information, the eighth feedback information as well as the ninth feedback information, the network-side device may send feedback information without a need to further decode data information, and at this point the fast feedback may be applied. For example, after receiving grant-free uplink transmission on a current subframe, for example the nth subframe, the network-side device sends feedback of the grant-free uplink transmission on a next subframe, for example the (n+l)th subframe. Regarding the fifth feedback information and sixth feedback information, the network-side device needs to further decode data information before sending feedback information, and may send feedback with fixed time offsets, for example the (n+k)th subframe. A time offset parameter k is predefined by the system, and k is 4 in existing LTE/LTE-A FDD systems. However, in 5G new wireless access FDD systems, if the hardware processing capability can be enhanced significantly, then k may be less than 4. By using the design of the present disclosure, the fast feedback may be applied as far as possible, and latency may be reduced effectively. [0085] Likewise, since the ID of preamble and the user ID do not need to be fed back in many casesa, the feedback signaling will be also greatly decreased.

[0086] The processing at the user terminal corresponds to that at the network-side device.

[0087] Fig. 5 schematically illustrates the processing procedure of a user terminal for feedback based on a resource unit in the one-step transmission. That is, the feedback based on a resource unit in the present disclosure is applied in the one-step transmission. It is noteworthy that the processing procedure in Fig. 5 corresponds to that in Fig. 3.

[0088] In step S501, UE transmits uplink data including preamble and data information on a resource unit allocated for grant-free transmission on the nth subframe, the uplink data. In step S502, UE attempts to receive grant-free feedback and performs corresponding processing on a feedback resource corresponding to a resource unit for grant-free transmission in a feedback window, that is from the (n+l)th subframe to the (n+k)th subframe. The size of the feedback window, that is k subframes, is set by the system. Regarding a resource unit already used by UE, if in step S506 UE receives the fourth feedback information on the (n+l)th subframe or it does not receive any feedback until the (n+k)th subframe, then UE performs step S510 for retransmission with a random backoff. If in step S505 UE receives the third feedback information on the (n+1) subframe, then UE performs step S510 for retransmission with a random backoff. If in step S504 UE receives the second feedback information on the (n+k)th subframe, then UE performs step S509 for retransmission with fixed time offsets. The fixed time offsets are configured by the system and it may comprise time and frequency offsets. If in step S503, UE receives the first feedback information on the (n+k)th subframe, then UE performs step S507 to further detect whether there is its own user ID in the feedback information. In step S508, UE receives its own user ID, then UE knows its transmission on the nth subframe succeeds and there is no need for data retransmission; if UE does not receive its own user ID, then UE knows its transmission on the nth subframe fails, and UE performs step S509 for retransmission with fixed time offsets. The fixed time offsets are configured by the system and it may comprise time and frequency offsets.

[0089] Fig. 6 schematically illustrates the processing procedure of a user terminal for feedback based on a resource unit in the two-step transmission. That is, the feedback based on a resource unit in the present disclosure is applied in the two-step transmission. It is noteworthy that the processing procedure in Fig. 6 corresponds to that in Fig. 4. [0090] In step S601, UE transmits uplink data including a preamble on a resource unit allocated for grant-free transmission on the nth subframe, the uplink data. In step S602, UE attempts to receive grant-free feedback and performs corresponding processing in a feedback window, that is from the (n+l)th subframe to the (n+k)th subframe. The size of the feedback window, that is k subframes, is set by the system. Regarding a resource unit already used by UE, if in step S603 UE receives seventh feedback information on a feedback resource corresponding to a resource unit for grant-free uplink transmission, then UE performs step S606 to further detect whether there is an ID of its own preamble in the seventh feedback information. If there is not the ID of its own preamble in the seventh feedback information, UE performs step S14 for retransmission with a random backoff; if there is the ID of its own preamble in the seventh feedback information, UE performs step S607 to send uplink data, that is data information on a resource unit allocated for grant-free transmission. Next, in step S608 UE detects the feedback information, and in step S609 UE receives the fifth feedback information. UE continues to perform step S611 to detect whether there is its own user ID. If there is not its own user ID,, UE performs step S613 for retransmission with fixed time offsets. If there exists its own user ID, UE performs step S612, and UE knows its transmission on the n^th subframe succeeds and there is no need for data retransmission. In step S608 UE detects feedback information, and in step S610 UE receives the sixth feedback information. UE performs step S613 for retransmission with fixed time offsets. In step S602, regarding a resource unit already used by UE, if in step S604 UE receives the eighth feedback information on a feedback resource corresponding to a resource unit for grant-free uplink transmission, UE performs step S614 for retransmission with a random backoff; if in step S605 UE receives the ninth feedback information on a feedback resource corresponding to a resource unit for grant- free uplink transmission, UE performs step S614 for retransmission with a random backoff.

[0091] Fig. 7 schematically illustrates a structural diagram of a network-side device for feedback based on a resource unit. The network-side device 700 may be or may be implemented on a network-side device described with reference to Fig. 3 or Fig. 4, for example.

[0092] The network-side device 700 comprises: a receiving unit 701 configured to receive uplink data from at least one user terminal, the uplink data including a preamble and/or user data information and being sent on a resource unit for grant-free transmission. A data processing unit includes a preamble detecting unit 702 and a data information decoding unit 704. The preamble detecting unit 702 is configured to detect a preamble, the data information decoding unit 704 is configured to decode data information; a determining unit 703 is configured to determine whether the data information needs to be decoded, according to a detecting of the preamble detecting unit; and a feedback unit 705 is configured to send feedback information on a feedback resource for grant-free transmission feedback corresponding to a resource unit for grant-free transmission, according to a result of the data processing.

[0093] Fig. 8 schematically illustrates a structural diagram of a user terminal for feedback based on a resource unit. A user terminal 800 may be or may be implemented on a user terminal described with reference to Fig. 5 or Fig. 6, for example. [0094] The user terminal 800 comprises: a transmitting unit 801 configured to transmit uplink data, including a preamble and/or data information, on a resource unit for grant-free transmission; a receiving unit 802 configured to receive from a network-side device feedback information sent on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission; a preamble ID detecting unit 803 configured to detect whether its own preamble is received; a user ID detecting unit 804 configured to detect whether its own user ID is received; and a re-transmitting unit 805 configured to re-transmit the uplink data which has been sent according to the feedback information.

[0095] The innovative solution of the present disclosure can effectively reduce the overhead of the feedback signaling for grant- free transmission feedback, because the ID of preamble and UE ID are not essential information elements in the feedback signaling, and the UE ID needs to be included only in the cases that data sending success is indicated. In specific scenarios, the present disclosure may send fast feedback and effectively reduce the latency. Moreover, retransmissions may be realized with fixed time offsets or a random backoff, which may reduce collisions and achieve HARQ combining in appropriate conditions.

[0096] It will be apparent to those skilled in the art that the present disclosure is not limited to details of the foregoing example embodiments and may be implemented in other specific form without departing from the spirit or basic features of the present disclosure. Nevertheless, the embodiments should be deemed as example and non-limiting. In addition, it is obvious that the word "comprise" does not exclude other elements and steps, and the word "one" does not exclude pluralities. Multiple elements in apparatus claims may be implemented by one element. Moreover, the words "first," "second" and the like are used to represent names rather than any specific order.

Claims

I/We Claim:

1. A method for feedback of grant- free transmission based on a resource unit, comprising:

receiving, at a network- side device, from at least one user terminal, uplink data transmitted on a resource unit for grant-free transmission;

performing, at the network-side device, data processing on the uplink data; and sending, at the network-side device, feedback information on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission based on a result of the data processing.

2. The method according to Claim 1, wherein the uplink data comprises data information and a preamble of at least one user terminal; and

wherein performing, at the network-side device, data processing on the uplink data comprises:

detecting the preamble;

determining, at the network-side device, whether the data information needs to be decoded based on the detecting of the preamble; and

in response to that the data information needs to be decoded, decoding the data information at the network- side device.

3. The method according to Claim 2, wherein sending, at the network-side device, feedback information on the feedback resource for grant-free transmission feedback based on the result of the data processing comprises:

in response to at least one preamble being detected during detection of the preamble from the uplink data at the network-side device, and data information of at least one user terminal being successfully decoded, sending, at the network-side device, first feedback information on the feedback resource for the grant-free transmission feedback;

in response to at least one preamble being detected during detection of the preamble from the uplink data at the network-side device, and data information of at least one user terminal being unsuccessfully decoded, sending, at the network- side device, second feedback information on the feedback resource for the grant-free transmission feedback;

in response to at least two preambles being detected during detection of the preamble from the uplink data at the network- side device and that the network- side device determines the data information cannot be correctly decoded, sending, at the network-side device, third feedback information on the feedback resource for the grant-free transmission feedback without decoding the data information; and

in response to no preamble being detected during detection of the preamble from the uplink data at the network-side device, sending, at the network-side device, fourth feedback information on the feedback resource for the grant-free transmission feedback without decoding the data information.

4. The method according to Claim 3, wherein the network-side device further sends user ID information of the correctly decoded data information, while sending the first feedback information.

5. The method according to Claim 4, wherein the first feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is correctly decoded does not need to re-transmit the uplink data, and a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is incorrectly decoded re-transmits the uplink data; the second feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data;

the third feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data; and the fourth feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

6. The method according to Claim 4, wherein the first feedback information is further used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is incorrectly decoded re-transmits the uplink data with a fixed offset;

the second feedback information is further used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a fixed offset;

the third feedback information is further used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a random backoff; and the fourth feedback information is further used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a random backoff.

7. The method according to Claim 2,, wherein sending the first feedback information comprises: sending, at the network- side device, the first feedback information at a fixed time offset from a current subframe when the uplink data is received;

wherein sending the second feedback information comprises: sending, at the network-side device, the second feedback information at a fixed time offset from a current subframe when the uplink data is received;

wherein sending the third feedback information comprises: sending, at the network-side device, the third feedback information at a subframe next to a current subframe when the uplink data is received; and

wherein sending the fourth feedback information comprises: sending, at the network-side device, the fourth feedback information at a subframe next to a current subframe when the uplink data is received.

8. The method according to Claim 1, wherein the uplink data comprises data information of at least one user terminal, and performing, at the network-side device, data processing on the uplink data comprises:

decoding the data information;

if the network- side device successfully decodes the data information from at least one user terminal, sending, at the network-side device, fifth feedback information on the feedback resource for grant-free transmission feedback; and

if the network- side device fails to decode the data information from a user terminal, sending, at the network- side device, sixth feedback information on the feedback resource for grant-free transmission feedback.

9. The method according to Claim 8, further comprising:

before receiving from the at least one user terminal the uplink data transmitted on the resource unit for grant-free transmission,

receiving, at the network-side device, the preamble of the at least one user terminal, and

decoding the preamble.

10. The method according to Claim 9, further comprising:

if the preamble is correctly decoded at the network-side device, sending, at the network-side device, seventh feedback information and an ID detected from the preamble to indicate that the uplink data information is sent from a user terminal which has sent the preamble with the ID.

11. The method according to Claim 8, wherein the network-side device further sends user ID information of the correctly decoded data information, while sending the fifth feedback information.

12. The method according to Claim 11, wherein the fifth feedback information is used to indicate that the user terminal whose data information has been correctly decoded does not need to re-transmit the uplink data; and

the sixth feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

13. The method according to Claim 12, wherein the network- side device sends the fifth feedback information or the sixth feedback information at a fixed time offset from a current subframe when the uplink data is received; and

the network- side device sends the seventh feedback information within a feedback window in which the preamble of the user terminal is received.

14. A method for feedback of grant-free transmission based on a resource unit, the method comprising:

transmitting, at a user terminal, uplink data on a resource unit for grant-free transmission;

receiving from a network-side device feedback information sent on a feedback resource for grant- free transmission feedback corresponding to the resource unit for grant- free transmission; and

re-transmitting, at the user terminal, the uplink data which has been sent according to the feedback information.

15. The method according to Claim 14, wherein the uplink data comprises a preamble and data information.

16. The method according to Claim 15, further comprising:

in response to the user terminal receiving first feedback information, detecting, at the user terminal, whether its own user ID is received, wherein the user terminal does not perform retransmission if its own user ID is received, and the user terminal re-transmits the uplink data on a resource unit for grant-free transmission if its own user ID is not received;

in response to the user terminal receiving second feedback information, re-transmitting, at the user terminal, the uplink data on a resource unit for grant-free transmission;

in response to the user terminal receiving third feedback information, the user terminal re-transmits the uplink data on a resource unit for grant-free transmission; and

in response to the user terminal receiving fourth feedback information, the user terminal re-transmits the uplink data on a resource unit for grant-free transmission.

17. The method according to Claim 16, wherein

if the user terminal receives the first feedback information and does not receive its own user ID, the user terminal re-transmits the uplink data with a fixed offset on a resource unit for grant-free transmission;

if the user terminal receives the second feedback information, the user terminal re-transmits the uplink data with a fixed offset on a resource unit for grant-free transmission; if the user terminal receives the third feedback information, the user terminal re-transmits the uplink data with a random backoff on a resource unit for grant-free transmission; and

if the user terminal receives the fourth feedback information, the user terminal re-transmits the uplink data with a random backoff on a resource unit for grant-free transmission.

18. The method according to Claim 14, wherein the uplink data comprises data information.

19. The method according to Claim 18, further comprising:

in response to the user terminal receiving fifth feedback information, detecting, at the user terminal, whether its own user ID is received, wherein the user terminal does not perform retransmission if its own user ID is received, and the user terminal re-transmits the uplink data on a resource unit for grant-free transmission if its own user ID is not received; and in response to the user terminal receiving sixth feedback information, re-transmitting, at the user terminal, the uplink data on a resource unit for grant-free transmission.

20. The method according to Claim 19, wherein the user terminal re-transmits the uplink data with a fixed offset on a resource unit for grant-free transmission.

21. The method according to Claim 18, further comprising:

before transmitting the uplink data at the user terminal on the resource unit for grant-free transmission,

sending a preamble; and

receiving, from the network-side device, feedback information of the preamble.

22. The method according to Claim 21, further comprising:

in response to the user terminal receiving seventh feedback information, detecting, at the user terminal, whether an ID of its own preamble is received;

in response to the ID of its own preamble being received, sending, at the user terminal, the uplink data on a resource unit for grant-free transmission; and

in response to the ID of its own preamble being not received, re- sending a preamble at the user terminal.

23. A network-side device for feedback of grant-free transmission based on a resource unit, the network- side device comprising:

a receiving unit configured receive from at least one user terminal, uplink data transmitted on a resource unit for grant-free transmission;

a data processing unit configured to perform data processing on the uplink data; and a feedback unit configured to send feedback information on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission based on a result of the data processing.

24. The network-side device according to Claim 23, wherein the uplink data comprises data information and a preamble of at least one user terminal; the data processing unit comprises a preamble detecting unit configured for detecting a preamble;

the network-side device further comprises a determining unit configured to determine whether the data information needs to be decoded based on the detecting of the preamble detecting unit; and

the data processing unit further comprises a data decoding unit configured to decode the data information.

25. The network-side device according to Claim 24, wherein the feedback information sent from the feedback unit comprises one of:

in response to the preamble detecting unit detecting at least one preamble and the data decoding unit successfully decoding data information of at least one user terminal, the feedback unit sends first feedback information on the feedback resource for grant-free transmission feedback;

in response to the preamble detecting unit detecting at least one preamble and the data decoding unit failing to decode data information, the feedback unit sends second feedback information on the feedback resource for grant-free transmission feedback;

in response to the preamble detecting unit detecting at least two preambles and the determining unit determining data information cannot be correctly decoded, the data decoding unit does not decode the data information and the feedback unit sends third feedback information on the feedback resource for grant-free transmission feedback; and

in response to the preamble detecting unit failing to detect any preamble, the data decoding unit does not decode data information and the feedback unit sends fourth feedback information on the feedback resource for grant-free transmission feedback.

26. The network- side device according to Claim 25, wherein the feedback unit is further configured to send user ID information of the correctly decoded data information, while sending the first feedback information.

27. The network-side device according to Claim 26, wherein the first feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is correctly decoded does not need to re-transmit the uplink data, and a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is incorrectly decoded re-transmits the uplink data;

the second feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data; the third feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data; and the fourth feedback information is used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

28. The network- side device according to Claim 23, wherein the first feedback information is further used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission and whose data information is incorrectly decoded re-transmits the uplink data with a fixed offset;

the third feedback information is further used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a random backoff; and

the fourth feedback information is further used to indicate that a user terminal transmitting uplink data on a resource unit for grant-free transmission re-transmits the uplink data with a random backoff.

29. The network- side device according to Claim 24, wherein if the feedback unit is configured to send the first feedback information, the feedback unit is configured to send the first feedback information at a fixed time offset from a current subframe,

if the feedback unit is configured to send the second feedback information, the feedback unit is configured to send the second feedback information at a fixed time offset from a current subframe when the uplink data is received;

if the feedback unit is configured to send third feedback information, the feedback unit is configured to send the third feedback information on a subframe next to a current subframe when the uplink data is received; and

if the feedback unit is configured to send fourth feedback information, the feedback unit is configured to send the fourth feedback information on a subframe next to a current subframe when the uplink data is received.

30. The network-side device according to Claim 23, wherein the uplink data comprises data information of at least one user terminal; the data processing unit is configured to decode the data information, if the data processing unit successfully decodes data information of at least one user terminal, the feedback unit is configured to send fifth feedback information on the feedback resource for grant-free transmission feedback, and if the data processing unit fails to decode data information from a user terminal, the feedback unit is configured to send sixth feedback information on the feedback resource for grant-free transmission feedback.

31. The network-side device according to Claim 30, wherein the receiving unit is further configured to receive the preamble of the at least one user terminal and output the preamble to the preamble detecting unit for preamble decoding, before receiving from at least one user terminal uplink data transmitted on a resource unit for grant-free transmission.

32. The network-side device according to Claim 31, wherein if the preamble detecting unit correctly decodes a preamble, the feedback unit is configured to send seventh feedback information and ID detected from the preamble to indicate that the uplink data information is transmitted from a user terminal which has sent the preamble with the ID.

33. The network-side device according to Claim 30, wherein if the feedback unit is configured to send the fifth feedback information, the feedback unit is further configured to further send user ID information of the correctly decoded data information.

34. The network-side device according to Claim 33, wherein the fifth feedback information is used to indicate that the user terminal whose data information has been correctly decoded does not need to re-transmit the uplink data; the sixth feedback information is used to indicate that a user terminal which transmits uplink data on a resource unit for grant-free transmission re-transmits the uplink data.

35. The network-side device according to Claim 34, wherein the feedback unit is configured to send the fifth feedback information or the sixth feedback information at a fixed time offset from a current subframe when the uplink data is received; the feedback unit is configured to send the seventh feedback information within a feedback window in which the preamble of the user terminal is received.

36. A user terminal for feedback of grant-free transmission based on a resource unit, the user terminal comprising: a transmitting unit configured to transmit uplink data on a resource unit for grant-free transmission;

a receiving unit configured to receive from a network-side device feedback information sent on a feedback resource for grant-free transmission feedback corresponding to the resource unit for grant-free transmission; and

a re-transmitting unit configured to re-transmit, or stop retransmission of, the uplink data which has been sent based on the feedback information.

37. The user terminal according to Claim 36, wherein the uplink data comprises a preamble and data information.

38. The user terminal according to Claim 37, further comprising:

a user ID detecting unit configured to detect whether its own user ID is received in response to the receiving unit receiving first feedback information, wherein in response to its own user ID being received, the re-transmitting unit does not perform retransmission; and in response to its own user ID not being received, the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission;

wherein the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission in response to the receiving unit receiving second feedback information;

wherein the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission in response to the receiving unit receiving third feedback information; and

wherein the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission in response to the receiving unit receiving fourth feedback information.

39. The user terminal according to Claim 38, wherein

the re-transmitting unit is configured to re-transmit the uplink data with a fixed time offset on a resource unit for grant-free transmission, in response to that the receiving unit receives the first feedback information and the user ID detecting unit does not detect its own user ID;

the re-transmitting unit is configured to re-transmit the uplink data with a fixed offset on a resource unit for grant-free transmission, in response to that the receiving unit receives the second feedback information;

the re-transmitting unit is configured to re-transmit the uplink data with a random backoff on a resource unit for grant-free transmission, in response to that the receiving unit receives the third feedback information; and

the re-transmitting unit is configured to re-transmit the uplink data with a random backoff on a resource unit for grant-free transmission, in response to that the receiving unit receives the fourth feedback information.

40. The user terminal according to Claim 36, wherein the uplink data comprises data information.

41. The user terminal according to Claim 40, further comprising:

a user ID detecting unit configured to detect whether its own user ID is received;

wherein in response to the receiving unit receiving fifth feedback information, the re-transmitting unit does not perform retransmission if the user ID detecting unit detects its own user ID; and the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant-free transmission if the user ID detecting unit does not detect its own user ID; and

wherein the re-transmitting unit is configured to re-transmit the uplink data on a resource unit for grant- free transmission, in response to the receiving unit receiving sixth feedback information.

42. The user terminal according to Claim 41, wherein the re-transmitting unit is configured to re-transmit the uplink data with a fixed offset on a resource unit for grant-free transmission.

43. The user terminal according to Claim 42, wherein the sending unit is further configured to send a preamble before transmitting the uplink data on the resource unit for grant-free transmission; and

the receiving unit is further configured to receive feedback information of the preamble from the network-side device.

44. The user terminal according to Claim 43, further comprising:

a preamble ID detecting unit configured to detect whether an ID of its own preamble is received in response to the receiving unit receiving seventh feedback information, wherein if the ID of its own preamble is received, the sending unit is configured to transmit the uplink data on a resource unit for grant-free transmission, and if the ID of its own preamble is not received, the sending unit is configured to re-send a preamble.

45. A method for resource allocation in a wireless network, the wireless network comprising a network-side device and at least one user terminal, the network-side device allocating a resource unit for grant-free uplink transmission for a user terminal and allocating a feedback resource for grant- free feedback for the network- side device, the resource unit for grant-free uplink transmission for the user terminal corresponding to the feedback resource for grant-free feedback for the network-side device.