Transmitting and Receiving Data

Abstract

Methods and apparatus are provided. In an example aspect, a method of transmitting data performed by a wireless device is provided, wherein the wireless device is associated with multiple serving cells. The method comprises transmitting data to a network node on one or more of the serving cells based on a respective cell weighting for each of the serving cells.

Description

TECHNICAL FIELD

Examples of the present disclosure relate to transmitting and receiving data, for example on one or more serving cells.

BACKGROUND

3GPP radio technologies, such as for example Long Term Evolution (LTE) or New Radio (NR), may be used in licensed spectrum. Initiatives like Licence Assisted Access (LAA), MulteFire and NR-U are solutions to use LTE and NR in unlicensed spectrum. Using unlicensed spectrum may increase the overall capacity of a network if used in parallel to licensed spectrum.

Using unlicensed spectrum, such as for example industrial, scientific and medical (ISM) radio bands, may require the use of Clear Channel Assessment (CCA) or Listen Before Talk (LBT) Medium Access Control (MAC) schemes, in which a transmitter first senses that the transmission medium is free before using it for transmissions.

SUMMARY

One aspect of the present disclosure provides a method of transmitting data performed by a wireless device. The wireless device is associated with multiple serving cells. The method comprises transmitting data to a network node on one or more of the serving cells based on a respective cell weighting for each of the serving cells.

Another aspect of the present disclosure provides a method of receiving data from a wireless device. The wireless device is associated with multiple serving cells. The method comprises receiving data from the wireless device on one or more of the serving cells based on a respective cell weighting for each of the serving cells.

A further aspect of the present disclosure provides apparatus comprising a processor and a memory. The memory contains instructions executable by the processor such that the apparatus is operable to transmit data to a network node on one or more of a plurality of serving cells associated with the apparatus based on a respective cell weighting for each of the serving cells.

A still further aspect of the present disclosure provides apparatus comprising a processor and a memory. The memory contains instructions executable by the processor such that the apparatus is operable to receive data from a wireless device on one or more of a plurality of serving cells associated with the wireless device based on a respective cell weighting for each of the serving cells.

An additional aspect of the present disclosure provides apparatus configured to transmit data to a network node on one or more of a plurality of serving cells associated with the apparatus based on a respective cell weighting for each of the serving cells.

Another aspect of the present disclosure provides apparatus configured to receive data from a wireless device on one or more of a plurality of serving cells associated with the wireless device based on a respective cell weighting for each of the serving cells.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of examples of the present disclosure, and to show more clearly how the examples may be carried into effect, reference will now be made, by way of example only, to the following drawings in which:

FIG. 1 is a flow chart of an example of a method of transmitting data performed by a wireless device;

FIG. 2 is a flow chart of an example of a method of receiving data from a wireless device;

FIG. 3 is a schematic of an example of apparatus for transmitting data; and

FIG. 4 is a schematic of an example of apparatus for receiving data.

DETAILED DESCRIPTION

The following sets forth specific details, such as particular embodiments or examples for purposes of explanation and not limitation. It will be appreciated by one skilled in the art that other examples may be employed apart from these specific details. In some instances, detailed descriptions of well-known methods, nodes, interfaces, circuits, and devices are omitted so as not obscure the description with unnecessary detail. Those skilled in the art will appreciate that the functions described may be implemented in one or more nodes using hardware circuitry (e.g., analog and/or discrete logic gates interconnected to perform a specialized function, ASICs, PLAs, etc.) and/or using software programs and data in conjunction with one or more digital microprocessors or general purpose computers. Nodes that communicate using the air interface also have suitable radio communications circuitry. Moreover, where appropriate the technology can additionally be considered to be embodied entirely within any form of computer-readable memory, such as solid-state memory, magnetic disk, or optical disk containing an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein.

Hardware implementation may include or encompass, without limitation, digital signal processor (DSP) hardware, a reduced instruction set processor, hardware (e.g., digital or analogue) circuitry including but not limited to application specific integrated circuit(s) (ASIC) and/or field programmable gate array(s) (FPGA(s)), and (where appropriate) state machines capable of performing such functions.

Allowing networks to operate in shared spectrum (or unlicensed spectrum) is an approach that may increase network capacity. Although unlicensed spectrum does not match the qualities of licensed spectrum, for example in terms of reliability, bandwidth, availability and/or latency, solutions that allow an efficient use of unlicensed spectrum as a complement to licensed spectrum (such as, for example, solutions provided herein) have the potential to provide increased capacity while mitigating or avoiding at least some of the drawbacks. Some features in a network technology, such as for example LTE or NR, may need to be adapted to comply with the special characteristics of the unlicensed band as well as also different regulations. When operating in unlicensed spectrum, a device may be required to sense the medium as free before transmitting. This operation is often referred to as Listen Before Talk (LBT). Sensing may be performed in a particular channel (corresponding to a defined carrier frequency) and over a predefined bandwidth. For example, in the 5 GHz band, the sensing is performed over 20 MHz bandwidth. Examples of LBT procedures are described in standards EN 301.893, 5 GHz RLAN, Harmonized standard covering the essential requirements of article 3.2 of Directive 2014/53/EU, which is incorporated herein by reference.

Using unlicensed spectrum and/or Listen Before Talk (LBT) procedures can in some cases cause problems for applications that have a fixed upper bound on the latency of related communications. Additionally or alternatively, applications supporting high reliability and deterministic latency, such as for example URLLC (Ultra Reliable Low-Latency Communications) or HRLLC (Highly Reliable Low-Latency Communications) schemes, may not be suitable for unlicensed spectrum use, as exclusive or guaranteed use of the unlicensed wireless spectrum or unlicensed channels is not provided. URLLC, for example, has strict requirements on transmission reliability and latency, i.e., 99.9999% reliability within 1 ms one-way latency. However, it is not known at a particular time whether unlicensed spectrum is occupied (e.g. by other radio technologies such as Wi-Fi) or can be used for transmissions, and a transmitter may need to wait for a channel in unlicensed spectrum to be free (e.g. no usage of the channel is detected) before it can begin transmissions. Hence, the latency of communications using that channel cannot easily be predicted or controlled, and the reliability of communications using unlicensed spectrum cannot be guaranteed.

URLLC operation has large bandwidth requirements given the need for extremely robust encoding techniques. Licensed spectrum may however be scarce and/or expensive, but nonetheless may be able to guarantee high reliability and QoS levels. Therefore, the use of unlicensed spectrum for communications (e.g. 5G or New Radio, NR, communications as well as other technologies such as LTE) or URLLC communications is considered for examples of this disclosure. It is however currently unclear how URLLC requirements and/or requirements from Time Sensitive Networking (TSN), such as reaching a deterministic low latency performance, can be achieved by operation in unlicensed shared spectrum that is primarily used for best effort services. Data referred to herein may comprise such types of data or communications and/or may refer to Internet of Things, IoT, data.

For a wireless device operating on multiple cells (referred to as serving cells for the wireless device), which may be in unlicensed spectrum or both licensed and unlicensed spectrum, a wireless device (e.g. User Equipment, UE) may consider a configured or estimated weight for each serving cell in deciding on which of those multiple unlicensed/shared spectrum cells to transmit on, and/or how much data to transmit on each. This weighting or ordering can in some examples be different for different services/logical channels in the wireless device. In particular examples for industrial IoT/URLLC use-cases, the ordering or weight estimation may be done according to expected delay performance resulting from LBT procedures on each serving cell.

Thus, for example, to consider the fact that different serving cells may be of differing quality (e.g. cells on unlicensed/shared spectrum may not be of the same quality as cells on licensed spectrum), a wireless device may consider cell weights e.g. estimated or configured weights or ranking to decide upon the order and/or amount of data transmitted on each of the serving cells. The weights or ranking may in some examples be provided per logical channel to differentiate cell usage between services with different QoS requirements.

FIG. 1 is a flow chart of an example of a method 100 of transmitting data performed by a wireless device. The wireless device is associated with multiple serving cells, e.g. the wireless device may transmit data on any of the serving cells (subject to any restrictions, if any). The method 100 comprises, in step 102, transmitting data to a network node on one or more of the serving cells based on a respective cell weighting for each of the serving cells. For example, a respective portion of the data on each of the one or more of the serving cells, such that for example different portions of the data are transmitted on each of the one or more serving cells.

In some examples, transmitting data to a network node on one or more of the serving cells comprises selecting one or more of the serving cells based on the respective weighting for each of the serving cells, and transmitting the data to the network node on the selected one or more of the serving cells. So, for example, one or some but not all of the serving cells may be selected based on the weighting. In some examples, selecting one or more of the serving cells based on the respective weighting for each of the serving cells comprises selecting one or more of the serving cells whose respective weighting indicates that one or more of a channel access or Listen Before Talk, LBT, failure risk for that serving cell, a delay or average delay for access to the serving cell by the wireless device and/or one or more other wireless devices, a number or rate of Listen Before Talk, LBT, failures for accessing the serving cell by the wireless device and/or one or more other wireless devices, an occupancy level of the serving cell and/or an interference level on the serving cell is below a threshold associated with a logical channel for the data. So, for example, a service or application that is to transmit data on the logical channel may only use those serving cells where the weighting indicates that the failure risk for channel access (e.g. LBT, CCA etc) is not too high. The weighting may for example indicate the failure risk for a cell or the failure risk may be derived from the weighting.

In some examples, transmitting data to a network node on one or more of the serving cells comprises transmitting a respective amount of the data on each of the one or more of the serving cells based on the weighting. So, for example, more data may be transmitted on those cells where the weighting may indicate a higher chance of channel access on that cell, a more reliable cell, lower interference on that cell, and/or any other parameter or property of the cell.

The respective weighting for each of the serving cells may in some examples be associated with a logical channel, e.g. a logical channel used by an application. Each of the serving cells may then have a respective further cell weighting associated with a further logical channel. In other words, the weighting for each cell may be different for different logical channels.

In some examples, the wireless device may determine (or estimate) the respective weighting for one or more of the serving cells. For example, determining the respective weighting for each of the one or more of the serving cells may comprise determining the respective weight based on one or more of a delay or average delay for access to the serving cell by the wireless device and/or one or more other wireless devices, a number or rate of Listen Before Talk, LBT, failures for accessing the serving cell by the wireless device and/or one or more other wireless devices, an occupancy level of the serving cell, an interference level on the serving cell, and an estimated chance of LBT failure by the wireless device for accessing the serving cell. The respective weighting for each of the serving cells may be determined e.g. based on measurements on each cell or records of usage attempts for each cell, such as the number of LBT access attempts and so on. The one or more of the serving cells comprise cells on unlicensed spectrum, and hence the weighting for each cell may for example be determined based on access attempts to use the cell or a channel on the cell. Alternatively, the respective weighting for one or more of the serving cells is pre-configured, e.g. preprogrammed or received from a base station or network node.

In some examples, the method 100 comprises, before transmitting data to a network node on one or more of the serving cells, receiving one or more uplink grants to transmit data on a plurality of the serving cells, and wherein transmitting data to the network node on one or more of the serving cells comprises selecting one or more of the plurality of serving cells based on the respective cell weighting for each of the plurality of serving cells, and transmitting the data to the network node on the selected one or more of the serving cells.

In some examples, one or more of the serving cells comprise cells on unlicensed spectrum. For example, all of the serving cells may be on unlicensed spectrum, or one or more of the serving cells may be on licensed spectrum instead.

FIG. 2 is a flow chart of an example of a method 200 of receiving data from a wireless device. The wireless device is associated with multiple serving cells, and may in some examples perform the method 100 described above. The method 200 comprises, in step 202, receiving data from the wireless device on one or more of the serving cells based on a respective cell weighting for each of the serving cells.

In some examples, receiving data from the wireless device on one or more of the serving cells comprises receiving a respective portion of the data on each of the one or more of the serving cells. So, for example, a different portion of the data may be received on each of the one or more serving cells.

Receiving data from the wireless device on one or more of the serving cells may in some examples comprise receiving a respective amount of the data on each of the one or more of the serving cells based on the weighting.

In some examples, the respective weighting for each of the serving cells is associated with a logical channel used by the wireless device, and each of the serving cells has a respective further cell weighting associated with a further logical channel used by the wireless device. Thus, for example each serving cell may have different weightings for different serving cells.

In some examples, the entity performing the method 200 (which is e.g. a network node or base station) may determine (or estimate) the respective weighting for one or more of the serving cells. For example, determining the respective weighting for each of the one or more of the serving cells comprises determining the respective weight based on one or more of a delay or average delay for access to the serving cell by the wireless device and/or one or more other wireless devices, a number or rate of Listen Before Talk, LBT, failures for accessing the serving cell by the wireless device and/or one or more other wireless devices, an occupancy level of the serving cell, an interference level on the serving cell, and an estimated chance of LBT failure by the wireless device for accessing the serving cell.

In some examples, the method 200 comprises sending the respective weighting for the one or more of the serving cells to the wireless device.

Particular examples will now be described. These are described in the context of a UE, though alternatively any suitable wireless device may be considered instead. A logical channel may be configured (e.g. by a network) with an ordered list of serving cells, and the UE has to follow this order when transmitting data of the logical channel, i.e. the UE first using resources of the first cell in the list, then the second, etc. In this case, the weighting for the cell may be considered to be the cell's position in the ordered list for example.

For the case of industrial IoT services, where guaranteed latency is important, the UE may consider a ranking, weighting or ordering of multiple serving cells according to one or more of the following metrics:

• • Delay to access the unlicensed channel/cell
  • Delay to transmit on the unlicensed channel/cell
  • Transmission time interval (and associated processing time)
  • LBT failures or LBT failure rate
  • LBT failure risk
  • Channel occupancy

In some examples, these metrics may be configured (e.g. by the network) or estimated or predicted e.g. based on a past average, moving average or last measured values as seen by the UE.

Conversely, in some examples, the UE may prioritize transmissions on the cell with the most favourable metric(s) and if further data is available for transmission when some data is transmitted on that cell, use one or more other cells according to the ranking. If a metric is the same for different cells, a secondary metric may be used in some examples to determine the order or weighting. If all metrics are the same, for example, the size of an uplink grant per cell could be used to determine the order or weighting. When weighting or ordering for the serving cells are provided per logical channel, the order configured for the highest priority logical channel shall be considered first in some examples.

Additionally or alternatively, data amounts transmitted per transmission opportunity per serving cell may be provided or configured per logical channel. For example, a UE could be configured with weights for each serving cell per logical channel, for example indicating the (maximum) number of bytes that can be transmitted on that cell at each transmission opportunity (e.g uplink grant). If sufficient data is available, the UE may then transmit these data amounts on one or more of the serving cells.

In some examples, a logical channel may be configured with a restriction to transmit on serving cells for which a certain risk of channel access failure (e.g. Clear Channel Access, CCA, or Listen Before Talk, LBT, failure) is configured or estimated. This may be indicated in some examples by the channel weights. For example, a logical channel may be configured with a channel access risk threshold, and only if the estimated channel access failure risk for a particular serving cell is below that threshold, should the logical channel be allowed transmission on that serving cell. In some examples, the channel access failure risk may relate to expected delay in accessing or transmitting on such cells. The UE may perform channel access failure risk or delay assessment itself, or may be provided with values from the network, e.g. network node or base station.

In some examples, the UE can estimate number of LBT failure within period of time on particular serving cell, or can be provided with this value by the network. This can be further formulated as a LBT failure rate. This is LBT failure rate can in some examples be further utilized to enable resource allocation as described in the below described excerpt of specification TS 38.321, section 5.4.3.1.3. In particular, this parameter may be utilized to decide resource allocation considering multiple MAC PDUs to be transmitted on multiple grants.

In some examples, for operation of PDCP duplication, duplicate PDCP packets (which are assigned to different logical channels) must be transmitted on different serving cells to be uncorrelated. When the UE selects among serving cells with potentially different quality for duplicate transmission, the UE must select different serving cells for the two duplicate PDCP packets. This may therefore be an exception to the rule of the order, weighting or ranking for the serving cells discussed herein.

In some examples, the resources used by the UE may be provided based on grant-based scheduling or pre-configured as in the case of configured uplink grant. Therefore, choosing one or more serving cells (and/or the amount of data to transmit on each) may be regarded as being the same as having multiple uplink grants to choose from.

FIG. 3 is a schematic of an example of apparatus 300 for transmitting data. The Apparatus comprises processing circuitry 302 (e.g. one or more processors) and a memory 304 in communication with the processing circuitry 302. The memory 304 contains instructions executable by the processing circuitry 302. The apparatus 300 also comprises an interface 306 in communication with the processing circuitry 302. Although the interface 306, processing circuitry 302 and memory 304 are shown connected in series, these may alternatively be interconnected in any other way, for example via a bus.

In one embodiment, the memory 304 contains instructions executable by the processing circuitry 302 such that the apparatus 300 is operable to transmit data to a network node on one or more of a plurality of serving cells associated with the apparatus based on a respective cell weighting for each of the serving cells. In some examples, the apparatus 300 is operable to carry out the method 100 described above with reference to FIG. 1.

FIG. 4 is a schematic of an example of apparatus 400 for receiving data. The apparatus 400 comprises processing circuitry 402 (e.g. one or more processors) and a memory 404 in communication with the processing circuitry 402. The memory 404 contains instructions executable by the processing circuitry 402. The apparatus 400 also comprises an interface 406 in communication with the processing circuitry 402. Although the interface 406, processing circuitry 402 and memory 404 are shown connected in series, these may alternatively be interconnected in any other way, for example via a bus.

In one embodiment, the memory 404 contains instructions executable by the processing circuitry 402 such that the apparatus 400 is operable to receive data from a wireless device on one or more of a plurality of serving cells associated with the wireless device based on a respective cell weighting for each of the serving cells. In some examples, the apparatus 400 is operable to carry out the method 200 described above with reference to FIG. 2.

It should be noted that the examples disclosed herein illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative examples without departing from the scope of the appended statements. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the statements below. Where the terms, “first”, “second” etc. are used they are to be understood merely as labels for the convenient identification of a particular feature. In particular, they are not to be interpreted as describing the first or the second feature of a plurality of such features (i.e. the first or second of such features to occur in time or space) unless explicitly stated otherwise. Steps in the methods disclosed herein may be carried out in any order unless expressly otherwise stated. Any reference signs in the statements shall not be construed so as to limit their scope.

Some example embodiments disclosed herein are shown below underlined as potential implementations in the 3GPP TS 38.321 MAC specification.

5.4.3.1 Logical Channel Prioritization

5.4.3.1.1 General

The Logical Channel Prioritization (LCP) procedure is applied whenever a new transmission is performed.

RRC controls the scheduling of uplink data by signalling for each logical channel per MAC entity:

• • priority where an increasing priority value indicates a lower priority level;
  • prioritisedBitRate which sets the Prioritized Bit Rate (PBR);
  • bucketSizeDuration which sets the Bucket Size Duration (BSD).

RRC additionally controls the LCP procedure by configuring mapping restrictions for each logical channel:

• • allowedSCS-List which sets the allowed Subcarrier Spacing(s) for transmission;
  • maxPUSCH-Duration which sets the maximum PUSCH duration allowed for transmission;
  • configuredGrantType1Allowed which sets whether a configured grant Type 1 can be used for transmission;
  • allowedServingCells which sets the allowed cell(s) for transmission.

The following UE variable is used for the Logical channel prioritization procedure:

• • Bj which is maintained for each logical channel j.

The MAC entity shall initialize Bj of the logical channel to zero when the logical channel is established.

For each logical channel j, the MAC entity shall:

• • 1> increment Bj by the product PBR×T before every instance of the LCP procedure, where T is the time elapsed since Bj was last incremented;
  • 1> if the value of Bj is greater than the bucket size (i.e. PBR×BSD):
    • 2> set Bj to the bucket size.
  • NOTE: The exact moment(s) when the UE updates Bj between LCP procedures is up to UE implementation, as long as Bj is up to date at the time when a grant is processed by LCP.

5.4.3.1.2 Selection of Logical Channels

The MAC entity shall, when a new transmission is performed:

• • 1> select the logical channels for each UL grant that satisfy all the following conditions:
    • 2> the set of allowed Subcarrier Spacing index values in allowedSCS-List, if configured, includes the Subcarrier Spacing index associated to the UL grant; and
    • 2> maxPUSCH-Duration, if configured, is larger than or equal to the PUSCH transmission duration associated to the UL grant; and
    • 2> configuredGrantType1Allowed, if configured, is set to true in case the UL grant is a Configured Grant Type 1; and
    • 2> allowedServingCells, if configured, includes the Cell information associated to the UL grant. Does not apply to logical channels associated with a DRB configured with PDCP duplication within the same MAC entity (i.e. CA duplication) for which PDCP duplication is deactivated.
    • 2> allowedDelay/Risk, if configured, includes the maximum value for configured/estimated risk/delay for an UL-grant/servingCell, for which transmission of data of this logical channel is allowed.
  • NOTE: The Subcarrier Spacing index, PUSCH transmission duration and Cell information are included in Uplink transmission information received from lower layers for the corresponding scheduled uplink transmission.

5.4.3.1.3 Allocation of Resources

The MAC entity shall, when a new transmission is performed:

• • 1> allocate resources to the logical channels as follows:
    • 2> logical channels selected in clause 5.4.3.1.2 for the UL grant with Bj>0 are allocated resources in a decreasing priority order. If the PBR of a logical channel is set to infinity, the MAC entity shall allocate resources for all the data that is available for transmission on the logical channel before meeting the PBR of the lower priority logical channel(s);
    • 2> decrement Bj by the total size of MAC SDUs served to logical channel j above;
    • 2> if any resources remain, all the logical channels selected in clause 5.4.3.1.2 are served in a strict decreasing priority order (regardless of the value of Bj) until either the data for that logical channel or the UL grant is exhausted, whichever comes first. Logical channels configured with equal priority should be served equally.
  • NOTE: The value of Bj can be negative.

If the MAC entity is requested to simultaneously transmit multiple MAC PDUs, or if the MAC entity receives the multiple UL grants within one or more coinciding PDCCH occasions (i.e. on different Serving Cells), it is up to UE implementation in which order the grants are processed, except when configured to consider ordered ranking of cells to use for at least on logical channel.

The UE shall also follow the rules below during the scheduling procedures above:

• • If the UE is configured to consider an ordered ranking of cells to use for at least one logical channel, the UE shall consider the order of grants to be processed per logical channel starting with the logical channel of highest priority. The UE should evaluate metrics (delay/LBT failures etc. see above) per serving cell to determine the order.
  • the UE should not segment an RLC SDU (or partially transmitted SDU or retransmitted RLC PDU) if the whole SDU (or partially transmitted SDU or retransmitted RLC PDU) fits into the remaining resources of the associated MAC entity;
  • if the UE segments an RLC SDU from the logical channel, it shall maximize the size of the segment to fill the grant of the associated MAC entity as much as possible;
  • the UE should maximise the transmission of data;
  • if the MAC entity is given a UL grant size that is equal to or larger than 8 bytes while having data available and allowed (according to clause 5.4.3.1) for transmission, the MAC entity shall not transmit only padding BSR and/or padding.

Claims

1.-38. (canceled)

39. A method performed by a wireless device configured with a plurality of serving cells, the method comprising: transmitting data to a network node on one or more of the serving cells based on respective cell weightings for the respective serving cells, wherein: the respective cell weightings are associated with respective logical channels, andeach of the serving cells has a different cell weighting associated with a different logical channel than other of the serving cells.

40. The method of claim 39, wherein transmitting data to a network node on one or more of the serving cells comprises: selecting one or more of the serving cells whose respective cell weightings indicates that one or more of the following are below a threshold associated with a logical channel for the data: a channel access or Listen Before Talk (LBT) failure risk for the serving cell,a delay or average delay for access to the serving cell by the wireless device and/or one or more other wireless devices,a number or rate of LBT failures for accessing the serving cell by the wireless device and/or one or more other wireless devices, andan occupancy level of the serving cell and/or an interference level on the serving cell; andtransmitting the data to the network node on the selected serving cells.

41. The method of claim 39, wherein transmitting data to a network node on one or more of the serving cells comprises transmitting respective amounts of the data on each of the one or more of the serving cells based on the respective cell weightings.

42. The method of claim 39, further comprising determining the respective cell weightings for one or more of the serving cells based on one or more of the following: a delay or average delay for access to the serving cell by the wireless device and/or one or more other wireless devices,a number or rate of Listen Before Talk (LBT) failures for accessing the serving cell by the wireless device and/or one or more other wireless devices,an occupancy level of the serving cell,an interference level on the serving cell, andan estimated chance of LBT failure by the wireless device for accessing the serving cell.

43. The method of claim 39, wherein: the respective cell weightings for one or more of the serving cells are pre-configured; andthe method further comprises receiving the pre-configured cell weightings from a network node.

44. The method of claim 39, wherein: the method further comprises, before transmitting the data, receiving from the network node one or more uplink grants for transmitting data on the plurality of the serving cells; andtransmitting data to the network node on one or more of the serving cells comprises: selecting one or more of the plurality of serving cells based on the respective cell weightings for the plurality of serving cells; andtransmitting the data to the network node on the selected serving cells.

45. The method of claim 39, wherein one or more of the serving cells comprise cells on unlicensed spectrum.

46. A method performed by a network node configured to provide a plurality of serving cells, and the method comprising: receiving data from the wireless device on one or more of the serving cells based on respective cell weightings for the respective serving cells, wherein: the respective cell weightings are associated with respective logical channels, andeach of the serving cells has a different cell weighting associated with a different logical channel than other of the serving cells.

47. The method of claim 46, wherein receiving data from the wireless device on one or more of the serving cells comprises receiving respective amounts of the data on each of the one or more of the serving cells based on the respective cell weightings.

48. The method of claim 46, comprising determining the respective cell weightings for one or more of the serving cells based on one or more of the following: a delay or average delay for access to the serving cell by the wireless device and/or one or more other wireless devices,a number or rate of Listen Before Talk (LBT) failures for accessing the serving cell by the wireless device and/or one or more other wireless devices,an occupancy level of the serving cell,an interference level on the serving cell, andan estimated chance of LBT failure by the wireless device for accessing the serving cell.

49. The method of claim 46, comprising sending the respective cell weightings for the one or more of the serving cells to the wireless device.

50. The method of claim 46, comprising, before receiving the data, sending the wireless device one or more uplink grants for transmitting data on the plurality of the serving cells.

51. The method of claim 46, wherein one or more of the serving cells comprise cells on unlicensed spectrum.

52. A wireless device operable with a plurality of serving cells, the wireless device comprising: a processor; anda memory containing instructions executable by the processor, wherein execution of the instructions configures the wireless device to: transmit data to a network node on one or more of the serving cells based on respective cell weightings for the respective serving cells, wherein: the respective cell weightings are associated with respective logical channels, andeach of the serving cells has a different cell weighting associated with a different logical channel than other of the serving cells.

53. A network node operable to provide a plurality of serving cells, the network node comprising: a processor; anda memory containing instructions executable by the processor, wherein execution of the instructions configures the network node to perform operations corresponding to the method of claim 46.