WO2019036863A1

WO2019036863A1 - Hybrid autonomous and network activation of carrier aggregation

Info

Publication number: WO2019036863A1
Application number: PCT/CN2017/098355
Authority: WO
Inventors: Ling Yu; Haitao Li; Jedrzej STANCZAK; Vinh Van Phan
Original assignee: Nokia Solutions And Networks Oy; Nokia Shanghai Bell Co., Ltd
Priority date: 2017-08-21
Filing date: 2017-08-21
Publication date: 2019-02-28
Also published as: CN110999383A; CN110999383B

Abstract

A user equipment estimates one or more traffic loads associated with one or more of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation. The user equipment is then selectively enabled for autonomous activation of carrier aggregation based on the one or more traffic loads. A network controller provides information indicating the one or more thresholds. The network controller can then receive signaling indicating whether the user equipment is enabled for autonomous activation of carrier aggregation based on a comparison of the one or more thresholds to the one or more traffic loads estimated by the user equipment. In some cases, the traffic load as indicated by a channel busy ratio (CBR) that represents a fraction of time that the one or more of the plurality of resource pools is busy.

Description

HYBRID AUTONOMOUS AND NETWORK ACTIVATION OF CARRIER AGGREGATION

BACKGROUND

Vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X) communication is a form of device-to-device (D2D) communication that accounts for the characteristics of vehicles such as cars and trucks. For example， V2V or V2X communication can be performed over an interface that is enhanced for vehicular use cases and supports communication between nodes traveling at high relative speeds (up to 250 km/h) and high densities of vehicles (e.g.， thousands of nodes) . This interface can be referred to as a PC5 or side link (SL) interface. Services provided using V2V or V2X communication include vehicle platooning that enables vehicles to dynamically form a platoon traveling together， extended sensors that enable the exchange of raw or processed data among vehicles， roadside units， pedestrian devices， and V2X application servers， advanced driving to enable semi-automated or fully-automated driving， and remote driving that enables a remote driver or a V2X application to operate a remote vehicle.

SUMMARY OF EMBODIMENTS

The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the disclosed subject matter. This summary is not an exhaustive overview of the disclosed subject matter. It is not intended to identify key or critical elements of the disclosed subject matter or to delineate the scope of the disclosed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

In some embodiments， a method is provided for hybrid autonomous and network activation of carrier aggregation. The method includes estimating， at a user equipment， at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation. The method also includes selectively enabling the user equipment for autonomous activation of carrier aggregation based on the at least one traffic load.

In some embodiments， selectively enabling the user equipment for autonomous activation of carrier aggregation includes comparing the at least one traffic load to at least one first threshold.

In some embodiments， selectively enabling the user equipment for autonomous activation of carrier aggregation includes enabling the user equipment for autonomous activation of carrier aggregation in response to the at least one traffic load being less than the at least one first threshold.

In some embodiments， the method also includes receiving information indicating the at least one first threshold from a network controller via broadcast signaling or signaling dedicated to the user equipment.

In some embodiments， the method also includes transmitting， from the user equipment， a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.

In some embodiments， the method also includes receiving， at the user equipment， information indicating at least one second threshold for comparison to the at least one traffic load.

In some embodiments， receiving the information includes receiving information indicating whether the user equipment is permitted to enter an idle mode and utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.

In some embodiments， the method also includes providing， from the user equipment， an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.

In some embodiments， estimating the at least one traffic load includes determining at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.

In some embodiments， a method is provided for hybrid autonomous and network activation of carrier aggregation. The method includes providing， from a network controller to a user equipment， information indicating at least one first threshold for comparison with at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation. The method also includes receiving， at the network controller and from the user equipment， a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.

In some embodiments， providing the information indicating the at least one first threshold includes providing information indicating at least one first threshold for comparison with at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.

In some embodiments， providing the information indicating the at least one first threshold includes at least one of broadcasting the information indicating the at least one first threshold and transmitting a dedicated signal including the information indicating the at least one first threshold to the user equipment.

In some embodiments， the method also includes receiving， at the network controller， signaling indicating whether the user equipment is enabled for autonomous activation of carrier aggregation based on the comparison.

In some embodiments， the method also includes providing， from the network controller to the user equipment， information indicating at least one second threshold for comparison to the at least one traffic load.

In some embodiments， providing the information includes providing information indicating whether the user equipment is permitted to enter an idle mode and utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.

In some embodiments， the method also includes receiving， at the network controller and from the user equipment， an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.

In some embodiments， the method also includes providing， from the network controller， a reconfiguration message to configure the user equipment for network resource allocation or to configure the user equipment for carrier aggregation with at least one other resource pool that has capacity to admit the user equipment for carrier aggregation.

In some embodiments， a user equipment is provided that includes a transceiver configured to estimate at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation. The user equipment also includes a processor configured to selectively enable the user equipment for autonomous activation of carrier aggregation based on the at least one traffic load.

In some embodiments， the processor is configured to compare the at least one traffic load to at least one first threshold.

In some embodiments， the processor is configured to enable the user equipment for autonomous activation of carrier aggregation in response to the at least one traffic load being less than the at least one first threshold.

In some embodiments， the transceiver is configured to receive information indicating the at least one first threshold from a network controller via broadcast signaling or signaling dedicated to the user equipment.

In some embodiments， the transceiver is configured to transmit a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.

In some embodiments， the transceiver is configured to receive information indicating at least one second threshold for comparison to the at least one traffic load.

In some embodiments， the transceiver is configured to receive information indicating whether the user equipment is permitted to enter an idle mode and the processor is configured to utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.

In some embodiments， the transceiver is configured to provide an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.

In some embodiments， the transceiver is configured to determine at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.

In some embodiments， an apparatus is provided that includes a processor configured to generate information indicating at least one first threshold for comparison with at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation. The processor also includes a transceiver configured to transmit the information to a user equipment and receive， from a user equipment， a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.

In some embodiments， the transceiver is configured to provide information indicating at least one first threshold for comparison with at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.

In some embodiments， the transceiver is configured to perform at least one of broadcasting the information indicating the at least one first threshold and transmitting a dedicated signal including the information indicating the at least one first threshold to the user equipment.

In some embodiments， the transceiver is configured to receive signaling indicating whether the user equipment is enabled for autonomous activation of carrier aggregation based on the comparison.

In some embodiments， the transceiver is configured to provide， to the user equipment， information indicating at least one second threshold for comparison to the at least one traffic load.

In some embodiments， the transceiver is configured to provide information indicating whether the user equipment is permitted to enter an idle mode and utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.

In some embodiments， the transceiver is configured to receive， from the user equipment， an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.

In some embodiments， the transceiver is configured to provide a reconfiguration message to configure the user equipment for network resource allocation or to configure the user equipment for carrier aggregation with at least one other resource pool that has capacity to admit the user equipment for carrier aggregation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood， and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference symbols in different drawings indicates similar or identical items.

FIG. 1 is a block diagram of a first example of a wireless communication system according to some embodiments.

FIG. 2 is a block diagram of a second example of a wireless communication system that supports selectively enabling autonomous activation of carrier aggregation according to some embodiments.

FIG. 3 illustrates a first portion of a message flow that is used to support hybrid autonomous and network activation of carrier aggregation according to some embodiments.

FIG. 4 illustrates a second portion of a message flow that is used to support hybrid autonomous and network activation of carrier aggregation according to some embodiments.

DETAILED DESCRIPTION

Carrier aggregation is used to combine the resources of multiple carriers to support communication between two nodes. For example， multiple carriers at different frequencies can be aggregated to support communication between two vehicles in V2V communication or a vehicle and another node in V2X communication. Carrier aggregation can be used for parallel transmission of media access control (MAC) packet data units (PDUs) in which the carriers are used to transmit MAC PDUs having different payloads on different carriers at the same or different transmission times. Carrier aggregation can also be used for parallel transmission of replicated copies of the same packet on different carriers at the same or different transmission times. Carrier aggregation can further be used to increase capacity from the receiver perspective by combining the available capacities of the multiple carriers for simultaneous or concurrent reception by the receiver. Carrier aggregation can therefore be used to increase the available data rate and/or the reliability of transmission over interlaces such as the PC5 interlace.

User equipment can perform autonomous activation of carrier aggregation， which results in allocation of resources of the resource pool for each of the aggregated carriers. Autonomous activation does not require approval or confirmation by any network entity. Consequently， fully autonomous activation of carrier aggregation by user equipment can result in resource pool congestion on one or more of the carriers if a large number of user equipment concurrently activate carrier aggregation. Fully autonomous activation of carrier aggregation can also lead to unjustified excessive usage by some user equipment. Conventional congestion control mechanisms over a PC5 interface set limits on the resources and modulation/coding schemes (MCS) that are available to user equipment that are communicating over congested carriers， which may defeat the purpose of carrier aggregation， e.g.， by making it difficult or impossible for the user equipment to achieve the high data rates or high reliability provided by carrier aggregation.

Network controlled activation of carrier aggregation can be used to coordinate carrier aggregation among multiple user equipment， which can reduce the likelihood of resource pool congestion. For example， the network can receive requests to activate carrier aggregation from multiple user equipment and then selectively activate carrier aggregation for one or more of the requesting user equipment， e.g.， based on the available resources for each of the carriers. However， network control of carrier aggregation introduces additional signaling overhead between the user equipment and the network.

The lower overhead of autonomous activation of carrier aggregation is combined with the superior congestion control of network activation by selectively enabling user equipment for autonomous activation of carrier aggregation based on a traffic load associated with carriers that are available for aggregation. In some embodiments， the user equipment determines a channel busy ratio (CBR) that represents a fraction of time that one or more channels of resource pools associated with the carriers are busy. For example， the user equipment can measure signal strengths on the one or more channels and determine the CBR as a fraction of time that the measured signal strengths are above a value that indicates that the channel is occupied by one or more other transmitters. The user equipment autonomously activates carrier aggregation if the traffic load (e.g.， as represented by the CBR) is below a first threshold， which can be configured using broadcast or dedicated signaling. The first threshold can have a value that is common to the resource pools or different values for different resource pools of different carriers. The user equipment requests network activation of carrier aggregation if the traffic load is above the first threshold. In response to receiving the request， some embodiments of the network configure one or more base stations to schedule resource allocation for the user equipment on the carriers. The base stations can then activate carrier aggregation for the user equipment. The network can also increase the first threshold for autonomous activation in response to receiving the request.

FIG. 1 is a block diagram of a first example of a wireless communication system 100 according to some embodiments. The wireless communication system 100 operates according to one or more standards such as Long Term Evolution (LTE) ， LTE Advanced (LTE-A) ， or Fifth Generation (5G) standards defined by the Third Generation Partnership Project (3GPP) . The wireless communication system 100 includes one or more base stations 105 that provide wireless connectivity within a geographic area or cell. The base station 105 can also be referred to as a node B， an eNodeB， a radio access network， a macrocell， a base station router， access point， a metrocell， a macrocell， a picocell， a femtocell， or other similar terms.

User equipment

110， 111， 112 (collectively referred to herein as “the user equipment 110-112” ) are able to access the wireless communication system 100 using

wireless connections

115， 116， 117 (collectively referred to herein as “the wireless connections 115-117” ) . The user equipment 110-112 include

personal devices

110， 111 such as cell phones， smart phones， tablets， laptop computers， or other wireless enabled devices. The user equipment 110-112 also include vehicles such as the vehicle 112.

The wireless communication system 100 supports device-to-device (D2D) communication including vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X) communication. For example， the user equipment 110 can establish a direct D2D wireless connection 120 with the user equipment 111. For another example， the user equipment 111 can establish a direct V2V wireless connection 125 with the vehicle 112. As discussed herein， the

wireless connections

120， 125 can be implemented as PC5 connections or side link (SL) connections. The base station 105 is not in the communication path used by the

wireless connections

120， 125. Some embodiments of the D2D， V2V， or V2X communication protocols support voice or data transmission on a one-to-one basis (unicast) ， on a one-to-many basis (groupcast) for applications such as push-to-talk (PTT) ， or on a one-to-all basis (broadcast) . The user equipment 110-112 can also serve as relay stations for D2D communication between other user equipment.

The wireless connections 115-117， 120， 125 support multiple carriers that can be aggregated， e.g.， to increase the available data rate and/or the reliability of transmission over the wireless connections 115-117， 120， 125. Aggregated carriers include a primary carrier that is responsible for conveying control plane signaling and user plane signaling and one or more secondary carriers that are used to convey control plane signaling. Carrier aggregation can be activated by either the user equipment 110-112 or a network controller 130. As used herein， the term “activation” refers to allocation of resources from resource pools associated with the aggregated carriers as well as configuration of the user equipment 110-112 and corresponding wireless connections 115-117， 120， 125. User equipment 110-112 can autonomously activate carrier aggregation， which means that the user equipment 110-112 can activate carrier aggregation without requiring input or authorization from the network controller 130. Alternatively， the network controller 130 can activate carrier aggregation， e.g.， by configuring the base station 105 to allocate resources from the resource pools of the aggregated carriers to the corresponding user equipment 110-112 and then to schedule communication over the aggregated carriers. The network controller 130 and the base station 105 may be implemented in one network entity in some embodiments of the wireless communication system 100

The wireless communication system 100 implements a hybrid carrier aggregation activation technique that allows the user equipment 110-112 to autonomously activate carrier aggregation in some cases and relies on the network controller 130 (which may be implemented in the same physical entity as the base station 105) to activate carrier aggregation in other cases. The user equipment 110-112 are configured to autonomously activate carrier aggregation when the traffic load on one or more of the wireless connections 115-117， 120， 125 is relatively low. The network controller 130 is configured to activate carrier aggregation when the traffic load on one or more of the wireless connections 115-117， 120， 125 is relatively high. The network controller 130 can therefore effectively control the number of user equipment that are activating carrier aggregation in the configured carriers in high traffic load situations. The high and low traffic load conditions can be determined by comparing the traffic load to one or more thresholds， e.g.， threshold values of a channel busy ratio (CBR) that represents a fraction of time that a corresponding resource pool of a carrier is busy. In some embodiments， a common threshold is provided to the user equipment 110-112 and used to trigger autonomous activation of carrier aggregation by the user equipment 110-112. The network controller 130 can configure dedicated thresholds for subsets of the user equipment 110-112 to control the number of user equipment 110-112 that are allowed to autonomously activate carrier aggregation on one or more of the carriers. This approach also supports prioritization of the user equipment 110-112 that are sharing resource pools of the carriers.

Some embodiments of the network controller 130 provide information indicating one or more thresholds for comparison with traffic loads associated with resource pools for a carriers that are available for carrier aggregation. The threshold information can be broadcast by the base station 105 or the threshold information can be conveyed to individual user equipment 110-112 using dedicated signaling， e.g.， over the wireless connections 115-117. The values of the threshold can be common to (i.e.， the same for) the resource pools for different carriers or the values can be set to different values for different resource pools in the different carriers. The user equipment 110-112 can estimate a traffic load associated with one or more of the resource pools for the carriers that are available for carrier aggregation. The estimated traffic load can then be compared to the corresponding threshold value to determine whether the traffic load is low or high. The user equipment 110-112 selectively enable autonomous activation of carrier aggregation based on the comparison. The user equipment 110-112 may optionally transmit signaling to t he network controller 130 to indicate whether the user equipment 110-112 are enabled for autonomous activation of carrier aggregation. The signaling can include signals transmitted over aggregated carriers (if carrier aggregation is autonomously activated) or it can include a request for network control of carrier aggregation， as discussed herein.

FIG. 2 is a block diagram of a second example of a wireless communication system 200 that supports selectively enabling autonomous activation of carrier aggregation according to some embodiments. The wireless communication system 200 includes a user equipment 205， a base station 210， and a network controller 215. The communication system 200 can therefore be implemented in some embodiments of the communication system 100 shown in FIG. 1. The base station 210 and the network controller 215 are implemented in the same physical entity in some embodiments of the wireless communication system 200.

The user equipment 205 and the base station 210 include

transceivers

220， 225 for transmitting and receiving signals over one or more of a group 230 of carriers that are implemented by a wireless connection between the user equipment 205 and the base station 210. Although a wireless connection between the user equipment 205 and the base station 210 is shown in FIG. 2 in the interest of clarity， the transceiver 220 can also support similar wireless connections with other user equipment， e.g.， for D2D， V2V， or V2X communication， as discussed herein. Carriers within the group 230 are available for aggregation by the user equipment 205. For example， a subset 235 of the carriers can be aggregated. One of the carriers in the subset 235 can be configured as a primary carrier and the other carriers in the subset 235 can be configured as secondary carriers.

The user equipment 205 and the base station 210 also include corresponding

processors

240， 245 and

memories

250， 255. The processor is 240， 245 can be used to execute instructions stored in the corresponding

memories

250， 255 and to store information in the corresponding

memories

250， 255 such as the results of the executed instructions.

The network controller 215 includes a transceiver 260 for transmitting and receiving signals over an interface with the base station 210. The network controller also includes a processor 265 and a memory 270. The processor 265 can be used to execute instructions stored in the memory 270 and to store information in the memory 270 such as the results of the executed instructions.

The network controller 215 is configured to provide threshold values and other information to configure the user equipment 205 to selectively enable autonomous activation of carrier aggregation. Some embodiments of the network controller 215 provide signalling that is used to configure threshold values of a CBR (Th_ca_low) for the resource pools of the different carriers in the group 230. The user equipment 205 uses the threshold values to autonomously activate carrier aggregation if a measured value of a CBR is lower than Th_ca_low. The value of Th_ca_low can be configured with either broadcast or dedicated signaling from the base station 210. The value of Th_ca_low can be configured commonly to all the resource pools of the carriers in the group 230 or different values of Th_ca_low can be assigned to different resource pools in different carriers of the group 230. Some embodiments of the network controller 215 can provide information indicating whether the value of Th_ca_low is applied to all of the carriers that are available for aggregation or the value of Th_ca_low is only applied to secondary carriers. This information can also be predefined so that the network controller 215 is not required to provide the information. Some embodiments of the network controller 215 provide configuration information to indicate whether network-controlled activation of carrier aggregation is supported or not. For example， the network controller 215 can provide configuration information to indicate to the user equipment 205 whether an activation request for carrier aggregation should be sent to the network controller 215 when no resource pool with a value of the CBR lower than Th_ca_low can be found for autonomous activation of carrier aggregation.

In relatively highly loaded scenarios， some embodiments of the network controller 215 are configured to enable fully network-controlled activation of carrier aggregation by allocating resources of the dedicted resource pools of aggregated carriers (e.g.， the subset 235) . The network controller 215 or the base station 210 can also schedule communication over the aggregated carriers. This can be referred to as “mode 3” operation. The network controller 215 can also modify the threshold value in response to the user equipment 205 being unable to autonomously activate carrier aggregation. Some embodiments of the network controller 215 configure the user equipment 205 to continue with autonomous activation of carrier aggregation but with a modified CBR threshold Th_ca_high (which is greater than Th_ca_low) . The network controller 215 can also perform network-controlled activation of carrier aggregation by configuring the user equipment 205 to aggregate carriers using specific resource pools in different carriers.

Network-controlled activation of carrier aggregation can be triggered by a request for activation of carrier aggregation that is transmitted by the user equipment 205 and received by the network controller 215. In some embodiments， the response of the network controller 215 to the request for activation of carrier aggregation is determined based on whether or not the network controller 215 previously configured the user equipment 205 to selectively enable autonomous activation of carrier aggregation on the basis of a modified threshold value Th_ca_high. For example， if the network controller 215 receives a subsequent request for activation of carrier aggregation after the network controller 215 configured the user equipment 205 with the modified threshold value Th_ca_high， the network controller 215 can enable the base station 210 to perform mode 3 resource allocation for the user equipment 205 to allow the base station 210 control activation of carrier aggregation. Alternatively， the network controller 215 can configure the user equipment 205 with specific resource pools that are used for carrier aggregation if there is still capacity in those pools to admit the user equipment 205 for carrier aggregation.

In cases where the network controller 215 decides to configure the user equipment 205 to continue with autonomous activation of carrier activation， the network controller 215 can configure the user equipment 205 with the modified CBR threshold Th_ca_high via dedicated signaling. The value of Th_ca_high can be common for all the carriers or the value of Th_ca_high can be different for different carriers. The value of Th_ca_high can configured to be applied for all carriers (e.g.， primary carriers and secondary carriers) or only secondary carriers. The network controller 215 can also indicate to the user equipment 205 whether an activation request for carrier aggregation can be sent to the network controller 215 if no resource pool with CBR lower than Th_ca_high can be found. In addition to Th_ca_high， the network controller 215 is also able to configure the user equipment 205 to enter an idle mode while still using Th_ca_high for autonomous activation of carrier aggregation.

Some embodiments of the user equipment 205 determine whether to autonomously activate carrier aggregation or request network control of activation of carrier aggregation based on values of thresholds that are configured by the network controller 215. The threshold values can be stored in the memory 250 along with other configuration information. For example， the user equipment 205 can determine to autonomously activate carrier aggregation in response to a measured value of a CBR in resource pools of concerned carriers (either in both primary and secondary carriers or only in secondary carriers， based on configuration information received from the network controller 215) being lower than Th_ca_low or Th_ca_high (if Th_ca_high has been configured， as discussed herein) . The user equipment 205 provides a request to the network controller 215 to provide control of activation of carrier aggregation if the user equipment 205 is unable to identify any resource pools that have measured values of a CBR that is lower than the configured values of Th_ca_low or Th_ca_high. The request for network control can be provided if the network controller 215 has previously provided information indicating that network controlled activation of carrier aggregation is supported when Th_ca_low or Th_ca_high is configured. Some embodiments of the user equipment 205 are able to enter an idle state (or idle mode) after Th_ca_high is configured and the user equipment 205 can continue using Th_ca_high for autonomous activation of carrier aggregation while in the idle state. The network controller 215 can provide configuration information that configures the user equipment 205 to continue to perform autonomous activation of carrier aggregation while in the idle state.

Hand off of the user equipment 205 to another base station can result in reconfiguration of the user equipment 205 for autonomous activation of carrier aggregation. For example， the value of the threshold Th_ca_high that was previously configured in the user equipment 205 may not be valid after user equipment 205 reselects to a new cell. In this case， the user equipment 205 can transmit a request to the network controller 215 to request network control of activation of carrier aggregation if the user equipment 205 is unable to locate any resource pools that have values of CBR that are lower than a threshold value Th_ca_low that is configured by the new reselected cell.

Some embodiments of the user equipment 205 transmit an activation request for carrier aggregation to the network controller 215 in order to request network control of activation of carrier aggregation. The activation request is triggered by comparison of a traffic load (e.g.， a measured value of CBR) and the activation request can indicate whether the user equipment 205 was configured to compare the traffic load to the threshold value Th_ca_low or the modified threshold value Th_ca_high. The user equipment 205 can transmit the information indicating which threshold value was used if the user equipment 205 is operating in the idle state because the network controller 215 is not have access to a context for the user equipment 205 and therefore is not able to determine whether Th_ca_high has been configured to the user equipment 205.

Some embodiments of the user equipment 205 provide scheduling assignments of SL transmission to the other user equipment to indicate whether the user equipment 205 is configured to use the threshold Th_ca_low or the modified threshold Th_ca_high to selectively enable autonomous activation of carrier aggregation. Based on the indication in the scheduling assignment， the SL transmission by other user equipment that are configured to use the threshold Th_ca_low may be preempted in favor of user equipment that are configured to use the modified threshold Th_ca_high in the event of an SL transmission resource collision between the two user equipment.

FIG. 3 illustrates a first portion 300 of a message flow that is used to support hybrid autonomous and network activation of carrier aggregation according to some embodiments. The first portion 300 of the message flow thai illustrates messages exchanged between a network (NW) and a user equipment (UE) . For example， the first portion 300 can represent messages exchanged between the network controller 130 and one or more of the user equipment 110-112 shown in FIG. 1 or messages exchanged between the network controller 215 and the user equipment 205 shown in FIG. 2.

The network provides configuration information including a first threshold (such as the threshold Th_ca_low) in a message 305. Some embodiments of the message 305 are a side link carrier aggregation (SL_CA) configuration message. The message 305 can be embedded into a system information block (SIB) such as a V2X related SIB or the message 305 can be incorporated in an RRC reconfiguration message that is used to perform V2X related configuration of the user equipment.

The user equipment uses the first threshold to configure monitoring of a traffic load on a set of configured carriers that are available for carrier aggregation. The user equipment determines whether the traffic load exceeds the first threshold at decision block 310. For example， the user equipment can compare a measured value of a CBR associated with one or more of the carriers to a value of the threshold Th_ca_low. If the traffic load is less than the first threshold， indicating that allocating resources to carrier aggregation is unlikely to create congestion in the network， the user equipment can autonomously activate carrier aggregation of one or more of the set of configured carriers at block 315. If the traffic load is greater than the first threshold， indicating that autonomous allocation of resources to carrier aggregation could create congestion and therefore network coordination may be necessary to avoid congestion， the user equipment can generate a request for network control of activation of carrier aggregation at block 320. In some embodiments， the user equipment can perform comparisons to the configured threshold， such as an SIB configured CBR threshold， while the user equipment is in an RRC idle state. If the comparison triggers transmission of a request for network control of activation， the user equipment can transition to an RRC connected state to transmit the request in the message 325.

The user equipment transmits an activation request for network control of activation of carrier aggregation to the network in message 325. Some embodiments of the message 325 are embedded into an RRC message such as a RRC SidelinkUEInformation message. The message 325 can also include an indication that the message 325 has been generated and transmitted in response to a comparison of the traffic load to the first threshold， e.g.， a comparison of the measured value of the CBR to the value of the threshold Th_ca_low. In response to receiving the message 325 including the indication of the first threshold， the network can configure (at block 330) a second threshold for transmission to the user equipment. For example， the network can generate a modified threshold value Th_ca_high that is larger than the value of the threshold Th_ca_low. The network provides the second threshold value to the user equipment in a message 335. For example， the message 335 can be embedded in an RRC SL_CA configuration message that includes the modified threshold value Th_ca_high.

FIG. 4 illustrates a second portion 400 of a message flow that is used to support hybrid autonomous and network activation of carrier aggregation according to some embodiments. The second portion 400 of the message flow that illustrates messages exchanged between a network (NW) and a user equipment (UE) . For example， the second portion 400 can represent messages exchanged between the network controller 130 and one or more of the user equipment 110-112 shown in FIG. 1 or messages exchanged between the network controller 215 and the user equipment 205 shown in FIG. 2. In some embodiments， the second portion 400 of the message flow is performed subsequent to the first portion 300 of the message flow shown in FIG. 3.

The network provides a second threshold value to the user equipment in a message 405. For example， the message 405 can be embedded in an RRC SL_CA configuration message that includes the modified threshold value Th_ca_high. The message 405 can therefore correspond to the message 335 in the first portion 300 of the message flow shown in FIG. 3.

The user equipment uses the second threshold to configure monitoring of a traffic load on a set of carriers that are configured to be available for carrier aggregation. The user equipment determines whether the traffic load exceeds the second threshold at decision block 410. For example， the user equipment can compare a measured value of a CBR associated with one or more of the carriers to a value of the modified threshold Th_ca_high. If the traffic load is less than the second threshold， indicating that allocating resources to carrier aggregation is unlikely to create congestion in the network， the user equipment can autonomously activate carrier aggregation of one or more of the set of configured carriers at block 415. If the traffic load is greater than the second threshold， indicating that autonomous allocation of resources to carrier aggregation could create congestion and therefore network coordination may be necessary to avoid congestion， the user equipment can generate a request for network control of activation of carrier aggregation at block 420.

The user equipment transmits an activation request for network control of activation of carrier aggregation to the network in message 425. Some embodiments of the message 425 are embedded into an RRC message such as a RRC SidelinkUEInformation message. The message 425 can also include an indication that the message 425 has been generated and transmitted in response to a comparison of the traffic load to the second threshold， e.g.， a comparison of the measured value of the CBR to the value of the threshold Th_ca_high. In some embodiments， the user equipment can perform comparisons to the configured threshold， such as an SIB configured CBR threshold， while the user equipment is in an RRC idle state. If the comparison triggers transmission of a request for network control of activation， the user equipment can transition to an RRC connected state to transmit the request in the message 425.

In response to receiving the message 425 including the indication of the second threshold， the network can configure (at block 430) mode 3 operation or allocate specific resource pools to the user equipment for carrier aggregation. For example， if the network configures mode 3 operation， the network can transmit instructions to configure one or more base stations to schedule resource allocation for the user equipment on the carriers. The base stations can then activate carrier aggregation for the user equipment. For another example， the network can identify specific resource pools that can be used for carrier aggregation because these resource pools have available capacity to admit the user equipment for carrier aggregation. The network provides the configuration information to the user equipment in a message 435. For example， the message 435 can be embedded in an RRC reconfiguration message that includes parameters that are used to configure the user equipment for mode 3 operation or carrier aggregation using the available resource pools identified by the network.

In some embodiments， certain aspects of the techniques described above may implemented by one or more processors of a processing system executing software. The software comprises one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer readable storage medium. The software can include the instructions and certain data that， when executed by the one or more processors， manipulate the one or more processors to perform one or more aspects of the techniques described above. The non-transitory computer readable storage medium can include， for example， a magnetic or optical disk storage device， solid state storage devices such as Flash memory， a cache， random access memory (RAM) or other non-volatile memory device or devices， and the like. The executable instructions stored on the non-transitory computer readable storage medium may be in source code， assembly language code， object code， or other instruction format that is interpreted or otherwise executable by one or more processors.

A computer readable storage medium may include any storage medium， or combination of storage media， accessible by a computer system during use to provide instructions and/or data to the computer system. Such storage media can include， but is not limited to， optical media (e.g.， compact disc (CD) ， digital versatile disc (DVD) ， Blu-Ray disc) ， magnetic media (e.g.， floppy disc， magnetic tape， or magnetic hard drive) ， volatile memory (e.g.， random access memory (RAM) or cache) ， non-volatile memory (e.g.， read-only memory (ROM) or Flash memory) ， or microelectromechanical systems (MEMS) -based storage media. The computer readable storage medium may be embedded in the computing system (e.g.， system RAM or ROM) ， fixedly attached to the computing system (e.g.， a magnetic hard drive) ， removably attached to the computing system (e.g.， an optical disc or Universal Serial Bus (USB) -based Flash memory) ， or coupled to the computer system via a wired or wireless network (e.g.， network accessible storage (NAS) ) .

Note that not all of the activities or elements described above in the general description are required， that a portion of a specific activity or device may not be required， and that one or more further activities may be performed， or elements included， in addition to those described. Still further， the order in which activities are listed are not necessarily the order in which they are performed. Also， the concepts have been described with reference to specific embodiments. However， one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Accordingly， the specification and figures are to be regarded in an illustrative rather than a restrictive sense， and all such modifications are intended to be included within the scope of the present disclosure.

Benefits， other advantages， and solutions to problems have been described above with regard to specific embodiments. However， the benefits， advantages， solutions to problems， and any feature (s) that may cause any benefit， advantage， or solution to occur or become more pronounced are not to be construed as a critical， required， or essential feature of any or all the claims. Moreover， the particular embodiments disclosed above are illustrative only， as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. No limitations are intended to the details of construction or design herein shown， other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope of the disclosed subject matter. Accordingly， the protection sought herein is as set forth in the claims below.

Claims

A method comprising：

estimating， at a user equipment， at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation； and

selectively enabling the user equipment for autonomous activation of carrier aggregation based on the at least one traffic load.
The method of claim 1， wherein selectively enabling the user equipment for autonomous activation of carrier aggregation comprises comparing the at least one traffic load to at least one first threshold.
The method of claim 2， wherein selectively enabling the user equipment for autonomous activation of carrier aggregation comprises enabling the user equipment for autonomous activation of carrier aggregation in response to the at least one traffic load being less than the at least one first threshold.
The method of claim 2， further comprising：

receiving information indicating the at least one first threshold from a network controller via broadcast signaling or signaling dedicated to the user equipment.
The method of claim 2， further comprising：

transmitting， from the user equipment， a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.
The method of claim 5， further comprising：

receiving， at the user equipment， information indicating at least one second threshold for comparison to the at least one traffic load.
The method of claim 6， wherein receiving the information comprises receiving information indicating whether the user equipment is permitted to enter an idle mode and utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.
The method of claim 6， further comprising：

providing， from the user equipment， an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.
The method of claim 1， wherein estimating the at least one traffic load comprises determining at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.
A method comprising：

providing， from a network controller to a user equipment， information indicating at least one first threshold for comparison with at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation； and

receiving， at the network controller and from the user equipment， a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.
The method of claim 10， providing the information indicating the at least one first threshold comprises providing information indicating at least one first threshold for comparison with at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.
The method of claim 10， wherein providing the information indicating the at least one first threshold comprises at least one of：

broadcasting the information indicating the at least one first threshold； and

transmitting a dedicated signal including the information indicating the at least one first threshold to the user equipment.
The method of claim 10， further comprising：

receiving， at the network controller， signaling indicating whether the user equipment is enabled for autonomous activation of carrier aggregation based on the comparison.
The method of claim 10， further comprising：

providing， from the network controller to the user equipment， information indicating at least one second threshold for comparison to the at least one traffic load.
The method of claim 14， wherein providing the information comprises providing information indicating whether the user equipment is permitted to enter an idle mode and utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.
The method of claim 10， further comprising：

receiving， at the network controller and from the user equipment， an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.
The method of claim 14， further comprising：

providing， from the network controller， a reconfiguration message to configure the user equipment for network resource allocation or to configure the user equipment for carrier aggregation with at least one other resource pool that has capacity to admit the user equipment for carrier aggregation.
A user equipment comprising：

a transceiver configured to estimate at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation； and

a processor configured to selectively enable the user equipment for autonomous activation of carrier aggregation based on the at least one traffic load.
The user equipment of claim 18， wherein the processor is configured to compare the at least one traffic load to at least one first threshold.
The user equipment of claim 19， wherein the processor is configured to enable the user equipment for autonomous activation of carrier aggregation in response to the at least one traffic load being less than the at least one first threshold.
The user equipment of claim 19， wherein the transceiver is configured to receive information indicating the at least one first threshold from a network controller via broadcast signaling or signaling dedicated to the user equipment.
The user equipment of claim 19， wherein the transceiver is configured to transmit a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.
The user equipment of claim 22， wherein the transceiver is configured to receive information indicating at least one second threshold for comparison to the at least one traffic load.
The user equipment of claim 23， wherein the transceiver is configured to receive information indicating whether the user equipment is permitted to enter an idle mode， and wherein the processor is configured to utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.
The user equipment of claim 23， wherein the transceiver is configured to provide an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.
The method of claim 18， wherein the transceiver is configured to determine at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.
An apparatus comprising：

a processor configured to generate information indicating at least one first threshold for comparison with at least one traffic load associated with at least one of a plurality of resource pools for a plurality of carriers that are available for carrier aggregation， and

a transceiver configured to receive， from the user equipment， a request for network activation of carrier aggregation in response to the at least one traffic load being greater than the at least one first threshold.
The apparatus of claim 27， wherein the transceiver is configured to provide information indicating at least one first threshold for comparison with at least one channel busy ratio (CBR) that represents a fraction of time that the at least one of the plurality of resource pools is busy.
The apparatus of claim 27， wherein the transceiver is configured to perform at least one of：

broadcasting the information indicating the at least one first threshold； and

transmitting a dedicated signal including the information indicating the at least one first threshold to the user equipment.
The apparatus of claim 27， wherein the transceiver is configured to transmit the information to a user equipment and receive signaling indicating whether the user equipment is enabled for autonomous activation of carrier aggregation based on the comparison.
The apparatus of claim 27， wherein the transceiver is configured to provide， to the user equipment， information indicating at least one second threshold for comparison to the at least one traffic load.
The apparatus of claim 31， wherein the transceiver is configured to provide information indicating whether the user equipment is permitted to enter an idle mode and utilize the at least one second threshold to selectively enable autonomous activation of carrier aggregation.
The apparatus of claim 31， wherein the transceiver is configured to provide a reconfiguration message to configure the user equipment for network resource allocation or to configure the user equipment for carrier aggregation with at least one other resource pool that has capacity to admit the user equipment for carrier aggregation.
The apparatus of claim 27， wherein the transceiver is configured to receive， from the user equipment， an indication of whether the at least one first threshold or the at least one second threshold were used to enable autonomous activation of carrier aggregation in response to enabling autonomous activation of carrier aggregation.