WO2017105268A1

WO2017105268A1 - A communication apparatus and method of component carrier assignment in a multi-carrier radio network

Info

Publication number: WO2017105268A1
Application number: PCT/RU2015/000884
Authority: WO
Inventors: Dmitrii Sergeevich MINENKOV; Victor Vladimirovich KUZNETSOV; Dmitri Alfredovich SHMELKIN; Suwen TANG; Yusun Fu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2015-12-15
Filing date: 2015-12-15
Publication date: 2017-06-22
Also published as: CN108370295A

Abstract

The invention relates to a communication apparatus (100) for assigning a user equipment (UE) (101) to at least one component carrier (CC) of a plurality of CCs of a communication channel (103), comprising: a communication interface (105) being configured to communicate with the UE (101) using the at least one CC of the plurality of CCs; a processor (107) being configured to determine an efficiency factor of a communication between the UE (101) and the communication apparatus for each CC of the plurality of CCs, wherein the processor is further configured to determine a communication load associated with each CC of the plurality of CCs, and wherein the processor is further configured to determine a composite quality measure for each CC from the determined efficiency factor and communication load; wherein the processor (107) is configured to select at least one CC of the plurality of CCs based on the composite quality measure, and to assign the UE (101) to the at least one selected CC.

Description

A COMMUNICATION APPARATUS AND A METHOD OF COMPONENT CARRIER ASSIGNMENT IN A MULTI-CARRIER RADIO NETWORK

TECHNICAL FIELD

Generally, the present invention relates to wireless communication. More specifically, the present invention relates to a communication apparatus capable of component carrier assignment and a method of operating such a communication apparatus.

BACKGROUND

Carrier aggregation is a technology used in mobile communication networks for enhancing the data rate, and hence bandwidth, of each user equipment (UE) in the network. In carrier aggregation each UE can be assigned to one or several component carriers (CC) of a communication channel.

Many issues arise in wireless network management with regard to carrier aggregation. One of them is the component earner assignment problem, i.e. the problem of assigning a UE to one or several CCs of the communication channel. The UEs in the communication network can share the CCs of the communication channel as per different scheduling schemes, which give rise to the scheduler problem. The network performance depends significantly on both the CC assignment and the scheduling policies. However, since a scheduler and a CC assignment algorithm can work with different periodicities, it is possible to separate their effects.

These resource management problems in wireless networks are further complicated by different channel efficiencies of the CCs for each UE, which means that different UEs can communicate with different data rates over the same CC. In addition, each UE in the communication network can be assigned to different CCs and to a different number of CCs.

Usually the communication network has several goals, such as network throughput and network fairness. Coordinating a CC assignment policy with a scheduler and providing balance between the goals of the communication network is difficult. Hence, there is a need for improved CC assignment techniques.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a communication apparatus and a method of operating a communication apparatus implementing an improved component carrier assignment technique.

The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, the invention relates to a communication apparatus for assigning a user equipment (UE) to at least one component carrier (CC) of a plurality of CCs of a communication channel, comprising: a communication interface being configured to communicate with the UE using the at least one CC of the plurality of CCs, a processor being configured to determine an efficiency factor of a communication between the UE and the communication apparatus for each CC of the plurality of CCs, wherein the processor is further configured to determine a communication load associated with each CC of the plurality of CCs, and wherein the processor is further configured to determine a composite quality measure for each CC from the determined efficiency factor and communication load; wherein the processor is configured to select at least one CC of the plurality of CCs based on the composite quality measure, and to assign the UE to the at least one selected CC.

By assigning the UE to the at least one CC based on the efficiency factor and the communication load, a more efficient assignment can be realized as compared to, for example, only using either the efficiency factor, or the communication load. Thus, it is possible to avoid the assignment of UEs to CCs with large efficiency factors but also high communication loads. Likewise it is possible to avoid the assignment of UEs to CCs with low communication loads but also low efficiency factors.

The assigned CC can be a primary CC for the communication between the UE and the communication apparatus. In this case, the UE can be a new UE that was previously not assigned to a CC of the plurality of CCs, or a UE that was previously assigned to a CC of the plurality of CCs and that changes its CC.

The CCs can comprise subcarriers that can be grouped into physical resource blocks. Each CC can consist of several resource blocks. A resource block can be a time and/or frequency resource that occupies a number of subcarriers, for instance 12 subcarriers, of the CC.

The communication apparatus can be a base station.

In a first possible implementation form of the communication apparatus according to the first aspect, the processor is configured to determine the composite quality measure of each CC of the plurality of CCs as a ratio of the respective efficiency factor for the UE and each CC, to the respective communication load of each CC.

This provides the advantage that the ratio of the efficiency factor to the communication load provides an efficient composite quality measure on the basis of which the processor can select a CC of the plurality of CCs for the UE.

The processor can further be configured to calculate the ratio of the power A of the efficiency factor to the power B of the communication load, according to Rcc^A / Lcc^B, wherein R_Cc is the efficiency factor and L_Cc is the communication load, and A and B are predefinable numbers. This allows enhancing the influence of either the efficiency factor, or the communication load on the composite quality measure and thus the assignment of the UE to the CC.

In a second possible implementation form of the communication apparatus according to the first aspect as such or the first implementation form thereof, the processor is configured to determine a ranking of the CCs upon the basis of the composite quality measures, wherein the processor is configured to assign the UE to the at least one CC, which is associated with a highest rank among the CCs.

This provides the advantage that an efficient assignment of the UE to the at least one CC based on both the efficiency factor and the communication load of each CC can be performed.

In a third possible implementation form of the communication apparatus according to the first aspect as such or the first or the second implementation form thereof, the efficiency factor for each CC of the plurality of CCs is one or a combination of the following values: a signal to noise and interference ratio (SINR) of the CC, a reference signal received power (RSRP) of the CC, a reference signal received quality (RSRQ) of the CC, a channel efficiency, in particular the transmission rate of data that can be transmitted between the communication apparatus and the UE via the CC.

Furthermore the efficiency factor of each CC of the plurality of CCs can be an uplink or a downlink channel efficiency for the UE and each CC raised to the power D, wherein D is a predefinable number, for instance, D = 1/a, wherein a is a fairness of a scheduler.

In a fourth possible implementation form of the communication apparatus according to the third implementation form of the first aspect, the processor is configured to determine the SI R and/or the RSRP and/or the RSRQ for the communication between the UE and the communication apparatus for each CC of the plurality of CCs, wherein the processor can be configured to determine the SINR and/or the RSRP and/or the RSRQ as average values of all resource blocks on the CC over several transmit time intervals (TTIs).

In a fifth possible implementation form of the communication apparatus according to the first aspect as such or any one of the first to fourth implementation form thereof, the communication load associated with the CC of the plurality of CCs is one or a combination of the following values: the number of UEs assigned to the CC, the ratio of the number of resource blocks that are currently used for transmission using the CC to the total number of resource blocks on the CC, the amount of data that is currently transmitted using the CC, a remaining processing time that is required to transmit the amount of data, or a sum of functions based on the efficiency factors of communication between the UEs that are currently assigned to the CC and the communication apparatus.

Furthermore, the communication load can be a sum of the efficiency factors to the power of E, wherein E is a predefinable number, for instance, E = (1-α)/α.

In a sixth possible implementation form of the communication apparatus according to the first aspect as such or any one of the first to fifth implementation form thereof, the processor is configured to select at least one further CC of the plurality of CCs for the UE based on the composite quality measures of the CCs which are currently not assigned to the UE, and wherein the processor is further configured to assign the UE to the further selected CC.

This provides the advantage that an efficient assignment of the at least one further CC can be realized. This further assigned CC of the plurality of CCs can be a secondary CC for the communication between the UE and the communication apparatus, if the UE is already assigned to a primary CC.

In a seventh possible implementation form of the communication apparatus according to the sixth implementation form of the first aspect, the processor is configured to assign the UE to the at least one further CC if a communication parameter of the UE, in particular the amount of data that is exchanged between the UE and the communication apparatus, reaches a threshold value, and to quit the assignment of the UE to the further CC, if the communication parameter is smaller than the threshold value.

This provides the advantage that with the assignment of the further CC to the UE a high data rate between the UE and the communication apparatus can be guaranteed. This further assignment of the CC to the UE can be applicable, when the amount of data that is exchanged between the UE and the communication apparatus is large, for instance during a download or an upload of a large dataset. The assignment of the at least one further CC can result in a higher data rate for the communication. The assignment can be quit as soon as the amount of data is smaller than the threshold value, in order to decrease the communication load of the further CC.

In an eighth possible implementation form of the communication apparatus according to the first aspect as such or any one of the first to seventh implementation form thereof, the communication apparatus comprises a memory, wherein the processor is configured to store the efficiency factor, the communication load and the composite quality measure in the memory.

This provides the advantage that an efficient determination of composite quality measures based on the stored efficiency factors and the communication loads can be achieved. The processor can use the stored values when assigning new UEs to at least one CC of the plurality of CCs, for instance for efficiently determining the efficiency factors of communication between the new UEs and the communication apparatus for the CCs or for efficiently determining the communication load of the CCs. Furthermore, computation time can be reduced since composite quality measures for all CCs and UEs do not have to be calculated anew for each new UE which is assigned to a CC of the plurality of CCs.

In a ninth possible implementation form of the communication apparatus according to the first aspect as such or any one of the first to eighth implementation form thereof, the communication interface is configured to communicate with the UE in an uplink or a downlink direction.

This provides the advantage that the assignment of the UE to the at least one CC of the plurality of CCs can be based on an uplink or a downlink efficiency factor, and an uplink or a downlink communication load of each CC. Different rules for determining the composite quality measure in uplink and downlink direction can be applied, for instance, different powers A and B of the efficiency factors and communication loads in the uplink and downlink direction.

In a tenth possible implementation form of the communication apparatus according to the first aspect as such or any one of the first to ninth implementation form thereof, the communication apparatus is configured to communicate with UEs of a set of UEs, wherein the communication apparatus is configured to determine a priority measure for each UE of the set of UEs, to select a further UE from the set of UEs which is associated with the highest priority measure, and to assign the further UE from the set of UEs to the at least one CC of the plurality of CCs.

This provides the advantage that the communication apparatus can first assign the UEs of the set of UEs which have a high priority, for instance CCs that can only communicate at high data rates when assigned to one particular CC of the plurality of CCs, and can subsequently assign the UEs of the set of UEs with lower priority, for instance UEs which can communicate with approximately the same data rate regardless of which CC of the plurality of CCs they are assigned to.

In an eleventh possible implementation form of the communication apparatus according to the tenth implementation form of the first aspect, the processor is configured to determine the priority measure for each UE of the set of UEs based on one or a combination of the following values: a maximum or average of the efficiency factors for the UE and each CC, a maximum or average ratio of the efficiency factors for the UE and each CC, to the communication load of each respective CC, or a ratio of the maximal efficiency factor to the minimal, average or submaximal efficiency factor for the UE and each CC.

This provides the advantage that an efficient determination of the priority measure for each UE of the set of UEs can be realized.

In a twelfth possible implementation form of the communication apparatus according to the tenth or eleventh implementation form of the first aspect, the processor is configured to select, after assigning the further UE with the highest priority measure from the set of UEs to the at least one CC, a further UE with the next highest priority measure from the set of UEs, and to assign the selected further UE with the next highest priority measure to the at least one CC.

This provides the advantage that the processor can subsequently assign the UEs to the at least one CC in the order of their priority measures until all UEs are assigned to at least one CC of the plurality of CCs.

According to a second aspect, the invention relates to a method for assigning a UE to at least one CC of a plurality of CCs of a communication channel, comprising: determining an efficiency factor of a communication between the UE and the communication apparatus for each CC of the plurality of CCs, determining a communication load associated with each CC of the plurality of CCs, determining a composite quality measure for each CC from the determined efficiency factor and communication load, selecting at least one CC of the plurality of CCs based on the composite quality measure, and assigning the at least one selected CC to the UE.

In a first possible implementation form of the method according to the second aspect, UEs from a set of UEs are assigned to at least one CC of the plurality of CCs, wherein the method further comprises: determining a priority measure for each UE of the set of UEs, selecting a further UE from the set of UEs which is associated with the highest priority measure, and assigning the selected further UE from the set of UEs to at least one CC of the plurality of CCs.

The method according to the second aspect of the invention can be performed by the communication apparatus according to the first aspect of the invention. Further features of the method according to the second aspect of the invention result directly from the functionality of the communication apparatus according to the first aspect of the invention and its different implementation forms.

According to a third aspect, the invention relates to a computer program comprising program code for performing the method according to the second aspect of the invention when executed on a processor.

The invention can be implemented in hardware and/or software.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which:

Fig. 1 shows a schematic diagram of a communication apparatus according to an embodiment;

Fig. 2a shows a schematic diagram of a method for assigning a UE to at least one CC of a plurality of CCs according to an embodiment;

Fig. 2b shows a schematic diagram of a method for assigning a UE from a set of UEs to at least one CC of a plurality of CCs according to an embodiment;

Fig. 3 shows a schematic diagram of a communication apparatus according to an embodiment;

Fig. 4 shows a schematic diagram of a wireless communication network according to an embodiment; and

Fig. 5 shows a ranking of a set of UEs for the assignment with CCs based on three different priority measures.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following detailed description, reference is made to the accompanying drawings, which form a part of the disclosure, and in which are shown, by way of illustration, specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

Figure 1 shows a schematic diagram of a communication apparatus 100 for assigning a user equipment (UE) 101 to at least one component carrier (CC) of a plurality of CCs of a communication channel 103 according to an embodiment.

The communication apparatus 100 comprises a communication interface 105 configured to communicate with the UE 101 using the at least one CC of the plurality of CCs. The communication apparatus 100 further comprises a processor 107 configured to determine an efficiency factor of a communication between the UE 101 and the communication apparatus 100 for each CC of the plurality of CCs, wherein the processor 107 is further configured to determine a communication load associated with each CC of the plurality of CCs, and wherein the processor 107 is further configured to determine a composite quality measure for each CC from the determined efficiency factor and communication load; wherein the processor 107 is configured to select at least one CC of the plurality of CCs based on the composite quality measure, and to assign the UE 101 to the at least one selected CC.

By assigning the UE 101 to the at least one CC based on the efficiency factor and the communication load a more efficient assignment can be realized as compared to, for example, only using either the efficiency factor, or the communication load. Thus, it is possible to avoid the assignment of UEs to CCs with large efficiency factors but also high communication loads. Likewise it is possible to avoid the assignment of UEs to CCs with low communication loads but also low efficiency factors.

The assigned CC can be a primary CC for the communication between the UE 101 and the communication apparatus 100. In this case the UE 101 can be either a new UE that was previously not assigned to a CC of the plurality of CCs, or a UE that was previously assigned to a CC of the plurality of CCs and that changes its primary CC.

The communication apparatus 100 can be a base station.

In the exemplary scenario shown in figure 1 the communication apparatus 100 comprises a memory 109. The processor 107 can be configured to store the efficiency factor, the communication load and the composite quality measure in the memory 109.

The processor 107 can be configured to use the stored values when assigning new UEs to the at least one CC of the plurality of CCs, for instance for efficiently determining the efficiency factors of a communication between the new UEs and the communication apparatus for the CCs or for the efficiently determining the communication load of the CCs. In an embodiment, the processor 107 is configured to determine the composite quality measure P_Cc of each CC of the plurality of CCs as a ratio of the respective efficiency factor R_Cc for the UE 101 and each CC, to the respective communication load Lcc of each CC, according to: Pec = ^ (1)

In an embodiment, the processor 107 is configured to determine the composite quality measure Pec of each CC of the plurality of CCs as a ratio of the respective efficiency factor R_Cc for the UE 101 and each CC raised to the power A, to the respective communication load Lcc of each CC raised to the power B, i.e.: (2)

^Lcc

wherein A and B are predefinable numbers. This allows enhancing the influence of either the efficiency factor, or the communication load on the composite quality measure, and thus the assignment of the UE 101 to the CC.

In an embodiment, the processor 107 is configured to further consider UE delays, buffers, QoS or other UE parameters when calculating the composite quality measure.

In an embodiment, the processor 107 is configured to determine a ranking of the CCs upon the basis of the composite quality measures Pec, wherein the processor 107 is further configured to assign the UE 101 to the at least one CC which is associated with a highest rank among the CCs.

In an embodiment, the processor 107 is configured to select the CC of the plurality of CCs which is associated with the highest composite quality measure, and to assign the UE 101 to the selected CC.

In an embodiment, the processor 107 is configured to select the CC of the plurality of CCs which is associated with the highest composite quality measure and to assign the UE 101 to the CC of the plurality of CCs which is associated with the highest composite quality measure.

In an embodiment, the efficiency factor Rcc for the UE 101 and each CC of the plurality of CCs is one or a combination of the following values: a signal to noise and interference ratio (SINR) of the CC, a reference signal received power (RSRP) of the CC, a reference signal received quality (RSRQ) of the CC, a channel efficiency, in particular the transmission rate of data that can be transmitted between the communication apparatus 100 and the UE 101 via the CC.

Furthermore the efficiency factor of each CC of the plurality of CCs can be an uplink or a downlink channel efficiency for the UE 101 and each CC raised to the power of D, wherein D is a predefinable number, for instance, D = 1/a, wherein a is a fairness of a scheduler.

In an embodiment, the processor 107 is configured to determine the SINR and/or the RSRP and/or the RSRQ for the communication between the UE 101 and the communication apparatus 100 for each CC of the plurality of CCs, wherein the processor 107 can be configured to determine the SINR, the RSRP and the RSRQ as average values over several transmit time intervals (TTIs).

The CCs can comprise subcarriers that can be grouped into physical resource blocks. Each CC can consist of several resource blocks. A resource block is a time- and frequency resource that occupies a number of subcarriers, for instance 12 subcarriers, of the CC.

In an embodiment, the communication load L<x associated with the CC of the plurality of CCs is one or a combination of the following values: the number of UEs assigned to the CC, the ratio of the number of resource blocks that are currently used for transmission using the CC to the total number of resource blocks on the CC, the amount of data that is cun-ently transmitted using the CC, a remaining processing time that is required to transmit the amount of data, or a sum of functions based on the efficiency factors of communication between the UEs that are currently assigned to the CC and the communication apparatus.

In an embodiment, the communication load can be a sum of functions based on the efficiency factors, wherein the functions are power functions with degree E, wherein E is a predefinable number, for instance, E = (1 -α)/α, wherein a is the fairness of the scheduler:

Lcc - ∑cc(Rcc ^E> (3)

In an embodiment, the algorithm used to calculate the efficiency factor and/or the communication load depends on traffic requirements and/or performance goals of the communication network.

In an embodiment, the processor 107 is configured to select at least one further CC of the plurality of CCs for the UE 101 based on the composite quality measures of the CCs which are currently not assigned to the UE 101 , and wherein the processor 107 is further configured to assign the UE 101 to the further selected CC. This further assigned CC can be a secondary CC for the communication between the UE 101 and the communication apparatus 100.

In an embodiment, the processor 107 is configured to assign the UE 101 to the at least one further CC if a communication parameter of the UE 101 , in particular the amount of data that is exchanged between the UE 101 and the communication apparatus 100, reaches a threshold value, and to quit the assignment of the UE 101 to the further CC if the communication parameter is smaller than the threshold value. With the assignment of the further CC to the UE 101 a high data rate between the UE 101 and the communication apparatus 100 can be guaranteed. If the communication parameter is smaller than the threshold value, i.e. if the data rate between the UE 101 and the communication apparatus 100 drops, the assignment of the further CC to the UE 101 can be terminated. This can prevent a high communication load of the further CC. The at least one further CC can, for instance, be assigned to the UE 101 during a download or an upload of large datasets.

In an embodiment, communication interface 105 is configured to communicate with the UE 101 in an uplink or a downlink direction. The assignment of the UE 101 to the at least one CC of the plurality of CCs can be based on an uplink or a downlink efficiency factor, and an uplink or a downlink communication load of each CC. Different rules for determining the composite quality measure in uplink and downlink direction can be applied, for instance different powers A and B of the efficiency factors and communication loads in uplink and downlink direction.

In an embodiment, the communication apparatus 100 is configured to communicate with UEs of a set of UEs, wherein the communication apparatus 100 is configured to determine a priority measure for each UE 101 of the set of UEs, to select a further UE from the set of UEs which is associated with the highest priority measure, and to assign the further UE from the set of UEs to the at least one CC of the plurality of CCs.

The communication apparatus 100 can first assign the UEs of the set of UEs which have a high priority, for instance, UEs that can only communicate at high data rates when assigned to one particular CC of the plurality of CCs, and can subsequently assign the UEs of the set of UEs with lower priority, for instance UEs which can communicate with approximately the same data rate regardless of which CC of the plurality of CCs they are assigned to.

In an embodiment, the processor 107 is configured to determine the priority measure for each UE 1 01 of the set of UEs based on one or a combination of the following values: a maximum or average of the efficiency factors for the UE 101 and each CC, a maximum or average ratio of the efficiency factors for the UE 101 and each CC, to the communication load of each respective CC, or a ratio of the maximal efficiency factor to the minimal, average or submaximal efficiency factor for the UE 101 and each CC.

In an embodiment, the processor 107 is configured to determine the priority measure P_UE for each UE 101 of the set of UEs based on the maximum efficiency factor for the UE 101 and each CC, according to:

P_UE = max_cc{R_cc} (4)

In an embodiment, the processor 107 is configured to determine the priority measure P_UE for each UE 101 of the set of UEs based on the maximum ratio of the efficiency factor for the UE 101 and each CC, according to:

P_UE = max_cc{g} (5) In an embodiment, the processor 107 is configured to determine the priority measure P_UE for each UE 101 of the set of UEs based on the average ratio of the efficiency factor for the UE 101 and each CC, according to:

In an embodiment, the processor 107 is configured to determine the priority measure P_UE for each UE 101 of the set of UEs based on the ratio of the maximal efficiency factor to the minimal efficiency factor for the UE 101 and each CC, according to: U^E - min_cc{«_cc} ^/}

In an embodiment, the processor 107 is configured to determine the priority measure P_UE for each UE 101 of the set of UEs based on the ratio of the maximal efficiency factor to the average efficiency for the UE 101 and each CC, according to: ∑ccRcc

In an embodiment, the processor 107 is configured to determine the priority measure PUE for each UE 101 of the set of UEs based on the ratio of the average efficiency factor to the minimal efficiency factor for the UE 101 and each CC, according to:

p _ ∑cc Rcc _fQ,

^UE - _m m_ii_nn_cc R _pcc {^?)

In an embodiment, the processor 107 is configured to determine the priority measure PUE for each UE 101 of the set of UEs based on the ratio of the maximal efficiency factor to a submaximal efficiency factor for the UE 101 and each CC.

In an embodiment, the processor 107 is configured to select, after assigning the further UE with the highest priority measure from the set of UEs to the at least one CC, a further UE with the next highest priority measure from the set of UEs and to assign the selected further UE with the next highest priority measure to the at least one CC. In this way, the processor 107 can subsequently assign the UEs to the at least one CC in the order of their priority measures until all UEs are assigned to at least one CC of the plurality of CCs.

Figure 2a shows a schematic diagram of a method 200 for assigning a UE 101 to at least one CC of a plurality of CCs of a communication channel 103 according to an embodiment.

The method 200 comprises a first step 201 of determining an efficiency factor of a communication between the UE 101 and the communication apparatus for each CC of the plurality of CCs, a second step 203 of detennining a communication load associated with each CC of the plurality of CCs, a third step 205 of determining a composite quality measure for each CC from the determined efficiency factor and communication load, a fourth step 207 of selecting at least one CC of the plurality of CCs based on the composite quality measure, and a fifth step 209 of assigning the at least one selected CC to the UE 101.

Figure 2b shows a schematic diagram of the method 200, wherein UEs 101 from a set of UEs are assigned to at least one CC of the plurality of CCs.

The method 200 in figure 2b comprises a first step 21 1 of determining a priority measure for each UE 101 of the set of UEs, a second step 213 of selecting a further UE from the set of UEs which is associated with the highest priority measure, a third step 215 of assigning the selected further UE from the set of UEs to at least one CC of the plurality of CCs, wherein the third step 215 in figure 2b can comprise the steps 201 to 209 shown in figure 2a applied to the selected further UE, and a fourth step 217 of checking if there is a further unassigned UE, whereas if a further unassigned UE is identified then the second step 213 of selecting the further unassigned UE with maximal priority and the third step 215 of assigning the selected further unassigned UE are repeated. If no further unassigned UE is identified the method 200 is ended.

The method 200 can be performed by the communication apparatus 100.

In an embodiment, the method 200 for assigning the UE 101 to the at least one CC of the plurality of CCs of the communication channel 103 can be combined with any scheduler.

In the following, further implementation forms, embodiments and aspects of the communication apparatus 100 and the method 200 will be described.

Figure 3 shows a schematic diagram of the communication apparatus 100 according to an embodiment. The communication apparatus 100 can be a base station.

In the exemplary scenario shown in figure 3, the communication interface 105 comprises a receiver and a transmitter. The receiver and transmitter can be configured to gather information required for calculating the efficiency factor, the communication load, the composite quality measure, and the priority measure. The memory 109 can be configured to store the gathered information, as well as calculated values and information about the ranking, and performed associations.

In the exemplary scenario shown in figure 3, the communication interface 105 is connected to an antenna 301 for communicating with the UE 101.

Figure 4 shows a schematic diagram of a wireless communication network 400. The communication network 400 comprises wireless terminals 401a, 401b, 401c and cells 402, 403, wherein each cell 402, 403 comprises several CCs 405a, 405b, 405c, 407a, 407b.

In an embodiment, the wireless terminals 401a, 401b, 401c are UEs, such as the

UE 101 shown in figure 1 , and/or the cells 402, 403 are communication channels 103.

In the exemplary scenario shown in figure 4, association links between UEs 401a, 401b, 401c and CCs 405a, 405b, 405c, 407a, 407b correspond to intra-cell carrier aggregation, for instance wireless terminals 401a and 401b, or to inter-cell carrier aggregation, for instance wireless terminal 401c. The CCs 405a, 405b, 405c, 407a, 407b can be associated with the wireless terminals 401a, 401b, 401c as primary CC (PCC) or as secondary CC (SCC).

In the exemplary scenario shown in figure 4, CC 405a is a PCC for UE 401a and a SCC for UE 401b, CC 405b is a PCC for UE 401b, CC 405c is a SCC for UE 401c, and CC 407a is a PCC for UE 401c. Each cell 402, 403 is coupled with a radio resource that is to be allocated to the terminals within the cell.

Figure 5 shows the ranking of a set of UEs 101 for the assignment with two

CCs based on three different priority measures.

In the exemplary scenario shown in figure 5, the two CCs CCl and CC2 are considered. For association of the UEs 101 to the CCs the efficiency factors and the communication loads are taken into account. In figure 5, an exemplary scenario of 6 UEs served by one base station with two CCs is considered. The efficiency factors of the UEs 101 and the CCs as well as the UE priority measures PUE of each UE 101 are shown in table 501.

In the exemplary scenario shown in figure 5, the efficiency factors of CC2 are lower than that of CCl for all UEs 101. Three association algorithms for calculating the CC priority measures Pec are compared in figure 5; the resulting priority measures and association schemes are presented in the tables 503, 505, 507: the first table 503 shows an association according to the number of UEs Ncc on each CC, which indicates the communication load of each CC, the second table 505 shows an association according to the channel efficiency Rcc, and the third table 507 shows an association according to a hybrid method that considers a ratio of the channel efficiency to the number of UEs 101 , similar to method 200 as shown in figures 2a and 2b.

The first method 503 assigns UE2, UE4 and UE6 to CC2 which leads to poor channel efficiencies, the second method 505 assigns all UEs to CCl which leads to a large communication load of CCl . Both methods can lead to a low performance, e.g. low data rates. The third method that considers the channel efficiencies and the channel loads provides an optimal assignment. In the exemplary scenario shown in figure 5, the efficiency factor is denoted as Rcc, which is a nonnegative value that reflects the channel situation for the UE that is assigned to the CC. The efficiency factor turns to zero only if the UE cannot receive or transmit any resources through the CC. Furthermore, Rcc is order-invariant. This means that if the UE can receive or transmit more resources through CCi rather than through CC₂, then Rcci > cc₂- Also if UE1 can receive or transmit more resources through a certain CC rather than UE2 can receive or transmit trough the same CC then the efficiency factor corresponding to UE1 is larger than the one corresponding to UE2.

Analogously, the communication load Lcc is a nonnegative value that reflects the load situation on the considered CC. For example, Lcc becomes larger with an increasing number of UEs assigned to the CC.

A communication network has several goals, such as network throughput and network fairness. A policy that keeps balance between these two goals is the proportional fairness and more generally the so-called "alpha-fairness". Proportional fair (PF) schedulers provide results which combine a large total throughput with a tolerable cell edge throughput. For a full buffer traffic model the PF scheduler allocates resources in such a manner that the UE throughputs are proportional to the efficiency factors. Fairness implies that even UEs with small channel efficiencies can communicate with a sufficient data rate. The PF scheduler maximizes a sum-log- throughput utility function, according to: UPF(XI , X₂, · · ·) ⁼∑n log(X_n), wherein the alpha-fair scheduler maximizes U_a(Xi, X₂, ...) =∑_n (X_n)^{l a}. Here the sum is taken over all N UEs, with n = 1 ...N, X_n is the throughput of n-th UE, and a is the fairness of the •scheduler.

In the following a theoretical justification for the presented method 200 is provided in the context of a proportional fair (PF) or an alpha-fair resource management policy.

Assuming that each UE 101 can be associated with only one CC and that the average efficiency factors are constant over time, a throughput over time T can be calculated according to X„ = T∑_m a„_im s_n,m r_n>m , where the sum is taken over M CCs, with m = 1 ...M, a, _ll is an association decisions which equals 1 if UE n is associated with CC m and 0 otherwise, s_{n m} is the fraction of time when UE n is served on CC m, and r_{n m} is the efficiency factor of UE n assigned to CC m.

For the PF scheduler the time fractions s_{n m} equal the inverse of the number of UEs associated to a CC: s_n,m =∑_n a_n,m = N_m, wherein the sum is taken over all N UE, and wherein N_m is the number of UEs 101 associated to CC m. If a new UE k joins the network and is associated to CC m, the utility function is increased by: AU_PF ~ log (T r_k>m / N_m). Associating UE k with the CC m = m(k) with the maximal composite quality measure P_m = i\_m / N_m maximizes the PF utility function, wherein m(k) = argmax{Pi, P₂,..., P_M}. Such an association of UEs to CCs based on the composite quality measure is described by the method 200 for assigning the UE 101 to at least one CC of a plurality of CCs of a communication channel 103 which is shown in figure 2a.

Analogous considerations for "alpha-fair" management policy give the following CC priorities for UE n: P_m = (r_n,ni)^1/a / L_m , wherein the load measure is L_m =∑„ (ΐ wherein the sum∑_n is taken over the UEs 101 associated to CC m.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations or embodiments, such feature or aspect may be combined with one or more other features or aspects of the other implementations or embodiments as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

Claims

1. A communication apparatus (100) for assigning a user equipment (UE) (101) to at least one component earner (CC) of a plurality of CCs of a communication channel (103), comprising:

a communication interface (105) being configured to communicate with the UE using the at least one CC of the plurality of CCs;

a processor (107) being configured to determine an efficiency factor of a communication between the UE (101) and the communication apparatus for each CC of the plurality of CCs, wherein the processor is further configured to determine a communication load associated with each CC of the plurality of CCs, and wherein the processor is further configured to determine a composite quality measure for each CC from the determined efficiency factor and communication load;

wherein the processor (107) is configured to select at least one CC of the plurality of CCs based on the composite quality measure, and to assign the UE (101) to the at least one selected CC.

2. The communication apparatus of claim 1, wherein the processor (107) is configured to determine the composite quality measure of each CC of the plurality of CCs as a ratio of the respective efficiency factor for the UE (101) and each CC, to the respective communication load of each CC.

3. The communication apparatus (100) of claim 1 or 2, wherein the processor (107) is configured to determine a ranking of the CCs upon the basis of the composite quality measures, and wherein the processor (107) is configured to assign the UE (101) to the at least one CC, which is associated with a highest rank.

4. The communication apparatus (100) of any one of the preceding claims, wherein the efficiency factor for each CC of the plurality of CCs is one or a combination of the following values: a signal to noise and interference ratio (SINR) of the CC, a reference signal received power (RSRP) of the CC, a reference signal received quality (RSRQ) of the CC, a channel efficiency, in particular the transmission rate of data that can be transmitted between the communication apparatus and the UE (101) via the CC.

5. The communication apparatus (100) of claim 4, wherein the processor is configured to determine the SINR, the RSRP or the RSRQ for the communication between the UE (101) and the communication apparatus for each CC of the plurality of CCs, wherein the processor can be configured to determine the SIN , the RSRP and the RSRQ as average values over several transmit time intervals (TTIs).

6. The communication apparatus (100) of any one of the preceding claims, wherein the communication load associated with each CC of the plurality of CCs is one or a combination of the following values: the number of UEs assigned to the CC, the ratio of the number of resource blocks that are currently used for transmission using the CC to the total number of resource blocks on the CC, the amount of data that is currently transmitted using the CC, a remaining processing time that is required to transmit the amount of data, or a sum of functions based on the efficiency factors of communication between the UEs (101) that are currently assigned to the CC and the communication apparatus.

7. The communication apparatus (100) of any one of the preceding claims, wherein the processor is configured to select at least one further CC of the plurality of CCs for the UE (101) based on the composite quality measures of the CCs which are currently not assigned to the UE (101), and wherein the processor is further configured to assign the UE (101) to the further selected CC.

8. The communication apparatus (100) of claim 7, wherein the processor is configured to assign the UE (101) to the at least one further CC if a communication parameter of the UE (101), in particular the amount of data that is exchanged between the UE (101) and the communication apparatus, reaches a threshold value, and to quit the assignment of the UE (101) to the further CC if the communication parameter is smaller than the threshold value.

9. The communication apparatus (100) of any one of the preceding claims, wherein the communication apparatus (100) comprises a memory (109), wherein the processor (107) is configured to store the efficiency factor, the communication load and the composite quality measure in the memory (109).

10. The communication apparatus (100) of any one of the preceding claims, wherein the communication interface (105) is configured to communicate with the UE (101) in an uplink or a downlink direction.

1 1. The communication apparatus (100) of any one of the preceding claims, wherein the communication apparatus (100) is configured to communicate with UEs (101) of a set of UEs, wherein the communication apparatus is configured to determine a priority measure for each UE (101) of the set of UEs, to select a further UE from the set of UEs which is associated with the highest priority measure, and to assign the further UE from the set of UEs to the at least one CC of the plurality of CCs.

12. The communication apparatus (100) of claim 1 1, wherein the processor

(107) is configured to determine the priority measure for each UE (101) of the set of UEs based on one or a combination of the following values: a maximum or average of the efficiency factors for the UE (101) and each CC, a maximum or average ratio of the efficiency factors for the UE (101) and each CC, to the communication load of each respective CC, or a ratio of the maximal efficiency factor to the minimal, average or submaximal efficiency factor for the UE (101) and each CC.

13. The communication apparatus (100) of claim 1 1 or 12, wherein the processor (107) is configured to select, after assigning the further UE with the highest priority measure from the set of UEs to the at least one CC, a further UE with the next highest priority measure from the set of UEs, and to assign the selected further UE with the next highest priority measure to the at least one CC.

14. A method (200) for assigning a UE (101) to at least one CC of a plurality of CCs of a communication channel (103), comprising:

determining (201) an efficiency factor of a communication between the UE (101) and the communication apparatus for each CC of the plurality of CCs;

determining (203) a communication load associated with each CC of the plurality of CCs,

determining (205) a composite quality measure for each CC from the determined efficiency factor and communication load;

selecting (207) at least one CC of the plurality of CCs based on the composite quality measure; and

assigning (209) the at least one selected CC to the UE (101 ).

15. The method (200) of claim 14, wherein UEs (101) from a set of UEs are assigned to at least one CC of the plurality of CCs, the method (200) further comprising:

determining (211) a priority measure for each UE (101) of the set of UEs; selecting (213) a further UE from the set of UEs which is associated with the highest priority measure; and

assigning (215) the selected further UE from the set of UEs to at least one CC of the plurality of CCs.

16. A computer program comprising program code for performing the method (200) of claim 14 or claim 15 when executed on a processor.