WO2015044769A2

WO2015044769A2 - Method and apparatus for scheduling user equipment

Info

Publication number: WO2015044769A2
Application number: PCT/IB2014/002105
Authority: WO
Inventors: Yun DENG
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2013-09-27
Filing date: 2014-09-17
Publication date: 2015-04-02
Anticipated expiration: 2016-03-27
Also published as: CN104519585B; WO2015044769A3; CN104519585A

Abstract

The present invention discloses methods and apparatuses for scheduling user equipment in a wireless communication system supporting dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, and the two base stations include a macro base station and a small base station, the method comprising: sending a dual connectivity setup request message from the macro base station to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment and enabling the macro base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment. With the methods and apparatuses of the present invention, the resources may be reasonably allocated to the user equipment and the processing capability for the use equipment under the dual connectivity could be ensured.

Description

METHOD AND APPARATUS FOR SCHEDULING USER EQUIPMENT

Field of the Invention

Embodiments of the present invention generally relate to wireless communication systems, and more specifically to a method and apparatus for scheduling user equipment in a wireless communication system supporting dual connectivity.

Background of the Invention

Since a low-power node can bring about capacity enhancement and a gain in respect of blind spot coverage, more and more studies direct the focus to deployment and enhancement of small cells covered by low-power node. Here, the low-power node may be a small base station, and its examples include but not limited to low-power base stations such as Pico and Femto. In 3GPP R12, a new research project "Small Cell Enhancements for E-UTRA and E-UTRAN Higher-layer Aspects" has already been approved, and one focus thereof is to support dual connectivity of a macro cell (a cell covered by a macro base station) layer and a small cell layer.

In a wireless communication, a different radio bearer needs to be established to provide service to data with different quality of service ("QoS"), and user plane (abbreviated as UP) data will be transmitted on a Data Radio Bearer (abbreviated as "DRB") and Control Plane (abbreviated as "CP") data will be transmitted on a Signaling Radio Bearer (abbreviated as "SRB"). Regarding the case of dual connectivity, user equipment (hereinafter referred to as "UE") will be simultaneously connected to two base stations, wherein one base station may be for example a macro base station and the other base station for example may be a small base station. The term "base station" here may be alternatively called node B and evolved node B ("eNB") along with the evolvement of wireless communication. To this end, it is necessary to consider how to configure and schedule UE in the case of dual connectivity. According to the current specification, E-UTRAN needs to respect the signaled UE radio access capability parameters when configuring the UE and when scheduling the UE. UE radio access capability parameters refer to UE-category and parameters independent of the field UE-category (including UE supported Packet Data Convergence Protocol ("PDCP") parameters, UE supported Radio Link Control ("RLC") parameters, UE supported physical layer parameters, UE supported RF parameters etc.).

When UE accesses the network for the first time, the network should acquire UE radio access capability. For example, the network should know UE-category, then it can allocate the suitable radio resources for this UE. Now there are 8 types of UE-category, the following table illustrates Downlink physical layer parameter values set by the field ue-Category. Table 1. Downlink physical layer parameter values set by the field ue-Category

UE Category Maximum number Maximum Total number Maximum

of number of bits of soft number of

Downlink-Shared of a DL-SCH channel bits supported

Channel transport block layers for

("DL-SCH") received spatial transport block bits within a TTI multiplexing in received within a DL transmission time

interval ("TTI")

(Note)

Category 1 10296 10296 250368 1

Category 2 51024 51024 1237248 2

Category 3 102048 75376 1237248 2

Category 4 150752 75376 1827072 2

Category 5 299552 149776 3667200 4

Category 6 301504 149776 (4 3654144 2 or 4

layers)

75376 (2

layers)

Category 7 301504 149776 (4 3654144 2 or 4

layers)

75376 (2

layers)

Category 8 2998560 299856 35982720 8

If one UE is Category 5, its Maximum number of DL-SCH transport block bits received within a TTI is 299552. The network cannot transmit more than 299552 bits within a TTI to this UE on account of the processing capability of the UE.

Before 3GPP Release 12, there is one Medium Access Control (abbreviated as "MAC") to perform centralized schedule for UE. Due to the centralized schedule, this MAC can assure that radio resources allocated for the UE is less than UE radio access capability.

Now dual connectivity is introduced in small cell enhancement for spectral efficiency and mobility improvement. To facilitate understanding, Fig.l illustrates the UE connected to both the macro base station providing macro cell coverage and the small base station providing small cell coverage, i.e., the UE is in a dual connectivity mode. There is no ideal backhaul link between the macro base station and the small base station. The significant delay (2ms to 60ms one way) of the backhaul link will cause that centralized schedule performed by the MAC cannot be applicable in the dual connectivity scenario. Therefore, it is a feasible scheme to adopt distributed schedule for the UP in the dual connectivity, and now RAN2 is discussing the feasible protocol architecture for dual connectivity. Fig. 2 illustrates one type of potential user plane architecture. As can be seen from Fig.2, SI interface coming from a core network terminates at the macro base station MeNB, whereas the small base station SeNB, based on Xn interface (or enhanced X2 interface), receives data of one or more DRBs from the MeNB and transmits to the UE via the corresponding RLC, MAC and physical layer (not shown). In the protocol architecture, independent MAC is used to perform distributed schedule. Usually, macro base station or small base station only can assure that resource allocation for its side obeys the restriction due to UE processing capability, macro base station or small base station cannot assure that the total resource allocation for two sides can obey the restriction due to UE processing capability. Under this situation, how to assure UE processing capability is a problem to be solved.

Summary of the Invention

In order to solve at least some of the above-mentioned technical problems, embodiments of the present invention provide a method and apparatus for scheduling user equipment in a wireless communication system supporting dual connectivity so as to ensure the UE's processing capability in the case of dual connectivity, avoid transmission overload for the UE and implement reasonable and efficient schedule of the UE. According to an aspect of the present invention, there is provided a method for scheduling user equipment in a wireless communication system supporting dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, the two base stations include a macro base station and a small base station. The method comprises sending a dual connectivity setup request message from the macro base station to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment. The method further comprises enabling the macro base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

In an embodiment, the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity. In another embodiment, the information related to the user equipment capability comprises at least one of the following items:

a maximum number of Uplink-Shared Channel transport block bits transmitted within a transmission time interval;

a maximum number of Downlink-Shared Channel transport block bits received within a transmission time interval;

a value set according to total number of soft channel bits transmitted by the downlink; a maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE cannot simultaneously transmit uplink data to the macro base station and the small base station;

a maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when UE cannot simultaneously receive downlink data from the macro base station and the small base station;

a value set according to the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE can simultaneously transmit uplink data to the macro base station and the small base station;

a value set according to the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when the UE can simultaneously receive the downlink data from the macro base station and the small base station;

a number of data radio bearers established for the UE, or the number of data radio bearers which are established for the UE and not offloaded to the small base station, or a sum of downlink bit rates of the data radio bearers established for the UE, or a sum of downlink bit rates of the data radio bearers which are established for the UE and not offloaded to the small base station, when the UE can simultaneously receive the downlink data from the macro base station and the small base station;

a number of data radio bearers established for the UE, or the number of data radio bearers which are established for the UE and not offloaded to the small base station, or a sum of uplink bit rates of the data radio bearers established for the UE, or a sum of uplink bit rates of the data radio bearers which are established for the UE and not offloaded to the small base station, when the UE can simultaneously transmit uplink data to the macro base station and the small base station; and

the UE' s category information.

In a further embodiment, the method further comprises receiving from the UE an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a radio resource control signaling or media access control layer control information element, and reducing amount of data transmitted to the UE based on the indication.

In an embodiment, the method further comprises transmitting a radio resource control connection reconfiguration message to the UE so that the UE is accessed to the small base station.

According to another aspect of the present invention, there is provided a method for scheduling user equipment in a wireless communication system supporting dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, the two base stations include a macro base station and a small base station. The method comprises receiving a dual connectivity setup request message from the macro base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the macro base station to perform resource schedule for the user equipment in the connectivity with the user equipment. The method further comprises enabling the small base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

a value set according to total number of soft channel bits transmitted by the downlink; the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE cannot simultaneously transmit uplink data to the macro base station and the small base station;

the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when UE cannot simultaneously receive downlink data from the macro base station and the small base station;

the UE's category information. In a further embodiment, the method further comprises receiving from the UE an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a media access control layer control information element, and reducing amount of data transmitted to the UE based on the indication.

In another embodiment, the small base station using the information to perform resource schedule for the UE in the connectivity with the UE comprises the small base station allocating transmission resource for the UE based on the information.

According to a further aspect of the present invention, there is provided an apparatus for scheduling user equipment in a wireless communication system supporting the dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, the two base stations include a macro base station and a small base station, the apparatus comprises a transmitting unit configured to transmit a dual connectivity setup request from the macro base station to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment. The apparatus further comprises a scheduling unit configured to enable the macro base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

According to a further aspect of the present invention, there is provided an apparatus for scheduling user equipment in a wireless communication system supporting the dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, the two base stations include a macro base station and a small base station, the apparatus comprises a receiving unit configured to receive a dual connectivity setup request from the macro base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the macro base station to perform resource schedule for the user equipment in the connectivity with the user equipment. The apparatus further comprises a scheduling unit configured to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

Although not detailed here, the above apparatus of the present invention may comprise various units for implementing the previous aspects and performing steps of the methods of the embodiments.

By using the method and apparatus according to the above aspects and embodiments of the present invention, it is feasible to efficiently schedule resource for the UE in the system supporting the dual connectivity, reasonably allocate resources to the UE, ensure the UE's processing capability in the case of dual connectivity, and thereby further improve normal transmission under dual connectivity and avoid transmission fault caused by the UE processing capability. Brief Description of Drawings

Other features, objects and advantages of the present invention will be made more apparent by reading the following detailed description of exemplary embodiments with reference to figures, wherein:

Fig.1 illustrates a wireless communication system supporting the dual connectivity to which an embodiment of the present invention may be applied;

Fig.2 illustrates a diagram of a possible protocol stack arrangement in the case of dual connectivity;

Fig.3 illustrates a flow chart of a method for scheduling user equipment in a wireless communication system supporting the dual connectivity according to an embodiment of the present invention;

Fig.4 illustrates a flow chart of a method for scheduling user equipment in a wireless communication system supporting the dual connectivity according to another embodiment of the present invention;

Fig.5 illustrates a signaling diagram of scheduling the user equipment in a wireless communication system supporting the dual connectivity according to an embodiment of the present invention;

Fig.6 illustrates a block diagram of an apparatus for scheduling user equipment in a wireless communication system supporting the dual connectivity according to an embodiment of the present invention; and Fig.7 illustrates a block diagram of an apparatus for scheduling user equipment in a wireless communication system supporting the dual connectivity according to another embodiment of the present invention. Detailed Description of Preferred Embodiments

Embodiments of the present invention provide several feasible solutions to assure the user equipment processing capability in the dual connectivity. Specifically, when MeNB (Macro eNB, also called macro base station) determines to configure small cell for the UE to establish dual connectivity, MeNB should inform SeNB (Small eNB, also called small base station) of information related to the user equipment capability. When the small base station obtains the information related to the user equipment capability, it can reasonably allocate resources to the user equipment after considering the user equipment capability to avoid excessive transmission from the macro base station and small base station for the user equipment and resultant transmission fault in the case of dual connectivity.

Fig.3 illustrates a flow chart of a method 300 for scheduling user equipment in a wireless communication system supporting the dual connectivity according to an embodiment of the present invention, wherein the user equipment remains connected to two base stations in the dual connectivity, the two base stations include a macro base station (e.g., macro base station shown in Fig.1 and MeNB shown in Fig.2) and a small base station (e.g., small base station shown in Fig.l and SeNB shown in Fig.2).

At step S301 of the method 300, a dual connectivity setup request message is sent from macro base station sends to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment. Then at step S302 of the method 300 the macro base station is enabled to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment. Noticeably, although the embodiment of the present invention uses the term "dual connectivity setup request message", use of this term is not intended for limiting purpose, it is only a name of the sent message, a main purpose of the message is to set up the dual connectivity so that the macro base station sends necessary parameters to the small base station by virtue of the message, for example, various parameters such as DRB parameter to be offloaded to the small base station will be discussed below.

Although not shown, in an embodiment, the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity. The information related to category here may for example comprise the category information shown in Table 1 and maximum information related to the category.

In another embodiment, the information related to the user equipment capability comprises at least one of the following items: maximum number of Uplink-Shared Channel transport block bits transmitted within a transmission time interval and maximum number of Downlink-Shared Channel transport block bits received within a transmission time interval. Regarding the dual connectivity, the macro base station and the small base station both perform independent schedule for the user equipment. When the user equipment is scheduled in an TTI (Transmission Time Interval), the macro base station or the small base station should obey this restriction. Hence, this parameter should be directly notified to the small base station;

a value set according to total number of soft channel bits transmitted by the downlink, wherein the total number defines the total number of soft channel bits that can be used for HARQ processing, the value may be a proportion value (e.g., between 0% and 100%) so that the macro base station and the small base station both may use a portion of all software channel bits;

the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE cannot simultaneously transmit uplink data to the macro base station and the small base station,;

the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when UE cannot simultaneously receive downlink data from the macro base station and the small base station; a value set according to the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE can simultaneously transmit uplink data to the macro base station and the small base station, wherein the value may be a proportion value (e.g., between 0% and 100%) so that a reasonable number of uplink data may be transmitted to the macro base station and the small base station respectively according to the proportion value; a value set according to the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when the UE can simultaneously receive the downlink data from the macro base station and the small base station, wherein the value may be a proportion value (e.g., between 0% and 100%) so that the macro base station and small base station may reasonably transmit data to the UE according to the proportion value. For example, the macro base station sets a value for the small base station, the value may be 50% of the maximum value so that the small base station may transmit downlink data smaller than or equal to half of the maximum value within the TTI, and the macro base station may transmit uplink data smaller than or equal to a surplus value with the TTI, wherein the surplus value=maximum value-the value for use in the small base station;

the number of data radio bearers established for the UE, or the number of data radio bearers which are established for the UE and not offloaded to the small base station, or a sum of downlink bit rates of the data radio bearers established for the UE, or a sum of downlink bit rates of the data radio bearers which are established for the UE and not offloaded to the small base station, when the UE can simultaneously receive the downlink data from the macro base station and the small base station; the number of data radio bearers established for the UE, or the number of data radio bearers which are established for the UE and not offloaded to the small base station, or a sum of uplink bit rates of the data radio bearers established for the UE, or a sum of uplink bit rates of the data radio bearers which are established for the UE and not offloaded to the small base station, when the UE can simultaneously transmit uplink data to the macro base station and the small base station; and the UE's category information.

In a further embodiment, the method 300 further comprises receiving from the UE an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a radio resource control signaling or media access control layer control information element, and reducing amount of data transmitted to the UE based on the indication. As can be seen from the depictions with reference to Fig.3, by transmitting the information related to UE capability to the small base station, embodiments of the present invention may reasonably allocate resource schedule for the UE between the macro base station and the small base station, so that under the situation of dual connectivity, the UE's processing capability may be ensured to achieve good distributed schedule.

Fig.4 illustrates a flow chart of a method 400 for scheduling user equipment in a wireless communication system supporting the dual connectivity according to another embodiment of the present invention, wherein the user equipment remains connected to two base stations in the dual connectivity, the two base stations include a macro base station (e.g., macro base station shown in Fig.1 and MeNB shown in Fig.2) and a small base station (e.g., small base station shown in Fig.l and SeNB shown in Fig.2).

At step S401 of the method 400, a dual connectivity setup request message from the macro base station is received, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment. Then at step S402, the method 400 further comprises enabling the small base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

Although not shown, as in the above depictions with reference to Fig.3, in an embodiment, the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity. In another embodiment, the information related to the user equipment capability comprises at least one of the following items: a maximum number of Uplink-Shared Channel transport block bits transmitted within a transmission time interval;

a value set according to total number of soft channel bits transmitted by the downlink, wherein the value may be a proportion value so that the macro base station and the small base station both may use a portion of all software channel bits;

the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE cannot simultaneously transmit uplink data to the macro base station and the small base station;

a value set according to the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the UE can simultaneously transmit uplink data to the macro base station and the small base station, wherein the value is for example a proportion value so that a reasonable number of uplink data may be transmitted to the macro base station and the small base station respectively according to the bit value;

a value set according to the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when the UE can simultaneously receive the downlink data from the macro base station and the small base station, wherein the value is for example a proportion value so that both the macro base station and small base station may reasonably transmit data to the UE according to the proportion value;

In a further embodiment, the method 400 further comprises receiving from the UE an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a media access control layer control information element, and reducing amount of data transmitted to the UE based on the indication.

As can be seen from the above depictions with reference to Fig.4, corresponding to the method 300 in Fig.3, after receiving the information related to the UE's capability, the small base station may reasonably allocate resource and implement schedule for the UE so as to ensure that the UE efficiently transmits data in the case of dual connectivity.

Since parameters in the information related to the UE capability and the setting thereof is a crucial factor for implementing reasonable schedule of the UE in the case of dual connectivity according to the embodiment of the present invention, further emphasis and detailed depictions are presented below with reference to an example to better understand the embodiment of the present invention.

According to the embodiment of the present invention, the macro base station may for example comprise the following exemplary various information or information combinations in the dual connectivity setup request: Complete UE capability information, including the UE's category and capability information about whether the UE supports simultaneous reception or simultaneous transmission. The UE's category may be represented by the maximum bit number of a single data packet (received from the downlink shared channel, the same hereunder) received within a TTI and a maximum bit number received within a TTI and a maximum bit number of a single data packet (transmitted at the uplink shared channel, the same hereunder) transmitted within a TTI and a maximum bit number transmitted within a TTI and total number of downlink soft channel bits. If the UE does not support simultaneous reception or simultaneous transmission, the small base station schedules resources for the UE according to the maximum value. If the UE supports simultaneous reception or simultaneous transmission, the small base station schedules resources for the UE according to the maximum value, or obtains useable UE capability information by the following method so as to schedule resources for the UE according to the useable UE capability information;

Complete UE capability information and useable UE capability information allocated to the small base station, for example, the maximum bit number received within a TTI and the maximum bit number transmitted in a TTI and total number of downlink soft channel bits. The values of these parameters are all smaller than the maximum value corresponding to the UE's category. After receiving these information, the small base station uses the useable UE capability information allocated to the small base station to allocate transmission (uplink or downlink) resources for the UE. For example, upon allocating the resources downlink, the small base station determines a maximum number of physical resource blocks that may be allocated to the UE according to the maximum bit number transmitted within a TTI, and the small base station may select part or all of the maximum number of physical resource blocks that may be allocated to the UE to transmit data to the UE;

Useable UE capability information allocated to the small base station, for example the maximum bit number of a single data packet received within a TTI and a maximum bit number received within a TTI and a maximum bit number of a single data packet transmitted within a TTI and a maximum bit number transmitted within a TTI and total number of downlink soft channel bits. After receiving these information, the small base station uses the useable UE capability information allocated to the small base station to allocate transmission (uplink or downlink) resources for the UE. For example, the useable UE capability information may be represented by a proportion value in a range of 0 to 1, for example, 0.6. After receiving the proportion value, the small base station obtains useable UE capability information by the following method. For example, the maximum bit number received within a TTI=the maximum bit number received within a TTI and corresponding to the UE's category x0.6. Other parameters such as the maximum bit number transmitted within a TTI or total number of downlink soft channel bits all requires the maximum value corresponding to the UE's category to multiply the proportion value so as to obtain the UE capability information that may be used by the small base station. The proportion value may be set uniformly or set respectively. For example, a proportion value is set for the maximum bit number received within a TTI, and another proportion value is set for the maximum bit number transmitted within a TTI;

Complete UE capability information, the number of all data radio bearers ("DRBs") established by the UE, or quality of service parameter (including uplink and downlink bit rates) of all DRBs established by UE, the number of DRBs established by the UE and served by the macro cell (in the DRBs established by the UE, some are offloaded to the small cell and served by the small cell; the remaining DRBs are not offloaded to the small cell and served by the macro cell), or quality of service parameter established by UE and served by the macro cell. After receiving these information, the small base station obtains useable UE capability information. For example, the maximum bit number received within a TTI=the maximum bit number received within a TTI and corresponding to the UE's category X (the number of DRBs established by the UE and served by the small cell/the number of all DRBs established by the UE); or the maximum bit number received within a TTI= the maximum bit number received within a TTI and corresponding to the UE's category x (a sum of downlink bit rates of DRBs established by the UE and served by the small cell/a sum of downlink bit rates of all DRBs established by the UE); or the maximum bit number transmitted within a TTI = the maximum bit number transmitted within a TTI and corresponding to the UE's categoryX(a sum of uplink bit rates of DRBs established by the UE and served by the small cell/a sum of uplink bit rates of all DRBs established by the UE). The bit rate may be the maximum bit rate or guaranteed bit rate. Being carried in the dual connectivity setup request, the small base station knows the number of DRBs established by the UE, offloaded to the small cell and served by the small cell and corresponding quality of service parameter. Some DRBs do not ensure the requirement of the bit rate or maximum bit rat. The small base station may not consider these DRBs upon making statistics of the sum of the uplink and downlink bit rates, or use a fixed value such as lOOOOObit/s to represent.

Regarding allocating resources after receiving the information, if the macro base station and the small base station both allocate resources for the UE according to the UE's capability, the sum of the allocated resources might exceed the maximum processing capability of the UE, for example, in a certain TTI, the downlink data packet to be received by the UE from the macro cell and small cell exceeds the maximum value, and the UE discards the corresponding data packet. In this case, the UE may send an indication to the macro base station or small base station to indicate that the number of allocated resources exceeds the UE's processing capability. After receiving the indication, the macro base station or small base station will correspondingly reduce the data transmission amount for the UE. If the UE sends the indication to the macro base station, the radio resource control RRC signaling, or media access control layer control information element MAC CE may be used to send the instruction to the macro base station. If the UE sends the indication to the small base station, the media access control layer control information element MAC CE may be used to send the indication to the small base station. As far as this aspect is concerned, it is necessary to enhance RRC signaling or MAC CE and set a dedicated information element to represent this indication.

Fig.5 illustrates a signaling diagram of scheduling the user equipment in a wireless communication system supporting the dual connectivity according to an embodiment of the present invention. As shown in Fig.5, at step S501, the UE is initially only accessed to the macro cell covered by the macro base station, so that the UE has a RRC connection with the macro cell. The macro base station may know the information related to the UE's capability from a mobility management entity ("MME") or the UE. It is assumed that UE belongs to category 5, its Maximum number of DL-SCH transport block bits received within a TTI is 299552; its Maximum number of bits of a DL-SCH transport block received within a TTI is 149776 and its Total number of soft channel bits is 3667200. Uplink processing capability is not listed because it can be dealt with similarly as downlink. At step S502, Macro cell becomes a primary cell ("PCell") for the UE. Macro cell determines whether to configure small cell for dual connectivity for the UE based on UE capability and radio condition. This step may involve collecting measurement report sent by the UE, and selecting a suitable small base station from candidate small base stations for dual connectivity for the UE.

Then, at step S503, Macro base station sends the dual connectivity setup request to the small base station. The request may include information related to the UE capability, for example, various information described previously with reference to Fig.3 and Fig.4. Alternatively, the dual connectivity setup request here may include the DRB information offloaded to the small cell.

Besides, in order to assure UE processing capability in dual connectivity, the request may for example include:

a maximum number of bits of a DL-SCH transport block received within a TTI for this UE.

If UE can simultaneously receive downlink data from the macro base station and the small base station, there are three solutions to deal with maximum number of DL-SCH transport block bits received within a TTI. Solution 1: the macro base station sets one value for the small base station. Small base station only can send downlink data within a TTI less than this value; while the macro base station can send downlink data within a TTI less than remaining value (remaining value=maximum - the value for small base station) also. For example, the macro base station sets one value =200000 (less than 299552) for the small base station. Small base station schedules UE within a TTI less than 200000 bits. And the macro base station can schedule UE within a TTI less than 99552 bits (i.e.

299552-200000). Solution 2: For the dual connectivity, some DRBs are offloaded to the small base station; other DRBs are still served by the macro base station. The macro base station can inform small base station that how many DRBs are established for this UE in the dual connectivity setup request. Then the small base station obtains one value equal to Maximum value*(number of offloaded DRBs/number of established DRBs), and uses this value to schedule this UE. For example, UE has established 3 DRBs, 2DRBs are offloaded to the small cell. So the mall base station obtains the value = 299552*(2/3)= 199701, and schedules this UE within a TTI less than 199701 bits. Solution 3: the macro base station and the small base station perform individual schedule for UE according to the maximum value. Once the UE detects that transport block bits exceed this maximum value, it sends one indicator to the macro base station or the small base station so that the macro base station or the small base station can reduce its transmitting bit rate. If UE cannot simultaneously receive downlink data from the macro base station and the small base station, maximum number of DL-SCH transport block bits received within a TTI for this UE should be included in the dual connectivity setup request. For total number of soft channel bits for downlink, the macro base station and the small base station only can utilize part of the total number of soft channel bits. The above solutions for maximum number of DL-SCH transport block bits when UE can simultaneously receive downlink data from the macro base station and the small base station can be applicable for this.

At step S504, after the small base station receives the request, small base station allocates necessary resource for the offloaded DRBs. The small cell should store UE's capability particularly UE processing capability information. Then the small cell sends a response to the macro cell. At step S505, the macro base station sends RRC connection reconfiguration to UE, which is used to inform the UE of resource configuration used by it in the small cell. At step S506, the UE accesses the small cell according to the reconfiguration message.

In one implementation, the macro base station may use an activation command to activate the small cell. After UE accesses the small cell simultaneously, UE establishes the dual connectivity. After dual connectivity is established, the macro base station and the small base station will perform distributed schedule for this UE. Because the above mechanism is introduced, UE processing capability according to the present invention can be assured. Fig.6 illustrates a block diagram of an apparatus 600 for scheduling user equipment in a wireless communication system supporting the dual connectivity according to an embodiment of the present invention. As shown in Fig.6, the apparatus 600 is used to schedule the UE in the wireless communication system supporting the dual connectivity, wherein the wireless communication system comprises UE and two base stations connected with the UE, and the two base stations comprise a macro base station and a small base station. The apparatus 600 comprises a transmitting unit configured to transmit a dual connectivity setup request from the macro base station to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment. The apparatus 600 further comprises a scheduling unit 602 configured to enable the macro base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment. It can be seen that the apparatus 600 of Fig.6 can implement the method 300 shown in Fig.3, and although not further shown, the apparatus 600 may comprise more functional units to implement a plurality of embodiments described with reference to the method 300. Furthermore, the apparatus 600 may be implemented at the macro base station or in the macro base station.

Fig.7 illustrates a block diagram of an apparatus 700 for scheduling user equipment in a wireless communication system supporting the dual connectivity according to another embodiment of the present invention. The apparatus 700 is used to schedule the UE in the wireless communication system supporting the dual connectivity, wherein the wireless communication system comprises UE and two base stations both connected with the UE, and the two base stations comprise a macro base station and a small base station. The apparatus 700 comprises a receiving unit 701 configured to receive a dual connectivity setup request from the macro base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the macro base station to perform resource schedule for the user equipment in the connectivity with the user equipment. The apparatus 700 further comprises a scheduling unit 702 configured to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment. It can be seen that the apparatus 700 of Fig.7 can implement the method 400 shown in Fig.4, and although not further shown, the apparatus 700 may comprise more functional units to implement a plurality of embodiments described with reference to the method 400. Furthermore, the apparatus 700 may be implemented at the small base station or in the small base station.

To sum up, each preferred embodiment of the present invention has been described in detail with reference to the accompanying drawings. Those skilled in the art would appreciate that embodiments of the present invention may be implemented through hardware, software, firmware, module or a combination thereof, or the present invention may be embodied on a computer program product set on a signal bearer medium available to any suitable data processing system. Such signal bearing medium may be a transmission medium or a recordable medium for computer-readable information, including a magnetic medium, an optical medium, or other suitable medium. Examples of recordable mediums include: a magnetic disk or floppy disk in a hard disk driver, an optical disk for a CD driver, a magnetic tape, and other medium that can be contemplated by the skilled in the art. The skilled in the art should understand that any communication terminal with an appropriate programming apparatus can implement steps of the method of the present invention as embodied in the program product. It should be noted that in order to make the present invention more comprehensible, the above description omits some more specific technical details which are known to the skilled in the art and may be essential to implement the present invention.

Although preferred embodiments of the present invention have been disclosed, those skilled in the art would appreciate that the preferred embodiments may be varied without departing from the spirit and scope of the present invention. Thus, the present invention is not limited to the preferred embodiments, and the appended claims comprise any and all such applications, modification, and embodiments within the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A method for scheduling user equipment in a wireless communication system supporting dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, and the two base stations include a macro base station and a small base station, the method comprising:

sending a dual connectivity setup request message from the macro base station to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment; and

enabling the macro base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

2. The method according to claim 1, wherein the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity.

3. The method according to claim 2, wherein the information related to the user equipment capability comprises at least one of the following items:

a value set according to a total number of soft channel bits transmitted by the downlink;

a maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the user equipment cannot simultaneously transmit uplink data to the macro base station and the small base station;

a maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when the user equipment cannot simultaneously receive downlink data from the macro base station and the small base station;

a value set according to the maximum number of Uplink-Shared Channel transport block bits transmitted within the transmission time interval when the user equipment can simultaneously transmit uplink data to the macro base station and the small base station;

a value set according to the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when the user equipment can simultaneously receive the downlink data from the macro base station and the small base station;

a number of data radio bearers established for the user equipment, or the number of data radio bearers which are established for the user equipment and not offloaded to the small base station, or a sum of downlink bit rates of the data radio bearers established for the user equipment, or a sum of downlink bit rates of the data radio bearers which are established for the user equipment and not offloaded to the small base station, when the user equipment can simultaneously receive the downlink data from the macro base station and the small base station;

a number of data radio bearers established for the user equipment, or the number of data radio bearers which are established for the user equipment and not offloaded to the small base station, or a sum of uplink bit rates of the data radio bearers established for the user equipment, or a sum of uplink bit rates of the data radio bearers which are established for the user equipment and not offloaded to the small base station, when the user equipment can simultaneously transmit uplink data to the macro base station and the small base station; and

the user equipment's category information.

4. The method according to claim 3, wherein the method further comprises: receiving from the user equipment an indication indicating that the received

Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a radio resource control signaling or media access control layer control information element; and

reducing amount of data transmitted to the user equipment based on the indication.

5. The method according to claim 1, wherein the method further comprises: transmitting a radio resource control connection reconfiguration message to the user equipment so that the user equipment is accessed to the small base station.

6. A method for scheduling user equipment in a wireless communication system supporting dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, and the two base stations include a macro base station and a small base station, the method comprising: receiving a dual connectivity setup request message from the macro base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the macro base station to perform resource schedule for the user equipment in the connectivity with the user equipment; and

enabling the small base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

7. The method according to claim 6, wherein the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity.

8. The method according to claim 7, wherein the information related to the user equipment capability comprises at least one of the following items:

a value set according to total number of soft channel bits transmitted by the downlink;

the user equipment's category information.

9. The method according to claim 8, wherein the method further comprises: receiving from the user equipment an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a media access control layer control information element; and

10. The method according to claim 6, wherein the small base station using the information to perform resource schedule for the user equipment in the connectivity with the user equipment comprises:

the small base station allocating transmission resource for the user equipment based on the information.

11. An apparatus for scheduling user equipment in a wireless communication system supporting the dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, and the two base stations include a macro base station and a small base station, the apparatus comprising: a transmitting unit configured to transmit a dual connectivity setup request from the macro base station to the small base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the small base station to perform resource schedule for the user equipment in the connectivity with the user equipment; and

a scheduling unit configured to enable the macro base station to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

12. The apparatus according to claim 11, wherein the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity.

13. The apparatus according to claim 12, wherein the information related to the user equipment capability comprises at least one of the following items:

a value set according to the maximum number of Downlink-Shared Channel transport block bits received within the transmission time interval when the user equipment can simultaneously receive the downlink data from the macro base station and the small base station; a number of data radio bearers established for the user equipment, or the number of data radio bearers which are established for the user equipment and not offloaded to the small base station, or a sum of downlink bit rates of the data radio bearers established for the user equipment, or a sum of downlink bit rates of the data radio bearers which are established for the user equipment and not offloaded to the small base station, when the user equipment can simultaneously receive the downlink data from the macro base station and the small base station;

the user equipment' s category information.

14. The apparatus according to claim 13, wherein the apparatus further comprises: a receiving unit configured to receive from the user equipment an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a radio resource control signaling or media access control layer control information element; and

a reducing unit configured to reduce amount of data transmitted to the user equipment based on the indication.

15. The apparatus according to claim 11, wherein the transmitting unit is further configured to transmit a radio resource control connection reconfiguration message to the user equipment so that the user equipment is accessed to the small base station.

16. An apparatus for scheduling user equipment in a wireless communication system supporting the dual connectivity, wherein the user equipment remains connected to both of two base stations in the dual connectivity, and the two base stations include a macro base station and a small base station, the apparatus comprising: a receiving unit configured to receive a dual connectivity setup request from the macro base station, wherein the dual connectivity setup request message comprises information related to user equipment capability, and the information is used by the macro base station to perform resource schedule for the user equipment in the connectivity with the user equipment; and a scheduling unit configured to use the information to perform resource schedule for the user equipment in the connectivity with the user equipment.

17. The apparatus according to claim 16, wherein the information related to the user equipment capability comprises at least one item of capability information of information related to category of the user equipment, information about whether the user equipment supports simultaneous transmission in the dual connectivity, and information about whether the user equipment supports simultaneous reception in the dual connectivity.

18. The apparatus according to claim 17, wherein the information related to the user equipment capability comprises at least one of the following items:

the user equipment's category information.

19. The apparatus according to claim 18, wherein the receiving unit is further configured to receive from the user equipment an indication indicating that the received Downlink-Shared Channel transport block bits exceed the maximum number, the indication being carried in a media access control layer control information element; and

20. The apparatus according to claim 16, wherein the scheduling unit is further configured to enable the small base station to allocate the transmission resources for the user equipment based on the information.