WO2013023353A1

WO2013023353A1 - System information delivery for inter-site carrier aggregation

Info

Publication number: WO2013023353A1
Application number: PCT/CN2011/078408
Authority: WO
Inventors: Haitao Li; Kodo Shu
Original assignee: Nokia Corporation
Priority date: 2011-08-15
Filing date: 2011-08-15
Publication date: 2013-02-21

Abstract

A method for an inter-site carrier aggregation comprises: determining a signaling interface for delivery of system information relevant to the inter-site carrier aggregation; and delivering the system information from a first network node to a second network node through the signaling interface, wherein upon configuration of the inter-site carrier aggregation, the first network node acts as a slave node and the second network node acts as a master node.

Description

SYSTEM INFORMATION DELIVERY FOR

INTER-SITE CARRIER AGGREGATION

FIELD OF THE INVENTION

The present invention generally relates to communication networks. More specifically, the invention relates to Carrier Aggregation (CA).

BACKGROUND

The modern communications era has brought about a tremendous expansion of communication networks. Wireless and mobile networking technologies have addressed related consumer demands, while providing more flexibility and immediacy of information transfer. In release 10 of 3 GPP (3rd Generation Partnership Project), CA is designed to support a total transmission bandwidth of up to 100MHz. In CA, a user equipment (UE) can aggregate multiple backward- compatible cells for data transmissions, among which one is called the Primary Cell (PCell) and others are called Secondary Cells (SCells). The PCell is mostly responsible for the UE's connection control and uplink control channel transmission, while SCells are usually modeled as additional resources for purely increasing transmission bandwidth.

SUMMARY

The present description introduces a new signaling procedure for a SCell System Information (SI) delivery under an inter-site CA scenario, which involves a backhaul signaling procedure for a slave node to transfer its SCell' s all CA-relevant SI to a master node for CA purpose.

According to a first aspect of the present invention, there is provided a method comprising: determining a signaling interface for delivery of SI relevant to an inter-site CA; and delivering the SI from a first network node to a second network node through the signaling interface, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to a second aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following: determining a signaling interface for delivery of SI relevant to an inter-site CA; and delivering the SI from the apparatus to another apparatus through the signaling interface, wherein upon configuration of the inter- site CA, the apparatus acts as a slave node and the another apparatus acts as a master node.

According to a third aspect of the present invention, there is provided a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for determining a signaling interface for delivery of SI relevant to an inter-site CA; and code for delivering the SI from a first network node to a second network node through the signaling interface, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to a fourth aspect of the present invention, there is provided an apparatus comprising: determining means for determining a signaling interface for delivery of SI relevant to an inter-site CA; and delivering means for delivering the SI from the apparatus to another apparatus through the signaling interface, wherein upon configuration of the inter- site CA, the apparatus acts as a slave node and the another apparatus acts as a master node.

According to exemplary embodiments, the apparatus (comprising an eNB) according to the second aspect or the fourth aspect of the present invention may function as the first network node, and the another apparatus (comprising an eNB) according to the second aspect or the fourth aspect of the present invention may function as the second network node. In accordance with exemplary embodiments, the signaling interface may comprise an interface between the first network node and the second network node, and said delivering may comprise sending the SI directly to the second network node through this interface. For example, the SI may be delivered via a backhaul signaling procedure comprising an evolved Node B (eNB) configuration update procedure between the first network node and the second network node. Alternatively, the signaling interface may comprise an interface between the first network node and a network entity, and said delivering may comprise sending the SI to the network entity through this interface, wherein the SI is forwarded from the network entity to the second network node through another interface between the network entity and the second network node. For example, the SI may be delivered via a backhaul signaling procedure comprising an eNB direct information transfer procedure between the first network node and the network entity, and a mobility management entity (MME) direct information transfer procedure between the network entity and the second network node.

In accordance with exemplary embodiments, the interface between the first and the second network nodes may have higher priority to be determined as the signaling interface than the interface between the first network node and the network entity. For example, the SI (such as the up-to-date SI relevant to the inter-site CA) may comprise radio resource configuration information, such as some downlink (DL) and uplink (UL) system-level configuration information, which may be delivered in a proactive mode or a reactive mode.

According to a fifth aspect of the present invention, there is provided a method comprising: determining a signaling interface for obtaining SI relevant to an inter- site CA; and obtaining the SI from a first network node by a second network node through the signaling interface, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to a sixth aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following: determining a signaling interface for obtaining SI relevant to an inter-site CA; and obtaining the SI from another apparatus through the signaling interface, wherein upon configuration of the inter-site CA, the another apparatus acts as a slave node and the apparatus acts as a master node.

According to a seventh aspect of the present invention, there is provided a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for determining a signaling interface for obtaining SI relevant to an inter-site CA; and code for obtaining the SI from a first network node by a second network node through the signaling interface, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to an eighth aspect of the present invention, there is provided an apparatus comprising: determining means for determining a signaling interface for obtaining SI relevant to an inter-site CA; and obtaining means for obtaining the SI from another apparatus by the apparatus through the signaling interface, wherein upon configuration of the inter-site CA, the another apparatus acts as a slave node and the apparatus acts as a master node.

According to exemplary embodiments, the apparatus (comprising an eNB) according to the sixth aspect or the eighth aspect of the present invention may function as the second network node, and the another apparatus (comprising an eNB) according to the sixth aspect or the eighth aspect of the present invention may function as the first network node. In accordance with exemplary embodiments, the signaling interface may comprise an interface between the first network node and the second network node, and said obtaining may comprise fetching the SI directly from the first network node through this interface. Alternatively, the signaling interface may comprise an interface between the second network node and a network entity, and said obtaining may comprise fetching the SI from the network entity through this interface, wherein the SI is delivered from the first network node to the network entity through another interface between the first network node and the network entity.

In accordance with exemplary embodiments, the interface between the first and the second network nodes may have higher priority to be determined as the signaling interface than the interface between the second network node and the network entity. For example, the SI (such as the up-to-date SI relevant to the inter-site CA) may comprise radio resource configuration information, such as some DL and UL system-level configuration information, which may be obtained by the second network node in response to a proactive delivery or a reactive delivery of SI by the first network node. In an exemplary embodiment, an acknowledgement procedure may be triggered at the second network node upon obtaining the SI. The second network node may inform a UE of the SI when it acts as the master node of the inter- site CA for the UE.

According to a ninth aspect of the present invention, there is provided a method comprising: receiving SI relevant to an inter- site CA from a first network node; and forwarding the SI to a second network node, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to a tenth aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following: receiving SI relevant to an inter-site CA from a first network node; and forwarding the SI to a second network node, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to a eleventh aspect of the present invention, there is provided a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for receiving SI relevant to an inter-site CA from a first network node; and code for forwarding the SI to a second network node, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to a twelfth aspect of the present invention, there is provided an apparatus comprising: receiving means for receiving SI relevant to an inter- site CA from a first network node; and forwarding means for forwarding the SI to a second network node, wherein upon configuration of the inter-site CA, the first network node acts as a slave node and the second network node acts as a master node.

According to exemplary embodiments, the apparatus according to the tenth aspect or the twelfth aspect of the present invention may comprise a MME or other intermediate entity in a core network, which can receives the SI relevant to the inter-site CA through an interface (such as SI interface) connected to the first network node and forward the SI to the second network node through an interface (such as SI interface) connected to the second network node. In exemplary embodiments of the present invention, the provided methods, apparatus, network node, network entity and computer program products can enable a master node to always obtain up-to-date SI relevant to an inter-site CA (such as SCell's SI) from a slave node and to inform a UE (which is under an inter-site CA configuration of this master node) of the SCell's most up-to-date SI, which is crucial for the UE to work on this SCell.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which:

Fig.l shows an exemplary scenario of inter-site CA in accordance with an embodiment of the present invention;

Fig.2 is a flowchart illustrating a method for inter-site CA, which may be implemented at a network node acting as a slave node in an inter-site CA configuration in accordance with embodiments of the present invention;

Fig.3 is a flowchart illustrating a method for inter-site CA, which may be implemented at a network node acting as a master node in an inter-site CA configuration in accordance with embodiments of the present invention;

Fig.4a exemplarily shows a signaling flow of X2-based solution in accordance with an embodiment of the present invention;

Fig.4b exemplarily shows a signaling flow of Sl-based solution in accordance with an embodiment of the present invention;

Fig.5 a shows an example of a proactive SI delivery procedure in accordance with an embodiment of the present invention;

Fig.5b shows an example of a proactive SI delivery procedure in accordance with another embodiment of the present invention;

Fig.6a shows an example of a reactive SI delivery procedure in accordance with an embodiment of the present invention;

Fig.6b shows an example of a reactive SI delivery procedure in accordance with another embodiment of the present invention; and

Fig.7 is a simplified block diagram of various apparatuses which are suitable for use in practicing exemplary embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention are described in detail with reference to the accompanying drawings. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

In a current architecture, most scenarios are directed to co-site CA in which a UE aggregates co-site cells from a single eNB or base station (BS) or access point (AP). Among them, an exceptional case is such a scenario where a Remote Radio Head (RRH) is deployed in a different site but connected with its eNB through a fiber link. Beyond these, a future potential CA scenario might go beyond such limitations of co-site CA or a necessary physical fiber link.

An exemplary scenario is presented in Fig.l where in an overlapping coverage of macro and pico cells, a UE can aggregate these two cells to achieve higher data rate. For example, in the case that a pico cell is deployed on a different layer than the macro one where X2 interface exists between them, for the overlapping coverage, traffic steering or offloading can be easily achieved by the UE through inter-site CA, as shown in Fig.l. For the inter- site CA involving different eNBs, an eNB in charge of a PCell can be called as a 'master node', and an inter-site eNB of SCells can be called as a 'slave node' .

As mentioned previously, a UE in CA can aggregate multiple backward- compatible cells for data transmissions. For CA to work, the UE first needs to obtain necessary CA-relevant SI which comprises some important cell specific common configuration information from its aggregated cells. In the current 3 GPP specification, the UE is not required to monitor the broadcasted SI from SCells. All the SCell's SI is delivered to the UE through a dedicated Radio Resource Control (RRC) signaling (such as the RRCConnectionReconfiguration message), for both cases of initial SCell addition and SCell SI update. More specifically, for the case of SCell SI update, an eNB delivers the updated SI to the UE by a combination action of removing and then adding the concerned SCell.

For co-site CA, the SCell's CA-relevant SI content may be specified as below, which can be comprised in the RRCConectionReconfiguration message over air interface, for example.

Above procedures are well established for co-site CA scenarios, since a single eNB entity is in charge of all the aggregated cells. Under the same eNB, any cell (for example PCell) can obtain SI of another cell (for example SCell) through an internal eNB implementation. However, in case of inter-site CA, upon initial SCell addition of a slave node, a PCell (or a master node) does not get all CA-relevant SI of the SCell according to current 3GPP status. Since one eNB (acting as a master node) cannot get any SCell' s CA-relevant SI from another eNB (acting as a slave node) currently, it is desirable to define a procedure for an inter- site CA-relevant SI delivery and design corresponding solutions for a master node and a slave node under inter- site CA scenarios.

In a communication network, CA may be applied for providing high data rate for a UE and CA can be configured by an eNB which would act as a master node after inter-site CA is enabled. When the UE indicates the eNB of a good candidate slave node through a measurement report, the eNB can decide whether to configure this slave node to the UE based at least in part on the UE's service requirement and its own network conditions. Once the decision is positive, the master node needs to fetch SCell's CA-relevant SI from this slave node. After the master node gets the SCell's CA-relevant SI, it can configure (for example, add) the slave node to the UE by using a dedicated message (for example, a RRC message such as RRCConnectionReconfiguration message). In this message, the master node can provide the slave node's CA-relevant SI to the UE. When the UE obtains the slave node's SI, it can work properly on this slave node.

After the CA has been configured, it is possible for the slave node to update its SI. In that case, the UE needs to know the exact updated SI to work properly on this slave node under CA. To achieve this, the slave node is required to pass its updated CA-relevant SI to the master node, and then the master node can notify the UE of the updated SI from the slave node through using a dedicated message (for example, a RRC message such as RRCConnectionReconfiguration message).

Thus it can be seen that for CA purpose, transmission of CA-relevant SI from a slave node to a master node is required for both cases of initial slave node (SCell) addition and slave node (SCell) SI update.

Fig.2 is a flowchart illustrating a method for inter-site CA, which may be implemented at a network node acting as a slave node in an inter-site CA configuration in accordance with embodiments of the present invention. With this method, the network node (such as a BS/eNB/AP/control center) can provide its CA-relevant SI to another network node (such as a BS/eNB/AP/control center) which serves as a master node in the inter- site CA configuration. For example, the CA configuration mainly addresses the function of adding/modifying/removing a SCell. For initial SCell addition, the CA configuration means adding a new SCell. In this adding process, besides SCell's SI, other dedicated configuration information may be sent from a master node (PCell) to a UE under the CA configuration. Moreover, a slave node may send its updated CA-relevant SI to the master node after CA has been configured.

In block 202, a first network node, which may act as a slave node upon configuration of an inter-site CA, determines a signaling interface for delivery of SI relevant to the inter-site CA. For example, the first network node may select an existing interface such as X2 interface or S 1 interface, or establish a new interface for this SCell SI delivery. In an exemplary embodiment, the determination of the signaling interface may be made by negotiations between the first network node and a second network node to which the SI from the first network node will be delivered, or according to transmission conditions of available interfaces, or considering service quality requirements. The SI relevant to the inter- site CA may comprise radio resource configuration information provided by the first network node. For example, it may comprise the related cell's physical layer radio resource configuration information, such as frequency, bandwidth, some physical channels' configuration information, and etc. According to an exemplary embodiment, the delivered SI relevant to the inter- site CA may comprise but not limited to the content specified for co-site CA as illustrated previously with respect to the RRCConectionReconfiguration message. For example, it may mainly relate to some DL and UL system-level configuration information.

Through the determined signaling interface, the first network node can deliver the SI relevant to the inter- site CA to a second network node which may act as a master node upon the configuration of an inter- site CA, as shown in block 204. In an exemplary embodiment, the signaling interface may comprise an interface between the first network node and the second network node. Accordingly, delivering SI relevant to the inter-site CA to the second network node may comprise sending the SI directly to the second network node through this interface. In an exemplary embodiment, such delivery involves a backhaul signaling procedure between the first network node and the second network node, which may be a newly designed signaling procedure or a current signaling procedure such as the current eNB Configuration Update procedure.

According to an exemplary embodiment, the interface between the first network node (the slave node) and the second network node (the master node) may comprise X2 interface. Through the X2 interface, the slave node passes its SCell's (updated) CA-relevant SI to the master node. As for the detailed message design, the current eNB Configuration Update procedure can be reused. Below in Table 1 is the structure of the eNB Configuration Update message. More specifically, the Information Element (IE) 'Served Cell Information' may be extended to comprise this served cell's CA-relevant SI.

Table 1 ENB CONFIGURATION UPDATE message

With this implementation, a signaling flow of X2-based solution in accordance with an embodiment of the present invention is shown in Fig.4a. In order for delivery of SCell's CA-relevant SI through X2 interface, an eNB Configuration Update procedure is performed after initial X2 setup between two eNBs (show as a slave node and a master node in Fig.4a). Such signaling procedure also may be used for the cases of adding served cells, subsequent updating of the slave node's information, or modify ing/deleting served cells, for example. With the above message extension, the master node (corresponding to the PCell) can get the up-to-date SCell's SI from the slave node, whenever it needs to add a new SCell or an existing SCell has changed its SI.

In an alternative embodiment, the signaling interface determined by the first network node may comprise an interface between the first network node and a network entity (such as a MME or other suitable intermediate entity in core networks). In this case, delivering SI relevant to the inter-site CA may comprise sending said SI through this interface to the network entity which then forwards the received SI to the second network node through another interface between the network entity and the second network node. For example, this delivery may involve backhaul signaling procedures such as an eNB direct information transfer procedure between the first network node and the network entity, and a MME direct information transfer procedure between the network entity and the second network node. It is also possible to reuse other current signaling procedures or design some new signaling procedures for delivery of SI relevant to the inter-site CA.

According to an exemplary embodiment, the interface between the first network node (the slave node) and the network entity (for example a MME in a core network) may comprise SI interface. Through the SI interface to and from the core network, the slave node transfers its SCell's (updated) CA-relevant SI to the master node. Fig.4b exemplarily shows a signaling flow of SI -based solution in accordance with an embodiment of the present invention. This SI -based solution involves two sub-procedures, one from the slave node to the MME and the other from the MME to the master node. In an exemplary embodiment, current two procedures, for example, eNB DIRECT INFORMATION TRANSFER and MME DIRECT INFORMATION TRANSFER can be reused and SCell's SI is extended in the corresponding message, in order for delivering up-to-date SI relevant to inter-site CA from the slave node to the master node via the MME.

According to the method as illustrated in Fig.2, a salve node can transfer SCell's SI to a master node directly (for example, through X2 interface as shown in Fig.4a) or indirectly (for example, through SI interface as shown in Fig.4b), so that the master node can provide the updated SI to a UE under a CA configuration of this master node. In an exemplary embodiment, considering some factors such as delay and network overhead, the direct delivery of CA-relevant SI through the interface (such as X2 interface) between the first network node (corresponding to the slave node) and the second network node (corresponding to the master node) is preferable to the indirect delivery of CA-relevant SI through the interface (such as SI interface) between the first network node and the network entity as well as the interface (such as SI interface) between the network entity and the second network node. As an example, the direct delivery may be designed for fast updating of SI, as the interface between the first network node and the second network node may have less delay (for example, X2 has 20ms delay at max), while the indirect delivery may be designed for a scenario where the direct delivery is not available. According to an exemplary embodiment, the interface between the first network node and the second network node has higher priority to be determined as the signaling interface for delivery of CA-relevant SI than the one between the first network node and the network entity.

Generally, the first network node may transmit its SCell's all CA-relevant SI to the second network node proactively, for example, when an interface between the first and the second network nodes is initially setup and when the first network node has changed its SI subsequently, or reactively when the second network node requests SCell's SI from the first network node to configure CA and/or update CA-relevant SI for a UE. In an exemplary embodiment, the SI relevant to inter- site CA from the first network node may be delivered in a proactive mode and/or a reactive mode, which will be detailed later in connection with Figs. 5a-5b and Figs. 6a-6b.

Reference is now made to Fig.3, which is a flowchart illustrating a method for inter-site CA in accordance with embodiments of the present invention. This method may be implemented at a network node (such as a BS/eNB/AP/control center) acting as a master node in an inter- site CA configuration, enabling this network node to get the required CA-relevant SI from another network node (such as a BS/eNB/AP/control center) which serves as a slave node in this inter-site CA configuration.

As a counterpart of a first network node delivering SI relevant to an inter- site CA, a second network node determines a signaling interface for obtaining the SI relevant to the inter-site CA, as shown in block 302. Similar to the above description with reference to Fig.2, upon configuration of the inter-site CA, the first network node may act as a slave node and the second network node may act as a master node. The second network node can obtain such SI from the first network node through the determined signaling interface, as shown in block 304. As mentioned previously, the determination of the signaling interface may be made for example by negotiations between the first network node and the second network node, or according to transmission conditions of available interfaces, or considering service quality requirements. In an exemplary embodiment, this signaling interface may comprise an interface between the first network node and the second network node, and the second network node may fetch the SI directly from the first network node through this interface. Alternatively, the signaling interface may comprise an interface between the second network node and a network entity such as a MME or other intermediate entity in core networks. Through this interface, the second network node may fetch the SI relevant to inter- site CA from the network entity which obtains such SI from the first network node through another interface between the first network node and the network entity. Considering transmission conditions and some other factors such as delay and network overhead, the interface (such as X2 interface) between the first network node and the second network node has higher priority to be determined as the signaling interface for obtaining CA-relevant SI than the interface (such as SI interface) between the second network node and the network entity. Particularly, the interface between the second network node and the network entity may be used in case that the interface between the first and the second network nodes is not available.

In an exemplary embodiment, an acknowledgement procedure may be triggered at the second network node upon obtaining the CA-relevant SI. For example, when the second network node obtains SCell's CA-relevant SI from the first network node via an eNB Configuration Update procedure, it can provide an acknowledgement to the first network node via an eNB Configuration Update Acknowledge procedure, as shown in Fig.4a. With the obtained SI relevant to the inter-site CA, which may comprise radio resource configuration information such as frequency, bandwidth and etc. from the first network node, the second network node (serving as a master node in an inter- site CA configuration) can configure or add the first network node as a slave node to a UE under this CA configuration, and notify this UE of the up-to-date SI from the slave node.

According to exemplary embodiments, the SI relevant to an inter-site CA may be delivered in a proactive mode and/or a reactive mode. Fig.5a-5b exemplarily show a proactive SI delivery procedure in accordance with embodiments of the present invention, and Fig.6a-6b exemplarily show a reactive SI delivery procedure in accordance with embodiments of the present invention. In the proactive mode, no matter whether CA is configured, the CA-relevant SI is transferred by the first network node (which may act as a slave node in a CA configuration) towards the second network node (which may act as a master node in the CA configuration). For example, upon initial setup of an interface between the two network nodes and/or upon update of SI after the initial setup of the interface, the first network node (such as a local area network node or a pico eNB/BS/AP/control center) may transfer its SCell's CA-relevant SI directly to the second network node (such as a network node in charge of a macro cell), as shown in Fig.5a. Alternatively, the first network node may proactively transfer its SCell's CA-relevant SI to a network entity in a core network and then to the second network node, as shown in Fig.5b. As such, whenever CA is to be enabled, the second network node acting as a master node has obtained a slave node's CA-relevant SI from the first network node. Alternatively or additionally, in the reactive mode, a delivery of CA-relevant SI is performed in response to a request from a master node when CA is to be configured. As the master node, the second network node may request CA-relevant SI from the first network node serving as the slave node, for example, in the case of initial SCell (slave node) addition. With a response from the slave node (as shown in Fig.6a) or a network entity in core networks (as shown in Fig.6b) to this request, the master node can fetch the required CA-relevant SI. In other words, the SI relevant to an inter-site CA can be obtained by the second network node in response to a proactive delivery and/or a reactive delivery of the SI (such as the up-to-date SI relevant to inter-site CA) by the first network node.

Specifically, the descriptions herein define a new signaling procedure for a SCell's SI delivery under an inter-site CA scenario, which may involve a backhaul signaling procedure for a slave node to transmit its SCell's all CA-relevant SI to a master node for CA purpose. For example, two technical options may be available. Option one is to propose that whenever a non-cosited SCell is configured or has SI updated, the SCell (slave node) may send its CA-relevant SI information via a message (such as a modified X2 signaling message) to the master node. Alternatively, option two is to propose that whenever a non-cosited SCell is configured or has SI updated, the SCell (slave node) may send its CA-relevant SI information via a message (such as a modified eNB-MME signaling message) to a network entity such as a MME and then from this network entity to the master node via another message (such as a modified MME-eNB signaling message). According to exemplary embodiments, a network entity (as an intermediate part) may receive SI relevant to an inter- site CA from a slave node and then forward the received SI to a master node.

The various blocks shown in Fig.2 and Fig.3 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s). The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated methods. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. By applying the proposed methods, a master node can fetch S Cell's CA-relevant SI from a slave node through a backhaul signaling interface (such as X2 or SI interface) before or at the time of an initial addition of the slave node (SCell). For the case that the slave node (SCell) updates its SI, the slave node also can notify the master node of its up-to-date CA-relevant SI through a backhaul signaling interface (such as X2 or SI interface). As such, the master node can always obtain the SCell' s SI from the slave node, and inform the related UE of the SCell's most up-to-date SI (which is crucial for the UE to work on this SCell) for example through dedicated RRC signaling, even when this SCell has been deactivated. Although the proposed solution may introduce an extra network overhead (for example, the SI -based solution causes further a bit of core network overhead compared with the X2-based solution), such slight increase of backhaul signaling overhead is normally tolerable.

Fig.7 illustrates a simplified block diagram of various apparatuses which are suitable for use in practicing exemplary embodiments of the present invention. In Fig.7, network nodes 710 and 720 (such as a BS/eNB/AP/control center) may be adapted for communicating with each other directly or through a network entity 730 (such as a MME or other intermediate entity in a core network). In an exemplary embodiment, the network node 710 may comprise a data processor (DP) 71 OA, a memory (MEM) 710B that stores a program (PROG) 7 IOC, and a suitable transceiver 710D for communicating with an apparatus such as the network node 720, the network entity 730 or a UE (not shown in Fig.7). Similarly, the network node 720 may comprise a data processor (DP) 720A, a memory (MEM) 720B that stores a program (PROG) 720C, and a suitable transceiver 720D for communicating with an apparatus such as the network node 710, the network entity 730 or a UE (not shown in Fig.7). For example, at least one of the transceivers 710D and 720D may be an integrated component for transmitting and/or receiving signals and messages. Alternatively, at least one of the transceivers 710D and 720D may comprise separate components to support transmitting and receiving signals/messages, respectively. The respective DPs 710A and 720A may be used for processing these signals and messages. Alternatively or additionally, the network node 710, 720 may comprise various means and/or components for implementing functions of the foregoing steps and methods in Fig.2 and Fig.3. For example, the network node 710, which acts as a slave node upon configuration of an inter- site CA, may comprise: determining means for determining a signaling interface for delivery of SI relevant to the inter- site CA; and delivering means for delivering the SI from the network node 710 to another network node 720 (which acts as a master node upon the configuration of the inter- site CA) through the determined signaling interface. In case that the network node 710 acts as a master node upon configuration of an inter-site CA, it may comprise: determining means for determining a signaling interface for obtaining SI relevant to the inter-site CA; and obtaining means for obtaining the SI from another network node 720 (which acts as a slave node upon the configuration of the inter-site CA) through the determined signaling interface.

According to exemplary embodiments, the determined signaling interface may comprise an interface between the network nodes 710 and 720 or an interface between the network node 710, 720 and the network entity 730. The network entity 730 may also comprise a DP 730A, a MEM 730B that stores a PROG 730C, and a suitable transceiver 730D. The transceiver 730D can be used for communicating with a network node (such as the network node 710, 720) and/or other devices within a communication network. For example, the transceiver 730D may be an integrated component for transmitting and/or receiving signals and messages. Alternatively, the transceiver 730D may comprise separate components to support transmitting and receiving signals/messages, respectively. The DP 730A may be used for processing these signals and messages. According to another exemplary embodiment, the network entity 730 may comprise various means and/or components for assisting delivery of inter- site CA-relevant SI between a slave node and a master node. For example, the network entity 730 may comprise: receiving means for receiving SI relevant to an inter- site CA from a first network node (such as the network node 710); and forwarding means for forwarding the SI to a second network node (such as the network node 720). Upon configuration of the inter- site CA, the first network node acts as a slave node and the second network node acts as a master node.

At least one of the PROGs 710C, 720C, 730C is assumed to comprise program instructions that, when executed by the associated DP, enable an apparatus to operate in accordance with the exemplary embodiments, as discussed above. That is, the exemplary embodiments of the present invention may be implemented at least in part by computer software executable by the DP 710A of the network node 710, by the DP 720A of the network node 720 and by the DP 730A of the network entity 730, or by hardware, or by a combination of software and hardware.

The MEMs 710B, 720B and 730B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs 71 OA, 720A and 730 A may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architectures, as non-limiting examples.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It will be appreciated that at least some aspects of the exemplary embodiments of the inventions may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM), and etc. As will be realized by one of skill in the art, the functionality of the program modules may be combined or distributed as desired in various embodiments. In addition, the functionality may be embodied in whole or in part in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA), and the like.

Although specific embodiments of the invention have been disclosed, those having ordinary skill in the art will understand that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted therefore to the specific embodiments, and it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.

Claims

CLAIMS What is claimed is:

1. A method, comprising:

determining a signaling interface for delivery of system information relevant to an inter- site carrier aggregation; and

delivering the system information from a first network node to a second network node through the signaling interface,

wherein upon configuration of the inter- site carrier aggregation, the first network node acts as a slave node and the second network node acts as a master node.

2. The method according to claim 1, wherein the signaling interface comprises a first interface between the first network node and the second network node, and said delivering comprises:

sending the system information directly to the second network node through the first interface.

3. The method according to claim 1, wherein the signaling interface comprises a second interface between the first network node and a network entity, and said delivering comprises:

sending the system information to the network entity through the second interface, wherein the system information is forwarded from the network entity to the second network node through a third interface between the network entity and the second network node.

4. The method according to claim 3, wherein the first interface has higher priority to be determined as the signaling interface than the second interface.

5. The method according to any one of claims 1 to 4, wherein the system information is delivered in a proactive mode or a reactive mode.

6. The method according to any one of claims 1 to 5, wherein the system information comprises radio resource configuration information.

7. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following:

determining a signaling interface for delivery of system information relevant to an inter-site carrier aggregation; and

delivering the system information from the apparatus to another apparatus through the signaling interface,

wherein upon configuration of the inter- site carrier aggregation, the apparatus acts as a slave node and the another apparatus acts as a master node.

8. The apparatus according to claim 7, wherein the signaling interface comprises a first interface between the apparatus and the another apparatus, and said delivering comprises:

sending the system information directly to the another apparatus through the first interface.

9. The apparatus according to claim 7, wherein the signaling interface comprises a second interface between the apparatus and a network entity, and said delivering comprises: sending the system information to the network entity through the second interface, wherein the system information is forwarded from the network entity to the another apparatus through a third interface between the network entity and the another apparatus.

10. The apparatus according to claim 9, wherein the first interface has higher priority to be determined as the signaling interface than the second interface.

11. The apparatus according to any one of claims 7 to 10, wherein the apparatus comprises an evolved Node B and the another apparatus comprises an evolved Node B.

12. The apparatus according to any one of claims 7 to 11, wherein the system information is delivered in a proactive mode or a reactive mode.

13. A computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for determining a signaling interface for delivery of system information relevant to an inter- site carrier aggregation; and

code for delivering the system information from a first network node to a second network node through the signaling interface,

14. The computer program product according to claim 13, wherein the signaling interface comprises a first interface between the first network node and the second network node, and said delivering comprises: sending the system information directly to the second network node through the first interface.

15. The computer program product according to claim 13, wherein the signaling interface comprises a second interface between the first network node and a network entity, and said delivering comprises:

16. The computer program product according to claim 15, wherein the first interface has higher priority to be determined as the signaling interface than the second interface.

17. An apparatus, comprising:

determining means for determining a signaling interface for delivery of system information relevant to an inter- site carrier aggregation; and

delivering means for delivering the system information from the apparatus to another apparatus through the signaling interface,

wherein upon configuration of the inter-site carrier aggregation, the apparatus acts as a slave node and the another apparatus acts as a master node.

18. A method, comprising:

determining a signaling interface for obtaining system information relevant to an inter- site carrier aggregation; and

obtaining the system information from a first network node by a second network node through the signaling interface, wherein upon configuration of the inter- site carrier aggregation, the first network node acts as a slave node and the second network node acts as a master node.

19. The method according to claim 18, wherein the signaling interface comprises a first interface between the first network node and the second network node, and said obtaining comprises:

fetching the system information directly from the first network node through the first interface.

20. The method according to claim 18, wherein the signaling interface comprises a second interface between the second network node and a network entity, and said obtaining comprises:

fetching the system information from the network entity through the second interface, wherein the system information is delivered from the first network node to the network entity through a third interface between the first network node and the network entity.

21. The method according to claim 20, wherein the first interface has higher priority to be determined as the signaling interface than the second interface.

22. The method according to any one of claims 18 to 21, wherein an acknowledgement procedure is triggered at the second network node upon obtaining the system information.

23. The method according to any one of claims 18 to 22, wherein the system information is obtained by the second network node in response to a proactive delivery or a reactive delivery of the system information by the first network node.

24. The method according to any one of claims 18 to 23, further comprising: informing a user equipment of the system information when the second network node acts as the master node of the inter-site carrier aggregation for the user equipment.

25. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

obtaining the system information from another apparatus through the signaling interface,

wherein upon configuration of the inter- site carrier aggregation, the another apparatus acts as a slave node and the apparatus acts as a master node.

26. The apparatus according to claim 25, wherein the signaling interface comprises a first interface between the apparatus and the another apparatus, and said obtaining comprises:

fetching the system information directly from the another apparatus through the first interface.

27. The apparatus according to claim 25, wherein the signaling interface comprises a second interface between the apparatus and a network entity, and said obtaining comprises:

fetching the system information from the network entity through the second interface, wherein the system information is delivered from the another apparatus to the network entity through a third interface between the another apparatus and the network entity.

28. The apparatus according to claim 27, wherein the first interface has higher priority to be determined as the signaling interface than the second interface.

29. The apparatus according to any one of claims 25 to 28, wherein the apparatus comprises an evolved Node B and the another apparatus comprises an evolved Node B.

30. The apparatus according to any one of claims 25 to 29, wherein an acknowledgement procedure is triggered at the apparatus upon obtaining the system information.

31. The apparatus according to any one of claims 25 to 30, wherein the system information is obtained by the apparatus in response to a proactive delivery or a reactive delivery of the system information by the another apparatus.

32. The apparatus according to any one of claims 25 to 31, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to further perform: informing a user equipment of the system information when the apparatus acts as the master node of the inter-site carrier aggregation for the user equipment.

33. A computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for determining a signaling interface for obtaining system information relevant to an inter- site carrier aggregation; and

code for obtaining the system information from a first network node by a second network node through the signaling interface,

34. The computer program product according to claim 33, wherein the signaling interface comprises a first interface between the first network node and the second network node, and said obtaining comprises:

35. The computer program product according to claim 33, wherein the signaling interface comprises a second interface between the second network node and a network entity, and said obtaining comprises:

36. The computer program product according to claim 35, wherein the first interface has higher priority to be determined as the signaling interface than the second interface.

37. An apparatus, comprising:

determining means for determining a signaling interface for obtaining system information relevant to an inter- site carrier aggregation; and obtaining means for obtaining the system information from another apparatus through the signaling interface,

38. A method, comprising:

receiving system information relevant to an inter-site carrier aggregation from a first network node; and

forwarding the system information to a second network node,

39. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

forwarding the system information to a second network node,

40. A computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for receiving system information relevant to an inter-site carrier aggregation from a first network node; and code for forwarding the system information to a second network node, wherein upon configuration of the inter-site carrier aggregation, the first network node acts as a slave node and the second network node acts as a master node.

41. An apparatus, comprising:

receiving means for receiving system information relevant to an inter- site carrier aggregation from a first network node; and

forwarding means for forwarding the system information to a second network node,