Patent Publication Number: US-2013237230-A1

Title: Reconfiguring a Base Station for Handover in Relay-Enhanced Communication Network

Description:
FIELD 
     The invention relates generally to mobile communication networks. More particularly, the invention relates to automatically reconfiguring eNBs in order to allow the reconfigured eNB to serve as a donor eNB in a relay-enhanced communication network. 
     BACKGROUND 
     In radio communication networks, such as the Long Term Evolution (LTE) or the LTE-Advanced (LTE-A) of the 3 rd  Generation Partnership Project (3GPP), network deployment comprises the use of base stations (such as a Node B (NB), or an evolved Node B(eNB)). However, it may be that the coverage areas of the eNBs are insufficient to enable certain user equipments (UE) to communicate properly with any eNB. In order to enable the UE to communicate, the network deployment may be extended by so called relay nodes. 
     In relay-enhanced communication networks, the transmission may occur from a transmitter to a receiver via a relay node, also known as a relay station. The relay node (RN) may be placed in a cell of the eNB in order to extend the coverage area of the eNB and to increase the capacity/throughput of the cell. Further, the RN may increase the capacity at shadowed areas in the cell as well as in the locations where the traffic demand is high such as in airports or other hot spots, for example. In addition, the RN may be applied to reduce the average radio transmission power of the user equipment attached to the relay node. 
     The RN must be connected to a certain eNB, called a donor eNB (DeNB). For an eNB to act as the DeNB, the eNB must be properly configured. When the RN desires to connect to an eNB which is not properly configured, problems may occur. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Embodiments of the invention seek to enable the self-organized upgrade of the base station to serve as the donor base station in the relay-enhanced communication network. According to an aspect of the invention, there are provided methods as specified in claims  1  and  10 . 
     According to an aspect of the invention, there are provided apparatuses as specified in claims  12 ,  21 ,  23 , and  24 . According to an aspect of the invention, there are provided computer program products as specified in claims  25  and  26 . Embodiments of the invention are defined in the dependent claims. 
    
    
     
       LIST OF DRAWINGS 
       In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which 
         FIG. 1  presents a communication network; 
         FIG. 2  shows a relay-enhanced communication network according to an embodiment; 
         FIGS. 3A ,  3 B and  3 C show communication between a relay node, base station and a centralized network element, according to embodiments; 
         FIG. 4  illustrates apparatuses capable of performing in the relay-enhanced communication network, according to an embodiment; 
         FIG. 5  illustrates a method for reconfiguring a base station in the relay-enhanced communication network, according to an embodiment; and 
         FIG. 6  illustrates a method for reconfiguring a base station in the relay-enhanced communication network, according to an embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. 
     Radio communication networks, such as the Long Term Evolution (LTE) or the LTE-Advanced (LTE-A) of the 3 rd  Generation Partnership Project (3GPP), are typically composed of at least one base station (also called a base transceiver station, a Node B, or an evolved Node B, for example), a user equipment (also called a user terminal and a mobile station, for example) and optional network elements that provide the interconnection towards the core network. The base station connects the UEs via the so-called radio interface to the network. 
       FIG. 1  shows a communication network. As explained, the communication network may comprise a base station  102 . The base station  102  may provide radio coverage to a cell  100 , control radio resource allocation, perform data and control signaling, etc. The cell  100  may be a macrocell, a microcell, or any other type of cell where radio coverage is present. Further, the cell  100  may be of any size or form, depending on the antenna system utilized. 
     In general, a base station  102  applicable to the embodiments may be configured to provide communication services according to at least one of the following communication protocols: Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Telecommunication System (UMTS) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), LTE, and/or LTE-A. The base station  102  may additionally provide the second generation cellular services based on GSM (Global System for Mobile communications) and/or GPRS (General Packet Radio Service). The present embodiments are not, however, limited to these technologies. 
     The base station  102  may be used in order to provide radio coverage to the cell  100 . The base station  102  may be seen as one communication point of the network. The base station  102  may be node B, evolved node B (eNB) as in LTE-A, a central node, or any other apparatus capable of controlling radio communication and managing radio resources within the cell  100 . The base station  102  may also have an effect on mobility management by controlling and analyzing radio signal level measurements performed by a user terminal, carrying out its own measurements and performing handover based on the measurements. 
     For the sake of simplicity of the description, let us assume that the base station is an eNB. The evolved universal mobile telecommunication&#39;s system (UMTS) terrestrial radio access network (E-UTRAN), which comprises the air interface of the LTE, is concentrated on the eNB  102 . All radio functionality is terminated here so that the eNB  102  is the terminating point for all radio related protocols. The E-UTRAN may be configured such that orthogonal frequency division multiple access (OFDMA) is applied in downlink transmission, whereas single carrier frequency division multiple access (SC-FDMA) may be applied in uplink, for example. In the case of multiple eNBs in the communication network, the eNBs may be connected to each other with an X2 interface as specified in the LTE. 
     The eNB  102  may be further connected via an S1 interface to an evolved packet core (EPC)  110 , more specifically to a mobility management entity (MME) and to a system architecture evolution gateway (SAE-GW). The MME handles/terminates the control plane for controlling functions of non-access stratum signal-ing, roaming, authentication, tracking area list management, etc., whereas the SAE-GW handles user plane functions including packet routing and forward-ing, E-UTRAN idle mode packet buffering, etc. The user plane bypasses the MME plane directly to the SAE-GW. The SAE-GW may comprise two separate gateways: a serving gateway (S-GW) and a packet data network gateway (P-GW). The MME controls the tunneling between the eNB and the S-GW, which serves as a local anchor point for the mobility between different eNBs, for ex-ample. The S-GW may relay the data between the eNB and the P-GW, or buffer data packets if needed so as to release them after appropriate tunneling has been established to a corresponding eNB. Further, the MMES and the SAE-GWs may be pooled so that a set of MMES and SAE-GWs may be as-signed to serve a set of eNBs. This means that an eNB may be connected to multiple MMES and SAE-GWs, although each user terminal is served by one MME and/or S-GW at a time. 
     According to an embodiment, the eNB  102  may establish a connection with a user equipment (UE)  108 A to  108 D such as a mobile user terminal, a palm computer, or any other apparatus capable of operating in a mobile communication network. That is, the UE  108 A to  108 D may perform data communication with the eNB  102 . 
     When the UE  108 A to  108 D is out of reach of the eNB  102 , it may be advisable to implement relay nodes to the network.  FIG. 2  illustrates a relay enhanced communication network, according to an embodiment, in which an eNB  202  provides radio coverage to a cell  200 . In addition there are one or more relay nodes (RN)  204  in the cell for enhancing the coverage/capacity of the cell  202 . A UE  206  may thus communicate with the eNB  202  via the RN  204 . 
     The link  208  between the eNB  202  and the RN  204  may be called a relay link or a backhaul link, and the link  210  between the RN  204  and the UE  206  may be called an access link. Although not shown in  FIG. 2 , the eNB  202  may also serve additional UEs via a direct link between the eNB  202  and each of the served UEs. 
     There are various relay transmission schemes that can be employed. In an amplify-and-forward protocol an amplify-and-forward relay node first receives a signal from the source node, then scales the power of the signal up or down and finally forwards the signal towards a target. Another exemplary relaying protocol applies selective decode-and-forward method, in which the received data at the relay node is decoded and re-transmitted to the target only if the data is correctly received through cyclic redundancy check or a similar error detecting code. A demodulate-and-forward relay scheme performs a hard decision of the received, demodulated, symbol at the relay node at a first phase and then modulates and forwards the data to the target. 
     It may be that the eNB  202  is not the most optimal eNB to use in the data communication in terms of radio channel conditions, for example. However, in the original network planning, the eNB  202  may have been set as the only eNB in the area that is capable of co-operating with a relay node as the donor eNB. 
     Let us assume that there is an eNB  212  in the network of  FIG. 2 . The eNB  212  may provide radio coverage to the same cell  200  or to another cell which is possibly overlapping the cell  200 . This eNB  212  may provide, for example, better radio communication conditions to the relay node  206  than the eNB  202 . The radio communication conditions may characterize radio propagation channel between the RN  204  and the eNB  202  and/or the eNB  212 . Therefore, it may be advisable to use this eNB  212  as the donor eNB (DeNB) instead of connecting to the eNB  202  that offers poor radio conditions to/from the RN  204 . However, due to the original network planning, this may not be possible as the eNB  212  is not configured to perform functionalities required when co-operating with a relay node. That is, based on the original network planning, the RN  204  may connect only to the eNB  202  that already comprises the required DeNB functionalities for the co-operation. These functionalities may comprise, for example, proxy functionalities and gateway-like functionalities. The proxy functionalities allow hiding the RNs  204  from MMEs/GWs serving the UEs. That is, the RN  204  is seen as a new cell under the DeNB (eNB). The DeNB appears to the RN  204  as an MME (S1 interface) and as an eNB (X2 interface). The gateway-like functionalities comprise creating sessions or managing evolved packet system (EPS) bearers for the RN  204 . In other words, these functionalities are needed from an eNB in order for the eNB to be a DeNB and to co-operate with the relay node. 
     It may be that the RNs are not considered in the initial network planning (roll-out), but are interesting to network operators for enhancing the network later, because they are simple and cost-effective. Therefore, in the initial roll-out phase eNBs are not necessarily configured as DeNBs, at least not all of the eNBs  202  and  212 . In the assumed example, when the relay node  204  prefers to co-operate with the eNB  212  as shown with a dotted line in  FIG. 2 , the eNB  212  may have to be upgraded (reconfigured) to be able to perform the functionalities as required from a DeNB (eNB). This type of re-configuration may result in quite a lot of effort with respect to at least the following aspects: a new planning phase may need to be launched to determine the best serving eNB, which may in turn require that the detailed position of the RN has to be known in advance and also the details of the radio propagation environment between the RN and the existing eNBs, including small scale effects due to buildings, trees, etc, need to be known. 
     As the RNs provide an efficient solution to enhance the network, it may be advisable that any upgrade, extension or replacement of hardware requires minimal operator attention. Therefore, it is advantageous to perform the possible reconfiguration automatically. This type of self-organizing network (SON), where the reconfiguration is performed automatically without any operator attention and any re-planning of the communication network, may result in that the relay nodes may be set up in a plug and play-manner. This automated process eliminates the need for manually upgrading (or planning) the eNB to DeNB prior to the RN deployment. 
     Accordingly, there is provided a self-organized upgrade of an eNB  212  to comprise the functionalities as required from a DeNB. In an embodiment, the relay node  204  selects a base station  212  to co-operate with, wherein the selection is made among at least one base station  202  and  212  on the basis of available radio channel conditions. The relay node  204  may measure the condition of the radio channel to each of the at least one base station  202 ,  212  and perform the selection on the basis of the measurement performed. The radio channel condition characterizes the propagation channel between the relay node  204  and the corresponding eNB  202 / 212 . The measurement may take the shadowing and small-scale fading between the RN  204  and the eNB  202 / 212  into account. The measurement of the radio channel condition may be made by the RN  204  in the same way as a user equipment in the communication network typically measures the received signal power strength when deciding which eNB to connect to, for example. In this sense, when the RN  204  is switched on, it will behave like an UE looking for best server (an eNB with the best signal strength). The scheme may, however, be generalized to other cell selection criteria taking more aspects into account e.g. interference levels, load at the eNB, expected positions of further relay nodes, etc. 
     Once the RN  204  has selected the eNB  212  to co-operate with, the RN  204  may inform an auto-configuration apparatus (ACA) about a preference of the relay node  204  to co-operate with the selected eNB  212  in order for the auto-configuration apparatus to automatically reconfigure or to initiate the reconfiguration of the selected eNB  212  to serve as the donor eNB when the selected eNB  212  does not currently support serving the relay node as the donor eNB. If the selected eNB  212  already supports relay node co-operation with respect to the DeNB functionalities as described earlier, the auto-configuration apparatus (ACA) need not perform any re-configuration in the relay-enhanced communication network. 
     In an embodiment, the reconfiguration of the eNB  212  is not performed to an eNB already capable of serving the relay node as the donor eNB, but only to an eNB that is not capable of co-operating with a relay node in terms of the above described functionalities. Therefore re-configuring an already performing DeNB for certain specific purpose is not the aim of the reconfiguration. 
     In another embodiment, the RN  204  selects at least one additional base station, wherein the at least two selected base stations  202  and  212  are candidate base stations for co-operation with the relay node  204 . Therefore, a list of possible eNBs that could serve as DeNB may be sent to the ACA. Again, the selection of the candidate eNBs may be based on the available radio channel conditions or the selection may take further aspects into account. The RN  204  may select, for example, four different eNBs which all are suitable for co-operation in terms of sufficiently adequate radio channel conditions. In the exemplary case of  FIG. 2 , the RN  204  may select the eNBs  202  and  212  as the candidate eNB for co-operating with the RN  204 . 
     Consequently, the eNB  204  may inform the ACA of the candidate eNBs  202  and  212  in order to allow the ACA to select which of the candidate eNB  202  and  212  is to serve the RN  204  as the donor eNB, and to automatically reconfigure or initiate the reconfiguration of the selected eNB  212  when the selected eNB  212  does not currently support serving the RN  204  as the donor eNB, assuming that the ACA selected the eNB  212  to be the DeNB for the RN  204 . The selection at the ACA may be based on at least one of the following reasons related to the at least two selected eNB  202  and  212 : indicated radio channel conditions, a current traffic situation, expected positions of further relay nodes, and original network planning. That is, in this example, the RN  204  may have indicated the measured radio channel conditions to the ACA so that the ACA may perform a sophisticated selection. The indication may inform the ACA what the quality of the link to the different eNBs  202 ,  212  is, in order to allow the ACA to prefer those eNBs with better links. Moreover, the ACA may be aware of the current traffic (load) situation in the relay-enhanced network. The ACA may also know if certain eNBs are reserved for some specific purposes which prevent those eNBs to be reconfigured as DeNB. In the simplest case however the ACA may not get any such supporting information and still may decide to reconfigure at least one of those eNBs, e.g. based on the number of RNs in the area. When taking the existing RNs or expectations of future RNs to be deployed in the area into account, the ACA may take care that preferably such an eNB is upgraded that can be expected to later also serve other RNs which are expected to be deployed. In this way the number of required future updates and associated cost can be reduced. The base station may have knowledge of the expected locations of further relay nodes as part of the original network deployment information, or it may obtain the knowledge from other network elements, operators, etc. 
     As the ACA may be aware of at least these reasons for selection, the ACA my prioritize the current traffic situation and the original network planning over the indicated radio channel conditions when selecting which of the candidate base stations is to serve the relay node. That is, when the eNB  212  with the best available radio channel condition is, for example, a legacy eNB that does not allow to be upgraded, or the eNB  212  is heavily loaded with traffic (either on the air interface or the backhaul), the ACA may not select the eNB  212  (which has the best radio channel conditions) but select the eNB  202  (which does not have the best, yet adequate, radio channel properties) to be the DeNB for the RN  204 . If the eNB  202  is already capable of performing as the DeNB, no reconfiguration is needed. 
     Let us take a look at how the informing of the preference to co-operate with a certain eNB to the ACA may take place. In embodiments of  FIGS. 3A ,  3 B and  3 C, the RN  302  has selected the eNB to co-operate with or provided information that allows another entity to select that eNB. As a consequence, the ACA  306  ( 306 A,  306 B, or  306 C) is informed accordingly of this. 
     In  FIG. 3A , the selected eNB  300  receives this information about a preference of the relay node  302  to co-operate with a selected base station  300 . This may happen so that the RN  302  uses the air interface  304  of selected eNB  300  to send a message to the ACA  306 A. The message may also contain an indication that the sender of the message is a relay node  302  (not a UE). In the example of  FIG. 3A , the ACA  306 A locates at the selected eNB  300 . Consequently, the ACA  306 A may then automatically reconfigure or initiate the re-configuration of the selected base station  300  when the selected base station  300  does not currently support serving the relay node  302  as the donor eNB. In other words, the selected base station  300  may automatically reconfigure itself to serve as the donor eNB in the relay-enhanced communication network. This may take place so that the ACA performs the re-configuration of the selected base station  300 , or so that it initiates the reconfiguration process by informing the selected base station  300  to trigger reconfiguration. When the reconfiguration is completed, data communication over the relay link  308  may take place. As the base station  300  now comprises the functionalities as required from a donor base station, the base station  300  may serve any relay node in the relay-enhanced communication network, not only the RN  302  making the co-operation request. 
     In  FIG. 3B , the auto-configuration apparatus  306 B locates at another network element  310  than the selected base station  300 . The other network element (NE)  310  may be a centralized element in the network, such as a network management system (NMS) element, an operational support system (OSS) element, or an operation and maintenance element (O&amp;M). Alternatively, the other network element  310  may be another eNB other than the selected one. 
     As the ACA  306 B does not locate in the selected eNB  300 , the RN  302  may directly inform the ACA  306 B of the preference to co-operate with the selected base station  300  via a communication link  312 B. The link  312 B may be for example a logical link which may physically go via the eNB  300 . Alternatively, the RN  302  may via communication links  312 A (between the RN  302  and the selected eNB  300 ) and  314  (between the eNB  300  and the NE  310 ) indirectly inform the ACA  306 B that the RN  302  desires to co-operate with the eNB  300 . After the ACA  306 B receives the information, it may decide to re-configure or initiate the reconfiguration of the selected eNB  300  when the selected eNB  300  does not currently support serving the RN  302  as the donor eNB. The signaling needed for the reconfiguration may be transmitted via a link  316 . That is, the reconfiguration may be triggered not by the eNB  300  itself but by another network entity  310 . When the reconfiguration is completed, data communication over the relay link  308  may take place. 
     As the RN  302  may not have to communicate with the eNB  300  before the reconfiguration, the RN  302  may not send an indication that it is a RN (not a UE) to the to-be-DeNB  300  but directly or indirectly to the NE  310 . This allows a more centralized and coordinated approach of performing the reconfigurations. The eNB in this case may be unaware why it is being reconfigured (upgraded)). The advantage of this approach is that then the eNB  300  may not have to implement any additional features to support its upgrade to DeNB. The processing at the eNB  300  may be decreased as the eNB  300  itself does not need to decide whether to perform the reconfiguration or not. 
     In  FIG. 3C , there are two NEs  318  and  320 , one  318  for the RN  302  and another  320  for the to-be-DeNB  300 . In an embodiment, the RN  302  may inform its own NE  318  via a link  322  about the preference to co-operate with the selected eNB  300 . It may be that the NE  318  connected to the RN  302  is incapable to perform the reconfiguration of the eNB  300 . Thus, information related to the selected base station  300  may be exchanged with the other network element  320 , when the NE  318  is incapable of reconfiguring the selected base station  300 , thereby allowing the other network element  320  to reconfigure the selected base station  300 . This way, the NE  320  with an ACA  306 C receives information via communication link  324  regarding which eNB  300  is to be upgraded to obtain DeNB functionalities. For example, the identification of the eNB  300  can be sent from the NE  318  to the NE  320 . The NE  320  may then trigger/perform the reconfiguration via a link  326 . When the reconfiguration of the eNB  300  is completed, data communication over the relay link  308  may take place. 
     When the ACA is not located at the selected eNB but in the other network element  310 , as is the case in the example of  FIG. 3B , for example, the ACA  306 B may receive information of at least one additional base station, wherein the at least two selected base stations are candidate base stations for co-operation with the relay node  302 . That is, the ACA  306 B may receive a list of candidate eNBs, wherein the relay node  302  plans to co-operate with one of the candidate eNBs but the RN  302  leaves the final selection to the ACA. Then the ACA  306 B may select which of the candidate base stations is to serve the relay node as the donor eNB on the basis of at least one of the following reasons (grounds) reflated to the at least two selected base stations: indicated radio channel conditions, a current traffic situation, expected positions of further relay nodes, and original network planning, as discussed above. In selection process, the ACA  306 B may apply the prioritization as discussed above. After the selection the ACA  306 B may automatically reconfigure or initiate the reconfiguration of the selected base station when the selected base station does not currently support serving the relay node  302  as the donor eNB. 
     In an embodiment, the ACA  306 A,  306 B,  306 C (from now on commonly referred to as  306 ), may reconfigure the selected base station  300 , wherein the reconfiguration may comprise at least one of the following: updating a software of the selected base station, re-parameterizing the configuration of the selected base station, activating a license to the software, assigning a new physical cell identity to the selected base station, updating a tracking area of the selected base station, and adjusting antenna orientation of the selected base station. 
     The updated software allows the eNB  300  to perform the functionalities required from a DeNB. These include the proxy functionalities and the gateway-like functionalities, as described earlier. The software may be updated by the ACA or the software update may be initiated by the ACA, e.g. the software may then be downloaded by the eNB itself or uploaded by another apparatus. After the software has been updated, a license for the software may need to be activated. In an embodiment, the license activation may even be required if the software does not need to be updated as the initial software release already does support relaying. In an embodiment, the ACA  306  may verify that the reconfiguration of the selected base station  300  is allowed with respect to licenses. In this sense, the reconfiguration is conditional depending on an authorization with respect to licenses. The verification may be obtained from a license manager apparatus, for example. The license manager apparatus may locate in a centralized unit, such as in the O&amp;M, for example. The ACA  306  may then restrain from the reconfiguration if the reconfiguration is not allowed. This is advantageous in order for operators to inhibit some eNBs to be upgraded to DeNBs. The reason for such may be to have only a subset of the eNBs available for performing as DeNB. The motivation behind this may be to save license costs, for example. 
     As part of the reconfiguration, a re-parameterization of the configuration of the selected base station may be useful. For example, some memory that may otherwise be used for data buffers may need to be set aside to keep information regarding the served relay nodes. Furthermore, the ACA  306  may give the DeNB a new physical cell identity (PCI) so that the co-operating RN  302  may use that PCI in order to be seen as new cell. The tracking areas of the DeNB may need to be updated. The reconfiguration of the eNB  300  may also comprise adjusting the eNB&#39;s  300  antenna orientation, such as tilt values of the antenna. The purpose of this re-orientation may aim at making sure that the RN  302  is within the main beam of the eNB  300 . As this depends on the location of the RN  302 , and in particular on the height above ground where the relay is deployed, a change in a tilt value (a lower tilt or a higher tilt), and/or possibly a change in the azimuth angle of the antenna may be beneficial depending on the exact location of the RN  302  with respect to the location of the eNB  300 . Typically relays are deployed at a higher altitude than normal subscribers are. For example, when deployed on a typical lamp post, the deployment altitude may be above 5 m, whereas typical altitude of a hand held device may be 1.5 m. Therefore, tilt values of the to-be-DeNB that were optimized originally for the handheld devices may need to be revised. 
     In an embodiment, the ACA  306  may inform the relay node  302  to restrain from the co-operation with the selected base station until the reconfiguration of the selected base station is compete. This may be advantageous because the upgrade of the eNB  300  to obtain the functionalities of a DeNB may take some time, during which the RN  302  may not connect to it as a RN. The time may be needed for downloading new software or licenses or performing other reconfigurations. The time to wait may also be longer than the time required to do the actual reconfiguration if the latter is deferred to a later time, e.g. to be performed during times of low traffic over night. Then it may be beneficial to inform the relay node  302  when the relay node  302  may attempt to co-operate with the selected base station  300 . Otherwise the RN  302  may select the next-best eNB, thus possibly creating a sub-optimal setup. The point of time when the RN  302  may try to co-operate with the to-be-DeNB  300  may be indicated as a specific time instant, a given time period during which co-operation may be attempted, or the RN  302  may be instructed to try the co-operation periodically. As a further embodiment, the RN  302  may after some attempts give up and connect to another (next best) eNB, for example. 
     In an embodiment, there is provided a solution against fake RNs attempting to connect to the eNB  300 . When the ACA locates in the selected eNB  300  or the selected eNB  300  itself requests for reconfiguration of the selected eNB  300 , the selected eNB  300  is gradually reconfigured so that the selected eNB  300  is first enabled to obtain knowledge of identification (ID) of at least one RN  302  in the relay-enhanced communication network. The identification and possibly verification of the identity of a RN may be done solely by the eNB  300  or in co-operation with other network elements, e.g. the MME or other core network elements. Thus, at this point only a part of the software of the eNB  300  may be updated instead of performing the reconfiguration of eNB to DeNB completely, wherein the updated part of the software contains information enabling the verification of the identities or IDs of the RNs  302  in the network. Typically, the functionality of knowing the IDs is considered to be a functionality of the MME. For this reason, this part of the software of the eNB  300  may be updated to enable this MME functionality or to co-operate with the MME accordingly. This part of the reconfiguration process may be done for each co-operation attempt from a RN, regardless whether the attempting RN is later found to be a fake RN or a valid (genuine) RN. 
     Thereafter, the eNB  300  may analyze the ID of the relay node  302  attempting to co-operate with the selected eNB  300  in order to verify that the RN  302  is a valid relay node in the relay-enhanced communication network. When the relay node is considered to be invalid, the eNB  300  is not reconfigured any further and the request from the RN  302  to co-operate with the eNB  300  is rejected. However, only when the ID of the RN  302  is a valid ID implying that the RN  302  is a genuine (valid) relay node, the reconfiguration of the eNB  300  is completed. This may take place by updating the rest of the modules of the eNB  300  in order for the eNB  300  to work fully as a DeNB. The rest of the modules that may be upgraded at this point typically comprise a much bigger part of the reconfiguration process than only the updating of the module allowing the ID verification. Thus, those RNs that are not genuine (valid) relay nodes do not trigger the complete re-configuration. This is beneficial so that major part of the reconfiguration process is not done when fake RNs attempt to connect the eNB  300 . Furthermore, this may result in saving in the license costs as well, because eNBs are not updated to DeNB for fake RNs. 
     Alternatively, each eNB  300  in the relay-enhanced communication network which are not yet DeNBs but which are able to upgrade themselves or are able to being upgraded, if needed, may be updated at least for the part allowing the eNB  300  to understand the information from the relay node attempting to co-operate, wherein the information relates to the identification of the relay node. That is, instead of updating part of the software for only those eNB that receive indication of co-operation attempt, the update may be performed for every eNB in the network. The identification by the RN may be given in the form of an international mobile subscriber identity (IMSI), or in the form of an international mobile equipment identification (IMEI), for example. Once the eNB knows the IDs of the RNs in the network, it may restrain from triggering the reconfiguration when the RN is found to be a fake RN. On the other hand, for co-operation attempts from genuine RNs, the reconfiguration process may be started. 
     When the update is triggered via a centralized network element,  310  or  320 , the centralized NE  310 ,  320  may include the check for genuine RNs in a similar way. The centralized NE  310 ,  320  may already have the knowledge needed to differentiate fake RNs from valid RNs. 
     In an embodiment, the ACA may receive information of at least one additional base station. Thus, the ACA receives information of at least two selected base stations. Each of the selected at least two eNBs are to co-operatively serve the RN as DeNBs. This may be the case, for example, in a soft handover, in a co-operative interference management, or in a co-operating transmission/reception where several eNBs co-operate to at least some extent to serve the RN. Then the ACA may automatically reconfigure or initiate the reconfiguration of at least one of the at least two selected eNBs to serve as the DeNB when the at least one of the at least two selected eNBs does not currently support serving the RN as the DeNB, wherein the reconfiguration of an eNB takes into account the functionalities required from the eNB when co-operatively serving the RN. 
     Thus, the ACA may decide to reconfigure only those parts of the eNB that need to be upgraded when the eNB is serving the RN in co-operation with at least one other eNB. This is advantageous so that each eNB need not be reconfigured in the same way. One eNB may require reconfiguration of several functionalities whereas another eNB may require reconfiguration of only a few functionalities. Thus, time is saved because the reconfiguration of an eNB is adapted to the needs of the eNB individually. The functionalities of the other co-operative eNBs are taken into account when determining which functionalities are needed from the eNB under the reconfiguration process. For example, when handover takes place, the functionalities required from a target DeNB may be different than the functionalities required from a source DeNB. 
     After at least one eNB has been reconfigured to DeNB in the relay-enhanced communication network, the ACA may perform reconfiguration of the relay-enhanced communication network. The reconfiguration of the network may comprise that radio- and transport-configurations of eNBs and DeNBs are adapted or generated. The ACA responsible may be located at the centralized network element (such as at the O&amp;M) or at the base station (such as at the eNB). 
     Very general architectures of apparatuses according to embodiments are shown in  FIG. 4 .  FIG. 4  shows only the elements and functional entities required for understanding the apparatuses. Other components have been omitted for reasons of simplicity. The implementation of the elements and functional entities may vary from that shown in  FIG. 4 . The connections shown in  FIG. 4  are logical connections, and the actual physical connections may be different. The connections can be direct or indirect and there can merely be a functional relationship between components. It is apparent to a person skilled in the art that the apparatuses may also comprise other functions and structures. 
     The apparatus  400  for co-operation in the relay-enhanced communication network may comprise a processor  402 . The processor  402  may be implemented with a separate digital signal processor provided with suitable software embedded on a computer readable medium, or with a separate logic circuit, such as an application specific integrated circuit (ASIC). The processor  402  may comprise an interface, such as computer port, for providing communication capabilities. The processor  402  may be, for example, a dual-core processor or a multiple-core processor. 
     The apparatus  400  may comprise a memory  404  connected to the processor  402 . However, memory may also be integrated to the processor  402  and, thus, no memory  404  may be required. The memory  404  may be used in storing information related to the reconfiguration process, such as which parts of the software need to be updated, license related information, etc. The memory may also store information related to the original network planning phase, such as identity of any legacy eNBs. The apparatus  400  may further comprise a transceiver (TRX)  406 . The TRX  406  may further be connected to one or more antennas  408  enabling connection to and from an air interface. The interface  406  may receive information from a relay node, wherein the information describes that the RN desires to co-operate with certain candidate eNB. The TRX  406  may also be used sending information to the RN to postpone the co-operation with the selected eNB, or to another network entity, when the current apparatus  400  is incapable of performing the reconfiguration of the selected eNB. 
     The processor  402  may comprise a radio control circuitry  410  for performing radio control related activities, such as radio resource management, radio access control, etc. The radio control circuitry  410  may also perform measurements related to the traffic situation in the communication network, for example. The radio control circuitry  410  may also perform selection of an eNB among the indicated candidate eNBs, wherein the selected eNB is to be reconfigured to obtain the DeNB functionalities. When doing the selection, prioritization between criteria for selection may take place, as described earlier. 
     The processor  402  may comprise a reconfiguration circuitry  412  for automatically performing or initiating the reconfiguration of an eNB so that after the reconfiguration the eNB may obtain functionalities which are required from a donor eNB when co-operating with a relay node in the relay-enhanced communication network. As the reconfiguration is performed automatically, there is no user/operator interaction needed for the reconfiguration. The reconfiguration circuitry  412  may perform the configuration process gradually. This may be due to the fact that a verification whether the RN is a valid RN may need to be performed first before the reconfiguration is completed. The verification may be performed by the radio control circuitry  410 , for example. 
     The apparatus  420  for co-operation in the relay-enhanced communication network may comprise a processor  422 . The processor  422  may be implemented with a separate digital signal processor provided with suitable software embedded on a computer readable medium, or with a separate logic circuit, such as an application specific integrated circuit (ASIC). The processor  422  may comprise an interface, such as computer port, for providing communication capabilities. The processor  422  may be, for example, a dual-core processor or a multiple-core processor. 
     The apparatus  420  may comprise a memory  424  connected to the processor  422 . However, memory may also be integrated to the processor  422  and, thus, no memory  424  may be required. The memory  424  may be used in storing information related to the selection process, such as which eNBs are selected as the candidate eNBs for the co-operation. 
     The apparatus  420  may further comprise a transceiver (TRX)  426 . The TRX  426  may further be connected to one or more antennas  428  enabling connection to and from an air interface. The interface  426  may transmit information, either directly or indirectly, to an auto configuration apparatus (ACA), wherein the information indicates the selected eNB or the selected candidate eNBs for co-operation. The TRX  426  may also be used in receiving information from the ACA wherein the information may indicate when the apparatus  420  may try to co-operate with the selected eNB. The TRX may also be used in receiving user-related data and transmitting the user-related data onwards towards the end-receiver, such as receiving data from an eNB/UE and transmitting the data to an UE/eNB, respectively. 
     The processor  422  may comprise a radio control circuitry  430  for performing radio control related activities, such as received signal power strength measurements, access control to connecting UEs, etc. 
     The processor  422  may comprise a selection circuitry  432  for performing the selection of the eNB with which to co-operate on the basis of the measurement results, for example. The selection circuitry may also select at least one additional eNB so that the selected at least two eNBs serve as candidate eNBs for the co-operation between the apparatus  420  and one of the candidate eNBs. 
     The apparatus  400  may be the auto configuration apparatus. The apparatus  400  may locate at a base station, at a centralized network element, such as a O&amp;M, NMS, for example. The apparatus  420  may be located in a relay node, for example. As used in this application, the term ‘circuitry’ refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of circuits and software (and/or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s)/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. 
     This definition of ‘circuitry’ applies to all uses of this term in this application. As a further example, as used in this application, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and/or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device. 
       FIG. 5  shows a method for reconfiguring a base station in a relay enhanced network. The method starts in step  500 . In step  502  the method comprises receiving information of candidate eNBs to co-operate with. This may comprise receiving information about a preference of the relay node to co-operate with the selected base station, or receiving information about at least two candidate eNBs for co-operating with the relay node. If this is the case, the apparatus performing the method of  FIG. 5  may select which eNB is to serve the relay node as the donor eNB. The method further comprises in step  504 , automatically reconfiguring or initiating the re-configuration of the selected base station when the selected base station does not currently support serving the relay node as the donor eNB. The method ends in step  506 . 
       FIG. 6  shows a method for reconfiguring a base station in a relay enhanced network. The method starts in step  600 . In step  602  the method comprises selecting candidate eNBs. The number of the selected candidate eNBs may be one or more. Therefore, in one embodiment, the apparatus performing the method of  FIG. 6  may select one base station to co-operate with, wherein the selection is made among at least one base station on the basis of available radio channel condition or other criteria as described above. In step  604 , the method comprises informing an auto-configuration apparatus about the candidate eNBs to co-operate with. The information may be about a preference of the relay node to co-operate with the specific selected base station in order for the auto-configuration apparatus to automatically perform the reconfiguration of the selected base station when the selected base station does not currently support serving the relay node as the donor base station. Alternatively, the information may comprise information of the at least two selected base stations so that the ACA may perform the final selection regarding which eNB is to be updated and to co-operate with the relay node as the donor eNB. The method ends in step  606 . 
     The embodiments of the invention offer many advantages. The embodiments prevent manual RN location detection, manual RN identification and manual configuration of eNBs when an operator deploys RNs in the area. This upgrade functionality is aligned with flexible deployment of the relay nodes. When the RN has been deployed somewhere, for instance mounted on a lamp post, the eNB which is to become the DeNB is setup and reconfigured automatically, if the required functionality is not available in the eNB yet. Further, only those eNBs are upgraded to DeNBs that are actually needed by the deployed RNs. By automating the procedure, the costs for configuration of RNs may be reduced and complex reconfiguration when any eNB changes its role may be avoided. Further, memory that is needed to store modules related for DeNB functionality may not need to be used in the other nodes for this purpose and, thus, may be used for other purposes e.g. for larger data buffers in these nodes 
     The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatuses of  FIG. 4  may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chip set (e.g. procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art. 
     Thus, according to an embodiment, the apparatus for performing the tasks of  FIGS. 1 to 6  comprises interfacing means for receiving, by an auto-configuration apparatus, information about a preference of a relay node to co-operate with a selected base station. The apparatus may further comprise processing means for automatically reconfiguring the selected base station to serve as the donor base station in the relay-enhanced communication network when the selected base station does not currently support serving the relay node as the donor base station. 
     Embodiments of the invention may be implemented as computer programs in the apparatuses according to the embodiments. The computer programs comprise instructions for executing a computer process for improving co-operation between the relay node and the base station in the relay-enhanced communication network. The computer program may carry out, but is not limited to, the tasks related to  FIGS. 1 to 6 . 
     The computer program may be stored on a computer program distribution medium readable by a computer or a processor. The computer program medium may be, for example but not limited to, an electric, magnetic, optical, infrared or semiconductor system, device or transmission medium. The computer program medium may include at least one of the following media: a computer readable medium, a program storage medium, a record medium, a computer readable memory, a random access memory, an erasable programmable read-only memory, a computer readable software distribution package, a computer readable signal, a computer readable telecommunications signal, computer readable printed matter, and a computer readable compressed software package. The computer program may also be downloaded. 
     Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.