Patent Publication Number: US-2013237269-A1

Title: Establishing a new wireless link hop

Description:
TECHNICAL FIELD 
     The present invention relates to a method for establishing a new wireless link hop comprising a new wireless node. The present invention is also related to a wireless node configured to operatively implement the method. 
     BACKGROUND 
     Wireless communication links are well known and widely used in various modern communication networks. Wireless communication links are e.g. often used for backhaul communication in modern telecommunication networks. 
     Typically, backhaul communication is communication that may occur between one or several radio access nodes or similar and a core network or core network node or similar in a wireless communication network, and/or between one or several radio access nodes and an access node controller or similar in a wireless communication network, and/or between an access node controller and a core network or core network node or similar of a wireless communication network, and/or between peer nodes in a core network or similar in an wireless communication network. 
     The radio access node may e.g. be a base station such as a eNodeB (eNB) or similar. The access node controller may e.g. be a Base Station Controller (BSC) or a Radio Network Controller (RNC) or similar. The core network may e.g. be the Evolved Packet Core (EPC) or similar. The wireless communication network may e.g. be the Evolved Packet System (EPS) or similar. The eNB, the BSC, the RNC, the EPC and the EPS and similar entities now mentioned are e.g. defined in the specifications provided by the 3 rd  Generation Partnership Project (3GPP, see e.g. www.3gpp.org) 
     A known wireless communication link  10   a  is schematically illustrated in  FIG. 1 . The link  10  comprises two wireless nodes  12  and  14 . The two nodes  12  and  14  are arranged to operatively communicate information between each other via a wireless communication path  16  in one direction only (unidirectional) or in both directions (bidirectional) as illustrated by the two arrow heads in  FIG. 1 . Various wireless communication links comprising two or more wireless nodes are well known to those skilled in the art and there is no need for a detailed description. An example of a known wireless node may e.g. be the MINI-LINK™ TN R4 provided by Ericsson (see e.g. www.ericsson.com). 
     The wireless communication link  10  may be a part of a larger wireless link network comprising several links of the same or similar type as the wireless communication link  10 . The links of a wireless link network are typically connected to each other according to a suitable topology. The link  10  will then represent a single hop or leg of several hops or legs through which an information entity (e.g. a data packet) has to travel before it reaches its destination. 
       FIG. 2   a  is another schematic illustration of the wireless of the communication link hop  10  previously shown in  FIG. 1 . The wireless communication node  12  of the link hop  10  may be seen as a nucleus in any link topology comprising one or more wireless links, such as the wireless link  10 .  FIG. 2   b  is a schematic illustration of a wireless link network  200  comprising the wireless link  10  and a plurality of identical or similar links being operatively connected according to a ring topology.  FIG. 2   c  is a schematic illustration of a wireless link network  300  comprising the link  10   a  and a plurality of identical or similar links being operatively connected according to a tree topology. Naturally, other topologies are clearly conceivable, e.g. a mesh topology, a star topology, a fully connected topology, a line topology or a buss topology or a combination of two or more of these topologies or similar. 
     The link network  200 ,  300  may comprise a network management function  210   a ,  310   a  respectively that is configured to operatively manage and/or control the activities of the wireless link network  200 ,  300  respectively and/or the wireless nodes therein e.g. the nodes  12  and  14 . The network management function  210 ,  310  respectively may e.g. be connected to and/or implemented in any suitable part of the link network  200 ,  300  respectively. For example, the network management function  210 ,  310  respectively may be connected to and/or implemented in a wireless nodes or similar of the network  200 ,  300  respectively. A network management function may communicate with all the wireless nodes in the network being connected to each other according to a suitable topology as indicated above. 
     It is common that modern communication networks such as the 3GPP Evolved Packet System (EPS) or similar are based at least partly on wireless link networks such as the wireless link networks  200  or  300  or similar. Modern communication networks are often rapidly expanded, which thus may require an expansion of the wireless link network of the communication network in question. 
     Typically, a wireless link network or similar is expanded in that a new wireless node is installed and connected to an existing operational wireless node of the link network in question. For example, as can be seen in  FIG. 2   a , a new wireless node  18  may be installed and connected to the existing operational wireless node  12 . Similarly, as can be seen in  FIGS. 2   b  and  2   c  respectively, the link network  200  or  300  may be expanded such that a new wireless node  18  is installed and connected to the existing operational wireless node  12  or similar of the link network  200  or  300  respectively. A new transmission path  17  will then be established enabling the nodes  12  and  18  to operatively communicate information between each in one direction only (unidirectional) or in both directions (bidirectional) in the same or similar manner as described above for transmission path  17 . The two wireless nodes  12  and  18  will then form a new wireless link hop of the same or similar kind as the known wireless link hop  10  described above with reference to  FIG. 1 . 
     However, with the introduction of packet based transport techniques in wireless links, the number of configuration parameters needed to setup a wireless link hop has exploded. The type of parameters range from e.g. Quality of Service (QoS) settings such as priority mapping and queue lengths to link configuration settings (channel etc) etc. etc. 
     Typically, when installing a new wireless link hop, a service technician carries with him an installation order comprising the parameter settings or similar printed out on paper and/or stored in his/hers computer or similar. When configuring the wireless link hop these settings are typically manually entered at each wireless node of the new link hop, or at least at the new wireless node of the new link hop. The configuration may e.g. be done by means of a local configuration tool of some sort. Other solutions may use a pre-configuration of the wireless link and its wireless nodes and/or a configuration at one or both wireless node by means of USB memory or similar. 
     However if the parameter settings or similar are wrong or corrupted and/or if the parameter settings or similar at one wireless node is misaligned with the parameter settings or similar at the other wireless node of the new link hop, then trouble shooting might be time consuming and difficult. For example, the trouble shooting may require repeated and time consuming travelling between the nodes of the new link hop. 
     SUMMARY 
     In view of the above there seems to be a need for improving the installation of new wireless nodes in a wireless link network. 
     At least one improvement and/or advantage has been accomplished according to a first embodiment of the present solution directed to a method for establish a new wireless link hop comprising an operational wireless node and a new wireless node and a new wireless communication path enabling communication between the operational node and the new node. The method may be performed in the new node  18   a  and comprise the actions of receiving a wireless installation signal transmitted from the operational node, which installation signal comprises installation information enabling the new node to establish the wireless path so as to at least provide physical communication between the operational node and the new node, and the actions of finding the installation signal, and the actions of obtaining the installation information from the found installation signal, and the actions of at least establishing physical communication between the operational node and the new node via the wireless path using the received installation information . . . . 
     At least one improvement and/or advantage has been accomplished according to a second embodiment of the present solution directed to a wireless link hop comprising a new wireless node and an operational wireless node. The operational node is configured to operatively transmit a wireless installation signal comprising installation information enabling the new node to establish a wireless path so as to at least provide physical communication between the operational node and the new node. The new node is configured to operatively receive the wireless installation signal transmitted from the operational node, and to operatively find the installation signal, and to operatively obtain the installation information from the found installation signal, and to operatively at least establish physical communication between the operational node and the new node via the wireless path using the received installation information. 
     Further advantages of the present invention and embodiments thereof will appear from the following detailed description of the invention. 
     It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. 
     It should also be emphasised that the actions preformed in the exemplifying methods described and/or claimed herein must not necessarily be executed in the order in which they appear. Moreover, embodiments of the exemplifying methods described and/or claimed herein may comprise fewer steps or additional steps without departing from the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a wireless communication link hop  10  comprising two wireless nodes  12  and  14  communicating via a wireless communication path  16 , 
         FIG. 2   a  is another schematic illustration of the wireless node  12  of the communication link  10  in  FIG. 1 , 
         FIG. 2   b  is a schematic illustration of a wireless link network  200  comprising the link hop  10  and a plurality of identical or similar link hops being operatively connected according to a ring topology, 
         FIG. 2   c  is a schematic illustration of another wireless link network  300  comprising the link hop  10  and a plurality of identical or similar link hops being operatively connected according to a tree topology, 
         FIG. 3  is a schematic illustration of an expansion of an existing operational link hop  10   a  creating a new wireless link hop  10   b  comprising an operational wireless node  12   b  and a new wireless node  18   a,    
         FIG. 4   a  is a schematic illustration of the new wireless node  18   a  according to an embodiment of the present solution, 
         FIG. 4   b  is a schematic illustration of the operational wireless node  12   a  according to an embodiment of the present solution, 
         FIG. 5  is a schematic flowchart illustrating an exemplifying method according to an embodiment of the present invention, 
         FIG. 6  is a schematic sequence diagram illustrating exemplifying methods according to embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Structure of Embodiments 
       FIG. 3  shows a schematic illustration of an exemplifying wireless link network  100  according to an embodiment of the present solution. The wireless link network  100  may in its simplest form comprise a single operational wireless node  12   a . However, the wireless link network  100  shown in  FIG. 3  comprises one existing operational wireless link hop  10   a  that is to be expanded by a new wireless link hop  10   b . The existing link hop  10   a  may comprise two wireless nodes  12   a  and  14   a  configured to operatively communicate information between each other via a wireless communication path  16   a . The link hop  10   a  may be substantially identical to the link hop  10  previously described with reference to  FIG. 1 . Thus, the nodes  12   a  and  14   a  may be substantially identical to the known nodes  12  and  14  respectively. However, node  12   a  and node  14   a  differ from the known node  12  and node  14  respectively in that the node  12   a  and node  14   a  respectively are modified according to embodiments of the present solution as will be further elaborated below. 
     Before proceeding it should be emphasised that the wireless link network  100  may comprise a plurality of wireless link hops such as the operational link hop  10   a  or similar arranged according to a suitable topology or similar. 
     The attention is now directed to the new wireless link hop  10   b  schematically shown in  FIG. 3 . The new wireless link hop  10   b  has been added as an expansion of the existing wireless link hop  10   a  mentioned above. 
     The new wireless link hop  10   b  comprises the operational wireless node  12   a  mentioned above and a new wireless node  18   a . The operational node  12   a  is configured to operatively transmit a wireless installation signal comprising installation information enabling the new node  18   a  to establish a new wireless communication path  17   a  so as to at least provide physical communication between the new node  18   a  and the operational node  12   a . The new node  18   a  is configured to operatively find and obtain the installation signal. The new node  18   a  is configured to operatively at least establish physical communication between the new node  18   a  and the operational node  12   a  via the wireless path  17   a  using the received installation information. 
     It is preferred that the new wireless link hop  10   b  is a Line of Sight (LOS) link. Generally, a LOS link uses electromagnetic radiation wave propagation including light emissions that is allowed to travel substantially undisturbed in a straight line. Typically, LOS links use highly directional antennas. The directional antennas are then typically arranged such that the antenna lobe of a first antenna (e.g. at node  12   a ) points at a second antenna (e.g. a node  18   a ), and such the antenna lobe of the second antenna points at the first antenna. The lobe of the antennas may e.g. extend less than 10°, or less than 5°, or less than 3° in the vertical and the horizontal direction, or at least in the horizontal direction. The concept of LOS may be thought of as the ability of a human located at a receiving antenna to visually see the transmitting antenna. It is also preferred that the wireless link hop  10   b  is a fixed link hop. Thus, the wireless nodes  12   a  and  18   a  are preferably fixed and aligned with respect to each other and they are preferably not configured to be moved or transported. 
     The wireless nodes  12   a  and  18   a  of the wireless link hop  10   b  are arranged to operatively communicate information between each other via the new wireless communication path  17   a , in one direction only (unidirectional) or in both directions (bidirectional) as illustrated by the two arrow heads in  FIG. 3 . The information may e.g. be communicated via the transmission path  17   a  by means of a microwave signal, e.g. utilizing microwaves above 1 GHz, or above 6 GHz or above 30 GHz, or above 50 GHz including suitable forms of light. Any suitable modulation scheme or similar may be used for conveying information between the wireless nodes  12   a ,  18   a  via the wireless transmission path  17   a , e.g. modulations schemes such as Amplitude Modulation (AM), Single Sideband (SSB), Quadrature Amplitude Modulation (QAM), Frequency Modulation (FM), Phase Modulation or similar, and/or modulation schemes such as Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM) or similar, and/or spread spectrum modulation such as various code modulation schemes or similar. Various combinations of the modulation schemes now mentioned may also be conceivable. 
       FIG. 4   a  is a schematic illustration of the new wireless node  18   a  according to an embodiment of the present solution. The new node  18   a  may comprise a directional antenna unit  19   a  and a transceiver unit  19   b  which are configured to operatively receive and/or transmit information from and/or to the operational wireless node  12   a  or similar via the wireless path  17   a . The antenna unit  19   a  and a transceiver unit  19   b  are particularly configured to operatively receive the wireless installation signal transmitted by the operational node  12   a . The node  18   a  may also comprise a local interface unit  19   c  configured to operatively communicate information between the node  18   a  and a first equipment  32  connected to the node  18   a , e.g. via a local communication link  32  as indicated in  FIG. 3 . The local communication link  23  may e.g. be a wired communication network, e.g. such as the Ethernet or similar, e.g. using copper or optical fiber for the communication. The node  18   a  may also comprise an obtaining unit  19   e  that is configured to operatively find the wireless installation signal transmitted by the operational node  12   a  and to obtain information comprised by the wireless installation signal as will be further described later. In addition, the node  18   a  may comprise an establishing unit  19   f  that is configured to operatively establish communication with the operational node  12   a  via the wireless path  17   a  as will be described later. The node  18   a  may also comprise a control unit  19   d  that is configured to operatively manage and/or control the activities of the antenna unit  19   a , the transceiver unit  19   b , the interface unit  19   c , the obtaining unit  19   e  and the establishing unit  19   f.    
       FIG. 4   b  is a schematic illustration of the existing operational wireless node  12   a  according to an embodiment of the present solution. The operational wireless node  12   a  may be identical to or substantially identical to the new wireless node  18   a  described above. Thus, the operational node  12   a  may at least comprise a directional antenna unit  13   a  and a transceiver unit  13   b  in the same or similar manner as node  18   a . Node  12   a  may also comprise a local interface unit  13   c  configured to operatively communicate information between node  18   a  and a second equipment  42  connected to node  12   a  as indicated in  FIG. 3 . The second equipment  42  may e.g. be directly or substantially directly connected to node  12   a , or connected via one or more networks, e.g. comprising a wireless link network comprising additional wireless nodes, e.g. such as node  14   a  mentioned above. In addition, node  12   a  may comprise an installation unit  13   d  that is configured to operatively manage the transmission of the wireless installation signal and the installation information comprised by the installation signal as will be elaborated in more detail later. The management performed by the installation unit  13   d  may e.g. comprise the actions of obtaining, receiving and/or selecting information indicative of the appropriate properties for the wireless installation signal (e.g. frequency and/or modulation etc) and/or the appropriate installation information to be carried by the installation signal. Node  12   a  may also comprise a control unit  13   e  that is configured to operatively manage and/or control the activities of said units  13   a ,  13   b ,  13   c  and  13   d . The attention is now directed to the first equipment  32  mention above in connection with the new wireless node  18   a  in  FIGS. 3 and 4   a . The first equipment  32  may e.g. be a radio base station, e.g. a radio base station in a cellular telecommunication network, e.g. such as a 3GPP eNodeB or similar. Alternatively, the first equipment  32  may be a network node or similar, e.g. such as a server or a router or similar. Alternatively, the first equipment  32  may be a core node (CN) in a communication network or similar. The core node may e.g. be a 3GPP core node, e.g. such as a Base Station Controller (BSC), a Radio Network Controller (RNC), a Serving GPRS Node (SGSN) or a Serving Gateway (SGW) or similar. 
     The description of the first equipment  32  made above applies mutatis mutandis to the second equipment  42  mention above in connection with the operational node  12   a  in  FIGS. 3 and 4   b . Thus, the second equipment  42  may be a radio base station or similar communicating with the first equipment  32  via the wireless nodes  12   a  and  18   a . The second equipment  42  may e.g. be a radio base station in a cellular telecommunication network, e.g. such as a 3GPP eNodeB or similar. Indeed, both equipments  32  and  42  may e.g. be eNodeBs that communicate via an X2 interface that is fully or at least partly implemented by the wireless nodes  12   a  and  18   a  as described herein. Alternatively, the second equipment  42  may be a network node or similar e.g. such as a server or a router or similar. Alternatively, the second equipment  42  may be a core node (CN) in a communication network  40  or similar. The communication network  40  may e.g. be a cellular communication network. The core node may e.g. be a 3GPP core node, e.g. such as a Base Station Controller (BSC), a Radio Network Controller (RNC), a Serving GPRS Node (SGSN) or a Serving Gateway (SGW) or similar. 
     From the discussion above it can be concluded that it is particularly preferred that node  18   a —using units  19   a ,  19   b ,  19   c ,  19   d ,  19   e  and/or  19   f  or similar—is configured to operatively convey information from the first equipment  32  to the second equipment  42  via node  12   a . Similarly, it is particularly preferred that node  18   a —using units  19   a ,  19   b ,  19   c ,  19   d  and/or  19   e  or similar—is configured to operatively receive information from the second equipment  42  via node  12   a  and to convey this information further to the first equipment  32 . It is also preferred that node  12   a —using units  13   a ,  13   b ,  13   c ,  13   d  and/or  13   e  or similar—is configured to operatively convey information between the first equipment  32  and the second equipment  42  via node  18   a  in the same or similar manner as now described for node  18   a.    
     From the discussion above it can also be concluded that the new wireless link hop  10   b  may be a backhaul communication link hop, e.g. conveying communication between one or several radio access nodes or similar and a core network or core network node or similar in a wireless communication network, and/or between one or several radio access nodes and an access node controller or similar in a wireless communication network, and/or between an access node controller and a core network or core network node or similar of a wireless communication network, and/or between peer nodes in a core network or similar in an wireless communication network. 
     Before proceeding it should be clarified that, as can be seen in  FIG. 3 , the operational wireless node  12   a  may be connected to a network management function  44  configured to operatively manage and/or control activities of the operational wireless node  12   a  according to embodiments of the present solution. The network management function  44  may e.g. be a part of the wireless node  12   a  or the communication network  40  or similar. The network management function  44  may e.g. be an Operation and Maintenance (OAM) function or similar. The OAM may be a functional entity from which the network operator monitors and controls the wireless link network  100 . The OAM may e.g. offer the network operator support for centralized, regional, and local operational and maintenance activities. The OAM may e.g. administrate the commercial operation related to such features as subscription, end terminals, charging and statistics, security management, network configuration, operation and performance management and/or maintenance tasks etc. The network management function  44  may communicate with all the wireless nodes  12   a  and  14   a  etc in the wireless link network  100 , which nodes may be connected to each other according to a suitable topology as indicated in the background section with reference to  FIGS. 2   a - 2   c . It is preferred that the network management function  44  is configured to operatively provide the operational wireless node  12   a  with at least a part of the information comprised by the installation signal transmitted by node  12   a  to node  18   a  as will be described in more detail below reference to  FIG. 5  and  FIG. 6 . 
     Before turning to  FIG. 5  and  FIG. 6  and a discussion of the function of embodiments of the present solution something should be said about the wireless installation signal that is operatively transmitted by the operational wireless node  12   a  and operatively received by the new wireless node  18   a . The wireless installation signal may comprise information indicating that the signal is in fact an installation signal. This may e.g. be accomplished by transmitting at a predetermined frequency and/or according to a predetermined modulation scheme or similar and/or according to a predetermined bit-pattern or similar and/or by transmitting a predetermined frame pattern and/or frame structure or similar. The frequency, the modulation scheme, the bit-pattern, the frame pattern and/or the frame structure or similar to expect may be known by the new node  18   a . This enables the node  18   a  to find the installation signal and to obtain information comprised by the installation signal. Transmitted frames may e.g. comprise frame synchronisation information enabling the receiving new node  18   a  to perform frame synchronization—i.e. to identify incoming frame alignment signals, i.e. distinctive bit sequences (e.g. synchronization words) that are distinguished from data bits—permitting the data bits within the frames to be extracted for decoding by the new node  18   a.    
     It is preferred that the installation signal comprises installation information. The installation information may comprise information that enables the new node  18   a  to establish the wireless path  17   a  between the operational node  12   a  and the new node  18   a  so as to at least provide physical communication between the nodes  12   a  and  18   a.    
     To provide physical communication it may be sufficient if the installation information comprises information indicative of the radio parameters that the new node  18   a  shall use with respect to the operational node  12   a  during reception and/or transmission. The radio parameters may e.g. indicate the transmission and/or receiving frequency or frequencies to be used by the new node  18   a . In addition, the radio parameters may e.g. indicate the modulation scheme or schemes to be used by the new node  18   a  during transmission and/or reception. 
     Physical communication in a very simple form may e.g. correspond to transmission and no transmission, i.e. similar to a Morse code communication. 
     Physical communication in a more advanced form may require that the installation information of the installation signal enables the new node  18   a  to establish communication with node  12   a  via the wireless path  17   a  at least according to layer 1 “Physical Layer” of the Open Systems Interconnection model (OSI-model) and possibly also according to layer 2 “Data Link” of the OSI-model. 
     The installation information may also enable the new node  18   a  to establish further communication with node  12   a  via the wireless path  17   a , e.g. so as to enable payload communication (i.e. payload data) to be communicated or conveyed between node  12   a  and node  18   a  as will be elaborated further later under actions S 1 -S 9 . Payload communication is typically the data that is carried within a transmission unit, e.g. within a data packet or similar as is well known to those skilled in the art. Typically, the payload data does not include the overhead data of the transmission unit required to transport the transmission unit to its destination. Typically, payload data is the data that is delivered to the end user at the destination indicated by the overhead data of the transmission unit in question. 
     Establishing payload communication between nodes  12   a  and  18   a  may e.g. require that the installation information of the installation signal enables the new node  18   a  to establish link payload communication between node  12   a  and node  18   a  via the wireless path  17   a . A link payload communication may e.g. be established according to layer 2 “Data Link” of the OSI-model or similar or according to the first layer “Link Layer” of the Internet Protocol Suit (i.e. the TCP/IP suit) or similar. It is preferred that the link payload communication is communicated between node  12   a  and node  18   a  via the wireless path  17   a  such that the link payload communication is terminated in node  12   a  and/or in node  18   a . Thus, it is preferred that the link payload communication is not conveyed transparently or substantially transparently by the new wireless hop  10   b.    
     In addition, establishing payload communication between nodes  12   a  and  18   a  may e.g. require that the installation information of the installation signal enables the new node  18   a  to establish transit payload communication that is conveyed via node  12   a  and node  18   a  and the wireless path  17   a  according to all or substantially all layers of the OSI-model or the TCP/IP suit. For example, the installation information may enable node  18   a  to establish communication with node  12   a  via the wireless path  17   a  according to layer 3 “Network Layer” of the OSI-model and preferably also at least according to layer 4 “Transport Layer” of the OSI-model. Similarly, the installation information may enable node  18   a  to establish communication with node  12   a  via the wireless path  17   a  according the second layer “Internet” of the TCP/IP suit and preferably also at least according to the third layer “Transport” or even the fourth layer “Application” of the TCP/IP suit. It is preferred that the transit payload communication is conveyed between node  12   a  and node  18   a  via the wireless path  17   a  of the new wireless hop  10   b  on behalf of end-users, e.g. end-users such as the first equipment  32  and the second equipment  42  previously described with reference to  FIG. 3 . Thus, the transit payload communication is preferably not terminated in node  12   a  or in node  18   a . On the contrary, the transit payload communication is preferably transparently or substantially transparently conveyed by the new wireless hop  10   b  between the first equipment  32  connected to the new node  18   a  and the second equipment  42  connected to the operational node  12   a.    
     It should be clarified that the installation information discussed above may be delivered in at a single action (e.g. at the beginning of the installation of the new node  18   a ). 
     Alternatively, the installation information may be delivered at one or more subsequent actions (e.g. after one or more requests from the new node  18   a ). 
     Function of Embodiments 
     The attention is now directed to the flowchart in  FIG. 5  and the sequence diagram in  FIG. 6  illustrating the operation of exemplifying embodiments of the present solution. 
     Action S 1   
     In this action S 1  it is presumed that the existing operational wireless node  12   a  transmits a wireless installation signal comprising installation information. The installation signal is received by the new wireless node  18   a . This presumes that the directional antenna  19   a  of the new node  18   a  is directed towards the operational node  12   a  to enabling the new node  18   a  to receive the installation signal transmitted by the operational node  12   a . Naturally, this also presumes that the new node  18   a  has been powered up and that the directional antenna unit  19   a  and the transceiver unit  19   b  are operational. 
     Before proceeding it should be emphasised that the mere reception of the transmitted installation signal does not necessarily imply that the installation signal is actually found by the new node  18   a . For example, the new node  18   a  may continue scanning a frequency band within which the installation signal is transmitted even if the installation signal was temporarily received. 
     It is preferred that the installation information comprises by the received installation signal at least enables the new wireless node  18   a  to establish physical communication between the operational node  12   a  and the new node  18   a  via the wireless path  17   a.    
     However, in other embodiments of the present solution the operational node  12   a  may already in action S 1  transmit a wireless installation signal with installation information that enables the new wireless node  18   a  to establish payload communication between node  12   a  and node  18   a  as will be elaborated later under actions S 4 -S 9 . 
     The installation information comprised by the transmitted installation signal may be stored in the operational node  12   a  itself before transmission. For example, the installation information may be pre-stored, preloaded or preconfigured or similar in the operational node  12   a . Alternatively, the installation information or at least parts thereof may be provided by the network management function  44  to the operational node  12   a  according to a sub-action S 1   a  or similar of action S 1 . 
     It is preferred that the operational node  12   a  is set to an installation mode in action S 1 . It is preferred that the installation mode causes node  12   a  to transmit the wireless installation signal comprising the installation information. The operational node  12   a  may be set to installation mode locally, e.g. by a technician visiting the operational node  12   a . Alternatively, the operational node  12   a  may be set to installation mode remotely, e.g. by the network management function  44  sending installation mode instructions to node  12   a . The installation mode is preferably temporary, e.g. only lasting until sufficient communication abilities have been established between node  12   a  and node  18   a  via the wireless path  17   a , e.g. until a sufficient physical communication or sufficient payload communication has been established as previously described. The operational node  12   a  may be taken out of installation mode locally by a technician or remotely by the network management function  44  or similar. Alternatively, operational node  12   a  may terminate the installation mode itself, e.g. when the operational node  12   a  detects that sufficient physical communication or sufficient payload communication has been established. 
     Action S 2   
     In this action S 2  the new wireless node  18   a  finds the wireless installation signal transmitted by the operational node  12   a  and received by the new node  18   a  in action S 1 . 
     As already indicated under action S 1 , a reception of the transmitted installation signal does not mean that the installation signal is found by the new node  18   a . For example, node  18   a  may continue scanning a frequency band within which the installation signal is transmitted even if the installation signal was temporarily received. 
     It is preferred that the new wireless node  18   a  remains in a receiving state while the wireless installation signal is received and found. In other words, it is preferred that the new node  18   a  does not transmit during action S 1  and S 2 . 
     Wireless nodes in a link hop such as node  12   a  and node  18   a  in the new link hop  10   a  are typically not allowed to transmit outside a particular frequency band or similar. Thus, it is preferred that the installation information indicates an allowed frequency band or similar to be used by the new node  18   a  for transmissions. This enables the new node  18  to establish communication with node  12   a  via the wireless path  17  while only transmitting within the allowed transmitting frequency band or similar as indicated by the installation information. If the opposite situation occurs, i.e. if the new node  18   a  tries to establish communication with the operational node  12   a  without knowing the allowed frequency band there is an evident risk that the new node  18   a  will transmit outside the allowed frequency band while trying to retrieve installation information and/or while establishing communication with node  12   a  via the wireless path  17   a . This is typically not allowed in wireless link networks and/or wireless link hops, particularly not in publicly deployed link networks and/or link hops. 
     Before proceeding it should be emphasised that a frequency band typically comprise many frequencies, e.g. from X to Y MHz, or from X to Y GHz or similar. However, nothing precludes that a frequency band only comprises a single frequency or only a few frequencies or similar, e.g. X MHz, or X MHz and Y MHz, or X GHz, or X GHz and Y GHz or similar. Similarly, a frequency band may comprise several sub-bands. A frequency band may e.g. comprise a first sub-band from X to Y MHz and a second sub-band from P to S MHz etc. 
     The attention is now directed to the finding of the transmitted installation signal by the new node  18   a . A person skilled in the art having the benefit of this disclosure realises that the new node  18   a  may find the transmitted installation signal in many different ways. For example, the new node  18   a  may find the transmitted installation signal by receiving all signals transmitted on a predetermined frequency or similar or within a predetermined frequency band, e.g. by scanning the predetermined frequency band. 
     As already explained above, to facilitate a finding of the installation signal it is preferred that the installation signal comprises information indicating that the installation signal is in fact an installation signal. This makes it possible for the new node  18   a  to decode the received installation signal and to recognise the installation signal as an installation signal. Thus, this makes it possible for the new node  18   a  to distinguish the installation signal from other signals that may be received by the new node  18   a . The other signals may e.g. be transmitted by other wireless nodes or similar or even by the operational node  12   a.    
     The properties of the transmitted installation signal enabling the new node  18   a  to find the installation signal is preferably known to the new node  18   a . For example, information indicating the properties of the installation signal may be stored in the new node  18   a , e.g. be pre-stored, preloaded or preconfigured or similar in the new node  18   a . The stored information may e.g. indicate the radio parameters or similar of the transmitted installation, e.g. indicate the frequency and/or modulation scheme or similar and/or bit-pattern or similar and/or frame pattern and/or frame structure or similar that is used by the installation signal to indicate that the installation signal is in fact an installation signal. 
     Action S 3   
     In this action S 3  the new wireless node  18   a  obtains the installation information comprised by the wireless installation signal received in action S 1  and found in action S 2  by the new wireless node  18   a.    
     It is preferred that the new node  18   a  remains in a receiving state while the installation information comprised by the installation signal is received, found and obtained. In other words, it is preferred that the new node  18   a  does not transmit during action S 1 , S 2  and S 3 . This is preferred for the reasons as given above when discussing action S 2 . 
     The attention is now directed to the obtaining of the installation information from the received installation signal by the new node  18   a . A person skilled in the art having the benefit of this disclosure realises that the new node  18   a  may obtain the installation information from the received installation signal in many different ways. For example, the transmitted and received installation signal may comprise frames and frame synchronisation information enabling the receiving new node  18   a  to perform frame synchronization—i.e. to identify incoming frame alignment signals, i.e. distinctive bit sequences (e.g. synchronization words) that are distinguished from data bits. This permits the new node  18   a  to extract and decode the data bits and/or bytes or similar representing the installation information within the frames transmitted by the installation signal. 
     Action S 4   
     In this action S 4  the new wireless node  18   a  communicates with the operational node  12   a  so as to at least establish physical communication with the operational node  12   a  via the wireless path  17   a  by using the installation information obtained from the installation signal in action S 3 . 
     As already indicated above, physical communication may be established in a very simple form may e.g. correspond to transmission and no transmission. In that case it may be sufficient if the installation information comprises information indicative of the radio parameters that the new node  18   a  shall operatively use during reception and/or transmission. The new node  18   a  will then establish physical communication with the operational node  12   a  by simply transmit and/or receive according to the indicated radio parameters, e.g. transmit and/or receive at a frequency or frequencies or similar indicated by the parameters, and possibly also according to a modulation scheme or schemes or similar indicated by the parameters. 
     More advanced physical communication may require that the installation information enables the new node  18   a  to establish communication with the operational node  12   a  via the wireless path  17   a  according to layer 1 “Physical Layer” of the OSI-model and possibly also according to layer 2 “Data Link” of the 051-model or similar. The new node  18   a  will then establish physical communication with the operational node  12   a  according to layer 1 of the OSI-model or similar, and possibly also according to layer 2 of the OSI-model or similar as indicated by the installation information. Various suitable methods for establishing layer 1 and layer 2 of the OSI-model or similar between various wireless link nodes are well known to those skilled in the art. In addition, the precise manner of establishing layer 1 and layer 2 of the OSI-model or similar between the wireless link nodes  12   a  and  18   a  is not crucial for embodiments of the present solution. Thus, there is no need for a detailed description of the precise manner of establishing layer 1 and layer 2 of the OSI-model or similar between the wireless link nodes  12   a  and  18   a.    
     As already indicated when discussing action S 1 , in other embodiments of the present solution the operational node  12   a  may transmit a wireless installation signal comprising installation information that enables the new wireless node  18   a  to also establish payload communication between node  12   a  and node  18   a . In that case it is preferred that payload communication is also established in this action S 4 , e.g. as is elaborated below under actions S 6  and S 8 . 
     Action S 5   
     In this action S 5  the new wireless node  18   a  may obtain further installation information from the operational node  12   a  via the wireless communication path  17   a  established in action S 4  (at least physical communication). 
     This action S 5  may be performed to the extent the installation information obtained in the third action S 3  was not sufficient to enable and cause the new node  18   a  to at least establish link payload communication with the operational node  12   a  via the wireless communication path  17   a . As explained above, it is preferred that link payload communication is communicated between node  12   a  and node  18   a  via the wireless path  17   a  such that the link payload communication is terminated in node  12   a  and/or in node  18   a.    
     In this action S 5  it is preferred that the new node  18   a  sends a request to node  12   a  requesting such payload installation information that at least enables the new node  18   a  to establish link payload communication with node  12   a  via the wireless path  17   a . It is also preferred that the new node  18   a  receives a response from node  12   a  comprising such payload installation information that at least enables the new node  18   a  to establish link payload communication with node  12   a  via the wireless path  17   a.    
     The payload installation information provided by the response may be stored in the operational node  12   a  itself. For example, the payload installation information may be pre-stored, preloaded or preconfigured or similar in the operational node  12   a.    
     Alternatively, the payload installation information may be provided by the network management function  44  to the operational node  12   a.    
     In other embodiments of the present solution the new node  18   a  may also request and receive transit payload installation information from the operational node  12   a  in this action S 5 , which transit payload installation information enables the new wireless node  18   a  to establish transit payload communication between node  12   a  and node  18   a  as will be described below under action S 8 . 
     Action S 6   
     In this action S 6  the new wireless node  18   a  may at least establish link payload communication with the operational node  12   a  via the wireless communication path  17   a  according to the installation information obtained in action S 5 . 
     This action S 6  may be performed to the extent installation information is obtained in action S 5 . 
     It is preferred that the installation information enables the new node  18   a  to at least establish link payload communication with the operational node  12   a  via the wireless path  17   a  such that the payload communication is terminated in the operational node  12   a  and/or in the new node  18   a . This may e.g. be accomplished by installation information comprising the unique Media Access Control address (i.e. the MAC-address) or similar of the two nodes  12   a  and  18   a  respectively enabling the new node  18   a  to establish terminating payload communication with the operational node  12   a  via the wireless path  17   a . This may also be done by installation information comprising information that enables the new node  18   a  to establish communication with the operational node  12   a  according to layer 2 “Data Link” and possibly also layer 3 “Network” of the OSI-model or similar, or according to the first layer “Link” layer of the TCP/IP suit or similar. The new node  18   a  will then establish link payload communication with the operational node  12   a  according to the installation information. 
     Establishing layer 2 and layer 3 of the OSI-model or the “Link” layer of the TCP/IP suit between various wireless link nodes are well known to those skilled in the art. In addition, the precise manner of establishing terminating payload communication between the wireless link nodes  12   a  and  18   a  is not crucial for embodiments of the present solution. Thus, there is no need for a detailed description of the precise manner of establishing terminating payload communication between the wireless link nodes  12   a  and  18   a.    
     In some embodiments of the present solution the operational node  12   a  may transmit a wireless installation signal comprising installation information that enables the new wireless node  18   a  to also establish transit payload communication between node  12   a  and node  18   a . In that case it is preferred that transit payload communication is also established in this action S 6 , e.g. as is elaborated below under action S 8 . 
     Action S 7   
     In this action S 7  the new wireless node  18   a  may obtain further installation information with the operational node  12   a  via the wireless communication path  17   a  established in action S 4  (at least physically communication) and in action S 6  (at least link payload communication). 
     This action S 7  may be performed to the extent the installation information obtained in the action S 3  and action S 5  was not sufficient to enable and cause the new node  18   a  to at least establish transit payload communication with the operational node  12   a  via the wireless communication path  17   a . As has already been explained above, it is preferred that transit payload communication is conveyed between node  12   a  and node  18   a  via the wireless path  17   a  of the new wireless hop  10   b  on behalf of end-users, e.g. end-users such as the first equipment  32  and the second equipment  42  previously described with reference to  FIG. 3 . Thus, transit payload communication is preferably not terminated in node  12   a  or in node  18   a.    
     In this action S 7  it is preferred that the new node  18   a  sends a request to node  12   a  requesting such payload installation information that enables the new node  18   a  to establish transit payload communication with node  12   a  via the wireless path  17   a . It is also preferred that the new node  18   a  receives a response from node  12   a  comprising such payload installation information that enables the new node  18   a  to establish transit payload communication with node  12   a  via the wireless path  17   a.    
     The payload installation information provided by the response may be stored in the operational node  12   a  itself. For example, the payload installation information may be pre-stored, preloaded or preconfigured or similar in the operational node  12   a . Alternatively, the payload installation information may be provided by the network management function  44  to the operational node  12   a.    
     Action S 8   
     In this action S 8  the new wireless node  18   a  may establish transit payload communication with the operational node  12   a  via the wireless communication path  17   a  according to the installation information obtained in action S 7 . 
     This action S 8  may be performed to the extent installation information is obtained in action S 7 . 
     It is preferred that the installation information enables the new node  18   a  to establish transit payload communication with the operational node  12   a  via the wireless path  17   a  such that the payload communication can be conveyed between node  12   a  and node  18   a  via the wireless path  17   a  on behalf of end-users. This may e.g. be accomplished by installation information comprising information that enables the new node  18   a  to establish communication with the operational node  12   a  via the wireless path  17   a  according to layer 3 “Network” and possibly layer 4 “Transport” or even higher layers of the OSI-model or similar, or according to the second layer “Internet” or possibly the third layer “Transport” or even higher layers of the TCP/IP suit or similar. The new node  18   a  will then establish link payload communication with the operational node  12   a  according to the installation information. 
     Establishing layer 3 and higher layers of the OSI-model or the “Network” layer or higher layers of the TCP/IP suit between various wireless link nodes are well known to those skilled in the art. In addition, the precise manner of establishing transit payload communication via the wireless link nodes  12   a  and  18   a  is not crucial for embodiments of the present solution. Thus, there is no need for a detailed description of the precise manner of establishing transit payload communication between the wireless link nodes  12   a  and  18   a.    
     Action S 9   
     In this action S 9  transit transit payload communication is operatively conveyed between node  12   a  and node  18   a  via the wireless path  17   a  of the new wireless hop  10   b  on behalf of end-users, e.g. end-users such as the first equipment  32  and the second equipment  42  previously described with reference to  FIG. 3 . 
     The embodiments indicated above may be summarized in the following manner: 
     One embodiment of the present solution is directed to a method for establish a new wireless link hop  10   b . The new wireless link hop  10   b  comprises an operational wireless node  12   a  and a new wireless node  18   a  and a new wireless communication path  17   a  enabling communication between the operational node  12   a  and the new node  18   a . The method may be performed in the new node  18   a  and it may comprise the actions of receiving S 1  a wireless installation signal transmitted from the operational node. It is preferred that the installation signal comprises installation information enabling the new node to establish the wireless path so as to at least provide physical communication between the operational node  12   a  and the new node  18   a . The method may also comprise the actions of finding S 2  the installation signal, and obtaining S 2  the installation information from the found installation signal, and at least establishing S 3  physical communication between the operational node  12   a  and the new node  18   a  via the wireless path  17   a  using the received installation information. 
     It is preferred that the new node  18   a  remains in a receiving state during the receiving, finding and obtaining actions. As indicated above, no transmissions during the receiving, finding and obtaining actions ensures that transmissions are made only within the allowed frequency band once the new node  18   a  starts transmitting. 
     Establishing S 3  of the physical communication via the wireless path  17   a  may comprise the action of establishing S 3  a physical communication on a frequency band determined by the new node  18   a  based on the information obtained from the received installation signal. 
     Receiving the wireless installation signal may comprise the action of receiving signals within a predetermined frequency band. 
     Finding the installation signal may comprise the action of determine whether a received signal is an installation signal. 
     The method may comprise the actions of obtaining from the operational node  12   a  further installation information enabling the new node  18   a  to establish the wireless path  17   a  such that at least terminating payload communication can be conveyed between the operational node  12   a  and the new node  18   a , and the actions of at least establishing terminating payload communication between the operational node and the new node  18   a  via the wireless path  17   a.    
     The method may comprising the actions of obtaining from the operational node  12   a  further installation information enabling the new node  18   a  to establish the wireless path  17   a  such that transit payload communication can be conveyed between the operational node  12   a  and the new node  18   a , and the actions of establishing transit payload communication between the operational node  12   a  and the new node  18   a  via the wireless path  17   a.    
     The obtaining of further installation information form the operational node  12   a  may comprise the actions of sending a request to the operational node  12   a  requesting further installation information enabling the new node  18   a  to establish the wireless path  17   a  such that at least terminating payload communication can be conveyed between the operational node  12   a  and the new node  18   a . The obtaining may also comprise the actions of receiving the requested installation information form the operational node  12   a.    
     The request may comprises information indicative of the identity of the new node  18   a  and/or the identity of the first equipment  32  enabling the operational node  12   a  and/or the network management function  44  to select and transmit installation information that is particularly suited for the new node  18   a  and/or the first equipment  32 . 
     The operational node  12   a  may be controlled by a network management function  44  transmitting to the operational node  12   a  at least a part of the physical properties of the installation signal and/or at least a part of the installation information to be transmitted by the operational node  12   a  to the new node  18   a.    
     Another embodiment of the present solution is directed to a wireless link hop  10   b  comprising a new wireless node  18   a  and an operational wireless node  12   a . The operational node  12   a  is configured to operatively transmit a wireless installation signal comprising installation information enabling the new node  18   a  to establish a wireless path  17   a  so as to at least provide physical communication between the operational node  12   a  and the new node  18   a . The new node  18   a  is configured to operatively receive S 1   b  the wireless installation signal transmitted from the operational node  12   a . The new node  18   a  is configured to operatively find the installation signal. The new node  18   a  is configured to operatively obtain the installation information from the found installation signal. The new node  18   a  is configured to operatively at least establish physical communication between the operational node  12   a  and the new node  18   a  via the wireless path  17   a  using the received installation information. 
     The new node  18   a  may be configured to operatively remain in a receiving state during the receiving, finding and obtaining. 
     The new node  18   a  may be configured to operatively establish a physical communication with the operational node  12   a  via the wireless path  17   a  on a frequency band being determined by the new node  18   a  based on the information obtained from the received installation signal. 
     The new node  18   a  may be configured to operatively receive the wireless installation by receiving signals within a predetermined frequency band. 
     The new node  18   a  may be configured to operatively find the installation signal by determine whether a received signal is an installation signal. 
     The new node  18   a  may be configured to operatively obtain from the operational node  12   a  further installation information enabling the new node  18   a  to establish the wireless path  17   a  such that at least terminating payload communication can be conveyed between the operational node  12   a  and the new node  18   a , and to operatively at least establish terminating payload communication between the operational node  12   a  and the new node  18   a  via the wireless path  17   a.    
     The new node  18   a  may be configured to operatively obtain from the operational node  12   a  further installation information enabling the new node  18   a  to establish the wireless path  17   a  such that transit payload communication can be conveyed between the operational node  12   a  and the new node  18   a , and to operatively establish transit payload communication between the operational node  12   a  and the new node  18   a  via the wireless path  17   a.    
     The further installation information may be obtained form the operational node  12   a  by the new node  18   a  being configured to operatively send a request to the operational node  12   a  requesting further installation information enabling the new node  18   a  to establish the wireless path  17   a  such that at least terminating payload communication can be conveyed between the operational node  12   a  and the new node  18   a , and to operatively receive the requested installation information form the operational node  12   a.    
     The new node  18   a  may be configured to operatively send the request such that the request comprises information indicative of the identity of the new node  18   a  and/or the identity of the first equipment  32  enabling the operational node  12   a  and/or the network management function  44  to select and transmit installation information that is particularly suited for the new node  18   a  and/or the first equipment  32 . 
     The present invention has now been described with reference to exemplifying embodiments. However, the invention is not limited to the embodiments described herein. On the contrary, the full extent of the invention is only determined by the scope of the appended claims.