WO2018172082A1 - Secondary base station, wireless communication system and method for controlling a secondary base station - Google Patents

Secondary base station, wireless communication system and method for controlling a secondary base station Download PDF

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Publication number
WO2018172082A1
WO2018172082A1 PCT/EP2018/055675 EP2018055675W WO2018172082A1 WO 2018172082 A1 WO2018172082 A1 WO 2018172082A1 EP 2018055675 W EP2018055675 W EP 2018055675W WO 2018172082 A1 WO2018172082 A1 WO 2018172082A1
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WO
WIPO (PCT)
Prior art keywords
base station
secondary base
link
backhaul link
wireless
Prior art date
Application number
PCT/EP2018/055675
Other languages
French (fr)
Inventor
Richard Weiler
Thomas Fehrenbach
Wilhelm Keusgen
Thomas Wiegand
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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Publication of WO2018172082A1 publication Critical patent/WO2018172082A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0203—Power saving arrangements in the radio access network or backbone network of wireless communication networks
    • H04W52/0206—Power saving arrangements in the radio access network or backbone network of wireless communication networks in access points, e.g. base stations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W92/00—Interfaces specially adapted for wireless communication networks
    • H04W92/04—Interfaces between hierarchically different network devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W92/00—Interfaces specially adapted for wireless communication networks
    • H04W92/16—Interfaces between hierarchically similar devices
    • H04W92/20—Interfaces between hierarchically similar devices between access points
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the present invention relates to the field of wireless communication networks, and embodiments relate to wireless communication networks/systems including primary and secondary cells. Embodiments relate to the secondary cells and a control thereof.
  • Fig. 1 is a schematic representation of an example of a wireless network 100 including a core network 102 and a radio access network 104.
  • the radio access network 104 may include a plurality of base stations eNB, to eNB 5 , each serving a specific area surrounding the base station schematically represented by respective cells 106 ! to 106 5 .
  • the base stations are provided to serve users within a cell.
  • a user may be a stationary device or a mobile device.
  • the wireless communication system may be accessed by IoT devices which connect to a base station or to a user.
  • IoT devices may include physical devices, vehicles, buildings and other items having embedded therein electronics, software, sensors, actuators, or the like as well as network connectivity that enable these devices to collect and exchange data across an existing network infrastructure.
  • Fig. 1 shows an exemplary view of only five cells, however, the wireless communication system may include more such cells.
  • Fig. 1 shows two users UE1 and UE2, also referred to as user equipment (UE), that are in cell 106 2 and that are served by base station eNB 2 .
  • Another user UE 3 is shown in cell 106 4 which is served by base station eNB 4 .
  • the arrows 108-1 , 108 2 and 108 3 schematically represent uplink/downlink connections for transmitting data from a user UE,, UE 2 and UE 3 to the base stations eNB 2 , eNB 4 or for transmitting data from the base stations eNB 2 , eNB 4 to the users UE,, UE 2 , UE 3 .
  • Fig. 1 shows two IoT devices 110i and 110 2 in cell 106 4 , which may be stationary or mobile devices.
  • the IoT device 110 accesses the wireless communication system via the base station eNB 4 to receive and transmit data as schematically represented by arrow 112,.
  • the !oT device 110 2 accesses the wireless communication system via the user UE 3 as is schematically represented by arrow 1 2 2 .
  • the respective base station eNB, to eNB 5 are connected to the core network 102 via respective backhaul links 114, to 114 5 , which are schematically represented in Fig. 1 by the arrows pointing to the "core".
  • the core network 102 may be connected to one or more externa! networks.
  • the wireless communication system may be any single-tone or multicarrier system based on frequency-division multiplexing, like the orthogonal frequency-division multiplexing (OFDM) system, the orthogonal frequency-division multiple access (OFDMA) system defined by the LTE standard, or any other IFFT-based signal with or without CP, e.g. DFT- s-OFDM.
  • OFDM orthogonal frequency-division multiplexing
  • OFDMA orthogonal frequency-division multiple access
  • Other waveforms like non-orthogonal waveforms for multiple access, e.g. filter- bank multicarrier (FBMC), generalized frequency division multiplexing (GFDM) or universal filtered multi carrier (UFMC), may be used.
  • FBMC filter- bank multicarrier
  • GFDM generalized frequency division multiplexing
  • UFMC universal filtered multi carrier
  • the radio access network 104 may be a heterogeneous network including a network of primary cells, each including a primary base station, also referred to as a macro base station. Further, a plurality of secondary base stations, also referred to as small cell base stations, may be provided for each of the macro cells.
  • Fig. 2 is a schematic representation of a cell, like cell 1061 in Fig. 1 , having two distinct overlaid networks, the networks comprising a macro cell network including the macro cell 106,, and a small cell network. Although Fig. 2 represents only a single macro cell, it is noted that one or more of the other cells in Fig. 1 may also use the overlaid networks.
  • the smali cell network comprises a plurality of small cell base stations eHB ⁇ to SeNB 5 each operating within a respective area 120i to 120 6 , also referring as the coverage area of the small cell.
  • the small cell base stations SeNE ⁇ to SeNB 5 may be controlled by the macro cell base station MeNBi to which the respective small cell base stations SeNB-i to SeNB 5 are connected via respective backhaul links 122 ⁇ ) to 122 5 .
  • one or more of the small cell base stations may be coupled to the core network via respective backhaul links.
  • Fig. 2 further shows a user equipment UE being served by the macro cell base station Me Bi as indicated by arrow 12 ⁇ and by the small cell base station SeNB ⁇ as indicated schematically by the arrow 124 2 .
  • Fig. 3 is a further schematic representation of a plurality of small cells 120t to 120 3 of a macro cell (not shown).
  • the macro cell may be similar to that in Fig. 2.
  • Each small cell may serve one or more UEs.
  • the respective small cell base stations SeNB ⁇ SeNB 2 , SeNB 3 , .... other than in Fig. 2, are connected via the backhaul links or connections 102i to 02 3 to the core network 102.
  • the respective small cells 102i to 102 3 may be directly connected with each other via the X2 interface, as schematically indicated in Fig. 3.
  • the transport network connecting the respective small cells to the core network 102 may be an optical fiber network including one or more points of presents (PoP) at which a plurality of small cells are connected to the transport network.
  • PoP points of presents
  • the small cells also referred to as secondary mobile communication cells, SCs, form an overlay network to the network of macro cells, also referred to as primary mobile communication ceils, PC.
  • the small cells may be connected via backhaul links (BL) to the macro cell (Fig. 2) and/or to the core network (Fig. 3).
  • the backhaul links may be wired or wireless links, and in case of connecting the small cells via the backhaul links to the core network, the point of presence (PoP) of the transport network (Fig. 3) may serve as an interface to the core network.
  • Each small cell may serve a number of mobile users UE within its coverage area by means of a wireless access link (AL) 124 2 . Further, the UEs may be connected to the primary cell, for example to receive control signals, and the connection may be referred to as a control link (CL).
  • a wireless access link AL 124 2
  • the UEs may be connected to the primary cell, for example to receive control signals, and the connection may be referred to as a control link (CL).
  • the SeNBs may be put to sleep or may be turned off when it is determined that no user is within the coverage area of the small cells.
  • Putting the small cell into the sleep mode includes deactivating the access link so that the small cell may not be directly visible by a UE entering its coverage area.
  • a secondary base station for a communication network is provided which is connected to a core network or to a primary base station of the communication network via a backhaul link.
  • a backhaul link is provided.
  • the secondary base station when the secondary base station is not needed, for example because there is no UE in the coverage area of the small cell, also the backhaul link of the small cell base station is deactivated.
  • the secondary base station when being activated again, will also activate the backhaul link upon its activation.
  • a control channel preferably a low energy channel, may be maintained to allow for the reception of external signals causing the small cell base station to enter into its activated state and to activate the backhaul link so that, once the backhaul link has been re-activated, the small cell base station may be used for serving a UE within a macro cell of which the small cell is part.
  • the inventive approach is advantageous in that turning off the backhaul link, in addition to the access link, all of which require high energy for being sustained, also in a deactivated state, allows saving power and avoids, especially in the case a wireless backhaul link is provided, radio interferences.
  • the overall power consumption of the small cells may be reduced and only a low power signaling is needed to detect and activate the small cell base station when needed. Further, this allows for a quick and flexible activation of deactivated links.
  • Fig. 1 shows a schematic representation of an example of a wireless network including a core network and a radio access network
  • Fig. 2 shows a schematic representation of a cell, like a cell in Fig. 1 , having two distinct overlaid networks, namely a macro cell network including a macro cell and a small cell network including small cell base stations connected via the backhaul links to the macro cell base station;
  • Fig. 3 shows a further schematic representation of a plurality of small cells of a macro cell, similar to Fig. 2, wherein the small cell base stations are connected via the backhaul links to the core network;
  • Fig. 4 shows a schematic representation an arrangement of a macro base station and secondary base stations in accordance with embodiments of the present invention
  • Fig. 5 shows an example for a backhaul activation of a deactivated small cell in accordance with an embodiment of the present invention ... ;
  • Fig. 6 shows an example for a small cell activation in accordance with an embodiment of the present invention including an access link activation;
  • Fig. 7 shows another example for a UE aided small cell activation in accordance with an embodiment of the present invention
  • Fig. 8 shows a schematic representation for the activation of a SC through one or more other small cells in accordance with an embodiment of the present invention
  • Fig. 9 is a schematic representation of a wireless communication system for communicating information between a secondary base station and a UE.
  • Fig. 10 illustrates an example of a computer system on which units or modules as well as the steps of the methods described in accordance with the inventive approach may execute.
  • Fig. 4 is a schematic representation similar to the one of Fig. 2 showing a primary or macro MeNB including, within its coverage area, two secondary or small cell base stations SeNB 2 in accordance with embodiments of the invention.
  • the first small cell base station SeNB- t is in its activated state and serves a user equipment UE within the coverage area 120, of the small cell base station SeNB v
  • the small cell base station SeNBi serves the UE via the access link 124 2 .
  • the UE is connected to the macro base station ⁇ - ⁇ via a control link 124,.
  • the backhaul link 122 of the small cell base station SeNBi is activated.
  • the backhaul link 122-1 is a wireless link to the macro cell base station MeNB v
  • the backhaul link may be a wired link.
  • the backhaul link may not be to the macro cell base station but may be connected to the core network, e.g., via a point of presence of the transport network (see Fig. 3).
  • Fig. 4 shows a deactivated small cell base station SeNB 2 . There is no UE to be served within its coverage area 120 2 .
  • the small cell base station SeNB 2 Upon recognizing such a situation, the small cell base station SeNB 2 enters into a deactivated state in which also the backhaul link is deactivated. Because the backhaul link of the small cell base station SeNB 2 is deactivated, it is not shown in Fig. 4.
  • the small cell base station once a UE enters into the coverage area 120 2 of the small cell base station SeNB 2 , the small cell base station will be activated and the backhaul link, either to the macro cell base station or to the core network, will be activated again so that the small cell base station may serve the UE within its coverage area 120 2 .
  • the connections may be as those described above with reference to the activated small cell base station SeNB,.
  • a small cell which, when being deactivated, provides for improved power savings and improved reductions of interferences because also the backhaul link is deactivated.
  • a control link 130 is provided for the small cell base station, which is a control link separate from the links described above in Fig. 4 with regard to the small cell base stations SeNB,.
  • the control link 130 is schematically shown and may be a wireless or wired control link.
  • the control link 130 is between the small cell base station SeNB 2 and the macro cell base station MeNB,.
  • the control link 130 may be between the small cell base station SeNB 2 and the core network, for example it may be a control link connecting the SeNB 2 to the PoP of the transport network (see Fig. 3).
  • the wireless control link 130 may be used to activate the backhaul link 122, once it is determined that a UE enters the coverage area 120 2 of the small cell base station SeNB 2 .
  • the wireless control channel 130 may be a low rate wireless link, a sensor network interface, a narrow-band beacon link or the like.
  • the wired or wireless control channel may use a frequency band that is within the backhaul link frequency band (in-band control channel) or that is within another frequency band different from the backhaul link frequency band, i.e., an out of band control channel.
  • the control channel may be a low power and/or a low latency channel to receive an external signaling for the small cell base station causing it to be activated and to activate the backhaul link.
  • the small cell backhaul link activation may be initiated by one or more of the following entities:
  • a user terminal UE may send a request to use the SC, for example upon a request of a data transmission,
  • a user terminal UE may act as a relay for the PC (primary cell) or the PoP and may forward a request to activate the SC,
  • the PC base station MeNBi may send a request to the SC to activate the SC backhaul link
  • PoP point of presence
  • another SC in the vicinity may send a request, for example on behalf of the PC.
  • the control link 130 is configured to receive the respective requests from these entities.
  • the connection to the SC is maintained by providing the low power control channel 130 between the SC and the PC or between the SC and the PoP.
  • this connection may be in accordance with different standards, like the NB-IOT standard, the GSM standard, the LTE standard or the 5G/NR standard.
  • Fig. 5 shows an example for a backhaul activation of the deactivated small cell SeNB 2 of Fig. 4 in accordance with an embodiment of the present invention.
  • the small cell base station SeNB 2 has the control channel 130 so as to maintain the connection to the other network entities when being in the deactivated state.
  • the control channel 130 formed of a first control channel 130a connecting the small cell base station SeNB 2 to the macro cell base station Me Bi and/or a second control channel 130b to the point of presence of the transport network of the core network.
  • UE is connected to the macro cell base station MeNBi, as is indicated at ⁇ .
  • Fig. 5 shows a situation in which the UE came into the reach of the SC as is indicated at ⁇ .
  • the MeNBi may signal via the first control channel 130a directly to the SeNB 2 (as indicated at 3a) that is to be activated.
  • the SC will activate the backhaul connection 122 2 .
  • the SC responsive to the signaling 3a on the first control channel 130a, may activate the backhaul link at the SeNB 2 .
  • the macro cell Me Bi may signal, via its backhaul line 114i, to the core 102 that the SC is to be activated, and core 102 causes an activation of the backhaul link at the PoP.
  • the second control channel 130b may be between the SC and the PoP.
  • the macro cell MeNBi signals the presence of the UE close to the SC via its backhaul link 114i to the core 102 which, in turn, causes the PoP to send an activation message to the SC via the second control channel 130b and causes the PoP side of the backhaul link to be activated, while the SC, responsive to the signaling via the second control channel 130b, activates the its backhaul link 122 2 , as is indicated at ⁇ .
  • the wireless control channel may include both channels 130a and 130b shown in Fig. 4, i.e., the control channel may be maintained between the SC and the macro cell base station as well as between the SC and the core network.
  • the signaling to activate the backhaul link 122 is such that after receiving the notice to be activated via the control channel 130a, the SC activates the backhaul link at its end, and signals via the control channel 130b to the PoP to activate the backhaul at its end, for example to activate the transceivers at both ends of the backhaul link.
  • the wireless or wired control link 130 is between the SC and the PC or between the SC and the PoP or between both.
  • the signaling to activate the backhaul link may be received via an access link between the SC and the PC.
  • the access link is like the link 124 2 shown in Fig. 4 via which the UE is connected to the SC.
  • the connection between the SC and the PC may be in accordance with the communication standard used in the communication network, for example the SC may act as a standard terminal device towards the PC, like a LTE terminal or a regular UE, an NB- loT client or the like.
  • the activation of the SC and its backhaul link activation may be initiated by the primary cell which may send a message to the SC directly through the access link or the message may be sent from the point of presence via the PC.
  • the signaling for activating the backhaul link may be received at the SC via an access link 124 (see Fig. 4) being active and connected to a UE using, for example, the LTE standard, or any other access technology.
  • the SC acts as a standard base station towards the connected UE and the access link may be a standard LTE link, a millimeter-wave link or any standard UE link.
  • the backhaul link activation may be initiated by one or more of the following entities:
  • the UE may send a message to the SC, for example in response to a request for a data transmission,
  • the UE may act as a relay for the PC and send a message to the SC,
  • SC may send a message to the SC
  • the UE may relay a message from the PoP to the SC.
  • the SC may be connected to a fixed line network, for example by a radio connection, a visible light connection, an optical fiber connection, a cable connection or a twisted pair connection.
  • the PC may send the activation message to the SC via the fixed line network.
  • the SC may be completely turned off to save power and turned on at predefined time intervals to receive updates.
  • the SC may be operated on a low power control mode and may be contacted by the UE, other SCs or the PC to be activated.
  • the backhaul link activation between the SC and the PoP has been described.
  • a backhaul link between the SC and the eNBi may be activated.
  • the backhaul link of the SC to the PC may be activated via the above described wireless control channel, via the above described access link, or via the above described fixed line link.
  • the SC when being deactivated, may also deactivate its access link so as to save power.
  • the core network may turn on the small cell, for example in case of a location aware core network.
  • the SC may provide a beacon signal using a low power device, and a UE may transmit beacon information received from the SC to the core network.
  • a wired or wireless control channel between the PC and/or the PoP may be maintained by the SC in its deactivated state, and the access link for serving a UE may be activated via this wireless control channel by providing additional signaling also instructing the SC to activate its access link.
  • Fig. 6 shows an example for a small cell activation in accordance with an embodiment of the present invention including an access link activation.
  • the small cell SeNB 2 is deactivated and the UE is assumed coming into its reach, i.e., it is within the coverage area 120 2 .
  • the SeNB 2 is configured to send out a beacon signal, as is indicated at ⁇ that is received by the UE and transmitted via the MeNB, and its backhaul to the core 102, as indicated at ⁇ and ®.
  • the core 102 via the control channel 130, causes the activation of the SC which includes activating the backhaul link 122 2 and the access link 124 2 as is indicated at ⁇ .
  • Fig. 7 shows another example for a UE aided small cell activation in accordance with an embodiment of the present invention.
  • a UE detects the beacon signal from the deactivated SeNB 2 , as is indicated at ⁇ .
  • the SeNB 2 may recognize that the beacon signal has been detected by the UE and starts its activation process which includes sending an activation message for the core network 102 to the UE.
  • the activation message is relayed via the UE and the primary cell Me Bi to the core network 102, as is indicated at ® and ®.
  • the core network 102 activates the backhaul link 122 2 between the core 102 and the small cell SeNB 2 , as indicated at ⁇ and ⁇ , so that the SC SeNB 2 which has been activated is now also connected via its backhaul link 122 2 to the core 102 and, thus, can serve the UE as indicated at ⁇ .
  • the backhaul between the SC and the core may not be a direct backhaul connection, but may be a backhaul link extending through one or more other small cells, as indicated, for example, in Fig. 3 by the X2-interface connection connecting the small cell base stations SeNBi, SeNB 2 and SeNB 3 are connected via a backhaul link X2 to the PoP, i.e., the backhaul link of SeNBi to the PoP is through the SeNB 2 .
  • a backhaul may also be deactivated or turned off to save power, and the wakeup process may be done through a beacon response or a wakeup receiver.
  • the first small cell base station SeNBi has a backhaul link for a connection to the core 102 or to the point of presence, wherein the backhaul link comprises a first link portion 122i between the Se Bi and the other small cell SeNB 2 , and a second portion 122 2 from the other small cell SeNB 2 to the PoP.
  • a UE entering the coverage area of the SeNBi may receive a beacon message from the small ceil, as is indicated at ®.
  • the UE may cause the SC to wake up or to be activated which, in turn, causes the SC to activate its backhaul link 122i towards the other small cell SeNB 2 as indicated at @. Further, an activation message may be sent via the UE and the primary base station MeNBi to the PoP, as indicated at ® and ⁇ so as to cause an activation of the backhaul link 122 2 to the other small cell.
  • the backhaul link for the first SC SeNBi is active, as indicated at ⁇ , and the UE may be served by the SeNBi, as indicated at ⁇ .
  • the activation of the access link between the SC and the UE to be served by the SC may be done via the control channel between the SC and the MC and/or between the SC and the core.
  • the signaling to activate the access link to the UE may be via the backhaul link, once it has been activated.
  • the activation of the access link between the SC and the UE may be signaled via the above-described access link between the small cell and the primary cell or via the above-described fixed line link.
  • the activation of the small cell may be triggered due to a detection that the PC is absent.
  • the SC activates its access link so as to serve one or more UEs within its coverage area and, in addition, via a connection to the core network, for example via the above described control channel between the SC and the PoP, the backhaul connection to the core is established so as to allow the SC to serve the UE.
  • the SC may try to connect other SCs in the vicinity to serve the UE via the neighboring SC, for example to route data from the SC to its neighboring SC and from there to the core network.
  • the SC is connected to the UE over a wireless UE access link and that the SC acts like a base station towards the connected UE using a communication standard, for example the one as is also used in the communication network.
  • the SC may be configured to provide as the access link a device-to-device link, so that, in this configuration, the SC acts to the connected UE as another UE providing for a side link or device-to-device link, like the PC 5 link.
  • the SC may listen to the side link and/or broadcast over the side link so as to recognize, for example, a UE requesting a connection to the small cell base station.
  • the SC may be configured to listen as to whether there is a UE requesting, in response to the beacon message, a connection to the SC.
  • Embodiments of the present invention may be implemented in a wireless communication system as depicted in Fig. 1 , Fig. 2, Fig. 3 or Fig. 4 including primary and secondary base stations and users, like mobile terminals or loT devices.
  • Fig. 9 is a schematic representation of a wireless communication system for communicating information between a secondary base station SeNB and a UE.
  • the secondary base station SeNB may include one or more antennas ANT S8 N B or an antenna array having a plurality of antenna elements, as well as a signal processor/transceiver circuit 202 to process signals to be transmitted/received.
  • the UE may include one or more antennas ANTUE or an antenna array having a plurality of antenna elements, as well as a signal processor/transceiver circuit 204 to process signals to be transmitted/received.
  • signals are communicated between the secondary base station SeNB and the UE via a wireless communication link, like the above described access link (Fig. 4).
  • the wireless communication system may operate in accordance with the techniques described herein. For example, when there is no UE to be served by the secondary base station SeNB, the SeNB may be deactivated. Upon deactivating the SeNB, a backhaul link 208 to the core and/or the MeNB is deactivated.
  • the SeNB When a UE is to be served by the secondary base station SeNB, the SeNB will be activated via an external signaling that may be received via the transceiver. Activating the SeNB includes activating the backhaul link 204. Once activated the SeNB serves the UE.
  • Various elements and features of the present invention may be implemented in hardware using analog and/or digital circuits, in software, through the execution of instructions by one or more general purpose or special-purpose processors, or as a combination of hardware and software.
  • embodiments of the present invention may be implemented in the environment of a computer system or another processing system.
  • Fig. 10 illustrates an example of a computer system 300.
  • the units or modules as well as the steps of the methods performed by these units may execute on one or more computer systems 300.
  • the computer system 300 includes one or more processors 302, like a special purpose or a general purpose digital signal processor.
  • the processor 302 is connected to a communication infrastructure 304, like a bus or a network.
  • the computer system 300 includes a main memory 306, e.g., a random access memory (RAM), and a secondary memory 308, e.g., a hard disk drive and/or a removable storage drive.
  • the secondary memory 308 may allow computer programs or other instructions to be loaded into the computer system 300.
  • the computer system 300 may further include a communications interface 310 to allow software and data to be transferred between computer system 300 and external devices.
  • the communication may be in the form electronic, electromagnetic, optical, or other signals capable of being handled by a communications interface.
  • the communication may use a wire or a cable, fiber optics, a phone line, a cellular phone link, an RF link and other communications channels 312.
  • computer program medium and “computer readable medium” are used to generally refer to tangible storage media such as removable storage units or a hard disk installed in a hard disk drive. These computer program products are means for providing software to the computer system 300.
  • the computer programs also referred to as computer control logic, are stored in main memory 306 and/or secondary memory 308. Computer programs may also be received via the communications interface 310.
  • the computer program when executed, enable the computer system 300 to implement the present invention.
  • the computer program when executed, enable processor 302 to implement the processes of the present invention, such as any of the methods described herein. Accordingly, such a computer program may represent a controller of the computer system 300.
  • the software may be stored in a computer program product and loaded into computer system 300 using a removable storage drive, an interface, like communications interface 310.
  • the implementation in hardware or in software may be performed using a digital storage medium, for example cloud storage, a floppy disk, a DVD, a Blue-Ray, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, having electronically readable control signals stored thereon, which cooperate (or are capable of cooperating) with a programmable computer system such that the respective method is performed. Therefore, the digital storage medium may be computer readable.
  • Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.
  • embodiments of the present invention may be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer.
  • the program code may for example be stored on a machine readable carrier.
  • inventions comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier.
  • an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.
  • a further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein.
  • a further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or the sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet.
  • a further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein.
  • a further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.
  • a programmable logic device for example a field programmable gate array
  • a field programmable gate array may cooperate with a microprocessor in order to perform one of the methods described herein.
  • the methods are preferably performed by any hardware apparatus.

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Abstract

A secondary base station for a communication network having a radio access network and a core network is provided. The radio access network has one or more primary base stations. The secondary base station includes a transceiver for a radio communication with one or more user equipments, and a backhaul link to the core network and/or to the primary base station. The secondary base station is configured to be in a first state in which the backhaul link is activated, or in a second state in which backhaul link is deactivated. The secondary base station is configured to enter the first state responsive to an external signaling, wherein entering the first state includes activating the backhaul link.

Description

SECONDARY BASE STATION, WIRELESS COMMUNICATION SYSTEM AND METHOD FOR CONTROLLING A SECONDARY BASE STATION
Description
The present invention relates to the field of wireless communication networks, and embodiments relate to wireless communication networks/systems including primary and secondary cells. Embodiments relate to the secondary cells and a control thereof.
Fig. 1 is a schematic representation of an example of a wireless network 100 including a core network 102 and a radio access network 104. The radio access network 104 may include a plurality of base stations eNB, to eNB5, each serving a specific area surrounding the base station schematically represented by respective cells 106! to 1065. The base stations are provided to serve users within a cell. A user may be a stationary device or a mobile device. Further, the wireless communication system may be accessed by IoT devices which connect to a base station or to a user. IoT devices may include physical devices, vehicles, buildings and other items having embedded therein electronics, software, sensors, actuators, or the like as well as network connectivity that enable these devices to collect and exchange data across an existing network infrastructure. Fig. 1 shows an exemplary view of only five cells, however, the wireless communication system may include more such cells. Fig. 1 shows two users UE1 and UE2, also referred to as user equipment (UE), that are in cell 1062 and that are served by base station eNB2. Another user UE3 is shown in cell 1064 which is served by base station eNB4. The arrows 108-1 , 1082 and 1083 schematically represent uplink/downlink connections for transmitting data from a user UE,, UE2 and UE3 to the base stations eNB2, eNB4 or for transmitting data from the base stations eNB2, eNB4 to the users UE,, UE2, UE3. Further, Fig. 1 shows two IoT devices 110i and 1102 in cell 1064, which may be stationary or mobile devices. The IoT device 110, accesses the wireless communication system via the base station eNB4 to receive and transmit data as schematically represented by arrow 112,. The !oT device 1102 accesses the wireless communication system via the user UE3 as is schematically represented by arrow 1 22. The respective base station eNB, to eNB5 are connected to the core network 102 via respective backhaul links 114, to 1145, which are schematically represented in Fig. 1 by the arrows pointing to the "core". The core network 102 may be connected to one or more externa! networks. The wireless communication system may be any single-tone or multicarrier system based on frequency-division multiplexing, like the orthogonal frequency-division multiplexing (OFDM) system, the orthogonal frequency-division multiple access (OFDMA) system defined by the LTE standard, or any other IFFT-based signal with or without CP, e.g. DFT- s-OFDM. Other waveforms, like non-orthogonal waveforms for multiple access, e.g. filter- bank multicarrier (FBMC), generalized frequency division multiplexing (GFDM) or universal filtered multi carrier (UFMC), may be used.
In the wireless communication network as shown in Fig. 1 the radio access network 104 may be a heterogeneous network including a network of primary cells, each including a primary base station, also referred to as a macro base station. Further, a plurality of secondary base stations, also referred to as small cell base stations, may be provided for each of the macro cells. Fig. 2 is a schematic representation of a cell, like cell 1061 in Fig. 1 , having two distinct overlaid networks, the networks comprising a macro cell network including the macro cell 106,, and a small cell network. Although Fig. 2 represents only a single macro cell, it is noted that one or more of the other cells in Fig. 1 may also use the overlaid networks. The smali cell network comprises a plurality of small cell base stations eHB^ to SeNB5 each operating within a respective area 120i to 1206, also referring as the coverage area of the small cell. The small cell base stations SeNE^ to SeNB5 may be controlled by the macro cell base station MeNBi to which the respective small cell base stations SeNB-i to SeNB5 are connected via respective backhaul links 122·) to 1225. Rather than connecting the small cell base stations via the backhaul links to the macro cell base station, one or more of the small cell base stations may be coupled to the core network via respective backhaul links. Fig. 2 further shows a user equipment UE being served by the macro cell base station Me Bi as indicated by arrow 12^ and by the small cell base station SeNB^ as indicated schematically by the arrow 1242.
Fig. 3 is a further schematic representation of a plurality of small cells 120t to 1203 of a macro cell (not shown). The macro cell may be similar to that in Fig. 2. Each small cell may serve one or more UEs. The respective small cell base stations SeNB^ SeNB2, SeNB3, .... other than in Fig. 2, are connected via the backhaul links or connections 102i to 023 to the core network 102. The respective small cells 102i to 1023 may be directly connected with each other via the X2 interface, as schematically indicated in Fig. 3. The transport network connecting the respective small cells to the core network 102 may be an optical fiber network including one or more points of presents (PoP) at which a plurality of small cells are connected to the transport network. Further details about a backhaul architecture as shown in Fig. 3 is described in the NGMN Alliance A White Paper "Small Cell Backhaul Requirements", Version 1.0, June 4, 2012. The small cells, also referred to as secondary mobile communication cells, SCs, form an overlay network to the network of macro cells, also referred to as primary mobile communication ceils, PC. The small cells may be connected via backhaul links (BL) to the macro cell (Fig. 2) and/or to the core network (Fig. 3). The backhaul links may be wired or wireless links, and in case of connecting the small cells via the backhaul links to the core network, the point of presence (PoP) of the transport network (Fig. 3) may serve as an interface to the core network. Each small cell may serve a number of mobile users UE within its coverage area by means of a wireless access link (AL) 1242. Further, the UEs may be connected to the primary cell, for example to receive control signals, and the connection may be referred to as a control link (CL). in wireless communication networks, in general, energy savings and energy efficiency are of interest and, for achieving such savings and efficiency, one or more of the SeNBs may be put to sleep or may be turned off when it is determined that no user is within the coverage area of the small cells. Putting the small cell into the sleep mode includes deactivating the access link so that the small cell may not be directly visible by a UE entering its coverage area.
Approaches for activating a sleeping small cell having its access link deactivated are described, for example, in EP 2 387 265 A1 , EP 2 453 706 A1 , EP 2 879 440 A1 , EP 2 879 425 A1 , EP 2 355 594 A1 , EP 2 677 814 A1 and EP 2 941 063 A1. However, even when putting the small cell base station into a sleep mode or when turning it off, the backhaul link to the core network or to the macro cell remains active so that, despite the fact that small cell is sleeping so as to reduce power, a substantial amount of power is needed for keeping the backhaul connection activated, especially in the case a wireless backhaul connection is provided.
Starting from the prior art summarized above, it is an object underlying the present invention to provide an improved approach allowing for further energy savings in secondary cells. This object is achieved by a secondary cell, a wireless communication system and a method as defined in the independent claims. In accordance with the present invention, a secondary base station for a communication network is provided which is connected to a core network or to a primary base station of the communication network via a backhaul link. To provide for energy savings and, in case of wireless backhaul links, to reduce interferences, in accordance with the present invention, when the secondary base station is not needed, for example because there is no UE in the coverage area of the small cell, also the backhaul link of the small cell base station is deactivated. In accordance with the present invention, the secondary base station, when being activated again, will also activate the backhaul link upon its activation.
In accordance with embodiments, a control channel, preferably a low energy channel, may be maintained to allow for the reception of external signals causing the small cell base station to enter into its activated state and to activate the backhaul link so that, once the backhaul link has been re-activated, the small cell base station may be used for serving a UE within a macro cell of which the small cell is part.
The inventive approach is advantageous in that turning off the backhaul link, in addition to the access link, all of which require high energy for being sustained, also in a deactivated state, allows saving power and avoids, especially in the case a wireless backhaul link is provided, radio interferences. Thus, the overall power consumption of the small cells may be reduced and only a low power signaling is needed to detect and activate the small cell base station when needed. Further, this allows for a quick and flexible activation of deactivated links. Embodiments are defined in the dependent claims.
Embodiments of the present invention are now described in further detail with reference to the accompanying drawings, in which:
Fig. 1 shows a schematic representation of an example of a wireless network including a core network and a radio access network;
Fig. 2 shows a schematic representation of a cell, like a cell in Fig. 1 , having two distinct overlaid networks, namely a macro cell network including a macro cell and a small cell network including small cell base stations connected via the backhaul links to the macro cell base station;
Fig. 3 shows a further schematic representation of a plurality of small cells of a macro cell, similar to Fig. 2, wherein the small cell base stations are connected via the backhaul links to the core network;
Fig. 4 shows a schematic representation an arrangement of a macro base station and secondary base stations in accordance with embodiments of the present invention;
Fig. 5 shows an example for a backhaul activation of a deactivated small cell in accordance with an embodiment of the present invention ... ; Fig. 6 shows an example for a small cell activation in accordance with an embodiment of the present invention including an access link activation;
Fig. 7 shows another example for a UE aided small cell activation in accordance with an embodiment of the present invention;
Fig. 8 shows a schematic representation for the activation of a SC through one or more other small cells in accordance with an embodiment of the present invention; Fig. 9 is a schematic representation of a wireless communication system for communicating information between a secondary base station and a UE; and
Fig. 10 illustrates an example of a computer system on which units or modules as well as the steps of the methods described in accordance with the inventive approach may execute.
In the following, preferred embodiments of the present invention are described in further detail with reference to the enclosed drawings in which elements having the same or similar function are referenced by the same reference signs. Fig. 4 is a schematic representation similar to the one of Fig. 2 showing a primary or macro MeNB including, within its coverage area, two secondary or small cell base stations SeNB2 in accordance with embodiments of the invention. The first small cell base station SeNB-t is in its activated state and serves a user equipment UE within the coverage area 120, of the small cell base station SeNBv The small cell base station SeNBi serves the UE via the access link 1242. In addition, the UE is connected to the macro base station βΝΒ-ι via a control link 124,. Further, in the activated state the backhaul link 122, of the small cell base station SeNBi is activated. In the example of Fig. 4, the backhaul link 122-1 is a wireless link to the macro cell base station MeNBv However, in accordance with other embodiments, the backhaul link may be a wired link. In accordance with further embodiments, the backhaul link may not be to the macro cell base station but may be connected to the core network, e.g., via a point of presence of the transport network (see Fig. 3). Fig. 4 shows a deactivated small cell base station SeNB2. There is no UE to be served within its coverage area 1202. Upon recognizing such a situation, the small cell base station SeNB2 enters into a deactivated state in which also the backhaul link is deactivated. Because the backhaul link of the small cell base station SeNB2 is deactivated, it is not shown in Fig. 4. In accordance with the teachings of the present invention, once a UE enters into the coverage area 1202 of the small cell base station SeNB2, the small cell base station will be activated and the backhaul link, either to the macro cell base station or to the core network, will be activated again so that the small cell base station may serve the UE within its coverage area 1202. In such a situation, once the small cell base station has been activated, the connections may be as those described above with reference to the activated small cell base station SeNB,.
Thus, in accordance with the present invention, a small cell is provided which, when being deactivated, provides for improved power savings and improved reductions of interferences because also the backhaul link is deactivated.
In accordance with embodiments of the present invention, a control link 130 is provided for the small cell base station, which is a control link separate from the links described above in Fig. 4 with regard to the small cell base stations SeNB,. The control link 130 is schematically shown and may be a wireless or wired control link. The control link 130 is between the small cell base station SeNB2 and the macro cell base station MeNB,. However, in accordance with other embodiments, the control link 130 may be between the small cell base station SeNB2 and the core network, for example it may be a control link connecting the SeNB2 to the PoP of the transport network (see Fig. 3). The wireless control link 130 may be used to activate the backhaul link 122, once it is determined that a UE enters the coverage area 1202 of the small cell base station SeNB2. In accordance with embodiments, the wireless control channel 130 may be a low rate wireless link, a sensor network interface, a narrow-band beacon link or the like. The wired or wireless control channel may use a frequency band that is within the backhaul link frequency band (in-band control channel) or that is within another frequency band different from the backhaul link frequency band, i.e., an out of band control channel. The control channel may be a low power and/or a low latency channel to receive an external signaling for the small cell base station causing it to be activated and to activate the backhaul link.
In accordance with embodiments, the small cell backhaul link activation may be initiated by one or more of the following entities:
a user terminal UE may send a request to use the SC, for example upon a request of a data transmission,
a user terminal UE may act as a relay for the PC (primary cell) or the PoP and may forward a request to activate the SC,
the PC base station MeNBi may send a request to the SC to activate the SC backhaul link,
the point of presence (PoP) may send a request to the SC to activate the SC backhaul link,
another SC in the vicinity, like the SC SeNB-i in Fig. 4, may send a request, for example on behalf of the PC.
In the above embodiments, in which the user terminal UE forwards a request to activate the SC or in which the request is sent by another SC, the control link 130 is configured to receive the respective requests from these entities. In accordance with the above described embodiments, the connection to the SC is maintained by providing the low power control channel 130 between the SC and the PC or between the SC and the PoP. In accordance with examples, this connection may be in accordance with different standards, like the NB-IOT standard, the GSM standard, the LTE standard or the 5G/NR standard. Fig. 5 shows an example for a backhaul activation of the deactivated small cell SeNB2 of Fig. 4 in accordance with an embodiment of the present invention. The small cell base station SeNB2 has the control channel 130 so as to maintain the connection to the other network entities when being in the deactivated state. The control channel 130 formed of a first control channel 130a connecting the small cell base station SeNB2 to the macro cell base station Me Bi and/or a second control channel 130b to the point of presence of the transport network of the core network. UE is connected to the macro cell base station MeNBi, as is indicated at ©. Fig. 5 shows a situation in which the UE came into the reach of the SC as is indicated at ©. Once the presence of the UE within the coverage area of the SC has been determined, the MeNBi may signal via the first control channel 130a directly to the SeNB2 (as indicated at 3a) that is to be activated. The SC will activate the backhaul connection 1222. In case of a wireless backhaul link 1222 the SC, responsive to the signaling 3a on the first control channel 130a, may activate the backhaul link at the SeNB2. Further, the macro cell Me Bi may signal, via its backhaul line 114i, to the core 102 that the SC is to be activated, and core 102 causes an activation of the backhaul link at the PoP. In accordance with other examples, the second control channel 130b may be between the SC and the PoP. In this case, the macro cell MeNBi signals the presence of the UE close to the SC via its backhaul link 114i to the core 102 which, in turn, causes the PoP to send an activation message to the SC via the second control channel 130b and causes the PoP side of the backhaul link to be activated, while the SC, responsive to the signaling via the second control channel 130b, activates the its backhaul link 1222, as is indicated at ©.
In accordance with other embodiments, the wireless control channel may include both channels 130a and 130b shown in Fig. 4, i.e., the control channel may be maintained between the SC and the macro cell base station as well as between the SC and the core network. In such an embodiment, the signaling to activate the backhaul link 122 is such that after receiving the notice to be activated via the control channel 130a, the SC activates the backhaul link at its end, and signals via the control channel 130b to the PoP to activate the backhaul at its end, for example to activate the transceivers at both ends of the backhaul link.
In the embodiments described above, the wireless or wired control link 130 is between the SC and the PC or between the SC and the PoP or between both. However, in accordance with other examples, the signaling to activate the backhaul link may be received via an access link between the SC and the PC. The access link is like the link 1242 shown in Fig. 4 via which the UE is connected to the SC. In other words, in accordance with such embodiments, the connection between the SC and the PC may be in accordance with the communication standard used in the communication network, for example the SC may act as a standard terminal device towards the PC, like a LTE terminal or a regular UE, an NB- loT client or the like. In such an embodiment, the activation of the SC and its backhaul link activation may be initiated by the primary cell which may send a message to the SC directly through the access link or the message may be sent from the point of presence via the PC. In accordance with yet other embodiments, the signaling for activating the backhaul link may be received at the SC via an access link 124 (see Fig. 4) being active and connected to a UE using, for example, the LTE standard, or any other access technology. In this embodiment, the SC acts as a standard base station towards the connected UE and the access link may be a standard LTE link, a millimeter-wave link or any standard UE link. The backhaul link activation may be initiated by one or more of the following entities:
the UE may send a message to the SC, for example in response to a request for a data transmission,
the UE may act as a relay for the PC and send a message to the SC,
another SC that connects to the SC to be activated and that acts as a UE itself, may send a message to the SC,
the UE may relay a message from the PoP to the SC.
In accordance with yet other embodiments, the SC may be connected to a fixed line network, for example by a radio connection, a visible light connection, an optical fiber connection, a cable connection or a twisted pair connection. The PC may send the activation message to the SC via the fixed line network. In this embodiment, the SC may be completely turned off to save power and turned on at predefined time intervals to receive updates. Alternatively, the SC may be operated on a low power control mode and may be contacted by the UE, other SCs or the PC to be activated.
In the embodiments described so far, the backhaul link activation between the SC and the PoP has been described. However, in the same way as described above, a backhaul link between the SC and the eNBi may be activated. In accordance with one embodiment, the backhaul link of the SC to the PC may be activated via the above described wireless control channel, via the above described access link, or via the above described fixed line link. In accordance with further embodiments, the SC, when being deactivated, may also deactivate its access link so as to save power. To activate the access link, the core network may turn on the small cell, for example in case of a location aware core network. In other embodiments, the SC may provide a beacon signal using a low power device, and a UE may transmit beacon information received from the SC to the core network. In a similar way as described above, a wired or wireless control channel between the PC and/or the PoP may be maintained by the SC in its deactivated state, and the access link for serving a UE may be activated via this wireless control channel by providing additional signaling also instructing the SC to activate its access link.
Fig. 6 shows an example for a small cell activation in accordance with an embodiment of the present invention including an access link activation. The small cell SeNB2 is deactivated and the UE is assumed coming into its reach, i.e., it is within the coverage area 1202. The SeNB2 is configured to send out a beacon signal, as is indicated at © that is received by the UE and transmitted via the MeNB, and its backhaul to the core 102, as indicated at © and ®. The core 102, via the control channel 130, causes the activation of the SC which includes activating the backhaul link 1222 and the access link 1242 as is indicated at ©.
Fig. 7 shows another example for a UE aided small cell activation in accordance with an embodiment of the present invention. In a similar way as described above with reference to Fig. 6, a UE detects the beacon signal from the deactivated SeNB2, as is indicated at ©. The SeNB2 may recognize that the beacon signal has been detected by the UE and starts its activation process which includes sending an activation message for the core network 102 to the UE. The activation message is relayed via the UE and the primary cell Me Bi to the core network 102, as is indicated at ® and ®. The core network 102 activates the backhaul link 1222 between the core 102 and the small cell SeNB2, as indicated at © and ©, so that the SC SeNB2 which has been activated is now also connected via its backhaul link 1222 to the core 102 and, thus, can serve the UE as indicated at ©.
In accordance with yet other embodiments, the backhaul between the SC and the core may not be a direct backhaul connection, but may be a backhaul link extending through one or more other small cells, as indicated, for example, in Fig. 3 by the X2-interface connection connecting the small cell base stations SeNBi, SeNB2 and SeNB3 are connected via a backhaul link X2 to the PoP, i.e., the backhaul link of SeNBi to the PoP is through the SeNB2. Such a backhaul may also be deactivated or turned off to save power, and the wakeup process may be done through a beacon response or a wakeup receiver. Fig. 8 shows a schematic representation for the activation of a SC through one or more other small cells in accordance with an embodiment of the present invention. Two small cells are shown by their respective small cell base stations SeNBi and SeNB2. The first small cell base station SeNBi has a backhaul link for a connection to the core 102 or to the point of presence, wherein the backhaul link comprises a first link portion 122i between the Se Bi and the other small cell SeNB2, and a second portion 1222 from the other small cell SeNB2 to the PoP. A UE entering the coverage area of the SeNBi may receive a beacon message from the small ceil, as is indicated at ®. The UE may cause the SC to wake up or to be activated which, in turn, causes the SC to activate its backhaul link 122i towards the other small cell SeNB2 as indicated at @. Further, an activation message may be sent via the UE and the primary base station MeNBi to the PoP, as indicated at ® and © so as to cause an activation of the backhaul link 1222 to the other small cell. Once both the backhaul receiver at the core side and at the SCs relaying the link are woken up, the backhaul link for the first SC SeNBi is active, as indicated at ©, and the UE may be served by the SeNBi, as indicated at ©.
In the embodiments described above, the activation of the access link between the SC and the UE to be served by the SC may be done via the control channel between the SC and the MC and/or between the SC and the core. In accordance with other examples, the signaling to activate the access link to the UE may be via the backhaul link, once it has been activated. In accordance with other embodiments, the activation of the access link between the SC and the UE may be signaled via the above-described access link between the small cell and the primary cell or via the above-described fixed line link.
In accordance with other embodiments, the activation of the small cell may be triggered due to a detection that the PC is absent. For example because the MeNBi may no longer operating due to power saving, failures and the like. In this case, the SC activates its access link so as to serve one or more UEs within its coverage area and, in addition, via a connection to the core network, for example via the above described control channel between the SC and the PoP, the backhaul connection to the core is established so as to allow the SC to serve the UE. In addition, the SC may try to connect other SCs in the vicinity to serve the UE via the neighboring SC, for example to route data from the SC to its neighboring SC and from there to the core network.
In some of the embodiments described above, it has been described that the SC is connected to the UE over a wireless UE access link and that the SC acts like a base station towards the connected UE using a communication standard, for example the one as is also used in the communication network. However, in accordance with other embodiments, the SC may be configured to provide as the access link a device-to-device link, so that, in this configuration, the SC acts to the connected UE as another UE providing for a side link or device-to-device link, like the PC 5 link. The SC may listen to the side link and/or broadcast over the side link so as to recognize, for example, a UE requesting a connection to the small cell base station. In addition to sending out the beacon message, the SC may be configured to listen as to whether there is a UE requesting, in response to the beacon message, a connection to the SC.
Embodiments of the present invention may be implemented in a wireless communication system as depicted in Fig. 1 , Fig. 2, Fig. 3 or Fig. 4 including primary and secondary base stations and users, like mobile terminals or loT devices. Fig. 9 is a schematic representation of a wireless communication system for communicating information between a secondary base station SeNB and a UE. The secondary base station SeNB may include one or more antennas ANTS8NB or an antenna array having a plurality of antenna elements, as well as a signal processor/transceiver circuit 202 to process signals to be transmitted/received. The UE may include one or more antennas ANTUE or an antenna array having a plurality of antenna elements, as well as a signal processor/transceiver circuit 204 to process signals to be transmitted/received. As is indicated by the arrow 206 signals are communicated between the secondary base station SeNB and the UE via a wireless communication link, like the above described access link (Fig. 4). The wireless communication system may operate in accordance with the techniques described herein. For example, when there is no UE to be served by the secondary base station SeNB, the SeNB may be deactivated. Upon deactivating the SeNB, a backhaul link 208 to the core and/or the MeNB is deactivated. When a UE is to be served by the secondary base station SeNB, the SeNB will be activated via an external signaling that may be received via the transceiver. Activating the SeNB includes activating the backhaul link 204. Once activated the SeNB serves the UE. Although some aspects of the described concept have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or a device corresponds to a method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus.
Various elements and features of the present invention may be implemented in hardware using analog and/or digital circuits, in software, through the execution of instructions by one or more general purpose or special-purpose processors, or as a combination of hardware and software. For example, embodiments of the present invention may be implemented in the environment of a computer system or another processing system. Fig. 10 illustrates an example of a computer system 300. The units or modules as well as the steps of the methods performed by these units may execute on one or more computer systems 300. The computer system 300 includes one or more processors 302, like a special purpose or a general purpose digital signal processor. The processor 302 is connected to a communication infrastructure 304, like a bus or a network. The computer system 300 includes a main memory 306, e.g., a random access memory (RAM), and a secondary memory 308, e.g., a hard disk drive and/or a removable storage drive. The secondary memory 308 may allow computer programs or other instructions to be loaded into the computer system 300. The computer system 300 may further include a communications interface 310 to allow software and data to be transferred between computer system 300 and external devices. The communication may be in the form electronic, electromagnetic, optical, or other signals capable of being handled by a communications interface. The communication may use a wire or a cable, fiber optics, a phone line, a cellular phone link, an RF link and other communications channels 312.
The terms "computer program medium" and "computer readable medium" are used to generally refer to tangible storage media such as removable storage units or a hard disk installed in a hard disk drive. These computer program products are means for providing software to the computer system 300. The computer programs, also referred to as computer control logic, are stored in main memory 306 and/or secondary memory 308. Computer programs may also be received via the communications interface 310. The computer program, when executed, enable the computer system 300 to implement the present invention. In particular, the computer program, when executed, enable processor 302 to implement the processes of the present invention, such as any of the methods described herein. Accordingly, such a computer program may represent a controller of the computer system 300. Where the disclosure is implemented using software, the software may be stored in a computer program product and loaded into computer system 300 using a removable storage drive, an interface, like communications interface 310. The implementation in hardware or in software may be performed using a digital storage medium, for example cloud storage, a floppy disk, a DVD, a Blue-Ray, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, having electronically readable control signals stored thereon, which cooperate (or are capable of cooperating) with a programmable computer system such that the respective method is performed. Therefore, the digital storage medium may be computer readable.
Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.
Generally, embodiments of the present invention may be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer. The program code may for example be stored on a machine readable carrier.
Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier. In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.
A further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein. A further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or the sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet. A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein. A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.
In some embodiments, a programmable logic device (for example a field programmable gate array) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor in order to perform one of the methods described herein. Generally, the methods are preferably performed by any hardware apparatus. The above described embodiments are merely illustrative for the principles of the present invention. It is understood that modifications and variations of the arrangements and the details described herein will be apparent to others skilled in the art. It is the intent, therefore, to be limited only by the scope of the impending patent claims and not by the specific details presented by way of description and explanation of the embodiments herein.

Claims

A secondary base station for a communication network having a radio access network and a core network, the radio access network having one or more primary base stations, secondary base station comprising: a transceiver for a radio communication with one or more user equipments (UEs); and a backhaul link to the core network and/or to the primary base station; wherein the secondary base station is configured to be in a first state in which the backhaul link is activated, or in a second state in which backhaul link is deactivated, and wherein the secondary base station is configured to enter the first state responsive to an external signaling, wherein entering the first state includes activating the backhaul link.
The secondary base station of claim 1 , wherein the backhaul link is a wireless backhaul link.
The secondary base station of claim 1 or 2, wherein the secondary base station is connected to the communication network by a wireless control channel, and wherein the secondary base station is configured to enter the first state responsive to the external signaling on the wireless control channel.
The secondary base station of claim 3, wherein the wireless control channel includes a low rate wireless link, a sensor network interface, or a narrow-band beacon link.
The secondary base station of claim 3 or 4, wherein the wireless control channel is configured to use a frequency band inside or outside of a backhaul link frequency band.
6. The secondary base station of one of claims 3 to 5, wherein the wireless control channel operates in accordance with the NB-loT, GSM, LTE standard or 5G standard.
The secondary base station of one of claims 3 to 6, wherein the wireless control channel is a low power channel and/or low latency channel.
The secondary base station of one of claims 3 to 7, wherein the wireless control channel (CC1 , CC2) is maintained between the secondary base station and the primary base station, or between the secondary base station and a point of presence (PoP).
The secondary base station of one of claims 3 to 7, wherein the wireless control channel (CC1 , CC2) provides a first link to the primary base station and a second link to the core network, wherein the backhaul link is activated at the secondary base station responsive to the external signaling on the first link, and wherein the backhaul link is activated at the core network responsive to the external signaling on the second link.
The secondary base station of one of claims 1 to 9, wherein the external signaling comprises:
a request from a UE to use the secondary base station;
a request to activate the backhaul link forwarded by a UE acting as a relay for the primary base station or for a PoP;
a request from the primary base station to activate the backhaul link;
a request from a PoP to activate the backhaul link; or
a request to activate the backhaul link forwarded by another secondary base station acting as a relay for the primary base station, for a PoP, or for a UE.
The secondary base station of claim 1 or 2, wherein the secondary base station is served by the primary base station over a wireless access link in accordance with the communication standard used in the communication network, and wherein the secondary base station is configured receive the external signaling for entering the first state via the wireless access link.
12. The secondary base station of claim 11 , wherein the secondary base station acts as a UE towards the primary base station.
13. The secondary base station of claim 12, wherein the secondary base station acts towards the primary base station as a 5G terminal, as a LTE terminal, as a GSM terminal, or as a NB-loT client.
14. The secondary base station of one of claims 11 to 13, wherein the external signaling comprises:
a request from the primary base station to activate the backhaul link; or a request from a PoP to activate the backhaul link.
15. The secondary base station of one of claims 1 to 14, wherein the secondary base station is configured to connect to a UE over a wireless UE access link.
16. The secondary base station of claim 15, wherein the wireless UE access link is a link in accordance with the communication standard used in the communication network, or is a device-to-device link.
17. The secondary base station of claim 15 or 16, wherein the wireless UE access link is a link in accordance with the communication standard used, and wherein the secondary base station acts as a base station towards the connected UE.
18. The secondary base station of claim 15 or 16, wherein the wireless UE access link is a device-to-device link, and wherein the secondary base station acts as a UE towards the connected UE.
19. The secondary base station of claim 8, wherein the device-to-device link comprises a PCS sidelink, and the secondary base station is configured to broadcast its presence over the sidelink and/or to listen on the sidelink for a UE requesting a connection to the secondary base station.
20. The secondary base station of one of claims 15 to 19, wherein, when entering the second state, the secondary base station is configured to deactivate the wireless UE access link, and wherein, when entering the first state, the secondary base station is configured to activate the wireless UE access link.
The secondary base station of one of claims 15 to 20, wherein, when the wireless UE access link is active and the secondary base station is connected to a UE, the secondary base station is configured receive the external signaling for entering the first state via the wireless UE access link.
The secondary base station of one of claims 15 to 21 , wherein the external signaling comprises:
request from the connected UE to use the secondary base station;
a request to activate the backhaul link forwarded by a UE acting as a relay for the primary base station or for a PoP; or
a request to activate the backhaul link forwarded by another secondary base station.
The secondary base station of claim 1 or 2, wherein the secondary base station is connected to a fixed line network by a channel, and wherein the secondary base station is configured to enter the first state responsive to the external signaling on the channel.
The secondary base station of claim 23, wherein the channel includes a wireless channel, like a radio channel, or a wired channel, like a visible light channel, a fiber connection, a cable connection, or twisted pair connection.
The secondary base station of claim 23 or 24, wherein the external signaling comprises a request to activate the backhaul link from the primary base station, a UE, another secondary base station, or a PoP.
The secondary base station of one of claims 23 to 25, wherein, in the second state, the secondary base station is configured be completely turned off to save power, or to be operated in a low power control mode to be contacted by a UE or another secondary base station.
The secondary base station of claim 1 or 2, wherein the external signaling includes a detection that the primary base station is absent.
28. The secondary base station of one of claims 1 to 27, wherein the secondary base station is configured to enter the first state in case no UE is served by the secondary base station.
29. The secondary base station of one of claims 1 to 28, wherein the first state comprises an active state of the secondary base station, and the second state comprises an inactive state, the inactive state being a sleep or power saving state of the secondary base station.
30. A wireless communication system, comprising: a radio access network having one or more primary base stations; a core network; and one or more a secondary base stations of one of claims 1 to 29.
31. A method for controlling a secondary base station for a communication network having a radio access network and a core network, the radio access network having one or more primary base stations, the method comprising: responsive to a certain event, switching the secondary base station into a state in which a backhaul link to the core network and/or to the primary base station is deactivated, and responsive to an external signaling, activating the backhaul link to the core network and/or to the primary base station.
32. A non-transitory computer program product comprising a computer readable medium storing instructions which, when executed on a computer, carry out the method of claim 31.
PCT/EP2018/055675 2017-03-23 2018-03-07 Secondary base station, wireless communication system and method for controlling a secondary base station WO2018172082A1 (en)

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