WO2015103742A1 - Procédé et appareil de sélection de composante porteuse dans un réseau de petites cellules - Google Patents

Procédé et appareil de sélection de composante porteuse dans un réseau de petites cellules Download PDF

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Publication number
WO2015103742A1
WO2015103742A1 PCT/CN2014/070299 CN2014070299W WO2015103742A1 WO 2015103742 A1 WO2015103742 A1 WO 2015103742A1 CN 2014070299 W CN2014070299 W CN 2014070299W WO 2015103742 A1 WO2015103742 A1 WO 2015103742A1
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Prior art keywords
scc
pcc
target cell
component carrier
cell
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PCT/CN2014/070299
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English (en)
Inventor
Su YI
Ming Lei
Qing Huang
Weitao GE
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Nec Corporation
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Priority to PCT/CN2014/070299 priority Critical patent/WO2015103742A1/fr
Publication of WO2015103742A1 publication Critical patent/WO2015103742A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference

Definitions

  • Embodiments of the present invention generally relate to communication techniques. More particularly, embodiments of the present invention relate to a method and apparatus for selecting a component carrier (CC) in a small cell network. BACKGROUND OF THE INVENTION
  • LPNs Low power nodes
  • HeNBs home base stations
  • small cells such as picocells, femtocells, and microcells etc.
  • Carrier Aggregation for aggregating multiple component carriers is used in small cell networks. In some situations, due to dense or self-development of some small cells, serious inter-cell interference may arise.
  • each eNodeB has one active component carrier, denoted as a primary component carrier (PCC).
  • PCC primary component carrier
  • the PCC is automatically selected by the eNodeB when it is first switched on.
  • SCCs secondary component carriers
  • each cell dynamically selects additional component carriers for transmission and/or reception, which is referred to as selection of secondary component carriers (SCCs).
  • SCCs secondary component carriers
  • the HeNBs generally do not have the ability of performing frequency allocation and cell optimization, when a HeNB selects a PCC or SCC(s) which has been used by neighboring cells, inter-cell interference may be caused. As such, frequency utilization may be decreased, and throughput of the small cell network may be reduced. In view of the above, selection of component carrier on which these small cells work is crucial.
  • embodiments of the present invention would propose to select a component carrier in a small cell network, such that interference between small cells is reduced and throughput in the small cell network is improved.
  • embodiments of the invention provide a method for selecting a component carrier in a small cell network.
  • the method may comprise steps of: establishing an interference list and a SCC pool, wherein the interference list comprises information about at least one neighboring cell of a target cell, and the SCC pool comprises SCC candidates of the target cell; determining a PCC of the target cell based on the interference list; and determining a SCC of the target cell based on the SCC pool when the PCC of the target cell does not meet communication requirements.
  • inventions of the invention provide an apparatus for selecting a component carrier in a small cell network.
  • the apparatus may comprise: an establishing unit configured to establish an interference list and a SCC pool, wherein the interference list comprises information about at least one neighboring cell of a target cell, and the SCC pool comprises SCC candidates of the target cell; a primary determining unit configured to determine a PCC of the target cell based on the interference list; and a secondary determining unit configured to determine a SCC of the target cell based on the SCC pool when the PCC of the target cell does not meet communication requirements.
  • the following benefits are expected with the invention. With the solution according to the present invention, undesirable interference between small cells is reduced and throughput of the small cell network is improved.
  • FIG. 1 illustrates a schematic diagram of a small cell network 100
  • FIG. 2 illustrates a flow chart of a method 200 for selecting a component carrier in a small cell network according to embodiments of the invention
  • FIG. 3 illustrates a flow chart of a method 300 for establishing an interference list and a SCC pool according to embodiments of the invention
  • FIG. 4 illustrates a flow chart of a method 400 for determining a PCC of the target cell based on the interference list according to embodiments of the invention
  • FIG. 5 illustrates a flow chart of a method 500 for determining a SCC of the target cell based on the SCC pool according to embodiments of the invention
  • FIG. 6 illustrates a flow chart of a method 600 for determining a component carrier from the SCC pool based on the interference list as the SCC of the target cell according to embodiments of the invention
  • FIG. 7 illustrates a flow chart of a method 700 for determining a component carrier from at least one SCC used by the at least one neighboring cell as the SCC of the target cell according to embodiments of the invention.
  • FIG. 8 illustrates a block diagram of an apparatus 800 for selecting a component carrier in a small cell network according to embodiments of the invention.
  • the term "user equipment” or “UE” may refer to a terminal, a Mobile Terminal (MT), a Subscriber Station (SS), a Portable Subscriber Station (PSS), Mobile Station (MS), or an Access Terminal (AT), and some or all of the functions of the UE, the terminal, the MT, the SS, the PSS, the MS, or the AT may be included.
  • MT Mobile Terminal
  • PSS Subscriber Station
  • MS Mobile Station
  • AT Access Terminal
  • BS may refer to a node B (NodeB), an evolved NodeB (eNodeB), a Base Transceiver Station (BTS), an Access Point (AP), a Radio Access Station (RAS), or a Mobile Multihop Relay (MMR)-BS, and some or all of the functions of the BS, the NodeB, the eNodeB, the BTS, the AP, the RAS, or the MMR-BS may be included.
  • a BS may be a macro BS, a micro BS, a pico BS, a femto BS, and so on.
  • small cell may refer to, for example, a microcell, a picocell, a femtocell, etc.
  • a small cell may be controlled by a low power node (LPN), such as a micro BS, a pico BS, a femto BS, and so on.
  • LPN low power node
  • the LPN may be also called as a home base station.
  • the home base station may be a home eNodeB (HeNB).
  • target cell may refer to a small cell which is selecting its component carriers.
  • the target cell may have one or more neighbors which are also small cells, called as neighboring cells.
  • the target cell and the neighboring cells may interfere with each other, for example, due to overlap of component carriers.
  • the term "interference list” may refer to a list comprising information about at least one neighboring cell of a target cell.
  • the interference list may comprise identification and reference signal strength of the at least one neighboring cell, pathloss from the target cell to the neighboring cell, and the like.
  • the reference signal strength may be Reference Signal Receiving Power (RSRP).
  • SCC pool may refer to a set of component carriers, which are candidates of secondary component carriers of the target cell.
  • FIG. 1 illustrates a schematic diagram of a small cell network 100.
  • a heterogamous network illustratively comprises a macro eNB (MeNB) and a plurality of home eNB (HeNBs), e.g., femto eNBs.
  • the MeNB controls a macro cell and each of the HeNBs controls a femtocell.
  • the plurality of HeNBs constitute a small cell network 100. Any one of the femtocells may be considered as a target cell, and accordingly its neighbors are neighboring cells
  • Embodiments of the present invention may be applied in various communication systems, including but not limited to a Long Term Evolution Advanced (LTE-A) system.
  • LTE-A Long Term Evolution Advanced
  • LTE-A Long Term Evolution Advanced
  • FIG. 2 illustrates a flow chart of a method 200 for selecting a component carrier in a small cell network according to embodiments of the invention.
  • the small cell network may be, but not limited to, the small cell network 100 as shown in FIG. 1.
  • the method 200 may be carried out by a LPN (e.g., a HeNB shown in FIG. 1) which controls a target cell or some other suitable device, or may be carried out by an apparatus comprised in the LPN or some other suitable device.
  • LPN e.g., a HeNB shown in FIG. 1
  • step S201 an interference list and a SCC pool are established.
  • the interference list may comprise information about at least one neighboring cell of a target cell.
  • the SCC pool may comprise SCC candidates of the target cell.
  • the interference list and the SCC pool may be established by several ways.
  • at least one notification message which may comprise information about adding or release of a PCC and/or at least one SCC in a neighboring cell, may be received from the at least one neighboring cell; reference signal strength, e.g., SRP, of the at least one neighboring cell may be obtained; and then, the interference list may be established based on the at least one notification message and the reference signal strength and the SCC pool may be established based on the at least one notification message. Details for establishing the interference list and the SCC pool may be found in embodiments in connection with FIG. 3.
  • a PCC of the target cell is determined based on the interference list.
  • the PCC may be determined in several ways.
  • the PCC may be determined by calculating an interference factor for each of PCC candidates based on the interference list, and selecting a component carrier which has a minimized interference factor from the PCC candidates as the PCC of the target cell.
  • a component carrier is selected, whether the selected component carrier is suitable to be the PCC of the target cell is to be further determined.
  • a request message may be sent from the target cell to the at least one neighboring cell to ask whether the selected component carrier is applicable to be a PCC of the target cell; the neighboring cell may reply the target cell according to predetermined policies; and then, the target cell may determine whether the carrier component is applicable to be the PCC based on the replies from one or more neighboring cells. Details for determining the PCC of the target cell may be found in embodiments in connection with FIG. 4.
  • a SCC of the target cell is determined based on the SCC pool when the PCC of the target cell does not meet communication requirements.
  • one or more SCCs may be determined to serve UE(s) in the target cell.
  • first, whether the SCC pool is empty may be judged. If the SCC pool is not empty, a component carrier may be determined from the SCC pool based on the interference list, as the SCC of the target cell. Otherwise, if the SCC pool is empty, a power reduction solution may be adopted, wherein a component carrier may be determined at least one SCC used by the at least one neighboring cell, as the SCC of the target cell. Details for determining the SCC of the target cell may be found in embodiments in connection with FIGs. 5-7.
  • the LPN controlling the target cell may release the SCC and send Notification Message to its neighboring cells to inform the release of the SCC.
  • FIG. 3 illustrates a flow chart of a method 300 for establishing an interference list and a SCC pool according to embodiments of the invention.
  • the method 300 may be considered as an embodiment of step S201 of the method 200 described above with reference to Fig. 2.
  • the interference list and the SCC pool are established.
  • this is only for the purpose of illustrating the principles of the present invention, rather than limiting the scope thereof.
  • At step S301 at least one notification message is received from the at least one neighboring cell.
  • a notification message comprises information about adding or release of a PCC and/or at least one SCC in a neighboring cell.
  • the notification message may be transmitted from the target cell to a neighboring cell or from a neighboring cell to the target cell, when a component carrier is added or released.
  • the notification message may be sent immediately after the component carrier is added or released, or may be sent periodically.
  • the notification message may be implemented in several ways, and an embodiment of its format is shown in Table 1.
  • the first field indicates the identification of the small cell which is a source cell sending the notification message
  • the second field indicates that a component carrier is added or released in the source cell
  • the third field indicates whether the component carrier which is added or released is a primary component carrier or a secondary component carrier
  • the fourth field indicates the identification of the component carrier which is added or released.
  • a component carrier i is selected as a PCC of a small cell k (e.g., by LPN k)
  • the HeNB k may send to its neighbors a notification message which is "kl li”.
  • reference signal strength of the at least one neighboring cell is obtained.
  • the reference signal strength may be Reference Signal Receiving Power (RSRP).
  • the interference list is established based on the at least one notification message and the reference signal strength.
  • the RSRP of a neighboring cell is larger than a predefined threshold, it means that the neighboring cell may have potential interference with the target cell. In this event, the identification and RSRP of this neighboring cell may be stored in the interference list.
  • the interference list may be established in several ways.
  • the identifications of a PCC and/or at least one SCC used by a neighboring cell may be obtained based on the notification message sent from the neighboring cell.
  • the notification message comprises information about adding or release of a PCC and/or a SCC in a neighboring cell.
  • the LPN controlling the target cell also referred to as the "target LPN” may determine the identifications of the PCC and one or more SCCs (if there are) used by a neighboring cell.
  • the pathloss from the target cell to the neighboring cell may be estimated based on the reference signal strength, e.g., the RSRP.
  • the interference list may be created based on the identifications of the PCC and/or the SCC(s) used by a neighboring cell, the reference signal strength and the pathloss.
  • the interference list may be implemented according to the following Table 2.
  • CELL ID indicates the identification of a neighboring cell which may have interference to the target cell
  • PCC ID indicates the identification the PCC used by the neighboring cell
  • PCC RSRP indicates the RSRP measured on the PCC
  • SCC ID indicates the identification a SCC used by the neighboring cell
  • SCC RSRP indicates the RSRP measured on the SCC
  • PATHLOSS indicates the pathloss from the target cell to the neighboring cell.
  • the notification message comprises information about adding or release of a PCC and/or a SCC of a neighboring cell.
  • the target LPN may use component carriers which are different from the PCC and/or SCC used by the neighboring cell, as candidate component carriers for selection of a SCC. In this way, the SCC pool comprising SCC candidates of the target cell may be established.
  • FIG. 4 illustrates a flow chart of a method 400 for determining a PCC of the target cell based on the interference list according to embodiments of the invention.
  • the method 400 may be considered as an embodiment of step S202 of the method 200 described above with reference to Fig. 2.
  • a component carrier is determined and is confirmed whether it is applicable to be the PCC of the target cell.
  • this is only for the purpose of illustrating the principles of the present invention, rather than limiting the scope thereof.
  • an interference factor for each of PCC candidates is calculated based on the interference list.
  • the interference factor indicates amount of interference between the target cell and one of its neighboring cells.
  • the interference factor may be calculated based on PCC incoming interference, PCC outgoing interference, SCC incoming interference, and SCC outgoing interference.
  • the PCC incoming interference is incoming interference from a neighboring cell which uses a PCC candidate as its PCC to the target cell.
  • the PCC outgoing interference is outgoing interference from the target cell to the neighboring cell which uses the PCC candidate as its PCC.
  • the SCC incoming interference is incoming interference from a neighboring cell which uses the PCC candidate as its SCC to the target cell.
  • the SCC outgoing interference is outgoing interference from the target cell to the neighboring cell which uses the PCC candidate as its SCC.
  • the interference factor for the PCC candidate may be computed based thereon.
  • the interference factor denoted as , may be calculated as follows:
  • a (0 ⁇ a ⁇ 1) is weight factor
  • I ⁇ ** and I!!*f n may be obtained from the interference list of the target cell and may be, for example, P SRP and SCC RSRP of cell k ' in the interference list of the target cell; and a n d -3 ⁇ 4c,'out ma y be estimated based on the pathloss in the interference list and an initial power, for example, by calculating the difference between initial power and the pathloss.
  • the weight factor a is used to adjust contributions of the PCC incoming interference, the PCC outgoing interference, the SCC incoming interference, and the SCC outgoing interference.
  • the weight factor is adjustable, which may be adjusted according to an initial power on a PCC/PCC, traffic load on the PCC/SCC or the like.
  • a component carrier which has a minimized interference factor is selected from the PCC candidates, as the PCC of the target cell.
  • the index i may be obtained by calculating the following:
  • a component carrier may be determined from the more than one component carrier as the PCC of the target cell, such that the number of neighboring cells that use the determined component carrier is minimal.
  • the component carrier whose Num J is minimal may be determined as the PCC of the target cell.
  • a request message is sent to the at least one neighboring cell.
  • the target cell may not directly use the selected component carrier, so as to avoid sharp reduction of throughput of neighboring cells.
  • a request message may be sent from the target cell to the at least one neighboring cell, so that the target cell may confirm whether the selected component carrier is applicable to be the PCC of the target cell.
  • the request message may comprise: identification of the target cell, the selected component carrier, a priority level for using the selected component carrier by the target cell, and/or the like.
  • the priority level may be a random number chosen from a fix window, or may be prescribed according to system requirements or some other rules.
  • step S404 whether the selected component carrier is applicable to be the PCC of the target cell is confirmed based on at least one reply to the request message from the at least one neighboring cell.
  • the neighboring cell when a neighboring cell receives the request message from the target cell, the neighboring cell may make response according to a set of predetermined policies.
  • the predetermined policies may be defined with respect to different cases.
  • the neighboring cell if a neighboring cell is working normally and its PCC is the same as the selected component carrier, and if interference caused when the selected component carrier is used as the PCC of the target cell is less than first tolerance of the neighboring cell, the neighboring cell sends to the target cell a reply comprising an acknowledge (ACK) message.
  • ACK acknowledge
  • the neighboring cell If a neighboring cell is working normally and its SCC is the same as the selected component carrier, and if interference caused when the selected component carrier is used as the PCC of the target cell is less than second tolerance of the neighboring cell, the neighboring cell sends to the target cell a reply comprising an ACK message. If a neighboring cell is working normally and neither its PCC nor its SCC is the same as the selected component carrier, the neighboring cell sends to the target cell a reply comprising an ACK message. If a neighboring cell is initializing and selecting its PCC, and if its PCC is not the same as the selected component carrier, the neighboring cell sends to the target cell a reply comprising an ACK message.
  • the neighboring cell compares its priority level with the priority level in the request message, and sends to the target cell a reply comprising an ACK message when the priority level in the request message is higher.
  • the first tolerance and the second tolerance may be determined in several ways.
  • y th indicates a threshold of a difference between a signal to interference and noise ratio (SIN ) obtained when the target cell does not use the component carrier i, and a SINR obtained when the target cell uses the component carrier i, then the dilference, denoted as ASINR , may be expressed as follows:
  • formula (4) may be further expressed as follows:
  • G k ', k m indicates the channel gain between target cell k and UE m of neighboring cell k'on CC i;
  • I , m indicates the interference received by UE m of neighboring cell k' on CC i;
  • ⁇ ⁇ 2 indicates the additive white Gaussian noise received by UE m of neighboring cell k' on CC i.
  • AI m may be derived as follows:
  • I th may be derived as follows:
  • the component carrier i may be used by the neighboring cell as its PCC or SCC, there may be two ⁇ ⁇ for both cases.
  • there may be two thresholds ⁇ ⁇ and y th2 wherein ⁇ ⁇ is used when the neighboring cell's PCC is the same as the component carrier i, and y th2 is used when the neighboring cell's SCC is the same as the component carrier i.
  • there may be two I th i.e., the first tolerance I M and the second tolerance I th2 , which may be calculated based on ⁇ ⁇ and y th2 through formulas (4)-(7).
  • the neighboring cell may send a reply comprising a negative acknowledge (NACK) message.
  • NACK negative acknowledge
  • the target cell When the target cell receives replies from its neighboring cells, if each of the replies comprises an ACK message, it may confirm that the selected component carrier is applicable to be the PCC of the target cell. Otherwise, if one of the replies does not comprise an ACK message, for example, if one or more replies comprise an NACK message, the target cell may confirm that the selected component carrier is not applicable to be the PCC of the target cell, and remove the selected component carrier from the PCC candidates, such that the PCC candidates are updated. In this event, the target cell may perform method 400 again based on the updated PCC candidates.
  • the target cell confirms that the selected component carrier is applicable to be its PCC
  • the selected component carrier may be removed from the SCC pool of the target cell.
  • the target cell may send a notification message to its neighboring cells to notify such change.
  • FIG. 5 illustrates a flow chart of a method 500 for determining a SCC of the target cell based on the SCC pool according to embodiments of the invention.
  • the method 500 may be considered as an embodiment of step S203 of the method 200 described above with reference to Fig. 2.
  • a SCC of the target cell may be determined according to whether the SCC pool is empty when the PCC of the target cell does not meet the communication requirements.
  • this is only for the purpose of illustrating the principles of the present invention, rather than limiting the scope thereof.
  • step S501 whether the SCC pool is empty when the PCC of the target cell does not meet communication requirements is judged.
  • the target LPN may use one or more SCCs to increase the throughput.
  • a component carrier is determined from the SCC pool based on the interference list, as the SCC of the target cell.
  • the SCC may be determined from the SCC pool based on the interference list by: calculating an interference factor for each of SCC candidates in the SCC pool based on the interference list; and selecting, from the SCC candidates in the SCC pool, a component carrier which has a minimized interference factor as the SCC of the target cell.
  • the target cell may not directly use the selected component carrier, because it may cause sharp reduction of throughput of neighboring cells.
  • a request message may be sent from the target cell to the at least one neighboring cell, so that the target cell may confirm whether the selected component carrier is applicable to be the SCC of the target cell. Details for determination of a component carrier from the SCC pool as the SCC of the target cell may be found in embodiments in connection with FIG. 6.
  • a component carrier is determined from at least one SCC used by the at least one neighboring cell, as the SCC of the target cell.
  • a power reduction request message may be sent to the at least one neighboring cell, wherein the power reduction request message comprises identification of the target cell; a SCC of the target cell may be determined based on at least one agree to reduce power (A P) message from the at least one neighboring cell, wherein the ARP message comprises a SCC used by the neighboring cell; and transmit power of the target cell on the SCC of the target cell may be decreased, so as to reduce interference to the at least one neighboring cell. More details may be found in embodiments in connection with FIG. 7.
  • FIG. 6 illustrates a flow chart of a method 600 for determining a component carrier from the SCC pool based on the interference list as the SCC of the target cell according to embodiments of the invention.
  • the method 600 may be considered as an embodiment of step S502 of the method 500 described above with reference to Fig. 5. However, it is to be noted that this is only for the purpose of illustrating the principles of the present invention, rather than limiting the scope thereof.
  • an interference factor for each of SCC candidates in the SCC pool is calculated based on the interference list.
  • the interference factor for a SCC may be calculated in a similar way as the interference factor for a PCC. Specifically, the interference factor may be calculated based on PCC incoming interference, PCC outgoing interference, SCC incoming interference, and SCC outgoing interference, for example, according to equation (1). It is to be noted that, different from step S401, at step S601, the component carrier n is selected from the SCC pool, instead of the PCC candidates. In other words, when the interference factor is calculated with equation (1), n ⁇ SSC pool .
  • a component carrier which has a minimized interference factor is selected, from the SCC candidates in the SCC pool, as the SCC of the target cell.
  • the index i may be obtained by calculating the following:
  • a request message is sent to the at least one neighboring cell.
  • the request message may comprise: identification of the target cell, the selected component carrier, a priority level for using the selected component carrier by the target cell, and/or the like.
  • the priority level may be preset according to traffic amount, QoS level of service, and/or the like.
  • step S604 whether the selected component carrier is applicable to be the SCC of the target cell is confirmed based on at least one reply to the request message from the at least one neighboring cell.
  • the neighboring cell may make response according to a set of predetermined policies.
  • the predetermined policies may be defined with respect to different cases.
  • the neighboring cell if a neighboring cell only uses a PCC, the neighboring cell sends to the target cell a reply comprising an ACK message; if a neighboring cell is selecting a SCC which is the same as the selected component carrier, the neighboring cell compares its priority level with the priority level in the request message, and sends to the target cell a reply comprising an ACK message when the priority level in the request message is higher; and if a neighboring cell is selecting a SCC which is not the same as the selected component carrier, the neighboring cell sends to the target cell a reply comprising an ACK message.
  • the neighboring cell may send a reply comprising a NACK message.
  • the target cell may confirm the selected component carrier is applicable to be the SCC of the target cell. Otherwise, if one of the at least one reply does not comprise an ACK message, for example, if one or more replies comprise an NACK message, the target cell may confirm the selected component carrier is not applicable to be the SCC of the target cell, and remove the selected component carrier from the SCC pool, such that the SCC pool is updated. In this event, the target cell may repeat steps S601-S604 of method 600 again based on the updated SCC pool.
  • the target cell may send a notification message to its neighboring cells to notify such change.
  • FIG. 7 illustrates a flow chart of a method 700 for determining a component carrier from at least one SCC used by the at least one neighboring cell as the SCC of the target cell according to embodiments of the invention.
  • the method 700 may be considered as an embodiment of step S503 of the method 500 described above with reference to Fig. 5.
  • this is only for the purpose of illustrating the principles of the present invention, rather than limiting the scope thereof.
  • a power reduction request message is sent to the at least one neighboring cell.
  • the power reduction request message may comprise an identification of the target cell.
  • a SCC of the target cell is determined based on at least one agree to reduce power (ARP) message from the at least one neighboring cell.
  • the neighboring cell when a neighboring cell receives the power reduction request message from the target cell, the neighboring cell may determine whether to send an ARP message to the target cell. In an embodiment, if a neighboring cell uses both a PCC and a SCC, and if throughput of the neighboring cell exceeds a predetermined threshold, the neighboring cell may send an ARP message to the target cell.
  • the ARP message may comprise a SCC used by the neighboring cell.
  • the target cell may determine the SCC in the ARP message as a SCC of the target cell. If the target cell receives multiple ARP messages are received, the target cell may select a component carrier which is not the same as the PCC of the target cell from the SCCs in the ARP messages, as a SCC of the target cell.
  • the neighboring cell may not send a reply to the target cell; as an alternative, the neighboring cell may send a reply comprising a NACK message to the target cell.
  • the target cell may wait for a time period and retry method 700 later.
  • step S703 transmit power of the target cell on the SCC of the target cell is decreased, so as to reduce interference to the at least one neighboring cell.
  • the decreased transmit power of the target cell on the SCC of the target cell which is denoted as P low
  • P low the transmit power of the target cell on the SCC of the target cell
  • AC k indicates the difference between first throughput of cell k whose transmit power on CC i is initial transmit power and second throughput of cell k whose transmit power on CC i is the reduced transmit power P iow ;
  • ⁇ is an offset value, which may be predetermined according to system requirements and/or other factors.
  • C indicates the throughput of cell k on CC i;
  • M is the number of UEs in a cell.
  • AP ⁇ is the reduction of power on a component carrier i in cell k .
  • the target cell may send a notification message to its neighboring cells to notify such change.
  • the neighboring cell may reduce its transmit power to P low , and does not remove the component carrier from its SCC pool, wherein the reduced transmit power P Iow may be calculated according to equations (9) - (23), or may be obtained from the notification message sent from the target cell.
  • the neighboring cell may remove the component carrier from its SCC pool.
  • the SCC pool may be updated as shown in the following Table 3.
  • the target cell when the target cell receives a notification message which indicates that some neighboring cell has selected a PCC, the target cell may remove this component carrier from its SCC pool.
  • the target cell may check if the component carrier is still be used in the Interference List (IL). If it is still be used, the target cell may do nothing, if it is not used, the target cell may add this component carrier to its SCC pool.
  • IL Interference List
  • the target cell When the target cell receives the notification message which indicates that a neighboring cell has selected a SCC, further judgment may be made as follows. If the target cell works on PCC only, it may remove this component carrier from its SCC pool; if the target cell works on PCC and SCC, and if the component carrier in this message is the same as the SCC of target cell, the target cell may reduce its power on this SCC to P low ; and if the component carrier in this message is different from the SCC of target cell, the target cell may remove this component carrier from its SCC pool.
  • the target cell When the target cell receives the notification message which indicates that a neighboring cell has released its SCC, further judgment may be made as follows. If the target cell only works on PCC, it checks whether the component carrier is still be used in the Interference List. If it is still be used, the target cell may do nothing; if it is not used, it may add this component carrier to its SCC pool. If the target cell works on both the PCC and the SCC, it checks whether the component carrier is still be used in the Interference List. If it is still be used, the target cell may do nothing; otherwise, if it is not used, the target cell makes the following judgment. If the component carrier in this message is the same as the SCC of target cell, the target cell may increase its power on this SCC to an initial transmit power, and if they are different, the target cell may add this component carrier to its SCC pool.
  • FIG. 8 illustrates a block diagram of an apparatus 800 for selecting a component carrier in a small cell network according to embodiments of the invention.
  • the apparatus 800 may be implemented at a LPN (e.g., a HeNB shown in FIG. 1) which controls a target cell or some other suitable device, or may be implemented at an apparatus comprised in the LPN or some other suitable device.
  • LPN e.g., a HeNB shown in FIG. 1
  • the apparatus 400 comprises: an establishing unit 810 configured to establish an interference list and a SCC pool, wherein the interference list comprises information about at least one neighboring cell of a target cell, and the SCC pool comprises SCC candidates of the target cell; a primary determining unit 820 configured to determine a PCC of the target cell based on the interference list; and a secondary determining unit 830 configured to determine a SCC of the target cell based on the SCC pool when the PCC of the target cell does not meet communication requirements.
  • the establishing unit may comprise: a receiving unit configured to receive at least one notification message from the at least one neighboring cell, wherein a notification message may comprise information about adding or release of a PCC and/or at least one SCC in a neighboring cell; a signal strength obtaining unit configured to obtain reference signal strength of the at least one neighboring cell; an interference list establishing unit configured to establish the interference list based on the at least one notification message and the reference signal strength; and a SCC pool establishing unit configured to establish the SCC pool based on the at least one notification message.
  • the interference list establishing unit may comprise: an identification obtaining unit configured to obtain identifications of a PCC and/or at least one SCC used by a neighboring cell based on the notification message sent from the neighboring cell; an estimating unit configured to estimate pathloss from the target cell to the neighboring cell based on the reference signal strength; and a creating unit configured to create the interference list based on the identifications, the reference signal strength, and the pathloss.
  • the primary determining unit 820 may comprise: a PCC calculating unit configured to calculate an interference factor for each of PCC candidates based on the interference list; and a PCC selecting unit configured to select, from the PCC candidates, a component carrier which has a minimized interference factor as the PCC of the target cell.
  • the PCC calculating unit may comprise: a first interference obtaining unit configured to obtain PCC incoming interference from a neighboring cell which uses a PCC candidate as its PCC to the target cell, and PCC outgoing interference from the target cell to the neighboring cell which uses the PCC candidate as its PCC; a second interference obtaining unit configured to obtain SCC incoming interference from a neighboring cell which uses the PCC candidate as its SCC to the target cell, and SCC outgoing interference from the target cell to the neighboring cell which uses the PCC candidate as its SCC; and a PCC computing unit configured to compute an interference factor for the PCC candidate based on the PCC incoming interference, the PCC outgoing interference, the SCC incoming interference, and the SCC outgoing interference.
  • the PCC selecting unit may comprise: a PCC determining unit configured to, if more than one component carrier has a minimized interference factor, determine a component carrier from the more than one component carrier as the PCC of the target cell, such that the number of neighboring cells that use the determined component carrier is minimal.
  • the PCC selecting unit may comprise: a first sending unit configured to send a request message to the at least one neighboring cell, wherein the request message may comprise identification of the target cell, the selected component carrier, and a priority level for using the selected component carrier by the target cell; and a PCC confirming unit configured to confirm whether the selected component carrier is applicable to be the PCC of the target cell, based on at least one reply to the request message from the at least one neighboring cell.
  • the neighboring cell if a neighboring cell is working normally and its PCC is the same as the selected component carrier, and if interference caused when the selected component carrier is used as the PCC of the target cell is less than first tolerance of the neighboring cell, the neighboring cell sends to the target cell a reply comprising an ACK message; if a neighboring cell is working normally and its SCC is the same as the selected component carrier , and if interference caused when the selected component carrier is used as the PCC of the target cell is less than second tolerance of the neighboring cell, the neighboring cell sends to the target cell a reply comprising an ACK message; if a neighboring cell is working normally and neither its PCC nor its SCC is the same as the selected component carrier, the neighboring cell sends to the target cell a reply comprising an ACK message; if a neighboring cell is initializing and selecting its PCC, and if its PCC is not the same as the selected component carrier, the neighboring cell sends to the target cell a reply
  • the PCC confirming unit may comprise: a first confirming unit configured to, if each of the at least one reply may comprise an ACK message, confirm that the selected component carrier is applicable to be the PCC of the target cell; and a second confirming unit configured to, if one of the at least one reply does not comprise an ACK message, confirm that the selected component carrier is not applicable to be the PCC of the target cell, and remove the selected component carrier from the PCC candidates.
  • the first confirming unit may comprise: a removing unit configured to remove the selected component carrier from the SCC pool.
  • the secondary determining unit 830 may comprise: a judging unit configured to judge whether the SCC pool is empty when the PCC of the target cell does not meet communication requirements; a first SCC determining unit configured to, if the SCC pool is not empty, determine a component carrier from the SCC pool based on the interference list, as the SCC of the target cell; and a second SCC determining unit configured to, if the SCC pool is empty, determining a component carrier from at least one SCC used by the at least one neighboring cell, as the SCC of the target cell.
  • the first SCC determining unit may comprise: a SCC calculating unit configured to calculate an interference factor for each of SCC candidates in the SCC pool based on the interference list; and a SCC selecting unit configured to select, from the SCC candidates in the SCC pool, a component carrier which has a minimized interference factor as the SCC of the target cell.
  • the SCC selecting unit may comprise: a second sending unit configured to send a request message to the at least one neighboring cell, wherein the request message may comprise identification of the target cell, the selected component carrier, and a priority level for using the selected component carrier by the target cell; and a SCC confirming unit configured to confirm whether the selected component carrier is applicable to be the SCC of the target cell, based on at least one reply to the request message from the at least one neighboring cell.
  • the neighboring cell if a neighboring cell only uses a PCC, the neighboring cell sends to the target cell a reply comprising an ACK message; if a neighboring cell is selecting a SCC which is the same as the selected component carrier, the neighboring cell compares its priority level with the priority level in the request message, and sends to the target cell a reply comprising an ACK message when the priority level in the request message is higher; and if a neighboring cell is selecting a SCC which is not the same as the selected component carrier, the neighboring cell sends to the target cell a reply comprising an ACK message.
  • the SCC confirming unit may comprise: a third confirming unit configured to, if each of the at least one reply may comprise an ACK message, confirm the selected component carrier is applicable to be the SCC of the target cell; and a fourth confirming unit configured to, if one of the at least one reply does not comprise an ACK message, confirm the selected component carrier is not applicable to be the SCC of the target cell, and remove the selected component carrier from the SCC pool.
  • the second SCC determining unit may comprise: a third sending unit configured to send a power reduction request message to the at least one neighboring cell, wherein the power reduction request message may comprise an identification of the target cell; a third SCC determining unit configured to determine a SCC of the target cell based on at least one agree to reduce power (ARP) message from the at least one neighboring cell, wherein the ARP message may comprise a SCC used by the neighboring cell; and a decreasing unit configured to decrease transmit power of the target cell on the SCC of the target cell, so as to reduce interference to the at least one neighboring cell.
  • ARP agree to reduce power
  • a neighboring cell uses both a PCC and a SCC, and if throughput of the neighboring cell exceeds a predetermined threshold, the neighboring cell sends an ARP message to the target cell.
  • the third SCC determining unit may be further configured to: if only one ARP message is received and the SCC in the ARP message is not the same as the PCC of the target cell, determine the SCC in the ARP message as a SCC of the target cell; and if multiple ARP messages are received, select a component carrier which is not the same as the PCC of the target cell from the SCCs in the ARP messages, as a SCC of the target cell.
  • the apparatus 800 may be configured to implement functionalities as described with reference to FIGs. 2-7. Therefore, the features discussed with respect to any of methods 200 to 700 may apply to the corresponding components of the apparatus 800. It is further noted that the components of the apparatus 800 may be embodied in hardware, software, firmware, and/or any combination thereof. For example, the components of the apparatus 800 may be respectively implemented by a circuit, a processor or any other appropriate selection device. Those skilled in the art will appreciate that the aforesaid examples are only for illustration not limitation.
  • the apparatus 800 comprises at least one processor.
  • the at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors already known or developed in the future.
  • the apparatus 800 further comprises at least one memory.
  • the at least one memory may include, for example, semiconductor memory devices, e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices.
  • the at least one memory may be used to store program of computer executable instructions.
  • the program can be written in any high-level and/or low-level compilable or interpretable programming languages.
  • the computer executable instructions may be configured, with the at least one processor, to cause the apparatus 800 to at least perform according to any of methods 200 to 700 as discussed above.
  • the present disclosure may be embodied in an apparatus, a method, or a computer program product.
  • the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.
  • some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto.
  • FIGs. 2-7 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s).
  • At least some aspects of the exemplary embodiments of the disclosures may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, FPGA or ASIC that is configurable to operate in accordance with the exemplary embodiments of the present disclosure.

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Abstract

Des modes de réalisation de l'invention concernent des procédés et des appareils de sélection d'une composante porteuse dans un réseau de petites cellules. Dans un procédé selon des modes de réalisation de la présente invention : une liste d'interférences et un groupe de SCC sont créés, la liste d'interférences contenant des informations sur au moins une cellule voisine d'une cellule cible, et le groupe de SCC comprenant des SCC candidates de la cellule cible; une PCC de la cellule cible est déterminée d'après la liste d'interférences; et une SCC de la cellule cible est déterminée d'après le groupe de SCC quand la PCC de la cellule cible ne répond pas aux exigences de communication.
PCT/CN2014/070299 2014-01-08 2014-01-08 Procédé et appareil de sélection de composante porteuse dans un réseau de petites cellules WO2015103742A1 (fr)

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