Cellular telecommunications network

Abstract

The present invention provides a method in a cellular telecommunications network comprising a plurality of transceivers and a node for implementing said method, the method comprising the steps of: obtaining data indicative of respective physical cell identifiers, PCIs, of a first transceiver and a second transceiver of the plurality of transceivers, and also indicating a current neighborhood relationship between the first transceiver and the second transceiver, the current neighborhood relationship between the first transceiver and the second transceiver having a specific order; identifying a first potential PCI conflict for the first transceiver and the second transceiver from the obtained data in the event that the order of the current neighbor relationships between the first transceiver and the second transceiver decreases; identifying a solution for the first potential PCI conflict; and causing a reconfiguration in the cellular telecommunications network to implement the identified solution.

Description

Technical Field

[0001] The present invention relates to cellular telecommunication networks. Background Art

[0002] A Physical Cell Identifier (PCI) is an identifier of a cell of a base station in a cellular telecommunications network. The PCI is broadcast in a physical layer transmission so that any user in the cellular network receiving the physical layer transmission can determine the PCI of the cell (even if the user is connected to another cell).

[0003] PCIs are assigned to cells in a cellular network from a limited range (504 in LTE and 1008 in 5G). PCIs must be assigned carefully to avoid PCI conflicts. One form of PCI conflict is called a PCI collision, where two cells with overlapping coverage areas have the same PCI, making it impossible for users in the overlapping coverage area to distinguish between the two cells. Another form of PCI conflict is called PCI confusion, where a cell includes two neighboring cells with the same PCI. PCI conflicts are known to result in poor user experience, such as increased interference or failed handovers.

[0004] Typically, PCI assignments are performed manually to avoid these PCI conflicts. However, as the density of cellular networks increases due to increased deployment of small cells (eg, femto cells), PCI conflicts may become more common and difficult to manage by manually assigning PCIs by mobile network operators.

[0005] In particular, the introduction of the Self-Organizing-Network (SON) capability in small cells enables the cell to self-allocate its PCI. This is usually achieved by the cell discovering the PCI of its neighboring cells through the Automatic Neighbour Relations (ANR) process, such as by obtaining data identifying neighboring cells from users in measurement reports, or by using Radio Environment Monitoring (REM) scanning to detect neighboring cells and allocate their PCIs based on the PCIs of their neighboring cells. SON PCI allocation technology facilitates the large-scale deployment of small cells without increasing the PCI allocation burden on mobile network operators.

[0006] Another feature related to PCI selection is PCI pooling. This is a technique for allocating PCIs from a specific PCI set to cells based on their categories (e.g., macro cells, pico cells, femto cells, etc.). This allows a cell to identify the category of a neighboring cell from its PCI and self-allocate a PCI that avoids collisions with PCIs of neighboring cells of different categories.

[0007] The trend towards network densification due to large deployments of small cells, increased use of SON-based PCI allocation, and PCI pooling from a limited PCI range means that PCI conflicts are more likely to occur. Summary of the invention

[0008] According to a first aspect of the present invention, there is provided a node for a cellular telecommunication network, the cellular telecommunication network comprising a plurality of transceivers, the node comprising: a transceiver configured to obtain data indicating respective physical cell identifiers PCIs of a first transceiver and a second transceiver of the plurality of transceivers, and also indicating a current neighbor relation between the first transceiver and the second transceiver, the current neighbor relation between the first transceiver and the second transceiver having a specific order; and a processor configured to: in a case where the order of the current neighbor relation between the first transceiver and the second transceiver decreases, identify a first potential PCI conflict between the first transceiver and the second transceiver of the plurality of transceivers from the obtained data, identify a solution to the first potential PCI conflict, and cause the cellular telecommunication network to be reconfigured to implement the identified solution.

[0009] In other words, the node comprises: a transceiver configured to obtain data indicating respective physical cell identifiers PCIs of a first transceiver and a second transceiver of a plurality of transceivers, and also indicating a current neighbor relation between the first transceiver and the second transceiver, the current neighbor relation having a specific order; and a processor configured to: identify, from the obtained data, a first potential PCI conflict between the first transceiver and the second transceiver of the plurality of transceivers in a case where the order of the current neighbor relation decreases, identify a solution to the first potential PCI conflict, and cause the cellular telecommunication network to be reconfigured to implement the identified solution.

[0010] The current neighbor relationship may indicate that the first transceiver and the second transceiver are second-order neighbors, and the first potential PCI conflict may occur when the first transceiver and the second transceiver are reconfigured from second-order neighbors to first-order neighbors, wherein the first-order neighbors are direct neighbors and the second-order neighbors are direct neighbors of the first-order neighbors rather than first-order neighbors.

[0011] The current neighbor relationship may indicate that the first transceiver and the second transceiver are third-order neighbors, and the first PCI conflict may occur when the first transceiver and the second transceiver are reconfigured from third-order neighbors to first-order neighbors or second-order neighbors, wherein the first-order neighbor is a direct neighbor, the second-order neighbor is a direct neighbor of the first-order neighbor instead of the first-order neighbor, and the third-order neighbor is a direct neighbor of the second-order neighbor instead of the first-order neighbor or the second-order neighbor.

[0012] The transceiver can also be configured to: obtain data indicating the corresponding PCIs of a third transceiver and a fourth transceiver among multiple transceivers, and also indicate a current neighbor relationship between the third transceiver and the fourth transceiver, the current neighbor relationship between the third transceiver and the fourth transceiver having a specific order, and wherein the processor is further configured to: identify a second potential PCI conflict between the third transceiver and the fourth transceiver among the multiple transceivers from the obtained data when the order of the current neighbor relationship between the third transceiver and the fourth transceiver is reduced; and determine that the solution priority of the first potential PCI conflict is greater than the solution priority of the second potential PCI conflict.

[0013] The resolution priority may be based on one or more of a group comprising: an order of neighbor relations of the respective transceivers such that relatively lower-order neighbor relations have greater resolution priority than relatively higher-order neighbor relations; a severity of a potential PCI conflict; energy saving characteristics of the first transceiver, the second transceiver, the third transceiver, and / or the fourth transceiver; and, in the case where the first transceiver and the second transceiver are remote units and the cellular telecommunication network is a decomposed radio access network, an identifier of a first distributed node of the first transceiver and an identifier of a second distributed node of the second transceiver.

[0014] The energy saving characteristic may be one or more of a current energy saving state and an energy saving capability.

[0015] The solution may be one or more items in a group including: changing the PCI of one or more transceivers among the plurality of transceivers; limiting the operation mode of one or more transceivers among the plurality of transceivers, wherein the operation mode is one of a power saving mode, a normal mode, and a compensation mode; limiting the transmit power of one or more transceivers among the plurality of transceivers; and disabling one or more transceivers among the plurality of transceivers.

[0016] The node may be one of the group consisting of: a controller and a transceiver of a plurality of transceivers.

[0017] According to a second aspect of the present invention, there is provided a method in a cellular telecommunication network, the cellular telecommunication network comprising a plurality of transceivers, the method comprising the following steps: obtaining data indicating respective physical cell identifiers PCIs of a first transceiver and a second transceiver of the plurality of transceivers, and also indicating a current neighbor relation between the first transceiver and the second transceiver, the current neighbor relation between the first transceiver and the second transceiver having a specific order; identifying a first potential PCI conflict between the first transceiver and the second transceiver from the obtained data in a case where the order of the current neighbor relation between the first transceiver and the second transceiver decreases; identifying a solution to the first potential PCI conflict; and causing the cellular telecommunication network to be reconfigured to implement the identified solution.

[0018] According to a third aspect of the present invention, there is provided a computer program comprising instructions to enable the node of the first aspect of the present invention to perform the steps of the method of the second aspect of the present invention. The computer program may be stored on a computer readable medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to better understand the present invention, embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0020] Figure 1 is a schematic diagram of a cellular telecommunications network;

[0021] Figure 2 yes Figure 1 A schematic diagram of a base station of a network;

[0022] Figure 3 yes Figure 1 A schematic diagram of a controller of a network;

[0023] Figure 4 is a flow chart showing a first process;

[0024] Figure 5 is a flow chart showing the second process;

[0025] Figure 6 is a flow chart showing a third process;

[0026] Figure 7 is a schematic diagram of a cellular telecommunications network;

[0027] Figure 8 is a flowchart showing a fourth process; and

[0028] Fig. 9 is a flowchart showing the fifth process. DETAILED DESCRIPTION

[0029] Figure 1A cellular telecommunication network 100 is shown. The cellular telecommunication network 100 comprises a first base station 110, a second base station 120, a third base station 130 and a fourth base station 140. The first base station 110, the second base station 120, the third base station 130 and the fourth base station 140 each have a single respective transceiver configured to communicate in a respective coverage area (in other words, each base station is a single cell base station). The first base station 110, the second base station 120, the third base station 130 and the fourth base station 140 communicate using the same frequency.

[0030] As shown in the figure, the first base station 110 and the second base station 120 have partially overlapping coverage areas, the second base station 120 and the third base station 130 have partially overlapping coverage areas, and the third base station 130 and the fourth base station 140 have partially overlapping coverage areas. Note the following terms regarding the neighboring relationships between these base stations. From the perspective of the first base station 110, the second base station 120 is a "first-order neighbor" because it has a partially overlapping coverage area with the first base station 110; the third base station 130 is a "second-order neighbor" because it is a first-order neighbor of the first-order neighbor of the first base station 110 (i.e., the second base station 120), and it itself is not a first-order neighbor of the first base station 110; and the fourth base station 140 is a "third-order neighbor" because it is a first-order neighbor of the second-order neighbor of the first base station 110 (i.e., the third base station 130), and it itself is not a first-order neighbor or a second-order neighbor of the first base station 110. For completeness, the following table indicates Figure 1 The neighbor relationship of the base station shown in:

[0031]

[0032] Each of the first base station 110 , the second base station 120 , the third base station 130 , and the fourth base station 140 may be connected to one or more user equipments (UE) (not shown).

[0033] Figure 1 A controller 150 is also shown. The controller 150 is shown as part of the core network, but in other implementations, the controller 150 may be part of a radio access network (e.g., in an open radio access network (OpenRAN) architecture). The controller 150 is connected (directly or indirectly) to each of the first base station 110, the second base station 120, the third base station 130, and the fourth base station 140.

[0034] exist Figure 21. The first base station 110 is shown in more detail in FIG. The first base station 110 comprises a first communication interface 111, a memory module 113, a processing module 115 and a second communication interface 117, all connected via a communication bus 119. The first communication interface 111 is connected to a transceiver for wireless communication with a UE. The second communication interface 117 is a wired (e.g., optical fiber) connection to a core network including a controller 150 of the cellular telecommunication network 100.

[0035] The first base station 110 is identified by (at least) a physical cell identifier (PCI). The PCI is transmitted by the first base station 110 in a physical layer broadcast transmission so that it can be decoded by any UE in the cellular telecommunication network 100 (including UEs connected to the first base station 110 and UEs not connected to the first base station 110).

[0036] The memory module 113 stores a Neighbour Relation Table (NRT) identifying one or more other base stations in the cellular telecommunication network 100. The first base station 110 is configured to populate the NRT in the following manner:

[0037] 1. receiving a measurement report identifying another base station in the cellular telecommunication network 100 from a UE connected to the first base station 110, and adding the other base station to the NRT; and / or

[0038] 2. Perform a Radio Environment Monitoring (REM) scan (via the first communication interface 111) to detect another base station in the cellular telecommunication network 100, and add the other base station to the NRT.

[0039] These measurement reports and REM scans may identify PCIs that have not yet been recorded in the NRT. In this case, it is assumed that the PCI is sent by a neighboring cell that has not yet been identified in the NRT. In response, the first base station 110 creates a new record for the neighboring cell in the NRT and determines its unique identifier (global cell ID).

[0040] The first base station 110 is also configured to transmit its NRT to the controller 150. This may be performed periodically or in response to a trigger (eg, the NRT is updated).

[0041] The second base station 120, the third base station 130, and the fourth base station 140 operate in a similar manner to send their respective PCIs, fill their respective NRTs, and transmit their respective NRTs to the controller 150. Figure 1As shown, the first base station 110 uses PCI 7, the second base station 120 uses PCI 8, the third base station 130 uses PCI 9, and the fourth base station 140 uses PCI 7.

[0042] Figure 3 150 is shown in more detail in FIG. The controller includes a first communication interface 151, a memory module 153, and a processing module 155, all of which are connected via a communication bus 157. The first communication interface 151 is a wired (e.g., optical fiber) connection (directly or indirectly) connected to each of the first base station 110, the second base station 120, the third base station 130, and the fourth base station 140. The first communication interface 151 can also enable the controller 150 to communicate with other networked nodes including other controllers in the case of performing a process (described below) in a distributed environment. The memory module 153 stores a combined NRT filled with data of the NRT received from each of the first base station 110, the second base station 120, the third base station 130, and the fourth base station 140. Therefore, the combined NRT can identify the first-order neighboring area, the second-order neighboring area, and the third-order neighboring area of ​​each base station for each base station. The processing module 155 is configured to perform the first process and / or the second process described below.

[0043] We will now describe Figure 4 The first process is shown in the flowchart of FIG. This process is executed by the controller 150 and involves the following steps: Figure 1 The cellular network 100 shown. In the first step (S101), the controller 150 triggers the PCI (re) allocation process. The trigger may be in response to an event (e.g., the controller 150 receives a message indicating a change in the PCI of any one of the base stations in the network 100 or a change in the neighbor relationship between the base stations from one or more of the first base station 110, the second base station 120, the third base station 130, and the fourth base station 140, or a PCI (re) allocation event triggered within the controller 150 or the core network), or the trigger may be time-based (such as the expiration of a timer). If there is a change in PCI or neighbor relationship between base stations, the combined NRT is updated to incorporate these changes.

[0044] In step S103, the controller 150 analyzes the current PCI allocations for each base station in the network 100 and the current neighbor relations between each pair of base stations in the network 100. This is achieved by entering an iterative loop, wherein, in each iteration, the current PCI allocations and the current neighbor relations are analyzed to identify one or more base station pairs having a particular combination of PCI allocations and neighbor relations. Each iteration is associated with a particular combination of PCI allocations and neighbor relations, which is ranked by the severity of the actual (or potential) degradation of network performance by that combination of PCI allocations and neighbor relations. These severity levels are listed in the following table:

[0045]

[0046]

[0047] These PCI relationships include those current PCI conflicts that are known to result in degraded network performance (e.g., Severity Level 1, Severity Level 2, Severity Level 4, Severity Level 5, and Severity Level 6 relationships), and those potential PCI conflicts that would achieve degraded network performance if a high-order neighbor is reconfigured to a low-order neighbor (e.g., Severity Level 3 and Severity Level 7 to Severity Level 16 PCI conflict types). In the first example, such a reconfiguration may be due to a higher-order neighbor transmitting at a different transmit power in order to change its coverage area to a lower-order neighbor (such as when a base station compensates for a base station entering power saving mode), or in the second example, the higher-order neighbor is a mobile base station that moves to another location in order to change its coverage area to a lower-order neighbor. Thus, these potential PCI conflict types cover scenarios in which two base stations with the same PCI value (or related PCI values) have satisfactory performance within their current respective coverage areas, but would have unsatisfactory performance if the two base stations were reconfigured to low-order neighbors.

[0048] Apply this step to Figure 1 In the cellular network 100 of FIG. 1 , in a first iteration loop, the controller 150 determines whether there is a relationship of severity level 1 in the network 100. Since there are no first-order neighbors with the same PCI value, the determination is negative. Therefore, the controller 150 enters a second iteration loop and determines whether there is a relationship of severity level 2 in the network 100. There are also no second-order neighbors with the same PCI value, so the determination is negative. Therefore, the controller 150 enters a third iteration loop and determines whether there is a relationship of severity level 3 in the network 100. Since the first base station 110 and the fourth base station 140 are third-order neighbors and have the same PCI value, the determination is positive.

[0049] In response to the affirmative determination of step S103, the controller 150 identifies a suitable solution (step S105). Since the relationship identified in step S103 is a relationship with a potential PCI conflict, the PCI reallocation is a preferred solution to the PCI conflict that will occur if one or both base stations in the identified base station pair (the first base station 110 and the fourth base station 140) are reconfigured so that the base station pair has a lower-order neighbor relationship. The preferred solution may be one or more of the following:

[0050] · reallocating one or more PCIs in the cellular network 100; and

[0051] • Ensure that one or both base stations in the identified base station pair cannot be reconfigured as a lower order neighbor cell.

[0052] Any preferred solution to reallocating one or more PCIs in the cellular network 100 may be to reallocate the PCI of one or both base stations in the identified base station pair and / or one or more other base stations. The reallocated PCIs should not create a relationship with a higher severity level, but may create a relationship with a lower severity level. In this example, the PCIs of the first base station 110 and / or the fourth base station 140 may be changed so that the first base station 110 and the fourth base station 140 no longer have the same PCI, but not so that one or both of the first base station 110 and the fourth base station 140 use PCI 8 or PCI 9 (such as creating a PCI relationship of severity level 1 or 2). After this reconfiguration, one or both base stations in the identified base station pair may be reconfigured as a lower order neighbor.

[0053] The preferred solution to ensure that one or both base stations in the identified base station pair cannot be reconfigured as a lower order neighbor cell may include one or more of the following:

[0054] · shutting down one or both base stations in the identified base station pair or instructing them to enter a power saving mode;

[0055] The transmit power of one or both base stations in the identified base station pair is limited so that they cannot become lower-order neighbors; and

[0056] • Preventing one or both base stations in the identified pair of base stations from entering backoff mode.

[0057] These priority solutions ensure that one or both base stations cannot be reconfigured to a lower order neighbor (and may involve the base stations continuing to use their current PCIs). These restrictions may also identify acceptable states for each base station in the network based on other base stations in the network (e.g., one base station may enter backoff mode only if another base station is not in backoff mode) to avoid PCI conflicts that would otherwise occur.

[0058] After identifying a suitable solution in step S105, the controller 150 determines whether there are further relationship severity levels to be analyzed. Since severity levels 4 to 16 have not yet been analyzed, the controller 150 iteratively analyzes each severity level and, if there is a relationship at that severity level, identifies a suitable solution that does not create a relationship at a higher severity level. In this example, no further relationships are identified, and the controller 150 proceeds to step S107, in which the controller instructs one or more base stations in the network 100 to implement the identified solution. This can be achieved by sending corresponding messages to each base station involved in the identified solution, which messages cause each corresponding base station to implement a respective portion of the identified solution.

[0059] Figure 4 The process enables the network 100 to prioritize resolving one or more PCI conflicts that would degrade network performance in the event of a change in neighbor relationships in the network. Conventional PCI allocation processes typically allocate PCIs to base stations so that there are no PCI conflicts for the current corresponding coverage area of ​​each base station. However, because the cellular network 100 implements technology that enables one or more base stations to change their respective coverage areas (such as mobile base stations or compensation base stations that are energy-saving base stations), these allocated PCIs may still result in PCI conflicts when one or more base stations change their respective coverage areas. Although this can be resolved by detecting PCI conflicts and reallocating PCIs in response, Figure 4 The process provides a priority solution so that potential PCI conflicts do not occur when one or more base stations change their respective coverage areas.

[0060] also, Figure 4 The process prioritizes solutions for relationships based on the actual or potential performance degradation of each relationship. That is, solutions are sorted by severity level so that solutions for relationships with greater actual or potential performance degradation are prioritized.

[0061] We will now describe Figure 5 The second process is also executed by the controller 150 and also involves Figure 1The cellular network 100 shown. In this second process, the controller 150 additionally stores data related to the energy-saving state of each base station in the network 100. Each base station in the network 100 can operate in normal mode, energy-saving mode (in which it enters an energy-saving state), or compensation mode (in which it compensates for another base station entering an energy-saving mode). Conventionally, base stations are configured to switch between normal mode and energy-saving mode, or between normal mode and compensation mode. One or more base stations in the network 100 may be configured to operate only in normal mode. The data stored by the controller 150 identifies, for each base station, its current energy-saving state (normal, energy-saving, or compensation mode) and its potential energy-saving state (normal, energy-saving, or compensation mode). This data can be transmitted from each base station to the controller 150 (e.g., as part of an NRT update message).

[0062] In a first step of this second process (S201), the controller 150 triggers a PCI (re)assignment process. The trigger may be in response to an event or may be time-based.

[0063] In step S203, the controller 150 analyzes the current PCI allocation of each base station in the network 100, the current neighbor relationship between each pair of base stations in the network 100, and the energy-saving state of each base station in the network 100. This second process introduces the concept of energy-saving priority groups. Energy-saving priority groups refer to the energy-saving state of a base station, such as its current energy-saving state and its potential energy-saving state (i.e., the energy-saving state of the base station when the demand in the network is low). Energy-saving priority groups are defined as follows:

[0064] Energy saving priority group Potential energy saving state Current energy saving status 1 Compensation Mode Compensation Mode 2 Compensation Mode Normal Mode 3 Normal Mode Normal Mode 4 Energy saving mode Normal Mode 5 Energy saving mode Energy saving mode

[0065] exist Figure 1 In the example shown, the first base station 110 and the fourth base station 140 are in energy saving priority group 2 (they are currently in normal mode, but can operate in compensation mode when network demand is low), and the second base station 120 and the third base station 130 are in energy saving priority group 4 (they are currently in normal mode, but can operate in energy saving mode when network demand is low).

[0066] In the following analysis, the concept of "maximum energy saving priority group" is also defined to indicate the maximum energy saving priority group of base station pairs identified as having a specific combination of PCI allocation and neighbor relationship. Figure 1 In the example shown, the first base station 110 and the fourth base station 140 are third-order neighboring cells with the same PCI, and the maximum energy saving priority group of the base station pair is 2.

[0067] Back to Figure 5In step S203, the controller 150 enters an iterative loop, wherein in each iteration, the controller 150 analyzes the current PCI allocation and the current neighbor relationship to identify one or more base station pairs having a specific combination of PCI allocation and neighbor relationship, and further determines whether the maximum energy saving priority group of any identified base station pair is equal to a specific value. These iterations are again ranked by the severity of the actual (or potential) degradation of network performance by the combination of PCI allocation, neighbor relationship and maximum energy saving priority group. These severity levels are listed in the following table:

[0068]

[0069]

[0070] For the sake of brevity, further severity levels and corresponding relationships are not shown (and the severity level of each maximum energy saving priority group, and each combination of PCI relationship and neighbor relationship, or a subset thereof, may additionally be covered in the table of the first process).

[0071] Will Figure 5 The process is applied to Figure 1 In the network shown, the controller 150 does not identify any base station pairs having a combination of PCI allocation, neighbor relationship and maximum energy saving priority group with severity levels 1 to 5, but instead identifies base station pairs having a combination of PCI allocation, neighbor relationship and maximum energy saving priority group with severity level 6 (i.e., the first base station 110 and the fourth base station 140 are third-order neighboring cells with the same PCI value, and the maximum energy saving priority group of the first base station 110 and the fourth base station 140 is 2).

[0072] Then, the process proceeds to step S205, in which a suitable solution is identified to preferentially resolve the potential PCI conflict. The controller 150 may identify a solution involving one or more of the following: reallocating one or more PCIs in the cellular network 100, and ensuring that one or both base stations in the identified base station pair cannot be reconfigured as a lower-order neighboring cell. The solution may be based on the energy-saving state of the base station, so that the base station in the identified base station pair with a relatively low energy-saving priority group mainly suffers any performance degradation caused by the solution (for example, if the first base station in the identified base station pair has energy-saving priority group 1 and the second base station in the identified base station pair has energy-saving priority group 2, then the solution will mainly sacrifice the performance of the second base station, such as by limiting the transmit power of the second base station or reallocating the PCI in the network so that the PCI conflict of the second base station is more serious than any PCI conflict of the first base station). In other words, any performance change as a result of the solution ensures that the performance of the base station of the identified base station pair with a relatively high energy-saving priority group is better than the performance of the base station of the identified base station pair with a relatively low energy-saving priority group.

[0073] In step S207 , the controller 105 instructs one or more base stations in the network 100 to implement the identified solution.

[0074] Therefore, by considering the current energy-saving state and the potential energy-saving state of the base stations involved in the identified relationship, the second process can prioritize solutions that favor the performance of base stations that contribute more to the overall network performance. That is, other base stations that are currently in compensation mode or configured to compensate for entering energy-saving mode contribute more to the overall network performance (e.g., in terms of the number of users served and throughput) than base stations that are in energy-saving mode or configured to enter energy-saving mode. Therefore, any solution that prioritizes resolving a potential PCI conflict involving a reduction in the performance of one of the base stations involved in the potential PCI conflict should prioritize the performance of base stations that are more likely to compensate for one or more other base stations.

[0075] Now refer to Figure 7 The network 200 shown describes Figure 6 The third process shown. Figure 7A network 200 is shown with a controller 250, a first base station 210, a second base station 220, a third base station 230, a fourth base station 240, and a fifth base station 250. As shown, the first base station 210 and the second base station 220 have partially overlapping coverage areas, the second base station 220 and the third base station 230 have partially overlapping coverage areas, the third base station 230 and the fourth base station 240 have partially overlapping coverage areas, and the fourth base station 240 and the fifth base station 250 have partially overlapping coverage areas. The third process may be performed by the controller 250.

[0076] In this third process, the controller 250 stores data about the PCI allocation and energy saving state of each base station in the network 200. The energy saving state data stored by the controller 250 identifies, for each base station, its current energy saving state (normal, energy saving, or compensation mode) and its potential energy saving state (normal, energy saving, or compensation mode). This data can be transmitted from each base station to the controller 250. The controller 250 can identify an energy saving priority group for each base station in the network 200. As described above, the energy saving priority group relates to the energy saving state of the base station, such as its current energy saving state and its potential energy saving state. The energy saving priority groups are defined in the following table:

[0077] Energy saving priority group Potential energy saving state Current energy saving status 1 Compensation Mode Compensation Mode 2 Compensation Mode Normal Mode 3 Normal Mode Normal Mode 4 Energy saving mode Normal Mode 5 Energy saving mode Energy saving mode

[0078] exist Figure 7 In the network, the first base station 210 uses PCI 7 and is in energy saving priority group 4, the second base station 220 uses PCI 8 and is in energy saving priority group 3, the third base station 230 uses PCI 7 and is in energy saving priority group 3, the fourth base station 240 uses PCI 9 and is in energy saving priority group 3, and the fifth base station 250 uses PCI 7 and is in energy saving priority group 2.

[0079] In the first step of the third process (S301), the controller 250 triggers the PCI (re)assignment process. The trigger may be in response to an event (such as a change in the PCI or energy saving state of a base station in the network 200) or may be time-based.

[0080] In step S303, the controller 250 analyzes the current PCI allocations in the network to identify multiple PCI conflicts. Figure 7In the network shown, the controller 150 identifies a first PCI conflict between the first base station 210 and the third base station 230 (second-order neighbor cells with the same PCI), and further identifies a second PCI conflict between the third base station 230 and the fifth base station 250 (again, second-order neighbor cells with the same PCI). Note that the PCI conflict between the first base station 10 and the fifth base station 250 is ignored because in this example, the controller 250 only identifies PCI conflicts between the first neighbor cells, the second neighbor cells, and the third-order neighbor cells.

[0081] In step S305, the controller 250 identifies a solution to the multiple PCI conflicts identified in step S303. The solution is based on the maximum (ie, highest priority) energy saving priority group of each base station pair for each PCI conflict. Figure 7 In the example, the maximum energy-saving priority group of the base station pair of the first PCI conflict is 3, and the maximum energy-saving priority group of the base station pair of the second PCI conflict is 2. The solution makes any network performance degradation as a result of the solution more likely for the base station pair with a relatively high maximum priority energy-saving priority group value, and therefore more likely to enter the energy-saving mode. That is, the scheme ensures that the performance of the base station pair with a relatively low maximum energy-saving priority group (i.e., the base station pair that is more likely to compensate for other base stations) is better than the performance of the base station pair with a relatively high maximum energy-saving priority group (i.e., the base station pair that is more likely to enter the energy-saving mode). In the example where the multiple PCI conflicts include a first PCI conflict (wherein the maximum energy-saving priority group of the base station involved in the first PCI conflict is 3) and also include a second PCI conflict (wherein the maximum energy-saving priority group of the base station involved in the second PCI conflict is 2), the controller identifies a solution that prioritizes the performance of the second PCI conflict over the first PCI conflict. In other words, the identified solution is a solution in which the base station involved in the first PCI conflict (at least primarily) suffers any network performance degradation.

[0082] The identified solution may involve reallocating PCIs to base stations in the network 200. In this case, the reallocated PCIs should resolve the second PCI conflict, and the base stations involved in the first PCI conflict should suffer any network performance degradation from the reallocation. For example, the PCI allocation may involve reallocation of a PCI for the third base station 230 so that the third base station 230 and the fifth base station 250 no longer have the same PCI, even if the change causes the first base station 210 and the third base station 230 to have another form of PCI conflict.

[0083] In step S307 , the controller 250 instructs each base station to implement its corresponding part of the identified solution.

[0084] Similar to the second process detailed above, this third process also considers the current energy-saving state and potential energy-saving state of the base stations involved in the identified PCI conflict, so as to prioritize solutions that favor the performance of base stations that contribute more to the overall network performance. That is, base stations that are currently in compensation mode or configured to compensate for other base stations entering energy-saving mode contribute more to the overall network performance (e.g., in terms of the number of users served and throughput) than base stations that are in energy-saving mode or configured to enter energy-saving mode. Therefore, solutions to PCI conflicts involving reduced performance of one of the base stations involved in the PCI conflict should prioritize the performance of base stations configured to compensate for one or more other base stations over the performance of base stations configured to enter energy-saving mode.

[0085] As mentioned above, Figure 1 The controller 150 is configured to perform the first process and the second process, and Figure 7 The controller 250 is configured to perform the third process. However, this is not necessary, and the first process, the second process, and the third process may be performed by one or more base stations. That is, the base station may exchange necessary data (such as NRT data and energy saving status data) in inter-base station messaging so that the remaining steps of each process may be performed locally. The base station may identify the neighbor relationship between base stations by comparing the NRT data. For example, if a first base station receives an NRT that can be detected by the first base station from a first neighboring base station (so that the first neighboring base station is a first-order neighbor of the first base station) and the NRT includes data about a second neighboring base station that cannot be detected by the first base station, the second neighboring base station is a second-order neighbor. The NRT may include a neighbor order for each base station (from the perspective of the base station that fills the NRT) to reduce calculations.

[0086] In the second and third processes detailed above, the energy saving priority group is used to define multiple energy saving states of the base station (including its current energy saving state and potential energy saving state). Each base station may have multiple potential energy saving states, in which case the energy saving priority group should reflect the energy saving state with the greatest coverage. In addition, a single energy saving state (current or potential) may be used instead.

[0087] Instead of identifying the maximum energy saving priority group of the base station involved in the PCI conflict, the minimum energy saving priority group can be used. A combined energy saving priority group representing the corresponding energy saving priority group of each base station involved in the PCI conflict can also be used. The combination can be achieved by averaging or adding the corresponding energy saving priority groups.

[0088] In the above process, one of the solutions to the PCI conflict is to configure the coverage area of ​​the base stations involved so that the PCI conflict cannot occur (such as by limiting the transmit power of one or more base stations). Those skilled in the art will understand that these solutions may not eliminate the PCI conflict, but only reduce the performance degradation caused by the PCI conflict to below a threshold amount. For example, the solution may be to reduce the transmit power of one of the base stations involved in the conflict so that the conflict still exists in a smaller geographical area.

[0089] The above procedures are described in the context of a conventional radio access network. However, these procedures may also be applied to a decomposed radio access network having remote units and centralized units (e.g., decomposed units and / or central units). In this case, when a PCI conflict is found between two remote units, a check may be made to determine whether they have a common centralized unit. If the two remote units have a common centralized unit, the threshold amount of acceptable performance degradation may be relatively high.

[0090] Figure 8 An example of Figure 1 A fourth process implemented in a node of a network of. In step S401, the node obtains data indicating corresponding physical cell identifiers PCIs of a first transceiver and a second transceiver among a plurality of transceivers, and also indicates a current neighbor relationship between the first transceiver and the second transceiver, and the current neighbor relationship between the first transceiver and the second transceiver has a specific order. In step S403, in the case where the order of the current neighbor relationship between the first transceiver and the second transceiver decreases, the node identifies a first potential PCI conflict between the first transceiver and the second transceiver among the plurality of transceivers from the obtained data. In step S405, the node identifies a solution to the first potential PCI conflict. In step S407, the node causes a reconfiguration in the cellular telecommunication network to implement the identified solution.

[0091] Fig. 9 An example of Figure 7A fifth process implemented in a node of a network of. In step S501, the node obtains data including a physical cell identifier PCI of each transceiver in a plurality of transceivers. In step S503, the node identifies a first PCI conflict between a first pair of transceivers in the plurality of transceivers and a second PCI conflict between a second pair of transceivers in the plurality of transceivers based on the obtained data. In step S505, the node determines that a priority of a solution to the first PCI conflict is greater than a priority of a solution to the second PCI conflict, wherein the priority of solutions to the first PCI conflict and the second PCI conflict are based on respective energy-saving characteristics of the respective first pair of transceivers and the second pair of transceivers. In step S507, the node identifies a solution to the first PCI conflict. In step S509, the node causes a reconfiguration in the cellular telecommunication network to implement the identified solution.

[0092] A person skilled in the art will understand that any combination of features is possible within the scope of the claimed invention.

Claims

1. A node for a cellular telecommunication network, the cellular telecommunication network comprising a plurality of transceivers, the node comprising: a transceiver configured to obtain data indicating respective physical cell identifiers (PCIs) of a first transceiver and a second transceiver of the plurality of transceivers and also indicating a current neighbor relation between the first transceiver and the second transceiver, the current neighbor relation between the first transceiver and the second transceiver having a specific order; and A processor, the processor being configured to: identifying from the obtained data a first potential PCI conflict between a first transceiver and a second transceiver of the plurality of transceivers in a case where the current neighbor relationship between the first transceiver and the second transceiver is in a decreasing order, Identify the solution to the first potential PCI conflict, and The cellular telecommunications network is caused to be reconfigured to implement the identified solution.

2. The node according to claim 1, wherein: The current neighbor relationship indicates that the first transceiver and the second transceiver are second-order neighbors, and the first potential PCI conflict is when the first transceiver and the second transceiver are reconfigured from second-order neighbors to first-order neighbors, wherein the first-order neighbors are direct neighbors and the second-order neighbors are direct neighbors of the first-order neighbors rather than first-order neighbors.

3. The node according to claim 1, wherein: The current neighbor relationship indicates that the first transceiver and the second transceiver are third-order neighbors, and the first PCI conflict occurs when the first transceiver and the second transceiver are reconfigured from third-order neighbors to first-order neighbors or second-order neighbors, wherein the first-order neighbors are direct neighbors, the second-order neighbors are direct neighbors of the first-order neighbors instead of the first-order neighbors, and the third-order neighbors are direct neighbors of the second-order neighbors instead of the first-order neighbors or second-order neighbors.

4. A node according to any one of the preceding claims, wherein: The transceiver is further configured to: obtaining data indicating respective PCIs of a third transceiver and a fourth transceiver of the plurality of transceivers and also indicating a current neighbor relationship between the third transceiver and the fourth transceiver, the current neighbor relationship between the third transceiver and the fourth transceiver having a specific order, And wherein the processor is further configured to: identifying from the obtained data a second potential PCI conflict between the third transceiver and the fourth transceiver of the plurality of transceivers in a case where the order of the current neighbor relationship between the third transceiver and the fourth transceiver is reduced; and Determine that a priority level of a solution to the first potential PCI conflict is greater than a priority level of a solution to the second potential PCI conflict.

5. The node according to claim 4, wherein: The solution priorities are based on one or more of the group consisting of: an order of said neighbor relations of respective transceivers such that relatively lower order neighbor relations have a greater resolution priority than relatively higher order neighbor relations, The severity of the potential PCI violation, power saving characteristics of the first transceiver, the second transceiver, the third transceiver and / or the fourth transceiver, and In case the first transceiver and the second transceiver are remote units and the cellular telecommunication network is a decomposed radio access network, an identifier of a first distributed node of the first transceiver and an identifier of a second distributed node of the second transceiver.

6. The node according to claim 5, wherein: The energy saving characteristic is one or more of a current energy saving state and an energy saving capability.

7. A node according to any one of the preceding claims, wherein: The solution is one or more of the group consisting of: changing a PCI of one or more transceivers of the plurality of transceivers, limiting an operation mode of one or more transceivers among the plurality of transceivers, wherein the operation mode is one of a power saving mode, a normal mode, and a compensation mode, limiting the transmit power of one or more of the plurality of transceivers, and One or more of the plurality of transceivers are disabled.

8. The node of any preceding claim, the node being one of the group consisting of: a controller, and a transceiver of the plurality of transceivers.

9. A method in a cellular telecommunication network, the cellular telecommunication network comprising a plurality of transceivers, the method comprising the steps of: Obtaining data indicating respective physical cell identifiers PCIs of a first transceiver and a second transceiver of the plurality of transceivers and also indicating a current neighbor relation between the first transceiver and the second transceiver, the current neighbor relation between the first transceiver and the second transceiver having a specific order; identifying, from the obtained data, a first potential PCI conflict between the first transceiver and the second transceiver in a case where the order of the current neighbor relationship between the first transceiver and the second transceiver is reduced; identifying a solution to the first potential PCI conflict; and The cellular telecommunications network is caused to be reconfigured to implement the identified solution.

10. A computer program comprising instructions for causing a node according to any one of claims 1 to 8 to execute the steps of claim 9.

11. A computer-readable medium having the computer program according to claim 10 stored thereon.

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