Method for controlling carrier turn-off in multicarrier cellular network

Abstract

Controlling carrier shutdown in a multicarrier cellular network includes a coverage cell in the multicarrier cellular network obtaining information about an active antenna unit (AAU) configuration of one or more capacity cells paired with the coverage cell. The coverage cell transmits information about a coverage cell load and a carrier borrowing capability of an AAU of the coverage cell to a paired capacity cell. And each paired capacity cell determines whether the carrier borrowing of the coverage cell meets the carrier turn-off entry condition of the capacity cell according to the carrier borrowing capability. The OFF carrier borrowing determines a capacity cell that satisfies the carrier OFF entry condition, while if the coverage cell determines that a carrier borrowing condition is satisfied, the coverage cell borrows a carrier of an OFF capacity cell using the AAU configuration of the capacity cell to activate a borrowed carrier.

Description

Technical Field

[0001] The present disclosure generally relates to controlling carrier shutdown in a multi-carrier cellular network. More specifically, the present disclosure relates to a method for controlling carrier shutdown in a multi-carrier cellular network. Background Art

[0002] Compared with the third generation partnership project (3GPP) long term evolution (LTE), the third-generation partnership project new radio (3GPP NR) deployment generally provides an energy efficiency improvement of about four times (4x) due to its greater capacity and improved hardware. However, due to the need to process more for wider bandwidths and more antennas, the energy consumption of 3GPP NR sites is estimated to be up to three times (3x) that of LTE sites, which may increase the carbon emissions and electricity bills of operators.

[0003] To address this issue and further improve the energy efficiency of cellular networks, LTE, and new radio base stations (BSs), an energy-saving solution is implemented that allows the BS to dynamically shut down some of its hardware to reduce its power consumption.

[0004] For energy saving, existing solutions use the carrier shutdown function to shut down carriers during a carrier shutdown period specified by the operator.

[0005] In the context of carrier shutdown, covered cells and capacity cells are introduced in 3GPP to allow energy saving through inter-cell coordination. Capacity cells are high-frequency cells that can be shut down. Covered cells are manually identified low-frequency cells that provide basic coverage and cannot be shut down. Each capacity cell is associated with a subset of covered cells through a different-frequency co-coverage relationship. When the total load of a capacity cell and its covered cell pair is not high, the traffic of the capacity cell can be migrated to its covered cell, and the capacity cell can be shut down. When the load of the covered cell increases, it may activate the shut-down capacity cell.

[0006] In addition, a capacity cell can only be shut down if its covered cell is identified and paired with it. Otherwise, it may not be possible to guarantee the coverage and capacity requirements of users served by the shut-down capacity. In addition, based on the instantaneous conditions of the covered cell and the capacity cell (such as their total load), the capacity cell may or may not (1) initiate an inter-frequency handover, (2) be shut down. Similarly, when the load of the covered cell increases, this may activate a dormant capacity cell. Therefore, in the current cellular network, it is necessary to keep the load of the covered cell as low as possible to increase the chance of shutting down the capacity cell and increase its shut-down time.

[0007] With the advent of the fifth-generation (5G) era, the number of frequency bands added to base stations is also increasing continuously. More than 70% of operators have more than five frequency bands, and future cellular networks may add more frequency bands (such as millimeter-wave frequency bands). Mainstream 2G / 3G / 4G base stations adopt a combination form of a base band unit (BBU), a radio remote unit (RRU), and an antenna. In the 5G era, they are evolving towards the form of a BBU and an active antenna unit (AAU). More specifically, the radio unit responsible for transmitting (TX) / receiving (RX) signal processing for a cell can be in the following forms: (1) an RRU, which exchanges digital signals with the base band unit through an optical fiber cable and exchanges analog signals with passive antenna elements through a coaxial cable; or (2) an AAU, which integrates the RRU function and passive antenna elements into one unit and provides the hardware and logic to (i) control the precoding coefficients of each passive antenna element and (ii) combine / divide digital signals from / to each passive antenna element. Existing RRUs / AAUs are multi-carrier and use a broadband power amplifier (PA) to jointly operate these multiple carriers.

[0008] Compared with a single-band PA, a broadband PA provides higher energy efficiency. This is mainly due to: (i) by integrating multiple carriers together, the total transmit power managed by the broadband PA is larger, allowing the broadband PA to operate in a more efficient region, and (ii) as part of the signal processing components that can be shared among different carriers, the static power consumption of the broadband PA increases sub-linearly with respect to the number of carriers. In addition, the use of a broadband PA has an impact on network energy-saving methods. If all the carriers supported by the broadband PA are turned off, the broadband PA can only be turned off. Otherwise, if one of them is active, the broadband PA will remain active, thus limiting energy saving on the cellular network side. Therefore, it is necessary to deploy paired coverage cells and capacity cells on different AAUs to maximize energy saving through carrier shutdown.

[0009] In addition, 3GPP introduced the concept of co-coverage relationship, in which the capacity cell and the basic cell are automatically identified using vendor-specific processes. For example, in a capacity cell, the base station randomly selects user equipments (UEs) and sends measurement control messages to measure all inter-frequency cells. This can utilize the 3GPP self-organizing network (SON) automatic neighboring relation (ANR) framework. Then, the base station receives the corresponding UE measurement reports (MRs) and estimates the coverage overlap by dividing the number of times the serving cell is the strongest cell by the number of times the measurement control message is sent for the frequency of the neighboring basic cell.

[0010] Typically, the paired serving cell and capacity cell are deployed on different AAUs to maximize energy savings through carrier shutdown, i.e., the paired serving cell and capacity cell do not share the same power amplifier. When the carrier shutdown feature is activated, the carrier shutdown entry condition determines whether the capacity cell enters carrier shutdown at a given point in time. This method is based on the following principles: (1) The capacity cell can decide to enter the sleep mode autonomously or based on the information exchanged with the serving cell. (2) The shutdown decision / request can be based on the information locally available in the access network node, including the load information of both the serving cell and the capacity cell. (3) The activation can be performed based on the request from one or more neighboring heterogeneous radio access technology (RAT) nodes or based on the internal node policy (e.g., periodic turn-on, maximum shutdown time, etc.). (4) The neighboring nodes of the same radio access technology (Intra-RAT) and heterogeneous radio access technology (Inter-RAT) can be notified after the activation / shutdown decision is made. (5) To save energy more efficiently, some energy-saving parameters (e.g., traffic threshold, duration, power consumption, etc.) can be exchanged between neighboring heterogeneous cells when needed.

[0011] In addition, when some capacity cells are not active and the load of the access to the cellular network increases, the serving cell may not know the appropriate capacity cells to wake up. The overloaded serving cell can request to wake up one or more of the neighboring dormant capacity cells based on the co-coverage relationship. However, the final decision to exit the sleep mode is made by the capacity cell based on the locally available information.

[0012] Although the above techniques can reduce the energy consumption of cellular networks, their current implementation may lead to limited user performance due to the handover mechanism and limited overlay capacity. In addition, the continuous deactivation and activation of capacity cells may result in limited energy efficiency gains. The network spectral efficiency is reduced due to the instantaneous deactivation of capacity cells and the unused spectrum of these capacity cells.

[0013] Another existing solution adopts a cell handover and spectrum leasing framework that maximizes the revenue of the primary network (PN) by leasing the spectrum it owns to a secondary network (SN). This framework analyzes the trade-off among energy conservation, spectrum leasing revenue, and quality of service (QoS), and designs an optimal cell handover and spectrum leasing strategy to bring the maximum revenue to the PN while ensuring the maintenance of the QoS of the PN. However, this framework does not focus on the coverage and load issues caused by carrier shutdown.

[0014] Another existing solution provides a cell handover and spectrum leasing framework that uses an algorithm to learn and maximize the revenue of the primary network (PN) while ensuring the maintenance of the QoS of the PN. In this solution, the PN can lease the spectrum it owns to a secondary network (SN). In addition, the cell handover and spectrum leasing problem is formulated as a binary integer programming problem, which is solved by a heuristic method based on simulated annealing. However, this solution does not focus on the coverage and load issues caused by carrier shutdown.

[0015] Another existing solution discloses a method for enabling frequency resource negotiation in a defined set of nearby access points. This solution realizes channel borrowing in WLAN, maintaining or improving the network throughput. However, this solution does not focus on energy conservation and the coverage and load issues caused by carrier shutdown.

[0016] Another existing solution discloses a channel borrowing method for reducing congestion in a cellular network, in which, based on unsatisfied user requests, a first cell requests an instantaneous number of channels from nearby cells, which allows the first cell to use these channels based on its expected traffic. However, this solution does not focus on using channel borrowing to extend the shutdown time of capacity cells.

[0017] Another existing solution discloses a network scheduling method for coordinating the energy-saving management of base stations. This method enables base stations to cooperate to achieve shutdown modes, including channel and carrier shutdown modes. However, this solution does not focus on using channel borrowing to extend the shutdown time of capacity cells.

[0018] Therefore, it is necessary to solve the above technical problems / defects of controlling carrier shutdown in a multi-carrier cellular network. Summary of the Invention

[0019] The object of the present disclosure is to provide a method for controlling carrier shutdown in a multi-carrier cellular network while avoiding one or more drawbacks of existing methods.

[0020] This object is achieved by the features of the independent claims. Additionally, the implementation is evident in the dependent claims, the description, and the drawings.

[0021] The present disclosure provides a method for controlling carrier shutdown in a multi-carrier cellular network.

[0022] According to a first aspect, there is provided a method for controlling carrier shutdown in a multi-carrier cellular network. The method includes: a serving cell in the multi-carrier cellular network obtaining information about the Active Antenna Unit (AAU) configuration of one or more capacity cells paired with the serving cell. The method includes: the serving cell sending information about the serving cell load and the carrier borrowing ability of the AAU of the serving cell to the paired capacity cells. The method includes: each paired capacity cell determining whether carrier borrowing from the serving cell meets the carrier shutdown entry condition based on the carrier borrowing ability. The method includes: shutting down each paired capacity cell for which it is determined that carrier borrowing meets the carrier shutdown entry condition. The method includes: if the serving cell determines that the carrier borrowing condition is met, the serving cell uses the AAU configuration of the capacity cell to borrow a carrier from one of the shut-down paired capacity cells to activate the borrowed carrier.

[0023] Due to the relationship between the capacity cell and the paired serving cell, the method increases the shutdown time of the capacity cell by allowing an adjacent serving cell to borrow the carrier frequency of the capacity cell (e.g., in 4G and 5G networks). By allowing the AAU of the serving cell to borrow the carrier frequency of the shut-down capacity cell, the capacity of the serving cell is increased, enabling it to divert more traffic from the shut-down capacity cell. Therefore, the capacity cell can be shut down more frequently, for a longer time, and the reactivation frequency can be lower. The AAU of the serving cell can benefit from the shut-down carriers of the AAUs near the capacity cell, thereby enhancing its diversion ability and delaying the activation of the capacity cell. The method enables the serving cell to borrow and release the capacity cell channels in a transparent manner. The method is semi-static and, based on load measurements at the serving cell and the paired capacity cell, increases the shutdown time of the capacity cell. The method selects the measured capacity cell and the serving cell located at different AAUs and adjusts the traffic load of the measured capacity cell such that the capacity cell shuts down.

[0024] Since the hardware is shared among the co-deployed carriers in the AAU, activating the borrowed carrier at the AAU covering the cell only slightly increases the power consumption, so this method is energy-saving. In addition, this method requires limited additional signaling exchanges because the covering cell pre-obtains the capabilities and configurations of the paired capacity cell in terms of the number, frequency, and bandwidth of the carriers, and notifies its paired capacity cell of the changes in its borrowing capabilities of the AAU.

[0025] Optionally, if the load of the covering cell is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shutdown exit threshold, the carrier borrowing condition is satisfied. The carrier borrowing condition may depend on one or more of the key performance indicators (KPIs) of the covering cell and / or the paired capacity cell, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency.

[0026] Optionally, the method further includes: when the covering cell determines that the carrier release condition is satisfied, the covering cell releases the carrier borrowed from the shutdown paired capacity cell. The method further includes: when the covering cell determines that the carrier borrowing condition is satisfied, the covering cell re-borrows the carrier from the shutdown paired capacity cell.

[0027] Optionally, if the average value of the load of the covering cell at the borrowed carrier and the load of the covering cell at its own carrier is lower than a predefined carrier borrowing release threshold, the carrier release condition is satisfied.

[0028] Optionally, the method further includes: the covering cell determines whether the carrier shutdown exit condition for the shutdown paired capacity cell is satisfied. The method further includes: the covering cell sends a cell activation message to activate the shutdown paired capacity cell determined to satisfy the carrier shutdown exit condition. The method further includes: releasing the carrier borrowed by the covering cell from the activated paired capacity cell.

[0029] Optionally, if the average value of the load of the covering cell at the borrowed carrier and the load of the covering cell at its own carrier is higher than a predefined carrier shutdown exit threshold, the carrier shutdown exit condition is satisfied. The carrier shutdown exit condition may depend on one or more of the KPIs of the covering cell related to the borrowed carrier and / or its own carrier, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency.

[0030] Optionally, the method further includes: before sending a cell activation message to the shutdown paired capacity cell, the serving cell initiates an inter-frequency handover to transfer any user equipment (UE) connected to the serving cell at the borrowed carrier to the serving cell's own carrier. Sending a cell activation message to activate the shutdown paired capacity cell includes: (i) the serving cell sending an AAU activation message to the baseband unit (BBU) of the shutdown paired capacity cell as the cell activation message, (ii) the BBU activating the AAU of the shutdown paired capacity cell, and (iii) performing mobility load balancing to balance the load between the serving cell's own carrier and the carrier borrowed by the serving cell. Releasing the carrier borrowed by the serving cell includes: in response to receiving an acknowledgement from the BBU of the paired capacity cell that its AAU has been activated and mobility load balancing has been achieved, the BBU of the serving cell releases the borrowed carrier.

[0031] Optionally, the method further includes: the serving cell determines that a part of the borrowed carrier of the shutdown paired capacity cell meets the carrier shutdown exit condition. The method further includes: the serving cell suspends accepting new UE connections at the borrowed carrier. Sending a cell activation message to activate the shutdown paired capacity cell includes: (i) the serving cell sending a partial carrier activation message to the baseband unit (BaseBand Unit, BBU) of the shutdown paired capacity cell as the cell activation message, where the partial carrier activation message indicates that a part of the capacity cell carrier will be activated, and (ii) the BBU activating the part of the capacity cell carrier at the AAU of the shutdown paired capacity cell. Releasing the carrier borrowed by the serving cell includes: (i) transferring the UE connected to the serving cell at the borrowed carrier to the activated part of the paired capacity cell carrier, and (ii) when the load of the serving cell is lower than a predefined serving cell threshold for releasing the carrier borrowing, the serving cell releases the borrowed carrier by sending a release message to the BBU of the partially activated paired capacity cell.

[0032] Optionally, the information about the AAU configuration of each capacity cell includes the number of carriers owned by the capacity cell, the frequency and bandwidth of the carriers. The information about the carrier borrowing ability of the AAU of the serving cell includes the information about the available AAU time slots at the AAU and the processing resources of the baseband unit (Base Band Unit, BBU) of the AAU of the serving cell.

[0033] Optionally, the method further includes defining a shutdown policy for each capacity cell of the multi-carrier cellular network. The shutdown policy includes a carrier shutdown entry condition and a carrier shutdown exit condition. The carrier shutdown entry condition is met when the combined load of the capacity cell and the serving cell is lower than the carrier shutdown threshold.

[0034] Optionally, the carrier-off threshold is defined during the pairing process of the coverage cell and the capacity cell as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process. Optionally, the method further includes: before turning off the paired capacity cell, the paired capacity cell initiates an inter-frequency handover to the coverage cell.

[0035] Optionally, the coverage cell borrowing a carrier from the turned-off paired capacity cell includes: (i) the coverage cell sending a carrier borrowing message to the BBU of the turned-off paired capacity cell, (ii) allocating one time slot of the AAU of the coverage cell to the borrowed carrier, and (iii) allocating the processing resources of the BBU of the coverage cell to the allocated time slot of the AAU.

[0036] Optionally, one of the capacity cells paired with the coverage cell is paired with one or more additional coverage cells, and the method further includes: coordinating the coverage cell with the additional coverage cells such that only one of the co-paired coverage cells borrows a carrier from the turned-off capacity cell.

[0037] Optionally, coordinating the coverage cell with the additional coverage cells includes: enabling the one of the co-paired coverage cells that experiences a larger load and / or has the largest overlapping area with the turned-off capacity cell to borrow a carrier from the turned-off capacity cell.

[0038] Optionally, one of the capacity cells paired with the coverage cell is paired with one or more additional coverage cells, and the method further includes: the BBU of the turned-off capacity cell enabling only one of the co-paired coverage cells to borrow a carrier from the turned-off capacity cell based on the load and / or other KPIs of the co-paired coverage cells.

[0039] Optionally, one of the capacity cells paired with the coverage cell is paired with one or more additional coverage cells, and the method further includes: the BBU of the turned-off capacity cell dividing the available bandwidth of the carrier of the turned-off capacity cell in time into parts for different co-paired coverage cells to borrow. The division can be based on one or more of the KPIs of the co-paired coverage cells, and the KPIs include the load experienced by each of the co-paired coverage cells, the overlapping area between each of the co-paired coverage cells and the turned-off capacity cell, and the delay of each of the co-paired coverage cells.

[0040] Therefore, different from the existing solutions, due to the relationship between the capacity cell and the paired coverage cell, the method increases the off time of the capacity cell by allowing adjacent coverage cells to borrow the carrier frequency of the capacity cell (e.g., in 4G and 5G networks). By allowing the AAU of the coverage cell to borrow the carrier frequency of the turned-off capacity cell, the coverage cell capacity is increased, so that it can divert more traffic from the turned-off capacity cell. Therefore, the capacity cell can be turned off more frequently, with a longer off time and a lower reactivation frequency.

[0041] These and other aspects of the disclosure will be apparent from the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Implementations of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0043] Figure 1 shows a method for controlling carrier shutdown in a multi-carrier cellular network to increase the capacity cell shutdown time;

[0044] Figure 2 shows an exemplary interaction diagram of a capacity cell and a coverage cell in a multi-carrier cellular network for increasing the shutdown time of a capacity cell;

[0045] Figure 3 is a graphical representation of the load of a coverage cell in a multi-carrier cellular network during carrier shutdown, carrier borrowing, carrier release, and carrier activation Figure 2 according to an embodiment of the disclosure;

[0046] Figure 4 is an exemplary interaction diagram according to an embodiment of the disclosure, showing a message sequence between a capacity cell and a coverage cell in a multi-carrier cellular network during carrier shutdown with carrier borrowing;

[0047] Figures 5A - 5E shows an exemplary view of carrier shutdown / deactivation based on the load of a coverage cell and multiple key performance indicators (KPIs) according to an embodiment of the disclosure;

[0048] Figure 6 shows an exemplary interaction diagram of a capacity cell paired with a coverage cell and one or more additional coverage cells in a multi-carrier cellular network for increasing the shutdown time of a capacity cell according to an embodiment of the disclosure;

[0049] Figure 7A and Figure 7B is a flowchart showing a method for controlling carrier shutdown in a multi-carrier cellular network according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0050] Embodiments of the disclosure provide a method for controlling carrier shutdown in a multi-carrier cellular network.

[0051] To make it easier for those skilled in the art to understand the solution of the disclosure, the following embodiments of the disclosure are described in conjunction with the accompanying drawings.

[0052] The inventive concepts, claims, and the above-mentioned drawings of the present disclosure use terms such as "first", "second", "third", and "fourth" (if any) to distinguish similar objects, and do not necessarily describe a specific sequence or order. It should be understood that the terms used in this way are interchangeable under appropriate circumstances, such that the embodiments of the present disclosure described herein can be implemented, for example, in a sequence different from that shown or described herein. In addition, the terms "comprising" and "having" and any variants thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device comprising a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0053] Figure 1 A method for controlling carrier shutdown in a multi-carrier cellular network to increase the capacity cell shutdown time according to an embodiment of the present disclosure is shown. In step 102, a method for controlling carrier shutdown in a multi-carrier cellular network is started. In step 104, the serving cell acquires information about the configuration of active antenna units (AAUs) of one or more capacity cells paired with the serving cell in the multi-carrier cellular network. In step 106, the serving cell sends information about the serving cell load and the carrier borrowing ability of the AAU of the serving cell to the paired capacity cells. In step 108, each paired capacity cell determines whether the carrier borrowing of the serving cell meets the carrier shutdown entry condition of the capacity cell according to the carrier borrowing ability. If the carrier borrowing of the serving cell does not meet the carrier shutdown entry condition of the capacity cell according to the carrier borrowing ability, step 108 is repeated. Otherwise, step 110 is entered to shutdown each paired capacity cell for which it is determined that the carrier borrowing meets the carrier shutdown entry condition.

[0054] Optionally, the capacity cell implements a shutdown policy for shutting down each paired capacity cell for which it is determined that the carrier borrowing meets the carrier shutdown entry condition. Optionally, the method further includes: before shutting down the paired capacity cell, the paired capacity cell initiates an inter-frequency handover to the serving cell. In step 112, if the serving cell determines that the carrier borrowing condition is met, the serving cell borrows a carrier from one of the shutdown paired capacity cells using the AAU configuration of the capacity cell to activate the borrowed carrier. In step 114, the serving cell determines whether the carrier shutdown exit condition for shutting down the paired capacity cell is met. If the carrier shutdown exit condition is not met, step 114 is repeated. Otherwise, step 116 is entered, and the serving cell sends a cell activation message to activate the shutdown paired capacity cell for which it is determined that the carrier shutdown exit condition is met, and the serving cell releases the carrier borrowed from the activated paired capacity cell.

[0055] Optionally, if the load of the serving cell is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shutdown exit threshold, the carrier borrowing condition is met. The carrier borrowing condition may depend on one or more of the key performance indicators (KPIs) of the serving cell and / or the paired capacity cell, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency. Optionally, the method further includes: when the serving cell determines that the carrier release condition is met, the serving cell releases the carrier borrowed from the shutdown paired capacity cell. The method further includes: when the serving cell determines that the carrier borrowing condition is met, the serving cell re-borrows the carrier from the shutdown paired capacity cell. Optionally, if the average of the load of the serving cell at the borrowed carrier and the load of the serving cell at its own carrier is lower than a predefined carrier borrowing release threshold, the carrier release condition is met.

[0056] Optionally, if the average of the load of the serving cell at the borrowed carrier and the load of the serving cell at its own carrier is higher than a predefined carrier shutdown exit threshold, the carrier shutdown exit condition is met. The carrier shutdown exit condition may depend on one or more of the KPIs of the serving cell related to the borrowed carrier and / or its own carrier, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency.

[0057] The AAU of the serving cell may use the carrier of one of its paired shutdown capacity cells, configure and use a new carrier in one of its unused AAU time slots, and transmit using the same radio frequency (RF) configuration. When carrier shutdown is activated, the serving cell sends both the load information and an indication of its AAU borrowing ability to the capacity cell, i.e., the number of available unused time slots in this AAU frame, its operating frequency, etc. When carrier borrowing occurs at the AAU of the serving cell, a larger carrier shutdown threshold may be used to relax the carrier shutdown entry condition at the capacity cell. Therefore, compared with no carrier borrowing, the capacity cell can be shut down more frequently or for a longer time because the serving cell can rely on the additional capacity provided by the borrowed carrier in its AAU.

[0058] An example of the AAU power model is shown below:

[0059] ,

[0060] where P AAU is the power consumption of the active antenna unit, P0 is the power consumption of a part of the AAU circuit that is always active (e.g., the circuit for controlling AAU activation / deactivation), P BBis the power consumption generated by performing baseband signal processing at the AAU, P TRX is the power consumption of the T transceivers of the AAU, P PA is M ac The power consumption of the power amplifier (PA), P out is the power consumed to generate the transmit power required to transmit data through C carrier components.

[0061] In the mode details, P TRX,t , that is, the power consumed by each of the T transceivers in the AAU, is the number M of available RF chains in transceiver t av,t multiplied by the power D TRX consumed by each RF chain, t. The static power P PA consumed by the multi-carrier PA is the number M ac of active RF chains multiplied by the static power D PA consumed by each multi-carrier PA. Finally, P out is calculated as the sum of the output powers P TX,c of each of the C carrier components divided by the efficiency of the multi-carrier PA and the antenna.

[0062] Since the hardware is shared among the co-deployed carriers in the AAU, activating the borrowed carriers at the AAU covering the cell only slightly increases the power consumption, so this method is energy-saving. In addition, this method requires limited additional signaling exchange because the covering cell pre-gets the capabilities and configurations of the paired capacity cell in terms of the number of carriers, frequency, and bandwidth, and notifies its paired capacity cell of the changes in its borrowing capabilities of the AAU.

[0063] Due to the relationship between the capacity cell and the paired covering cell, this method increases the off-time of the capacity cell by allowing adjacent covering cells to borrow the carrier frequencies of the capacity cell (e.g., in 4G and 5G networks). By allowing the AAU of the covering cell to borrow the carrier frequencies of the off-capacity cell, the capacity of the covering cell is increased, so that it can divert more traffic from the off-capacity cell. Therefore, the capacity cell can be turned off more frequently, for a longer off-time, and the reactivation frequency can be lower. The AAU of the covering cell can benefit from the off-carriers of the AAU near the capacity cell, thus enhancing its diversion ability and delaying the activation of the capacity cell. This method enables the covering cell to borrow and release the capacity cell channels in a transparent manner. This method is semi-static and, based on the load measurements at the covering cell and the paired capacity cell, increases the off-time of the capacity cell. This method selects the measured capacity cell and covering cell located at different AAUs and adjusts the traffic load of the measured capacity cell so that the capacity cell is turned off.

[0064] Figure 2FIG. 0 shows an exemplary interaction diagram of a capacity cell 202 and a coverage cell 204 in a multi-carrier cellular network for increasing the off-time of the capacity cell 204 according to an embodiment of the present disclosure. In a multi-carrier cellular network, an Active Antenna Unit (AAU) deploying multiple carriers is used to achieve a balance between the requirements of the coverage cell 204 and the capacity cell 202. In step 206, the capacity cell 202 and the coverage cell 204 in the multi-carrier cellular network are paired according to a co-coverage analysis. In step 208, the capacity cell 202 sends information about the AAU configuration to the paired coverage cell 204. Optionally, the information about the AAU configuration of each capacity cell 202 includes the number of carriers owned by the capacity cell 202, the frequencies and bandwidths of the carriers.

[0065] In step 210, an off strategy is defined for each capacity cell 202 of the multi-carrier cellular network. Optionally, the off strategy includes a carrier-off entry condition and a carrier-off exit condition. The carrier-off entry condition is satisfied when the combined load of the capacity cell 202 and the coverage cell 204 is lower than a carrier-off threshold. Optionally, the carrier-off entry condition depends on whether carrier borrowing can be performed at the AAU of the coverage cell 204. Optionally, the carrier-off threshold takes into account the capacity of the coverage cell 204 with / without carrier borrowing. Optionally, the carrier-off threshold is defined to activate / release the borrowed carriers at the AAU of the coverage cell 204. Optionally, the carrier-off threshold is defined during the pairing process of the coverage cell 204 and the capacity cell 202 as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process. In step 212, the off strategy of each capacity cell 202 of the multi-carrier cellular network is activated. Optionally, the off strategy runs at a predefined interval. In step 214, the coverage cell 204 sends information about the coverage cell load and the carrier borrowing ability of the AAU of the coverage cell 204 to the paired capacity cell 202. Optionally, the information about the carrier borrowing ability of the AAU of the coverage cell 204 includes information about the available AAU time slots at the AAU and the processing resources of the Base Band Unit (BBU) of the AAU of the coverage cell 204. In step 216, the paired capacity cell 202 determines whether the carrier borrowing of the coverage cell 204 meets the carrier-off entry condition of the capacity cell 202 according to the carrier borrowing ability, and turns off the paired capacity cell 202 for which the carrier borrowing is determined to meet the carrier-off entry condition. In step 218, the capacity cell 202 sends a status message to the coverage cell 204, and the status message includes information about the turn-off of the paired capacity cell 202. Optionally, as in the baseline carrier-off scheme, the capacity cell 202 to be turned off performs an inter-frequency handover to achieve traffic diversion.

[0066] In step 220, if the serving cell 204 determines that the carrier borrowing condition is met by sending a carrier borrowing message to the BBU that shuts down the paired capacity cell 202 in step 222, the serving cell 204 uses the AAU configuration of the capacity cell 202 to borrow the carrier of the shut-down paired capacity cell 202 to activate the borrowed carrier. Optionally, if the load of the serving cell 204 is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shutdown exit threshold, the carrier borrowing condition is met. Optionally, the carrier borrowing condition depends on one or more of the key performance indicators (KPIs) of the serving cell 204 and / or the paired capacity cell 202, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency. In step 224, when the load at the serving cell 204 drops below a predefined serving cell threshold, the borrowed carrier of the paired capacity cell 202 is released.

[0067] In step 226, when the serving cell 204 determines that the carrier release condition is met, the serving cell 204 releases the carrier borrowed from the shut-down paired capacity cell 202. Optionally, if the average of the serving cell load at the borrowed carrier and the serving cell load at its own carrier is lower than a predefined carrier borrowing release threshold, the carrier release condition is met. Optionally, when the serving cell 204 determines that the carrier borrowing condition is met, the serving cell 204 re-borrows the carrier from the shut-down paired capacity cell 202. In step 228, when the load at the serving cell 204 increases and the carrier shutdown exit condition of the shut-down paired capacity cell 202 is met, the AAU of the serving cell 204 activates the borrowed carrier. In step 230, the serving cell 204 sends a cell activation message to the shut-down paired capacity cell 202 that is determined to meet the carrier shutdown departure condition, and the cell activation message includes information about the activation of the borrowed carrier of the shut-down paired capacity cell 202. In step 232, the serving cell 204 activates the carrier borrowed by the serving cell 204 at the paired capacity cell 202.

[0068] Figure 3 is a diagram showing a multi-carrier cellular network during carrier shutdown, carrier borrowing, carrier release, and carrier activation according to an embodiment of the present disclosure Figure 2Graphical representation of the load of the serving cell. From the graphical representation, it can be observed that during carrier borrowing and carrier release, the total load of both the serving cell 204 and the capacity cell 202 is lower than the carrier-off entry condition. If the total load of both the serving cell 204 and the capacity cell 202 is lower than the carrier-off entry condition, the paired capacity cell 202 initiates an inter-frequency handover. If the inter-frequency handover is successfully completed, the paired capacity cell 202 is turned off. If the capacity of the serving cell 204 increases, more traffic can be diverted from the turned-off capacity cell 202. Therefore, the capacity cell 202 can be turned off more frequently, for a longer time, and the reactivation frequency can be lower.

[0069] Figure 4 FIG. is an exemplary interaction diagram according to an embodiment of the present disclosure, which shows a message sequence between a capacity cell 402 and a serving cell 404 in a multi-carrier cellular network during carrier-off with carrier borrowing. In a multi-carrier cellular network, a multi-carrier Active Antenna Unit (AAU) is deployed to balance the requirements of the serving cell 404 and the capacity cell 402. Carrier borrowing enables the serving cell 404 associated with the capacity cell 402 being turned off to borrow its carrier / bandwidth to instantaneously increase the serving cell capacity, so that the serving cell 404 can smoothly support any additional load previously served by the turned-off capacity cell 402 for a user equipment (UE). Carrier borrowing can improve the quality of service on the UE side and can extend the off time of the capacity cell 402, which needs to be activated when the load of the associated serving cell increases above a predefined threshold.

[0070] In step 406, the capacity cell 402 and the serving cell 404 in the multi-carrier cellular network are paired according to co-coverage analysis. In step 408, the capacity cell 402 sends information about the AAU configuration together with the paired serving cell 404. Optionally, the exchange of information is implemented between the Base Band Units (BBUs) of the capacity cell 402 and the paired serving cell 404. Optionally, the information about the AAU configuration of each capacity cell 402 includes the number of carriers owned by the capacity cell 402, the frequency and bandwidth of the carriers. In step 410, an off strategy is defined for each capacity cell 402 of the multi-carrier cellular network. Optionally, the off strategy includes a carrier-off entry condition, a carrier-off exit condition, and the time when the off strategy starts and ends. The carrier-off entry condition is satisfied when the combined load of the capacity cell 402 and the serving cell 404 is lower than the carrier-off threshold. Optionally, the carrier-off threshold is defined during the pairing process of the serving cell 404 and the capacity cell 402 as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process.

[0071] Optionally, the carrier-off threshold is expressed as:

[0072] • - The carrier-off threshold for the carrier-off entry condition without carrier borrowing (i.e., the capacity cell threshold);

[0073] • - The carrier-off threshold for the carrier-off exit condition without carrier borrowing (i.e., the capacity cell threshold);

[0074] • - The carrier-off threshold for the carrier-off entry condition with carrier borrowing (i.e., the capacity cell threshold);

[0075] • - The carrier-off threshold for the carrier-off exit condition with carrier borrowing (i.e., the capacity cell threshold);

[0076] • - The predefined coverage cell threshold for releasing carrier borrowing;

[0077] • - The predefined coverage cell threshold for activating carrier borrowing.

[0078] In addition, the following are expressed as:

[0079] • - The coverage cell load;

[0080] • - The capacity cell load;

[0081] • - The load of the carrier of the capacity cell 402 borrowed at the coverage cell 404.

[0082] In step 412, the shutdown strategy of each capacity cell 402 of the multi-carrier cellular network is activated. Optionally, the shutdown strategy operates within a predefined interval. Optionally, during the operation of the shutdown strategy, the paired capacity cells 402 periodically request information about the load and carrier borrowing capabilities of the paired coverage cells 404 (i.e., the configuration and load status, such as the coverage cell load The information of (). In step 414, the serving cell 404 sends information about the serving cell load and the carrier borrowing capability of the AAU of the serving cell 404 to the paired capacity cell 402. Optionally, the information about the carrier borrowing capability of the AAU of the serving cell 404 includes information about the available AAU time slots at the AAU and the processing resources of the baseband unit (BBU) of the AAU of the serving cell 404. Optionally, the AAU of the serving cell may or may not be compatible with the carrier frequency used at the capacity cell 402.

[0083] Optionally, if the shutdown policy is activated, the capacity cell 402 may be shut down based on the information about the serving cell load, the capacity cell load, and the carrier borrowing capability of the AAU of the serving cell 404.

[0084] In step 416, the paired capacity cell 402 determines whether the carrier borrowing of the serving cell 404 meets the carrier shutdown entry condition of the capacity cell 402 according to the carrier borrowing capability. If the carrier borrowing performed by the serving cell 404 meets the carrier shutdown entry condition of the capacity cell 402 (for example, if the total load of both the serving cell 404 and the capacity cell 402 is lower than the carrier shutdown entry condition for performing carrier borrowing, then the paired capacity cell 402 initiates an inter-frequency handover. If the inter-frequency handover is successfully completed, the paired capacity cell 402 is shut down. In step 418, when the AAU of the paired capacity cell 402 is shut down / deactivated, its BBU sends a status message to the serving cell 404 to shut down / deactivate the computing resources allocated to the capacity cell 402. Optionally, at the BBU of the capacity cell 402, only a small amount of processing resources are reserved to receive and process control messages from the network (such as the paired serving cell 404).

[0085] Optionally, when the capacity cell 402 is shut down / deactivated, its serving cell 404 continuously measures its load status and compares the result with the carrier shutdown exit condition and a predefined carrier borrowing activation threshold. Optionally, if the load of the serving cell is higher than the predefined carrier borrowing activation threshold and lower than the predefined carrier shutdown exit threshold, the carrier borrowing condition is met. Optionally, the carrier borrowing condition depends on one or more of the key performance indicators (KPIs) of the serving cell 404 and / or the paired capacity cell 402, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell delay. In step 420, if the load of the serving cell 404 is greater / higher than the predefined carrier borrowing activation threshold and less / lower than the predefined carrier shutdown exit condition , the overlaid cell 404 generates a carrier borrowing message to borrow the carrier of the deactivated capacity cell 402. In step 422, the overlaid cell 404 sends the carrier borrowing message to the BBU of the deactivated paired capacity cell 402 and borrows the carrier of the deactivated capacity cell 402. Optionally, a time slot of the AAU of the overlaid cell 404 is allocated to the borrowed carrier, and the BBU of the overlaid cell 404 allocates processing resources to the allocated time slot of the AAU.

[0086] Optionally, if the average value of the overlaid cell load at the borrowed carrier and the overlaid cell load at its own carrier is higher than the predefined carrier deactivation exit threshold, the carrier deactivation exit condition is met. The carrier deactivation exit condition may depend on one or more of the KPIs of the overlaid cell 404 related to the borrowed carrier and / or its own carrier, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell delay.

[0087] In step 424, when the capacity cell 402 is still deactivated, if the overlaid cell load (which can be calculated as the average value of the load at the capacity cell borrowed carrier and the load at its original carrier) is greater / higher than the carrier deactivation exit condition for performing carrier borrowing , then before sending the cell activation message to the deactivated paired capacity cell 402, the overlaid cell 404 initiates an inter-frequency handover to transfer any user equipment (UE) connected to the overlaid cell 404 at the borrowed carrier to the own carrier of the overlaid cell 404. In step 426, the overlaid cell 404 sends an AAU activation message to the base band unit (BBU) of the deactivated paired capacity cell 402 as the cell activation message. In step 428, the BBU of the capacity cell 402 activates the AAU of the deactivated paired capacity cell 402. In step 430, the BBU of the capacity cell 402 confirms the carrier activation to the overlaid cell 404 and accordingly switches some of the users connected to the overlaid cell 404 to the capacity cell 402, so as to balance the load between the own carrier of the overlaid cell 404 and the activated carrier at the capacity cell 402. In step 432, the BBU of the overlaid cell 404 releases the borrowed carrier. Optionally, in response to receiving the confirmation that its AAU is activated from the BBU of the paired capacity cell 402, the BBU of the overlaid cell 404 releases the borrowed carrier to achieve mobility load balancing.

[0088] Optionally, the serving cell 404 determines that a portion of the borrowed carrier of the deactivated paired-capacity cell 402 meets the carrier deactivation exit condition. The serving cell 404 suspends the borrowed carrier from accepting new UE connections. Sending a cell activation message to activate the deactivated paired-capacity cell 402 includes: (i) the serving cell 404 sending a partial carrier activation message to the baseband unit (BBU) of the deactivated paired-capacity cell 402 as the cell activation message, where the partial carrier activation message indicates that a portion of the capacity cell carrier will be activated; (ii) the BBU activating a portion of the capacity cell carrier at the active antenna unit (AAU) of the deactivated paired-capacity cell 402. Releasing the borrowed carrier of the serving cell 404 includes: (i) transferring the UE connected to the serving cell 404 at the borrowed carrier to the activated portion of the paired-capacity cell carrier, (ii) when the load of the serving cell 404 is lower than a predefined serving cell threshold for releasing carrier borrowing, the serving cell 404 releases the borrowed carrier by sending a release message to the BBU of the partially activated paired-capacity cell 402.

[0089] Optionally, when carrier borrowing is implemented, the serving cell 404 is associated with a predefined carrier borrowing activation threshold and a predefined carrier borrowing release threshold (i.e., the carrier borrowing threshold) for activation and release. The predefined carrier borrowing activation threshold is used to determine at the serving cell 404 whether to borrow the carrier of the paired-capacity cell 402, and the predefined carrier borrowing release threshold is used to release the borrowed carrier. Optionally, the carrier deactivation entry condition and the carrier deactivation exit condition for performing carrier borrowing are determined by each paired-capacity cell 402.

[0090] Optionally, when the capacity cell 402 is deactivated / shut down and the serving cell 404 borrows the carrier of the capacity cell 402, the serving cell 404 can dynamically release and activate the borrowed carrier to reduce its power consumption. Specifically, if the load of the serving cell 404, i.e., the average of the load at the borrowed carrier of the capacity cell and the load at its original carrier, is lower than a predefined serving cell threshold for releasing carrier borrowing , , then the BBU of the serving cell 404 releases the borrowed carrier of the capacity cell 402. Optionally, if the load of the serving cell 404 is greater than / higher than the predefined carrier borrowing activation threshold , and its load is less than / lower than the predefined carrier deactivation exit condition , then the BBU of the serving cell 404 reactivates the borrowed carrier of the deactivated capacity cell 402.

[0091] Optionally, for the carrier deactivation entry condition for performing carrier borrowing, a carrier deactivation threshold is defined as follows:

[0092] , where, is the cell overlap factor.

[0093] Optionally, the carrier-off threshold is defined during the pairing process of the coverage cell 404 and the capacity cell 402 as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process. Optionally, the carrier-off threshold for the carrier-off entry condition with carrier borrowing is higher than the carrier-off threshold for the carrier-off entry condition without carrier borrowing. , and thus, when the carrier borrowing mechanism is implemented, the capacity cell 402 can be turned off more frequently.

[0094] Optionally, for the carrier-off exit condition for carrier borrowing, the carrier-off threshold is defined as follows:

[0095] .

[0096] Optionally, when the load of the coverage cell is greater than the carrier-off threshold for the carrier-off exit condition, , the coverage cell 404 activates the capacity cell 402 without carrier borrowing. The carrier-off exit condition for carrier borrowing can be defined as . When the carrier borrowing mechanism is implemented, the capacity cell 402 can be turned off for a longer time because a part of the coverage cell load can be transferred to the borrowed carrier.

[0097] Optionally, a predefined coverage cell threshold for releasing carrier borrowing is defined as follows:

[0098] .

[0099] Optionally, a predefined coverage cell threshold for activating carrier borrowing is defined as follows:

[0100] ,

[0101] where can be calculated as .

[0102] Optionally, when the capacity cell 402 is still deactivated / turned off and the average of the coverage cell load at the borrowed carrier and the coverage cell load at its own carrier is higher than the predefined carrier-off exit threshold, , the overlaid cell 404: (i) suspends borrowing carriers to accept new UE connections, (ii) sends a partial carrier activation message to the Base Band Unit (BBU) of the deactivated paired capacity cell 402 as a cell activation message, where the partial carrier activation message indicates that a part of the capacity cell carrier will be activated, and the BBU activates the part of the capacity cell carrier at the AAU of the deactivated paired capacity cell 402, (iii) transfers the UEs connected to the overlaid cell 404 at the borrowed carrier to the activated part of the paired capacity cell carrier, (iv) when the load of the overlaid cell is lower than a predefined overlaid cell threshold for releasing carrier borrowing , releases the borrowed carrier by sending a release message to the BBU of the partially activated paired capacity cell 402, (v) sends a release message to the BBU of the capacity cell 402. When the load of the overlaid cell is less than , the overlaid cell releases the borrowed carrier.

[0103] Figures 5A - 5E Shows an exemplary view of carrier shutdown / deactivation based on the load of the overlaid cell 504 and multiple key performance indicators (KPIs) according to an embodiment of the present disclosure. In a multi-carrier cellular network, cells are divided into capacity cells and overlaid cells to implement an energy-saving strategy. Carrier borrowing can improve the quality of service on the user equipment side and can extend the shutdown time of the capacity cell 502, which needs to be activated when the load of the associated overlaid cell increases above a predefined threshold. The capacity cell 502 and the overlaid cell 504 in the multi-carrier cellular network are paired according to co-coverage analysis. Optionally, the capacity cell 502 sends information about the AAU configuration together with the paired overlaid cell 504. Optionally, the information about the AAU configuration of the capacity cell 502 includes the number of carriers owned by the capacity cell 502, the frequency and bandwidth of the carriers. Optionally, a shutdown strategy is defined for each capacity cell 502 of the multi-carrier cellular network. Optionally, the shutdown strategy includes carrier shutdown entry conditions, carrier shutdown exit conditions, and the start and end times of the shutdown strategy. When the combined load of the capacity cell 502 and the overlaid cell 504 is lower than the carrier shutdown threshold, the carrier shutdown entry conditions are met. Optionally, the carrier shutdown threshold is defined during the pairing process of the overlaid cell 504 and the capacity cell 502 as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process.

[0104] Optionally, the carrier shutdown threshold is expressed as:

[0105] • - The carrier shutdown threshold for the carrier shutdown entry condition without carrier borrowing (i.e., the capacity cell threshold);

[0106] • - Carrier-off threshold for the carrier-off exit condition without carrier borrowing (i.e., capacity cell threshold);

[0107] • - Carrier-off threshold for the carrier-off entry condition with carrier borrowing (i.e., capacity cell threshold);

[0108] • - Carrier-off threshold for the carrier-off exit condition with carrier borrowing (i.e., capacity cell threshold);

[0109] • - Predefined coverage cell threshold for releasing carrier borrowing;

[0110] • - Predefined coverage cell threshold for activating carrier borrowing.

[0111] In addition, the following are represented as:

[0112] • - Coverage cell load;

[0113] • - Capacity cell load;

[0114] • - Load of the carrier of capacity cell 502 borrowed at coverage cell 504.

[0115] Figure 5A It shows that capacity cell 502 operates a carrier , and coverage cell 504 operates a carrier . For example, , , the power consumption of both coverage cell 504 and capacity cell 502 .

[0116] Optionally, if the offloading policy is activated, capacity cell 502 can be turned off based on information about the coverage cell load, capacity cell load, and the carrier borrowing ability of the AAU of coverage cell 504. Coverage cell 504 borrows a carrier from paired capacity cell 502 as Figure 5B shown. If the carrier borrowing of coverage cell 504 meets the carrier-off entry condition of capacity cell 502, the AAU of coverage cell 504 borrows the capacity cell carrier . Here, is replaced by , that is, . Optionally, for the carrier-off entry condition with carrier borrowing, the carrier-off threshold is defined as . Among them, is the cell overlap factor. Optionally, as Figure 5B shown, when the serving cell 504 borrows a carrier from the paired capacity cell 502, the power consumption of both the serving cell 504 and the capacity cell 502 is 1160 W, that is, compared with the power consumption of both the serving cell 504 and the capacity cell 502 in Figure 5A , 20% of the power is saved.

[0117] As Figure 5C shown, the serving cell 504 releases the borrowed carrier of the capacity cell 502. Optionally, when the capacity cell 502 is deactivated / turned off and the serving cell 504 borrows the capacity cell carrier, the borrowed carrier can be dynamically released and activated to reduce its power consumption on the base station and user equipment (UE) sides. Specifically, if the load of the serving cell 504, that is, the average of the load at the borrowed carrier of the capacity cell 502 and the load at its original carrier, is lower than the predefined serving cell threshold for releasing carrier borrowing , that is , then the AAU of the serving cell 504 releases the borrowed carrier of the capacity cell 502. Optionally, the predefined serving cell threshold for releasing carrier borrowing is equal to the carrier shutdown threshold (i.e., the capacity cell threshold) for the carrier shutdown entry condition without carrier borrowing, that is, . Optionally, the power consumption of both the serving cell 504 and the capacity cell 502 is 1060 W, that is, compared with the power consumption of both the serving cell 504 and the capacity cell 502 in Figure 5A , 27% of the power is saved.

[0118] As Figure 5D shown, the serving cell 504 reactivates the borrowed carrier of the capacity cell 502. Optionally, when the serving cell load is greater than / higher than the predefined carrier borrowing activation threshold, the AAU of the serving cell 504 reactivates the borrowed carrier of the deactivated capacity cell 502. Optionally, the predefined serving cell threshold for activating carrier borrowing is equal to the carrier shutdown threshold (i.e., the capacity cell threshold) for the carrier shutdown exit condition without carrier borrowing, that is . Optionally, the power consumption of both the serving cell 504 and the capacity cell 502 is 1160 W, that is, compared with the power consumption of both the serving cell 504 and the capacity cell 502 in Figure 5A , 20% of the power is saved.

[0119] As Figure 5EAs shown, the overlay cell 504 sends a cell activation message to the capacity cell 502. Optionally, when the capacity cell 502 is still deactivated / shut down, and the average of the overlay cell load at the borrowed carrier and the overlay cell load at its own carrier is higher than a predefined carrier shut-down exit threshold, that is , where . When this is the case, the overlay cell 504 sends a cell activation message to the paired capacity cell 502 and releases the borrowed carrier. Optionally, the carrier shut-down threshold for the carrier shut-down exit condition for carrier borrowing is equal to the carrier shut-down threshold for the carrier shut-down entry condition for carrier borrowing, that is , where, . Optionally, the power consumption of both the overlay cell 504 and the capacity cell 502 is 1450 W.

[0120] Optionally, if the load of the overlay cell 504 is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shut-down exit threshold, then the carrier borrowing condition is met. The carrier borrowing condition can depend on one or more of the key performance indicators (KPIs) of the overlay cell and / or the paired capacity cell, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency. For example, if , then when , the AAU of the overlay cell 504 does not release the borrowed carrier, where, are respectively the number of UEs in the connected mode in the original carrier and the borrowed carrier of the overlay cell 504, is a predefined threshold. Optionally, because , the AAU of the overlay cell 504 reactivates the borrowed carrier even if , where, is the rate experienced at the overlay cell 504, is a predefined threshold. Optionally, the KPIs of the overlay cell 504 are used in the form of a linear combination to determine whether the borrowed carrier should be activated or released.

[0121] Figure 6FIG. shows an exemplary interaction diagram of a capacity cell 602 paired with a coverage cell 604A in a multi - carrier cellular network for increasing the off - time of the capacity cell 602, and the capacity cell 602 paired with one or more additional coverage cells 604B. In step 606, based on the co - coverage analysis, the capacity cell 602 paired with the coverage cell 604A is paired with one or more additional coverage cells 604B in the multi - carrier cellular network. In step 608, the capacity cell 602 sends information about the AAU configuration to the co - paired coverage cells (604A - 604B). Optionally, the information about the AAU configuration of each capacity cell 602 includes the number of carriers the capacity cell 602 has, the frequency and bandwidth of the carriers. In step 610, an off - strategy is defined for each capacity cell 602 of the multi - carrier cellular network. Optionally, the off - strategy includes a carrier - off entry condition and a carrier - off exit condition. The carrier - off entry condition is met when the combined load of the capacity cell 602 and the co - paired coverage cells (604A - 604B) is below the carrier - off threshold. Optionally, the carrier - off threshold is defined during the pairing process of the co - paired coverage cells (604A - 604B) and the capacity cell 602 as a function of the cell overlap factor calculated in the co - coverage analysis during the pairing process.

[0122] In step 612, the off - strategy of each capacity cell 602 of the multi - carrier cellular network is activated. Optionally, the off - strategy runs at a predefined interval. In step 614, the co - paired coverage cells (604A - 604B) send information about the load of the coverage cells and the carrier borrowing ability of the AAUs of the co - paired coverage cells (604A - 604B) to the paired capacity cell 602. Optionally, the information about the carrier borrowing ability of the AAUs of the co - paired coverage cells (604A - 604B) includes information about the available AAU time slots at the AAU and the processing resources of the base - band unit (BBU) of the AAUs of the co - paired coverage cells (604A - 604B).

[0123] In step 616, the paired capacity cell 602 determines whether the carrier borrowing performed by any one of the co-paired coverage cells (604A - 604B) meets the carrier shutdown entry condition of the capacity cell 602 according to the carrier borrowing ability, and shuts down the paired capacity cell 602 for which it is determined that the carrier borrowing meets the carrier shutdown entry condition. In step 618, the capacity cell 602 sends a status message to the co-paired coverage cells (604A - 604B), and the status message includes information about the shutdown of the paired capacity cell 602. In step 620, the coverage cell 604A coordinates with the additional coverage cell 604B so that only one of the co-paired coverage cells (604A - 604B) can borrow a carrier from the shutdown capacity cell 602 to optimize network performance. Optionally, coordinating the coverage cell 604A with the additional coverage cell 604B includes: enabling one of the co-paired coverage cells (604A - 604B) that experiences a larger load and / or has the largest overlapping area with the shutdown capacity cell 602 to borrow a carrier from the shutdown capacity cell 602. Optionally, one of the capacity cells 602 paired with the coverage cell 604A is paired with one or more additional coverage cells 604B so that only one of the co-paired coverage cells (604A - 604B) borrows a carrier from the shutdown capacity cell 602 by shutting down the BBU of the capacity cell 602 and based on the load and / or other KPIs of the co-paired coverage cells (604A - 604B).

[0124] In step 622, if one of the co-paired coverage cells (604A - 604B) determines that the carrier borrowing condition is met, only one of the co-paired coverage cells (604A - 604B) borrows a carrier from the shutdown paired capacity cell 602 using the AAU configuration of the capacity cell 602 to activate the borrowed carrier. Optionally, if the load of one of the co-paired coverage cells (604A - 604B) is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shutdown exit threshold, the carrier borrowing condition is met. Optionally, the carrier borrowing condition depends on one or more of the key performance indicators (KPIs) of the co-paired coverage cells (604A - 604B) and / or the paired capacity cell 602, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell delay.

[0125] In step 624, a carrier borrowing message is sent by one of the co-paired coverage cells (604A - 604B) of the borrowed carrier to the BBU of the shutdown paired capacity cell 602. Optionally, a time slot of an AAU of one of the co-paired coverage cells (604A - 604B) is allocated to the borrowed carrier, and the BBU of one of the co-paired coverage cells (604A - 604B) allocates processing resources to the allocated time slot of the AAU. In step 626, when the load of one of the co-paired coverage cells (604A - 604B) decreases, the carrier of the paired capacity cell 602 is released. In step 628, when one of the co-paired coverage cells (604A - 604B) determines that the carrier release condition is satisfied, one of the co-paired coverage cells (604A - 604B) releases the carrier borrowed from the shutdown paired capacity cell 602. Optionally, if the average value of the co-paired coverage cell load at the borrowed carrier and the co-paired coverage cell load at its own carrier is lower than a predefined carrier borrowing release threshold, the carrier release condition is satisfied. Optionally, when any one of the co-paired coverage cells (604A - 604B) determines that the carrier borrowing condition is satisfied, one of the co-paired coverage cells (604A - 604B) re-borrows the carrier from the shutdown paired capacity cell 602.

[0126] Optionally, one of the capacity cells 602 paired with the coverage cell 604A is paired with one or more additional coverage cells 604B, and the BBU of the shutdown capacity cell 602 divides the available bandwidth in time of the carrier of the shutdown capacity cell 602 into parts for borrowing by different co-paired coverage cells (604A - 604B). The division can be based on one or more of the KPIs of the co-paired coverage cells (604A - 604B), and the KPIs include the load experienced by each of the co-paired coverage cells (604A - 604B), the overlapping area of each of the co-paired coverage cells (604A - 604B) with the shutdown capacity cell 602, and the time delay of each of the co-paired coverage cells (604A - 604B).

[0127] Figures 7A - 7BIt is a flowchart of a method for controlling carrier shutdown in a multi-carrier cellular network according to an embodiment of the present disclosure. In step 702, the serving cell obtains information about the Active Antenna Unit (AAU) configuration of one or more capacity cells paired with the serving cell in the multi-carrier cellular network. In step 704, the serving cell sends information about the serving cell load and the carrier borrowing ability of the AAU of the serving cell to the paired capacity cells. In step 706, each paired capacity cell determines whether the carrier borrowing of the serving cell meets the carrier shutdown entry condition according to the carrier borrowing ability determined for each paired capacity cell. In step 708, each paired capacity cell whose determined carrier borrowing meets the carrier shutdown entry condition is shut down. In step 710, if the serving cell determines that the carrier borrowing condition is met, the serving cell borrows a carrier from one of the shut-down paired capacity cells using the AAU configuration of the capacity cell to activate the borrowed carrier.

[0128] Due to the relationship between the capacity cell and the paired serving cell, this method increases the shutdown time of the capacity cell by allowing an adjacent serving cell to borrow the carrier frequency of the capacity cell (e.g., in 4G and 5G networks). By allowing the AAU of the serving cell to borrow the carrier frequency of the shut-down capacity cell, the serving cell capacity is increased, enabling it to divert more traffic from the shut-down capacity cell. Therefore, the capacity cell can be shut down more frequently, for a longer time, and reactivated less frequently. This method is semi-static and increases the shutdown time of the capacity cell based on load measurements at the serving cell and the paired capacity cell.

[0129] Since the hardware is shared among the carriers co-deployed in the AAU of the serving cell, activating the borrowed carrier at the AAU of the serving cell only slightly increases the power consumption, so this method is energy-saving. In addition, this method requires limited additional signaling exchange because the serving cell pre-obtains the capabilities and configurations of the paired capacity cell in terms of the number, frequency, and bandwidth of the carriers and notifies the paired capacity cell of the changes in the borrowing ability of its AAU.

[0130] Optionally, if the load of the serving cell is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shutdown exit threshold, the carrier borrowing condition is met. The carrier borrowing condition can depend on one or more of the Key Performance Indicators (KPIs) of the serving cell and / or the paired capacity cell, including load, the number of connected User Equipments (UEs), coverage holes, cell rate, and cell latency.

[0131] Optionally, the method further includes: when the serving cell determines that the carrier release condition is satisfied, the serving cell releases the carrier borrowed from the deactivated paired capacity cell. The method further includes: when the serving cell determines that the carrier borrowing condition is satisfied, the serving cell re-borrows the carrier from the deactivated paired capacity cell.

[0132] Optionally, if the average value of the serving cell load at the borrowed carrier and the serving cell load at its own carrier is lower than a predefined carrier borrowing release threshold, the carrier release condition is satisfied.

[0133] Optionally, the method further includes: the serving cell determines whether the carrier deactivation exit condition of the deactivated paired capacity cell is satisfied. The method further includes: the serving cell sends a cell activation message to activate the deactivated paired capacity cell that is determined to satisfy the carrier deactivation exit condition. The method further includes: releasing the carrier borrowed by the serving cell from the activated paired capacity cell.

[0134] Optionally, if the average value of the serving cell load at the borrowed carrier and the serving cell load at its own carrier is higher than a predefined carrier deactivation exit threshold, the carrier deactivation exit condition is satisfied. The carrier deactivation exit condition may depend on one or more of the KPIs of the serving cell related to the borrowed carrier and / or its own carrier, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell latency.

[0135] Optionally, the method further includes: before sending the cell activation message to the deactivated paired capacity cell, the serving cell initiates an inter-frequency handover to transfer any user equipment (UE) connected to the serving cell at the borrowed carrier to the serving cell's own carrier. Sending the cell activation message to activate the deactivated paired capacity cell includes: (i) the serving cell sends an AAU activation message to the baseband unit (BBU) of the deactivated paired capacity cell as the cell activation message, (ii) the BBU activates the AAU of the deactivated paired capacity cell, and (iii) performs mobility load balancing to balance the load between the serving cell's own carrier and the carrier of the capacity cell previously borrowed by the serving cell. Releasing the carrier borrowed by the serving cell includes: in response to receiving the confirmation that its AAU is activated and the mobility load balancing is achieved from the BBU of the paired capacity cell, the BBU of the serving cell releases the borrowed carrier.

[0136] Optionally, the method further includes: the serving cell determines that a part of the borrowed carrier of the deactivated paired capacity cell meets the carrier deactivation exit condition. The method further includes: the serving cell suspends the borrowed carrier to accept new UE connections. Sending a cell activation message to activate the deactivated paired capacity cell includes: (i) the serving cell sending a partial carrier activation message to the BaseBand Unit (BBU) of the deactivated paired capacity cell as the cell activation message, where the partial carrier activation message indicates that a part of the capacity cell carrier will be activated; (ii) the BBU activates the part of the capacity cell carrier at the Active Antenna Unit (AAU) of the deactivated paired capacity cell. Releasing the carrier borrowed by the serving cell includes: (i) transferring the UE connected to the serving cell at the borrowed carrier to the activated part of the paired capacity cell carrier; (ii) when the load of the serving cell is lower than a predefined serving cell threshold for releasing the carrier borrowing, the serving cell releases the borrowed carrier by sending a release message to the BBU of the partially activated paired capacity cell.

[0137] Optionally, the information about the AAU configuration of each capacity cell includes the number of carriers owned by the capacity cell, the frequency and bandwidth of the carriers. The information about the carrier borrowing ability of the AAU of the serving cell includes the information about the available AAU time slots at the AAU and the processing resources of the Base Band Unit (BBU) of the AAU of the serving cell.

[0138] Optionally, the method further includes defining a deactivation strategy for each capacity cell of the multi-carrier cellular network. The deactivation strategy includes a carrier deactivation entry condition and a carrier deactivation exit condition. The carrier deactivation entry condition is met when the combined load of the capacity cell and the serving cell is lower than the carrier deactivation threshold.

[0139] Optionally, the carrier deactivation threshold is defined during the pairing process of the serving cell and the capacity cell as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process. Optionally, the method further includes: before deactivating the paired capacity cell, the paired capacity cell initiates an inter-frequency handover to the serving cell.

[0140] Optionally, the serving cell borrowing a carrier from the deactivated paired capacity cell includes: (i) the serving cell sending a carrier borrowing message to the BBU of the deactivated paired capacity cell; (ii) allocating a time slot of the AAU of the serving cell to the borrowed carrier; (iii) allocating the processing resources of the BBU of the serving cell to the allocated time slot of the AAU.

[0141] Optionally, one of the capacity cells paired with the serving cell is paired with one or more additional serving cells, and the method further includes: coordinating the serving cell with the additional serving cells so that only one of the co-paired serving cells borrows a carrier from the deactivated capacity cell.

[0142] Optionally, coordinating the serving cell with the additional serving cells includes: enabling one of the co-paired serving cells experiencing a larger load and / or having the largest overlapping area with the offloading-capacity cell to borrow a carrier from the offloading-capacity cell.

[0143] Optionally, one of the capacity cells paired with the serving cell is paired with one or more additional serving cells, and the method further includes: the BBU of the offloading-capacity cell enabling only one of the co-paired serving cells to borrow a carrier from the offloading-capacity cell based on the load and / or other KPIs of the co-paired serving cells.

[0144] Optionally, one of the capacity cells paired with the serving cell is paired with one or more additional serving cells, and the method further includes: the BBU of the offloading-capacity cell dividing the available bandwidth of the carriers of the offloading-capacity cell in time into portions for borrowing by different co-paired serving cells. The division can be based on one or more of the KPIs of the co-paired serving cells, where the KPIs include the load experienced by each of the co-paired serving cells, the overlapping area of each of the co-paired serving cells with the offloading-capacity cell, and the latency of each of the co-paired serving cells.

[0145] It should be understood that the arrangement of the components shown in the described drawings is exemplary, and other arrangements are possible. It should also be understood that the various system components (and devices) defined by the claims, described below and shown in the various block diagrams, represent components in some systems configured according to the subject matter disclosed herein. For example, one or more of these system components (and devices) can be implemented in whole or in part by at least some of the components in the arrangement shown in the drawings.

[0146] In addition, although at least one of these components is at least partially implemented as an electronic hardware component and thus constitutes a machine, other components can be implemented in software, which, when included in an execution environment, constitutes a machine, hardware, or a combination of software and hardware.

[0147] Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

1. A method for controlling carrier shutdown in a multi - carrier cellular network, comprising: The coverage cells (204, 404, 504, 604A - B) in the multi - carrier cellular network obtain information about the active antenna unit (AAU) configuration of one or more capacity cells (202, 402, 502, 602) paired with the coverage cells; The coverage cells send information about the coverage cell load and the carrier borrowing ability of the AAUs of the coverage cells to the paired capacity cells; Each paired capacity cell determines whether the carrier borrowing of the coverage cell meets the carrier shutdown entry condition according to the carrier borrowing ability; Shut down each paired capacity cell for which it is determined that the carrier borrowing meets the carrier shutdown entry condition; If the coverage cell determines that the carrier borrowing condition is met, the coverage cell borrows a carrier from one of the shut - down paired capacity cells using the AAU configuration of the capacity cell to activate the borrowed carrier.

2. The method according to claim 1, wherein, If the load of the coverage cell is higher than a predefined carrier borrowing activation threshold and lower than a predefined carrier shutdown exit threshold, the carrier borrowing condition is met.

3. The method according to claim 1, wherein The carrier borrowing condition depends on one or more of the key performance indicators (KPIs) of the coverage cell and / or the paired capacity cell, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell delay.

4. The method according to any one of claims 1 to 3, further comprising: When the coverage cell determines that the carrier release condition is met, the coverage cell releases the carrier borrowed from the shut - down paired capacity cell; When the coverage cell determines that the carrier borrowing condition is met, the coverage cell re - borrows the carrier from the shut - down paired capacity cell.

5. The method according to claim 4, wherein If the average value of the coverage cell load at the borrowed carrier and the coverage cell load at its own carrier is lower than a predefined carrier borrowing release threshold, the carrier release condition is met.

6. The method according to any one of claims 1 to 5, further comprising: The coverage cell determines whether the carrier shutdown exit condition of the shut - down paired capacity cell is met; The coverage cell sends a cell activation message to activate the shut - down paired capacity cell for which it is determined that the carrier shutdown exit condition is met; Release the carrier borrowed by the coverage cell from the activated paired capacity cell.

7. The method according to claim 6, wherein, If the average value of the coverage cell load at the borrowed carrier and the coverage cell load at its own carrier is higher than a predefined carrier shutdown exit threshold, the carrier shutdown exit condition is met.

8. The method according to claim 6, wherein The carrier shutdown exit condition depends on one or more of the KPIs of the coverage cell related to the borrowed carrier and / or its own carrier, including load, the number of connected user equipments (UEs), coverage holes, cell rate, and cell delay.

9. The method according to any one of claims 6 to 8, further comprising: Before sending the cell activation message to the switched-off paired capacity cell, the serving cell initiates an inter-frequency handover to transfer any user equipment (UE) connected to the serving cell at the borrowed carrier to the serving cell's own carrier. Wherein, sending the cell activation message to activate the switched-off paired capacity cell includes: The serving cell sends an AAU activation message to the baseband unit (BBU) of the switched-off paired capacity cell as the cell activation message. The BBU activates the AAU of the switched-off paired capacity cell. Perform mobility load balancing to balance the load between the serving cell's own carrier and the carrier borrowed by the serving cell. Wherein, releasing the carrier borrowed by the serving cell includes: in response to receiving confirmation from the BBU of the paired capacity cell that its AAU has been activated and the mobility load balancing has been achieved, the BBU of the serving cell releases the borrowed carrier.

10. The method according to any one of claims 6 to 8, further comprising: The serving cell determines that a part of the borrowed carrier of the switched-off paired capacity cell meets the carrier switch-off exit condition. The serving cell suspends the borrowed carrier from accepting new UE connections. Wherein, sending the cell activation message to activate the switched-off paired capacity cell includes: The serving cell sends a partial carrier activation message to the baseband unit BBU of the switched-off paired capacity cell as the cell activation message, wherein the partial carrier activation message indicates that a part of the capacity cell carrier will be activated. The BBU activates the part of the capacity cell carrier at the AAU of the switched-off paired capacity cell. Wherein, releasing the carrier borrowed by the serving cell includes: Transferring the UE connected to the serving cell at the borrowed carrier to the activated part of the paired capacity cell carrier. When the load of the serving cell is lower than a predefined serving cell threshold for releasing carrier borrowing, the serving cell releases the borrowed carrier by sending a release message to the BBU of the partially activated paired capacity cell.

11. The method according to any one of claims 1 to 10, wherein Information about the AAU configuration of each capacity cell includes the number of carriers owned by the capacity cell, the frequency and bandwidth of the carriers. Information about the carrier borrowing ability of the AAU of the serving cell includes information about the available AAU time slots at the AAU and the processing resources of the baseband unit (BBU) of the AAU of the serving cell.

12. The method according to any one of claims 1 to 10, further comprising: Defining a switch-off strategy for each capacity cell of the multi-carrier cellular network, the switch-off strategy including a carrier switch-off entry condition and a carrier switch-off exit condition, wherein the carrier switch-off entry condition is met when the combined load of the capacity cell and the serving cell is lower than the carrier switch-off threshold.

13. The method according to claim 13, wherein, The carrier switch-off threshold is defined during the pairing process of the serving cell and the capacity cell as a function of the cell overlap factor calculated in the co-coverage analysis during the pairing process.

14. The method according to any one of claims 1 to 13, wherein The method further includes: before turning off the paired capacity cell, the paired capacity cell initiates an inter-frequency handover to the coverage cell.

15. The method according to any one of claims 1 to 14, wherein, The coverage cell borrowing the carrier from the turned-off paired capacity cell includes: The coverage cell sends a carrier borrowing message to the BBU of the turned-off paired capacity cell. Allocate one time slot of the AAU of the coverage cell to the borrowed carrier. Allocate the processing resources of the BBU of the coverage cell to the allocated time slot of the AAU.

16. The method according to any one of claims 1 to 15, wherein One of the capacity cells (202, 402, 502, 602) paired with the coverage cell (604A) is paired with one or more additional coverage cells (604B). The method further includes: Coordinating the coverage cell (604A) with the additional coverage cell (604B) so that only one of the co-paired coverage cells (604A-B) borrows the carrier from the turned-off capacity cell.

17. The method according to claim 16, wherein, Coordinating the coverage cell with the additional coverage cell includes: enabling the co-paired coverage cell that experiences a larger load and / or has the largest overlapping area with the turned-off capacity cell to borrow the carrier from the turned-off capacity cell.

18. The method according to any one of claims 1 to 15, wherein One of the capacity cells paired with the coverage cell is paired with one or more additional coverage cells. The method further includes: The BBU of the turned-off capacity cell enables only one of the co-paired coverage cells to borrow the carrier from the turned-off capacity cell based on the load and / or other KPIs of the co-paired coverage cells.

19. The method according to any one of claims 1 to 15, wherein One of the capacity cells paired with the coverage cell is paired with one or more additional coverage cells. The method further includes: The BBU of the turned-off capacity cell divides the available bandwidth of the carrier of the turned-off capacity cell in time into parts for different co-paired coverage cells to borrow.

20. The method according to claim 16, wherein The division is based on one or more of the KPIs of the co-paired coverage cells. The KPIs include the load experienced by each of the co-paired coverage cells, the overlapping area of each of the co-paired coverage cells with the turned-off capacity cell, and the delay of each of the co-paired coverage cells.

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