Patent Description:
In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) and/or user equipments (UE), communicate via a Radio Access Network (RAN) to one or more core networks (CNs). The RAN covers a geographical area which is divided into service areas or cells, with each service area or cell being served by a radio network node such as a radio access node e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a NodeB (NB), an enhanced NodeB (eNodeB), or a gNodeB (gNB). A service area or cell is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.

A Universal Mobile Telecommunications System (UMTS) is a third generation (<NUM>) telecommunication network, which evolved from the second generation (<NUM>) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for wireless devices. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks, and investigate enhanced data rate and radio capacity. In some RANs, e.g., as in UTRAN, several radio network nodes may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural radio network nodes connected thereto. This type of connection is sometimes referred to as a backhaul connection. The RNCs and BSCs are typically connected to one or more core networks.

Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (<NUM>) network, have been completed within the <NUM>rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a Fifth Generation (<NUM>) network. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access network, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access network wherein the radio network nodes are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of an RNC are distributed between the radio network nodes, e.g., eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially "flat" architecture comprising radio network nodes connected directly to one or more core networks, i.e., they are not connected to RNCs. To compensate for that, the E-UTRAN specification defines a direct interface between the radio network nodes, this interface being denoted the X2 interface. New generation radio (NR) is a new radio access technology being standardized in 3GPP.

A cell may be in different states, for instance, in a sleeping state. A sleeping cell is an unlocked cell that is transmitting on the broadcast channel which has no alarms and is unable to setup traffic, such as packets or voice calls.

The sleeping cell is a situation whereby a cell is considered as functioning by the operator, but from a wireless device perspective it is not working. It is difficult to detect when a cell switch to a sleeping state since there is no alarm associated with the switch. It could be caused by misconfiguration, excessive load, or software/firmware problems at a base station side. In case of sleeping cells, it is impossible for wireless devices to establish a connection or to make a handover to the sleeping cells. Sleeping cells are troublesome for operators as they lead to poor network performance, revenue loss and increased operating expenses (OPEX).

Sleeping cells are currently detected after <NUM> to <NUM> hours of their occurrence. During this time the originating call attempts performed by wireless devices camped on those cells fail. Although the action of getting cells back in operation is mostly confined to node restart or cell lock and unlock, it may take some time to detect that a cell has entered a sleeping state. Since the sleeping cells are detected after <NUM> or <NUM> hours the delay leads to unsatisfied customers which in turn leads to loss of revenue.

There is currently no method for predicting cells going to a sleeping state. A solution for predicting cells which will enter the sleeping state is needed.

<CIT> discloses a method for operating a mobile radio communication device in a wireless communication network.

<CIT> discloses a method for controlling energy saving and compensation of a network management signal.

<CIT> discloses a method of ranking cells in a cellular network.

An object of embodiments herein is to provide a mechanism for improving performance of the wireless communication network. Particularly to provide a method and system for predicting a state of a cell in a RAN. Thereby it is possible to prevent the cell from entering the sleeping state.

This object is achieved by the subject matter as defined by the independent claims. Embodiments of the invention are characterized by the dependent claims.

According to an aspect the object is achieved by providing a method for predicting a state of a cell in a RAN. The method comprises obtaining information of the cell; determining one or more sets of conditions based on the information, wherein at least one of said one or more sets of conditions indicates a decrease of a Random Access Channel (RACH) success rate; and predicting that the cell will enter a sleeping state when at least one set of the one or more sets of conditions is fulfilled.

According to still another aspect the object is achieved by providing a system for predicting a state of a cell in a RAN. The system is configured to: obtain information of the cell; determine one or more sets of conditions based on the information, wherein at least one of said one or more sets of conditions indicates a decrease of a Random Access Channel (RACH) success rate; and predict that the cell will enter a sleeping state when at least one set of the one or more sets of conditions is fulfilled.

It is furthermore provided herein a computer program product comprising instructions, which, when executed on at least one processor of a system (<NUM>) for predicting a state of a cell (<NUM>) in a radio access network, RAN, cause the at least one processor to carry out any of the methods above. It is additionally provided herein a computer-readable storage medium, having stored thereon a computer program product comprising instructions which, when executed on at least one processor of a system (<NUM>) for predicting a state of a cell (<NUM>) in a radio access network, RAN, cause the at least one processor to carry out any of the methods above.

<FIG> is a schematic overview depicting a wireless communication network <NUM> comprising one or more RANs e.g., a first RAN (RAN1), connected to one or more CNs (not shown). The wireless communication network <NUM> may use one or more technologies, such as Wi-Fi, Long Term Evolution (LTE), LTE-Advanced, <NUM>, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations. Embodiments herein relate to recent technology trends that are of particular interest in a <NUM> context, however, embodiments are applicable also in further development of the existing communication systems such as e.g., <NUM> and LTE.

In the wireless communication network <NUM>, wireless devices e.g., a wireless device <NUM> such as a mobile station, a non-access point (non-AP) station (STA), a STA, a user equipment (UE) and/or a wireless terminal, are connected via the one or more RANs, to the one or more CNs, e.g., 5GCs. It should be understood by those skilled in the art that "wireless device" is a non-limiting term which means any terminal, wireless communication terminal, communication equipment, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or UE e.g., smart phone, laptop, mobile phone, sensor, relay, mobile tablets or any device communicating within a cell or service area.

The wireless communication network <NUM> comprises a radio network node <NUM>. The radio network node <NUM> is exemplified herein as a RAN node providing radio coverage over a cell <NUM>, i.e., a geographical area or a service area, of a radio access technology (RAT), such as NR, LTE, UMTS, Wi-Fi or similar. The radio network node <NUM> may be a radio access network node such as radio network controller or an access point such as a wireless local area network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g., a radio base station such as a NodeB, a gNodeB, an evolved Node B (eNB, eNodeB), a base transceiver station, Access Point Base Station, base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of serving a wireless device <NUM> within the service area served by the radio network node <NUM> depending e.g., on the radio access technology and terminology used and may be denoted as a receiving radio network node.

The wireless communication network <NUM> also comprises a network operations center (NOC) <NUM> also known as a network management center. The NOC <NUM> is responsible for monitoring and controlling power failures, communication line alarms such as bit errors, framing errors, line coding errors, circuits down, and other performance issues that may affect the wireless communication network <NUM>.

According to embodiments herein a system <NUM> for predicting that the cell <NUM> will enter the sleeping state will be introduced into the wireless communication network <NUM>. The system <NUM> may be located either in the NOC <NUM> or in a cloud.

The method actions performed by the system <NUM> for predicting a state of the cell <NUM> in the RAN <NUM> according to embodiments herein will now be described with reference to a flowchart depicted in <FIG>. The actions do not have to be taken in the order stated below, but may be taken in any suitable order. Actions performed in some embodiments may be marked with dashed boxes.

Action S210. In order to predict an upcoming sleeping state, the system <NUM> first obtains information of the cell <NUM>.

The information of a cell, e.g. cell <NUM>, which may also be referred to as a profile of the cell <NUM>, may comprise performance, configuration, and any other information of the cell <NUM>. For instance, the information of a cell may comprise a Random Access Channel (RACH) success rate, how many Radio Resource Controller (RRC) connection requests, how many RRC connection failures, a RRC connection success rate, how many RRC connected wireless devices, how many RACH requests, how many RACH failures, an uplink (UL) throughput, a downlink (DL) throughput, and/or a DL acknowledgment failure rate. Additional information may also be comprised in the information of the cell, which will be discussed below.

The information of the cell may be of the current moment or of any previous period such as the last <NUM> hours, the last seven days, the last one month, etc..

Action S220. The system <NUM> determines one or more sets of conditions based on the information.

A set of conditions may comprise a plurality of conditions, e.g., rules, indicating a profile change of the cell <NUM>, e.g., a performance change of the cell <NUM>.

For instance, the set of conditions may indicate one or more of: a decrease of the RACH success rate, a decrease of the downlink throughput or a decrease of the RRC connection success rate.

Optionally, said set or sets of conditions may be dynamically determined by using a machine learning algorithm. The machine learning algorithm may be trained to learn what conditions have been fulfilled when a profile change of the cell <NUM> has happened, and thus the machine learning algorithm may determine the one or more sets of conditions.

Action S230. The system <NUM> predicts that the cell <NUM> will enter the sleeping state when at least one set of the one or more sets of conditions is fulfilled.

The sleeping cell <NUM> may be identified by a cell identity (ID) or any other identification information of a cell.

The system <NUM> may predict whether or not the cell <NUM> will enter the sleeping state. Additionally or alternatively, the system <NUM> may predict a probability that the cell <NUM> will enter the sleeping state. The probability defines a percentage of chance that the cell <NUM> will enter the sleeping state. The probability may increase with more conditions in one set being fulfilled. In other words, the more conditions in one set that are fulfilled, the higher probability that the cell <NUM> will enter the sleeping state. For instance, if all conditions in one set are fulfilled the probability may be <NUM>%, if only partial conditions in one set are fulfilled the probability may be less than <NUM>%, e.g., <NUM>%. The skilled person will appreciate that the embodiments herein are not limited to any specific probability value, it can be a design option.

Action S240. The system <NUM> may output a recommended action to prevent the cell <NUM> from entering the sleeping state based on the probability and the number of wireless devices currently connected to the cell <NUM>.

Actions to prevent the cell <NUM> from entering the sleeping state may comprise a soft reset, a hard reset (also referred to as a node reset) or a locking of the cell <NUM>. Which one of the above actions to take may depend on the probability and the number of wireless devices currently connected to the cell. This can be a design option.

The number of wireless devices currently connected to the cell <NUM> may determine how much impact the switching into the sleeping state will have, as the number increases the severity of the impact increase. The impact may have different levels. As an example, the impact may comprise three levels with reference to an average number of connected wireless devices on the site. The impact may be: a critical level when the number of connected wireless devices on the cell <NUM> is higher than an average number; a major level when the number of connected wireless devices on the cell <NUM> is equal to or less than the average number; and an informative level when the number of connected wireless device on the cell <NUM> is close to zero.

The recommended action may be performed at times when there is low traffic, i.e., when a small or minimum number of wireless devices are connected on the cell <NUM>.

Embodiments herein enable a prediction of the cell <NUM> entering the sleeping state prior to it happening. Thereby it is possible to prevent the cell <NUM> from entering the sleeping state by performing any of the action mentioned above. Accordingly, various improvements on the performance of the wireless communication network, e.g., increased performance of cells, improved quality of service etc., will be achieved.

The system <NUM> may be implemented by either a conventional signal processing technique or the machine learning (ML) algorithm. A technical advantage of the ML algorithm is that it can take into account large number of variables and complex relationships among them, Moreover, the ML algorithm may adapt, e.g., the set or sets of conditions, the thresholds and/or time periods etc. over time.

The system <NUM> implemented by the ML algorithm for predicting a state of the cell <NUM> in the RAN <NUM> according to embodiments will now be described with reference to a flowchart depicted in <FIG>.

A ML algorithm in a data preparation module <NUM> will obtain information of the cell <NUM> as an input. The information of the cell <NUM> may be normalized data, which may comprise a performance measurement (PM), a configuration management (CM), and/or a measurement by a wireless device. The data preparation module <NUM> may clean up the normalized data, for example, by removing outliers. As shown in Table <NUM> below, possible information of the cell <NUM> can be obtained from different data sources.

As mentioned above, the information of the cell <NUM> may comprise various different types of information associated with the cell <NUM>. The ML algorithm, e.g., XGBoost, in the data preparation module <NUM> will select the information which have more influence on getting the cell <NUM> to go to the sleeping state. For instance, the selected information may be the RACH success rate. Then the ML algorithm, e.g., XGBoost, will generate complex information to be used for the prediction. The complexed information may be generated by complexing key performance indicator (KPI) values of the selected information in a time period, e.g., in the last one week. The time period may be configurable. The complexing may be performed by using a moving average (MA). For example, the complexed information for RACH success rate is the MA of RACH success rate for one week. That is to say, the output from the data preparation module <NUM> may be the complexed information of the cell <NUM>.

Then a prediction module <NUM>, e.g. by using a ML algorithm such as a decision tree, may determine the one or more sets of conditions associated with the complexed information. Since the information of the cell <NUM> is changing dynamically over time, the determination may also be dynamic over time. By using the information of the cell <NUM>, the ML algorithm may train the set or sets of conditions, the thresholds and/or time periods over time.

For instance, one set of the conditions may comprise one or more conditions associated with the RACH success rate specifying a decrease of the RACH success rate. The one or more conditions may specify the decrease of the RACH success rate by comparing the RACH success rates of different periods, e.g., a MA of the RACH success rate for the last seven days is higher than the MA of the RACH success rate for last <NUM> hours. Alternatively, the one or more conditions may specify the increase by using different thresholds, e.g., the MA of the RACH success rate in the last seven days is above a threshold, and the MA of the RACH success rate in the last <NUM> hours is lower than a threshold which threshold may be either the same or a different threshold from the previous threshold.

Similarly, another set of the conditions may comprise one or more conditions associated with the RACH success rate specifying a decrease of the DL throughput. Another set of the conditions may comprise one or more conditions associated with the RACH success rate specifying the decrease of the RRC connection success rate. Alternatively, another set of the conditions may comprise any combination of the above one or more conditions.

Furthermore, in order to get a more precise prediction, the set of the conditions may additionally be associated with other information of the cell <NUM>. For instance, the MA of the average number of RRC connected wireless devices for the last <NUM> is above a threshold, and/or a current DL acknowledgment failure rate is above a threshold.

Some exemplary sets of conditions are provided herein.

For ease of reading, embodiments herein are described in the context of a time period such as a current moment, the last <NUM> hours, the last seven days or the last one month. However the skilled person will appreciate that the embodiments herein also applies to other time references. Similarly, the embodiments herein are applicable to any type of MA such as an exponentially weighted moving average (EWMA).

Next step, the prediction module <NUM> may use the set or sets of conditions to predict whether or not the cell <NUM> will enter the sleeping state. If e.g. all conditions in one set are fulfilled, then the cell <NUM> will be predicted to enter the sleeping state. Alternatively, the prediction module <NUM> may predict the probability that the cell <NUM> will enter the sleeping state as mentioned above.

In case that the cell <NUM> has been predicted to enter the sleeping state, the prediction module <NUM> may output recommended action or actions, in order to enable a NOC engineer to prevent the cell <NUM> from entering the sleeping state. As shown in Table <NUM>, possible actions may be recommended depending on the probability and the number of wireless devices currently connected to the cell <NUM>.

The recommended action may involve a complete stoppage of service, which may make the situation worse after taking the action. Ideally the action may be taken during low traffic period which means that the minimum number of users will be impacted when the action is taken. Sometimes, manual intervention by the NOC engineer would be necessary if the NOC engineer believes that there is no low traffic time available and if the action is not taken then it will have adverse effects.

In order to assist the NOC engineer to take any necessary control action, the prediction module <NUM> may output the following information to the NOC engineer:.

The NOC engineer may provide feedback whether or not the cell <NUM> predicted to go to sleep actually went to sleep. If the feedback is negative, the ML algorithm in the data preparation module <NUM> will be retrained in order to improve the result.

By virtue of the embodiment herein, a prediction of the cell entering the sleeping state prior to it happening has been enabled. Thereby it is possible to prevent the cell from entering the sleeping state. Accordingly, various improvements on the performance of the wireless communication network, e.g., increased performance of cells, improved quality of service etc., will be achieved.

<FIG> is a block diagram depicting the system <NUM> for predicting the state of the cell <NUM> in the RAN according to embodiments herein. The system <NUM> may be located either in the NOC <NUM> or in a cloud. Different modules of the system <NUM> may also be located in different locations in a cloud.

The system <NUM> may comprise processing circuitry <NUM>, e.g., one or more processors, configured to perform the methods herein.

The system <NUM> may comprise the data preparation module <NUM>. The system <NUM>, the processing circuitry <NUM>, and/or the data preparation module <NUM> are configured to obtain information of the cell <NUM>.

The system <NUM> may comprise the prediction module <NUM>. The system <NUM>, the processing circuitry <NUM>, and/or the prediction module <NUM> are configured to determine one or more sets of conditions based on the information, and predict that the cell <NUM> will enter the sleeping state when at least one set of the one or more sets of conditions is fulfilled.

The system <NUM>, the processing circuitry <NUM>, and/or the prediction module <NUM> may also be configured to output an action to prevent the cell <NUM> from entering the sleeping state based on the probability and the number of wireless devices currently connected to the cell <NUM>.

The system <NUM> may further comprise a memory <NUM>. The memory comprises one or more units to be used to store data on, such as the inputs, outputs, thresholds, time period and/or the related parameters to perform the methods disclosed herein when being executed. Thus, the system <NUM> may comprise the processing circuitry <NUM> and the memory <NUM>, said memory <NUM> comprising instructions executable by said processing circuitry <NUM> whereby said system <NUM> is operative to perform the methods herein.

The methods according to the embodiments described herein for the system <NUM> are respectively implemented by means of e.g., a computer program product <NUM> or a computer program <NUM>, comprising instructions, i.e., software code portions, which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the system <NUM>. The computer program product <NUM> may be stored on a computer-readable storage medium <NUM>, e.g., a disc, USB or similar. The computer-readable storage medium <NUM>, having stored thereon the computer program product <NUM>, may comprise the instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the system <NUM>. In some embodiments, the computer-readable storage medium may be a non-transitory computer-readable storage medium.

As will be readily understood by those familiar with communications design, that functions means or modules may be implemented using digital logic and/or one or more microcontrollers, microprocessors, or other digital hardware. In some embodiments, several or all of the various functions may be implemented together, such as in a single application-specific integrated circuit (ASIC), or in two or more separate devices with appropriate hardware and/or software interfaces between them. Several of the functions may be implemented on a processor shared with other functional components of a radio base station, for example.

Claim 1:
A method for predicting a state of a cell (<NUM>) in a radio access network, RAN, the method comprising:
- obtaining (S210) information of the cell (<NUM>);
- determining (S220) one or more sets of conditions based on the obtained information, characterized in that at least one of said one or more sets of conditions indicates a decrease of a Random Access Channel, RACH, success rate; and
- predicting (S230) that the cell (<NUM>) will enter a sleeping state when at least one set of said one or more sets of conditions is fulfilled.