WO2023168646A1

WO2023168646A1 - Wireless network node supplied with power by a dc generator

Info

Publication number: WO2023168646A1
Application number: PCT/CN2022/080082
Authority: WO
Inventors: Qiang Liu; Lackis ELEFTHERIADIS
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-03-10
Filing date: 2022-03-10
Publication date: 2023-09-14

Abstract

The invention is concerned with a wireless network node and a wireless communication network comprising such a node as well as a method, computer program and computer program product for controlling a DC generator of a wireless network node. The wireless network node (12) is provided for a wireless communication network and comprises a group of radio communication units (34, 36, 38) comprising at least one radio communication unit, a DC generator (46) providing a voltage at which the radio communication units operate and a power supply control unit (32), which power supply control unit (32) obtains current operational data (39, COD1) from the radio communication units (34, 36, 38) of the group when the wireless network node operates with a first energy efficiency and provides the DC generator (46) with selected operational settings (51, NOS) causing the wireless network node (12) to operate with a second energy efficiency.

Description

WIRELESS NETWORK NODE SUPPLIED WITH POWER BY A DC GENERATOR

TECHNICAL FIELD

The invention generally relates to the supply of power of a wireless network node. More particularly, the invention relates to a wireless network node and a wireless communication network comprising such a wireless network node as well as to a method, computer program and computer program product for controlling a direct current, DC, generator of a wireless network node.

BACKGROUND

In wireless communication networks, such as mobile communication networks including Radio Access Networks (RAN) , powering the nodes is currently typically made by using an alternating current, AC, power grid, where power is fed to a node via a power supply unit (PSU) that converts from AC to direct current, DC, (AC/DC) and optionally also via an Automatic Transfer Switch (ATS) .

However, there are problems associated with the use of AC power from a power grid.

A wireless communication network may place nodes in different areas, such as urban, suburban and rural. In some instances, such as in some countries, there is need to improve not only the coverage and performance, but also enable and produce local electricity to be able to provide the wireless communication services. The generating of electricity may for instance be needed if there is no power grid or if there is a power grid that is poor or unstable.

Furthermore, also when a power grid is present and stable, there may be issues. Typically, there is a need for conversion between AC and DC for connection to the power grid, which conversion is made via the PSU, and this causes losses in the node.

There is therefore a need for an alternative or a complement in the way that power is supplied to a wireless network node.

One way to generate local power is to use an AC generator. However, also the AC generator typically employs an ATS and a PSU, with a consequential introduction of losses in the power flow from the power source to the node. Also, an AC generator requires an internal DC battery for starting the AC generator to enable future starts. This also makes the AC generator unnecessarily bulky and complex. Furthermore, in an AC generator the number of control parameters that can be varied are limited, in relation to the node operational settings.

There is therefore a need for an alternative in the way that local electricity is provided in a wireless network node and more particularly a need for an alternative that can provide a higher energy efficiency in the power flow from a power source, like a generator, to the node.

SUMMARY

One object of the invention is thus to improve energy efficiency of a wireless network node. Another object is to provide a sustainable operation of the wireless network node.

At least one of these objects is according to a first aspect achieved by a wireless network node for a wireless communication network, where the wireless network node comprises a group of radio communication units comprising at least one radio communication unit, a direct current, DC, generator that provides a voltage at which the radio communication units operate and a power supply control unit, where the power supply control unit is configured to:

obtain current operational data from the radio communication units of the group when the wireless network node operates with a first energy efficiency, and further provide the DC generator with selected operational settings causing the wireless network node to operate with a second energy efficiency, where the operational settings have been selected based on the current operational data of the radio communication units.

The at least one object is according to a second aspect achieved by a wireless communication network comprising the wireless network node according to the first aspect.

The at least one object is according to a third aspect achieved by a method of controlling a direct current, DC, generator of a wireless network node, the wireless network node comprising a group of radio communication units comprising at least one radio communication unit, a power supply control unit and the DC generator, where the DC generator provides a voltage at which the radio communication units operate. The method is performed in the power supply control unit and comprises:

obtaining current operational data from the radio communication units of the group when the wireless network node operates with a first energy efficiency, and providing the DC generator with selected operational settings causing the wireless network node to operate with a second energy efficiency, which operational settings have been selected based on the current operational data of the radio communication units.

The at least one object is according to a fourth aspect achieved by a computer program for controlling a direct current, DC, generator of a wireless network node, which wireless network node comprises a group of radio communication units comprising at least one radio communication unit, a power supply control unit and the DC generator, where the DC generator provides a voltage at which the radio communication units operate. The computer program comprises computer program code which when run by a processor of the wireless network node forming the power supply control unit implements the method steps according to the third aspect.

The at least one object is according to a fifth aspect achieved by a computer program product for controlling a direct current, DC, generator of a wireless network node, which computer program product comprises a data carrier with the computer program code according to the fourth aspect.

An energy efficiency may be an energy efficiency of the wireless network node, which may be the energy consumed by the node for operating the radio communication units during prevailing or predicted operating conditions, such as for operating the radio communication units with current and/or predicted traffic loads. The energy being consumed thereby comprises a contribution from the radio communication units. The energy being consumed also comprises a contribution from the DC generator, which is reflected by the electrical efficiency of the DC generator or the losses in the DC generator when generating power for the node. The energy efficiency may also comprise the efficiency or losses of a power flow from the DC generator to an electrical load of the wireless communication node, which electrical load comprises the group of radio communication units.

The operational settings may have been selected as operational settings that are known to cause the wireless network node to operate with the second energy efficiency when the radio communication units operate according to or with the current operational data.

The selected operational settings may furthermore be new operational settings and these new operational settings may also have been selected based on obtained current operational settings of the DC generator. In this case the new operational settings may additionally have been selected as operational settings known to cause the wireless network node to operate with the second energy efficiency when being changed to from the current operational settings.

In one variation of the first aspect, the power supply control unit is further configured to select the operational settings of the DC generator.

In a corresponding variation of the third aspect, the method further comprises selecting the operational settings of the DC generator.

Furthermore, the DC generator may be operated with fuel of one of a number of various fuel types and the operational settings may have been selected also based on the fuel type used. It is additionally possible that the DC generator has a fuel efficiency for the fuel type and that the operational settings have been selected also based on the fuel efficiency. The fuel efficiency may be provided using fuel efficiency metrics.

The current operational data of the group of radio communication units may comprise data about radio traffic load, such as a number of radio resources used and a number of connections set up to user equipment by each radio communication unit.

The operational settings for the DC generator may in this case also have been selected based on the current radio traffic load of the group of radio communication units.

In one variation of the first aspect, the power supply control unit may be further configured to predict the future radio traffic load of the group of radio communication units, which predicting may be based on the current radio traffic load.

In a corresponding variation of the third aspect, the method further comprises predicting the future radio traffic load of the group of radio communication units, which predicting may be based on the current radio traffic load.

In this case, the operational settings of the DC generator may have been selected also based on predictions of future radio traffic load of the group of radio communication units.

The current operational data may comprise data about a current power consumption of the group of radio communication units. The operational settings for the DC generator may thereby also have been selected based on the current power consumption.

It is additionally possible that the operational settings have been selected based on a prediction of a future power consumption of the group of radio communication units, which prediction of a future power consumption may be based on the prediction the future radio traffic load and/or the current power consumption.

In another variation of the first aspect, the power supply control unit is further configured to predict the future power consumption of the group of radio communication units.

In a corresponding variation of the third aspect, the method further comprises predicting the future power consumption of the group of radio communication units.

According to another variation of the first aspect, the power supply control unit is further configured to obtain a current voltage level used for supply of power in the wireless network node.

According to a corresponding variation of the third aspect, the method further comprises obtaining a current voltage level used for supply of power in the wireless network node.

In this case the operational settings that cause the wireless network node to operate with the second energy efficiency may also have been selected based on the current voltage level used for supply of power in the wireless network node.

The wireless network node may comprise an energy storage system. In this case, the consumed energy forming the energy efficiency may also comprise a contribution from the energy storage system, which is reflected by the losses when supplying power from and possibly also to the energy storage system. In this case the energy storage system may be a further power source. The energy efficiency may in this case also comprise the efficiency or losses of a power flow from the energy storage system to the electrical load, which includes the efficiency or losses of the energy storage system.

According to yet another variation of the first aspect, the power supply control unit is further configured to obtain current operational data of the energy storage system.

According to a corresponding variation of the third aspect, the method further comprises obtaining current operational data of the energy storage system.

In this case the operational settings that cause the wireless network node to operate with the second energy efficiency may also have been selected based on the current operational data of the energy storage system.

The current operational data of the energy storage system may comprise temperatures and/or voltages of energy storage units in the energy storage system.

The selected operational settings of the DC generator may comprise a new rotational speed of the DC generator. A new rotational speed may be advantageous if the second energy efficiency concerns an improvement of the efficiency of the DC generator, including an efficiency of the power flow from the DC generator to the electrical load.

The selected operational settings of the DC generator may additionally or instead comprise and propose a new output voltage of the DC generator. A new output voltage may be advantageous if the second energy efficiency involves a lowering of the power flow losses in the radio communication units.

The wireless network node may comprise a power grid interface comprising a group of power supply units with at least one power supply unit. In this case the consumed energy forming the energy efficiency may also comprise a contribution from the power grid interface, which is reflected by the electrical efficiencies of the power supply units or the losses in the power supply units when converting between AC and DC. In this case the power grid may be a further power source. The energy efficiency may in this case also comprise the efficiency or losses of a power flow from the AC grid to the electrical load, which includes the efficiency or losses of the power grid interface.

In a further variation of the first aspect, the power supply control unit may be further operative to provide the power supply units with a control signal corresponding to the new output voltage of the DC generator for controlling the power supply units to also supply the new output voltage.

In a corresponding variation of the second aspect, the method may in this case further comprise providing the power supply units with a control signal corresponding to the new output voltage of the DC generator for controlling the power supply units to also supply the new output voltage.

In another variation of the first aspect, the power supply control unit may be further operative to provide the energy storage system with a control signal corresponding to the new output voltage of the DC generator for ensuring that the operation of the energy storage system is aligned with the new proposed output voltage.

In a corresponding variation of the third aspect, the method may further comprise providing the energy storage system with a control signal corresponding to the new output voltage of the DC generator for ensuring that the operation of the energy storage system is aligned with the new output voltage.

The power grid interface may be connected to the power grid via an AC voltage connection that may comprise one or more AC cables. In this case the energy efficiency may also include the power losses of the AC voltage connection. The energy being consumed by the node may thus comprise a contribution from the power losses of the AC voltage connection. The efficiency of the power flow from the AC grid to the electrical load may in this case also comprise an efficiency or losses of the AC voltage connection.

The DC generator, the power grid interface and the energy storage system may be connected to the group of radio communication units via a power distribution system that may comprise at least one DC bus. In this case the energy efficiency may also include the efficiency or power losses of the power distribution system. The energy being consumed by the node may thus comprise a contribution from the power losses of the power distribution system, which may be a part of the efficiency of the power flow from the DC generator, the AC power grid and/or the energy storage system to the electrical load.

The invention according to the above-mentioned aspects has a number of advantages. Through the use of a DC generator an efficient, flexible, compact and simple power supply structure is provided, which is controlled to improve the energy efficiency of the wireless network node.

It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail in relation to the enclosed drawings, in which:

Fig. 1 schematically shows a wireless communication network comprising a number of wireless network nodes.

Fig. 2 schematically shows a first wireless network node of the wireless communication network comprising a number of radio communication units, a power grid interface, an energy storage system, a DC generator and a power supply control unit,

Fig. 3 schematically shows a first realization of the power supply control unit of the first wireless network node,

Fig. 4 schematically shows a second realization of the power supply control unit,

Fig. 5 shows a number of method steps in a first embodiment of a method of controlling the DC generator,

Fig. 6 schematically shows a number of method steps in a second embodiment of the method of controlling the DC generator,

Fig. 7 schematically shows a number of method steps for selecting of operational settings for the DC generator based on fuel type, and

Fig. 8 schematically shows a computer program product comprising a data carrier with computer program code for realizing the power supply control unit.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding of embodiments of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices, circuits and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

Aspects of the present disclosure are directed towards supplying of power in a wireless network node of a wireless communication network, which supply comprises supply of power from a direct current, DC, generator in relation to radio traffic variations.

Fig. 1 shows a wireless communication network WCN 10, which in this case is a mobile communication network. The network 10 comprises a number of wireless network nodes, which in the case of a mobile communication network are access nodes implementing base stations, sometimes referred to gNB or gNodeB. As an example there is a first wireless network node WNN1 12, a second wireless network node WNN2 14 and a third wireless network node WNN3 16. It should here be realized that there can be more wireless network nodes. However, there may also be fewer. It is even possible with only one wireless network node. In its simplest form the wireless communication network 10 thus only comprises the first wireless network node 12.

Fig. 2 schematically shows one realization of the first wireless network node WNN1 12.

The first wireless network node 12 comprises an interface to an alternating current, AC, power grid PG 18, i.e. a power grid interface PGI 20. The AC power grid 18 may be a three-phase power grid. Thereby, the power grid interface 20 is connected to a first phase A, a second phase B and a third phase C of the power grid 18. The power grid interface 20 has a first conductor leading to the first phase A, a second conductor leading to the second phase B and a third conductor leading to the third phase C, where these conductors are part of an AC power connection to the AC power grid. The power grid interface 20 also comprises an AC voltage distribution block ACDB 22 and at least one power supply unit connected to the AC voltage distribution block 22. In this case the power grid interface 2o comprises three separate power supply units. There is a first power supply unit PSUA 24 having a grid side connected to the ac voltage distributor distribution block 22, a second power supply unit PSUB 26 having a grid side connected to the AC voltage distributor distribution block 22 and a third power supply unity PSUC 28 having a grid side connected to the AC voltage distribution block 22. The AC voltage distribution block 22 comprises an AC voltage distributor that distributes power from or to the power grid 18 between the power supply units. The AC Voltage distribution block 22 may furthermore comprise one or more Circuit Breakers (CB) for protection, such as protection against overcurrents and short-circuits in the AC distribution block 22, thereby protecting the cables of the AC power connection and the other equipment of the power grid interface 20.

There is also a direct current, DC, generator DCG 46, which DC generator 46 comprises a control unit 48. There is thus a DC generator control unit DCGC 48 in the DC generator 46. The DC generator 46 is connected to a fuel tank FT 50, which comprises fuel of a type used to operate the DC generator 46.

There is furthermore an energy storage system ESS 40 in the first wireless network node 12, which energy storage system 40 comprises at least one energy storage unit, for instance in the form of a battery, which as an example may be a Li-ion battery or a valve regulated lead–acid (VRLA) battery.

The first wireless network node 12 also comprises a group of radio communication units, which radio communication units may include baseband and radio communication units, where in the example in fig. 2 the group comprises three radio communication units. There is a first radio communication unit RCU1 34, a second radio communication unit RCU2 36 and a third radio communication unit RCU3 38. These radio communication units are supplied with power from the DC generator 46 and possibly also from the AC power grid and/or the energy storage system 40. Because of this the

radio communication units

34, 36, 38 are connected to the power grid interface 20 and to the DC generator 46 via a local power distribution system PDS 30, where the power distribution system 30 may be a DC system operating at an internal node voltage, which node voltage thus is a DC voltage. In its simplest form the power distribution system may be realized as a DC bus.

As was mentioned above, the

power supply units

24, 26 and 28 have a grid side connected to the AC power grid 18. They also have a system side connected to the power distribution system 30. The

power supply units

24, 26 and 28 may be realized as AC/DC converters, which as an example may convert between 230VAC and a suitable DC voltage that may range between-58 and-42VDC. The

power supply units

24, 26 and 28 may for instance be realized as voltage source converters, such as two-level voltage source converters or modular multilevel converters (MMCs) , or as rectifiers.

Also, the DC generator 46 is connected to the power distribution system 30 as is the energy storage system 40. The energy storage system 40 may be connected to the power distribution system 30 via one or more converters, which converters may be DC/DC converters. Also the energy storage system 40 may be used to supply the radio communication units with power.

There is also a power supply control unit PSCU 32, which controls the power supply of the

radio communication units

34, 36 and 38. In order to do this, it communicates with the

radio communication units

34, 36 and 38 via a radio communication unit interface RCUI 39, with the energy storage system 40 via an energy storage system interface ESSI 41, with the DC generator control unit 48 via an operational settings interface OSI 51 and with the

power supply units

24, 26 and 28 via a control signal interface CSI 29. More particularly, the power supply control unit 32 obtains first current operational data COD1 of the

radio communication units

34, 36, 38 via the radio communication unit interface 39, optionally also obtains current operational settings COS of the DC generator 46 via the operational setting interface 51 and optionally obtains second current operational data COD2 of the energy storage system 40 via the energy storage system interface 41 as well as provides new operational settings NOS for the DC generator 46 over the operational settings interface 51 and optionally also supplies control signals CS to the

power supply units

24, 26, 28 via the control signal interface 29.

Finally, the power supply control unit 32 is shown as being connected to an operational settings selecting device 44 via a communication interface 42. The operational settings selecting device 44 may be provided as a part of a network manager unit provided in an Operation Support System (OSS) for the wireless communication network. In this case the communication interface 42 may be an interface to a backhaul network used for communication with the OSS. The operational settings selecting device 44 may as an alternative be implemented in the cloud and in this case the communication interface 42 may instead be a cloud communication interface.

It should additionally be realized that in some variations the power grid interface 20 may be omitted. In some other variations the energy storage system may be omitted and in some further variations both the power grid interface and the energy storage system may be omitted.

Fig. 3 schematically shows a first realization of the power supply control unit PSCU 32. It may be provided in the form of a processor PR 52 connected to a program memory M 54. The program memory 54 may comprise a number of computer instructions CI 56 implementing the functionality of the power supply control unit 32. The power supply control unit 32 may thereby be implemented as software. As an alternative it may be provided as hardware, such as through one or more application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs) .

Fig. 4 shows another realization of the power supply control unit PSCU 32. It comprises a radio control unit operational data obtainer RCUODO 58, which is an element that obtains operational data from the

radio communication units

34, 36 and 38. It also comprises an energy storage system operational data obtainer ESSODO 59, which is an element that obtains operational data from the energy storage system 40. Furthermore, the power supply control unit 32 also comprises a predictor P 60, which is an element for predicting the traffic load of the

radio communication units

34, 36 and 38. The predictor 60 may also be used to predict new efficient operating conditions/settings for the DC generator 46, such as the right voltage setting in relation to the radio traffic predictions.

There is also a node supply voltage obtainer NSVO 61, which is an element that obtains a supply voltage used in the first wireless network node 12. There is also an operational settings obtainer OSO 62, which is an element that obtains current operational settings used by the DC generator 46. There is furthermore an operational settings selector OSS 64, which is an element that selects operational settings to be used by the DC generator 46.Finally there is an operational settings provider OSP 66, which is an element that provides the selected operational settings to the DC generator 46.

The radio control unit operational data obtainer 58, the energy storage system operational data obtainer 59, node supply voltage obtainer 61 and the operational settings provider 66 are provided in the power supply control unit 32 in the first wireless network node 12. This is indicated through these units being shown in solid boxes.

However, the predictor 60, the operational settings obtainer 62 and the operational settings selector 64, may each be provided either in the power supply control unit 32 or in the operational settings selecting device 44. As the provision of these elements in the power supply control unit 32 is optional, they are shown in dashed boxes in fig. 4.

When the operational settings selector 64 is provided in the power supply control unit 32, it may with advantage be combined with the operational settings provider 66.

As was mentioned earlier, it is possible that the node 12 is provided without the energy storage system 40 and/or without the power grid interface 20. For this reason, it is also evident that it is possible to omit the energy storage system operational data obtainer 59. It is also possible that the node supply voltage obtainer 61 is omitted. Furthermore, some variations of the aspects described herein are performed without the use of predicted traffic load and operational settings obtained from the DC generator 48. It is therefore also possible to omit the predictor 60 and/or the operational settings obtainer 62 from the unit in which they are realized, i.e. from either the power supply control unit 32 or the operational settings selecting device 44.

The blocks in Fig. 4 may be provided as software blocks, for instance as software blocks in a program memory, or as hardware blocks, such as through one or more application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs) .

As has been mentioned earlier, there are situations when there is no power grid present for a wireless network node, such as the first wireless network node 12, or when there is such a power grid present, the grid may be of poor quality.

In these cases there is thus a need for producing local power. At the same time it is of interest that the energy efficiency of the wireless network node is high. Also sustainability may be an issue.

One way of producing local power is through the use of generators, such as AC or DC generators.

However, the feeding of power using an AC generator is typically made via an Automatic Transfer Switch (ATS) and a power supply unit (PSU) that converts between AC and DC. There is thus a loss of power. An AC generator also typically has an internal +12VDC battery that is used to recharge it to enable future starts. Apart from adding to the cost of the AC generator, this battery also makes the generator over-dimensioned. The AC generator is therefore also unnecessarily bulky. It also has a fairly low amount of control variables that can be controlled, which also makes it inflexible.

A DC generator may on the other hand be directly connected to the power distribution system. It does thus not need any conversion between AC and DC. Moreover, if there is an energy storage system in the wireless network node, the DC generator can use this system for starting, instead of the +12VDC battery. A DC generator may thus be made smaller than an AC generator and can be provided without the own +12VDC battery and a converter for converting to the voltage of the wireless network node.

A DC generator that is directly connected to the power distribution system 30 avoids one conversion step and improves the total efficiency of the wireless network node both in normal operation of the node, but also during charging/discharging of the batteries as compared with an AC generator.

The DC generator additionally has two control parameters that can be varied; the output voltage and the rotational speed.

There is room for improvement with regard to the use of a DC generator for powering of a wireless network node and then especially for improving the energy efficiency of the wireless network node, in relation to the dynamic radio traffic conditions.

Aspects of the present disclosure are directed towards improving the energy efficiency of the wireless network node through varying operational settings of the DC generator, like the control parameters rotational speed and/or output voltage.

How this may be done in the first wireless network node 12 will now be described with reference also being made to fig. 5, which shows a number of method steps in a method of controlling the DC generator 46, which method is performed by the power supply control unit 32.

At a current point in time, the first wireless network node 12 operates with a first energy efficiency, where the first energy efficiency may be the energy consumed by the node 12 for operating the radio communication units during prevailing operating conditions, such as for operating the radio communication units with current traffic loads. The energy being consumed thereby comprises a contribution from the

radio communication units

34, 36 and 38. The node may in this way have an electrical load comprising the

radio communication units

34, 36 and 38. The energy being consumed also comprises a contribution from the DC generator 46, which is reflected by the electrical efficiency of or the losses in the DC generator 46 when generating power for the node 12. The first energy efficiency may additionally comprise the efficiency of a first power flow from a first power source formed by the DC generator 46 to the electrical load via the power distribution system 30.

At the current point in time, the radio communication unit operational data obtainer 58 of the power supply control unit 32 obtains first current operational data COD1 from the

radio communication units

34, 36 and 38 of the group via the radio communication unit interface 39, step 68, which operational data may comprise radio traffic load data, such as data of the number of connections being set up to user equipment (UE) and the number of radio resources used for each of the connections. The first current operational data COD1 is thus obtained when the wireless network node operates with the first energy efficiency. The data may additionally comprise the current power consumption of each of the

radio communication units

34, 36 and 38. The first current operational data COD1 is then provided to the operational settings selector 64, which, as was mentioned earlier, may be provided in the power supply control node 32 or in the operational settings selecting device 44.

After having received the current operational data COD1 of the

radio communication units

34, 36 and 38, the operational settings selector 64 selects operational settings for the DC generator 46, which operational settings may be new operations settings NOS that cause the node 12 to operate with a second energy efficiency, step 70. The second energy efficiency may in this case be the energy consumed by the node 12 for operating the radio communication units with current or predicted operating conditions, such as for operating the radio communication units with current or predicted traffic loads. The selection may be based on the current operational data, and if the data comprises data about current traffic load, the selection may also be based on the current radio traffic load of the group of radio communication units. It can also be based on prediction of the future radio traffic load. When the selection is based on a prediction of the future traffic load, the operational settings selector 64 may instruct the predictor 60 to predict new operating conditions/settings for the DC generator 46, such as the right voltage setting in relation to the radio traffic load predictions.

The selected operational settings may comprise a rotational speed of a rotor of the DC generator 46 and/or an output DC voltage that the DC generator 46 is supposed to generate. The settings may additionally be settings that are known to cause the first wireless network node 12 to operate with the second energy efficiency when the radio communication units operate according to or with the current operational data. The selected operational settings are thus known to provide the second energy efficiency when the settings are applied by the DC generator 46 as the radio communication units operate according to or with the current operational data.

For this reason there may be a database or table with a mapping between operational data of the

radio communication units

34, 36 and 38, different operational settings of the DC generator 46 and different energy efficiencies. Such a table may have been obtained through measuring or calculating the energy efficiency of the wireless network node 12 for different combinations of operational data of the

radio communication units

34, 36 and 38 and operational settings of the DC generator 46 and selecting operational settings for the current operational data that corresponds to a desired second energy efficiency, which may be the highest energy efficiency that is available for the current operational data. The second energy efficiency may additionally comprise the efficiency of the first power flow from the DC generator 46 to the electrical load.

It is also possible that the second energy efficiency is obtained based on machine learning. In this case a machine learning system may have been trained with training data comprising different combinations of radio communication unit operational data, different operational settings for the DC generator and different energy efficiencies, where a reward is given for instance when the energy efficiency is high. The operational settings selector 64 may then select the operational settings of the DC generator 46 that provides a second energy efficiency that according to the trained system is the highest possible efficiency,

The second energy efficiency may thus be an energy efficiency that is higher than the first energy efficiency and may also be an energy efficiency that is optimal when considering the current operational data. The selected operational settings may furthermore comprise a set point defining a desired output voltage of the DC generator, which may be used to reduce the energy consumption contribution from the

radio communication units

34, 36 and 38 and/or a set point defining a desired rotational speed of the rotor of the DC generator 46, which may be used to reduce the energy consumption contribution from the DC generator 46.

When the operational settings have been selected, they are then provided from the operational settings selector 64 to the operational settings provider 66, which goes on and provides the DC generator 46 with the selected operational settings NOS causing the wireless network node 12 to operate with the second energy efficiency, step 72, where, as was stated above, these operational settings have been selected based on the first current operational data COD1 of the

radio communication units

34, 36, 38. The operational settings may be provided to the DC generator 46 through the operational settings provider 66 sending new operational settings NOS to the DC generator control unit 48 via the operational settings interface 51.

A second embodiment will now be described with reference being made to fig. 6, which shows a flow chart of the method of controlling the DC generator according to the second embodiment.

In this embodiment the selection of operational settings is also based on predictions of radio traffic load, current operational data related to power supply and/or power consumption by the node including current operational settings of the DC generator. The selection of operational settings may possibly also be based on the currently used DC voltage. Furthermore, in this case also settings in the node may include settings of the

power supply units

24, 26 and 28 in the power grid interface 20 and/or second current operational data COD2 of the energy storage system 40.

As in the first embodiment, the wireless network node 12 operates with a first energy efficiency at a current point in time, which may be the energy consumed by the node for operating the

radio communication units

34, 36 and 38 during current or prevailing operating conditions and comprising a contribution from the radio communication units, the DC generator 46 as well as from the energy storage system 40. If the energy storages of the energy storage system 40 are being charged, the electrical load may also comprise the energy storage system 40.

The first energy efficiency may, just as in the first embodiment, comprise the efficiency of a first power flow from the DC generator 46 to the electrical load. If the energy storage system 40 is used for supply of power, the first energy efficiency may also comprise the efficiency of a second power flow from the energy storage system 40 to the electrical load, which includes the efficiency of the energy storage system 40. In case the AC power grid 18 is used for supply of power, the energy efficiency may comprise a third power flow from the AC power grid 18 to the electrical load, which includes the efficiency or losses of the power grid interface. It may additionally comprise the power losses of the AC voltage connection. In all these flows the efficiency or losses in the power distribution system may also be included. The energy being consumed by the node may thus comprise a contribution from the power losses of the power distribution system, which may be a part of the efficiency of the power flow from the DC generator, of the power flow from the AC power grid and/or the power flow from the energy storage system to the electrical load.

At the current point in time, the radio communication unit operational data obtainer 58 of the power supply control unit 32 obtains radio traffic load data from the

radio communication units

34, 36, 38 of the group as first current operational data COD1, step 74, which radio traffic load data may again be data such as the number of connections being set up to UEs and the number of radio resources used for each of the connections. Radio resources may in this case comprise frequencies and time slots for instance in the form of Physical Resource Blocks (PRBs) . The information is provided from the radio communication unit operational data obtainer 58 to the predictor 60, which may, as was mentioned earlier be provided in the power supply control unit 32 or in the operational settings selecting device 44, The predictor 60 then predicts a traffic load in a future prediction time interval based on the current radio traffic load, step 76, which prediction may also be based on the time, like hours and minutes, and day of the week of the time interval as well as historical traffic loads for corresponding known time intervals.

The radio communication unit operational data obtainer 58 also obtains the current power consumption of the

radio communication units

34, 36 and 38, which may be based on the voltage levels at the radio communication units, step 78, which may be done through detecting the current voltage of the power distribution system 30 and/or the

radio communication units

34, 36 and 38 and the current delivered to the

radio communication units

34, 36 and 38. As an alternative it is possible to obtain the power consumption also based on the radio traffic load data.

It is additionally possible that the predictor 60 predicts a future power consumption of the group of radio communication units based on current power consumption of the

radio communication units

34, 36 and 38. The predicted future radio traffic load, which may be made for the same time interval as the traffic load prediction, may also be based on the prediction of the future radio traffic load.

At the current point in time also the node supply voltage obtainer 61 obtains the current DC voltage level used in the node, step 80. This may comprise obtaining the current output voltage of the DC generator 46, the current output voltage of the

power supply units

24, 26 and 28 and/or the current voltage of the energy storage system 40, i.e. the voltage at which the energy storage system 40 supplies or receives power to or from the power distribution system 30.

The energy storage system operational data obtainer 59 in this case also optionally obtains second current operational data COD2 of the energy storage system 40 via the energy storage system interface 41, which second current operational data COD2 may comprise temperatures and/or voltages of energy storage units, here batteries, in the energy storage system 40, where the temperatures may comprise the temperatures of lead acid batteries.

Furthermore, the operational settings obtainer 62 also obtains the current operational settings COS of the DC generator 46 in the form of the current control variables current rotational speed of the rotor and/or the current DC voltage being output by the DC generator 46, step 82. The operational settings obtainer 62 may obtain the current operational settings COS via the operational settings interface 51. If the node voltage has been previously obtained, it is possible to omit the obtaining of the output voltage of the DC generator 46. If the operational settings obtainer is provided in the operational settings selecting device 44, then the DC generator control unit 46 may send the current operational settings directly to the operational settings selecting device 44 using an appropriate own communication interface.

The collected data is then provided by the different data collecting elements to the operational settings selector 64, which as was mentioned earlier, may be provided in the power supply control unit 32 or in the operational settings selecting device 44.

After having received the traffic load data and current power consumption COD1 of the

radio communication units

34, 36 and 38 from the radio communication unit operational data obtainer 58, the predicted radio traffic load data from the traffic load predictor 60, the current DC voltage level from the node supply voltage obtainer 61, the current energy storage system operational data COD2 from the energy storage system operational data obtainer 59 and the current rotational speed and/or current output voltage of the DC generator 46 from the operational settings obtainer 62, the operational settings selector 64 selects operational settings for the DC generator 46 based on the obtained current operational data COD1 of the

radio communication units

34, 36 and 38 comprising the current radio traffic load and current power consumption and based on the obtained current operational settings COS of the DC generator 46, step 84. The new operational settings may additionally be selected based on the predictions of future radio traffic load, predictions of future power consumption, the current voltage level used for supply of power in the node and/or the current operational data COD2 of the energy storage system 44. When the selection is based on a prediction of the future traffic load, the operational settings selector 64 may instruct the predictor 60 to predict new operating conditions/settings for the DC generator 46, such as the right voltage setting in relation to the radio traffic load predictions.

The new operational settings may comprise a new rotational speed and/or a new output voltage of the DC generator 46 known to cause the node 12 to operate with the second energy efficiency. The settings may additionally be settings that are known to provide the second energy efficiency for the current and predicted traffic load and current power consumption of the

radio communication units

34, 36 and 38, the current energy storage system operational data COD2, the current DC voltage level and the current rotational speed and/or current output voltage of the DC generator 46. The new operational settings NOS may additionally have been selected as operational settings known to cause the wireless network node 12 to operate with the second energy efficiency when being changed to from the current operational settings. The second energy efficiency may in this case be the energy efficiency associated with the energy consumed by the node for operating the radio communication units during predicted operating conditions, i.e. for operating the

radio communication units

34, 36 and 38 with predicted traffic loads. A new rotational speed may in this case be selected when the losses in the DC generator 46 are to be changed, while a new output voltage may be selected when the energy being consumed by the

radio communication units

34, 36 and 38 is to be changed. A new output voltage may also influence the losses in the energy storage system 40 and/or the losses in the power grid interface 20, such as in the

power supply units

24, 26 and 28, and the power distribution system 30 (including all power cables) .

The selected operational settings may be new operational settings and these new operational settings may also have been selected based on obtained current operational settings of the DC generator. In this case the new operational settings may additionally have been selected as operational settings known to cause the wireless network node to operate with the second energy efficiency when being changed to from the current operational settings.

The second energy efficiency may comprise contributions from the same power flows that contributed to the first energy efficiency. Alternatively, it is possible that the some of the power flows differ. It is for instance possible that the second or third power flow is only present in one of the first and second energy efficiencies.

The way a selection is made may be made in the same way as described in the first embodiment. There may thus be a database or table with a mapping between the collected data, the different operational settings of the DC generator and different energy efficiencies. Such a table may have been obtained through measuring or calculating the energy efficiency of the node for different combinations of collected data and operational settings and then operational settings are selected that correspond to a desired second energy efficiency, which may be the highest energy efficiency that is available when starting from the first energy efficiency. It is also here possible that the second energy efficiency is obtained through machine learning, where a machine learning system has been trained with training data comprising different combinations of operational settings and operational and different energy efficiencies. The operational settings selector 64 may then select the operational settings of the DC generator 46 that provides the second energy efficiency that according to the trained system is the highest possible efficiency.

The new operational settings NOS may be operational settings that are known to cause the wireless network node 12 to operate with the second energy efficiency when being changed to from the current operational settings. The change from the current operational settings to the new operational settings is thus a change that is known to provide a change from the first energy efficiency to the second energy efficiency.

The second energy efficiency may also here be an energy efficiency that is higher than the first energy efficiency and may also be an energy efficiency that is optimal when considering the current operational data. The selected operational settings may also here comprise a set point defining a desired output voltage of the DC generator 46 and/or a set point defining a desired rotational speed of the rotor of the DC generator 46.

The operational settings are then provided from the operational settings selector 64 to the operational settings provider 66, which goes on and supplies the DC generator 46 with the selected new operational settings NOS that are known to cause the wireless network node 12 to operate with the second energy efficiency for the current radio traffic load, possibly together with for the predicted radio traffic load, for the current power consumption and/or for the current operational data of the energy storage system 40. The operational settings provider 66 thereby supplies a new rotational speed and/or a new output voltage to the DC generator 46, step 86. The new rotational speed and/or the new output voltage may also here be provided to the DC generator 46 through the operational settings provider 66 sending them to the DC generator control unit 48 via the operational settings interface 51.

Furthermore, if there is a new output voltage, the operational settings provider 66 may additionally supply a control signal CS corresponding to the new output voltage to the other power sources of the node, step 88. It thus supplies a control signal CS to the

power supply units

24, 26, 28 via the control signal interface 29 for controlling the

power supply units

24, 26 and 28 to also supply the new output voltage through converting to the new DC voltage. A similar control signal may be provided in relation to the energy storage system 40, for ensuring that the operation of the energy storage system 40 is aligned with the new output voltage of the DC generator 46.

It can thereby be seen that a rotational speed (RPM) and/or an output DC voltage is provided in relation to the actual and predicted radio traffic load. This may additionally be done fast in order to save energy in the node

The previously described scheme may be continuously performed. There may thereby be a number of iterations. In every iteration, the operational settings selector 64 receives current operational settings and current operational data and applies new operational settings of the DC generator 46 in relation to the observation of radio traffic and power consumption, thereby improving the energy efficiency.

The optimum energy efficiency may at the same time be evaluated by current and historical data, for every iteration to establish better and more accurate operational settings.

During operation, it is also possible that the best operational settings and power consumption is stored in historical logs.

The DC generator may thus be controlled so that it has a direct relation to and operation based on the actual and predicted radio traffic load.

Based on the radio traffic load and optionally also the power consumption, operation of variable speed and increase/decrease of the output DC voltage is enabled. This type of integrated control gives a tight operational control that enables higher efficiency. The higher efficiency is gained based on the close relationship to the radio traffic and rotational speed and voltage of the DC generator.

Furthermore, as the radio energy features are known, the dynamicity of the ON/OFF control of the radio communication units may be directly considered, providing improved savings, related to operation of the power flow with a DC generator.

The operation thus includes considerations that enable various type of radio traffic/different operating conditions in relation to the operating points or control variables for the DC generator.

It can in this way be seen that the energy efficiency of the wireless network node may be enhanced by enabling the DC generator to be controlled in relation to the radio traffic pattern and radio load conditions, to maximize the energy efficiency of the node. It is for instance possible to improve the efficiency of the power distribution by selecting a higher operational voltage. This may comprise the efficiency of the first power flow from the DC generator 46 to the electrical load comprising the group of

radio communication units

34, 36 and 38. If the energy storage system is used for supply of power, the improved efficiency may also comprise the efficiency of the second power flow from the energy storage system to the electrical load, which includes the efficiency of the energy storage system. In case the power grid is used for supply of power, the improved efficiency may comprise the efficiency of the third power flow from the AC grid to the electrical load. A changed rotational speed may change the operational efficiency of the DC generator 46, related to the fuel efficiency, i.e. the efficiency with which the rotor is being operated with a fuel in the fuel tank. An improvement of the efficiency of the DC generator 46 may of course also improve the efficiency of the first power flow.

Other advantages are: a smaller footprint and size of DC generator compared to existing AC generators, a low start up current and a related capability to operate on several and more sustainable fuels.

As was mentioned earlier, the contribution to the energy efficiency from the DC generator may be linked to the fuel used to operate it. It may additionally be possible to operate the DC generator with different types of fuel. The DC generator 46 may thus be operated with fuel of one of a number of fuel types.

One aspect that is directed towards the link to fuels will now be described with reference being made to fig. 7, which shows a number of method steps for selecting of operational settings for the DC generator based on fuel type that is used.

The tank 50 may be filled with fuel of a fuel type. The operational settings selector 64 may obtain information about the fuel type used, for instance through an operator having knowledge of what fuel is used and providing the operational settings selector 64 with this information. As one of several other alternatives it is possible that the fuel tank 50 has a fuel type detector, which informs the DC generator control unit 48 of the detected fuel type. The DC generator control unit 48 may then inform the operational settings obtainer 62 about the fuel type. Information about the fuel type may in this way be obtained by the operational settings obtainer 62, step 90. The DC generator 46 may additionally have a fuel efficiency linked to the fuel type. It thus has a fuel efficiency for the fuel type, such as the efficiency of the type in KWh/fuel type and/or liter/kWh consumption. It is possible that an operator provides fuel efficiency information to the operational settings selector 64. Alternatively, the DC generator control unit 48 may have or have access to the fuel efficiencies of the DC generator 46 for the different types of fuels. The DC generator control unit 48 may then inform the operational settings obtainer 62 about the fuel efficiency of the DC generator for the fuel type. Information about the fuel efficiency for the fuel type may in this way optionally also be obtained by the operational settings obtainer 62, step 92.

The operational settings obtainer 62 may in turn inform the operational settings selector 64. The operational settings selector 64 may then select operational settings based on the fuel type used and optionally also based on the fuel efficiency for the fuel type, step 94. It is here more particularly possible that the rotational speed of the DC generator 46 is selected based on the fuel type and the fuel efficiency.

Also various operating modes that are used in various types of nodes may be considered and a green index of operation related to fuel type for various types of nodes may be generated. The operation of the wireless network node may comprise:

a) Stand-alone mode (DC generator is the only power source including battery (small capacity) ) .

b) Power grid and DC generator (including battery (small capacity) ) .

c) Hybrid mode 12h/12h (Generator including battery (large capacity) .

d) Fuel type in relation @KWh usage (and CO2 emissions) .

It is furthermore possible to determine various green indexes for various fuel types.

Having this information, the wireless network node, which may operate on various fuel types, based on location, (urban, suburban, rural) , may apply different fuel type and control strategies. Local variations may have different opportunities of fuelling the site, and the kW/h may be calculated for each location.

The computer program instructions used for implementing the power supply control unit may be provided as a computer program that implements this unit when being run by a corresponding processor. As an alternative, the computer program may be included in a computer program product for instance as computer program code on a data carrier, such as a CD ROM disc or a memory stick. In this case the data carrier carries a computer program with the computer program code, which will implement the above-mentioned power supply control unit. One such data carrier 96 with the computer program code 56 is schematically shown in Fig. 8.

In the power supply control unit

■ the radio communication unit operational data obtainer may be considered to comprise means for obtaining current operational data from the radio communication units,

■ the operational settings selector, if present, may be considered to comprise means for selecting the operational settings of the DC generator, and

■ the operational settings provider may be considered to comprise means for providing the DC generator with selected operational settings.

Furthermore, the predictor, if present may be considered to comprise means for predicting the future radio traffic load of the group of radio communication units. It is additionally possible that the predictor is considered to comprise means for predicting the future power consumption of the group of radio communication units.

The node system voltage obtainer, if present, may in turn be considered to comprise means for obtaining a current voltage level used for supply of power in the wireless network node.

The energy storage system operational data obtainer, if present, may be considered to comprise means for obtaining current operational data of the energy storage system.

The operational settings obtainer, if present, may be configured to comprise means for obtaining current operational data of the energy storage system.

The operational settings provider may additionally be considered to comprise means for providing power supply units with a control signal corresponding to a new output voltage of the DC generator.

While aspects of the present disclosure have been described in connection with what is presently considered to be most practical and preferred embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements. Therefore, the disclosure is only to be limited by the following claims.

Claims

A wireless network node (12) for a wireless communication network (10) , the wireless network node (12) comprising a group of radio communication units (34, 36, 38) comprising at least one radio communication unit, a direct current, DC, generator (46) providing a voltage at which the radio communication units operate and a power supply control unit (32) configured to obtain (58) current operational data (39, COD1) from the radio communication units (34, 36, 38) of the group when the wireless network node operates with a first energy efficiency and further provide (66) the DC generator (46) with selected operational settings (51, NOS) causing the wireless network node (12) to operate with a second energy efficiency, which operational settings have been selected (64) based on the current operational data (COD1) of the radio communication units (34, 36, 38) .
The wireless network node (12) according to claim 1, wherein the operational settings have been selected (66) as operational settings that are known to cause the wireless network node to operate with the second energy efficiency.
The wireless network node (12) according to claim 1 or 2, wherein the selected operational settings (NOS) are new operational settings and where the new operational settings have also been selected based on obtained (62) current operational settings (COS) of the DC generator (46) .
The wireless network node (12) according to claim 3 when depending on claim 2, wherein the new operational settings (NOS) have been selected (64) as operational settings known to cause the wireless network node to operate with the second energy efficiency when being changed to from the current operational settings.
The wireless network node (12) according to any previous claim, wherein the power supply control unit (32) is further configured to select (64) the operational settings (NOS) of the DC generator (46) .
The wireless network node (12) according to any previous claim wherein the DC generator (46) is operated with fuel of one of a number of fuel types and the operational settings (NOS) have been selected also based on the fuel type used.
The wireless network node (12) according to claim 6, wherein the DC generator (46) has a fuel efficiency for the fuel type and where the operational settings (NOS) have been selected also based on said fuel efficiency.
The wireless network node (12) according to any previous claim, wherein the current operational data (COD1) of the group of radio communication units (34, 36, 38) comprises data about radio traffic load.
The wireless network node (12) according to claim 8, wherein the operational settings (NOS) that are selected for the DC generator (46) are also based on predictions of future radio traffic load of the group of radio communication units (34, 36, 38) .
The wireless network node (12) according to claim 9, wherein the power supply control unit (32) is further configured to predict (60) the future radio traffic load of the group of radio communication units (34, 36, 38) .
The wireless network node (12) according to any previous claim, wherein the current operational data (COD1) comprises data about a current power consumption of the group of radio communication units.
The wireless network node (12) according to any previous claim, wherein the power supply control unit (32) is further configured to obtain (61) a current voltage level used for supply of power in the wireless network node (12) and where the operational settings that cause the wireless network node (12) to operate with the second energy efficiency have also been selected (64) based on the current voltage level used for supply of power in the wireless network node (12) .
The wireless network node (12) according to any previous claim, wherein the wireless network node (12) comprises an energy storage system (40) and the power supply control unit (32) is further configured to obtain (59) current operational data (41, COD2) of the energy storage system (40) and the operational settings that cause the wireless network node (12) to operate with the second energy efficiency have also been selected (64) based on the current operational data (COD2) of the energy storage system (40) .
The wireless network node (12) according to claim 13, wherein the current operational data of the energy storage system (40) comprises temperatures and/or voltages of energy storage units in the energy storage system.
The wireless network node (12) according to any previous claim, wherein the selected operational settings (NOS) of the DC generator (46) comprise a new rotational speed of the DC generator (46) .
The wireless network node (12) according to any previous claim, wherein the selected operational settings (NOS) of the DC generator (46) comprise a new output voltage of the DC generator (46) .
The wireless network node (12) according to claim 16, wherein the wireless network node (12) comprises a power grid interface (20) comprising a group of power supply units (24, 26, 28) with at least one power supply unit, wherein the power supply control unit (32) is further operative to provide the power supply units (24, 26, 28) with a control signal (29, CS ) corresponding to the new output voltage of the DC generator (46) for controlling the power supply units (24, 26, 28) to also supply the new output voltage.
A wireless communication network (10) comprising the wireless network node (12) according to any previous claim.
A method of controlling a direct current, DC, generator (46) of a wireless network node (12) , the wireless network node (12) comprising a group of radio communication units (34, 36, 38) comprising at least one radio communication unit, a power supply control unit (32) and the DC generator (46) providing a voltage at which the radio communication units operate, the method being performed in the power supply control unit (32) and comprising:

obtaining (68; 74, 78) current operational data (COD1) from the radio communication units (34, 36, 38) of the group when the wireless network node operates with a first energy efficiency, and

providing (72; 86) the DC generator (46) with selected operational settings (NOS) causing the wireless network node (12) to operate with a second energy efficiency, which operational settings have been selected (70; 84) based on the current operational data (COD1) of the radio communication units (34, 36, 38) .
The method according to claim 19, wherein the selected operational settings (NOS) are new operational settings and where the new operational settings have also been selected based on obtained (82) current operational settings (COS) of the DC generator (46) .
The method according to any of claims 19 -20, further comprising selecting (70 ; 84) the operational settings (NOS) of the DC generator (46) .
The method according to claim any of claims 19 -21, wherein the DC generator (46) is operated with a fuel of one of a number of fuel types and the operational settings (NOS) have been selected (94) also based on the fuel type used.
The method according to claim 22, wherein the DC generator (46) has a fuel efficiency for the fuel type and where the operational settings (NOS) have been selected (94) also based on said fuel efficiency.
The method according to any of claims 19 -23, wherein the current operational data (COD1) of the group of radio communication units (34, 36, 38) comprise radio traffic load and the operational settings (NOS) that are selected for the DC generator (46) are also based on predictions of future radio traffic load of the group of radio communication units (34, 36, 38) .
The method according to claim 25, further comprising predicting (76) the future radio traffic load of the group of radio communication units (34, 36, 38) .
The method according to any of claims 19 –25, wherein the wireless network node (12) comprises an energy storage system (40) and further comprising obtaining (81) current operational data (COD2) of the energy storage system (40) and the operational settings that cause the wireless network node (12) to operate with a second energy efficiency have also been selected based on the current operational data (COD2) of the energy storage system (40) .
The method according to any of claims 19 -26, wherein the selected operational settings (NOS) of the DC generator (46) comprise a new output voltage of the DC generator (46) .
The method according to claim 27, wherein the wireless network node (12) comprises a power grid interface (20) comprising a group of power supply units (24, 26, 28) with at least one power supply unit, the method further comprising providing (88) the power supply units (24, 26, 28) with a control signal (CS) corresponding to the new output voltage of the DC generator (46) for controlling the power supply units (24, 26, 28) to also supply the new output voltage.
A computer program for controlling a direct current, DC, generator (46) of a wireless network node (12) , the wireless network node (12) comprising a group of radio communication units (34, 36, 38) comprising at least one radio communication unit, a power supply control unit (42) and the DC generator (46) providing a voltage at which the radio communication units operate, the computer program comprising computer program code (56) which when run by a processor (52) of the wireless network node (12) forming the power supply control unit (32) implements the method steps according to any of claims 19 -28.
A computer program product for controlling a direct current, DC generator (46) of a wireless network node (12) , the computer program product comprising a data carrier (96) with said computer program code (56) according to claim 29.