WO2019192698A1

WO2019192698A1 - Operation of energy harvesting access points

Info

Publication number: WO2019192698A1
Application number: PCT/EP2018/058688
Authority: WO
Inventors: Kari Heiska; Oleksandr PUCHKO; Soheil ROSTAMI; George Koudouridis
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-04-05
Filing date: 2018-04-05
Publication date: 2019-10-10

Abstract

It is an object to provide an energy harvesting access point, EH-AP, device and a master access point, M-AP, device. The EH-AP device can utilize available energy sources and stored energy that has been harvested from such energy sources. Furthermore, the EH-AP device can utilize a backhaul link to communicate with the M-AP device and utilize an access link to provide wireless connectivity for at least one client device. Thus, the EH-AP device can be flexibly positioned regardless of external wired resources. Using signalling between the EH-AP device and the M-AP device, the EH-AP device and/or the M-AP device can efficiently manage the power consumption of the EH-AP device. An EH-AP device, an M-AP device, methods and a computer program are described.

Description

OPERATION OF ENERGY HARVESTING ACCESS POINTS

TECHNICAL FIELD

The disclosure relates to a field of wireless radio communications, and more particularly to an energy harvesting access point device and a master access point device in a wireless radio communication. Furthermore, the disclosure relates to corresponding methods and a computer program.

BACKGROUND

In ultra-dense networks, UDNs, the density of access points, APs, is significantly increased from what is used in current wireless communication technologies, such as in LTE or 4G. Due to this high AP density, UDNs may be able to provide significantly higher capacity density and are therefore a promising technology for upcoming wireless networks, such as new radio, NR. However, UDNs also introduce new practical challenges. For example, the APs require a source of energy and a backhaul connection, which may complicate the deployment of the APs when the AP density is high. Furthermore, the amount of traffic in the network may vary significantly over time. Therefore, unused APs may consume unnecessary energy during, for example, low traffic hours. All of these drawbacks may increase operational expenses of UDNs.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

It is an object to provide an energy harvesting access point device and a master access point device. The object is achieved by the features of the independent claims. Further implementation forms are provided in the dependent claims, the description and the figures.

According to a first aspect, an energy harvesting access point, EH-AP, device is configured to: measure energy harvesting, EH, information based on harvested energy; wherein the EH-AP device further comprises: an access transceiver, ACC-TRX, configured to: provide wireless connectivity for at least one client device; a backhaul transceiver, BH-TRX, configured to: transmit the EH information to a master access point, M-AP, device; receive a control message from the M-AP device, wherein the control message is based on the transmitted EH information; and a processor, configured to: determine control parameters based on information comprised in the received control message; control operation of the BH-TRX and the ACC-TRX using the control parameters. Using these configurations, the EH-AP device can, for example, efficiently manage its power consumption based on the harvested energy and any additional information provided by the M-AP.

In an implementation form of the first aspect, the EH-AP device further comprises: an energy subsystem, ESS, configured to: harvest energy from an energy source; and store the harvested energy in an energy storage. When the EH-AP comprises the ESS, the EH-AP can be positioned with high flexibility, and the EH-AP may not be dependent on any external wired resources.

In a further implementation form of the first aspect, the processor is further configure to: manage the power consumption of the EH-AP device according to an energy utilization threshold, wherein the information in the control message comprises the energy utilization threshold. The energy utilization threshold can be associated at least with one of stored energy, energy harvesting rate, and energy consumption rate of the EH-AP device. Using the energy utilization threshold, the EH-AP device can, for example, efficiently manage its power consumption based on a single threshold value.

In a further implementation form of the first aspect, the BH-TRX and the ACC-TRX are further configured for a discontinuous reception, DRX; and wherein the processor is further configured to: utilize a settings for the discontinuous reception, DRX, wherein the control parameters in the control message comprises the settings for the discontinuous reception DRX. Using these configurations, the EH-AP can save power by, for example, using a longer DRX cycle so that the BH- TRX and/or the ACC-TRX are active and consuming power less often.

In a further implementation form of the first aspect, the ACC-TRX is further configured to: receive an at least one uplink, UL, pilot signal from the at least one client device; wherein the processor is further configured to: determine an UL measurement report based on the received at least one UL pilot signal; wherein the BH-TRX is further configured to: transmit the, UL measurement report to the M-AP, as configured by the control parameters. Using these configurations, the M- AP device can, for example, estimate the potential traffic volume of the EH-AP device, and the M-AP and/or the EH-AP can take this estimate into account when managing the power consumption of the EH-AP device.

In a further implementation form of the first aspect, the processor is further configured to: evaluate downlink, DL, pilot signals according to the control parameters; wherein the ACC-TRX is further configured to: transmit the DL pilot signals. Using these configurations, the M-AP device can, for example, estimate the potential traffic volume of the EH-AP device, and the M-AP and/or the EH-AP can take this estimate into account when managing the power consumption of the EH-AP device.

In a further implementation form of the first aspect, the EH-AP device is configured to a first mode of operation, wherein the BH-TRX is active and the ACC- TRX is inactive. Using these configurations, the EH-AP device can, for example, communicate with the M-AP device while the ACC-TRX is not consuming significant amounts of power.

In a further implementation form of the first aspect, the EH-AP device is configured to a second mode of operation, wherein the BH-TRX and ACC-TRX are active. Using these configurations, the EH-AP device can, for example, communicate with the M-AP device and with the at least one client device.

In a further implementation form of the first aspect, the EH-AP device is configured to a third mode of operation, wherein the BH-TRX and ACC-TRX are active and user data is configured to be transmitted from the EH-AP device to the at least one client device. Using these configurations, the EH-AP can, for example, communicate with the M-AP device and with the at least one client device.

In a further implementation form of the first aspect the EH-AP device is configured to switch from a current mode of operation to one of the first, second or third mode of operation based on the control parameters received from the M-AP device. Using these configurations, the EH-AP can, for example, efficiently manage its power consumption by switching between the different modes of operation.

According to a second aspect, a master access point, M-AP, device, comprises a master backhaul transceiver, BH-TRX, configured to: receive an energy harvesting, EH, information from an energy harvesting access point, EH- AP, device, wherein the EH information comprises an information about harvested energy in the EH-AP device; and a processor configured to: determine a control message based on the EH information, wherein the control message comprises information that the EH-AP device is configured to use in order to control a BH- TRX of the EH-AP device and an ACC-TRX of the EH-AP device; wherein the BH- TRX is further configured to transmit the control message to the EH-AP device. Additionally, the M-AP device may use any other available information, such as traffic volume estimates, to determine the information in the control message. The information in the control message may comprise, for example, control parameters or the information may be such that the EH-AP device is configured to deduce the control parameters from the information. Using these configurations, the M-AP device can, for example, efficiently manage the power consumption of the EH-AP device.

In an implementation form of the second aspect, the processor is further configured to: calculate an energy utilization threshold based on the EH information, wherein the energy utilization threshold is associated at least with one of stored energy, energy harvesting rate, and energy consumption rate of the EH- AP device. Using the energy utilization threshold, the M-AP device can, for example, efficiently manage the power consumption of the EH-AP device based on a single threshold value.

In a further implementation form of the second aspect, the master BH-TRX is further configured to: transmit the energy utilization threshold to the EH-AP in the control message. Using these configurations, the M-AP device can, for example, efficiently manage the power consumption of the EH-AP device by transmitting this single threshold value to the EH-AP device.

In a further implementation form of the second aspect, the processor is further configured to: determine at least one control parameter based on the energy utilization threshold; wherein the master BH-TRX is further configured to: transmit the at least one control parameter to the EH-AP device in the control message. Using these configurations, the M-AP device can, for example, offload some computations from the EH-AP device to the M-AP device.

In a further implementation form of the second aspect, the M-AP further comprises an ACC-TRX, and the ACC-TRX is configured to: transmit an uplink UL, client control message to the at least one client device, wherein the UL client control message comprises control information about UL pilot signals to be transmitted by the at least one client device to the EH-AP device; and wherein the master BH-TRX is further configured to: receive an UL measurement report from the EH-AP device, wherein the UL measurement report comprises measurement results for the UL pilot signals transmitted by the at least one client device; and wherein the processor is further configured to: estimate traffic volume of the EH- AP device based on the received UL measurement report; determine the control message based on the estimated traffic volume. Using these configurations, the M-AP device can, for example, use the additional information provided by the estimated traffic volume to more effectively manage the power consumption and traffic volume of the EH-AP device.

In a further implementation form of the second aspect, the master BH-TRX is further configured to: receive a downlink, DL, client control message from a second M-AP device; wherein the ACC-TRX is further configured to: relay the DL client control message to the at least one client device; and receive a DL measurement report from the at least one client device; and wherein the master BH-TRX is further configured to: relay the DL measurement report to the second M-AP device. Using these configurations, the M-AP device can, for example, help the second M-AP device to estimate the potential traffic volume of an EH-AP device even if the EH-AP device is connected to the second M-AP device and the client device is connected to the M-AP device.

In a further implementation form of the second aspect, the processor is further configured to determine the control message based on amount of harvested and/or stored energy in the EH-AP device indicated by the EH information. Using these configurations, the M-AP device can, for example, efficiently manage the power consumption of the EH-AP device.

In a further implementation form of the second aspect, the processor is further configured to: estimate traffic volume of the EH-AP device; and determine the control message based on the estimated traffic volume. Using these configurations, the M-AP device can, for example, use the additional information provided by the estimated traffic volume to more effectively manage the power consumption and traffic volume of the EH-AP device. According to a third aspect, a method comprises measuring energy harvesting, EH, information based on harvested energy; providing wireless connectivity for at least one client device; transmitting the EH information to a master access point, M-AP, device; receiving a control message from the M-AP device, wherein the control message is based on the transmitted EH information; and determining control parameters based on information comprised in the received control message; controlling operation of the BH-TRX and the ACC-TRX using the control parameters. Using this method, the EH-AP device can, for example, efficiently manage its power consumption based on the harvested energy and any additional information provided by the M-AP.

According to a fourth aspect, a method comprises receiving an energy harvesting, EH, information from an energy harvesting access point, EH-AP, device, wherein the energy harvesting information comprises information about harvested energy in the EH-AP device; determining a control message based on the EH information, wherein the control message comprises information that the EH-AP is configured to use in order to control a backhaul transceiver, BH-TRX, of the EH-AP device and an access transceiver, ACC-TRX, of the EH-AP device; transmitting the control message to the EH-AP device. Using this method, the M- AP device can, for example, efficiently manage the power consumption of the EH- AP device.

According to a fifth aspect, a computer program is provided, comprising program code configured to perform a method according to the third aspect or the fourth aspect when the computer program is executed on a computer.

Many of the implementation mentioned above will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

The present description will be better understood from the following detailed description read in light of the accompanying drawings, wherein:

FIG. 1 illustrates a schematic representation of an energy harvesting access point device according to an example;

FIG. 2 illustrates a schematic representation of a master access point device according to an example; FIG. 3 illustrates a schematic representation of wireless communication system according to an example;

FIG. 4 illustrates a schematic representation of a wireless communication system according to another example;

FIG. 5 illustrates a schematic representation of selected components of an energy harvesting access point device according to an example;

FIG. 6 illustrates a schematic representation of connections between users and access points according to an example;

FIG. 7 illustrates a schematic representation of connections between a master access point and multiple energy harvesting access points according to an example;

FIG. 8 illustrates a schematic representation of a signalling diagram according to an example;

FIG. 9 illustrates a schematic representation of downlink pilot signals according to an example;

FIG. 10 illustrates a schematic representation of uplink pilot signals according to an example;

FIG. 1 1 illustrates a schematic representation of a signalling diagram according to another example;

FIG. 12 illustrates a schematic representation of a signalling diagram according to another example;

FIG. 13 illustrates a schematic representation of client device handover according to another example;

FIG. 14 illustrates a schematic representation of a signalling diagram according to another example;

FIG. 15 illustrates a schematic representation of a signalling diagram according to another example;

FIG. 1 6 illustrates a schematic representation connections between users and access points before handovers;

FIG. 17 illustrates a schematic representation connections between users and access points after handovers;

FIG. 18 illustrates a schematic representation of a signalling diagram according to another example; FIG. 19 illustrates a schematic representation of a signalling diagram according to another example;

FIG. 20 illustrates a schematic representation of energy harvesting access point operation modes according to an example; and

FIG. 21 illustrates a schematic representation of energy harvesting access point power consumption in different operation modes according to an example.

Like references are used to designate like parts in the accompanying drawings.

DETAILED DESCRIPTION

The detailed description provided below in connection with the appended drawings is intended as a description of the embodiments and is not intended to represent the only forms in which the embodiment may be constructed or utilized. However, the same or equivalent functions and structures may be accomplished by different examples.

FIG. 1 illustrates a schematic representation of an energy harvesting access point, EH-AP, device 100 according to an example. The EH-AP may also be referred to as an autonomous access point, A-AP. The EH-AP device 100 comprises a processor 101 , a backhaul transceiver, BH-TRX, 103, and an access transceiver, ACC-TRX, 104. The EH-AP device 100 may further comprise an energy subsystem, EES, 102. Alternatively, some other device that can be connected to the EH-AP device 100 may comprise the ESS 102.

According to an aspect, the EH-AP device 100 is configure to measure energy harvesting, EH, information based on harvested energy. The EH information may comprise, for example, the rate of energy harvesting, the rate of energy consumption, the amount of available harvested energy in an energy storage, the amount of harvested energy during a predetermined time interval, the amount of consumed energy during a predetermined time interval, an prediction of the aforementioned quantities, a deviation from a prediction of the aforementioned quantities, or some combination of these.

According to an aspect, the ACC-TRX 104 is configured to provide wireless connectivity for at least one client device. A single client device or multiple client devices can be connected to the EH-AP device 100 via the ACC-TRX 104. The EH-AP device 100 may provide wireless connectivity for all connected client devices or for some subset of connected client devices. The wireless connectivity may comprise, for example, internet access, phone calls, data transfer, or some combination of these.

According to an aspect, the backhaul transceiver, BH-TRX, 103 is configured to transmit the EH information to a master access point, M-AP, device 200 and to receive a control message from the M-AP device 200, wherein the control message is based on the transmitted EH information.

According to an aspect, the processor 101 is configured to determine control parameters based on information comprised in the received control message and to control operation of the BH-TRX and the ACC-TRX using the control parameters. The information in the control message can comprise control parameters, or the EH-AP device 100 can be configured to deduce control parameters from the information.

EH-AP device 100 and/or the ESS 102 may collect energy to be used by the EH-AP device 100 from available energy sources, such as solar panels and wind turbines. The harvested energy can be stored in batteries and transformed for the use of the EH-AP device 100 when needed. The energy harvesting power may depend, for example, on the intensity of the received sun radiation or wind speed at the particular base station location and may be timely independent on the power needs of the EH-AP device 100 for communication needs.

The capacity need of the mobile network may vary over time being in its maximum during busy hours and in its minimum during low traffic periods, such as night times. Using the invention, mobile networks can be dimensioned to have its maximum active AP density during the peak hours while during low traffic periods the majority of the APs can be switched off in order to save energy.

According to an example, mmWave links can be used for AP backhauling. This together with the energy harvesting abilities of the EH-APs 100 can make the implementation of access nodes independent of location of energy grid wires and wired backhaul, such as optical fibre.

Use of EH-APs in ultra-dense network, UDN, environment can enable fast installation of EH-APs within the M-AP coverage area, low operational expenses and cheap, energy efficient deployment of small cell networks. The EH-AP site location can be planned based on availability of the wireless backhaul. FIG. 2 illustrates a schematic representation of a master access point, M- AP, device 200 according to an example. The M-AP device 200 comprises a processor 201 , a master backhaul transceiver, BH-TRX, 202. The M-AP device 200 may further comprise an access transceiver, ACC-TRX, 203.

According to an aspect the master BH-TRX 202 is configured to receive an energy harvesting, EH, information from the EH-AP device 100, wherein the EH information comprises an information about harvested energy in the EH-AP device 100, and the processor 201 is configured to determine a control message based on the EH information. The control message comprises information that the EH- AP device is configured to use in order to control the BH-TRX 103 of the EH-AP device 100 and the ACC-TRX 104 of the EH-AP device 100. The processor may, for example, deduce control parameters from the EH information, and the information in the control message may comprise the control parameters. The M- AP device 200 may also use, for example, traffic volumes, traffic volume estimates, and EH estimates to determine the control parameters and/or information in the control message. An estimate of a quantity, such as power consumption or traffic volume, may be an estimate of the current value of the quantity, or it may be an prediction of the value of the quantity during, for example, some upcoming time interval.

The control parameters may comprise, for example, commands for the EH- AP device 100 to switch between different modes of operation or commands to switch off some components of the EH-AP device 100, such as the BH-TRX 103 or the ACC-TRX 104. Alternatively, the information may comprise, for example, a power consumption limit or an energy utilization threshold.

According to an aspect, the master BH-TRX 203 is further configured to transmit the control message to the EH-AP device 100.

The EH-AP device 100 or the M-AP device 200 may further comprise a memory (not illustrated in FIG. 1 or in FIG. 2) that is configured to store, for example, computer programs and data. The memory may include one or more volatile memory devices, one or more non-volatile memory devices, and/or a combination of one or more volatile memory devices and non-volatile memory devices. For example, the memory may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, and semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

FIG. 3 illustrates a schematic representation of a wireless communication system according to an example. The wireless communication system comprises an EH-AP device 100, an M-AP device 200, and a client device 300. The client device 300 further comprises a transceiver, TRX, 301 . The client device 300 may be any of a User Equipment (UE) in Long Term Evolution (LTE), mobile station (MS), wireless terminal or mobile terminal which is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The client device 300 may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The client device 300 in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice or data, via a radio access network, with another entity, such as another receiver or a server. The client device 300 can be a Station (STA) which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM).

The EH-AP device 100 and the M-AP device 200 can communicate with each other using a backhaul, BH, link 302 and the BH-TRX 103, 202 of each device. Furthermore, the EH-AP device 100 can communicate with the client device 300 using access link 304, and the M-AP device 200 can communicate with the client device 300 using access link 303. The EH-AP device 100 and/or the M- AP device 200 can utilize the access links 303, 304 to provide wireless connectivity for the client device 300. This wireless connectivity can comprise, for example, internet access and data transfer. Although only a single client device 300 is depicted in FIG. 3, the EH-AP device 100 and the M-AP device 200 can form access links with a plurality of client devices using the ACC-TRXs 104, 203 and provide wireless connectivity for the plurality of client devices.

The M-AP device 200 may be a base station, a (radio) network node or an access node or an access point or a base station, e.g., a Radio Base Station (RBS), which in some networks may be referred to as a transmitter, “eNB”, “eNodeB”,“gNB,“gNodeB”,“NodeB”, or“B node”, depending on the technology and terminology used. The radio network nodes may be of different classes such as, e.g., macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network node can be a Station (STA) which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM).

FIG. 4 illustrates a schematic representation of wireless communication system with self-backhauling links according to an example. The wireless communication system of FIG. 4 may be similar to that of FIG. 3. However, in the example of FIG. 4, in the EH-AP device 100 and in the M-AP device 200, a single transceiver, TRX, comprises both the BH-TRX and the ACC-TRX. In the EH-AP device 100, the TRX 105 comprises the BH-TRX 103 and the ACC-TRX 104, and in the M-AP device 200, the TRX 204 comprises the master BH-TRX 203 and the ACC-TRX 203. Therefore, the EH-AP device 100 may use the TRX 105 both for the BH link 302 and for the access link 304. Similarly, the M-AP device 200 may use the TRX 204 both for the BH link 302 and for the access link 303.

FIG. 5 illustrates a schematic representation of selected components of the EH-AP device 100 according to an example. The EH-AP device 100 comprises the ESS 102, and the ESS 102 may further comprise a battery 105, a solar panel 106, a wind turbine 107, and a regulator 108. Alternatively, the EH-AP device 100 may not comprise the ESS 102, but the ESS 102 is only connected to the EH-AP device 100 so that the ESS 102 can provide power for the EH-AP device 100. The solar panel 106 and the wind turbine 107 are only examples of energy sources that the EH-AP device 100 may utilise. The ESS 102 may also comprise a single energy source or any combination of different energy sources. Energy harvested by the ESS 102 from the solar panel 106 and the wind turbine 107 may be stored into the battery 105. The battery 105 is only an example of an energy storage, and the ESS 102 may comprise any single energy storage or any number of different energy storages. The regulator 108 may regulate the power produced by the solar panel 106 and the wind turbine 107 in order to efficiently store the harvested energy and prevent any potential damage to the battery 105 or to any other component caused by, for example, voltage peaks. As is illustrated in FIG. 5, the ESS 102 may be configured to power the BH-TRX 103 and the ACC-TRX 104 using the stored and harvested energy. Furthermore, the ESS 102 may be configured to power any other component of the EH-AP device 100, such as the processor 101 . FIG. 6 illustrates a schematic representation of various users that are connected to an EH-AP device 100 and to an M-AP device 200. Users 600 are connected to the M-AP device 200, and the M-AP device 200 may provide wireless connectivity for the users 600. Users 600’ are connected to the EH-AP device 100, and the EH-AP may provide wireless connectivity for the users 600’. Furthermore, the EH-AP device 100 and the M-AP are connected through the BH link 302. The M-AP device 200 may use the BH link 302 to control the EH-AP device 100 or to send information to the EH-AP device 100 that the EH-AP device 100 can use to control itself. The EH-AP device 100 can also use the BH link 302 to send information to the M-AP device 200 related to, for example, the energy harvesting and power consumption of the EH-AP device 100.

FIG. 7 illustrates a schematic representation of multiple EH-AP devices 100 and M-AP device 200 according to an example. Three EH-AP devices 100 are connected to a single M-AP device 200. The number of EH-AP devices 100 connected to a single M-AP device 200 in FIG. 7 is only exemplary, and any number of EH-AP devices 100 can be connected to a single M-AP device 200.

Herein, some functionality of the EH-AP device 100 is described using different modes of operation. These modes, their functionality, and naming are only exemplarily and are only used to describe possible operation of EH-AP in different situations.

According to an example, the EH-AP device 100 may comprise three working modes: a sleep mode, an idle mode and a connected mode. When in the sleep mode, the EH-AP device 100 is sleeping consuming minimum amount of energy. During the idle mode the EH-AP device 100 can inform its energy harvesting state and it can also be controlled by the M-AP device 200. During the idle mode the EH-AP device 100 is also able to transmit/receive pilot signals needed for the AP identification and traffic volume estimation. In the energy harvesting networking, the idle mode may be needed to enable stable transition between the energy efficient sleep mode and the high energy consuming connected mode. In the connected mode, the EH-AP device 100 may work like a normal EH-AP enabling high data rate communication between the M-AP device 200, EH-AP device 100 and a client device 300.

According to an example, the idle mode comprises two sub-modes: idlel and idle2. Idlel and idle2 modes may differ in their functional and power consumption characteristics. During the idlel mode, the BH link can follow pre defined discontinuous reception, DRX, or Wake-up patterns. With the DRX, the BH link 302 is waking up periodically following a DRX pattern determined by the DRX configuration. During the DRX active periods the EH-AP device 100 can send EH information, such as battery charging levels, energy harvesting intensity and power consumption information, to the M-AP device 200 and the M-AP device 200 can send, for example, new DRX configuration information and other controlling data including the mode change commands to the EH-AP device 100. In order to improve the energy efficiency and the availability of the EH-AP operation, the DRX cycle can be dependent on the current EH status. During idlel mode, the EH-AP ACC-TRX 104 may not be active except in the self-backhauling case.

FIG. 8 illustrates a schematic representation of a signalling diagram between the EH-AP device 100 and the M-AP device 200 according to an example. Before the signalling, the EH-AP device 100 may be, for example, in idlel mode. The M-AP device 200 can transmit default discontinuous reception, DRX, parameters 801 to the EH-AP device 100 in a control message, and the EH-AP device 100 can use the DRX parameters 801 in operation 802. This may be referred to as the connection set-up phase.

When the EH-AP device 100 uses DRX, it only transmits messages to the M-AP device 200 during certain time periods. The length and timing of these time periods can be configured, for example, using the DRX settings. This may help the EH-AP device 100 to conserve battery, since it may turn off the BH-TRX 103 when no messages are transferred between the EH-AP device 100 and the M-AP device 200. Alternatively, in idlel mode, the EH-AP device 100 may follow predefined wake-up patterns. Furthermore, during idlel mode, the ACC-TRX 104 of the EH- AP device 100 may be inactive except for the self-backhauling case presented in FIG. 4.

The EH-AP device 100 may transmit energy harvesting, EH, information 803 to the M-AP device 200. The EH information 803 may also be referred to as EH data. The EH information 803 may comprise any information about the ESS 102 of the EH-AP device 100. For example, the EH information 803 may comprise battery charge level, battery discharge rate, energy harvesting rate, energy consumption of some component, total energy consumption of the EH-AP device 100, or some combination of these. Herein, terms charge level and energy level may be used interchangeably. The EH-AP device 100 may periodically switch itself on, synchronizes to the M-AP device 200 and send the EH information to the M-AP device 200 after which it may switch itself off.

After receiving the EH information 803 from the EH-AP device 100, the M- AP device 200 may assess the status of the EH-AP device 100 based on the EH information 803. For example, the M-AP device 200 may compare the amount of stored energy E in the EH-AP device 100 to some threshold value E_thl in operation 804. If the amount of stored energy is below the threshold value, the M-AP device 200 may transmit a switch off command 805 to the EH-AP device 100 in a control message. When the EH-AP device 100 receives the switch off 805 command, it may transition to a sleep mode 807 in operation 806. In the sleep mode 807, both the ACC-TRX 104 and the BH-TRX 103 of the EH-AP device 100 may be switched off, while the ESS 102 may still be operational in order to harvest energy and measure the harvested energy. The EH-AP device 100 may turn back on based on, for example, a preconfigured time delay or when the stored energy level is above a preconfigured threshold. This turn on condition may be configured, for example, by the EH-AP device 100 or by the M-AP device 200 via a control message.

On the other hand, if the M-AP device 200 assesses in operation 804 that the amount of stored energy in the EH-AP device 100 is not below the threshold, the M-AP device 200 may instead calculate new DRX parameters for the EH-AP device 100 in operation 808. Furthermore, the M-AP device 200 may make a state change decision for the EH-AP device 100 in operation 809. The new DRX parameters and the change state decision can be based on, for example, the EH information or any other information that is available to the M-AP device 200 about the EH-AP device 100. For example, if the amount of stored energy in the EH-AP device 100 is low, the M-AP device 200 may configure the DRX cycle to be longer so that the EH-AP device 100 can conserve energy. The M-AP device 200 may transmits the new DRX settings and a state change command to the EH-AP device 100 in a control message 810. The control massage 810 may also be referred to as control data, and it may comprise also other information, such as EH measurement and update intervals. After receiving the control message 810, the EH-AP device 100 may use the new DRX settings in operation 81 1 . Furthermore, the EH-AP device 100 may change its mode in operation 812 based on the control message 810. For example, the EH-AP device 100 may transition to a connected mode 813 or to so called idle mode 2 814. If the mode is not changed in operation 812, the EH-AP device 100 may transmit a new EH information 815 to the M-AP device 200, and the same process may continue.

Idle2 mode may be similar to idlel mode. However, in idle2, the ACC-TRX 104 of the EH-AP device 100 may be active. Depending whether downlink, DL, or uplink, UL, based mobility scheme is used, the EH-AP device 100 may send or receive pilot signals to/from client devices with predefined signal sequences and predefined timing and frequency.

FIG. 9 illustrates a schematic representation of downlink, DL, pilot signal measurements according to an example. Two client devices 300 and an EH-AP device 100 are within the coverage area 901 of an M-AP device 200. Furthermore, the client devices 300 are in the coverage area 902 of the EH-AP device 100. The EH-AP device 100 transmits DL pilot signals 903 to the client devices 300, and based on the received DL pilot signals, the client devices 300 can transmit DL measurement reports 904 to the M-AP device 200.

FIG. 10 illustrates a schematic representation of uplink, UL, pilot signal measurement according to an example. The situation is similar to that of FIG. 9. However, now the client devices 300 transmit UL pilot signals 903 to the EH-AP device 100. Based on the received UL pilot signals, the EH-AP device 100 can then transmit an UL measurement report 1004 to the M-AP device 200.

FIG. 1 1 illustrates a schematic representation of a signalling diagram in DL pilot signal measurements according to an example. This may illustrate signalling for a situation similar to, for example, FIG. 9. The EH-AP device 100 may transmit EH information 803 to the M-AP device 200. The M-AP device 200 may then transmit a control message 1 101 to the EH-AP device 100. The control message 1 101 may comprise information that the EH-AP device 100 may use to evaluate DL pilots signals. Furthermore, the M-AP device 200 may transmits DL client control messages 1 102 to client devices 300. For example, the control message 1 101 and the DL client control message 1 102 may comprise the reserved time and frequency resources as well as the pilot signal sequences. The client device 300 may be within the coverage area of the EH-AP device 100. The DL client control messages 1 102 may configure the client devices 300 to receive the pilot signals to be transmitted by the EH-AP device 100. The EH-AP device 100 may then transmit the pilot signals 903 to the client devices 300 according to the control message 1 101 . Based on the received and measured DL pilot signals, the client devices 300 can transmit DL measurement reports 904 to the M-AP device 200, wherein the DL measurement reports 904 comprise information about the measured DL pilot signals. The DL pilot signal measurement can be, for example, reference signal received power, RSRP, measurements. The DL measurement reports 904 may comprise, for example, average measurement over a time specified by the control message.

Based on the measurement reports 904, the M-AP device 200 may estimate the current or upcoming traffic under the EH-AP device 100 in operation 1 104 and use this estimate for controlling the EH-AP device 100. For example, if the M-AP device 200 estimates that there is a high potential traffic volume for the EH-AP device 100 and that the EH-AP device 100 has sufficient power, the M-AP device 200 may choose to switch the ACC-TRX 104 of the EH-AP device 100 on in operation 1 105. The M-AP device 200 may transmit this switch on command to the EH-AP device 100 in a control message 1 106. Furthermore, the M-AP device 200 may transmit control messages 1 107 to the client devices 300 in order to hand over the traffic of the client device 300 to the EH-AP device 100.

FIG. 12 illustrates a schematic representation of a signalling diagram in UL pilot signal measurements according to an example. This may illustrate signalling for a situation similar to, for example, FIG. 10. The EH-AP device 100 may transmit EH information 803 to the M-AP device 200, and in response, the M-AP device 200 may transmit a control message 1201 to the EH-AP device 100. The control message 1201 may configure the EH-AP device 100 to receive UL pilot signals to be transmitted by the client devices 300. Furthermore, the M-AP device 200 may transmits UL client control messages 1202 to client devices 300. For example, the control message 1201 and the UL client control messages 1202 may comprise the reserved time and frequency resources as well as the pilot signal sequences. The UL client control messages 1202 may comprise information that the client devices 300 may use to evaluate pilots signals. The client device 300 may be within the coverage area of the EH-AP device 100. The client devices 300 may then transmit the UL pilot signals 1003 to the EH-AP device 100 according to the UL client control messages 1202. Based on the received and measured UL pilot signals, the EH- AP device 100 can transmit an UL measurement a report 1004 to the M-AP device 200, wherein the UL measurement report 1004 comprises information about the measured UL pilot signals 1003.

Based on the UL measurement report 1004, the M-AP device 200 may estimate the traffic under the EH-AP device 100 in operation 1 104 and use this estimate for controlling the EH-AP device 100. For example, if the M-AP device 200 estimates that there is a high potential traffic volume for the EH-AP device 100 and that the EH-AP device 100 has sufficient power, the M-AP device 200 may choose to switch the ACC-TRX 104 of the EH-AP device 100 on in operation 1 105. The M-AP device 200 may transmit this switch on command to the EH-AP device 100 in a control message 1 106. Furthermore, the M-AP device 200 may transmit control messages 1 107 to the client devices 300 in order to hand over the traffic of the client device 300 to the EH-AP device 100.

The M-AP device 200 can allocate different resources for the pilot signals dynamically so they can vary from one allocation to another. The starting point and ending point of the measurements as well as the frequency of measurement report sending is controlled by the M-AP device 200 by using above mentioned control messages. The EH-AP device 100 can utilize this information for power saving purposes by being in the low power state mode during the time between the pilot signal transmissions/receptions. The power state mode can be DRX sleep mode or low bandwidth model in bandwidth part, BWP, in which case the control message 1 101 and the client control message 1202 may comprise DRX/BWP parameterization. When controlling the EH-AP pilot power it is possible to optimize the EH-AP energy load by changing the cell size of the EH-AP device 100.

Based on the averaged signal strength measurements from each client device 300, the data volume used by each client device, and the EH information, the M-AP device 200 can predict the load, the throughput and coverage performance and the power consumption of the EH-AP device 100 and of the M- AP device 200 after the EH-AP switch ON. Based on the prediction, M-AP device 200 can make the switch ON decision after which it can send a control message 1 106 to the EH-AP device 100 for supporting switch ON procedures and control message 1 107 to client devices for supporting handover procedures.

FIG. 13 illustrates a schematic representation of a client device 300 moving in the coverage area of neighbouring M-PAs. The moving client device 300 is connected to M-AP2 200’, and the client device 300 is within the coverage area 1303 of M-AP2 200’. However, due to the movement, the client device 300 may move to the coverage area 1302 of an EH-AP device 100, and the EH-AP device 100 may not be connected to M-AP2 200’, but the EH-AP device 100 may be connected to M-AP1 200. Furthermore, when the client device 300 moves to the coverage area 1302 of the EH-AP device 100, it does not necessarily move to the coverage area 1301 of M-AP1 200. Thus, M-AP1 200 or M-AP 2 200’ may not be able to use the pilot signalling of FIG. 1 1 or FIG. 12 to assess, for example, if handover of the client device 300 to the EH-AP device 100 may be beneficial.

M-AP1 200 should transmit EH-AP related pilot information and measurement and transmission request information to M-AP2 200’ after the EH- AP installation and initial configuration phase. M-AP2 200’ should forward this information to all of its client devices which according to the request start either measuring the DL pilot signals from the EH-AP device 100 or start transmitting UL pilot signals to the EH-AP device 100. Similarly, measurement reports and control messages should be routed via M-AP2 200’. There can always be one to several EH-APs 100 under M-AP1 200 control in which case M-AP1 200 can send pilot information and measurement (DL) or transmission (UL) request information of all of the EH-APs 100 to neighbouring M-APs that are relevant from mobility perspective.

FIG. 14 illustrates a schematic representation of a signalling diagram in DL pilot signal measurements with multiple M-APs according to an example. This may illustrate signalling for a situation similar to, for example, FIG. 13. The signalling diagram of FIG. 14 is similar to that of FIG. 1 1 . However, now the signalling is presented only for a single client device, and because the client device 300 is connected to M-AP2 200’, all communication between the client device 300 and M-AP1 200 should be relayed through M-AP2 200’. M-AP2 200’ can receive the DL client control message 1 102 from M-AP1 200 via BH-TRX 202 of the M- AP2 200’, and relay this message to the client device 300 via the ACC-TRX 203. The DL client control message 1 102 control of this functionality can be implemented by the processor 201 of the MP-AP2 200’. For example, after the DL client control message 1 102 has been received by the BH-TRX 202, the processor can identify the message type and choose to relay the message to the client device using the ACC-TRX 203. Similarly, M-AP2 200’ can receive a DL measurement report 1 103 from the client device 300 using the ACC-TRX 203, and the DL measurement report 1 103 can be relayed to M-AP1 200 via the BH-TRX 202.

Using this relaying, M-AP1 200 may assess if handover of the client device 300 to the EH-AP device 100 is beneficial even when the client device 300 is connected to M-AP2 200’ and EH-AP device 100 is connect to M-AP1 200.

FIG. 15 illustrates a schematic representation of a signalling diagram in UL pilot signal measurements with multiple M-APs according to an example. This may illustrate signalling for a situation similar to, for example, FIG. 13. The signalling diagram of FIG. 15 is similar to that of FIG. 12. However, now the signalling is presented only for a single client device, and because the client device 300 is connected to M-AP2 200’, all communication between the client device 300 and M-AP1 200 is relayed through M-AP2 200’ in a similar fashion with the DL pilot signal measurement case described above. Using this relaying, M-AP1 200 may assess if handover of the client device 300 to the EH-AP device 100 is beneficial even when the client device 300 is connected to M-AP2 200’ and EH-AP device 100 is connect to M-AP1 .

According to an example, in the connected mode, both the EH-AP ACC- TRX 103 and the BH-TRX 104 can be active. The BH link 302 can be controlled by the M-AP device 200, for example, by configuring appropriate BWP in order to find the most energy efficient transmission mode without compromising with the latency. Furthermore, in the connected mode, the access link 304 between the EH-AP device 100 and the client device 300 can be governed so that the EH-AP device 100 can operate at an energy-saving or energy-preserving state in which an EH-AP device 100 preserves its energy surplus. Preserving energy surplus of an EH-AP device 100 within a certain time period can be performed by the M-AP device 200 and implies that the EH-AP device 100 may harvest and reserve more energy within the set time period than it consumes on average. This can be effectively implemented based on an energy utilization ratio that is associated at least with one of stored energy, energy harvesting rate, and energy consumption rate of the EH-AP device. For example, the energy utilization ratio may be defined as the ratio of energy reserves and harvesting, characterizing the available energy, and energy consumption, characterizing the required energy. In one example, the energy utilization ratio E_u over a time period t may be expressed as follows

where E_c(t denotes the average or total energy consumption during time period t, E_H(t) denotes the average or total energy harvesting during the time period t, and E_R (t denotes the average or total residual energy that a battery may provide during the time period t. Units of these quantities may be expressed, for example, in joules, in watt hours, or in kilowatt hours. In a another example, the energy utilization ratio may be expressed in terms of powers, where E_c, E_R and E_H may be given, for example, in watts. In another definition, the E_R maybe omitted and the energy utilization may be simply defined as the ratio of E_c and E_H.

In full connected mode, the energy consumption rate could be higher than the energy harvesting rate resulting in using residual energy from the battery reserves. In the full connected state, the M-AP device 200 may not be actively controlling the load of the EH-AP device 100 but may send the switch-on and switch-off commands based on the energy levels and/or predicted traffic requirements, depending on the selected strategy.

In energy-preserving connected state, on the other hand, the M-AP device 200 can determine the traffic load to be assigned to the EH-AP device 100 so that the energy utilization ratio as defined above is below a certain energy utilization threshold value, wherein the energy utilization threshold is associated at least with one of stored energy, energy harvesting rate, and energy consumption rate of the EH-AP device 100. The energy-preserving connected state may enable continuous operation of the EH-AP device 100 at the cost of total served capacity by the EH-AP device 100. The energy utilization threshold is typically set so that the energy reserves increase as a function of time. It regulates the pace of the energy increase in the EH-AP device 100 as determined and communicated to the EH-AP device 100 by the M-AP device 200. Occasionally, the energy utilization threshold can be set to control the pace at which the energy reserves of an EH-AP device 100 may decrease.

In one example, a client device 300 may be a dual connectivity UE, DC-UE, with an M-AP device 200 as a primary AP and an EH-AP device 100 as a secondary AP. The EH-AP device 100 can inform periodically the M-AP device 200 of its energy utilization ratio and the M-AP device 200 may reassign users and/or packets so as, whenever possible, to optimize the energy load and to keep the energy utilization of the EH-AP device 100 close to a target value. Alternatively, the EH-AP device 100 may inform the M-AP device 200 periodically the charging level of the battery and the energy production over predefined time unit. The M-AP device 200 can utilize these values in order to calculate the average energy consumption and the energy utilization ratio.

Reporting the energy utilization ratio regularly could be used to monitor the energy harvesting and/or consumption of the EH-AP device 100. In one particular case of interest, an EH-AP device 100 in energy-preserving connected state may report a deviation of that state when the traffic load unexpectedly increases and the energy utilization ratio increases above the energy utilization threshold.

In addition, the energy utilization ratio can be further used to optimize the EH-AP device 100 usage based on a prediction of the average charging rate of the battery within a certain period. Assuming that the M-AP device 200 knows the data amount, it can use the harvested energy information to try to model the charging level as a function of traffic load so that the M-AP device 200 is then able to optimize the EH-AP device 100 usage.

For instance, for an upcoming time period, the M-AP device 200 may determine the average amount of energy that the BH-TRX 103 and ACC-TRX 104 in the EH-AP device 100 would require based on the traffic load (energy demand) assigned to it. At the same time, the EH-AP device 100 may determine battery energy reserves and the possibility to harvest certain amount of energy on average (energy availability). Keeping the energy utilization ratio for the time period above the utilization threshold implies that more energy is produced than consumed within that time period. In another example, the energy utilization ratio E_u maybe expressed as ratio of the expected values over a time period t as follows

where E_c(t ) denotes the expected energy consumption, E_H (t) denotes the expected energy harvesting, and E_R t) denotes the expected residual energy that a battery may provide on average during the time period t. Deviation from this goal would be attributed to either traffic load increase or energy harvesting and battery level energy decrease. As a result, it would require the control of the M-AP device 200 so as to ease the traffic load and reduce the energy demand. Occasionally, an M-AP device 200 controlling multiple EH-AP devices 100 may distribute the traffic load among the EH-AP devices 100 taking into account the battery supply reserves and the energy utilization ratio. To this end, depending on the traffic load and wherever possible it may allow for a certain time that some EH-AP devices 100, typically the fully charged ones, operate in full connected mode with an energy utilization ratio above the utilization threshold. This could effectively release the traffic load pressure at neighbour EH-AP devices 100 with lower battery charging levels giving them time to charge the batteries by operating at energy utilization ratio below the utilization threshold. The optimization of the energy and traffic requirements may be performed by the M-AP device 200 by means of assignments of the users and their traffic to appropriate EH-AP devices 100 as well as suitable DTRX/BWP configuration of the EH-APs 100.

A main effect of the energy utilization ratio may be that it provides means to regulate the utilization of the EH-AP device 100. The energy utilization ratio may provide a single but effective indicator that may allow for the M-AP device 200 to control the EH-AP device 100 which monitors and report deviations within certain time period. Deviations may occur due to a decrease in the average rate of energy harvesting (e.g., wind vanishing or strength/speed fluctuations) or an increase in the average energy consumption rate (e.g., traffic load increase). As a response an M-AP device 200 may control the traffic load of the EH-AP device (i.e., users served by EH-AP device 100) so as the EH-AP device 100 can operate within certain levels of energy utilization.

FIG. 1 6 and FIG. 17 illustrate schematic representations of user assignment between multiple EH-AP devices according to an example. In FIG. 1 6, EH- AP1 100_1 , EH_AP2 100_2, and EH_AP3 100_3 are connected to a single M-AP device 200. Furthermore, user 600_1 and user 600_2 are assigned to EH- AP1 100_1 , and user 600_3 and user 600_4 are assigned to EH-AP3 100_3. No users are assigned to EH-AP2 100_2. This may be, for example, because EH- AP2 100_2 is offloaded to increase the energy utilization ratio of EH-AP2 100_2 and to allow EH-AP2 100_2 some time to charge its battery. When the battery in EH-AP2 100_2 is charged, the EH-AP2 100_2 can be transferred to connected mode and a partial transfer of user load to EH-AP2 100_2 from the other EH-APs may occur as determined by the M-AP device 200. This situation is presented in FIG. 17. Furthermore, as is shown in FIG. 17, the M-AP device 200 may decide to fully offload, for example, EH-AP1 100_1 (preferably putting it into an idle-mode) and partially offload EH-AP3 100_3 so that the latter operates with an energy utilization ratio that is greater than the energy utilization threshold. Thus, in FIG. 17, two users, user 600_2 and user 600_3 are assigned to EH-AP2 100_2, no users are assigned to EH-AP1 600_1 , user 600_4 is still assigned to EH- AP3 100_3, and user 600_1 is assigned to the M-AP device 200.

FIG. 18 illustrates a schematic representation of a signalling diagram for M- AP centric power consumption control according to an example. The EH-AP device 100 may transmit EH information 803 to the M-AP device 200. Based on the EH information and other information available, such as DL or UL measurement reports, the M-AP device 200 may predict the traffic volume of the EH-AP device 100 in operation 1 104. This traffic prediction can be based on, for example, past stored data on diurnal or daily variations of the traffic under the EH-AP device 100. Based on the predicted traffic volume and other available information and/or predictions, the M-AP device 200 can set a new energy utilization threshold for the EH-AP device 100 in operation 1801 . Based on the new energy utilization threshold and, for example, energy level thresholds and traffic throughput thresholds, the M-AP device 200 can perform power consumption control for the EH-AP device 100 in operation 1802. For example, the M-AP device 200 may calculate new control parameters for the EH-AP device 100 and then transmit the control parameters to the EH-AP device 100 in a control message 810. These control parameters may comprise, for example, total used power, discontinuous transmission, DTX, parameters, discontinuous reception, DRX, parameters, bandwidth part parameters, pilot powers, utilized bandwidth, number of beams, width of beams, and sub-frames, direct commands for the EH-AP device 100, or some combination of these.

FIG. 19 illustrates a schematic representation of a signalling diagram for EH-AP centric power consumption control according to an example. The first operations of the signalling diagram of FIG. 19 are similar to those in FIG. 18. However, in FIG. 19, after the M-AP device 200 has calculated the energy utilization threshold in operation 1801 , the M-AP device 200 may transmit the energy utilization threshold to the EH-AP device 100 in a control message 810. Based on the received energy utilization threshold, the EH-AP device 100 can calculate control parameters so that the energy utilization ratio remains below the energy utilization threshold. These control parameters may be similar to those describe for the M-AP centric case.

FIG. 20 illustrates a schematic representation of different operation modes for the EH-AP device 100 according to an example. The variables governing the transitions between these modes can be, for example, the energy level data, energy consumption data, energy forecast data, traffic data, traffic forecast data, and energy utilization data. The EH-AP device 100 can send this data to the M-AP device 200 for the state transition decisions. Selection between idlel 2021 and idle2 814 modes in idle mode 2020 and Full Connected 2031 state and Energy Preserving state 2032 can be considered as a choice for an operator.

FIG. 21 illustrates a schematic representation of the EH-AP device 100 power consumption for modes presented in FIG. 20 according to an example. During the idlel mode 2021 , the power consumption may be mostly effected by the configured DRX cycle. The DRX cycle can be long since typically there is no low latency requirement in the EH-AP setup. During the idle2 mode 814, the EH- AP device 100 may be waking up and following the backhaul DRX/BWP cycle. In FIG. 21 , DRX is assumed indicating the low power consumption during the inactive time. With BWP procedure the power consumption may be non-zero even with narrow bandwidths. In FIG. 21 , it is assumed that the backhaul power consumption is constant during the connected mode.

The functionality described herein can be performed, at least in part, by one or more computer program product components such as software components. According to an example, the EH-AP device 100 and/or the M-PA device 200 comprise the processor 101 , 201 configured by the program code when executed to execute the examples of the operations and functionality described. Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Program-specific Integrated Circuits (ASICs), Program-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs). Any range or device value given herein may be extended or altered without losing the effect sought. Also any example may be combined with another example unless explicitly disallowed.

Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

It will be understood that the benefits and advantages described above may relate to one example or may relate to several examples. The examples are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items. The term‘and/or’ may be used to indicate that one or more of the cases it connects may occur. Both, or more, connected cases may occur, or only either one of the connected cases may occur.

The operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

The term 'comprising' is used herein to mean including the method, blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.

It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary examples. Although various examples have been described above with a certain degree of particularity, or with reference to one or more individual examples, those skilled in the art could make numerous alterations to the disclosed examples without departing from the spirit or scope of this specification.

Claims

1. An energy harvesting access point, EH-AP, device (100) configured to: measure energy harvesting, EH, information based on harvested energy;

wherein the EH-AP device further comprises:

an access transceiver, ACC-TRX, (104) configured to:

provide wireless connectivity for at least one client device (300); a backhaul transceiver, BH-TRX, (103) configured to:

transmit the EH information (803) to a master access point, M-AP, device (200);

receive a control message (805, 810, 1 101 , 1 106, 1201 ) from the M- AP device, wherein the control message is based on the transmitted EH information; and

a processor (101 ), configured to:

determine control parameters based on information comprised in the received control message;

control operation of the BH-TRX and the ACC-TRX using the control parameters.

2. The EH-AP device according to claim 1 , wherein the EH-AP device further comprises:

an energy subsystem, ESS, (102) configured to:

harvest energy from an energy source; and

store the harvested energy in an energy storage.

3. The EH-AP device according to any preceding claim, wherein the processor is further configure to:

manage the power consumption of the EH-AP device according to an energy utilization threshold, wherein the information in the control message comprises the energy utilization threshold.

4. The EH-AP device according to any preceding claim, wherein the BH- TRX and the ACC-TRX are further configured for a discontinuous reception, DRX; and

wherein the processor is further configured to:

utilize a settings for the discontinuous reception, DRX, wherein the control parameters in the control message comprises the settings for the discontinuous reception DRX.

5. The EH-AP device according to any preceding claim, wherein the ACC- TRX is further configured to:

receive an at least one uplink, UL, pilot signal (903) from the at least one client device;

wherein the processor is further configured to:

determine an UL measurement report (1203) based on the received at least one UL pilot signal;

wherein the BH-TRX is further configured to:

transmit the, UL measurement report to the M-AP, as configured by the control parameters.

6. The EH-AP device according to any preceding claim, wherein the processor is further configured to:

evaluate downlink, DL, pilot signals (903) according to the control parameters;

wherein the ACC-TRX is further configured to:

transmit the DL pilot signals.

7. A master access point, M-AP, device (200), comprising:

a master backhaul transceiver, BH-TRX, (202) configured to:

receive an energy harvesting, EH, information (803) from an energy harvesting access point, EH-AP, device (100), wherein the EH information comprises an information about harvested energy in the EH-AP device; and

a processor (201 ) configured to:

determine a control message (805, 810, 1 101 , 1 106, 1201 ) based on the EH information, wherein the control message comprises information that the EH-AP device is configured to use in order to control a BH-TRX of the EH-AP device and an ACC-TRX of the EH-AP device;

wherein the master BH-TRX is further configured to transmit the control message to the EH-AP device.

8. The M-AP device according to claim 7, wherein the processor is further configured to:

calculate an energy utilization threshold based on the EH information, wherein the energy utilization threshold is associated at least with one of stored energy, energy harvesting rate, and energy consumption rate of the EH-AP device.

9. The M-AP device according to claim 8, wherein the master BH-TRX is further configured to:

transmit the energy utilization threshold to the EH-AP in the control message.

10. The M-AP according to claim 9, wherein the processor is further configured to:

determine at least one control parameter based on the energy utilization threshold;

wherein the master BH-TRX is further configured to:

transmit the at least one control parameter to the EH-AP device in the control message.

1 1 . The M-AP device according to any of claims 7 - 10, wherein the M-AP further comprises an ACC-TRX, and the ACC-TRX is configured to:

transmit an uplink UL, client control message (1202) to the at least one client device, wherein the UL client control message comprises control information about UL pilot signals to be transmitted by the at least one client device to the EH-AP device; and

wherein the master BH-TRX is further configured to: receive an UL measurement report (1203) from the EH-AP device, wherein the UL measurement report comprises measurement results for the UL pilot signals transmitted by the at least one client device; and

wherein the processor is further configured to:

estimate traffic volume of the EH-AP device based on the received UL measurement report;

determine the control message based on the estimated traffic volume.

12. The M-AP device according to any of claim 7 - 1 1 , wherein the master BH-TRX is further configured to:

receive a downlink, DL, client control message (1 102) from a second

M-AP device;

wherein the ACC-TRX is further configured to:

relay the DL client control message to the at least one client device; and

receive a DL measurement report (1 103) from the at least one client device; and

wherein the master BH-TRX is further configured to:

relay the DL measurement report to the second M-AP device.

13. A method, comprising:

measuring energy harvesting, EH, information based on harvested energy;

providing wireless connectivity for at least one client device;

transmitting the EH information to a master access point, M-AP, device;

receiving a control message from the M-AP device, wherein the control message is based on the transmitted EH information; and

determining control parameters based on information comprised in the received control message;

controlling operation of the BH-TRX and the ACC-TRX using the control parameters.

14. A method, comprising:

receiving an energy harvesting, EH, information from an energy harvesting access point, EH-AP, device, wherein the energy harvesting information comprises information about harvested energy in the EH-AP device;

determining a control message based on the EH information, wherein the control message comprises information that the EH-AP is configured to use in order to control a backhaul transceiver, BH-TRX, of the EH-AP device and an access transceiver, ACC-TRX, of the EH-AP device;

transmitting the control message to the EH-AP device.

15. A computer program comprising program code configured to perform a method according to claim 13 or 14 when the computer program is executed on a computer.