Patent Description:
Exposure guidelines for communication systems are known. Such exposure guidelines may be expressed relative to specific absorption rate (SAR) or maximum permissible exposure (MPE). Although developments have been made, there remains scope for further developments in this field.

<CIT> describes methods, apparatus and systems for a wireless transmit/receive unit (WTRU) to manage its transmission power. A power headroom report (PHR) may be triggered based on changes to backoff or the impacts of backoff. Additional backoff may be used to calculate a maximum output power of the WTRU and may be indicated by a domination indicator to network resources. Prior-art document "<NPL>, discusses mechanisms helping the network cope with UE Maximum Permissible Exposure (MPE) limitations.

In a first aspect, this specification describes an apparatus (e.g. an user device, or an apparatus implemented at a user device) comprising: means for detecting an occurrence of a maximum permissible exposure event (e.g. when a user device is at a distance less than a minimum safety distance from a user); means for determining a severity of the detected maximum permissible exposure event; means for setting a periodic scheduling override condition to be valid in the event that the detected maximum permissible exposure event is determined to have a high severity; means for reporting (e.g. to a network element) maximum permissible exposure assistance information in response to the detection of the occurrence of the maximum permissible exposure event, wherein the means for reporting the maximum permissible exposure assistance information is configured to: generate a scheduled report in the event that the periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and generate an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire. A first timer may be provided for monitoring said first time period (e.g. the first time period may be the period of the first timer).

The detected maximum permissible exposure event may be determined to have a high severity in the event that a duty cycle reduction required to address said exposure event is above a threshold or in the event that power backoff requirements are above a threshold.

Some example embodiments further comprise means for monitoring an ongoing maximum permissible exposure event (e.g. using a second timer). Some example embodiments further comprise means for reporting that the maximum permissible exposure event has ended in the event that the maximum permissible exposure event ends before a second time period expires. The second time period may be the same, or may be different, to the first time period referred to above.

Some example embodiments further comprise a first timer for monitoring said first time period. Thus, for example, the first time period may be the period of the first timer. Some example embodiments further comprise a second timer for monitoring the second time period referred to above. The second time period may be same as the first time period, but this is not essential to all example embodiments. For example, the second time period may be shorter than the first. The first and second timers may be implemented using the same timer apparatus, or using separate timer apparatus. Some example embodiments further comprise means for indicating (e.g. by communication with the relevant network, base station, node B etc.) that the apparatus (e.g. the relevant user device) is capable of providing maximum permissible exposure assistance information.

Some example embodiments further comprise means for triggering a power backoff in response to the maximum permissible exposure event. Alternatively, or in addition, some example embodiments further comprise means for triggering a duty cycle adjustment (or a duty cycle limit) in response to the maximum permissible exposure event. The power backoff and/or the duty cycle limit may be triggered in order to meet MPE regulation requirements.

Some example embodiments further comprise means for reconfiguring user device protocols to enable maximum permissible exposure assistance information to be communicated between a user device and a network element.

The said maximum permissible exposure assistance information may be provided as part of a modified L3-based UE assistance signalling procedure. For example, said signalling procedure may include: establishing a connection; exchanging capabilities; and device reconfiguration.

In a second aspect, this specification describes an apparatus (e.g. a network node, such as a base station and gNB or a device or system in communication with such as node) comprising: means for detecting (e.g. at a network element or similar device or system) a maximum permissible exposure event report (e.g. received from a user device or from a device or system in communication with one or more user devices); means for determining whether the detected maximum permissible exposure report is a scheduled report or an unscheduled report (e.g. based on whether the report is received with an expected periodicity); means for determining whether one or more time periods (e.g. as implemented by one or more timers) of the maximum permissible exposure event protocol should be updated in the event the detected maximum permissible exposure event report is determined to be an unscheduled report, in order to reduce the instances of unscheduled reports; and means for adjusting uplink resources (e.g. triggering duty cycle adjustments and/or power back-off in response to the MPE event) to meet maximum permissible exposure power backoff requirements.

Some example embodiments further comprise means for storing maximum permissible exposure event statistics on receipt of a maximum permissible exposure event report.

Some example embodiments further comprise means for receiving an indication that a remote user device is capable of providing maximum permissible exposure related assistance information.

Some example embodiments further comprise means for defining a first timer start time for a user device, wherein said scheduled report is sent by said user device to said apparatus in the event of the expiry of said first timer. The means for defining a first timer start time may define first timer start times for each of a plurality of user devices (e.g. different user devices of the plurality may have different first timer start times).

In a third aspect, this specification describes a method comprising: detecting an occurrence of a maximum permissible exposure event; determining a severity of the detected maximum permissible exposure event and setting a periodic scheduling override condition to be valid in the event that the detected maximum permissible exposure event is determined to have a high severity; and reporting maximum permissible exposure assistance information in response to the detection of the occurrence of the maximum permissible exposure event, wherein reporting the maximum permissible exposure assistance information comprises: generating a scheduled report in the event that the periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and generating an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire.

The method may further comprise monitoring an ongoing maximum permissible exposure event and reporting that the maximum permissible exposure event has ended in the event that the maximum permissible exposure event ends before a second time period expires.

In a fourth aspect, this specification describes a method comprising: detecting a maximum permissible exposure event report; determining whether the detected maximum permissible exposure report is a scheduled report or an unscheduled report; determining whether one or more time periods of the maximum permissible exposure event protocol should be updated in the event that the detected maximum permissible exposure event report is determined to be an unscheduled report, in order to reduce the instances of unscheduled reports; and adjusting uplink resources to meet maximum permissible exposure power backoff requirements.

The method may further comprise storing maximum permissible exposure event statistics on receipt of a maximum permissible exposure event report.

The method may further comprise defining a first timer start time for a user device, wherein said scheduled report is sent by said user device in the event of the expiry of said first timer. Example embodiments may further comprise defining first timer start times for each of a plurality of user devices.

In a fifth aspect, not claimed, this specification describes an apparatus configured to perform any method as described with reference to the third or fourth aspects.

In a sixth aspect, not claimed, this specification describes computer-readable instructions which, when executed by computing apparatus, cause the computing apparatus to perform any method as described with reference to the third or fourth aspects.

In a seventh aspect, not claimed, this specification describes a computer readable medium comprising program instructions stored thereon for performing at least the following: detecting an occurrence of a maximum permissible exposure event; and reporting maximum permissible exposure assistance information in response to the detection of the occurrence of the maximum permissible exposure event, wherein reporting the maximum permissible exposure assistance information comprises: generating a scheduled report in the event that a periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and generating an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire.

In an eighth aspect, not claimed, this specification describes a computer readable medium comprising program instructions stored thereon for performing at least the following: detecting a maximum permissible exposure event report; determining whether the detected maximum permissible exposure report is a scheduled report or an unscheduled report; determining whether one or more time periods of the maximum permissible exposure event protocol should be updated in the event that the detected maximum permissible exposure event report is determined to be an unscheduled report, in order to reduce the instances of unscheduled reports; and adjusting uplink resources to meet maximum permissible exposure power backoff requirements.

In a ninth aspect, this specification describes a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out at least the following: detecting an occurrence of a maximum permissible exposure event; and determining a severity of the detected maximum permissible exposure event; setting a periodic scheduling override condition to be valid in the event that the detected maximum permissible exposure event is determined to have a high severity; and reporting maximum permissible exposure assistance information in response to the detection of the occurrence of the maximum permissible exposure event, wherein reporting the maximum permissible exposure assistance information comprises: generating a scheduled report in the event that a periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and generating an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire.

In a tenth aspect, this specification describes a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out at least the following: detecting a maximum permissible exposure event report; determining whether the detected maximum permissible exposure report is a scheduled report or an unscheduled report; determining whether one or more time periods of the maximum permissible exposure event protocol should be updated in the event that the detected maximum permissible exposure event report is determined to be an unscheduled report, in order to reduce the instances of unscheduled reports; and adjusting uplink resources to meet maximum permissible exposure power backoff requirements.

In an eleventh aspect, not claimed, this specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code which, when executed by the at least one processor, causes the apparatus to: detect an occurrence of a maximum permissible exposure event; and report maximum permissible exposure assistance information in response to the detection of the occurrence of the maximum permissible exposure event, wherein reporting the maximum permissible exposure assistance information comprises: generating a scheduled report in the event that a periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and generating an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire.

In a twelfth aspect, not claimed, this specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code which, when executed by the at least one processor, causes the apparatus to: detect a maximum permissible exposure event report; determine whether the detected maximum permissible exposure report is a scheduled report or an unscheduled report; determine whether one or more time periods of the maximum permissible exposure event protocol should be updated in the event that the detected maximum permissible exposure event report is determined to be an unscheduled report, in order to reduce the instances of unscheduled reports; and adjust uplink resources to meet maximum permissible exposure power backoff requirements.

In a thirteenth aspect, not claimed, this specification describes an apparatus comprising: a maximum permissible exposure event monitor for detecting an occurrence of a maximum permissible exposure event; and an output for reporting maximum permissible exposure assistance information (e.g. to a network node) in response to the detection of the occurrence of the maximum permissible exposure event, wherein reporting the maximum permissible exposure assistance information comprises: generating a scheduled report in the event that a periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and generating an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire.

In a fourteenth aspect, not claimed, this specification describes an apparatus comprising: a control module for detecting a maximum permissible exposure event report and determining whether the detected maximum permissible exposure report is a scheduled report or an unscheduled report; a timer module for determining whether one or more time periods of the maximum permissible exposure event protocol should be updated in the event that the detected maximum permissible exposure event report is determined to be an unscheduled report, in order to reduce the instances of unscheduled reports; and resources module for adjusting uplink resources to meet maximum permissible exposure power backoff requirements.

Example embodiments will now be described, by way of non-limiting examples, with reference to the following schematic drawings, in which:.

The scope of protection sought for various example embodiments of the invention is set out by the independent claims. The example embodiments and features, if any, described in the specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

The millimeter-wave (mmW) spectrum offers the possibility of using large portions of contiguous bandwidth to enable mobile communication systems to provide highthroughput applications. The 5th Generation (<NUM>) New Radio (NR) frequency spectrum extends well-above the previous 4th Generation (<NUM>) spectrum, which was ranging from <NUM> to <NUM> - otherwise known as Frequency Range <NUM> (FR1). In mmWave <NUM> NR, Frequency Range <NUM> (FR2) comprises the frequencies between <NUM> and <NUM>; and extending the NR operation into the <NUM>-<NUM> range is currently being discussed.

Operating at such high frequencies with high gain antennas has raised concerns for the health of users. There is a standard on millimeter-wave regime that specifies and regulates the maximum power for the user equipment (UE). Since frequencies below <NUM> are non-ionizing, the concern for health is limited to thermal heating of the body tissue while absorbing electromagnetic mmW energy. Millimeter-wave frequencies yield penetration depths below <NUM>, therefore possible thermal damage is limited to the surface of the skin and the eyes; indeed, most of the energy is absorbed within the first <NUM> of the human skin at <NUM>.

Governmental exposure guidelines are in place to prevent health issues due to thermal effects. Below <NUM>, Specific Absorption Rate (SAR) has been used to determine the exposure threshold. SAR measures the energy absorbed by the human body when exposed to electromagnetic fields. The SAR limitation in the U. is <NUM> W/kg averaged over <NUM>-g tissue from FCC, while in Europe it is 2W/kg averaged over <NUM>-g tissue. The <NUM>-g averaging provides a finer resolution for the study of energy absorption in the human body.

Nonetheless, for millimetre-wave regimes where the penetration depth is below <NUM>, even <NUM>-g tissue is in fact a rather large volume. Being difficult to define a meaningful volume for SAR evaluation, it has been commonly accepted to use Power Density (PD) and not SAR to set the restrictions on exposure at millimeter-wave frequencies. It is thus a planar energy distribution as opposed to a volumetric one. Maximum Permissible Exposure (MPE) is a regulation based on PD for the millimeter-wave regime. The FCC and ICNIRP set the threshold for MPE at 10W/m<NUM> (<NUM> mW/cm<NUM>), for the general public, between <NUM> or <NUM> respectively and <NUM>. The energy absorbed by the human body increases as a function of the distance to the UE. Therefore, to comply with the MPE limit, the UE may reduce its output power if the user gets in close vicinity of the antenna.

<FIG> is a block diagram of a system, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. In the system <NUM>, a first user <NUM> is using a first mobile communication device (UE) <NUM> to communicate with a network node (gNB) <NUM> and a second user <NUM> is using a second mobile communication device (UE) <NUM> to communicate with the network node <NUM>.

As shown in <FIG>, communications between the first device <NUM> and the network node <NUM> occur via an unobstructed Line of Sight (LOS) path, whereas the second user <NUM> stands at least partially in the path of a beam from the second device <NUM> to the network node <NUM>.

Thus, the second user is exposed to a radiated beam between the second device <NUM> and the network node <NUM>. As the user comes in close vicinity of the second device <NUM>, the amount of energy absorbed by the user's body may be relatively large; as such the output power of the second device <NUM> may need to be reduced to comply with MPE requirements.

<FIG> is a graph, indicated generally by the reference numeral <NUM>, showing maximum allowed equivalent isotropically radiated power (EIRP) depending on the distance between a user device (e.g. an antenna of the user device) and a user. As is clearly shown in the example graph <NUM>, the maximum allowed EIRP reduces as the distance between the user device and the user is reduced.

<FIG> is a block diagram of a system <NUM> in accordance with an example embodiment. The system <NUM> comprises a user <NUM> (similar to the users <NUM> and <NUM> described above) and a user device <NUM> (similar to the user devices <NUM> and <NUM> described above). In the system <NUM>, the user <NUM> and the user device <NUM> are separated by a distance duser-UE that is greater than a minimum safety distance dmin.

<FIG> is a block diagram of a system <NUM>, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. The system <NUM> comprises the user <NUM> and the user device <NUM> described above with reference to <FIG>. However, in the system <NUM>, the user <NUM> and the user device <NUM> are separated by a distance duser-UE that is less than a minimum safety distance dmin.

When the distance between the user <NUM> and the user device <NUM> goes below the minimum safety distance dmin, then the user device is required to perform a power back-off in order to meet the MPE regulation requirements. This back-off is referred to herein as an MPE event.

<FIG> is a plot, indicated generally by the reference numeral <NUM>, showing an example power back-off feature. The plot shows a user device transmit power (on the y-axis) plotted against time. As shown in the plot <NUM>, the user device transmit power is reduced between times t<NUM> and t<NUM> (due to an MPE event). The user device transmit power may be reduced, for example, by reducing a duty cycle of uplink transmissions.

In the event that the user device <NUM> is communicating with a network element (such as the network node <NUM> described above) when a power back-off occurs, it is possible that the network node may be unable to receive enough power from the uplink transmission from the user device in order to decode successfully the transmitted payload from the user device. This may be the case, for example, since the link adaptation (e.g. the selection of MCS, TBS and UL transmission power) may have been performed when the user device was at a position above the dmin MPE triggering distance. Depending on the duration of the MPE event, a radio link failure (RLF) might also be triggered, resulting in disruption to a user experience and requiring the user device to reconnect to the relevant network (e.g. transition again to an RRC connected state).

<FIG> is a message sequence, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. The message sequence shows messages between a user device <NUM> (such as the user device <NUM>, <NUM> or <NUM> described above) and a network element <NUM> (such as the network node <NUM> described above) that enables the user device <NUM> to inform the network element <NUM> of the occurrence of an MPE event. The message sequence <NUM> comprises establish connection messages <NUM>, capability exchange messages <NUM>, device re-configuration messages <NUM> and MPE assistance information <NUM>. As discussed further below, the MPE assistance information <NUM> may be used to report the occurrence of an MPE event.

The message sequence <NUM> may be implemented using Radio Resource Control (RRC) protocols, as discussed further below.

The message sequence <NUM> starts with establish connection messages <NUM> in which the user device <NUM> establishes a connection with the network element <NUM>. For example, the user device <NUM> may transition from a radio resource control (RRC) idle or inactive state to an RRC connected state.

The establish connection messages <NUM> are followed by capability exchange messages <NUM> in which the user device <NUM> informs the network element <NUM> of its capabilities, typically in response to requests for such information from the network element. In the context of the example embodiments described herein, the user device <NUM> informs the network element <NUM> that it is capable of providing MPE related UE assistance as part of the capability exchange messages <NUM>.

Using the device re-configuration messages <NUM> (RRC reconfiguration), the network element <NUM> configures the users device <NUM> to be able to to report the MPE related UE assistance. This configuration may include details such as how often the user device <NUM> is allowed to perform this reporting (e.g. the range of allowable periodicity). For example, a long periodicity may be preferred in order to minimize signaling overhead. Alternatively, a small periodicity may be preferred to enable the network to react quickly (e.g. to adjust power back-off at the user device quickly). The re-configuration messages may be in accordance with existing RRC reconfiguration protocols.

Finally, upon detecting the occurrence of an MPE event, the user device <NUM> transmits to the network its MPE Assistance Information as part of the MPE assistance information message <NUM>. As discussed in detail below, the transmission of the MPE event report timing may depends on the severity of the MPE conditions.

<FIG> is a flow chart showing an algorithm, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment.

The algorithm <NUM> starts at operation <NUM>, where the occurrence of a maximum permissible exposure (MPE) event is detected. At operation <NUM>, a severity of a detected MPE event is determined or otherwise detected.

At operation <NUM>, a determination is made regarding whether an override condition (e.g. a periodic scheduling override condition) is met. An override condition may, for example, relate to a severity of the detected MPE event. The severity may be linked to the extent to which a transmit (uplink) duty-cycle needs to be reduced in order to overcome the MPE event. Alternatively, or in addition, the severity may be linked to the extent to which power back-off is required in order overcome the MPE event.

If operation <NUM> determines that the override condition is not met (e.g. if the severity of the MPE event is below a threshold level), then the algorithm <NUM> moves to a wait state <NUM>. After the expiry of the wait state, then an MPE report (referred to below as a scheduled MPE report) is generated at operation <NUM>.

If operation <NUM> determines that the override condition is met, then the algorithm <NUM> moves to operation <NUM>, such that an MPE report is generated without waiting for the expiry of the wait state described above (referred to below as an unscheduled MPE report).

Thus, the algorithm <NUM> enables reporting of maximum permissible exposure assistance information (e.g. to a network element, such as the network element <NUM>) in response to the detection of the occurrence of the maximum permissible exposure event. Moreover, the reporting of the maximum permissible exposure assistance information includes: generating a scheduled report in the event that the override condition is not met (e.g. is invalid) and generating an unscheduled report in the event that the override condition is met (i.e. is valid).

As discussed further below, a scheduled report may be sent when a first time period expires, whereas an unscheduled report may be sent without waiting for the first time period to expire.

<FIG> is a message sequence, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. The message sequence <NUM> shows messages between the user device <NUM> and the network element <NUM> described above that enables the user device <NUM> to inform the network element <NUM> of the occurrence of an MPE event. The messages sequence <NUM> shows details of an example implementation of the MPE assistance information message <NUM> described above.

The message sequence <NUM> shows the detection of an MPE event <NUM> at the user device <NUM> and the detection of the end of an MPE event <NUM> at the user device. The message sequence <NUM> shows how this information is communicated to the network element <NUM> in the event that the override condition of operation <NUM> of the algorithm <NUM> is not met (e.g. the MPE event is not considered to be severe).

As discussed further below, in circumstances when an MPE event is not considered to be severe, then MPE assistance information is sent at the expiry of a time period (e.g. a timer). Thus, MPE assistance information messages may be sent periodically.

The message sequence <NUM> includes a first potential MPE assistance information message 83a and a second potential MPE assistance information message 83b, both of which occur before the start of the MPE event <NUM>. Since no MPE event is detected at these times, no MPE information is required to be sent in the potential messages 83a and 83b. Those potential message slots may simply be omitted; alternatively, a blank message may be sent, indicating that no MPE event has been detected.

Following the detection of the MPE event <NUM>, an MPE assistance information message <NUM> is sent from the user device <NUM> to the network element <NUM>. Since the MPE event <NUM> is deemed to not be severe, the MPE assistance information message <NUM> is sent at the next available one of the periodic potential MPE assistance information messages.

In response to the receipt of the MPE assistance information <NUM>, MPE handling procedures <NUM> are enacted. The MPE handling procedures <NUM> may include means for triggering a power backoff in response to the maximum permissible exposure event in order to meet MPE regulation requirements. As discussed further below, the power backoff procedures may include changes to the uplink resources provided for the user device <NUM> to communicate with the network element <NUM> in order to meet the MPE requirements.

Once the end of the MPE event <NUM> is detected, an MPE assistance information message <NUM> is sent from the user device to the network element <NUM>, for example at the next periodic message slot indicating the end of the MPE event.

The message sequence <NUM> includes further potential MPE assistance information messages 87a and 87b, both of which occur after then end of the MPE event. Following the message <NUM>, no further MPE event is detected and so no MPE information is required to be sent in the potential messages 87a and 87b. As noted above, those potential message slots may simply be omitted; alternatively, a blank message may be sent, indicating that no MPE event has been detected.

<FIG> is a message sequence, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. The message sequence <NUM> shows messages between the user device <NUM> and the network element <NUM> described above that enables the user device <NUM> to inform the network element <NUM> of the occurrence of an MPE event. Thus, in common with the message sequence <NUM>, the messages sequence <NUM> shows details of an example implementation of the MPE assistance information message <NUM> described above.

The message sequence <NUM> shows the detection of an MPE event <NUM> at the user device <NUM> and the detection of the end of an MPE event <NUM> at the user device. The message sequence <NUM> shows how this information is communicated to the network element <NUM> in the event that the override condition of operation <NUM> of the algorithm <NUM> is met (e.g. the MPE event is considered to be severe).

As discussed further below, in circumstances when an MPE event is considered to be severe, then MPE assistance information is sent without waiting for the expiry of a time period (e.g. a timer).

The message sequence <NUM> includes a first potential MPE assistance information message 93a and a second potential MPE assistance information message 93b, both of which occur before the start of the MPE event <NUM>. Since no MPE event is detected at these times, no MPE information is required to be sent in the potential messages 93a and 93b. Those potential message slots may simply be omitted; alternatively, a blank message may be sent, indicating that no MPE event has been detected.

Following the detection of the MPE event <NUM>, an MPE assistance information message <NUM> is sent from the user device <NUM> to the network element <NUM>. Since the MPE event <NUM> is deemed to be severe, the MPE assistance information message <NUM> is sent without wait for the next available one of the periodic potential MPE assistance information messages.

In response to the receipt of the MPE assistance information <NUM>, MPE handling procedures <NUM> are enacted. The MPE handling procedures are similar to the MPE handling procedures <NUM> discussed above; for example, the MPE handling procedures <NUM> may include changes to the uplink resources provided for the user device <NUM> to communicate with the network element <NUM> in order to meet the MPE requirements.

The message sequence <NUM> includes further potential MPE assistance information messages 97a and 97b, both of which occur after then end of the MPE event. Following the message <NUM>, no further MPE event is detected and so no MPE information is required to be sent in the potential messages 97a and 97b. As noted above, those potential message slots may simply be omitted; alternatively, a blank message may be sent, indicating that no MPE event has been detected.

<FIG> is a flow chart showing an algorithm, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. The algorithm <NUM> is initiated at operation <NUM>. The algorithm <NUM> may be implemented at the user device <NUM> (or some similar user device). In some example embodiments, multiple instances of the algorithm <NUM> may be implemented at each of a plurality of user devices.

At operation <NUM>, a first timer T1 is initiated (e.g. at the user device <NUM> described above). The first timer T1 is associated with the periodic reporting of MPE events.

At operation <NUM>, the user device <NUM> starts monitoring for the start of an MPE event. This may be an internal user device process and may be implemented in many different ways. For example, proximity sensors may be provided to determine the presence of a user close to the user device or radar-based or similar detection methods may be provided.

At operation <NUM>, the user device <NUM> determines whether an MPE event (such as the start of the MPE events <NUM> or <NUM> described above) has been detected. If an MPE event is detected, the algorithm <NUM> moves to operation <NUM>. If an MPE event is not detected, the algorithm <NUM> returns to operation <NUM>.

At operation <NUM>, the user device <NUM> determines whether a periodic scheduling overriding condition is valid. As discussed elsewhere herein, a periodic scheduling override condition may be valid in the event that the MPE event is deemed to be severe. If the periodic scheduling override condition is not valid, then the algorithm <NUM> moves to operation <NUM>. If the periodic scheduling override condition is valid, then the algorithm <NUM> moves to operation <NUM>.

Example implementations of the operation <NUM> include considering a duty cycle threshold or a power back-off threshold. For example, the overriding condition may be met if a duty cycle reduction required due to the MPE event is below a duty cycle threshold level (e.g. <NUM>%) due to the MPE event. Alternatively, or in addition, the overriding condition may be met if a power back-off required due to the MPE event is above a threshold level (e.g. a given dB level).

Alternatively, or in addition, the operation <NUM> may consider a flag that may be set to override periodic reporting. For example, user device <NUM> or a control module may be allowed to set a flag to override the periodic reporting (e.g. when the required duty cycle reduction is not achievable if the UE waits until the timer T1 elapses).

Thus, the operation <NUM> may include determining a severity of the detected maximum permissible exposure event. The operation <NUM> may include setting the periodic scheduling override condition to be valid in the event that the detected maximum permissible exposure event is determined to have a high severity.

At operation <NUM>, the user device <NUM> waits for the timer T1 to lapse and then transmits the MPE event report. Thus, the operation <NUM> results in a periodic MPE report being transmitted (as discussed above with reference to the message sequence <NUM>). The algorithm <NUM> then moves to operation <NUM>.

At operation <NUM>, the user device <NUM> triggers the transmission of the MPE event reporting, without waiting for the timer T1 to lapse (as discussed above with reference to the message sequence <NUM>). The algorithm <NUM> then moves to operation <NUM>.

At operation <NUM>, a second timer T2 is set. The first timer T1 and the second timer T2 may have the same duration or different durations; for example, the second timer duration may be shorter than the first. The timers may be two instances of the same timer or may be separate timers.

At operation <NUM>, the user device <NUM> monitors the ongoing MPE event. Then, at operation <NUM>, a determination is made regarding whether or not the MPE event has concluded. For example, a determination may be made regarding whether the distance between the user device <NUM> and a user is above the dmin distance discussed above. The operation <NUM> may determine that the MPE event has ended in the event that the maximum permissible exposure event ends before a period of the second timer expires.

If it is determined in operation <NUM> that the MPE event has concluded, the algorithm <NUM> moves to operation <NUM>; otherwise, the algorithm <NUM> moves to operation <NUM>.

At operation <NUM>, the end of the MPE event is reported (e.g. by the user device <NUM> to the network element <NUM>). The operation <NUM> may be implemented, for example, by the message <NUM> of the message sequence <NUM> or the message <NUM> of the message sequence <NUM> described above. Once the end of the MPE has been reported, the algorithm <NUM> returns to operation <NUM>.

At operation <NUM> (where it is determined that the MPE event is going), the user device <NUM> determines whether a periodic scheduling overriding condition is valid. As discussed with reference to operation <NUM>, a periodic scheduling override condition may be valid in the event that the MPE event is deemed to be severe. If the periodic scheduling override condition is not valid, then the algorithm <NUM> moves to operation <NUM>. If the periodic scheduling overriding condition is valid, then the algorithm <NUM> moves to operation <NUM>.

Example implementations of the operation <NUM> include considering a duty cycle threshold, a power back-off threshold or a flag. The overriding condition in operation <NUM> may be the same as the condition in operation <NUM>, but this is not essential. For example, the overriding condition in operation <NUM> may be stricter than the condition in operation <NUM> or stricter than the actual condition of the user device at that time, thereby determining whether or not the MPE event is getting worse (e.g. is the user device <NUM> moving closer to the user).

At operation <NUM>, the user device <NUM> waits for the second timer T2 to lapse and then transmits the MPE event report. Thus, the operation <NUM> results in a periodic MPE report being transmitted. The algorithm <NUM> then returns to operation <NUM>.

At operation <NUM>, the user device <NUM> triggers the transmission of the MPE event reporting, without waiting for the second timer T2 to lapse. The algorithm <NUM> then returns to operation <NUM>.

<FIG> is a flow chart showing an algorithm, indicated generally by the reference numeral <NUM>, in accordance with an example embodiment. The algorithm <NUM> is initiated at operation <NUM>. The algorithm <NUM> may be implemented at the network element <NUM> (or some similar node).

At operation <NUM>, the network element <NUM> monitors for the reception of a UE assistance report from a user device (such as the user device <NUM>). At operation <NUM>, on detection of a UE assistance report, a determination is made (e.g. at the network element <NUM>) regarding whether the received UE Assistance report is an MPE event report (e.g. a message such as the messages <NUM> or <NUM> described above).

If a received MPE event report is detected at operation <NUM>, then the algorithm <NUM> moves to operation <NUM>; otherwise, the operation <NUM> returns to operation <NUM>.

At operation <NUM>, the network element <NUM> determines whether the received report follows the current expected periodicity (i.e. T1 for the case of MPE event detection or T2 for the case of an ongoing MPE event). If not, the received MPE report is identified as an unscheduled report and the algorithm <NUM> moves to operation <NUM>. Otherwise, the received MPE report is identified as a scheduled report and the algorithm <NUM> moves to operation <NUM>.

At operation <NUM>, information is extracted (e.g. at the network element <NUM>) about the user device triggering the unscheduled report and this information is used to create statistics. Such MPE event statistics may be generated and stored on receipt of an MPE event report. Moreover, one or more time periods (e.g. timers) of the MPE event protocol may be updated, in order to reduce the instances of unscheduled reports. By way of example, the timers (or time periods) may be updated using machine learning algorithms.

By way of example, the values associated with the first and/or the second timers described above may be adjusted. It should be noted that, in certain cells (or even for individual users), the occurrence of MPE events will be different. For example, a specific user might regularly hold the user deice close to their head in a talk mode, while another one might consistently use a headset with the user device placed on a surface away from the user. In the latter case it is expected that fewer MPE events will occur and as such the T1 and T2 timers can be more relaxed.

At operation <NUM>, information is extracted (e.g. at the network element <NUM>) about the user device triggering the scheduled report and this information is used to create statistics. Such MPE event statistics may be generated and stored on receipt of an MPE event report.

At operation <NUM>, the uplink resources of the user device <NUM> are adjusted, for example to meet the MPE power back-off requirements. In one example embodiment, an uplink duty cycle may be modified in the operation <NUM>.

The uplink resources may also be modified by defining a first timer start time for a particular user device, wherein said scheduled report is sent by said user device to said apparatus in the event of the expiry of said first timer. Moreover, the first timer start time may be set to be different for different user devices, such that the first timers (and hence the scheduled reports) are staggered.

For completeness, <FIG> is an example schematic diagram of components of one or more of the modules for implementing the algorithms described above, which hereafter are referred to generically as processing systems <NUM>. A processing system <NUM> may have a processor <NUM>, a memory <NUM> coupled to the processor and comprised of a RAM <NUM> and ROM <NUM>, and, optionally, user inputs <NUM> and a display <NUM>. The processing system <NUM> may comprise one or more network interfaces <NUM> for connection to a network, e.g. a modem which may be wired or wireless.

The memory <NUM> may comprise a non-volatile memory, a hard disk drive (HDD) or a solid state drive (SSD). The ROM <NUM> of the memory <NUM> stores, amongst other things, an operating system <NUM> and may store software applications <NUM>. The RAM <NUM> of the memory <NUM> is used by the processor <NUM> for the temporary storage of data. The operating system <NUM> may contain code which, when executed by the processor, implements aspects of the algorithms and message sequences <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>.

The processor <NUM> may take any suitable form. For instance, it may be a microcontroller, plural microcontrollers, a processor, or plural processors. Processor <NUM> may comprise processor circuitry.

The processing system <NUM> may be a standalone computer, a server, a console, or a network thereof.

In some example embodiments, the processing system <NUM> may also be associated with external software applications. These may be applications stored on a remote server device and may run partly or exclusively on the remote server device. These applications may be termed cloud-hosted applications. The processing system <NUM> may be in communication with the remote server device in order to utilize the software application stored there.

<FIG> show tangible media, respectively a removable memory unit <NUM> and a compact disc (CD) <NUM>, storing computer-readable code which when run by a computer may perform methods according to example embodiments described above. The removable memory unit <NUM> may be a memory stick, e.g. a USB memory stick, having internal memory <NUM> storing the computer-readable code. The memory <NUM> may be accessed by a computer system via a connector <NUM>. The CD <NUM> may be a CD-ROM or a DVD or similar. Other forms of tangible storage media may be used.

Some example embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic.

Reference to, where relevant, "computer-readable storage medium", "computer program product", "tangibly embodied computer program" etc., or a "processor" or "processing circuitry" etc. should be understood to encompass not only computers having differing architectures such as single/multi-processor architectures and sequencers/parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device as instructions for a processor or configured or configuration settings for a fixed function device, gate array, programmable logic device, etc..

As used in this application, the term "circuitry" refers to all of the following: (a) hardware-only circuit implementations (such as implementations in only analogue and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

Similarly, it will also be appreciated that the flow diagrams and message sequences of <FIG> are examples only and that various operations depicted therein may be omitted, reordered and/or combined.

It will be appreciated that the above described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification.

Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and/or combination of such features.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described example embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is also noted herein that while the above describes various examples, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Example embodiments described herein may be implemented as part of an existing RRC protocol (such as the specification TS38. <NUM>: Radio Resource Control protocol specification).

In the following, we introduce the text that needs to be added into TS <NUM> to enable this functionality. We highlight with underlinings the new added functionality.

Note: In this section we define the MPE functionality at UE upon the reception of the RRC reconfiguration message.

Note: Here we ensure that the UE flushes the previous MPE Assistance Configuration upon an RRC connection re-establishment.

The UE initiates the procedure when one of the following conditions is met:.

Upon initiation of the procedure, the UE shall:.

Note: Here we ensure that the UE flushes the previous MPE Assistance Configuration upon a RRC connection resume.

Note: Here we describe the behaviour of the UE when it should start transmitting the UE Assistance Information.

The purpose of this procedure is to inform the network of the UE's delay budget report carrying desired increment/decrement in the Uu air interface delay, connected mode DRX cycle length, overheating assistance information or MPE assistance information.

A UE capable of providing delay budget report in RRC_CONNECTED may initiate the procedure in several cases, including upon being configured to provide delay budget report and upon change of delay budget preference.

A UE capable of providing overheating assistance information in RRC _CONNECTED may initiate the procedure if it was configured to do so, upon detecting internal overheating, or upon detecting that it is no longer experiencing an overheating condition.

A UE capable of providing MPE assistance information in RRC CONNECTED may initiate the procedure if it was configured to do so, upon detecting the MPE event (i.e. that the UE is below the dmin distance towards the user), or upon detecting that it is no longer experiencing an MPE event.

Upon initiating the procedure, the UE shall:.

The UE shall set the contents of the UEAssistanceInformation message for the MPE event report as follows:.

Note: Here we introduce the changes required in the UE Assistance Information to support the MPE functionality.

The UEAssistanceInformation message is used for the indication of UE assistance information to the network.

Signalling radio bearer: SRB1
RLC-SAP: AM
Logical channel: DCCH
Direction: UE to Network
<IMG>
<IMG>
<IMG>.

Note: Here we introduce the elements that allow the UE to inform the network that is able to provide MPE related UE Assistance.

The IE UE-NR-Capability is used to convey the NR UE Radio Access Capability Parameters, see TS <NUM> [<NUM>]. <IMG>
<IMG>
<IMG>.

Note: In this section we introduce the required RRC information element changes so that a prohibit timer associated with the MPE reporting is defined. This prohibit timer is used by the network to control how often is the UE allowed to trigger the MPE report.

The IE OtherConfig contains configuration related to miscellaneous other configurations. <IMG>
<IMG>.

Note: Here we introduce a timer that allows to control how often can the MPE related UE Assistance message.

Claim 1:
An apparatus comprising:
means for detecting (<NUM>, <NUM>) an occurrence of a maximum permissible exposure event;
means for determining (<NUM>) a severity of the detected maximum permissible exposure event;
means for setting a periodic scheduling override condition to be valid in the event that the detected maximum permissible exposure event is determined to have a high severity; and
means for reporting (<NUM>) maximum permissible exposure assistance information in response to the detection of the occurrence of the maximum permissible exposure event, wherein the means for reporting the maximum permissible exposure assistance information is configured to:
generate a scheduled report in the event that the periodic scheduling override condition is invalid, wherein the scheduled report is sent when a first time period expires; and
generate an unscheduled report in the event that the periodic scheduling override condition is valid, wherein the unscheduled report is sent without waiting for the first time period to expire.