Patent Description:
For facilitating wireless communication in a network, sometimes multiple-input multiple-output (MIMO) techniques are employed. Here, for transmitting and/or receiving (communicating) data on a wireless link, multiple antennas are used as a phased array. Antenna weights, sometimes also referred to as precoding coefficients, define the amplitude and phase relationship between the various antennas.

MIMO techniques are sometimes employed at base stations (BSs). MIMO techniques are sometimes also employed in portable communication devices (user equipment, UE). Here, situations have been observed where the work load imposed on circuitry for controlling, modulating, demodulating, sending and receiving MIMO communication is high so that overheating events occur. An overheating event may relate to a scenario where the temperature of the circuitry exceeds a certain threshold. Damage may result from overheating events, in particular, if persistent over an extended period of time. Generally, overheating events may not only be triggered by MIMO communication, but also by other tasks that impose a significant workload on circuitry of a UE. Examples include carrier aggregation or modulation schemes using high constellations.

Reference implementations of mitigating overheating events include the UE detaching and then re-attaching to the network. After re-attaching, the UE may report a lower carrier aggregation or reduced MIMO capability to the network by means of a UE capability transfer procedure. This may be indicated by transmitting a different UE capability after the re-attach, as compared to prior the re-attach. Such techniques may face certain restrictions and drawbacks. For example, the quality of service may be severely affected by detaching and re-attaching to the network. Increased latency may result.

Further techniques of mitigating overheating include indication of the temperature at the UE. See Third Generation Partnership Project (3GPP) TSG-RAN WG2 #97bis, R2-<NUM>. Then, the MIMO capability or carrier aggregation may be degraded. See 3GPP TSG-RAN WG2 #97bis R2-<NUM>.

There is a need of advanced techniques of mitigating overheating events.

Provided is a method, comprising communicating, on a wireless link between a network node and a communication device, first data at a first data rate. The method further comprises communicating, on the wireless link, at least one uplink control signal associated with an overheating event at the communication device. The method further comprises, in response to said communicating of the at least one uplink control signal: communicating, on the wireless link, second data at a second data rate, wherein the second data rate is different from the first data rate, wherein the uplink control signal is native to the Layer <NUM> or the Layer <NUM> of a communication protocol stack of the wireless link,wherein the at least one uplink control signal comprises a sequence of uplink control signals. The method further comprises: communicating an uplink control message indicative of the overheating event and triggering said communicating of the sequence of uplink control signals in response to said communicating of the uplink control message; wherein the uplink control message is native to a higher layer of a communication protocol stack of the wireless link if compared to the native layer of the at least one uplink control signal.

Also provided is a device comprising control circuitry configured to communicate, on a wireless link between a network node and a communication device, first data at a first data rate, and to communicate, on the wireless link, at least one uplink control signal associated with an overheating event at the communication device. The control circuitry is further configured, in response to said communicating of the at least one uplink control signal, to communicate, on the wireless link, second data at a second data rate, wherein the second data rate is different from the first data rate, wherein the uplink control signal is native to the Layer <NUM> or the Layer <NUM> of a communication protocol stack of the wireless link, wherein the at least one uplink control signal comprises a sequence of uplink control signals. The control circuitry is further configured to communicate an uplink control message indicative of the overheating event, and trigger said communicating of the sequence of uplink control signals in response to said communicating of the uplink control message; wherein the uplink control message is native to a higher layer of a communication protocol stack of the wireless link if compared to the native layer of the at least one uplink control signal.

The techniques facilitate reduction of the latency associated with implementing an adjusted data rate. This enables to efficiently mitigate the overheating event.

Hereinafter, techniques of mitigating overheating events are described. Such techniques may find particular application in mitigating overheating events in UEs. Often, due to the portable nature of the UEs, UEs may have impaired heat dissipation capabilities such that overheating events tend to occur more often.

There may be various reasons for overheating events. For example, overheating events may occur due to communication of data on a wireless link. Operation of receiver or transmitter functionality may require significant energy, e.g., for operating analog and/or digital circuitry such as frontends or modems. Communication of data may impose a significant workload on the circuitry. It has been observed that the work load imposed on the circuitry can further increase if MIMO wireless communication and/or carrier aggregation is employed. For example, for operating an analog front end and/or a digital front end with variable antenna weights, significant energy may be required so that there can be a tendency towards overheating events. Likewise, carrier aggregation or high-order modulation and/or coding schemes may impose usage of additional hardware components, and it may result in increased workload and, in turn, in a tendency towards overheating events.

According to various examples, mitigation of overheating events is achieved by tailoring properties of communication of data on a wireless link. In the various examples described herein, properties of communication of uplink (UL) data and/or of downlink (DL) data may be tailored. In particular, it is possible to implement different data rate used for communicating data on the wireless link. It is possible to implement lower data rates to mitigate the overheating event. There may be a tendency to reduce heating at the UE when using smaller data rates. Therefore, if a lower data rate is implemented - e.g., by scheduling data for communication less frequently or reducing an outflow rate of a transmit buffer -, the overheating event can be mitigated. The UE can be at least partly in control of the data rate in contrast to reference implementation where the UE simply signals the condition, but the measures are fully taken by the network.

According to examples, data is communicated at a different data rate in response to communicating an UL control signal. Hence, implementation of the different data rate can triggered directly by the UL control signaling. In other words, according to examples, at least one UL control signal is transmitted by the UE to indicate a wish to adjust or modify - i.e., increase or reduce - the data rate. This facilitates reduction of the latency associated with implementing an adjusted data rate. This may be helpful in order to efficiently mitigate the overheating event.

The data rate may relate to an amount of data communicated per time unit across a wireless link. The time unit may be significantly larger than individual resource elements, e.g., may be in the order of a milliseconds or even seconds; hence, the data rate may be associated with some averaging. The data rate is sometimes also referred to as data flow.

One approach of adjusting the data rate in accordance with the details described above is to use reference implementations of stop and wait flow control. Here, data communication is stopped until an acknowledgement has been received. However, for a wireless system and in particular a 3GPP system, there are inactivity timers that monitor the activity on the wireless link. These timers are set to significantly lower values than seconds. Temperature gradients are typically slow, in the order of seconds or several seconds or even minutes. The slow temperature gradient indicates that a stop and wait approach would result in inactivity time-out of the wireless link. Therefore, according to further techniques, the data rate is adjusted using a resource scheduling functionality based on the UL control signal transmitted by the UE. By scheduling small data chunks with an interval that is still within the time window imposed by an inactivity timer, the scheduler can reduce the data rate and keep the wireless link active.

This UL control signal may be preceded or announced by a higher-layer UL control message. For example, an UL control message native to Layer <NUM> of a communication protocol stack of the wireless link may be used to indicate that a sequence of UL control signals will be transmitted by the UE to implement regulation of the data rate.

The UL control signal may be communicated in response to detecting an overheating event. As such, the UL control signal may be associated with the overheating event. For example, the UL control signal may be indicative of the overheating event. For example, the mere presence of the UL control signal may indicate to the recipient of the UL control signal, e.g., to the BS, that the overheating event occurs at the UE. The UL control signal may include an indicator indicative of an amount of the adjustment of the data rate that is required for mitigating an overheating event. For example, the UL control signal may include an indicator indicative of the difference between an initial data rate used for communicating data prior to communication of the UL control signal and a subsequent data rate used for communicating data after communication of the UL control signal. Such indication could be in terms of predefined increments, thereby defining different states of adjustment need.

The indicator may indicate whether the limitation should be applied to upcoming data transmissions in the uplink direction and/or downlink direction. Thereby, the UE can prioritize DL communication or UL communication, e.g., depending on certain service requirements, etc..

The indicator could be related to the different UE capabilities defined within 3GPP.

In some examples, the network, e.g., the BS, may respond to UL control signal to confirm the requested change of the data rate. The response may include an indicator indicative of the new data rate implemented in response to receiving UL control signal.

Implementing a given data rate may include specifying a threshold data rate that is not to be exceeded. Then, the actual data rate used for communicating data on the wireless link may be equal or below the threshold data rate, e.g., depending on an amount of data in a transmit buffer of the communication protocol stack. For example, if the transmit buffer of the communication protocol stack includes data queued for transmission, the data rate may equal the threshold data rate. If, on the other hand, the transmit buffer is at least temporarily empty, then, the data rate may be smaller than the threshold data rate. In some examples, it is possible that the at least one UL control signal includes an indicator indicative of the threshold data rate. Then, it is possible to implement the data rate for communicating data in accordance with the threshold data rate.

One method of implementing a data rate limitation is to include a ratio of scheduled and non-scheduled subframes. During a non-scheduled subframe, data communication can be conducted between the base station and other UEs connected with the base station, but not between the base station and the particular UE. For example, if the communication of the wireless link includes one non-scheduled subframe every <NUM> subframes, the data rate is limited with <NUM>%. If in another example a non-scheduled subframe is included every second subframe, the data rate is limited with <NUM>%.

A further technique of implementing such a data rate limitation is to implicitly indicate the threshold data rate, e.g., by indicating an amount of carriers in a carrier aggregation scenario.

<FIG> schematically illustrates a wireless communication network <NUM> which may benefit from the techniques disclosed herein. , the network <NUM> may be a 3GPP specified network such as <NUM>, <NUM> and upcoming <NUM>. Other examples include point-to-point networks such as Institute of Electrical and Electronics Engineers (IEEE) - specified networks, e.g., the <NUM>. 11x Wi-Fi protocol or the Bluetooth protocol.

The network <NUM> includes a BS <NUM> and a UE <NUM>. A wireless link <NUM> is established between the BS <NUM> and the UE <NUM>. The link <NUM> includes a DL channel from the BS <NUM> to the UE <NUM>; and further includes an UL channel from the UE <NUM> to the BS <NUM>. Data - e.g., payload data or control data - can be communicated in UL and DL. TDD and/or frequency-division duplexing (FDD) may be employed for the DL channel and the UL channel. This is facilitated by resource elements of a time-frequency resource mapping.

For example, the UE may be portable. The UE may be battery-powered. The UE may be selected from the group comprising: smartphone; laptop; smart TV; Machine Type Communication (MTC) sensor or actuator. In particular battery powered device may face restrictions with respect to heat dissipation and cooling so that overheating events may occur more likely.

<FIG> schematically illustrates the BS <NUM> and the UE <NUM> in greater detail. The BS <NUM> includes a processor <NUM> and a transceiver <NUM>. The transceiver <NUM> includes a module <NUM> including a plurality of antennas <NUM> for MIMO wireless communication. Each antenna <NUM> may include one or more electrical traces to carry a radio frequency current. Each antenna <NUM> may include one or more LC-phase shifters implemented by the electrical traces. Each traces may radiate electromagnetic waves and when combined can create a certain beam pattern. As such, the antennas <NUM> may form an antenna port for providing an output signal. The BS <NUM> further includes a memory <NUM>, e.g., a non-volatile memory. The memory may store control instructions that can be executed by the processor <NUM>. Executing the control instructions causes the processor <NUM> to perform techniques with respect to adjusting the data rate to mitigate overheating events at the UE <NUM>.

The UE <NUM> includes a processor <NUM> and a transceiver <NUM>. The transceiver <NUM> includes a module <NUM> including a plurality of antennas <NUM> for MIMO wireless communication. Each antenna <NUM> may include one or more electrical traces to carry a radio frequency current. Each antenna <NUM> may include one or more LC-phase shifters implemented by the electrical traces. Each traces may radiate electromagnetic waves and when combined can create a certain beam pattern. As such, the antennas <NUM> may form an antenna port for providing an output signal. The UE <NUM> further includes a memory <NUM>, e.g., a non-volatile memory. The memory <NUM> may store control instructions that can be executed by the processor <NUM>. Executing the control instructions causes the processor <NUM> to perform techniques with respect to adjusting the data rate to mitigate overheating events at the UE <NUM>.

Different spatial streams may be supported between the transceivers <NUM>, <NUM> on the channel <NUM>. The different spatial streams are associated with different antennas <NUM> in module <NUM> of the UE <NUM>.

In the various examples described herein, it is possible that logic associated with mitigating overheating events at the UE <NUM> resides fully or partially at the BS <NUM>; likewise, it is possible that logic associated with mitigating overheating events at the UE <NUM> resides fully or partially at the UE <NUM>.

Overheating events can occur at the UE <NUM>. For example, if complex communication tasks are imposed on the interface <NUM>, the temperature at the interface <NUM> and/or at the processor <NUM> may rise above a certain threshold. Then, damage may occur. It has been observed that overheating events are more likely to occur if the communication of data on the wireless link <NUM> is comparably complex, e.g., uses multiple spatial streams and/or employs carrier aggregation, aggregation of two or more radio access communication technologies, uses a high transmission power for a long period of time, and/or employs a modulation and/or coding scheme having a high constellation.

<FIG> illustrates aspects with respect to an overheating event <NUM>. In detail, <FIG> illustrates a time dependency of the data rate <NUM> (full line) and a time dependency of a temperature <NUM> (dashed line ) which is associated with the overheating event <NUM>.

In particular, an overheating event <NUM> may occur if the temperature <NUM> rises above a threshold (horizontal dotted line). The temperature <NUM> may be the temperature of a circuitry, e.g., of the processor <NUM> of the UE <NUM>. The overheating event <NUM> may generally resolve (not shown in <FIG>) once the temperature <NUM> falls below the threshold, e.g., for a certain period of time or with a certain safety margin. Short or temporary drops of the temperature <NUM> below the threshold may or may not resolve the overheating event <NUM>.

<FIG> illustrates a correlation between the data rate <NUM> and the temperature <NUM>. In particular, while initially a comparably small data rate <NUM> is used for communicating data, eventually, a larger data rate <NUM> is used for communicating data. Then, the temperature <NUM> increases and finally crosses the threshold such that in overheating event <NUM> occurs.

For example, the overheating event <NUM> may be due to complex reconstruction, demodulation, or decoding of received data. Then, if the data rate <NUM> increases, the associated workload increases which generally results in increased heat dissipation. This increases the temperature <NUM>. In particular, computational tasks associated with MIMO reception or MIMO transmission or carrier aggregation or demodulation/decoding can result in significant workload.

Hereinafter, techniques are described which enable to mitigate the overheating event <NUM>. For example, the techniques described herein may enable to pro-actively prevent occurrence of the overheating event <NUM>. Alternatively or additionally, the techniques described herein may enable to provide cooling if an overheating event <NUM> has occurred.

<FIG> is a flowchart of a method according to various examples. The method according to <FIG> allows for mitigating overheating events. For example, the method according to <FIG> could be executed by the processor <NUM> of the BS <NUM>. It would also be possible that the method according to <FIG> is executed by the processor <NUM> of the UE <NUM>.

In <NUM>, first data is transmitted and/or received (communicated) at a first data rate. For example, the first data may be transmitted by the BS <NUM>. It would also be possible that the first data is transmitted by the UE <NUM>. The first data may be received by the BS <NUM>. It would also be possible that the first data is received by the UE <NUM>.

Then, in <NUM>, one or more UL control signals are communicated. It would be possible that the one or more UL control signals are transmitted by the UE <NUM>. It would be possible that the one or more UL control signals are received by the BS <NUM>.

The UL control signals may be piggybacked on an acknowledgement message. The UL control signals may include one or more symbols which encode information.

The one or more UL control signals are associated with an overheating event at the UE. For example, the one or more UL control signals may be transmitted by the UE in response to detecting the overheating event. Hence, implementation of the second data rate can triggered directly by the UL control signal. Intermediate steps - such as a re-attach or a change of the modulation and/or coding scheme or the MIMO capability - may not be required. For example, the one or more UL control signals may be indicative of the overheating event. For example, the one or more control signals may include an indicator indicative of the overheating event. It would also be possible that the one or more control signals include an indicator indicative of a countermeasure implemented or proposed in view of the overheating event. The countermeasure may include implementing an adjusted data rate for communicating data.

In <NUM>, second data is communicated on the wireless link at a second data rate. The second data rate is different from the first data rate at which the first data is communicated in <NUM>. For example, the second data rate may be smaller than the first data rate or larger than the first data rate.

The second data is communicated in <NUM> in response to communicating the UL control signal in <NUM>. Hence, the second data rate is implemented in response to communicating the one or more UL control signals at <NUM>. For example, the second data rate may be implemented based on an instruction indicated by an indicator included in the UL control signal. For example, the indicator may be indicative of a difference between the first data rate and the second data rate. Such implementation of an adjusted data rate triggered by the UL control signal enables to mitigate the overheating event at a comparably small latency. In particular, if compared to reference implementations where the data rate is adjusted only in response to a change of, e.g., the modulation and/or a coding and/or MIMO scheme, a shorter latency can be provided when mitigating the overheating event.

The first data communicated in <NUM> may include UL data and/or DL data. Likewise, the second data communicated in <NUM> may include UL data and/or DL data.

<FIG> is a signal flow diagram illustrating aspects with respect to communicating data between the BS <NUM> and the UE <NUM>. <FIG> illustrates aspects with respect to adjusting the data rate <NUM> of said communicating of the data for mitigating an overheating event.

At <NUM> - <NUM>, DL data <NUM> is communicated on the wireless link <NUM> from the BS <NUM> to the UE <NUM>. The DL data <NUM> is communicated at a comparably large data rate <NUM>-<NUM>. Thus, eventually, an overheating event <NUM> occurs.

The UE <NUM> continuously monitors a temperature and, thus, detects the overheating event <NUM>. For mitigating the overheating event <NUM>, the UE <NUM> transmits an UL control signal <NUM> at <NUM>. The BS <NUM> receives the UL control signal <NUM> at <NUM>. In response to receiving the UL control signal <NUM>, the BS <NUM> implements a lower data rate <NUM>: DL data <NUM> is communicated at <NUM> - <NUM> at the lower data rate <NUM>-<NUM>. This results in a decreasing temperature at the UE <NUM> and, eventually, the overheating event <NUM> resolves.

The UE <NUM> then transmits another UL control signal <NUM> at <NUM> and, in response to receiving the UL control signal <NUM> at <NUM>, the BS <NUM> again implements the higher data rate <NUM>-<NUM>. DL data at <NUM> is then communicated at <NUM> - <NUM> at the higher data rate <NUM>-<NUM>.

<FIG> also illustrates aspects with respect to a threshold data rate <NUM>. The threshold data rate <NUM> sets an upper limit for the data rate <NUM>-<NUM> with which the DL data <NUM> is communicated at <NUM> - <NUM>, i.e., in response to the UL control signal <NUM> communicated at <NUM>. For example, it would be possible that the UL control signal <NUM> includes an indicator explicitly or implicitly indicative of the threshold data rate <NUM>. Then, it may be possible that the BS <NUM> implements the lower data rate <NUM>-<NUM> according to which the DL data <NUM> is communicated at <NUM> - <NUM> in accordance with the threshold data rate <NUM>. Hence, it may be possible that the BS <NUM> limits the lower data rate <NUM>-<NUM> accordingly. For example, the threshold data rate <NUM> may be explicitly indicated in absolute terms, e.g., by specifying the threshold data rate <NUM> in bits per second, etc.. Alternatively, the threshold data rate <NUM> may be implicitly indicated, e.g., by specifying the count of carriers in a carrier aggregation scenario.

In the example of <FIG>, the lower data rate <NUM>-<NUM> is continuously limited by the threshold data rate <NUM>. This may be because there is DL data <NUM> scheduled for transmission by the BS <NUM> in a transmit buffer of a communication protocol stack. Then, there may be no dead times during which there is no DL data <NUM> available for transmission. This is why the lower data rate <NUM>-<NUM>, in the example of <FIG>, equals the threshold data rate <NUM>. In other examples, the lower data rate <NUM>-<NUM> may at least temporarily drop below the threshold data rate <NUM>.

In <FIG>, the difference <NUM> between the threshold data rate <NUM> and the higher data rate <NUM>-<NUM> is illustrated. According to some examples, the difference <NUM> may be predefined, e.g., in relative terms with respect to the initial, higher data rate <NUM>-<NUM>. , the difference <NUM> may be in the range of +/- <NUM>%, or +/-<NUM>%, or +/- <NUM>% change if compared to the initial higher data rate <NUM>-<NUM>. Alternatively or additionally, it would also be possible to include an indicator in the UL control signal <NUM> communicated at <NUM> which is indicative of the difference <NUM>. For example, it would be possible to dimension the difference <NUM> larger for larger temperatures associated with the overheating event <NUM>, and vice versa.

The threshold data rate <NUM> may or may not be smaller than the maximum data rate that is supported by parameters of the communication protocol stack of the wireless link <NUM> in accordance to the modulation and/or coding scheme used for said communicating of the data <NUM> in <NUM> - <NUM>. The maximum data rate may be the maximum nominal data rate achievable by the given modulation and/or coding scheme employed for communicating the data <NUM>. The maximum data rate may be the maximum nominal data rate achievable by the given MIMO capability, e.g., MIMO rank or number of spatial streams. The maximum data rate may be the maximum nominal data rate achievable by the given level of carrier aggregation. By dimensioning the threshold data rate <NUM> to be smaller than the maximum data rate that is supported by the parameters of the communication protocol stack, it is possible to reduce the workload imposed on control circuitry of the UE <NUM> - while maintaining the capability to increase the data rate on a short timescale, e.g., up to the maximum data rate, once the overheating event has resolved. In particular, it can be then possible to increase the data rate on the short timescale, e.g., up to the maximum data rate, without having to reconfigure the MIMO capability, the modulation and/or coding scheme, and/or the <NUM> aggregation. For example, between implementing the lower data rate <NUM>-<NUM> and the higher data rate <NUM>-<NUM>, it may not be required to reconfigure the MIMO capability, the modulation and/or coding scheme, and/or the carrier aggregation. This enables to implement adjusted data rates <NUM> on a short timescale, thereby increasing the flexibility in mitigating the overheating event and giving the possibility maximize the overall aggregated network data throughput. This is an example implementation: in other examples, the MIMO capability, the modulation and/or coding scheme, and/or the carrier aggregation may be reconfigured to implement the lower data rate <NUM>-<NUM>.

In the example of <FIG>, DL data <NUM> is transmitted by the BS <NUM> and received by the UE <NUM>. In other examples, it could also be UL data <NUM> which is transmitted by the UE <NUM> and received by the BS <NUM> which is subject to adjustment of the data rate <NUM> for mitigating an overheating event <NUM>. Such an example is illustrated in <FIG>.

<FIG> is a signal flow diagram illustrating aspects with respect to communicating data between the BS <NUM> and the UE <NUM>. <FIG> illustrates aspects with respect to adjusting the data rate of said communicating of the data for mitigating an overheating event.

The example of <FIG> generally corresponds to the example of <FIG>. However, at <NUM> - <NUM>, UL data <NUM> is communicated from the UE <NUM> to the BS <NUM>. Then, the overheating event <NUM> occurs and, at <NUM>, the UE <NUM> again transmits the UL control signal <NUM>. Based on the UL control signal <NUM> and the buffer status report from the UE <NUM>, the BS <NUM> will provide scheduling grants according to a lower data rate <NUM>-<NUM>.

Subsequently, at <NUM> - <NUM>, the UE <NUM> transmits UL data <NUM> at a lower data rate <NUM>-<NUM> if compared to the higher data rate <NUM>-<NUM> used for communication of the UL data <NUM> at <NUM> - <NUM>.

Once the overheating event <NUM> has resolved, the UE <NUM> transmits an UL control signal <NUM> at <NUM> and then transmits the UL data <NUM> at <NUM> - <NUM> again at the higher data rate <NUM>-<NUM>.

In the scenarios of <FIG> and <FIG> and, generally, the various examples described herein, there are various techniques conceivable for implementing adjusted data rates <NUM>, <NUM>-<NUM>, <NUM>-<NUM>, i.e., throttling techniques.

<FIG> illustrates aspects with respect to implementing an adjusted data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM>. According to the example of <FIG>, a given data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM> is implemented by changing a scheduling rate <NUM> of resources allocated for communicating of DL data <NUM>. Similar techniques may also be employed for communicating UL data <NUM>.

The scheduling rate <NUM> may generally define the number of resources allocated per time unit. This scheduling rate may be adjusted by changing a time between subsequent scheduling occasions and/or changing the number of resources per scheduling occasion.

In <FIG>, a DL assignment <NUM> is transmitted by the BS <NUM> and received by the UE <NUM>, <NUM> (in the case of UL data <NUM>, a UL grant would be transmitted). The DL assignment <NUM> is associated with a scheduling occasion. For example, the DL assignment <NUM> may be communicated on a DL control channel, e.g., in the case of 3GPP LTE on the physical DL control channel (PDCCH). The DL assignment <NUM> is indicative of one or more time-frequency resource elements of a time-frequency resource mapping implemented by the wireless link <NUM>.

For example, the time-frequency resource mapping may include multiple resource elements which are associated with symbols of a modulation scheme. For example, the frequency bandwidth of an individual resource element may correspond to the frequency bandwidth of a subcarrier of a Orthogonal Frequency Division Multiplexing (OFDM) modulation and coding scheme.

Then, at <NUM>, DL data <NUM> is transmitted by the BS <NUM> and received by the UE <NUM>. The DL data <NUM> is communicated in the one or more time-frequency resource elements indicated by the DL assignment <NUM> communicated at <NUM>. For example, the DL data <NUM> communicated at <NUM> may be payload data. For example, in the case of 3GPP LTE, the DL data <NUM> may be communicated in a Physical DL Shared Channel (PDSCH) at <NUM>.

After a while, another DL assignment <NUM> is communicated at <NUM> and associated DL data <NUM> is communicated at <NUM>. The timing between the subsequent DL assignments <NUM> or scheduling occasions correlates with the scheduling rate <NUM>. For higher (lower) scheduling rates <NUM>, higher (lower) data rates <NUM>, <NUM>-<NUM>, <NUM>-<NUM> are obtained. Alternatively or additionally, different scheduling rates <NUM> could also be implemented by changing the count of resources elements per scheduling occasion. For example, a scheduler functionality of the BS <NUM> may be configured to set the scheduling rate <NUM> depending on the required data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM>. By adjusting the scheduling rate <NUM>, it is possible to adjust a duty cycle of the interface <NUM> of the UE <NUM>. By reducing the scheduling rate <NUM>, the interface <NUM> of the UE <NUM> may receive or transmit data less frequently; thereby, reducing the amount of heat generated.

<FIG> illustrates aspects with respect to implementing an adjusted data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM>. According to the example of <FIG>, a given data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM> is implemented by changing an outflow rate of a transmit buffer <NUM>, <NUM> for communicating data <NUM> on the wireless link <NUM>.

<FIG> illustrates aspects with respect to a communication protocol stack <NUM> implemented for communication on the wireless link <NUM>. The communication protocol stack <NUM> includes a transmit section <NUM> and receive section <NUM>. Depending on the directivity of the communicated data, the transmit section <NUM> may be implemented by the BS <NUM> for DL data or by the UE <NUM> for UL data. For bi-directional communication, both, BS <NUM> and UE <NUM> implement the transmit section <NUM> and the receive section <NUM>.

The communication protocol stack <NUM> includes multiple layers <NUM> - <NUM>. The lowest layer <NUM> is Layer <NUM>, sometimes also referred to as the physical layer. Next up in hierarchy is the layer <NUM>, referred to as Layer <NUM> or data link layer. Still further up in hierarchy is the layer <NUM>, referred to as Layer <NUM> or network layer. See, for example, International Telecommunication Union ITU-T X. <NUM> (<NUM>/<NUM>), section <NUM>.

Different layers <NUM> - <NUM> may be associated with different native data units that are handled and processed by that layer <NUM>-<NUM>. For example, the layer <NUM> may sometimes be associated with so-called transport blocks, e.g., of fixed size. The layer <NUM> may be associated with service data units and packet data units of variable size. Likewise, the layer <NUM> may be associated with frames or datagrams. Concatenation and/or segmentation may be employed between native data units at the boundaries between the different layers <NUM> - <NUM>.

<FIG> also illustrates aspects with respect to buffers <NUM> - <NUM>. Transmit buffers <NUM>, <NUM> are provided for the layers <NUM>, <NUM>; corresponding receive buffers <NUM>, <NUM> are also provided. The respective native data units can be queued in the respective transmit buffers <NUM>, <NUM>. By changing the outflow rate of one or more of the transmit buffers <NUM>, <NUM> it is possible to implement a given data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM>. For example, a higher (lower) outflow rate corresponds to a higher (lower) data rate <NUM>, <NUM>-<NUM>, <NUM>-<NUM>. The outflow rate may define how many data units are retrieved from the respective transmit buffer <NUM>, <NUM> per time unit.

As illustrated in <FIG>, it is possible to use different outflow rates of low-level transmit buffers <NUM>, <NUM> of the layers <NUM>, <NUM>. This enables to implement different data rates <NUM>, <NUM>-<NUM>, <NUM>-<NUM> at a low latency. This is because the time between outflow of a given native data unit from the respective transmit buffer <NUM>, <NUM> to transmission via the wireless link <NUM> is comparably low for the lower layers <NUM>, <NUM>.

<FIG> illustrates aspects with respect to communicating a sequence <NUM> of UL control signals <NUM>. In <FIG>, the time dependency of the data rate <NUM> is illustrated (solid line). Furthermore, in <FIG>, the time dependency of the temperature <NUM> associated with an overheating event <NUM> is illustrated (dashed line). The example of <FIG> generally corresponds to the example of <FIG>.

In the example of <FIG>, a sequence <NUM> of UL control signals <NUM> is communicated. Different data rates <NUM> are incrementally implemented using multiple subsequent adjustments in response to communicating each UL control signals <NUM> of the sequence <NUM>. The difference <NUM> of the data rates implemented prior to and after such an incremental adjustment is illustrated in <FIG> for illustrative purposes. The difference <NUM> may be defined in relative terms, e.g., with respect to the respective data rate implemented prior to an incremental adjustment.

To facilitate such an incremental implementation of the data rate <NUM>, it would be possible that the various UL control signals <NUM> include indicators which are indicative of a sign of the difference <NUM> of an incremental adjustment. Optionally, the various UL control signals <NUM> could also be indicative of the magnitude of the difference <NUM> of an incremental adjustment, e.g., in relative or absolute terms. Alternatively, a predefined magnitude may be used.

It is possible that the UE <NUM> monitors the temperature <NUM> which is associated with the overheating event <NUM>. Then, the respective indicator included in the UL control signals <NUM> can be repeatedly adjusted based on said monitoring.

By using the UL control signals <NUM> which include indicators indicative of the sign or the magnitude of the difference <NUM> of an incremental adjustment to the implemented data rate, the signaling overhead can be reduced. In particular, a size of the corresponding indicator can be comparably small if compared to the size of indicators which indicate the temperature <NUM> or the required data rate in absolute terms. This facilitates communication of multiple UL control signals <NUM>.

Again, it would be possible that incremental adjustments to the data rate <NUM> are implemented in accordance with a threshold data rate (not illustrated in <FIG>). For example, the difference <NUM> indicated by respective indicators may be associated with the respective threshold data rate. Then, if no or only a limited amount of data is to be transmitted, the actual data rate <NUM> can fall below the threshold data rate which is incrementally changed.

<FIG> also illustrates a time interval <NUM> between adjacent UL control signals <NUM> of the sequence <NUM>. In some examples, communication of the UL control signals <NUM> may occur at a high repetition rate. For example, an average time interval <NUM> may not be larger than <NUM> seconds, further optionally not larger than <NUM> second, further optionally not larger than200 milliseconds, optionally not larger than <NUM> milliseconds, further optionally not larger than <NUM> millisecond. Thereby, it may be possible to facilitate low-latency mitigation of the overheating event <NUM>. For example, adjacent UL control signals <NUM> of the sequence <NUM> may be communicated in adjacent frames or subframes of a transmission protocol of the wireless link <NUM>.

For example, such a short time interval <NUM> can be facilitated if the UL control signals <NUM> are piggybacked on control messages, e.g., automatic repeat request (ARQ) control messages such as positive or negative acknowledgments that may be communicated on a Physical Hybrid-ARQ Indicator Channel (PHICH). Such techniques may be generally applied to the various examples described herein. Generally, instead of an ARQ control message it would be possible to piggyback to other control messages, e.g., the Medium Access (MAC) CE part of the MAC control message, preferably for uplink control, and CSI similar indications to control the downlink data rate.

The time intervals <NUM> may be fixed, i.e., the UL control signals <NUM> may be communicated at a fixed periodicity. The time intervals <NUM> may vary, e.g., according to the varying temperature at the UE.

It may not be required to communicate the UL control signals <NUM> if there is no adjustment to the implemented data rate <NUM> (cf. flat regions of the full line in <FIG>). Thus, while in <FIG> UL control signals <NUM> are communicated at a fixed periodicity, in other examples, it would be possible to, e.g., only communicate the UL control signals <NUM> if there are adjustments to the implemented data rate <NUM>.

As will be appreciated from <FIG>, it is possible to provide a closed-loop control of the temperature <NUM> associated with the overheating event <NUM> based on said incremental implementation of a certain data rate <NUM>. Implementing adjusted data rates can serve as the corrective action of the closed-loop control.

In <FIG>, a set temperature <NUM> is illustrated; the temperature <NUM> is regulated towards this set temperature <NUM>. Overshoots and undershoots of a transient phase are illustrated. Finally, the temperature <NUM> settles close to the set temperature <NUM>. The set temperature <NUM> is dimensioned to be adjacent to the threshold associated with the overheating event <NUM>; this maximizes the data throughput. In particular, by using the UL control signals <NUM>, a feedback can be provided which indicates the impact of the difference <NUM> associated with an incremental adjustment of the data rate <NUM> on the temperature <NUM>. By providing such a feedback, different sensitivities of the temperature <NUM> on the incremental changes - as encountered for different types of UEs <NUM> or even for UEs <NUM> which operate in different environments - may be taken into account. Thereby, unnecessary reduction of the data rate <NUM> is avoided and the overall throughput of data may be maximized - while still mitigating overheating events <NUM>.

To further facilitate low-latency communication of the UL control signals <NUM> - which may be of particular relevance when implementing the closed-loop control of the temperature <NUM> -, it is possible that the UL control signals <NUM> are native to one of the lower layers <NUM>, <NUM> of the transmission protocol stack <NUM> of the wireless link <NUM>, i.e., to Layer <NUM> or Layer <NUM>.

Sometimes, it may be desirable to appropriately configure such a closed-loop control of the temperature <NUM> between the BS <NUM> and the UE <NUM>.

<FIG> illustrates aspects with respect to communicating an UL control message <NUM> from the UE <NUM> to the BS <NUM>. The UL control message <NUM> is communicated at <NUM>, i.e., transmitted by the UE <NUM> and received by the BS <NUM>. Communicating the UL control message <NUM> triggers subsequent communication of a sequence <NUM> of UL control signals <NUM> at <NUM> - <NUM>.

For example, it would be possible to provide a closed-loop control of the temperature <NUM> associated with the overheating event <NUM> based on incremental adjustments of the data rate implemented in response to communicating the various UL control signals <NUM>. It would be possible that the control message <NUM> is indicative of certain properties of the closed-loop control. For example, the control message <NUM> could be indicative of reoccurring time-frequency resources used for communicating the UL control signals <NUM> of the sequence <NUM>. Alternatively or additionally, the control message <NUM> could be indicative of the difference <NUM> of an incremental adjustment of the data rate <NUM>, e.g., the magnitude thereof; as such, the difference <NUM> may be predefined with respect to the closed-control. Alternatively or additionally, the control message <NUM> could be indicative of the time interval <NUM> between adjacent UL control signals <NUM> of the sequence <NUM>. Potentially the BS <NUM> may reply with a response message acknowledging that the UE is allowed to initiate data rate control.

To accommodate such complex information, it would be possible that the UL control message <NUM> is native to a higher layer <NUM>, <NUM> of the transmission protocol stack <NUM> if compared to the native layer of the UL control signals <NUM>. For example, if the UL control signals <NUM> are native to layer <NUM>, the UL control message <NUM> could be native to layer <NUM> or layer <NUM>.

<FIG> illustrates aspects with respect to the UL control signal <NUM>. In the example of <FIG>, the UL control signal <NUM> includes an indicator <NUM> which is indicative of the sign of the difference <NUM> of an incremental change of the data rate <NUM>. In the example of <FIG>, the indicator is indicative of a positive difference <NUM> of the associated incremental change of the data rate <NUM>. Hence, an increased data rate <NUM> is implemented.

<FIG> illustrates aspects with respect to the UL control signal <NUM>. In the example of <FIG>, the UL control signal <NUM> includes an indicator <NUM> which is indicative of, both, the sign and the magnitude of the difference <NUM> of an incremental change of the data rate <NUM>. In the example of <FIG>, the indicator <NUM> is indicative of a comparably large negative difference <NUM> of the associated incremental change of the data rate <NUM>. Hence, a strongly reduced data rate <NUM> implemented.

In the various examples described herein, it would be possible that the indicator <NUM> which may be included in the UL control signal <NUM> has a limited length. For example, the indicator <NUM> could be a <NUM>-bit or <NUM>-bit or <NUM>-bit in length or generally not larger than <NUM>-bit in length. This facilitates low-latency communication of the UL control signal <NUM> and enables a high repetition rate of the UL control signal <NUM>. Furthermore, such length-limited control signal <NUM> may be piggybacked onto other signals.

<FIG> is a flowchart of a method according to various examples. For example, the method according to <FIG> may be executed by the processor <NUM> of the UE <NUM>.

At <NUM>, it is checked whether an overheating event <NUM> is detected. For example, the measured temperature <NUM> of control circuitry of the UE <NUM> may be compared to the predefined threshold. The threshold may be specific to the particular UE <NUM> and/or the operating environment of the UE <NUM>.

If no overheating event is detected at <NUM>, communicating of the data at the first data rate commences at <NUM>. If an overheating event <NUM> is detected at <NUM>, the method commences at <NUM>.

At <NUM>, the higher-layer UL control message <NUM> is transmitted by the UE <NUM>. The UL control message <NUM> is indicative of the overheating event <NUM>. For example, the UL control message <NUM> may include an indicator indicative of the temperature <NUM> associated with the overheating event <NUM> which may serve as a seed value for subsequent closed-loop control <NUM>.

At <NUM>, the temperature <NUM> associated with the overheating event <NUM> is measured. It is then checked, at <NUM>, whether this temperature <NUM> is below or above a set temperature <NUM>.

If the temperature is below or above the set temperature, then, at <NUM>, and UL control signal <NUM> is communicated which includes an indicator indicative of an increase or decrease of the data rate <NUM>. As such, the indicator may be indicative of the sign of the difference <NUM> associated with the incremental change of the data rate. Optionally, the indicator could also be indicative of a magnitude of the difference <NUM>; the magnitude may be determined based on a difference between the temperature <NUM> and the set temperature <NUM>.

At <NUM>, it is checked whether the overheating event <NUM> has resolved. For example, if the temperature <NUM> has fallen significantly below the lower threshold of the overheating event <NUM>, it can be judged that closed-loop control <NUM> of the temperature <NUM> is not required anymore. Then, a higher-level UL control message can be transmitted at <NUM> which informs the BS <NUM> accordingly.

If the overheating event is judged to not have resolved, then, closed-loop control <NUM> proceeds by re-measuring the temperature at another iteration of <NUM>.

Throughout execution of the method according to the example of <FIG>, data may be communicated (not illustrated in <FIG>). The data may be communicated in accordance with a data rate implemented in accordance with the uplink control signal communicated at subsequent iterations of <NUM>. Throughout the method according to the example of <FIG> and, in particular, throughout the closed-loop control <NUM>, it would be possible to maintain one and the same modulation scheme, coding scheme, and MIMO scheme for the communication of data. In particular, it can be expendable to adjust a UE category which is associated with a particular modulation and/or coding scheme. See for example 3GPP Technical Specification <NUM> V14. Likewise, the MIMO rank may be maintained. Instead of changing such underlying properties of the communication, it is rather possible to directly implement changes to the data rate <NUM>, e.g., by appropriately scheduling and/or retrieving data from a transmit buffer.

In <FIG>, the closed-loop control is triggered by an overheating event at <NUM>. In other examples, the closed-loop control <NUM> could also be triggered if the temperature falls below a threshold so that the data rate is increased in a controlled fashion.

Summarizing, above, techniques of mitigating overheating events have been described. As will be appreciated from the above, there are different options available for mitigating overheating events. Here, techniques are described which enable to keep the original UE category from the initial registration of the UE, still supporting highest order of modulation and MIMO as configured. This supports the network using the most efficient method to communicate data on a wireless link, maximum utilization of the radio resources, etc..

A dynamic control of the scheduler is described to regulate the data rate and, thereby, the work load imposed on the UE. Alternatively or additionally to controlling scheduling, it would also be possible to control the outflow rate of a transmit buffer to regulate the data rate.

Various techniques described herein are based on the finding that heat dissipation can occur slower in time domain if compared to conventional data-flow control. Therefore, legacy data-flow control may be enhanced to mitigate overheating events. In particular, legacy acknowledgment timers/inactivity timers may be unsuited for mitigating overheating events.

According to examples, the data rate is controlled by piggybacking UL control signals on ARQ control messages. Generally, an UL control signal may be communicated from the UE to the BS which is indicative that the UE requires a modification of the data rate. By changing the data rate, the duty cycle of a modem of the UE can be relaxed such that the heat dissipation reduces.

In some examples, an UL control signal can be indicative of a sign of a difference between incremental implementations of adjusted data rates. This could be denoted as ACK + "up" and ACK + "down". Thereby, it is possible to provide a large data throughput while still mitigating overheating events. By such techniques, the BS can control the data throughput and mitigate overheating events while still taking into account varying requirements for different UEs. For example, different UEs or UEs operating in different environments may show different characteristics with respect to heat transfer or temperature stabilization. Thus, the dataflow is not unnecessarily throttled down.

Incremental changes to the data rate corresponds to step functions, where each step may be defined in relative terms, e.g., +/-<NUM>% if compared to the previously implemented data rate (applying to a <NUM>-bit implementation of an indicator included in the UL control signal). It would also be possible to indicate the magnitude of the step with higher resolution, e.g., +/-<NUM>%, <NUM>%, <NUM>%, <NUM>%.

Above, techniques with respect to implementing such a closed-loop control have also been explained in view of control signaling. For example, if the UE detects an overheating event - or, generally, any other reason for limiting the data rate -, the UE can transmit a UL control signal. The UL control signal could be part of a hybrid ARQ acknowledgment/negative acknowledgment message or a separate Layer <NUM> message valid for a specific wireless link. The UL control signal could also be a Radio Resource Control (RRC) message, or generally a Layer <NUM> or Layer <NUM> message. Such a message may be valid for a complete PDU session. The UL control signal may include a step indicator, wherein the step indicator is indicative of the amount of reduction or increase of the data rate required. This may be in terms of a reduced scheduling rate/duty cycle or a target maximum average data rate.

The UE may further indicative the reduction/increase of the data rate is required for, both, UL data and DL data, or selectively required for a specific direction. Thereby, a prioritization of DL data vis-à-vis UL data, or vice versa, can be achieved. For 3GPP <NUM>, the UE may further indicate a preference of the radio access technology is configured to use LTE - New Radio (NR) dual connectivity. For example, it could be indicated whether the adjustment of the data rate applies to 3GPP LTE and/or 3GPP NR.

Such techniques can be seen as a state machine control where each implemented data rate corresponds to certain state. The network may send a response to confirm the current state of the UE overheating event. The response by the network may include a network indicated target data rate which may or may not be the same as the data rate requested by the UE.

As will be appreciated from the above, by such techniques, the UE can inform the network about an overheating event. The UE can request a certain reduction of the data rate required to mitigate the overheating event. The network - when informed about the overheating event - keeps in charge of the access to take and may or may not consider the suggestions by the UE. The UE can be informed about the decision of the network, as a response to the UE indication. The UE can inform about a further need to reduce the power consumption, by sending a sequence of UL control signals. The UE can inform in the overheating event has resolved.

Although the invention has been shown and described with respect to certain preferred embodiments, equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the appended claims.

For illustration, above, various examples have been described with respect to tailoring communication of UL data or DL data. Similar techniques may also be employed for device to device communication on a sidelink channel of the network or relay-mediated communication.

For further illustration, above, various examples have been described with respect to overheating events triggered by MIMO communication. However, overheating events may be triggered at least partially also by other influencing factors, e.g., environmental conditions, workload imposed on circuitry due to applications, etc.. The particular reason or mix of reasons for triggering an overheating is not germane for the techniques described herein. Generally, the techniques described herein can be used to tailor the workload imposed on the UE by communicating data and, as such, to controlling the temperature at the UE. Therefore, the particular reason for an overheating event may be of subordinate relevance.

Furthermore, various techniques of closed-loop control of the temperature at the UE have been described in the context of an overheating event. However, generally, closed-loop control of the temperature may not be bound to an overheating event. Closed-loop control of the temperature at the UE could also commence if no overheating event has been detected, but if rather stabilization of the temperature at a set temperature is desired for some other reasons.

For further illustration, various definitions of overheating events are conceivable. For example, an overheating event may be defined with respect to the temperature exceeding a threshold; and resolving once the temperature falls below the threshold or below a further threshold defined with a safety margin with respect to the threshold. The overheating event may be defined with a temporal component, e.g., if the temperature crosses a threshold an remains above the threshold for a certain latency duration. Likewise, the resolving of the overheating event may be defined based on a latency duration of the temperature falling below a threshold. The overheating event may also be defined based on a rate of change of the temperature. For example, if the rate of change of the temperature exceeds a threshold, the overheating event may occur. Again, certain latency may be taken into account.

For still further illustration, above, various examples have been described in which the UL control signal is indicative of a threshold data rate. Threshold data rate may refer to the possibility of implementing the data rate at the threshold data rate or below. As such, the threshold data rate may also be referred to as set data rate or simply data rate, depending on the terminology used. For example, if a transmit buffer includes data queued for transmission, then the actual data rate may equal the threshold data rate and the threshold data rate may consequently be simply referred to as data rate.

For still further illustration, various examples have been described in which the threshold data rate is set below a maximum data rate supported by the parameters of the protocol stack. However, in some examples, the protocol stack may be appropriately configured such that the threshold data rate can equal the threshold data rate.

Claim 1:
A method, comprising:
- communicating, on a wireless link (<NUM>) between a network node (<NUM>) and a communication device (<NUM>), first data (<NUM>) at a first data rate (<NUM>, <NUM>-<NUM>, <NUM>-<NUM>),
- communicating, on the wireless link (<NUM>), at least one uplink control signal (<NUM>) associated with an overheating event (<NUM>) at the communication device (<NUM>), and
- in response to said communicating of the at least one uplink control signal (<NUM>): communicating, on the wireless link (<NUM>), second data (<NUM>) at a second data rate (<NUM>, <NUM>-<NUM>, <NUM>-<NUM>),
wherein the second data rate (<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) is different from the first data rate (<NUM>, <NUM>-<NUM>, <NUM>-<NUM>),
wherein the uplink control signal (<NUM>) is native to the Layer <NUM> or the Layer <NUM> of a communication protocol stack of the wireless link (<NUM>),
wherein the at least one uplink control signal (<NUM>) comprises a sequence (<NUM>) of uplink control signals (<NUM>),
wherein the method further comprises:
- communicating an uplink control message (<NUM>) indicative of the overheating event (<NUM>),
- triggering said communicating of the sequence (<NUM>) of uplink control signals (<NUM>) in response to said communicating of the uplink control message (<NUM>);
wherein the uplink control message (<NUM>) is native to a higher layer of a communication protocol stack of the wireless link (<NUM>) if compared to the native layer of the at least one uplink control signal (<NUM>).