WO2020132867A1

WO2020132867A1 - Thermal management in a wireless device

Info

Publication number: WO2020132867A1
Application number: PCT/CN2018/123492
Authority: WO
Inventors: Kuan Mao XU; Taotao CHEN; Jincheng WEI
Original assignee: Qualcomm Incorporated
Priority date: 2018-12-25
Filing date: 2018-12-25
Publication date: 2020-07-02

Abstract

In certain aspects, a method for a transceiver frame duty cycle search in a wireless device comprises: in a convergence mode, periodically monitoring a temperature in a first selected time interval; exiting the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold; updating an upper bound to an existing frame duty cycle if the temperature is higher than a target high or updating a lower bound to the existing frame duty cycle ifthe temperature is lower than a target low; and placing the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound ifthe temperature is higher than the target high or the temperature is lower than the target low.

Description

THERMAL MANAGEMENT IN A WIRELESS DEVICE

BACKGROUND Field

Aspects of the present disclosure relate to thermal management, and more particularly, to method and system for a transceiver thermal management in a wireless device.

Background

Cellular and wireless communication technologies have seen explosive growth over the past several years. This growth has been fueled by better communications hardware, larger networks, and more reliable protocols. Wireless service providers are now able to offer their customers an ever-expanding array of features and services, and provide users with unprecedented levels of access to information, resources, and communications. To keep pace with these service enhancements, wireless devices (e.g., cellular phones, tablets, laptops, etc. ) have become faster and more powerful than ever, and now commonly include multiple processors, system-on-chips (SoCs) , memories, and other resources (e.g., power rails, etc. ) that support high-speed communications and allow device users to execute complex and power intensive software applications on their wireless devices.

While the performance demands of wireless devices are increasing, device users expect to maintain certain levels of responsiveness, battery life, and surface temperature on their wireless devices. Maintaining these expected levels of performance on a wireless device may result in increased power consumption on the wireless device, which if not controlled may increase the surface temperature of the device to an uncomfortable or unsafe degree. Thus, it is important to implement effective power and thermal management solutions that balance the performance and thermal requirement.

SUMMARY

The following presents a simplified summary of one or more implementations to provide a basic understanding of such implementations. This summary is not an extensive overview of all contemplated implementations, and is intended to neither identify key nor critical elements of all implementations nor delineate the scope of any or all implementations. The sole purpose of the summary is to present concepts relate to one or more implementations in a simplified form as a prelude to a more detailed description that is presented later.

In one aspect, a method for a transceiver frame duty cycle search in a wireless device comprises: in a convergence mode, periodically monitoring a temperature in a first selected time interval; exiting the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold; updating an upper bound to an existing frame duty cycle if the temperature is higher than a target high or updating a lower bound to the existing frame duty cycle if the temperature is lower than a target low; and placing the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound if the temperature is higher than the target high or the temperature is lower than the target low.

In another aspect, an apparatus comprises a transceiver; and a thermal controller configured to, in a convergence mode, periodically monitor a temperature in a first selected time interval; exit the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold; update an upper bound to an existing frame duty cycle if the temperature is higher than a target high or update a lower bound to the existing frame duty cycle if the temperature is lower than a target low; and place the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound if the temperature is higher than the target high or the temperature is lower than the target low.

In another aspect, a non-transitory computer readable medium storing a program causing a system to execute a transceiver frame duty cycle search, the search comprises, in a convergence mode, periodically monitoring a temperature in a first selected time interval; exiting the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold; updating an upper bound to an existing frame duty cycle if the temperature is higher than a target high or updating a lower bound to the existing frame duty cycle if the temperature is lower than a target low; and placing the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound if the temperature is higher than the target high or the temperature is lower than the target low.

To accomplish the foregoing and related ends, one or more implementations include the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more implementations. These aspects are indicative, however, of but a few of the various ways in which the principles of various implementations may be employed and the described implementations are intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary transceiver frame duty cycle determination according to certain aspects of the present disclosure.

FIG. 2 illustrates another exemplary transceiver frame duty cycle determination according to certain aspects of the present disclosure.

FIG. 3 illustrates an exemplary device employing dichotomy search for a transceiver frame duty cycle according to certain aspects of the present disclosure.

FIG. 4 illustrates an exemplary dichotomy search method for a transceiver frame duty cycle in a normal operation mode according to certain aspects of the present disclosureFIG. 5 illustrate an exemplary dichotomy search method for a transceiver frame duty cycle in a convergence mode according to certain aspects of the present disclosure.

FIG. 6 illustrates an exemplary method for updating upper and/or lower bound in a convergence mode according to certain aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended drawings, is intended as a description of various aspects and is not intended to represent the only aspects in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing an understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts Generally, components and circuitry within a wireless device generate heat or thermal energy, which at excessive levels may be detrimental to the wireless device and uncomfortable or even injurious to users. The amount of thermal energy that is generated may vary depending upon the operating conditions and computing activities. For example, in an instance in which a wireless device is wirelessly transmitting data for a sustained time period at a high power-level, the transceiver may generate a potentially detrimental amount of thermal energy. In addition, processors within the wireless device may generate a potentially detrimental amount thermal energy when the processing burden is high.

Wireless devices have been configured with thermal management solutions or policies to ensure the temperature of wireless devices do not reach unsafe or uncomfortable levels, as well as to avoid operating components at temperatures that may shorten the operating life of the device. In many operating situations, the central processing unit (CPU) and associated components is a primary heat generator, so conventional thermal management policies include power management of such components (e.g., controlling the CPU clock frequency) . However, new communication protocols and systems, including 5G, new WiFi protocol, may result in changes in thermal characteristics and heat generation of wireless devices in ways that may render conventional thermal management policies unsuitable when certain communication activities are underway. Such conditions are anticipated when 5G or WiFi communication components are dominating device activities.

For a situation where the communication components are dominating thermal generator, it is effective to decrease the temperature by decreasing the transceiver frame duty cycle, which also enables the power amplifier to stay off for longer time. One method to find a good transceiver frame duty cycle is a step-control algorithm. The algorithm designates several temperature ranges, each maps to a frame duty cycle. The transceiver will operate at a certain duty cycle to mitigate the temperature when the monitored temperature is in one of these ranges based on the predetermined temperature frame duty cycle mapping. However, the step-control algorithm may lead the transceiver to switch frequently between different duty cycles and it is necessary to tune the mapping differently for a different design. Therefore, it is beneficially to have a method and system for effectively finding a stable frame duty cycle for a transceiver to meet the thermal requirement while maintaining high transceiver frame duty cycle.

FIG. 1 illustrates an exemplary transceiver frame duty cycle determination according to certain aspects of the present disclosure. The x-axis is the time and the y-axis is the temperature. The line 100 shows the temperature change over the time. The temperature is monitored periodically with a predetermined time interval, such as time periods T1, T2, T3, .... The transceiver frame duty cycle is updated according to the temperature. As the transceiver frame duty cycle increases or decreases, the power consumption increases or decreases accordingly. The increase or decrease of the power consumption, in turn, increases or decreases the temperature.

The transceiver may operate in two modes: a normal operation mode and a convergence mode. In the normal operation mode, the temperature is within a predetermined range and the transceiver may operate in a stable frame duty cycle. For example, the predetermined temperature range may be between a temperature low threshold 102 and a temperature high threshold 104. If the temperature is below the temperature low threshold 102, there is sufficient thermal budge for the transceiver to be more active and the transceiver frame duty cycle may be increased. If the temperature is higher than the temperature high threshold 104, the thermal budget is exceeded, the transceiver activity should be reduced to lower down the power consumption, and the transceiver frame duty cycle should be decreased. Between the temperature low threshold 102 and the temperature high threshold 104, the transceiver frame duty cycle is kept unchanged. The predetermined temperature range may be large enough so that the transceiver frame duty cycle would not be changed too often to affect the system stability and performance.

When the temperature is above the temperature high threshold 104, the transceiver enters the convergence mode. In the convergence mode, the system searches a new frame duty cycle for the transceiver in order to meet the thermal budget. This is done by searching a transceiver frame duty cycle that would settle the temperature within a target range. The target range is bounded by a target low 106 and a target high 108.

In the convergence mode, the new transceiver frame duty cycle is identified through a dichotomy search. Two parameters are introduced: an upper bound and a lower bound. The upper bound and the lower bound define the range where the new frame duty cycle is to be searched. If the temperature is too high, implying the existing transceiver frame duty cycle is too high and the new transceiver frame duty cycle should not be any higher. Therefore, the upper bound is updated to the existing transceiver frame duty cycle. If the temperature is too low, implying the existing transceiver frame duty cycle is too low and the new transceiver frame duty cycle should not be any lower. Therefore, the lower bound is then updated to the existing transceiver frame duty cycle. In addition, a new transceiver frame duty cycle is selected to be something between the lower bound and the upper bound, e.g., the average of the upper bound and the lower bound. The process is repeated to settle the temperature to be within the target range.

FIG. 1 illustrates two time periods where the transceiver may be at the normal operation mode: time period T1 and time period T8. At the beginning of the time period T1, the temperature is lower than the temperature low threshold 102. As time goes by, the temperature may continue to rise due to power consumption. If the temperature finally exceeds the temperature high threshold 104, as happens at the beginning of time period T2, the transceiver enters a convergence mode, where it looks for a new frame duty cycle.

The transceiver is in the convergence mode during the time periods T2-T7. At the start of the frame duty cycle search, the upper bound for the transceiver frame duty cycle can be 100%and lower bound can be 0%. At the beginning of time period T2, the temperature is not within the target range. It is too high. The temperature is higher than the target high 108, therefore, the upper bound should be updated, which is still 100%. The new transceiver frame duty cycle is thus set to a number between the lower bound 0%and the upper bound 100%, e.g., the average of the upper bound 100%and the lower bound 0%, which is 50%in this example.

With the reduced transceiver frame duty cycle (e.g., 50%) , the temperature decreases over time. At the beginning of the time period T3, the temperature is lower than the target low 106, indicating that the transceiver frame duty cycle can be larger. The lower bound is thus set at 50%, and the new transceiver frame duty cycle is set to be a number between 50%and 100%, e.g., 75%. Similarly, at the beginning of the time period T4, the new transceiver frame duty cycle is set to be e.g., 62.5%and the upper bound is updated to be 75%. TABLE 1 summarizes the exemplary parameter update over the time periods.

TABLE 1

By the time period T6, the temperature has reaches the target range. Therefore, after time period T6, the transceiver frame duty cycle is settled, e.g., at 65.625%. The temperature is continuously monitored. If the temperature is out of the target range again, the new frame duty cycle may be found.

The temperature high threshold, the temperature low threshold, the target low, the target high, the upper bound, and the lower bound may be predetermined. Their values may be adjusted depending on certain operation modes of the wireless device. The values may be initialized during the beginning of the search or during the wireless device power up or other suitable moments.

The time intervals for the normal operation mode may be the same as or different from the one in the convergence mode. For example, there may be a first selected time interval for the convergence mode and a second selected time interval for the normal operation mode. A longer time interval may be used in the normal operation mode to achieve a stable system, such that the second selected time interval is longer than the first selected time interval.

The method in FIG. 1 assumes that the time interval is long enough that the temperature approaches a stable point after each new transceiver frame duty cycle. However, if the time interval is too long, it may take too long to adjust the transceiver frame duty cycle, which may degrade the performance and increase the risk of thermal runaway.

FIG. 2 illustrates another exemplary transceiver frame duty cycle determination according to certain aspects of the present disclosure. The x-axis is the time and the y-axis is the temperature. The temperature line 200 shows the temperature change over the time. The transceiver has a temperature low threshold 202, a temperature high threshold 204, a target low 206, and a target high 208. Over the time period T2, the temperature continues to drop. Given sufficient time, the temperature will follow dash line 212, which means it takes more than one time interval for the temperature to settle to a stable point. If the time interval is sufficient long, the system may find that the temperature is settled to a point below the target low. However, since the time interval is not long enough, at the beginning of the time period T3, the monitored temperature is still above the target high 208, causing the transceiver frame duty cycle to adjust lower to 25%and the upper bound to 50%. The upper bound is even lower than the final transceiver frame duty cycle should be. As a result, by the dichotomy search of FIG. 1, the transceiver frame duty cycle will not reach the desired level.

To address the issue, in FIG. 2, a duty cycle adjustment is introduced. If the temperature is continuously dropping, like line 214, the lower bound is continuously increases for a few time intervals, e.g., 2 time intervals, this is an indication that the upper bound may be too low. At time period T4, even with lower bound increasing to 25%, the new transceiver frame duty cycle is only 37.5%without adjustment. If the same algorithm continues, at time period T5, the lower bound will be 37.5%and the upper bound will still be 50%, and the new transceiver frame duty cycle will be 43.75%, a little bit higher, but not high enough. The lower bound may be further increased to approach the upper bound, but the new frame duty cycle will not exceed the upper bound, which is not updated. When the system detects that the lower bound has been continuously updated for a predetermined number of time intervals, for example, 2 times in 2 time intervals or 3 times in 3 intervals, or the upper bound and lower bound is within a predefined range, such as 25%and the temperature is still lower than the target low 206, it realizes that the problems may lie in insufficient long interval time and the upper bound needs to be adjusted, too. Therefore, at time period T5, the upper bound is increased by an adjustment upper amount, an amount of the duty cycle increase for the upper bound, such as 25%, to increase the upper bound to 75%. The new transceiver frame duty cycle, therefore, is updated to, e.g., the average of the lower bound (37.5%) and the upper bound (75%) , which is 56.25%. The temperature line 200 thus goes up as line 216, and not continue to decrease as line 218. At time period T6, the transceiver frame duty cycle is then updated to 65.625%and the system reaches a stable point thereafter. TABLE 2 summarizes the exemplary parameter update over the time periods with adjustment.

TABLE 2

Similarly, if the upper bound has been continuously updated for a predetermined time intervals, such as 2 times, or the upper bound and lower bound is within a predefined range, such as 25%and the temperature is still higher than the target high 208. then the lower bound is further decreased by an adjustment lower amount, such as 25%. The adjustment upper amount and the adjustment lower amount may be the same or different.

The parameters used in FIGS. 1 and 2, such as temperature high threshold, the temperature low threshold, the target low, the target high, the upper bound, the lower bound, the adjustment lower amount, and/or the adjustment upper amount, may be predetermined. Their values may be adjusted depending on certain operation modes of the wireless device. The values may be initialized during the beginning of the search or during the wireless device power up or other suitable moments. To maintain system stability and reduce unnecessary frame duty cycle search, the temperature high threshold may be set to be higher than the target high and the temperature low threshold may be set to be lower than the target low.

When the device is initially powered on, the device is generally relatively cold, the temperature is generally lower than the temperature

low threshold

102 or 202. It is generally in the normal operation mode. The device temperature goes up as the activity goes up. When the temperature exceeds the temperature

high threshold

104 or 204, the transceiver enters the convergence mode to find an appropriate new frame duty cycle. The transceiver may stay in the convergence mode to maintain the target temperature range. However, the wireless device may be in an idle state and the transceiver may not receive or transmit any data for a while. The temperature may drop down regardless of the frame duty cycle, even at 100%. When the temperature drops below the temperature

low threshold

102 or 202, the transceiver exits the convergence mode and back to the normal operation mode, such as in time period T8 in both FIGS. 1 and 2.

FIG. 3 illustrates an exemplary device employing dichotomy search for a transceiver frame duty cycle according to certain aspects of the present disclosure. The device 300 comprises, for example, a modem processor 302, a power management unit 304, a memory 306, a transceiver module 308, other processors 310, and interconnection/bus 314 for linking the components. The transceiver module 308 may comprise one or more transceivers, such as transceiver A 308A and transceiver B 308B. The transceivers may be used for cellular communication, or WiFi, Bluetooth, position location, etc. In addition, the device 300 may comprise

multiple temperature sensors

312, 322, 328. The temperature sensors may be standalone, such as the temperature sensor (s) 312. It may be part of other components, such as the temperature sensor (s) 322 inside the modem processor 302, the temperature sensor (s) 328 inside the transceiver module 308. There may be more temperature sensors and the temperature sensors may be in other locations. There are other components that are not shown, such as power amplifier (s) etc.

One or more temperature sensors may be used to monitor the temperature of the transceiver A 308A or the transceiver B 308B or the transceiver module 308. The temperature sensors may be one inside the transceiver module 308, such as the temperature sensor (s) 328. The temperature sensors may be outside of the transceiver module 308 but in its proximity.

A thermal controller (not shown) is configured to perform the search of the transceiver frame duty cycle. The thermal controller may be a hardware, software, firmware, or any combinations thereof. It could be a hardware module inside the transceiver itself, such as a state machine or a microcontroller with embedded code. It could be done by a processor, such as by the modem processor 302 or any of the additional other processors 310, or by a combination thereof, with the software in the memory 306 or other suitable mediums.

FIG. 4 illustrates an exemplary dichotomy search method 400 for a transceiver frame duty cycle in a normal operation mode according to certain aspects of the present disclosure. At 402, the temperature is monitored periodically at a selected time interval. At 404, enter a convergence mode if the temperature is higher than a temperature high threshold.

FIG. 5 illustrate an exemplary dichotomy search method 500 for a transceiver frame duty cycle in a convergence mode according to certain aspects of the present disclosure. At 502, the temperature is monitored periodically at a selected time interval. The selected time interval may be the same as or different from the time interval in the method 400. At 504, the temperature is monitored against the temperature low threshold. If the temperature is lower than the temperature low threshold, it implies that the transceiver has sufficient thermal budget for any frame duty cycle. Thus, at 512, the transceiver exits the convergence mode and back to the normal operation mode. At 506, the temperature is monitored against the target range. If the temperature is within the target range, the search is completed, and the temperature is continuously monitored. If the temperature is out of the target range, at 508, update the upper bound to an existing frame duty cycle if the temperature is higher than the target high or update the lower bound to the existing frame duty cycle if the temperature is lower than the target low. In addition, at 510, the transceiver is placed from an existing frame duty cycle to a new frame duty cycle that is between an upper bound and a lower bound, such as the average of the upper bound and the lower bound.

FIG. 6 illustrates an exemplary method 600 for updating upper and/or lower bound in a convergence mode according to certain aspects of the present disclosure. The method 600 is a further improvement to 508, where the upper or lower bound is updated. In addition to actions taken in 508, at 602, a monitor is performed if the upper bound has been continuously updated for a predetermined time intervals, such as 2 times, or the upper bound and lower bound are within a predefined range, e.g., 25%, and the temperature is still higher than the target high. If that is true, the lower bound is further decreased by an adjustment lower amount, such as 25%. Otherwise, a monitor is performed if the lower bound has been continuously updated for a predetermined times, such as 2 times, or the upper bound and lower bound are within a predefined range, e.g., 25%, and the temperature is still lower than the target low. If that is true, the upper bound is further increased by an adjustment upper amount, such as 25%. The adjustment lower amount and the adjustment upper amount may be the same or may be different.

For the methods shown in FIGS. 4-6, the temperature high threshold, the temperature low threshold, the target low, the target high, the upper bound, the lower bound, the adjustment lower amount, and/or the adjustment upper amount may be predetermined. Their values may be adjusted depending on certain operation modes of the wireless device. The values may be initialized during the beginning of the search or during the wireless device power up or other suitable moments.

The methods illustrated in FIGS. 4-6 may be performed by a thermal controller. The thermal controller may be a hardware, software, firmware, or any combinations thereof. For example, it could be a hardware module inside the transceiver itself, such as a state machine or a microcontroller with embedded code. It could be done by a processor with a software in the memory or other suitable mediums.

The flow in FIGS. 4-6 does not imply the order, it is for illustration purpose only and one of possible embodiments. Some steps may be performed in different sequences without affecting the results. For example, 506 may be done before 504, 606 and 608 may be done before 602 and 604. Some steps may be skipped as well.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method for a transceiver frame duty cycle search in a wireless device, comprising:

in a convergence mode,

periodically monitoring a temperature in a first selected time interval;

exiting the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold;

updating an upper bound to an existing frame duty cycle if the temperature is higher than a target high or updating a lower bound to the existing frame duty cycle if the temperature is lower than a target low; and

placing the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound if the temperature is higher than the target high or the temperature is lower than the target low.
The method of claim 1, further comprising:

in the normal operation mode,

periodically monitoring the temperature in a second selected time interval; and

entering the convergence mode if the temperature is higher than a temperature high threshold.
The method of claim 2, wherein the temperature high threshold is higher than the target high and the temperature low threshold is lower than the target low.
The method of claim 2, wherein the first selected time interval equals the second selected time interval.
The method of claim 2, further comprising initializing the temperature high threshold, the temperature low threshold, the target low, the target high, the upper bound, and the lower bound.
The method of claim 5, wherein the upper bound is initialized to be 100%and the lower bound is initialized to be 0%.
The method of claim 1, wherein the new frame duty cycle is an average of the upper bound and the lower bound.
The method of claim 1, further comprising:

in the convergence mode,

increasing the upper bound by an adjustment upper amount if the upper bound and the lower bound are within a predefined range and the temperature is lower than the target low; and

decreasing the lower bound by an adjustment lower amount if the upper bound and the lower bound are within the predefined range and the temperature is higher than the target high.
The method of claim 8, wherein the predefined range is 25%.
The method of claim 8, wherein the adjustment lower amount is 25%.
The method of claim 8, wherein the adjustment upper amount is 25%.
The method of claim 1, further comprising:

in the convergence mode,

increasing the upper bound by an adjustment upper amount if the lower bound is continuously updated for a predetermined number of time intervals; and

decreasing the lower bound by an adjustment lower amount if the upper bound is continuously updated for the predetermined number of time intervals.
An apparatus, comprising:

a transceiver; and

a thermal controller configured to:

in a convergence mode,

periodically monitor a temperature in a first selected time interval;

exit the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold;

update an upper bound to an existing frame duty cycle if the temperature is higher than a target high or update a lower bound to the existing frame duty cycle if the temperature is lower than a target low; and

place the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound if the temperature is higher than the target high or the temperature is lower than the target low.
The apparatus of claim 13, wherein the thermal controller is further configured to:

in the normal operation mode,

periodically monitor the temperature in a second selected time interval; and

enter the convergence mode if the temperature is higher than a temperature high threshold.
The apparatus of claim 14, wherein the temperature high threshold is higher than the target high and the temperature low threshold is lower than the target low.
The apparatus of claim 14, wherein the first selected time interval equals the second selected time interval.
The apparatus of claim 14, wherein the thermal controller is further configured to initialize the temperature high threshold, the temperature low threshold, the target low, the target high, the upper bound, and the lower bound.
The apparatus of claim 17, wherein the upper bound is initialized to be 100%and the lower bound is initialized to be 0%.
The apparatus of claim 13, wherein the new frame duty cycle is an average of the upper bound and the lower bound.
The apparatus of claim 13, wherein the thermal controller is further configured to:

in the convergence mode,

increase the upper bound by an adjustment upper amount if the upper bound and the lower bound are within a predefined range and the temperature is lower than the target low; and

decrease the lower bound by an adjustment lower amount if the upper bound and the lower bound are within the predefined range and the temperature is higher than the target high.
The apparatus of claim 20, wherein the predefined range is 25%.
The apparatus of claim 20, wherein the adjustment lower amount is 25%.
The apparatus of claim 20, wherein the adjustment upper amount is 25%.
A non-transitory computer readable medium storing a program causing a system to execute a transceiver frame duty cycle search, the search comprising:

in a convergence mode,

periodically monitoring a temperature in a first selected time interval;

exiting the convergence mode and enter a normal operation mode if the temperature is lower than a temperature low threshold;

updating an upper bound to an existing frame duty cycle if the temperature is higher than a target high or updating a lower bound to the existing frame duty cycle if the temperature is lower than a target low; and

placing the transceiver from the existing frame duty cycle to a new frame duty cycle that is between the upper bound and the lower bound if the temperature is higher than the target high or the temperature is lower than the target low.
The non-transitory computer readable medium of claim 24, wherein the search further comprise:

in the normal operation mode,

periodically monitoring the temperature in a second selected time interval; and

entering the convergence mode if the temperature is higher than a temperature high threshold.
The non-transitory computer readable medium of claim 25, wherein the search further comprises initializing the temperature high threshold, the temperature low threshold, the target low, the target high, the upper bound, and the lower bound.
The non-transitory computer readable medium of claim 26, wherein the upper bound is initialized to be 100%and the lower bound is initialized to be 0%.
The non-transitory computer readable medium of claim 24, wherein the new frame duty cycle is an average of the upper bound and the lower bound.
The non-transitory computer readable medium of claim 24, wherein the search further comprises:

in the convergence mode,

increasing the upper bound by an adjustment upper amount if the upper bound and the lower bound are within a predefined range and the temperature is lower than the target low; and

decreasing the lower bound by an adjustment lower amount if the upper bound and the lower bound are within the predefined range and the temperature is higher than the target high.
The non-transitory computer readable medium of claim 29, wherein the predefined range is 25%.