JP7315393B2 - Wireless terminal, its uplink transmission control method, and program - Google Patents

Description

The present invention relates to a radio terminal, its uplink transmission control method, and a program.

3GPP (Third Generation Partnership Project) standardization specifications define Carrier Aggregation (CA) for bundling a plurality of Component Carriers (CC) for communication. In carrier aggregation according to LTE (Long Term Evolution) up to 3GPP Release 10, one eNB
The throughput is improved by performing simultaneous communication using multiple component carriers operated within (evolved Node B: base station). 3GPP Release 12 has introduced a dual connectivity (DC) technology that extends intra-eNB carrier aggregation and performs simultaneous communication using component carriers operated in different eNBs. DC corresponds to carrier aggregation between base stations (Inter-eNB Carrier Aggregation), and is expected to further improve throughput.

In 5G (fifth generation mobile communication) defined by 3GPP Release 15, a core network for 4G (EPC: Evolved Packet Core) is standardized to perform communication while performing simultaneous transmission and reception between a base station for 4G (fourth generation mobile communication) and a base station for 5G. A wireless terminal (User Equipment: UE) compatible with such a network configuration includes a wireless communication unit for 5G communication and a wireless communication unit for 4G communication, and performs uplink communication only with the 5G wireless communication unit of 5G and 4G while the data amount (storage amount) of the buffer that stores (stores) data for uplink transmission does not exceed the threshold notified from the base station (for 5G). On the other hand, when the threshold is exceeded, simultaneous transmission using both 5G and 4G wireless communication units is performed (for example, Patent Document 1).

JP 2017-163599 A

However, the simultaneous communication of 5G and 4G described above is a communication mode corresponding to network operation in the transitional period until the communication infrastructure shifts from 4G to 5G. For this reason, the load on the wireless terminal is large, and it is thought that the temperature of the wireless terminal will rise rapidly and the remaining battery level will drop rapidly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wireless terminal, an uplink transmission control method thereof, and a program capable of suppressing temperature rise and remaining battery level decrease.

One embodiment of the present invention is a wireless terminal that has a buffer for accumulating data to be transmitted to an uplink, and performs uplink transmission using a first wireless system when a retention amount indicating the amount of data retained in the buffer does not exceed a threshold, and performs uplink transmission using both the first wireless system and a second wireless system different from the first wireless system when the retention amount exceeds the threshold.
The wireless terminal supplies data to the buffer, indicates execution of uplink transmission using both the first wireless system and the second wireless system, detects a sudden rise in the temperature of a wireless unit used for the uplink transmission, and, after detecting the sudden rise in the temperature of the wireless unit, sets an upper limit on the amount of data supplied to the buffer when the temperature in the wireless terminal exceeds an upper limit threshold or the remaining battery level of the wireless terminal falls below a lower limit threshold. Characterized by

The present invention may also be an uplink transmission control method for a wireless terminal, a program, and a recording medium recording the program, which have the same characteristics as the wireless terminal.

According to the embodiment of the present invention, it is possible to suppress the temperature rise and the remaining battery level decrease.

FIG. 1 shows an example of a network system to which a wireless terminal according to an embodiment is applied. FIG. 2 is an explanatory diagram showing interactions between a wireless terminal and a base station for uplink communication. FIG. 3A shows an example of single transmission and FIG. 3B shows an example of dual transmission. FIG. 4 shows the flow of UL data (packets) in dual transmission. FIG. 5 shows a configuration example of a radio terminal (UE). FIG. 6 schematically shows the configuration of a wireless terminal. FIG. 7 shows the relationship between the amount of UL data supplied to the PDCP layer (buffer retention amount), time, and the threshold. FIG. 8 shows a graph showing changes in CPU temperature and a graph showing changes in remaining battery capacity. FIG. 9 is a flowchart illustrating a processing example of a dual connectivity control unit; FIG. 10 is a flowchart illustrating a processing example of a dual connectivity control unit; FIG. 11 shows an example in which the buffer threshold differs depending on the base station. FIG. 12 shows the transition of the CPU temperature and the transition of the remaining battery capacity in the base station A. FIG. FIG. 13 shows the transition of the CPU temperature and the transition of the remaining battery capacity in the base station B. FIG.

In the prior art, in a terminal that supports dual connectivity (DC), simultaneous communication (also called dual transmission) with 4 base stations and 5G base stations when the amount of uplink (UL) data has increased. The heat of the terminal and the internal state of the battery are not considered.

Real-time streaming, which is considered to be one of the main services of 5G, performs encoding processing to compress data while shooting high-definition video with the terminal's camera. Then, when a large amount of transmission data for transmission is generated, simultaneous transmission is performed using a 4G transmitter and a 5G transmitter, and data is continuously sent to a predetermined destination (for example, a content distribution server).

However, since simultaneous transmission places a heavy load on the terminal, if the simultaneous transmission operation continues, the temperature inside the terminal rises more rapidly than in the case of single communication using 4G or 5G (also called single transmission), and there is a risk that the operation of the terminal will fall into an abnormal state. Simultaneous communication also consumes more battery power than single communication, and it is necessary to consider operation even when the remaining battery power is low. Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the embodiment is an example, and the present invention is not limited to the configuration of the embodiment.

<Network configuration example>
FIG. 1 shows an example of a network system to which a wireless terminal according to an embodiment is applied. In FIG. 1 , the network system has a macrocell base station 1A (base station 1A) that forms a macrocell 1 and a small cell base station 2A that forms a small cell 2 within the macrocell 1 .

The base station 1A is a base station compatible with 4G, and the base station 2A is a base station compatible with 5G. The base station 1A is connected to the EPC 5, which is a core network for 4G, for both the control plane (C-plane) and user plane (U-plane). Base station 2A may be connected to EPC via base station 1A for the C-plane and directly to EPC 5 for the U-plane. 5G is an example of a "first wireless system (wireless communication standard)", and 4G is an example of a "second wireless system (wireless communication standard)".

A wireless terminal (UE) 10 is a terminal having both 4G communication functions and 5G communication functions. The UE 10 can perform communication by connecting to the small cell (base station 2A) and communication by connecting to the macrocell (base station 1A) individually or simultaneously (in parallel). As services using 5G communication, for example, low-delay data transmission/reception, real-time streaming distribution, etc., particularly uplink communication services for transmitting large amounts of data from UEs are being considered.

FIG. 2 is an illustration showing interactions between a UE and a base station (BS) for uplink communication. UE 10 may behave as the UE in FIG. On the other hand, each of base stations 1A and 2A can behave as a BS in FIG.

In FIG. 2, when the UE generates data for uplink communication (UE→BS direction communication), that is, data to be transmitted to the BS using the uplink (also referred to as UL data), the UL data is stored in a buffer provided by the UE. The UE sends a message called a Scheduling Request (SR) to the BS. SR is a message requesting allocation of radio resources for transmitting UL data.

Upon receiving the SR, the BS allocates resources for UL data, and sends a message indicating the allocation result (UL transmission permission) (called a UL grant, hereinafter simply grant) to the UE via downlink communication (downlink, communication in the BS→UE direction). When the UE receives the grant, it uses the resources (time and frequency band) permitted for use in the grant, UL data, and a message called a buffer status report (Buffer Status Report: BLR (buffer amount report)) to the BS. BSR indicates the amount of UL data retained in the buffer (retention amount). The BS determines a buffer retention threshold for the UE based on its own communication status (the number of UE connections, the amount of data transmitted and received), and transmits (notifies) it to the UE.

FIG. 3A shows an example of single transmission, and FIG. 3B shows an example of dual transmission. In FIG. 3A, the UE 10 performs UL communication only with the base station 2A out of the base station 1A (4G) and the base station 2A (5G) if the amount of retained data (data retention amount) in the buffer (UE buffer) storing the UL data in the UE 10 is less than a threshold. On the other hand, as shown in FIG. 3B, when the amount of data retained in the UE buffer reaches or exceeds the threshold, the UE performs parallel UL communication (dual transmission) with the base station 2A and the base station 1A. In dual transmission, the UE 10 transmits BSR and UL data to base station 1A (4G) and base station 2A (5G) respectively and receives buffer thresholds. In dual transmission, UL data is stored in a buffer for 4G and a buffer for 5G.

FIG. 4 shows the flow of UL data (packets) in dual transmission. In dual transmission, UL data (packets) are transmitted from the UE 10 to each of the base station 2A and the base station 1A. The packet received by the base station 2A is transferred to the base station 1A via the line between base stations (X2 interface), the original packet train is generated and transferred to the EPC 5. FIG.

Real-time streaming, which is considered to be one of the main services of 5G, performs encoding processing to compress data while shooting high-definition video with the terminal's camera. Then, when a large amount of transmission data for transmission is generated, simultaneous transmission is performed using a 4G transmitter and a 5G transmitter, and data is continuously sent to a predetermined destination (for example, a content distribution server).

However, dual transmission imposes a heavy load on wireless terminals. For this reason, if the dual transmission operation is continued, the temperature inside the terminal rises more rapidly than in the single transmission, and there is a risk that the wireless terminal will fall into an abnormal state. In addition, dual transmission consumes more battery power than single transmission, and operation in a low battery state should also be considered.

In the wireless terminal according to the embodiment, the threshold value of the buffer that determines whether the packet data convergence protocol (PDCP) layer can be divided is not changed in the wireless terminal, and the amount of UL data that flows into the PDCP layer from the Internet Protocol (IP) layer in the buffer is managed together with the temperature or remaining battery capacity in the wireless terminal to control dual transmission.

A wireless terminal according to the embodiment adjusts the amount of UL data supplied to the PDCP layer for dual transmission control. For this reason, it is preferable to know the PDCP layer buffer threshold for transitioning to the dual transmission state.

As a method of knowing the threshold, it is conceivable to have the PDCP layer notify the IP layer of the threshold of the retention amount of the buffer that divides the UL data in the PDCP layer. However, buffer thresholds are only part of the operating parameters in the protocol stack. Therefore, the threshold varies for each target base station to which the wireless terminal connects due to handover (H/O) or the like. Also, even if the PDCP layer divides the UL data and sends SR messages to different base stations, it is not always possible to obtain grants from each base station to kyify the UL transmission. Also, the buffer threshold varies depending on the status of the connected base station, regardless of the status of the wireless terminal. For this reason, it was not possible to know in advance when to change the threshold.

Based on the above circumstances, in the following embodiments, a radio terminal, an uplink transmission control method thereof, and a program that can suppress temperature rise of the UE 10 due to dual transmission, operation abnormalities, and a sudden decrease in remaining battery capacity will be described. Also, a wireless terminal, its uplink transmission control method, and a program capable of suppressing a decrease in transmission rate due to dual transmission control will be described.

FIG. 5 shows a configuration example of a radio terminal (UE). 5, UE 10 includes CPU 11, memory device 12, input device 13, output device 14, detection circuit 16, and baseband (BB) circuits 17A and 17B interconnected via bus B. FIG. The BB circuit 17A is connected to an RF (Radio Frequency) circuit 18A to form a radio section 20A for 5G communication. Also, the BB circuit 17B is connected to the RF circuit 18B to form a radio section 20B for 5G communication.

The UE 10 also has a battery 15 for supplying power for operation to each part of the UE 10 . A battery voltage indicating the remaining amount of the battery 15 is detected by the detection circuit 16 and notified to the CPU 11 via the bus B. FIG. The RF circuits 18A and 18B are provided with temperature sensors 19A and 19B, respectively, and the CPU 11 is notified of the temperatures of the RF circuits 18A and 18B. The CPU 11 is also provided with a temperature sensor 21 to measure the temperature of the CPU 11 . The temperature of the CPU 11 is used for processing in the CPU 11 .

The storage device 12 includes a main storage device and an auxiliary storage device. The main memory is, for example, RAM (Random Access Memory) or a combination of RAM and ROM (Read Only Memory). The main memory is used as a storage area for programs and data, a work area for the CPU 11, and a buffer area for communication data (for example, the buffer 23). Secondary storage is used to store programs and data. Auxiliary storage devices include hard disks, Solid State Drives (
SSD), EEPROM (Electrically Erasable Programmable Read-Only Memory),
Such as flash memory.

The input device 13 is used for inputting information. The input device 13 includes keys, buttons, touch panels, pointing devices, and the like. The input device 13 may also include an image or video input device such as a camera or scanner, or an audio input device such as a microphone. The output device 14 is used for outputting information and data. The output device 14 is, for example, a display device. Output device 14 may include an audio output device, such as a speaker.

The CPU 11 performs various processes by executing programs stored in the storage device 12 . The CPU 11 performs, for example, processing related to UL communication from the application layer to the IP layer, and stores UL data generated by the processing in, for example, a buffer 23 formed in a storage area of the storage device 12 . Buffer 23 may reside in a local memory connected to CPU 11 . The UL data stored in the buffer 23 is stored in the buffer 22A of the BB circuit 17A for 5G communication.

The BB circuit 17A converts the digital data (UL data) into an upstream baseband signal (BB signal) by digitally modulating it, or converts the BB signal into an analog signal as analog BB processing and sends it to the RF circuit 18A. The BB circuit 17A also performs a process of converting an analog signal received from the RF circuit 18A into a BB signal and a process of demodulating the BB signal to obtain downlink data.

The RF circuit 18A includes a duplexer as a component common to the uplink and downlink, and the duplexer is connected to the transmit and receive antennas. For the uplink direction, RF circuitry 18A includes an upconverter and a power amplifier (PA). The up-converter up-converts the analog signal (RF signal) from the BB circuit 17A to the frequency of radio waves. The PA amplifies the upconverted signal. The duplexer connects the amplified signal to a transmit/receive antenna, which radiates radio waves. The radiated radio waves are received by the base station 2A.

For the downlink direction, RF circuitry 18A includes a low noise amplifier (LNA) and a downconverter. A radio wave from a base station is input to the LNA via a duplexer and is amplified with low noise by the LNA. The low-noise amplified signal is down-converted to the frequency of an analog signal (RF signal) by a down-converter. The down-converted signal is input to the BB circuit.

The BB circuit 17B and the RF circuit 18B are the same as the BB circuit 17A and the RF circuit 18A in that they perform conversion between digital data and radio signals in the uplink and downlink directions, respectively, although there are differences in the modulation and demodulation methods between 4G and 5G. The BB circuits 17A and 17B are formed by, for example, integrated circuits such as DSP, FPGA, and ASIC, or a combination of two or more types of integrated circuits. Also, the RF circuits 18A and 18B are formed by electric/electronic circuits.

From the viewpoint of the protocol stack, the radio section 20A and the radio section 20B perform processing from the PDCP layer to the physical layer. With respect to PDCP layer processing, the BB circuit 17A includes a buffer 22A, described as an intra-UE buffer in the description of FIGS. 3A and 3B.

In the process related to the PDCP layer, when the UL data generated as a result of the process of the IP layer immediately above the PDCP layer is stored in the buffer 22A, the BB circuit 17A assumes that the UL data is generated, and transmits an SR message, receives a grant, and transmits UL data and BSR.

The radio unit 20A monitors a threshold for the amount of buffer retention received from the base station 2A, and when the threshold is exceeded, the radio units 20A and 20B start dual transmission. That is, the BB circuit 17A stores part of the UL data staying in the buffer 22A in the buffer 22B of the BB circuit 17B for 4G communication. Then, the BB circuit 22B starts PDCP layer processing in the radio section 20B. That is, it transmits an SR message to the base station 1A, receives a grant from the base station 1A, and transmits UL data and BSR staying in the buffer 22B. In this way, dual transmission, that is, 5G uplink communication by the radio unit 20A and 4G uplink communication by the radio unit 20B are performed simultaneously (parallel).

After that, when the amount of UL data retained in the buffer 22A falls below the threshold, the supply of UL data to the buffer 22B is stopped, UL communication using the radio section 20B is stopped, and the single transmission state is restored.

FIG. 6 is a diagram schematically showing the configuration of the radio terminal (UE 10).
4 schematically shows the processing related to the P layer. The CPU 11 operates as a dual connectivity (DC) control unit 101 by executing programs.

FIG. 7 shows the relationship between the amount of UL data supplied to the PDCP layer (buffer retention amount), time, and the threshold. Assuming that the transmission rate is constant, single transmission is performed in a range in which the amount of UL data supplied (retention amount) does not exceed the threshold notified from the base station 2A, and dual transmission is performed while the retention amount exceeds the threshold. Dual transmission loads the RF circuits 18A and 18B, causing the temperature of the RF circuits 18A and 18B to rise sharply. The DC control unit 101 detects a rapid temperature rise (rapid rise) as a dual transmission state.

FIG. 8 shows a graph showing changes in CPU temperature and a graph showing changes in remaining battery capacity. In the dual transmission state of the UE 10, the load on the CPU 11 increases, so the temperature of the CPU 11 increases due to heat generation. Since the temperature rise of the CPU 11 causes abnormal operation of the CPU 11 (and thus abnormal operation of the UE 10), the upper limit value of the CPU temperature is prepared as a threshold. Also, in the dual transmission state, the load on the CPU 11 is increased, so power consumption is greater than in the single transmission state. Therefore, a lower limit value (threshold value) of the remaining battery level is prepared.

Phenomenon 1 shown in FIG. 8 indicates a situation in which a transition from the single transmission state to the dual transmission state causes the load on the CPU 11 to rise, the temperature to rise, and the amount of decrease in the remaining battery capacity to increase. Phenomenon 2 shows a situation in which the amount of buffer 22A retained decreases, the single transmission state is entered, the load on the CPU 11 decreases, and the temperature drops. Phenomenon 2 indicates a situation in which the rate of decrease in the remaining battery capacity becomes moderate due to the decrease in the load on the CPU 11 . Phenomenon 3 shows a situation in which the temperature of the CPU 11 rises and the rate of decrease in the remaining battery capacity increases when the dual transmission state resumes.

Considering the characteristics shown in the graphs of FIGS. 6, 7 and 8, the DC control unit 101 performs the following processing. The DC control unit 101 (CPU 11) is an example of a "control unit".
(1) Temperature measurement The DC control unit 101 periodically samples (detects) the conditions of the temperature sensors 19A and 19B in the UE 10 when transmitting UL data. Temperature sensors 19A and 19B output signals indicating the temperature of RF circuits 18A and 18B. The RF circuits 18A, 18B are mounted within the housing of the UE 10, for example, on a board, but may be mounted by other mounting methods. The DC control unit 101 acquires information indicating the temperature of the RF circuits 18A and 18B from the temperature sensors 19A and 19B.

Note that the number of temperature sensors is not limited to two, and may be one or more. For example, only one of the temperature sensors 19A and 19B may be provided as long as a temperature that allows determination of dual transmission can be obtained. If the 4G RF circuit and the 5G RF circuit are formed in one chip or package, one temperature sensor may be sufficient. It is also possible to provide three or more temperature sensors and use an average value.

The temperature of the RF circuits 18A and 18B is continuously monitored, and if a steep slope (the amount of rise per unit time is greater than or equal to a threshold value) occurs, it is detected. The presence or absence of a steep slope is used to determine whether the current communication state is the dual transmission state or the single transmission state. When a steep slope (rapid rise) is detected, the current communication state is determined to be the dual transmission state.

The temperature sensor 21 is a temperature sensor built into the CPU 11, and the temperature measured by the temperature sensor 21 is used for comparison with a threshold for determining whether to maintain the continuation of the dual transmission state or stop the dual transmission state. Note that the temperature sensor 21 may be non-internal (external) as long as it can measure a CPU temperature that can be compared with a threshold value. The number of temperature sensors 21 may be two or more.

(2) Remaining Battery Level The DC control unit 101 periodically samples (detects) the conditions of the temperature sensors 19A and 19B in the UE 10 when transmitting UL data. As described with reference to FIG. 5, the voltage of battery 15 is detected by detection circuit 16 (FIG. 5) and input to DC control section 101 . The DC control unit 101 acquires the voltage as information indicating the remaining battery level.

The change speed of the remaining battery capacity is usually slower than the temperature change (increase/decrease). For this reason, the change in the remaining battery capacity is not used to determine whether it is in the dual transmission state, but is used for comparison with a threshold that limits the amount of data supplied to the buffer 22A.

(3) Simultaneous Transmission Determination The DC control unit 101 determines whether the amount of change per unit time in the temperatures measured by the temperature sensors 19A and 19B exceeds a threshold. If it is determined to exceed the threshold, it is determined to be in a dual transmission state. The threshold is stored in the storage device 12 or a storage device other than the storage device 12 and used by the DC controller 101 .

(4) Determining Whether or Not to Maintain Simultaneous Transmission The storage device 12 or a storage device other than the storage device 12 stores a threshold to be compared with the temperature of the CPU 11 and a threshold to be compared with the remaining battery capacity. The DC control unit 101 determines whether the temperature inside the UE 10 exceeds a threshold or whether the remaining battery level is below a threshold. A state in which the temperature inside the UE 10 is less than the threshold or a state in which the remaining battery level is greater than the threshold indicates that the dual transmission state can be maintained. On the other hand, a state in which the temperature inside the UE 10 is equal to or higher than the threshold or a state in which the remaining battery level is equal to or lower than the threshold indicates that the dual transmission state should be canceled (not maintained).

(5) Supply amount adjustment When it is determined that the temperature in the UE 10 is equal to or higher than the threshold value or the remaining battery level is equal to or lower than the threshold value in the simultaneous transmission maintenance determination, the DC control unit 101 sets the data amount (supply amount) to be supplied from the TCP/IP layer to the PDCP layer buffer 22A to a predetermined value in order to cancel the dual transmission state. The predetermined value is the amount of supply that is measured and stored before it is determined that the temperature inside the UE 10 is equal to or higher than the threshold or the remaining battery level is equal to or lower than the threshold. However, there may be cases where the supply amount is determined in advance based on experiments or empirical rules.

By setting the upper limit of the supply amount, the upper limit of the supply amount is determined. That is, since the amount of data supplied to the buffer 22A is limited, the retention amount of the buffer 22A eventually becomes equal to or less than the threshold notified from the base station, and the dual transmission state is released. Note that the UL data supplied to the buffer 22A is held in the buffer 23, for example.

Regarding the supply amount adjustment, the DC control unit 101 determines whether or not the UL data is real-time data (for example, stream data). For real-time data, a request to reduce the amount of data (a request to lower the image quality) is issued to the information source (camera, etc.). For UL data that does not have real-time characteristics, the priority of the order of supply is lowered so that UL data that has real-time characteristics is preferentially supplied to the buffer 22A.

9 and 10 are flowcharts showing an example of processing by the DC control unit 101. FIG. In this embodiment, an example in which the CPU 11 operates as the DC control unit 101 is shown, but a processor or an integrated circuit other than the CPU 11 may perform processing as the DC control unit 101 .

In S01, the DC control unit 101 determines whether the 5G service (UL transmission using the radio unit 20A for 5G) is in operation. This determination can be made, for example, by determining whether or not the UL data from the information source (input device 13, etc.) accumulated in the buffer 23 is supplied to the PDCP layer (buffer 22A). When it is determined that the 5G service is not in operation, the DC control unit 101 resets the UL data supply amount (S02) and returns the process to S01. On the other hand, when it is determined that the 5G service is in operation, the DC control unit 101 advances the process to S03.

In S03, the DC control unit 101 measures the RF temperature, CPU temperature, and remaining battery capacity. In S04, the DC control unit 101 determines whether or not the RF temperature is rapidly rising (that is, whether or not the temperature rise rate per unit time exceeds the threshold). If it is determined that the RF temperature has risen sharply, the process proceeds to S05; otherwise, the process proceeds to S06. In the process of S04, as the RF temperature, it may be determined whether at least one of the temperature of the RF circuit 18A and the temperature of the RF circuit 18B is rapidly rising, and the temperature of the RF circuit 18A and the temperature of the RF circuit 18B may be summarized by some method (average value) may be used as the RF temperature.

Proceeding to S05 means that the UE 10 has been determined to be in the dual transmission state. The DC control unit 101 stores the UL data supply amount at this time in the storage device 12 or a storage device other than the storage device 12 as the UL data supply amount at the time of dual transmission. After that, the process proceeds to S06.

In S06, the DC control unit 101 determines whether the CPU temperature acquired in S03 is equal to or higher than the CPU temperature threshold, or whether the remaining battery charge is equal to or lower than the remaining battery charge threshold. If it is determined that the CPU temperature is less than the threshold and the remaining battery capacity is greater than the threshold, the process proceeds to S07. On the other hand, if it is determined that the CPU temperature obtained in S03 is equal to or higher than the CPU temperature threshold or the remaining battery charge is equal to or lower than the remaining battery charge threshold, the process proceeds to S08.

When the process proceeds to S07, the DC control unit 101 operates in the normal operation mode. In other words, the DC control unit 101 supplies UL data to the PDCP layer without limiting the amount of UL data to be supplied, and causes single transmission or dual transmission to be performed. After the end of S07, the process returns to S01.

When the process proceeds to S08, the DC control unit 101 operates in the buffer supply amount upper limit mode. That is, the UL data supply amount per unit time stored in S05 is set as the upper limit of the supply amount to the PDCP layer, and the UL data is supplied to the PDCP layer within the range of this upper limit.

When the process proceeds to S09, the DC control unit 101 determines whether the amount of information source data (that is, the amount of UL data) sent from the information source (input device 13, etc.) exceeds the PDCP layer supply amount. For example, the DC control unit 101 determines whether the amount of UL data flowing (accumulated) into the buffer 23 per unit time (flow amount into the buffer 23) exceeds the supply amount per unit time of UL data supplied to the PDCP layer from the buffer 23 (PDCP supply amount). If it is determined that the amount of inflow into the buffer 23 exceeds the PDCP supply amount, the process proceeds to S10; otherwise, the process returns to S01.

When the process proceeds to S10, the DC control unit 101 refers to a list of application programs (apps) currently in operation (created on the storage device 12), and determines whether an application requiring real-time performance is in operation. If it is determined that an application that requires real-time performance (for example, an application that uploads a video stream) is in operation, the process proceeds to S11; otherwise, the process returns to S01.

When the process proceeds to S11, the DC control unit 101 requests the application to reduce the amount of information from the information source. For example, it requests a reduction in the resolution (frame size) of image data captured by an information source (for example, a camera). After the process of S11 is completed, the process returns to S01.

<Operation example>
As described above, the DC control unit 101 in the UE 10 periodically measures the RF temperature, CPU temperature, and remaining battery capacity (S03), and monitors rapid increases in the RF temperature (S04). After the start of UL transmission using 5G, as the amount of UL data increases, the steep rise in RF temperature increases the gradient (amount of rise per unit time) of temperature change (increase) of the RF circuits 18A and 18B. The DC controller 101 detects this temperature change as the implementation of dual transmission. The DC control unit 101 stores the UL data supply amount at the time of detecting the implementation of dual transmission. This UL data supply amount is recognized as the amount of data that triggers dual transmission.

The DC control unit 101 maintains a state in which the supply amount of UL data is not limited for a while even after entering the dual transmission state (loop of S01→S03→S04→S06→S07→S01). However, in S06, the DC control unit 101 monitors whether the CPU temperature measured in S03 is higher than the upper limit or lower than the lower limit of remaining battery capacity (S06).

When the CPU temperature exceeds the upper limit, or when the remaining battery level falls below the lower limit, an operation is performed to lower the temperature as early as possible. Therefore, the UL data supply amount stored when the RF temperature suddenly rises is set as the upper limit of the supply amount to the PDCP layer (S08). This causes the DC control unit 101 to , S01→S03→S04→S06→S08→S09→S01. In the buffer supply amount upper limit mode, the set UL data supply amount is maintained and is not updated until the buffer supply amount upper limit mode is canceled.

By setting the upper limit of the UL data supply amount to the PDCP layer, the UL data amount accumulated in the buffer 22A of the PDCP layer is reduced, and when it falls below the threshold notified from the base station, the dual transmission state is canceled and single transmission is performed.

By canceling the dual transmission state, the load on the CPU 11 is reduced and the CPU temperature is lowered. Then, in S06, when the CPU temperature falls below the upper limit threshold (or when the remaining battery level exceeds the lower limit threshold due to charging), the buffer supply amount upper limit mode transitions to the normal operation mode. In the normal operation mode, there is no upper limit on the amount of UL data supplied, and it becomes unlimited.

By controlling the dual transmission as described above, it is possible to avoid further temperature rise of the UE 10 while maintaining the maximum transmission rate of UL data that can be transmitted by the 5G radio unit 20A alone (one line).

The slope of the temperature rise in the UE 10, the slope of the battery consumption, and the UL data amount are not constant among the base stations, and the threshold value of the buffer 22A is different for each base station. Therefore, the DC control unit 101 repeats the processes of FIGS. 9 and 10 and stores the UL data supply amount when dual transmission is performed.

FIG. 11 shows an example in which the buffer threshold differs depending on the base station. The upper graph in FIG. 11 shows the transition of the UE data supply amount when the UE 10 is connected to the base station A (for example, the base station 1A in FIG. 1). On the other hand, the lower graph in FIG. 11 shows an example of transition of the data supply amount in the case of handover to base station B (4G base station other than base station 1A). As shown in FIG. 11, the base station A and the base station B have different thresholds for the buffer 22A to be notified to the UE 10 (there is a difference). For this reason, in the connection state to base station B, the threshold for the dual transmission state is different from that in base station A. FIG.

12 shows the transition of the CPU temperature and the remaining battery level at the base station A, and FIG. 13 shows the transition of the CPU temperature and the remaining battery level at the base station B. FIG. As shown in FIGS. 12 and 13, the base station A and the base station B have different thresholds to be notified to the UE 10, so the transitions of the CPU temperature and remaining battery capacity are also different.

Further, in the embodiment, as shown in S09 to S11 of FIG. 10, consideration is given to whether the communication service is a real-time service. For real-time services, the amount of data is reduced as the transmission rate drops, enabling the service to continue to be used. That is, it is possible to ensure user convenience.

The UE 10 (radio terminal) according to the embodiment has a buffer 22A for accumulating data to be UL transmitted, and performs UL transmission using 5G (first radio method) when the retention amount indicating the amount of data retained in the buffer 22A does not exceed the threshold, and performs UL transmission using 5G and 4G (second wireless method) when the retention amount exceeds the threshold. The UE 10 supplies data to the buffer 22A, detects a sudden rise in the temperature of the radio units 20A and 20B, indicates execution of UL transmission using 5G and 4G, and after detecting a sudden rise in temperature, the temperature in the UE 10 (CPU temperature in this embodiment) exceeds the upper limit threshold, or the remaining amount of the battery 15 falls below the lower limit threshold. 1: control unit).

As a result, it is possible to prevent the temperature of the UE 10 from rising due to the continuation of the dual transmission, causing an abnormality in the operation of the UE 10 and the sudden decrease in the remaining battery capacity of the UE 10 .

The DC control unit 101 stores the amount of data supplied to the buffer 22A when a sudden rise in the temperature of the radio units 20A and 20B is detected, and then sets the stored supply amount as the upper limit when the temperature in the UE 10 exceeds the upper limit threshold or the remaining amount of the battery 15 falls below the lower limit threshold. This prevents the transmission rate of UL transmission from significantly decreasing even when the upper limit is set, and makes it possible to perform single transmission at the maximum transmission rate in single transmission.

Further, the DC control unit 101 sets an upper limit on the amount of data to be supplied to the buffer 22A, and then cancels the upper limit when detecting a decrease in temperature (CPU temperature) in the UE 10 . This makes it possible to perform dual transmission again.

In addition, the DC control unit 101 outputs a request to reduce the amount of first data generated per unit time in the first data generation source (for example, the input device 13, camera) when the amount of first data (data having real-time properties) generated per unit time (information source data amount) out of the data supplied to the buffer 22A exceeds the upper limit of the amount of data supplied to the buffer 22A (PDCP layer supply amount). This makes it possible to continue using the service.

In the above-described embodiment, in the process of S06, it is determined whether the CPU temperature is equal to or higher than the threshold or whether the remaining battery capacity is less than the threshold. However, instead of this configuration, the DC control unit 101 may acquire the CPU usage rate (CPU operation amount) in the processing of S06 and determine whether the CPU usage rate is equal to or higher than a threshold. The CPU usage rate may also be used for the threshold determination for canceling the upper limit of the PDCP layer supply amount. In addition, the upper limit of the supply amount of the PDCP layer may be set to be different from the threshold to perform a hysteresis operation to avoid chattering. The configurations of the embodiments described above can be combined as appropriate.

1A, 2A... base station 10... wireless terminal (UE)
11 CPU
Reference Signs List 12 Storage device 13 Input device 14 Output device 15 Battery 19A, 19B RF circuit 20A, 20B Radio unit 101 Dual connectivity control unit

Claims (6)

A wireless terminal that has a buffer for accumulating data to be transmitted to the uplink, performs uplink transmission using a first wireless system when a retention amount indicating the amount of data retained in the buffer does not exceed a threshold, and performs uplink transmission using both the first wireless system and a second wireless system different from the first wireless system when the retention amount exceeds the threshold,
A control unit that supplies data to the buffer and indicates execution of uplink transmission using both the first wireless method and the second wireless method, detects a sudden rise in the temperature of a radio unit used for the uplink transmission, and sets an upper limit on the amount of data to be supplied to the buffer when the temperature in the wireless terminal exceeds an upper threshold value or the remaining battery level of the wireless terminal falls below a lower threshold value after the sudden temperature rise in the wireless unit is detected,
A wireless terminal comprising: 2. The wireless terminal according to claim 1, wherein the control unit stores the amount of data supplied to the buffer when a rapid rise in temperature of the wireless unit is detected, and thereafter sets the stored amount of supply to the upper limit when the temperature in the wireless terminal exceeds an upper limit threshold or the remaining battery level of the wireless terminal falls below a lower limit threshold. After setting an upper limit on the amount of data to be supplied to the buffer, the control unit cancels the upper limit when a decrease in temperature within the wireless terminal is detected.
The wireless terminal according to claim 1 or 2. The wireless terminal according to any one of claims 1 to 3, wherein the control unit outputs a request to reduce the amount of the first data generated per unit time at the source of the first data when the amount of the first data generated per unit time out of the data to be supplied to the buffer exceeds the upper limit of the amount of data supplied to the buffer. An uplink transmission control method for a wireless terminal having a buffer for accumulating data to be transmitted to the uplink, and performing uplink transmission using a first radio system when a retention amount indicating the amount of data retained in the buffer does not exceed a threshold, and performing uplink transmission using both the first radio system and a second radio system different from the first radio system, when the retention amount exceeds the threshold,
the wireless terminal
supplying data to the buffer;
detecting a sudden rise in temperature of a radio unit used for uplink transmission, indicative of uplink transmission using both the first radio scheme and the second radio scheme;
An uplink transmission control method for a wireless terminal, including setting an upper limit on the amount of data supplied to the buffer when the temperature in the wireless terminal exceeds an upper limit threshold or the remaining amount of the battery of the wireless terminal falls below a lower limit threshold after detecting a sudden rise in the temperature of the wireless unit. A wireless terminal that has a buffer for accumulating data to be transmitted to the uplink, performs uplink transmission using a first wireless method when a retention amount indicating the amount of data retained in the buffer does not exceed a threshold, and performs uplink transmission using both the first wireless method and a second wireless method different from the first wireless method when the retention amount exceeds the threshold,
a process of supplying data to the buffer;
a process of detecting a sudden rise in temperature of a radio unit used for said uplink transmission, indicating the execution of uplink transmission using both said first radio system and said second radio system;
A program for setting an upper limit on the amount of data supplied to the buffer when the temperature in the wireless terminal exceeds an upper limit threshold or the remaining battery level of the wireless terminal falls below a lower limit threshold after detecting a sudden rise in the temperature of the wireless unit.

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