RU2311735C2 - Method for controlling output power for communication uplinks with a set of time intervals - Google Patents

Abstract

FIELD: communications engineering, in particular, method for functioning of a mobile station in multi-access system with time division of channels (TDMA).

SUBSTANCE: in TDMA communication system, mobile stations are assigned time intervals and output power levels by base stations. This may result in situations, where combination of size of assigned time intervals and required output power level exceeds resource of mobile station. Mobile stations are offered an opportunity to reduce their average output powers in one-sided manner by reducing their peak output powers or reducing usage of assigned time intervals.

EFFECT: ensured high speed data transfer in mobile communication system.

2 cl, 15 dwg

Description

Technical field

The present invention relates to a method for a mobile station to operate in a time division multiple access (TDMA) network.

State of the art

The provision of high-speed data services to mobile stations, such as mobile telephones and transceivers in TDMA networks, has necessitated the need for mobile stations transmitting in more than one time slot in each TDMA frame. The obstacle is that the base station must have information about the maximum allowable power of the mobile station.

It was proposed to provide the mobile station with the ability to change its power class through a procedure for changing the classification index or updating the trace area, but these procedures are too slow and are not properly supported by different network implementations.

SUMMARY OF THE INVENTION

The present invention provides a method for a mobile station to function in a TDMA network, the method including receiving from a base station a command to set peak output power and receiving from a base station a distribution of transmission time intervals, characterized in that:

in the mobile station, a radio frequency system parameter of the mobile station is determined that satisfies a predetermined criterion;

in response to the above definition, the average radio frequency output power of the mobile station is changed over a plurality of time intervals so that it falls below the level that would be the average output power level if the peak output power setting command was executed in all allocated time intervals.

The criterion may include an increase in the distribution of time intervals. An increase in the distribution of time intervals occurs when additional bandwidth is required. Another suitable criterion is the temperature of the RF output power amplifier. Many time slots may be sequential or may not be sequential.

The change may be a decrease in the average radio frequency output by reducing the instantaneous radio frequency output during each transmitted time interval and / or a decrease in the average radio frequency output by reducing the use of the allocated time intervals. In the event of a change in the distribution of time intervals, there is preferably a predetermined delay time between said determination and said answer.

Also provided according to the present invention is a mobile station for a TDMA network, wherein the mobile station includes a controller and an RF output power amplifier, and wherein the controller is configured to control the operation of the mobile station to carry out the method according to the present invention.

Brief Description of the Drawings

FIG. 1 is a mobile communication system according to the present invention.

FIG. 2 is a block diagram of a mobile station.

FIG. 3 is a block diagram of a base transceiver station.

FIG. 4 is a frame structure used in an embodiment of the present invention.

FIG. 5 is a packet data channel according to an embodiment of the present invention.

FIG. 6 illustrates the separation of a radio channel between two half-speed packet data channels in an embodiment of the present invention.

FIG. 7 is the lower layers of the protocol stack used in an embodiment of the present invention.

FIG. 8 is a flowchart illustrating a first embodiment of the present invention.

FIG. 9 is a flowchart illustrating a second embodiment of the present invention.

FIG. 10 and 11 are flowcharts illustrating a third embodiment of the present invention.

FIG. 12 is a flowchart illustrating a fourth embodiment of the present invention.

FIG. 13 is a flowchart illustrating a fifth embodiment of the present invention.

FIG. 14 and 15 are flow diagrams illustrating a sixth embodiment of the present invention.

Detailed Description of Preferred Embodiments

The following examples describe preferred embodiments of the present invention with reference to the drawings.

According to FIG. 1, a mobile telephone network 1 comprises a plurality of switching centers including first and second switching centers 2a and 2b. The first switching center 2a is connected to a plurality of base station controllers including first and second base station controllers 3a, 3b. The second switching center 2b is similarly connected to a plurality of base station controllers (not shown).

The first controller of the base station 3a is connected to and controls the base transceiver station 4 and a plurality of other base transceiver stations. The second base station controller 3b is similarly connected to and controls a plurality of base transceiver stations (not shown).

In the present example, each base transceiver station serves its corresponding cell. Thus, the base transceiver station 4 serves the cell 5. However, using directional antennas, a single base transceiver station can serve multiple cells. In cell 5 there are many mobile stations 6a, 6b. It is clear that the number and membership of mobile stations in any given cell change over time.

Mobile telephone network 1 is connected to a public switched telephone network 7 using a gateway switching center 8.

The network packet service aspect includes a plurality of packet service support nodes 9 (one shown) that are associated with respective plurality of base station controllers 3a, 3b. At least one gateway packet service support node 10 or each packet service support node 10 is connected to the Internet 11.

The switching centers 3a and 3b and the packet service support node 9 have access to the home location register 12 (ROM).

The communication between the mobile stations 6a and 6b and the base transceiver station 4 uses a time division multiple access (TDMA) scheme.

According to FIG. 2, the first mobile station 6a comprises an antenna 101, a radio frequency subsystem 102, a baseband DSP (digital signal processing) subsystem 103, an analog audio subsystem 104, a speaker 105, a microphone 106, a controller 107, a liquid crystal display 108, a keyboard 109, a memory 110, a battery 111 and power supply circuit 112.

The radio frequency subsystem 102 comprises intermediate frequency circuits and radio frequency circuits of the transmitter and receiver of the mobile telephone and a frequency synthesizer for tuning the transmitter and receiver of the mobile station. The antenna 101 is connected to the radio frequency subsystem 102 for receiving and transmitting radio waves.

The baseband DSP subsystem 103 is connected to the radio frequency subsystem 102 for receiving modulating signals from it and for supplying baseband modulation signals thereto. The baseband DSP subsystem 103 includes codec functions that are widely known in the art.

The analog audio subsystem 104 is connected to the baseband DSP subsystem 103 and receives demodulated audio signals from it. The analog audio subsystem 104 amplifies the demodulated audio signals and transfers them to the loudspeaker 105. The acoustic signals detected by the microphone 106 are pre-amplified by the analog audio subsystem 104 and sent to the baseband DSP subsystem 103 for encoding.

The controller 107 controls the operation of the mobile phone. It is connected to the radio frequency subsystem 102 to provide tuning commands to the frequency synthesizer and the DSP subsystem 103 of the base band for supplying control data and distribution data for transmission. The controller 107 operates in accordance with a program stored in the memory 110. The memory 110 is shown separately from the controller 107. However, it can be combined with the controller 107.

A display device 108 is connected to a controller 107 for receiving control data, and a keyboard 109 is connected to a controller 107 for inputting user data signals thereto.

Battery 111 is coupled to a power supply circuit 112, which provides power control for various voltages used by the components of the mobile phone.

A controller 107 is programmed to control a mobile station for transmitting data and voice and applications, such as a WAP browser, to use the data transfer functions of the mobile station.

The second mobile station 6b is arranged in a similar manner.

In FIG. 3 shows a simplified representation of a base transceiver station 4 including an antenna 201, an RF subsystem 202, a baseband DSP (digital signal processing) subsystem 203, a base station controller interface 204, and a controller 207.

The radio frequency subsystem 202 comprises intermediate frequency circuits and radio frequency transmitter circuits of the base transceiver station and a frequency receiver and synthesizer for tuning the transmitter and receiver of the base transceiver station. The antenna 201 is connected to the radio frequency subsystem 202 for receiving and transmitting radio waves.

The baseband DSP subsystem 203 is connected to the radio frequency subsystem 202 for receiving modulating signals from it and for supplying baseband modulation signals thereto. The baseband DSP subsystem 203 20 includes codec functions that are widely known in the art.

The base station controller interface 204 couples the base transceiver station 4 to its base station control controller 3a.

A controller 207 controls the operation of the base transceiver station 4. It is connected to the radio frequency subsystem 202 to provide tuning commands to the frequency synthesizer and DSP subsystem 203 for supplying control data and distribution information for transmission. Controller 207 operates in accordance with a program stored in memory 210.

The base station controllers 3a and 3b are responsible for distributing radio link resources between the mobile stations and transmit power control signals from the base transceiver stations 4 to the mobile stations 6a, 6b. Under normal circumstances, mobile stations 6a, 6b transmit at a power level that is set according to these command signals. However, as explained below, according to the present invention, this is not always the case.

According to FIG. 4, each TDMA frame used for exchanging information between mobile stations 6a, 6b and base transceiver stations 4 contains eight time slots of 0.577 ms each. “Multi-shot 26” includes 26 frames, and “Multi-shot 51” includes 51 frames. Fifty-one “Multi-shot 26” or twenty-six “Multi-shot 51” comprise one superframe. Finally, the hyperframe includes 2048 superframes.

The data format within the time slots changes according to the time slot function. Normal package i.e. the time interval contains three end bits, followed by 58 encrypted data bits, a training sequence of 26 bits, another sequence of 58 encrypted data bits and the other three end bits. At the end of the packet, a guard interval of eight and a quarter bit durations is provided. The frequency correction packet has the same end bits and guard interval. However, its payload includes a fixed sequence of 142 bits. The synchronization packet is similar to a normal packet, except that in it the encrypted data is reduced to two clock pulses of 39 bits, and the training sequence is replaced by a synchronization sequence of 64 bits. Finally, the access packet includes eight leading bits, followed by a synchronization sequence of 41 bits, 36 bits of encrypted data, and three more tail bits. In this case, the guard interval has a length of 68.25 bits.

When using circuit-switched data for a speech stream, the scheme for dividing the frequency band into separate channels is used in the same way as in the global mobile communication system (GSM).

According to FIG. 5 full-speed packet-switched channels use 12 4-segment radio blocks within the “Multi-shot 51”. Free segments (time intervals) follow the third, sixth, ninth and twelfth radio blocks.

In FIG. 6 shows packet switched channels having half speed, both dedicated and shared, with time slots being alternately allocated to two subchannels.

The baseband DSP subsystems 103, 203 and the controllers 107, 207 of the mobile stations 6a, 6b and the base transceiver stations 4 are arranged to implement two protocol stacks. The first protocol stack is for circuit-switched traffic and is essentially used as in conventional GSM systems. The second protocol stack is for packet-switched traffic.

In FIG. 7 shows the levels relevant for the radio link between mobile stations 6a, 6b and the base transceiver station 4, namely, the radio link control layer 401, the medium access control layer 402, and the physical layer 403.

The radio link control level 401 has two modes: transparent and opaque. In transparent mode, data is simply transmitted without modification in the upstream or downstream direction through the radio link control level.

In the opaque mode, the radio link control level 401 provides the adaptation of the communication line and forms data blocks from data elements received from higher levels by segmenting or concatenating, as necessary, data elements and performs the inverse process for data that is transmitted up the stack. He is also responsible for detecting lost data blocks or for reordering data blocks for upstream transmission of their contents, depending on whether the acknowledged mode is used. This level can also provide correction due to feedback errors in the mode with confirmation.

The medium access control layer 402 is responsible for distributing data blocks from the radio link control layer 401 to the respective transport or logical channels and transmitting the radio blocks received from the transport or logical channels to the radio link control level 403.

The physical layer 403 is responsible for generating the transmitted radio signals from the data transmitted through the transport or logical channels, and for transmitting the received data in the upstream direction through the correct transport or logical channel to the media access control layer 402.

The exchange of blocks occurs between the media access control layer 402 and the physical layer 403 in synchronism with the clocking of the radio blocks, that is, the block is transmitted to the physical layer in each interval of the radio block.

As the required bandwidth increases, more time slots are required to support the increasing throughput of the transport or logical channel. Increased use of time intervals can lead to overheating of the power amplifier of the mobile station and current needs.

In the first embodiment, the mobile station immediately changes its output power in accordance with threshold combinations of the use of power time slots.

According to FIG. 8, when the demand for time intervals changes, the controller 107 of the mobile stations 6a, 6b determines whether the current instantaneous output level of the power amplifier exceeds the first threshold set for the number of time intervals to be used after the change (step s1). The first threshold is an instantaneous output power level that provides an acceptable average output power level. If the first threshold is exceeded, the controller 107 determines the required power reduction and compares it with the second threshold set at the power level required by the mobile stations 6a, 6b by the controller 3a, 3b serving the base station minus the margin for “allowable reduction”, for example 3 dB . If this reduced power level falls below a second threshold, then the controller 107 notifies the application that a service requiring additional time intervals cannot be provided (step s3). If the power reduction does not reach the output power level of the power amplifier below the second threshold, then the controller 107 accordingly reduces the output power (step s4). The process ends after steps s3 and s4.

If the first threshold is not exceeded (step s1), the controller 107 determines whether the current output level of the power amplifier is lower than the current power level required from the mobile stations 6a, 6b by the serving base station controller 3a, 3b (step s5). This situation may occur if the use of time slots is reduced. If the current output power level is not lower than the required level, then the process ends. However, if the current power level is lower than the required level, the current output level of the power amplifier increases as close to the required level as possible without exceeding the second threshold (step s6), and then the process ends.

In a second embodiment, the mobile station changes its output power in accordance with the temperature of its radio frequency power amplifier, which is measured by monitoring the corresponding DC voltage in the amplifier, or using a temperature sensor (not shown) provided for this purpose. In this case, the peak output power is maintained for all time intervals at the level required by the base station subsystem until the temperature exceeds the threshold level, after which the output power is reduced to the indicated limits.

According to FIG. 9, the controller 107 regularly compares the temperature of the radio frequency power amplifier of the mobile station with a first threshold corresponding to the maximum allowable operating temperature (step s101). If the first threshold is exceeded, the controller 107 reduces the power (step s102). The process ends after step s102.

If the first threshold is not exceeded (step s101), the temperature is compared with the second lower threshold (s103). A second lower threshold is used to introduce some delay in power control. If the temperature is not lower than the second threshold, then the process ends. However, if the temperature is below the second threshold, then the controller 107 determines whether the current power is at a level that is lower than the level required by the controller 3a, 3b serving the base station (step s104) and, if so, in step s105 increases the output level the power of the mobile station, for example, in steps of 2dB, and the process ends. Otherwise, the procedure simply ends without changing the output power of the mobile station.

In a third embodiment, relatively high average power levels are allowed. However, such high power levels are controlled with decreasing delay to avoid overheating when allowing the short-term use of a large frequency band.

According to FIG. 10, when the need for changes in time intervals changes, the controllers 107 of the mobile stations 6a, 6b determine whether the current instantaneous output level of the power amplifier exceeds the first threshold (step s201). The first threshold is an instantaneous output power level that provides an acceptable average output power level. If the first threshold is exceeded, then the controller 107 determines whether the cooling flag is set (step s202) and, if not, sets the timer (step s203), unless the timer is already running, then increases the output power level (step 204) and completes the process. Otherwise, the application is notified that a service requiring additional time intervals cannot be provided (step s205), and then the process ends.

If the first threshold is not exceeded (step s201), then the controller 107 determines whether the current instantaneous output level of the power amplifier is less than the current power level required from the mobile stations 6a, 6b by the serving base station controller 3a, 3b (step s206). This situation may occur when the distribution of time intervals decreases. If the current instantaneous output power level is not lower than the required level, then the process ends. However, if the current power level is below the required level, then it increases as close to the required level as possible, without exceeding the second threshold (step s204), and then the process ends.

According to FIG. 11, at the end of the timer installation time, the controller 107 determines the required power reduction and compares it with the second threshold set to the power level required from the mobile stations 6a, 6b serving their base transceiver station 4, minus the margin of “allowable reduction”, for example, 6 dB ( step s207). If this decrease in power level falls below the second threshold, the controller 107 notifies the application that a service requiring additional time intervals cannot be provided (step s208). If the power reduction does not reach the output level of the power amplifier below the second threshold, then the controller 107 accordingly reduces the output power (step s209). After the timer setting time has elapsed (step s210), a cooling flag is also set.

An alternative to reducing the instantaneous output power is to reduce the average output power using not all time slots allocated to the mobile station by the controller 3a, 3b of the serving base station.

In a fourth embodiment, the mobile station immediately changes its actual use of time slots in accordance with a threshold represented by time slice / power combinations.

According to FIG. 12, when the demand for time intervals changes, the controller 107 of the mobile stations 6a, 6b determines whether the new average output power level of the power amplifier exceeds the first threshold set for the number of time intervals to be used after the change (step s301). If the first threshold is exceeded, the controller 107 determines the reduction in the use of the allocated time intervals required to reduce the average power level below the first threshold. The new accepted value of using time slots is compared with a second threshold, that is, with a minimum number of time slots required to maintain the current level of service (step s302). If the decrease in use of the allocated time slots falls below the second threshold, then the controller 107 notifies the application that the service requiring additional time slots cannot be provided (step s303). If the reduction in the use of time slots does not reach the use of time slots below the second threshold, then the controller 107 reduces a portion of the used dedicated time slots (step s304). The process ends after steps s303 and s304.

If the first threshold is not exceeded (step s301), then the controller 107 determines whether the new average output power of the power amplifier is less than the average power corresponding to the current power level required from the mobile stations 6a, 6b by the controller 3a, 3b of the serving base stations 3a 3b (step s305). This situation may occur when the use of the allocated time intervals decreases. If the new average output power level is not less than the power level corresponding to the required level, then the process ends. However, if the new average power level is lower than the power level corresponding to the desired instantaneous power level, then the consumption of the allocated time intervals increases as close to the assigned level as possible, without exceeding the first threshold (step s306), and then the process ends.

In a fifth embodiment, the mobile station changes its use of the allocated time intervals in accordance with the temperature of its radio frequency power amplifier, which is measured by monitoring the corresponding DC voltage in the amplifier or using a sensor provided specifically for this purpose.

According to FIG. 13, the controller 107 regularly compares the temperature of the radio frequency power amplifier of the mobile station with a first threshold corresponding to the maximum allowable operating temperature (step s401). If the first threshold is exceeded, the controller 107 determines whether it is possible to reduce the use of the allocated time slots without canceling the service (step s402). If the use of the allocated time intervals falls below the minimum acceptable level, then the service or services may be lost due to lack of resources and the application is notified of insufficient resources (step s403). Otherwise, the use of time slots is reduced (step s404). The process ends after steps s403 and s404.

If the first threshold is not exceeded (step s401), the temperature is compared with the second lower threshold (s405). The second lower threshold is used to introduce some lag in the management of the use of time intervals. If the temperature is not lower than the second threshold, then the process ends. However, if the temperature is below the second threshold, the controller determines whether the current average RF frequency output level of the amplifier is lower than that which corresponds to the power level required by the serving base station controllers 3a, 3b (step s406), and if so, it increases using the allocated time slots by the mobile station (step s407), and the process ends. Otherwise, the process simply ends without changing the consumption of the allocated time intervals.

In a sixth embodiment, the use of the allocated time slots is adjusted downward after a delay in order to avoid overheating while allowing short-term use of a large frequency band.

According to FIG. 14, when the demand for time intervals changes, the controller 107 of the mobile stations 6a, 6b determines whether the new average output power level of the power amplifier exceeds the first threshold (step s501). The first threshold is an instantaneous output power level that provides an acceptable average output power level. If the first threshold is exceeded, the controller 107 determines whether the cooling flag is set (step s502), and if not, sets the timer (step s503), unless the timer is already running, then increases the output power level (step 504) and completes the process. Otherwise, the application is notified that a service requiring additional time intervals cannot be provided (step s505), and then the process ends.

If the first threshold is not exceeded (step s501), then the controller 107 determines whether the new average output power level of the power amplifier is lower than the average power corresponding to the current power level required from the mobile stations 6a, 6b by the serving base station controller 3a, 3b ( step s506). This situation may occur when the use of the allocated time intervals decreases. If the new average output power level is not less than the power level corresponding to the required level, then the process ends. However, if the new average power level is lower than the power level corresponding to the desired level, the use of the allocated time intervals is increased so that the average output power level is as close to the required level as possible, without exceeding the second threshold (step s504), and then the process ends.

According to FIG. 15, at the end of the timer setting time, the controller 107 determines the desired reduction in the use of the allocated time intervals and compares it with a second threshold set to the minimum suitable use of the time intervals for maintaining current services (step s507). If the reduction in the use of time slots falls below the second threshold, then the controller 107 notifies the application that a service requiring additional time slots cannot be provided (step s508). If the power reduction does not reach the output power level of the power amplifier, which is lower than the second threshold, then the controller 107 accordingly reduces the output power (step s509). After the timer setting time has elapsed (step s510), a cooling flag is also set.

The above average power levels were calculated based on the instantaneous power levels in the moving window. The window length will depend on the thermal characteristics of the radio frequency power amplifier and the duration of time intervals and frames, as well as on the number of time intervals in the frame.

Claims (3)

1. A method of operating a mobile station in a time division multiple access (TDMA) network, comprising: receiving a command for setting a peak output power from a base station; receiving a distribution of transmission time slots from a base station; an increase in the distribution of time intervals of the mobile station is detected in the mobile station, and in response to said detection, it is determined whether the received peak output power exceeds a threshold and, if so, the average radio frequency output power of the mobile station is changed over a plurality of time intervals by reducing the instantaneous radio frequency output power over each transmission time interval or reduce the use of the allocated time intervals so that it falls below a value that would of the average level of the output power setting command if the peak output power was performed in all timeslots allocated, characterized in that the predetermined waiting time between determination that said threshold is exceeded and performing said subsequent changes in the average output power. 2. The method according to claim 1, comprising executing the application program on the mobile station, wherein at the end of said predetermined time, a cooling flag is set, and if said threshold is exceeded and the cooling flag is not set, a timer is set that determines said predefined time, while the aforementioned subsequent change in the average output power is performed after the timer setting time has elapsed, and if, after the timer setting time has elapsed, it is determined that the required lower If the power level brings the output power to a level below an additional lower threshold, the application program is notified that a service requiring an increase in the allocated time intervals cannot be supported. 3. A mobile station for a TDMA network, comprising an antenna associated with a radio frequency subsystem including a radio frequency output power amplifier, a digital signal processing subsystem and a controller associated with a radio frequency subsystem and a digital signal processing subsystem, characterized in that the controller is operable the operation of the mobile station to implement the method according to any one of claims 1 and 2.

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