PATENT DOCUMENT

Publication Number: US-11102729-B2
Application Number: US-201615736416-A
Country: US
Kind Code: B2

Title: Multi-transmission capable data transmission system and method of operating the same

Abstract:
A data transmission system may comprise a first transmission chain comprising a first transmission power controller, the first transmission power controller being configured to operate in an open loop power control mode or in a closed loop power control mode; a second transmission chain; and a power control mode selector configured to select the first transmission power controller to operate in the open loop power control mode or in the closed loop power control mode based on at least one quantity indicative of interference induced by the second transmission chain in the first transmission power controller when operating in the closed loop power control mode.

Claims:
The invention claimed is: 
     
       1. A data transmission system comprising:
 a first transmission chain comprising a first transmission power controller, the first transmission power controller is configured to operate in an open loop power control mode or in a closed loop power control mode; 
 a second transmission chain; and 
 a power control mode selector configures the first transmission power controller to operate in the open loop power control mode or in the closed loop power control mode based on at least one quantity indicative of interference induced by the second transmission chain in the first transmission power controller when operating in the closed loop power control mode and based on an activated multi-transmission mode or an activated single transmission mode of the data transmission system. 
 
     
     
       2. The data transmission system of  claim 1 , wherein the power control mode selector configures the first transmission power controller based on a frequency pairing of a first transmission frequency of the first transmission chain and a second transmission frequency of the second transmission chain. 
     
     
       3. The data transmission system of  claim 1 , wherein the power control mode selector configures the first transmission power controller based on a transmission power pairing of a first transmission power of the first transmission chain and a second transmission power of the second transmission chain. 
     
     
       4. The data transmission system of  claim 1 , wherein the power control mode selector configures the first transmission power controller based on a measurement indicative of a leakage of transmission power of the second transmission chain into the first transmission chain. 
     
     
       5. The data transmission system of  claim 1 , further comprising:
 a first look-up table; 
 wherein the first look-up table is configured to perform an update process of entries of the first look-up table based on transmission power measurement values obtained while the data transmission system is operated in the closed loop power control mode; and 
 wherein the open loop power control mode of the first transmission power controller is further configured to set a transmission power of the first transmission chain based on the first look-up table. 
 
     
     
       6. The data transmission system of  claim 5 , further comprising:
 an interference indicator configured to enable or disable the update process, wherein the interference indicator is configured to enable the update process if the interference induced by the second transmission chain in the first transmission power controller when operating in the closed loop power control mode is estimated to be small. 
 
     
     
       7. The data transmission system of  claim 5 , wherein the first look-up table comprises first entries and second entries,
 wherein the first entries are target transmission power levels of the first transmission chain; 
 wherein the second entries are setting values for the first transmission power controller; and 
 wherein each setting value corresponds to a respective target transmission power level. 
 
     
     
       8. The data transmission system of  claim 7 , further comprising:
 a second look-up table; 
 wherein the second look-up table comprises adjustment values for adjusting the second entries of the first look-up table, the adjustment values are based on one or more of a temperature, a supply voltage and a spatial orientation of the data transmission system. 
 
     
     
       9. The data transmission system of  claim 8 , wherein the second look-up table is configured to adjust the second entries of the first look-up table if one or more of a time span since a last update of the second entries of the first look-up table, a change in the temperature, a change in the supply voltage and a change in the spatial orientation of the data transmission system exceeds a respective certain threshold. 
     
     
       10. The data transmission system of  claim 1 , wherein the data transmission system is comprised in a wireless device. 
     
     
       11. The data transmission system of  claim 1 , wherein the data transmission system is comprised in a cable-based device. 
     
     
       12. The data transmission system of  claim 1 , further comprising:
 a second transmission power controller comprised in the second transmission chain; wherein the power control mode selector configures the second transmission power controller to operate in the open loop power control mode or in the closed loop power control mode, wherein the configuration of the second transmission power controller is based on at least one quantity indicative of interference induced by the first transmission chain in the second transmission power controller when operated in the closed loop power control mode. 
 
     
     
       13. The data transmission system of  claim 1 , wherein the first transmission chain is configured to transmit first data via a first antenna and the second transmission chain is configured to transmit second data via a second antenna. 
     
     
       14. The data transmission system of  claim 1 , wherein the first transmission chain and the second transmission chain are configured to transmit first data and second data via a common antenna. 
     
     
       15. The data transmission system of  claim 1 , wherein the power control mode selector is implemented in software. 
     
     
       16. The data transmission system of  claim 1 , wherein the first transmission chain comprises a power amplifier and wherein the first transmission power controller is configured to control an input power of the power amplifier. 
     
     
       17. The data transmission system of  claim 1 , wherein the first transmission chain comprises a power amplifier and wherein the first transmission power controller is configured to control a power supply of the power amplifier. 
     
     
       18. A multi-transmission communication system comprising: a first transmitter;
 a first transmission power controller configured to control a transmission power of the first transmitter; 
 a second transmitter; 
 a second transmission power controller configured to control a transmission power of the second transmitter; and 
 a power control mode selector configured to receive at least one quantity and to set the first transmission power controller in an open loop power control mode or a closed loop power control mode based on the at least one quantity, and based on an activated multi-transmission mode or an activated single transmission mode of the multi-transmission communication system, 
 wherein the at least one quantity is indicative of interference induced by the second transmitter in the first transmission power controller when operating in the closed loop power control mode. 
 
     
     
       19. A method of operating a multi-transmission system, wherein the multi-transmission system is configured to transmit first data using a first transmission chain and second data using a second transmission chain, the method comprising:
 controlling a transmission power of the first transmission chain in an open loop power control mode or in a closed loop power control mode; and 
 selecting the open loop power control mode or the closed loop power control mode at least partially based on at least one quantity indicative of interference induced by the second transmission chain in the closed loop power control mode and based on an activated multi-transmission system mode or an activated single transmission mode of the multi-transmission system. 
 
     
     
       20. The method of  claim 19 , further comprising:
 controlling the transmission power of the first transmission chain in the open loop power control mode by using a first look-up table; 
 measuring the transmission power of the first transmission chain in the closed loop power control mode; and 
 updating the first look-up table based on measured transmission power values obtained during closed loop power control mode operation. 
 
     
     
       21. The method of  claim 20 , wherein updating of the first look-up table is enabled only if an interference indicator indicates that the interference induced by the second transmission chain in the closed loop power control mode is estimated to be below a given threshold. 
     
     
       22. The method of  claim 20 , wherein first entries of the first look-up table are target transmission power levels of the first transmission chain and wherein second entries of the first look-up table are setting values for controlling the transmission power of the first transmission chain, the method further comprising:
 updating the second entries of the first look-up table so as to obtain a closer correspondence between the target transmission power levels and actual transmission power levels. 
 
     
     
       23. The method of  claim 22 , further comprising:
 adjusting the second entries of the first look-up table on a basis of adjustment values of a second look-up table, wherein the adjustment values of the second look-up table are based on one or more of a temperature, a supply voltage and a spatial orientation of the multi-transmission system.

Description:
FIELD 
     The disclosure relates to a multi-transmission capable data transmission system. In particular, the disclosure relates to a transmission power control system for a multi-transmission capable data transmission system and a method of controlling a transmission power of the multi-transmission capable data transmission system. 
     BACKGROUND 
     Data transmission systems may be an integral part of any telecommunication device, be it a mobile device or a cable based device. Data may be transmitted using different transmission powers depending on the current channel conditions and transmission requirements. Tight control of the transmission power may be crucial in order to ensure an accurate data transmission and/or data reception by the intended receiver. Furthermore, manufacturers aim to produce new data transmission systems having improved functionalities like, for example, increased data transfer rates, by, for example, employing multiple transmission chains simultaneously. However, in such multi-transmission systems, it may be necessary to employ an improved transmission power control system in order to obtain satisfactory transmission power control. 
     For these and other reasons there is a need for the current invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. 
         FIG. 1  schematically shows an example of a first data transmission system comprising a power control mode selector. 
         FIG. 2  schematically shows a transmission power controller, wherein the transmission power controller may be employed in a data transmission system as shown in  FIG. 1 . 
         FIG. 3  schematically shows a power control mode selector, wherein the power control mode selector may be employed in a data transmission system as shown in  FIG. 1 . 
         FIG. 4  schematically shows a look-up table, wherein the look-up table may be employed in a data transmission system as shown in  FIG. 1 . 
         FIG. 5  shows an operation chart depicting a possible mode of operation of a data transmission system. 
         FIG. 6  schematically shows a further example of a data transmission system in greater detail, wherein the data transmission system shown in  FIG. 6  may, for example, be implemented in a mobile device. 
         FIG. 7  shows a chart of an example of a method of operating a multi-transmission data transmission system, wherein the method may be used to operate the data transmission systems shown in  FIGS. 1 and 6 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings in which are shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. 
     It is to be understood that the features of the various examples described herein may be combined with each other, unless specifically noted otherwise. Further, like reference numerals designate corresponding identical or similar parts. 
     As employed in this specification, the terms “coupled” and/or “connected” are not meant to mean in general that the elements must be directly coupled or connected together; intervening functional elements may be provided between the “coupled” or “connected” elements. However, although not restricted to that meaning, the terms “coupled” and/or “connected” may also be understood to optionally disclose an implementation in which the elements are directly coupled or connected together without intervening elements provided between the “coupled” or “connected” elements. 
     A data transmission system may be comprised in a telecommunication device such as a wireless device or a cable based device and may be configured for transmitting data from the telecommunication device to a second telecommunication device. Examples for wireless devices are base stations and mobile devices like mobile phones or laptops. Wireless devices may employ various Radio Access Technologies (RATs) for wireless communications, for example Bluetooth, Wi-Fi (Wireless Fidelity), 2G (Second Generation), 3G (Third Generation), 4G (Fourth Generation), LTE (Long Term Evolution), etc. 
     A data transmission system may support simultaneous transmission of more than one data stream (this may also be called multi-transmission herein). Multi-transmission is, for example, employed in telecommunication devices featuring Up-Link Carrier Aggregation (UL-CA), Dual Sim Dual Active (DSDA) or Transmission-Multiple Input Multiple Output (TX-MIMO). UL-CA is a feature of LTE-A (LTE-Advanced, Release 10 and higher versions of LTE). Multi-transmission may increase a data transfer rate of the telecommunication device. For example, in LTE-A two or more component carriers may be aggregated to achieve a transmission bandwidth of 40 MHz, or even 100 MHz. Therefore, the data transmission system may simultaneously transmit in two different frequency bands. Furthermore, it is possible that two different RATs are active at the same time in a multi-transmission capable data transmission system. For example, in DSDA a 2G telephone call associated with a first SIM card and an LTE data transfer associated with a second SIM card may be active simultaneously. In some features, for example in DSDA, it is of course also possible to simultaneously transmit first data and receive second data. 
     A data transmission system may comprise means for controlling a transmission power of a data transmission. Means for controlling a transmission power may comprise a power control mode selector, a first transmission power controller comprised in a first transmission chain and a second transmission power controller comprised in a second transmission chain. Controlling the transmission power may comprise accurately controlling transmission power step sizes and/or a maximum transmission power. For example, for 3G Frequency-Division Duplexing (FDD) systems the 3GPP TS 25.101 specification defines a maximal tolerated transmission power step size error of ±0.5 dB per 1 dB transmission power change. In Time-Division Duplexing (TDD) systems, such as for example GSM (Global Systems for Mobile Communications) or LTE TDD, data may be transmitted slot-wise. The means for controlling the transmission power may be configured to ramp up the transmission power of a transmission chain to a target transmission power level at the beginning of a data transmission slot and may be configured to ramp down the transmission power to a specific minimum level at the end of the data transmission slot. For example, in LTE TDD the minimum level may be less than about −40 dBm and the target transmission power level may be about 23 dBm. 
       FIG. 1  shows an exemplary data transmission system  100 . The data transmission system  100  may comprise a first transmission chain  102 , a second transmission chain  104  and a power control mode selector  108 . The first transmission chain  102  may comprise a first transmission power controller  106 , wherein the first transmission power controller  106  is coupled to the power control mode selector  108 . 
     The data transmission system  100  may optionally comprise a second transmission power controller  112  comprised in the second transmission chain  104 . The second transmission power controller  112  may be coupled to the power control mode selector  108 . 
     The data transmission system  100  may optionally comprise a first look-up table  110 . The first look-up table  110  may be coupled to the first transmission power controller  106 . The first look-up table  110  may optionally be coupled to the second transmission power controller  112  (not shown in  FIG. 1 ). 
     The first and the second transmission chains  102 ,  104  may be configured to be coupled to a first and a second transmission means, respectively. The first and second transmission means may comprise a first and a second antenna (schematically shown in  FIG. 1 ). Instead of antennas, the first and second transmission means may comprise first and second data transmission cables. Alternatively, the first and the second transmission chains  102 ,  104  may be configured to be coupled to a common transmission means. The common transmission means may comprise a common antenna or a common data transmission cable. A diplexer may, for example, be configured to combine transmission data of the first and second transmission chains  102 ,  104  in the common transmission means. 
     Although only first and second transmission chains  102  and  104  are shown, data transmission system  100  may also comprise further data transmission chains. The further transmission chains may comprise corresponding transmission power controllers coupled to the power control mode selector  108 . The further transmission power controller(s) may be coupled to the first look-up table  110 . 
     The first transmission power controller  106  may be configured to operate in a first power control mode or a second power control mode in order to control a first transmission power of the first transmission chain  102 . The second transmission power controller  112  may be configured to operate in the first power control mode or the second power control mode in order to control a second transmission power of the second transmission chain  104 . The power control mode selector  108  may be configured to select the first transmission power controller  106  to operate in the first power control mode or in the second power control mode. The power control mode selector  108  may further be configured to select the second transmission power controller  112  to operate in the first power control mode or in the second power control mode. 
     The first power control mode may comprise a closed loop power control mode and the second power control mode may comprise an open loop power control mode. 
     In the closed loop power control mode the power control may use of a feedback mechanism. The transmission power may be measured and compared to a target transmission power level. Measuring the transmission power may, for example, be done using a coupler in the respective transmission chain. The difference between the measured transmission power and the target transmission power may be applied as an input to the respective transmission power controller, thereby adjusting the transmission power until the difference is zero or falls below a certain threshold. Adjusting the transmission power may comprise changing a signal fed by the respective transmission power controller into the respective transmission chain. The signal may, for example, be fed into a power amplifier comprised in the transmission chain. For example, an input power of the input signal of the power amplifier may be changed based on the signal. It is also possible to change the bias of the power amplifier, for example by changing a quiescent current and/or a supply voltage of the power amplifier based on the signal. 
     In the open loop power control mode the transmission power may be adjusted without measuring the transmission power and without applying a feedback mechanism. Instead, data on the target transmission power levels and the corresponding input values of the respective transmission chain may be stored in a memory and may be read out when required. For example, target transmission power levels and corresponding input values may be stored in the first look-up table  110  as described further below with respect to  FIG. 4 . The input values may comprise values of an input of a power amplifier comprised in the respective transmission chain as described above. 
     The data transmission system  100  may be configured to update entries of the first look-up table  110  while the first transmission power controller  106  operates in the closed loop power control mode and the transmission power is measured. This approach of refreshing the first look-up table  110  from time to time by actual data is explained in greater detail further below with respect to  FIG. 4 . 
     The power control mode selector  108  may be configured to select the first transmission power controller  106  to operate in the closed loop power control mode if operation conditions in the first transmission chain  102  are such that a reliable measurement of the transmission power is deemed possible. If operation conditions in the first transmission chain  102  are such that a reliable measurement of the transmission power is deemed not possible, the power control mode selector  108  may be configured to select the first transmission power controller  106  to operate in the open loop power control mode. Here “reliable” means that the measured transmission power and the actual transmission power are identical or that the difference between the two is below than a certain threshold. 
     For example, in some cases a reliable measurement of the transmission power of the first transmission chain  102  may not be possible if the second transmission chain  104  transmits simultaneously. Transmitted power of the second transmission chain  104  may be coupled into the first transmission chain  102  due to a finite isolation between the two respective transmission means and may contribute to the measured transmission power of the first transmission chain. Therefore, the measured transmission power may be higher than the actual transmission power. 
     This is further illustrated by the following example: the first transmission chain  102  may transmit with a first transmission power of 10 dBm, the second transmission chain  104  may simultaneously transmit with a transmission power of 33 dBm and an isolation between the first transmission means and the second transmission means may be 15 dBm. In this case about 18 dBm of the transmission power of the second transmission chain  104  is, e.g., inductively coupled into the first transmission chain  102 . This leakage power may form a reverse wave in the first transmission chain  102  as seen from the perspective of a directional coupler. However, the second transmission chain  104  may transmit at a different radio frequency compared to the first transmission chain  102 . Therefore, the reverse wave may be reflected at a duplexer or another component of the first transmission chain  102 . The reflected wave may form a forward wave which may add to the first transmission power. Assuming a return loss of 6 dB the power of the reflected wave is about 12 dBm and therefore greater than the first transmission power (which in this example is only 10 dBm). This would result in a highly incorrect measurement of the transmission power of the first transmission chain  102 . 
     Generally speaking, the selection of the power control mode selector  108  to operate the first transmission power controller  106  in the closed loop power control mode or in the open loop power control mode may be based on at least one quantity indicative of interference induced by the second transmission chain  104  in the first transmission power controller  106  when operating the first transmission power controller  106  in the closed loop power control mode. The at least one quantity may be indicative of actual or assumed interference induced. An example of a power control mode selector  108  is described in greater detail further below with respect to  FIG. 3 . 
     Power control mode selector  108  may also be configured to select the second transmission power controller  112  or any further transmission power controllers to operate in the closed loop power control mode or the open loop power control mode as described above with respect to the first transmission power controller  106 . Reference is made to the above description to avoid reiteration. By way of example, a method of operating such multi-transmission system may comprise transmitting first data with a first transmission chain  102  and transmitting second data with a second transmission chain  104 . For at least a first time period, the first transmission chain  102  may be operated in a closed loop power control mode. A potential interference induced by the second transmission chain  104  in the first transmission chain  102  may be identified, e.g., as described above. Then, for at least a second time period and in response to identifying the potential interference, the first transmission chain  102  may be operated in an open loop power control mode. 
       FIG. 2  shows an example of a transmission power controller  200 , wherein transmission power controller  200  may correspond to the first transmission power controller  106  or the second transmission power controller  112  of  FIG. 1 . Transmission power controller  200  may comprise a first input  202 , a second input  204 , a third input  206 , a fourth input  208  and an output  210 . The transmission power controller  200  may further comprise a regulator  212 , wherein the first, second and third inputs  202 ,  204 ,  206  may be coupled to the regulator  212 . The transmission power controller  200  may further comprise an open loop control  214 , wherein the first input  202  and the fourth input  208  may be coupled to the open loop control  214 . The transmission power controller  200  may further comprise an programmable gain control  216 , wherein an output of the regulator  212  may be coupled to a first input of the programmable gain control  216 , an output of the open loop control  214  may be coupled to a second input of the programmable gain control  216  and the output  210  is an output of the programmable gain control  216 . 
     The first input  202  may be configured to be coupled to a baseband integrated circuit (IC), the second input  204  may be configured to be coupled to a power control mode selector, e.g. power control mode selector  108 , the third input  206  may be configured to be coupled to a transmission power sensor and the fourth input  208  may be configured to be coupled to a first look-up table, e.g. the first look-up table  110 . The output  210  may be configured to be coupled to an input of a power amplifier comprised in a transmission chain. 
     The regulator  212  may be configured to receive a target transmission power value via the first input  202  and a measured power via the third input  206 . The regulator  212  may be configured to receive a signal via the second input  204  setting the regulator  212  to operate in the closed loop power control mode or in the open loop power control mode. 
     In the closed loop power control mode, the regulator  212  may be configured to compare the target transmission power value received via the first input  202  with the measured power received via the third input  206  and to output a corresponding setting value to the programmable gain control  216  in order to minimize a difference between the target transmission power and the measured power as described above. 
     In the open loop control mode, the open loop control  214  may be configured to receive a target transmission power value via the first input  202  and may be configured to obtain a corresponding setting value via the fourth input  208 . The open loop control  214  may be configured to output the setting value to the programmable gain control  216 . In one example of a transmission power controller  200  the open loop control  214  may also be coupled to the second input  204  (not shown in  FIG. 2 ). In this case the open loop control  214  may be configured to receive a signal via the second input  204  activating the open loop control  214  in the open loop power control mode and deactivating the open loop control  214  in the closed loop power control mode. In one example of a transmission power controller  200  the open loop control  214  may, e.g., be comprised in the regulator  212 . In this case, the regulator  212  may output a setting value to the programmable gain control  216  which may either be generated by closed loop control operation as described above or by open loop control operation as, e.g., described above in view of the setting value output by the open loop control  214  to the programmable gain control  216 . 
     The programmable gain control  216  may be configured to receive a setting value from the open loop control  214  in the open loop power control mode and a setting value from the regulator  212  in the closed loop power control mode. The programmable gain control  216  may be configured to control an amplification factor of a power amplifier coupled to output  210  based on the setting value. By way of example, the programmable gain control  216  may be configured to control an input power, a quiescent current and/or a supply voltage of the power amplifier. 
     Transmission power controller  200  may be implemented in software, in hardware, or in a combination of software and hardware. 
       FIG. 3  shows an example of a power control mode selector  300 , wherein power control mode selector  300  may correspond to the power control mode selector  108  of FIG.  1 . Power control mode selector  300  may comprise a first input  302 , a second input  304 , a multi-transmission scheduler  306  and a first output  310 . The first input  302 , the second input  304  and the first output  310  may be coupled to the multi-transmission scheduler  306 . 
     The first input  302  may be configured to be coupled to a first baseband IC. Alternatively, the first input  302  may be configured to be coupled to a first transmission chain. The multi-transmission scheduler  306  may be configured to receive a signal (from the first baseband IC or from the first transmission chain) via the first input  302  indicating that the first transmission chain is active. The second input  304  may be configured to be coupled to a second baseband IC or to the first baseband IC if the first baseband IC is configured to operate the first transmission chain and also a second transmission chain. Alternatively, the second input  304  may be configured to be coupled to the second transmission chain. The multi-transmission scheduler  306  may be configured to receive a signal (from the baseband IC or from the second transmission chain) via the second input  304  indicating that the second transmission chain is active. 
     The output  310  may be configured to be coupled to a first transmission power controller of the first transmission chain. For example, the output  310  may be configured to be coupled to a regulator comprised in the first transmission chain. 
     The multi-transmission scheduler  306  may be configured to select the first transmission power controller to operate in the closed loop power control mode or in the open loop power control mode. In an example of a power control mode selector  300  the multi-transmission scheduler  306  may be configured to select the first transmission power controller to operate in the closed loop power control mode if only the first transmission chain is active and in the open loop power control mode if also the second transmission chain is active. 
     However, simultaneous transmission of the first and second transmission chains may not impair a reliable measurement of transmission power in to the closed loop power control mode in every case. For example, for certain known combinations of a first transmission frequency of the first transmission chain and a second transmission frequency of the second transmission chain an isolation of the first transmission chain may be good enough that transmission power of the second transmission chain coupled into the first transmission chain is zero or below a critical threshold for a reliable measurement of transmission power. 
     Another quantity that might impair a reliable measurement may be a transmission power pairing of a first transmission power of the first transmission chain and a second transmission power of the second transmission chain. For example, in the case that the second transmission power exceeds a certain threshold relative to the first transmission power, a reliable measurement may not be possible. 
     Therefore, in a further example the power control mode selector  300  comprises an interference indicator  308  configured to signal the multi-transmission scheduler  306  if an interference situation prevails or not (“interference situation” means that no reliable measurement of transmission power is deemed possible). In the case of an interference situation the multi-transmission scheduler  306  selects the open loop power control mode while in the case of no interference situation the multi-transmission scheduler  306  selects the closed loop power control mode. The interference indicator  308  may, for example, comprise a table containing data on transmission frequency pairings and/or (target) transmission power pairings in which an interference situation prevails. These data may, for example, stem from prior knowledge, i.e. the occurrence or non-occurrence of an interference situation may be evaluated without measurement on the basis of a-priory information. It is also possible that the occurrence or non-occurrence of an interference situation may be evaluated based on combined a-priori and measurement information. 
     According to an example the power control mode selector  300  may comprise a third input (not shown in  FIG. 3 ). The third input may be an input of the interference indicator  308 , and the interference indicator  308  may be configured to receive information indicating an interference situation via the third input. For example, the interference indicator  308  may receive information about channels used in the first and second transmission chains or (measured or target) transmission powers of the first and second transmission chains via the third input. Furthermore, the first (and/or the second) transmission chain may comprise a directional coupler configured to measure a reverse wave in the first (the second) transmission chain. A high power of the reverse wave is an indication that a transmission power measurement may be corrupted. In order to distinguish between power coupled into the transmission chain (e.g. inductively) from a transmission power reflected at the transmission means (e.g. the antenna), the level of the forward wave and the reverse wave may be compared. If the reverse wave has a higher power than the forward wave then power is coupled into the transmission chain and an interference situation may prevail. This information may also be received by the interference indicator  308  via the third input. 
     According to an example the power control mode selector  300  comprises a second output (a third output, a fourth output, . . . ), wherein the second output (the third output, the fourth output, . . . ) is an output of the multi-transmission scheduler  306  and is configured to be coupled to a transmission power controller of the second (a third, a fourth, . . . ) transmission chain. The control mode selector  300  may be configured to select the second (third, fourth, . . . ) transmission power controller to operate in the closed loop power control mode or in the open loop power control mode as described above with respect to the first transmission power controller. 
     Power control mode selector  300  may be implemented in software, in hardware, or in a combination of software and hardware. 
       FIG. 4  shows an example of a first look-up table  400 , wherein the first look-up table  400  may correspond to the first look-up table  110  of  FIG. 1 . The first look-up table  400  may comprise a first column  402  comprising first entries x 1 , x 2 , . . . , x n  and a second column  404  comprising second entries y 1 , y 2 , . . . , y n , wherein each first entry x 1  may have a corresponding second entry y 1 . 
     According to an example of a first look-up table  400 , the first entries comprise target transmission power levels of a first transmission chain and the second entries comprise corresponding setting values for a first transmission power controller of the first transmission chain. For example, the setting values may be gain values of a power amplifier of the transmission chain or transceiver gain values. 
     A data transmission system such as data transmission system  100  may comprise a first look-up table  400  for each transmission chain comprised in the data transmission system. According to another example, the first look-up table  400  may comprise a distinct second column  404  for each transmission chain. 
     The first and second entries may be predetermined values which stem from prior knowledge and may be fixed. The first and second entries may stem from factory calibration. Calibrating the first look-up table  400  during factory calibration may help to compensate for possible part to part variations. However, according to another example of a first look-up table  400 , the first and/or second entries may be updated during an operation of the data transmission system. For example, the first look-up table  400  may be configured to be updated while the data transmission system operates in the closed loop power control mode. The transmission power and the corresponding input value of the power amplifier may be determined. The look-up table  400  may be updated by the determined input value. According to an example of a first look-up table  400 , updating may comprise averaging the new data with the existing entry in order to avoid corrupting the look-up table  400  by a failed measurement. 
     The number of rows (that is, the number of first and second entries) of the first look-up table  400  may be fixed and may have a fixed step size of, e.g., 1 dB. However, the number of entries may also be dynamic and may correspond to the number of different transmission power levels occurring during a transmission period of the transmission chain. 
     In the open loop power control mode a transmission power controller such as, e.g., the first transmission power controller  106  of  FIG. 1  may obtain setting values from a first look-up table like the first look-up table  400 . 
     The second entries (setting values) of the first look-up table  400  may be a function of current operating conditions of the data transmission system. Current operating conditions may, for example, comprise a temperature, a supply voltage, an antenna mismatch, a spatial orientation, etc. of the data transmission system. Changes in the operating conditions may be slow compared to an update rate of the first look-up table  400 . However, if a transmission power controller is operated in the open loop power control mode for a prolonged time span, then changes in the operating conditions may lead to an increasing mismatch between the transmission power set according to the first look-up table and the target transmission power. 
     Therefore, a data transmission system such as data transmission system  100  may comprise a second look-up table (not shown) comprising adjustment values for adjusting the first and/or the second entries of the first look-up table  400 , wherein the adjustment values are based on the operating conditions. The adjustment values may be determined based on one or more measurements of the operating conditions. Note that a measurement of the operating conditions may be performed independent of a transmission power controller operating in the open loop or closed loop power control mode. According to an example, the second look-up table is used for adjusting the second entries of the first look-up table  400  if one or more of a time span since a last update of the second entries of the first look-up table, a change in the temperature, a change in the supply voltage and a change in the spatial orientation of the data transmission system (e.g. a mobile device such as, e.g., a mobile phone, smartphone, tablet, laptop, etc.) exceeds a respective certain threshold. Adjustment of the second entries of the first look-up table  400  may be performed by any appropriate combining of the second entries with the adjustment values, e.g. by multiplying or adding the corresponding second entry with the corresponding adjustment value. As such, while updating the second entries of the first look-up table during the closed-loop control operation provides for a kind of self-learning control scheme, the (optional) application of the second look-up table may provide for an additional control mechanism for compensating (residual) changes of operating conditions which are not taken into account by the self-learning scheme. 
     It is to be noted that the self-learning approach as described above (optionally extended by the operation condition adjustment mechanism) may accurately set the output power during open loop control operation without requiring time-consuming factory calibration and/or complex real-time compensation algorithms. 
       FIG. 5  shows an operation chart  500  depicting an exemplary operation of a data transmission system such as, e.g., data transmission system  100  of  FIG. 1 . At  502  it is checked if simultaneous transmission of two or more transmission chains is enabled. If the answer is no, then at  504  a closed loop power control mode is enabled. During the closed loop power control mode at  506 , entries of a first look-up table may be updated based on measured transmission power values. If the answer at  502  is yes, then at  508  it may optionally be checked if an interference situation prevails or not. If the answer is no, then the closed loop power control mode is enabled. If the answer at  508  is yes or if the check at  508  is omitted, then an open loop power control mode is enabled. During the closed loop power control mode and/or the open loop power control mode, it may be repeatedly checked if multi-transmission is enabled at  502 . 
       FIG. 6  shows an example of a data transmission system  600 , wherein data transmission system  600  may represent a more detailed example of the data transmission system  100  of  FIG. 1 . Elements illustrated in  FIG. 6  may likewise be implemented in the data transmission system  100  and vice versa. Reference is made to the above description in order to avoid reiteration. 
     Data transmission system  600  may comprise a first transmission chain  602  configured to be coupled to a first transmission means such as, e.g., a first antenna and to a first baseband IC  610 . Data transmission system  600  may comprise a second transmission chain  604  configured to be coupled to a second transmission means such as, e.g., a second antenna and to a second baseband IC  612 . Data transmission system  600  may also be configured to be coupled to a common baseband IC and/or to first and second cables or a common cable or a common antenna. The first and second transmission chains  602  and  604  may comprise first and second power amplifiers  606  and  608 , respectively. There is a non-infinite isolation between the first and second transmission means. 
     The data transmission system  600  may further comprise a multi-transmission scheduler  614 , an interference indicator  616 , regulators  618  and  620 , open loop controls  622  and  624 , first (and, optionally, second) look-up tables  626  and  628  and programmable gain controls  630  and  632 . The open loop controls  622  and  624  may optionally be coupled to the outputs of the multi-transmission scheduler  614  (not shown in  FIG. 6 ). Furthermore, the open loop controls  622  and  624  may be comprised in the regulators  618  and  620 , respectively. All these elements may be operable as described above with respect to  FIGS. 1 to 4 , and reiteration is avoided for the sake of brevity. 
     Briefly, closed loop power control operation is performed by a feedback loop including, e.g., the coupler, the power sensor, the regulator  618  and  620 , respectively, the BB IC  610  and  612 , respectively, the programmable gain control  630  and  632 , respectively, and the power amplifier  606  and  608 , respectively. Optionally, the PA power supply may form part of the feedback loop if the gain of the power amplifier  606  and  608 , respectively, is controlled by the amplifier bias. 
     Open loop power control operation is performed by a forward control including, e.g., the BB IC  610  and  612 , respectively, the open loop control  622  and  624 , respectively, the programmable gain control  630  and  632 , respectively, and the power amplifier  606  and  608 , respectively. Optionally, the PA power supply may form part of the open loop control if the gain of the power amplifier  606  and  608 , respectively, is controlled by the amplifier bias. Further, if a self-learning approach as described above is implemented, the open loop power control may, e.g., be supplemented by the coupler, the power sensor and the first (and, optionally, second) look-up table  626  and  628 , respectively. 
     Selection between the open loop power control operation and the closed loop power control operation for one or each of the first and second transmit chains  602 ,  604  may be performed by, e.g., the interference indicator  616  and the multi-transmission scheduler  614  as described above with respect to  FIG. 3 . 
     The symmetric design of the first and second transmit chains  602  and  604  as exemplified in  FIG. 6  is a mere option. It is also possible that the first and second transmit chains  602  and  604  are quite different and/or that only one of these transmit chains is implemented with the circuitry disclosed herein. 
     Further, it is to be noted that the concept of alternatingly operating one or more of the transmit chains  602  and  604  in the open and closed power control mode based on the output of the power control mode selector (e.g. the interference indicator  616  and the multi-transmission scheduler  614 ) and the concept of applying a self-learning approach for improving the open loop power control are basically independent from each other. As such, they may be combined in various embodiments but may, in other embodiments, also be implemented individually without making use of the other concept. 
       FIG. 7  shows an example of a method  700  of operating a multi-transmission system such as, e.g., the data transmission system  100  of  FIG. 1 , wherein the multi-transmission system is configured to transmit first data using a first transmission chain and second data using a second transmission chain. Method  700  may comprise at  701  controlling a transmission power of the first transmission chain in an open loop power control mode or in a closed loop power control mode. Method  700  may comprise at  702  selecting the power control mode based on at least one quantity indicative of interference induced by the second transmission chain in the closed loop power control. Processes  701  and  702  may be performed consecutively or simultaneously. 
     EXAMPLES 
     The following examples pertain to further embodiments. Example 1 is a data transmission system comprising a first transmission chain comprising a first transmission power controller, the first transmission power controller being configured to operate in an open loop power control mode or in a closed loop power control mode; a second transmission chain; and a power control mode selector configured to select the first transmission power controller to operate in the open loop power control mode or in the closed loop power control mode based on at least one quantity indicative of interference induced by the second transmission chain in the first transmission power controller when operating in the closed loop power control mode. 
     In Example 2 the subject matter of Example 1 may comprise that the power control mode selector is configured to select based on the data transmission system being operated in a multi-transmission mode or a single-transmission mode. 
     In Example 3 the subject matter of Examples 1 or 2 may comprise that the power control mode selector is configured to select based on a frequency pairing of a first transmission frequency of the first transmission chain and a second transmission frequency of the second transmission chain. 
     In Example 4 the subject matter of any of the preceding Examples may comprise that the power control mode selector is configured to select based on a transmission power pairing of a first transmission power of the first transmission chain and a second transmission power of the second transmission chain. 
     In Example 5 the subject matter of any of the preceding Examples may comprise that the power control mode selector is configured to select based on a measurement indicative of a leakage of transmission power of the second transmission chain into the first transmission chain. 
     In Example 6 the subject matter of any of the preceding Examples may further comprise a first look-up table, wherein the first look-up table is configured to perform an update process of entries of the first look-up table based on transmission power measurement values obtained while the data transmission system is operated in the closed loop power control mode; and wherein, in the open loop power control mode, the first transmission power controller is configured to set the transmission power of the first transmission chain based on the first look-up table. 
     In Example 7 the subject matter of Example 6 may further comprise an interference indicator configured to enable or disable the update process, wherein the interference indicator is configured to enable the update process if the interference induced by the second transmission chain in the first transmission power controller when operating in the closed loop power control mode is estimated to be small. 
     In Example 8 the subject matter of Examples 6 or 7 may comprise that the first look-up table comprises first entries and second entries, wherein the first entries are target transmission power levels of the first transmission chain, wherein the second entries are setting values for the first transmission power controller, and wherein each setting value corresponds to a respective target transmission power level. 
     In Example 9 the subject matter of Example 8 may further comprise a second look-up table, wherein the second look-up table comprises adjustment values for adjusting the second entries of the first look-up table, the adjustment values being based on one or more of a temperature, a supply voltage and a spatial orientation of the data transmission system. 
     In Example 10 the subject matter of Example 9 may comprise that the second look-up table is configured to adjust the second entries of the first look-up table if one or more of a time span since a last update of the second entries of the first look-up table, a change in the temperature, a change in the supply voltage and a change in the spatial orientation of the data transmission system exceeds a respective certain threshold. 
     In Example 11 the subject matter of any one of the preceding Examples may comprise that the data transmission system is comprised in a wireless device. 
     In Example 12 the subject matter of any one of the preceding Examples may comprise that the data transmission system is comprised in a cable-based device. 
     In Example 13 the subject matter of any one of the preceding Examples may further comprise a second transmission power controller comprised in the second transmission chain, wherein the power control mode selector is configured to select the second transmission power controller to operate in the open loop power control mode or in the closed loop power control mode, wherein the selection is based on at least one quantity indicative of interference induced by the first transmission chain in the second transmission power controller when operated in the closed loop power control mode. 
     In Example 14 the subject matter of any one of the preceding Examples may comprise that the first transmission chain is configured to transmit first data via a first antenna and the second transmission chain is configured to transmit second data via a second antenna. 
     In Example 15 the subject matter of any one of the preceding Examples may comprise that the first transmission chain and the second transmission chain are configured to transmit first data and second data via a common antenna. 
     In Example 16 the subject matter of any one of the preceding Examples may comprise that the power control mode selector is implemented in software. 
     In Example 17 the subject matter of any one of the preceding Examples may comprise that the first transmission chain comprises a power amplifier, wherein the first transmission power controller is configured to control an input power of the power amplifier. 
     In Example 18 the subject matter of any one of the preceding Examples may comprise that the first transmission chain comprises a power amplifier, wherein the first transmission power controller is configured to control a power supply of the power amplifier. 
     Example 19 is a multi-transmission communication system comprising a first transmitter; a first transmission power controller configured to control a transmission power of the first transmitter; a second transmitter; a power control mode selector configured to receive at least one quantity and to set the first transmission power controller in an open loop power control mode or a closed loop power control mode based on the at least one quantity; wherein the at least one quantity is indicative of interference induced by the second transmitter in the first transmission power controller when operating in the closed loop power control mode. 
     Example 20 is a method of operating a multi-transmission system, wherein the multi-transmission system is configured to transmit first data using a first transmission chain and second data using a second transmission chain, the method comprising controlling a transmission power of the first transmission chain in an open loop power control mode or in a closed loop power control mode; and selecting the power control mode based on at least one quantity indicative of interference induced by the second transmission chain in the closed loop power control. 
     In Example 21 the subject matter of Example 20 may further comprise controlling the transmission power of the first transmission chain in the open loop power control mode by using a first look-up table; measuring the transmission power of the first transmission chain in the closed loop power control mode; and updating the first look-up table based on measured transmission power values obtained during closed loop power control mode operation. 
     In Example 22 the subject matter of Example 21 may comprise that updating of the first look-up table is enabled only if an interference indicator indicates that the interference induced by the second transmission chain in the closed loop power control is estimated to be below a given threshold. 
     In Example 23 the subject matter of Examples 21 or 22 may comprise that first entries of the first look-up table are target transmission power levels of the first transmission chain, wherein second entries of the first look-up table are setting values for controlling the transmission power of the first transmission chain, and the method may further comprise updating the second entries of the first look-up table so as to obtain a closer correspondence between the target transmission power levels and actual transmission power levels. 
     In Example 24 the subject matter of Example 23 may further comprise adjusting the second entries of the first look-up table on the basis of adjustment values of a second look-up table, wherein the adjustment values are based on one or more of a temperature, a supply voltage and a spatial orientation of the multi-transmission system. 
     Example 25 is a method of updating a first look-up table configured to adjust the transmission power of a transmission chain in an open loop control mode, the method comprises operating the transmission chain in the open loop control mode based on power control entries in the first look-up table which are setting values for controlling the transmission power; switching to a closed loop control mode for operating the transmission chain; measuring the transmission power of the transmission chain in the closed loop power control mode; updating the power control entries in the first look-up table based on measured transmission power values obtained during closed loop control mode operation; and switching back to the open loop control mode for operating the transmission chain based on the updated power control entries in the first look-up table. 
     In Example 26 the subject matter of Example 25 may further comprise enabling or disabling the update process using an interference indicator, wherein the interference indicator is configured to enable the update process only if an interference induced into the transmission chain when operating in the closed loop power control mode is estimated to be below a given threshold. 
     In Example 27 the subject matter of Example 25 may further comprise the power control entries of the first look-up table comprising input values of a power amplifier. 
     In Example 28 the subject matter of Example 25 may further comprise adjusting the power control entries of the first look-up table using adjustment values in a second look-up table, wherein the adjustment values are based on one or more of a temperature, a supply voltage and a spatial orientation of a data transmission system comprising the transmission chain. 
     In Example 29 the subject matter of Example 28 may further comprise adjusting the power control entries of the first look-up table if one or more of a time span since a last update of the power control entries of the first look-up table, a change in the temperature, a change in the supply voltage and a change in the spatial orientation of the data transmission system exceeds a respective certain threshold. 
     Example 30 is a method of operating a multi-transmission system, the method comprising: with a first transmission chain, transmitting first data; with a second transmission chain, transmitting second data; for at least a first time period, operating the first transmission chain in a closed loop power control mode; identifying potential interference induced by the second transmission chain in the first transmission chain; and for at least a second time period and in response to identifying the potential interference, operating the first transmission chain in an open loop power control mode. 
     Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Metadata:
Filing Date: 20160523
Publication Date: 20210824
Grant Date: 20210824
Priority Date: 20150624
Inventors: LANGER, ANDREAS
BRUDER, THOMAS
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W52/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/06", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/42", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 56084022