PATENT DOCUMENT

Publication Number: US-9749871-B2
Application Number: US-201514816971-A
Country: US
Kind Code: B2

Title: Radio frequency systems and methods for overriding network signaling values

Abstract:
Systems and method to improve performance of a radio frequency system while operating in compliance with wireless transmission regulations are provided. One embodiment describes a radio frequency system including an antenna that wirelessly transmits an analog electrical signal at a transmission frequency and receives a first network signaling value from a wireless network. The radio frequency system further includes a controller that determines operational constraints on the radio frequency system based on a region of operation; determines a second network signaling value based on the operational constraints, in which the second network signaling value overrides the first network signaling value; determines operational parameters based on the second network signaling value; and instructs the radio frequency system to implement the operational parameters to facilitate the radio frequency system operating in compliance with the operational constraints.

Claims:
What is claimed is: 
     
       1. A radio frequency system comprising:
 an antenna configured to:
 wirelessly transmit an analog electrical signal at a transmission frequency; and 
 receive a first network signaling value from a wireless network; and 
 
 a controller communicatively coupled to the antenna, wherein the controller is configured to:
 determine whether the first network signaling value is a default value, wherein the default value is associated with a maximum output power of the radio frequency system; and 
 when the first network signaling value is the default value:
 determine operational constraints on the radio frequency system based at least in part on a region the radio frequency system is operating in; 
 determine a second network signaling value based on the operational constraints, wherein the second network signaling value is different from the first network signaling value and overrides the first network signaling value; 
 determine operational parameters based at least in part on the second network signaling value; and 
 instruct the radio frequency system to implement the operational parameters to facilitate transmitting the analog electrical signal in compliance with the operational constraints. 
 
 
 
     
     
       2. The radio frequency system of  claim 1 , wherein the controller is configured to:
 determine the transmission frequency, wherein the transmission frequency comprises one or more resource blocks assigned to the radio frequency system by a wireless service provider; 
 determine channel frequency, wherein the channel frequency comprises frequencies of a channel that includes the transmission frequency; and 
 determine whether spurious emissions are expected to meet the operational constraints based at least in part on the transmission frequency and the channel frequency, wherein the second network signaling value is determined when the spurious emissions are not expected to meet the operational constraints. 
 
     
     
       3. The radio frequency system of  claim 1 , wherein the controller is configured to:
 determine an output power reduction value based at least in part the second network signaling value; and 
 instruct the radio frequency system to reduce output power by applying the output power reduction value to the maximum output power of the radio frequency system. 
 
     
     
       4. The radio frequency system of  claim 1 , comprising a power supply configured to output a power amplifier supply voltage to a power amplifier to control output power used to transmit the analog electrical signal, wherein:
 the controller is configured to determine an output power reduction value based at least in part on the second network signaling value; 
 the power supply is configured to adjust the power amplifier supply voltage based at least in part on voltage of an input signal to the power amplifier when the output power reduction value is less than a threshold; and 
 the power supply is configured to adjust the power amplifier supply voltage based at least in part on average output power when the output power reduction value is greater than the threshold. 
 
     
     
       5. The radio frequency system of  claim 1 , comprising a power supply configured to output a power amplifier supply voltage to a power amplifier to control output power used to transmit the analog electrical signal; wherein:
 the controller is configured to determine proximity of a protected frequency to the transmission frequency; 
 the power supply is configured to adjust the power amplifier supply voltage based at least in part on voltage of an input signal to the power amplifier when the proximity is greater than a threshold; and 
 the power supply is configured to adjust the power amplifier supply voltage based at least in part on average output power when the proximity is less than the threshold. 
 
     
     
       6. The radio frequency system of  claim 1 , comprising a filter configured to filter the analog electrical signal before transmission when enabled; wherein:
 the controller is configured to determine an output power reduction value based at least in part on the second network signaling value and location of a protected frequency; 
 the filter is configured to adjust filter rejection based at least in part on the output power reduction value; and 
 the filter is configured to adjust target frequency based at least in part on location of the protected frequency. 
 
     
     
       7. The radio frequency system of  claim 1 , wherein:
 the radio frequency system is configured to transmit the analog electrical signal using a first channel and a second channel when carrier aggregation is enabled; and 
 the controller is configured to disable carrier aggregation when the second network signaling value is determined. 
 
     
     
       8. The radio frequency system of  claim 1 , wherein the controller is configured to restrict location of the transmission frequency when the second network signaling value is determined. 
     
     
       9. The radio frequency system of  claim 1 , wherein the first network signaling value is NS_01 or CA_NS_01. 
     
     
       10. A method for operating a radio frequency system, comprising:
 determining, using a processor of the radio frequency system, whether a received network signaling value is a default value, wherein the received network signaling value is received from a network communicatively coupled to the radio frequency system; 
 instructing, using the processor, the radio frequency system to wirelessly transmit an analog electrical signal to the network by implementing a first set of operational parameters when the received network signaling value is not the default value; and 
 when the receive network signaling value is the default value:
 determining, using the processor, operational constraints on operation of the radio frequency system; 
 determining, using the processor, an override network signaling value based at least in part on the operational constraints; 
 determining, using the processor, a second set of operational parameters, wherein determining the second set of operational parameters comprises:
 determining an output power reduction value based at least in part on the override network signaling value; 
 determining power amplifier operational parameters based at least in part on the output power reduction value; 
 determining filtering operational parameters based at least in part on the output power reduction value; 
 determining carrier aggregation operational parameters based at least in part on location of a protected frequency, wherein the operational constraints comprise the protected frequency; 
 determining channel configuration operational parameters based at least in part on location of the protected frequency; 
 or any combination thereof; and 
 
 instructing, using the processor, the radio frequency system to wirelessly transmit the analog electrical signal to the network using the second set of operational parameters determined based at least in part on the override network signaling value. 
 
 
     
     
       11. The method of  claim 10 , wherein determining the operational constraints comprises:
 determining a region in which the radio frequency system is operating; and 
 determining protected frequencies and spurious emission limits associated with the region. 
 
     
     
       12. The method of  claim 10 , comprising, when the receive network signaling value is the default value:
 determining, using the processor, an output power reduction value based at least in part on the override network signaling value, channel bandwidth, a starting resource block assigned to the radio frequency system, and number of resource blocks assigned to the radio frequency system; and 
 determining, using the processor, whether network signaling override is enabled; 
 wherein instructing the radio frequency system to wirelessly transmit the analog electrical signal to the network using the second set of operational parameters comprises:
 instructing the radio frequency system to reduce output power based at least in part on the output power reduction value when network signaling override is enabled; and 
 instructing the radio frequency system to adjust power amplifier operational parameters, filtering operational parameters, or both to achieve the output power reduction value when network signaling override is not enabled. 
 
 
     
     
       13. The method of  claim 10 , wherein:
 the power amplifier operational parameters comprise a radio frequency gain index, a peak power amplifier supply voltage, an amplitude digital predistortion coefficient, a phase digital predistortion coefficient, an envelope tracking detrough function, a tracking mode, or any combination thereof; 
 the filtering operational parameters comprise whether to enable a filter, filter rejection of the filter, target frequency of the filter, or any combination thereof; 
 the carrier aggregation operational parameters comprise whether to enable carrier aggregation, transmission frequency to use when carrier aggregation is disabled, or both; and 
 the channel configuration operational parameters comprise restrictions on bandwidth of a channel used to transmit the analog electrical signal. 
 
     
     
       14. The method of  claim 10 , wherein the default value of the received network signaling value is NS_01 or CA_NS_01. 
     
     
       15. A tangible, non-transitory, computer-readable medium configured to store instructions executable by processing circuitry of an electronic device, wherein the instructions comprise instructions to:
 determine, using the processing circuitry, a set of operational constraints on a radio frequency system associated with a region the electronic device is designed to operate in; 
 determine, using the processing circuitry, a first set of operational parameters that causes operation of the radio frequency system to not be in compliance with the set of operational constraints; 
 associate, using the processing circuitry, the first set of operational parameters with an override network signaling value to enable the radio frequency system to:
 determine the override network signaling value when the first set of operational parameters is detected and a received network signaling value is a default value; and 
 operate using the override network signaling value instead of the received network signaling value 
 
 associate, using the processing circuitry, the override network signaling value to an output power reduction value; 
 associate, using the processing circuitry, the output power reduction value to power amplifier operational parameters, wherein the power amplifier operational parameters comprise a radio frequency gain index, a peak power amplifier supply voltage, an amplitude digital predistortion coefficient, a phase digital predistortion coefficient, a detrough function, a tracking mode, or any combination thereof; and 
 associate, using the processing circuitry, the output power reduction value to filtering operational parameters, wherein the filtering operational parameters comprise whether to enable a filter, filter rejection of the filter, target frequency of the filter, or any combination thereof. 
 
     
     
       16. The computer-readable medium of  claim 15 , wherein the first set of operational parameters comprises a channel frequency and a transmission frequency, wherein:
 the transmission frequency comprises resource blocks assigned to the radio frequency system to transmit the analog electrical signal; and 
 the channel frequency comprises frequencies of a channel that includes the transmission frequency. 
 
     
     
       17. The computer-readable medium of  claim 15 , comprising instructions to associate, using the processing circuitry, the first set of operational parameters to one of an override enable setting or an override disable setting, wherein:
 the override enable setting instructs the radio frequency system to reduce maximum output power by the output power reduction value; and 
 the override disable setting instructs the radio frequency system to implement the power amplifier operational parameters, the filtering operational parameters, or both. 
 
     
     
       18. The computer-readable medium of  claim 15 , wherein the default value of the received network signaling value is NS_01 or CA_NS_01. 
     
     
       19. An electronic device, comprising:
 a radio frequency system configured to wirelessly transmit and receive analog electrical signals, wherein the radio frequency system comprises:
 a network signaling value override look-up-table configured to associate a first set of operational parameters to an override network signaling value, wherein the radio frequency system is configured to:
 determine whether a received network signaling value is associated with a maximum output power of the radio frequency system; and 
 determine the override network signaling value using the network signaling value override look-up-table when the received network signaling value is associated with the maximum output power, wherein the radio frequency system is configured to transmit an analog electrical signal based on the override network signaling value instead of a received network signaling value; and 
 
 an output power reduction look-up-table configured to associate a second set of operational parameters to an output power reduction value, wherein the second set of operational parameters comprises the override network signaling value and the radio frequency system is configured to adjust operational parameters used to transmit the analog electrical signal based at least in part on the output power reduction value. 
 
 
     
     
       20. The electronic device of  claim 19 , wherein the radio frequency system comprises a power amplifier operational parameter look-up-table configured to associate a third set of operational parameters to a set of power amplifier operational parameters, wherein:
 the third set of operational parameters comprises the output power reduction value and proximity of a transmission frequency to a protected frequency; 
 the set of power amplifier operational parameters comprises a radio frequency gain index, a peak power amplifier supply voltage, an amplitude digital predistortion coefficient, a phase digital predistortion coefficient, a detrough function, a tracking mode, or any combination thereof; and 
 the radio frequency system is configured to transmit the analog electrical signal by implementing the set of power amplifier operational parameters. 
 
     
     
       21. The electronic device of  claim 19 , wherein the radio frequency system comprises a filtering operational parameter look-up-table configured to associate a third set of operational parameters to a set of filtering operational parameters, wherein:
 the third set of operational parameters comprises the output power reduction value and location of a protected frequency; 
 the set of filtering operational parameters comprises an enable setting, a target frequency, a filter rejections, or any combination thereof; and 
 the radio frequency system is configured to transmit the analog electrical signal by implementing the set of filtering operational parameters. 
 
     
     
       22. The electronic device of  claim 19 , wherein:
 the first set of operational parameters comprises a channel frequency and a transmission frequency; and 
 the second set of operational parameters comprises the override network signaling value, a channel bandwidth, a starting resource block, number of assigned resource blocks, or any combination thereof. 
 
     
     
       23. The electronic device of  claim 19 , wherein the electronic device comprises a portable phone, a media player, a personal data organizer, a handheld game platform, a tablet device, a computer, or any combination thereof.

Description:
BACKGROUND 
     The present disclosure relates generally to radio frequency systems and, more particularly, to controlling spurious emissions produced by a radio frequency system. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Many electronic devices may include a radio frequency system to facilitate wireless communication of data with other electronic devices and/or a network. The radio frequency system may include a transceiver that receives a digital representation of data as a digital electrical signal and generates an analog representation of the data as an analog electrical signal. A power amplifier may then amplify the analog electrical signal to a desired output power for wireless transmittance via an antenna at a desired radio frequency, such as one or more assigned resource blocks within a channel. As used herein, a “channel” is intended to describe a range of frequencies and a “resource block” is intended to describe a smallest assignable range of frequencies within the channel. 
     To facilitate operating in varying regions (e.g. countries, jurisdictions, geographies), the radio frequency may be designed to be capable of transmitting at multiple different frequencies. However, different regions may have different regulatory bodies, which set wireless transmission regulations for that region. For example, the Federal Communications Commission (FCC) sets wireless transmission regulations for the United States, the Industry Canada (IC) sets wireless transmission regulations for Canada, the Ministry of Internal Affairs and Communications (MIC) sets wireless transmission regulations for Japan, and the European Telecommunications Standards Institute (ETSI) sets wireless transmission regulations for Europe. As such, the wireless transmission regulations may vary in different regions. 
     To facilitate compliance with wireless transmission regulations in a region, a wireless service provider may transmit a network signaling value (NS_XX or CA_NS_XX). Based on the network signaling value, the radio frequency system may adjust operation to be in compliance with the wireless transmission regulations. Thus, compliance with the wireless transmission regulations may be reliant on receiving the correct network signaling value from the wireless service provider. In other words, if the correct network signaling value is not received, the radio frequency system may operate out of compliance with the wireless transmissions regulations. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure generally relates to improving performance of a radio frequency system while operating in compliance with wireless transmission regulations. Generally, the radio frequency system may wirelessly communicate data with other electronic devices and/or a network by modulating radio waves at an assigned transmission frequency (e.g., one or more resource blocks) based on an analog representation of the data (e.g., an analog electrical signal). However, the analog electrical signal may contain noise introduced by the components in the radio frequency system that causes the radio frequency system to transmit spurious emissions at frequencies other than the transmission frequency. 
     However, regulatory bodies generally set wireless transmission regulations that govern acceptable amount of spurious emissions transmitted, particularly at protected or restricted frequencies, by radio frequency systems operating within their regions (e.g., jurisdictions). To facilitate compliance, a wireless service provider may transmit a network signaling value to a radio frequency system connected to its network. Based on the received network signaling value, the radio frequency system may adjust operational parameters to be in compliance with the wireless transmission regulations. Thus, in such embodiments, compliance with the wireless transmission regulations may be premised on the radio frequency system receiving the correct network signaling value. 
     However, in some instances, the radio frequency system may not receive the correct network signaling value, thereby causing the radio frequency system to operate out of compliance with the wireless transmission regulations. As such, regulatory bodies may require that radio frequency systems operate in compliance with wireless transmission regulations regardless of network signaling values received. 
     Since radio frequency systems may be designed to operate in different regions with varying wireless transmission regulations, this may cause the radio frequency system to unduly adjust operational parameters even when the radio frequency system may otherwise already be in compliance. In some embodiments, adjusting the operational parameters may affect performance of the radio frequency system. In other words, adjusting operational parameters when the radio frequency system is already in compliance may unnecessarily impact performance of the radio frequency system. 
     Accordingly, to improve operation, a radio frequency system may dynamically adjust operational parameters to be in compliance with wireless transmission regulations even when the correct network signaling value is not received. For example, in some embodiments, the radio frequency system may determine the region (e.g., country) it is operating in. Based on the region, the radio frequency system may then determine protected frequencies within that region, and/or spurious emission limits for those protected frequencies. In this manner, the radio frequency system may determine the operational constraints (e.g., wireless transmission regulations) even when a correct network signaling value is not received. 
     Based on the operational constraints, the radio frequency system may then determine operational parameters to implement. More specifically, the radio frequency system may determine whether operating based on a network signaling value, which may be received from a wireless service provider, is expected to be in compliance with the operational constraints. In some embodiments, the radio frequency system may whether expected to operate in compliance based on the protected frequencies, spurious emission limits, transmission frequency, channel frequency, channel bandwidth, location of the transmission frequencies in the channel frequencies, and the like. 
     When not expected to be in compliance, the radio frequency system may determine an override network signaling value and operate based on the override network signaling value instead of the received network signaling value. More specifically, based at least in part on the override network signaling value, the radio frequency system may determine operational parameters that facilitate operating in compliance with the operational constraints (e.g., wireless transmission regulations). In some embodiments, the operational parameters may include an output power reduction value, power amplifier operational parameters, filtering operational parameters, carrier aggregation operational parameters, and/or channel configuration operational parameters. 
     For example, the radio frequency system may determine the output power reduction value based at least in part on the override network signaling value, the channel bandwidth, a starting assigned resource block, and/or number of assigned resource block. In some embodiments, the radio frequency system may then implement the output power reduction value to reduce output power and, thus, magnitude of spurious emissions. Additionally or alternatively, the radio frequency system may determine other operational parameters based at least in part on the output power reduction value. 
     For example, the radio frequency system may determine power amplifier operational parameters based at least in part on the output power reduction value and/or proximity to protected frequencies. The radio frequency system may then implement the power amplifier operational parameters to increase linearity of a power amplifier and, thus, magnitude of spurious emissions. Additionally, the radio frequency system determine filtering operational parameters based at least in part on the output power reduction value and/or location of protected frequencies. The radio frequency system may then implement the filtering operational parameters to reduce magnitude of spurious emissions at the protected frequencies. 
     Moreover, the radio frequency system may determine carrier aggregation operational parameters and/or channel configuration operational parameters based at least in part on the location of protected frequencies. The radio frequency system may then implement the carrier aggregation operational parameters and/or channel configuration operational parameters to control transmission frequency and, thus, magnitude and/or location of spurious emissions. In this manner, the radio frequency system may operate in compliance with wireless transmission regulations even when a correct network signaling value is not received. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of a electronic device with a radio frequency system, in accordance with an embodiment; 
         FIG. 2  is an example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 3  is an example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 4  is an example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 5  is block diagram of a portion of the radio frequency system of  FIG. 1 , in accordance with an embodiment; 
         FIG. 6  is a plot of a first analog electrical signal transmitted by the radio frequency system, in accordance with an embodiment; 
         FIG. 7  is a plot of a second analog electrical signal transmitted by the radio frequency system, in accordance with an embodiment; 
         FIG. 8  is a flow diagram of a process for operating the radio frequency system, in accordance with an embodiment; 
         FIG. 9  is an example of an output power reduction look-up-table, in accordance with an embodiment; 
         FIG. 10  is a flow diagram of a process for determining an override network signaling value, in accordance with an embodiment; 
         FIG. 11  is an example of a network signaling value override look-up-table, in accordance with an embodiment; 
         FIG. 12  is a flow diagram of a process for using an output power reduction value, in accordance with an embodiment; 
         FIG. 13  is a flow diagram of a process for determining power amplifier operational parameters, in accordance with an embodiment; 
         FIG. 14  is an example of a power amplifier operational parameter look-up-table, in accordance with an embodiment; 
         FIG. 15  is a flow diagram of a process for determining filtering operational parameters, in accordance with an embodiment; 
         FIG. 16  is a flow diagram of a process for determining carrier aggregation operational parameters, in accordance with an embodiment; 
         FIG. 17  is a plot of a first analog electrical signal with carrier aggregation enabled and a second analog electrical signal with carrier aggregation disabled transmitted by the radio frequency system, in accordance with an embodiment; 
         FIG. 18  is a flow diagram of a process for determining channel configuration operational parameters, in accordance with an embodiment; 
         FIG. 19  is a plot of a first analog electrical signal using a 10 MHz channel bandwidth and a second analog electrical signal using a 5 MHz channel bandwidth transmitted by the radio frequency system, in accordance with an embodiment; and 
         FIG. 20  is a flow diagram of a process for determining configuration data used to operate the radio frequency system, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. These described embodiments are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but may nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     As mentioned above, an electronic device may include a radio frequency system to facilitate wirelessly communication of data with another electronic device and/or a network. More specifically, the radio frequency system may modulate radio waves at a transmission frequency, such as an assigned one or more resource blocks in a channel, to enable the electronic device to communicate via a personal area network (e.g., Bluetooth network), a local area network (e.g., an 802.11x Wi-Fi network), and/or a wide area network (e.g., a 4G or LTE cellular network). In other words, the radio frequency systems may utilize various wireless communication protocols to facilitate communication of data. 
     Nevertheless, radio frequency systems may generally be operationally similar regardless of the wireless communication protocol used. For example, to transmit data, processing circuitry may generate a digital representation of the data as a digital electrical signal and a transceiver (e.g., a transmitter and/or a receiver) may then convert the digital electrical signal into one or more analog electrical signals. The analog electrical signal may then be amplified by a power amplifier, filtered by one or more filters, and transmitted by an antenna. 
     However, along with the data, the radio frequency system may also transmit spurious emissions. As used herein, “spurious emissions” are intended to describe wireless signals transmitted at frequencies other than the assigned transmission frequency. In some embodiments, the spurious emissions may be the result of noise introduced into the analog electrical signal by the transceiver and/or the power amplifier. For example, the transceiver may introduce noise as a result of digital signal modulation or analog impairments in its modulator, mixer, or driver amplifier. Additionally, the power amplifier may introduce noise as a result of non-linearities. 
     In some instances, spurious emissions may leak into frequencies surrounding the transmission frequency. For example, when a radio frequency system is assigned fifty resource blocks (e.g., 10 MHz) in a channel between 2500.5-2510.5 MHz, the radio frequency system may generate spurious emissions between 2490.5-2500.5 MHz and between 2510.5-2520.5 MHz due to third order intermodulation products. Additionally, the radio frequency system may generate spurious emissions between 2480.5-2490.5 MHz and between 2520.5-2530.5 MHz due to fifth order intermodulation products, and so on with higher odd order intermodulation products. 
     Additionally, spurious emissions may occur at harmonics of the transmission frequency. For example, continuing with the above example, the radio frequency system may generate spurious emissions between 5001-5021 MHz due to a second harmonic. Additionally, the radio frequency system may generate spurious emissions between 7501.5-7531.5 MHz due to a third harmonic, and so on with higher harmonics. 
     However, regulatory bodies may set allowable spurious emissions limits for radio frequency systems operating in their regions (e.g., jurisdictions). More specifically, some regulatory bodies may restrict radio frequency systems from transmitting spurious emissions above a specified limit at restricted or protected frequencies. For example, the FCC mandates that spurious emissions transmitted in the United States should be less than −13 dBm at frequencies between 2490.5-2496 MHz and should be less than −25 dBm at frequencies less than 2490.5 MHz. 
     In fact, a regulatory body may authorize only radio systems that comply with its wireless transmission regulations to operate in its region. As such, a radio frequency system should operate such that spurious emissions are lower than the set limits. For example, when operating in the United States, the radio frequency system transmitting at 2500-2510 MHz should operate such that the third order intermodulation products (e.g., between 2490.5-2500.5) are less than −13 dBm and the fifth order intermodulation products (e.g., between 2480.5 and 2490.5) are less than −25 dBm. 
     To facilitate compliance, a wireless service provider may transmit a network signaling value (NS_XX) to radio frequency systems connected to its network. In this manner, the radio frequency system may determine wireless transmission regulations governing the region it is operating in. Based on the received network signaling value, the radio frequency system may adjust operational parameters to be in compliance with the wireless transmission regulations. 
     Thus, in such embodiments, compliance with the wireless transmission regulations may be premised on the radio frequency system receiving the correct network signaling value. However, in some instances, the radio frequency system may fail to receive the network signaling value, for example, if the wireless service provider inadvertently turns off transmission of the network signaling value or transmits an incorrect network signaling value. In such instances, the radio frequency system may operate out of compliance with the wireless transmission regulations. 
     Thus, some regulatory bodies may require that a radio frequency system operates in compliance with wireless transmission regulations regardless of network signaling values received from the wireless service provider. However, since the radio frequency system may be designed to operate in different regions with varying wireless transmission regulations, this may cause the radio frequency system to unduly adjust operational parameters even when the radio frequency system may otherwise already be in compliance. 
     In some embodiments, adjusting the operational parameters may affect performance of the radio frequency system. For example, reducing output power of the radio frequency system may reduce distance the radio frequency system is able to communicate and/or integrity of received wireless signals. Additionally, increasing linearity of a power amplifier in the radio frequency system may increase power consumption of the radio frequency system. In other words, adjusting operational parameters when the radio frequency system is already in compliance may unnecessarily impact performance of the radio frequency system. 
     Accordingly, as will be described in more detail below, the present disclosure provides techniques to facilitate compliance with wireless transmission regulations without unnecessarily adjusting operational parameters. In some embodiments, a radio frequency system may determine operational constraints (e.g., wireless transmission regulations) irrespective of a network signaling value received. For example, the radio frequency system may determine the country (e.g., region) it is operating in and determine protected frequency bands and spurious emission limits for that country. In this manner, the radio frequency system may determine the wireless transmission regulations even when a correct network signaling value is not received. 
     Based at least in part on the operational constraints, the radio frequency system may determine operational parameters to implement. For example, the radio frequency system may determine whether transmitting an analog electrical signal is expected to produce spurious emissions in protected frequencies that meet the spurious emission limits based on its transmission frequency and channel frequency. In some embodiments, the radio frequency system may determine an override network signaling value to indicate that spurious emissions are not expected to meet limits. 
     As such, when the override network signaling value is determined, the radio frequency system may adjust operational parameters to facilitate compliance with the operational constraints (e.g., spurious emission limits). For example, in some embodiments, the radio frequency system may then use the override network signaling value to override a network signaling value received from the wireless service provider. In such embodiments, the radio frequency system may determine an output power reduction value associated with the override network signaling value. Based on the output power reduction value, the radio frequency system may then reduce its output power and, thus, magnitude of spurious emissions. 
     Additionally or alternatively, the radio frequency system may utilize the override network signaling value and/or the output power reduction value to determine other operational parameters. For example, based on the output power reduction value and/or location of protected frequencies, the radio frequency system may determine power amplifier operational parameters (e.g., radio frequency gain index, power amplifier supply voltage, digital predistortion coefficients, envelope tracking detrough function or shaping table, and/or tracking mode) and/or filtering operational parameters (e.g., enable/disable filter, filter rejection, and/or target frequencies) to reduce magnitude of spurious emissions at the protected frequencies. Additionally, based on location of the protected frequencies, the radio frequency system may determine carrier aggregation operational parameters (e.g., enable/disable carrier aggregation and/or transmission frequency when disabled) and/or channel configuration operational parameters (e.g., channel bandwidth restrictions and/or output power restrictions) to adjust magnitude and/or location of spurious emissions. 
     The radio frequency system may then implement any combination of the operational parameters (e.g., a set of operational parameters) to facilitate operating in compliance with the operational constraints (e.g., wireless transmissions regulations). In fact, since the radio frequency system may operate based on the override network signaling value instead of the received network signaling value, the radio frequency system may operate in compliance even when the correct network signaling value is not received. More specifically, the radio frequency system may determine operational constraints (e.g., wireless transmission regulations) irrespective of the received network signaling value and determine an override network signaling value based on the operational constraints. Based at least in part on the override network signaling value, the radio frequency system may then dynamically adjust its operational parameters. In this manner, unnecessary operational parameter adjustments may be obviated, thereby improving performance of the radio frequency system. 
     To help illustrate, an electronic device  10  that may utilize a radio frequency system  12  is described in  FIG. 1 . As will be described in more detail below, the electronic device  10  may be any suitable electronic device, such as a handheld computing device, a tablet computing device, a notebook computer, and the like. As depicted, the electronic device  10  includes the radio frequency system  12 , input structures  14 , memory  16 , one or more processor(s)  18 , one or more storage devices  20 , a power source  22 , input/output ports  24 , and an electronic display  26 . The various components described in  FIG. 1  may include hardware elements (including circuitry), software elements (including instructions stored on a non-transitory computer-readable medium), or a combination of both hardware and software elements. 
     It should be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in the electronic device  10 . Additionally, it should be noted that the various depicted components may be combined into fewer components or separated into additional components. For example, the memory  16  and a storage device  20  may be included in a single component. 
     As depicted, the processor  18  is operably coupled with memory  16  and the storage device  20 . More specifically, the processor  18  may execute instruction stored in memory  16  and/or the storage device  20  to perform operations in the electronic device  10 , such as instructing the radio frequency system  12  to communicate with another device. As such, the processor  18  may include one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. Additionally, memory  16  and/or the storage device  20  may be a tangible, non-transitory, computer-readable medium that stores instructions executable by and data to be processed by the processor  18 . For example, the memory  16  may include random access memory (RAM) and the storage device  20  may include read only memory (ROM), rewritable flash memory, hard drives, optical discs, and the like. 
     Additionally, as depicted, the processor  18  is operably coupled to the power source  22 , which provides power to the various components in the electronic device  10 . As such, the power source  22  may includes any suitable source of energy, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. Furthermore, as depicted, the processor  18  is operably coupled with I/O ports  24 , which may enable the electronic device  10  to interface with various other electronic devices, and input structures  14 , which may enable a user to interact with the electronic device  10 . Accordingly, the inputs structures  14  may include buttons, keyboards, mice, trackpads, and the like. Additionally, in some embodiments, the electronic display  26  may include touch sensitive components. 
     In addition to enabling user inputs, the electronic display  26  may display image frames, such as a graphical user interface (GUI) for an operating system, an application interface, a still image, or video content. As depicted, the electronic display  26  is operably coupled to the processor  18 . Accordingly, the image frames displayed by the electronic display  26  may be based on display image data received from the processor  18 . 
     As depicted, the processor  18  is also operably coupled with the radio frequency system  12 , which may facilitate communicatively coupling the electronic device  10  to one or more other electronic devices and/or networks. For example, the radio frequency system  12  may enable the electronic device  10  to communicatively couple to a personal area network (PAN), such as a Bluetooth network, a local area network (LAN), such as an 802.11x Wi-Fi network, and/or a wide area network (WAN), such as a 4G or LTE cellular network. 
     As can be appreciated, the radio frequency system  12  may enable communication using various communication protocols. However, operational principles of the radio frequency system  12  may be similar for each of the communication protocols (e.g., Bluetooth, LTE, 802.11x Wi-Fi, etc). For example, regardless of communication protocol, the radio frequency system  12  generally converts a digital electrical signal containing data desired to be transmitted into an analog electrical signal using a transceiver. The analog electrical signal may then be amplified using a power amplifier, filtered using a filter, and transmitted using an antenna. In other words, the techniques described herein may be applicable to any suitable radio frequency system  12  that operates in any suitable manner regardless of communication protocol used. 
     As described above, the electronic device  10  may be any suitable electronic device. To help illustrate, one example of a handheld device  10 A is described in  FIG. 2 , which may be a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. For example, the handheld device  10 A may be a smart phone, such as any iPhone® model available from Apple Inc. As depicted, the handheld device  10 A includes an enclosure  28 , which may protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  28  may surround the electronic display  26 , which, in the depicted embodiment, displays a graphical user interface (GUI)  30  having an array of icons  32 . By way of example, when an icon  32  is selected either by an input structure  14  or a touch sensing component of the electronic display  26 , an application program may launch. 
     Additionally, as depicted, input structures  14  may open through the enclosure  28 . As described above, the input structures  14  may enable a user to interact with the handheld device  10 A. For example, the input structures  14  may activate or deactivate the handheld device  10 A, navigate a user interface to a home screen, navigate a user interface to a user-configurable application screen, activate a voice-recognition feature, provide volume control, and toggle between vibrate and ring modes. Furthermore, as depicted, the I/O ports  24  open through the enclosure  28 . In some embodiments, the I/O ports  24  may include, for example, an audio jack to connect to external devices. Additionally, the radio frequency system  12  may also be enclosed within the enclosure  28  and internal to the handheld device  10 A. 
     To further illustrate a suitable electronic device  10 , a tablet device  10 B is described in  FIG. 3 , such as any iPad® model available from Apple Inc. Additionally, in other embodiments, the electronic device  10  may take the form of a computer  10 C as described in  FIG. 4 , such as any Macbook® or iMac® model available from Apple Inc. As depicted, the tablet device  10 B and the computer  10 C also each includes an electronic display  26 , input structures  14 , I/O ports  24 , and an enclosure  28 . Similar to the handheld device  10 A, the radio frequency system  12  may also be enclosed within the enclosure  28  and internal to the tablet device  10 B and/or the computer  10 C. 
     As described above, the radio frequency system  12  may facilitate communication with other electronic devices and/or a network by wirelessly communicating data. To help illustrate, a portion  34  of radio frequency system  12  is described in  FIG. 5 . As depicted, the portion  34  includes a digital signal generator  36 , digital predistortion circuitry  37 , a transceiver  38 , a power amplifier  40 , a filter bypass  41 , a first filter  42 , a second filter  43 , an antenna  44 , a power amplifier power supply  46 , and a controller  48   
     In the depicted embodiment, the controller  48  may control operation of the radio frequency system  12 . To facilitate controlling operation, the controller  48  may include a controller processor  50  and controller memory  52 . In some embodiments, the controller  48  may instruct the radio frequency system  12  to implement determined operational parameters based at least in part on calibration data  56 . Accordingly, in some embodiments, the controller processor  50  may be included in the processor  18  and/or separate processing circuitry and the controller memory  52  may be included in memory  16  and/or a separate tangible non-transitory computer-readable medium. 
     More specifically, the calibration data  56  may describe operational parameters that may be implemented so that the radio frequency system  12  operates in compliance with wireless transmission regulations. For example, in the depicted embodiment, the calibration data  56  includes one or more network signaling (NS_XX) override look-up-tables (LUTs)  58 , one or more output power reduction LUTs  60 , one or more power amplifier (PA) operational parameter LUTs  62 , one or more filtering operation parameter LUTs  64 , one or more carrier aggregation (CA) operational parameter LUTs  66 , and/or one or more channel configuration operational parameter LUTs  68 . As will be described in more detail below, the calibration data  56  may enable the radio frequency system  12  to determine an output power reduction value, power amplifier operational parameters, filtering operational parameters, channel configuration operational parameters, and/or carrier aggregation operational parameters that may be implemented to facilitate operating in compliance with wireless transmission regulations. 
     Additionally, the digital signal generator  36  may generate a digital representation of data  54  desired to be transmitted from the electronic device  10  by outputting a digital electrical signal. In some embodiments, the digital signal generator  36  may be included in the processor  18  and/or separate processing circuitry, such as a baseband processor or a modem in the radio frequency system  12 . 
     The digital predistortion circuitry  37  may then receive the digital electrical signal from the digital signal generator  36 . Generally, the digital predistortion circuitry  37  may apply digital predistortion to the digital electrical signal to mitigate (e.g., cancel) noise introduced by the radio frequency system  12  (e.g., the transceiver  38  and/or the power amplifier  40 ). For example, the digital predistortion circuitry  37  may perform gain expansion on the digital electrical signal to compensate for compression in the power amplifier  40 . 
     In some embodiments, the digital predistortion circuitry  37  may apply digital distortion based at least in part on an amplitude modulation (AMAM) predistortion coefficient and/or a phase modulation (AMPM) predistortion coefficient. In some embodiments, the controller  48  may determine the predistortion coefficients using the one or more power amplifier operational parameter LUTs  62  and communicate the predistortion coefficients to the digital predistortion circuitry  37 . In this manner, the digital predistortion circuitry  37  may implement operational parameters (e.g., predistortion coefficients) to facilitate the radio frequency system  12  operating in compliance with wireless transmission regulations. 
     Subsequently, the transceiver  38  may receive the digital electrical signal and generate an analog representation of the data  54 . For example, the transceiver  38  may generate an analog representation by outputting an amplitude signal to indicate a desired output power and an analog electrical signal to indicate phase (e.g., whether high or low) of the digital electrical signal. In some embodiments, the controller  48  may instruct the transceiver  38  to generate the analog electrical signal using a radio frequency gain index (RGI) determined using the one or more power amplifier operational parameter LUTs  62 . In this manner, the digital predistortion circuitry  37  may implement operation parameters (e.g., radio frequency gain index) to facilitate the radio frequency system  12  operating in compliance with wireless transmission regulations. 
     Since the output power of the analog electrical signal may be small, the power amplifier  40  may receive and amplify the analog electrical signal by outputting an amplified analog electrical signal. More specifically the power amplifier  40  may selectively connect its output to a power amplifier supply voltage based on the magnitude of the analog electrical signal. As such, the output power of the amplified electrical signal may be based at least in part on the power amplifier supply voltage received from the power amplifier power supply  46 . 
     In some embodiments, the controller  48  may instruct the power amplifier power supply  46  to generate the power amplifier supply voltage based at least in part on an output power reduction value determined using the one or more output power reduction LUTs  60 . Additionally or alternatively, the controller  48  may instruct the power amplifier power supply  46  to generate the power amplifier supply voltage based on a target power amplifier supply voltage (V cc ) determined using the one or more power amplifier operational parameter LUTs  62 . In this manner, the power amplifier power supply  46  may implement operation parameters (e.g., output power reduction value and/or target power amplifier supply voltage) to facilitate the radio frequency system  12  operating in compliance with wireless transmission regulations. 
     As described above, the radio frequency system  12  (e.g., transceiver  38  and/or power amplifier  40 ) may introduce noise into the amplified analog electrical signal. As such, the controller  48  may instruct the radio frequency system  12  to adjust filtering applied to the amplified analog electrical signal based on operational constraints. For example, in the depicted embodiment, the controller  48  may instruct the radio frequency system  12  to connect to (e.g., enable) the filter bypass  41 , thereby bypassing filtering on the amplified analog electrical signal. 
     To filter the amplified analog electrical signal, the controller  48  may instruct the radio frequency system  12  to connect to (e.g., enable) a filter. In some embodiments, the radio frequency system  12  may include multiple filters with different operational parameters (e.g., filter rejection and/or target frequencies). For example, in the depicted embodiment, the controller  48  may instruct the radio frequency system  12  to connect to either the first filter  42  or second filter  43  based on desired filtering operational parameters. Additionally or alternatively, the controller  48  may instruct the radio frequency system  12  to connect to the first filter  42  and instruct the first filter  42  to adjust its operational parameters. 
     In some embodiments, the controller  48  may instruct the radio frequency system  12  to enable the filter bypass  41 , the first filter  42 , or the second filter  43  based at least in part on the one or more filtering operational parameter LUTs  64 . Additionally, in some embodiments, the controller  48  may instruct the first filter  42  to adjust target frequency and/or filter rejection determined using the one or more filtering operational parameter LUTs  64 . In this manner, the radio frequency system  12  may implement operation parameters (e.g., enable/disable of filters, target frequencies, and/or filter rejection) to facilitate the radio frequency system  12  operating in compliance with wireless transmission regulations. 
     The analog electrical signal may then be wirelessly transmitted to another electronic devices and/or a network via the antenna  44  as modulated radio waves. In some embodiments, the controller  48  may instruct the antenna  44  regarding the transmission frequency and/or the transmission bandwidth to use for transmission. For example, the antenna  44  may enable carrier aggregation to increase transmission bandwidth. As such, the controller  48  may instruct the antenna  44  to enable/disable carrier aggregation and/or transmission frequency to use when carrier aggregation is disabled based at least in part on the one or more carrier aggregation operational parameter LUTs  66 . Additionally, the controller  48  may instruct the antenna  44  to restrict channel bandwidth and/or output power in edge frequencies based at least in part on channel configuration operational parameters determined using the one or more channel configuration operational parameter LUTs  68 . In this manner, the antenna  44  may implement operation parameters (e.g., enable/disable carrier aggregation, transmission frequency to use, channel bandwidth restriction and/or output power restriction) to facilitate the radio frequency system  12  operating in compliance with wireless transmission regulations. 
     As described above, noise or distortion introduced by the radio frequency system  12  may result in spurious emissions at frequencies other than the desired transmission frequency. To help illustrate,  FIGS. 6 and 7  describe examples of analog electrical signals transmitted by the radio frequency system  12 . More specifically,  FIG. 6  describes a first analog electrical signal  70  that is transmitted when the radio frequency system  12  is assigned fifty resource blocks and  FIG. 7  describes a second electrical signal  72  that is transmitted when the radio frequency system  12  is assigned one resource block. In the depicted embodiments, the radio frequencies are divided into channels with bandwidths of 10 MHz. As such,  FIGS. 6 and 7  describe the magnitude of the analog electrical signals  70  and  72  in a first channel  74  between 2490.5-2500.5 MHz, a second channel  76  between 2500.5-2510.5 MHz, a third channel  78  between 2510.5-2520.5 MHz, a fourth channel  80  between 2520.5-2530.5 MHz, and a fifth channel  82  between 2530.5-2540.5 MHz. It should be noted that the analog electrical signals  70  and  72  are merely intended to be illustrative and not limiting. 
     With regard to  FIG. 6 , since the radio frequency system  12  is assigned fifty resource blocks, the first analog electrical signal  70  has a desired transmission bandwidth of 10 MHz. Thus, as depicted, the first analog electrical signal  70  includes a data portion  84  between 2510.5-2520.5 MHz. More specifically, the data portion  84  includes the analog representation of the data  54  desired to be wirelessly transmitted to another electronic device and/or a network. 
     However, as described above, noise may be introduced in the radio frequency system  12 , for example, by the transceiver  38 . As such, when the introduced noise is mixed in the power amplifier  40 , intermodulation spurious emissions may result. Generally odd order intermodulation spurious emissions occur near the transmission frequency. In some embodiments, third order intermodulation spurious emissions may occur in channels directly adjacent to the transmission channel, fifth order intermodulation spurious emissions may occur at channels two channels away from the transmission channel, seventh order intermodulation spurious emissions may occur at channels three channels away from the transmission channel, and so on. For example, in the depicted embodiment, third order intermodulation spurious emissions  86  with a 10 MHz bandwidth occur in the second channel  76  and the fourth channel  80 . Additionally, fifth order intermodulation spurious emissions  88  with a 10 MHz bandwidth occur in the first channel  74  and the fifth channel  82 . 
     With regard to  FIG. 7 , since the radio frequency system  12  is assigned one resource block, the second analog electrical signal  72  has a desired transmission bandwidth of 0.2 MHz. In the depicted embodiment, the second analog electrical signal  72  includes a data portion  84  at frequencies between 2510.5-2510.7 MHz. Thus, the second analog electrical signal  72  is located at the edge of the third channel  78 . More specifically, the data portion  84  includes the analog representation of data  54  desired to be wirelessly transmitted to another electronic device and/or a network. 
     However, in addition to the data portion  84 , the analog electrical signal  72  also includes a local oscillator (LO) spurious emission  90  at frequencies between 2515.4-2515.6 MHz and an in-phase quadrature (IQ) spurious emission  92  at frequencies between 2520.3-2520.5 MHz. In some embodiments, the local oscillator spurious emission  90  may be introduced by the transceiver  38  at the central frequencies of the channel (e.g., 2515.5 MHz) since the transceiver  38  is generally tuned to the central frequencies. Additionally, the in-phase quadrature spurious emission  92  may also be introduced by imperfections of the transceiver  38  and occur at frequencies such that the local oscillator spurious emission  90  is between and equidistant from the data portion  84  and the in-phase quadrature spurious emission  92 . 
     Additionally, when the data portion  84 , the local oscillator spurious emissions  90 , and the in-phase quadrature spurious emission  92  are mixed in the power amplifier  40 , intermodulation spurious emissions may result. For example, in the depicted embodiment, third order intermodulation spurious emissions  86  occur in the second channel  76  at frequencies between 2505.4-2505.6 MHz (e.g., as a result of intermodulation between the data portion  84  and local oscillator spurious emission  90 ) and at frequencies between 2500.5-2500.7 (e.g., as a result of intermodulation between the data portion  84  and the in-phase quadrature spurious emission  92 ). Similarly, third order intermodulation spurious emissions  86  occur in the fourth channel  80  at frequencies between 2525.4-2525.6 MHz and between 2530.3-2530.5 MHz. Additionally, fifth order intermodulation spurious emissions  88  occur in the first channel  74  at frequencies between 2495.4-2495.6 MHz and between 2590.5-2490.7 MHz. Similarly, fifth order intermodulation spurious emissions  88  occur in the fifth channel  82  at frequencies between 2535.4-2535.6 MHz and between 2540.3-2540.5 MHz. 
     Thus, as depicted, the spurious emission  86  and  88  generally decrease in magnitude as distance from the transmission frequency increases. For example, the fifth order intermodulation spurious emissions  88  are generally lower in magnitude than the third order intermodulation spurious emissions  86 . 
     Nevertheless, as described above, wireless transmission regulations may place acceptable limits on spurious emissions (e.g., intermodulation spurious emissions  86  and  88 ), particularly at protected/restricted frequencies. For example, the FCC mandates that spurious emissions between 2490.5-2496 MHz must be less than −13 dBm and that spurious emissions less than 2490.5 MHz must be less than −25 dBm. Thus, the analog electrical signals  70  and  72  result in fifth order intermodulation spurious emissions  88  occurring in the protected frequencies between 2490.5-2496 MHz. Additionally, the analog electrical signals  70  and  72  result in higher odd order intermodulation spurious emissions occurring in protected frequencies less than 2490.5 MHz. As such, to operate within the United States, the radio frequency system  12  should operate such that fifth order intermodulation spurious emission  88  are less than −13 dBm and the higher odd order intermodulation spurious emissions are less than −25 dBm. 
     One embodiment of a process  94  for controlling operation of a radio frequency system  12  is described in  FIG. 8 . Generally, the process  94  includes receiving a network signaling value (process block  96 ), determining whether the network signaling value is a default value (decision block  98 ), and operating based on the received network signaling value when the network signaling value is not the default value (process block  100 ). When the network signaling value is the default value, the process  94  includes determining operational constraints (process block  102 ), determining operational parameters (process block  104 ), and operating with determined operational parameters (process block  106 ). In some embodiments, the process  94  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may receive a network signaling value (process block  96 ). In some embodiments, the network signaling value may be transmitted by a wireless service provider when the radio frequency system  12  connects to its network. As such, the antenna  44  may receive an analog representation of the network signaling value, the transceiver  38  may convert the analog representation to a digital representation of the network signaling value, and communicate the digital representation to the controller  48 . 
     The controller  48  may then determine whether the network signaling value is equal to a default value, such as NS_ 01  or CA_NS_ 01  (decision block  98 ). In some embodiments, a wireless service provider may switch from transmitting the default network signaling value to a different network signaling value to indicate different wireless transmission regulations. Thus, in some instances, it is possible for the wireless service provide to inadvertently transmit the default network signaling value instead of the different network signaling value. 
     Generally, the default network signaling value may correspond with a maximum output power that the radio frequency system  12  is designed to operate at. As such, wireless transmission regulations associated with the default network signaling value may permit more spurious emissions than wireless transmission regulations associated with other network signaling values. In other words, operating based on one of the other network signaling values may still meet wireless transmission regulations associated with the default network signaling value, but not vice versa. 
     As such, when not the default network signaling value, the controller  48  may instruct the radio frequency system  12  to operate based on the received network signaling value (process block  100 ). More specifically, the radio frequency system  12  may reduce output power such that the radio frequency system  12  operates in compliance with wireless transmission regulations associated with the received network signaling value. To determine the reduced output power, the controller  48  may apply an output power reduction value to the maximum output power of the radio frequency system  12 . In some embodiments, the controller  48  may determine the output power reduction value algorithmically. In other embodiments, the controller  48  may determine the output power reduction using the one or more output power reduction LUTs  60 . 
     To help illustrate, one example of an output power reduction LUT  60  is described in  FIG. 9 . More specifically, the described output power reduction LUT  60  is used to determine output power reduction values when the network signaling value is NS_ 04 . Additional output power reduction LUTs  60  may be used to determine output power reduction values for other network signaling values. It should be appreciated that the output power reduction LUT  60  described in  FIG. 9  is merely intended to be illustrative and not limiting. 
     In the depicted embodiment, the output power reduction LUT  60  associates a set of operational parameters (e.g., a channel bandwidth, a starting resource block (RB) in a transmission channel, and number of assigned resource blocks) to an output power reduction value. For example, when the channel bandwidth is 10 MHz and the starting resource block is between 0-12, a first row  108  indicates that the associated output reduction value is 3 dB. When the channel bandwidth is 10 MHz, the starting resource block is between 13-36, and the number of assigned resource block is greater than 37, a second row  110  indicates that the associated output power reduction value is 2 dB. When the channel bandwidth is 10 MHz and the starting resource block is between 37-49, a third row  112  indicates that the associated output power reduction value is 3 dB. 
     Additionally, when the channel bandwidth is 20 MHz and the starting resource block is between 0-24, a fourth row  114  indicates that the associated output power reduction value is 3 dB. When the channel bandwidth is 20 MHz, the starting resource block is between 25-74, and the number of assigned resource blocks is greater than 74, a fourth row  114  indicates that the associated output power reduction value is 2 dB. When the channel band width is 20 MHz and the starting resource block is between 75-99, a sixth row  118  indicates that the associated output power reduction value is 3 dB. Although only six rows are depicted, it should be appreciated that the output power reduction LUT  60  may associate additional sets of operational parameters (e.g., channel bandwidth, starting resource block, and number of assigned resource blocks) to a corresponding output power reduction value. 
     Thus, using the one or more output power reduction LUTs  60 , the controller  48  may determine an output power reduction value associated with the received network signaling value. The controller  48  may then determine a reduced output power by subtracting the output power reduction value from a maximum output power. For example, when the maximum output power is 23 dB and the output power reduction value is 3 dB, the controller  48  may determine that the reduced output power is 20 dB. The controller  48  may then instruct the radio frequency system  12  to implement the reduced output power, for example, by instruct the power amplifier power supply  46  to adjust the power amplifier supply voltage output to the power amplifier  40 . 
     Returning to the process  94  described in  FIG. 8 , when the default network signaling value is received, the controller  48  may determine operational constraints on the radio frequency system  12  (process block  102 ). As used herein, “operational constraints” are intended to describe factors that act to limit or restrict operation of the radio frequency system  12  in some way, such as wireless transmission regulations. For example, the operational constraints may include protected frequencies and/or spurious emission limits for a specific region. 
     Thus, in some embodiments, the controller  48  may determine a region in which the radio frequency system  12  is operating (process block  120 ). Various techniques may be utilized to determine the region. For example, the controller  48  may utilize a global positioning system (GPS) to determine the location of the radio frequency system  12  and, thus, the region it is operating in. Additionally or alternatively, the controller  48  may receive an indication of the region from the wireless service provider, a communicatively coupled network, and/or another communicatively coupled electronic device. 
     Based on the region, the controller  48  may determine protected frequencies in that region (process block  122 ) and spurious emission limits in that region (process block  124 ). In some embodiments, associations of regions with protected frequencies and/or spurious emissions limits may be stored in the controller memory  52 . Thus, in such embodiments, the controller  48  may retrieve the associations and input the determined region to determine protected frequencies and/or spurious emissions limits for that region. 
     In other embodiments, the associations may be stored in a communicatively coupled device (e.g., a server). Thus, in such embodiments, the controller  48  may instruct the radio frequency system  12  to communicate the determined region to the other device. In response, the other device may transmit the protected frequencies and/or spurious emissions limits for that region. In this manner, the controller  48  may determine operational constraints even when the correct network signaling value is not received from a wireless service provider. 
     Based on the operational constraints, the controller  48  may determine operational parameters for the radio frequency system  12  (process block  104 ). In some embodiments, the operational parameters may include an output power reduction value, power amplifier operational parameters, filtering operational parameters, channel configuration operational parameters, and/or carrier aggregation operational parameters. To facilitate determining the operational parameters, the controller  48  may determine an override network signaling value. 
     One embodiment of a process  126  for determining the override network signaling value is described in  FIG. 10 . Generally, the process  126  includes determining channel frequency (process block  128 ), determining transmission frequency (process block  130 ), determining whether spurious emissions are likely to meet operational constraints (decision block  132 ), operating with a received (e.g., default) network signaling value when likely to meet operational constraints (process block  134 ), and determining an override network signaling value otherwise (process block  136 ). In some embodiments, the process  126  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may determine frequencies of the channel that the radio frequency system  12  is assigned to transmit in (process block  128 ). In some embodiments, the channel may be assigned to the radio frequency system  12  by a wireless service provider. Thus, in such embodiments, the radio frequency system  12  may receive an indication of the channel and the frequencies of the channel from the wireless service provider. For example, the antenna  44  may receive an analog representation of the channel frequency, the transceiver  38  may convert the analog representation to a digital representation of the channel frequency, and the controller  48  may determine the channel frequency based on the digital representation. 
     Additionally, the controller  48  may determine frequencies (e.g., resource blocks) in the channel that the radio frequency system  12  is assigned to transmit at (process block  130 ). In some embodiments, the wireless service provider may assign resource blocks to the radio frequency system  12 . Thus, in such embodiments, the radio frequency system  12  may receive an indication of the assigned transmission frequency from the wireless service provider. For example, the antenna  44  may receive an analog representation of the assigned transmission frequency, the transceiver  38  may convert the analog representation to a digital representation of the assigned transmission frequency, and the controller  48  may determine the assigned transmission frequency based on the digital representation. 
     Based on the channel frequency and the transmission frequency, the controller  48  may determine whether spurious emissions are expected to meet the operational constraints on the radio frequency system  12  (decision block  132 ). In some embodiments, the controller  48  may make the determination using the one or more network signaling value (NS_XX) override LUTs  58 . More specifically, the one or more network signaling value override LUTs  58  may indicate an override network signaling value when the radio frequency system  12  is not expected to meet the operational constraints. 
     To help illustrate, one example of a network signaling value override LUT  58  is described in  FIG. 11 . The described network signaling value override LUT  58  is used to determine override network signaling values when the radio frequency system  12  is operating in band  41  (e.g., 2496-2690 MHz). Additional network signaling value override LUTs  58  may be used to determine override network signaling values for other frequency bands. It should be appreciated that the network signaling value override LUT  58  described in  FIG. 11  is merely intended to be illustrative and not limiting. 
     In the depicted embodiment, the network signaling value override LUT  58  associates a set of operational parameters (e.g., channel frequency and transmission frequency) to an override network signaling value. Additionally, the network signaling value override LUT  58  may be used to facilitate compliance with spurious emissions limits for protected frequencies between 2490.5-2496 MHz. As described above, magnitude of spurious emissions may decrease as distance from the transmission frequency increases. For example, when the transmission frequency is 2510.5-2530.5 MHz, a first row  138  indicates an override network signaling value. On the other hand, when the transmission frequency is 2530.5-2550.5, a second row does not indicate an override network signaling value. 
     Additionally, as described above, intermodulation spurious emissions may occur in each channel adjacent the transmission channel. As such, spread of spurious emissions may increase as the channel frequency (e.g., bandwidth) increases. For example, when the channel frequency is 2510.5-2530.5 MHz, a third row  142  indicates an override network signaling value. On the other hand, when the channel frequency is 2510.5-2520.5 MHz, a fourth row  144  does not indicate a network signaling value. 
     Furthermore, as described above, LO spurious emissions and IQ spurious emissions leakage may occur when the transmission frequency does not include the center frequency of the channel. As such, number of spurious emissions may increase when the transmission frequency is not centered. For example, when the channel frequency is 2510.5-2520.5 MHz and the transmission frequency is 2510.5-2510.6 MHz, a fifth row  146  indicates an override network signaling value. On the other hand, when the channel frequency is 2510.5-2520.5 and the transmission frequency is 2515.5-2515.7, a sixth row  148  does not indicate an override network signaling value. Although only six rows are depicted, it should be appreciated that network signaling value override LUT  58  may associate other sets of operational parameters (e.g., channel frequency and transmission frequency) to override network signaling values. 
     Since an override network signaling value is not indicated, operating the radio frequency system  12  with any of operational parameters sets listed in the second row  140 , the fourth row  144 , or the sixth row is expected to meet the operational constraints. Thus, returning to process  126  of  FIG. 10 , the controller  48  may instruct radio frequency system  12  to operate with the received network signaling value when an override network signaling value is not indicated (process block  134 ). 
     On the other hand, since an override network signaling value is indicated, operating the radio frequency system  12  with any of the operational parameter sets listed in the first row  138 , the third row  142 , or the fifth row  146  is not expected to meet the operational constraints. Thus, the controller  48  may instruct radio frequency system  12  to determine the override network signaling value based at least in part on the channel frequency and the transmission frequency (process block  136 ). As described above, the override network signaling value may then be used to determine operational parameters, which when implemented facilitate operation in compliance with operational constraints. 
     Accordingly, returning to process  94  of  FIG. 8 , the controller  48  may then determine operational parameters based at least in part on the override network signaling value. For example, in some embodiments, the controller  48  may determine an output power reduction value (process block  154 ). As described above, the controller  48  may determine the output power reduction value using the one or more output power reduction LUTs  60  based on the override network signaling value. 
     Additionally or alternatively, the controller  48  may determine other operational parameters based at least in part on the override network signaling value and/or the output power reduction value. For example, the controller  48  may determine power amplifier operational parameters (process block  156 ), filtering operational parameters (process block  158 ), channel configuration operational parameters (process block  160 ), and/or carrier aggregation operational parameters (process block  162 ). In some embodiments, various sets of operational parameters may enable the radio frequency system  12  to operate in compliance with the operational constraints. For example, using the output power reduction value to reduce output power and adjusting power amplifier operational parameters to improve linearity may both enable the radio frequency system  12  to operate in compliance with operational constraints. 
     However, adjustments to different operational parameters may have varying affects on the radio frequency system  12 . For example, using the output power reducing value to reduce output power may reduce transmission distance of the radio frequency system  12  and/or integrity of received signals. On the hand, adjusting power amplifier operational parameters to increase linearity may increase power consumption of the radio frequency system  12 . As such, in some embodiments, the controller  48  may adjust different types of operational parameters to facilitate meeting operational constraints for different based on operational parameters of the radio frequency system  12 . 
     To help illustrate, one embodiment of a process  154  for using operational parameters of the radio frequency system  12  is described in  FIG. 12 . Generally, the process  164  includes determining the output power reduction value (process block  166 ), determining whether network signaling override is enabled (decision block  168 ), implementing the output power reduction value when enabled (process block  170 ), and determining other operational parameters when not enabled (process block  172 ). In some embodiments, the process  164  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may determine the output power reduction value (process block  166 ). As described above, the controller  48  determine the output power reduction value using the one or more output power reduction LUTs  60  based on the override network signaling value. For example, the first row  138  of the network signaling value override LUT  58  described in  FIG. 11  indicates that the channel bandwidth is 20 MHz, the override network signaling value is NS_ 04 , and the starting resource block is 0. Similarly, the third row  142  indicates that the channel bandwidth is 20 MHz, the override network signaling value is NS_ 04 , and the starting resource block is 0. Thus, based on the fourth row  144  of the output power reduction LUT  60  described in  FIG. 9 , the controller  48  may determine that the output power reduction value for both instances is 3 dB. 
     The controller  48  may then determine whether to implement the output power reduction value based on whether network signaling value override is enabled (decision block  168 ). In some embodiments, the controller  48  may determine whether network signaling value override is enabled using the one or more network signaling value override LUTs  58 . For example, the first row  138  of the network signaling value override LUT  58  described in  FIG. 11  indicates that an override setting is enabled. As such, the controller  48  may instruct the radio frequency system to reduce output power based on the output power reduction value (e.g., 3 dB) (process block  170 ). 
     On the other hand, the second row  140  indicates that the override setting is disabled. As such, the controller  48  may determine other operational parameters based at least in part on the override network signaling value and/or the output power reduction value (process block  172 ). In some embodiments, the controller  48  may determine other operational parameters to implement in addition to the output power reduction value (arrow  174 ). As described above, the other operational parameters may include power amplifier operational parameters, filtering operational parameters, carrier aggregation operational parameters, and/or channel configuration operational parameters. 
     One embodiment of a process  178  for determining power amplifier operational parameters is described in  FIG. 13 . Generally, the process  178  includes determining the output power reduction value (process block  180 ), determining proximity to protected frequencies (process block  182 ), determining power amplifier operational parameters (process block  184 ), and optionally determining other operational parameters (process block  186 ). In some embodiments, the process  178  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may determine the output power reduction value (process block  180 ). As described above, the controller  48  determine the output power reduction value using the one or more output power reduction LUTs  60  based on the override network signaling value. 
     Since magnitude of spurious emissions generally decrease as distance from the transmission frequency increases, the controller  48  may determine proximity of the transmission frequency (e.g., assigned resource blocks) to protected frequencies (process block  182 ). To determine the proximity, the controller  48  may determine the transmission frequency from a wireless service provider and the protected frequencies based on region the radio frequency system  12  is operating. The controller  48  may then determine proximity based on difference between the two. For example, when the transmission frequency is 2500-2510 MHz and the protected frequency is 2490.5-2496 MHz, the controller  48  may determine that the protected frequency is 4 MHz from the transmission frequency. 
     Based on the output power reduction value and the proximity to protected frequencies, the controller  48  may determine power amplifier operational parameters (process block  184 ). For example, the controller  48  may determine a radio frequency gain index (RGI) (process block  188 ), power amplifier supply voltage (process block  190 ), digital predistortion coefficients (process block  192 ), and/or supply voltage tracking mode (process block  194 ). In some embodiments, the controller  48  may determine the power amplifier operational parameters algorithmically. Additionally or alternatively, the controller  48  may determine the power amplifier operational parameters using the one or more power amplifier operational parameter LUTs  62 . 
     To help illustrate, one example of a power amplifier operational parameter LUT  62  is described in  FIG. 3 . More specifically, the described power amplifier operational parameter LUT  62  describes association between sets of operational parameters (e.g., output power reduction value and proximity to protected frequency) with a set of power amplifier operational parameters, which include a radio frequency gain index, a peak power amplifier supply voltage, digital predistortion coefficients, an envelope tracking detrough function or shaping table, and a tracking mode. It should be appreciated that the power amplifier operational parameter LUT  62  is merely intended to be illustrative and not limiting. 
     As described above, the power amplifier operational parameters may be adjusted to improve linearity of the power amplifier  40 . For example, the radio frequency gain index may indicate a peak voltage of the analog electrical signal generated by the transceiver  38  and input to the power amplifier  40 . Accordingly, decreasing the radio frequency gain index may decrease compression in the power amplifier  40 , thereby improving linearity. Additionally, the digital predistortion coefficients may be applied by the digital predistortion circuitry  37  to the digital electrical signal output by the digital signal generator  36 . Accordingly, adjusting the digital predistortion coefficients to offset distortion introduced by the radio frequency system  12  may improve linearity of the power amplifier  40 . 
     Furthermore, the power amplifier  40  may be operated in an average power tracking mode or an envelope tracking mode. When operating in average power tracking mode, the power amplifier power supply  46  determine average output power over a control duration (e.g. time slot) and adjust the power amplifier supply voltage after each control duration. On the other hand, when operating in envelope tracking mode, the power amplifier power supply  46  may adjust the power amplifier supply voltage dynamically based on the voltage of the analog electrical signal input from the transceiver  38 . In some embodiments, the power amplifier supply voltage may change as a function of the voltage of the analog electrical signal input to the power amplifier  40  from the transceiver  38 . As used herein a “detrough function” is intended to describe the power amplifier supply voltage as a function of the input analog electrical signal voltage such that the peak voltage of the input analog electrical signal results in the peak power amplifier supply voltage. In other words, different detrough functions may describe different corresponding power amplifier supply voltages when the input analog electrical signal is modulated (e.g., reduced below the peak voltage). 
     In some embodiments, operating the power amplifier  40  in average power tracking mode may produce spurious emissions over a smaller range of frequencies compared to envelope tracking mode. Thus, when protected frequencies are closer to the transmission frequency than a threshold, the controller  48  may instruct the power amplifier power supply  46  and the power amplifier  40  to operate in average power tracking mode. For example, when the output power reduction value is 3 dB and the proximity to the protected frequency is 40 MHz (e.g., greater than the threshold), a first row  196  indicates that the power amplifier operational parameters include operating in envelope tracking mode. On the other hand, when the output power reduction value is 3 dB and the proximity to the protected frequency is 4 MHz (e.g., less than the threshold), the second row  198  indicates that the power amplifier operational parameters include operating in average power tracking mode. 
     Additionally, in some embodiments, operating the power amplifier  40  in envelope tracking mode may enable reducing power consumption of the radio frequency system at higher output powers. However, at lower output powers, power consumption used to track voltage of the input analog electrical signal may outweigh the power savings. Thus, when output power reduction value increases above a threshold (e.g., 7 dB), thereby decreasing the output power, the controller  48  may instruct the power amplifier power supply  46  and the power amplifier  40  to operate in average power tracking mode. For example, when the output power reduction value is 6 dB, a third row  200  indicates that the operational parameters include operating in envelope tracking mode. On the other hand, when the output power reduction value is 7 dB, a fourth row  202  indicates that the operational parameters include operating in average power tracking mode. In this manner, the controller  48  may determine power amplifier operational parameters that may be implemented to facilitate the radio frequency system  12  operating in compliance with operational constraints. 
     Additionally or alternatively, the controller  48  may determine filtering operational parameters. To help illustrate, one embodiment of a process  204  for determining filtering operational parameters is described in  FIG. 15 . Generally, the process  204  includes determining an output power reduction value (process block  206 ), determining location of protected frequencies (process block  208 ), determining filtering operational parameters (process block  210 ), and optionally determining other operational parameters (process block  212 ). In some embodiments, the process  204  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may determine the output power reduction value (process block  206 ). As described above, the controller  48  determines the output power reduction value using one or more output power reduction LUTs  60  based on the override network signaling value. Additionally, the controller  48  may determine the location of protected frequencies based on the region in which the radio frequency system  12  is operating (process block  208 ). 
     Based on the output power reduction value and the location of protected frequencies, the controller  48  may determine filtering operational parameters (process block  210 ). More specifically, in some embodiments, the controller  48  may determine target frequencies of a filter based at least in part on the location of protected frequencies (process block  214 ). For example, when protected frequencies are located at 2490.5-2496 MHz, the controller  48  may determine that filtering should be targeted to frequencies less than 2496 MHz. 
     Additionally, in some embodiments, the controller  48  may determine filter rejection based at least in part on the output power reduction value (process block  216 ). As described above, the output power may be reduced to reduce magnitude of spurious emissions. Thus, the filter rejection may be determined so that approximately the same reduction in spurious emission magnitude may be achieved as the reduction in output power. 
     Furthermore, the controller  48  may enable or disable a filter based at least in part on the determined filter rejection and target frequencies (process block  218 ). In embodiments where the radio frequency system  12  includes multiple filters that can be selectively enabled and disabled, the controller  48  may enable a filter that has the determined filter rejection and target frequencies and disable the other filters. In embodiments where the radio frequency system  12  includes a configurable (e.g., a tunable) filter, the controller  48  may enable the filter and instruct the filter to implement the determined filter rejection at the target frequencies. In this manner, the controller  48  may determine filtering operational parameters that may be implemented to facilitate the radio frequency system  12  operating in compliance with operational constraints. 
     Additionally or alternatively, the controller  48  may determine carrier aggregation operation parameters. To help illustrate, one embodiment of a process  214  for determining carrier aggregation operational parameters is described in  FIG. 16 . Generally, the process  214  includes determining an override network signaling value (process block  216 ), determining whether carrier aggregation is enabled (decision block  218 ), and when disabled determining other operational parameters (process block  220 ). When enabled, the process  214  includes determining location of protected frequencies (process block  222 ), determining transmission frequency to disable (process block  224 ), and disabling carrier aggregation (process block  226 ). In some embodiments, the process  214  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may determine the override network signaling value (process block  216 ). As described above, in some embodiments, the controller  48  may determine the override network signaling value based on channel frequency and transmission frequency using the one or more network signaling value override LUTs  58 . 
     Additionally, the controller  48  may determine whether carrier aggregation is enabled (decision block  218 ). In some embodiments, carrier aggregation may be enabled by the network signaling value received from a wireless service provider. For example, carrier aggregation may be enabled when a network signaling value CA_NS_XX is received. In such embodiments, the antenna  44  may receive an analog representation of the carrier aggregation network signaling value, the transceiver  38  may convert the analog representation to a digital representation of the carrier aggregation network signaling value, and the controller  48  may determine the carrier aggregation network signaling value based on the digital representation. 
     When carrier aggregation is enabled, the controller  48  may determine location of protected frequencies (process block  222 ). In some embodiments, the controller  48  may determine location of the protected frequencies based at least in part on the region it is operating. Additionally, the controller  48  may determine transmission frequency to disable based at least in part on the location of the protected frequencies (process block  224 ). As such, in some embodiments, the controller  48  may determine its assigned transmission frequency from a wireless service carrier. 
     To help illustrate effects of carrier aggregation,  FIG. 17  describes a first analog electrical signal  228  with carrier aggregation enabled and a second analog electrical signal  230  with carrier aggregation disabled. In the depicted embodiments, the radio frequencies are divided into channels with bandwidths of 10 MHz. As such,  FIG. 18  describe the magnitude of the analog electrical signals  228  and  230  in the first channel  74  between 2490.5-2500.5 MHz, the second channel  76  between 2500.5-2510.5 MHz, the third channel  78  between 2510.5-2520.5 MHz, the fourth channel  80  between 2520.5-2530.5 MHz, and the fifth channel  82  between 2530.5-2540.5 MHz. It should be noted that the analog electrical signals  228  and  230  are merely intended to be illustrative and not limiting. 
     Since the channel bandwidth is 10 MHz, the radio frequency system  12  may be assigned one hundred resource blocks when carrier aggregation is enabled. In other words, effectively, the radio frequency system  12  may utilize a transmission bandwidth of 20 MHz. Thus, as depicted, the first analog electrical signal  228  includes a data portion  84 A between 2500.5-2520.5 MHz. 
     In addition to the data portion  84 A, the first analog electrical signal  228  includes third order intermodulation spurious emissions  86 A with a 10 MHz bandwidth in the first channel  74  and the fourth channel  80 . Additionally, the first analog electrical signal  228  includes fifth order intermodulation spurious emissions  88 A with a 10 MHz bandwidth in the fifth channel  82  and in the 2480.5-2490.5 MHz channel. However, as depicted, the magnitude of the spurious emissions  86 A and  88 A may be greater due to the increased transmission bandwidth. 
     Thus, to reduce spurious emissions, the controller  48  may reduce the transmission bandwidth by instructing the radio frequency system  12  to disable carrier aggregation. For example, in the depicted embodiment, the controller  48  may instruct the radio frequency system  12  to transmit using fifty resource blocks, thereby reducing transmission bandwidth to 10 MHz. In this manner, magnitude of spurious emissions may be reduced. 
     As such, the second analog electrical signal  230  includes a data portion  84 B between 2510.5-2520.5 MHz. In addition to the data portion  84 B, the second analog electrical signal  230  includes third order intermodulation spurious emissions  86 B with a 10 MHz bandwidth in the first channel  74  and the fourth channel  80 . Additionally, the second analog electrical signal  230  includes fifth order intermodulation spurious emissions  88 B with a 10 MHz bandwidth in the fifth channel  82  and the first channel  74 . 
     As depicted, due to the larger transmission bandwidth, the magnitude of the spurious emissions  86 A and  88 A of the first analog electrical signal  228  may be greater than the spurious emissions  86 B and  88 B of the second analog electrical signal  230 . Moreover, due to the selection of the resource blocks, the order of intermodulation spurious emissions  86 A produced by the first analog electrical signal  228  is lower than the order of the intermodulation spurious emissions  88 B produced by the second analog electrical signal  230  in the protected frequencies 2490.5-2496 MHz. As such, in the protected frequencies, the magnitude of the third order intermodulation spurious emissions  86 A is greater than the magnitude of the fifth order intermodulation spurious emissions  88 B. In this manner, the controller  48  may determine carrier aggregation operational parameters that may be implemented to facilitate the radio frequency system  12  operating in compliance with operational constraints. 
     Additionally or alternatively, the controller  48  may determine channel operation parameters. To help illustrate, one embodiment of a process  232  for determining channel configuration operational parameters is described in  FIG. 18 . Generally, the process  232  includes determining an override network signaling value (process block  234 ), determining location of protected frequencies (process block  236 ), restricting bandwidth of a channel at edge frequencies (process block  238 ), and/or restricting output power in the channel (process block  240 ). In some embodiments, the process  232  may be implemented using instructions stored in the controller memory  52  and/or other suitable tangible non-transitory computer-readable medium and executable by the controller processor  50  and/or other suitable processing circuitry. 
     Accordingly, in such embodiments, the controller  48  may determine the override network signaling value (process block  234 ). As described above, in some embodiments, the controller  48  may determine the override network signaling value based on channel frequency and transmission frequency using the one or more network signaling value override LUTs  58 . Additionally, the controller  48  may determine the location of protected frequencies based on region the radio frequency system  12  is operating (process block  236 ). In some embodiments, the controller  48  may determine the location of protected frequencies based on region it is operating. 
     Based at least in part on the location of protected frequencies, the controller  48  may restrict bandwidth of a channel at edge frequencies (process block  238 ) and/or restrict output power in the channel at the edge frequencies (process block  240 ). As used herein, “edge frequencies” are intended to describe frequencies that are within a threshold from the protected frequencies. 
     To help illustrate the effects signals transmitted at edge frequencies,  FIG. 19  describes a first analog electrical signal  242  transmitted in a 10 MHz channel and a second analog electrical signal  244  transmitted in a 5 MHz channel. As depicted, the first analog electrical signal  242  includes a data portion  84 A between 2510.5-2520.5 MHz. In addition to the data portion  84 A, the first analog electrical signal  242  includes third order intermodulation spurious emissions  86 A between 2500.5-2510.5 MHz and between 2520.5-2530.5 MHz. Additionally, the first analog electrical signal  242  includes fifth order intermodulation spurious emissions  88 A between 2490.5-2500.5 MHz and between 2530.5-2540.5 MHz. 
     On the other hand, the second analog electrical signal  244  includes a data portion between 2510.5-2515.5 MHz. In addition to the data portion  84 B, the second analog electrical signal  244  includes third order intermodulation spurious emissions  86 B between 2505.5-2510.5 MHz and between 2515.5-2520.5 MHz and fifth order intermodulation spurious emissions  88 B between 2500.5-2505.5 MHz and between 2520.5-2525.5 MHz. Additionally, the second analog electrical signal  244  includes seventh order intermodulation spurious emissions  246  between 2495.5-2500.5 MHz and between 2530.5-2535.5 MHz and ninth order intermodulation spurious emissions  248  between 2490.5-2495.5 MHz and between 2530.5-2535.5 MHz. 
     Thus, both the first analog electrical signal  242  and the second analog electrical signal  244  include spurious emissions that fall within protected frequencies between 2490.5-2496 MHz. More specifically, the first analog electrical signal  242  may produce third order intermodulation spurious emission  88 A in the protected frequencies. On the other hand, the second analog electrical signal  244  may produce seventh order intermodulation spurious emissions  246  and ninth order intermodulation spurious emissions  248  in the protected frequencies. Thus, due to the higher orders of intermodulation, the spurious emissions produced by the second analog electrical signal  244  in the protected frequencies may be less than the spurious emissions produced by the first analog electrical signal  242 . 
     Accordingly, the controller  48  may restrict channel bandwidth in edge frequencies to magnitude of spurious emissions produced in the protected frequencies. For example, the controller  48  may restrict channel bandwidth to 5 MHz or less and disable channel bandwidths greater than 5 MHz. In some embodiments, the controller  48  may restrict channel bandwidth based on proximity to protected frequencies. For example, the controller  48  may enable 10 MHz channel bandwidths at frequencies greater than 2520.5 MHz because resulting spurious emissions in the protected frequencies will be fifth order or higher. In such an embodiment, the edge frequencies may be defined as frequencies as less than 2520.5 MHz. 
     In fact, in some embodiments, a wireless service provider may recognize the possibility of certain channel bandwidth s at edge frequencies causing spurious emissions that are not in compliance with wireless transmission regulations. As such, in actual operation, the wireless service provider may proactively disable those channel bandwidths at the edge frequencies. In such instances, the radio frequency system  12  may provide an additional safeguard and similarly disable those channel bandwidths at the edge frequencies. 
     Additionally, in some embodiments, the controller  48  may restrict output power at edge frequencies to limit magnitude of spurious emissions in the protected frequencies. For example, the controller  48  may restrict output power by applying a mask to analog electrical signals transmitted in the edge frequencies. In this manner, the controller  48  may determine channel configuration operational parameters that may be implemented to facilitate the radio frequency system  12  operating in compliance with operational constraints. 
     Thus, returning to process  94  of  FIG. 8 , the controller  48  may instruct the radio frequency system  12  to implement any combination of the output power reduction value, power amplifier operational parameters, filtering operational parameters, carrier aggregation operational parameters, and channel configuration operational parameters to facilitate operating in compliance with operational constraints (e.g., wireless transmission regulations). As described above, in some embodiments, the various operational parameters may be determined using calibration data  56  stored in the controller memory  52 . Accordingly, in such embodiments, a manufacturer may determine and store the calibration data  56  in the radio frequency system  12 . 
     One embodiment of a process  250  for determining the calibration data  56  is described in  FIG. 20 . Generally, the process  250  includes determining different sets of operational constraints (process block  252 ), operating with different sets of operational parameters (process block  254 ), determining whether radio frequency system operates in compliance with operational constraints (process block  256 ), associate noncompliant operational parameters with an override network signaling value (process block  258 ), and store compliant operational parameters in operational parameter look-up-tables (process block  260 ). 
     For example, a manufacturer may determine different sets of operational constraints (process block  252 ). In some embodiments, the manufacturer may determine regions the radio frequency system  12  is designed to operate in. The manufacturer may then determine wireless transmission regulations (e.g., operational constraints) for those regions, which may include protected frequencies and/or spurious emission limits. Additionally, the manufacturer may operate the radio frequency system  12  using different sets of operational parameters (process block  254 ). For example, the manufacturer may operate the radio frequency system  12  with different transmission frequency and channel frequency pairs. 
     The manufacturer may then determine whether operating with each set of operational parameters causes the radio frequency system  12  to be in compliance or noncompliance with each set of operational constraints (process block  258 ). For example, the manufacturer may determine spurious emissions that result in protected frequencies when operating with a set of operational parameters and compare the spurious emissions with spurious emission limits. In this manner, the manufacturer may determine whether the operating with the set of operational parameters facilitates compliance with operational constraints (e.g., spurious emission limits). 
     Operational parameters that cause the radio frequency system  12  to operate out of compliance with operational constraints may be associated with an override network signaling value (process block  258 ). For example, sets of operational parameters (e.g., a channel frequency and transmission frequency pair) that result in noncompliance with operational constraints may be associated with the network signaling value. In some embodiments, the association may be stored in one or more network signaling value override LUTs  58 . 
     The manufacturer may determine the override network signaling value to associate with each set of operational parameters based at least in part on what frequency band includes the channel frequency and the transmission frequency. For example, when the channel frequency and the transmission frequency are between 2496-2690 MHz, the manufacturer may determine that the radio frequency system is operating in band  41 . The manufacturer may then determine that the override network signaling value associated with the set of operational parameters is NS_ 04 . 
     On the other hand, operational parameters that cause the radio frequency system  12  to operate in compliance with operational constraints may be stored in one or more operational parameter look-up-tables (process block  260 ). For example, an operational parameter set (e.g., override network signaling value, channel bandwidth, starting assigned resource block, and number of assigned resource blocks) may be associated with an output power reduction value that facilitate compliance with operational constraints. In some embodiments, the association may be stored in one or more output power reduction LUTs  60   
     Additionally, an operational parameter set (e.g., output power reduction value and a proximity to protected frequencies) may be associated with power amplifier operational parameters that facilitate compliance with operational constraints. In some embodiments, the power amplifier operational parameters may include a radio frequency gain index (RGI), a peak power amplifier supply voltage, digital predistortion coefficients, a detrough function, and/or tracking mode. Additionally, in some embodiments, the association may be stored in one or more power amplifier operational parameter LUTs  62 . 
     Furthermore, an operational parameter set (e.g., output power reduction value and location of protected frequencies) may be associated with filtering operational parameters that facilitate compliance with operational constraints. In some embodiments, the filtering operational parameters may include whether to enable/disable a filter, filter rejection of an enabled filter, and/or target frequencies of the enabled filter. Additionally, in some embodiments, the association may be stored in one or more filtering operational parameter LUTs  64 . 
     An operational parameter set (e.g., carrier aggregation setting and location of protected frequencies) may be associated with carrier aggregation operational parameters that facilitate compliance with operational constraints. In some embodiments, the carrier aggregation operational parameters may include whether to enable/disable carrier aggregation and/or what transmission frequency to use after carrier aggregation is disabled. Additionally, in some embodiments, the association may be stored in one or more carrier aggregation operational parameter LUTs  66 . 
     Moreover, an operational parameter set (e.g., location of protected frequencies) may be associated with channel configuration operational parameters that facilitate compliance with operational constraints. In some embodiments, the channel configuration operational parameters may include channel bandwidth restrictions and/or output power restrictions. Additionally, in some embodiments, the association may be stored in one or more channel configuration operational parameter LUTs  68 . Thus, during operation, the radio frequency system  12  may determine operational parameters to implement, which facilitate compliance with operational constraints (e.g., wireless transmission regulations), using the calibration data  56 . 
     Accordingly, the technical effects of the present disclosure include facilitating compliance with wireless transmission regulations while improving performance of a radio frequency system. In some embodiments, the radio frequency system may determine operational constraints, for example based on region of operation, even when a correct network signaling value is not received. Based on the operational constraints, the radio frequency system may determine an override network signaling value when not expected to operate in compliance with the operational constraints. The radio frequency system may then operate based on the override network signaling value instead of a received network signaling value to facilitate compliance with the operational constraints. For example, the radio frequency system may determine and implement operational parameters based at least in part on the override network signaling value. In this manner, the radio frequency system may reduce unnecessary adjustments to operational parameters, thereby improving performance of the radio frequency system. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20150803
Publication Date: 20170829
Grant Date: 20170829
Priority Date: 20150803
Inventors: GOEDKEN RYAN J.
LIU XUETING
LUM NICHOLAS W.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W52/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/367", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/225", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W16/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W24/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/283", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W16/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/225", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/367", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/283", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 58052787