Patent Description:
In a scenario, a communication device receives a radio frequency signal. The communication device may process the radio frequency signal based on a shift frequency and a baseband frequency. It may be desirable to enhance a performance of the communication device by tuning the processing of the radio frequency signal. <CIT>relates to a downlink signal reception method and apparatus of a low-cost machine-type terminal in a wireless communication system, and particularly to the selection of a best narrowband DC subcarrier.

In the following description, various embodiments of the invention are described with reference to the following drawings, in which:.

The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced.

A "circuit" may be understood as any kind of a logic implementing entity, which may be special purpose circuitry or a processor executing software stored in a memory, firmware, or any combination thereof. Further, a "circuit" may be a hard-wired logic circuit or a programmable logic circuit such as a programmable processor, e.g. a microprocessor. A "circuit" may also be a processor executing software, e.g. any kind of computer program. Any other kind of implementation of the respective functions which will be described in more detail below may also be understood as a "circuit". It is understood that any two (or more) of the described circuits may be combined into a single circuit with substantially equivalent functionality, and conversely that any single described circuit may be distributed into two (or more) separate circuits with substantially equivalent functionality. In particular with respect to the use of "circuitry" in the claims included herein, the use of "circuit" may be understood as collectively referring to two or more circuits.

The representation of a signal represented in the frequency domain may be based on a Fourier transformation of the signal represented in the time domain to the frequency domain. Component radio signals based on the signal represented in the frequency domain may be associated with frequencies based on the representation of the signal in the frequency domain.

A communication device may receive radio frequency signals. A first radio frequency signal of the received radio frequency signals may include a distorted signal component and undistorted signal components. A second radio frequency signal of the received radio frequency signals may include only undistorted signal components. For example the second radio frequency signal may be a narrowband signal that is included in the first radio frequency signal. The communication device may be configured to process the radio frequency signal based on a shift frequency and a baseband frequency. The communication device may be configured to tune a shift frequency based on the radio frequency signal. Further, in an example, the communication device may be configured to tune a baseband frequency based on the radio frequency signal. For example, the tuned shift frequency or baseband frequency may be determined before the radio frequency signal is received by the communication device.

Various aspects of this disclosure provide a communication device that may include a receiver configured to receive a radio frequency signal. Further, the communication device may include a processor configured to determine a shift frequency based on a component radio frequency signal. Further, the processor may be configured to determine a second signal based on the radio frequency signal. The component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain. The second signal may be determined from shifting frequencies related to the radio frequency signal represented in the frequency domain by the shift frequency. Thus, the communication device may be configured to efficiently and reliably process the radio frequency signal in the baseband. Further, the communication device may be configured to flexibly and reliably process various types of signals. Moreover, the communication device may be configured to effectively process the radio frequency signal at a low power consumption.

This disclosure further provides a communication device that may include a receiver configured to receive a radio frequency signal. Further, the communication device may include a processor configured to determine a second signal based on the radio frequency signal. Further, the processor may be configured to determine a baseband frequency based on a component radio frequency signal. The second signal may be determined from shifting frequencies related to the radio frequency signal represented in the frequency domain by a shift frequency. The component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain. Thus, the communication device may be configured to efficiently and reliably process the radio frequency signal in the baseband. Further, the communication device may be configured to effectively process the radio frequency signal at a low power consumption. Moreover, the communication device may be configured to flexibly and reliably process various types of signals.

Furthermore, a method for radio frequency communication may be provided that may include receiving a radio frequency signal. Further, the method may include determining a shift frequency based on a component radio frequency signal. Moreover, the method may include determining a second signal based on the radio frequency signal. The component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain. The second signal may be determined from shifting frequencies related to the radio frequency signal represented in the frequency domain by the shift frequency. Thus, the method may be configured to flexibly and reliably process various types of signals. Moreover, the method may be configured to effectively process the radio frequency signal at a low power consumption. Further, the method may be configured to efficiently and reliably process the radio frequency signal in the baseband.

This disclosure further provides a method for radio frequency communication that may include receiving a radio frequency signal. Further, the method may include determining a second signal based on the radio frequency signal. Moreover, the method may include determining a baseband frequency based on a component radio frequency signal. The second signal may be determined from shifting frequencies related to the radio frequency signal represented in the frequency domain by a shift frequency. The component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain. Thus, the method may be configured to efficiently and reliably process the radio frequency signal in the baseband. Further, the method may be configured to effectively process the radio frequency signal at a low power consumption. Moreover, the method may be configured to flexibly and reliably process various types of signals.

<FIG> shows a scenario in which a base station <NUM> and a communication device <NUM> transmit and receive signals based on a radio frequency connection. The base station <NUM> may be configured to transmit a radio frequency signal in accordance with a radio communication technology. The communication device <NUM> may be configured to receive and process the transmitted radio frequency signal.

In an example, the radio communication technology may be based on Orthogonal Frequency Division Multiplexing. Further, the radio frequency signal may include a DC (Direct Current) subcarrier signal that may be associated with a DC subcarrier frequency.

<FIG> shows a schematic diagram of a representation of the radio frequency signal in the frequency domain and a baseband frequency range <NUM>. The baseband frequency range may include a baseband frequency <NUM>. The baseband frequency <NUM> may be a center frequency of the baseband frequency range <NUM>. The diagram may have a first axis <NUM> that may indicate frequencies and a second axis <NUM> that may indicate time.

The radio frequency signal may include a first signal. The first signal may be associated with a first frequency range <NUM> related to the first signal represented in the frequency domain. The first frequency range may include a center frequency <NUM> of the first frequency range <NUM>. A difference frequency of the center frequency <NUM> and the baseband frequency <NUM> may be referenced by the reference sign <NUM>.

<FIG> shows a flow diagram that illustrates a method for processing the radio frequency signal based on <FIG>.

The method may include, in <NUM>, receiving the radio frequency signal.

The method may further include, in <NUM>, band-pass filtering the radio frequency signal based on preserving the first signal.

The method may further include, in <NUM>, shifting frequencies based on the band-pass filtered signal and a first shift frequency to form a frequency shifted signal. The first shift frequency may be the difference frequency <NUM>. The baseband frequency range <NUM> may include the frequencies of a frequency shifted first frequency range that is associated with the frequency shifted signal. In an example, the shifting of frequencies may be based on mixing the band-pass filtered signal with another signal.

The method may further include, in <NUM>, low-pass filtering the frequency shifted signal based on the first frequency range <NUM> and the first shift frequency <NUM>. The low-pass filtering may be configured to remove frequencies that are not included in the frequency shifted first frequency range.

The method may further include, in <NUM>, high-pass filtering the low-pass filtered signal based on a second frequency range. The high-pass filtering may be configured to remove a signal that is associated with the second frequency range related to the low-pass filtered signal represented in the frequency domain from the low-pass filtered signal. The second frequency range may be centered around the baseband frequency <NUM>.

Thus, if the DC subcarrier frequency is a center frequency of the first frequency range <NUM> the high-pass filtering may be configured to remove a distortion signal based on the DC subcarrier signal. The distortion signal may be associated with a distortion frequency range related to the distortion signal represented in the frequency domain. The high-pass filtering may be configured such that the second frequency range includes the distortion frequency range. The distortion signal may be based on the frequency shifting of the DC subcarrier frequency to the distortion frequency range by the first shift frequency <NUM>.

The method may further include, in <NUM>, processing the high-pass filtered signal based on a Fast Fourier Transform (FFT) process. The FFT process may be based on <NUM> data points. If the first signal is in accordance with a narrowband Internet-of-Things communication technology the FFT process may for example be based on sixteen data points.

The method may further include, in <NUM>, selecting frequencies based on the FFT processed signal and a multiplexer for further baseband signal processing, for example for channel estimation and channel equalization. In case the signal is in accordance with the Long Term Evolution communication technology, the frequencies may be subcarrier frequencies that are associated with resource elements.

The method may further include, in <NUM>, rotating phases of component signals based on the FFT processed signal and the selected frequencies. The rotating may be configured to compensate a rotation based on the processed signal, a cyclic prefix and the FFT process.

<FIG> shows a schematic diagram of component signals associated with the frequency shifted signal based on the method based on <FIG>. The diagram may have a first axis <NUM> that may indicate the associated frequencies and a second axis <NUM> that may indicate time. The component signals may be based on the first signal.

The frequency shifted signal may include component signals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The component signals <NUM> to <NUM> may be associated with subcarrier frequencies related to the frequency shifted signal represented in the frequency domain, respectively.

The frequency shifted signal may include reference signals of a plurality of types that may be indicated by diagonal hatching, vertical hatching and horizontal hatching. As an example, the component signals <NUM>, <NUM> and <NUM> may include reference signals <NUM>, <NUM> and <NUM>. The types of the reference signals <NUM>, <NUM> and <NUM> may be different from each other as indicated by the hatching.

The second frequency range referenced by <NUM> may include the distortion frequency range. The frequency shifted signal may be distorted in the distortion frequency range. The distortion frequency range may be based on the DC subcarrier signal and the frequency shifting. The component signals <NUM> and <NUM> may be at least partially included in the distortion frequency range and consequently distorted. Therefore, reference signals <NUM>, <NUM>, and <NUM> that may be included in the component signals <NUM> and <NUM> may be distorted. For example, the reference signals may be required to determine channel characteristics required for processing the component signals <NUM> to <NUM>. A further processing, for example to recover data packets or the reference signals, based on the distorted component signals <NUM> and <NUM> may be inefficient. Further, the distortion frequency range may include the baseband frequency <NUM>. In an example, the distortion frequency range may indicate a main distortion based on the frequency shifted signal.

<FIG> shows a communication device <NUM>. The communication device <NUM> may include a receiver <NUM> configure to receive a radio frequency signal and a processor <NUM>. The processor <NUM> may be configured to determine a second shift frequency based on a first component radio frequency signal. The first component radio frequency signal may be dependent from the radio frequency signal and associated with a first frequency related to the radio frequency signal represented in the frequency domain.

Further, the processor <NUM> may be configured to determine a second signal based on the radio frequency signal. The processor <NUM> may be configured to determine the second signal from shifting frequencies related to the radio frequency signal represented in the frequency domain by the second shift frequency.

Thus, the communication device <NUM> may be configured to efficiently and effectively reduce the loss of signals that are required for reliably processing the radio frequency signal.

<FIG> shows a schematic diagram of frequencies that may be associated with the radio frequency signal represented in the frequency domain and frequencies that may be associated with the second signal represented in the frequency domain based on the communication device based on <FIG>. The diagram may have a first axis <NUM> that may indicate the associated frequencies and a second axis <NUM> that may indicate time.

The radio frequency signal may include a third radio frequency signal that may be associated with a third frequency range <NUM> related to the third radio frequency signal represented in the frequency domain. The third frequency range <NUM> may include a center frequency <NUM> and the first frequency referenced by <NUM>.

In an example, the first signal may include the third radio frequency signal. For example, the third radio frequency signal may be a narrowband signal. Further, the first frequency range <NUM> may include the third frequency range <NUM>.

In an example, the third radio frequency signal may be in accordance with Orthogonal Frequency Division Multiplexing. Further, exemplary, the first signal may be in accordance with Orthogonal Frequency Division Multiplexing.

In an example, the first signal and the third radio frequency signal may be in accordance with a radio communication technology. For example, the first signal may be in accordance with a Long Term Evolution communication technology and the third radio frequency signal may be in accordance with a narrowband Internet-of-Things communication technology or a Long Term Evolution category M1 communication technology.

The second signal may be associated with frequencies that are included in a baseband frequency range <NUM>. Further, the baseband frequency range <NUM> may include a baseband frequency <NUM>. The baseband frequency <NUM> may be a center frequency of the baseband frequency range <NUM>. The communication device <NUM> may be configured to process the second signal based on the baseband frequency <NUM> and the baseband frequency range <NUM>.

The processor <NUM> may be configured to determine the second shift frequency referenced by <NUM> based on a difference of the first frequency <NUM> and the baseband frequency <NUM>. Further, the processor <NUM> may be configured to determine the second signal based on shifting the frequencies related to the radio frequency signal represented in the frequency domain based on the radio frequency signal by the second shift frequency <NUM>.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> based on the radio frequency signal before the radio frequency signal is received by the receiver <NUM>.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> based on the received radio frequency signal.

In an example, the processor <NUM> may be configured to determine the second signal based on shifting the frequencies of the third frequency range <NUM> based on the received third radio frequency signal by the second shift frequency <NUM>. Moreover, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the baseband frequency range <NUM> may include the frequency shifted third radio frequency signal that may be shifted by the second shift frequency <NUM>.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the second frequency range <NUM> excludes frequencies that are associated with component signals that include reference signals.

In an example, the reference signals may be in accordance with the radio communication technology.

<FIG> shows a flow diagram that illustrates a method based on the communication device based on <FIG>. The method may, in <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, be based on <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> of the method based on <FIG>.

The method may further include, in <NUM>, shifting frequencies based on the band-pass filtered signal and the second shift frequency <NUM> to form the second signal. The processor <NUM> may be configured to determine the second shift frequency <NUM> based on the first component radio frequency signal and the radio frequency signal such that the first frequency <NUM> may be shifted to a baseband frequency <NUM> that is included in the second frequency range <NUM>.

The processor <NUM> may be configured to determine the second shift frequency <NUM> such that the high-pass filtering based on <NUM> may remove a component signal based on the first component radio frequency signal. Thus, the communication device <NUM> may be configured to high-pass filter independent from whether the signal to be filtered includes the distortion signal. In case the signal to be filtered includes the distortion signal the high-pass filtering may be configured to remove the distortion signal by filtering based on the second frequency range <NUM>.

The method may further include, in <NUM>, low-pass filtering the second signal based on the third frequency range <NUM>, the second shift frequency <NUM> and the baseband frequency <NUM>. The low-pass filtering may be configured to remove component radio frequency signals based on the second signal that are associated with frequencies that are not included in the baseband frequency range <NUM>.

The method may further include, in <NUM>, selecting subcarrier frequencies that are associated with the third radio frequency signal.

In case the third radio frequency signal is in accordance with the Long Term Evolution category M1 communication technology the third frequency range may include <NUM> subcarrier frequencies that are associated with the third radio frequency signal. The selecting may be configured to select the <NUM> subcarrier frequencies that are associated with the third radio frequency signal. For example, the bandwidth of the third frequency range may be about <NUM>.

In case the third radio frequency signal is in accordance with the narrowband Internet-of-Things communication technology the third frequency range may include <NUM> subcarrier frequencies that are associated with the third radio frequency signal. The selecting may be configured to select the <NUM> subcarrier frequencies that are associated with the third radio frequency signal.

<FIG> shows a schematic diagram of component radio frequency signals based on the second signal that are processed based on the communication device based on <FIG>. The second signal may be based on the third radio frequency signal. The diagram may have a first axis <NUM> that may indicate the frequencies that are associated with the component radio frequency signals and a second axis <NUM> that may indicate time. The frequencies shown in <FIG> are included in the baseband frequency range <NUM>.

The second signal may include component signals <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The component signals <NUM> to <NUM> may be associated with subcarrier frequencies related to the second signal represented in the frequency domain, respectively.

In an example, the determined first component radio frequency signal may not include reference signals. By shifting the first frequency <NUM> by the second shift frequency <NUM>, the frequency shifting may shift the first component radio frequency signal to the component signal <NUM>. Further, in an example, the second frequency range <NUM> may include only the component signal <NUM>. Thus, the high-pass filtering based on <NUM> may only remove component signals that do not include reference signals. Thus, the communication device <NUM> may be configured to avoid reference signal corruption by a DC subcarrier.

A second frequency <NUM> may be based on shifting the center frequency <NUM> by the second shift frequency <NUM>. The second frequency <NUM> may differ from the baseband frequency <NUM> by a frequency difference that allows to process the second signal based on the Fast Fourier Transform without further frequency shifting.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the second frequency range <NUM> excludes frequencies that are associated with reference signals based on the second signal. Thus, the communication device <NUM> may be configured to avoid the loss of reference signals. Therefore, the communication device <NUM> may be configured to increase the performance.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the second frequency range <NUM> excludes frequencies that are associated with component signals that include a type of reference signal based on the second signal, for example cell specific reference signals, demodulation reference signals and channel state information reference signals. Thus, the processor <NUM> may be configured to avoid the loss of performance sensitive reference signals, as for example the cell specific reference signals.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the second frequency range <NUM> excludes frequencies that are associated with component signals that include a plurality of types of reference signals based on the second signal. Thus, the communication device <NUM> may be configured to efficiently reduce adverse effects on signal processing by reducing the loss of signals and flexibly avoiding the loss of further data.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the second frequency range <NUM> only includes frequencies that may be associated with component signals that include a first number of reference signals or first number of type of reference signals based on the second signal. Further, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the first number of reference signals is smaller than a threshold. Thus, the communication device <NUM> may be configured to reliably provide a degree of performance in an efficient manner.

In an example, the processor <NUM> may be configured to determine the second shift frequency <NUM> such that the second frequency range <NUM> excludes frequencies that may be associated with component signals that include a second number of reference signals or second number of type of reference signals based on the second signal. The second number may be greater than a second threshold.

In an example, processor <NUM> may be configured to determine the second shift frequency <NUM> such that the high-pass filtering may only remove a group of subcarrier component signals that may be included in a fourth frequency range centered around the first frequency <NUM>. The width of the fourth frequency range may be the width of the third frequency range <NUM>.

In an example, the processor <NUM> may be configured to determine third component signals based on the second signal. Further, the processor <NUM> may be configured to determine a fourth component signal based on a FFT process based on the third component signals. The processor <NUM> may be configured to determine the second shift frequency <NUM> based on the third component signals. For example, the processor <NUM> may be configured to select component radio frequency signals based on the third radio frequency signal such that the third component signals exclude reference signals, exclude reference signals of a type of reference signal and/or include a number of reference signals that is smaller than a threshold. Thus, the communication device <NUM> may be configured to effectively avoid the loss of reference signals to increase the performance of the communication device <NUM>. Further, the communication device <NUM> may be configured to flexibly process signals based on an uncomplex high-pass filter.

In an example, the type of the third radio frequency signal may be a modulation scheme. The modulation scheme may be, for example, at least one of Binary Phase-Shift Keying, Quadrature Phase-Shift Keying, Sixteen Quadrature Amplitude Modulation, Sixty Four Quadrature Amplitude Modulation, Two Hundred Fifty Six Quadrature Amplitude Modulation or One Thousand Twenty Four Quadrature Amplitude Modulation.

It should be noted that aspects of communication device based on <FIG> may be combined with aspects of the communication device based on <FIG>.

<FIG> shows a schematic diagram of a communication device <NUM> that may include a receiver <NUM>, a processor <NUM>, a frequency shifter <NUM> and a high-pass filter <NUM>. The receiver <NUM> may be configured to receive the radio frequency signal. The radio frequency signal may include the first signal that may be in accordance with the Long Term Evolution communication technology.

The processor <NUM> may be configured to determine the first component radio frequency signal based on the second component radio frequency signals. The second component radio frequency signals may be based on the radio frequency signal and associated with frequencies related to the radio frequency signal represented in the frequency domain. The processor <NUM> may be configured to determine the second shift frequency <NUM> based on the first component radio frequency signal.

The processor <NUM> may be configured to determine the second signal based on shifting frequencies related to the radio frequency signal represented in the frequency domain based on the radio frequency signal by the second shift frequency <NUM>. Further, the processor <NUM> may be configured to control the frequency shifter <NUM> to form the second signal based on shifting frequencies of the third frequency range <NUM> based on the radio frequency signal by the second shift frequency <NUM>. Further, the high-pass filter <NUM> may be configured to filter the output signal of the frequency shifter <NUM> to remove component signals that are associated with frequencies included in the second frequency range <NUM>.

The processor <NUM> may be configured to select the first component radio frequency signal from the second component radio frequency signals. Thus, the communication device <NUM> may be configured to effectively determine the first component radio frequency signal in an efficient manner.

In an example, the second component radio frequency signals may include second reference signals. The frequencies that are associated with the second reference signals may be included in a frequency range that has the same width as the second frequency range <NUM>. The processor <NUM> may be configured to determine the second shift frequency <NUM> based on the second reference signals. Thus, the communication device <NUM> may be configured to efficiently and effectively reduce the loss of reference signals that are required for reliably processing the radio frequency signal.

In an example, the second reference signals may be in accordance with the radio communication technology.

In an example, the processor <NUM> may be configured to determine the second frequencies based on a radio communication technology.

In an example, the processor may be configured to determine the frequencies that are associated with the second component radio frequency signals based on a fast frequency hopping pattern in accordance with the radio communication technology. In an example, the second frequencies are associated with a resource block based on the Long Term Evolution radio communication technology.

<FIG> shows a schematic diagram of component radio frequency signals based on the second signal which are processed based on the communication device based on <FIG>. The second signal may be based on the third radio frequency signal. Further, the third radio frequency signal may be in accordance with the Long Term Evolution communication technology.

In an example, the radio frequency signal may be in accordance with the Long Term Evolution radio communication technology.

A first slot <NUM> based on the second signal may be associated with time periods <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. Further, a second slot <NUM> may be associated with time periods <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. Each component signal of the component signals <NUM> to <NUM> may include resource elements that are associated with the time periods <NUM> to <NUM>, respectively. The resource elements may include reference signals, respectively. Each reference signal may be based on a type of a plurality of types of reference signals. Resource elements that include cell specific reference signals may be indicated by diagonal hatching, as for example resource element <NUM>. Resource elements that include demodulation reference signals may be indicated by vertical hatching, as for example resource element <NUM>. Resource elements that include channel state information reference signals may be indicated by horizontal hatching, as for example resource element <NUM>.

Each component radio frequency signal of the third radio frequency signal may include at least one number of resource elements that include reference signals of at least one type and are associated with the slots <NUM> and <NUM>. In an example, the processor <NUM> may be configured to select the first component radio frequency signal based on the numbers of resource elements that include reference signals, for example reference signals of a type, and are associated with at least one of the slots <NUM> and <NUM>.

In an example, the second component radio frequency signals may be based on the component signals <NUM> to <NUM> of slot <NUM>, <NUM> or both slots <NUM> and <NUM>.

Thus, the communication device <NUM> may be configured to flexibly and efficiently determine the resource elements that are required to enhance a performance of the communication device <NUM>. Further, the communication device <NUM> may be configured to reduce the number of hybrid automatic repeat requests (HARQ).

In an example, the second component radio frequency signals include fourth signals. The processor <NUM> may be configured to determine the first component radio frequency signal based on a first number of the fourth signals.

In an example, the second component radio frequency signal include fourth signals. The processor <NUM> may be configured to determine the first component radio frequency signal based on types of the fourth signals.

Thus, the communication device <NUM> may be configured to flexibly determine the shift frequency <NUM> in an efficient manner.

In an example, the fourth signals are reference signals.

In an example, the second component radio frequency signals are associated with first numbers of reference signals of the second component radio frequency signals, respectively. The processor <NUM> may be configured to determine the first component radio frequency signal such that a number of reference signals of the first component radio frequency signal is the smallest number from the first numbers. Thus, the communication device <NUM> may be configured to effectively determine the shift frequency <NUM> in an efficient manner.

In an example, the second component radio frequency signals are associated with first numbers of reference signals of the second component radio frequency signals, respectively. Moreover, first weights are associated with types of the reference signals of the second component radio frequency signals. Further, the first numbers are associated with the first weights based on the types of the reference signals. First weighted numbers are weighted based on the first numbers and the first weights. Further, the second component radio frequency signals are associated with second numbers of fourth signals of the second component radio frequency signals, respectively. The fourth signals exclude reference signals. Second weights are associated with types of the fourth signals. Further, the second numbers are associated with the second weights based on the types of the fourth signals. Second weighted numbers are weighted based on the second numbers and the second weights. The processor <NUM> may be configured to select the first component radio frequency signal based on the first weighted numbers and the second weighted numbers. Thus, the processor <NUM> may be configured to effectively process the radio frequency signal in the baseband in a flexible manner.

It should be noted that aspects of communication device based on <FIG> may be combined with aspects of the communication devices based on <FIG> and <FIG>.

<FIG> shows a schematic diagram of a communication device <NUM> that may include a receiver <NUM> and a processor <NUM>. The receiver <NUM> may be configured to receive a radio frequency signal.

Further, the processor <NUM> may be configured to determine the second signal based on the radio frequency signal. The processor may be configured to determine the second signal from shifting frequencies related to the radio frequency signal represented in the frequency domain by a shift frequency.

The processor <NUM> may be configured to determine a baseband frequency based on the first component radio frequency signal. The first component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain.

Thus, the communication device <NUM> may be configured to efficiently and effectively reduce the loss of signals that are required for reliably processing the radio frequency signal. Moreover, the communication device <NUM> may be configured to efficiently and effectively process the radio frequency signal. By adapting the baseband frequency based on the first component radio frequency signal, the processor <NUM> may be configured to enhance the performance of the communication device <NUM>.

<FIG> shows a schematic diagram of frequencies that may be associated with the radio frequency signal represented in the frequency domain and frequencies that may be associated with the second signal represented in the frequency domain based on the communication device based on <FIG>. The diagram may have a first axis <NUM> that may indicate the frequencies and a second axis <NUM> that may indicate time.

The radio frequency signal may include the third radio frequency signal that may be associated with the third frequency range <NUM>. The third frequency range <NUM> may include the center frequency <NUM> of the third frequency range <NUM> and the first frequency <NUM>.

The communication device <NUM> may be configured to shift the third frequency range <NUM> by a third shift frequency <NUM> to a processing frequency range <NUM> that is included in the filter frequency range <NUM>. Further, the processor <NUM> may be configured to shift the center frequency <NUM> of the third frequency range <NUM> by the third shift frequency <NUM> to a third frequency <NUM> that may be included in a filter frequency range <NUM>. In an example, the third frequency <NUM> may be the center frequency of the filter frequency range <NUM>.

In an example, the filter frequency range <NUM> may be the baseband frequency range based on a shifted signal that is shifted based on the radio frequency signal.

In an example, the filter frequency range <NUM> may be the baseband frequency range of the second signal.

The processor <NUM> may be configured to determine a baseband frequency <NUM> such that the first frequency <NUM> is shifted to the baseband frequency <NUM> based on the third shift frequency <NUM>. Further, the communication device <NUM> may be configured to process the second signal based on the baseband frequency <NUM>.

In an example, the processor <NUM> may be configured to determine the baseband frequency <NUM> based on the radio frequency signal before the radio frequency signal is received by the receiver <NUM>.

In an example, the processor <NUM> may be configured to determine the baseband frequency <NUM> based on the received radio frequency signal.

The method may further include, in <NUM>, shifting frequencies based on the band-pass filtered signal and the baseband frequency <NUM> to form the second signal. The processor <NUM> may be configured to determine the baseband frequency <NUM> based on the first component radio frequency signal based on the radio frequency signal such that the first frequency <NUM> may be shifted to the baseband frequency <NUM>.

The method may further include, in <NUM>, low-pass filtering the second signal based on the filter frequency range <NUM>. The low-pass filtering may be configured to remove component radio frequency signals that are associated with frequencies that are not included in the frequency range that is associated with the second signal represented in the frequency domain.

The method may further include, in <NUM>, high-pass filtering the low-pass filtered signal based on a fifth frequency range. The high-pass filtering may be configured to remove a signal from the low-pass filtered signal that is associated with the fifth frequency range related to the low-pass filtered signal represented in the frequency domain. The fifth frequency range may be centered around the baseband frequency <NUM>.

The processor <NUM> may be configured to determine the baseband frequency <NUM> such that the high-pass filtering may remove a component signal based on the first component radio frequency signal. Thus, the communication device <NUM> may be configured to high-pass filter independent from the condition that the signal to be filtered includes the distortion signal. In case the signal to be filtered includes the distortion signal the high-pass filtering may be configured to remove the distortion signal by filtering based on the fifth frequency range.

In an example, the processor <NUM> may be configured to determine the baseband frequency <NUM> such that the high-pass filtering may only remove a group of subcarrier component radio frequency signals that may be included in the fourth frequency range centered around the first frequency <NUM>.

<FIG> shows a schematic diagram of component signals based on the second signal which are processed based on the communication device based on <FIG>. The second signal may be based on the third radio frequency signal.

Each component radio frequency signal of the third radio frequency signal may include at least one number of resource elements that include reference signals of at least one specified type and are associated with the slots <NUM> and <NUM>. The processor <NUM> may be configured to select the first component radio frequency signal from the component radio frequency signals of the third radio frequency signal. In an example, the processor <NUM> may be configured to select the first component radio frequency signal based on the numbers of resource elements that include reference signals of a specified type and are associated with the slots <NUM> and <NUM>.

The processor <NUM> may be configured to determine the baseband frequency <NUM> based on a frequency difference of the first frequency <NUM> and the center frequency <NUM> of the third frequency range <NUM>.

The processor <NUM> may be configured to determine the baseband frequency <NUM> such that the fifth frequency range referenced by <NUM> excludes frequencies that are associated with resource elements that include reference signals of cell specific reference signals and demodulation reference signals. Thus, the communication device <NUM> may be configured to flexibly and efficiently determine the type of resource elements that are required to enhance a performance of the communication device. Further, the communication device <NUM> may be configured to reduce the number of hybrid automatic repeat requests.

In an example, the third component radio frequency signals may be based on the second signal. Further, the processor <NUM> may be configured to determine the fourth component signal based on the FFT process based on the third component signals. The processor <NUM> may be configured to determine the baseband frequency <NUM> based on the third component signals. For example, the processor <NUM> may be configured to select component signals based on the third radio frequency signal such that the third component signals exclude reference signals, exclude reference signals of a type of reference signal and/or include a number of reference signals that is smaller than a threshold. Thus, the communication device <NUM> may be configured to effectively avoid the loss of reference signals to increase the performance of the communication device <NUM>. Further, the communication device <NUM> may be configured to flexibly process signals based on an uncomplex high-pass filter.

In an example, the second component radio frequency signals include second reference signals. The frequencies that are associated with the second reference signals may be included in a frequency range that has the same width as the fifth frequency range <NUM>. The processor <NUM> may be configured to determine the baseband frequency <NUM> based on the second reference signals. Thus, the communication device <NUM> may be configured to efficiently and effectively reduce the loss of reference signals that are required for reliably processing the radio frequency signal.

It should be noted that aspects of communication device based on <FIG> may be combined with aspects of the communication devices based on <FIG>, <FIG> and <FIG>.

<FIG> shows a schematic diagram of a communication device <NUM> that may include a receiver <NUM>, first filter <NUM>, a frequency mixer <NUM>, a second filter <NUM>, a third filter <NUM>, a Fast Fourier Transform circuit <NUM>, a signal selection circuit <NUM>, a phase rotation circuit <NUM> and a processor <NUM>. The processor <NUM> may be based on the processor <NUM> of the communication device <NUM> based on <FIG> or the processor <NUM> of the communication device <NUM> based on <FIG>. The processor <NUM> may be configured to determine the second shift frequency <NUM> or the baseband frequency <NUM> based on the first component radio frequency signal based on the radio frequency signal. The radio frequency signal may include the third radio frequency signal.

The receiver <NUM> may be configured to receive a radio frequency signal and output the radio frequency signal to the first filter <NUM>.

The first filter <NUM> may be a band-pass filter configured to filter a frequency band that includes the first component radio frequency signal based on the radio frequency signal to form an output signal.

The frequency mixer <NUM> may be configured to receive the output signal of the first filter <NUM>. Further, the frequency mixer <NUM> may be configured to shift frequencies based on the received output signal to form an output signal.

In an example, the processor <NUM> may be configured to determine second signal to noise ratios based on the second component radio frequency signals. Further, the processor <NUM> may be configured to select a smallest signal to noise ratio from the signal to noise ratios. The frequency mixer <NUM> may be configured to shift the frequencies based on the radio frequency signal by the second shift frequency only if the smallest signal to noise ratio is greater than a threshold. Thus, the communication device <NUM> may be configured to ensure a reliable processing of reference signals in bad radio conditions.

The second filter <NUM> may be configured to receive the output signal of the frequency mixer <NUM>. Further, the second filter <NUM> may be a low-pass filter configured to filter the received output signal based on a filter frequency range to form an output signal.

In an example, the filter frequency range may be the filter frequency range <NUM>.

In an example, the filter frequency range may be the processing frequency range <NUM>.

In an example, the baseband frequency range may be included in the filter frequency range <NUM> and based on the baseband frequency <NUM>.

In an example, the processor <NUM> may be configured to determine the filter frequency range based on the third frequency range <NUM> and the frequency difference based on the center frequency <NUM> of the third frequency range <NUM> and the first frequency <NUM>.

The third filter <NUM> may be configured to receive the output signal of the second filter <NUM>. Further, the third filter <NUM> may be a high-pass filter configured to preserve component signals that are associated with frequencies different from the second frequency range <NUM> and to remove component signals that are associated with frequencies that are included in the second frequency range <NUM> based on the received output signal to form an output signal.

The Fast Fourier Transform circuit <NUM> may be configured to receive the output signal of the third filter <NUM>. Further, the Fast Fourier Transform circuit <NUM> may be configured to process the received output signal based on a FFT process to form an output signal.

The FFT process may be based on a FFT processing bandwidth that is independent from the selection of the first component radio frequency signal and the corresponding shift frequency or baseband frequency.

In an example, the FFT process may be based on a <NUM> point Fast Fourier Transform process. In case the received third radio frequency signal is in accordance with the Narrowband Internet of Things communication technology the FFT process may be based on a sixteen point Fast Fourier Transform process.

The signal selection circuit <NUM> may be configured to receive the output signal of the Fast Fourier Transform circuit <NUM>. Further, the signal selection circuit <NUM> may be configured to select component signals and/or resource elements based on the received output signal and the baseband frequency range to form an output signal.

The phase rotation circuit <NUM> may be configured to receive the output signal of the signal selection circuit <NUM>. Further, the phase rotation circuit <NUM> may be configured to rotate phases based on the received output signal and a rotation of the phases based on the Fast Fourier Transform process.

It should be noted that aspects of communication device based on <FIG> may be combined with aspects of the communication devices based on <FIG>, <FIG>, <FIG> and <FIG>.

<FIG> shows a flow diagram that illustrates a process based on a communication device based on <FIG>, <FIG>, <FIG> or <FIG>.

In <NUM>, the communication device may start a new enhanced machine type communications (eMTC) connection or connect to a new serving cell. Further, the receiver may be configured to receive a radio frequency signal. Further, the radio frequency signal may include the first signal that may include at least one narrowband signal. The at least one narrowband signal may be associated with frequencies of a narrowband frequency range related to the radio frequency signal represented in the frequency domain. The first signal may be associated with the first frequency range related to the first signal represented in the frequency domain.

In <NUM>, the processor may determine if the radio frequency signal of the new connection includes more than one narrowband signals. If the processor determines that the radio frequency signal includes more than one narrowband signals the processor may proceed to <NUM>. If the processor determines that the radio frequency signal includes at most one narrowband signal the processor may proceed to <NUM>.

In <NUM>, the processor may select a narrowband signal from the narrowband signals. Further, the processor may determine the difference of a narrowband center frequency and a baseband frequency of the selected narrowband signal.

In <NUM>, the processor may determine second subcarrier frequencies that are associated with reference signals that are included in a first subframe.

In <NUM>, the processor may determine selection parameters based on second component radio frequency signals that may be associated with the second subcarrier frequencies. A selection parameter of a component radio frequency signal of the second component radio frequency signals may be a signal to noise ratio based on the component radio frequency signal. The processor may be configured to determine a quality of service based on the selection parameters.

In an example, the selection parameter of a component radio frequency signal may be relative to a parameter based on a second subframe that precedes the first subframe. For example, the selection parameter of the component radio frequency signal may be a ratio of the determined signal to noise ratio to a signal to noise ratio based on the second subframe.

In <NUM>, the processor may select a subcarrier frequency from the second subcarrier frequencies based on the determined selection parameters. In an example, the processor may be configured to select the subcarrier frequency that is associated with the component radio frequency signal that is based on the smallest signal to noise ratio or the smallest ratio of signal to noise ratios.

In <NUM>, the processor may compare the determined selection parameter of the selected subcarrier frequency with a threshold. If the signal to noise ratio or the ratio of signal to noise ratios of the selected subcarrier frequency is greater than the threshold the processor may proceed to <NUM>. If the signal to noise ratio or the ratio of signal to noise ratios of the selected subcarrier frequency is smaller than the threshold the processor may proceed to <NUM>.

In <NUM>, the processor may determine the shift frequency based on at least one of <FIG>, <FIG>, <FIG>, <FIG>, <FIG> or <FIG> or the baseband frequency based on at least one of <FIG>, <FIG>, <FIG>, <FIG> or <FIG>. Further, the processor may be configured to wait for the next subframe to be handled.

In <NUM>, the processor may determine a low intermediate frequency based on a narrowband center frequency and a narrowband frequency range.

The processor may be configured to determine a fourth shift frequency. The fourth shift frequency may be a difference of the narrowband center frequency and the baseband frequency. Thus, the fourth shift frequency may be a center offset frequency. Further, the processor may be configured to determine a fifth shift frequency based on the narrowband frequency range. The fifth shift frequency may be an intermediate frequency. The fifth shift frequency may be greater than the narrowband frequency range divided by two. The processor may be configured to determine a fifth signal based on shifting frequencies based on the radio frequency signal by the fourth shift frequency and the fifth shift frequency. The frequency shifter may be configured to shift the narrowband frequency range to a baseband frequency range such that the baseband frequency is not included in the shifted narrowband frequency range. Further, the communication device may be configured to perform the method based on <FIG>. Thus, the communication device may be configured to effectively process the radio frequency signal in bad radio conditions.

Moreover, the processor may be configured to wait for the next subframe to be handled.

In <NUM>, the processor may determine if the eMTC connection is to be terminated. Further, in an example, the processor may determine if the serving cell changed. If the eMTC connection is not to be terminated and the serving cell is unchanged the processor may proceed to <NUM>. If the eMTC connection is to be terminated or the serving cell is changed the processor may proceed to <NUM>.

In <NUM>, the processor may determine if a narrowband center frequency of a third subframe that follows the first subframe is different from the narrowband center frequency of the first subframe. If the narrowband center frequency of the third subframe is different from the narrowband center frequency of the first subframe the processor may proceed to <NUM>. If the narrowband center frequency of the third subframe is the same as the narrowband center frequency of the first subframe the processor may proceed to <NUM>.

In <NUM>, the processor may terminate the eMTC connection or receive a termination notice thereof.

In <NUM>, the processor may determine a sixth shift frequency based on the center frequency of the first frequency range. The sixth shift frequency may be a difference of the center frequency of the first frequency range and the baseband frequency. The processor may determine a seventh signal based on shifting frequencies based on the radio frequency signal and the sixth shift frequency. Further, the processor may be configured to perform the method based on <FIG> based on the first signal, the first frequency range and the sixth shift frequency. Moreover, the processor may be configured to wait for the next subframe to be handled.

In <NUM>, the processor may determine if the eMTC connection is to be terminated. Further, in an example, the processor may determine if the serving cell changed. If the processor determines that the eMTC connection is not to be terminated and the serving cell is unchanged the processor may proceed to <NUM>. If the processor determines that the eMTC connection is to be terminated or the serving cell is changed the processor may proceed to <NUM>.

<FIG> shows a flow diagram that illustrates a method based on <FIG>.

The method may include, in <NUM>, receiving a radio frequency signal.

The method may further include, in <NUM>, band-pass filtering the radio frequency signal to filter a frequency band that includes the narrowband frequency range.

The method may further include, in <NUM>, shifting frequencies based on the filtered radio frequency signal based on the fourth shift frequency and the fifth shift frequency to form a sixth signal. The shifted narrowband frequency range may not include the baseband frequency.

The method may further include, in <NUM>, low-pass filtering the sixth signal to remove component signals that are associated with frequencies that are not included in a filter frequency range. The filter frequency range may be based on the narrowband frequency range, the fourth shift frequency, the fifth shift frequency and the baseband frequency. The filter frequency range may include the shifted narrowband frequency range.

The method may further include, in <NUM>, high-pass filtering the low-pass filtered signal based on the second frequency range.

The method may further include, in <NUM>, shifting frequencies based on the high-pass filtered signal based on the fifth shift frequency such that a center frequency of the frequency shifted narrowband frequency range is shifted to the baseband frequency.

The method may further include, in <NUM>, low-pass filtering the frequency shifted signal to remove component signals that are associated with frequencies that are not included in a frequency shifted narrowband frequency range.

The method may further include, in <NUM>, processing the low-pass filtered signal of <NUM> based on a FFT process.

The method may further include, in <NUM>, selecting frequencies based on the FFT processed signal and the narrowband signal.

The method may further include, in <NUM>, rotating phases of component signals based on the FFT processed signal and the selected frequencies. The rotating may be configured to compensate a rotation based on a cyclic prefix and the FFT process.

Thus, the communication device may be configured to effectively process the radio frequency signal in bad radio conditions.

In an example, the frequency shifting based on <NUM> may be configured to shift the frequencies based on the radio frequency signal based on a sum, or in an example a difference, of the fourth shift frequency and the fifth shift frequency.

In an example, the method may be performed based on the communication device based on <FIG>.

In an example, if the processor determines that each component radio frequency signal of the second component radio frequency signals includes a reference signal the frequency mixer may be configured to shift the frequencies based on the radio frequency signal by the fourth shift frequency and the fifth shift frequency.

The method may further include, in <NUM>, shifting frequencies based on the filtered signal based on the sixth shift frequency to form the seventh signal. The shifted narrowband frequency range may not include the baseband frequency.

The method may further include, in <NUM>, low-pass filtering the seventh signal to remove component signals that are associated with frequencies that are not included in the shifted narrowband frequency range. The filter frequency range may be based on the narrowband frequency range, the fourth shift frequency and the baseband frequency.

The method may further include, in <NUM>, processing the high-pass filtered signal based on a FFT process.

Thus, the communication device may be configured to increase the performance in bad radio conditions.

In an example, the method may be performed based on the communication device based on <FIG>. If the processor determines that the radio frequency signal includes at most one narrowband signal the frequency mixer may be configured to shift the frequencies based on the radio frequency signal by the fourth shift frequency.

<FIG> shows a method for radio frequency communication.

The method may further include, in <NUM>, determining a shift frequency based on a component radio frequency signal. The component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain.

The method may further include, in <NUM>, determining a second signal based on the radio frequency signal. The second signal may be determined from shifting frequencies related to the radio frequency signal represented in the frequency domain by the shift frequency.

Thus, the method may be configured to efficiently and effectively process the radio frequency signal. Further, the method may be configured to efficiently reduce the loss of signals that are required to reliably process the radio frequency signal.

In an example, the method of <FIG> may be performed by a communication device based on <FIG>.

The method may include, in <NUM>, determining a second signal based on the radio frequency signal. The second signal may be determined from shifting frequencies related to the radio frequency signal represented in the frequency domain by a shift frequency.

The method may include, in <NUM>, determining a baseband frequency based on a component radio frequency signal. The component radio frequency signal may be dependent from the radio frequency signal and associated with a frequency related to the radio frequency signal represented in the frequency domain.

It should be noted that aspects of the examples of <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG> may be combined with aspects of the above described methods.

Claim 1:
A communication device (<NUM>), comprising:
a receiver (<NUM>) configured to receive a radio frequency signal,
wherein the radio frequency signal is in accordance with a Long Term Evolution radio communication technology,
wherein the radio frequency signal comprises a first radio frequency signal that is associated with a first frequency range (<NUM>) related to a frequency domain representation of the radio frequency signal,
a processor (<NUM>) configured to determine
a shift frequency (<NUM>), based on a component radio frequency signal; and
a second signal based on the radio frequency signal,
wherein the first radio frequency signal comprises the component radio frequency signal that is associated with a second frequency range (<NUM>) that includes a first subcarrier frequency (<NUM>) related to a frequency domain representation of the radio frequency signal,
wherein the first frequency range (<NUM>) comprises the second frequency range (<NUM>),
wherein the second signal is determined based on shifting frequencies of the second frequency range (<NUM>) by the shift frequency (<NUM>) to a baseband frequency range (<NUM>, <NUM>),
wherein the baseband frequency range (<NUM>, <NUM>) comprises a filter frequency range (<NUM>) to remove the shifted component radio frequency signal,
wherein the processor (<NUM>) is configured to determine the shift frequency (<NUM>) such that the first subcarrier frequency (<NUM>) is shifted to a baseband frequency (<NUM>) that is included in the filter frequency range (<NUM>).