Patent Description:
In massive multiple-input multiple-output (MIMO), the radio base-station (RBS) is equipped with a large number (e.g., hundreds) of antenna elements to serve a number (e.g., tens) of user equipment (UE) in the same time-frequency resource. This enables significant gains in spectral efficiency and energy efficiency. To fully exploit the gains provided by the large antenna array in massive MIMO, each antenna element might be equipped with set of analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). Such architectures will hereinafter be referred to as digital-beamforming architectures. The digital-beamforming architecture is implemented in a radio transceiver device. However, in order to keep costs and power consumption within tolerable limits when scaling up the number of antenna elements in such digital-beamforming architectures, and thus in the radio transceiver device, low-precision (e.g., <NUM>-<NUM> bits) ADCs and DACs may have to be used at the RBS. This inevitably leads to reduced system performance. Massive MIMO is robust, to some extent, towards the use of low-resolution ADCs and DACs at the RBS.

Most available analyses of the use of low-precision data converters (i.e., ADCs and DACs) in massive MIMO have considered the case of direct-conversion transceivers at the RBS, where mixers are required at each antenna element to perform down-conversion and up-conversion of the radio frequency (RF) signal to baseband, and vice versa. In the receiver part of a direct-conversion transceiver, the in-phase (I) and quadrature (Q) components of the received signal are converted from the analog domain into the digital domain using a pair of ADCs; one for the I component and one for the Q component. Conversely, in the transmitter part of a direct-conversion transceiver, the I and Q components of the transmit signal are generated by a pair of DACs; one for the I component and one for the Q component.

Recent advances in data-converter technology have opened up the possibility to design radio transceivers that samples the RF signal almost directly at the antenna, without the need of analog up-conversion and down-conversion. In such RF-sampling transceivers, by bringing high-speed ADCs and DACs physically closer to the antenna, much of the conventional RF circuitry (e.g., oscillators, filters and, mixers) is replaced by a digital signal processor (DSP). RF-sampling transceivers also bring more flexibility as the desired signal can be processed in the digital domain, whereas conventional direct-conversion transceivers have to be tailored for a particular carrier frequency. In RF-sampling transceivers, the sampling rate of the ADCs and DACs is in the order of several Giga samples per second (GS/s). Since the power consumption of ADCs and DACs scale roughly linearly with the sampling rate and exponentially with the resolution (i.e. with the number of bits), low-precision ADCs and DACs for RF-sampling systems, not only for massive MIMO systems but also for single-input single-output (SISO) systems and small-scale MIMO systems have been designed. For example, a <NUM>-bit RF-sampling transmitter design and a <NUM>-bit RF-sampling receiver design have been proposed.

Taking time-division duplexing (TDD) operation in a massive MIMO up-link (UL) system, i.e., when the UEs transmit to the RBS, as an example, it is known that operating at high signal-to-noise ratio (SNR) may lead to a performance degradation in some scenarios when low-resolution (e.g., <NUM>-bit) ADCs are used at the RBS. For example, it is not possible to support M-quadrature amplitude modulation (QAM) constellations, for M><NUM>, under certain channel conditions.

Further, as the UEs become more and more advanced, also the UEs might be provided with a similar digital-beamforming architecture as the RBS.

In "<NPL>, is disclosed how to build arrays that enable multiuser massive multiple-input-multiple-output (MIMO) and aggressive spatial multiplexing with many users sharing the same spectrum. The focus is energy- and cost-efficient realization of these arrays in order to enable new applications.

<CIT> relates to techniques and mechanisms for adding dithering noise to a receiver to reduce harmonics.

<CIT> relates to a semiconductor integrated circuit device having A/D converters for converting, by means of digital correction processing, analog input signals into digital signals is reduced in area. Hence, there is still a need for improved digital-beamforming architectures, and thus improved radio transceiver devices.

An object of embodiments herein is to provide a radio transceiver device not suffering from the issues noted above (e.g. performance degradation), or at least where the above noted issues have been mitigated or reduced.

<FIG> is a schematic diagram illustrating a communications network <NUM> where embodiments presented herein can be applied. The communications network <NUM> comprises a radio access network node <NUM> configured to provide network access over one or more radio propagation channels to a terminal device <NUM> in a radio access network <NUM>. Non-limited examples of terminal devices <NUM> are portable wireless devices, mobile stations, mobile phones, handsets, wireless local loop phones, user equipment (UE), smartphones, laptop computers, tablet computers, network equipped sensors, network equipped vehicles, and Internet of Things (IoT) devices. In some embodiments the radio access network node <NUM> is part of, integrated with, or collocated with a radio base station, base transceiver station, node B, evolved node B, gNB, access point, or the like. The radio access network <NUM> is operatively connected to a core network <NUM>. The core network <NUM> is in turn operatively connected to a packet data network <NUM>, such as the Internet. The terminal device <NUM> is thereby, via the radio access network node <NUM>, enabled to access services of, and exchange data with, the service network <NUM>. Each of the radio access network node <NUM> and the terminal device <NUM> comprises a respective radio transceiver device <NUM>.

As noted above, there is still a need for improved digital-beamforming architectures, and thus improved radio transceiver devices <NUM>. The above noted issue of performance degradation can be mitigated to some extent by dithering (i.e., by intentionally adding noise prior to quantizing the received signal using the low-resolution ADCs). Implementing dithering functionality at the receiver, however, requires equipping the radio transceiver device <NUM> with additional hardware circuitry and, hence, incur additional costs and circuit power consumption. This issue is especially significant for massive MIMO systems employing large antenna arrays (and, hence, a large number of ADCs), and for RF-sampling systems in which the ADCs and the dither source (e.g., a plurality of DACs) need to operate at high sampling rates.

The embodiments disclosed herein therefore relate to a radio transceiver device <NUM>, where the radio transceiver device <NUM> is configured for dithering of a received signal in an efficient manner. Embodiments disclosed herein further relate to a method performed by communication device 140a, <NUM>, such as a radio access network node <NUM> or a terminal device <NUM> comprising the radio transceiver device <NUM> for receiving a dithering a signal. Embodiments disclosed herein further relate to a computer program product comprising code, for example in the form of a computer program, that when run on a communication device 140a, <NUM>, such as a radio access network node <NUM> or a terminal device <NUM> comprising the radio transceiver device <NUM>, causes the communication device <NUM>, <NUM> comprising the radio transceiver device <NUM> to perform the method.

Parallel reference will now be made to <FIG>, <FIG>, and <FIG> which illustrate a radio transceiver device <NUM> according to embodiments disclosed herein.

The radio transceiver device <NUM> comprises an antenna <NUM>. The antenna might be part of an antenna array. The antenna array might be a linear array or a two-dimensional array. The radio transceiver device <NUM> further comprises a signal processing module <NUM>. The signal processing module <NUM> might be a DSP and be configured to operate either in baseband, in intermediate frequency, in radio frequency, or any combination thereof, depending on the type of radio transceiver device <NUM>.

The radio transceiver device <NUM> further comprises a receiver chain <NUM>. The receiver chain <NUM> is configured to receive a first signal. The receiver chain <NUM> extends from the antenna <NUM> to the signal processing module <NUM>. The receiver chain <NUM> at least comprises an ADC <NUM>. The receiver chain <NUM> is thereby configured to receive a first signal from the antenna <NUM> and provide the first signal to the signal processing module <NUM> after application of analog-to-digital conversion in the ADC <NUM> to the first signal. Examples of further components of the receiver chain <NUM> will be provided below.

The radio transceiver device <NUM> further comprises a transmitter chain <NUM>. The transmitter chain <NUM> extends from the signal processing module <NUM> to the antenna <NUM>. The transmitter chain <NUM> at least comprises a DAC <NUM>. The transmitter chain <NUM> is thereby configured to receive a second signal from the signal processing module <NUM> and provide the second signal to the antenna <NUM> after application of digital-to-analog conversion in the DAC <NUM>. Examples of further components of the transmitter chain <NUM> will be provided below.

The DAC <NUM> is configured to generate a dither signal. The DAC <NUM> is connected to the receiver chain <NUM> for application of the dither signal to the first signal before application of analog-to-digital conversion in the ADC <NUM> to the first signal.

Such a radio transceiver device <NUM> enables a hardware-efficient and low-cost implementation of dithering of a received signal, for example during the uplink phase of a TDD system (if the radio transceiver device <NUM> is provided in a radio access network node <NUM> and is configured for TDD operation) by reusing already-existing hardware circuitry found in the transmitter chain <NUM> of the radio transceiver device <NUM> which during TDD operation commonly is used only during the downlink phase (if the radio transceiver device <NUM> is provided in a radio access network node <NUM>). Specifically, the dither signal, which is added to the received signal in the analog domain prior to the ADC <NUM>, is generated by the DAC <NUM> used also in the transmitter chain <NUM>.

Embodiments relating to further details of the radio transceiver device <NUM> will now be disclosed.

According to some aspects, the power of the dither signal is a function of the power of the received signal (i.e., of the first signal). This can be achieved by using automatic gain control (AGC) and a variable-gain amplifier (VGA) at each antenna element of the receiver. If the radio transceiver device is a multi-antenna radio transceiver device and thus the antenna <NUM> is part of an antenna array, an estimate of the received power could be obtained using only one or few AGCs for the entire antenna array of the radio transceiver device <NUM>. Hence, according to an embodiment the radio transceiver device <NUM> further comprises a signal power adjuster <NUM> (such as an AGC or a VGA). The DAC <NUM> might then be connected to the receiver chain <NUM> via the signal power adjuster <NUM>. Further, the dither signal is power adjusted by the signal power adjuster <NUM> before being applied to the first signal. In some embodiments the dither signal is power adjusted as a function of the power of the first signal.

According to some aspects, the dither signal, generated by the DAC <NUM>, is made dependent on previous samples of the received signal (i.e., of the first signal) after quantization by the ADC <NUM> and after being processed by the signal processing module <NUM>. Hence, according to an embodiment, application of the ADC <NUM> results in samples of the first signal being produced, and the radio transceiver device <NUM> implements a feedback mechanism, where the dither signal is, via the feedback mechanism, made dependent on previous samples of the first signal. The feedback mechanism might be implemented in the signal processing module <NUM>.

According to some aspects, the sampling rate and/or the resolution (i.e., the number of bits) of the ADC <NUM> (in the receiver chain <NUM>) and the DAC <NUM> (in the transmitter chain <NUM>) need not be equal. In some non-limiting examples, the DAC <NUM> has higher sampling rate and/or the resolution than the ADC <NUM>. For example, the ADC <NUM> might be a <NUM>-bit ADC.

According to some aspects, the dither signal, generated by the DAC <NUM>, is processed in the analog domain (for example, by means of filtering and/or passing through a nonlinear device) before being combined with the received signal (i.e., with the first signal). Hence, according to an embodiment the radio transceiver device <NUM> further comprises a filter <NUM>. The DAC <NUM> might then be connected to the receiver chain <NUM> via the filter <NUM>. The dither signal might then be filtered by the filter <NUM> before being applied to the first signal. There could be different types of filters <NUM>. For example, the filter <NUM> could be any of: a low-pass filter, a high-pass filter, a bandpass filter, or a band-stop filter. For example, if the first signal occupies a given frequency band, it might be desirable that the dither signal occupies some other frequency band (to not interfer with the first signal). This can be achieved by filtering. Furthermore, filtering might have an impact on the probability distribution of the dither signal, which can be beneficical in some scenarios in which the amplitude levels supported by the DAC <NUM> is constrained. In some aspects, the filter <NUM> is designed to be dependent on the received signal (i.e., on the first signal). In particular, in some embodiments the filter <NUM> has a filter response that is dependent on properties of the first signal.

There could be different ways for the dither signal to be generated.

In some aspects, the dither signal equals the second signal (i.e., the signal to be transmitted) as outputted from the DAC <NUM>. That is, according to an embodiment, the dither signal is defined by the second signal after application of digital-to-analog conversion in the DAC <NUM> to the second signal.

In other aspects, the dither signal is generated in the DAC <NUM> from another signal than the second signal. This another signal is hereinafter denoted an auxiliary signal. That is, according to an embodiment, the DAC <NUM> is configured to generate the dither signal by performing digital-to-analog conversion of an auxiliary signal being fed to the DAC <NUM>.

Regardless if the dither signal equals the second signal as outputted from the DAC <NUM> or is generated in the DAC <NUM> from another signal than the second signal, the dither signal might be subjected to filtering by the filter <NUM> as disclosed above.

The dither signal might be subtractive dither (SD) or non-subtractive dither (NSD). That is, according to an embodiment, the dither signal represents SD or NSD. For the case of SD, the dither signal (or a function thereof) is subtracted from the quantized signal in the signal processing module <NUM> unit. For the case of NSD, the dither signal (or a function thereof) is not subtracted from the quantized signal in the signal processing module <NUM>.

In general terms, the first signal as received from the antenna <NUM> by the receiver chain <NUM> is in the radio frequency domain. There could be different places in the radio transceiver device <NUM> where the first signal is converted from the radio frequency domain to the baseband domain (and where the second signal is converted from the baseband domain to the radio frequency domain). Hence, there could be different types of radio transceiver devices <NUM>.

For example, the radio transceiver devices <NUM> might be implemented as a direct frequency domain transceiver in which signals are not up/down-converted between the antenna <NUM> and the signal processing module <NUM>. The signal processing module <NUM> then operates at least in the radio frequency domain and the baseband domain. Hence, according to an embodiment, the dither signal is applied to the first signal in the radio frequency domain. Such an embodiment of a radio transceiver device <NUM> is illustrated in <FIG> and in <FIG>.

For example, the radio transceiver device <NUM> might be implemented as a heterodyne transceiver in which signals are up/down-converted to an intermediate frequency between the antenna <NUM> and the signal processing module <NUM>. The signal processing module <NUM> then operates in the intermediate frequency domain and the baseband domain. In particular, according to an embodiment, the radio transceiver device <NUM> further comprises an intermediate frequency mixer <NUM>. The intermediate frequency mixer <NUM> is placed in the receiver chain <NUM>. The intermediate frequency mixer <NUM> is configured to convert the first signal from the radio frequency domain to intermediate frequency domain. The dither signal is then applied to the first signal in the intermediate frequency domain. The intermediate frequency mixer <NUM> might be operated by an oscillator <NUM>. Such an embodiment of a radio transceiver device <NUM> is illustrated in <FIG>.

For example, the radio transceiver device <NUM> might be implemented as a direct-conversion transceiver (also denoted homodyne, synchrodyne, or zero-IF transceiver) in which signals are directly up/down-converted between the radio frequency domain and the baseband domain between the antenna <NUM> and the signal processing module <NUM>. The signal processing module <NUM> then operates only in the baseband domain. In particular, according to an embodiment, the radio transceiver device <NUM> further comprises a radio frequency mixer <NUM>. The radio frequency mixer <NUM> is placed in the receiver chain <NUM>. The radio frequency mixer <NUM> is configured to convert the first signal from the radio frequency domain to baseband frequency domain. The dither signal is then applied to the first signal in the baseband frequency domain. The radio frequency mixer <NUM> might be operated by an oscillator <NUM>. Such an embodiment of a radio transceiver device <NUM> is illustrated in <FIG>.

In some examples the radio transceiver device <NUM> further comprises a low-noise amplifier (LNA) <NUM>. The LNA <NUM> is placed in the receiver chain <NUM> between the antenna <NUM> and the ADC <NUM>. In some examples the radio transceiver device <NUM> further comprises a power amplifier (PA) <NUM>. The PA <NUM> is placed in the transmitter chain <NUM> between the antenna <NUM> and the DAC <NUM>. In some embodiments the dither signal is applied to the first signal after application of the LNA <NUM> to the first signal, and in other embodiments the dither signal is applied to the first signal before application of the LNA <NUM> to the first signal. For example, If the LNA <NUM> is highly nonlinear it will introduce significant nonlinear distortion. This distortion will be correlated with the first signal, which can be performance-limiting in some scenarios (e.g., in large antenna arrays where uncorrelated noise is averaged out whereas correlated noise is not). This correlation can be decreased by means of dithering before the LNA <NUM>, which can lead to improved performance. If any nonlinear distortion caused by the LNA <NUM> is insignificant compared to the nonlinear distortion caused by the ADC <NUM>, the dither signal could be applied to the first signal after the LNA <NUM>.

There could be different ways in which the dither signal is applied to the received signal (i.e., to the first signal). In general terms, the dither signal might be applied to the received signal (i.e., to the first signal) in any linear or nonlinear fashion.

According to a first example, the dither signal is applied by means of addition. That is, according to some embodiments, the radio transceiver device <NUM> further comprises a combiner <NUM>. The DAC <NUM> is connected to the receiver chain <NUM> at the combiner <NUM>, and wherein the dither signal is applied to the first signal by, in the combiner <NUM>, being added to the first signal.

According to a second example, the dither signal is applied by means of multiplication. That is, according to some embodiments, the radio transceiver device <NUM> further comprises a mixer <NUM>. The DAC <NUM> is connected to the receiver chain <NUM> at the mixer <NUM>. The dither signal is applied to the first signal by, in the mixer <NUM>, being multiplied to the first signal.

In some aspects the dither signal is applied by being fed to a differential input port of the ADC <NUM>. That is, according to an embodiment, the ADC <NUM> comprises a comparator with differential input ports, and the dither signal is applied to the first signal by being fed to one of the differential input ports. Such an ADC <NUM> might be realized by a <NUM>-bit ADC <NUM>.

There could be different ways in which the radio transceiver device <NUM> is configured to operate. For example, the radio transceiver device <NUM> might be configured for either TDD operation or frequency-division duplex (FDD) operation. That is, according to some embodiments, the radio transceiver device <NUM> might be configured for TDD operation such that no second signal representing a message to be transmitted is provided to the antenna <NUM> when the first signal is provided to the signal processing module <NUM>, and vice versa. To prevent the dither signal from being transmitted over the air, an UL/DL switch <NUM> may be installed in the transmitter chain <NUM> (e.g., between the DAC <NUM> and the antenna <NUM>). According to other embodiments, the radio transceiver device <NUM> is configured for FDD operation such that the second signal is provided to the antenna <NUM> when the first signal is provided to the signal processing module <NUM>.

In some aspects the receiver chain <NUM> and the transmitter chain <NUM> are implemented using radio-over-fiber (ROF) and thus the antenna <NUM> and the signal processing module <NUM> are at least partly connected over optical fiber links <NUM>. Each optical fiber link <NUM> is at each end terminated by an enhanced small form-factor pluggable transceiver (SFP+) <NUM>. Such an embodiment of a radio transceiver device <NUM> is illustrated in <FIG>. The functionality of the aforementioned ADCs <NUM> and DACs <NUM> might then be provided by the SFP+ <NUM>. Alternatively, the radio transceiver device <NUM> of <FIG> comprises ADCs <NUM> provided in the receiver chain <NUM> between the antenna <NUM> and the LNA <NUM> and DACs <NUM> provided in the transmitter chain <NUM> between the antenna <NUM> and the PA <NUM>. However, for the purpose and scope of the herein disclosed embodiments, each SFP+ <NUM> is considered to be equal to the aforementioned ADCs <NUM> and DACs <NUM>, where appropriate.

<FIG> is a flowchart illustrating embodiments of a method for receiving a first signal using a radio transceiver device <NUM> according to any of the above disclosed embodiments. The methods are advantageously performed by communication device 140a, <NUM>, such as a radio access network node <NUM> or a terminal device <NUM>, comprising the radio transceiver device <NUM>. The method is advantageously provided as a computer program <NUM>.

S102: The first signal is received at the antenna <NUM>.

S104: The dither signal is applied to the first signal before the application of analog-to-digital conversion in the ADC <NUM> to the first signal.

S106: The first signal is provided to the signal processing module <NUM> after the dither signal has been applied and after analog-to-digital conversion in the ADC <NUM> has been applied to the first signal.

Numerical examples will be presented next to compare the proposed radio transceiver device <NUM> to state-of-the-art low-precision radio transceiver devices. The numerical examples are given for a radio transceiver device <NUM> provided in a radio access network node <NUM> and using RF-sampling in which <NUM>-bit ADCs <NUM> are used to quantize the received signal during the uplink phase and in which <NUM>-bit DACs <NUM> are used to generate the transmit signal during the downlink phase. Such a radio transceiver device <NUM> is illustrated in <FIG>. In what follows, the signal bandwidth is set to <NUM>, the carrier frequency is set to fcarrier = <NUM>. Furthermore, the sampling rate of the signal processing module <NUM>, the ADCs <NUM>, and the DACs <NUM> has been set to fsam = <NUM> GS/s.

The dither signal used in the numerical examples is NSD whose realizations have been drawn randomly from some probability distribution (e.g., uniform, Gaussian, etc.). Hence, the dither signal has not been tailored to the received signal. Only the power of the dither signal has been optimized for each value of SNR. Better performance can be achieved by jointly optimizing the dither signal and the power level and/or by considering SD that may be dependent on previous samples of the received signal.

In <FIG> are shown, for the SISO case and for the case of an additive white Gaussian noise (AWGN) channel, the received constellations for the cases of <NUM>-QAM with and without the proposed radio transceiver device <NUM> and with SNR = <NUM> dB. The constellation points of the transmitted signal are given by {+<NUM>, +<NUM>} for each of the I component and the Q component [Inventors: please fill in the values]. For the results in this figure has been assumed a dither signal drawn from a uniform binary distribution, which can be generated, e.g., using a radio transceiver device <NUM> in which the possible <NUM>-bit DAC outputs are limited to two levels. The proposed radio transceiver device <NUM> yields a more discernable <NUM>-QAM constellation compared to the state of the art.

In <FIG> is shown the mean squared error (MSE) of the received symbols for an assumed transmitted sequence of <NUM>-QAM symbols over a SISO additive white Gaussian noise (AWGN) channel with and without the proposed radio transceiver device <NUM> as a function of SNR. The SNR is given by Es/No, where Es is the symbol power and No is the receiver noise power. For the results in this figure has been assumed a dither signal drawn from a uniform binary distribution and a Gaussian distribution, respectively. The MSE resulting from the proposed radio transceiver device <NUM>, despite suboptimal choices for the dither signal, outperforms the state of the art in the high-SNR regime.

In <FIG> are shown, for the <NUM>-by-<NUM> single-input multiple-output (SIMO) case (i.e., a single transmit antenna and <NUM> receive antennas) and for the case of a Rayleigh fading channel, the received constellation for the cases of <NUM>-QAM with and without the proposed radio transceiver device <NUM> and with SNR = <NUM> dB. The constellation points of the transmitted signal are given by {±<NUM>, ±<NUM>, ±<NUM>, ±<NUM>} for each of the I component and the Q component [Inventors: please fill in the values]. For the results in this figure has been assumed a dither signal drawn from a uniform binary distribution [Inventors: is this correct?], which can be generated, e.g., using a radio transceiver device <NUM> in which the possible <NUM>-bit DAC outputs are limited to two levels. The proposed radio transceiver device <NUM> yields a more discernable <NUM>-QAM constellation compared to the state of the art.

In <FIG> is shown the MSE of the received symbols for an assumed transmitted sequence of <NUM>-QAM symbols over a <NUM>-by-<NUM> SIMO Rayleigh-fading channel with and without the proposed radio transceiver device <NUM> as a function of SNR. The SNR is given by Es/No, where Es is the symbol power and No is the receiver noise power. For the results in this figure has been assumed a dither signal drawn from a uniform binary distribution and a Gaussian distribution, respectively. The MSE resulting from the proposed radio transceiver device <NUM>, despite suboptimal choices for the dither signal, outperforms the state of the art in the high-SNR regime.

<FIG> schematically illustrates, in terms of a number of functional units, the components of a communication device 140a, <NUM>, such as a radio access network node <NUM> or terminal device <NUM> according to an embodiment. Processing circuitry <NUM> is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product <NUM> (as in <FIG>), e.g. in the form of a storage medium <NUM>. The processing circuitry <NUM> may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

Particularly, the processing circuitry <NUM> is configured to cause the communication device <NUM>, <NUM> to perform a set of operations, or steps, as disclosed above. For example, the storage medium <NUM> may store the set of operations, and the processing circuitry <NUM> may be configured to retrieve the set of operations from the storage medium <NUM> to cause the communication device <NUM>, <NUM> to perform the set of operations.

Thus the processing circuitry <NUM> is thereby arranged to execute methods as herein disclosed. The communication device <NUM>, <NUM> may further comprise a communications interface <NUM> at least configured for communications with another communication device, function, node, or entity. As such the communications interface <NUM> may comprise one or more transmitters and receivers, comprising analogue and digital components. In particularly, the communications interface <NUM> comprises a radio transceiver device <NUM> according to any of the above embodiments.

The processing circuitry <NUM> controls the general operation of the communication device <NUM>, <NUM> e.g. by sending data and control signals to the communications interface <NUM> and the storage medium <NUM>, by receiving data and reports from the communications interface <NUM>, and by retrieving data and instructions from the storage medium <NUM>. Other components, as well as the related functionality, of the communication device <NUM>, <NUM> are omitted in order not to obscure the concepts presented herein.

<FIG> schematically illustrates, in terms of a number of functional modules, the components of a communication device <NUM>, <NUM> according to an embodiment. The communication device <NUM>, <NUM> of <FIG> comprises a number of functional modules; a receive module 1210a configured to perform step S102, an apply module 1210b configured to perform step S104, and a provide module 1210c configured to perform step S106. The communication device <NUM>, <NUM> of <FIG> may further comprise a number of optional functional modules, as represented by functional module 1210d. In general terms, each functional module 1210a-1210d may in one embodiment be implemented only in hardware and in another embodiment with the help of software, i.e., the latter embodiment having computer program instructions stored on the storage medium <NUM> which when run on the processing circuitry makes the communication device <NUM>, <NUM> perform the corresponding steps mentioned above in conjunction with <FIG>. It should also be mentioned that even though the modules correspond to parts of a computer program, they do not need to be separate modules therein, but the way in which they are implemented in software is dependent on the programming language used. Preferably, one or more or all functional modules 1210a-1210d may be implemented by the processing circuitry <NUM>, possibly in cooperation with the communications interface <NUM> and/or the storage medium <NUM>. The processing circuitry <NUM> may thus be configured to from the storage medium <NUM> fetch instructions as provided by a functional module 1210a-1210d and to execute these instructions, thereby performing any steps as disclosed herein.

Claim 1:
A radio transceiver device (<NUM>), the radio transceiver device (<NUM>) comprising:
an antenna (<NUM>);
a signal processing module (<NUM>);
a receiver chain (<NUM>) configured to receive a first signal, the receiver chain (<NUM>) extending from the antenna (<NUM>) to the signal processing module (<NUM>) and at least comprising an analog-to-digital converter, ADC (<NUM>), and thereby configured to receive a first signal from the antenna (<NUM>) and provide the first signal to the signal processing module (<NUM>) after application of analog-to-digital conversion in the ADC (<NUM>) to the first signal; and
a transmitter chain (<NUM>), the transmitter chain (<NUM>) extending from the signal processing module (<NUM>) to the antenna (<NUM>) and at least comprising a digital-to-analog converter, DAC (<NUM>), and thereby configured to receive a second signal from the signal processing module (<NUM>) and provide the second signal to the antenna (<NUM>) after application of digital-to-analog conversion in the DAC (<NUM>);
wherein the DAC (<NUM>) is configured to generate a dither signal and is connected to the receiver chain (<NUM>) for application of the dither signal to the first signal before application of analog-to-digital conversion in the ADC (<NUM>) to the first signal, and wherein the dither signal is defined by the second signal after application of digital-to-analog conversion in the DAC (<NUM>) to the second signal.