WO2015043673A1

WO2015043673A1 - Mechanism for improving receiver sensitivity

Info

Publication number: WO2015043673A1
Application number: PCT/EP2013/070344
Authority: WO
Inventors: Marko FLEISCHER; Jan Hellmann; Bjoern Jelonnek; Michael KRONWALD
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2013-09-30
Filing date: 2013-09-30
Publication date: 2015-04-02

Abstract

A method comprising capturing data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received, predicting, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received, the distortion being caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled, deriving, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, applying the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and correcting the signal being received by using the generated reference signal.

Description

MECHANISM FOR IMPROVING RECEIVER SENSITIVITY

DESCRIPTION

BACKGROUND Field

The present invention relates to apparatuses, methods, systems, computer programs, computer program products and computer-readable media usable for improving a sensitivity of a receiver in a communication system.

Background Art

The following description of background art may include insights, discoveries, understandings or disclosures, or associations, together with disclosures not known to the relevant art prior, to at least some examples of embodiments of the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.

The following meanings for the abbreviations used in this specification apply:

AAS: active antenna systems

ADC: analogue to digital converter

AIM : active intermodulation product

ASIC: application specific integrated circuit

BS: base station

BW: bandwidth CPU : central processing unit

DAC: digital to analogue converter

DFE: digital front end

DSP: digital signal processor

EVM : error vector magnitude

eNB: evolved node B

FDD: frequency division duplex

FIR: finite impulse response

FPGA: field programmable gate array

HW: hardware

ID: identification, identifier

IMx: intermodulation distortion

LNA: low noise amplifier

LTE: long term evolution

LTE-A: long term evolution advanced

PA: power amplifier

RF: radio frequency

RX: reception, receiver

SW: software

TX: transmission, transmitter

TXRX: transmitter to receiver

UE: user equipment

WCDMA: wireless code division multiple access In the last years, an increasing extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), DSL, or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation (3G) and fourth generation (4G) communication networks like the Universal Mobile Telecommunications System (UMTS), enhanced communication networks based e.g. on LTE or LTE-A, cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolution (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN), Bluetooth or Worldwide Interoperability for Microwave Access (WiMAX), took place all over the world. Various organizations, such as the 3rd Generation Partnership Project (3GPP), Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN), the International

Telecommunication Union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute of Electrical and Electronics Engineers), the WiMAX Forum and the like are working on standards for telecommunication network and access environments.

Generally, for properly establishing and handling a communication connection between communication entities, such as terminal devices, user devices or user equipment (UE), and other communication entities, such as network elements, user devices, a database, a server, host etc., one or more intermediate network entities, such as communication network control elements, base stations, control nodes, support nodes, service nodes etc., are involved which may belong to different communication network. The communication entities, network entities etc. comprise one or more communication functions or elements operating for transmitting and receiving signaling exchanged between communication/network entities involved in a communication, such as transmitter- receiver systems, transceiver systems combining both transmitter and receiver functions or elements, transponder systems etc. That is, transmission and reception of signaling e.g. via an air interface is conducted in parallel in communication/network entities on plural carriers, for example.

However, the parallel operation of receiver and transmitter systems may cause interferences which may limit in particular the sensitivity on receiver side. For example, when considering e.g. a high power broadband multistandard multicarrier FDD system, it is possible that the system performance and sensitivity is affected by transmitter induced intermodulation products landing at RX channels. Due to the inband nature of such distortions, it is not possible to use conventional filter technique to improve receiver sensitivity.

The likelihood of having a receiving channel being polluted by an own transmitter is increasing with new broadband multicarrier BTS architectures simultaneously supporting a combination of plural communication systems, such as a combination of LTE/WCDM A/GSM.

SUMMARY

According to example versions of the disclosure, there is provided, for example, a method comprising capturing data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received, predicting, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received, the distortion being caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled, deriving, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, applying the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and correcting the signal being received by using the generated reference signal. In addition, according to example versions of the disclosure, there is provided, for example, an apparatus comprising at least one processor, and at least one memory for storing instructions to be executed by the processor, wherein the at least one memory and the instructions are configured to, with the at least one processor, cause the apparatus at least: to capture data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received, to predict, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on a signal being received, the distortion being caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled, to derive, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, to apply the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and to correct the signal being received by using the generated reference signal.

Moreover, according to example versions of the disclosure, there is provided, for example, an apparatus comprising a link to at least one transmission path for conveying a signal to be transmitted, a link to at least one reception path for conveying a signal being received, a data capturing unit configured to capture data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received, a reference signal generation device configured to predict, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received, the distortion being caused by cross-coupling in a connection element to which the at least one transmission path and the at least one reception path are coupled, to derive, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, and to apply the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and a correction unit configured to correct the signal being received by using the generated reference signal.

According to some further refinements, example versions of the disclosure considers at least one of the following :

- the correction of the signal being received may include a subtraction processing, in the reception path coming from the connection element, of the reference signal from the signal being received which is affected by the distortion effect caused by the signal to be transmitted;

- the captured data which is used for predicting the distortion effect may be captured by a feedback receiver connected to the transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted, and the reference signal may be generated on the basis of the derived model in time and magnitude via a finite impulse response filter on the basis of an output of the feedback receiver;

- in case plural transmission paths are coupled to the connection element, a respective feedback receiver may be provided for each transmission path for capturing data based on a respective signal to be transmitted;

- the captured data which is used for predicting the distortion effect may be captured by an identification radio frequency receiver connected to the transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted, and the reference signal may be generated on the basis of a digital signal conveyed on the transmission path by using a model based on an estimation of a power amplifier model and an estimation of an attenuation characteristic of the connection element derived from the identification radio frequency receiver;

- the identification radio frequency receiver may be configured to receive and process the signal to be transmitted after a digital-to-analog conversion and a power amplification thereof, wherein the estimation of the power amplifier model and the estimation of the attenuation characteristic of the connection element may be related to a frequency band used at the reception path;

- in case plural transmission paths are coupled to the connection element, one identification radio frequency receiver may be provided for all transmission paths in a time shared manner;

- the identification radio frequency receiver may further provide information how filter coefficients for a finite impulse response filter are to be set for generating the reference signal;

- the captured data which is used for predicting the distortion effect may be based on a digital signal conveyed on the transmission path, and the reference signal may be generated on the basis of the signal being received and the digital signal conveyed on the transmission path by using a non-linear model related to a power amplifier model and based on a pre- known attenuation characteristic of the connection element;

- the modeling of the reference signal may be approved on the basis of a thermal behavior of an attenuation characteristic from a transmission path side to a reception path side of the connection element;

- the connection element may be a device providing a connection between at least one antenna on one side and at least one transmission path and at least one reception path on the other side in a transceiver entity usable in a communication network.

In addition, according to embodiments, there is provided, for example, a computer program product for a computer, comprising software code portions for performing the steps of the above defined methods, when said product is run on the computer. The computer program product may comprise a computer-readable medium on which said software code portions are stored. Furthermore, the computer program product may be directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example versions of the disclosure are described below, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 shows a diagram illustrating a part of a transceiver element used in a communication scenario where some example versions of the disclosure can be applied;

Fig. 2 shows a diagram illustrating details of a configuration of a transceiver system according to some example versions of the disclosure; Fig. 3 shows a diagram illustrating details of a configuration of a transceiver system according to some further example versions of the disclosure;

Fig. 4 shows a diagram illustrating details of a configuration of a transceiver system according to some further example versions of the disclosure;

Fig. 5 shows a diagram illustrating an example of a characteristic of a connection element according to some example versions of the disclosure; Fig. 6 shows a flow chart of a processing conducted in a transceiver element according to some example versions of the disclosure; and

Fig. 7 shows a diagram of a transceiver element including processing portions conducting functions according to some example versions of the disclosure.

DESCRIPTION OF EMBODIMENTS

In the following, some example versions of the disclosure are described with reference to the drawings. In the following, different example versions of the disclosure will be described using a communication element, such as a transceiver element as an example which is used, for example, in a communication conducted e.g. in a wireless communication network, such as an LTE based network. However, it is to be noted that example versions of the disclosure are not limited to an application using such types of communication elements or communication system, but they are also applicable in other types of communication elements and systems, and the like. The following example versions of the disclosure are only illustrative examples. Although the specification may refer to "an", "one", or "some" example version of the disclosure in several locations, this does not necessarily mean that each such reference is to the example version(s), or that the feature only applies to a single example version. Single features of different example versions may also be combined to provide other example versions. Furthermore, words "comprising" and "including" should be understood as not limiting the described example versions of the disclosure to consist of only those features that have been mentioned and such example versions may also contain also features, structures, units, modules etc. that have not been specifically mentioned. A basic system architecture of a communication system where examples of embodiments are applicable may comprise a commonly known architecture of one or more communication networks comprising a wired or wireless access subsystem. Such an architecture may consist of plural communication elements comprising e.g. one or more communication network control elements, access network elements, radio access network elements, access service network gateways or base transceiver stations, such as a base station, an access point or an eNB, which control a respective coverage area or cell and with which one or more communication elements like terminal devices such as a UE or another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like, are capable to communicate via one or more channels for transmitting several types of data. Furthermore, core network elements such as gateway network elements, policy and charging control network elements, mobility management entities, operation and maintenance elements, and the like may be comprised. It is assumed that at least one of the communication elements involved in a communication comprises a component or function allowing a transmission and reception of data where a distortion caused by a signaling on a transmission path affects the sensitivity of a receiver path or chain. The general functions and interconnections of described elements, which also depend on the actual network configuration, are known to those skilled in the art, so that a detailed description thereof is omitted herein. However, it is to be noted that several additional elements, functions or devices and signaling links may be employed for transmitting and receiving a signaling related to a communication to or from a communication element comprising a transmitting and receiving element or function besides those described in detail herein below. A communication network in which example versions of the disclosure are applicable for increasing a sensitivity of a receiver in a communication element may communicate via wireless and/or wired communication paths of a public switched telephone network, a local area network, the Internet, etc.. It should be appreciated that communication elements using a transmitting and receiving function or the like, such as terminal devices,

UEs, access points, eNBs etc., or their functionalities may be implemented by using any node, host, server, access node etc. or entity suitable for such a usage. Furthermore, the described communication elements, such as terminal devices, user devices like UEs, communication network control elements of a cell, like an eNB, access network elements and the like, as well as corresponding functions as described herein may be implemented by software, e.g. by a computer program product for a computer, and/or by hardware. In any case, for executing their respective functions, correspondingly used devices, nodes or network elements may comprise several means, modules, units, components, etc. (not shown) which are required for control, processing and/or communication/signaling functionality. Such means, modules, units and components may comprise, for example, one or more processors or processor units including one or more processing portions for executing instructions and/or programs and/or for processing data, storage or memory units or means for storing instructions, programs and/or data, for serving as a work area of the processor or processing portion and the like (e.g. ROM, RAM, EEPROM, and the like), input or interface means for inputting data and instructions by software (e.g. floppy disc, CD-ROM, EEPROM, and the like), a user interface for providing monitor and manipulation possibilities to a user (e.g. a screen, a keyboard and the like), other interface or means for establishing links and/or connections under the control of the processor unit or portion (e.g. wired and wireless interface means, radio interface means comprising e.g. an antenna unit or the like, means for forming a radio communication part etc.) and the like, wherein respective means forming an interface, such as a radio communication part, can be also located on a remote site (e.g. a radio head or a radio station etc.). It is to be noted that in the present specification processing portions should not be only considered to represent physical portions of one or more processors, but may also be considered as a logical division of the referred processing tasks performed by one or more processors.

As described above, system performance of a communication element with regard to receiver sensitivity is affected by distortions caused by a TX path, e.g. by transmitter induced intermodulation products landing at RX frequency band. A source of such distortions is caused by active components in the TX path, such as e.g. a power amplifier, and hence they are hence more or less unavoidable. These intermodulations are also addressed to as active intermodulation products (AIM).

According to a comparative example, AIM can be compensated in a received signal by means of applying feedback solutions, i.e. by using some kind of echo cancellation. The effectiveness of cancellation, i.e. the compensation result depend on a similarity between a signal used for compensation, also referred to as feedback or reference signal, and a leakage signal, i.e. the component of the signal conveyed on the RX path which is caused e.g. by the cross- coupling in a connection element.

In narrow band/ single standard FDD systems, in some cases, AIM can be dealt with by employing an avoidance strategy, i.e. to place a carrier (i.e. the part of the frequency spectrum used thereby) in an appropriate manner so as to prevent intermodulation receive band hits. However, such an approach is not feasible in broadband scenarios.

Another approach would be digital pre-distortion which is used to limit spurious emissions. However, in scenarios using e.g. ultra broadband radio designs, this approach is also not feasible also since cleaning of receive bands from unwanted noise is extremely difficult and costly.

Suppression of TXRX leakage is also the aim of duplexers and the like as connection elements. However, high attenuation requirements prevent the use of e.g. ceramic materials and lead to bulky designs.

Fig. 1 shows a diagram illustrating a part of a transceiver element used in a communication scenario where some example versions of the disclosure can be applied. Specifically, Fig. 1 shows a diagram illustrating a general configuration of a part of a communication element consisting of a TX path and an RX path of e.g. a transceiver element or function which are coupled to a connection element 10, such as a duplexer. The connection element allows a bidirectional communication via an antenna 20 via which a signal conveyed by the TX path can be sent and via which a signaling can be received which is conveyed by the RX path into the communication element.

It is to be noted that the configuration shown in Fig. 1 shows only those devices, parts, connections and links which are useful for understanding principles underlying the examples of embodiments. As also known by those skilled in the art there may be several other elements included in a communication element or transceiver element which are omitted here for the sake of simplicity. Furthermore, even though in Fig. 1 and the following figures a configuration is depicted consisting of one TX path and one RX path coupled to a connection element 10 (such as a duplexer), example versions of the disclosure are not limited thereto. Various combinations of one or more TX paths and one or more RX paths (multi-carrier architectures using more than one TX path and/or one or more RX paths) can also be used in a communication element where example versions of the disclosure are implemented. Furthermore, even though only one antenna 20 is shown in the figures illustrating example versions of the disclosure, a corresponding communication element may also comprise plural antennas or antenna arrays.

Indicated by a dashed arrow in Fig. 1, a distortion caused by the TX path on the RX path is indicated, such as a signal leakage. As indicated in the additional diagram of Fig. 1, as the TX power is usually significantly higher than the RX power, when the frequency range of the TX signaling is in a certain range, it is possible that the RX power at frequency range with central frequency f|¾< (indicated by the white area) is affected by TX caused distortion (TX leakage) (indicated by black area). For example, in case of using a multi-carrier configuration, as a distortion, AIM is usually produced.

According to some example versions of the disclosure, an approach for improving the sensitivity of a receiver is provided which is based on compensating distortions caused by TX signaling, such as TX induced intermodulation, by using a reference signal which is generated or created according to example versions of the disclosure. Specifically, according to some example versions of the disclosure, apparatuses, methods and design concepts are provided allowing to create such reference signals in order to attenuate/cancel distortions such as e.g. AIMs landing at a receive band and having a de-sensitisation effect on the receiver performance. That is, according to some example versions of the disclosure, intermodulation prediction is conducted for modeling a reference signal.

Some example versions of the disclosure will be described in connection with FDD based systems. However, it is to be noted that corresponding measures are also applicable in other system types.

For example, when considering a single antenna FDD system as indicated in Fig. 1, noise leakage caused by the TX path may affect the receiver sensitivity. These leakage or active intermodulation effects is predicted on the basis of the TX signal. On the basis of the prediction, a reference signal is modeled in an appropriate manner. Then the distortion is corrected in a received signal, e.g. by subtracting the reference signal from the received signal including components caused by the TX caused distortion so as to improve the receiver sensitivity.

Fig. 2 shows a diagram illustrating details of a configuration of a transceiver system as an example of a communication element according to some example versions of the disclosure.

A TX path conveying a signal to be transmitted X is coupled to a connection element 10, i.e. a duplexer 10, so that the signal to be transmitted can be transmitted via antenna 20. In the TX path, a DAC 30 for converting the signal to be transmitted into an analogue signal and a PA 40 for amplifying the converted signal are connected.

On the other side, an RX path is coupled to the duplexer 10 for conveying a signal being received via the antenna 20. The received signal is amplified in the RX path by means of e.g. LNA 80 and converted into a digital signal by an ADC 90. The signal output by the ADC 90 is also referred to as RX main signal Y which is illustrated in Fig. 2 in a box. As described above, the signal being received may be distorted by TX induced intermodulation (e.g. caused by AIM) resulting in the RX main signal Y. The distortion depends, for example, on a cross-coupling characteristic of the connection element 10 (indicated as a dashed box in the duplexer 10). Fig. 5 shows a diagram illustrating an example of a corresponding attenuation characteristic of the connection element 10 according to some example versions of the disclosure. It is to be noted that Fig. 5 indicates only one possible example, and other characteristics can be present in a connection device.

Hence, according to example versions of the disclosure, a reference signal generation configuration used for providing a correction of the RX main signal Y is connected in the transceiver system.

In detail, as indicated in Fig. 2, after the PA 40, a coupling or link via a delay element 50 is made towards a feedback RF receiver 60. Connected to the feedback RF receiver 60 is a FIR filter 70. The FIR filter 70 is connected to the RX path at a location where the RX main signal Y is present by means of a subtraction element (inverse addition) 100, for example.

For the generation of the reference signal, the reference signal generation configuration according to the example version of the disclosure as indicated in Fig. 2 derives a model for the reference signal generation, wherein the following components are to be captured, i.e. the RX main signal Y and a signal Zl output by the feedback RF receiver 60.

The feedback RF receiver 60 scans, via the coupling to the TX path, signal components of a certain frequency region. The frequency region may be set, for example, to any region between a broad region comprising basically the whole processable spectrum or a rather narrow region comprising e.g. on a frequency region corresponding to frequency band used at the RX (e.g. 20 MHz). The setting of the frequency region being scanned by the feedback RF receiver is selected such that the distortion component causing the IMx, for example, is detected. The scanned signal components being received in the set frequency band are then processed and converted into a digital signal composing signal Zl.

The digital signal Zl is supplied to the FIR filter 70. Filter coefficients of the FIR filter 70 are set so as to model the duplexer characteristic. That is, a system behavior based on a prediction of a distortion caused in the connection element (duplexer) is derived and a model is applied for generating a reference signal. Hence, reference signal Xe is output by the

FIR filter which is related to the distortions caused by the TX signal, e.g. AIM.

That is, the feedback RF receiver 60, which is e.g. a reference hardware RF receiver, functions as leakage reference signal source. A modeling for generating a reference signal Xe in time and magnitude is based on the signal Zl provided by the receiver 60, which is derived from the signal on the TX path in the set frequency range , and the setting of the the FIR filter 70 which is used to model the duplexer, i.e. to match the duplexer characteristic.

The reference signal Xe which is illustrated in Fig. 2 in a corresponding box corresponds to the distortion component assumed to be added to the signal being received from the antenna 20 in the duplexer 10. Hence, the reference signal Xe is subtracted from the RX main signal Y (i.e. the receiver leakage signal) for removing the distortion. As a result, a corrected RX signal (indicated by a separate box in Fig. 2) output from element 100 is further conveyed on the RX path which corresponds to the originally received signal (i.e. without the TX induced distortion).

By means of the procedure discussed in connection with Fig. 2, it is possible to provide a robust correction method with good distortion suppression results. Furthermore, the correction procedure according to Fig. 2 requires low adaptation rates.

It is to be noted that according to some example versions of the disclosure, in case of a communication element comprising plural TX paths, each TX path is provided with a dedicated feedback RX receiver 60. Furthermore, the reference signal generation/modeling is operating permanently, i.e. the presently used modeling is adapted to the current PA characteristic etc., so that a very accurate compensation is possible.

As indicated above, in the configuration according to Fig. 2, in case plural TX paths are used, each TX path has to be provided with an own feedback RF receiver. In order to reduce the number of components in such a case, further example versions of the disclosure are designed to bypass this requirement of a dedicated feedback RF receiver per TX, as discussed in the following.

Fig. 3 shows a diagram illustrating details of a configuration of a transceiver system as an example of a communication element according to some further example versions of the disclosure. The basic structure of the communication element with regard to the TX path, the RX path and the connection element (duplexer) 10 is comparable to that described in connection with the example according to Fig. 2, and elements being the same as in the configuration according to Fig. 2 are denoted by the same reference signs, so that a repetition of a description thereof is omitted.

According to present example versions of the disclosure, a reference signal generation configuration used for providing a correction of the RX main signal Y is connected in the transceiver system as described in the following.

In detail, as indicated in Fig. 3, a coupling or link to the TX path in front of the DAC 30 is made via a delay element 55, so that digital signal X on the TX path is retrieved. The digital signal X is supplied to a modeling unit 110 providing a PA model in a preset frequency region, e.g. in the RX band. Furthermore, an identification RF receiver 160 is connected to the TX path after the PA 40. The identification receiver 160 is configured to provide specific information via a signal Z2 to the modeling unit 110.

A FIR filter 70 is connected to the modeling unit 110. The FIR filter 70 is connected to the RX path at a location where the RX main signal Y is present by means of a subtraction element 100, for example.

The function of the modeling unit 110, the identification receiver 160 and the FIR filter 70 for generating the reference signal and compensating for the TX induced distortion in the RX main signal is described in the following.

For the generation of the reference signal, the reference signal generation configuration according to the example version of the disclosure as indicated in Fig. 3 derives a model for the reference signal generation, wherein the following components are to be captured, i.e. the digital signal X on the TX path, the RX main signal Y and signal Z2 output by the identification receiver 160.

The identification receiver 160 scans, via the coupling to the TX path, signal components of a certain frequency region. The frequency region may be set, for example, to any region between a broad region comprising basically the whole processable spectrum or a rather narrow region comprising e.g. on a frequency region corresponding to frequency band used at the RX (e.g. 20 MHz). The setting of the frequency region being scanned by the feedback RF receiver is selected such that the distortion component causing the IMx, for example, is detected.

On the basis of the scanned signal components being received in the set frequency band, the identification receiver is configured to identify how a modeling for generating the reference signal is to be set. That is, for example, the identification receiver is able to estimate how the PA influences the signal (PA model). Furthermore, FIR filter coefficient setting is derivable for modeling the connection element characteristic. In addition, for example, a setting of the value for the delay element 55 can be identified.

The signal Z2 is supplied to the modeling unit 110 for setting a PA model (duplexer modeling is made e.g. via FIR filter coefficient setting). For generating the reference signal Xe, the models are applied on real time TX data.

That is, a system behavior based on a prediction of a distortion caused in the connection element (duplexer) is derived and a model is applied for generating a reference signal. Hence, reference signal Xe is output by the

FIR filter 70 which is related to the distortions caused by the TX signal, e.g. AIM.

That is, in the illustrated example version of the disclosure according to Fig. 3, in contrast to the configuration according Fig. 2, the reference signal is directly derived from the digital signal X on the TX path, wherein the reference signal is then again used for correcting the received signal (RX main signal Y) e.g. by subtracting it from the receiver leakage signal (the RX main signal Y) at the subtraction element 100 for removing the distortion.

As indicated above, the identification how the TX signal is to be transformed into a useful cancellation signal (reference signal), i.e. how the modeling for generating the reference is to be made, is a two step approach. The identification receiver 160 provides the information Z2 allowing an estimation of a power amplifier model and likewise an estimation of the duplexer attenuation characteristic (see Fig. 5). These estimations are then used in the modeling unit 110 and the FIR filter 70 for modeling the reference signal.

According to some example versions of the disclosure, in a configuration based on that described in connection with Fig. 3, when a communication element with plural TX paths (multi transmitter design) is used, the identification receiver 160 is shared in time across the different TX paths. In other words, one identification receiver 160 is e.g. switched between the plural TX paths for identifying the corresponding setting and parameters required for the modeling of the reference signal per TX path. This allows e.g. a small sized and low cost configuration.

It is to be noted that some model parameters, such as that related to the PA 40, may change with the time. Therefore, a continued updating of the PA model by repeated detection via the identification receiver 160 on the TX paths is advantageous. Furthermore, according to some example versions of the disclosure, also other parameters such FIR filter coefficients are updated, which may vary e.g. due to temperature drifts of duplexer characteristic.

Fig. 4 shows a diagram illustrating details of a configuration of a transceiver system as an example of a communication element according to some further example versions of the disclosure. The basic structure of the communication element with regard to the TX path, the RX path and the connection element (duplexer) 10 is comparable to that described in connection with the example according to Fig. 2 or Fig. 3, and elements being the same as in the configuration according to Fig. 2 or Fig. 3 are denoted by the same reference signs, so that a repetition of a description thereof is omitted.

For the generation of the reference signal, the reference signal generation configuration according to the example version of the disclosure as indicated in Fig. 4 derives a model for the reference signal generation, wherein the following components are to be captured, i.e. the RX main signal Y and the digital signal X on the TX path.

In detail, as indicated in Fig. 4, a coupling or link to the TX path in front of the DAC 30 is made via a delay element 55, so that a digital signal X on the TX path is retrieved. The digital TX signal is supplied to a distortion prediction unit 120. The distortion prediction unit 120 is further configured to be supplied with information regarding a characteristic of the connection element 10. For example, corresponding information is based on measurements of duplexer characteristics or the like being conducted in advance, wherein the distortion prediction unit 120 is then storing the relevant information for further usage or provided with the information when required.

Furthermore, a FIR filter function 125 is provided which is connected to the distortion prediction unit 120 and the RX path at the subtraction element 100. It is to be noted that the FIR filter function 125 may be realized by a separate element or provided as a function in the distortion prediction unit 120.

The distortion prediction unit 120 is used for predicting the distortion caused by the TX signaling. For example, a PA model using a non-linear operation (e.g. X³) is conducted for simulating the distortion affecting the received signal. That is, the distortion prediction unit 120 (and the FIR filter 125) generates on the basis of models of the PA and the duplexer (connection element) a reference signal Xe by using real time TX data and outputs the reference signal Xe which is then used for correcting the received signal e.g. by subtracting it from the receiver leakage signal (the RX main signal Y) at the subtraction element 100 for removing the distortion

In the illustrated example version of the disclosure, the reference signal is derived from the digital signal X on the TX path. The digital signal X is then processed in a direct conversion procedure, so that the need to provide any (further) hardware receiver for the correction processing can be avoided. Instead, according to the present example versions of the disclosure, a model for generating the reference signal for cancellation is estimated out of the received leakage signal and corresponding transmit signal. The identification how the modeling is to be conducted comprises a non linear PA modeling (e.g. X³) and an a priori knowledge of characteristic information related to the connection element 10, such as the duplexer TXRX attenuation characteristic. This is used for generating the reference signal in the distortion prediction unit 120 (and the FIR filter function 125) on the basis of the thus derived model.

It is to be noted that according to some further example versions of the disclosure, the modeling of the reference signal can be approved when the thermal behavior of e.g. the duplexer TXRX attenuation characteristic is taken into consideration.

It is to be noted that the non-linear distortion prediction operation in the distortion prediction unit 120 may further consider, according to some example versions of the disclosure, whether a memory effect is present or not in the model. In other words, according to some example versions of the disclosure, it is considered whether calculations for generating a reference signal using the model requires or not time-consuming memory processing, i.e. whether an immediate provision of the reference signal (without memory) is possible or a delayed generation of the reference signal (with memory) is present. A corresponding consideration is then considered in a memory modeling in the distortion prediction unit 120 and/or the FIR filter 125.

The above described example versions of the disclosure illustrating mechanisms for improving a receiver sensitivity by applying distortion cancellation methods are described to be applied with a TX induced intermodulation distortion. However, it is to be noted that the principles described above can be applied also to a variety of other distortion types including concurrent non-linear active distortions since they provide a flexible design and problem-specific adaptation capability. Furthermore, it is to be noted that the mechanisms described in connection with Figs. 2 to 4 are applicable by HW and/or SW.

In addition, the concepts described in connection with the example versions of the disclosure according to Figs. 2 to 4 can be used in radio designs to cope with unwanted leakage signals affecting receiver sensitivity degradations, wherein in particular broadband radio applications benefit from effects of the example versions of the disclosure. Furthermore, one design advantage is the option to clean only affected receive channels rather than to use an approach where it is required to suppress the entire intermodulation products (as e.g. required in TX digital pre-distortion processing). Thus, the complexity can be kept low while still very good suppression results are achievable. In addition, it is to be noted that the antenna signal (i.e. the signal at the antenna 20) is completely unaffected by the compensation/correction procedures according to example versions of the disclosure. The example versions of the disclosure as described in connection with Figs. 2 to 4 are different with regard to a level of microprocessor support and real time constraints. For example, when considering the example version of the disclosure as described in Fig. 2, when the reference signal is obtained by using a feedback RF receiver, requirements regarding digital hardware depend mainly to the FIR filter part. According to some example versions of the disclosure, a comparable simple FIR filter configuration is sufficient which can be realized e.g. by means of an ASIC/FPGA approach or a DSP approach. Furthermore, a very high processing stability and gain are achievable while an adaptation rate can be kept slow.

On the other hand, when considering the example version of the disclosure as described in Fig. 3, where an identification receiver is used, a compromise between hardware requirements and digital front end complexity can be achieved. The proposed example is in particular useful when the identification receiver resource is used in a shared manner by several TX chains.

Finally, when considering the example version of the disclosure as described in Fig. 4, where a direct conversion method of the digital TX signal is conducted, an additional RF receiver is not required. Furthermore, it is possible to handle the modeling of the PA and the duplexer characteristic in a HW element such as an ASIC, total HW costs can be reduced to a minimum.

Furthermore, example versions of the disclosure as described in connection with Figs. 2 to 4 are applicable in connection with e.g. AAS. Moreover, size of duplex devices can be reduced allowing e.g. the usage of new materials. In the following, effects of example versions of the disclosure according to the configurations described in connection with Figs. 2 to 4 for improving the receiver sensitivity are explained. In this connection, it is to be noted that example versions according to Figs. 2 to 4 vary with regard to requirements for hardware, costs and achievable improvement for the RX sensitivity. For example, the example version of the disclosure according to Fig. 2 provides a very high improvement level regarding sensitivity, but may be expensive due to the HW requirements. On the other hand, the example version of the disclosure according to Fig. 4 may lead to a smaller degree of improvement, bur requires no additional HW receiver. The example version of the disclosure according to Fig. 3 is a compromise.

Assuming that an unpolluted RX signal (i.e. RX main signal Y where no crosstalk is included), which is e.g. received in an LTE system, has an EVM of e.g. 24.1% (i.e. difference between a symbol being received and an ideal symbol). This value is used in the following as a reference for signal quality and hence achieved improvement of the receiver sensitivity.

When applying a configuration based on the example version of the disclosure according to Fig. 2, when the RX main signal is distorted (i.e. it consists theoretically of the unpolluted signal being received and a TX leakage component), an EVM improvement from e.g. 66.8 % (without correction) to 24.4 % is achievable. When applying a configuration based on the example version of the disclosure according to Fig. 3, when the RX main signal is distorted (i.e. it consists theoretically of the unpolluted signal being received and a TX leakage component), an EVM improvement from e.g. 66.8 % (without correction) to 27.3 % is achievable.

When applying a configuration based on the example version of the disclosure according to Fig. 4, when the RX main signal is distorted (i.e. it consists theoretically of the unpolluted signal being received and a TX leakage component), an EVM improvement from e.g. 66.8 % (without correction) to 33,1 % is achievable. Thus, an improvement of the receiver sensitivity is achievable by each of the described example versions of the disclosure.

It is to be noted that the above mentioned values for EVM are only examples for illustrating a possible effect also in relation between the respective examples. Actually achieved values may of course be different.

Fig. 6 shows a flow chart of a processing conducted in a transceiver element according to some example versions of the disclosure. In detail, a processing flow is shown corresponding to a procedure executed in a communication element in which example versions of the disclosure for improving the receiver sensitivity are executing, for example in accordance with a configuration as depicted in any of Figs. 2 to 4, wherein a HW and/or SW based configuration may be used.

In S100, data from signaling on a TX path conveying a signal to be transmitted and a RX path conveying a signal being received are captured.

The data on the RX path are distorted, for example, by AIM. For example, the data are captured in a time synchronized manner.

In S110, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received is predicted. The distortion is e.g. caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled. Then, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received is derived.

In S120, the model is applied on a detected signaling on the TX path for generating a reference signal matching the distortion effect. In S130, the signal being received is corrected by using the generated reference signal. For example, the correction of the signal being received includes a subtraction processing, in the RX path coming from the connection element, of the reference signal from the signal being received which is affected by the distortion effect caused by the signal to be transmitted.

For example, the captured data which is used for predicting the distortion effect in SI 10 is captured by a feedback RF receiver connected to the TX path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted. The reference signal is generated or obtained on the basis of the derived model in time and magnitude via a FIR filter on the basis of an output of the feedback RF receiver. In case plural TX paths are coupled to the connection element, a respective feedback RF receiver is provided for each TX path for capturing data based on a respective signal to be transmitted.

Alternatively, the captured data which is used for predicting the distortion effect is captured by an identification RF receiver connected to the TX path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted. The reference signal is generated on the basis of a digital signal conveyed on the TX path by using a model based on an estimation of a PA model and an estimation of an attenuation characteristic of the connection element derived from the identification RF receiver. The identification radio frequency receiver is configured to receive and process the signal to be transmitted after a digital-to-analog conversion and a power amplification thereof, wherein the estimation of the PA model and the estimation of the attenuation characteristic of the connection element are related to a frequency band used at the RX path. Furthermore, in case plural TX paths are coupled to the connection element, one identification RF receiver is provided for all TX paths in a time shared manner. The identification radio frequency receiver further provides information how filter coefficients for a FIR filter are to be set for generating the reference signal.

Further alternatively, the captured data which is used for predicting the distortion effect is based on a digital signal conveyed on the TX path. The reference signal is generated on the basis of the signal being received and the digital signal conveyed on the TX path by using a non-linear model related to a PA model and based on a pre-known attenuation characteristic of the connection element.

Fig. 7 shows a diagram of a configuration of a communication element part, such as a part of a transceiver element, including processing portions conducting functions according to some example versions of the disclosure. Specifically, Fig. 7 shows a diagram illustrating a configuration of an apparatus being connectable or introducible to a communication element like a transceiver element, which is configured to implement the procedure for improving the receiver sensitivity as described in connection with some example versions of the disclosure. It is to be noted that the apparatus shown in Fig. 7 may comprise further elements or functions besides those described herein below which are related to other transmitting or receiving functionalities, for example. Furthermore, even though reference is made to a transceiver, the communication element may be also another device having a similar function, including also a chipset, a chip, a module etc., which can also be part of a communication element or attached as a separate element to a communication element, or the like. It should be understood that each block and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry.

The part of the communication element 200 shown in Fig. 7 may comprise a processing function, control unit or processor 210, such as a CPU or the like, which is suitable for executing instructions given by programs or the like related to a communication procedure. The processor 210 may comprise one or more processing portions dedicated to specific processing as described below, or the processing may be run in a single processor. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors or processing portions, such as in one physical processor like a CPU or in several physical entities, for example. Reference signs 220 and 230 denote input/output (I/O) units (interfaces) connected to the processor 210. The I/O units 220 may be used for forming a coupling or link to one or more communication lines forming a respective TX chain, wherein one or both of digital data and analog data (after DAC) can be scanned. The I/O units 230 may be used for forming a coupling or link to one or more communication lines forming a respective RX path. Reference sign 240 denotes a memory usable, for example, for storing data and programs to be executed by the processor 210 and/or as a working storage of the processor 210.

The processor 210 is configured to execute processing related to the above described communication procedure. In particular, the processor 210 comprises a sub-portion 211 as a processing portion which is usable for capturing data. The portion 211 may be configured to perform processing according to S100 of Fig. 6. Moreover, the processor 210 comprises a sub- portion 212 as a processing portion which is usable for deriving a model for generating a reference signal using a prediction of a distortion effect. The portion 212 may be configured to perform processing according to SllO of Fig. 6. Furthermore, the processor 210 comprises a sub-portion 213 usable as a portion for generating a reference signal using the model. The portion

213 may be configured to perform processing according to S120 of Fig. 6. Furthermore, the processor 210 comprises a sub-portion 214 usable as a portion for conducting an RX signal correction. The portion 214 may be configured to perform a processing according to S130 of Fig. 6.

According to a further example versions of the disclosure, there is provided an apparatus comprising processing means for capturing data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received, processing means for predicting, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on a signal being received, the distortion being caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled, processing means for deriving, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, processing means for applying the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and processing means for correcting the signal being received by using the generated reference signal.

According to a further example versions of the disclosure, there is provided an apparatus comprising means providing a link to at least one transmission path for conveying a signal to be transmitted, means providing a link to at least one reception path for conveying a signal being received, data capturing means for capturing data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received, reference signal generation means for predicting, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received, the distortion being caused by cross-coupling in a connection element to which the at least one transmission path and the at least one reception path are coupled, for deriving, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, and for applying the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and correction means for correcting the signal being received by using the generated reference signal.

It should be appreciated that

- an access technology via which signaling is transferred to and from a network element may be any suitable present or future technology, such as WLAN (Wireless Local Access Network), WiMAX (Worldwide Interoperability for Microwave Access), LTE, LTE-A, Bluetooth, Infrared, and the like may be used; Additionally, embodiments may also apply wired technologies, e.g. IP based access technologies like cable networks or fixed lines. - a user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface may be allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self- backhauling relay) towards the base station or eNB. The user device typically refers to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. It should be appreciated that a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing.

- embodiments suitable to be implemented as software code or portions of it and being run using a processor are software code independent and can be specified using any known or future developed programming language, such as a high-level programming language, such as objective-C, C, C++, C#, Java, etc., or a low-level programming language, such as a machine language, or an assembler, - implementation of embodiments, is hardware independent and may be implemented using any known or future developed hardware technology or any hybrids of these, such as a microprocessor or CPU (Central Processing Unit), MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), and/or TTL (Transistor-Transistor Logic). - embodiments may be implemented as individual devices, apparatuses, units or means or in a distributed fashion, for example, one or more processors may be used or shared in the processing, or one or more processing sections or processing portions may be used and shared in the processing, wherein one physical processor or more than one physical processor may be used for implementing one or more processing portions dedicated to specific processing as described,

- an apparatus may be implemented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset;

- embodiments may also be implemented as any combination of hardware and software, such as ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) or CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components.

- embodiments may also be implemented as computer program products, comprising a computer usable medium having a computer readable program code embodied therein, the computer readable program code adapted to execute a process as described in embodiments, wherein the computer usable medium may be a non-transitory medium.

Although the present invention has been described herein before with reference to particular embodiments thereof, the present invention is not limited thereto and various modifications can be made thereto.

Claims

1. A method comprising

capturing data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received,

predicting, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received, the distortion being caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled,

deriving, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received,

applying the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and

correcting the signal being received by using the generated reference signal.

2. The method according to claim 1, wherein

the correction of the signal being received includes a subtraction processing, in the reception path coming from the connection element, of the reference signal from the signal being received which is affected by the distortion effect caused by the signal to be transmitted.

3. The method according to claim 1 or 2, wherein

the captured data which is used for predicting the distortion effect is captured by a feedback receiver connected to the transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted, and

the reference signal is generated on the basis of the derived model in time and magnitude via a finite impulse response filter on the basis of an output of the feedback receiver.

4. The method according to claim 3, wherein

in case plural transmission paths are coupled to the connection element, a respective feedback receiver is provided for each transmission path for capturing data based on a respective signal to be transmitted.

5. The method according to claim 1 or 2, wherein

the captured data which is used for predicting the distortion effect is captured by an identification radio frequency receiver connected to the transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted , and

the reference signal is generated on the basis of a digital signal conveyed on the transmission path by using a model based on an estimation of a power amplifier model and an estimation of an attenuation characteristic of the connection element derived from the identification radio frequency receiver.

6. The method according to claim 5, wherein the identification radio frequency receiver is configured to receive and process the signal to be transmitted after a digital-to-analog conversion and a power amplification thereof, wherein the estimation of the power amplifier model and the estimation of the attenuation characteristic of the connection element are related to a frequency band used at the reception path.

7. The method according to claim 6, wherein

in case plural transmission paths are coupled to the connection element, one identification radio frequency receiver is provided for all transmission paths in a time shared manner.

8. The method according to any of claims 5 to 7, wherein the identification radio frequency receiver further provides information how filter coefficients for a finite impulse response filter are to be set for generating the reference signal.

9. The method according to claim 1 or 2, wherein the captured data which is used for predicting the distortion effect is based on a digital signal conveyed on the transmission path, and

the reference signal is generated on the basis of the signal being received and the digital signal conveyed on the transmission path by using a non-linear model related to a power amplifier model and based on a pre- known attenuation characteristic of the connection element.

10. The method according to claim 9, wherein

the modeling of the reference signal is approved on the basis of a thermal behavior of an attenuation characteristic from a transmission path side to a reception path side of the connection element.

11. The method according to any of claims 1 to 10, wherein the connection element is a device providing a connection between at least one antenna on one side and at least one transmission path and at least one reception path on the other side in a transceiver entity usable in a communication network.

12. An apparatus comprising

at least one processor,

and

at least one memory for storing instructions to be executed by the processor, wherein

the at least one memory and the instructions are configured to, with the at least one processor, cause the apparatus at least:

to capture data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received,

to predict, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on a signal being received, the distortion being caused by cross-coupling in a connection element to which the transmission path and the reception path are coupled,

to derive, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, to apply the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and

to correct the signal being received by using the generated reference signal.

13. The apparatus according to claim 12, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least

to conduct, when correcting the signal being received, a subtraction processing, in the reception path coming from the connection element, of the reference signal from the signal being received which is affected by the distortion effect caused by the signal to be transmitted.

14. The apparatus according to claim 12 or 13, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least

to capture the captured data which is used for predicting the distortion effect by a feedback receiver function connected to the transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted, and

to generate the reference signal on the basis of the derived model in time and magnitude via a finite impulse response filter on the basis of an output of the feedback receiver function.

15. The apparatus according to claim 14, wherein

in case plural transmission paths are coupled to the connection element, a respective feedback receiver function is provided for each transmission path for capturing data based on a respective signal to be transmitted.

16. The apparatus according to claim 12 or 13, wherein at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least to capture the captured data after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted, and to generate the reference signal on the basis of a digital signal conveyed in the transmission path by using a model based on an estimation of a power amplifier model and an estimation of an attenuation characteristic of the connection element.

17. The apparatus according to claim 16, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least

to provide an identification radio frequency receiver function connected to the transmission path after the digital-to-analog conversion and the power amplification of the signal to be transmitted, the identification radio frequency receiver function being for receiving and processing the signal to be transmitted after a digital-to-analog conversion and a power amplification thereof,

wherein the estimation of the power amplifier model and the estimation of the attenuation characteristic of the connection element are related to a frequency band used at the reception path.

18. The apparatus according to claim 17, wherein

in case plural transmission paths are coupled to the connection element, one identification radio frequency receiver function is provided for all transmission paths in a time shared manner.

19. The apparatus according to any of claims 16 to 18, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least

to cause the identification radio frequency receiver to provide information how filter coefficients for a finite impulse response filter are to be set for generating the reference signal.

20. The apparatus according to claim 12 or 13, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least

to capture the data from a digital signal conveyed on the transmission path and to use it for predicting the distortion effect, and

to generate the reference signal on the basis of the signal being received and the digital signal conveyed on the transmission path by using a non-linear model related to a power amplifier model and based on a pre- known attenuation characteristic of the connection element.

21. The apparatus according to claim 20, wherein the at least one memory and the instructions are further configured to, with the at least one processor, cause the apparatus at least

to approve the modeling of the reference signal on the basis of a thermal behavior of an attenuation characteristic from a transmission path side to a reception path side of the connection element.

22. The apparatus according to any of claims 12 to 21, wherein the connection element is a device providing a connection between at least one antenna on one side and at least one transmission path and at least one reception path on the other side in a transceiver entity usable in a communication network.

23. An apparatus comprising

a link to at least one transmission path for conveying a signal to be transmitted,

a link to at least one reception path for conveying a signal being received,

a data capturing unit configured to capture data from signaling on a transmission path conveying a signal to be transmitted and a reception path conveying a signal being received,

a reference signal generation device configured to predict, on the basis of the captured data, a distortion effect caused by the signal to be transmitted on the signal being received, the distortion being caused by cross-coupling in a connection element to which the at least one transmission path and the at least one reception path are coupled, to derive, on the basis of the prediction of the distortion effect, a model for generating a reference signal being related to a predetermined frequency spectrum part used by the signal being received, and to apply the model on a detected signaling on the transmission path for generating a reference signal matching the distortion effect, and

a correction unit configured to correct the signal being received by using the generated reference signal.

24. The apparatus according to claim 1, wherein

the correction unit includes a subtraction processing unit connected to the at least one reception path, the subtraction processing unit being configured to subtract the reference signal from the signal being received which is affected by the distortion effect caused by the signal to be transmitted.

25. The apparatus according to claim 23 or 24, wherein the reference signal generation device further comprises

at least one feedback receiver which is connected to the at least one transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted are conducted, the at least one feedback receiver being configured to capture the data which is used for predicting the distortion effect, and

a finite impulse response filter connected to the at least one feedback receiver, wherein the reference signal is generated on the basis of a model in time and magnitude via the finite impulse response filter on the basis of an output of the feedback receiver.

26. The apparatus according to claim 25, wherein

in case plural transmission paths are coupled to the connection element, the reference signal generation device comprises a respective feedback receiver for each transmission path for capturing data based on a respective signal to be transmitted.

27. The apparatus according to claim 23 or 24, wherein the reference signal generation device further comprises

an identification radio frequency receiver connected to the transmission path after a digital-to-analog conversion and a power amplification of the signal to be transmitted after a digital-to-analog conversion and a power amplification thereof for capturing the data which is used for predicting the distortion effect, and

a modeling unit configured to generate the reference signal on the basis of a digital signal conveyed on the transmission path by using a model based on an estimation of a power amplifier model and an estimation of an attenuation characteristic of the connection element derived from the identification radio frequency receiver.

28. The apparatus according to claim 27, wherein

the identification radio frequency receiver is configured to receive and process the signal to be transmitted after a digital-to-analog conversion and a power amplification thereof,

29. The apparatus according to claim 28, wherein

in case plural transmission paths are coupled to the connection element, the reference signal generation device comprises one identification radio frequency receiver for all transmission paths being used in a time shared manner.

30. The apparatus according to any of claims 27 to 29, wherein the reference signal generation device further comprises a finite impulse response filter, wherein the identification radio frequency receiver is further configured to provide information how filter coefficients for the finite impulse response filter are to be set for generating the reference signal.

31. The apparatus according to claim 23 or 24, wherein the reference signal generation device further comprises

a coupling to the transmission path for capturing the data on the basis of a digital signal conveyed on the transmission path, which is used for predicting the distortion effect, and

a distortion prediction unit configured to generate the reference signal based on the signal being received and the digital signal conveyed on the transmission path by using a non-linear model related to a power amplifier model and based on a pre-known attenuation characteristic of the connection element.

32. The apparatus according to claim 31, wherein the reference signal generation device is further configured to approve the modeling of the reference signal on the basis of a thermal behavior of an attenuation characteristic from a transmission path side to a reception path side of the connection element.

33. The apparatus according to any of claims 23 to 32, wherein the connection element is a device providing a connection between at least one antenna on one side and at least one transmission path and at least one reception path on the other side in a transceiver entity usable in a communication network.

34. A computer program product for a computer, comprising software code portions for performing the steps of any of claims 1 to 11 when said product is run on the computer.

35. The computer program product according to claim 34, wherein

the computer program product comprises a computer-readable medium on which said software code portions are stored, and/or

the computer program product is directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.