MOBILE DEVICE AND METHOD FOR PROCESSING SIGNALS

Abstract

Method for processing a received radio signal, wherein the method comprises: Receiving a receiving radio signal in a mobile device; Equalizing the received radio signal using a first equalizer to generate a first equalized received radio signal; Equalizing the received radio signal using a second equalizer to generate a second equalized received radio signal; Calculating a first subtraction signal based on a first resynthesized transmit signal; Subtracting the first subtraction signal from the second equalized received radio signal to generate a subtracted equalized received radio signal; Resynthesize a second transmit signal from the subtracted, equalized received radio signal; Calculating a second subtraction signal based on the resynthesized second transmit signal; and Subtracting the second subtraction signal from the first equalized received radio signal.

Description

Technical field

[0001] Several aspects of this disclosure generally concern mobile devices and methods for processing signals. background

[0002] High-data-rate wireless communication systems, such as high-speed packet access (HSPA) or Long-Term Evolution (LTE), can suffer from severe inter-symbol interference due to multipath propagation in physical transmission channels. A conventional mitigation of this type of problem in a code-division multiple access (CDMA) system, such as high-speed packet access for the downlink (HSDPA), is the use of a linear, (fractionally) spaced equalizer at the chip level in the baseband, designed according to an optimization criterion of choice, such as minimum mean square error (MMSE) or maximum signal-to-noise ratio (SNR) at the equalizer output.The equalization stage is followed by an anti-spreading stage, a symbol detection stage, and a demodulation stage before channel decoding can take place. The quality of the equalization and symbol detection stages determines the amount of redundancy required to decode the transmitted codeword without errors in the channel decoder, and therefore the achievable throughput in bits per second (bit / s) on the physical layer.

[0003] Document US 2007 / 0064845 A1 discloses a circuit that allows selective compensation to be applied to individual, discrete data signal components by performing four main functions. The circuit branch containing a first adaptive equalizer processes the electrical data signal such that, essentially, a defined signal component representing an intersymbol interference product of a segment of the data symbol sequence is removed. The circuit branch containing an equalization and processing circuit in the form of another adaptive equalizer, signal segmenter, and nonlinear signal processor approximately duplicates an intersymbol interference product of another segment of the data symbol sequence for removal, e.g., by subtraction, in a signal combiner from the compensated signal provided by the first equalizer.

[0004] Document US 5838739 A discloses a channel estimator circuit and an associated method for a digital receiver for estimating the channel impulse response of a transmission channel. The channel estimation quality is improved when intersymbol interference is introduced into a communication signal only by the circuitry of a transmitter and receiver. Even when intersymbol interference is introduced into a communication signal during its transmission, the channel estimation quality is improved by decomposing the components of the intersymbol interference into parts introduced during the transmission of the signal on a communication channel and parts introduced by the transmitter and receiver circuitry. Brief description

[0005] The invention is defined in the independent claims. Advantageous embodiments are defined in the dependent claims. A method for processing a received radio signal is provided. The method can comprise receiving a received radio signal in a mobile device, equalizing the received radio signal using a first equalizer to generate a first equalized received radio signal, equalizing the received radio signal using a second equalizer to generate a second equalized received radio signal, resynthesizing a transmit signal from the second equalized received radio signal, calculating a subtraction signal based on the resynthesized transmit signal, and subtracting the subtraction signal from the equalized received radio signal. Brief description of the drawings

[0006] In the drawings, the same reference numerals generally refer to the same parts throughout all different views. The drawings are not necessarily to scale; instead, the emphasis is on illustrating the principles of the invention. The following description details various embodiments of the invention with reference to the following drawings, wherein: Fig. 1 represents a block diagram of a mobile communication system; Fig. 2 represents a block diagram illustrating an internal configuration of a baseband modem; Fig. 3 represents a block diagram of a receiver that uses interference cancellation and has two receiving branches; Fig. 4 represents a block diagram of a channel model; Fig. 5 represents a block diagram of a receiver that uses interference cancellation and has three receiving branches; Fig. Figure 6 shows a block diagram of a receiver that uses interference cancellation and has multiple receiving branches. Description

[0007] The following detailed description refers to the accompanying drawings, which illustrate specific details and embodiments in which the invention can be implemented.

[0008] The word "exemplary" is used herein to mean "serving as an example or for illustration." Embodiments or designs described herein as "exemplary" are not necessarily to be interpreted as preferred or advantageous over other embodiments or designs.

[0009] The words "multiple" and "multiple" in the description and claims, if used at all, are used to expressly refer to a quantity greater than one. Accordingly, all expressions that explicitly include the aforementioned words (e.g., "several [objects]," "multiple [objects]") and refer to a quantity of objects are intended to expressly refer to more than one of the objects. The terms "group," "set," "collection," "series," "sequence," "grouping," "selection," etc., and the like, in the description and claims, if used at all, are used to refer to a quantity equal to or greater than one, e.g., one or more.Accordingly, the expressions “a group of [objects]”, “a set of [objects]”, “a collection of [objects]”, “a series of [objects]”, “a sequence of [objects]”, “a grouping of [objects]”, “a selection of [objects]”, [object]group, “[object]set”, “[object]collection”, “[object]series”, “[object]sequence”, “[object]grouping”, “[object]selection”, etc., which are used herein in reference to a quantity of objects, shall refer to a quantity of one or more of the objects. It is understood that references to quantities of objects, unless they are directly listed with an explicitly stated quantity in the plural (e.g., "two [objects]", "three of the [objects]", "ten or more [objects]", "at least four [objects]", etc.) or express the use of the words "multiple", "multiple" or similar terms, are intended to refer to one or more of the objects.

[0010] It is understood that all vector and / or matrix notations used herein are exemplary and are employed solely for illustrative purposes. Accordingly, it is understood that the approaches detailed in this disclosure are not limited to being implemented using only vectors and / or matrices, and that the associated processes and computations can be performed equivalently with respect to sets, sequences, groups, etc., of data, observations, and information.

[0011] Furthermore, it is understood that references to a "vector" can refer to a vector of any size or orientation, e.g., including a 1 × 1 vector (e.g., a scalar), a 1 × M vector (e.g., a row vector), and an M × 1 vector (e.g., a column vector). It is also understood that references to a "matrix" can refer to a matrix of any size or orientation, e.g., including a 1 × 1 matrix (e.g., a scalar), a 1 × M matrix (e.g., a row vector), and an M × 1 matrix (e.g., a column vector).

[0012] As used herein, a "circuit" means any type of logical (analog or digital) implementation entity, which may be a special circuit arrangement or processor execution software, firmware, hardware, or any combination thereof stored in memory. Furthermore, a "circuit" may be a hard-wired logic circuit or a programmable logic circuit, such as a programmable processor, for example, a microprocessor (for example, a processor of a Complex Instruction Set Computer (CISC) or a Reduced Instruction Set Computer (RISC)). A "circuit" may also be processor execution software, for example, any type of computer program, for example, a computer program that uses virtual machine code, such as Java.Any other type of implementation of the respective functions described in more detail below shall also be understood as a "circuit". It is understood that any two (or more) of the described circuits can be combined to form a single circuit with substantially equivalent functionality, and conversely, that each individual described circuit can be distributed across two (or more) separate circuits with substantially equivalent functionality. In particular, with regard to the use of "circuit arrangement" in the claims contained herein, the use of "circuit" is to be understood as referring collectively to two or more circuits.

[0013] A “processing circuit” (or equivalently, “processing circuit arrangement”), as used herein, is to be understood as referring to any circuit that performs an operation on a signal or signals, such as any circuit that performs processing on an electrical or optical signal. A processing circuit may therefore refer to any analog or digital circuit arrangement that modifies a characteristic or property of an electrical or optical signal, which may contain analog and / or digital data. A processing circuit may thus refer to an analog circuit (explicitly referred to as an analog “processing circuit (arrangement)”), a digital circuit (explicitly referred to as a “digital circuit (arrangement)”), a logic circuit, a processor, a microprocessor, a central processing unit (CPU), or a microprocessor.Central Processing Unit), a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), an integrated circuit, an Application Specific Integrated Circuit (ASIC), etc., or any combination thereof. Accordingly, a processing circuit can refer to a circuit that performs processing on an electrical or optical signal as hardware or as software, such as software that runs on hardware (e.g., a processor or microprocessor). As used herein, "digital processing circuit (arrangement)" can refer to a circuit implemented using digital logic that performs processing on a signal, e.g.,an electrical or optical signal, and which may include logic circuit(s), processor(s), scalar processor(s), vector processor(s), microprocessor(s), controller(s), microcontroller(s), central processing unit (CPU), graphics processing unit (GPU), digital signal processor(s) (DSP), field-programmable gate array(s) (FPGA), integrated circuit(s), application-specific integrated circuit(s) (ASIC), etc., or any combination thereof. It is further understood that a single processing circuit can be equivalently divided into two separate processing circuits, and conversely, that two separate processing circuits can be combined into a single equivalent processing circuit.

[0014] As used herein, "memory" is to be understood as an electrical component in which data or information can be stored for retrieval. References to "memory" contained herein are therefore to be understood as referring to volatile or non-volatile memory, including random access memory (RAM), read-only memory (ROM), flash memory, solid-state memory, magnetic tape, hard disk drive, optical drive, etc., or any combination thereof. It is also understood that the term "memory" includes registers, shift registers, processor registers, data buffers, etc. It is understood that a single component referred to as "memory" or "a memory" may consist of more than one distinct type of memory and may therefore refer to a collective component comprising one or more types of memory.It is easy to understand that each individual memory "component" can consist of multiple distributed and / or separate, essentially equivalent memory components, and vice versa. Furthermore, it is understood that although a "memory" may be depicted as separate from one or more other components, as in the drawings, the memory may be integrated into another component, such as a shared integrated chip.

[0015] The term "base station", used in reference to an access point of a mobile communications network, is to be understood as a macro base station, a micro base station, a femto base station, a NodeB, evolved NodeBs (eNB), a HeimateNodeB, a Remote Radio Head (RRH), a relay point, etc.

[0016] It is understood that the following description may detail exemplary scenarios involving a mobile device operating according to certain specifications of the Third Generation Partnership Project (3GPP), in particular the Universal Mobile Telecommunications System (UMTS) and any of its extensions, such as High-Speed ​​Packet Access (HSPA), High-Speed ​​Packet Access Downlink (HSDPA), and High-Speed ​​Packet Access Uplink (HSUPA). It is understood that such exemplary scenarios are illustrative in nature and, accordingly, apply similarly to other mobile communication technologies and standards, such as wireless local area network (WLAN), Wi-Fi, and Universal Mobile Telecommunications System (UMTS).Universal Mobile Telecommunications System (UMT), Global System for Mobile Communications (GSM), Bluetooth, Code Division Multiple Access (CDMA), Wideband CDMA (W-CDMA), Long Term Evolution (LTE) and Long Term Evolution-Advanced (LTE-A), and future mobile communication technologies and standards, such as 5G, etc. The examples provided herein are therefore to be understood as being applicable to various other mobile communication technologies, both existing and yet to be formulated, particularly in cases where such mobile communication technologies share similar features, as disclosed in the following examples.

[0017] The term "network", as used herein, for example, in reference to a communications network such as a mobile communications network, is intended to encompass both an access component of a network (e.g., a radio access network (RAN) component) and a core component of a network (e.g., a core network component).

[0018] Unless otherwise specified, the terms "transmit" and "send" include both direct and indirect transmission / sending. Similarly, the term "receive" includes both direct and indirect reception, unless otherwise specified. As used herein, the term "derived from" means obtained directly or indirectly from a specific source. Accordingly, data derived from a source includes data that is derived directly or indirectly (e.g., through one or more secondary agents) from the source.

[0019] In an HSPA architecture, as specified by the 3GPP (3rd Generation Partnership Project), base stations and mobile devices can use CDMA (Centralized Multi-Access) technology. CDMA is a spread-spectrum multiple access technique that evenly spreads the bandwidth of data for the same transmission power. A spreading code is generated by a generator that performs a Walsh-Hadamard transform and is designed to produce orthogonal codes for the same user or different users. In CDMA, a locally generated code executes at a higher rate than the data being transmitted. This results in multiple so-called chips. Each chip to be transmitted by a transmitter is exclusively ORed by the pseudorandom code (which can also be called a pseudorandom scrambling code). For example, 128 chips can be generated per bit. It's worth noting that the number of chips can depend on the spreading factor of the code used.

[0020] Each user, i.e., each mobile device, in a CDMA system uses a different code to spread its bitstream. Choosing the codes used for bitstream spreading is crucial for the performance of CDMA systems. Optimal performance is achieved when there is good separation between the chip sequence of a desired user and the chip sequences of other users, meaning the chip sequences are orthogonal to each other. As mentioned earlier, a single user can have more than one code. Good code separation can also be provided for this purpose. This can be achieved by designing the different codes to be orthogonal to each other.

[0021] The separation of chip sequences in a mobile device is achieved by correlating the received chip sequence with the locally generated code of the desired user. This process is called unspreading the received chip sequence, as it restores the original bandwidth. Because the different codes are designed to be orthogonal, separation of different users or of a single user becomes possible. If, as a result, the chip sequence matches the code of the desired user, the correlation function is high, and the system can extract this chip sequence. Otherwise, the chip sequence exhibits a correlation close to zero with the locally generated code of the desired user, making it impossible to recover the originally transmitted bitstream.

[0022] The present disclosure relates to a technique which can improve the equalization and symbol detection stage in high frequency-selective channels in order to increase the achievable throughput on the physical layer.

[0023] Fig. Figure 1 represents a mobile communications network comprising a base station 11 and a mobile terminal 12. The mobile terminal can be served by a first cell of the base station 11, which can consist of one or more cells (not explicitly shown in Figure 1). Fig. 1) The first cell could be any cell. The mobile communications network could, for example, be an HSPA communications network. However, it is understood that the description provided herein is also applicable to various other mobile communications technologies, both existing and yet to be formulated, for example, in cases where such mobile communications technologies share similar features, as disclosed with respect to the following examples.

[0024] As in Fig. As illustrated in Figure 1, the mobile device 12 can have an antenna 121, a radio frequency (RF) transceiver 122, a radio frequency baseband (RF-BB) interface 123, and a baseband modem 124. The aforementioned components of the mobile device 12 can be implemented as separate components. However, it is understood that the architecture of the mobile device 12, which is illustrated in Figure 1, Fig. Figure 1 is shown for illustrative purposes only, and accordingly, one or more of the aforementioned components of the mobile device 12 may be integrated into a single equivalent component or divided into two separate components with collective equivalence. It is understood that the mobile device 12 may have one or more additional components, such as hardware, software, or firmware elements. For example, the mobile device 12 may also have various additional components, including hardware, firmware, processors, microprocessors, memory, and other specialized or generic hardware / processors / circuits, etc., to support a variety of additional operations. The mobile device 12 may also have a variety of user input / output devices (display(s), keyboard(s), touchscreen(s), speaker(s), external button(s), camera(s), microphone(s), etc.).), peripheral device(s), storage, power supply, interface(s) for external devices, subscriber identification module(s) (SIM), etc. In particular, the mobile terminal 12 may have a BB-HF interface memory for storing radio samples.

[0025] It is understood that the aforementioned components of the mobile terminal 12, for example the RF transceiver 122, the BB RF interface 123, and the baseband modem 124, can be implemented in a number of different ways, such as by hardware, firmware, software running on hardware (e.g., a processor), or any combination thereof. Various options include analog circuitry, digital circuitry, logic circuitry, processor(s), microprocessor(s), controller(s), microcontroller(s), scalar processor(s), vector processor(s), central processing unit (CPU), graphics processing unit (GPU), digital signal processor(s) (DSP), field-programmable gate array(s) (FPGA), integrated circuit(s), or application-specific integrated circuit(s) (ASIC).

[0026] The high-frequency processing unit (the RF transceiver 122) can process a radio signal received via the antenna 121 and transmitted via a radio channel, downmix it to baseband, and then forward it to the RF BB interface 123. The radio channel can have a line-of-sight path 14, as shown in Fig. Figure 1 shows that the antenna 121 has a line-of-sight path 15a, 15b, which occurs when the radio signal is reflected, for example, by a building 13. As a result, a radio signal transmitted by the base station 11 can reach the antenna 121 directly via the line-of-sight path 14, and a delayed copy or copies of the radio signal can reach the antenna 121 via the non-line-of-sight path 15a, 15b. This scenario is called multipath propagation. The radio signal and its delayed copy or copies overlap at the antenna 121. Consequently, the delayed copy or copies can interfere with the radio signal received via the line-of-sight path 14. This phenomenon is called inter-symbol interference (ISI). The baseband modem 124, which receives the downmixed radio sample values ​​from the RF-BB interface 123, must take the ISI into account for correct detection.

[0027] In a simplified overview of the functionality of the mobile device 12, the mobile device 12 can be designed to receive and / or transmit wireless signals according to several different wireless access protocols or radio access technologies (RATs), including HSPA (High-Speed ​​Packet Access), LTE (Long Term Evolution), WLAN (Wireless Local Area Network), WiFi, UMTS (Universal Mobile Telecommunication System), GSM (Global Mobile Communication System), Bluetooth, CDMA (Code Division Multiple Access), Broadband CDMA (W-CDMA), etc., or any combination thereof. The RAT capabilities of the mobile device 12 can be determined by one or more subscriber identification modules (SIMs) contained in the mobile device 12 (not explicitly shown in Fig. 1) It is understood that separate components may be provided for each individual type of compatible wireless signals, such as a dedicated LTE antenna, a dedicated RF transceiver and a dedicated baseband modem for LTE reception and transmission, and a dedicated WiFi antenna, a dedicated RF transceiver and a dedicated baseband modem for WiFi reception and transmission.

[0028] Alternatively, one or more components of the mobile terminal 12 can be shared between different wireless access protocols, for example, by sharing the antenna 121 between several different wireless access protocols. In one aspect of the disclosure, the RF transceiver 122 and / or the baseband modem 124 can operate according to several mobile communication access protocols (i.e., "multi-mode") and can therefore be designed to support one or more of the HSPA, LTE, UMTS, and / or GSM access protocols. Alternatively, one or both of the RF transceiver 122 and the baseband modem 124 can be divided into two separate components, with each component reserved for a single radio access technology.

[0029] Furthermore, according to the abridged overview of the operation of the mobile device 12, the RF transceiver 122 can receive wireless high-frequency signals via the antenna 121, which can be implemented, for example, as a single antenna or an antenna array consisting of several antennas. The RF transceiver 122 can have various receiving circuit elements, which can include, for example, analog circuitry and be designed to process externally received signals, such as a mixer circuit for down-converting externally received RF signals to baseband and / or intermediate frequencies. The RF transceiver 122 can also have amplification circuitry for amplifying externally received signals, such as power amplifiers (PAs) and / or low-noise amplifiers (LNAs).The RF transceiver 122 may include low-noise amplifiers, although it is understood that such components can also be implemented separately. The RF transceiver 122 may also include various transmit circuit elements designed to transmit internally received signals, such as baseband and / or intermediate frequency signals provided by the baseband modem 124. These elements may include a mixer circuit for modulating internally received signals onto one or more high-frequency carrier waves and / or an amplification circuit for amplifying internally received signals before transmission. The RF transceiver 122 can transmit such signals to the antenna 121 for wireless transmission.Further references herein to the receiving and / or sending of wireless signals by the mobile terminal 12 are therefore to be understood as an interaction between the antenna 121, the RF transceiver 122 and the baseband modem 124, as detailed above.

[0030] Fig. Figure 2 shows a block diagram illustrating an internal configuration of the 124 baseband modem. Fig. Figure 1 illustrates this. The baseband modem 124 can include a linear equalizer 21, a spreader 22, a symbol detector 23, a demodulator 24, and a channel decoder 25. The baseband modem stages (which can also be called baseband modem circuits) essentially reverse the signal processing performed at the transmitter of a base station. The equalizer 21 takes the radio channel into account and compensates for it. A linear equalizer can be designed as a finite impulse response (FIR) filter, optimized with respect to a specific criterion such as minimum mean square error (MMSE) or maximum signal-to-noise ratio (SNR). It can process fractionally spaced I / Q samples provided by the transmit receiver 122 and retrieved by the BB-HF interface 123.The decoder converts radio sample values ​​(chip sequences) back into their original domain. The symbol detector 23 makes decisions about the symbols based on the input received from the decoder 22. The demodulator 24 generates bits that can then be decoded by the channel decoder 25 to yield the most likely transmitted bit sequence.

[0031] The Baseband Modem 124 can include digital processing circuitry, i.e., one or more digital processing circuits, a protocol processor, a baseband memory, and one or more additional stages, although in Fig. Not explicitly shown in Figure 1, the circuitry must have internal configurations to implement the configuration described above. Digital processing circuitry may consist of various processing circuit arrangements designed to perform baseband (including "intermediate") frequency processing, such as analog-to-digital converters (ADCs) and / or digital-to-analog converters (DACs), modulation / demodulation circuit arrangements, encoding / decoding circuit arrangements, audio codec circuit arrangements, digital signal processing circuit arrangements, etc. Digital processing circuitry may include hardware, software, or a combination of hardware and software.For example, the digital processing circuit(s) of the 124 baseband modem can include one or more logic circuits, processors, microprocessors, controllers, microcontrollers, scalar processors, vector processors, central processing units (CPUs), graphics processing units (GPUs) (including general-purpose computing on graphics processing units (GPGPU)), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), integrated circuits, application-specific integrated circuits (ASICs), etc., or any combination thereof.It is understood that a person skilled in the art will be able to recognize the corresponding structure disclosed herein, whether by explicit reference to a physical structure and / or in the form of mathematical formulas, prose, flowcharts, or any other manner that provides sufficient structure (such as with respect to an algorithm). The components of the baseband modem 124 can be described in detail herein, given that a person skilled in the art can easily recognize the various possible structural realizations of the baseband modem 124 using a digital processing circuit arrangement that provides the desired functionality, essentially with regard to its functional operation.

[0032] Fig. Figure 3 shows a block diagram illustrating a different internal configuration of the 124 baseband modem. Fig. Figure 1 illustrates the baseband modem 124, which can have two receive branches, a highest receive branch 31 and a lowest receive branch 32, both of which process the same radio sample values ​​y provided by the RF transceiver 33.

[0033] The lowest receiving branch 32 can include a second equalizer 321, which is designed to equalize the received radio signal y in order to generate and thus obtain a second equalized radio signal, and a resynthesizer 324, which is designed to resynthesize a transmit signal from the second equalized radio signal in order to generate and thus obtain a resynthesized transmit signal. It is apparent to a person skilled in the art that an equalizer 322 and a symbol detector 323 can be used to resynthesize the transmit signal.

[0034] The highest receiving branch 31 can include a first equalizer 314, which is designed to equalize the received radio signal in order to generate and thus obtain a first equalized received radio signal. The highest receiving branch 31 can further include a filter 315, which is designed to filter the resynthesized transmitted signal of a preceding branch, i.e., the lowest receiving branch 32, in order to generate and thus obtain a subtraction signal. The highest receiving branch 31 can further include a subtractor 316, which is designed to subtract the subtraction signal from the first equalized received radio signal. It is apparent to a person skilled in the art that the first equalizer 314, the filter 315, and the subtractor 316 form an equalizer 311. The highest receiving branch 31 can further include an equalizer 312 and a symbol detector 313. Through signal recovery (symbol decision, signal resynthesis), i.e.By feeding the signal into another FIR filter, a nonlinearity can be introduced, which is described in more detail below.

[0035] As previously mentioned, a mobile device can implement a method for processing a radio signal that includes receiving a radio signal in the mobile device, equalizing the received radio signal using a first equalizer to generate and thus obtain a first equalized received radio signal, equalizing the received radio signal using a second equalizer to generate and thus obtain a second equalized received radio signal, resynthesizing a transmit signal from the second equalized received radio signal, calculating a subtraction signal based on the resynthesized transmit signal, and subtracting the subtraction signal from the equalized received radio signal.

[0036] According to various aspects of this disclosure, filter 315 represents a residual multipath response B of a radio channel. The residual multipath response can be cascaded by a radio channel (not shown in Fig. 3) and the first equalizer 314 minus the correctly delayed Dirac delta impulse response, i.e., the main tap of the radio channel. As mentioned earlier, the subtractor 316 subtracts a subtraction signal, consisting of a resynthesized and filtered transmit signal from a preceding receive branch, from the first equalized receive radio signal. The subtraction signal can therefore be designed to represent the (negative) residual multipath interference present at the output of the other equalizer 314. In this way, intersymbol interference can be removed nonlinearly without any noise amplification (or SNR degradation) effect. The final symbol decision, which is made at the output of the symbol detector 313 in Fig. As shown in section 3, demodulation and channel decoding stages can follow (not shown in section 3). Fig. 3).

[0037] An advantage over a linear MMSE (least mean squared error) equalizer is provided by the nonlinear symbol decision prior to transmit signal recovery. It is worth noting that reliable symbol decisions are desirable for multipath interference subtraction. To achieve this, a high signal-to-noise ratio and / or robust modulation schemes, such as QPSK, can be employed. Alternatively, soft decision techniques can be used, as they intrinsically attenuate unreliable symbols by reducing their strength. Furthermore, a subsequent cancellation approach can be used, canceling only reliable symbols at a first stage. This, in turn, leads to higher reliability of initially weak symbols at later processing stages, which can then be subtracted again, and so on.

[0038] Filter 315 can therefore be designed such that the resulting subtraction signal processed by subtractor 316 represents multipath interference contained within the other equalized radio signal. However, filter 315 can also be designed such that the resulting subtraction signal processed by subtractor 316 represents neighbor-cell interference contained within the other equalized radio signal. The filter coefficients determine the type of interference, i.e., neighbor-cell or multipath.

[0039] Several aspects of the present disclosure relate to different designs of the first equalizer 314 with an equalizer coefficient matrix F1, the second equalizer 321 with an equalizer coefficient matrix F2, and the cancellation filter 315 with a filter coefficient matrix B. It should be noted that the size of the equalizer coefficient matrices and the cancellation filter coefficient matrix depends on the number of receiving antennas. It should also be noted that the antenna 121 is in Fig. 1. It could therefore be an antenna group.

[0040] The first equalizer 314 with equalization coefficient matrix F1 in the highest receive branch 31 can be designed as a (linear) MMSE (least mean squared error) equalizer. The equalization coefficient matrix F1 of the first equalizer 314 can be identical to the equalization coefficient matrix F2 of the second equalizer 321, which was calculated in the second receive branch 32 to minimize the mean squared error between an output signal of the second equalizer 321 and the transmitted signal. In this case, the coefficients of the cancellation filter 315 with filter coefficient matrix B must reflect the residual multipath interference of the equalizer output (F1 and F2, respectively), which is obtained by subtracting the Dirac delta impulse response with the correct delay from the equalizer channel cascade (h[n] * f). l [n]) is obtained, where h[n] is the channel impulse response, f l[n] is the impulse response of the first equalizer 314 in the first receiver branch 31 (which corresponds to the matrix notation F1), and “*” is intended to represent the convolution between the sequences.

[0041] In other words: Choose F1=F2=(σx2HHH+σn2I)−1σx2Hep corresponding to the linear MMSE solution and B as a cascade filter matrix, which represents the convolution between the channel impulse response h and the function f1 of the first equalizer 314 minus the Dirac delta impulse response for the correct delay and undersampling by a factor of “2”. σx2 corresponds to the signal energy, while σn2 the energy of the additive white Gaussian noise n corresponds to, e pThis denotes the unit vector with the entry "1" that achieves the desired delay. Subtracting the Dirac delta impulse response for the correct delay adjusts the cascade of the radio channel and the first equalizer 314 by the main tap; that is, the main tap is removed from the cascade's impulse response. In this way, residual intermediate symbol interference, or at least parts of it, can be removed from the equalized output chip sequence of the first equalizer 314, thus improving subsequent decision performance.

[0042] If the symbol decisions and the resynthesized signal are perfect, multipath interference can be completely eliminated, apart from channel estimation errors and limitations resulting from the equalizer coefficient calculation. Since the second receiving branch 32 is capable of removing multipath interference as long as the resynthesized signal is reliable enough, it seems even more attractive to use the degrees of freedom of the equalizer F1 to suppress noise rather than worrying about multipath interference.

[0043] The first equalizer 314 with equalization coefficient matrix F1 in the highest receive branch 31 can be designed as an impedance matching filter. The equalization coefficient matrix F1 can be adapted to the radio channel impulse response to suppress noise as much as possible. The cancellation filter 315 with filter coefficient matrix B can, in this case, remove multipath interference, which in turn can be represented as a cascade of the radio channel and the equalization coefficient matrix F1 minus the Dirac delta impulse response with the correct delay. The equalization coefficient matrix F1 of the equalizer channel cascade is, in this case, an impedance matching filter. Inter-symbol interference is not suppressed by the first equalizer 314 at all, since it is subtracted anyway at the next processing stage. The cancellation filter matrix B is therefore designed to represent the cascade of the channel and the adapted channel impulse response of the first equalizer 314 adapted around the main tap.

[0044] In other words: Choose F1 = H H (as an adaptation filter for the channel impulse response) and F2=(σx2HHH+σn2I)−1σx2Hep as a linear MMSE solution and B as a cascade filter matrix, which represents the convolution between the channel impulse response h and the equalizer filter f1 minus the Dirac delta impulse response for the corrected delay and undersampling by 2. It can be assumed that the multipath interference at the output of the equalizer in the first receive channel 31 is quite large for typical propagation channels.

[0045] The first equalizer 314 with equalization coefficient matrix F1 in the highest receive branch 31 and the cancellation filter 315 with filter coefficient matrix B can be designed to jointly minimize a mean squared estimation error. A joint optimization of both filter coefficient matrix B and equalization coefficient matrix F1 is disclosed below, which automatically weights the contribution of the resynthesized transmit signal and the equalization in the first receive branch 31 depending on the quality of the resynthesized transmit signal.

[0046] Since the contribution of the resynthesized transmit signal x̌ influences the joint solution x̃, it is desirable to reliably resynthesize this transmit signal and, consequently, to reliably restore the output signal x̃2 of the second equalizer 321. This can be achieved by an optimization that takes into account the signal-to-noise ratio (SNR) of the restored signal in the second receive branch 32. The task is to minimize F1,B E[||x̃ - x|| 2 ], to determine, i.e., to provide filter coefficients that lead to the solution of the least mean squared error (MMSE) for the receiver structure that is in Fig. 3 is disclosed, where x̃ corresponds to the estimate of x already taking into account the “multipath cancellation”, where x is the original transmit signal on the transmitter side, for example the base station 11 in Fig. 1, is.

[0047] Now with reference to Fig. Section 4 explains the optimization using the presented system model. The system model assumes a received signal or observation y, which results from a multipath loss channel and uiv additive white Gaussian noise. nk∼N(0,σ2) y=Hx+n is obtained where y, x, and n are vectors, and H is the channel matrix, which represents the channel impulse response when the transmitted signal x is convolved with the channel and oversampling by a factor of 2. The size of the matrix and the vectors is determined by the oversampling factor, the number of equalization coefficients, the number of channel coefficients, and the number of receiving antennas. The received signal y is then split into the two branches (31 and 32 in Fig. 3) fed into the architecture, which applies equalization, drafting, spreading, and symbol detection. The equalization coefficients in the two branches, as well as the filter coefficient matrix B, can be designed to allow a good estimation of the recovered transmitted signal.

[0048] The second equalizer 321 in the second receiver branch 32 equalizes the observation y of the equalizer coefficient matrix F2, which contains the undersampling by a factor of 2: x˜2=F2y=F2Hx+F2n.

[0049] The result is an estimate of the transmitted chip sequence x̃2, which the deconstructor / de-spreader 322 deconstructs and de-spreads into the estimated transmitted symbols, which the symbol detector 323 determines. The symbol detector 323 makes either hard decisions based on the assumed modulation alphabet or some kind of soft decision that takes into account the signal-to-noise ratio (SNR) of the symbols after de-spreading. Based on the determined symbols and estimates of the applied code power, the resynthesizer 324 resynthesizes the transmitted signal. x⌣=x+v, where v can be an AWGN (additive white Gaussian noise) model of the estimation error remaining after symbol selection. Other models for this noise are, of course, also possible. This error can consist of thermal noise and residual interference. Naturally, errors in symbol selection can lead to significant noise at the output of symbol detector 323. The noise variance at the output of symbol detector 323 in the second receive branch 32 can provide reliability information for the output of the second receive branch 32 and therefore determine the weighting of the two branches as well as the equalizer and cascade coefficient design.

[0050] The output signal of the first receiving branch 31 before subtraction by the subtractor 316 is given as: x˜1=F1y=F1Hx+F1n Finally, the equalizer 311 generates the estimated transmission sequence as: x˜=x˜1−Bx⌣=F1Hx+F1n−Bx−Bv=(F1H−B)x+F1n−Bv

[0051] Since the cancellation filter 315 filters the replica of the transmitted signal in the second receiving branch 32 by B, and the subtractor 316 subtracts this replica from the equalized received signal x̃1 of the first receiving branch 31, the signal quality is improved before drafting and spreading by the drafter / spreader 312.

[0052] Under specific assumptions about the noise correlations, the solution to the optimization problem stated above is given as f1=[σx2HHH+(1+σx2σv2)σn2I]−1σx2Hep b=σx2σx2+σv2(HHf1−ep)

[0053] If σv2=0,σx2≠0 and σn2≠0, If the transmitted signal resynthesis works perfectly in the second receiving branch, then it follows that f1 = 0 and b = -e p . If σv2>>σx2, Then it follows that b = 0 and f1 corresponds to the MMSE solution given above.

[0054] If the resynthesized transmit signal is already correct, i.e., x̌ = x, then no additional equalization is needed in the first receive branch 31, and the symbols are correctly obtained by drafting and spreading. The minus sign of cancellation is compensated by the minus in the formula for b. In all other cases, it turns out that the cascade is obtained by removing the main tap from the channel equalizer cascade, which is formed by σx2σx2+σv2. is weighted. For small σv2≠0 This leads to a solution that is very close to the solution heuristically determined for MMSE or the fitting filter.

[0055] In principle, it can be observed that the heuristic solutions mentioned above also receive some motivation from the optimal solution. The cascade filter b can be obtained by subtracting a Dirac delta impulse response from the equalizer channel cascade. The optimal solution should therefore represent an envelope of the heuristically motivated solutions, at least when the complete transmitted signal, and not just the part based on "reliable" symbols, is recovered. The optimization is based on the subtraction of x. If only parts of it are subtracted, the remaining part can be considered in the noise section v. The same applies to small soft values ​​that are the result of unreliable symbol decisions. σv2>>σx2, This means that if the recovered transmitted signal is not very reliable, then b becomes small, and the information from the second receiving branch is suppressed instead to avoid erroneous decisions. In this case, the equalization in the first receiving branch could degrade the state-of-the-art linear equalization.

[0056] As mentioned previously, the joint minimization of the estimation error by the equalizer 314 and the cancellation filter 315 can be based on modeling the recovered transmit signal as the correct transmit signal plus a noise component: x̌ = x + v. The recovered transmit signal can be obtained by selecting the equalization coefficients of the second equalizer 321 according to the MMSE criterion. Modeling the recovered transmit signal allows for a joint optimization of the equalization coefficient of the first equalizer 314 and the filter coefficients of the cancellation filter 315 according to a specific criterion, such as the least mean squared error between the estimated transmit chips before the input of the equalizer / de-spreader 312 and the actually transmitted chips. For the special case that the recovered transmit signal is already correct (i.e.,(where the noise component is zero), the obvious solution of the optimization leads to a cancellation filter B with a Dirac delta impulse response, while the filter coefficient matrix F1 of the first equalizer 314 contains only zero coefficients.

[0057] Several aspects of the present disclosure relate to subsequent intersymbol interference subtraction. These aspects are based on the fact that parts of the signal may either be known, such as the pilot symbols of a common pilot channel (CPICH), or can be detected with higher reliability than others, e.g., larger spreading factors or higher relative transmit power. The interference of these parts is subtracted first. On the one hand, this avoids degrading the signal quality by subtracting erroneous intersymbol interference. On the other hand, the equalizer optimization criterion used in a subsequent receive branch can neglect the signal parts that will be subtracted later anyway. This improves the equalizer performance for the remaining parts.This also means that further signal components in the corresponding receiving branch can be reliably detected and used for possible further subtraction in a subsequent receiving branch. In this case, the receiver architecture can be, as in . Fig. 3 shows that it can be extended accordingly by adding an additional receiving branch or even several additional receiving branches.

[0058] Now with reference to Fig. The receiver comprises a lowest receiving branch 53, a highest receiving branch 51, and an intermediate receiving branch 52 located between the lowest receiving branch 53 and the highest receiving branch 51. Each of the receiving branches 51, 52, 53 includes an equalizer 514, 524, 531, followed by a decongestant / de-spreader 512, 522, 532, and a symbol detector 513, 523, 533, respectively, to form a complete receive radio signal recovery path. The equalizer 531, located in the lowest receiving branch 53, equalizes a receive radio signal to generate and thus maintain an equalized receive radio signal. The intermediate receiving branch 52 has a resynthesizer 527 which resynthesizes a transmit signal from the equalized received radio signal of the lowest receiving branch 53 in order to generate and thus obtain a resynthesized transmit signal.It should be noted that in this example, the resynthesizer 527 belongs to the intermediate receive branch 52. However, the resynthesizer 527 could instead belong to the lowest receive branch 53.

[0059] The resynthesizer 527 can be designed to resynthesize a transmit signal from the equalized receive radio signal of the lowest receive branch 53 by considering only those parts of the equalized receive radio signal of the lowest receive branch 53 that satisfy a reliability criterion. Such parts are known parts of the equalized radio receive signal, such as pilots. Alternatively, such parts can be parts of the equalized radio receive signal that have been encoded with a spreading factor exceeding a spreading factor threshold, or parts of the equalized radio receive signal that were received with a transmit power exceeding a transmit power threshold. A cancellation filter 525 filters the transmit signal resynthesized in this way to determine either the residual intersymbol interference or the residual neighbor cell interference.Since only reliable components are used to determine the interference, the subtractor 526 is less likely to subtract erroneous inter-symbol interference or neighboring cell frequency compared to a configuration in which the resynthesizer 527 would resynthesize the entirety, including the unreliable parts, of the received radio signal from the lowest receiving branch 53. Consequently, the subtractor 526 subtracts more reliable interference from the equalized received radio signal generated by the equalizer 524, which is determined by the cancellation filter 525, thereby improving the recovery quality in the intermediate receiving branch 52. It should be noted that the equalizer 524, the cancellation filter 525, and the subtractor 526 together form an equalizer 521.

[0060] A computation coefficient calculation by the equalizer 524 can therefore ignore parts of the received radio signal that are subtracted by the subtractor 526, further improving the quality of the signal recovery of the intermediate receiving branch 52. As a result, other parts of the received radio signal can be recovered more reliably, so that they meet the reliability criteria. The resynthesizer 517 resynthesizes the recovered signal of the intermediate receiving branch 52 that meets the reliability criteria. The cancellation filter 515 then filters the transmitted signal resynthesized in this way to determine either the residual inter-symbol interference or the residual neighboring cell interference.Since the cancellation filter 515 filters only the reliable parts of the signal recovered in the intermediate reception branch 52 to determine the interference, the subtractor 516 is less likely to subtract erroneous inter-symbol interference or neighboring cell frequency compared to a configuration in which the resynthesizer 517 would resynthesize the entirety, including the unreliable parts, of the received radio signal of the intermediate reception branch 52. Consequently, the subtractor 516 subtracts more reliable interference from the equalized received radio signal generated by the equalizer 514, which is determined by the cancellation filter 515, thereby improving the recovery quality in the highest reception branch 51. It should be noted that the equalizer 514, the cancellation filter 515, and the subtractor 516 form a non-linear equalizer 511. It should also be mentioned that in this example the Resynthesizer 517 belongs to the highest receiving branch 51.However, the resynthesizer 517 can instead belong to the intermediate receiving branch 52.

[0061] A computation coefficient calculation of the equalizer 514 can therefore also ignore parts of the received radio signal that are subtracted by the subtractors 516 and 526, thereby further improving the signal recovery quality of the highest receive branch 51. A demodulator and a channel decoder can follow the highest receive branch 51 (not shown in [reference]). Fig. 5) It should be noted that the equalizers 514, 524, and 531 can be of the MMSE type. However, each of the equalizers 514, 524, and 531 can also be of the MF type. Furthermore, the equalizer and cancellation filter of each of the receiving branches can be designed to collectively minimize the estimation error.

[0062] Several aspects of the present revelation concern a subsequent reduction in intoxication.

[0063] Again with reference to Fig. The concept underlying this receiver architecture is to perform equalization successively by subtracting reliably detected components through additional receive branches, such as a third receive branch 53 in addition to the first and second receive branches 52. This ensures that the equalization of the remaining component no longer requires any degrees of freedom for these components. Besides its application to reliable or known channels, such as CPICH or channels modulated by quaternary phase shift keying (QPSK), this concept can even be extended to noise. The principle here is that the detected noise is no longer considered part of the input signal in successive branches of the equalizer and therefore does not influence the calculated equalization coefficients.

[0064] Again with reference to Fig. For example, in the lowest receiving branch 53, the equalizer 531 is designed to recover the noise by suppressing any arbitrary signal segment. The equalizer 524 of the subsequent receiving branch 52 is designed to disregard the recovered noise. Consequently, the recovered noise is not considered part of the input signal to the equalizer 524. Instead, the subtractor 526 subtracts the recovered noise at the output of the equalizer 524. This can provide a better estimate of the signal than by considering the noise when calculating the filter coefficients of the equalizer 524. In this estimate, the known or highly reliable detected symbols in the signal can be recovered and subtracted by the subsequent highest receiving branch 51.In the highest receiving branch 51, the equalizer 514 no longer needs to take into account the noise and the reliably detected signal part of the previous receiving branch 52. This allows for a better signal estimation of the missing signal part.

[0065] Several aspects of the present revelation concern a general expansion of the receiver architecture, as in Fig. 5 shown. This receiver architecture can be extended by any number of successive cancellation stages, i.e., receive branches 61, 62, ... 6n, as shown in Fig. Figure 6 illustrates the simultaneous implementation of successive inter-symbol interference cancellation and / or (successive) neighbor-cell interference cancellation. Each of the receive branches 61, 62, 6n can use only the reliable portions of the recovered transmitted signal for interference subtraction from a preceding receive branch. This avoids degradation caused by subtracting erroneous interference and allows a subsequent receive branch to ignore, in its equalizer design, those portions of the signal that would be canceled out anyway by the subtraction path. Consequently, each receive branch can generate more reliable estimates of further portions of the transmitted signal, which can then be subtracted by the subsequent receive branch.Starting with a lowest receive branch 6n, this procedure can be continued until either all components have already been subtracted or the reliability of the recovered signal becomes too low to be considered for further cancellation. The type of interference (inter-symbol or neighbor-cell) is determined solely by the choice of filter coefficients for the cancellation filter in the receive branch.

[0066] Several aspects of this revelation can be used in highly frequency-selective propagation channels. Or, put another way, in channels with very long delay spreads, such as 3GPP Pedestrian B, and channels with closely spaced paths of nearly equal strength. Such channels occur in both laboratory / operator testing and typical road tests. Generally, these types of channels cannot be equalized by linear equalizers without noise gain, i.e., without degrading the signal-to-noise ratio (SNR) at the equalizer output.

[0067] Various aspects of this revelation can be implemented in any mobile communication system that exhibits inter-symbol interference and neighbor-cell interference. Therefore, the receive branches 31, 32 of the receiver architecture, as in Fig. Figure 3 shows the receiver branches 51, 52, 53 of the receiver architecture, as shown in Fig. 5 shown, or the receiver branches 61, 62, ..., 6n of the receiver architecture, as in Fig. Figure 6 shows that a receiver does not have an equalizer if, for example, it is not based on code-division multiplexing. Each of the aforementioned receive branches may have alternative or additional components of a different RAT between the equalizer and the resynthesizer, which generate a signal from which the resynthesizer can resynthesize a transmit signal. It should also be noted that it is apparent to a person skilled in the art that the assignment of the resynthesizer to a specific branch is purely arbitrary. A resynthesizer of a specific receive branch may either resynthesize a transmit signal that is provided for the cancellation filter of the receive branch, or the resynthesizer may be designed to resynthesize a transmit signal that is provided for a subsequent receive branch.

[0068] The following illustrates various aspects of this revelation.

[0069] Example 1 is a method for processing a received radio signal. The method may include receiving a received radio signal in a mobile device, equalizing the received radio signal using a first equalizer to generate a first equalized received radio signal, equalizing the received radio signal using a second equalizer to generate a second equalized received radio signal, resynthesizing a transmit signal from the second equalized received radio signal, calculating a subtraction signal based on the resynthesized transmit signal, and subtracting the subtraction signal from the first equalized received radio signal.

[0070] In Example 2, the item according to Example 1 may optionally feature that the calculation of a subtraction signal based on the resynthesized transmit signal includes filtering of the resynthesized transmit signal using a filter that represents a residual multipath response of a radio channel.

[0071] In Example 3, the item according to Example 2 can optionally have the filter representing the remaining multipath response of a radio channel being given by a cascade of the radio channel and the first equalizer minus a correctly delayed Dirac delta impulse response of the cascade.

[0072] In Example 4, the object according to one of Examples 1 to 3 may optionally exhibit that the subtraction signal represents multipath interference contained in the first equalized radio signal.

[0073] In Example 5, the object according to one of Examples 1 to 4 may optionally have the subtraction signal representing a neighbor cell interference contained in the first equalized radio signal.

[0074] In Example 6, the item according to one of Examples 1 to 5 may optionally include resynthesizing the transmit signal: drafting and unspreading the equalized second receive signal to generate estimated transmit symbols, symbol-based detection of the transmit symbols, and respreading and re-scrolling the symbols to transmit chips.

[0075] In Example 7, the item according to one of Examples 1 to 6 may optionally have the first equalizer and the second equalizer each designed as MMSE (smallest mean squared error) filters.

[0076] In Example 8, the item according to one of Examples 1 to 6 may optionally have the first equalizer designed as an matching filter of a radio channel through which the received radio signals are received, and the second equalizer designed as an MMSE filter.

[0077] In Example 9, the item according to one of Examples 1 to 6 may optionally have that the second equalizer is designed as an MMSE filter, or that the first equalizer and the filter representing the remaining multipath response are jointly designed as an MMSE filter.

[0078] In Example 10, the item according to one of Examples 1 to 9 may optionally feature that the resynthesis of a transmit signal from the second equalized receive radio signal includes consideration of parts of the second equalized receive radio signal that meet a reliability criterion.

[0079] In Example 11, the item according to Example 10 may optionally have parts of the second equalized received radio signal that are known parts of the second equalized received radio signal.

[0080] In Example 12, the object according to Example 11 may optionally have parts of the second equalized received radio signal that are pilot symbols.

[0081] In Example 13, the item according to one of Examples 10 to 12 may optionally have parts of the second equalized received radio signal that satisfy a reliability criterion are parts of the second equalized received radio signal that have been encoded with a spreading factor that exceeds a spreading factor threshold.

[0082] In Example 14, the item according to one of Examples 10 to 13 may optionally have parts of the second equalized received radio signal that satisfy a reliability criterion are parts of the second equalized received radio signal that were received with a transmit power that exceeds a transmit power threshold.

[0083] Example 15 is a method for processing a received radio signal. The method can include receiving a received radio signal in a mobile device, equalizing the received radio signal using a first equalizer to produce a first equalized received radio signal, equalizing the received radio signal using a second equalizer to produce a second equalized received radio signal, equalizing the received radio signal using a third equalizer to produce a third equalized received radio signal, resynthesizing a first transmit signal from the third equalized received radio signal by considering parts of the third equalized received radio signal that satisfy a first reliability criterion to produce a first resynthesized transmit signal, and calculating a first subtraction signal based on the first resynthesized transmit signal.Subtracting the first subtraction signal from the second equalized received radio signal, resynthesizing a second transmit signal from the second equalized received radio signal by considering parts of the second equalized received radio signal that satisfy a second reliability criterion to generate a second resynthesized transmit signal, calculating a second subtraction signal based on the second resynthesized transmit signal, and subtracting the second subtraction signal from the first equalized received radio signal.

[0084] In Example 16, the item according to Example 15 may optionally include the calculation of the first subtraction signal based on the first resynthesized transmit signal, which involves filtering the first resynthesized transmit signal using a filter that represents a residual multipath response of a radio channel.

[0085] In Example 17, the item according to Example 16 may optionally include the calculation of the second subtraction signal based on the second resynthesized transmit signal, which involves filtering the second resynthesized transmit signal using a filter that represents a residual multipath response of a radio channel.

[0086] In Example 18, the item according to one of Examples 15 to 17 may optionally have the filter representing the remaining multipath response given by a cascade of the channel and the corresponding equalizer minus a correctly delayed Dirac delta impulse response of the cascade.

[0087] In Example 19, the item according to one of Examples 15 to 18 may optionally have such that each of the first and second subtraction signals represents multipath interference contained in the first equalized signal or in the second equalized signal.

[0088] In Example 20, the object according to one of Examples 15 to 19 may optionally have such that each of the first and second subtraction signals represents a neighbor cell interference contained in the first equalized signal or in the second equalized signal.

[0089] In Example 21, the item according to one of Examples 15 to 20 may optionally include that the resynthesis of the first and second transmit signals involves drafting and unspreading the first and second equalized received radio signals to generate estimated transmit symbols, symbol-related detection of the transmit symbols, and respreading and re-scrolling the symbols to transmit chips.

[0090] In Example 22, the item according to one of Examples 15 to 21 may optionally have each equalizer designed as an MMSE filter.

[0091] In Example 23, the item according to one of Examples 15 to 21 may optionally have the first equalizer designed as an matching filter of a channel through which the receiving radio signals are received, and the second equalizer designed as an MMSE filter.

[0092] In Example 24, the item according to one of Examples 15 to 21 may optionally have that the second equalizer is designed as an matching filter of a channel through which the receiving radio signals are received, and that the third equalizer is designed as an MMSE filter.

[0093] In Example 25, the item according to any of Examples 15 to 21 may optionally include that one of the first, second or third equalizers is designed as an MMSE filter, and that minimizing a mean squared estimation error neglects estimation signal parts that were subtracted in a previous receive branch.

[0094] Example 26 is a receiver for a mobile radio communication device. The receiver may have a lowest receive branch. The lowest receive branch may include a second equalizer designed to equalize a received radio signal to produce a second equalized received radio signal, and a resynthesizer designed to resynthesize a transmit signal from the second equalized received radio signal to produce a resynthesized transmit signal. The receiver may further include a highest receive branch.The highest receive branch may include a first equalizer designed to equalize the received radio signal to produce a first equalized received radio signal, a filter designed to filter the resynthesized transmitted signal of a preceding receive branch to produce a subtraction signal, and a subtractor designed to subtract the subtraction signal from the first equalized received radio signal.

[0095] In Example 27, the device according to Example 26 may optionally include at least one further receiving branch arranged between the lowest receiving branch and the highest receiving branch. The at least one further receiving branch may include an equalizer designed to equalize a received radio signal to produce an equalized received radio signal, a filter designed to filter a resynthesized transmit signal of a preceding receiving branch to produce a subtraction signal, a subtractor designed to subtract the subtraction signal from the equalized received radio signal to produce a subtracted equalized received radio signal, and a resynthesizer designed to resynthesize a transmit signal from the subtracted equalized received radio signal to produce a resynthesized transmit signal.

[0096] In Example 28, the device according to Example 26 may optionally include a receiver further comprising several cascaded receive branches arranged between the lowest receive branch and the highest receive branch. Each of the several cascaded receive branches may include an equalizer designed to equalize a receive radio signal to produce an equalized receive radio signal, a filter designed to filter a resynthesized transmit signal of a preceding receive branch to produce a subtraction signal, and a subtractor designed to subtract the subtraction signal from the equalized receive radio signal.

[0097] In Example 29, the subject matter according to one of Examples 27 or 28 may optionally include that the at least one other receiving branch or each of the several cascaded receiving branches has a resynthesizer designed to resynthesize a transmit signal from a linearly or non-linearly equalized received radio signal of the receiving branch in order to produce a resynthesized transmit signal.

[0098] In Example 30, the item according to Example 29 may optionally have that each filter represents a residual multipath response given by a cascade of the channel and the corresponding equalizer minus a correctly delayed Dirac delta impulse response of the cascade.

[0099] In Example 31, the object according to one of Examples 26 to 30 may optionally have such that each subtraction signal represents a multipath interference contained in a corresponding equalized signal.

[0100] In Example 32, the object according to one of Examples 26 to 31 may optionally have such that each subtraction signal represents a neighbor cell interference contained in a corresponding equalized signal.

[0101] In Example 33, the object according to any of Examples 26 to 31 may optionally include that each receiving branch further comprises a decongestor / de-spreader designed to process each decongested signal to produce estimated transmit symbols, a symbol detector designed to detect the transmit symbols, and again spread and decongest the symbols to transmit chips.

[0102] In Example 34, the item according to one of Examples 26 to 33 may optionally include at least one of the receiving branches having a resynthesizer designed to resynthesize a transmit signal from an equalized received radio signal by taking into account parts of the equalized received radio signal that satisfy a reliability criterion.

[0103] In Example 35, the item according to Example 34 may optionally have parts of the equalized received radio signal that are known parts of the equalized received radio signal.

[0104] In Example 36, the object according to Example 35 may optionally have parts of the equalized received radio signal that are pilot symbols.

[0105] In Example 37, the item according to Example 34 may optionally have parts of the equalized received radio signal that satisfy a reliability criterion are parts of the equalized received radio signal that have been encoded with a spreading factor that exceeds a spreading factor threshold.

[0106] In Example 38, the item according to Example 34 may optionally have parts of the equalized received radio signal that satisfy a reliability criterion are parts of the equalized received radio signal that were received with a transmit power that exceeds a transmit power threshold.

[0107] In Example 39, the object according to any of Examples 26 to 38 may optionally include an equalizer of a receive branch designed to recover noise contained in the receive branch, and a subtractor of a subsequent receive stage designed to subtract the recovered noise from an output of an equalizer of a subsequent stage.

[0108] In Example 40, the item according to Example 39 may optionally have that the equalizer of the subsequent receiving branch is designed to ignore the recovered noise.

[0109] In Example 41, the item according to one of Examples 26 to 40 may optionally have an equalizer coefficient calculation of an equalizer of a receive branch designed to ignore parts of the received radio signal that are subtracted by a subtractor of the receive branch.

[0110] In Example 42, the item according to one of Examples 26 to 40 may optionally include an equalizer coefficient calculation of an equalizer of a receive branch designed to ignore parts of the received radio signal that are subtracted by a subtractor of a preceding receive branch.

[0111] In Example 43, the item according to Example 26 can optionally have the preceding receiving branch being the lowest receiving branch.

[0112] Example 44 is a mobile radio communication terminal. The mobile radio communication terminal may include a receiver. The receiver may have a lowest receive branch. The lowest receive branch may include a second equalizer designed to equalize a received radio signal to produce a second equalized received radio signal, and a resynthesizer designed to resynthesize a transmit signal from the second equalized received radio signal to produce a resynthesized transmit signal. The receiver may further include a highest receive branch.The highest receive branch may include a first equalizer designed to equalize the received radio signal to produce a first equalized received radio signal, a filter designed to filter the resynthesized transmitted signal of a preceding receive branch to produce a subtraction signal, and a subtractor designed to subtract the subtraction signal from the first equalized received radio signal. The mobile radio communication terminal may further include an application processor coupled to the receiver.

[0113] Example 45 is a computer-readable medium containing computer-readable instructions for performing a procedure for processing a received radio signal. The procedure may include receiving a received radio signal in a mobile device, equalizing the received radio signal using a first equalizer to produce a first equalized received radio signal, equalizing the received radio signal using a second equalizer to produce a second equalized received radio signal, resynthesizing a transmit signal from the second equalized received radio signal, calculating a subtraction signal based on the resynthesized transmit signal, and subtracting the subtraction signal from the equalized received radio signal.

[0114] Although the invention has been presented and described with regard to specific embodiments, it should be understandable to those skilled in the art that various changes in form and detail can be made without deviating from the essence and scope of protection of the invention as defined in the claims. The scope of protection of the invention is therefore specified by the appended claims, and all modifications that fall within the scope and equivalence of the claims are thus intended to be covered by them.

Claims

[1] Method for processing a received radio signal, wherein the method comprises: Receiving a receiving radio signal in a mobile device; Equalizing the received radio signal using a first equalizer to generate a first equalized received radio signal; Equalizing the received radio signal using a second equalizer to generate a second equalized received radio signal; Calculating a first subtraction signal based on a first resynthesized transmit signal; Subtracting the first subtraction signal from the second equalized received radio signal to generate a subtracted equalized received radio signal; Resynthesize a second transmit signal from the subtracted, equalized received radio signal; Calculating a second subtraction signal based on the resynthesized second transmit signal; and Subtracting the second subtraction signal from the first equalized received radio signal. [2] Method according to claim 1, wherein calculating a second subtraction signal based on the resynthesized second transmit signal involves filtering the resynthesized transmit signal using a filter that represents a residual multipath response of a radio channel; where optionally the filter representing the remaining multipath response of a radio channel is given by a cascade of the radio channel and the first equalizer minus a correctly delayed Dirac delta impulse response of the cascade. [3] Method according to one of claims 1 or 2, wherein the second subtraction signal represents a multipath interference contained in the first equalized radio signal. [4] Method according to any one of claims 1 to 3, wherein the second subtraction signal represents a neighboring cell interference contained in the first equalized radio signal. [5] Method according to any one of claims 1 to 4, wherein the resynthesis of the second transmit signal comprises: Drafting and decongesting the subtracted, equalized received signal to generate estimated transmit symbols; and Symbol-based detection of the transmitted symbols; and Re-spreading and re-shuffling the symbols to create transmit chips. [6] Method according to any one of claims 1 to 5, wherein the first equalizer and the second equalizer are each designed as MMSE (smallest mean squared error) filters. [7] Method according to any one of claims 1 to 5, wherein the first equalizer is designed as an matching filter of a radio channel through which the received radio signals are received, and the second equalizer is designed as an MMSE filter. [8] Method according to any one of claims 1 to 5, the second equalizer is designed as an MMSE filter; and where the first equalizer and the filter representing the remaining multipath response are jointly designed as an MMSE filter. [9] Method according to any one of claims 1 to 8, wherein the resynthesis of the second transmit signal from the subtracted equalized received radio signal involves taking into account parts of the subtracted equalized received radio signal that meet a reliability criterion; where optionally parts of the subtracted equalized received radio signal are known parts of the subtracted equalized received radio signal; where optionally parts of the subtracted, equalized received radio signal are pilot symbols. [10] Method for processing a received radio signal, wherein the method comprises: Receiving a receiving radio signal in a mobile device; Equalizing the received radio signal using a first equalizer to generate a first equalized received radio signal; Equalizing the received radio signal using a second equalizer to generate a second equalized received radio signal; Equalizing the received radio signal using a third equalizer to generate a third equalized received radio signal; Resynthesizing a first transmit signal from the third equalized receive radio signal by taking into account parts of the third equalized receive radio signal that meet a first reliability criterion in order to generate a first resynthesized transmit signal; Calculating a first subtraction signal based on the first resynthesized transmit signal; Subtracting the first subtraction signal from the second equalized received radio signal; Resynthesizing a second transmit signal from the second equalized receive signal by taking into account parts of the second equalized receive signal that meet a second reliability criterion in order to generate a second resynthesized transmit signal; Calculating a second subtraction signal based on the second resynthesized transmit signal; and Subtracting the second subtraction signal from the first equalized received radio signal. [11] Method according to claim 10, wherein calculating the first subtraction signal based on the first resynthesized transmit signal involves filtering the first resynthesized transmit signal using a filter that represents a residual multipath response of a radio channel; where optionally the calculation of the second subtraction signal based on the second resynthesized transmit signal includes filtering the second resynthesized transmit signal using a filter that represents a residual multipath response of a radio channel. [12] Method according to one of claims 10 or 11, wherein the filter representing the remaining multipath response is given by a cascade of the channel and the corresponding equalizer minus a correctly delayed Dirac delta impulse response. [13] Method according to any one of claims 10 to 12, wherein each of the first and second subtraction signals represents a multipath interference contained in the first equalized signal or in the second equalized signal. [14] Method according to any one of claims 10 to 13, wherein each equalizer is designed as an MMSE (smallest mean squared error) filter. [15] Method according to any one of claims 10 to 13, wherein the first equalizer is designed as an matching filter of a channel through which the receiving radio signals are received, and the second equalizer is designed as an MMSE filter. [16] Method according to any one of claims 10 to 13, wherein the second equalizer is designed as an matching filter of a channel through which the receiving radio signals are received, and the third equalizer is designed as an MMSE filter. [17] Method according to any one of claims 10 to 13, wherein one of the first, second or third equalizers is designed as an MMSE filter, and wherein minimizing a mean squared estimation error neglects estimation signal parts that were subtracted in a previous receive branch. [18] Receiver for a mobile radio communication device, comprising: one or more low receiving branches, having: a second equalizer designed to equalize a received radio signal in order to produce a second equalized received radio signal; and a second filter designed to filter a second resynthesized transmit signal to generate a second subtraction signal; a second subtractor designed to subtract the second subtraction signal from the second equalized received radio signal in order to produce a second subtracted equalized received signal; a resynthesizer designed to resynthesize a transmit signal from the second equalized receive radio signal in order to produce a resynthesized transmit signal; wherein the one or more low receiving branches are either a lowest receiving point or an intermediate receiving point arranged between the lowest receiving point and a highest receiving point; and where the highest receiving branch has: a first equalizer designed to equalize the received radio signal in order to produce a first equalized received radio signal; a first filter designed to filter the resynthesized transmitted signal to produce a subtraction signal; and a first subtractor designed to subtract the subtraction signal from the first equalized received radio signal. [19] Receiver according to claim 18, further comprising: at least one further receiving branch arranged between the lowest receiving branch and the highest receiving branch, wherein the receiving branch has at least one further receiving branch: an equalizer designed to equalize a received radio signal in order to produce an equalized received radio signal; a filter designed to filter a resynthesized transmit signal from a preceding receive branch to produce a subtraction signal; a subtractor designed to subtract the subtraction signal from the equalized radio receive signal in order to produce a subtracted equalized radio receive signal; and a resynthesizer designed to resynthesize a transmit signal from the subtracted equalized receive radio signal in order to produce a resynthesized transmit signal. [20] Receiver according to claim 18, further comprising: several cascaded receiving branches arranged between the lowest receiving branch and the highest receiving branch, each of the several cascaded receiving branches having: an equalizer designed to equalize a received radio signal in order to produce an equalized received radio signal; a filter designed to filter a resynthesized transmit signal from a preceding receive branch to produce a subtraction signal; and a subtractor designed to subtract the subtraction signal from the equalized received signal. [21] Recipient according to one of claims 19 or 20, wherein the at least one other receiving branch or each of the several cascaded receiving branches has a resynthesizer designed to resynthesize a transmit signal from a linearly or non-linearly equalized received radio signal of the receiving branch in order to produce a resynthesized transmit signal; where optionally each filter represents a residual multipath response, which is given by a cascade of the channel and the corresponding equalizer minus a correctly delayed Dirac delta impulse response. [22] Recipient according to any one of claims 18 to 21, where each subtraction signal represents a multipath interference contained in a corresponding equalized signal; where optionally each subtraction signal represents a neighboring cell interference contained in a corresponding equalized signal. [23] Recipient according to any one of claims 18 to 21, wherein at least one of the receiving branches has a resynthesizer designed to resynthesize a transmit signal from an equalized received radio signal by taking into account parts of the equalized received radio signal that meet a reliability criterion; where optionally parts of the equalized received radio signal are known parts of the equalized received radio signal; where optionally parts of the equalized received radio signal are pilot symbols. [24] Mobile radio communication terminal, comprising: a receiver according to any one of claims 18 to 23; and an application processor that is coupled with the receiver.

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