EP4364365A1

EP4364365A1 - A method for determining receiver weights

Info

Publication number: EP4364365A1
Application number: EP21739337.0A
Authority: EP
Inventors: Sairamesh Nammi; Namir Lidian
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2021-07-01
Filing date: 2021-07-01
Publication date: 2024-05-08
Also published as: WO2023274538A1

Abstract

Disclosed herein is a method of a network node for determining receiver weights comprising obtaining scheduling information from neighboring network nodes or sectors pertaining to interfering wireless devices associated with the neighboring network nodes or sectors; determining, based on the scheduling information, whether a resource block received from at least one serving wireless device and comprising one or more device specific reference signals is subjected to partial interference; calculating a first covariance value for a first symbol subjected to interference comprising a first device specific reference signal and comprised in the resource block; calculating a second covariance value for a second symbol not subjected to interference and comprising a second device specific reference signal and comprised in the resource block; determining a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

Description

A METHOD FOR DETERMINING RECEIVER WEIGHTS

Technical Field

The present invention relates generally to the field of wireless communication. More particularly, it relates to determining receiver weights based on interference detection.

Background

To meet the huge demand for data centric applications, currently 3GPP is discussing to extend the 4^th generation (4G) standards to 5^th generation (5G, also known as New Radio (NR) access). The following are requirements for 5G networks:

• Data rates of several tens of megabits per second should be supported for tens of thousands of users

• 1 gigabit per second to be offered simultaneously to dozens of workers on the same office floor

• Several hundreds of thousands of simultaneous connections to be supported for massive sensor deployments

• Spectral efficiency should be significantly enhanced compared to 4G

• Coverage should be improved

• Signaling efficiency should be enhanced

• Latency should be reduced significantly compared to Long Term Evolution (LTE)

It is well known that Multiple Input Multiple Output (MIMO) systems can significantly increase the data carrying capacity of wireless communication systems. Because of this, MIMO is an integral part of the 3rd and 4th generation wireless systems. 5G systems will typically also employ a type of MIMO system known as massive MIMO systems (mMIMO) which typically comprise hundreds of antennas at the Transmitter side and/or Receiver side. Typically, with (Nt,Nr), where Nt denotes the number of transmit antennas and Nr denotes the receive antennas, the peak data rate multiplies with a factor of Nt over single antenna systems in rich scattering environments.

Antenna, or layer mapping in general, may typically be described as a mapping from the output of the data modulation to the different antenna ports. The input to the antenna mapping thus consists of the modulation symbols (Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), 64QAM, and 256QAM corresponding to the transport block. The output of the antenna mapping is a set of symbols for each antenna port. The symbols of each antenna port are subsequently applied to an Orthogonal Frequency Demodulation (OFDM) modulator - that is, mapped to the basic OFDM time-frequency grid corresponding to that antenna port.

In 5G, when uplink is to be established between a wireless communication device and a network node, the wireless communication device typically transmits a Sounding Reference Signal (SRS) to the network node. From the sounding reference signals, the network node computes the channel estimates then computes the parameters needed for Channel State Information (CSI) determination. The determination step consists for example of computing the Channel Quality Indicator (CQI) and/or modulation and coding scheme (MCS), Transmit Precoding Matrix Index (TPMI), Transmit Rank Information (TRI) etc.

Once the network node determines the parameters needed for scheduling uplink data, it will inform the wireless communication device of these parameters through a grant channel also called Physical Downlink Control Channel (PDCCH).

Once the wireless communication device receives this grant information, the device will typically transmit the uplink data using a Physical Uplink Shared Channel (PUSCH).

Receivers are used to decode the transmitted signal. The receiver typically estimates the noise and co-channel interference from the received signal in order to determine suitable receiver weights. Estimating noise and co-channel interference is typically done by using some form of covariance estimation. In conventional communication systems such as Long Term Evolution (LTE), it can typically always be assumed that all received symbols in a resource block are subjected to interference, which leads to a straight forward estimation of covariance and hence determination of receiver weights. However, in NR systems, the network nodes are not obliged to schedule traffic over an entire resource block. Assuming that the entire resource block experiences the same interference, when in reality it does not, will typically lead to an erroneous determination of receiver weights, which in turn may lead to degraded throughput and system capacity due to detection of non-existing bits.

Therefore, there is a need for a method and apparatus for calculating receiver weights in network scenarios where the interference over a resource block may vary across the symbols.

Summary

It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

It is an object of some embodiments to obviate or at least mitigate at least some of the above disadvantages and to provide methods, apparatuses and computer program product for determining accurate receiver weights.

According to a first aspect, this is achieved by a method of a network node for determining receiver weights. The network node operates in a wireless communication network and comprises a receiver for receiving transmissions from at least one serving wireless device. The method comprises obtaining scheduling information from one or more neighboring network nodes or sectors, the scheduling information pertaining to one or more interfering wireless devices associated with the one or more neighboring network nodes or sectors. The method also comprises determining, based on the obtained scheduling information, whether a resource block received from the at least one serving wireless device and comprising one or more device specific reference signals is subjected to partial interference from the one or more the interfering wireless devices. When it is determined that the received resource block is subjected to partial interference, the method comprises calculating a first covariance value for a first symbol comprising a first device specific reference signal, where the first symbol is comprised in the resource block. The first symbol is subjected to interference from the one or more interfering wireless devices. The method also comprises calculating a second covariance value for a second symbol comprising a second device specific reference signal. The second symbol is in the resource block. The second symbol is not subjected to interference from the one or more interfering wireless devices. The method also comprises determining a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

Hence, two sets of receiver weights are determined, where one set is calculated based on experienced interference, and the other set is calculated based on non- experienced interreference.

In some embodiments, the method may further comprise applying the first set of receiver weights for detecting a first set of symbols comprised in the resource block, wherein the first set of symbols is subjected to interference from the one or more interfering wireless devices and comprises the first symbol. The method may also comprise applying the second set of receiver weights for detecting a second set of symbols comprised in the resource block, wherein the second set of symbols is not subjected to interference from the one or more wireless devices and comprises the second symbol.

Hence, more accurate symbol detection is enabled since symbols experiencing interference will be detected using transmission weights having been calculated with the interference taken into consideration, whereas symbols not experiencing interference will be detected using transmission weights having been calculated without taking interference into consideration. The risk of detection of non-exiting bits is thus decreased. This in turn may lead to increased throughput and overall enhancement of system capacity in the wireless network. It may also lead to power savings.

In some embodiments, the method may further comprise that the first covariance value is calculated based on a received signal, an estimated channel matrix and the first symbol; and the second covariance value is calculated based on the received signal, the estimated channel matrix and the second symbol.

In some embodiments, the device specific reference signal is a demodulation reference signal, DMRS. In some embodiments, the second device specific reference signal is a copy of the first device specific reference signal, and wherein the first and second device specific reference signals occupy the same frequency.

In some embodiments, the first and second device specific reference signals are received on a same antenna port.

In some embodiments, the method may further comprise determining whether the resource block comprises a third device specific reference signal. The method may further comprise determining whether a third symbol comprising the third device specific reference signal is subjected to interference. The method may further comprise calculating the first covariance value for the first and third symbols by accumulating the first and third device specific reference signals, when it is determined that the third symbol is subjected to interference from the one or more interfering wireless devices.

Or, in some embodiments, the method may comprise calculating the second covariance value for the second and third symbols by accumulating the second and third device specific reference signals, when it is determined that the third symbol is not subjected to interference from the one or more interfering wireless devices.

In some embodiments, obtaining scheduling information from one or more neighboring network nodes or sectors comprises obtaining at least one of time domain and frequency domain resource element allocation associated with the one or more neighboring network nodes for every received resource block.

In some embodiments, obtaining scheduling information from one or more neighboring network nodes or sectors, comprises obtaining a bit map from the one or more neighboring network nodes or sectors for each symbol in the received resource block, the bit map indicating whether the one or more neighboring network nodes has scheduled traffic on each symbol in the resource block.

A second aspect is a computer program product comprising a non-transitory computer readable medium. The non-transitory computer readable medium has stored there on a computer program comprising program instructions. The computer program is configured to be loadable into a data-processing unit comprising a processor and a memory associated with or integral to the data-processing unit. When loaded into the data-processing unit, the computer program is configured to be stored in the memory. The computer program, when loaded into and run by the processor is configured to cause the processor to execute method steps according to the first aspect.

A third aspect is an apparatus for a network node for determining receiver weights. The network node operating in a wireless communication network and comprising a receiver for receiving transmissions from at least one serving wireless device. The apparatus comprising controlling circuitry configured to cause obtainment of scheduling information from one or more neighboring network nodes or sectors. The scheduling information pertaining to one or more interfering wireless devices associated with the one more neighboring network nodes or sectors. The controlling circuitry is configured to cause determination of, based on the obtained scheduling information, whether a resource block received from the at least one serving wireless device and comprising one or more device specific reference signals is subjected to partial interference from the one or more interfering wireless devices. When it is determined that the received resource block is subjected to partial interference, the controlling circuitry is configured to cause calculation of a first covariance value for a first symbol comprising a first device specific reference signal and comprised in the resource block. The first symbol is subjected to interference from the one or more interfering wireless devices. The controlling circuitry is configured to cause calculation of a second covariance value for a second symbol comprising a second device specific reference signal and comprised in the resource block. The second symbol is not subjected to interference from the one or more interfering wireless devices. The controlling circuitry is configured to cause determination of a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

A fourth aspect is a network node, comprising the apparatus according to the third aspect

In some embodiments, the third and fourth aspects may additionally have features identical with or corresponding to any of the various features as explained above for the first aspect. Brief Description of the Drawings

Further objects, features and advantages will appear from the following detailed description of embodiments, with reference being made to the accompanying drawings, in which:

Fig. la-ld is a block diagram illustrating an example resource block according to some embodiments;

Fig. 2 is a flowchart illustrating example method steps according to some embodiments;

Fig. 3 is a block diagram illustrating an example resource block according to some embodiments;

Fig. 4 is a block diagram illustrating an example resource block according to some embodiments;

Fig. 5 is a flowchart illustrating example method steps according to some embodiments;

Fig. 6 is a schematic drawing illustrating an example network scenario according to some embodiments;

Fig. 7 is a block diagram illustrating an example computer program product according to some embodiments; and

Fig. 8 is a block diagram illustrating an example apparatus according to some embodiments.

Detailed Description

In the following, embodiments will be described where accurate determination of receiver weights is enabled by taking into consideration that a resource block may be subjected to partial interference.

Furthermore, in this disclosure the term network node is used. A network node is typically an entity deployed in, or in association with a wireless communication network for controlling network traffic and serving one or more wireless communication devices. A network node as referred to herein may e.g. be a base station, a controlling node, a gNB, an eNB, a Radio Access Network (RAN) node, an Access Point (AP), etc. The various terms for a network node may hence be used interchangeably in this disclosure unless otherwise explicitly stated.

Furthermore, in this disclosure the term wireless communication device is used. A wireless communication device is typically an entity deployed in, or in association with a wireless communication network. The wireless communication device is typically served by a network node operating in the wireless communication network. A wireless communication devices as referred to herein may e.g. be a stationary device, a mobile device, a smart phone, a mobile phone, a lap top, a computer, a hand set, a tablet, a drone, an autonomous vehicle, a User Equipment (UE), or any other device capable of wireless communication in a wireless communication network. The various terms for a wireless communication device may be used interchangeably in this disclosure unless otherwise explicitly stated.

When establishing and maintaining communication within a communication network, uplink reference signals are typically transmitted from a serving wireless device to its dedicated network node.

Uplink reference signals are predefined signals occupying specific resource elements within the uplink time-frequency grid. In e.g. 5G systems there are two types of uplink reference signals that are transmitted in different ways and used for different purposes by the gNB:

• Sounding reference signals (SRS): These reference signals are specifically intended to be used by e.g. the gNB to acquire channel-state information (CSI) and beam specific information. In 5G systems, the SRS is UE specific so it can have a significantly lower time/frequency density.

• Demodulation reference signals (DM-RS): These reference signals are UE specific and specifically intended to be used by the gNB for channel estimation of the data channel between the gNB and the UE. The label “UE-specific” relates to the fact that each demodulation reference signal is received from a specific UE and intended for channel estimation by the gNB for that specific UE. That specific reference signal is then only transmitted within the resource blocks assigned for data traffic channel transmission from and to that specific UE. Since in general the data is pre- coded, the DM-RS is also pre-coded with the same precoding as that of data. In general, it is important for a UE to consider certain assumptions in terms of the relationship between the radio channels experienced by different downlink transmissions. E.g. the UE needs to understand what reference signal(s) should be used for channel estimation for a certain downlink transmission and determine relevant channel-state information required for scheduling and link-adaptation purposes.

For the same reason, the concept of antenna port is used in 5GNR and it follows the same principles as antenna ports in 4G LTE. The term “antenna port” is a logical concept related to the physical layer (LI), and not the physical antenna like the RF antenna which is visible on e.g. a base station tower.

According to 3GPP specification definition, an antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed.

Multiple antenna port signals can be transmitted on a single transmit/receiver antenna and correspondingly, a single antenna port can be spread across multiple transmit/receiver antennas.

E.g. if 4 antenna ports are used, it allows for a maximum of 4 layers and 4 DMRS signals.

If reference symbols (i.e. the symbols comprising the device specific reference signals) within a resource block are transmitted for a single antenna port 0, then the same reference symbols are code multiplexed and transmitted on antenna port 1. Similarly, for ports 2 and 3 the same resource elements are used for transmitting DMRS reference symbols. However, they are code multiplexed as in port 0 and 1. Note that the resource elements that are used for rank 3 and 4 (ports 2 and 3) are orthogonal in frequency to those of port 0 and 1.

Typically, the DMRS is front loaded in the resource block (i.e. it is located at a symbol in the beginning of the resource block). However, the NR specification allows additional DMRS in later part of the resource blocks. These additional DMRS may for example be for improving the channel estimation quality at the receiver, or for high mobility UEs, or for higher modulations etc. The 5G specification provides up to 3 DMRS in addition to the front loaded DMRS in a resource block. Conventionally Minimum Mean Square Error and Interference Rejection Combiner (MMSE-IRC) receivers are used by the network node to decode the transmitted signal received from a serving UE. A MMSE-IRC receiver typically estimates the noise and co-channel interference from the received signal. In general, to estimate the noise and co-channel interference, the receiver uses covariance estimation. It is common to use the DMRS to estimate covariance. When interfering cells are fully loaded, estimating the covariance from DMRS is straightforward as the network accumulates the front loaded DMRS and additional DMRS (if any) and estimates the covariance based on the DMRS symbols.

E.g. the network node may have received a resource block from the serving UE. The received resource block is illustrated by Fig. la as being a fully loaded resource block 100a (comprising 14 symbols 1-14 and 12 subcarriers 01-012). The resource block 100a comprises a first (front loaded) device specific reference signal (e.g. a DMRS) located at symbol 3 and one additional (i.e. a second) device specific reference signal located at symbol 12.

An interfering wireless device served by a neighboring network node (or belonging to a different sector) may transmit a resource block 100b which interferes with the resource block 100a. The resource block 100b of the interfering device is illustrated in Fig. lb and it has the same characteristics as the resource block 100a of Fig. la. Both resource blocks are fully loaded, and covariance may be estimated by accumulating the first DMRS located at the third symbol and the second DMRS located at the 12^th symbol of the resource block 100a.

In order to calculate the covariance, it may be assumed that the received signal Y in frequency domain may be written as

Y = HiPi*_! + n + H₂P_2X2 where Y 6 C^NrXl corresponds to a received signal vector, and H₁ 6 C^NrXNt describes an overall channel matrix for the serving UE (e.g. the UE associated with the resource block 100a of Fig la). A complex zero-mean Gaussian noise vector ΊP 6 C^NT ^{x 1} is having covariance R_n.

An unknown complex data/symbol vector is denoted by X 6 C ^L (having normalized power E{xx^H } = R_x = / ) corresponding to M-QAM (where M is an integer e.g. 64) constellation. A complex precoder P-L 6 c^NtXNL is selected from a given/known codebook having N_P number of precoders (where PMI = {0,1,.. N_P- 1}) for a given rank £ min{N_r, N_t}.

H₂ 6 C^NrXNt describes an overall channel matrix from the other UE (e.g. the UE associated with the resource block 100b of Fig. lb) interfering with the base station and which is pre-coded with P₂ and sending data X₂ to another base station.

At the first base station receiver, the base station computes the covariance matrix ( R_c ) based on the DMRS symbols of the serving UE as where H_est is the estimated channel matrix of the serving UE, d = [d₁ ; d₂ ] is all of the accumulated DMRS symbols in the resource block (in the example of Fig. la, symbols 3 and 12). H is the matrix transpose.

Once the receiver computes the covariance matrix, it uses this when determining the receiver weights for all the symbols in the resource block. I.e., the same receiver weights are applied on the entire resource block in order to detect all of the symbols in the resource block.

However, unlike 4G LTE, where the base station schedules the whole resource block (all the symbols) for data transmission, 5G NR can schedule only a few symbols in a resource block for data transmission. In addition, 5G NR supports multiple services such as enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communication (URLLC) etc. This leads to higher demands on throughput and performance of 5G networks than e.g. 4G and LTE, and hence less room for errors.

Compare e.g. Fig. la with Fig. lc. If the serving UE transmits a resource block 100a comprising data and reference signals as illustrated in Fig. la and described above, then the resource block 100a will only experience partial interference if an interfering UE is scheduled by a neighboring base station (e.g. a base station located in a neighboring cell or in a different sector of the same cell as the serving base station) such that it transmits according to resource block 100c in Fig. lc. The interfering UE only transmits data on the symbols 1-7, whereas the symbols 8-9 are left unused. Another example is seen in Fig. Id, where the interfering UE utilize the last 8- 14 symbols in resource block lOOd for uplink transmission.

In the above cases, when an interfering UE is scheduled by a neighboring base station with resource blocks according to Fig. lc and/or Fig. Id, the serving cell being scheduled with transmitting resource blocks according to Fig la, will experience partial interference. If the covariance would be calculated according the conventional method elaborated on above by simply accumulating the device specific reference signals (or the symbols holding the device specific reference signals), it would result in one value for reception weights applied for detecting all of the symbols in the resource block. However, since some of the symbols experience interference, while others do not, the receiver weights when based on the single covariance value will not be optimally calculated and may instead lead to erroneous detection of non-existing bits. This may negatively affect performance of the network and may hence make it more difficult to meet the high demands set for 5G communication.

Figure 2 illustrates an example method 200 for addressing this problem. The method 200 is of a network node for determining receiver weights. The network node operates in a wireless communication network and comprises a receiver for receiving transmissions from at least one serving wireless device.

In some embodiments, the method 200 is of a receiver system for determining receiver weights. The receiver system may be comprised within, or connectable to, a network node.

In step 210, the method comprises obtaining scheduling information from one or more neighboring network nodes or sectors, the scheduling information pertaining to one or more interfering wireless devices associated with the one or more neighboring network nodes or sectors (compare with Fig la, and Figs lb-d).

In step 211 the method comprises determining, based on the obtained scheduling information, whether a resource block received from the at least one serving wireless device and comprising one or more device specific reference signals is subjected to partial interference from the one or more the interfering wireless devices.

When in step 211 it is determined that the received resource block is not subjected to partial interference (N-path out of 211) then the method continues in step 217 with calculating a single covariance value which is used for determining one set of receiver weights used to detect all symbols in the resource block.

When in step 211 it is determined that the received resource block is subjected to partial interference (Y-path out of 211), the method comprises in step 212 calculating a first covariance value for a first symbol comprising a first device specific reference signal and comprised in the resource block (i.e. the first symbol is comprised in the resource block). The first symbol is subjected to interference from the one or more interfering wireless devices.

The method comprises in step 213 calculating a second covariance value for a second symbol comprising a second device specific reference signal comprised in the resource block (i.e. the first and second symbols are comprised in the same resource block). The second symbol is not subjected to interference from the one or more interfering wireless devices.

Then in the following steps 214 and 215 the method comprises determining a first set of receiver weights (step 214) and a second set (step 215) of receiver weights based on the calculated first and second covariance value respectively.

Thus, the method 200 enables calculation of different covariance values and hence the determination of different receiver weights, based on detected interference from other sectors or cells.

This leads to that the receiver weights may be more accurately determined for the symbols they are used for detecting. This in turn leads to less risk of detecting non existing bits, or less risk in resulting in other errors in data reception. Thus, link throughput may be increased as well as improving the overall system capacity. This may in the long run lead to energy savings in the network, as well as increasing the likelihood that the high demands on connectivity in a 5G network are met.

Furthermore, in some embodiments, the method 200 may further continue in step 216 comprising applying the first set of receiver weights for detecting a first set of symbols in the resource block, wherein the first set of symbols is subjected to interference from the one or more interfering wireless devices and comprises the first symbol and applying the second set of receiver weights for detecting a second set of symbols in the resource block, wherein the second set of symbols is not subjected to interference from the one or more wireless devices and comprises the second symbol.

Compare again with e.g. Fig. la and Fig lc. If the serving UE transmits a resource block according to the resource block 100a, and an interfering UE transmits a resource block according to the resource block 100c, then the serving UE experience interference on symbols 1-7 but not on symbols 8-14, and hence the first device specific reference signal (e.g. DMRS) at symbol 3 is subjected to interference, while the second device specific reference signal (e.g. DMRS) at symbol 12 is not. According to the method 200, a first covariance value will be calculated for the first symbol (symbol 3) comprising the first device specific reference signal, and a second covariance value will be calculated for the second symbol (symbol 12) comprising the second device specific reference signal. Based on the first covariance value, a first set of weights will be determined, and based on the second covariance value a second set of weights will be determined.

The first set of weights may be used to detect the symbols 1-7 experiencing interference. The second set of weights may be used to detect the symbols 8-14 not experiencing interference.

In some embodiments, the first and second set of receiver weights are calculated for a first resource block. The first and second set of receiver weights may then be applied to subsequently received resource blocks and symbols, depending on whether the received symbols experience interference or not. E.g., in some embodiments, the first set of receiver weights may be applied in subsequently received resource blocks which experience partial interference for detecting symbols that are determined to experience (or be subjected to) interference. The second set of receiver weights may be applied in subsequently received resource blocks which experience partial interference for detecting symbols that are determined to not experience (not subjected to) interference. In some embodiments, the covariance values and first and second set of weights may be calculated once and then used for all received symbols from a specific serving wireless device during a communication session between the serving wireless device and the network node. The sets of receiver weights may be calculated again whenever a new connection is, or is to be established, between a serving wireless device and the network node. In some embodiments, the first covariance value is calculated based on a received signal, an estimated channel matrix and the first symbol. The second covariance value is calculated based on the received signal, the estimated channel matrix and the second symbol.

Covariance may be determined in many different ways, using many different formulas (one example is provided above, but a skilled person would realize that there are other variants to the formula). In general, covariance is based on a received signal, an estimated channel matrix and the received symbol(s) comprising the reference signal.

E.g. in some embodiments, the first covariance value is calculated according to and the second covariance value is calculated according to where Y corresponds to a received signal vector, H_est is an estimated channel matrix of the at least one serving wireless device, d ₁ is the first symbol comprising the first device specific reference signal, d₂ is the second symbol comprising the second device specific reference signal and H is the matrix transpose. Furthermore, in this disclosure, referral has been made to the term device specific reference signal. Such a signal is unique for each wireless device and is typically used by the serving base station to perform channel estimation.

In some embodiments, the device specific reference signal is a demodulation reference signal, DMRS. In NR, where additional copies of DMRS are allowed in a resource block, the front loaded DMRS is typically copied and repeated at other symbols in the resource block but occupying the same frequency as the front loaded (original) DMRS.

Hence, in some embodiments the second device specific reference signal is a copy of the first device specific reference signal. The first and second device specific reference signals occupy the same frequency. Furthermore, when a resource block comprises more than one device specific reference signals, all of the reference signals are received on the same logical antenna port.

Hence in some embodiments, the first and second device specific reference signals are received on a same antenna port.

Example resource blocks of the serving UE comprising several device specific reference signals are illustrated in Figs. 3 and 4.

Fig. 3 illustrates a resource block 300 from a serving UE comprising a first device specific reference signal located at a first symbol (symbol 3), a second device specific reference signal located at a second symbol (symbol 7) and a third device specific reference signal located at a third symbol (symbol 11).

The method 200 may in some embodiments further comprise additional steps. These steps are described in Fig. 5 by the method 500. The method 500 may hence in some embodiments be incorporated into the method 200. The method 500 may be carried out by a network node comprising a receiver. The method 500 may be carried out by a receiver circuit. The receiver circuit may be comprised in or connectable to a network node.

In step 510 (which may be incorporated into step 211 of the method 200) the method 500 comprises determining a number of device specific reference signals comprised in the resource block. In step 511 (which step may also be incorporated into step 211 of the method 200), the method comprises determining whether the symbols comprising the device specific reference signals are subjected to interference or not. Then in step 512 (which step may be incorporated into step 212 of the method 200) the method comprises accumulating the symbols comprising device specific reference signals determined to be subjected to interference, and calculating a first covariance value based on the accumulated interfered symbols comprising device specific reference signals. In step 513 (which step may be incorporated into step 214 of the method 200), a first set of receiver weights is determined based on the first covariance value.

Then in step 514 (which step may be incorporated into step 213 of the method 200) the method comprises accumulating the symbols comprising device specific reference signals determined not to be subjected to interference, and calculating a second covariance value based on the accumulated non-interfered symbols comprising device specific reference signals. In step 515 (which step may be incorporated into step 215 of the method 200), a second set of receiver weights is determined based on the second covariance value.

Then in step 516 (which step may be incorporated into step 216 of the method 200) the first set of weights is applied to detected symbols experiencing interference.

The second set of weights is applied to detect symbols not experiencing interference.

If, e.g. a resource block comprises three device specific reference signals (such as e.g. the resource block 300 of Fig. 3), the method 500 may be applied to detect the first and second device specific reference signal in step 510.

Then, in step 510 the method 500 comprises determining whether the resource block comprises a third device specific reference signal and determining in step 511 whether a third symbol comprising the third device specific reference signal is subjected to interference.

The method 500 may then continue in step 514 comprising calculating the first covariance value for the first and third device specific reference signal by accumulating the first and third device specific reference signals(it should be noted that the terms “accumulating the device specific reference signals, implicitly means that the symbols comprising the device specific reference signals are accumulated), when it is determined that the third symbol is subjected to interference from the one or more interfering wireless devices (Y-path out of 511).

Or, the method 500 may continue in step 512 comprising calculating the second covariance value for the second and third device specific reference signal by accumulating the second and third device specific reference signals, when it is determined that the third symbol is not subjected to interference from the one or more interfering wireless devices (N-path out of 511).

In some embodiments, the method 500 may comprise in step 515 determining the first set of receiver weights based on the first covariance value. In step 513, the method 500 may comprise determining the second set of receiver weights based on the second covariance value. In step 516, the first and second set of determined receiver weights may be applied to detect the symbols of the resource block. The first set of weights may be applied to detect a first subset of symbols experiencing interference. The second set of weights may be applied to detect a second set of symbols not experiencing interference (the step 516 may e.g. be incorporated into the step 216 of the method 200).

E.g., in an example where the serving UE transmits according to resource block 300 and an interfering UE is scheduled for uplink according to resource block 100c. Then the device specific reference signals located at symbols 3 and 7 in resource block 300 of Fig. 3 will experience interference from symbols 1-7 of resource block 100c of Fig. lc. A first covariance value is thus calculated for the first and second symbols comprising the device specific reference signals and experiencing interference by accumulating the device specific reference signals comprised in symbol 3 and 7 in resource block 300.

The first covariance value may e.g. be calculated according to

R_C1 = (Y - H_esf[d₁rf₂]) * (Y - H_est[d₁d₂])^H

Since the third device specific reference signal at symbol 11 in resource block 300 does not experience any interference a second covariance value is calculated for the third symbol comprising the third device specific reference signal.

The second covariance value may e.g. be calculated according to

R_c2 = (Y - H_estd₃) * (Y - H _estd₃)^H

The first covariance value is used for determining a first set of receiver weights for detecting symbols 1-7. The second covariance value is used for determining a second set of receiver weights for detecting symbols 8-14.

If, in some embodiments, the interfering UE instead is scheduled for uplink according to the resource block lOOd of Fig. Id, then it may be determined that the third symbol (symbol 11 in this example) comprising the third device specific reference signal in resource block 300 of Fig. 3 experience interference, while the first and second device specific reference signals located at symbols 3 and 7 respectively do not. A first covariance value may then be calculated for the first and second symbols comprising the first and second device specific reference signals by accumulating them. A second covariance value may be calculated for the third symbol comprising the third device specific reference signal. A first set of receiver weights may be determined based on the first covariance value. A second set of receiver weights may be determined based on the second covariance value. The first set of receiver weights may be used for detecting symbols 1-7 not experiencing interference. The second set of receiver weights may be used for detecting symbols 8-14 experiencing interference.

Furthermore, in some embodiments, the serving UE may provide four device specific reference signals in a resource block. As is illustrated in Fig. 4. The resource block 400 comprises a first device specific reference signal at symbol 3 (first symbol), a second device specific reference signal at symbol 5 (second symbol), a third device specific reference signal at symbol 8 (third symbol) and a fourth device specific reference signal at symbol 11 (fourth symbol).

If again the interfering UE utilize the resource block 100c of Fig. lc, then the first and second symbols comprising the first and second device specific reference signals of resource block 400 experience interference. The third and fourth symbols comprising the third and fourth device specific reference signals of resource block 400 do not experience interference.

Hence when the method 200 and/or the method 500 is applied, a first covariance value will be calculated by accumulating the first symbol comprising the first device specific reference signal and the second symbol comprising the second device specific reference signals (step 512). A second covariance value will be calculated by accumulating the third symbol comprising the third device specific reference signal and the fourth symbol comprising the fourth device specific reference signals (step 514).

The first covariance value will be used for determining a first set of receiver weights (step 513) and the second covariance value will be used for determining a second set of receiver weights (step 515). The first set of receiver weights may e.g. be applied/used for detecting symbols 1-7 in the resource block 400(step 516), which symbols are experiencing interference. The second set of receiver weights will be applied/used for detecting symbols 8-14 in resource block 400 (step 516), which symbols are not experiencing interference.

It should be noted that in some embodiments, the first and fourth device specific reference signals comprised in resource block 400 experience interference, while the second and third device specific reference signals do not. Or, in some embodiments, the first and the third device specific reference signal may experience interference, while the second and the fourth does not, or vice versa.

In such embodiments, the method 200 and/or 500 (on their own or as a combination) will allow for accumulating the symbols comprising reference signals which experience interference and basing a first covariance value on this accumulation. The methods 200 and/or 500 will also allow for accumulating the symbols comprising reference signals which does not experience interference and basing a second covariance value on this accumulation. The determined first and second set of receiver weights (based on the first and second covariance value respectively) will then respectively be used to detect the symbols experiencing interference and the symbols not experiencing interference in the resource block (and/or in subsequently received resource blocks).

Fig. 6 illustrates a network scenario according to some embodiments. In Fig.6 three network cells 610, 620, 630 are illustrated. In some embodiments, the three network cells 610, 620, 630 are not individual cells, but may instead be three sectors within a same network cell. It may further be envisioned that the three cells 610, 620, 630 may be more or less overlapping. E.g. the first network cell 610 may be a macro cell, whereas the second 620 and third 630 network cells are pico and/or femto cells deployed completely within, or at the borders, of the macro network cell 610.

Each network cell (or sector) comprises a network node, e.g. a base station. Hence the first network cell 610 is served by a first base station 611. The second network cell 620 is served by a second base station 621. The third network cell 630 is served by a third base station 631.

The first base station 611 is communicating with and scheduling a first serving wireless device (e.g. a UE) 612. The second base station 621 is communicating with and scheduling a second UE 622. The third base 631 station is communicating with and scheduling a third UE 632.

To simplify, the first base station 611 may correspond to the network node described in conjunction with any of the previous Figs 1-5. and carrying out any of the methods 200 and 500 described in conjunction with Figs. 2 and 5. The first serving UE 612 may correspond to the serving wireless device described in conjunction with any of the previous figures 1-5. The second and third base station 621, 631 may correspond to one or more neighboring network nodes described in conjunction with any of the figures 1-5. The second and third UE may correspond to the one or more interfering wireless devices described in conjunction with any of the Figs, 1-5.

Hence the first network node 611 may determine receiver weights. The first network node 611 operates in a wireless communication network and comprises a receiver for receiving transmissions from at least one serving wireless device 612.

The first network node 611 may obtain scheduling information from one or more neighboring network nodes 621, 631 or sectors 620, 630. The scheduling information pertains to one or more interfering wireless devices 622, 632 associated with the one or more neighboring network nodes 621, 631 or sectors 620, 630.

The first network node 611 may then determine, based on the obtained scheduling information, whether a resource block (e.g. any of the resource blocks 100a, 300, 400 described in conjunction with Figs la-d, 3 and 4) received from the at least one serving wireless device 612 and comprising one or more device specific reference signals is subjected to partial interference from the one or more the interfering wireless devices 622, 632.

When it is determined that the received resource block is subjected to partial interference, the first network node 611 may calculate a first covariance value for a first symbol comprising a first device specific reference signal and comprised in the resource block. The first symbol is subjected to interference from the one or more interfering wireless devices 622, 632.

The first network node 611 may further calculate a second covariance value for a second symbol comprising a second device specific reference signal and comprised in the resource block. The second symbol is not subjected to interference from the one or more interfering wireless devices 622, 632.

The first network node 611 may further determine a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

In some embodiments, the first network node 611 may apply the first set of receiver weights for detecting a first set of symbols in the resource block. The first set of symbols is subjected to interference from the one or more interfering wireless devices 622, 632 and comprises the first symbol.

The first network node 611 may further apply the second set of receiver weights for detecting a second set of symbols in the resource block. The second set of symbols is not subjected to interference from the one or more wireless devices 622, 632 and comprises the second symbol.

In some embodiments, the first network 611 node may apply the determined first set of receiver weights for detecting symbols in subsequently received resource blocks that are determined to be subjected to interference.

In some embodiments, the first network 611 node may apply the determined second set of receiver weights for detecting symbols in subsequently received resource blocks that are determined to not be subjected to interference.

In some embodiments, the first network node 611 may apply the determined first and second set of receiver weights for all received symbols during a communication session with the serving wireless device 612.

It should be noted that either of the illustrated network nodes 611, 621, 631 in Fig.6 may carry out any of the method 200 and 500 as described herein and/or be the neighboring network node. Similarly, either of the wireless devices 612, 622, 632 may be the at least one serving wireless device, and/or the one or more interfering device.

Hence, although the resource blocks 100a, 300, 400 as shown in Fig. la, 3 and 4 has been used as an example of a resource block of the serving wireless device, also the resource blocks 100c, lOOd shown in Figs. 100c and lOOd may be resource blocks of the serving wireless device. Similarly, the one or more interfering wireless device may be scheduled with resource blocks that corresponds to any of the resource blocks described in the Figs la-d, 3 and 4.

Hence, embodiments may be envisioned where the serving UE is only utilizing part of a resource block, whereas interfering UEs utilize a full (or partly loaded) resource block. In an example where the serving UE utilize part of a resource block (e.g. such as illustrated in Fig lc), and an interfering UE is scheduled on a full resource block, a covariance value may be determined only for the symbols experiencing interference.

In Fig. 6, the first network node 611 is illustrated to obtain scheduling information from the neighboring (second and third) network nodes 621 and 631 by means of signaling arrows 640 and 650. Furthermore, the second 621 and third 631 network nodes may exchange scheduling information with each other as illustrated by signaling arrow 660, as well as obtain scheduling information from the first network node 611 through signaling arrows 640, 650.

In order to be able to obtain the scheduling information, various embodiments are envisioned.

E.g., in some embodiments, obtaining scheduling information from one or more neighboring network nodes or sectors comprises obtaining at least one of a time domain and frequency domain resource element allocation associated with the one or more neighboring network nodes for every received resource block. Based on this the network node may determine whether a symbol in a resource block is scheduled for communication or not.

It should be noted that a resource block (sometimes also denoted as a transmission slot) typically carries a number of symbols (usually 7 or 14) spread over a number of subcarriers (usually 12). A resource element is the smallest part of a resource block and carries data or reference signals. A resource block comprising 14 symbols and 12 subcarriers holds 14*12 resource elements. Hence a symbol can be split into 12 resource elements, one for each subcarrier.

In some embodiments, obtaining scheduling information from one or more neighboring network nodes or sectors may alternatively or additionally comprise obtaining a bit map from the one or more neighboring network nodes for each symbol in the received resource block, the bit map indicating whether the one or more neighboring network nodes has scheduled traffic on a symbol in the resource block.

The bit map may e.g. be set to 1 for each scheduled symbol in the resource block, and 0 for each unscheduled symbol in the resource block The methods 200 and 500, on their own or combined, may be implemented by means of a computer program. Fig. 7 illustrates a computer program product according to some embodiments and comprising a (which may be non-transitory) computer readable medium 700. The (non-transitory) computer readable medium 700 has stored thereon a computer program comprising program instructions. The computer program is configured to be loadable into a data-processing unit 710, comprising a processor (PROC) 720 and a memory (MEM) 730 associated with or integral to the data- processing unit 710.

When loaded into the data-processing unit 710, the computer program is configured to be stored in the memory 730, wherein the computer program, when loaded into and run by the processor 720 is configured to cause the processor 720 to execute method steps described for methods 200 and/or 500 and any of the described embodiments associated with these methods.

Fig. 8 illustrates an apparatus 800 for a network node for determining receiver weights. The network node operating in a wireless communication network and comprising a receiver for receiving transmissions from at least one serving wireless device.

The apparatus 800 may e.g. be comprised in any of the network nodes described in conjunction with Figs. 1-7. The apparatus 800 may further be configured to carry out, or execute, one or more of the method steps described for the methods 200 and/or 500 described in conjunction with Figs. 2 and 5.

In some embodiments, the apparatus 800 is of a receiver assembly or a receiver circuit. The receiver assembly or receiver circuit may be configured to be comprised in, or connected to, a network node.

The apparatus 800 comprises a receiving circuit (RX/TX) 820. The receiving circuit 820 may in some embodiments be the receiver comprised in the network node. The receiving circuit 820 may further comprise a transceiver, and hence act as both a receiver and a transmitter. The receiving circuit 820 may comprise multiple antennas in an antenna array. The receiving circuit 820 may further comprise one or more logical antenna ports.

The receiving circuit may in some embodiments be a MMSE-IRC receiver. In some embodiments, the receiving circuit may be any type of receiver utilizing calculation of covariance in order to determine suitable receiver weights.

The apparatus 800 further comprises a controlling circuitry (CNTR) 810. The controlling circuitry 810 may e.g. be a processor. The receiving circuitry 820 may further be comprised in the controlling circuitry as an integrated circuit.

The controlling circuitry (CNTR) 810 is configured to cause obtainment of scheduling information from one or more neighboring network nodes or sectors, the scheduling information pertaining to one or more interfering wireless devices associated with the one more neighboring network nodes or sectors.

To this end the controlling circuitry 810 may comprise a scheduling circuitry configured to evaluate the obtained scheduling information.

The controlling circuitry 810 is configured to cause determination of, based on the obtained scheduling information, whether a resource block received from the at least one serving wireless device and comprising one or more device specific reference signals is subjected to partial interference from the one or more interfering wireless devices.

To this end, the controlling circuitry 810 may comprise a determining circuitry (DET) 812 configured to determine (possibly in collaboration with the scheduling circuitry 811) whether the received resource block is subjected to partial interference.

When it is determined that the received resource block is subjected to partial interference, the controlling circuitry 810 is configured to cause calculation of a first covariance value for a first symbol comprising a first device specific reference signal and comprised in the resource block, wherein the first symbol is subjected to interference from the one or more interfering wireless devices; and cause calculation of a second covariance value for a second symbol comprising a second device specific reference signal and comprised in the resource block, wherein the second symbol is not subjected to interference from the one or more interfering wireless devices. To this end, the controlling circuitry 810 may comprise a calculating circuitry (CALC) 813 configured to calculate covariance values based on the received symbols comprising the device specific reference signals.

The controlling circuitry 810 is configured to cause determination of a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

The calculating circuitry 813 may e.g. be configured to determine the receiver weights based on the calculated covariance value.

In some embodiments, controlling circuitry 810 is further configured to cause application of the first set of receiver weights for detecting a first set of symbols in the resource block, wherein the first set of symbols is subjected to interference from the one or more interfering wireless devices and comprises the first symbol, and cause application of the second set of receiver weights for detecting a second set of symbols in the resource block, wherein the second set of symbols is not subjected to interference from the one or more interfering wireless devices and comprises the second symbol.

The receiving circuitry 820 may e.g. be configured to apply the determined first and second set of receiver weights respectively for detecting the first set of symbols subjected to interference from the one or more interfering wireless device and for detecting the second set of symbols not subjected to interference from the one or more interfering wireless devices.

In some embodiments, the first covariance value is calculated (e.g. by the calculating circuitry 813) based on a received signal, an estimated channel matrix and the first symbol. The second covariance value is calculated (e.g. by the calculating circuitry 813) based on the received signal, the estimated channel matrix and the second symbol.

In some embodiments, the device specific reference signal is a demodulation reference signal, DMRS.

In some embodiments, the second device specific reference signal is a copy of the first device specific reference signal, and the first and second device specific reference signals occupy the same frequency. In some embodiments, the first and second device specific reference signals are received on a same antenna port. The first and second device specific reference signals may e.g. be received at one of the logical antenna ports comprised in (or associated with) the receiving circuitry 820.

In some embodiments, the controlling circuitry 810 is further configured to cause determination of whether the resource block comprises a third device specific reference signal (e.g. by causing the determining circuitry 812 to determine).

The controlling circuitry 810 may further be configured to cause determination of whether a third symbol comprising the third device specific reference signal is subjected to interference from the one or more interfering wireless devices.

The controlling circuitry 810 may e.g. cause the scheduler to analyse based on obtained scheduling information whether the third device specific reference signal is subjected to interference from the one or more interfering wireless devices.

The controlling circuitry may further be configured to cause calculation of the first covariance value for the first and third symbols comprising the first and third device specific reference signal by accumulating the first and third device specific reference signals, when it is determined that the third symbol is subjected to interference from the one or more interfering wireless devices, or cause calculation of the second covariance value for the second and third symbols comprising the second and third device specific reference signal by accumulating the second and third device specific reference signals, when it is determined that the third symbol is not subjected to interference from the one or more wireless devices.

The controlling circuitry may e.g. cause the calculating circuitry 813 (possibly in cooperation with the scheduling circuitry 811) to calculate the first and second covariance value.

In some embodiments, the controlling circuitry 810 is configured to cause obtainment of scheduling information (e.g. by causing the scheduling circuitry 811, possibly in cooperation with the receiving circuitry 820 to obtain) from one or more neighboring network nodes or sectors by being configured to cause obtainment of at least one of time domain and frequency domain resource element allocation associated with the one or more neighboring network node or sectors for every received resource block.

In some embodiments, the controlling circuitry 810 is configured to cause obtainment of scheduling information (e.g. by causing the scheduling circuitry 811, possibly in cooperation with the receiving circuitry 820 to obtain) from one or more neighboring network nodes or sectors by being configured to cause obtainment of a bit map from the one or more neighboring network nodes or sectors for each symbol in the received resource block, the bit map indicating whether the one or more neighboring network nodes or sectors has scheduled traffic on each symbol in the resource block.

As noted above, the apparatus 800 may be comprised in a network node. A network node comprising the apparatus 800 may carry out any of the embodiments described herein.

In some embodiments, the apparatus 800 may be of a receiving system/receiver assembly/receiver circuit (the terms may be used interchangeably), where the receiving system is configured to determine receiver weights by applying any of the method 200 and 500 and/or the embodiments described herein. The apparatus 800 of the receiving system may be operably connected to (i.e. it can be connected to but also disconnected and removed from), or comprised in, a network node.

The described embodiments and their equivalents may be realized in software or hardware or a combination thereof. They may be performed by general-purpose circuits associated with or integral to a communication device, such as digital signal processors (DSP), central processing units (CPU), co-processor units, field- programmable gate arrays (FPGA) or other programmable hardware, or by specialized circuits such as for example application-specific integrated circuits (ASIC). All such forms are contemplated to be within the scope of this disclosure.

Embodiments may appear within an electronic apparatus (such as a wireless communication device) comprising circuitry/logic or performing methods according to any of the embodiments. The electronic apparatus may, for example, be a portable or handheld mobile radio communication equipment, a mobile radio terminal, a mobile telephone, a base station, a base station controller, a pager, a communicator, an electronic organizer, a smartphone, a computer, a notebook, a USB-stick, a plug-in card, an embedded drive, or a mobile gaming device.

According to some embodiments, a computer program product comprises a computer readable medium such as, for example, a diskette or a CD-ROM. The computer readable medium may have stored thereon a computer program comprising program instructions. The computer program may be loadable into a data-processing unit, which may, for example, be comprised in a mobile terminal or network node.

When loaded into the data-processing unit, the computer program may be stored in a memory associated with or integral to the data-processing unit. According to some embodiments, the computer program may, when loaded into and run by the data- processing unit, cause the data-processing unit to execute method steps according to, for example, the methods shown in any of the Figures 2 and/or 5.

Reference has been made herein to various embodiments. However, a person skilled in the art would recognize numerous variations to the described embodiments that would still fall within the scope of the claims. For example, the method embodiments described herein describes example methods through method steps being performed in a certain order. However, it is recognized that these sequences of events may take place in another order without departing from the scope of the claims. Furthermore, some method steps may be performed in parallel even though they have been described as being performed in sequence.

In the same manner, it should be noted that in the description of embodiments, the partition of functional blocks into particular units is by no means limiting.

Contrarily, these partitions are merely examples. Functional blocks described herein as one unit may be split into two or more units. In the same manner, functional blocks that are described herein as being implemented as two or more units may be implemented as a single unit without departing from the scope of the claims.

Hence, it should be understood that the details of the described embodiments are merely for illustrative purpose and by no means limiting. Instead, all variations that fall within the range of the claims are intended to be embraced therein.

Claims

1. A method (200, 500) of a network node for determining receiver weights, the network node operating in a wireless communication network and comprising a receiver for receiving transmissions from at least one serving wireless device, the method comprising:

- obtaining (210) scheduling information from one or more neighboring network nodes or sectors, the scheduling information pertaining to one or more interfering wireless devices associated with the one or more neighboring network nodes or sectors;

- determining (211, 510, 511) based on the obtained scheduling information, whether a resource block received from the at least one serving wireless device and comprising one or more device specific reference signals is subjected to partial interference from the one or more the interfering wireless devices; wherein, when it is determined that the received resource block is subjected to partial interference, the method comprises

- calculating (212, 514) a first covariance value for a first symbol comprising a first device specific reference signal and comprised in the resource block, wherein the first symbol is subjected to interference from the one or more interfering wireless devices;

- calculating (213, 512) a second covariance value for a second symbol comprising a second device specific reference signal and comprised in the resource block, wherein the second symbol is not subjected to interference from the one or more interfering wireless devices; and

- determining (214, 215, 513, 515) a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

2. The method according claim 1, further comprising:

- applying (216, 516) the first set of receiver weights for detecting a first set of symbols comprised in the resource block, wherein the first set of symbols is subjected to interference from the one or more interfering wireless devices and comprises the first symbol; and

- applying (216, 516) the second set of receiver weights for detecting a second set of symbols comprised in the resource block, wherein the second set of symbols is not subjected to interference from the one or more wireless devices and comprises the second symbol.

3. The method according to any of the previous claims 1-2, wherein the first covariance value is calculated based on a received signal, an estimated channel matrix and the first symbol; and the second covariance value is calculated based on the received signal, the estimated channel matrix and the second symbol.

4. The method according to any of the previous claims 1-3, wherein the device specific reference signal is a demodulation reference signal, DMRS.

5. The method according to any of the previous claims 1-4, wherein the second device specific reference signal is a copy of the first device specific reference signal, and wherein the first and second device specific reference signals occupy the same frequency.

6. The method according to any of the previous claims 1-5, wherein the first and second device specific reference signals are received on a same antenna port.

7. The method according to any of the previous claim 1-6, further comprising

- determining (510) whether the resource block comprises a third device specific reference signal;

- determining (211, 511) whether a third symbol comprising the third device specific reference signal is subjected to interference; and

- calculating (212, 514) the first covariance value for the first and third symbols by accumulating the first and third device specific reference signals, when it is determined that the third symbol is subjected to interference from the one or more interfering wireless devices; or

- calculating (213, 512) the second covariance value for the second and third symbols by accumulating the second and third device specific reference signals, when it is determined that the third symbol is not subjected to interference from the one or more interfering wireless devices.

8. The method according to any of the previous claims 1-7, wherein obtaining scheduling information from one or more neighboring network nodes or sectors comprises:

- obtaining at least one of time domain and frequency domain resource element allocation associated with the one or more neighboring network nodes for every received resource block.

9. The method according to any of the previous claims 1-8, wherein obtaining scheduling information from one or more neighboring network nodes or sectors, comprises:

- obtaining a bit map from the one or more neighboring network nodes or sectors for each symbol in the received resource block, the bit map indicating whether the one or more neighboring network nodes has scheduled traffic on each symbol in the resource block.

10. A computer program product comprising a non-transitory computer readable medium (700), wherein the non-transitory computer readable medium has stored there on a computer program comprising program instructions, wherein the computer program is configured to be loadable into a data-processing unit (710), comprising a processor (720) and a memory (730) associated with or integral to the data-processing unit (710), wherein when loaded into the data-processing unit (710), the computer program is configured to be stored in the memory (730), wherein the computer program, when loaded into and run by the processor (720) is configured to cause the processor (720) to execute method steps according to any of the claims 1-10.

11. An apparatus (800) for a network node (611) for determining receiver weights, the network node operating in a wireless communication network and comprising a receiver (820) for receiving transmissions from at least one serving wireless device (612), the apparatus comprising controlling circuitry (810) configured to cause:

- obtainment of scheduling information from one or more neighboring network nodes (621, 631) or sectors (620, 630), the scheduling information pertaining to one or more interfering wireless devices (622, 632) associated with the one more neighboring network nodes (621, 631) or sectors (620, 630);

- determination of, based on the obtained scheduling information, whether a resource block (lOOa-d, 300, 400) received from the at least one serving wireless device (612) and comprising one or more device specific reference signals is subjected to partial interference from the one or more interfering wireless devices (622, 632); wherein, when it is determined that the received resource block is subjected to partial interference, the controlling circuitry (810) is configured to cause:

- calculation of a first covariance value for a first symbol comprising a first device specific reference signal and comprised in the resource block, wherein the first symbol is subjected to interference from the one or more interfering wireless devices (622, 632);

- calculation of a second covariance value for a second symbol comprising a second device specific reference signal and comprised in the resource block, wherein the second symbol is not subjected to interference from the one or more interfering wireless devices (622, 632); and

- determination of a first set of receiver weights and a second set of receiver weights based on the calculated first and second covariance value respectively.

12. The apparatus according claim 11, wherein the controlling circuitry (810) is further configured to cause:

- application of the first set of receiver weights for detecting a first set of symbols in the resource block, wherein the first set of symbols is subjected to interference from the one or more interfering wireless devices (622, 632) and comprises the first symbol; and

- application of the second set of receiver weights for detecting a second set of symbols in the resource block, wherein the second set of symbols is not subjected to interference from the one or more interfering wireless devices (622, 632) and comprises the second symbol.

13. The apparatus according to any of the previous claims 11-12, wherein the first covariance value is calculated based on a received signal, an estimated channel matrix and the first symbol; and the second covariance value is calculated based on the received signal, the estimated channel matrix and the second symbol.

14. The apparatus according to any of the previous claims 11-13, wherein the device specific reference signal is a demodulation reference signal, DMRS.

15. The apparatus according to any of the previous claims 11-14, wherein the second device specific reference signal is a copy of the first device specific reference signal, and wherein the first and second device specific reference signals occupy the same frequency.

16. The apparatus according to any of the previous claims 11-15, wherein the first and second device specific reference signals are received on a same antenna port.

17. The apparatus according to any of the previous claim 11-16, wherein the controlling circuitry (810) is further configured to cause:

- determination of whether the resource block comprises a third device specific reference signal;

- determination of whether a third symbol comprising the third device specific reference signal is subjected to interference from the one or more interfering wireless devices (622, 632); and - calculation of the first covariance value for the first and third symbols by accumulating the first and third device specific reference signals, when it is determined that the third symbol is subjected to interference from the one or more interfering wireless devices (622, 632); or

- calculation of the second covariance value for the second and third symbols by accumulating the second and third device specific reference signals, when it is determined that the third symbol is not subjected to interference from the interfering one or more wireless devices (622, 632).

18. The apparatus according to any of the previous claims 11-17, wherein the controlling circuitry (810) is configured to cause obtainment of scheduling information from one or more neighboring network nodes (621, 631) or sectors (620, 630) by being configured to cause:

- obtainment of at least one of time domain and frequency domain resource element allocation associated with the one or more neighboring network node or sectors for every received resource block.

19. The apparatus according to any of the previous claims 11-18, wherein the controlling circuitry (810) is configured to cause obtainment of scheduling information from one or more neighboring network nodes (621, 631) or sectors 8620, 630) by being configured to cause:

- obtainment of a bit map from the one or more neighboring network nodes or sectors for each symbol in the received resource block, the bit map indicating whether the one or more neighboring network nodes or sectors has scheduled traffic on each symbol in the resource block.

20. A network node (61, 621, 631), comprising the apparatus (800) according to any of the previous claims 11-19.