Method and network node for interference mitigation for TDD UL / DL configuration

Abstract

A method for reducing interference in a wireless device (200) (the wireless device is operated in a cell using a time division duplex (TDD) configuration) from at least another wireless device (which is operated in a neighboring cell using another TDD configuration) for a network node is proposed. The TDD configuration is divided into different time units for at least downlink (DL) transmission and uplink (UL) transmission. The method includes: allocating time units in the TDD configuration to one of at least two time unit groups, wherein the allocation of time units to the time unit groups is based on interference from a neighboring cell using another TDD configuration. The method also includes: using different link adaptations for at least two time unit groups. A network node is also provided.

Description

Technical Field

[0001] Embodiments presented herein relate to a method for a network node, a network node, a computer program, and a computer program product for reducing the impact of interference from at least another wireless device operating in a neighboring cell using another TDD configuration. Background Art

[0002] 5G NR (New Radio) is the latest standard in the 3GPP family of cellular standards and supports very high data rates and lower latency compared to LTE (4G) and 3G / 2G technologies that preceded 5G NR.

[0003] Transmissions and receptions from nodes (e.g., terminals or user equipment (UE) and base stations) in cellular standards such as NR or LTE may be multiplexed in the frequency domain or the time domain (or a combination thereof). Figure 1 Frequency division duplexing (FDD), shown on the left, means that downlink (DL) transmissions and uplink (UL) transmissions occur in different, well-separated frequency bands. Figure 1 Time Division Duplex (TDD), shown on the right, means that downlink transmissions and uplink transmissions occur in different, non-overlapping time slots. Therefore, TDD can operate in unpaired spectrum, while FDD requires paired spectrum.

[0004] In LTE and NR, neighboring cells usually have the same uplink-downlink configuration to avoid severe interference between uplink and downlink transmissions. This makes it difficult to dynamically change the uplink-downlink configuration according to the current traffic pattern.

[0005] Networks of different operators in the same area may operate in adjacent frequencies. Due to independent UL power control between different cells and different operators, the transmit power of UEs from different operators cannot be controlled, which may cause severe interference when the UE has a large path loss to its serving base station and uses a large transmit power to compensate for the path loss. For example, the spectrum mask required for adjacent channel suppression (usually on the order of 30-40dB compared to the transmit power) is less than the path loss difference between other operator UEs and their own base stations. This means that, for example, two UEs belonging to people traveling on the same bus and using different operator networks operating on adjacent frequencies may cause significant interference to each other. If the operator networks use different TDD uplink-downlink configurations, the amount of so-called cross-link interference may be large.

[0006] To achieve coexistence within reasonable power and spectrum constraints, some countries’ IT and telecommunications government agencies (e.g. Post och Telestyrelsen (PTS) in Sweden) have specified fixed TDD modes. For Australia’s new NR sub-6 spectrum, ACMA specified fixed TDD modes that are operator synchronized and matched to LTE Configuration 1. However, the potential spectrum utilization improvements that can be achieved with dynamic TDD are not exploited.

[0007] If neighboring cells or operators with neighboring frequency bands are allowed to have different uplink-downlink configurations, there may be several cases of severe cross-interference. For example, a UE receiving downlink at the cell edge may be severely interfered by a neighboring UE that is simultaneously transmitting in uplink to a neighboring base station using a different uplink-downlink configuration, such as Figure 2 shown. Figure 2 A network node and a wireless device operating in one cell using a TDD configuration (TDD configuration A) are shown, as well as another network node and another wireless device operating in another neighboring cell using another TDD configuration (TDD configuration B). There may be interference, cross-link interference, between the network nodes and between the wireless devices because they operate in neighboring cells operating using different TDD configurations.

[0008] Even if the channels are changing slowly, the interference may change rapidly in a time-slot periodic pattern, depending on the uplink-downlink configuration chosen for the neighboring cells. Neighboring cells operated by the same operator usually use the same frequency band, and in case of different uplink-downlink configurations, cross-link interference may be severe, especially at the cell-edges. Neighboring cells operated by different operators on adjacent frequency bands and using different TDD configurations may experience less cross-link interference due to the spectral masking required for adjacent channel suppression. However, neighboring cells operated by different operators may almost completely overlap geographically (they may even use the same tower as their antenna), so cross-link interference problems are usually significant in all parts of the cell, not just at the cell-edges.

[0009] The interference level in UL-DL conflicting subframes or time slots will depend on the UE individual locations for co-channel cases (neighboring cells) and adjacent channel cases (e.g. different operators). If the UEs are well separated, there will not be any significant interference, especially for adjacent channel cases with adjacent channel suppression applied.

[0010] Cross-link interference from a UE transmitting in the uplink to a neighboring UE in a neighboring cell that is trying to receive a downlink transmission is one example. Another example of significant cross-link interference is a downlink transmission in a cell where a UE is in the direction of a neighboring base station, which may be interfered by the downlink transmission when receiving an uplink transmission from a UE in its own cell. In this case, it is the beam / antenna direction and receiver combining ("receive beam direction") that is relevant, not the exact location of the UE.

[0011] If the operators' networks are not synchronized and use different TDD mode configurations, the interference will vary periodically between different subframes or time slots. Summary of the invention

[0012] According to one aspect, a method in a network node is provided. The method is performed in the network node to reduce the impact of interference from at least another adjacent cell in a cell. The cell operates using a time division duplex (TDD) configuration, while the adjacent cell operates using another TDD configuration. The TDD configuration is divided into different time units for at least downlink (DL) transmission and uplink (UL) transmission. The method includes: allocating a time unit in the TDD configuration to one of at least two time unit groups. Allocating a time unit to a time unit group is based on the other TDD configuration used in the adjacent cell. The method also includes: using different link adaptation methods for the at least two time unit groups.

[0013] According to another aspect, a network node is provided. The network node is configured to reduce the impact of interference from at least another adjacent cell in a cell. The cell is configured to operate using a time division duplex (TDD) configuration, and the adjacent cell is configured to operate using another TDD configuration. The TDD configuration is divided into different time units for at least downlink (DL) transmission and uplink (UL) transmission. The network node includes a processor and a memory for storing program code, and the program code is executed by the processor to perform operations, the operations including: assigning a time unit in the TDD configuration to one of at least two time unit groups. Assigning a time unit to a time unit group is based on the other TDD configuration used in the adjacent cell. The operations also include: using different link adaptation methods for the at least two time unit groups.

[0014] According to another aspect, a computer program is provided. The computer program reduces the impact of interference from at least another adjacent cell in a cell. The cell operates using a time division duplex TDD configuration, while the adjacent cell operates using another TDD configuration. The TDD configuration is divided into different time units for at least downlink DL transmission and uplink UL transmission. The computer program includes computer code, which, when running on a processing circuit, causes the network node to: assign the time unit in the TDD configuration to one of at least two time unit groups. Assigning the time unit to the time unit group is based on the other TDD configuration used in the adjacent cell. The computer program also causes the network node to: use different link adaptation methods for the at least two time unit groups.

[0015] According to another aspect, a computer program product is provided, comprising a computer program according to the above content, and a computer-readable storage medium storing the computer program thereon.

[0016] The time unit in the TDD configuration is assigned to different time unit groups, specifically depending on the possibility that the time unit experiences interference (for example, the cross-link interference of another TDD configuration in the adjacent cell using different TDD configurations). In this way, the time unit can be assigned to the time unit group according to the possibility that they will experience interference. Therefore, data or control signaling can be transmitted in the time unit according to the sensitivity of data or control signaling to error, interference or fault transmission. For example, the most sensitive or most important data or control signaling can be transmitted in the time unit group without or rarely experiencing interference. Not too sensitive data and control signaling can be transmitted in the time unit group that will experience more interference, particularly cross-link interference. DETAILED DESCRIPTION

[0017] The inventive concept will now be described more fully below with reference to the accompanying drawings, in which specific embodiments of the inventive concept are shown. However, the inventive concept may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that the disclosure will be thorough and complete and the scope of the inventive concept will be fully conveyed to those skilled in the art. Throughout the specification, the same numbers represent the same elements. Any steps or features shown in dashed lines should be considered optional.

[0018] Figure 3is a schematic diagram showing a communication network 100a to which embodiments proposed herein may be applied. The communication network 100a may be a third generation (3G) telecommunication network, a fourth generation (4G) telecommunication network or a fifth generation (5G) telecommunication network and support any 3GPP telecommunication standard.

[0019] The communication network 100a includes a transmission point TP 140, which includes an antenna device 500, which may be a multiple input multiple output (MIMO) antenna including two or more antennas. The antenna device 500 is connected to the radio device 400. The communication network 100a also includes a network node 200, which may include one or more TPs. The network node is configured to provide network access to a user equipment (UE) 300 in a radio access network 110. The radio access network 110 is operationally connected to a core network 120. The core network 120 is in turn operationally connected to a service network 130, such as the Internet. The UE 300 is thus able to access the services of the service network 130 and exchange data with the service network 130 via the network node and the transmission point 140. Examples of network nodes are radio access network nodes, radio base stations, base transceiver stations, node Bs, evolved node Bs, g node Bs, gNBs, access points, access nodes, antenna integrated radios (AIRs), and transmit and receive points (TRPs). UEs may also be referred to as wireless devices. Other examples of UE are terminal equipment, mobile stations, mobile phones, handsets, wireless local loop phones, smart phones, laptops, tablets, network-equipped sensors, network-equipped vehicles and so-called Internet of Things devices.

[0020] Typically, the structure of signals transmitted in a communication system is organized in the form of a frame structure. For example, LTE uses ten equally sized subframes of length 1 ms per radio frame, such as Figure 4 shown.

[0021] LTE and NR use Orthogonal Frequency Division Multiplexing (OFDM) in the downlink direction and Discrete Fourier Transform (DFT) extended OFDM in the uplink direction. Therefore, the basic LTE downlink physical resources can be viewed as a time-frequency grid, where each resource element corresponds to one OFDM subcarrier during one OFDM symbol interval. In the time domain, LTE downlink transmissions can be organized into 10ms radio frames, each of which consists of ten equally sized subframes of length Tsubframe = 1ms.

[0022] In addition, resource allocation in LTE is usually described in terms of resource blocks, where a resource block corresponds to one time slot in the time domain (e.g., 0.5 ms) and to 12 subcarriers in the frequency domain. A pair of two resource blocks adjacent in the time direction (e.g., 1.0 ms) is called a resource block pair. Resource blocks are numbered in the frequency domain, starting with 0 at one end of the system bandwidth.

[0023] NR terminology is fairly consistent with LTE terminology; for example, a resource element (RE) is still 1 subcarrier x 1 OFDM symbol. However, some terms known in LTE have been given new meanings in NR. This disclosure (including the claims) applies the prefixes "LTE" and "NR" where ambiguity may arise.

[0024] In view of the NR specification, any term designating an object or operation known from LTE is expected to be functionally reinterpreted. Example: Considering that both LTE radio frame and NR frame have a duration of 10ms, the LTE radio frame can be functionally equivalent to the NR frame. LTE eNB can be functionally equivalent to NR gNB, as their functionality as downlink transmitters at least partially overlaps. The least schedulable resource unit in LTE can be reinterpreted as the least schedulable resource unit in NR. The shortest data set for which LTE acknowledgment feedback is possible can be reinterpreted as the shortest data set for which NR acknowledgment feedback is possible.

[0025] Therefore, even though some embodiments of the present disclosure have been described using terminology derived from LTE or terminology derived from NR, they are still fully applicable to NR technology or LTE technology, respectively. In addition, throughout the embodiments, the term 'subframe' is fully interchangeable with the term 'time slot'.

[0026] In case of FDD operation, as Figure 1 As shown on the left, there are two carrier frequencies, one for uplink transmission (fUL) and one for downlink transmission (fDL). FDD, at least for terminals in a cellular communication system, can be either full-duplex or half-duplex. In the full-duplex case, the terminal can transmit and receive simultaneously, while in half-duplex operation, the terminal cannot transmit and receive simultaneously. However, the base station is able to receive / transmit simultaneously, for example, receiving from one terminal while transmitting to another terminal. In LTE, half-duplex terminals monitor / receive in the downlink unless explicitly instructed to transmit in a specific subframe.

[0027] In the case of TDD operation, such as Figure 1As shown in the right part of , there is only a single carrier frequency, and uplink and downlink transmissions are always separated in time on a cell basis. Since the same carrier frequency is used for uplink and downlink transmissions, both the base station and the mobile terminal need to switch from transmission to reception and from reception to transmission. One aspect of any TDD system is the possibility to provide a sufficiently large guard time, during which neither downlink nor uplink transmissions occur. This is necessary to avoid interference between uplink and downlink transmissions. For LTE, this guard time is provided by special subframes (e.g., subframe 1 and in some cases subframe 6 of a frame), which are divided into three parts: a downlink part (DwPTS), a guard period (GP), and an uplink part (UpPTS), as shown in FIG. Figure 4 The remaining subframes are allocated either to uplink transmission or to downlink transmission.

[0028] With different uplink-downlink configurations, TDD allows for different asymmetries in the amount of resources allocated for uplink and downlink transmissions, respectively. In LTE, there are seven different configurations, as shown in Table 1. It should be understood that a DL subframe may refer to a DL or special subframe.

[0029] In TDD, some subframes / time slots / symbols are allocated for uplink transmissions and some subframes / time slots / symbols are allocated for downlink transmissions. The switch between downlink and uplink occurs in so-called special subframes (LTE) or flexible subframes (NR).

[0030] Table 1: LTE uplink-downlink configuration (from 36.211, Table 4.2-2)

[0031]

[0032] The size of the guard period (and thus the number of symbols of DwPTS and UwPTS in a special subframe) may also be configured from a set of possible choices.

[0033] On the other hand, NR provides many different uplink-downlink configurations. There are 10 to 320 time slots per radio frame (where each radio frame is 10 milliseconds long), depending on the subcarrier spacing. Each time slot can be configured with a time slot format as shown in Table 2. If a dynamic time slot format indication (SFI) is used (where the format of the time slot is indicated by DCI format 2_0), the OFDM symbols in the time slot are classified as "downlink" (marked as "D" in Table 2), "flexible" (marked as "X"), or "uplink" (marked as 'U'). As an alternative to this, a semi-static TDD UL-DL configuration can be used, where the TDD configuration is configured using the RRC IE TDD-UL-DL-ConfigCommon:

[0034]

[0035] That is, the number of UL and DL time slots and the guard period (the number of UL symbols and DL symbols in a flexible time slot) can be configured almost arbitrarily within a TDD cycle. This allows for very flexible uplink-downlink configurations.

[0036] Table 2: NR timeslot format (from 38.211, Table 4.3.2-3)

[0037]

[0038]

[0039] To avoid severe interference between downlink and uplink transmissions between different cells, neighboring cells should have the same downlink / uplink configuration. If this is not done, uplink transmissions in one cell may interfere with downlink transmissions in neighboring cells, and vice versa.

[0040] In a reconfigurable TDD system, the TDD configuration can be changed according to the service requirements of each cell. As a result, two adjacent base stations may use corresponding different resource allocations for UL and DL, which may cause DL to UL interference, that is, the transmitting base station to the receiving base station interference. DL to UL interference (which will be referred to as cross-link interference (CLI) in this article) occurs when one base station (referred to as base station in this article) is transmitting on DL and the second base station is receiving transmissions from the UE in UL. Different resource allocations cause interference.

[0041] Figure 5 The TDD configuration of two adjacent cells is schematically shown. It is assumed that the cells are synchronized. If the cells belong to different networks, it is assumed that the networks are synchronized.

[0042] exist Figure 5In a, one of the UEs has a more "downlink heavy" TDD configuration. "Downlink heavy" is defined as a TDD configuration with more subframes or time slots available for DL. "Uplink heavy" is defined by a TDD configuration with more subframes or time slots available for UL. Figure 5 aAs can be seen, a subframe or time slot in which one cell is configured for uplink and the other cell is configured for downlink or vice versa is called a variable subframe or time slot. A subframe or time slot in which one cell is configured for uplink and the other cell is also configured for uplink (both cells may also be configured for downlink) is called a fixed subframe or time slot. CLI mainly appears in variable subframes or time slots because two cells / networks transmit in the same direction in fixed subframes or time slots.

[0043] If two UEs belong to different cells, which are scheduled with different uplink-downlink configurations and are close to each other, e.g. Figure 2 As shown in FIG. 1 , UEs with more DL time slots (referred to as Rx UEs) will experience interference on the changing time slots used for the downlink. UEs with more UL time slots (referred to as Tx UEs) may experience less cross-link interference than Rx UEs. Figure 5 This is exemplarily shown in b, where it is assumed that neighboring UEs are so close that they may experience CLI and other interference due to their proximity to each other.

[0044] exist Figure 5 In c, the time slots are grouped into at least two types of time slots. The first group (Group A) includes the variable time slots, i.e., the time slots that are mainly affected by the cross-link interference. The second group (Group B) includes the time slots that are not affected by the cross-link interference.

[0045] In another embodiment, the time slots are grouped into at least two groups. The first group (Group A) includes variable time slots, i.e., time slots that are more likely to be affected by interference, especially cross-link interference. The second group (Group B) includes time slots that are less likely to be affected by cross-link interference. Time slots can be grouped into more groups based on their likelihood of being affected by cross-link interference.

[0046] In cases where regulations allow only a few different uplink-downlink configurations to be used, the grouping of time slots can be configured once and then remain fixed. In this case, it is not necessary to know the actual uplink-downlink configuration used for the cells in the network when configuring the grouping, it is sufficient to know that the uplink-downlink configuration is one of a few possible configurations. The grouping can also be dynamic, taking into account which uplink-downlink configurations the neighboring cells (co-channel or adjacent channels) are configured with. If these configurations change, the grouping can be updated.

[0047] The at least two time slot groups are then processed separately for link adaptation and / or scheduling, thereby reducing the impact of cross-link interference on, for example, throughput.

[0048] Figure 6 The method steps of the embodiments disclosed herein are shown. The method is performed by a network node (300), and the purpose of the method is to reduce the impact of cross-link interference on transmissions between a wireless device (200) and the network node (300). The wireless device is configured with a specific TDD configuration in a cell, such as one of the configurations in Table 1 or Table 2. The wireless device may experience CLI from another neighboring wireless device in a neighboring cell operating with another TDD configuration. For example, a wireless device may belong to a cell configured with uplink-downlink configuration 2 in Table 1, while a neighboring wireless device may belong to a cell configured with uplink-downlink configuration 3 in Table 1. The TDD configuration is divided into different time units for at least downlink (DL) transmission and uplink (UL) transmission, and thus the wireless device can receive or transmit within the time unit. The time unit may have a length of a subframe, a time slot and / or a symbol. In some embodiments, the time unit is a time period, such as 1 ms. In an illustrative embodiment, subframes, time slots and symbols may be used interchangeably. Although some illustrative embodiments are disclosed with respect to slot time units, these embodiments are also applicable to symbol time units or subframe time units.

[0049] In step 601, the network node allocates time units in a TDD configuration to one of at least two time unit groups. The allocation of time units to the time unit groups is based on the TDD configuration used in the serving cell and in at least one neighboring cell.

[0050] In the exemplary embodiment, it is assumed that Figure 7 The first NR TDD timeslot configuration for 30kHz subcarrier spacing shown in a. The TDD configuration includes DL timeslots (D), UL timeslots (U), and special DL timeslots (S). This may represent the TDD configuration used by the serving cell and wireless device. Figure 7 Another exemplary TDD configuration with more uplink time slots is shown in b. This TDD configuration may represent the TDD configuration used by neighboring wireless devices in neighboring cells. In an exemplary embodiment, time units are allocated to each group as follows:

[0051] Group A is fixed: time slots {0,1,2,3,4,5,8,9,10,11,12,13,14,15,18,19}

[0052] Group B changes: time slots {6,7,16,17}

[0053] It is assumed that the special DL time slots (S) have the same DL and UL symbol configuration in each of the two example configurations. Therefore, there will not be any cross-link interference in the special time slots in this exemplary embodiment, and these time slots can be included in Group A. Group B contains time slots that can be DL or UL, depending on which cell (and thus which TDD configuration) the wireless device belongs to.

[0054] The time slots allocated to group A and group B are then processed separately for link adaptation and / or scheduling. For both groups, different link adaptation methods are applied, step 602.

[0055] In some embodiments, link adaptation is divided into two outer loops for different groups. Block errors caused by cross-link interference caused by different TDD configurations in neighboring cells will cause the outer loop to increase margins and use a more robust modulation and coding scheme (MCS) for time slots in group B compared to time slots in group A. In one embodiment, the signal-to-noise ratio (SNR) threshold for the selection of a specific modulation and coding scheme (MCS) is different for groups A and B.

[0056] In an exemplary embodiment, downlink control information (DCI) for PUSCH scheduling of variable time slots 6, 7, 16 and 17 is allocated to variable DL time slots 6, 7, 16 and / or 17. DCI for PUSCH scheduling of fixed UL time slots 4, 5, 14 and 15 is allocated to fixed DL time slots 0-3, 8-12 and / or 18-19.

[0057] In an exemplary embodiment, ACK / NACK responses to PDSCH on variable slots 6, 7, 16 and 17 are allocated to variable UL slots 6, 7, 16 and / or 17. ACK / NACK responses to PDSCH on fixed DL slots 0-3, 8-12 and / or 18-19 are allocated to fixed UL slots 4, 5, 14 and 15.

[0058] Exemplary embodiments involve transmitting all control signaling in fixed time slots without cross-link interference, thereby reducing the error rate of control signaling. However, in some embodiments, the amount of control data to be transmitted may be too large to fit into a fixed time slot. Therefore, DCI and HARQ ACK / NACK are preferably assigned to time slots in the same group as the actual data transmission.

[0059] In another embodiment, control signals (RLC, RRC and higher layers) are scheduled on time slots in Group A to maintain connectivity also for wireless devices exposed to severe TDD interference such as CLI.

[0060] Different HARQ processes can be used for different groups of time slots. Then, any retransmission of data from one group of time slots will be transmitted in a time slot belonging to the same group of time slots. This can be advantageous because the number of bits to be transmitted in the time-frequency resources of a time slot can differ significantly between different groups, depending on the MCS selection offset, different average SINRs, etc. For a data packet that is first transmitted on a fixed time slot (meaning that a large data packet can be transmitted because the MCS is usually high) and then retransmitted on a varying time slot (capable of carrying much less data), the amount of additional information received in the retransmission may not be sufficient to correctly decode the data packet.

[0061] In some embodiments, different HARQ processes are used for different time unit groups. In addition, HARQ processes associated with different time unit groups may be associated with different link adaptation outer loops.

[0062] Different outer loop methods and characteristics (e.g., SINR offset) can be used for the two time slot groups. For group B, filtering such as windowing can be applied so as not to compensate for a single block error to limit the impact of a single TDD scheduling conflict occurring. This will improve overall throughput and capacity if simultaneous scheduling of two wireless devices close to each other is unlikely.

[0063] In another embodiment, the TDD configuration set may be limited to only a few allowed configurations. Group A may be selected to include only time slots where all possible configurations have time slots of the same type. The variable time slots included in Group B are all time slots that are not of the same type in each allowed configuration. Figure 7 c shows an example embodiment with three allowed TDD configurations. The figure also shows how the time slots are divided into Group A and Group B, where Group A includes fixed time slots and Group B includes variable time slots.

[0064] Therefore, the time units are allocated to the time unit groups so that the time units are allocated to the time unit groups according to how much cross-link interference they may be subject to. Therefore, the time unit groups may be Group A and Group B as described above in some embodiments, and in other embodiments, the time units are allocated to at least two time unit groups so that the time units that will experience or may experience cross-link interference from a neighboring cell using another TDD configuration are allocated to one time unit group, and the other time units in the TDD configuration are allocated to another time unit group.

[0065] Figure 8 The components of the network node 200 according to the embodiment are schematically shown in terms of a number of functional units. Fig.10 The processing circuit 210 may be provided by any combination of one or more of a suitable central processing unit (CPU), a multiprocessor, a microcontroller, a digital signal processor (DSP), etc., which may be implemented using software instructions in a processor (such as a processor, ...

[0066] In particular, the processing circuit 210 is configured to cause the network node 200 to perform a set of operations or steps 601-602 as described above. For example, the storage medium or memory 230 may store the set of operations, and the processing circuit 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the network node 200 to perform the set of operations. The set of operations may be provided as a set of executable instructions.

[0067] Thus, the processing circuit 210 is thereby arranged to perform the method as disclosed herein. The storage medium 230 may also include a persistent storage device, which may be, for example, any one of a magnetic memory, an optical memory, a solid-state memory, or even a remotely mounted memory, or a combination thereof. The network node 200 may also include a communication interface 220 configured at least for communicating with other nodes, devices, functions of the communication network 100a. Thus, the communication interface 220 may include one or more transmitters and receivers, one or more transmitters and receivers including analog and digital components. The communication interface 220 may be used to send and receive signals from the network node 200 and by the network node 200.

[0068] The processing circuit 210 controls the overall operation of the network 200, for example, by sending data and control signals to the communication interface 220 and the storage medium 230, by receiving data and reports from the communication interface 220, and by retrieving data and instructions from the storage medium 230. In order not to obscure the concepts presented herein, other components of the network node 200 and related functions are omitted.

[0069] Fig. 9 The components of the wireless device (UE) 300 according to the embodiment are schematically shown in terms of a number of functional units. Fig.10 The processing circuit 310 may be provided by any combination of one or more of a suitable central processing unit (CPU), a multiprocessor, a microcontroller, a digital signal processor (DSP), etc., which may be implemented using software instructions in a processor (such as a processor, ...

[0070] In particular, the processing circuit 310 is configured to cause the UE 300 to perform a set of operations as described above. For example, the storage medium or memory 330 may store the set of operations, and the processing circuit 310 may be configured to obtain the set of operations from the storage medium 330 to cause the UE 300 to perform the set of operations. The set of operations may be provided as a set of executable instructions.

[0071] Thus, the processing circuit 310 is thereby arranged to perform the method as disclosed herein. The storage medium 330 may also include a persistent storage device, which may be, for example, any one of a magnetic memory, an optical memory, a solid-state memory, or even a remotely mounted memory, or a combination thereof. The UE 300 may also include a communication interface 320 configured at least for communicating with other nodes, devices, functions of the communication network 100a. Thus, the communication interface 320 may include one or more transmitters and receivers, and the one or more transmitters and receivers include analog and digital components. The communication interface 320 may be used to send and receive signals from the UE 300 and by the UE 300.

[0072] The processing circuit 310 controls the overall operation of the UE 300, for example, by sending data and control signals to the communication interface 320 and the storage medium 330, by receiving data and reports from the communication interface 320, and by obtaining data and instructions from the storage medium 330. Optionally, the UE may include a display 340, but the embodiments of this document are not limited thereto. In order not to confuse the concepts presented herein, other components of the UE 300 and related functions are omitted.

[0073] Fig.10 An example of a computer program product 910 including a computer-readable storage medium 930 is shown. A computer program 920 may be stored on the computer-readable storage medium 930, which may cause the processing circuit 210 or 310 and entities and devices operatively coupled thereto (e.g., the communication interface 220 or 320 and the storage medium 230 or 330) to perform methods according to the embodiments described herein. The computer program 920 and / or computer program product 910 may therefore provide means for performing any of the steps disclosed herein.

[0074] exist Figure 8In the example of , computer program product 910 is shown as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-ray disc. Computer program product 910 may also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM) or an electrically erasable programmable read-only memory (EEPROM), and more specifically, as a non-volatile storage medium of a device in an external memory (such as a USB (universal serial bus) memory) or a flash memory (such as a compact flash). Therefore, although computer program 920 is schematically shown here as a track on the depicted optical disc, computer program 920 may be stored in any manner suitable for computer program product 910.

[0075] The inventive concept has been described above mainly with reference to a few embodiments. However, as readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept as defined by the appended patent claims.

Claims

1. A method in a network node for reducing the impact of interference in a cell from at least one other neighboring cell, the cell operating using a time division duplex (TDD) configuration, the neighboring cell operating using another TDD configuration, wherein: The TDD configuration is divided into different time units for at least downlink DL transmission and uplink UL transmission, and the method includes: - allocating (601) time units in the TDD configuration to one of at least two time unit groups, wherein the allocation of time units to a time unit group is based on the other TDD configuration used in the neighboring cell, wherein different HARQ processes are used for the at least two different time unit groups, and wherein the HARQ processes associated with the at least two different time unit groups are associated with different link adaptation outer loops; and - For the at least two groups of time units, using (602) different link adaptation methods.

2. The method according to claim 1, wherein: One time unit group includes fixed time slots and at least another time unit group includes variable time slots.

3. The method according to claim 1 or 2, wherein: The time units are allocated to the at least two groups of time units such that time units experiencing cross-link interference from the neighboring cell using the other TDD configuration are allocated to one group and other time units in the TDD configuration are allocated to the other group.

4. The method according to claim 1, wherein: Using different link adaptation methods includes: using different link adaptation outer loop instances for the at least two time unit groups.

5. The method according to claim 1, wherein: A more robust modulation and coding scheme MCS is used for the group of time units that experiences cross-link interference from the neighboring cell using the other TDD configuration than a modulation and coding scheme MCS used for at least another group of time units.

6. The method according to claim 1, wherein: The SNR threshold is different for the group of time units that experiences the most cross-link interference from the neighboring cell using the another TDD configuration compared to the SNR threshold for selection of the modulation and coding scheme MCS for another group of time units that does not experience cross-link interference.

7. The method according to claim 1, wherein: The HARQ feedback ACK / NACK associated with a time unit group in the downlink is transmitted in a time unit in the same time unit group in the uplink.

8. The method according to claim 1, wherein: UL, downlink control information DCI associated with an uplink UL time unit group is transmitted in the same time unit group in the downlink.

9. The method according to claim 1, wherein: Control signaling such as RLC, RRC and / or other higher layer signaling is transmitted in a group of time units that experiences the least interference from the neighboring cell using the other TDD configuration.

10. The method according to claim 1, wherein: The time unit is a time unit for at least one of a subframe, a slot, and a symbol.

11. The method according to claim 1, wherein: The time units in the group of time units are scheduled downlink time units, uplink time units, special downlink time units or flexible time units.

12. The method according to claim 1, wherein: The network node and the wireless device operate in the cell using the TDD configuration, and another network node and another wireless device operate in the neighboring cell using the another TDD configuration.

13. The method according to claim 1, wherein: The impact of the interference in the cell from at least one other neighboring cell is reduced in a wireless device and / or the network node operating the cell.

14. A network node (200) configured to reduce the impact of interference in a cell from at least another neighboring cell, the cell being configured to operate using a time division duplex (TDD) configuration, the neighboring cell being configured to operate using another TDD configuration, wherein: The TDD configuration is divided into different time units for at least downlink DL transmission and uplink UL transmission, and the network node comprises: processing circuit (210), and A memory (230) for storing program code executed by the processor circuit (210) to perform operations, the operations comprising: - assigning time units in the TDD configuration to one of at least two time unit groups, wherein the assignment of time units to the time unit groups is based on the other TDD configuration used in the neighboring cell, wherein different HARQ processes are used for the at least two different time unit groups, and wherein the HARQ processes associated with the at least two different time unit groups are associated with different link adaptation outer loops; and - For the at least two time unit groups, different link adaptation methods are used.

15. The network node according to claim 14, wherein: One time unit group includes fixed time slots and at least another time unit group includes variable time slots.

16. The network node according to claim 14 or 15, wherein: The time units are allocated to the at least two groups of time units such that time units experiencing cross-link interference from the neighboring cell using the other TDD configuration are allocated to one group and other time units in the TDD configuration are allocated to the other group.

17. The network node according to claim 14, wherein: Using different link adaptations includes: using different link adaptation method outer loop instances for the at least two time unit groups.

18. The network node according to claim 14, wherein: A more robust modulation and coding scheme MCS is used for the group of time units that experiences cross-link interference from the neighboring cell using the other TDD configuration than a modulation and coding scheme MCS used for at least another group of time units.

19. The network node according to claim 14, wherein: The SNR threshold is different for the group of time units that experiences the most cross-link interference from the neighboring cell using the another TDD configuration compared to the SNR threshold for selection of the modulation and coding scheme MCS for another group of time units that does not experience cross-link interference.

20. The network node according to claim 14, wherein: The HARQ feedback ACK / NACK associated with a time unit group in the downlink is transmitted in a time unit in the same time unit group in the uplink.

21. The network node according to claim 14, wherein: UL, downlink control information DCI associated with an uplink UL time unit group is transmitted on the same time unit group in the downlink.

22. The network node according to claim 14, wherein: Control signaling such as RLC, RRC and / or other higher layer signaling is transmitted in a group of time units that experiences the least interference from the neighboring cell using the other TDD configuration.

23. The network node according to claim 14, wherein: The time unit is a time unit for at least one of a subframe, a slot, and a symbol.

24. The network node according to claim 14, wherein: The time units in the group of time units are scheduled downlink time units, uplink time units, special downlink time units or flexible time units.

25. The network node according to claim 14, wherein: The network node and the wireless device operate in the cell using the TDD configuration, and another network node and another wireless device operate in the neighboring cell using the another TDD configuration.

26. The network node according to claim 14, wherein: The impact of the interference is reduced in a wireless device and / or the network node operating the cell.

27. A computer program product (910) comprising a computer readable storage medium (930) storing a computer program which, when executed in a processor, causes the processor to perform the method according to claim 1.

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