Interference Management in Wireless Systems

Abstract

The present application relates to interference management in wireless systems, and in particular discloses a technique for interference suppression in wireless communication systems. An example method includes: receiving interference state information indicating long-range interference between the first communication node and a second communication node at a first communication node; and performing subsequent communication to the second communication node by the first communication node by implementing a backoff based on granularity.

Description

[0001] This application is a divisional application of the Chinese patent application with application number "201880099101.5", application date "November 2, 2018", and title "Interference Management in Wireless Systems". Technical Field

[0002] This patent document relates generally to wireless communications. Background Art

[0003] Mobile communication technologies are driving the world towards an increasingly connected and networked society. The rapid growth of mobile communications and advances in technology have led to greater demands for capacity and connectivity. Other aspects such as energy consumption, equipment cost, spectrum efficiency, and latency are also important to meet the needs of various communication scenarios. Various technologies are being discussed, including new ways to provide higher quality services, longer battery life, and improved performance. Summary of the invention

[0004] This patent document describes, inter alia, techniques for managing long-range interference caused by phenomena such as atmospheric ducting. The disclosed techniques allow wireless communication nodes to effectively suppress such interference without negatively impacting system performance.

[0005] In one embodiment, a wireless communication method is disclosed. The method includes receiving, at a first communication node, interference state information indicating long-range interference between the first communication node and a second communication node; and performing, by the first communication node, subsequent communication to the second communication node by implementing a backoff based on granularity.

[0006] In another example aspect, another wireless communication method is disclosed. The method includes: sending, by a first communication node, a first reference signal indicating that long-range interference exists between the first communication node and a second communication node, wherein a time domain position of the first reference signal includes one of a last symbol before a maximum downlink transmission boundary for transmission between the first communication node and the second communication node or an Nth symbol before a transmission boundary, wherein N is an integer greater than 1.

[0007] In another example aspect, a wireless communication method is disclosed. The method includes: sending, by a first communication node, a first reference signal indicating that long-range interference exists between the first communication node and a second communication node, wherein the first reference signal is sent in a preconfigured time period, and wherein the first reference signal is sent at multiple occasions in each time period; and using the first reference signal to transmit ID information associated with the first communication node.

[0008] In yet another example aspect, a wireless communication method is disclosed. The method includes: transmitting, from a first communication node, a first reference signal associated with a first interference on an inbound channel to the first communication node and a second reference signal associated with a second interference on an outbound channel from the first communication node. The first reference signal and the second reference signal are transmitted in a non-overlapping manner.

[0009] In yet another example aspect, a wireless communication device is disclosed. The device includes a processor configured to implement the above method.

[0010] In yet another embodiment, a computer program storage medium is disclosed. The computer program storage medium includes code stored thereon. When executed by a processor, the code causes the processor to implement the described method.

[0011] This patent document describes these and other aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 An example of long-range interference caused by atmospheric ducting phenomena is shown.

[0013] Figure 2 Shown by Figure 1 An example of an uplink frame affected by interference due to atmospheric ducting is depicted in Figure 2.

[0014] Figure 3 An example of different frame structures used by different base stations with a common understanding of maximum downlink transmission boundaries and maximum uplink transmission boundaries is shown.

[0015] Figure 4 is a block diagram representation of a portion of a radio station in which techniques in accordance with one or more embodiments of the present technology may be applied.

[0016] Figure 5 is a flow chart of an example method for wireless communication.

[0017] Figure 6 An example workflow for Framework-0 is shown.

[0018] Figure 7 An example workflow for Framework-1 is shown.

[0019] Figure 8 An example workflow for Framework-2.1 ​​is shown.

[0020] Fig. 9 An example workflow for Framework-2.2 is shown.

[0021] Fig.10 An example of a time domain method for long range interference (RI) suppression is shown.

[0022] Fig.11 An example of a frequency domain method for long range interference (RI) suppression is shown.

[0023] Fig.12 An example of a power domain approach for remote interference (RI) suppression is shown.

[0024] Fig.13 An example along the time domain of a Remote Interference Management (RIM) Reference Signal (RS) is depicted.

[0025] Fig.14 An example of raw symbol generation (eg, Physical Downlink Shared Channel, PDSCH, generation) is shown.

[0026] Fig.15 Examples of Orthogonal Frequency Division Multiplexing (OFDM) signals generated for the Alt-2 and Alt-3 methods are shown.

[0027] Fig.16 An alternative for a symbol reference signal with a comb structure is shown.

[0028] Fig.17 An example of OFDM baseband signal generation for RS of two symbols is shown.

[0029] Fig.18 An example of RIM-RS transmission in the time domain is shown.

[0030] Fig.19 An example of remote interference management is shown.

[0031] Fig. 20 An example of remote interference management with a small UL-DL switching period is shown.

[0032] Fig.21 An example is shown where the RIM-RS is repeated before the boundary when the transmission delay exceeds the sum of the GP and UL durations.

[0033] Fig. 22 An example is shown in which the RIM-RS is repeated before the boundary when the transmission delay is within the sum of the GP and UL durations. DETAILED DESCRIPTION

[0034] The section headings used in this patent document are intended only to improve readability and are not intended to limit the scope of the embodiments and techniques disclosed in each section to only that section. Certain features are described using examples of 5G wireless protocols. However, the applicability of the disclosed techniques is not limited to 5G wireless systems.

[0035] Under certain weather conditions, the lower density at higher altitudes in the Earth's atmosphere results in a reduced refractive index, which bends the signal back toward the Earth. In this case, the signal can propagate in a layer of higher refractive index, also called an atmospheric waveguide, because reflection and refraction meet at the boundary with the lower refractive index material. In this propagation mode, the radio signal experiences less attenuation and is guided over distances far greater than the normal radiation range. The frequency range typically affected by this phenomenon is around 0.3 GHz to 30 GHz.

[0036] The time division duplex (TDD) system adopts the TDD duplex mode and sends and receives signals in the same frequency band. The uplink and downlink signals are distinguished by sending in different time periods in the time domain. For example, in the time division long term evolution (TD-LTE) frame structure, there are downlink subframes, uplink subframes and special subframes, wherein all symbols in the downlink subframe are downlink symbols, and all symbols in the uplink subframe are uplink symbols. The special subframe includes the downlink part of the special subframe, the guard period (GP) and the uplink part of the special subframe. The GP does not send any signal and provides protection between the uplink symbol and the downlink symbol, thereby avoiding cross-link interference between the uplink transmission and the downlink transmission.

[0037] However, when the atmospheric ducting phenomenon occurs, the radio signal can propagate a relatively long distance, and the propagation delay exceeds the gap. In this case, the downlink signal of the first base station may propagate a long distance and interfere with the uplink signal of the distant second base station, resulting in interference known as long-range interference. Figure 1 An example of long-range interference caused by atmospheric ducting phenomena is shown. Figure 1 In the example, the downlink signal from gNB 1 (101) may propagate over the ground or ocean and interfere with the uplink signal of gNB 3 (103). Figure 2 Shown by Figure 1 An example of an uplink frame that is interfered with due to atmospheric ducting is depicted in Figure 1. Figure 2 As shown, downlink transmissions from gNB 1 (101) may arrive at gNB 3 (103) after a long transmission delay (201). As shown in overlap region 202, some of the downlink symbols sent by gNB 1 (101) now interfere with uplink symbols sent by gNB 3 (103).

[0038] In order to solve the long-range interference problem, it is first useful to determine the interference source, and the determination of the interference source involves the transmission of a reference signal, for example. After the interference source is determined, it is also useful to accurately perform the interference cancellation mechanism. This document discloses a technique that can be used by an embodiment to provide a signal transmission method and an interference cancellation method for interference cancellation, which can solve the problem of long-end interference and cross-channel interference caused by atmospheric waveguides.

[0039] In some embodiments, remote interference management (RIM) may include the following.

[0040] Architecture-1:

[0041] The interfered base station (e.g., interfered gNB) confirms that it is interfered with RI, and the interfered base station sends a reference signal RS-1.

[0042] The interfering gNB detects RS-1. When RS-1 is detected, it determines that the receiving network device (e.g., gNB) is interfering with other devices. The interfering base station performs the RIM interference avoidance scheme and sends the reference signal RS-2.

[0043] The interfered base station detects RS-2:

[0044] - If RS-2 is detected, it is judged that the atmospheric duct phenomenon still exists and the interfered base station continues to send RS-1;

[0045] - If RS-2 is not detected, the atmospheric ducting phenomenon is judged to have disappeared and the transmission of RS-1 is stopped;

[0046] The interfering base station continues to detect RS-1:

[0047] - If RS-1 is detected, continue with the RIM interference avoidance scheme and continue to send RS-2;

[0048] - If RS-1 is not detected, it is determined that the atmospheric duct phenomenon has disappeared, and the RIM scheme is stopped, and the transmission of RS-2 is stopped;

[0049] Here, RS-1 and RS-2 may be the same or different reference signals.

[0050] Architecture-2.1:

[0051] The interfered base station confirms that it is interfered with by RI, and the interfered base station transmits a reference signal RS (or identified as RS-1).

[0052] The interfering base station detects RS (RS-1). When RS is detected, it is determined that the interfering base station interferes with other base stations. The interfering base station performs the RIM interference avoidance scheme and notifies the interfered base station that it has received the RS through the backhaul.

[0053] If the subsequent interfering base station does not receive the RS, the interfering base station informs the interfered base station that it does not receive the RS through the backhaul and stops performing the RIM scheme.

[0054] Interfered base station:

[0055] - If a return signal received by the RS is received, it is determined that the atmospheric duct phenomenon still exists and the RS continues to transmit;

[0056] - If the return signaling of RS is received but not received, it is judged that the atmospheric duct phenomenon disappears and the sending of RS is stopped;

[0057] Architecture-2.2:

[0058] The interfered base station confirms that it is interfered by RI, and the interfered base station sends a reference signal RS;

[0059] The interfering base station detects the RS. When the RS is detected, it is determined that it interferes with other base stations. The interfering base station notifies the interfered base station through the backhaul that it has received the RS.

[0060] If the interfered base station receives the backhaul signaling of RS reception transmitted by the interfering base station, the interfered base station transmits the auxiliary RIM coordination information to the interfering base station.

[0061] After receiving the RIM coordination information, the interfering base station executes the RIM solution.

[0062] If the subsequent interfering base station does not receive the RS, the interfering base station informs the interfered base station that it does not receive the RS through the backhaul and stops performing the RIM scheme.

[0063] If the interfered base station receives backhaul signaling that the RS is not received, it determines that the atmospheric duct phenomenon disappears and stops sending the RS.

[0064] The above architecture provides an overall description. Not every step in every architecture is required, and other steps can be added.

[0065] In some embodiments disclosed herein, a first base station transmits a signal or information, and a second base station receives the signal or information, thereby performing a far-end interference cancellation scheme, which can solve the atmospheric duct long-range interference problem.

[0066] It can be assumed that, in general, only semi-static time division duplex (TDD) configuration is used between gNBs and only co-channel interference exists between neighboring gNBs. It is also assumed that the semi-static downlink (DL) and uplink (UL) configured by gNBs throughout the network do not conflict with each other in the absence of atmospheric waveguide interference or far-end interference. To ensure this, it is agreed that the entire network needs to be in a DL-UL exchange period or transmission period. To this end, the wireless system can configure a maximum downlink transmission boundary (Max DL Transmission Boundary) and a maximum UL transmission boundary (Max UL Transmission Boundary).

[0067] like Figure 3 As shown, in a DL-UL switching period or transmission period, the maximum DL transmission boundary is represented by a first reference point, and the maximum DL transmission boundary or the first reference point indicates the last DL OFDM symbol allowed to be scheduled. The maximum UL transmission boundary is represented by a second reference point, and the maximum UL transmission boundary or the second reference point indicates the first UL symbol allowed to be scheduled.

[0068] Figure 3 Three timelines are shown that transmissions follow. The horizontal axis represents time. In the top timeline, the arrangement of network transmissions in two directions (inbound / outbound or downlink / uplink) followed by nodes in the wireless network. The time slots marked as D represent one direction in which network transmissions occur (e.g., downlink), the time slots marked as "U" indicate the other direction in which network transmissions occur (e.g., uplink), and the time slots marked as "S" indicate the intervals used to switch between the two directions. As can be seen from the figure, due to network delays, downlink transmissions may occupy channel time exceeding the last D time slot and occur until the maximum transmission boundary falls into the S time slot. Similarly, due to network delays and clock skew, the earliest U transmission may also extend to the maximum uplink transmission boundary. A guard period (GP) can separate the first reference point from the second reference point.

[0069] Figure 3 The middle timeline in shows an example of a 3-slot backoff performed by gNB1, which results in three additional “Xs” (flexible symbols) in slot S.

[0070] The bottom timeline shows the frame structure configuration of gNB2 (the interfered node) corresponding to the backoff case of the middle timeline, showing that the interference has been suppressed due to the introduction of a backoff with a granularity of 3 symbols.

[0071] The methods of various embodiments described below may be used alone or in combination. The terms interfering base station and interfered base station are used here only for the convenience of description, and in some cases, the interfering base station receiving the signal may not interfere with the interfered base station. The interfered base station may be interfered by other base stations, but the interfering base station here receives the signal it sends.

[0072] Example 1

[0073] Interference base station side

[0074] Method 1.1: The interfering base station receives a first reference signal called RIM-RS transmitted by the interfering base station, performs an interference cancellation mechanism, and reduces interference to the interfered base station.

[0075] The reference signal RIM-RS is sent by the interfered base station to determine the source of interference. The interfered base station can measure and analyze the received signal to determine that it has been affected by atmospheric waveguide or far-end interference, thereby triggering the transmission of RIM-RS.

[0076] After receiving the reference signal sent by the interfered base station, the interfering base station determines whether it (usually the downlink of the interfering base station) causes atmospheric waveguide interference or far-end interference to the interfered base station (usually the uplink reception of the interfered base station). If there is interference, the interfering base station performs interference cancellation mechanism.

[0077] Interference cancellation mechanisms may include, for example, downlink back-off (DL back-off), spatial solutions, increasing downtilt angles, lowering site altitudes, etc.

[0078] Downlink backoff may include one or more of the following: time domain backoff, power backoff, frequency domain backoff, and may also include spatial domain solutions, such as no longer transmitting DL in some beam directions.

[0079] Downlink backoff means that downlink data cannot be sent, configured or scheduled on some resources, or the downlink transmission power is reduced.

[0080] For time domain downlink backoff, it specifically refers to resources before the first reference point (or the maximum downlink transmission boundary), so that the first reference point is preceded by a DL symbol or a flexible symbol.

[0081] This document uses time domain downlink backoff as an example, but other backoffs are possible. For example, the method proposed in this document is also applicable to power backoff or frequency domain backoff.

[0082] DL backoff can be performed from the last symbol before the first reference point or the last DL symbol forward. In other words, the symbols used to perform downlink backoff include the last one or more symbols before the first reference point (the last symbol is continuous with the first reference point in time domain), or the last one or more DL symbols (the last DL symbol and the first reference point in time domain may be continuous or discontinuous, depending on the configuration of the time slot structure).

[0083] Here, "the last one or more symbols" means that these symbols are DL symbols, GP symbols or flexible symbols (usually represented by X or F symbols), and cannot be configured as DL or scheduled as DL after the rollback symbol. In the absence of such restrictions, flexible symbols can usually be reconfigured as DL symbols later. Flexible symbols that perform downlink fallback cannot be configured as DL symbols. Unless the downlink fallback is canceled, it can only be a flexible symbol or a GP symbol. For "the last one or more DL symbols", it means that the object of downlink fallback is the DL symbol before the first reference point. Downlink fallback is performed on these DL symbols.

[0084] There are several methods for downlink fallback: In an example implementation, the interfering base station does not schedule DL data transmission on these symbols. Alternatively, or in addition, the interfering base station is silent on these symbols; or the interfering base station reconfigures the time slot format and configures these DL symbols as flexible symbols. Further, these flexible symbols can no longer be reconfigured as DL symbols. The interfering base station reconfigures the time slot format can be configured by the high-level parameters tdd-UL-DL-ConfigurationCommon (and tdd-UL-DL-ConfigurationCommon2), tdd-UL-DL-ConfigDedicated, or by the group common physical downlink control channel PDCCH.

[0085] The granularity of downlink fallback can be as follows:

[0086] Sub-method 1.1.1: The interfering base station receives the RIM-RS and / or timing information transmitted by the interfered base station to determine the number of interfered UL resources and perform DL backoff according to the number of interfered UL resources.

[0087] For example, it is assumed that the interfered base station transmits a signal (RIM-RS) on the last symbol before the first reference point (assuming a=1), and it is assumed that the interfering base station can receive the RIM-RS on the UL symbol.

[0088] In the first step, the interfering base station calculates the transmission delay from the interfered base station to the interfering base station.

[0089] Transmission delay n_delay = the number of symbols n1 between the first reference point and the second reference point + the number of symbols n2 between the first UL symbol in the base station and the second reference point + the sequence number of the UL symbol in the RIM-RS received by the base station. The last term on the right side of the equation is the sequence number (or index) of the UL symbol. For example, the first UL symbol number after the second reference point is 1, and the second UL symbol number is 2. The last two terms can be combined into "the number of symbols in the RIM-RS received by the base station after the second reference point". For example, the first symbol number after the second reference point is 1. The second reference point is also called the maximum uplink reception boundary or the maximum uplink transmission boundary, and the second reference point may be followed by a flexible symbol or a UL symbol.

[0090] In the second step, the interfering base station calculates the number of flexible symbols between the interfering base station DL and the interfered base station UL.

[0091] N_x=the number of symbols n1 between the first reference point and the second reference point+the number of symbols n0 between the first reference point and the last DL symbol of the base station+the number of symbols m2 between the first UL symbol scheduled by the interfered base station and the second reference point.

[0092] The interfered base station is a RIM-RS transmitting base station.

[0093] In the third step, the interfering base station calculates the number of UL resources interfered by the cell.

[0094] N_interfered = n_delay - n_x = the number of symbols between the first UL symbol and the second reference point in the base station n2 + the sequence number of the UL symbol in the RIM-RS received by the base station - the number of symbols between the first reference point and the last DL symbol of the base station n0 - the number of symbols between the first UL symbol and the second reference point scheduled by the interfered base station m2.

[0095] The first two terms in the rightmost operation of the above formula can be combined into "sequence number of the symbol in the RIM-RS received by the base station after the second reference point" and numbered starting from 1.

[0096] If m2 is considered, then interfered = sequence number s2 of the symbol in the RIM-RS received after the second reference point (numbered from the second reference point, starting from 1) - the number of symbols n0 between the first reference point and the last DL symbol of the base station - the number of symbols m2 between the first UL symbol scheduled by the interfered base station and the second reference point.

[0097] If m2 is considered, the above configuration information (the number of symbols m2 between the first UL symbol scheduled by the interfered base station and the second reference point) can be sent by the RIM-RS to the base station or base station group through the RIM-RS scrambling code information or sequence information or timing information when the signal is sent. The timing information can be the transmission period, offset, subframe information / time slot information of the RIM-RS.

[0098] Alternatively, the configuration information is sent by the RIM-RS sending base station or base station group to other base stations through backhaul signaling. The other base stations may be interfering base stations, or other base stations or base station groups to receive RIM-RS, or designated base stations or base station groups.

[0099] If m2 is not considered (assuming = 0 or directly ignoring m2, X is also regarded as an interfered resource, that is, more DL symbols are backed off), the actual interfered = the sequence number s2 of the symbol in the RIM-RS received after the second reference point (numbering starting from the second reference point, starting from 1) - the number of symbols n0 between the first reference point and the last DL symbol of the base station.

[0100] If the interfered base station does not send a signal (RIM-RS) on the last symbol before the first reference point, the configuration information (the number of symbols m0 between the last DL symbol and the first reference point) needs to be notified to the interfering base station or the interfering base station group. The notification method is the same as the above m2 notification method.

[0101] Sub-method 1.1.2: The interfering base station receives a reference signal (RIM-RS) transmitted by the interfered base station and performs interference cancellation mechanisms, such as DL backoff, according to a configured granularity or a preset granularity.

[0102] The atmospheric waveguide interference experienced by the interfered base station (UL reception) is likely to be the superposition of interference from multiple interfering base stations. Sometimes, it is difficult for the interfered base station to calculate the exact number of interfered resources based on the received reference signal. For example, in sub-method 1, it is necessary to notify the interfering base station of the configuration information m2 and / or m0 of the interfered base station, but there are certain difficulties whether through the air interface or the return signaling. In addition, for the power domain backoff or power domain method, it is difficult for the interfering base station to determine how much power needs to be reduced at the beginning. Therefore, the interfering base station receives the RIM-RS sent by the interfered base station and performs DL backoff according to the configured granularity or the preset granularity.

[0103] The granularity of configuration or preset granularity for DL ​​symbol backoff can be 1 symbol or multiple symbols, or 1 dB or more dB power reduction, or frequency domain backoff of one RB or multiple RBs, or frequency domain backoff of one sub-band or multiple sub-bands, or frequency domain backoff of one BWP (partial bandwidth) or multiple BWPs. The granularity setting or configuration can be set or configured by OAM, S1 / NG, X2 / Xn. The granularity can be a configured or preset fixed value.

[0104] Therefore, in some embodiments, the interfered base station sends interference status information to the interfering base station. For example, this interference status information may omit sending a specific amount of backoff to be performed by the interfering base station.

[0105] Preferably, after the interfered base station receives the reference signal RIM-RS2 sent by the interfering base station (RIM-RS2 is sent by the interfering base station to confirm whether the atmospheric waveguide phenomenon still exists), or after the interfered base station receives the information detected by RIM-RS through the backhaul, the interfered base station sends the interference state information to the interfering base station. Alternatively, after the interfering base station performs an interference elimination mechanism (such as downlink backoff), the interfered base station transmits the interference state information to the interfering base station.

[0106] The interference status information includes at least one of the following: confirmation ACK (or no interference), negative NACK (or interference still exists), interference level, the number or duration of interfered resources, the value of the reduction in the granularity of continued adjustment (e.g., the number of symbols used for backoff, power), the frequency domain granularity of backoff, whether RIM-RS2 is received, and whether there is an atmospheric duct phenomenon.

[0107] The interference status information may be sent by the interfered base station to the interfering base station via the air interface (e.g., reusing RIM-RS, or new signals such as RIM-RS3), backhaul signaling (X2, Xn, S1 or NG signaling), or via OAM configuration.

[0108] RIM-RS3 may be a new signal different from RIM-RS or RIM-RS2 (for example, different from the RIM-RS or RIM-RS2 sequence or the generation parameters of the sequence; or the same as the RIM-RS or RIM-RS2 sequence, but with different configured parameters), and RIM-RS3 has a separate set of configuration parameters (period, offset, duration, time domain and frequency domain position, timing relationship, one or more of the above parameters).

[0109] After receiving the interference status information, the interfering base station selects at least one of the following operations: keeping the existing interference cancellation mechanism unchanged, further performing interference cancellation, and stopping the execution of the interference cancellation mechanism.

[0110] For example, the interference cancellation mechanism performed by the interfering base station is to back off 3 DL symbols (e.g., Figure 3 If the interfering base station receives the interference status information (ACK), the existing scheme of "backing off 3 DL symbols or reducing the DL transmit power by 3dB" is maintained. If the interfering base station receives the interference status information (NACK), the base station can continue to back off 1 DL symbol or reduce the DL transmit power by 1dB on the basis of "backing off 3 DL symbols or reducing the DL transmit power by 3dB". If the interfering base station receives the interference status information (but does not receive RIM-RS2 or the atmospheric duct phenomenon does not exist), it can be concluded that the duct phenomenon does not exist, and the interfering base station stops performing the interference cancellation mechanism.

[0111] The first interference cancellation mechanism performed after receiving the RIM-RS transmitted by the victim and the second interference cancellation mechanism performed after receiving the interference status information may be different. For example, the method in the first time is a DL symbol backoff in the time domain DL. However, the method used in the first time is a solution based on the frequency domain or a solution based on the implementation.

[0112] In order to reduce the signaling overhead exchanged between the interfered base station and the interfering base station, the number of transmissions of the interference status information can be limited to once, twice or several times. Accordingly, the number of interference cancellations performed on the interfering side can be limited to once, twice or several times.

[0113] Interfered base station side

[0114] 1. Corresponding to the first method 1 (method 1.1) in embodiment 1, before the interfering base station performs an interference cancellation mechanism (such as downlink backoff), the interfered base station performs the following operations.

[0115] The configuration information (the number of symbols m2 from the first UL symbol of the RIM-RS transmitting base station to the second reference point) may be carried by the interfered base station (RIM-RS transmitting base station) or the interfered base station group through the scrambling code information, sequence information, or timing information of the RIM-RS. The timing information may be the transmission period, offset, subframe information / time slot information, etc. of the RIM-RS.

[0116] Alternatively, the aforementioned configuration information is sent by the interfered base station or the interfered base station group to the interfering base station or the interfering base station group through backhaul signaling or OAM. The backhaul signaling may include X2, Xn, S1 or NG signaling.

[0117] If the interfered base station does not send a signal on the last symbol before the first reference point, it is necessary to notify the interfering base station or the interfering base station group of the configuration information (the last DL symbol of the RIM-RS sending base station starting from the first reference point symbol number m0). The notification method is the same as the above m2 notification method.

[0118] 2. Corresponding to the second method of the first embodiment, after the interfering base station performs an interference cancellation mechanism (eg, downlink backoff), the interfered base station performs the following operations.

[0119] The interfered base station sends interference cancellation status information to the interfering base station.

[0120] Preferably, after the interfered base station receives the reference signal RIM-RS2 sent by the interfering base station (RIM-RS2 is sent by the interfering base station to confirm whether the atmospheric waveguide phenomenon still exists), or after the backhaul message, the interfered base station sends the interference status information to the interfering base station. Alternatively, after the interfering base station performs an interference elimination mechanism (such as downlink backoff), the interfered base station sends the interference status information to the interfering base station.

[0121] The interference status information includes at least one of the following: confirmation ACK (no interference), negative NACK (interference still exists), interference level, the number or duration of interfered resources, the granularity of continued adjustment (for example, the number of symbols used for backoff, power backoff value, frequency domain granularity of backoff), and whether RIM-RS2 is received.

[0122] The interference cancellation status information may be configured by the interfered base station through an air interface (eg, RIM-RS or RIM-RS3), backhaul signaling (X2, Xn, S1 or NG signaling), or through OAM.

[0123] RIM-RS3 may be a new signal different from RIM-RS or RIM-RS2 (for example, different from the RIM-RS or RIM-RS2 sequence or the generation parameters of the sequence; or the same as the RIM-RS or RIM-RS2 sequence but with different configuration parameters). RIM-RS3 has a separate set of configuration parameters (one or more of the parameters such as period, offset, duration, time domain and frequency domain position, timing relationship, etc.).

[0124] Embodiment 2: In this example, the base station transmits RIM-RS and / or RIM-RS2.

[0125] For larger subcarrier spacing, the transmission delay of 300 km between base stations corresponds to more OFDM symbols (e.g., for 300 km, 14 OFDM symbols require 14 15kHz subcarrier spacing. If it is 30kHz, 28 OFDM symbols are required). In this way, after the RIM-RS sent by the interfering base station is delayed (through the flexible symbol and the UL time slot of 14 symbols), it may fall on the DL time slot of the interfering base station. Because the interfering base station is likely to detect the RIM-RS only on the UL symbol or the flexible symbol.

[0126] In order to detect the RIM-RS sent by the interfered base station on the uplink symbol of the interfering base station, the interfered base station configures the transmission resources of the RIM-RS at several specific locations, or at least sends the RIM at several specific locations. The specific location includes at least one of the following items:

[0127] The last symbol before the first reference point is also called the downlink transmission boundary, which is continuous with the first reference point in the time domain. That is, the first symbol is before the first reference point. RIM-RS can be transmitted on one or more symbols. If RIM-RS is transmitted on multiple symbols, at least the last symbol is included. The last symbol is sent to ensure that the short-range base station can receive RIM-RS on UL symbols and flexible symbols.

[0128] The last Nth symbol (N is not equal to 1) before the first reference point can be as follows. N may depend on the subcarrier spacing, the transmission distance / transmission delay, the number of flexible symbols after the first reference point, the first reference point to the next complete UL slot, one or other factors (such as the number of UL symbols, the number of symbols in the UL slot, etc.). For example, for a transmission distance of 300km and a subcarrier spacing of 30kHz, the number of flexible symbols after the first reference point is 3, the number of UL symbols from the first reference point to the next complete UL slot is 2, and the number of symbols in the UL slot is 14. Then N=14*2-3-2-14+1=10.

[0129] The RIM-RS transmission method is also applicable to RIM-RS2. For the interfered base station, RIM-RS2 is sent by the interfering base station to confirm whether the atmospheric ducting phenomenon still exists.

[0130] Embodiment 3: The base station sends RIM-RS or RIM-RS2.

[0131] This embodiment describes several implementations of how ID information is carried by RIM-RS or RIM-RS2.

[0132] In the LTE scheme, a 10ms radio frame includes two 5ms periods (subframes or transmission time intervals), and the RIM-RS is transmitted in the upper and lower fields respectively, and the 3-bit gNB ID information (through 8 sequences) can be carried in each field. In the upcoming New Radio (NR) based technology, the dl-UL-TransmissionPeriodicity of NR is flexible: it can include values ​​from {0.5, 0.625, 1, 1.25, 2, 2.5, 5, 10} milliseconds, and two dl-UL-TransmissionPeriodicity modes P and P2 can be supported. The sum of the periods (P+P2) can be divided into separate parts. P and P2 are two periods that are connected end to end in the transmission along the timeline. For example, P=3ms, P2=2ms, then the 20ms period can be divided into {P, P2, P, P2, P, P2, P, P2}.

[0133] In some embodiments, the RIM-RS unit time (e.g., 5 ms, 10 ms, or 20 ms) is divisible by P+P2, that is, it includes an integer number of P+P2 periods, or n1 RIM-RS opportunities. In some embodiments, the RIM-RS unit time (e.g., 5 ms) is divisible by P, that is, it includes an integer number of P periods, or n2 RIM-RS opportunities. The RIM-RS unit time may also be a period different from P and P2, generally greater than P and P2, for example, a RIM-RS transmission period.

[0134] As mentioned above, the reference signal transmission is performed at different transmission opportunities (symbols) along time. Some example embodiments of how to send RIM-RS in time units include:

[0135] Method 3.1: The same RIM-RS is sent at all times, and the same RIM-RS carries the same ID information (gNB ID or gNB group ID).

[0136] Method 3.2: Different RIM-RS are sent at all opportunities, and the different RIM-RS carry different ID information.

[0137] Method 3.3: The same RIM-RS is transmitted at the time in period P, and these RSs carry the same ID information. The same RIM-RS carrying the same ID information is transmitted at the time in period P2, and the same RIM-RS carries the same ID information. However, different RIM-RS carrying different ID information are transmitted at the time in period P and P2, and the different RIM-RS carry different ID information.

[0138] If there is only one occupancy in period P and only one occupancy in period P2 per unit time, then different RIM-RS are sent at these two times, and these RS carry different ID information. The above method can be illustrated by example. For example, RSs in different times may carry part of the ID information (gNB ID or gNB group ID). For example, the total number of a gNB ID is 20 bits. RSs in different times can only carry a 4-bit portion of the ID. If there are four times in the time period, method 3.1 can be implemented so that the transmission at each time carries the same 4 bits (the remaining bits can be transmitted in another time period). Using method 3.2, each time can carry a single bit, but this bit can transmit the entire ID, one bit at a time. Using method 3.3, the ID can be divided into M bit parts and repeated M times. For example, two times can carry the same 2 bits, the other two times can carry another 2 bits, and so on.

[0139] For method 3.2 or method 3.3, how the receiving base station splices together the ID information belonging to the same sending base station or sending base station group can be performed in many different ways. For example, the power difference of the RIM-RS sent by the same base station at different times should be less than a certain threshold. If the power difference of the RIM-RS is greater than this threshold, the receiving base station can abandon splicing. If the receiving base station still obtains multiple splicing results even when performing splicing according to the threshold, the use of splicing can be suppressed.

[0140] The UL-DL transition period corresponding to the RIM-RS transmission opportunity in NR is configurable. If the RIM-RS transmission period matches the UL-DL mode transition, only one opportunity is used for RIM-RS transmission, such as Fig.13 If it is multiple (e.g., M>1), the UL-DL switching period is configured in the RS transmission period, such as Fig.13 (b) to Fig.13 (d) as shown.

[0141] There are many ways to pass ID information.

[0142] Method 1: Fig.13 As shown in (b), the same generated sequence is used at different times, which can improve the detection performance through repetition while transmitting less ID information.

[0143] Method 2: If Fig.13 As shown in (c), in order to convey more information, a different generation sequence is used for each opportunity. The disadvantage is that the detection is more than once.

[0144] Method 3: With Fig.13 (c) Different, Fig.13The RS in (d) is repeated at each opportunity. So the method for sending RIM-RS depends on the ID length, RS transmission period and UL-DL switching period.

[0145] Example 4: Unified Design of RIM-RS and RIM-RS2

[0146] As described in other embodiments, after the interfered base station confirms that it is interfered by the atmospheric duct, it sends a RIM-RS for confirming the interference source. After receiving the RIM-RS, the interfering base station sends a RIM-RS2 to the interfered base station, and the interfered base station confirms whether the atmospheric duct phenomenon still exists.

[0147] The RIM-RS transmission method in the second embodiment is also applicable to RIM-RS2.

[0148] In order to reduce the design complexity and detection complexity of the two signals, the following methods are designed (the following methods can be combined):

[0149] Method 4.1: Configure a dual period, send RIM-RS in one period, and send RIM-RS2 in another period. With this duty cycle-based implementation, the two reference signals can be based on a saved waveform, but their appearance in a predefined time opportunity can define whether it is a RIM-RS or RIM-RS2 transmission. For example, RIM-RS is sent during the period configured by tdd-UL-DL-ConfigurationCommon, and RIM-RS2 is sent during the period configured by tdd-UL-DL-ConfigurationCommon2; the above two parameters are advanced parameters used to configure the time slot format in 3GPP TS38.331-f30.

[0150] Further, RIM-RS and RIM-RS2 may be configured with a same transmission period, wherein RIM-RS and RIM-RS2 are transmitted in two different small periods (e.g., tdd-UL-DL-ConfigurationCommon and tdd-UL-DL-ConfigurationCommon2). The two periodic small periods may be connected end to end. RIM-RS or RIM-RS2 may be transmitted only once or multiple times in a small period, a large period, or each small period.

[0151] Method 4.2: Configure the same reference signal transmission period, but configure different offsets for each reference signal. RIM-RS and RIM-RS2 are distinguished by different offsets to avoid conflict and interference.

[0152] Method 4.3: RIM-RS and RIM-RS2 are configured with different transmission periods, and there is a multiple relationship or a certain functional relationship between their periods, for example, n1*T1=n2*T2, where T1 / T2 are the periods of RIM-RS / RIM-RS2 respectively, and n1 and n2 are positive integers. In other words, RIM-RS and RIM-RS2 are configured with different transmission densities (or their resource densities are different). For example, the resource configuration or transmission density of RIM-RS is higher, while the resource configuration or transmission density of RIM-RS2 is lower, and the resource configuration or transmission mode of RIM-RS2 is a subset of RIM-RS.

[0153] The detection period or detection mode of the RIM-RS and the RIM-RS2 is the same as that of the first method, the second method or the third method.

[0154] Example 5

[0155] In this embodiment, for NR RIM RS (RIM-RS or RIM-RS2 or RIM-RS3) design, the time domain cyclic characteristic should be satisfied. In the current 3GPP research, there are three alternatives for NR RIM RS design. The first alternative is 1 symbol RS. The second alternative and the third alternative are multiple symbol RS (e.g., 2 symbols) RIM-RS, and both of them have multiple continuous sequences (e.g., 2 sequences). The details are as follows.

[0156] Alt 1: RS of 1 symbol uses the existing CSI-RS having a comb structure in the frequency domain;

[0157] Comb factors = 2 and 4;

[0158] Alt 2: RS of multiple (e.g., 2) symbols, where multiple (e.g., two) copies of the RS sequence are concatenated and a CP (cyclic prefix) is attached at the beginning of the concatenated sequence;

[0159] Alt 3: RS of multiple (e.g., 2) symbols, where a CP is added to the front of the first OFDM symbol and a suffix is ​​added to the end of the last OFDM symbol.

[0160] In the following, we present a method for Alt 2 and Alt 3 that can use the same FFT as for PDSCH generation.

[0161] The traditional PDSCH in one symbol is generated in Fig.14 Shown in.

[0162] The CP of Alt-2 is attached as Fig.15(a) at the beginning of the concatenated sequence, while the CP of Alt-3 was added at Fig.15 (c) at the beginning and end of the cascade sequence shown. Obviously, Fig.15 Method (a) for Alt-2-1 and Fig.15 Method-3 for Alt-3 in (c) cannot use the same FFT as PDSCH generation.

[0163] In order to reuse FFT for PDSCH generation and keep the time domain cyclic property, a Fig.15 Alt-2 and Fig.15 (d) The OFDM baseband generation method of Alt-3.

[0164] The first part of the original CP in the first symbol is still used as the CP, and the other part of the original CP is used as data / sequence. And / or,

[0165] The data / sequence at the beginning of the second symbol and / or the following symbols is used as the CP.

[0166] For example, in Fig.15 In (a), in method-1 for Alt-2, the last four symbols at the end of the second symbol are attached as the original CP at the beginning of the concatenated sequence. Obviously, this symbol generation cannot be like Fig.14 FFT is reused as shown in the PDSCH generation. Fig.15 (b), Fig.15 Part of the original CP in (a) (the first two symbols) is still used as the CP, but the other part (i.e. Fig.15 (a) the last two symbols of the original CP are used as data / sequence. Further, the first two symbols of the data / sequence that were originally the second symbol are used as CP.

[0167] Meanwhile, for Method 2 and Method 4, different OFDM symbols (eg, the second symbol) should be multiplied by different linear phase factors in the frequency domain, or should be cyclically shifted in the time domain.

[0168] In addition, for Alt 2: 2-symbol RS, two copies of the RS sequence are concatenated and a CP is attached at the beginning of the concatenated sequence;

[0169] Method 1: In the frequency domain, RIM-RS in different OFDM symbols need to be multiplied by different linear phase rotation factors.

[0170] Method: In the frequency domain, RIM-RS in different OFDM symbols do not need to be multiplied by different linear phase rotation factors.

[0171] Figure 4 4 is a block diagram representation of a portion of a radio station. A radio station 405, such as a base station or a wireless device (or UE), may include a processor electronics 410 such as a microprocessor that implements one or more of the wireless technologies presented in this document. The radio station 405 may include a transceiver electronics 415 to send and / or receive wireless signals through one or more communication interfaces, such as an antenna 420. The radio station 405 may include other communication interfaces for sending and receiving data. The radio station 405 may include one or more memories (not explicitly shown) configured to store information, such as data and / or instructions. In some embodiments, the processor electronics 410 may include at least a portion of the transceiver electronics 415. In some embodiments, the radio station 405 is used to implement at least some of the disclosed techniques, modules, or functions.

[0172] Figure 5 5 is a flow chart of an example method 500 for wireless communication. The method 500 includes: receiving (502) interference state information indicating long-range interference between the first communication node and a second communication node at a first communication node; and performing (504) subsequent communication by the first communication node to the second communication node by implementing a backoff based on granularity. For example, the method 500 can be implemented by an interfering base station in a wireless system.

[0173] Another wireless communication method includes: sending, by a first communication node, a first reference signal indicating the presence of long-range interference between the first communication node and a second communication node, wherein a time domain position of the first reference signal includes one of the following: the last symbol before a maximum downlink transmission boundary for transmission between the first communication node and the second communication node, or the Nth symbol before a transmission boundary, wherein N is an integer greater than 1.

[0174] Another wireless communication method includes: sending, by a first communication node, a first reference signal indicating the presence of long-range interference between the first communication node and a second communication node, wherein the first reference signal is sent in a preconfigured time period, and wherein the first reference signal is sent at multiple times in each time period; and using the first reference signal to transmit ID information associated with the first communication node.

[0175] Another wireless communication method includes transmitting from a first communication node a first reference signal associated with a first interference on an inbound channel to the first communication node and a second reference signal associated with a second interference on an outbound channel from the first communication node. The first reference signal and the second reference signal are sent in a non-overlapping manner.

[0176] In some embodiments, the first communication node and the second communication node may be a base station (gNB), and may use Figure 4 The hardware platform described is used for implementation.

[0177] The following description may be used to explain example embodiments of the applicability of the disclosed technology to the upcoming 5G standard.

[0178] 1. Terminology

[0179] The following description of the framework uses the term "victim" for a communication node that is interfered with, and the term "attacker" for a communication node that interferes with.

[0180] 2. Discussion on the framework

[0181] The RIM framework is an essential part of studying the start / end mechanism of RS transmission and RIM operation in scenario #1 and scenario #2. Several RIM frameworks were identified in the RAN1#94 meeting as starting points for RIM research [3]. Due to time constraints and the complexity of standardization, we believe that further studying their pros and cons while focusing on only a few simple frameworks is reasonable for future specification work in Rel-16. In the following sections, we give our views on each RIM framework.

[0182] 2.1 Framework-0

[0183] Figure 6 An example workflow for Framework-0 is shown.

[0184] The common point of Framework-0 / 1 / 2.1 / 2.2 is that the victim gNB must first confirm in step 0 that it is interfered by RI (remote interference), such as Figure 1 As shown, and then sends a reference signal to the attacker in step 1. Specifically, if the IoT level on the victim side exceeds a threshold and exhibits some long-range interference characteristics (e.g., like an increased "tilt" of IoT), the victim can infer that it is interfered with by RI and will trigger an event, i.e., start RS transmission. The measurement mode of IoT for identifying RI can be considered or left to be implemented.

[0185] Most of the following RIM steps after step 1 in Framework-0 are operations of gNB and OAM, including the attacker reporting the detected RS to OAM, OAM sending the RI suppression scheme to the attacker, the attacker applying the scheme, and OAM stopping RS transmission / detection and restoring the original configuration. These processes can be implemented by implementation, so the standardization complexity of Framework-0 is minimal.

[0186] 2.2 Framework-1

[0187] Figure 8 An example workflow for Framework-1 is shown.

[0188] In scenario #1 with symmetric IoT addition, the attacker is also the victim. Same as the victim side, it can trigger the same events through IoT measurements and analysis (i.e., RS-1 transmission and RS-2 monitoring). In addition, the victim and attacker also need to trigger RS-1 monitoring to detect RS-1 transmission between each other. If the victim (also acting as the attacker) and the attacker (also acting as the victim) adopt the same triggering strategy, the events they trigger should be consistent. No matter who triggers the event, it should be included in step 1: RS-1 transmission, RS-2 monitoring, RS-1 monitoring.

[0189] In scenario #2 with asymmetric IoT addition, the IoT level suffered by the attacker may be below the threshold, while the total IoT level at the victim exceeds the threshold. In this case, the RS-1 monitoring in step 1 cannot be triggered by IoT, but can only be triggered by OAM configuration. Periodic monitoring or event triggering can be considered. Some of the field test results and conclusions can be used as input to assist OAM configuration.

[0190] Observation 1: The following was observed for Scenario #1 and Scenario #2:

[0191] At least for scenario #1 with symmetric IoT addition, if the victim and attacker adopt the same triggering strategy (e.g., by IoT level and characteristics), the events triggered at the victim and attacker can be consistent.

[0192] In scenario #2, RS monitoring in step 1 cannot be triggered dynamically through IoT measurements, but can be triggered through OAM configuration.

[0193] RS-1 is used to assist attackers in realizing that they are causing long-range interference to the victim and to deduce how much of the victim's UL resources are affected by the attacker. If the attacker knows the ID information of the victim gNB or the gNB group to which the victim belongs, it can perform more relevant RIM suppression schemes, such as adjusting the antenna downtilt. Moreover, considering the forward compatibility of the framework, the RS-1 in the framework-1 should also carry the gNB ID or group ID information. The RS-1 transmission mode should be configurable to meet different requirements, such as overhead, delay, and less collisions. The RS-1 detection mode should also be carefully designed to meet the detection performance, reduce the detection complexity, and avoid the impact on the existing UL signal reception.

[0194] Observation 2: Considering forward compatibility and various possible RI suppression schemes, RS-1 in frame 1 carrying gNB ID or group ID information is necessary.

[0195] RS-1 is a critical / essential part of the whole process for long-range interference management. Considering the difficulty in reusing existing reference signals to meet the detection requirements, it is necessary to introduce a dedicated reference signal for RIM. More details on the RIM-RS design can be found in our companion contribution [4].

[0196] If RS-1 is detected, the attacker will realize that it is causing RI to the victim and deduce how much UL resources of the victim are affected. The attacker should then perform a corresponding long-range interference mitigation scheme (step 2), such as DL backoff, which will be further discussed in Section 3. Moreover, the attacker will send RS-2 (step 2), which is used to help the victim determine whether the atmospheric ducting phenomenon still exists.

[0197] If the victim receives RS-2 sent in step 2, it is determined that the atmospheric duct phenomenon still exists. In this case, the victim should continue to send RS-1. Correspondingly, if the attacker receives RS-1 sent by the victim, it continues to perform the RI suppression scheme, sends RS-2, and monitors RS-1. If the atmospheric duct phenomenon persists, the victim and the attacker always perform a loop between them.

[0198] The victim may not be able to detect RS-2, either because the attacker did not send RS-2 due to the inability to detect RS-1, or because even if the attacker has sent RS-2, RS-2 arrives at the victim side with little energy due to the atmospheric ducting phenomenon having weakened or disappeared. If RS-2 cannot be detected for a certain period of time, and the IoT returns to a certain level, the victim will determine that the atmospheric ducting phenomenon has disappeared, and then it can stop RS-1 transmission and RS-2 monitoring (step 3).

[0199] If RS-1 cannot be detected within a certain period of time due to similar reasons as in step 3, the attacker will determine that the atmospheric ducting phenomenon has disappeared, and then it can stop RS-2 transmission and RS-1 monitoring and restore the original configuration before RIM operation (step 4).

[0200] The above termination mechanism mainly depends on the transmission and detection of RS-1 and RS-2. Another simple and feasible solution is: once the attacker receives RS-1 and then executes the RI suppression scheme, it can start a timer. If the timer does not expire, the attacker will always execute the suppression scheme. Otherwise, the attacker can terminate the RI suppression scheme and restore the original configuration. On the victim side, if the IoT increase exhibits a "tilted" characteristic in the time domain, the victim will continue to transmit RS-1. Otherwise, the victim can stop RS-1 transmission.

[0201] Based on the analysis of RS-1 in step 1 and RS-2 in step 2, we can see that the functions of RS-1 and RS-2 may be different, so they may have different designs. In order to reduce the complexity of NR-RIM standardization, the necessity of RS-2 transmission needs to be further evaluated. For example, a timer can be used instead of RS-2 transmission to implement the RI suppression scheme and the termination of RS-1 transmission.

[0202] Based on the above, it seems that RS-2 transmission is not necessary in Framework-1. RAN1 should study whether a single RS can handle both functions, or at least strive for a common RS design for both RSs as much as possible. Otherwise, alternatives such as a timer-based solution should be considered for Framework-1.

[0203] Recommendation 1: RAN1 should evaluate the necessity of RS-2 transmission in Framework 1 from the perspective of RS design and standardization complexity:

[0204] If yes, RAN1 should strive for a common design for RS-1 and RS-2.

[0205] Recommendation 2: A timer based scheme should be considered as an alternative to RS-2 of the gNB to terminate RS transmission / monitoring and RI suppression scheme operation.

[0206] 2.3 Framework-2.1

[0207] Figure 8 An example workflow for Framework-2.1 ​​is shown.

[0208] The main difference from Framework-1 is that the attacker in Framework-2.1 ​​informs the victim of the state of the atmospheric waveguide phenomenon via backhaul signaling, rather than via RS-2 transmission / monitoring (or timer-based as we proposed in Section 2.1). Framework-1 has lower standardization complexity and is easier to implement in commercial networks. For these reasons, we slightly prefer Framework-1 if it works well.

[0209] RS in Framework-2.1 ​​needs to transmit the victim gNB ID or group ID information for victim identification and inter-gNB communication through the backhaul. If the attacker needs to identify the unique ID of the victim gNB through RS detection within the coverage area of ​​300km radius, the sequence and timing of RS sent by the victim gNB needs to carry at least 20 bits of gNB ID information. Alternatively, if RS directly carries CGI, cellIdentity or gNB ID in cellIdentity, it needs to transmit more bits of ID information to the attacker. Carrying the complete gNB ID through RIM-RS poses challenges to the sequence design, transmission timing and detection performance of RIM-RS. One possible approach is that the operator can assign group IDs to one or more gNBs that are frequently interfered or interfered by other gNBs based on some historical data. Since the number of groups is much smaller than the number of gNBs, the RS sent by the victim gNB can only contain the group ID. However, the division of groups, group numbering, and group information exchange should be further studied. For more details on the design of RIM-RS, please refer to the contribution [4].

[0210] Recommendation 3: Regardless of the chosen framework, RIM-RS should convey the victim gNB ID or group ID information for victim identification and inter-gNB communication.

[0211] 2.4 Framework-2.2

[0212] Fig. 9 An example workflow for Framework-2.2 is shown.

[0213] Both Framework 2.1 and Framework 2.2 require the attacker to notify the victim about the reception or disappearance of the RS through the backhaul. The difference between Framework 2.1 and Framework 2.2 is that the former is a one-way backhaul signaling transmission from the attacker to the victim, while the latter is a two-way backhaul signaling communication.

[0214] “Step 3: Send information to assist RIM coordination” may depend on the final design of RIM-RS and what type of RI suppression scheme the network adopts. For example, if the attacker can infer how much of the victim’s UL resources are affected based on RS detection, the victim does not need to send information related to DL backoff or interfered symbols to assist RIM operation. Since the final design of RIM-RS has not yet been completed and the RI suppression scheme adopted by the gNB is unclear, it is difficult to determine what coordination information the victim must send to the attacker at this stage. Therefore, like RAN3, in step 3 of framework 2.2 [7], we are unclear about the benefits and content of the RIM coordination assistance information.

[0215] Observation 3: Compared with framework-2.1 ​​and framework-2.2, framework-0 and framework-1 have lower normalization complexity and are easier to implement.

[0216] Recommendation 4: Among the possible frameworks identified in RAN1#94, we have the following recommendations:

[0217] The design of RS and / or backhaul signaling should be designed to support one or more preferred frameworks (e.g., framework-0 / 1 / 2.1), and the framework applied in commercial networks can be left to the operator / vendor.

[0218] 3. Potential mechanisms for improving network robustness

[0219] 3.1 Time Domain-Based Solution

[0220] 3.1.1 Solutions implemented through network implementation

[0221] The victim gNB can reduce the number of uplink symbols, such as Fig.10 As shown (left), or the attacker gNB can reduce the number of downlink symbols, such as Fig.10 As shown in (middle), or the gNBs on both sides perform UL&DL backoff, such as Fig.10 Shown (right).

[0222] Fig.10 Examples of time domain methods for RI suppression only on the victim side (left), only on the aggressor side (middle), and suppression on both sides (right) are shown.

[0223] The first method for reducing the number of interfered UL symbols or interfering DL symbols is to reconfigure the slot format. The NR slot format is more flexible and can be reconfigured through the higher layer parameters tdd-UL-DL-ConfigurationCommon (and tdd-UL-DL-ConfigurationCommon2), tdd-UL-DL-ConfigDedicated or via the group common PDCCH, etc. The victim gNB can reduce the number of UL symbols through the higher layer parameters nrofDownlinkSymbols or nrofDownlinkSlots. Unless RIM suppression is terminated, the flexible symbols before the interfered UL symbols cannot be reconfigured as UL symbols. Similarly, the aggressor gNB can reduce the number of DL symbols through the higher layer parameters nrofUplinkSymbols or nrofUplinkSlots. The flexible symbols after the interfering DL symbols cannot be reconfigured as DL symbols.

[0224] Alternatively, the victim gNB can avoid scheduling the interfered UL symbols for UL transmission. The victim gNB can also schedule larger transport blocks as CBGs, where the first one or more CBGs may not be decoded correctly due to long-range interference, while the later CBGs may be correct. Small transport blocks can be considered to be transmitted on symbols with low interference. The aggressor gNB can perform DL symbol backoff, i.e., mask the interfering DL symbols, or avoid scheduling the interfering DL symbols for DL ​​transmission. The above scheduling-based approach is transparent to the UE.

[0225] Both slot format reconfiguration and scheduling-based methods for RI suppression may be implemented by existing NR specifications or network implementations, but determining the number of downlink symbols on which an attacker performs DL symbol backoff or non-scheduling may have specification impact.

[0226] Note that if the RIM suppression solution is performed on the victim / aggressor gNB side, the uplink / downlink throughput of the victim / aggressor gNB will be affected. Relatively speaking, the impact on the uplink may be more severe. Taking a subcarrier spacing SCS of 15kHz as an example, in a typical TDD macro deployment scenario, the UL part in a 5ms DL-UL switching cycle is usually only a little longer than one slot of 1ms. Long-range interference from a remote aggressor gNB up to 300km away may interfere with most UL symbols (14 - the number of flexible symbols after the first reference point). The time domain method performed only at the victim side has a great impact on the UL performance and DL HARQ_ACK latency. Therefore, if the time domain method is adopted, RIM should not rely entirely on the victim itself, but on the aggressor or both.

[0227] 3.1.2 Solutions with 5G Specification Impact

[0228] There are several methods to determine the number of downlink resources on which an attacker needs to perform DL symbol backoff or non-scheduling, some of which have no normative impact, but some other methods have normative impact.

[0229] In the first approach, the number of downlink resources is set based on the maximum distance between the victim gNB and the aggressor gNB of 300km (1ms time delay), regardless of the actual distance. This means that the aggressor gNB will configure a large enough GP to reduce the long-range interference to the victim. As long as the aggressor gNB detects RIM-RS, if they all have the same slot format, they perform a time domain based solution on the same number of downlink resources. This approach has no additional impact on the standard (except RIM RS), but it greatly sacrifices downlink throughput.

[0230] To more precisely and adaptively perform the time-domain method on the attacker side, the second approach is that the attacker gNB detects / infers how much UL resource of the victim is affected by the attacker. The RAN1 convention in the RAN1#94bis meeting:

[0231] It is expected that the gNB will not receive the RS before the DL transmission boundary and will not send the RS after the UL reception boundary either.

[0232] The transmission positions of RIM RS-1 in Frame 1 and the RS in Frame 2 are fixed in the last X symbols before the DL transmission boundary, that is, the end boundary of the transmitted RIM-RS is aligned with the first reference point.

[0233] Suppose there are two gNBs (e.g., Fig.11 gNB1 and gNB2 in ), and the two gNBs comply with the above rules. However, since the number of flexible symbols before the first reference point and after the second reference point may be different for two long-distance gNBs, the following problems may occur when the gNB detects the RIM-RS and infers how many UL interfered resources there are. These problems need to be considered when applying the time-domain method and designing the RIM-RS on the attacker side.

[0234] gNB1 does not interfere with gNB2, but gNB2 is interfered by other gNBs. gNB1 receives the RIM-RS from gNB2 on its UL symbols.

[0235] gNB1 interferes with gNB2 on N UL symbols, but gNB1 receives the RIM-RS from gNB2 on N+M (M>0) UL symbols.

[0236] gNB2 interferes with gNB1 on N UL symbols, but gNB2 cannot receive any RIM-RS on its UL symbols.

[0237] gNB2 interferes with gNB1 on N UL symbols, but gNB2 receives the RIM-RS from gNB1 on N-M (0<M<N) UL symbols.

[0238] To avoid the above problems and more precisely calculate the number of UL interfered resources, the attacker gNB needs to know the slot format configuration of the victim gNB, such as the number of flexible symbols between the second reference point and the first UL symbol.

[0239] Considering that NR may adopt a subcarrier spacing higher than 15kHz (e.g. 30kHz), the maximum distance of 300km between two GNBs corresponds to more symbols with the same transmission delay. The RIM-RS sent by the victim gNB may appear in the DL slot on the attacker gNB side in the next DL-UL switching period, and after the first reference point in this DL-UL switching period, it cannot be detected by the attacker gNB in ​​flexible symbols or UL symbols. So RAN1 should further study the transmission position of RIM-RS, such as how to configure these last X symbols before the first reference point.

[0240] Previously discussed Figure 3 Depicted are examples of DL and UL transmission boundaries within a DL-UL transmission period.

[0241] The third way is that the attacker gNB performs DL backoff with a smaller fixed or configurable granularity (e.g., one or more symbols). In this method, the attacker gNB does not need to calculate the number of interfered UL resources based on the detected RIM RS, which is similar to the first way. When the victim gNB receives RS-2 in frame-1 or receives backhaul signaling in step-2 of frame-2.1 / 2.2, the victim gNB sends RI suppression state information (RIM-SI) to the attacker gNB through the air interface or backhaul signaling. RIM-SI may include: ACK (no RI), NACK (RI still exists), the number of interfered UL symbols, etc. If the attacker gNB receives RIM-SI, it decides whether to maintain the existing suppression scheme unchanged, or continue to perform DL backoff in more symbols, or even stop the suppression scheme. RIM-SI can also be used in the second way to help the attacker gNB perform RIM suppression better.

[0242] Recommendation 5: Several methods exist to determine the amount of DL resources on which an attacker needs to perform time-domain based solutions (such as DL symbol backoff or unscheduling):

[0243] Option 1 is set based on a distance of 300km (1ms time delay), regardless of the actual distance between the victim and the attacker.

[0244] Option 2 The attacker infers how much of the victim's UL resources are affected by the attacker, but some of the victim's slot format configuration information needs to be notified to the attacker.

[0245] Option 3 reduces long-range interference step by step. Each step is performed only at a small fixed or configurable granularity (e.g., one or two symbols). After the attacker performs RIM suppression, the victim sends RIM suppression state information (RIM-SI), such as ACK, NACK, etc., to the attacker.

[0246] Recommendation 6: In order to avoid the RIM-RS sent by the victim falling into the DL symbols of the aggressor gNB side in the next DL-UL switching period, RAN1 should further study the transmission position of RIM-RS.

[0247] 3.2 Frequency Domain Based Solution

[0248] 3.2.1 Solutions implemented through network implementation

[0249] Frequency domain based solutions can be divided into static / semi-static solutions and adaptive solutions.

[0250] If a static / semi-static FDM (frequency division multiplexing) scheme is applied, no coordination and adaptation between the attacker and the victim is required for bandwidth usage. Fig.11 As shown, the UL part of the interfered UL symbol at the victim side always uses a non-overlapping frequency band with the DL part of the interfering UL symbol from the aggressor side. Once the band combination including two non-overlapping frequency bands for (one or more) victims and (one or more) aggressors is determined in the early stage of network deployment, it will not be dynamically adjusted according to the actual interference. According to the analysis of the time domain method, in a typical TDD macro deployment scenario, most of the UL symbols of the victim may be interfered by long-range interference. If the victim UL and the aggressor DL ​​always use non-overlapping bandwidth (such as in a static manner), the spectrum efficiency and UL / DL capacity will be greatly reduced.

[0251] For adaptive schemes operating only on the victim side, the victim can avoid UL transmission on the interfered frequency resources by scheduling or activating different BWPs or sub-bands based on its IoT measurements and analysis. But if the uplink reception in the full bandwidth is interfered, the frequency domain-based solution applied only on the victim side cannot work.

[0252] Fig.11 is an example of a frequency domain method for RI suppression.

[0253] 3.2.2 Solutions with 5G Specification Impact

[0254] For the adaptive scheme, the victim and the aggressor may also work together to adaptively utilize different frequency bands between the aggressor DL ​​and the victim UL, for example, by scheduling or activating different BWPs or sub-bands without overlapping bandwidth between them.

[0255] The first method is that the victim can only transmit RIM-RS to the attacker in the interfered BWP / sub-band. The attacker determines the interfered UL BWP / sub-band based on RIM-RS detection, and then avoids scheduling DL transmission on the interfered BWP / sub-band or deactivates the interfered BWP / sub-band. This method has an impact on the RIM-RS design. Another method is that the victim notifies the attacker about the interfered BWP / sub-band through backhaul signaling after the connection is established between them.

[0256] 3.3 Solutions based on spatial domain

[0257] 3.3.1 Solutions implemented through network implementation

[0258] As agreed in RAN1#94bis, possible spatial domain RIM suppression solutions include:

[0259] -Receive beam nulling at the victim gNB to suppress long-range interference in the spatial domain.

[0260] -Schedule UE transmissions that will be received in the spatial direction that will experience less interference at the victim gNB.

[0261] - Control the transmit beam at the aggressor gNB (e.g., tilt downward)

[0262] - Using different beam directions at different DL locations (e.g., selecting the beam direction that experiences the least interference, and then using this beam to perform transmissions in DL resources adjacent to the GP based on reciprocity)

[0263] Mount the antenna at a lower height and electrically / mechanically tilt it downwards.

[0264] On the victim side, when it is subject to remote interference, it can adopt the solution of bullet 1 / 2 / 5. On the attacker side, it can adopt the solution of bullet 3 / 4 / 5. The above five methods can be implemented through implementation methods.

[0265] 3.3.2 Solutions with 5G Specification Impact

[0266] All of the above five methods can be implemented through implementation methods. However, in order to better implement these methods, there can be some standardized optimizations.

[0267] For example, if the attacker knows the ID of the victim gNB or gNB group, it can infer the direction of the victim gNBs and the distance between them regardless of the chosen framework. Therefore, it can perform some more relevant and accurate implementation-based solutions, such as increasing electrical / mechanical downtilt, reducing site height, or adjusting the coverage direction / beam of the attacker site. Moreover, the victim and attacker can coordinate the beam direction through the air interface or backhaul signaling.

[0268] 3.4 Power Domain-Based Solutions

[0269] 3.4.1 Solutions implemented through network implementation

[0270] The UE at the victim cell increases the UL transmission power in the UL interfered symbols (e.g. Fig.12 (a), but this will cause more interference to neighboring cells and increase UE power consumption. Alternatively, the attacker gNB reduces the DL transmission power, but this will affect the coverage of the cell, such as Fig.12 (b) as shown.

[0271] Both the victim gNB and the aggressor gNB can adjust the UL and DL transmission power by implementation. For example, the victim gNB can increase the UL transmission power in the interfered UL time slot by increasing PO or TPC (transmit power control) commands. The aggressor gNB can reduce its DL transmit power by a relatively large margin, such as 3dB, and it does not need to care whether the long-range interference is completely eliminated.

[0272] Fig.12 An example of a power domain approach for RI suppression on the victim side (left) and the aggressor side (right) is shown.

[0273] 3.4.2 Solutions with 5G Specification Impact

[0274] Although some implementation schemes without regulatory impact are given in Section 3.4.1, there are some problems with these implementation schemes. For example, the victim / aggressor gNB increases / decreases the transmission power with the granularity of one complete timeslot. However, there is actually no RI or generated RI in some specific symbols in the timeslot. For the victim cell, it may cause unnecessary power consumption and co-channel interference for the UE. For the aggressor cell, it will reduce the downlink throughput and coverage. Therefore, the interfered / interfering symbols and non-interfered / interfering symbols in the timeslot can be executed independently of the power control mechanism. In addition, the attacker can gradually reduce its DL transmission power, and the victim transmits RI suppression state information (RIM-SI) to help the attacker make the next power decision.

[0275] Specifically, for the victim scheme, if the UL power of the UE is increased at the edge of the cell, it will cause interference to the uplink of the adjacent cell. It makes no sense to introduce a new interference to solve the long-range interference. Moreover, the power margin that the UE at the cell edge can increase is limited, and it is doubtful whether increasing the power of the UE at the cell edge can resist RI. If the UL power of the UE is increased at the cell center, it means that the long-range interference problem is not completely solved, because the bottleneck of RI still lies mainly in the UE at the cell edge. In addition, whether it is for the UE at the cell edge or the UE at the cell center, increasing the UL power will lead to a sharp increase in UE power consumption. First, since the long-range interference originates from the DL transmission with larger power and has less attenuation after passing through the atmospheric waveguide, it still dominates compared with the energy received from the UL. Therefore, it is necessary to use RI to evaluate the relationship between the UL power increase and the system performance. Moreover, because the atmospheric waveguide usually lasts for several hours or even longer, the UE needs to increase its power for a long time continuously, which will pose a greater challenge to the power consumption of the UE.

[0276] In summary, we believe that RI suppression methods should be effective, efficient, and have as low complexity as possible. All the above time / frequency / space / power domain methods can be considered to improve network robustness.

[0277] Recommendation 7: In Rel-16, RI suppression schemes in the time domain, frequency domain, spatial domain, and power domain can be considered to improve network robustness.

[0278] 4. Conclusion of the previous description

[0279] In this contribution, we discuss some potential schemes for the NR-RIM framework and mechanisms for improving network robustness with the following observations and recommendations:

[0280] Observation 1: The following was observed for Scenario #1 and Scenario #2:

[0281] At least for scenario #1 with symmetric IoT addition, if the victim and attacker adopt the same triggering strategy (e.g., by IoT level and characteristics), the events triggered at the victim and attacker can be consistent.

[0282] In scenario #2, RS monitoring in step 1 cannot be triggered dynamically by IoT measurements but can be triggered by OAM configuration.

[0283] Observation 2: Considering forward compatibility and various possible RI suppression schemes, RS-1 in frame 1 carrying gNB ID or group ID information is necessary.

[0284] Observation 3: Compared with framework-2.1 ​​and framework-2.2, framework-0 and framework-1 have lower normalization complexity and are easier to implement.

[0285] Recommendation 1: RAN1 should evaluate the necessity of RS-2 transmission in Framework 1 from the perspective of the complexity of RS design and standardization:

[0286] If yes, RAN1 should strive for a common design for RS-1 and RS-2.

[0287] Recommendation 2: For gNB, a timer-based scheme should be considered to terminate RS transmission / monitoring and RI suppression scheme operation.

[0288] Recommendation 3: Regardless of the chosen framework, RIM-RS should transmit the victim gNB ID or group ID information for victim identification and inter-gNB communication.

[0289] Recommendation 4: Among the possible frameworks identified in RAN1#94, we have the following recommendations:

[0290] The design of RS and / or backhaul signaling should be designed to support one or more preferred frameworks (e.g., framework-0 / 1 / 2.1), and the framework applied in commercial networks can be left to the operator / vendor.

[0291] Recommendation 5: Several methods exist to determine the amount of DL resources on which an attacker needs to perform time-domain based solutions (such as DL symbol backoff or unscheduling):

[0292] Option 1: Based on a distance setting of 300km (1ms time delay), regardless of the actual distance between the victim and the attacker.

[0293] Option 2 The attacker infers how much of the victim's UL resources are affected by the attacker, but some of the victim's slot format configuration information needs to be notified to the attacker.

[0294] Option 3 reduces long-range interference in steps. Each step is performed only at a small fixed or configurable granularity (e.g., one or two symbols). After the attacker performs RIM suppression, the victim sends RIM suppression state information (RIM-SI), such as ACK, NACK, etc., to the attacker.

[0295] Recommendation 6: In order to avoid the RIM-RS sent by the victim falling into the DL symbols of the aggressor gNB side in the next DL-UL switching period, RAN1 should further study the transmission position of the RIM-RS.

[0296] Recommendation 7: In Rel-16, RI suppression schemes in the time, frequency, spatial and power domains can be considered to improve network robustness.

[0297] B1. Preface

[0298] The following sections describe examples of RIM-RS that can be used for interference management.

[0299] B2: Requirements and functions of RIM-RS

[0300] In all framework candidates, reference signals are a key and necessary part in remote interference management. In the case of considering the scenario of remote interference management, the reference signals in RIM should meet the following requirements:

[0301] Performance: In RIM, the reference signal should have sufficiently good autocorrelation and cross-correlation performance, low false alarm rate and missed detection probability, etc. Only in this way can correlation-based detection be used as a reliable method.

[0302] Overhead: According to TD-LTE network field tests, the atmospheric ducting phenomenon can last for several hours. The overhead of the reference signal should be considered to ensure that the network throughput is not severely degraded.

[0303] Compatibility: Considering backward compatibility, the reference signal should not cause confusion or detection problems at both the gNB and UE sides. At the same time, the impact of existing signals on RIM-RS should also be considered to ensure detection performance. In short, the impact between RIM's reference signal and existing reference signals should be minimized.

[0304] Detection without symbol alignment: Even in the RIM study it was assumed that the whole network is synchronized. The gNBs are interfered by attacker gNBs up to hundreds of kilometers away. The distance between the victim and the attacker is not clear. Therefore, RIM-RS should be detectable without symbol alignment.

[0305] Additionally, some functions of reference signals have been discussed as follows:

[0306] Function-1: The reference signals in all three frameworks should convey the gNB ID or gNB group ID information, which will enable some RI suppression mechanisms. For example, the adjustment of downtilt angle and other MIMO-related mechanisms requires the information of the location of the victim gNB ID or gNB group. In addition, the ID information is necessary for the attacker to identify the victim, and is also necessary and beneficial for the inter-gNB communication between the attacker and the victim through the backhaul in Framework-2.1 ​​and Framework-2.2. Therefore, in an effort to achieve a universal RIM-RS design and reduce the complexity of NR-RIM standardization, the reference signals should convey the ID information.

[0307] Function-2: The reference signal should be able to help the attacker gNB identify how far away the affected gNB is. Without knowing how far away the affected gNB is and how many uplink symbols are affected, the attacker may employ inappropriate time-domain long-range interference mitigation mechanisms.

[0308] Recommendation 1: The design of reference signals in RIM should consider the following factors: performance, overhead, compatibility, and detection without symbol alignment.

[0309] Recommendation 2: The reference signal in the RIM should have the following functions: convey the gNB ID or gNB group ID and help the attacker gNB to identify how many victims’ uplink symbols are affected.

[0310] B3. Candidates for RIM-RS

[0311] According to the discussion in RAN1-#94bis, there are three alternatives that can be used for further evaluation.

[0312] B3.1 Single Symbol RS

[0313] Alt-1 is a symbol reference signal with a comb structure in the frequency domain, and its comb factor is 2 or 4. Fig.15 As shown. The comb structure reference signal is repeated continuously within the symbol. With a detection window smaller than the OFDM symbol, the additional part can be used as a cyclic prefix. Therefore, the single-port CSI-RS is detectable even without OFDM symbol alignment. However, this requires a detector with an FFT size different from the FFT size used for uplink transmission. In our supporting contribution, an OFDM symbol long detector was used in the simulation. From the simulation results, it can be seen that the detection performance of the comb structure is inferior to the monitoring performance of other alternatives. Considering the field test results in LTE, the channel is very sensitive to weather conditions. The robustness of this comb structure with one symbol may not be enough to meet the requirements.

[0314] Fig.16 An alternative of a symbol reference signal with a comb structure is shown. Fig.16 (a) shows a comb factor = 4, while Fig.16 (b) shows an example of comb factor = 2.

[0315] Observation 1: The robustness of the comb structure with one-symbol RS may not be sufficient to meet the requirements.

[0316] B3.2 RS of two symbols

[0317] Alt-2 RIM-RS consists of two consecutive sequences. The CP of Alt-2 can be attached to the beginning of the concatenated sequence. Fig.17 In order to reuse FFT for PDSCH generation and maintain the time domain cyclic property, another OFDM baseband generation method for Alt-2 can be considered, which is Fig.17 At the same time, different OFDM symbols should be multiplied by different linear phase factors in the frequency domain, or should be cyclically shifted in the time domain.

[0318] Fig.17 An example of OFDM baseband signal generation for RS of two symbols is shown.

[0319] Observation 2: Alt-2 RIM-RS can reuse FFT for PDSCH signal generation.

[0320] Compared with a single symbol comb factor, the two-symbol RS shows better detection performance. Considering that the transmission period of RIM-RS in LTE is about 2.7307 minutes, the additional overhead of the two-symbol RS is small.

[0321] Observation 3: Considering the periodicity of RIM-RS transmission, the additional overhead of the two-symbol RS is small.

[0322] Proposal 3: Two-symbol RS (where two copies of an RS sequence are concatenated together and one CP is attached at the beginning), the concatenated sequence can be used as RIM-RS.

[0323] B4.ID information

[0324] To meet functionality-1, RIM-RS should transmit gNB or gNB group ID information to help the attacker identify the victim and / or employ appropriate mitigation mechanisms.

[0325] Code Field

[0326] When the number of sequences used to transmit ID increases, the detection performance may decrease. Considering that according to LTE field test results, RI will last for several hours, and if a large number of sequences are used, the detection complexity will not be negligible. Therefore, the number of sequences used to generate RIM-RS should be limited, for example, 8.

[0327] Recommendation 4: The number of sequences used to generate RIM-RS should be limited, for example, 8.

[0328] Time Domain

[0329] The UL-DL switching period corresponding to the RIM-RS transmission opportunity in NR is configurable. If the RIM-RS transmission period matches the UL-DL mode switch, there is only one opportunity for RIM-RS transmission, such as Fig.18(a) shown. Fig.18 RIM-RS transmission in the time domain is shown.

[0330] like Fig.18 (b) to Fig.18 As shown in (d), if multiple (e.g., M) UL-DL switching periods are configured in the RS transmission period, there are different methods for transmitting the ID information. Fig.18 In (b), the same generated sequence is used at different times, and the detection performance can be improved by repetition while transmitting less ID information. Fig.18 In (c), in order to convey more information, a different generation sequence is used for each opportunity. The disadvantage is that the detection is more than once. Fig.18 (c) different, Fig.18 The RS in (d) is repeated at each opportunity. Therefore, the method used to transmit the RIM-RS depends on the ID length, RS transmission period and UL-DL switching period.

[0331] Recommendation 5: To improve the detection performance and robustness of RIM-RS, there are two methods that can be used: a) repeat RIM-RS within the transmission period; b) repeat RIM-RS within the opportunity. Moreover, the repetition factor should be configurable.

[0332] Observation 4: The RIM-RS transmission pattern depends on the ID length, RS transmission periodicity, and UL-DL switching periodicity.

[0333] As for Fig.18 (c) and Fig.18 For the transmission mode in (d), the receiver should merge the ID information in different transmission opportunities to obtain a complete ID. It should be noted that if the receiver detects ID-1 and ID-2 at opportunity 1, and also detects ID-3 and ID-4 at opportunity 2. There will be four different interpretations, namely, (ID-1, ID-3), (ID-1, ID-4), (ID-2, ID-3), (ID-2, ID-4). In order to handle ambiguity, the merging used to transmit IDs should be limited.

[0334] Recommendation 6: If ID information is obtained by combining different transmission opportunities, the possible combinations used to transmit the ID should be limited to reduce ambiguity.

[0335] Frequency Domain

[0336] In LTE, the maximum frequency bandwidth is 20MHz, and the full bandwidth reference signal is used for RIM. For NR FR1 and FR2, the maximum frequency bandwidth may be up to 100MHz and 400MHz respectively. In order to reduce the blind detection complexity, the position of the start, end or center of the RIM-RS in the frequency domain may be fixed, for example at the synchronization grid.

[0337] Recommendation 7: To reduce the complexity of blind detection, the position of RIM-RS in the frequency domain should be fixed.

[0338] Some potential issues with using the FDM method to transmit ID information are discussed below:

[0339] If some FDM methods are used to transmit ID information, the ambiguity problem will arise again. For example, two sub-bands are used to represent the ID information of each gNB. If three reference signals are detected at different sub-bands at a certain time, there will be six different interpretations. It is difficult for the detector to identify the ID information from the six candidates.

[0340] If the frequency band used to transmit the ID partially overlaps with the frequency band where the RI occurs, the detection performance will be reduced because only part of the RS is detected.

[0341] According to the above analysis, if both RS-1 and RS-2 are necessary in Frame-1, TDM is a better method for distinguishing the two reference signals, such as the offset within the transmission cycle, the transmission timing, etc.

[0342] Recommendation 8: If both RS-1 and RS-2 are necessary in Frame-1, they should be distinguished by TDM.

[0343] B5: RIM-RS mode

[0344] In the RAN1#94 meeting, it was agreed that the entire network with synchronized macro cells has a common understanding of the DL and UL transmission boundaries within the DL-UL transmission period. In addition, in RAN1#94bis, it was agreed that RS-1 in frame-1 and RS in other frames are agreed to occupy the last X symbols before the DL transmission boundary.

[0345] As for RS-2 in Framework 1, which is used to notify whether the remote interference is still present, it should be detectable by the victim gNB. If RS-2 is placed on the last few symbols after the DL symbol backoff, there is a risk that RS-2 reaches the GP symbol which may not be detected by the victim gNB because the GP symbol will be subject to stronger interference from the neighboring cell. In this case, the victim gNB will stop sending RS-1 and a ping-pong effect may result. RS-2 is sent periodically per gNB and it is distributed from the perspective of the entire macro cell. Even if RS-2 is placed at the last symbol before the DL transmission boundary, the interference will not accumulate and cause a strong impact at the victim gNB.

[0346] Observation 5: If the position of RS-2 is backed off as a DL symbol, it may not be detected at the victim gNB side.

[0347] Observation 6: Even when RS-2 is placed as the last symbol before the DL transmission boundary, the interference does not accumulate and cause a strong impact at the victim gNB.

[0348] Recommendation 9: Same as RS-1, RS-2 in frame-1 should be placed at the last symbol before the DL transmission boundary.

[0349] According to LTE field test results, the distance between the victim and attacker gNBs can be up to 300km, which corresponds to a delay of 1ms. In LTE, if the transmission delay of the attacker gNB is 1ms, its DL signal will still reach the UL symbol and cause interference on the victim gNB side, such as Fig.19 (a) shown. Fig.19 An example of remote interference management is shown.

[0350] After the gNB recognizes itself as an aggressor and infers how many UL symbols it interfered, it can keep the last DL symbol causing interference as GP, and then RI will be suppressed or disappear, which is Fig.19 As shown in (b).

[0351] Fig. 20 An example of remote interference management with a small UL-DL switching period is shown.

[0352] However, different parameter sets and UL-DL transmission periods are supported in NR. The transmission delay may exceed Fig. 20 The sum of the GP and UL durations shown in (a). Since the gNB is not expected to detect RS during the DL duration, the attacker will not detect the RS sent at the DL boundary and will not recognize itself as an attacker, as shown in Fig. 20 (b) as shown.

[0353] Observation 7: In NR, if RSs are placed only at DL transmission boundaries, the attacker gNB may not recognize itself as an attacker and RI will not be suppressed.

[0354] Fig.21 When the transmission delay exceeds the sum of the GP and UL duration, the RIM-RS is repeated before the boundary.

[0355] To solve this problem, Fig.21 As shown, the RS can be repeated before the DL transmission boundary. Even if the RS before the boundary arrives at the DL duration and cannot be detected, the repeated RS is detectable. The attacker gNB can infer how many UL symbols it interfered with, e.g. Fig.21 (b) at n2. If the interval between the repeated RS and the boundary is known, for example Fig.21 At n1 in (b), the gNB will eventually infer that there are n1+n2 symbols interfered at the victim gNB, and it should reserve n1+n2 DL symbols as GP. As for the location of the repeated RS, 1) it can be properly configured based on previous experience, or 2) it can be encoded into the ID information, or 3) it can be indicated in the backhaul signaling.

[0356] Fig. 22 When the transmission delay is within the sum of the GP and UL duration, the RIM-RS is repeated before the boundary.

[0357] For the case where the transmission delay is within the sum of the GP and UL durations, this is Fig. 22 If the RIM-RS is repeatedly transmitted, the attacker will detect two identical RSs in the transition period. The attacker knows that only the UL symbol is interfered, and the range of interference can be reduced by detecting the position of the RS.

[0358] exist Fig. 22 In the present invention, repeated RS does not seem to be necessary. To reduce the detection complexity, the gNB may not need to send RS repeatedly. The scope of long-range interference and the necessity of RIM-RS can be inferred from previous experience. If the transmission delay exceeds the sum of GP and UL duration, repeated RS should be sent. Otherwise, repeated RS can be omitted. And the presence of repeated RS should be notified across macro cells within the network.

[0359] Observation 8: If the transmission delay exceeds the sum of the GP and UL duration, it is necessary to repeat the RS before the DL transmission boundary.

[0360] Recommendation 10: If the transmission delay exceeds the sum of the GP and UL duration, repeated RS should be sent. Otherwise, repeated RS can be omitted. And the presence of repeated RS should be notified across macro cells within the network.

[0361] Recommendation 11: The location of repeated RSs may be 1) appropriately configured based on previous experience, or 2) encoded into the ID information, or 3) indicated in the backhaul signaling.

[0362] B6. Conclusion of previous chapters

[0363] In this contribution, we discuss the reference signal design for long-range interference management with the following observations and recommendations:

[0364] Observation 1: The robustness of the comb structure with one-symbol RS may not be sufficient to meet the requirements.

[0365] Observation 2: Alt-2 RIM-RS can reuse FFT for PDSCH signal generation.

[0366] Observation 3: Considering the periodicity of RIM-RS transmission, the additional overhead of the two-symbol RS is small.

[0367] Observation 4: The RIM-RS transmission pattern depends on the ID length, RS transmission periodicity, and UL-DL switching periodicity.

[0368] Observation 5: If the position of RS-2 is backed off as a DL symbol, it may not be detected at the victim gNB side.

[0369] Observation 6: Even when RS-2 is placed as the last symbol before the DL transmission boundary, the interference does not accumulate and cause a strong impact at the victim gNB.

[0370] Observation 7: In NR, if RSs are placed only at DL transmission boundaries, the attacker gNB may not recognize itself as an attacker and RI will not be suppressed.

[0371] Observation 8: If the transmission delay exceeds the sum of the GP and UL duration, it is necessary to repeat the RS before the DL transmission boundary.

[0372] Recommendation 1: The design of reference signals in RIM should consider the following factors: performance, overhead, compatibility, and detection without symbol alignment.

[0373] Recommendation 2: The reference signal in the RIM should have the following functions: convey the gNB ID or gNB group ID and help the attacker gNB to identify how many victims’ uplink symbols are affected.

[0374] Suggestion 3: Two-symbol RS (where two copies of an RS sequence are concatenated together and one CP is attached at the beginning), the concatenated sequence can be used as RIM-RS.

[0375] Recommendation 4: The number of sequences used to generate RIM-RS should be limited, for example, 8.

[0376] Recommendation 5: To improve the detection performance and robustness of RIM-RS, there are two methods that can be used: a) repeat RIM-RS within the transmission period; b) repeat RIM-RS within the opportunity. Moreover, the repetition factor should be configurable.

[0377] Recommendation 6: If ID information is obtained by combining different transmission opportunities, the possible combinations used to transmit the ID should be restricted to reduce ambiguity.

[0378] Recommendation 7: To reduce the complexity of blind detection, the position of RIM-RS in the frequency domain should be fixed.

[0379] Recommendation 8: If both RS-1 and RS-2 are required in Frame-1, they should be distinguished by TDM.

[0380] Recommendation 9: Same as RS-1, RS-2 in frame-1 should be placed at the last symbol before the DL transmission boundary.

[0381] Recommendation 10: If the transmission delay exceeds the sum of the GP and UL duration, repeated RS should be sent. Otherwise, repeated RS can be omitted. And the presence of repeated RS should be notified across macro cells within the network.

[0382] Recommendation 11: The location of repeated RSs can be 1) appropriately configured based on previous experience, or 2) encoded into the ID information, or 3) indicated in the backhaul signaling.

[0383]

[0066] Various example implementations may be described using the following clause-based format.

[0384] 1. A wireless communication method, the method comprising: receiving, at a first communication node, interference state information indicating long-range interference between the first communication node and a second communication node; and performing, by the first communication node, subsequent communication to the second communication node by implementing a backoff based on granularity.

[0385] 2. The method of clause 1, comprising: receiving, at the first communication node, a first reference signal indicative of the remote interference from the second communication node.

[0386] 3. A method according to clause 2, wherein the reference signal carries a first identifier of the second communication node.

[0387] 4. A method according to any one of clauses 1 to 3, wherein the first communication node and the second communication node agree to operate using a maximum downlink transmission boundary and a maximum uplink transmission boundary during a downlink-uplink switching period. Figure 3 and the related descriptions provide time domain examples.

[0388] 5. A method according to clause 1, wherein the backoff includes backing off the transmission power based on power granularity, or avoiding transmission on multiple symbols based on the symbol granularity between the last downlink symbol configured by the second communication node and the maximum downlink transmission boundary, or the second time domain distance between the first uplink symbol configured by the second communication node and the maximum uplink transmission boundary.

[0389] 6. A method according to any of clauses 1 to 5, wherein the interference cancellation state information comprises one or more of an ACK, a NACK, a dB value, a symbol count, a back-off time and an indication of long-range interference received at the second communication node.

[0390] 7. A method according to any of clauses 1 to 6, wherein the first communication node adjusts the granularity based on a message from the second communication node.

[0391] 8. A method according to any of clauses 1 to 7, wherein the information is received via an air interface or a backhaul signalling message.

[0392] 9. A method according to any of clauses 1 to 8, wherein performing subsequent communications comprises: performing, by the first communication node, an interference mitigation scheme based on the information.

[0393] 10. The method of clause 9, comprising terminating, by the first communication node, the suppression scheme.

[0394] 11. A method according to clause 9 or 10, wherein performing a mitigation scheme comprises: sending, by the first communication node, a second reference signal based on a parameter, wherein the parameter indicates that the second reference signal is sent to indicate whether the atmospheric ducting phenomenon persists.

[0395] 12. A method for wireless communication, the method comprising: sending, by a first communication node, a first reference signal indicating the presence of remote interference between the first communication node and a second communication node, wherein a time domain position of the first reference signal comprises one of: the last symbol before a maximum downlink transmission boundary for transmission between the first communication node and the second communication node or the Nth symbol before a transmission boundary, wherein N is an integer greater than 1.

[0396] 13. A method according to clause 12, wherein N is a function of at least one of the following parameters: subcarrier spacing, a transmission distance between the first communication node and the second communication node, a transmission delay between the first communication node and the second communication node, or the number of flexible symbols after a maximum downlink transmission boundary.

[0397] 14. A method according to any of clauses 12 to 13, wherein for the first communication node, N is semi-persistently scheduled.

[0398] 15. A method for wireless communication, the method comprising: sending, by a first communication node, a first reference signal indicating the presence of remote interference between the first communication node and a second communication node, wherein the first reference signal is sent in a preconfigured time period, and wherein the first reference signal is sent at multiple times in each time period; and using the first reference signal to transmit ID information associated with the first communication node.

[0399] 16. The method of clause 15, wherein the ID information associated with the first communication node is an identifier of the first communication node or an identifier of a group to which the first communication node belongs.

[0400] 17. A method according to clause 15 or 16, wherein at occasions within a given time period, transmissions of the first reference signal all carry the same subset of bits of the ID information.

[0401] 18. A method according to clause 15 or 16, wherein the transmission of the first reference signal comprises N consecutive bits of ID information, where N is an integer.

[0402] 19. A method according to clause 15 or 16, wherein the ID information is transmitted in bit portions, wherein each bit portion of size M is sent in M ​​consecutive transmissions of the first reference signal, wherein M is an integer.

[0403] 20. A method according to clause 15 or 16, wherein the preconfigured time periods comprise at least a first time period P1 and a second time period P2, and wherein different parts of the identifier are sent in transmissions during P1 and P2.

[0404] 21. Another wireless communication method, the method comprising: sending a first reference signal related to a first interference on an inbound channel to the first communication node and a second reference signal related to a second interference on an outbound channel from the first communication node from a first communication node, wherein the first reference signal and the second reference signal are sent in a non-overlapping manner.

[0405] 22. The method of clause 21, wherein the non-overlapping pattern comprises a dual-cycle pattern comprising a first cycle in which the first reference signal is transmitted and a second cycle in which the second reference signal is transmitted and which does not overlap with the first cycle.

[0406] 23. A method according to clauses 21 to 22, wherein the first period of the first cycle and the second period of the second cycle are configured by a higher layer message.

[0407] 24. A method according to any of clauses 21 to 23, wherein the first cycle and the second cycle have different durations.

[0408] 25. The method of clause 24, wherein one of the first cycle and the second cycle repeats more frequently than the other of the first cycle and the second cycle.

[0409] 26. The method of clause 21, wherein the non-overlapping manner comprises periodically transmitting the first reference signal and the second reference signal starting with different offsets in each time period.

[0410] 27. The method of clause 21, wherein the first reference signal and the second reference signal have different transmission densities in the first period and the second period, respectively.

[0411] 28. A wireless communication device comprising a processor configured to implement the method set forth in any one or more of clauses 1 to 27.

[0412] 29. A computer program product having stored thereon code which, when executed by a processor, causes the processor to carry out the method set out in any one or more of clauses 1 to 27.

[0413] It should be appreciated that this document discloses techniques that may be embodied in a wireless communication system to allow wireless communication nodes to effectively suppress long-range interference without noticeable impact on system performance.

[0414] The disclosed and other embodiments, modules and functional operations described in this document may be implemented in a digital electronic circuit system, or in computer software, firmware or hardware including the structures disclosed in this document and their structural equivalents, or a combination of one or more of them. The disclosed and other embodiments may be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by a data processing device or for controlling the operation of a data processing device. The computer-readable medium may be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter that implements a machine-readable propagation signal, or a combination of one or more of them. The term "data processing device" includes all devices, equipment and machines for processing data, including, as examples, a programmable processor, a computer or multiple processors or computers. In addition to hardware, the device may include code that creates an execution environment for the computer program in question, for example, code that constitutes a processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. The propagated signal is an artificially generated signal, such as a machine-generated electrical signal, an optical signal or an electromagnetic signal generated to encode information for transmission to a suitable receiver device.

[0415] A computer program (also referred to as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, and it may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple collaborative files (e.g., files storing portions of one or more modules, subroutines, or code). A computer program may be deployed to execute on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communications network.

[0416] The processes and logic flows described herein may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and the apparatus may be implemented as, a special purpose logic circuit system, such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0417] For example, processors suitable for executing computer programs include both general-purpose microprocessors and special-purpose microprocessors, as well as any one or more processors of any type of digital computer. In general, the processor will receive instructions and data from a read-only memory or a random access memory or both. The basic elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. In general, a computer will also include a large-capacity storage device (such as a magnetic disk, a magneto-optical disk, or an optical disk) that is operably coupled to one or more for storing data, to receive data from it or to transmit data to it, or both. However, a computer does not require such a device. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, by way of example, semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks (e.g., internal hard disks or removable disks); magneto-optical disks; and CD ROM and DVD-ROM disks. The processor and memory may be supplemented by a dedicated logic circuit system or incorporated into a dedicated logic circuit.

[0418] Although this patent document contains many details, these details should not be interpreted as limitations on the scope of any invention or what may be claimed, but rather as descriptions of features specific to particular embodiments of particular inventions. Certain features described in this patent document in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination. Moreover, although features may be described above as working in certain combinations, or even initially claimed as such, in some cases one or more features from the claimed combination may be excluded from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination.

[0419] Similarly, although operations are depicted in a particular order in the drawings, this should not be understood as requiring that the operations be performed in the particular order shown or in sequential order, or that all of the operations shown be performed, in order to achieve the desired results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0420] Only a few implementations and examples are described, and other implementations, enhancements, and variations can be made based on what is described and illustrated in this patent document.

Claims

1. A wireless communication method, the method comprising: transmitting, from a first communication node, a first reference signal and a second reference signal, the first reference signal being associated with first interference on an inbound channel to the first communication node and the second reference signal being associated with second interference on an outbound channel from the first communication node, wherein the first reference signal and the second reference signal are sent in a non-overlapping manner, The first communication node sends interference status information to the second communication node, wherein the interference status information is sent after the interfered base station receives a remote interference management reference signal RIM-RS2 sent by the interfering base station, or after the interfered base station receives information detected by the RIM-RS through a backhaul, The interference status information includes one of interference presence and interference absence, or the interference status information includes one of negative acknowledgement (NACK) and confirmation (ACK).

2. The method according to claim 1, wherein: The non-overlapping mode includes a dual-cycle mode, and the dual-cycle mode includes a first cycle and a second cycle, the first reference signal is sent in the first cycle, and the second reference signal is sent in the second cycle, wherein the second cycle does not overlap with the first cycle.

3. The method according to claim 1, wherein: The non-overlapping manner includes transmitting the first reference signal and the second reference signal starting at different offsets in one cycle.

4. A wireless communication method, the method comprising: a second communication node receiving a first reference signal and a second reference signal, the first reference signal being associated with first interference on an inbound channel to the first communication node and the second reference signal being associated with second interference on an outbound channel from the first communication node, wherein the first reference signal and the second reference signal are received in a non-overlapping manner, The second communication node receives interference status information from the first communication node, and the interference status information is received after the interfered base station receives a remote interference management reference signal RIM-RS2 sent by the interfering base station, or after the interfered base station receives information detected by RIM-RS through a backhaul, The interference status information includes one of interference presence and interference absence, or the interference status information includes one of negative acknowledgement (NACK) and confirmation (ACK).

5. The method according to claim 4, wherein: The non-overlapping mode includes a dual-cycle mode, and the dual-cycle mode includes a first cycle and a second cycle, the first reference signal is received in the first cycle, and the second reference signal is received in the second cycle, wherein the second cycle does not overlap with the first cycle.

6. The method according to claim 4, wherein: The non-overlapping approach includes receiving a first reference signal and a second reference signal starting at different offsets in a cycle.

7. The method according to claim 4, wherein: The method further comprises: performing, by the second communication node, a first interference cancellation mechanism; and After receiving the interference status information, the second communication node maintains the first interference cancellation mechanism unchanged or further performs a second interference cancellation mechanism.

8. A wireless communication device, the device comprising a processor and a memory, the processor being configured to implement the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having computer program code stored thereon, wherein the computer program code, when executed by a processor, implements the method according to any one of claims 1 to 7.

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