Multiple Radio Access Technology Interference Reduction

Abstract

A method is provided for operating a station to communicate simultaneously on a first frequency division duplex (FDD) radio access network (RAN) using a first carrier signal; and a second time division duplex (TDD) RAN using a second carrier signal, the second carrier signal being at a higher frequency than the frequency of the first carrier signal, wherein transmission from the station using the first carrier signal causes interference to reception at the station on the second TDD RAN. The method includes aligning the timing of transmission from the station on the first FDD RAN with the timing for transmission from the station on the second TDD RAN.

Description

Technical Field

[0001] The present disclosure relates to the operation of stations, in particular mobile stations (user equipment), in a network, such as a cellular network. Background Art

[0002] It is well known to use two radio access networks (RANs) to increase the data rate over the air interface. For example, carrier aggregation (CA) or dual connectivity (DC) configurations are known, especially for the Long Term Evolution (LTE) cellular network architecture. Such configurations require simultaneous transmission and / or reception of multiple carriers. At least one carrier may be associated with a frequency division duplex (FDD) RAN, and at least one carrier may be associated with a time division duplex (TDD) RAN.

[0003] Such multi-carrier configurations may be implemented, including implementations using multiple radio access technologies (RATs). Some examples of multi-carrier configurations are LTE / NR CA, LTE-DC, and multi-RAT DC mode (MR-DC), such as specified in the Third Generation Partnership Project (3GPP) TS 37.340. In MR-DC, one or more carriers may use LTE RAN (where most of the frequency bands allocated for this RAT are designated for FDD operation) and one or more carriers may use NR RAN (typically TDD). In such an implementation, a transceiver (which may include a separate transmitter and receiver for these purposes) sends and receives signals in different frequency bands. For example, at least one carrier may be sent at a frequency in a first frequency band, and at least one carrier may be sent at a frequency in a different second frequency band. The second frequency band may be much higher than the first frequency band. For example, LTE RAN may operate in the 1.8 GHz frequency band, while NR RAN may operate in the 3.5 GHz frequency band.

[0004] Such scenarios may result in interference, particularly harmonic interference at the receiver (or the receive chain of a transceiver and any reference to a receiver below may include this). Harmonic interference occurs when the receive frequency is an integer multiple of the transmit frequency and may be a particular concern in the example above where the NR RAN may operate at a harmonic frequency (or close to a harmonic frequency) of the LTE RAN carrier. Such harmonic interference may severely impact receiver performance as LTE FDD transmissions (especially on the uplink) may cause interference to the NR TDD air interface, especially on the downlink. Successful operation of such CA or DC mode desirably mitigates and / or minimizes this interference. Summary of the invention

[0005] In this context, the present disclosure provides a method for operating a station according to claim 1 and according to claim 12, a method for configuring a station according to claim 9, and a station (e.g. UE, mobile station, relay station or base station) for a cellular network according to claim 15. Further preferred features are disclosed with reference to the claims and the following description.

[0006] The method of the present disclosure uses two radio access networks (RANs): a first frequency division duplex (FDD) RAN using a first carrier signal; and a second time division duplex (TDD) RAN. The FDD RAN carrier signal and the TDD RAN carrier signal are at different frequencies, wherein the TDD RAN carrier signal is a higher frequency and typically much higher, such as on a different frequency band and / or is at least twice the FDD RAN carrier signal. Specifically, the frequency (or frequency band) of the TDD RAN carrier signal may be (approximately) a harmonic (integer multiple) of the frequency (or frequency band) of the FDD RAN carrier signal.

[0007] In any case, the transmission of a slave station (e.g., in the uplink, a mobile station) using an FDD RAN carrier signal causes interference, such as harmonic interference, to the reception at the station via the TDD RAN. However, the station will operate for simultaneous communication on both the FDD RAN and the TDD RAN, such as in a multi-carrier configuration, such as using carrier aggregation (CA) or dual connectivity (DC) functionality (dual uplink or dual downlink operation). The term "station" as used herein may be a mobile station (or user equipment, UE or the like) or a base station (eNB, gNB or the like), a relay station and / or a remote radio head (RRH) remote radio unit (RRU) or the like, and may include a transceiver, higher protocol layer components and other parts that allow operation in a network, in particular a cellular network, such as based on 3GPP standards. It is noteworthy that at least some stations providing relay functionality may also be considered as base stations, for example, if they are considered as base stations by mobile devices and / or network nodes.

[0008] In the method of the present disclosure, the timing of (all) reception of confirmation messages (e.g., automatic repeat request (ARQ)), transmissions, or indeed all transmissions from a station via the FDD RAN is aligned (e.g., by setting, adjusting, coordinating or synchronizing) with the timing for transmissions (e.g., ARQ transmissions from the station via the TDD RAN). In contrast, transmissions (at least ARQ transmissions, but preferably all transmissions of any type) may not be performed by the station via the FDD RAN during the time slots when the station is receiving via the TDD RAN. Advantageously, this means that each ARQ transmission may not always be performed for a fixed (predetermined) number of time slots after the transmission and / or reception of the corresponding message associated therewith. In the case where the station is a user equipment (UE) (e.g., a mobile station), the uplink ARQ transmissions (or all uplink transmissions) are thereby aligned with the uplink time slots for the TDD RAN. In this way, interference from ARQ transmissions (or any uplink transmissions) on the FDD RAN to reception at the station on the TDD RAN is at least reduced or mitigated and preferably avoided. Dual uplink (where both FDD RAN uplink and TDD RAN uplink are utilized simultaneously) is maintained, with subsequent capacity benefits. These advantages will also apply to dual downlink at the base station (where both FDDRAN downlink and TDD RAN downlink are utilized simultaneously), mutatis mutandis.

[0009] On the other hand, a receiving station (and / or a method of operating such a receiving station) may be considered that is configured to receive such aligned transmissions through two RANs. In this case, the receiving station may align (alternatively, coordinate or synchronize) the timing for receiving transmissions on the first FDD RAN with the timing for receiving transmissions at the station on the second TDD RAN. In the uplink case, the receiving station will be a base station. Any features described herein with respect to transmissions may be considered in contrast with respect to reception. In addition, a combination of this aspect with any other aspect described herein may also be considered. In a preferred method, the FDDRAN ARQ transmission is delayed or advanced, and the delayed or advanced FDD RAN ARQ transmission is transmitted in the same time slot as the (ARQ) transmission with respect to the second TDD RAN. For example, this can be achieved using transmit time interval (TTI) bundling.

[0010] Control signaling (e.g., RRC signaling) may be provided by the FDD RAN or the TDD RAN. This aspect of the disclosure may be considered independently of or in combination with other aspects described herein. Such control signaling advantageously instructs a station (particularly a UE) to align the timing of transmission of a slave station on the first FDD RAN with the timing of transmission of a slave station on the second TDD RAN. Therefore, a method of transmitting the instruction may be considered. The control signaling may optionally indicate the possibility of interference, in particular an indication that the frequency (band) of the TDD carrier signal is approximately a harmonic of the frequency of the FDD RAN carrier signal. In any case, the alignment of the timing of at least ARQ transmission (and in some cases, all uplink transmissions) may be performed in response to receiving the control signaling. The control signaling may also indicate the timing to be used.

[0011] In a preferred embodiment, the FDD RAN and the TDD RAN use different radio access technologies (RATs), for example, the FDD RAN may be a Long Term Evolution (LTE) RAN and the TDD RAN may be a New Radio (NR) RAN. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The method of the present disclosure may be implemented in various ways, one of which will now be described by way of example only and with reference to the accompanying drawings, in which:

[0013] Figure 1 A schematic diagram showing example transmission timing for a first FDD RAN and a second TDD RAN;

[0014] Figure 2 A schematic diagram depicting transmission timing for a first FDD RAN and a second TDD RAN according to an embodiment of the present disclosure is depicted;

[0015] Figure 3 A flowchart consistent with an embodiment of the present disclosure is shown; and

[0016] Figure 4 An example of a station for use with embodiments of the present disclosure is schematically depicted. DETAILED DESCRIPTION

[0017] The example discussed above will be used to illustrate the following disclosure, where one or more carriers may use FDD LTE RAN in the 1.8 GHz band and one or more carriers may use TDD NR RAN in the 3.5 GHz band. In this example, there may be a fixed configuration of time instances where TDD channels are used for transmission with other fixed time instances where channels are used for reception. This means that when the transceiver transmits on the 3.5 GHz band, it cannot simultaneously receive on the same 3.5 GHz band. For simplicity, the configuration at the user equipment (UE) or mobile station will be considered, but it should be recognized that the corresponding situation at the RAN can be considered inversely. In the case of MR-DC, the RAN may include two base stations (one for LTE FDD RAN and one for NR TDD RAN) connected via an X2 or Xn interface.

[0018] When the transceiver operates in the 1800 MHz band using FDD LTE RAN, a fixed timing is provided between receiving data in one direction and sending control information in the other direction using Automatic Repeat Request (ARQ) to confirm correct delivery of the data. For the following examples, a timing of three subframes will be used.

[0019] This reference Figure 1 1, there is shown a schematic diagram of example transmission timing (e.g., spanning a frame of 5 ms duration) for a first FDD RAN and a second TDD RAN. The subframes are numbered from 0 across the top (i.e., 0, 1, 2, 3, 4, ...). In the FDD RAN downlink 101, a first transmission A is made in subframe 0, a second transmission B is made in subframe 1, and a third transmission C is made in subframe 2. In the FDD RAN uplink 102, a first acknowledgement A* (which may be an ACK or NACK message) regarding the first transmission A is made in subframe 3, a second acknowledgement B* regarding the second transmission B is made in subframe 4, and a third acknowledgement C* regarding the third transmission C is made in subframe 5. It can be seen that with respect to the NR TDD system 111, every fourth subframe provides an uplink U and every other subframe is used for a downlink D. Therefore, the sending of the first confirmation A* does not affect the uplink subframe 3 of the NR TDD system 111, as shown by arrow 120, but the sending of the second confirmation B* does affect the uplink subframe 4 of the NR TDD system 111, as shown by arrow 121, and the sending of the third confirmation C* does affect the uplink subframe 5 of the NR TDD system 111, as shown by arrow 122.

[0020] The approach taken by the present disclosure is to avoid that FDD RAN transmissions do impact TDD RAN reception. This is achieved by the transceiver transmitting over the FDDRAN uplink (in the example shown) only during time instances when the TDD RAN band is also being used for transmission (and therefore not receiving signals). The fixed time limits used for LTE FDD ARQ would mean that this approach would limit the time instances when a device could receive downlink data on FDD. This could result in a loss of LTE RAN downlink throughput. To mitigate this problem, the ARQ on the FDD RAN is configured to use the transmit timing of the TDD RAN. In particular, the FDD RAN may use the hybrid ARQ (HARQ) transmit timing of the TDD RAN such that (at Figure 1 In the example of ) the UL transmission on the FDD RAN is synchronized with the uplink transmission on the TDD band. This can be achieved using Transmission Time Interval (TTI) bundling.

[0021] refer to Figure 2 , depicts a schematic diagram of transmission timing for a first FDD RAN and a second TDD RAN according to an embodiment of the present disclosure. Figure 1 Similarly, in the FDD RAN downlink 201, the first transmission A is performed in subframe 0 and the second transmission B is performed in subframe 1. However, the fixed timing for ARQ is relaxed. In the FDD RAN uplink 202, both the first acknowledgement A* regarding the first transmission A and the second acknowledgement B* regarding the second transmission B are performed in subframe 3. Therefore, the transmission of the first acknowledgement A* and the second acknowledgement B* does not affect the NR TDD system 111 uplink subframe 3, as shown by arrow 220.

[0022] The method allows flexible timing (e.g. bundling) of HARQ ACK or NACK messages for multiple subframes, and these are sent on limited uplink subframes in time instances when the TDD downlink is not received by the UE or mobile station. The TDD configuration to be operated will be signaled to the mobile station through RRC control signaling, as described below. Although the above discussion has been made with reference to a mobile station or UE, where the timing of FDD uplink ARQ transmissions is aligned with the TDD RAN uplink, it will be understood that in a network node (e.g., a base station), the timing of FDD downlink ARQ transmissions can be aligned with the TDD RAN downlink. It should be noted that in a system based on the 3GPP standard, the base station (eNB or gNB) determines the scheduling of uplink transmissions, or the scheduling of uplink transmissions is predetermined in the standard. Therefore, the UE does not have a specific uplink scheduler. The UE operates or performs transmissions according to instructions or standards from the network.

[0023] The result of the method provides a second TDD RAN uplink configuration for a semi-static configuration of a device for a first FDD RAN (e.g. LTE) carrier such that the FDD RAN uplink transmissions are (only) consistent with uplink transmissions by the same device on the TDD RAN. The FDD RAN uplink transmissions are not consistent with the TDD RAN downlink transmissions.

[0024] In general, a method for operating a station (e.g., in a cellular network) to simultaneously communicate via: a first frequency division duplex (FDD) radio access network (RAN) using a first carrier signal; and a second time division duplex (TDD) RAN using a second carrier signal, the second carrier signal being at a higher frequency than the frequency of the first carrier signal (e.g., in a different frequency band). A station (e.g., a mobile station, a UE, a relay station, a remote radio head / unit (RRH / RRU), a relay station, and / or a base station (e.g., an eNB or gNB)) configured to operate according to the method may also be considered. In the context of the present disclosure, a station may include one or more of a transceiver, an antenna system, a scheduler (in particular, in a base station), a transmission configuration (in particular, implementing a scheduling command or instruction at a UE from a network), other physical layer components, higher protocol layer components, and other parts that allow operation in a network, in particular a cellular network, such as based on a 3GPP standard. In addition, a computer program (e.g., stored on a computer-readable medium), logic (which may be programmable), or other system configuration configured to operate according to the method may be provided.

[0025] The transmission of the slave station using the first carrier signal causes interference to the reception at the station on the second TDD RAN. The method comprises aligning the timing of (all) transmissions of the slave station on the first FDD RAN with the timing of transmissions (e.g. ARQ transmissions) of the slave station on the second TDD RAN. This may be performed to avoid interference from transmissions on the first FDD RAN to reception at the station on the second TDD RAN. Alignment is advantageously an active step, which may include one or more of: setting; adjusting; coordinating; synchronizing; and other similar concepts.

[0026] The timing may be particularly applicable to reception confirmation message transmission, such as ACK / NACK messages. For example, this may include aligning the timing of at least reception confirmation message transmission by the slave station on the first FDD RAN with the timing of transmission (including reception confirmation message transmission) by the slave station on the second TDD RAN, in particular such that the timing of reception confirmation message transmission is not (always) performed at a fixed (predetermined) time (e.g., a reference time slot, such as a number of subframes) after the transmission and / or reception of the message associated therewith. The reception confirmation message transmission may be part of an automatic repeat request (ARQ) scheme, which may include a hybrid ARQ (HARQ) protocol.

[0027] In another sense, a method may be considered in which a station operates in one of two modes (and may select between the modes). In a first mode for when no TDD / FDD interference is expected, a predetermined (or fixed) timing is used for the transmission of a reception confirmation message by a slave station on the first FDD RAN relative to the transmission by the slave station on the first FDD RAN (e.g., the reception confirmation message is sent a predetermined or fixed number of time slots after the message of the confirmation or retransmission request is sent). Fixed timing for ARQ is generally preferred because it is less complex to implement, requires less signaling, and therefore has less overhead. Delays may also be reduced if a separate reception confirmation message transmission (ACK / NACK) is performed for each subframe. In a second mode where interference is possible, the timing of the reception confirmation message transmission on the first FDD RAN is based on the timing of the transmission by the slave station on the second TDD RAN.

[0028] Aligning the timing of the ARQ transmissions optionally comprises delaying or advancing the ARQ transmissions with respect to the first FDD RAN. In particular, this may be a comparison with a fixed, predetermined timing for reception confirmation message transmissions, as described above. This advantageously enables the delayed or advanced ARQ transmissions with respect to the first FDD RAN to be transmitted in the same time slot as the transmissions with respect to the second TDD RAN. The step of aligning the timing of the ARQ transmissions may comprise transmit time interval (TTI) bundling of the ARQ transmissions with respect to the first FDD RAN.

[0029] Preferably, the frequency of the second carrier signal and the frequency of the first carrier signal are in different frequency bands. For example, the frequency of the second carrier signal may be at least twice the frequency of the first carrier signal. Therefore, the transmission of the slave station using the first carrier signal may cause harmonic interference to the reception at the station on the second TDD RAN. In this case, the frequency of the second carrier signal may be approximately a harmonic (i.e., an integer multiple) of the frequency of the first carrier signal.

[0030] The first FDD RAN and the second TDD RAN may use different radio access technologies (RATs). For example, the first FDD RAN may be a long term evolution (LTE) RAN, and the second TDD RAN may be a new radio (NR) RAN. Advantageously, the station operates using the first carrier and the second carrier to provide multi-carrier functionality, such as carrier aggregation (CA) or dual connectivity (DC).

[0031] It will also be understood that for each transmitting station on a particular side of a link (e.g., uplink or downlink), a corresponding configuration may be implemented at a receiving station on the other side of the link. For example, the receiver should know the mode in which the transmitting station is operating so that it can look for a transmission (e.g., an ACK / NACK message or the like) at the correct time slot.

[0032] In general, in another aspect, this may be considered to be a method for operating a station to communicate simultaneously via: a first frequency division duplex (FDD) radio access network (RAN) using a first carrier signal; and a second time division duplex (TDD) RAN using a second carrier signal, the second carrier signal being at a higher frequency than the frequency of the first carrier signal. The frequency of the second carrier signal is approximately a harmonic of the frequency of the first carrier signal. The method includes aligning the timing for receiving a transmission at the station on the first FDD RAN with the timing for receiving a transmission at the station on the second TDD RAN. It will be appreciated that with respect to the uplink, the station in this aspect may be a base station.

[0033] In this regard, receiver features corresponding to any optional, preferred or otherwise advantageous transmitter features described herein may be provided.For example, the method may be applied in relation to reception of one or more reception confirmation (eg ARQ) messages and / or different types of RATs.

[0034] The method adopted in the present disclosure is similar to the method described in International Patent Publication No. WO-2018 / 174766, the details of which are incorporated by reference. The method adopted in this document is intended to solve problems different from those considered in the present disclosure, in particular intermodulation distortion (IMD). IMD is a specific form of interference and is completely different from other types of interference such as harmonic interference considered in the present disclosure. This is because IMD is caused by the simultaneous transmission of two or more carriers, which produces additional components at the sum and difference frequencies of the carrier frequencies and at the sum and difference of multiples of these carrier frequencies. IMD can be generated by simultaneous operation on FDD RAN and TDD RAN operating in the same frequency band, so that the station can communicate with both RANs using a single carrier signal. In order to solve the IMD problem, simultaneous uplink transmission on FDD RAN and TDD RAN is avoided. This can be achieved by TTI bundling of ARQ messages in FDD RAN. In this method, a single uplink is effectively implemented, and simultaneous dual uplink is lost. Although this method has similarities with the method of the present disclosure, it should be understood that there are also significant differences, as described above.

[0035] An alternative approach adopted in the present disclosure may be to limit transmission on the FDD RAN to ensure that there is no corresponding feedback sent when the TDD RAN channel is being received. However, this will cause difficulties. In particular, there may be a significant reduction in throughput on the FDD RAN. In addition, it may require synchronization of transmissions at multiple stations. For example, when the NR TDD RAN operates on the 3.5 GHz band, the base stations of the LTE FDD RAN and the NR TDD RAN may not be able to dynamically communicate with each other. This approach will also limit the throughput to the station (for example, on the downlink, where the station is a UE or a mobile station). Therefore, static configuration will be required for the LTE carrier.

[0036] Next, refer to Figure 3 , shows a flow chart consistent with an embodiment of the present disclosure. In a first step 301, a station receives an indication of using a multi-carrier (eg, CA or DC) configuration.

[0037] In a second step 302, the station receives an indication that there may be interference (e.g., harmonic interference) between the FDD RAN and the TDD RAN and / or an indication of the TDD RAN transmission timing. Such an indication may be provided by signaling in the medium access control (MAC) layer and / or radio resource control (RRC) connection setup or reconfiguration. For example, a configuration similar to that shown below may be employed, which is used when a single uplink transmission is required for power control or IMD issues, as specified in 3GPP TS 38.101-3 and 3GPP TS 38.213. For example, a new information element similar to "tdm-PatternConfig" may be implemented.

[0038]

[0039] Therefore, this may incorporate new signaling from the network to the UE mobile device, such as providing an uplink / downlink reference configuration indicating when the UE (e.g. configured with EN-DC) may transmit. For example, updates to RAN1 and RAN2 (e.g. 3GPP TS 36.331 and / or 3GPP TS 38.331) may be employed.

[0040] The timing of the ARQ transmission of the secondary station on the FDD RAN is aligned with the timing for the transmission of the secondary station on the TDD RAN in step 303. This is to avoid interference from the ARQ transmission on the FDD RAN to the reception at the station on the TDD RAN.

[0041] Returning to the general terms described above, where the station is a UE, a mobile station, or another type of station as described above, the method may also include receiving a control signal at the station and / or sending a control signal to the station (e.g., on a first FDD RAN or a second TDD RAN) to instruct the station to align the timing of transmissions from the station on the first FDD RAN with the timing for transmissions from the station on the second TDD RAN. The control signal may additionally or alternatively indicate that the frequency of the second carrier signal is (approximately or approximately) a harmonic of the frequency of the first carrier signal. In any case, the step of aligning the timing of ARQ transmissions may be performed in response to receiving the control signal. The control signal may include an RRC and / or MAC signal. The control signal may optionally further indicate the timing for transmissions on the second TDD RAN.

[0042] In another aspect, a method of signaling and / or configuring a station (e.g., a user equipment (UE), a mobile station, or other type of station in a cellular network) may be considered. The station may be configured or configurable for multi-carrier operation on a first FDD RAN, for example, using a first carrier signal, and a second TDD RAN, for example, using a second carrier signal, which operates in different frequency bands and / or the TDD RAN is at a higher frequency (e.g., a harmonic) of the operating frequency of the FDD RAN. The method includes transmitting a downlink control signal to the station (preferably on the first FDD RAN) to instruct the station to align the timing of transmissions from the station on the first FDD RAN with the timing for transmissions from the station on the second TDD RAN. Additionally or alternatively, the control signal may indicate that the frequency of the second TDD RAN is (approximately) a harmonic of the frequency of the first carrier signal, and / or indicate that the timing for transmissions on the second TDD RAN is for the station to adopt with respect to the first FDD RAN. Then, aligning the timing of ARQ transmissions at the station with respect to the first FDD RAN with the timing of transmissions by the station on the second TDD RAN may be performed in response to receiving the control signal. The control signals may include RRC and / or MAC signals. The method may be performed by a network node such as a base station, a remote radio head or unit, or a relay station (in which case the step of transmitting may include sending or transmitting) or at a UE, a mobile station, or other type of station (in which case the step of transmitting may include receiving).

[0043] refer to Figure 4 , schematically shows an example of a station for use with an embodiment of the present disclosure. Station 400 includes: a processor 410; a transceiver 420; and an antenna device 430. In the transmit path, a signal from the processor 410 may be passed to the transceiver 420 for modulation, and the transmission is then provided to the antenna device 430 for transmission. Conversely, in the receive path, the transmission is received using the antenna device 430, and the received signal is passed to the transceiver 420 for detection and / or demodulation. The detected and / or demodulated signal is then provided to the processor 410. It should be understood that although a single transmit and receive path using the transceiver 420 is shown, this can be replaced with separate transmit paths and receive paths, such as using separate transmitters and receivers. For example, the components may be collocated, but this need not be the case (e.g., in the case of using RRH / RRU). Such a station may be used for a UE, a network node (base station), or a relay station. The skilled person will further understand that this is merely an example of a station for use with the present disclosure, and other examples may be considered, such as discussed herein.

[0044] Although specific embodiments have now been described, the skilled person will appreciate that various modifications and variations are possible. Furthermore, any combination of specific features shown with reference to one embodiment or with reference to multiple embodiments is also provided, even if the combination is not explicitly detailed herein.

[0045] Specific variations may include different RANs and / or RATs used, specific configurations of frames and / or subframes, and ways to align the timing of transmissions. In addition, while the present disclosure describes methods for mitigating harmonic interference, it may also be applicable to other types of interference caused by FDD RAN transmissions causing interference to TDD RAN receivers at or near the same location or in adjacent locations (e.g., in the same station or tower or in stations or towers near each other) and / or within the same station (e.g., for a UE). The base stations may optionally communicate with each other using S1, N2, or another interface over the core network within a transparent container.

Claims

1. A method for operating a station to communicate simultaneously on a first frequency division duplex (FDD) radio access network (RAN) using a first carrier signal; and a second time division duplex (TDD) RAN using a second carrier signal, the second carrier signal being at a higher frequency than the frequency of the first carrier signal, wherein, Transmission from the station using the first carrier signal causes interference to reception at the station on a second TDD RAN, the method comprising: aligning timing of transmission of a reception confirmation message from the station on the first FDD RAN with timing for transmission from the station on the second TDD RAN; wherein the step of aligning comprises delaying or advancing the transmission of the reception confirmation message with respect to the first FDDR RAN by bundling the transmission time intervals (TTIs) of the reception confirmation message transmission with respect to the first FDD RAN compared to a fixed, predetermined timing for the transmission of the reception confirmation message, such that the delayed or advanced transmission of the reception confirmation message with respect to the first FDD RAN is transmitted in the same time slot as the transmission with respect to the second TDD RAN; and Among them, FDD RAN is Long Term Evolution (LTE) RAN, and TDD RAN is New Radio (NR) RAN.

2. The method according to claim 1, wherein: The frequency of the second carrier signal is at least twice the frequency of the first carrier signal.

3. The method according to claim 1 or 2, wherein: Transmission from the station using the first carrier signal causes harmonic interference to reception at the station on a second TDD RAN, and a frequency of the second carrier signal is approximately a harmonic of a frequency of the first carrier signal.

4. The method according to claim 1 or 2, wherein: The station operates using a first carrier and a second carrier to provide carrier aggregation (CA) or dual connectivity (DC) functionality.

5. The method according to claim 4, further comprising: receiving a control signal at the UE or mobile station instructing the UE or mobile station to align timing of transmissions from the UE or mobile station on the first FDD RAN with timing for transmissions from the UE or mobile station on the second TDD RAN; and Therein, the step of aligning the timing of transmission is performed in response to receiving the control signal.

6. A method for configuring a station to communicate simultaneously on a first frequency division duplex (FDD) radio access network (RAN) using a first carrier signal; and a second time division duplex (TDD) RAN using a second carrier signal, the second carrier signal being at a higher frequency than the frequency of the first carrier signal, wherein, Transmission from the station using the first carrier signal causes interference to reception at the station on a second TDD RAN, the method comprising: transmitting a downlink control signal to the station, the control signal instructing the station to align timing of reception confirmation message transmission from the station on a first FDD RAN with timing for transmission from the station on a second TDD RAN by: delaying or advancing reception confirmation message transmission with respect to the first FDD RAN by transmission time interval (TTI) bundling of reception confirmation message transmission with respect to the first FDD RAN compared to a fixed, predetermined timing for reception confirmation message transmission, such that the delayed or advanced reception confirmation message transmission with respect to the first FDD RAN is transmitted in the same time slot as the transmission with respect to the second TDD RAN; and Among them, FDD RAN is Long Term Evolution (LTE) RAN, and TDD RAN is New Radio (NR) RAN.

7. The method according to claim 5 or claim 6, wherein: The control signal also indicates the timing for sending a reception confirmation message on the second TDDRAN.

8. The method according to claim 1, 2, 5 or 6, wherein: The station is a user equipment (UE), a mobile station or a relay station.

9. A station for a cellular network arranged to operate according to the method of any preceding claim.

Images