Patent Description:
Radio repeaters provide a way of extending range for radio signals, for example in radio access networks (RAN). The term "relay" may be used in the same context. In its simplest form, a radio repeater is an apparatus that comprises a radio receiver, an amplifier and a radio transmitter. The radio receiver may receive a signal from, for example, a first node of a radio network and may retransmit the signal to another node. Radio repeaters may become important in radio networks where coverage and range is an issue, for example where the underlying radio access technology has a limited range. The Fifth Generation (<NUM>) New Radio (NR) technology is one such example.

<CIT> describes a communication device providing: a communication unit which is capable of simultaneously performing data transmission and data reception using the same band; an acquisition unit which acquires information pertaining to self-interference that occurs when the data transmission and the data reception are performed simultaneously using the same band; and a communication control unit which performs control with regard to data transmission on the basis of the information pertaining to self-interference or on the basis of information that is from another device and that has been generated on the basis of the information pertaining to self-interference.

According to a first aspect, there is described an apparatus according to claim <NUM>.

The predetermined threshold may be based on the transmit power level minus a predetermined design value. The predetermined design value may be user-defined.

The modifying means may be configured to reduce or increase the gain based on the difference between the self-interference power value and the predetermined threshold.

The modifying means may be configured to reduce the gain by an amount substantially equal to the difference between the self-interference power value and the predetermined threshold.

The modifying means may be configured to determine that the amount of gain reduction is greater than a further predetermined threshold and, responsive thereto, to disable at least the amplifying means.

The modifying means may be configured to increase the gain by an amount substantially equal to the minimum of (i) the difference between the self-interference power value and the predetermined threshold and (ii) a maximum gain value associated with the amplifying means minus the current gain.

The one or more sets of reference data may comprise a look-up-table pre-populated during characterization testing and prior to deployment of the apparatus.

The reference data may be stored remotely from the apparatus, the apparatus being configured to access the reference data over a data network.

The one or more reference signals may be transmitted based on one or more control signals received from a remote node.

The one or more reference signals may be transmitted at one or more times when data-carrying radio signals received by the apparatus are not being retransmitted.

The one or more reference signals may comprise pilot or synchronisation signals (e.g. primary and/or secondary synchronisation signals) associated with the data-carrying radio signals. The timings of these types of reference signals may be provided to the apparatus by a base station or may be pre-provided at the apparatus, e.g. stored on one or more memories.

The apparatus may be configured to retransmit data-carrying radio signals associated with an uplink during a first repeating period and data-carrying radio signals associated with a downlink during a second repeating period, the first and second repeating periods being separated by a guard period, wherein the one or more reference signals are transmitted in the guard period.

The one or more reference signals may be transmitted according to a schedule which determines to transmit the one or more control signals at a time when one or more repeater nodes within a predetermined range of the apparatus do not transmit signals.

The one or more reference signals may be transmitted using a frequency band that is different from frequency band(s) used by one or more repeater nodes within a predetermined range of the apparatus.

The one or more repeater nodes within a predetermined range of the apparatus may comprise one or more repeater nodes associated with a radio access network cell with which the apparatus is associated.

The one or more reference signals may comprise an analogue tone. The analogue tone may be transmitted using a different frequency from frequencies used by one or more repeater nodes within a predetermined range of the apparatus.

The one or more reference signals may comprise a digitally-encoded signal. The digitally-encoded signal may be different from those used by one or more repeater nodes within a predetermined range of the apparatus.

The apparatus may comprise a radio access network (RAN) repeater. The RAN repeater may be configured for full-duplex operation. The RAN repeater may be configured for in-band operation.

According to a second aspect, there is described a method according to claim <NUM>.

The modifying may reduce or increase the gain based on the difference between the self-interference power value and the predetermined threshold.

The modifying may reduce the gain by an amount substantially equal to the difference between the self-interference power value and the predetermined threshold.

The modifying may determine that the amount of gain reduction is greater than a further predetermined threshold and, responsive thereto, to disable at least the amplifying means.

The modifying may increase the gain by an amount substantially equal to the minimum of (i) the difference between the self-interference power value and the predetermined threshold and (ii) a maximum gain value associated with the amplifying means minus the current gain.

The one or more sets of reference data may comprise a look-up-table pre-populated during characterization testing and prior to deployment of the repeater.

The reference data may be stored remotely from the repeater, the apparatus being configured to access the reference data over a data network.

The one or more reference signals may be transmitted at one or more times when data-carrying radio signals received by the repeater are not being retransmitted.

The one or more reference signals may comprise pilot or synchronisation signals (e.g. primary and/or secondary synchronisation signals) associated with the data-carrying radio signals. The timings of these types of reference signals may be provided to the repeater by a base station or may be pre-provided at the repeater e.g. stored on one or more memories.

The method may further comprise retransmitting data-carrying radio signals associated with an uplink during a first repeating period and data-carrying radio signals associated with a downlink during a second repeating period, the first and second repeating periods being separated by a guard period, wherein the one or more reference signals are transmitted in the guard period.

The one or more reference signals may be transmitted according to a schedule which determines to transmit the one or more control signals at a time when one or more repeater nodes within a predetermined range of the repeater do not transmit signals.

The one or more reference signals may be transmitted using a frequency band that is different from frequency band(s) used by one or more repeater nodes within a predetermined range of the repeater.

The one or more repeater nodes within a predetermined range of the repeater may comprise one or more repeater nodes associated with a radio access network cell with which the repeater is associated.

The one or more reference signals may comprise an analogue tone. The analogue tone may be transmitted using a different frequency from frequencies used by one or more repeater nodes within a predetermined range of the repeater.

The one or more reference signals may comprise a digitally-encoded signal. The digitally-encoded signal may be different from those used by one or more repeater nodes within a predetermined range of the repeater.

The repeater may comprise a radio access network (RAN) repeater. The RAN repeater may be configured for full-duplex operation. The RAN repeater may be configured for in-band operation.

Example embodiments will now be described by way of non-limiting example, with reference to the accompanying drawings, in which:.

Example embodiments relate to control of radio repeaters. Radio repeaters may provide a way of extending coverage and range for radio technologies, for example in radio access networks (RANs) such as mobile networks. For the purposes of this disclosure, the term "relay" may be used in the same context.

In its simplest form, a radio repeater is an apparatus that comprises a radio receiver with an associated receive antenna and a radio transmitter with an associated transmit antenna, and an amplifier provided in the signal path between the radio receiver and radio transmitter.

Modern and future radio standards, such as the Fifth Generation (<NUM>) New Radio (NR) standard for mobile networks, may involve the use of radio repeaters given that the range of associated base stations (i.e. gNodeBs or gNBs) for millimetre-wave transmission and reception is relatively low. This may necessitate network densification with a shorter distance between base stations. Integrated Access and Backhaul (IAB) is a feature associated with <NUM> NR whereby, rather than relying on fibre connections to provide the backhaul connection, part of the wireless spectrum is used for backhaul links as well for radio access links.

Radio repeaters may be more efficient when operating in an "in-band" mode, which is when fronthaul and access links use the same frequency band. Radio repeaters may also be more efficient when operating in a "full-duplex" mode, which is when fronthaul and access transmissions are active at the same time, as opposed to half-duplex repeaters.

In the context of <NUM> NR, and future standards, the use of antenna arrays for beamforming is proposed. Accordingly, radio repeaters may need to be configured for repeating beamformed signals and for operation in, for example, in-band and/or full-duplex modes for achieving above-mentioned efficiencies. Such solutions may have low cost and low latency attributes while providing higher throughput.

A consideration with radio repeaters is self-interference, which depends on the isolation between the transmit and receive antennas. If isolation is low, this can cause near-field coupling between the transmit and receive antennas. Also, reflections from the surrounding environment may lead to interference from so-called far-field coupling.

Example embodiments relate to control of radio repeaters for mitigating self-interference.

<FIG> is a schematic view of a radio repeater <NUM> as part of a radio access network (RAN) such as a mobile communications network.

<FIG> shows a first base station <NUM>, such as a gNb, which may be connected to another part of a RAN, e.g. a core node or distribute unit (DU) via an optical channel <NUM> or other form of channel. The first base station <NUM> may have limited transceiving range and hence the radio repeater <NUM> may be placed within said transceiving range for receiving and re-transmitting radio signals, for example to a user equipment (UE) <NUM> or other receiving node in range of the radio repeater <NUM>. Similarly, radio signals transmitted by the UE <NUM> destined for the first base station <NUM> may be received and re-transmitted by the radio repeater <NUM> in the other direction.

<FIG> is a schematic view of at least some functional components of the radio repeater <NUM> which may be useful for understanding example embodiments.

The radio repeater <NUM> may comprise circuitry <NUM>, a first antenna <NUM> and a second antenna <NUM>. At least one of the first and second antennas <NUM>, <NUM> may comprise an antenna array comprised of multiple antenna elements (e.g. in a grid pattern) from which receive and transmit beams, indicated generally by reference numerals <NUM>, <NUM>, may be formed. It will be appreciated that <NUM> NR and some future telecommunications standards may employ beamforming in which one or more of such antenna elements may be energised or enabled for receiving and/or transmitting signals by means of directive beams.

<FIG> indicates, as part of the circuitry <NUM>, distinct chains of components respectively associated with downlink (DL) and uplink (UL) data-carrying signals. First and second switches <NUM>, <NUM> may switch between the downlink and uplink chains according to time division duplex (TDD) signalling. The connection of the first and second switches <NUM>, <NUM> shows a downlink setup and, for or ease of explanation, only the downlink chain of components will be mentioned. According to the downlink setup, the first antenna <NUM> will act as a receive antenna and the second antenna <NUM> will acts as a transmit antenna. The reverse will be true for the uplink setup with the lower chain of components considered.

The downlink chain of components may comprise a low noise amplifier (LNA) <NUM>, a variable gain amplifier (VGA) <NUM> and a power amplifier (PA) <NUM>. A data-carrying signal received by the first antenna <NUM> will be routed via the first switch <NUM> to the LNA <NUM> which may be configured to amplify the data-carrying signal above the noise floor. The data-carrying signal may then be routed to the VGA <NUM> which amplifies the signal further according to a determined gain setting and may ultimately determine the transmitting range of the radio repeater <NUM>. The PA <NUM> provides a further, set level of amplification before the amplified data-carrying signal is retransmitted by the second antenna <NUM>.

As mentioned above, the received and retransmitted data-carrying signal may be received in a first beam <NUM> having a particular receive beam index, and re-transmitted in a second beam <NUM> having a particular transmit beam index.

Self-interference is indicated schematically in terms of near-field coupling (which may pass through both the downlink and uplink component chains) and also far-field coupling between, in the shown case, the second antenna <NUM> acting as a transmit antenna and the first antenna <NUM> acting as a receive antenna.

Example embodiments may involve controlling the gain, for example associated with the VGA <NUM>, in order to mitigate self-interference, as will be explained below.

<FIG> is a flow diagram indicating operations that may be performed at a radio repeater according to an example embodiment. The operations may be processing operations performed by hardware, software, firmware or a combination thereof.

Returning to <FIG>, a first operation <NUM> comprises transmitting (or causing to transmit) one or more reference signals at a transmit power level using a transmit antenna of a repeater.

A second operation <NUM> comprises measuring a receive power level of the corresponding one or more reference signals received using a receive antenna of the repeater.

A third operation <NUM> comprises determining a self-interference power value based on the difference between the transmit power level of the one or more reference signals and the receive power level of the one or more corresponding reference signals.

A fourth operation <NUM> comprises modifying a gain associated with an amplifying means of the repeater based on the determined self-interference power value.

Further details of the function and form of the one or more reference signals be explained below.

The one or more reference signals may be referred to hereafter as Self Interference Reference Signals, or SIRS.

The self-interference power value may be the SIRS transmit power level minus the SIRS receive power level for the corresponding SIRS.

Example embodiments involve reducing the gain associated with the amplifying means of the repeater, e.g. the VGA, if the self-interference power value is above a certain threshold value and/or increasing the gain if the self-interference power value is below a certain threshold value.

For example, <FIG> is a more detailed flow diagram indicating operations that may be performed at a radio repeater according to one or more example embodiments. As above, the operations may be processing operations performed by hardware, software, firmware or a combination thereof.

The operations will be explained later on with reference to <FIG> which is a schematic diagram of a modified radio repeater <NUM>.

A first operation <NUM> comprises transmitting (or causing to transmit) one or more reference signals at a transmit power level using a transmit antenna of a repeater.

A fourth operation <NUM> comprises determining if the self-interference power level is above a predetermined threshold.

If yes, in a fifth operation <NUM>, the gain of the amplifying means is reduced, e.g. by an amount substantially equal to the difference between the self-interference power value and the predetermined threshold.

If no, in a sixth operation <NUM>, the gain of the amplifying means is increased. The predetermined threshold may be referred to as Δ'.

Modifying comprises reducing the gain if the self-interference power value is above the predetermined threshold Δ' and increasing the gain if the self-interference power value is below the predetermined threshold. If the self-interference power value is equal or substantially equal to the predetermined threshold, the gain may be maintained at its current level.

The predetermined threshold Δ' may, for example, be based on the SIRS transmit power level of the one or more SIRSs minus a predetermined design value Δ.

The predetermined design value Δ may be user-defined and/or modifiable.

For example, with reference to <FIG>, it may be assumed that isolation between the transmit antenna <NUM> and the receive antenna <NUM> (the effective path loss for self-interference) in the shown downlink case should be larger than the overall gain of the downlink components of the radio repeater <NUM>. For example: <MAT>.

The value of Δ may be set and, if needed, adjusted to reflect a desirable gap between the isolation and the total repeater gain. For example, the value of Δ for traffic types that are data rate heavy, but are more tolerant to interference, might be in the order of a <NUM> - <NUM> dBs, whereas for reliable data transmissions with very low tolerance to interference, a larger value of Δ may be used e.g. a <NUM> dB gap.

The above formula (<NUM>) can be written as: <MAT>.

If (<NUM>) does not hold, the radio repeater <NUM> may create a strong loop interference, causing a severe degradation to the received Signal to Interference Noise Ratio (SINR) which may defeat the purpose of a radio repeater <NUM>. Indeed, it may be preferable to turn the radio repeater <NUM> off, or fall back to an out-of-band repeating option to avoid self-interference.

In some embodiments, the right-hand-side of the above inequality in (<NUM>) may be modified by, for example, adjusting the gain of the VGA <NUM>, to ensure a consistent Δ gap for the above reasons.

Therefore, the formula (<NUM>) may be modified to perform the following comparison. <MAT> which can be simplified to: <MAT>.

The self-interference power value (or level) may be the SIRS transmit power level minus the SIRS receive power level for the corresponding SIRS.

In practical applications, the value of the SIRS transmit power level may be fixed which leaves the comparison as: <MAT> where Δ' is the predetermined threshold mentioned above, and may indicate the SIRS transmit power level minus the predetermined design value Δ.

Other methods of setting and adjusting the value of the predetermined threshold Δ' may be used, and the above is one example.

One or both of the first and second antennas <NUM>, <NUM> comprise an antenna array from which receive and transmit beams may be formed, the self-interference power level depends on the given receive and transmit beam combination. The value of Δ or Δ' can be fixed or can be made beam-specific, although the former option is used in this case.

In such cases, the formula (<NUM>) may be re-written as: <MAT>.

In view of the above, modifying the gain of the amplifier, e.g. the VGA <NUM> may comprise reducing or increasing the gain based on the difference between the self-interference power value and the predetermined threshold Δ' and/or based on one or more rules or constraints. For example, the gain may be reduced by an amount substantially equal to the difference between the self-interference power value and the predetermined threshold Δ'. In some cases, if the amount of gain reduction is greater than a further predetermined threshold, at least the amplifying means may be disabled so that the radio repeater <NUM> will not be used.

In some example embodiments, modifying the gain may comprise increasing the gain by an amount based on one or more rules or constraints. For example, the gain may be increased by an amount substantially equal to, for example, the minimum of (i) the difference between the self-interference power value and the predetermined threshold and (ii) a maximum gain value associated with the amplifying means minus the current gain.

<FIG> is a schematic view of at least some functional components of a radio repeater <NUM> according to one or more example embodiments.

The radio repeater <NUM> may be configured to operate according to the above operations indicated in <FIG> and <FIG> and according to any related operations discussed herein.

The radio repeater <NUM> may comprise circuitry <NUM>, a first antenna <NUM> and a second antenna <NUM>. At least one of the first and second antennas <NUM>, <NUM> may comprise an antenna array comprised of multiple antenna elements (e.g. in a grid pattern) from which receive and transmit beams, indicated generally by reference numerals <NUM>, <NUM>, may be formed. It will be appreciated that <NUM> NR and some future telecommunications standards may employ beamforming in which one or more of such antenna elements may be energised or enabled for receiving and transmitting signals by means of directive beams.

<FIG> indicates, as part of the circuitry <NUM>, distinct chains of components respectively associated with repeating downlink (DL) and uplink (UL) data carrying signals. First and second switches <NUM>, <NUM> switch between the downlink and uplink chains according to time division duplex (TDD) signalling. The connection of the first and second switches <NUM>, <NUM> shows a downlink setup and, for ease of explanation, only the downlink chain of components will be mentioned. According to the downlink setup, the first antenna <NUM> will act as a receive antenna and the second antenna <NUM> will acts as a transmit antenna. The reverse will be true for the uplink setup.

The upper, downlink chain of components may comprise a low noise amplifier (LNA) <NUM>, a first SIRS switch <NUM>, a variable gain amplifier (VGA) <NUM>, a second SIRS switch <NUM> and a power amplifier (PA) <NUM>.

The circuitry <NUM> may further comprise a power sensor <NUM>, a gain controller <NUM>, a reference signal generator <NUM> and a controller <NUM>. The controller <NUM> may be connected to each of the power sensor <NUM>, gain controller <NUM> and reference signal generator <NUM> and may be configured to control operation thereof. The controller <NUM> may also issue an SIRS enable signal to the first and second SIRS switches <NUM>, <NUM> for setting said switches in the manners indicated below. The controller <NUM> may form part of the circuitry <NUM> or may be remote from the radio repeater <NUM>, e.g. operated at some other part of a RAN.

A data-carrying signal received by the first antenna <NUM> (i.e. for being retransmitted) will be routed via the first switch <NUM> to the LNA <NUM> which may be configured to amplify the data-carrying signal above the noise floor. The data-carrying signal may then be routed either to the VGA <NUM>, if the first SIRS switch <NUM> is disabled, or to the power sensor <NUM>, if the first SIRS switch is enabled in accordance with an SIRS enable signal from the controller <NUM>.

The output from the VGA <NUM> is routed to the second SIRS switch <NUM>. If the second SIRS switch <NUM> is disabled by the controller <NUM>, the output from the VGA <NUM> is therefore routed to the PA <NUM>. If the second SIRS enable switch <NUM> is enabled by the controller <NUM>, as in the shown case, the output of the reference signal generator <NUM> is routed to the PA <NUM> instead.

The gain of the VGA <NUM> may be set by the gain controller <NUM> and determines the gain applied to the data-carrying signal when re-transmitted by the transmit antenna <NUM> if the first and second SIRS switches <NUM>, <NUM> are disabled.

Regarding the uplink (lower) chain of components, another VGA <NUM> may also be controlled by the gain controller <NUM> in the same manner described herein, in the situation where the first antenna <NUM> is the transmit antenna and the second antenna <NUM> is the receive antenna. The controller <NUM> may be configured to cause the reference signal generator <NUM> to generate one or more reference signals, or SIRSs at one or more times.

In other embodiments, the reference signal generator <NUM> may generate the one or more SIRSs responsive to one or more control signals from a remote node, e.g. a node in a core part of the RAN.

The SIRSs are transmitted at a known power level, which may be fixed or which may vary. This is referred to above as the SIRS transmit power level.

The times at which the SIRSs are generated is synchronised with the first and second SIRS switches <NUM>, <NUM> being enabled to the shown state. The SIRSs are therefore transmitted from the radio repeater <NUM> via the transmit antenna <NUM>. The power sensor <NUM> then may sense, or measure, SIRS receive power levels received via the receive antenna <NUM> corresponding to the SIRS transmit power levels for determining a self-interference power level.

The power sensor <NUM> may then provide the determined self-interference power level to the controller <NUM> or the gain controller <NUM> which may determine whether to modify the gain of the VGA <NUM> in accordance with operations described herein.

If the gain of the VGA <NUM> (or the VGA <NUM> in uplink operation) requires modification, the gain is adjusted accordingly. The controller <NUM> may then issue an SIRS disable signal (or simply cease the SIRS enable signal) to the first and second SIRS switches <NUM>, <NUM> so that the data carrying signal can be retransmitted as before using the updated gain value of the VGA <NUM> (or the VGA <NUM> in uplink operation).

It will be appreciated therefore that the one or more SIRSs may be transmitted at one or more times when data-carrying radio signals received by the radio repeater <NUM> are not being retransmitted.

In some example embodiments, the radio repeater <NUM> may retransmit data-carrying radio signals associated with a downlink during a first repeating period and data-carrying radio signals associated with an uplink during a second repeating period, the first and second repeating periods being separated by a guard period, wherein the controller <NUM> or a remote node controller may cause the one or more SIRSs to be transmitted in the guard period. The SIRSs need to be shorter than the guard period.

In some example embodiments, the one or more SIRSs may be transmitted according to a schedule which determines to transmit the one or more SIRSs at a time when one or more other repeater apparatus, e.g. within a predetermined range of the apparatus do not transmit signals.

For example, SIRSs may be transmitted or around <NUM>.

In some example embodiments, the one or more SIRSs may be transmitted using a frequency band that is different from frequency band(s) used by one or more other repeater apparatuses within a predetermined range of the apparatus.

In this respect, the one or more other repeater apparatuses within a predetermined range of the apparatus comprise one or more repeater nodes associated with a RAN cell with which the apparatus is associated, e.g. the same RAN cell.

It follows that, to avoid the power sensor <NUM> sensing, or measuring, SIRS receive power levels from other nearby repeaters, the SIRSs may need to be "orthogonalized" in terms of timing and/or frequency. Thus, a network of radio repeaters <NUM> may be scheduled accordingly so that SIRSs and other radio activity from one radio repeater does not interference with that of others in the network.

In some example embodiments, the one or more SIRSs may comprise an analogue tone, e.g. at a particular frequency. For example, the analogue tone SIRS may be transmitted using a different frequency from frequencies used by one or more repeater nodes within a predetermined range of the apparatus.

In some example embodiments, the one or more SIRSs may comprise a digitally-encoded data signal. The digitally-encoded data signal SIRSs may different from those used by one or more repeater nodes within a predetermined range of the apparatus.

The one or more SIRSs may comprise pilot or synchronisation signals (e.g. primary and/or secondary synchronisation signals) associated with the data-carrying radio signals. The timings of these types of reference signals may be provided to the apparatus by a base station or may be pre-provided at the apparatus, e.g. stored on one or more memories.

In some example embodiments, the controller <NUM> may store, or have access to, one or more sets of reference data which may indicate how to perform the fifth and sixth operations <NUM>, <NUM> indicated in <FIG>. In other words, the one or more sets of reference data may comprise values or rules for determining how to decrease and/or increase the gain of the VGA <NUM> for a determined self-interference power level. For example, the one or more sets of reference data may indicate the amount of gain reduction or increase to apply to the VGA <NUM>.

The one or more sets of reference data may comprise one or more look-up-tables (LUTs). The one or more sets of reference data may be pre-populated, for example during a characterization testing stage prior to deployment, and may be based on a predetermined SIRS transmit power level.

The LUT may be updated periodically or on demand as new values are obtained and measured and may act as a reference point for subsequent operations.

Referring to <FIG>, an example set of reference data is shown in the form of a LUT <NUM>.

The LUT <NUM> comprises reference data for a repeater apparatus configured the same or similar to the radio repeater of <FIG>. It is assumed that the receive antenna <NUM> and the transmit antenna <NUM> comprise antenna arrays configured for beamforming using a 2x2 beam configuration. In practice, a larger number of beams may be provided for. The antenna arrays may therefore transmit and receive respective SIRSs using a plurality of beams at respective times, and hence the reference data in the LUT <NUM> may indicate values for the four different beam combinations. The transmit beams and the receive beams are referenced by respective index numbers as shown in first and second columns <NUM>, <NUM> of the LUT <NUM>.

The third column <NUM> may indicate the above mentioned predetermined threshold Δ' which is set, in this example, to <NUM> dB.

The fourth column <NUM> may indicate reference values corresponding to measured self-interference power values (or levels) at a predetermined gain G of the VGA <NUM> in dBm.

The fifth column <NUM> may indicate a set of dynamic gain constraints applied to the current gain G when decreasing or increasing the gain of the VGA <NUM> according to one or more predetermined rules.

The rows <NUM> represent the various beam index combinations.

For example, for the case where the transmit beam index was "<NUM>" and the receive beam index was "<NUM>" the measured self-interference power value was <NUM> dB and so below the <NUM> dB threshold. In accordance with the fourth operation <NUM> in <FIG>, the process moved to the sixth operation <NUM> and the gain G of the VGA <NUM> could be increased. According to the LUT <NUM>, the gain G could be increased by a value equal to: <MAT>.

For the case where the transmit beam index was "<NUM>" and the receive beam index was "<NUM>" the measured self-interference power value was <NUM> dB and so above the <NUM> dB threshold. In accordance with the fourth operation <NUM> in <FIG>, the process moved to the fifth operation <NUM> and the gain G of the VGA <NUM> could be decreased. According to the LUT <NUM>, the gain G could be decreased by a value equal to: <MAT>.

For the case where the transmit beam index was "<NUM>" and the receive beam index was "<NUM>" the measured self-interference power value was <NUM> dB and so below the <NUM> dB threshold. In accordance with the fourth operation <NUM> in <FIG>, the process moved to the sixth operation <NUM> and the gain G of the VGA <NUM> could be increased. According to the LUT <NUM>, the gain G could be increased by a value equal to: <MAT>.

In subsequent operations of the radio repeater <NUM>, based on the transmit beam index and receive beam index at a particular time, and the determined self-interference power value, the controller may access the LUT <NUM> and determine how to increase or decrease the value of G.

As an alternative to using a LUT <NUM> or other reference data, the radio repeater <NUM> may transmit an SIRS for all the possible beams (i.e. sweeps all beam index combinations) and adjusts the gain according to the strongest self-interference power level observed. For example, the gain may be adjusted to be the minimum of all gain values given in the fifth column <NUM>, which should correspond to the maximum self-interference power level indicated in the fourth column <NUM>.

In some embodiments, there may be provided a method of signalling between a network node, e.g. network hub access point (AP), whereby the AP schedules radio resources based on how particular radio repeaters are reporting self-interference. For example, if a particular radio repeater, through operation according to examples mentioned above, update the LUT <NUM> to indicate a high-level of self-interference whereby the radio repeater needs to be turned off, at least for a particular beam index combination, the AP may avoid scheduling a particular UE through said radio repeater or for that beam index combination.

In example embodiments, the radio repeater <NUM> may be a radio access network (RAN) repeater. For example, the RAN repeater may be configured for full-duplex operation. For example, the RAN repeater may be configured for in-band operation.

Example embodiments provide an apparatus, method and computer program product that may offer advantages in terms of control of radio relays, for example those which are operating in the full-duplex and/or in-band modes where self-interference might otherwise be a technical issue causing performance degradation. Example embodiments, through use of SIRSs, enable dynamic operation on the basis of possibly changing self-interference effects over time which can be unpredictable. Example embodiments may achieve such advantages without the need for, for example, physical shielding.

Example embodiments may allow the isolation between antennas to be proportional to the amplifier gain of the radio repeater <NUM> in order to keep the interference power level low enough. The interfering signal may be the same as the useful signal with a short delay, the signal linearity degradation may be acceptably low if the interference power level is low, e.g. provided the amplifier gain is less than the transmit power level. However, with increased delay, as may be the case in IAB setups which use more complex processing, the required isolation may need to be higher to keep the signal degradation low. Hence, example embodiments employ the predetermined threshold and also may act in a dynamic manner through the use of SIRSs.

<FIG> shows an example apparatus that may comprise, for example, the controller <NUM> or one or more of the power sensor <NUM>, gain controller <NUM> and the reference signal generator <NUM>.

The apparatus may comprise at least one processor <NUM> and at least one memory <NUM> directly or closely connected or coupled to the processor. The memory <NUM> may comprise at least one random access memory (RAM) 710a and at least one read-only memory (ROM) 710b. Computer program code (software) <NUM> may be stored in the ROM 710b. The apparatus may be connected to a transmitter path and a receiver path in order to obtain respective signals or data. The apparatus may be connected with a user interface (UI) for instructing the apparatus and/or for outputting data. The at least one processor <NUM> with the at least one memory <NUM> and the computer program code <NUM> may be arranged to cause the apparatus to at least perform methods described herein, such as those described with reference to <FIG> and/or <NUM>.

The processor <NUM> may be a microprocessor, plural microprocessors, a microcontroller, or plural microcontrollers.

<FIG> shows a non-transitory media <NUM> according to some embodiments. The non-transitory media <NUM> is a computer readable storage medium. It may be e.g. a CD, a DVD, a USB stick, a blue ray disk, etc. The non-transitory media <NUM> stores computer program code causing an apparatus to perform operations described above when executed by a processor such as processor <NUM> of <FIG>.

Any mentioned apparatus and/or other features of particular mentioned apparatus may be provided by apparatus arranged such that they become configured to carry out the desired operations only when enabled, e.g. switched on, or the like. In such cases, they may not necessarily have the appropriate software loaded into the active memory in the non-enabled (e.g. switched off state) and only load the appropriate software in the enabled (e.g. on state). The apparatus may comprise hardware circuitry and/or firmware. The apparatus may comprise software loaded onto memory. Such software/computer programs may be recorded on the same memory/processor/functional units and/or on one or more memories/processors/ functional units.

In some examples, a particular mentioned apparatus may be pre-programmed with the appropriate software to carry out desired operations, and wherein the appropriate software can be enabled for use by a user downloading a "key", for example, to unlock/enable the software and its associated functionality. Advantages associated with such examples can include a reduced requirement to download data when further functionality is required for a device, and this can be useful in examples where a device is perceived to have sufficient capacity to store such pre-programmed software for functionality that may not be enabled by a user.

Any mentioned apparatus/circuitry/elements/processor may have other functions in addition to the mentioned functions, and that these functions may be performed by the same apparatus/circuitry/elements/processor. One or more disclosed aspects may encompass the electronic distribution of associated computer programs and computer programs (which may be source/transport encoded) recorded on an appropriate carrier (e.g. memory, signal).

Any "computer" described herein can comprise a collection of one or more individual processors/processing elements that may or may not be located on the same circuit board, or the same region/position of a circuit board or even the same device. In some examples one or more of any mentioned processors may be distributed over a plurality of devices. The same or different processor/processing elements may perform one or more functions described herein.

The term "signalling" may refer to one or more signals transmitted as a series of transmitted and/or received electrical/optical signals. The series of signals may comprise one, two, three, four or even more individual signal components or distinct signals to make up said signalling. Some or all of these individual signals may be transmitted/received by wireless or wired communication simultaneously, in sequence, and/or such that they temporally overlap one another.

With reference to any discussion of any mentioned computer and/or processor and memory (e.g. including ROM, CD-ROM etc), these may comprise a computer processor, Application Specific Integrated Circuit (ASIC), field-programmable gate array (FPGA), and/or other hardware components that have been programmed in such a way to carry out the inventive function.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole, in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that the disclosed aspects/examples may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the disclosure.

Claim 1:
An apparatus (<NUM>), comprising means for:
transmitting one or more reference signals at a transmit power level using a transmit antenna (<NUM>) of a repeater;
measuring a receive power level of the corresponding one or more reference signals received using a receive antenna (<NUM>) of the repeater, wherein one or both of the transmit and receive antennas comprise an antenna array for respectively transmitting and receiving respective reference signals using a plurality of beams;
determining a self-interference power value based on the difference between the transmit power level of the one or more reference signals and the receive power level of the one or more corresponding reference signals;
determining whether the self-interference power value is above or below a predetermined threshold; and characterised in that comprising further means for:
accessing one or more sets of reference data indicative of an amount of gain reduction or gain increase to apply to a gain associated with an amplifying means (<NUM>) of the repeater, wherein the reference data is indicative of the amount of gain reduction or gain increase to apply for different combinations of transmit (<NUM>) and receive (<NUM>) antenna beams for a given self-interference power value;
modifying, at a given time, the gain for a given beam combination based on the one or more sets of reference data and based on the determination of whether the self-interference power value is above or below the predetermined threshold and based on the one or more sets of reference data, wherein if the self-interference power is below the predetermined threshold, the modifying means is configured to increase the gain, and wherein if the self-interference power value is above the predetermined threshold,
the modifying means is configured to decrease the gain.