Mobile communication system

Abstract

Arrangements are described for receiving an analogue-to -digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system (wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver) and adjusting transmitter processing based, at least in part, on at least one of digital-to-analogue converter, DAC, capability information relating to characteristics of a DAC of the transmitter and the characteristics of the ADC received in the ADC capability report.

Description

Field Example embodiments may relate to systems, methods and / or computer programs for use in mobile communication. Background Mobile communication systems having digital-to-analog (DAC) and / or analog-to-digital (ADC) components having relatively low resolution may be provided for practical reasons. This can present challenges. The embodiments described herein are described in this context. Summary The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. In a first aspect, this specification describes an apparatus (e.g. a transmitter) comprising: means for receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report provides information relating to characteristics of an ADC of the receiver; and means (e.g. a neural network or a machine learned algorithm) for adjusting transmitter processing based, at least in part, on at least one of a digital-to-analog converter, DAC, capability information relating to characteristics of the DAC of the transmitter and the characteristics of the ADC received in the ADC capability report. The ADC capability report may include at least one of: an ADC bit resolution; a distortion function; and an ADC table mapping a bit resolution to a distortion value. Some example embodiments further comprise means for providing a DAC capability report from the transmitter of the mobile communication system to the receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of the digital-to-analog converter of the transmitter. The DAC capability report may, for example, include at least one of: a DAC bit resolution; a distortion function for the digital-to-analog converter; and a DAC table mapping a bit resolution to a distortion value. In some example embodiments, the means for adjusting transmitter processing comprises a neural precompensation module (e.g. implemented using a neural network). The means for adjusting transmitter processing may be configured to compensate for quantization errors (e.g. as introduced by a digital-to-analog converter and / or an analog-to-digltal converter of the communication system). Some example embodiments further comprise means for sending an indication (e.g. a UCI field) of a change in DAC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. Some example embodiments further comprise means for receiving an indication (e.g. a DCI field) of a change in ADC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. In a second aspect, this specification describes an apparatus (e.g. a receiver) comprising: means for receiving a digital-to-analog converter, DAC, capability report from a transmitter of a mobile communication system at a receiver of the mobile communication system, wherein the DAC capability report comprises information relating to characteristics of a DAC of the transmitter; and means for compensating for communication errors in a received signal, based, at least in part, on at least one of the characteristics of the DAC received in the DAC capability report and an analog-to-digital converter, ADC, capability information relating to characteristics of the ADC of the receiver. The DAC capability report may include at least one of: a DAC bit resolution; a distortion function for the digital-to-analog converter; and a DAC table mapping a bit resolution to a distortion value. Some example embodiments further comprise means for sending an ADC capability report from the receiver of the mobile communication system to the transmitter of the mobile communication system, wherein the ADC capability report comprises said information relating to characteristics of an ADC of the receiver. The ADC capability report may, for example, include at least one of: an ADC bit resolution; a distortion function; and an ADC table mapping a bit resolution to a distortion value. The means for compensating for communication errors may comprise a neural equalization module (e.g. in the form of a neural network). The means for compensating for communication error may be configured to compensate for quantization errors (e.g. as introduced by a digital-to-analog converter and / or an analog-to-digital converter of the communication system). Some example embodiments further comprise means for sampling data received at the apparatus from the transmitter, wherein the means for sampling said data has an over-sampling factor greater than one. Some example embodiments further comprise: means for sending an indication (e.g. a DCI field) of a change in ADC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. This may be based on a different receiver resolution per selected receiver antenna. Some example embodiments further comprise means for receiving an indication (e.g. a UCI field) of a change in DAC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. In a third aspect, this specification describes an apparatus (e.g. a transmitter) comprising: means for receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; means for setting (e.g. choosing) a transmission constellation for said transmitter based, at least in part, on at least one of: characteristics of a digital-to-analog converter, DAC, of the transmitter and the characteristics of the ADC received in the ADC capability report; and means for modulating a signal for transmission to the receiver based, at least in part, on the transmission constellation. Some example embodiments further comprise means (e.g. a neural network or a trained machine learning algorithm) for pre-compensating data for transmission from the transmitter to the receiver, based, at least in part, on at least one of said characteristics of the DAC and said characteristics of the ADC. Some example embodiments further comprise means for receiving an indication (e.g. a DCI field) of a change in ADC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. Some example embodiments further comprise means for sending a DAC capability report from the transmitter to the receiver, wherein the DAC capability report provides information relating to said characteristics of said DAC of the transmitter. The apparatus may further comprise means for sending an indication (e.g. a UCI field) of a change in DAC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. The DAC capability report may include a DAC bit resolution and / or a distortion function for the digital-to-analog converter. The DAC capability report may include a DAC table mapping a bit resolution to a distortion value. In some example embodiments, the ADC capability report includes an ADC bit resolution and / or a distortion function (e.g. a noisy distortion function). The ADC capability report may include an ADC table mapping a bit resolution to a distortion value. In a fourth aspect, this specification describes an apparatus (e.g. a transmitter), comprising: means for sending an analog-to-digital converter, ADC, capability report from the apparatus of a mobile communication system to a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the apparatus; and means for demodulating a signal for transmission from the transmitter to the apparatus based, at least in part, on a transmission constellation. Some example embodiments further comprise means for sending an indication of a change in ADC resolution prior to transmission of data from the transmitter to the receiver. Some example embodiments further comprise means for receiving a digital-to-analog converter, DAC, capability report from the transmitter to the receiver, wherein the DAC capability report provides information relating to said characteristics of said DAC of the transmitter. Further, some embodiments comprise means for receiving an indication of a change in DAC resolution prior to transmission of data from the transmitter to the receiver. The DAC capability report may include a DAC bit resolution and / or a distortion function for the digital-to-analog converter. The DAC capability report may include a DAC table mapping a bit resolution to a distortion value. The ADC capability report may include an ADC bit resolution and / or a distortion function (e.g. a noisy distortion function). In some example embodiments, the ADC capability report includes an ADC table mapping a bit resolution to a distortion value. In some of the aspects described above, the apparatus is a user equipment, UE, of the mobile communication system and the receiver is a gNB of the mobile communication system. The alternative configuration is also possible, in which the apparatus is a gNB of a mobile communication system and the receiver is a user equipment of the mobile communication system. In the aspects described above, the mobile communication system may be a MIMO communication system (e.g. a massive MIMO system). In a fifth aspect, this specification describes a method comprising: receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; and adjusting transmitter processing based, at least in part, on at least one of digital-to-analog converter, DAC, capability information relating to characteristics of a DAC of the transmitter and the characteristics of the ADC received in the ADC capability report. The ADC capability report may include at least one of: an ADC bit resolution; a distortion function; and an ADC table mapping a bit resolution to a distortion value. Some example embodiments further comprise providing a DAC capability report from the transmitter of the mobile communication system to the receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of the digital-to-analog converter of the transmitter. The DAC capability report may, for example, include at least one of: a DAC bit resolution; a distortion function for the digital-to-analog converter; and a DAC table mapping a bit resolution to a distortion value. The transmitter processing may be adjusted to compensate for quantization errors (e.g. as introduced by a digital-to-analog converter and / or an analog-to-digital converter of the communication system). Some example embodiments further comprise sending an indication (e.g. a UCI field) of a change in DAC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. Some example embodiments further comprise receiving an indication (e.g. a DCI field) of a change In ADC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. In a sixth aspect, this specification describes a method comprising: receiving a digital-to-analog converter, DAC, capability report from a transmitter of a mobile communication system at a receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of a DAC of the transmitter; and compensating for communication errors in a received signal, based, at least in part, on at least one of the characteristics of the DAC receiver in the DAC capability report and analog-to-digital converter, ADC, capability information relating to characteristics of an ADC of the receiver. The DAC capability report may include at least one of: a DAC bit resolution; a distortion function for the digital-to-analog converter; and a DAC table mapping a bit resolution to a distortion value. Some example embodiments further comprise sending an ADC capability report from the receiver of the mobile communication system to the transmitter of the mobile communication system, wherein the ADC capability report comprises said information relating to characteristics of an ADC of the receiver. The ADC capability report may, for example, include at least one of: an ADC bit resolution; a distortion function; and an ADC table mapping a bit resolution to a distortion value. Compensating for communication error may compensate for quantization errors (e.g. as introduced by a digital-to-analog converter and / or an analog-to-digital converter of the communication system). Some example embodiments further comprise sampling data received at the apparatus from the transmitter, wherein the means for sampling said data has an over-sampling factor greater than one. Some example embodiments further comprise: sending an indication (e.g. a DCI field) of a change in ADC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. This may be based on a different receiver resolution per selected receiver antenna. Some example embodiments further comprise receiving an indication (e.g. a UCI field) of a change in DAC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. In a seventh aspect, this specification describes a method comprising: receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report provides information relating to characteristics of an ADC of the receiver; setting (e.g. choosing) a transmission constellation for said transmitter based, at least in part, on at least one of characteristics of a digital-to-analog converter DAC of the transmitter and / or the characteristics of the ADC received in the ADC capability report; and modulating a signal for transmission to the receiver based, at least in part, on the transmission constellation. The method may comprise pre-compensating data for transmission from the transmitter to the receiver, based, at least in part, on said characteristics of the DAC and said characteristics of the ADC. Some example embodiments further comprise receiving an indication (e.g. a DCI field) of a change in ADC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. Some example embodiments further comprise sending a DAC capability report from the transmitter to the receiver, wherein the DAC capability report provides information relating to said characteristics of said DAC of the transmitter. The apparatus may further comprise means for sending an indication (e.g. a UCI field) of a change in DAC resolution (e.g. for a particular antenna) prior to transmission of data from the transmitter to the receiver. The DAC capability report may include a DAC bit resolution and / or a distortion function for the digital-to-analog converter. The DAC capability report may include a DAC table mapping a bit resolution to a distortion value. In some example embodiments, the ADC capability report includes an ADC bit resolution and / or a distortion function (e.g. a noisy distortion function). The ADC capability report may include an ADC table mapping a bit resolution to a distortion value. In an eighth aspect, this specification describes a method, comprising: sending an analog-to-digltal converter, ADC, capability report from a receiver of a mobile communication system to a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; demodulating a signal for transmission from the transmitter to the receiver based, at least in part, on a transmission constellation. Some example embodiments further comprise sending an indication of a change in ADC resolution prior to transmission of data from the transmitter to the receiver. Some example embodiments further comprise receiving a dlgital-to-analog converter, DAC, capability report from the transmitter to the receiver, wherein the DAC capability report provides information relating to said characteristics of said DAC of the transmitter. Further, some embodiments comprise means for receiving an indication of a change in DAC resolution prior to transmission of data from the transmitter to the receiver. The DAC capability report may include a DAC bit resolution and / or a distortion function for the digital-to-analog converter. The DAC capability report may include a DAC table mapping a bit resolution to a distortion value. The ADC capability report may include an ADC bit resolution and / or a distortion function (e.g. a noisy distortion function). In some example embodiments, the ADC capability report includes an ADC table mapping a bit resolution to a distortion value. In a ninth aspect, this specification describes computer-readable instructions which, when executed by a computing apparatus, cause the computing apparatus to perform (at least) any method as described herein (including the methods of the fifth to eighth aspects described above). In a tenth aspect, this specification describes a computer-readable medium (such as a non-transitory computer-readable medium) comprising program instructions stored thereon for performing (at least) any method as described herein (including the methods of the fifth to eighth aspects described above). In an eleventh aspect, this specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code which, when executed by the at least one processor, causes the apparatus to perform (at least) any method as described herein (including the methods of the fifth to eighth aspects described above). In a twelfth aspect, this system comprising a transmitter as set above (including as set out above with respect to the first or third aspects) and a receiver as set above (including as set out above with respect to the second or fourth aspects). In a thirteen aspect, this specification describes a system comprising a transmitter of a mobile communication system and a receiver of the mobile communication system, wherein: the transmitter comprises: means for sending a digital-to-analog converter, DAC, capability report from the transmitter to the receiver, wherein the DAC capability report comprises information relating to characteristics of a DAC of the transmitter; and the receiver comprises: means for receiving the DAC capability report from the transmitter; and means for compensating for communication errors in a received signal, based, at least In part, on the DAC capability report for the DAC located at the transmitter and / or analog-to-digital converter capability information for an ADC located at the receiver. In a fourteenth aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: receive an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; and adjust transmitter processing based, at least in part, on at least one of digital-to-analog converter, DAC, capability information relating to characteristics of a DAC of the transmitter and the characteristics of the ADC received in the ADC capability report. In a fifteenth aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: receiver a digital-to-analog converter, DAC, capability report from a transmitter of a mobile communication system at a receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of a DAC of the transmitter; and compensate for communication errors in a received signal, based, at least in part, on at least one of the characteristics of the DAC receiver in the DAC capability report and analog-to-digital converter, ADC, capability Information relating to characteristics of an ADC of the receiver. In a sixteenth aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: receive an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report provides information relating to characteristics of an ADC of the receiver; set a transmission constellation for said transmitter based, at least in part, on at least one of characteristics of a digital-to-analog converter DAC of the transmitter and / or the characteristics of the ADC received in the ADC capability report; and modulate a signal for transmission to the receiver based, at least in part, on the transmission constellation. The computer program may comprise instructions, which when executed by the apparatus, cause the apparatus to pre-compensate data for transmission from the transmitter to the receiver, based on said characteristics of the DAC and said characteristics of the ADC. In an seventeenth aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: send an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system to a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; and demodulate a signal for transmission from the transmitter to the receiver based, at least in part, on a transmission constellation. In an eighteenth aspect, this specification describes an apparatus comprising an input (or some other means) for receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; and a control module (or some other means) for adjusting transmitter processing based, at least in part, on at least one of digital-to-analog converter, DAC, capability information relating to characteristics of a DAC of the transmitter and the characteristics of the ADC received in the ADC capability report. In a nineteenth aspect, this specification describes an apparatus comprising an input (or some other means) for receiving a digital-to-analog converter, DAC, capability report from a transmitter of a mobile communication system at a receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of a DAC of the transmitter; and a control module (or some other means) for compensating for communication errors in a received signal, based, at least in part, on at least one of the characteristics of the DAC receiver in the DAC capability report and analog-to-digital converter, ADC, capability information relating to characteristics of an ADC of the receiver. In a twentieth aspect, this specification describes an apparatus comprising an input (or some other means) for receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report provides information relating to characteristics of an ADC of the receiver; a constellation control module (or some other means) for setting a transmission constellation for said transmitter based, at least in part, on at least one of characteristics of a digital-to-analog converter DAC of the transmitter and / or the characteristics of the ADC received in the ADC capability report; and a modulator (or some other means) for modulating a signal for transmission to the receiver based, at least in part, on the transmission constellation. In a twenty-first aspect, this specification describes an apparatus comprising an output (or some other means) for sending an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system to a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; and a demodulator (or some other means) for demodulating a signal for transmission from the transmitter to the receiver based, at least in part, on a transmission constellation. Brief Description of the Drawings Example embodiments will now be described by way of non-limiting example, with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a transmitter used in some example embodiments; FIG. 2 is a block diagram of a receiver used in some example embodiments; FIG. 3 is a message flow sequence in accordance with an example embodiment; FIG. 4 is a message flow sequence in accordance with an example embodiment; FIG. 5 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. 6 is a block diagram of a system in accordance with an example embodiment; FIG. 7 is a block diagram of a system in accordance with an example embodiment; FIG. 8 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. 9 is a block diagram of a system in accordance with an example embodiment; FIG. 10 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. 11 is a block diagram of a system in accordance with an example embodiment; FIG. 12 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. 13 is a schematic diagram of components of one or more of the example embodiments described previously; and FIG. 14 shows tangible media for storing computer-readable code which when run by a computer may perform methods according to example embodiments described herein. Detailed Description In the description and drawings, like reference numerals refer to like elements throughout. FIG. 1 is a block diagram of a transmitter, indicated generally by the reference numeral 10, used in some example embodiments. FIG. 2 is a block diagram of a receiver, indicated generally by the reference numeral 20, used in some example embodiments. The transmitter 10 and the receiver 20 may be used together as part of a mobile communication system. The transmitter 10 comprises a data processor 12 (e.g. comprising an encoder and an OFDM modulator, as discussed in detail below) and a low resolution digital-to-analog converter (DAC) 14. The output of the DAC 14 is provided to a wireless channel 16 via an antenna (and usually using a power amplifier between the DAC 14 and the antenna). The receiver 20 comprises a low-resolution analog-to-digital converter (ADC) 22 and a data processor 24 (e.g. comprising an OFDM demodulator and a data decoder, as discussed in detail below). The ADC 22 receives a signal from the channel 16 and provides a quantized signal to the data processor 24. In the example embodiments described below, uplink (UL) transmission scenarios are generally described in which a transmitter (such as the transmitter 10) is a user device (e.g. a user equipment, UE) equipped with a low-resolution DAC and a receiver (such as the receiver 20) is a network node (e.g. a gNB) equipped with a low-resolution ADC. Note however that the principles described herein are also applicable to the downlink (DL) scenarios. In FIG. 1, the data processor 12 encodes and modulates transmit bits u to generate symbols x = where fc and fm denote encoding and bit-to-symbol mapping functionalities. The symbols are OFDM modulated to yield the signal s which is passed through the DAC 14 that yields the signal sq = Qt(s). By way of example, the distortion function QtQ, may be modelled as follows: Qt(s) = a^s + nt, Where: • a(b£) is the distortion factor of the DAC 14 depending on the bit resolution bt; and • nt is the quantization noise otherwise uncorrelated with s. For example, the distortion factor may be of the form af^) = (1 222^. The signal sq passes through the multipath wireless channel 16. At reception, the received signal r is passed through the ADC 22 that yields the signal rq = Qr(r), By way of example, the distortion function QtQ, may be modelled as follows: Qr W = (1 - p(br)) r + nr, Where: • p(br) is the distortion factor of the low-resolution ADC 22, depending on the number of quantization bits br; and • nr is the uncorrelated quantization noise. Assuming the channel impulse response Is h, then the received signal is: r, = Qr(h * Qt(s) + n) where n is AWGN and denotes convolution. The signal is then OFDM demodulated to yield the signal yq that is the output of the data processor 22. For the receiver 20 to effectively reconstruct the original bits u (i.e. to minimize the reconstruction error between the estimated bits u and original transmit bits u), some mechanism for compensating for the distortion and quantization losses Qt,Qr of the DAC 14 and the ADC 22 respectively may be provided. The principles described herein may be applied to Multiple Input Multiple Output (MIMO) systems. This can present difficulties since power consumption and hardware costs of ADCs and DACs In such systems typically increase linearly within bandwidth and exponentially with the number of quantization bits. Thus, relatively high-resolution ADCs and DACs (e.g., 8-12 bits for commercial use) may result in unacceptably high power consumption and hardware cost. Thus, to cut the hardware costs, low resolution (e.g. a few bits, or event single bit) ADC and DACs may be preferred for use in mobile communication systems, such as MIMO system and massive MIMO systems. Of course, a disadvantage of low-resolution DACs and ADCs is the inherent quantization distortion that they introduce to the transmitted and received signals which tends to translate Into performance loss. FIG. 3 is a message flow sequence, indicated generally by the reference numeral 30, in accordance with an example embodiment. The sequence 30 shows messages transferred between a transmitter 31 (which may be similar to the transmitter 10) and a receiver 32 (which may be similar to the receiver 20). The sequence 30 starts with a message 34 being sent from the transmitter 31 to the receiver 32. The message 34 provides a DAC capability report. As discussed in detail below, the DAC capability report may provide information relating to characteristics of a digital-to-analog converter of the transmitter (such as the DAC 14 described above). The sequence 30 continues with a message 36 being sent from the receiver 32 to the transmitter 31. The message 36 provides an ADC capability report. The ADC capability report may provide information relating to characteristics of an analog-to-digital converter of the receiver (such as the ADC 22 described above). FIG. 4 is a message flow sequence, indicated generally by the reference numeral 40, in accordance with an example embodiment. The sequence 40 shows messages transferred between a UE 41 (which is an example of the transmitter 31 described above) and a gNB 42 (which is an example of the receiver 32 described above). The sequence 40 includes first messages 44 (that may be performed only occasionally, perhaps only once) and second messages 46 that may be sent on each transmission (UL transmission in this example). The message sequence 40 provides a method that seeks to counteract quantization losses introduced by the use of low-resolution DAC / ADC (e.g. in communication systems such as 6G MIMO systems). The example message sequence 40 describes an UL scenario but can be straightforwardly modified for a downlink scenario. The first messages 44 implement a capability exchange process and include the UE 41 informing the gNB 42 via a capability report about its own DAC characteristics. These characteristics may include: • The DAC bit resolution bt and distortion function Qt; or • A DAC table mapping a bit resolution to a distortion value; or • A noisy version of the distortion function Qt - to maintain the UE hardware model privacy. Additionally, or optionally, the gNB 42 may inform the UE 41 about its own ADC characteristics. These characteristics may include: a bit resolution br and a distortion function Qr (or a noisy version of thereof), or an ADC mapping table. The second messages 46 may include (prior to an UL MIMO transmission), the UE 41 informing the gNB whether the UE is using a different DAC resolution per TX antenna. This may be implemented using a new UCI field. Additionally, or optionally (prior to the UL transmission), the gNB may inform the UE whether the UE is using a different ADC resolution per RX antenna. This may be implemented using a new DCI field. The UE 41 may use the information received from the gNB 42 in a neural transmitter that compensates for both DAC and ADC quantization losses (as discussed in detail below). Note that the neural transmitter may operate in a modulation distorted mode e.g. applying a distortion to the QAM-OFDM signal, or it may learn a new constellation (so-called irregular constellation) which is indirectly optimizes the quantization loss. Both options are described further below. Combinations of different embodiments are also possible. The UE transmits the UL MIMO signal via a low-resolution DAC. The gNB 42 then receives the signal, passes it through a low-resolution ADC and applies a neural receiver that compensates for the DAC / ADC quantization loss, by accounting for the DAC and ADC characteristics, as sent by the UE and respectively available locally in the gNB. FIG. 5 is a flow chart showing an algorithm, indicated generally by the reference numeral 50, in accordance with an example embodiment. The algorithm 50 may be implemented by the transmitter 10 and receiver 20 described above. The algorithm 50 starts at operation 52, where DAC capabilities are transferred from the transmitter to the receiver. The operation 52 may form part of the first messages 44 described above and may be used to provides information relating to characteristics of a digital-to-analog converter of the transmitter. At operation 54 (which may be omitted in some example embodiments), ADC capabilities are transferred from the receiver to the transmitter. Again, the operation 54 may form part of the first messages 44 described above. The operation 54 may be used to provide information relating to characteristics of an analog-to-digital converter of the receiver. At operation 56, data is transmitted from the transmitter to the receiver. Finally, at operation 58, compensation for communication errors is performed on the receiver side (i.e. "post-compensation"), based, at least in part, on one or more of the capability reports transferred between the transmitter and receiver. The operations 52 and 54 may be used to implement the first messages 44 of the message flow sequence 40 described above. The operations 56 and 58 may implement at least part of the second messages 46 of the message flow sequence 40. FIG. 6 is a block diagram of a system, indicated generally by the reference numeral 60, in accordance with an example embodiment. The system 60 may be used to implement the algorithm 50 described above. The system 60 comprises a transmitter 61 (which is similar to the transmitter 10 described above) and a receiver 62 (which is similar to the receiver 20 described above). The transmitter 61 comprising an encoder, an OFDM modulator and a low resolution digital-to-analog converter (DAC) in a similar manner to the transmitter 10 described above. The output of the transmitter is provided to a wireless channel 63 via an antenna (e.g. via a power amplifier, not shown). The receiver 62 comprises a low-resolution analog-to-digital converter (ADC), an OFDM demodulator and a data decoder in a similar manner to the receiver 20 described above. The transmitter 61 further comprises a transmitter assistance information module 64. The receiver 62 further comprises a receiver assistance information module 65, a neural equalization module 66 and an oversampler module 67. The transmitter assistance information module 64 can be used to transfer DAC properties (e.g. in the form of a DAC capability report) to the neural equalization module 66 of the receiver. Similarly, the receiver assistance information module 65 can be used to transfer ADC properties (e.g. in the form of an ADC capability report) to the neural equalization module 66. Thus, the transmitter and receiver information modules can be used in the transfer or DAC and / or ADC properties (e.g. implementing the first messages 44 described above). The oversampler module 67 may enable the receiver to draw a tradeoff between performance and power consumption. As noted above, the power consumption of the receiver ADC typically scales with the quantization resolution of the ADC. Increasing the sample rate Fs (i.e. by oversampling) can, in some example embodiments, be more beneficial to the overall operation of the system 60 than increasing the ADC resolution. The neural equalization module 66 seeks to compensate for the quantization effects of both the transmitter 61 and the receiver 62 and equalizes the signal yq. In an example use of the system 60, the transmitting radio device (e.g. UE in UL transmission) shares with the receiver (e.g. gNB) the DAC characteristics via a new RRC IE in e.g. an enhanced UE capability report. This capability report can be provided by the transmitter assistance information module 64 to the neural equalization module 66 and may include one or more of: • The bit resolution bt of the DAC; • The distortion function Qt of the DAC; • A table mapping bt to a distortion level. As noted above, prior to the UL transmission, the transmitter may indicate to the receiver which DAC configuration is being used for the respective transmission. For example, different DAC configuration may be possible, for example based on different power modes. Note that the distortion function Q and the table mapping may be considered by some providers to be sensitive information. In that event, the transmitter may only be required to share the bit resolution bt, which offers most of the benefit that can be achieved at the UE. To de-sensitize the information on the distortion function Q and the table mapping, the UE may share a noisy version of this information. In a use of the system 60, a signal for transmission is passed through an OFDM modulator and low-resolution DAC (with bt bits) of the transmitter 61. At the receiver 62, the received signal may be oversampled using oversampler module 67 to reduce the degradation of low-resolution ADC (with br bits). The quantized and digitalized signal is transformed to frequency domain using OFDM demodulator block. Then, equalization of the received signal and compensation of the nonlinearities caused by the low-resolution DAC and ADC is carried out by the neural equalization module 66. Assistance information (such as one or more of bt, Qt, br, Qr) can be provided as inputs to the neural equalization module 66. FIG. 7 is a block diagram of a system, indicated generally by the reference numeral 70, in accordance with an example embodiment. The system 70 has many similarities with the system 60. The system 70 comprises the transmitter 61 and wireless channel 63 described above and further comprises a receiver 72 that is similar to the receiver 62 described above. Specifically, the receiver 72 comprises a low-resolution analog-to-digital converter (ADC), an OFDM demodulator and a data decoder in a similar manner to the receivers 20 and 60 described above. The receiver also comprises the receiver assistance information module 65 and oversampler module 67 described above. The receiver 72 includes a neural equalization module 76 (that is similar to the neural equalization module 66) and a quantization compensation module 74. In this way, the receiver 72 provides separate blocks for compensation of the non-linearities introduced by the DAC and ADC (the quantization compensation module 74) and for equalization of the OFDM signals (the neural equalization module 76). FIG. 8 is a flow chart showing an algorithm, indicated generally by the reference numeral 80. in accordance with an example embodiment. The algorithm 80 may be implemented by the system 90 described below. The algorithm 80 starts at operation 81, where DAC capabilities are transferred from a transmitter to a receiver. The operation 81 may form part of the first messages 44 described above and may be used to provides information relating to characteristics of a digital-to-analog converter of the transmitter. Note that the operation 81 may be omitted in some example embodiments (for example, if the DAC characteristics are not needed by the receiver, for example if the post-compensation discussed below is omitted). At operation 82, ADC capabilities are transferred from the receiver to the transmitter. Again, the operation 82 may form part of the first messages 44 described above. The operation 82 may be used to provide information relating to characteristics of an analog-to-digital converter of the receiver. At operation 83, transmitter processing is adjusted (so called "pre-compensation") based, for example, on the characteristics of the digital-to-analog converter (e.g. as provided in the DAC capability report) and the characteristics of the analog-to-digital converter received in the ADC capability report (which may be obtained in the operation 82). As discussed below, the operation 83 may be implemented by a neural precompensation module. At operation 84, data is transmitted from the transmitter to the receiver. Finally, at operation 85, compensating for communication errors may be performed on the receiver side (i.e. "post-compensation"), based, at least in part, on the capability reports transferred between the transmitter and receiver. Note that the operation 85 may be omitted in some example embodiments. FIG. 9 is a block diagram of a system, indicated generally by the reference numeral 90, in accordance with an example embodiment. The system 90 may be used to implement the algorithm 80 described above. The system 90 has many similarities with the systems 60 and 70 described above. The system 90 comprises a transmitter 91 (similar to the transmitter 61 described above), the wireless channel 63 described above, and the receiver 62 described above. Note that the receiver 62 could be replaced with the receiver 72 of the system 70 described above. The transmitter 91 comprises an encoder, an OFDM modulator and a low resolution digital-to-analog converter (DAC) in a similar manner to the transmitter 10 described above. The output of the transmitter is provided to a wireless channel 63 via an antenna. The transmitter 91 further comprises the transmitter assistance information module 64 described above and a neural precompensation module 92 that receives DAC characteristics from the transmitter assistance information module 64 (e.g. in the form of a DAC capability report) and receives ADC characteristics from the receiver 62 (e.g. in the form of an ADC capability report). The neural precompensation module 92 seeks to compensate for the quantization effects of both the transmitter 91 and the receiver 62, thereby implementing the operation 83 of the algorithm 80 described above. In the system 90, the receiver 62 may transfer to the transmitter (via a new R.R.C IE) the ADC quantization capability (e.g. br and / or Qr or a noisy version of thereof (as explained in the previous embodiment); a table mapping br to a level of ADC distortion). Then, prior to the UL transmission, the receiver may indicate to the transmitter which ADC configuration is being used for the respective reception of the UL. Then, the transmitter applies a neural quantization compensation which uses both the ADC and DAC characteristics to modify the OFDM signal prior to DAC conversion and over-the-air (OTA) transmission (thereby implementing the operation 83 of the algorithm 80). The role of this block is to compensate in advance for the quantization loss. This neural transmitter may be paired with a neural quantization compensation equalizer and may be trained jointly or separately (with sharing training data only), as discussed further below. FIG. 10 is a flow chart showing an algorithm, indicated generally by the reference numeral 100, in accordance with an example embodiment. The algorithm 100 starts at operation 102, where DAC and ADC capability of a mobile communication system are exchanged. The operation 102 may include an ADC capability report being provided by a receiver to a transmitter of a mobile communication system and / or a DAC capability report being provided by the transmitter to the receiver. As discussed elsewhere, the ADC capability report (if provided) may include information relating to characteristics of an analog-to-digital converter of the receiver and the DAC capability report (if provided) may include information relating to characteristics of a digital-to-analog converter of the transmitter. At operation 104, a transmission constellation for the transmitter Is set (e.g. selected or determined) based, at least in part, on characteristics of the analog-to-digital converter received in the ADC capability report and characteristics of the dlgltal-to-analog converter. At operation 106, data is transmitted from the transmitter to the receiver. Finally, at operation 108, compensating for communication errors may be performed on the receiver side (i.e. "post-compensation"), based, at least in part, on the capability reports transferred between the transmitter and receiver. Note that the operation 108 may be omitted in some example embodiments. Moreover, if the operation 108 is omitted then the provision of the DAC capability report may be omitted from the capability exchange 102. FIG. 11 is a block diagram of a system, indicated generally by the reference numeral 110, in accordance with an example embodiment. The system 110 may be used to implement the algorithm 100 described above. The system 110 has many similarities with the systems 60, 70 and 90 described above. The system 110 comprises a transmitter 111 and a receiver 112. The transmitter 111 comprises an encoder, an OFDM modulator and a low resolution digital-to-analog converter (DAC) in a similar manner to the transmitter 10 described above. The output of the transmitter is provided to a wireless channel 63 via an antenna. The transmitter 111 further comprises the transmitter assistance information module 64 described above and further comprises a constellation module 113 that receives DAC characteristics from the transmitter assistance information module 63 (e.g. in the form of a DAC capability report) and receives ADC characteristics from the receiver 112 (e.g. in the form of an ADC capability report). The constellation module 113 seeks to compensate for the quantization effects of both the transmitter 91 and the receiver 62, thereby implementing the operation 83 of the algorithm 80 described above. The receiver 112 comprises a low-resolution analog-to-digital converter (ADC), an OFDM demodulator and a data decoder in a similar manner to the receivers 20, 60, 70 and 90 described above. The receiver also comprises the receiver assistance information module 65 and oversampler module 66 described above. The receiver 112 includes a neural equalization module 114 and a demodulation module 115. In the system 110, the transmitter 111 may learn and use an irregular constellation that reduces the non-linearities caused by low-resolution DAC / ADC in the transmitter 111 and receiver 112. To achieve this, the receiver 112 may share some information on the considered ADC via a new RRC IE its own ADC quantization capability (e.g. br and / or Qr or a noisy version of thereof; or a table mapping br to a level of ADC distortion). The transmitter lllmay then use a pre-learned constellation based on the received information or learn a new constellation. The transmitter 111 and receiver 112 can coordinate on the learned / used constellation. In the event of joint training over the air (OTA), the receiver 112 may share gradients / feedback with the transmitter 111 to update the constellation points. The receiver 112 may apply a quantization over the gradients based on the considered resolution for DAC / ADC at the transceivers, with the receiver sharing only the quantized version of gradients to reduce signaling overhead. FIG. 12 is a flow chart showing an algorithm, indicated generally by the reference numeral 120, in accordance with an example embodiment. The algorithm 120 is similar to the algorithm 100 described above. The algorithm 120 starts at operation 121, where DAC and ADC capabilities of a mobile communication system are exchanged. The operation 121 may include an ADC capability report being provided by a receiver to a transmitter of a mobile communication system and / or a DAC capability report being provided by the transmitter to the receiver. As discussed elsewhere, the ADC capability report may include information relating to characteristics of an analog-to-digital converter of the receiver and the DAC capability report may include information relating to characteristics of a digital-to-analog converter of the transmitter. At operation 122, a transmission constellation for the transmitter is set (e.g. selected or determined) based, at least in part, on characteristics of the analog-to-digital converter received in the ADC capability report and characteristics of the digital-to-analog converter, as discussed above. At operation 123, transmitter processing is adjusted (so called "pre-compensation") based, for example, on the characteristics of the digital-to-analog converter provided in the DAC capability report and the characteristics of the analog-to-digital converter received in the ADC capability report (which may be obtained in the operation 121). As discussed below, the operation 123 may be implemented by a neural pre-compensation module. At operation 124, data is transmitted from the transmitter to the receiver. Finally, at operation 125, compensating for communication errors may be performed on the receiver side (i.e. "post-compensation"), based, at least in part, on the capability reports transferred between the transmitter and receiver. Note that the operation 125 may be omitted in some example embodiments. Thus, the algorithm 120 includes the pre-compensation of the algorithm 80, the constellation selection of the algorithm 100 and may also include post-compensation at the receiver. A number of the example embodiments described above may use of neural processors, for example as part of the transmitter (e.g. pre-compensation or constellation setting) or as part of the receiver (e.g. post-compensation). Such neural processors may use the principles of deep learning for training purposes. For example, the constellation module 113 of the transmitter 111 may use deep learning to learn a new UE-specific constellation shaped to maximize the link performance between the transmitter and receiver. A loss function may be optimized in order to obtain / learn the trainable parameters of the neural receiver and / or transmitter constellation considering the nonlinearities caused by the low-resolution DAC / ADC. For example, we may consider the cross entropy (CE) function over the transmitted bits b and estimated bits b, i.e., B—l cey y^iogs^Mi-^wi-o / Vn D L—i L—i (d^ED b=0 where CE is the cross entropy between the transmitted bit and estimated bit at RX, averaged over all the data resource elements in the resource grid D and all the B bits in each symbol. Data may be collected and labelled for use in training purposes. For example, the following options are possible: • Label collection over the air (OTA): to obtain the ground truth values at UE, gNB and UE may coordinate to use a pseudo random generator for bit generation, and gNB may configure a seed value for generating synthetic bits. • Label collection based on simulation data: If UE decide to deploy a previously trained neural receiver based on simulation data, label collection Is not a problem as the true / actual value of all the parameters are available in simulators. For completeness, FIG. 13 is a schematic diagram of components of one or more of the example embodiments described previously, which hereafter are referred to generically as a processing system 300. The processing system 300 may, for example, be the apparatus referred to in the claims below. The processing system 300 may have a processor 302, a memory 304 closely coupled to the processor and comprised of a RAM 314 and a ROM 312, and, optionally, a user input 310 and a display 318. The processing system 300 may comprise one or more network / apparatus interfaces 308 for connection to a network / apparatus, e.g. a modem which may be wired or wireless. The network / apparatus interface 308 may also operate as a connection to other apparatus such as device / apparatus which is not network side apparatus. Thus, direct connection between devices / apparatus without network participation is possible. The processor 302 is connected to each of the other components in order to control operation thereof. The memory 304 may comprise a non-volatile memory, such as a hard disk drive (HDD) or a solid state drive (SSD). The ROM 312 of the memory 304 stores, amongst other things, an operating system 315 and may store software applications 316. The RAM 314 of the memory 304 is used by the processor 302 for the temporary storage of data. The operating system 315 may contain code which, when executed by the processor implements aspects of the algorithms and message sequences 30, 40, 50, 80, 100 and 120 described above. Note that in the case of small device / apparatus the memory can be most suitable for small size usage i.e. not always a hard disk drive (HDD) or a solid state drive (SSD) is used. The processor 302 may take any suitable form. For instance, it may be a microcontroller, a plurality of microcontrollers, a processor, or a plurality of processors. The processing system 300 may be a standalone computer, a server, a console, or a network thereof. The processing system 300 and needed structural parts may be all inside device / apparatus such as loT device / apparatus i.e. embedded to very small size. In some example embodiments, the processing system 300 may also be associated with external software applications. These may be applications stored on a remote server device / apparatus and may run partly or exclusively on the remote server device / apparatus. These applications may be termed cloud-hosted applications. The processing system 300 may be in communication with the remote server device / apparatus in order to utilize the software application stored there. FIG. 14 shows a tangible media, in the form of a removable memory unit 365, storing computer-readable code which when run by a computer may perform methods according to example embodiments described above. The removable memory unit 365 may be a memory stick, e.g. a USB memory stick, having internal memory 366 storing the computer-readable code. The internal memory 366 may be accessed by a computer system via a connector 367. Of course, other forms of tangible storage media may be used, as will be readily apparent to those of ordinary skilled in the art. Tangible media can be any device / apparatus capable of storing data / information which data / information can be exchanged between devices / apparatus / network. Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and / or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "memory" or "computer-readable medium" may be any non-transitory media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. Reference to, where relevant, "computer-readable medium", "computer program product", "tangibly embodied computer program" etc., or a "processor" or "processing circuitry" etc. should be understood to encompass not only computers having differing architectures such as single / multi-processor architectures and sequencers / parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices / apparatus and other devices / apparatus. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device / apparatus as instructions for a processor or configured or configuration settings for a fixed function device / apparatus, gate array, programmable logic device / apparatus, etc. The term "means" as used in the description and in the claims may refer to one or more individual elements configured to perform the corresponding recited functionality or functionalities, or it may refer to several elements that perform such functionality or functionalities. Furthermore, several functionalities recited in the claims may be performed by the same individual means or the same combination of means. For example performing such functionality or functionalities may be caused in an apparatus by a processor that executes instructions stored in a memory of the apparatus. If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the abovedescribed functions may be optional or may be combined. Similarly, it will also be appreciated that the flow diagrams, message sequences and block diagrams of Figures 3 to 12 are examples only and that various operations depicted therein may be omitted, reordered and / or combined. It will be appreciated that the above described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification. Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and / or combination of such features. Although various aspects of the invention are set out in the independent claims, other 5 aspects of the invention comprise other combinations of features from the described example embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while the above describes various examples, these io descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. An apparatus comprising:means for receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report provides information relating to characteristics of an ADC of the receiver; andmeans for adjusting transmitter processing based, at least in part, on at least one of a digital-to-analog converter, DAC, capability information relating to characteristics of the DAC of the transmitter and the characteristics of the ADC received in the ADC capability report.

2. The apparatus of claim 1, wherein the ADC capability report includes at least one of:an ADC bit resolution;a distortion function; andan ADC table mapping a bit resolution to a distortion value.

3. The apparatus of claim 1 or claim 2, further comprising means for providing a DAC capability report from the transmitter of the mobile communication system to the receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of the digital-to-analog converter of the transmitter.

4. The apparatus of any claim 3, wherein the DAC capability report includes at least one of:a DAC bit resolution;a distortion function for the digital-to-analog converter; and a DAC table mapping a bit resolution to a distortion value.

5. The apparatus of any one of the preceding claims, wherein the means for adjusting transmitter processing comprises a neural precompensation module.

6. The apparatus of any one of the preceding claims, wherein the means for adjusting transmitter processing is configured to compensate for quantization errors (e.g. as introduced by a digital-to-analog converter and / or an analog-to-digital converter of the communication system).

7. The apparatus of any one of the preceding claims, further comprising:means for sending an indication of a change in DAC resolution prior to transmission of data from the transmitter to the receiver.

8. The apparatus of any one of the preceding claims, further comprising:means for receiving an indication of a change in ADC resolution prior to transmission of data from the transmitter to the receiver.

9. An apparatus comprising:means for receiving a digital-to-analog converter, DAC, capability report from a transmitter of a mobile communication system at a receiver of the mobile communication system, wherein the DAC capability report comprises information relating to characteristics of a DAC of the transmitter; andmeans for compensating for communication errors in a received signal, based, at least in part, on at least one of the characteristics of the DAC received in the DAC capability report and an analog-to-digital converter, ADC, capability information relating to characteristics of the ADC of the receiver.

10. The apparatus of claim 9, wherein the DAC capability report includes at least one of:a DAC bit resolution;a distortion function for the digital-to-analog converter; anda DAC table mapping a bit resolution to a distortion value.

11. The apparatus of claim 9 or claim 10, further comprising means for sending an ADC capability report from the receiver of the mobile communication system to the transmitter of the mobile communication system, wherein the ADC capability report comprises said information relating to characteristics of an ADC of the receiver.

12. The apparatus of claim 11, wherein the ADC capability report includes at least one of:an ADC bit resolution;a distortion function; andan ADC table mapping a bit resolution to a distortion value.

13. The apparatus of any one of claims 9 to 12, wherein the means for compensating for communication errors comprises a neural equalization module.

14. The apparatus of any one of claims 9 to 13, wherein the means for compensating for communication error is configured to compensate for quantization errors (e.g. as introduced by a digital-to-analog converter and / or an analog-to-digital converter of the communication system).

15. The apparatus of any one of claims 9 to 14, further comprising means for sampling data received at the apparatus from the transmitter, wherein the means for sampling said data has an over-sampling factor greater than one.

16. The apparatus of any one of claims 9 to 15, further comprising: means for sending an indication of a change in ADC resolution prior to transmission of data from the transmitter to the receiver.

17. The apparatus of any one of claims 9 to 16, further comprising: means for receiving an indication of a change in DAC resolution prior to transmission of data from the transmitter to the receiver.

18. A method comprising:receiving an analog-to-digital converter, ADC, capability report from a receiver of a mobile communication system at a transmitter of the mobile communication system, wherein the ADC capability report comprises information relating to characteristics of an ADC of the receiver; andadjusting transmitter processing based, at least in part, on at least one of digital-to-analog converter, DAC, capability information relating to characteristics of a DAC of the transmitter and the characteristics of the ADC received in the ADC capability report.

19. A method comprising:receiving a digital-to-analog converter, DAC, capability report from a transmitter of a mobile communication system at a receiver of the mobile communication system, wherein the DAC capability report provides information relating to characteristics of a DAC of the transmitter; andcompensating for communication errors in a received signal, based, at least In part, on at least one of the characteristics of the DAC receiver in the DAC capability report and analog-to-digital converter, ADC, capability information relating to characteristics of an ADC of the receiver.

20. A system comprising a transmitter of a mobile communication system and a receiver of the mobile communication system, wherein:the transmitter comprises: means for sending a digital-to-analog converter, DAC, capability report from the transmitter to the receiver, wherein the DAC capability report comprises information relating to characteristics of a DAC of the transmitter; means for receiving an analog-to-digital converter, ADC, capability report from the receiver, wherein the ADC capability report provides information relating to characteristics of an ADC of the receiver; and means for adjusting transmitter processing based, at least in part, on the characteristics of the DAC and / or the characteristics of the ADC; andthe receiver comprises: means for receiving the DAC capability report from the transmitter; means for providing the ADC capability information to the transmitter; and means for compensating for communication errors, based, at least in part, on the characteristics of the DAC converter and / or the characteristics of the ADC.

21. A system comprising a transmitter of a mobile communication system and a receiver of the mobile communication system, wherein:the transmitter comprises: means for sending a digital-to-analog converter, DAC, capability report from the transmitter to the receiver, wherein the DAC capability report comprises information relating to characteristics of a DAC of the transmitter; andthe receiver comprises: means for receiving the DAC capability report from the transmitter; and means for compensating for communication errors in a received signal, based, at least in part, on the DAC capability report for the DAC located at the transmitter and / or analog-to-digital converter capability information for an ADC located at the receiver.

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