Method and device for detecting discontinuous transmission (DTX) assisted by noise estimation

Abstract

Described is a method of processing a signal received at an uplink control information (UCI) receiver in a wireless communication system. The method comprises processing a signal received on an uplink (UL) at said UCI receiver to transform said received signal into a likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N) and determining a maximum magnitude θ.sub.max value from said likelihood calculation. The method includes comparing said maximum magnitude θ.sub.max value to a selected, calculated or predetermined scaled threshold S.Math.τ where τ is a threshold and S is a scaling factor for the threshold τ. The comparison step is such that, where |θ.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received comprises a linear block encoded signal. In the method, prior to said comparison step, the scaling factor S is selected from a plurality of scaling factor options. One scaling factor option (i) is a scaling factor S.sub.RE derived from a combination of estimated noise and/or signal power at an output of a resource element (RE) demapper module and an estimated channel response from/before an equalizer module of said UCI receiver. The options also include using a combination of S.sub.RE and a suitable scaling factor derived excluding option (i).

Claims

1. A method of processing a signal received at an uplink control information (UCI) receiver in a wireless communication system, the method comprising: processing a signal received on an uplink (UL) at said UCI receiver to transform said received signal into a likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N); determining a maximum magnitude θ.sub.max value from said likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N); and comparing said maximum magnitude θ.sub.max value to a selected, calculated or predetermined scaled threshold S.Math.τ where τ is a threshold and S is a scaling factor for the threshold τ and said scaled threshold S.Math.τ is a product of the threshold τ and the scaling factor S, the comparison being such that, where |θ.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver comprises a linear block encoded signal; wherein, prior to said comparison step, the scaling factor S is selected from a plurality of scaling factor options.

2. The method of claim 1, wherein, where |θ.sub.max|.sup.2≤S.Math.τ, the method comprises outputting a discontinuous transmission (DTX) signal.

3. The method of claim 1, wherein the scaling factor options comprise: (i) S=S.sub.RE where S.sub.RE is derived from a combination of estimated noise and/or signal power at an output of a resource element (RE) demapper module of the UCI receiver and an estimated channel response from or before an equalizer module of said UCI receiver; (ii) S=S.sub.OTHER where S.sub.OTHER is any method of deriving a suitable scaling factor excluding option (i); and (iii) S=S.sub.COMB where S.sub.COMB is derived from a combination of S.sub.RE and S.sub.OTHER.

4. The method of claim 3, wherein S.sub.COMB=f(S.sub.OTHER,S.sub.RE)=α(S.sub.OTHER).sup.λ.Math.(S.sub.RE).sup.1-λ, where λ comprises a weighting value less than or equal to 1 and α comprises a combination coefficient.

5. The method of claim 4, wherein the combination coefficient α is derived from a payload bit length.

6. The method of claim 3, wherein S.sub.OTHER=S.sub.HAD where S.sub.HAD is derived from a multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N) of the signal received on the UL at said UCI receiver.

7. The method of claim 6, wherein S.sub.COMB=f(S.sub.HAD,S.sub.RE)=α(S.sub.HAD).sup.λ.Math.(S.sub.RE).sup.1-λ, where λ comprises a weighting value less than or equal to 1.

8. The method of claim 7, wherein λ>0.5, and is preferably equal to 0.667, and α=1.

9. The method of claim 3, wherein the step of selecting the scaling factor S from the plurality of scaling factor options comprises: selecting option (i) if the accuracy of the estimated noise and/or signal power at the output of the RE demapper module is at an acceptable or better level, otherwise; selecting option (iii) if the number of UCI payload bits is large, otherwise; selecting option (ii).

10. The method of claim 3, wherein the step of selecting the scaling factor S from the plurality of scaling factor options comprises: select option (ii) if a code mask is not applied at an encoder module of the UCI receiver, otherwise; select option (iii) if a code mask is applied.

11. The method of claim 3, wherein the step of selecting the scaling factor S from the plurality of scaling factor options comprises: select option (ii) if a payload bit length is smaller than or equal to a maximum unmask bit payload length, otherwise; select option (iii) if the payload bit length is larger than the maximum unmask bit payload length.

12. The method of claim 1, wherein S=S.sub.RE and S.sub.RE is derived from: $S_{\mathrm{RE}}=\underset{r}{.Math.}\underset{l}{.Math.}\underset{k}{.Math.}\frac{g_{r,l,k}.Math.g_{r,l,k}^{*}}{{\sigma }_r^2}$ where σ.sub.r.sup.Z is the estimated noise variance or signal power corresponding to the r-th receiver antenna obtained at the output of the RE demapper module; g.sub.r,l,k is the estimated channel response from the equalizer module with r comprising a receiver antenna index value, l comprising a time domain index value and k comprising a frequency domain index value.

13. The method of claim 1, wherein the step of selecting the scaling factor S is omitted such that the comparison step comprises comparing said θ.sub.max value to the scaled threshold S.Math.τ such that, where |θ.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver comprises a linear block encoded signal.

14. The method of claim 1, wherein the likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N) comprises a multi-dimensional discrete Fourier Transform (DFT) (θ.sub.1 . . . θi . . . θ.sub.N) of said signal received on the UL at said UCI receiver and the maximum magnitude θ.sub.max value is derived from a plurality of real numbers comprising said multi-dimensional DFT.

15. The method of claim 14, wherein the multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N) comprises a Hadamard transform of the signal received on the UL at said UCI receiver.

16. The method of claim 1, wherein the method is utilized to determine that the signal received on the UL at said UCI receiver comprises a small block encoded signal in a long-term evolution (LTE) communication system.

17. The method of claim 16, wherein the method is utilized to determine DTX in a small block encoded signal comprising a new radio (NR) Physical Uplink Control Channel (PUCCH) format such as PUCCH format 2, PUCCH format 3, or PUCCH format 4.

18. The method of claim 1, wherein the linear block code comprises Reed-Muller (RM) code or RM-based super code.

19. An uplink control information (UCI) receiver in a wireless communication system, the receiver comprising: a memory storing machine-readable instructions; and a processor for executing the machine-readable instructions such that, when the processor executes the machine-readable instructions, it configures the receiver to: process a signal received on an uplink (UL) at said UCI receiver to transform said received signal into a likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N); determine a maximum magnitude θ.sub.max value from said likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N); and compare said maximum magnitude θ.sub.max value to a selected, calculated or predetermined scaled threshold S.Math.τ where τ is a threshold and S is a scaling factor for the threshold τ and said scaled threshold S.Math.τ is a product of the threshold τ and the scaling factor S, the comparison being such that, where |θ.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver comprises a linear block encoded signal; wherein, prior to said comparison step, the scaling factor S is selected from a plurality of scaling factor options.

20. A method of processing a signal received at an uplink control information (UCI) receiver in a wireless communication system, the method comprising: processing a signal received on an uplink (UL) at said UCI receiver to transform said received signal into a likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N); determining a maximum magnitude θ.sub.max value from said likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N); and comparing said θ.sub.max value to a selected, calculated or predetermined scaled threshold S.Math.τ where τ is a threshold and S is a scaling factor for the threshold τ and said scaled threshold S.Math.τ is a product of the threshold τ and the scaling factor S, and where the scaling factor is S derived from a combination of estimated noise and/or signal power at an output of a resource element (RE) demapper module of the UCI receiver and an estimated channel response from an equalizer module of said UCI receiver, the comparison being such that, where |.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver comprises a linear block encoded signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figures, of which:

(2) FIG. 1 is a signal diagram illustrating message exchanges between a BS and a UE for retransmission of control data and payload data;

(3) FIG. 2 is a signal diagram illustrating errant transmission of control data and payload data from a BS to a UE when a UCI receiver at the BS determines a false ACK message;

(4) FIG. 3 is a block schematic diagram of a conventional polar code-based receiver for a 5G communications system;

(5) FIG. 4 is a block schematic diagram of a conventional small block code-based receiver for a 5G communications system;

(6) FIG. 5 is a block schematic diagram of a UCI receiver in accordance with the invention;

(7) FIG. 6 is a block diagram illustrating an improved scaling factor determination method in accordance with one aspect of the present invention;

(8) FIG. 7 is a diagram schematically illustrating method steps in accordance with the invention performed by the UCI receiver of FIG. 5 utilizing the improved scaling factor determined by the method of FIG. 6;

(9) FIG. 8 is a block diagram illustrating a combined scaling factor determination method in accordance with another aspect of the present invention;

(10) FIG. 9 is a block diagram illustrating a scaling factor selection method in accordance with another aspect of the present invention;

(11) FIG. 10 is a diagram schematically illustrating method steps in accordance with the invention performed by the UCI receiver of FIG. 5 utilizing a scaling factor derived from a multi-dimensional DFT of the signal received on the UL at said UCI receiver;

(12) FIG. 11 is a block diagram illustrating a combined scaling factor determination method based on the improved scaling factor determined by the method of FIG. 6 and the scaling factor derived from the multi-dimensional DFT of the signal received on the UL at said UCI receiver, and

(13) FIG. 12 is a block diagram illustrating a scaling factor selection method in accordance with another aspect of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

(14) The following description is of preferred embodiments by way of example only and without limitation to the combination of features necessary for carrying the invention into effect.

(15) Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments, but not other embodiments.

(16) It should be understood that the elements shown in the FIGS, may be implemented in various forms of hardware, software or combinations thereof. These elements may be implemented in a combination of hardware and software on one or more appropriately programmed general-purpose devices, which may include a processor, memory and input/output interfaces.

(17) The present description illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope.

(18) Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

(19) Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herein represent conceptual views of systems and devices embodying the principles of the invention.

(20) The functions of the various elements shown in the figures may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (“DSP”) hardware, read-only memory (“ROM”) for storing software, random access memory (“RAM”), and non-volatile storage.

(21) In the claims hereof, any element expressed as a means for performing a specified function is intended to encompass any way of performing that function including, for example, a) a combination of circuit elements that performs that function or b) software in any form, including, therefore, firmware, microcode or the like, combined with appropriate circuitry for executing that software to perform the function. The invention as defined by such claims resides in the fact that the functionalities provided by the various recited means are combined and brought together in the manner which the claims call for. It is thus regarded that any means that can provide those functionalities are equivalent to those shown herein.

(22) The invention relates to a method for detecting acknowledgment (ACK), negative acknowledgment (NACK) and discontinuous transmission (DTX) signals accurately in uplink control information (UCI) in wireless communication systems. It is particularly useful for DTX detection in small block code-based receivers where cyclic redundancy check CRC is not available for DTX detection.

(23) FIG. 5 shows an exemplary embodiment of an improved UCI receiver device 100 in accordance with concepts of the present invention. In the illustrated embodiment, the UCI receiver device 100 may comprise communication equipment such as a network node, a network card, or a network circuit communicatively connected to or forming part of a BS 103 (denoted by dashed line in FIG. 5), etc. operating in a 5G communications system environment 115, although the improved UCI receiver device 100 of the invention is not limited to operating in a 5G communications system but could comprise a UCI receiver device for a 4G cellular network or any cellular network. The BS 103 communicates with one or more UEs 125.

(24) The UCI receiver device 100 may comprise a plurality of functional blocks for performing various functions thereof. For example, the UCI receiver device 100 includes receiver module 110 providing received signal processing and configured to provide received signals and/or information extracted therefrom to functional block module(s) 120 such as may comprise various data sink, control element(s), user interface(s), etc. Although receiver module 110 is described as providing received signal processing, it will be appreciated that this functional block may be implemented as a transceiver providing both transmitted and received signal processing. Irrespective of the particular configuration of receiver 110, embodiments include signal detection module 130 disposed in association with the receiver module 110 for facilitating accurate processing and/or decoding of a received channel signal in accordance with the invention. Channel signals may be received via an antenna module 105.

(25) Although the signal detection module 130 is shown as being deployed as part of the receiver module 110 (e.g. comprising a portion of the receiver module control and logic circuits), there is no limitation to such a deployment configuration according to the concepts of the invention. For example, the signal detection module 130 may be deployed as a functional block of UCI receiver device 100 that is distinct from, but connected to, receiver module 110. The signal detection module 130 may, for example, be implemented using logic circuits and/or executable code/machine readable instructions stored in a memory 140 of the UCI receiver device 100 for execution by a processor 150 to thereby perform functions as described herein. For example, the executable code/machine readable instructions may be stored in one or more memories 140 (e.g. random access memory (RAM), read only memory (ROM), flash memory, magnetic memory, optical memory or the like) suitable for storing one or more instruction sets (e.g. application software, firmware, operating system, applets, and/or the like), data (e.g. configuration parameters, operating parameters and/or thresholds, collected data, processed data, and/or the like), etc. The one or more memories 140 may comprise processor-readable memories for use with respect to one or more processors 150 operable to execute code segments of signal detection module 130 and/or utilize data provided thereby to perform functions of the signal detection module 130 as described herein. Additionally, or alternatively, the signal detection module 130 may comprise one or more special purpose processors (e.g. application specific integrated circuit (ASIC), field programmable gate array (FPGA), graphics processing unit (GPU), and/or the like configured to perform functions of the signal detection module 130 as described herein.

(26) FIG. 6 provides a block diagram illustrating an improved scaling factor S.sub.RE determination method and utilization of the improved scaling factor determined thereby in determining a DTX state in accordance with one aspect of the present invention. The scaling factor S.sub.RE is determined, calculated or derived from a combination of estimated noise and/or signal power at an output of the RE demapper module of the UCI receiver device 100 and an estimated channel response from the equalizer module of said UCI receiver device 100. By improving the scaling factor S, the determination of a DTX state becomes more accurate. The improved scaling factor S.sub.RE makes use of the estimated noise and/or signal power at the output of the RE demapper module which has not previously been effectively used. Consequently, where |θ.sub.max|.sup.2>S.sub.RE.Math.τ, where τ is a predetermined threshold, the method comprises determining that the signal received on the UL at said UCI receiver device 100 comprises a linear block encoded signal and conversely, where |θ.sub.max|.sup.2≤S.sub.RE.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver device 100 comprises a DTX state.

(27) The scaling factor S.sub.RE is preferably derived from the equation:

(28) $S_{\mathrm{RE}}=\underset{r}{.Math.}\underset{l}{.Math.}\underset{k}{.Math.}\frac{g_{r,l,k}.Math.g_{r,l,k}^{*}}{{\sigma }_r^2}$

(29) where σ.sub.r.sup.2 is the estimated noise variance or signal power corresponding to the r-th receiver antenna obtained at the output of the RE demapper module; and

(30) g.sub.r,l,k is the estimated channel response obtained before the equalizer module as an input to the equalizer module with r comprising a receiver antenna index value, l comprising a time domain index value, e.g. an OFDM symbol index, and k comprising a frequency domain index value, e.g. a subcarrier index.

(31) FIG. 7 schematically illustrates an improved linear block code-based (UCI) receiver device 100/200, an improved decoder 210 for the improved linear block code-based (UCI) receiver device 100/200, and improved and enhanced methods implemented by the signal detection module 130 comprising the improved decoder 210 for the improved linear block code-based (UCI) receiver device 100/200 or for the UCI receiver device 100 of FIG. 5.

(32) As described in greater detail below, the signal detection module 130 comprising the improved decoder 210 is configured to implement improved detection or determination of acknowledgment (ACK), negative acknowledgment (NACK) and discontinuous transmission (DTX) signals accurately in uplink control information (UCI) in wireless communication systems.

(33) In one embodiment, the UCI receiver device 100/200 is configured to receive a UL UCI signal as a demapper output signal. The demapper output signal is firstly equalized in a known manner in an equalizer module 202 to provide an equalized signal. The equalized signal is then demodulated and descrambled again in a known manner by a demodulation/descrambling module 204 which outputs soft bits to the improved decoder 210. In FIG. 6, the improved decoder 210 is shown as a small block code decoder 210 but it will be understood that this is shown by way of example only. The small block code decoder 210 is configured to process said received signal in a transform module 210A to transform, in step 300, said received signal into a likelihood calculation of possible transmitted codewords in said received signal. Preferably, the likelihood calculation of possible transmitted codewords comprises a multi-dimensional discrete Fourier transform (DFT) (θ.sub.1 . . . θi . . . θ.sub.N) of said received signal. The UL UCI signal is received at the UCI receiver device 100/200 from a UE 125 operating in the 5G communications system environment 115 and which is wirelessly connected to the BS 103 via a UL channel. However, it will be understood that the signal received at the UCI receiver device 100/200 may only comprise noise in an instance where the UE 125 has missed a DL control message from the BS 103 and the UE 125 has therefore not issued any message or signal in response to the missed DL control message. In this case, the UCI receiver device 100/200 anticipates receiving a reply message from the UE 125 and therefore treats received noise as a UL UCI signal to be processed. In either case, the small block code decoder 210 processes the ‘received signal’ whether it is a real UL UCI signal from the UE 125 or whether it is a noise signal mistakenly taken as being a real UL UCI signal from the UE 125 to transform said signal into the multi-dimensional discrete Fourier transform (DFT) (θ.sub.1 . . . θi . . . θ.sub.N).

(34) As indicated above, the signal detection module 130 of FIG. 5 may comprise the improved decoder 210 for an improved linear block code-based (UCI) receiver device 100/200 of FIG. 7 with, in one embodiment, the improved decoder 210 replacing the polar code decoder forming part of the conventional polar code-based receiver of FIG. 3 or, more preferably, in another embodiment, the improved decoder 210 replacing, as shown in FIG. 7, the small block code decoder forming part of the conventional small block code-based receiver of FIG. 4.

(35) It will be understood from the description that the signal detection module 130 comprising the improved decoder 210 may be implemented through any of software, firmware and/or hardware changes to conventional linear block code decoders, although it is possible to implement the improved decoder 210 of the invention by implementing only software changes.

(36) The likelihood calculation of possible transmitted codewords in the UL UCI signal received at said UCI receiver device 100/200 may be expressed as likelihood values. The multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N) may comprise a Hadamard transform of said received signal. The Hadamard transform is also known as the Walsh-Hadamard transform, the Hadamard-Rademacher-Walsh transform, the Walsh transform or the Walsh-Fourier transform. Herein, it will be referred to as the ‘Hadamard transform’ but encompasses all forms of said transform.

(37) A module 210B of the small block code decoder 210 is configured to determine, in step 305, a maximum magnitude θ.sub.max value from said likelihood calculation of possible transmitted codewords. The maximum magnitude θ.sub.max value may be determined or calculated from a plurality of real numbers comprising said multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N).

(38) In conventional UCI receivers as exemplified by FIGS. 3 and 4, the UCI bits denoting ACK or NACK messages are derived from the maximum magnitude θ.sub.max value's index and sign. Similarly, a UCI-bits module 210C of the small block code decoder 210 is configured to generate, in a known manner in step 310, UCI bits according to the index and sign of the maximum magnitude θ.sub.max value.

(39) As already described with respect to FIG. 4, the absence of a CRC function in the conventional small block code-based receiver prevents a determination of whether or not a received UL UCI signal is, in fact, indicative of a DTX state rather than an ACK or NACK message. In other words, the absence of a CRC function prevents a determination being made between DTX on the one hand and ACK/NACK on the other hand.

(40) Comparing said θ.sub.max value or, more preferably |θ.sub.max|.sup.2, to a selected, calculated or predetermined scaled threshold S.Math.τ where S is the scaling factor for the threshold τ and said scaled threshold S.Math.τ is obtained by multiplying the threshold τ by the scaling factor S, the comparison being such that, where |θ.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver comprises a linear block encoded signal.

(41) A first embodiment of the method of the invention includes, in step 315, the step of comparing said |θ.sub.max|.sup.2 value to the scaled threshold S.sub.RE.Math.τ. The scaling factor S.sub.RE may be obtained by a DTX detector for UCI module 210D by estimating the scaling factor S.sub.RE from the combination of estimated noise and/or signal power at the output of the RE demapper module of the UCI receiver device 100/200 and the estimated channel response from the equalizer module 202 of said UCI receiver device 100/200.

(42) The DTX detector for UCI module 210D for the small block code decoder 210 has loaded into a memory thereof the predetermined threshold τ. The threshold τ is preferably derived from a target detection performance and a number of detection occurrences in the signal received on the UL at said UCI receiver device 100/200. The target detection performance may comprise any of: a target probability of detecting DTX as an acknowledgement message (ACK) (Pr(DTX.fwdarw.ACK)); a target probability of detecting DTX as a transmitted message (TX) (Pr(DTX.fwdarw.TX)); or a target probability of detecting a false alarm (Pr(FA)) in the signal received on the UL at said UCI receiver device 100/200.

(43) The number of detection occurrences is preferably determined from a number of payload bits and/or a number of encoded bits in the signal received on the UL at said UCI receiver device 100/200.

(44) The threshold τ may also be determined according to a tail probability of the distribution of the multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N).

(45) More particularly, the threshold τ is derived from:

(46) $\tau =Q^{-1}\left(\frac{1}{2}-\frac{1}{2}{\left(P_{\mathrm{detect}}\right)}^{\frac{1}{N_{\mathrm{detect}}}}\right),$

(47) where

(48) where Q.sup.−1(.Math.) is the inverse Q-function

(49) N.sub.detect=2.sup.N.sup.bit.sup.−1

(50) P.sub.detect=1−2Pr(DTX.fwdarw.ACK), or 1−Pr(DTX.fwdarw.TX), or 1−Pr(FA), and

(51) N.sub.bit is a number of payload bits and/or a number of encoded bits in the in the signal received on the UL at said UCI receiver device 100/200.

(52) In FIG. 7, only P.sub.detect=1−2Pr(DTX.fwdarw.ACK) is shown for clarity of the drawing.

(53) The threshold τ is dependent on two inputs, namely the target probability and the number of payload bits and/or a number of encoded bits as hereinbefore described. As such, the threshold τ can be predetermined and loaded into the memory 140 of the UCI receiver device 100/200. As such, the threshold τ does not necessarily need to be determined in real-time. Furthermore, the scaled threshold S.Math.τ is suitable for different channels or channel conditions which greatly simplifies the method of the invention and reduces the computational workload in the signal detection module 130/small block code decoder 210.

(54) The small block code decoder 210 is configured, in step 315, to determine whether or not the signal received on the UL at said UCI receiver device 100/200 comprises a linear block encoded signal when |θ.sub.max|.sup.2>S.Math.τ. However, where |θ.sub.max|.sup.2≤S.Math.τ, a discontinuous transmission (DTX) signal is outputted at step 315.

(55) In the case where |θ.sub.max|.sup.2>S.Math.τ, step 315 may be enhanced to output an acknowledgement (ACK) message or a negative-acknowledgement (NACK) message based on the generated UCI bits.

(56) The method described with respect to FIG. 7 make uses of only the improved scaling factor S.sub.RE and therefore references to S in the above description can be taken to be references to S.sub.RE. However, in the following description S may comprise one of a number of scaling factor options as will be described and thus references to S may comprise references to any of said scaling factor options.

(57) Referring to FIG. 8, provided is a block diagram illustrating a combined scaling factor S.sub.COMB determination method and utilization of the combined scaling factor S.sub.COMB determined thereby in determining a DTX state in accordance with another aspect of the present invention. The scaling factor S.sub.COMB is determined, calculated or derived from a combination of the improved scaling factor S.sub.RE and any other scaling factor S.sub.OTHER suitable for determining a DTX state. S.sub.OTHER may comprise known scaling factors for determining a DTX state. The scaling factor S.sub.COMB=f(S.sub.OTHER,S.sub.RE)=α(S.sub.OTHER).sup.λ.Math.(S.sub.RE).sup.1-λ, where λ comprises a weighting value less than 1 and α comprises a combination coefficient. The scaling factor S.sub.COMB is therefore derived from a function of the improved scaling factor S.sub.RE and any other scaling factor S.sub.OTHER suitable for determining a DTX state. The combination coefficient α may be derived from a payload bit length. In some embodiments, the combination coefficient α is equal to 1. The combination coefficient α can be a sigmoid function of the payload bit length l. The weighting value λ may be greater than 0.5, but is preferably equal to 0.667 (or ⅔), although it may take other values such as 0 or 1.

(58) In some embodiments, the combination coefficient α can take the expression of the payload bit length l:

(59) $\alpha =c.Math.\exp \left(\frac{-{\left(l-l_g\right)}^{\omega }}{d}\right)+{\alpha }_g$

(60) where c is a scaling coefficient, l.sub.0 is a constant offset, d is a normalization factor, ω is the exponent and α.sub.0 are parameters of the combination coefficient α. Typical values of the parameters may be 0=0.2, Ω=2, l.sub.0=2, d=25, α.sub.0=0.945.

(61) Consequently, in this aspect of the invention, the method comprises determining that the signal received on the UL at said UCI receiver device 100/200 comprises a linear block encoded signal when where |θ.sub.max|.sup.2>S.sub.COMB.Math.τ and conversely, where |θ.sub.max|.sup.2≤S.sub.COMB.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver device 100/200 comprises a DTX state.

(62) FIG. 9 illustrates another aspect of the invention where the scaling factor S may be selected from a number of scaling factor options. The method includes selecting as the scaling factor S one of (i) S.sub.RE, (ii) S.sub.OTHER, or (iii) S.sub.COMB. The selection of which scaling factor option to choose may be based on one or more signal conditions. For example, option (i) may be selected if the estimated noise and/or signal power at the output of the RE demapper module is at an acceptable or better level; otherwise option (iii) may be selected if the number of UCI payload bits is large; otherwise option (ii) is selected. In some embodiments, option (ii) may be selected if a code mask is not applied at the encoder module of the UCI receiver; otherwise option (iii) may be selected if a code mask is applied. In yet other embodiments, option (ii) may be selected if a payload bit length is smaller than or equal to a maximum unmask bit payload length; otherwise option (iii) may be selected if the payload bit length is larger than the maximum unmask bit payload length. The maximum unmask payload bit length can take the value of 6 when the block code length is 32.

(63) It will be noted that the step of selecting a scaling factor option is implemented prior to the step of comparing the resultant scaled threshold S.Math.τ to the maximum magnitude θ.sub.max value, i.e. to |θ.sub.max|.sup.2, or configured as a default option.

(64) In some embodiments, S.sub.OTHER=S.sub.HAD. FIG. 10 provides a diagram schematically illustrating method steps in accordance with the invention performed by the UCI receiver 100 of FIG. 5 utilizing the scaling factor S.sub.HAD derived from the multi-dimensional DFT of the signal received on the UL at said UCI receiver 100.

(65) FIG. 10 schematically illustrates the improved linear block code-based (UCI) receiver device 100′/200′, an improved decoder 210′A for the improved linear block code-based (UCI) receiver device 100′/200′, and improved and enhanced methods implemented by the signal detection module 130 comprising the improved decoder 210′ for the improved linear block code-based (UCI) receiver device 100′/200′ or for the UCI receiver device 100 of FIG. 5.

(66) As described above, the signal detection module 130 comprising the improved decoder 210′ is configured to implement improved detection or determination of acknowledgment (ACK), negative acknowledgment (NACK) and discontinuous transmission (DTX) signals accurately in uplink control information (UCI) in wireless communication systems.

(67) The UCI receiver device 100′/200′ receives the UL UCI signal as a RE demapper output signal which is firstly equalized in an equalizer module 202′ to provide an equalized signal. The equalized signal is then demodulated and descrambled again by a demodulation/descrambling module 204′ which outputs soft bits to the improved decoder 210′. In FIG. 10, the improved decoder 210′ is shown as a small block code decoder 210′ but it will be understood that this is shown by way of example only. The small block code decoder 210′ is configured to process said received signal in a transform module 210′A to transform, in step 300′, said received signal into a likelihood calculation of possible transmitted codewords in said received signal. The likelihood calculation of possible transmitted codewords comprises a multi-dimensional discrete Fourier transform (DFT) (θ.sub.1 . . . θi . . . θ.sub.N) of said received signal. The UL UCI signal is received at the UCI receiver device 100′/200′ from a UE 125′ operating in the 5G communications system environment 115′ and which is wirelessly connected to the BS 103′ via a UL channel. The small block code decoder 210′ processes the ‘received signal’ whether it is a real UL UCI signal from the UE 125′ or whether it is a noise signal mistakenly taken as being a real UL UCI signal from the UE 125′ to transform said signal into the multi-dimensional discrete Fourier transform (DFT) (θ.sub.1 . . . θi . . . θ.sub.N).

(68) The likelihood calculation of possible transmitted codewords in the UL UCI signal received at said UCI receiver device 100′/200′ may be expressed as likelihood values. The multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N) may comprise a Hadamard transform of said received signal.

(69) A module 210′B of the small block code decoder 210′ is configured to determine, in step 305, a maximum magnitude θ.sub.max value from said likelihood calculation of possible transmitted codewords.

(70) A UCI-bits module 210′C of the small block code decoder 210′ is configured to generate, in a known manner in step 310, UCI bits according to the index and sign of the maximum magnitude θ.sub.max value.

(71) A first embodiment of the method of the invention illustrated by FIG. 10 includes, in step 315, the step of comparing said θ.sub.max value to a selected, calculated or predetermined scaled threshold S.sub.HAD.Math.τ. The scaling factor S.sub.HAD may be obtained by a DTX detector for UCI module 210′D by estimating the scaling factor S.sub.HAD from the multi-dimensional DFT (θ.sub.1 . . . θi . . . θ.sub.N) but is preferably obtained by obtaining an estimate of the noise variance after the DFT transform step.

(72) The threshold τ is preferably determined in the manner described with respect to FIG. 7.

(73) The small block code decoder 210′ is configured, in step 315, to determine whether or not the signal received on the UL at said UCI receiver device 100′/200′ comprises a linear block encoded signal when |θ.sub.max|.sup.2>S.sub.HAD.Math.τ. However, where |θ.sub.max|.sup.2≤S.sub.HAD.Math.τ, a discontinuous transmission (DTX) signal is outputted at step 315.

(74) Referring to FIG. 11, provided is a block diagram illustrating a second combined scaling factor S.sub.COMB determination method and utilization of the combined scaling factor S.sub.COMB determined thereby in determining a DTX state in accordance with yet another aspect of the present invention. The scaling factor S.sub.COMB is determined, calculated or derived from a combination of the improved scaling factor S.sub.RE and the scaling factor S.sub.HAD of FIG. 10. The scaling factor S.sub.COMB=f(S.sub.HAD,S.sub.RE)=α(S.sub.HAD).sup.λ.Math.(S.sub.RE).sup.1-λ, where, as before, λ comprises a weighting value less than 1 and α comprises a combination coefficient. The scaling factor S.sub.COMB is therefore derived from a function of the improved scaling factor S.sub.RE and the scaling factor S.sub.HAD. The combination coefficient α may be derived from a payload bit length. In some embodiments, the combination coefficient α is equal to 1. The weighting value λ may be greater than 0.5, but is preferably equal to 0.667, but may take other values as hereinbefore described.

(75) Consequently, in this aspect of the invention, the method comprises determining that the signal received on the UL at said UCI receiver device 100/200, 100′/200′ comprises a linear block encoded signal when where |θ.sub.max|.sup.2>S.sub.COMB.Math.τ and conversely, where |θ.sub.max|.sup.2≤S.sub.COMB.Math.τ, the method comprises determining that the signal received on the UL at said UCI receiver device 100/200, 100′/200′ comprises a DTX state.

(76) FIG. 12 illustrates a further aspect of the invention where the scaling factor S may be selected from a number of scaling factor options. The method includes selecting as the scaling factor S one of (i) S.sub.RE, (ii) S.sub.HAD, or (iii) S.sub.COMB. The selection of which scaling factor option to choose may be based on one or more signal conditions or other factors. For example, it is found that S.sub.HAD can lead to over-estimation of noise variance at one end of the variance scale fundamentally due to the fact that the S.sub.HAD and the |θ.sub.max|.sup.2 both are obtained according to the same realizations of (θ.sub.1 . . . θi . . . θ.sub.N), and their monotonicity has a close and positive relationship. Consequently, under certain conditions it is better to use S.sub.RE than S.sub.HAD and vice-versa and, in yet other conditions, it is better to combine S.sub.RE than S.sub.HAD to provide S.sub.COMB. It is noted, however, that S.sub.RE can lead to under-estimation of noise variance, especially for the case where the framework of used noise estimation method is based on subtracting the estimated signal portion (derived using the estimated channel) from the overall received signal. Moreover, the degree of under-estimation by S.sub.RE may be more significant than the degree of over-estimation caused by S.sub.HAD. Consequently, it is preferred that the weighting value λ is greater than 0.5 and is preferably as high as 0.667. Simulated results show that a value of λ=⅔ (0.667) achieves near to 1% false alarm rate (FAR) which is desirable.

(77) It has been found that using option (i) S.sub.RE provides excellent results when there is a good noise estimator at the RE demapper output, where the noise estimation takes into consideration the channel/signal characteristics other than PUCCH such that the under-estimation effect will be weaker than other cases. This is the preferred option. However, if the noise estimation is poor and the number UCI payload bits is large. e.g., more than 6, then option (iii) S.sub.COMB is preferred because, when the number UCI payload bits is above 6, the 3GPP standard 38.212 requires a code mask operation to be implemented where the influence of over-estimation by S.sub.HAD is increased. In the event that neither of options (i) or (iii) are selected, i.e., deemed suitable, then option (ii) S.sub.HAD is selected as the ‘baseline’ option.

(78) It can be seen therefore that the methods of the foregoing aspects and embodiments of the invention can be most usefully, although not exclusively, utilized in a small block code-based receiver not having CRC functionality such as that exemplified by FIG. 4 to determine if a signal received on the UL at the UCI receiver device 100/200, 100′/200′ comprises a linear block encoded signal and furthermore to detect or determine if the received signal, whether real or comprising noise, includes an ACK message from the UE 125, 125′ or a NACK message from the UE 125, 125′. In other words, not only can the method of the above embodiments determine if the received signal comprises a linear block encoded signal but it also enables the improved decoder 210, 210′ to distinguish between a DTX state on the one hand and ACK/NACK signals on the other hand. Consequently, the method of the above embodiments is particularly useful in wireless communication systems for DTX detection in small block code-based receivers where cyclic redundancy check CRC is not available for DTX detection.

(79) The methods can therefore be utilized to determine that the signal received on the UL at the UCI receiver device 100/200, 100′/200′ comprises a small block encoded signal in a long-term evolution (LTE) communication system and, more particularly, to determine DTX in a small block encoded signal comprising a NR (5G) Physical Uplink Control Channel (PUCCH) format such as PUCCH format 2, PUCCH format 3, or PUCCH format 4.

(80) It will be understood that the linear block code may be Reed-Muller (RM) code or RM-based super code.

(81) Outputting a DTX state may comprise outputting a Boolean or binary value indicative of said DTX state.

(82) In general, signal power varies over time. In a case of DTX, for example, where the received signal only comprises noise, the noise power is not constant over time. Therefore, it is necessary to estimate the noise power (e.g., based on all of (θ.sub.1 . . . θi . . . θ.sub.N)), at one or more points in time. Otherwise, the maximum magnitude θ.sub.max value derived from the received signal comprising only noise may still be such that the maximum magnitude θ.sub.max value is greater than the threshold τ, due to the fact that (θ.sub.1 . . . θi . . . θ.sub.N) are all/mostly large on the whole, rather than due to the fact that θ.sub.max is really outstanding among (θ.sub.1 . . . θi . . . θ.sub.N). Using a scaling factor S with the threshold τ helps to address this problem.

(83) In other embodiments, it is possible that the scaling factor S can be omitted in, for example, the case where we have a priori knowledge of the noise power over a long period of time. In this case, it is possible to determine that noise on the UL channel does not vary rapidly over time or to determine that it follows a certain distribution. In this way, it is possible to treat the noise power as a constant or at least a known entity. Consequently, as long as a suitable level for the threshold τ is chosen, it may no longer become necessary to apply a scaling factor to the threshold τ.

(84) The invention also provides a non-transitory computer-readable medium 140 storing machine-readable instructions, wherein, when the machine-readable instructions are executed by a processor 150, they configure the processor 150 to implement the afore-described methods in accordance with the invention.

(85) The apparatus described above may be implemented at least in part in software. Those skilled in the art will appreciate that the apparatus described above may be implemented at least in part using general purpose computer equipment or using bespoke equipment.

(86) Here, aspects of the methods and apparatuses described herein can be executed on any apparatus comprising the communication system. Program aspects of the technology can be thought of as “products” or “articles of manufacture” typically in the form of executable code and/or associated data that is carried on or embodied in a type of machine-readable medium. “Storage” type media include any or all of the memory of the mobile stations, computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives, and the like, which may provide storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunications networks. Such communications, for example, may enable loading of the software from one computer or processor into another computer or processor. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to tangible non-transitory “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution.

(87) While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.

(88) In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e., to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

(89) It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art.