Transmitter using PSCM scheme and transmission method
阅读说明：本技术 使用pscm方案的发射机及传输方法 (Transmitter using PSCM scheme and transmission method ) 是由 欧纽尔凯·伊斯坎 许文 于 2019-01-31 设计创作，主要内容包括：本发明涉及一种用于经由通信信道与接收机进行通信的发射机(300)。该发射机(300)用于：使用概率整形方案将数据字预编码为预编码数据字,其中,该概率整形方案取决于一个或多个预编码参数(s1；s2)；使用调制和/或编码方案将预编码数据字编码为码字,其中,该调制和/或编码方案取决于一个或多个调制和编码参数(M)；以及,基于一个或多个调制和编码参数(M)中的至少一个,和/或基于至少一个其他预编码参数(s2),确定至少一个预编码参数(s1)。此外,本发明涉及一种相应的传输方法。(The invention relates to a transmitter (300) for communicating with a receiver via a communication channel. The transmitter (300) is configured to: precoding the data words into precoded data words using a probability shaping scheme, wherein the probability shaping scheme depends on one or more precoding parameters (s 1; s 2); encoding the precoded data words into codewords using a modulation and/or coding scheme, wherein the modulation and/or coding scheme depends on one or more modulation and coding parameters (M); and determining at least one precoding parameter (s1) based on at least one of the one or more modulation and coding parameters (M), and/or based on at least one other precoding parameter (s 2). The invention further relates to a corresponding transmission method.)
1. A transmitter (300) for communicating with a receiver via a communication channel, the transmitter (300) being configured to:
precoding the data words into precoded data words using a probability shaping scheme, wherein the probability shaping scheme depends on one or more precoding parameters (s 1; s 2);
encoding the precoded data words into codewords using a modulation and/or coding scheme, wherein the modulation and/or coding scheme depends on one or more modulation and coding parameters (M); and
determining at least one precoding parameter (s1) based on at least one of the one or more modulation and coding parameters (M), and/or based on at least one other precoding parameter (s 2).
2. The transmitter (300) of claim 1, wherein the transmitter (300) is further configured to provide at least one of the one or more modulation and coding parameters (M) and/or the at least one further precoding parameter (s2) to the receiver.
3. The transmitter (300) of claim 1 or 2, wherein the at least one precoding parameter (s1, s2) is a parameter specific to a precoder (301) implementing the precoding, in particular an identifier of a specific precoder type, and/or a parameter of a specific precoder type.
4. The transmitter (300) of any of the preceding claims, wherein the one or more modulation and coding parameters (M) comprise a codeword length, a message length, a modulation order, a code rate, a constellation and/or a modulation and coding scheme index.
5. The transmitter (300) of any of the preceding claims, configured to determine the at least one precoding parameter by using a look-up table, an analytical function and/or a characteristic curve.
6. The transmitter (300) of any of the preceding claims, wherein the encoding is based on a polar code.
7. The transmitter (300) of any of the preceding claims, wherein the precoding and/or the precoder (301) is based on a channel decoder, in particular for a polarization code.
8. The transmitter (300) of claim 7, wherein the channel decoder is a successive cancellation, SC list, SCL, belief propagation, BP, flip, stack, or non-binary decoder.
9. The transmitter (300) of claim 8, wherein the at least one precoding parameter (s1, s2) is a parameter specific to the channel decoder, in particular a list size, a frozen bit sequence, a frozen set of subchannel indices, a number of iterations, and/or a size of a galois field.
10. The transmitter (300) of any of claims 6-9, wherein the precoded data word comprises the data word.
11. The transmitter (300) of any of claims 6 to 10, wherein the precoded data word comprises at least one shaping bit, wherein the transmitter (300) is configured to determine the number of shaping bits based on at least one of the modulation and coding parameters (M) and/or based on the at least one other precoding parameter (s 2).
12. The transmitter (300) according to claim 10 or 11, further configured to determine bit probabilities of bits in the codeword, in particular for a predefined subset of the bits in the codeword.
13. The transmitter (300) of claim 12, wherein the transmitter (300) is configured to provide the bit probabilities to the receiver.
14. The transmitter (300) of claim 12 or 13, configured to determine the bit probabilities based on the number of shaped bits and based on the one or more modulation and coding parameters (M).
15. The transmitter (300) of claim 12 or 13, wherein the transmitter (300) is configured to determine the bit probability based on at least one of the modulation and coding parameters (M) and/or based on the at least one further precoding parameter (s 2).
16. The transmitter (300) of any of claims 10-15, configured to determine the number of shaping bits by selecting the number of shaping bits from a predefined set of possible numbers of shaping bits.
17. The transmitter (300) of any of the preceding claims 1 to 10, wherein the transmitter (300) is further configured to activate and/or deactivate the precoding, in particular to inform the receiver whether the codeword has been generated if the precoding is active or deactivated, and/or wherein the transmitter (300) is configured to provide an indication whether a shaping bit is present in data provided to the receiver.
18. A transmission method (500) for communicating via a communication channel, the transmission method (500) comprising:
determining (501) at least one precoding parameter (s1) based on the at least one modulation and coding parameter (M) and/or based on at least one other precoding parameter (s 2);
precoding (503) the data words into precoded data words using a probability shaping scheme, wherein the probability shaping scheme depends on the one or more precoding parameters (s 1; s 2); and
encoding (505) the pre-encoded data words into code words using a modulation and/or coding scheme, wherein the modulation and/or coding scheme depends on one or more modulation and coding parameters (M).
19. A computer program product comprising program code for performing the method (500) according to claim 18 when executed on a computer or processor.
Technical Field
The present invention relates generally to communication systems. In particular, the present invention relates to a transmitter and a transmission method using a Probability Shaped Coded Modulation (PSCM) scheme.
Background
According to shannon's theorem, the capacity of a transmission channel can only be achieved when channel input symbols, such as Quadrature Amplitude Modulation (QAM) symbols, Amplitude Shift Keying (ASK) symbols, etc., generated by a transmitter and fed into the channel are distributed according to a capacity that achieves an (optimal) probability distribution. The distribution depends on the channel, i.e. on the channel characteristics, so that the optimal distribution is different. For example, a gaussian distribution is optimal for AWGN channels. This means that to approach this capacity, the channel input symbols need to be distributed according to a gaussian distribution.
Many conventional communication systems do not take into account optimal symbol distribution. For example, conventional mobile communication systems (such as 3G, 4G) employ bit-interleaved coded modulation (BICM) with uniformly distributed symbols. The reason for this choice is its simplicity: without special measures, the transmitter would typically generate symbols selected from the set with the same probability, i.e., each channel input symbol would be transmitted with the same probability. This leads to so-called "shaping losses" since no optimal distribution is used. On AWGN channels, the shaping loss can be as high as 1.53dB, i.e., 1.53dB more power than theoretically needed is needed to reliably transmit the symbols.
There are several different schemes to avoid or reduce the shaping loss. One promising scheme is PSCM, where the transmitter chain is modified in such a way that the codewords generated before the symbol mapper have a desired (non-uniform) probability distribution. In this way, the symbols generated after symbol mapping have an optimal (or near optimal) probability distribution. One way in which this result may be obtained is to use a shaping encoder 101 prior to the channel encoder 101, such as the conventional transmitter 100 shown in fig. 1, which conventional transmitter 100 also typically includes a symbol mapper 105. It will be appreciated that in a communication system without probability shaping, the shaping encoder is not used, but rather the data is fed directly to the channel encoder. The task of the shaping encoder 101 is to introduce additional redundancy (shaping redundancy) that can bring the codeword (and channel input symbols) to a target probability distribution.
Onurcan、RonaldAnd Wen Xu in "Shaped Polar Codes for high Order Modulation" (IEEE Communications Letters) 22.2 (2018): 252-255 propose a PSCM scheme based on polar coding (referred to as "shaped polar code"). In this approach, the precoder 201 acts as a shaping encoder before the channel encoder 203, which generates and appends "shaping bits" s to its input (data bits d), which are then fed into the channel encoder 203 of the transmitter 200 as shown in fig. 2. The task of shaping the bits is to obtain a binary codeword c at the output of the channel encoder 203, where some parts of the codeword c contain bits with a non-uniform probability distribution, i.e. the probability that some bits (at predetermined positions in the codeword) are 1 is p, where p is a real number between 0 and 1 and is not equal to 0.5, i.e. the bit distribution is non-uniform. After the codewords are mapped to channel input symbols, such as by a symbol mapper not shown in fig. 2, the symbol distribution is made non-uniform.
The polar code based channel encoder may comprise a polarity inversion, one or more interleavers, a bit selector and/or a (binary) jammer.
For shaped-polarity coding, two parameters are particularly important, namely (i) the bit probability p and (ii) the number of shaping bits s, i.e. the length of the string of shaping bits s. These two parameters are correlated with each other and the resulting bit probability p is obtained for a given number of shaping bits s. However, this relationship is not direct, but depends on different factors.
It is noted that selecting different shaping bits s (of the same length) results in different codewords c, but which represent the same data bits, i.e. there are a number of possibilities to generate s. The optimal precoder will generate shaping bits in a way to obtain the target p as accurately as possible. On the other hand, choosing different s may yield similar performance in terms of p's precision. The way s is generated depends on the configuration and implementation of the precoder, i.e. there is no single choice of shaping bits s that meets the requirements. Thus, it may be advantageous to find a near-optimal solution, rather than finding an optimal choice of optimal precoders (which may be too complex to implement), because the precoders are simple to implement.
As described above, fromOnurcan、RonaldAnd Wen Xu in "shaped polarity codes for high order modulation," IEEE letters, 22.2 (2018): 252-255 it can be seen that a "polar decoder" can be used as a precoder. It is noted that polar decoding is typically an operation at the receiver end and is therefore placed in the receiver chain of the communication system. However, many communication systems are bi-directional, i.e., the node includes both a transmitter chain and a receiver chain. The implementation of the decoder is typically vendor specific and therefore likely unspecified in any (standard) technical document. There are several different types of decoders, where all decoders have their own (implementation-specific) parameters.
In modern communication systems, the parameter selection process is mainly described in standard documents. For example, parameter selection for rate adaptive transmission in LTE is defined by a large table, where relevant parameters are obtained according to Modulation and Coding Scheme (MCS), Transport Block Size (TBS), number of physical resource blocks, and the like. PSCM has not been included in any standard for wireless communications. Therefore, in the prior art specification, there is no systematic way to obtain PSCM related parameters. There are some academic works that study probabilistic shaping, but these works do not consider systematic methods of obtaining the required parameters, nor the alignment between transmitter and receiver (i.e., how the signaling of shaping-related parameters should be performed).
In view of the above, there is a need for an improved transmitter and a corresponding improved transmission method, which enable parameter selection and signaling of signal shaping related parameters, making them easy to calculate and suitable for signaling of an aligned receiver.
Disclosure of Invention
The present invention aims to provide an improved transmitter and a corresponding improved transmission method, which are capable of performing parameter selection and signaling on signal shaping related parameters, so that the signal shaping related parameters are easy to calculate and suitable for signaling of an alignment receiver.
The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementations are apparent from the dependent claims, the description and the drawings.
According to a first aspect, the invention relates to a transmitter for communicating with a receiver via a communication channel. The transmitter is configured to: precoding the data words into precoded data words using a probability shaping scheme, wherein the probability shaping scheme depends on one or more precoding parameters; encoding the precoded data words into codewords using a modulation and/or coding scheme, wherein the modulation and/or coding scheme depends on one or more modulation and coding parameters; and determining at least one precoding parameter based on at least one modulation and coding parameter, i.e. at least one of the one or more modulation and coding parameters, and/or based on at least one other precoding parameter.
Thus, an improved transmitter using a PSCM scheme is provided that enables parameter selection and signaling of signal shaping related parameters that is easy to calculate and suitable for signaling to an aligned receiver.
In another possible implementation form of the first aspect, the transmitter is further configured to provide the at least one modulation and coding parameter and/or the at least one other precoding parameter to the receiver.
In another possible implementation manner of the first aspect, the at least one precoding parameter is a parameter specific to a precoder implementing the precoding, in particular an identifier of a specific precoder type, and/or a parameter of a specific precoder type.
In another possible implementation form of the first aspect, the one or more modulation and coding parameters include a codeword length, a message length, a modulation order, a code rate, a constellation, and/or a modulation and coding scheme index.
In another possible implementation form of the first aspect, the transmitter is configured to determine the at least one precoding parameter by using a look-up table, an analytic function and/or a characteristic curve.
In another possible implementation form of the first aspect, the encoding is based on a polar code.
In another possible implementation form of the first aspect, the precoding and/or the precoder is based on a channel decoder, in particular a channel decoder for polarization codes. The receiver can decode data received from the transmitter using the same channel decoder (type). Advantageously, the transmitter may have a simplified structure since the channel decoder may be used in both the receiver chain and the transmitter chain.
In another possible implementation manner of the first aspect, the channel decoder is a Successive Cancellation (SC) decoder, an SC List (SCL) decoder, a Belief Propagation (BP) decoder, a flip-flop decoder, a stack decoder, or a non-binary decoder.
In another possible implementation form of the first aspect, the at least one precoding parameter is a parameter specific to the channel decoder, in particular a list size, a frozen bit sequence, a frozen set of subchannel indices, a number of iterations, and/or a size of a galois field.
In another possible implementation form of the first aspect, the precoded data word comprises the data word.
In another possible implementation form of the first aspect, the precoded data word comprises at least one shaping bit, wherein the transmitter is configured to determine the number of shaping bits based on at least one of the modulation and coding parameters and/or based on the at least one other precoding parameter.
In another possible implementation form of the first aspect, the transmitter is further configured to determine bit probabilities of bits in the codeword, in particular bit probabilities of a predefined subset of the bits in the codeword.
In another possible implementation form of the first aspect, the transmitter is configured to provide the bit probabilities to the receiver.
In another possible implementation form of the first aspect, the transmitter is configured to determine the bit probabilities based on the number of shaped bits and based on the one or more modulation and coding parameters.
In another possible implementation form of the first aspect, the transmitter is configured to determine the bit probability based on at least one of the modulation and coding parameters and/or based on the at least one other precoding parameter.
In another possible implementation form of the first aspect, the transmitter is configured to determine the number of shaped bits by selecting the number of shaped bits from a predefined limited set of possible numbers of shaped bits.
In another possible implementation form of the first aspect, the transmitter is further configured to activate and/or deactivate the precoding, in particular to inform the receiver whether the codeword has been generated in case the precoding is activated or deactivated, and/or wherein the transmitter is configured to provide an indication, e.g. a flag bit, whether a shaping bit is present in data provided to the receiver.
According to a second aspect, the invention relates to a transmission method for communicating via a communication channel. The transmission method comprises the following steps: determining at least one precoding parameter based on the at least one modulation and coding parameter and/or based on at least one other precoding parameter;
precoding the data words into precoded data words using a probability shaping scheme, wherein the probability shaping scheme is dependent on the one or more precoding parameters; and
encoding the pre-encoded data word into a codeword using a modulation and/or coding scheme, wherein the modulation and/or coding scheme is dependent on one or more modulation and coding parameters.
Thus, an improved transmission method using a PSCM scheme is provided, enabling parameter selection and signaling of signal shaping related parameters, making it easy to calculate and suitable for signaling of an aligned receiver.
The transmission method according to the second aspect of the invention may be performed by a transmitter according to the first aspect of the invention. Further features of the transmission method according to the second aspect of the invention may be derived directly from the functionality of the transmitter according to the first aspect of the invention and the different implementations described above and below.
A third aspect of the invention relates to a computer program product for executing the program code of the method according to the second aspect when executed on a computer.
Therefore, the embodiment of the invention can perform parameter selection and parameter signaling related to the forming polarity coding. As mentioned above, the choice of s and p can significantly affect the gain achieved by signal shaping. Thus, embodiments of the invention allow for optimal or near optimal selection of these parameters, however, this may depend on the selection of other parameters.
Furthermore, embodiments of the present invention may enable a receiver to obtain the values of s and p in order to recover the signal shaping operation at the receiver side. Since s is usually an integer, its specific value should be known at the transmitter and receiver. On the other hand, p is a real-valued parameter (0< ═ p < ═ 1), which can also be represented with limited accuracy, and for transmitters and receivers an approximation (or quantized version) of p is usually sufficient. In addition, as previously described, s and p are associated with each other. Thus, if one of the parameters is known, a relationship may be used to obtain the other parameter, which relationship may also depend on the other parameter. For example, as described above, the correlation, i.e., the relationship between s and p, may depend on the implementation of the precoder. For example, if the precoder is implemented by using a polar decoder, the type of decoder and decoder parameters may affect the relationship. Since this relationship can be implemented specifically, this makes the relationship between s and p different from the relationship between any other parameter in the transceiver chain. Embodiments of the present invention take advantage of this relationship to reduce signaling overhead between the transmitter and receiver, since signaling from one parameter is sufficient to obtain the other parameter, which can cause the receiver to resume signal shaping operations.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Drawings
The following embodiments of the invention are described in more detail with reference to the accompanying drawings, in which:
FIG. 1 is a schematic block diagram illustrating an example of a transmitter of a communication system using probability shaping;
FIG. 2 is a schematic block diagram illustrating an example of a transmitter of a communication system using polar-code-based probability shaping;
FIG. 3 is a schematic block diagram illustrating an example of a transmitter using a communication system using probability shaping in accordance with an embodiment of the present invention;
FIG. 4 illustrates an example of an approximate mathematical relationship between parameters implemented in a communication system transmitter in accordance with an embodiment of the present invention; and
fig. 5 is a flowchart illustrating an example of a transmission method according to an embodiment of the present invention.
In the following, the same reference numerals indicate identical or at least functionally equivalent features.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate certain aspects of embodiments of the invention and, together with the description, serve to explain certain aspects that may be used in embodiments of the invention. It should be understood that embodiments of the invention may be used in other respects, and include structural or logical changes not shown in the drawings. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
For example, it is to be understood that the disclosure relating to the method may also apply to a corresponding device or system configured to perform the method, and vice versa. For example, where one or more particular method steps are described, although one or more elements may not be explicitly described or shown in the figures, a corresponding apparatus may include the one or more elements, such as functional elements, to perform the one or more method steps (such as one element performing the one or more steps, or each of the plurality of elements performing one or more of the steps). On the other hand, for example, if a particular apparatus is described based on one or more units (such as functional units), although one or more steps are not explicitly described or shown in the drawings, the corresponding method may include one step to perform the function of one or more units (such as one step to perform the function of one or more units, or each of multiple steps to perform the function of one or more units). Furthermore, it is to be understood that features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.
Fig. 3 shows a block diagram of a transmitter 300 according to an embodiment of the invention. The transmitter 300 shown in fig. 3 comprises a precoder 301, a channel encoder 303 and a configuration unit 302, the transmitter 300 being configured to communicate with a receiver via a communication channel. To this end, the transmitter 300 may include other components not shown in fig. 3, such as an RF antenna, a symbol mapper, and the like.
The precoder 301 of the transmitter 300 is configured to precode the data words d into precoded data words using a probability shaping scheme, wherein the probability shaping scheme depends on one or more precoding parameters s1, s 2.
The channel encoder 303 of the transmitter 300 is arranged to encode the precoded data words into codewords c using a modulation and/or coding scheme, wherein the modulation and/or coding scheme depends on one or more modulation and coding parameters M.
The configuration unit 302 of the transmitter 300 is configured to determine at least one precoding parameter s1 based on at least one modulation and coding parameter, i.e. at least one of the one or more modulation and coding parameters M, and/or based on at least one other precoding parameter s2, as is elaborated below. In an embodiment, the transmitter 300 is further configured to provide the receiver with at least one modulation and coding parameter M, and/or at least one other precoding parameter s 2.
Thus, the configuration unit 302 of the transmitter may generate the required parameters from the existing parameters. Therefore, the configuration unit 302 not only can obtain a systematic way of the required parameters, but is also advantageous for reducing the signaling overhead. If the same configuration unit 302 is used at both the transmitter 300 and the receiver, only a small amount of signaling is sufficient to align the parameters on both sides of the communication system.
In the embodiment shown in fig. 3, the transmitter 300 (and receiver) is part of a Polar coded PSCM system, which may for example rely on the recently developed concept of "Shaped Polar (splar) Coding". As described above, the shaping polarization code combines the PSCM with the polarization code in such a way that the shaping encoder, i.e., the precoder 301 of the transmitter 300, can be implemented by the polar decoder 301. This is particularly advantageous as it eliminates the necessity of additional hardware for the PSCM. Since the polarity decoder 301 is already included in the receiver chain if the communication is bidirectional. Since the polarity decoder 301 can be implemented in different ways and there are different types of polarity decoders, the precoding parameters required for the shaping encoder 301 are "implementation specific". In other words, the input parameters (i.e., the precoding parameters of the shaping encoder 301) may be different while providing the same target output, depending on their implementation. Thus, the output of the configuration unit 302 of the transmitter 300 shown in fig. 3 depends not only on the modulation and coding parameters, but also on the precoding parameters of the particular implementation. According to an embodiment, the channel decoder 301 is a Successive Cancellation (SC) decoder, an SC List (SCL) decoder, a Belief Propagation (BP) decoder, a flip-flop decoder, a stack decoder, or a non-binary decoder.
For the embodiment shown in fig. 3, in which the reshaping encoder, i.e. the precoder 301, is provided by a polar decoder, the precoded data word [ d s ] comprises the data word d, as shown in fig. 3. In this embodiment, the precoded data word comprises at least one shaping bit (s here denoted shaping bit), the configuration unit 302 of the transmitter 300 is operable to determine the number of shaping bits based on at least one of the modulation and coding parameters and/or based on at least one other precoding parameter.
As mentioned above, fig. 3 shows the interaction between the configuration unit 302 and the other components of the transmitter 300. A similar relationship exists for receivers. In the embodiment shown in fig. 3, the task of the configuration unit 302 is to determine a shaping parameter, which, as mentioned above, depends on two different sets of parameters, namely a modulation and coding specific parameter and a precoding specific parameter.
Modulation and coding specific parameters have typically been specified in conventional communication systems. According to an embodiment, the modulation and coding parameters may include a codeword length n, a message length k, a modulation order, a code rate, a constellation and/or a Modulation and Coding Scheme (MCS) index. According to an embodiment, the transmitter 300 is configured to signal one or more modulation and coding parameters to the receiver via a control channel in order to align the operations at the transmitter and receiver sides.
Because of implementation-specific, precoding parameters, such as parameters related to the precoder 301 implementation-specific, are typically not specified. For example, as described above, the precoder 301 may be provided by a polar decoder. In this case, the decoder type (SC, SCL, BP, etc.) and its parameters (such as SCL decoder list size, BP decoder iteration number, etc.) may be considered as precoding parameters. In other words, according to an embodiment, the at least one precoding parameter may be a parameter specific to implementing the precoder 301, in particular an identifier of a specific type of precoder 301 and/or a parameter of a specific type of precoder 301.
As mentioned above, the selection of at least one precoding, i.e. shaping parameter, directly affects the overall performance of the transmitter 300 and the communication system. According to an embodiment, the transmitter 300 is configured to determine at least one precoding parameter by using a look-up table, an analytic function and/or a characteristic curve, as will be described in more detail below. According to an embodiment, the at least one precoding parameter is a specific parameter of the channel decoder, in particular a list size, a frozen bit sequence, a frozen set of subchannel indices, a number of iterations, and/or a size of a galois field.
In the following, an exemplary embodiment of the configuration unit 302 will be described in more detail, wherein the configuration unit 302 is configured to determine the number of shaping bits s based on a predefined target bit probability p and vice versa (and depending on modulation and coding parameters). To obtain an accurate relationship between s and p, according to an embodiment, the configuration unit 302 may be configured to use numerical simulations for different parameter sets. For a large number of parameters, the dependency between the two parameters can be determined and defined in a large look-up table. While this provides a very accurate solution, it requires a large amount of storage and may not be feasible for applications that require flexibility in terms of parameters. However, analytical functions can be derived by using a curve fitting algorithm, which functions can effectively approximate the results of the look-up table. Thus, according to an embodiment, the configuration unit 302 may be configured to determine the number of shaping bits s using the analytic function shown in fig. 4 based on a predefined target bit probability p, and vice versa. In the analytic function shown in FIG. 4, h2(p) — (p log (p) - (1-p) log (1-p)) is a binary entropy function, n denotes the codeword length, and L denotes the list size of the precoder 301, in this case provided by the SCL decoder 301. Thus, n is a modulation and coding specific parameter and L is a precoding specific parameter. In this example, the relationship between s and p depends on two parameters. Allowing the configuration unit 302 to determine the relationship between s and p based on a parsing function, such as the parsing function shown in fig. 4, requires less storage resources than, for example, using a look-up table.
From L, the parameter M can be numerically determinedLAnd/or BL. This may be achieved by performing simulation and/or curve fitting methods. For example, for different choices of s, it is possible to operate the Monte cardThe simulation evaluates the result p, which is then used as input to a curve fitting algorithm, for example to obtain curve parameters such as coefficients of a polynomial and/or any other analytical function. Other parameters may be further considered to extend the method.
According to an embodiment, the configuration unit 302 may further be configured to determine an optimal value of at least one precoding parameter, such as a number of shaping bits s and/or a bit probability p. It should be appreciated, however, that in the above-described embodiment, the configuration unit 302 is configured to determine the number of shaping bits s based on a predefined target bit probability p, and vice versa, sufficient to determine an optimal value for at least one of these precoding parameters. Furthermore, the specific parameters (n, codeword length), (k, message length), (m, modulation order) and the precoding specific parameters (L, list of SCL decoders) are modulated and encoded by numerical simulation
Size) may be determined and implemented in the configuration unit 302. Most preferred of the parameter s
The selection will result in optimal overall system performance. However, after analyzing all the obtained optima, the optimum s and
some relationships between other parameters. For example, the optimal value of s and the ratio s/(nk) are almost constant for a large number of parameters, wherein the constant value may depend on a particular implementation parameter, such as the list size L.
Therefore, the configuration unit 302 can obtain the precoding parameters p and s in an efficient manner. All parameters should be known to both the transmitter 300 and the receiver for alignment between the transmitter 300 and the receiver. By placing the configuration unit 302 at both the transmitter 300 and the receiver, the signaling overhead can be reduced. Since the configuration unit 302 already contains the relation between these parameters, it is not necessary to signal all parameters to the receiver.
In the following, further embodiments of the transmitter 300 will be described, which embodiments support different signaling procedures between the transmitter 300 and the receiver.
According to an embodiment, the transmitter 300 is configured to select, i.e. determine the number of shaping bits s using a configuration unit 302 at the transmitter 300 and send s to the receiver via a control channel. According to an embodiment, the transmitter 300 also uses the configuration unit 302 to obtain p, and also sends the value of p (or a quantized version thereof) to the receiver via the control channel. If p is not signaled by the transmitter 300, the receiver can obtain p from s by using a configuration unit at the receiver. According to an alternative embodiment, if the transmitter 300 does not signal p, the receiver blindly acquires p (in this case, there is no need to set a configuration unit at the receiver). In general, blind detection (such as of p) may be performed, such as by attempting to decode using a predefined set of precoder parameters. Among the precoder parameter sets, the most likely set in the sense of maximum likelihood decoding, or the set that results in the smallest decoding error (in terms of minimum error decoding), may be considered as the desired precoder parameter set.
According to an embodiment, the transmitter 300 is configured to select, i.e. determine s, based on modulation and coding specific parameters only, by using a configuration unit 302 (assuming that the precoding parameters are fixed). According to an embodiment, the transmitter 300 also uses the configuration unit 302 to obtain p, and also sends the value of p (or a quantized version thereof) to the receiver via the control channel. If p is not signaled by the transmitter 300, the receiver can obtain p from s by using a configuration unit at the receiver. According to an alternative embodiment, if the transmitter 300 does not signal p, the receiver blindly acquires p (in this case, there is no need to set a configuration unit at the receiver).
According to an embodiment, the transmitter 300 is configured to select from a set of finite bases, i.e., determine s. For example, configuration unit 302 may be used to support a limited number of different choices of s, or a function of s, such as s/n or s/(n-k). This is advantageous as it reduces the signalling overhead. For example, if only 32 combinations are supported, 5 bits are sufficient for signaling.
According to an embodiment, the configuration unit 302 is adapted to set, i.e. determine, s such that the existing parameters at the receiver (the parameters already signaled) are sufficient to obtain s without signaling its actual value. In this case, 1-bit signaling is sufficient (shaping on/off signaling).
Fig. 5 is a flow chart illustrating an example of a corresponding transmission method 500 according to an embodiment of the present invention. The method 500 includes the following steps: determining 501 at least one precoding parameter s1 based on the at least one modulation and coding parameter M and/or based on at least one other precoding parameter s 2; precoding 503 the data words into precoded data words using a probability shaping scheme, wherein the probability shaping scheme depends on one or more precoding parameters s1, s 2; the pre-coded data words are encoded 505 into code words using a modulation and/or coding scheme, wherein the modulation and/or coding scheme depends on one or more modulation and coding parameters M.
Those skilled in the art will appreciate that the various figures (methods and apparatus) represent or describe the functions of embodiments of the invention (rather than merely individual "units" of hardware or software), and thus likewise describe apparatus embodiments as well as functions or features of method embodiments (such as steps).
In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative. For example, a cell partition is only one logical functional partition, and may be other partitions in an actual implementation. For example, multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented. Furthermore, the shown or discussed couplings or direct couplings or communicative connections to each other may be realized by using some interfaces. An indirect coupling or communicative connection between devices or units may be implemented electrically, mechanically, or otherwise.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in various embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.