阅读说明：本技术 数据符号至芯片映射的方法和设备 (Method and apparatus for data symbol to chip mapping ) 是由 苏吉特·卓斯 钱德拉西卡·德贾斯威·皮斯 金然·拜纳姆 洪永骏 朴昌淳 曼奥吉·乔德哈瑞 于 2014-10-21 设计创作，主要内容包括：公开了一种数据符号至芯片映射的方法和设备。所述方法包括如下步骤：基于输入比特,产生数据符号；以及将数据符号映射至三进制序列的集合,其中,映射通过k/L-三进制幅移键控(TASK)调制格式所确定,其中,k表示数据符号中的每个的大小,L表示三进制序列中的每个的长度。(A method and apparatus for data symbol to chip mapping is disclosed. The method comprises the following steps: generating data symbols based on the input bits; and mapping the data symbols to a set of ternary sequences, wherein the mapping is determined by a k/L-Ternary Amplitude Shift Keying (TASK) modulation format, wherein k denotes a size of each of the data symbols and L denotes a length of each of the ternary sequences.)

1. A method of data symbol to chip mapping, comprising the steps of:

generating data symbols based on the input bits; and

the data symbols are mapped to a set of ternary sequences,

wherein the mapping is determined by a k/L-Ternary Amplitude Shift Keying (TASK) modulation format,

where k denotes the size of each of the data symbols and L denotes the length of each of the ternary sequences.

2. The method of claim 1, wherein the set of ternary sequences comprises: ternary sequence c₀And ternary sequence c_mWherein c is_mIs from c₀A cycle of shift m positions, m being a positive integer.

3. The method of claim 2, wherein m is an integer no greater than L.

4. The method of claim 2, wherein c_mIs from c₀A cycle of m positions to the right.

5. The method of claim 4, wherein c is applied 3/8-TASK₀Is { 0001-,

wherein, in case of 5/32-TASK being applied, c₀Is { -100101-10-1-11-1010100010010011-.

6. A method according to claim 3, wherein, in the case where 3/8-TASK is applied, the number of data symbols is 8,

wherein 8 data symbols are mapped to a length-8 ternary sequence.

7. The method of claim 2, wherein the number of data symbols is 8 in case 3/8-TASK is applied, obtaining c corresponding to data symbol "0₀，c₀Is { 0001- }.

8. The method of claim 1, wherein, in the case of 5/32-TASK, the number of data symbols is 32,

wherein 32 data symbols are mapped to a length-32 ternary sequence.

9. The method of claim 1, wherein each of the ternary sequences is 2 in length^k。

10. An apparatus for performing data symbol to chip mapping, the apparatus comprising:

a processor configured to: generating data symbols based on the input bits, and mapping the data symbols to a set of ternary sequences,

wherein the mapping is determined by a k/L-Ternary Amplitude Shift Keying (TASK) modulation format,

where k denotes the size of each of the data symbols and L denotes the length of each of the ternary sequences.

11. The apparatus of claim 10, wherein the set of ternary sequences comprises: ternary sequence c₀And ternary sequence c_mWherein c is_mIs from c₀A cycle of shift m positions, m being a positive integer.

12. The apparatus of claim 11, wherein m is an integer no greater than L.

13. The apparatus of claim 11, wherein c_mIs from c₀A cycle of m positions to the right.

14. The apparatus of claim 13, wherein c is when 3/8-TASK modulation format is used₀Is { 0001-,

wherein, in the case of using 5/32-TASK modulation format, c₀Is { -100101-10-1-11-1010100010010011-.

15. The apparatus of claim 10, wherein, in case 3/8-TASK is used, the number of data symbols is 8,

wherein 8 data symbols are mapped to a length-8 ternary sequence.

16. The apparatus as claimed in claim 11, wherein the number of data symbols is 8 in case of using 3/8-TASK modulation format, and c corresponding to data symbol "0" is obtained₀，c₀Is { 0001- }.

17. The apparatus of claim 10, wherein, in case that 5/32-TASK modulation format is applied, the number of data symbols is 32,

wherein 32 data symbols are mapped to a length-32 ternary sequence.

18. The apparatus of claim 10, wherein each of the ternary sequences is 2 in length^k。

Technical Field

The present invention relates to communication systems, and more particularly, to methods and systems for coherent and non-coherent data transmission.

Background

Low power wireless networks, such as sensor networks, PANs (personal access networks), BANs (body area networks), etc., have received increasing interest in industrial automation, personalized entertainment and personal healthcare. Typically, the devices in these networks are small in size and need to conserve their battery life. Thus, although these devices have a relatively low symbol rate, it is desirable that these devices operate at low power. The selection of efficient transmit and receive protocols that trade off energy versus symbol rate becomes an important aspect in the design of low power wireless networks.

The form of the signal processing algorithm used at the receiver is crucial to the design of the power-saving transmission protocol. It is well known that receivers are broadly divided into coherent and non-coherent receivers. Coherent receivers utilize phase information in the demodulation of symbols (symbols), whereas non-coherent receivers are based primarily on envelope detection without phase information. Generally, coherent receivers achieve better performance than non-coherent receivers in terms of power cost and complexity. Coherent communication supports a bipolar modulation alphabet (alphabets) due to the ability to utilize phase information, while non-coherent communication supports a unipolar alphabet. Therefore, in general, communication networks are designed to exclusively support coherent receivers or non-coherent receivers. However, many communication networks that include low power constraints may need to support both coherent and non-coherent reception. This stems from the fact that some receivers use non-coherent reception due to system processing and power constraints. Therefore, in such networks, the transmission scheme needs to be designed to ensure suitability for both types of receivers. Furthermore, in many cases, due to practical concerns, the design task is made more challenging given that the sender does not know the type of target receiver.

Disclosure of Invention

Solution of the problem

The object of the invention is to transmit data in low power devices.

Yet another object of the present invention is to simultaneously transmit data to both coherent and non-coherent receivers.

Embodiments of the present invention describe a method of transmitting data. The method comprises the following steps: retrieving a base ternary sequence having a predefined length; acquiring one or more ternary sequences corresponding to data to be transmitted from the base ternary sequence; the acquired ternary sequence is transmitted by the transmitter. According to one embodiment of the present invention, the step of acquiring one or more ternary sequences corresponding to data to be transmitted from the base ternary sequence includes: dividing data to be transmitted into one or more symbols having a predefined length; mapping one or more symbols in binary form to one or more ternary sequences obtained as one or more cyclic shifts of a base ternary sequence, wherein the number of cyclic shifts is determined based on a one-to-one mapping from symbols to ternary sequences obtained as the cyclic shifts.

One aspect of the invention discloses the generation of a base ternary sequence having a predefined length. The method for generating the base ternary sequence comprises the following steps: selecting a seed sequence of a predefined length, wherein the seed sequence is one of an m-sequence and a complement of the m-sequence; generating a perfect ternary sequence from the seed sequence if the weight of the seed sequence is a perfect square, wherein the weight of the sequence is the number of non-zero elements in the sequence; generating a near-perfect ternary sequence from the seed sequence if the weight of the seed sequence is different from the perfect square number; a predefined binary value is inserted into a predefined position of the perfect ternary sequence or close to the perfect ternary sequence for generating a base ternary sequence.

Another aspect of the invention discloses a method of receiving data transmitted from one or more transmitters. According to one embodiment of the invention, the method comprises: receiving, by a receiver from the one or more transmitters, one or more data symbols transmitted as one or more ternary sequences; demodulating the ternary sequence by correlating the received signal with all cyclic shifts of the base ternary sequence, provided that the receiver is a coherent receiver; in case the receiver is a non-coherent receiver, demodulating by correlating the received signal with all cyclic shifts of the absolute value of the base ternary sequence; each data symbol transmitted is detected based on a cyclic shift corresponding to the maximum correlation. In this regard, the cyclic shift of the base ternary sequence is a ternary sequence obtained by cyclically shifting the base ternary sequence to the left or right. For example, if x is a base ternary sequence of length N, its elements are given as x₀，x₁，……，x_N. Then the cyclic shift of two bits of the base ternary sequence is x₂……x_N，x₀，x₁Or x_N-1，x_N，……，x₀，x₁. There are N different cyclic shifts of the base ternary sequence and the above cyclic shifts of the base ternary sequence can be obtained by cyclically shifting in either direction, as long as the direction of each cyclic shift remains unchanged.

Another aspect of the invention discloses a transmitter. The transmitter includes: a data input module; a sending module; a symbol generation module, in combination with the data input module, adapted to generate one or more data symbols based on the input data; a ternary sequence generation module combined with the symbol generation module; a base ternary sequence retrieval module; and a cyclic shift generation module. The base ternary sequence retrieval module retrieves a base ternary sequence. Likewise, the cyclic shift generation module is adapted to generate a cyclic shift of the base ternary sequence based on the generated data symbols.

In addition, the invention discloses a basic ternary sequence generation module. The base ternary sequence generation module comprises: a seed sequence selection module; a perfect ternary sequence generation module; a near perfect ternary sequence generating module; and a predefined value insertion module. The seed sequence selection module is adapted to select a seed sequence as an m-sequence or a complement of an m-sequence. If the length of the base ternary sequence is N, the weight of the seed sequence is N/2 if the seed sequence selected is an m-sequence. Likewise, if the selected seed sequence is the complement of the m-sequence, the weight of the seed sequence is equal to (N-2)/2.

Furthermore, the invention discloses a receiver. A receiver according to one embodiment of the present invention includes: a signal receiving module; the demodulation module is combined with the ternary sequence input module and the signal receiving module; and a symbol detection module. If the receiver is a coherent receiver, the ternary sequence input module retrieves all N cyclic shifts of the base ternary sequence. If the receiver is a non-coherent receiver, the ternary sequence input module retrieves all N cyclic shifts of the absolute value of the base ternary sequence. In this regard, N is the length of the base ternary sequence and will be referred to in many places herein. The signal receiving module is adapted to receive a signal transmitted from a transmitter.

The demodulation module demodulates the received signal by correlating the received signal with the sequence from the ternary sequence input module.

The symbol detection module is adapted to detect each data symbol transmitted by identifying a cyclic shift of the base ternary sequence corresponding to a maximum correlation value among all N correlation values obtained by the demodulation module corresponding to the N sequences from the ternary sequence input module and then mapping the identified cyclic shift to the data symbol using an inverse of the one-to-one mapping used at the transmitter.

In addition, the invention discloses a method for mapping data symbols to chips, which comprises the following steps: generating data symbols based on the input bits; and mapping the data symbols to a set of ternary sequences, wherein the mapping is determined by a k/L-Ternary Amplitude Shift Keying (TASK) modulation format, wherein k denotes a size of each of the data symbols and L denotes a length of each of the ternary sequences.

In addition, the present invention also discloses an apparatus for performing mapping of data symbols to chips, the apparatus comprising: a processor configured to: based on the input bits, data symbols are generated and mapped to a set of ternary sequences, wherein the mapping is determined by a k/L-Ternary Amplitude Shift Keying (TASK) modulation format, wherein k denotes a size of each of the data symbols and L denotes a length of each of the ternary sequences.

Drawings

The above aspects and other features of the present invention will be explained by the following description in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram of an exemplary communication system in accordance with one embodiment of the present invention;

FIG. 2 is a block diagram depicting data processing operations in an exemplary communication system, in accordance with one embodiment of the present invention;

FIG. 3 is a flow diagram illustrating a method of transmitting data according to one embodiment of the invention;

fig. 4 is a flowchart illustrating a method of acquiring one or more ternary sequences (ternary sequences) corresponding to data to be transmitted;

fig. 5 is a flow diagram illustrating a method of generating a base ternary sequence (base ternary sequence), according to one embodiment of the present invention;

FIG. 6 is a flow diagram illustrating a method of generating a perfect (best) ternary sequence from a seed sequence, according to one embodiment of the present invention;

FIG. 7 is a flow diagram illustrating a method of generating a near perfect ternary sequence, according to one embodiment of the present invention;

FIG. 8 is a block diagram of a transmitter in accordance with one embodiment of the present invention;

FIG. 9 is a block diagram of a base ternary sequence generation module according to one embodiment of the present invention;

FIG. 10 is a block diagram of a receiver according to one embodiment of the invention;

FIG. 11 is a block diagram illustrating an exemplary communications device for implementing various components of an embodiment of the invention.

Detailed Description

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these examples. The present invention may be modified in various forms. Accordingly, the embodiments of the present invention are provided only to explain the present invention more clearly to those skilled in the art of the present invention. In the drawings, like reference numerals are used to designate like components.

This specification may refer to "an" or "some" embodiment in various places. This does not necessarily mean that each such embodiment is the same embodiment or that the described features only apply to a single embodiment. Individual features of different embodiments may also be combined to provide further embodiments.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms "comprises," "comprising," "… …," "includes" and/or "including … …," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Fig. 1 is a block diagram of an exemplary communication system in accordance with one embodiment of the present invention. According to one embodiment of the invention, a communication system includes a sender 101 and one or more receivers. The receiver according to one embodiment of the invention is one of a coherent receiver (such as 102A, 102B … … 102N) and a non-coherent receiver (such as 103A, 103B … … 103N). The transmitter 101 and the receiver are connected by a wireless channel.

Data transmitted from the sender 101 is received and processed simultaneously by coherent receivers 102A, 102B … … 102N and non-coherent receivers 103A, 103B … … 103N. The transmitter 101 transmits data over a ternary (ternary) alphabet {0, -1, +1 }. Coherent receivers 102A, 102B … … 102N demodulate the received signal through a ternary (ternary) alphabet {0, -1, +1}, whereas noncoherent receivers demodulate the received signal through a binary alphabet {0, 1 }.

Throughout this specification, for convenience, coherent and non-coherent receivers are interchangeably denoted by reference numerals 102 and 103 or coherent receivers 102A, 102B … … 102N and non-coherent receivers 103A, 103B … … 103N, respectively.

Fig. 2 is a block diagram depicting data processing operations in an exemplary communication network, in accordance with one embodiment of the present invention.

In block 201 of fig. 2, data to be transmitted in digital form is presented. At the transmitter 101, the data is divided into data blocks of length k (called data symbols). Thus, N is 2^kThe data symbols are encoded as N different ternary sequences (ternary sequences). The coding requires the number of different ternary sequences to be equal to N. For example, when the symbol size k is 3, each of N-8 symbols is uniquely encoded as one of N-8 ternary sequences.

The transmitter obtains data symbols from a symbol set S, wherein

S＝{s₀,s₁,……,s_N-1},N＝2^k

These data symbols are mapped to symbols from the codeset C ═ C₀,……,c_N-1One of N possible ternary sequences. The mapping is represented as follows:

we define a set of intervals Z_N0, 1, 2, … …, N-1. Note that m, g ∈ Z_N. The corresponding ternary sequence is sent to both the non-coherent receiver 103A and the coherent receiver 102A.

When the transmitter 101 transmits the ternary sequence, the coherent receiver 102A receives the ternary sequence unchanged. The non-coherent receiver 103A receives the absolute value of the ternary sequence transmitted from the transmitter 101, that is, the transmitted ternary sequence having "-1" is received as a ternary sequence having "+ 1". Therefore, in order to efficiently transmit the same ternary sequence to the coherent receiver 102A and the non-coherent receiver 103A, the ternary sequence should belong to a ternary code set (ternary code set) C satisfying the following properties.

a. The sequences in the ternary code set C should be maximally separated.

b. The sequences in the corresponding binary code set | C | which are composed of sequences obtained as absolute values of the corresponding sequences in the ternary code set C should be maximally separated.

The design of the ternary code set C is achieved by designing a single sequence with good autocorrelation properties on the binary alphabet {0, 1} and the ternary alphabet {0, -1, +1 }.

This sequence is hereinafter referred to as "base ternary sequence (base ternary sequence)" throughout the specification.

The ternary code set C is obtained as a set of all cyclic shifts of the base ternary sequence described above. Let the base ternary sequence appear as t_bThen the codeset C is given by:

here, L^g{t_bIs the "g cyclic shift" operator that cyclically shifts the base ternary sequence by "g" elements. It may be noted that cyclic shifts may be applied in any direction, meaning that all cyclic shifts are along the same direction whenever more than one cyclic shift is considered.

The mapping in equation (1) may be rewritten as:

we can now look from the symbol set s to Z_NThe one-to-one mapping of (a) is defined as:

g＝f(s_m) (3)

where f (x) is the symbol s_mMapping e S to cyclic shift g e Z_NAny one-to-one mapping of. For example, g ═ f(s)_m) May be equivalent to a binary symbol s_mDecimal system of (d). Similarly, g ═ f(s)_m) May be identical to the symbol s_mGray mapping of (or mapping) or mapping data symbols s_mMapping e S to cyclic shift e Z_NAny other one-to-one mapping of. Thus, each data symbol is mapped to a unique cyclic shift of the base ternary sequence.

Inverse mapping f^-1(x) Is defined as:

s_m＝f^-1(g) (4)

in all of the following discussions, we consider the mapping in equation (3) as a one-to-one mapping and the mapping described by equation (4) as the inverse of the one-to-one mapping.

Fig. 3 is a flow diagram illustrating a method of transmitting data according to one embodiment of the invention. In step 301, the base ternary sequence is retrieved and stored in all transmitters and receivers. In step 302, one or more ternary sequences corresponding to data symbols to be transmitted are obtained from a base ternary sequence. This step is explained in detail in fig. 4. In step 303, the ternary sequence is transmitted to the receiver.

In step 304 of fig. 3, if the receiver is a coherent receiver 102A, 102B, … …, 102N, the receiver correlates the received signal with all cyclic shifts of the base ternary sequence. Likewise, the non-coherent receivers 103A, 103B, … …, 103N demodulate the received signal by correlating it with all cyclic shifts of the absolute value of the base ternary sequence.

In step 305, each data symbol transmitted is detected by mapping the above-mentioned cyclic shift back to the data symbol using the inverse of the one-to-one mapping based on the cyclic shift corresponding to the largest correlation value among all N correlation values corresponding to all N cyclic shifts.

In one embodiment, the sending and receiving may be explained as follows. And symbol s_mE.s corresponding transmitted signal (equivalently, c)_gE C) is expressed as:

here, p (t) is a pulse shaping waveform and c_g[0]，c_g[1]，……，c_g[N-1]Refers to the ternary sequence c_gOf (2) is used. Chip duration time T_cAnd (4) showing. And ternary sequence c interfered by Additive White Gaussian Noise (AWGN) and other channel impairments_gE C corresponding transmitted signal (equivalently, symbol s)_mEs) is received by the receiver.

For example, let y^c _g(t) and y^nc _g(t) signals c to be transmitted_g(t) the baseband equivalents of the corresponding signals received at the coherent receiver 102 and the non-coherent receiver 103. It can be noted that y^nc _g(t)＝|y^c _g(t) |. For clarity, in the following discussion, signal y^c _g(t) and y^nc _g(t) ternary sequence c referred to as AND-Send_gE.c corresponding to the "received ternary sequence". If the receiver is a coherent receiver, by the ternary sequence y to be received^c _g(t) correlating all cyclic shifts of the base ternary sequence to y^c _g(t) demodulating. Likewise, by converting the received ternary sequence y^nc _g(t) correlating all cyclic shifts of the absolute value of the base ternary sequence to y^nc _g(t) demodulating. This will be described below.

g∈Z_NSuch as:

similarly, for non-coherent receivers, we have

Wherein the content of the first and second substances,

the data symbols are detected based on a single cyclic shift corresponding to a maximum correlation value among all N correlation values corresponding to the N cyclic shifts. If we make cyclic shift with g ═ g_EstimatingCorresponding maximum correlation value is Corr_maxThen the data symbol is detected as:

fig. 4 is a flowchart illustrating a method of acquiring one or more ternary sequences corresponding to data symbols to be transmitted from a base ternary sequence. In step 401, the transmitter divides data to be transmitted into one or more data symbols having a predefined length. In step 402, each symbol from the set of data symbols S is mapped onto one of N possible ternary sequences from the set of codes C obtained as a cyclic shift of the base ternary sequence. The process of the mapping and inverse mapping is explained in detail in equations 3 and 4.

FIG. 5 isA flow diagram illustrating a method of generating a base ternary sequence is shown, according to one embodiment of the present invention. In step 501, a seed sequence of a predefined length is selected. The seed sequence may be an m-sequence or the complement of an m-sequence. The seed sequence is N-1 in length, where N-2ⁿIs the desired length of the base ternary sequence. If the seed sequence is an m-sequence, the weight of the sequence is N/2, and if the seed sequence is the complement of the m-sequence, the weight is (N-2)/2.

At step 502, it is determined whether the weight of the selected seed sequence is a perfect square (perfect square). In the present invention, the weight of a sequence is the number of non-zero elements in the sequence. According to one embodiment of the invention, if the weight of the selected seed sequence is a perfect square, a perfect ternary sequence is generated from the seed sequence as shown in step 503. The method of generating a perfect ternary sequence from a seed sequence is explained in detail in fig. 6. If the weight of the selected seed sequence is not a perfect square, then a near perfect ternary sequence is generated from the seed sequence as shown in step 504. The method of generating a near-perfect ternary sequence from a seed sequence according to step 504 is explained in detail in fig. 7.

In step 505, predefined values are inserted in predefined positions of the perfect ternary sequence or near the perfect ternary sequence for generating a base ternary sequence. The predefined value is determined based on a seed sequence selected for the generation of a perfect ternary sequence. The position for inserting the predefined value is the position, among all possible positions, at which the MSAC of the resulting base ternary sequence and the MSAC of the absolute value of the base ternary sequence are minimal. There are two cases, in one case, if the selected seed sequence used to produce a perfect ternary sequence is an m-sequence, then a value of "1" is inserted in the perfect ternary sequence or in a near-perfect ternary sequence. In another case, if the selected seed sequence is the complement of the m-sequence, the predefined value inserted close to a perfect ternary sequence is the value "1".

Fig. 6 is a flow diagram illustrating a method of generating a perfect ternary sequence from a seed sequence, according to one embodiment of the present invention. In step 601, seed sequences are usedA pair of preferred m-sequences is obtained. The first m-sequence in this preferred pair is itself a seed sequence. The second seed sequence in the preferred pair is a predefined decimated m-sequence that is obtained as a seed sequence. It is a known technique to obtain said predefined decimation of another m-sequence from a given m-sequence. In this context, it is assumed that the values are from the set

Then the preferred pair of m-sequences of period P ═ N-1 (where N ═ 2)ⁿ) Is a pair of m-sequences x and y with a cross-correlation sequence theta (x, y). K of the sequence theta (x, y)^thThe (kth) element is given by:

at step 602, a correlation sequence θ (x, y) for the preferred pair is obtained using equation (10).

At step 603, the shifted correlation sequence Ψ from the corresponding correlation sequence θ (x, y) is obtained^(x,y). The offset correlation sequence is obtained by adding a value of "1" to each element in the correlation sequence. I.e. Ψ^(x,y)1+ θ (xy). Let Ψ^(x,y)The elements of (a) are the following values:

at step 604, a perfect ternary sequence is generated based on the shifted correlation sequence. To generate a perfect ternary sequence, the shifted correlation sequence Ψ^(x,y)1+ θ (x, y) divided by

The sequence Λ (x, y) with elements 0, ± 1} is obtained.

The method steps described in step 602, step 603 and step 604 are shown using the following example for obtaining a perfect ternary sequence of length 7.

This is demonstrated in the following example using an m-sequence with a period (period) of 7. The m-sequence x is selected as the seed sequence and the m-sequence y forms a preferred pair with the m-sequence x.

Let x be { 0111010 }

And, y ═ { 0101110 }

Then, let the cross-correlation θ (x, y) be given by:

θ(x,y)＝{-1 -1 -5 3 3 -1 3}

Ψ^(x,y)＝1+θ(x,y)＝{0 0 -4 4 4 0 4}

the sequence Λ (x, y) is thus obtained as:

the sequence Λ (x, y) is a perfect ternary sequence with θ (x, y) ═ 4000000 }. Note also that the sequence Λ (x, y) is also a cyclic shift of the absolute value of the seed m-sequence x.

FIG. 7 is a flow diagram illustrating a method of generating a near perfect ternary sequence, according to one embodiment of the present invention. If the weight of the seed sequence is different from the perfect square number, a near perfect ternary sequence is generated from the seed sequence. In step 701, one or more candidate sequences are obtained by inverting the values of one or more positions in the seed sequence corresponding to "1" for a predefined ratio. In this context, inversion changes a "1" to "-1". According to one embodiment of the present invention, candidate sequences are obtained by inverting all possible combinations of "1" s in the sequence such that the ratio of the number of-1 s to the number of 1 s in the resulting sequence is within a predefined ratio range. The above-mentioned predefined ratio ranges refer to all ratios between 1/3 and 2/3.

At step 702, at least one sequence is selected from the candidate sequences as a near-perfect ternary sequence based on a minimum value of a Mean Square Autocorrelation Coefficient (MSAC). MSAC is calculated as the average of N-1 of phase squared autocorrelation coefficients. Therefore, a near perfect ternary sequence is obtained by performing a computer search on these scales. A sequence is selected having a minimum value of a Mean Square Autocorrelation Coefficient (MSAC).

The mean square autocorrelation of a sequence of length P is defined as:

here, P ═ N-1 is the length of the seed sequence, and R (τ) is the period of the sequence delayed by τ, given by:

when the seed sequence is an m-sequence, base ternary sequences of lengths 8, 16 and 32 are shown in table 1.

TABLE 1

Base ternary sequences of lengths 8, 16 and 32 when the seed sequence is the complement of the m-sequence are shown in table 2. Note that multiple base ternary sequences with similar MSACs are obtained and are all given in tables 1 and 2.

TABLE 2

The sequence in table 2 has a smaller number of consecutive non-zero elements, which may be desirable in receiver design. A sequence with a uniform distribution of zero and non-zero elements is selected from all the sequences listed in table 2 to obtain a comprehensive list of base ternary sequences shown in table 3.

TABLE 3

In an exemplary embodiment of the present invention, the cyclic shifts of the base ternary sequences of lengths 8, 16 and 32 are presented in table 3. These are used to encode data symbols of size k 3, k 4 and k 5, respectively, prior to transmission. These base ternary sequences in Table 3 are referred to as 3/8-OOK, 4/16-OOK, and 5/32-OOK, respectively. Here, "OOK" represents ON-OFF Keying.

Table 4 shows the base ternary sequences in table 3 with respective terms (nomenclature).

TABLE 4

According to embodiments of the present disclosure, alternative term families, such as 3/8 ternary OOK (3/8-too), 4/16 ternary OOK (4/16-too), and 5/32 ternary OOK (5/32-too), and 3/8 ternary ASK (3/8-TASK), 4/16 ternary ASK (4/16-TASK), and 5/32 ternary ASK (5/32-TASK), may also be provided to the terms 3/8-OOK, 4/16-OOK, and 5/32-OOK, respectively, of the sequences as referenced in table 4. Here, "ASK" means Amplitude shift keying (Amplitude shifting).

Table 5 shows an example of mapping a data symbol with k-3 onto a cyclic shift of a base ternary sequence of length 8, wherein each cyclic shift of the base ternary sequence is obtained as the decimal equivalent of the respective binary representation of the data symbol. As previously described, any other one-to-one mapping described by equation (3) as mentioned in fig. 2 may be used to map the data symbols onto different cyclic shifts of the base ternary sequence.

TABLE 5

The autocorrelation function of the base ternary sequence for an arbitrary delay k can be expressed as follows:

R(k)＝xp+qx+R^a(N-k+1)+R^a(k) (13)

in the above expression, the binary value "x" is equal to "0" when the base ternary sequence is derived from a perfect ternary sequence.

Likewise, "x" equals "1" when the base ternary sequence is derived from a near-perfect ternary sequence.

The elements "p" and "q" represent those elements that match (align with) the element x at an arbitrary delay k. Term R^a(k) Is an aperiodic autocorrelation coefficient defined as:

here, c ═ { c ═ c₀，c₁，c₂，……，c_N-1Is the sequence for which the aperiodic autocorrelation coefficients are calculated.

An example of generating a perfect ternary sequence 00-11101 is explained below using an example.

Consider "x" inserted before the third bit, resulting in the sequence shown below.

{0 0x -1 1 1 0 1}

For any shift k-5, then the relative positioning of the elements of the sequence and its shifted copy are:

0 0x -1 1 1 0 1

-1 1 1 0 1 0 0x

the autocorrelation of the delay k 5 is given below:

R(k)＝x1+1x+R^a(3)+R^a(5)

in the above calculation, exactly p ═ q ═ 1.

When the base ternary sequence is derived from a perfect ternary sequence, we make x 0. Thus, r (k) is modified to:

R(k)＝R^a(N-k+1)+R^a(k) (15)

to limit

Maximum value of (k) of (a)By choosing the appropriate phase of the seed sequence sufficient to correct the phase shift

The value of (c) is minimized. However, in the literature, there are no known results for the phases of the seed sequence for minimizing aperiodic autocorrelation in both binary and ternary alphabets. However, if only the binary alphabet is considered, the autocorrelation properties of the sequence are determined by the aperiodic autocorrelation properties of the binary sequence. This fact is used to compute the autocorrelation of the binary sequence obtained by the spreading of a known sequence, such as the spread m-sequence.

Inserting x ═ 0 at a position corresponding to the minimum value of MSAC of the obtained base ternary sequence and the absolute value of the base ternary sequence ensures that equation (15) is the minimum value of different values for delay k.

Fig. 8 is a block diagram of a transmitter according to an embodiment of the present invention. According to one embodiment of the invention, the transmitter includes a data input module 801, a symbol generation module 802, a ternary sequence generation module 803, a base ternary sequence retrieval module 804, a cyclic shift generation module 805, and a transmission module 806.

In one embodiment of the invention, data to be transmitted is provided to data input module 801. The data input module 801 is operatively connected to a symbol generation module 802. The binary format data is divided into predefined lengths to produce data symbols. The symbol generation module 802 performs the above-mentioned operations.

According to one embodiment of the invention, the base ternary sequence is stored in the transmitter 101. The base ternary sequence retrieval module 804 retrieves the base ternary sequence and provides the base ternary sequence into the ternary sequence generation module 803. The ternary sequence generation module 803 is connected to the base ternary sequence retrieval module 804 and the symbol generation module 802. The ternary sequence generation module 803 generates one or more ternary sequences from the base ternary sequence by mapping each symbol to a corresponding ternary sequence obtained as a cyclic shift of the base ternary sequence based on the one-to-one mapping described in equation (3) in the description of fig. 2.

The transmission module 806 according to an embodiment of the present invention transmits the generated ternary sequence to the coherent receiver 102A and the non-coherent receiver 103A.

FIG. 9 is a block diagram of a base ternary sequence generation module according to one embodiment of the present invention. Generation of the base ternary sequence includes selection of a seed sequence, generation of a perfect ternary sequence, generation of a near perfect ternary sequence, and the like.

In an exemplary embodiment of the present invention, the base ternary sequence generating module 900 includes a seed sequence selecting module 901, a perfect ternary sequence generating module 902, a near-perfect ternary sequence generating module 903, and a predefined value inserting module 904.

The seed sequence selection module 901 selects a seed sequence for generating a base ternary sequence. The seed sequence may be an m-sequence or the complement of an m-sequence. The length of the selected seed sequence is N-1, where N is the expected length of the base ternary sequence to be generated.

If the weight of the sequence is a perfect square, then the seed sequence is fed into a perfect ternary sequence generation module 902. If the weight of the seed sequence is not a perfect square, the selected seed sequence is fed into a near perfect ternary sequence generation module 903.

The step of generating a perfect ternary sequence using perfect ternary sequence generation module 902 includes obtaining a preferred pair of m-sequences using a seed sequence. In addition, the perfect ternary sequence generation module 902 obtains the correlation sequence of the preferred pair. The correlation sequence is obtained as a cross-correlation function between the two sequences of the preferred pair. Then, the shifted correlation sequences are obtained from the corresponding correlation sequences, and a perfect ternary sequence is generated based on the shifted correlation sequences.

The operation of generating a near-perfect ternary sequence by the near-perfect ternary sequence generation module 903 includes the case when the weight of the seed sequence is different from the perfect square number. The generation of a near perfect ternary sequence includes: obtaining one or more candidate sequences by inverting all possible combinations of "1" in the seed sequence such that the ratio of the number of-1 to the number of +1 in the resulting sequence is within a predefined ratio range; and selecting at least one sequence from the candidate sequences as a near perfect ternary sequence based on a minimum value of a Mean Square Autocorrelation Coefficient (MSAC).

The predefined value insertion module 904 inserts a predefined value into a predefined position of one of the perfect ternary sequence and the near-perfect ternary sequence for generating a base ternary sequence. The predefined position for inserting the predefined value is the position among all possible positions that minimizes the resulting base ternary sequence and the MSAC of the absolute value of the base ternary sequence. If the seed sequence is an m-sequence, the inserted predefined value is "0". The predefined value inserted is "1" if the seed sequence is the complement of the m-sequence.

Fig. 10 is a block diagram of a receiver 102 according to one embodiment of the invention. The receiver may be coherent or non-coherent. A typical receiver includes a signal receiving module 1001, a demodulation module 1002, a cyclic shift sequence input module 1003, and a symbol detection module 1004.

The signal receiving module 1001 receives a signal transmitted from the transmitter 101. The received signal is demodulated using a demodulation module 1002. If the receiver is a coherent receiver, demodulation is performed by correlating the received signal with all cyclic shifts of the base ternary sequence. If the receiver is a non-coherent receiver, demodulation is performed by correlating the received signal with all cyclic shifts of the absolute value of the base ternary sequence. The cyclic shift of the base ternary sequence and the cyclic shift of the absolute value of the base ternary sequence are provided by the ternary sequence input module 1003. The associated values are fed to a symbol detection module 1004. The symbol detection module 1004 identifies the data symbol from the cyclic shift corresponding to the maximum value of correlation by mapping the cyclic shift back to the data symbol using the inverse of the one-to-one mapping.

FIG. 11 is a block diagram illustrating an exemplary communications device for implementing various components of an embodiment of the invention. The communication device 1100 may be a transmitter or a receiver. In fig. 11, a communication device 1100 includes a processor 1101, a memory 1104, a Read Only Memory (ROM)1102, a transceiver 1106, and a bus 1103.

Processor 1102, as used herein, means any type of computational circuit (such as, but not limited to, a microprocessor, a microcontroller, a complex instruction set computing microprocessor, a reduced instruction set computing microprocessor, a very long instruction word microprocessor, an explicit parallel instruction computing microprocessor, a graphics processor, a digital signal processor), or any other type of processing circuit. The processor 1102 may also include embedded controllers (such as general purpose or programmable logic devices or arrays, application specific integrated circuits, single-chip microprocessors, smart cards, etc.).

The memory 1104 and the ROM 1102 may be volatile memory and non-volatile memory. The memory 1104 includes a base ternary sequence generation module 1105 that generates a base ternary sequence according to one or more embodiments described in fig. 5. Various computer-readable storage media may be stored in or accessible from the memory element. The memory elements may include any suitable memory device for storing data and machine-readable instructions (such as read-only memory, random access memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, hard disk drives, removable media drives for handling compact disks, digital video disks, floppy disks, tape cassettes, memory cards, and the like).

Embodiments of the present subject matter may be implemented in conjunction with modules (including functions, procedures, data structures, and applications) for performing tasks or defining abstract data types or low-level hardware environments. The base ternary sequence generating module 1105 may be stored in the form of machine-readable instructions on any of the storage media described above and executable by the processor 1102. In one embodiment, the program may be included on a compact disk read only memory (CD-ROM) and loaded from the CD-ROM to a hard drive in a non-volatile memory. The transceiver 1106 is capable of transmitting and receiving data. The bus 1103 serves as an interconnection between various components of the communication device 1100.

The present embodiments have been described with reference to specific exemplary embodiments. It will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Further, the various devices, modules, etc. described herein may be enabled and operated using hardware circuitry, firmware, and/or software embodied in a machine-readable medium. While the embodiments herein have been described in terms of various specific embodiments, it will be apparent to those skilled in the art that the invention may be practiced with modification. However, all such modifications are considered to be within the scope of the claims. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein, and all statements of the scope of the embodiments that, as a matter of language, might be said to fall therebetween.