A signal modulation method and system based on a dual-mode index OSDM

Abstract

The application provides a signal modulation method and system based on a double-mode index OSDM, which comprises grouping input data bits, each group being mapped into an OSDM block and being divided into two parts; bits in one part entering an index selector to generate a pattern, and bits in the other part being respectively mapped to two different bit modulation modes and being combined to obtain data of each block after index modulation; the obtained groups of data being subjected to OSDM block processing, then being subjected to OSDM modulation, and being multiplexed into one group of data; the multiplexed data being subjected to channel impulse response to obtain a signal after channel equalization, and to obtain each block of the signal after equalization. The application can not only make data be implicitly transmitted through an active pattern, but also make data be transmitted through all carriers, thereby greatly improving the throughput of the OSDM system and greatly reducing the bit error rate and PAPR of the OSDM system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and particularly relates to a signal modulation method and system based on a dual-mode index OSDM. BACKGROUND

[0002] 75% of the earth's surface is covered by water, and there are many valuable resources under water, such as a large amount of energy resources, from mineral resources such as oil and natural gas to renewable energy. Due to the important role of underwater communication in the fields of environmental monitoring, ocean exploration, ocean data collection and disaster warning, underwater communication has become more and more important in the past few decades. Compared with the ground radio frequency communication channel, the underwater acoustic channel has large transmission loss, fast time-varying multipath propagation, limited bandwidth and distance-related, large propagation delay, and these shortcomings make the underwater acoustic channel one of the most difficult to use channels. Therefore, it is urgent to introduce new systems into the field of underwater acoustic communication to solve the problems of high bit error rate, high PAPR and low system capacity of the existing underwater acoustic communication system.

[0003] The underwater acoustic communication network is used in marine environmental monitoring, natural disaster warning, port and nearshore detection. With the increasing requirements for the exploration accuracy and speed of the underwater world, the requirements for the bit error rate and the authenticity of underwater communication are becoming higher and higher.

[0004] Currently, underwater communication and underwater detection are mostly based on underwater acoustic signals. Radio frequency and light waves can transmit information very quickly in a short distance underwater, but sound waves are still the only medium for underwater wireless communication at any distance. However, underwater acoustic signals are an extremely complex time-varying, frequency-varying and space-varying channel, and have characteristics such as strong multipath and high noise, making the underwater acoustic channel the most complex wireless communication channel. The research on high-speed medium-short-range underwater acoustic communication systems and low-speed long-range underwater acoustic communication systems has been very active. The limited bandwidth of long-range underwater communication limits the improvement of data rate. On the contrary, the relatively large available bandwidth of medium-short-range communication systems makes it possible to study high data rate schemes. In the face of the complex underwater acoustic channel of the ocean, the existing underwater acoustic communication systems, such as the Orthogonal Frequency Division Multiplex (OFDM) system, have a large bandwidth, but have a high PAPR and are sensitive to Doppler; the Single Carrier Frequency Domain Equalization (SC-FDE) system has a lower PAPR and better Doppler tolerance, but brings lower channel capacity and inflexible bandwidth; the Orthogonal Signal Division Multiplexing (OSDM) system has been used in underwater channel systems in recent years to provide a unified framework for OFDM and SC-FDE systems, but the disadvantage is that as the number of blocks of the OSM system decreases, the bit error rate performance will also deteriorate, and when the number of blocks increases, the PAPR also increases as the number of carriers decreases. Therefore, it is of great significance to further study the bit error rate performance of the OSM system and reduce the PAPR of the system, so as to bring a reliable high-speed underwater communication system.

[0005] OSDM is a new multiplexing modulation scheme that was first introduced into terrestrial wireless communication to achieve reliable transmission. Unlike traditional OFDM, at the sending end, it multiplexes multiple data vectors, a pilot signal and multiple messages into a data stream, and does not require any interpolation in the channel measurement process, and is modulated by a full-length inverse discrete Fourier transform. Due to the block characteristics of the system, the bit error rate performance of the OSM system is better when the number of blocks is high, and the PAPR performance is better when the number of blocks is low. Neither the PAPR is too high, nor the channel capacity is too low, thus making up for the gap between OFDM and SC-FDE, and the block characteristics of the OSM system make the system more flexible, so it can better cope with the changing environment of the underwater acoustic channel.

[0006] Recently, the concept of index modulation (IM) has attracted much attention from researchers. In recent years, researchers have applied the concept of index modulation to OFDM systems and proposed an OFDM system based on index modulation (OFDM-IM). This system not only transmits symbols through carriers, but also implicitly transmits data through indexes, which can improve the transmission rate of the system to a certain extent. However, due to the existence of non-activated carriers in the system, the spectral efficiency is lost to a certain extent. However, most of the existing indexes are applied to OFDM systems. Since the equalization of the receiving end of the ODSM system is relatively complex, high-complexity calculations are required at the receiving end when the index is used, so there is almost no research on the index applied to the ODSM system. With the proposal of more reliable modal indexes such as spread spectrum index modulation (IM-SS) and dual-mode index modulation (DM-IM), it is the current development trend of underwater high-speed information transmission to seek new index modalities for different systems to combat complex underwater acoustic channels in underwater acoustic communication. SUMMARY

[0007] To solve the above technical problems in the prior art, the present application provides a signal modulation method based on dual-mode index OSDM.

[0008] In one aspect, the present application provides a signal modulation method based on dual-mode index OSDM, the method comprising:

[0009] S1: Grouping the input data bits, each group is mapped into an OSDM block and divided into two parts;

[0010] S2: One part of the bits enters the index selector to generate a pattern, and the other part is mapped to two different bit modulation modes respectively, and the data of each block after index modulation is obtained by combination;

[0011] S3: The obtained multiple groups of data are subjected to OSDM block processing, and then subjected to OSDM modulation, and multiple groups of data are multiplexed into one group of data;

[0012] S4: The multiplexed data is subjected to channel impulse response to obtain a signal after channel equalization, and each block of equalized signal is obtained.

[0013] In some specific embodiments, S1 specifically comprises: for inputting m-bit data, using quantile to average into G groups, each group having p bits, i.e. p = m / G, and the p bits of each group are mapped to the OSDM block with a length of n, where n = N / G, N being the total number of symbols of the OSDM.

[0014] In some specific embodiments, S2 specifically comprises:

[0015] S21: for the p-bit data in the block g, the p-bit data is divided into two parts, the first part of p1 bits is input into an index selector to generate a pattern and

[0016] S22: the remaining p2 bits are divided into two groups and are respectively mapped to two different M h , M l bit modulation modes to realize different power allocations and After obtaining and , the data of the gth block is obtained, where p h and p l are two different power levels set for and , respectively, and specifically represent the modulation symbols under two different modulation modes.

[0017] In some specific embodiments, S3 specifically comprises: dividing the G groups of n-length data into U rows and K columns, where Gn = UK is satisfied, and performing OSDM modulation, and multiplexing the U groups of data into a single data X w is the data after the dual-mode index modulation.

[0018] In some specific embodiments, step S4 specifically comprises: after adding a cyclic prefix, the result is data obtained by passing through a channel impulse response h , and where L is the time delay of the channel; after obtaining the dual-mode index modulation data X w at the sending end, a pilot signal P 0 with strong autocorrelation characteristics is used to replace X 0 for channel estimation at the receiving end, and the channel impulse response h can be obtained at the receiving end through r and X 0 .

[0019] In some specific embodiments, after obtaining the impulse response h, a matrix C is calculatedw And obtain the signal Y after channel equalization. w =rD w (C w ) -1 D w express It is matrix f Uw The complex conjugate transpose, I K Given a K x K identity matrix, obtain the signal Y of the g-th block after equalization. g =rD g (C g ) -1 .

[0020] In some specific embodiments, the method further includes: calculating the ED or LLR values ​​of n received symbols, using information known at the transmitting end. For each pattern, calculate the sum of the received symbol values ​​at the k high-power symbol positions in each pattern. Find the pattern with the largest sum of these sums; this sum is the estimated pattern. The rest form a set Demodulation using ML detection All symbols:

[0021] Among them, Y g (β), X g (β) indicates that the signal is received in the g-th block, and the symbols in each block are all determined by M. h PSK symbol modulation, detecting the modulation symbols carried on the block symbols as follows: If the symbols in each block are all M l PSK symbol modulation, detecting the modulation symbols carried on the block symbols. This represents the specific modulation symbol estimate.

[0022] In some specific embodiments, ML detection demodulation is used. All symbols specifically include:

[0023] Step a: If All symbols satisfy Proceed to step d; otherwise proceed to step b.

[0024] Step b: In response to detection If all symbols are present, proceed to step d; otherwise, proceed to step c.

[0025] Step c: Use Symbol substitution in middle The symbol, and update The ML is used to detect the demodulated updated symbol, and the step a is returned;

[0026] Step d: using Regarding the complement set determination of the set {1,...,n} All the symbols of the gth block are detected by the ED.

[0027] According to the second aspect of the present application, a multi-dimensional OFDM-based signal modulation system is provided, which comprises:

[0028] The bit segmentation unit is configured to group the input data bits, and each group is mapped into two parts in the OSDM block.

[0029] The data processing unit is configured to enter the index selector with one part of the bits to generate a pattern, and the other part is respectively mapped to two different bit modulation modes, and the data of each block after index modulation is obtained by combination.

[0030] The OSDM modulation unit is configured to perform OSDM block processing on the obtained multiple groups of data, and then perform OSDM modulation to multiplex the multiple groups of data into one group of data.

[0031] The channel equalization unit is configured to pass the multiplexed data through the channel impulse response to obtain the signal after channel equalization, and obtain the signal after equalization of each block.

[0032] The present application provides a unified framework of OFDM and SC-FDE, which can overcome the problems of high PAPR of OFDM system and low capacity of SC-FDE system. By dual mode, all carriers are divided into two kinds of carriers carrying different modulation modes, which are used to carry different modulation modes, so that all carriers can carry symbols without idle carriers. By introducing index, the subcarriers are divided into block structures, and each block is transmitted. The DM-OSDM-IM system not only enables data to be implicitly transmitted through the activation pattern, but also enables data to be transmitted through all carriers, greatly improving the throughput of the OSDM system. At the same time, due to the introduction of dual-mode index in the system, the bit error rate and PAPR of the OSDM system can be greatly reduced, solving the problems of high bit error rate when the block number is low and high PAPR when the block number is high, and is an excellent underwater communication system. Compared with the traditional OFDM system and SC-FDE, the present application respectively reduces the high PAPR and improves the system capacity, and further reduces the bit error rate and PAPR of the traditional OSDM. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the application. Other embodiments and many of the intended advantages of the present application will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings:

[0034] Figure 1 is a flow chart of a signal modulation method based on dual-mode index OSDM according to an embodiment of the present application;

[0035] Figure 2 is a flow chart of a DM-OSDM-IM system framework according to a specific embodiment of the present application;

[0036] Figure 3 is a comparison chart of error rates of DM-OSDM-IM, OFDM-IM, and DM-OFDM according to a specific embodiment of the present application;

[0037] Figure 4 is a comparison chart of error rates of DM-OSDM-IM in different block cases according to a specific embodiment of the present application;

[0038] Figure 5 is a comparison chart of PAPRs of the present application and other two systems according to a specific embodiment of the present application;

[0039] Figure 6 is a comparison chart of PAPRs of DM-OSDM-IM systems in different block cases according to a specific embodiment of the present application;

[0040] Figure 7 is a comparison chart of performances of a low-complexity ML detector and a conventional ML detector according to a specific embodiment of the present application;

[0041] Figure 8 is a comparison chart of error rates of the present application and other detectors according to a specific embodiment of the present application;

[0042] Figure 9 is a framework chart of a signal modulation system based on dual-mode index OSDM according to an embodiment of the present application. DETAILED DESCRIPTION

[0043] The present application will be further described by examples in connection with the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the scope of the application. It is further noted that, for the sake of brevity, the figures of the drawings are not to scale.

[0044] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0045] Figure 1 A flow chart of a signal modulation method based on a dual-mode index OSDM according to an embodiment of the present application is shown. As shown, the method mainly includes the following steps: Figure 1

[0046] S101: Group the input data bits, and each group is mapped to two parts in an OSDM block.

[0047] In a specific embodiment, for input m-bit data, first use the quantile divider to divide into G groups, each group has p bits, that is, p = m / G, and the p bits in each group are mapped to an OSDM block with a length of n, where n = N / G, N is the total number of symbols of the OSDM.

[0048] S102: Enter the bits in one part into an index selector to generate a pattern, and the bits in the other part are respectively mapped to two different bit modulation modes, and the data of each block after index modulation is obtained by combination.

[0049] In a specific embodiment, this step specifically includes:

[0050] For the p-bit data in the block g, the first part of p1 bits is input into the index selector to generate a pattern and

[0051] The remaining p2 bits are divided into two groups and respectively mapped to two different M h and M l bit modulation modes;

[0052] The index selector is used to select k symbols from n symbols as high-power symbols, and the remaining n-k symbols are as low-power symbols, so p1 can be calculated;

[0053] After the calculation of and , the positions of the high-power symbols and the low-power symbols are determined, and they will respectively carry the symbols of M h and M l PSK, so p2 can be calculated;

[0054] p2 is divided into two parts and respectively input into the symbol mapping of M h and M l , and then different power allocations are realized and​ After obtaining and , the data of the gth block can be obtained.

[0055] S103: The obtained groups of data are subjected to block processing of OSDM, and then subjected to OSDM modulation, and the groups of data are multiplexed into one group of data.

[0056] In a specific embodiment, the G groups of n-length data are divided into U rows and K columns, where Gn=UK is satisfied, and then subjected to OSDM modulation, and the U groups of data are multiplexed into one group of single data. X w is the data after bimodal index modulation.

[0057] S104: The multiplexed data are subjected to channel impulse response to obtain a signal after channel equalization, and a signal after equalization of each block is obtained.

[0058] In a specific embodiment, assuming that the delay of the channel is L, the result after adding the cyclic prefix is After the channel impulse response h, the following can be obtained and rD w and X w have the following relationship (n=0):

[0059]

[0060] In order to obtain a good channel h, the data X after bimodal index modulation is obtained at the sending end w , and then the pilot signal P 0 with strong autocorrelation characteristics is used to replace X 0 for channel estimation at the receiving end. Through the periodic autocorrelation characteristics of X 0 , the following conclusions are obtained:

[0061]

[0062] The channel impulse response h can be obtained at the receiving end through r and X 0 , and the impulse response h is obtained using X 0 , and then the matrix C w can be calculated. Therefore, the signal Y w after channel equalization can be obtained w (C w ) -1 , is the complex conjugate transpose of the matrix f Uw , and I Kis a K by K identity matrix. Finally, the signal of the gth block after equalization Y g = rD g (C g ) -1 .

[0063] Through the above method, the input data is converted through a series of conversion, and finally the signal after channel equalization can be obtained at the receiving end.

[0064] The application provides a double-mode index OSDM system design, according to the input data, the data is divided into two parts through a bit splitter, and the grouped data is divided into different power levels through an index selector and mapping. Finally, the design of a low-complexity detection algorithm at the receiving end solves the problem of high complexity at the receiving end caused by the index in the system. In order to introduce the content of the application in detail, some concepts are described or defined as follows:

[0065] Definition 1: peak-to-average power ratio (PAPR)

[0066] MIMO-OFDM system can provide greater coverage, better transmission quality, higher data rate and spectral efficiency. However, since the OFDM symbol is superimposed by a plurality of independently modulated sub-carrier signals, when the phases of each sub-carrier are the same or similar, the superimposed signal will be modulated by the same initial phase signal, thereby generating a large instantaneous power peak, which further brings a high peak-to-average power ratio (PAPR-Peak to Average Power Ratio), simply referred to as peak-to-average ratio (PAPR). Since the dynamic range of a general power amplifier is limited, a MIMO-OFDM signal with a large peak-to-average ratio is easy to enter the nonlinear region of the power amplifier, resulting in nonlinear distortion of the signal, causing significant spectral spread interference and in-band signal distortion, resulting in a serious decline in the performance of the entire system. High peak-to-average ratio has become a major technical obstacle for MIMO-OFDM. The PAPR is calculated as follows: Where C is usually called crest factor, or peak-to-average ratio, simply referred to as PAR. Since the peak amplitude of a waveform is always greater than or equal to the RMS amplitude, PAPR ≥ 1.

[0067] For a discrete signal x, its root mean square amplitude is: The peak amplitude is: xpeak = max[|x|], and the peak-to-average power ratio (PAPR) has the following characteristics: when transmitting information, the amplitude and phase of each subcarrier can be assumed to be independent random events; when all subcarrier amplitudes and phases are consistent (all subcarriers have the same symbol), the resulting composite wave will have a very large peak, which can exceed the average value by many dB; in general, the more subcarriers, the larger the PAPR; the linear response range of the amplifier of the electronic component is limited, that is, when the symbol combination requires a peak value that exceeds the linear range, the amplifier cannot actually achieve it.

[0068] Definition two: bit error rate

[0069] The generation of error codes is due to the change of signal voltage caused by fading in signal transmission, which causes the signal to be destroyed in transmission and generates error codes. Noise, alternating current or lightning caused impulse, transmission equipment failure and other factors can cause error codes (such as the transmitted signal is 1, and the received signal is 0; vice versa). Various different specifications of equipment have strict error rate definitions. The calculation formula is: bit error rate = number of error bits / total number of transmitted bits.

[0070] Definition three: low complexity ML detection

[0071] First, assume that each block contains M h PSK symbol modulation, detect the modulation symbols carried on the block symbols: If each block contains M l PSK symbol modulation, detect the modulation symbols carried on the block symbols: Therefore, according to the formula can be estimated: where: and: The corresponding modulation symbols can be estimated by calculation: Its complexity is Its complexity is linear level.

[0072] Definition four: low complexity ED detection

[0073] For DM-OSDM-IM systems, the transmitting end respectively and assign different powers p h and power p l to the corresponding symbols. Therefore, the average power of the βth symbol in the gth OSM block at the receiving end can be written as: For the above equation, we have: where: is the instantaneous power of the received symbol. After calculating all n values of the equation, we take the k indices of the maximum values of the equation to estimate and determine After estimating , we can get the number of bits of the index by looking up a table or using a combination number method. At the same time, after knowing the symbol positions corresponding to high and low power, we can get the corresponding modulation symbols:

[0074] where and are the estimated values of and , respectively. From the above detection, the complexity of the ED detector is O(kM h +(n-k)M l +nlogn), where nlogn is the complexity of sorting n values when looking for k high-power symbols, and kM h and (n-k)M l are the complexities of constellation point detection after finding the high-power and low-power symbol positions, respectively.

[0075] Definition five: low complexity LLR detection

[0076] In the DM-OSDM-IM system, the symbols in each block are modulated by M h symbols with power p h or M l symbols with power p l , so the modulation mode of each block symbol can be obtained by calculating the logarithm of the ratio of the probability after being modulated by M h and the probability after being modulated by M l :

[0077] where β = 1,..., n, X h，χ ∈ X h and X l，χ ∈ X l . At the same time, because: the above equation can be written as follows: In order to prevent numerical overflow, the last two polynomials in the above equation are calculated using the Jacobian logarithm. Therefore, after the LLR detector calculates all n LLR values, it determines the k indices of the maximum LLR values to determine Then, the remaining n-k terms determine to get After that, the corresponding modulation symbols can be estimated as the ED detector.

[0078] Reference Figure 2 , Figure 2 A DM-OSDM-IM system framework flow chart according to one specific embodiment of the present application is shown, and the specific implementation steps of the dual-mode index-based OSDM system are as follows:

[0079] Step 1: For input m-bit data, first use the quantile to divide into G groups, each group has p bits, i.e. p = m / G, and the p bits of each group are mapped to the OSDM block with a length of n, where n = N / G, N is the total number of OSDM symbols. As a DM-OSDM-IM system, the p-bit data in the block g is divided into two parts, the first part of p1 bits is input into the index selector to generate a pattern and and The corresponding symbols are set to two different power levels, denoted as p h and p l , and p h > p l , and the remaining p2 bits are divided into two groups and mapped to two different M h , M l modulation modes;

[0080] Step 2: Calculate p1 and p2, and map the results of p2 to achieve different power allocation to obtain and In this way, the data of the gth block can be obtained: X g = [X g (1), X g (2),... X g (n)] T ;

[0081] Step 3: Perform OSDM block processing, which assumes that the G groups of n-length data are divided into U rows and K columns, where Gn = UK, and then perform OSDM modulation to multiplex the U groups of data into a single data:

[0082] Step 4: Add the results of the cyclic prefix after the channel impulse response;

[0083] Step 5: After obtaining the dual-mode index modulation data X w at the sending end, replace X 0 with a pilot signal P 0 with strong autocorrelation characteristics to perform channel estimation at the receiving end;

[0084] Step 6: Using r and X 0 To obtain the impulse response h of the channel, the matrix C is calculated. w Therefore, we can obtain the signal after channel equalization, and finally obtain the signal of the g-th block after equalization.

[0085] Step 7: After obtaining the ED or LLR calculation values ​​of n received symbols, use the known values ​​at the transmitting end... For each pattern, calculate the sum of the received symbol values ​​at the k high-power symbol positions in each pattern. The pattern with the largest sum is then identified as the estimated pattern. The rest form a set

[0086] Step 8: Next, we will perform ML detection to demodulate. All symbols:

[0087] Among them, Y g (β), X g (β) indicates that the signal is received in the g-th block, and the symbols in each block are all determined by M. h PSK symbol modulation, detecting the modulation symbols carried on the block symbols as follows: If the symbols in each block are all M l PSK symbol modulation, detecting the modulation symbols carried on the block symbols. This represents the specific modulation symbol estimate.

[0088] Step 9: If All symbols have Then proceed to step 12; otherwise, proceed to step 10.

[0089] Step 10: If detected If all symbols are found, proceed to step 12; otherwise, proceed to step 11.

[0090] Step 11: Use Symbol substitution in middle The symbol, and update Then, using the previously detected and demodulated symbols from ML, proceed to step nine.

[0091] Step 12: Use Regarding the determination of the complement of the set {1, ..., n} Then, all symbols in the g-th block are demodulated using ED detection.

[0092] The signal is processed and converted by the above method, and is detected by a designed low complexity detection at the receiving end. The DM-OSDM-IM system is proposed, and the problem of high bit error rate of the OSDM system when the number of blocks is small and the problem of high PAPR when the number of blocks is large are solved. The double-mode index system can not only implicitly transmit data through the activation pattern, but also transmit data through all carriers. The low complexity detection algorithm at the receiving end of the DM-OSDM-IM system is designed, and the problem of high complexity at the receiving end caused by the index is solved. A reliable high-speed underwater communication system is built.

[0093] Figures 3-6 The DM-OSDM-IM, OFDM-IM, DM-OFDM bit error rate comparison diagram, DM-OSDM-IM bit error rate comparison diagram under different block conditions, three system PAPR comparison diagram and DM-OSDM-IM system PAPR comparison diagram under different block conditions are shown respectively. For the DM-OSDM-IM system in the application, different block numbers will bring different performance, and as the block number increases, the bit error rate performance is better. When the block number of the DM-OSDM-IM system is 256 and 128, the PAPR curve of the system is similar to that of the OFDM-IM and DM-OFDM systems, and when the block number is reduced to 64 and 16, it is obviously better than the other two systems, and when the block number is 4, the PAPR curve is close to that of the SC-FDE. Therefore, the performance of the DM-OSDM-IM system in PAPR is far superior to the other two systems. It is shown that the bit error rate performance of the DM-OSDM-IM system proposed by us is the same as that of the traditional OFDM-IM system when the block number reaches 64, and when the block number exceeds 64, especially when the block number reaches 256, the bit error rate performance is improved by 1 dB, and the PAPR is only half of that of the OFDM-IM system. It is an excellent underwater communication system.

[0094] Figure 7 The low complexity ML detector and the performance comparison diagram of the traditional ML detector according to one specific embodiment of the application are shown as Figure 6 As shown in the figure, when the SNR is [-5, 25], the results under the ML detector and the low complexity ML detector are shown at 10 -3 The bit error rate display results of the two detectors are almost the same at the bit error rate level of 10

[0095] Figure 8The following diagram illustrates the bit error rate (BER) plots of this application with other detectors according to a specific embodiment of this application, such as... Figure 8 As shown, the bit error rate results obtained using different receivers under the condition of SNR [0, 25] were simulated. -3 At the given bit error rate (BER) level, the conventional ED detector exhibits a higher BER, with a BER performance reduction of 1.5 dB compared to the low-complexity ML detector. The conventional LLR detector, compared to the low-complexity ML detector, shows a 0.5 dB decrease in gain. However, the improved LLR and ED algorithms reduce their BER, achieving receiver performance gains of 0.8 dB and 0.2 dB respectively compared to the unimproved versions.

[0096] Figure 9 This is a framework diagram of a signal modulation system based on dual-mode indexed OSDM according to an embodiment of this application, as shown below. Figure 9 As shown, the system includes a bit segmentation unit 901, a data processing unit 902, an OSDM modulation unit 903, and a channel equalization unit 904. The bit segmentation unit 901 is configured to group the input data bits, with each group mapped to an OSDM block and divided into two parts. The data processing unit 902 is configured to input one part of the bits into an index selector to generate a pattern, while the other part is mapped to two different bit modulation schemes and combined to obtain each block of data after index modulation. The OSDM modulation unit 903 is configured to perform OSDM block processing on the obtained multiple data groups, then perform OSDM modulation, multiplexing the multiple data groups into a single data stream. The channel equalization unit 904 is configured to pass the multiplexed data through a channel impulse response to obtain the channel-equalized signal, and obtain the equalized signal for each block.

[0097] This invention further incorporates the advantages of OSDM systems over OFDM systems into DM-OFDM, and further proposes the concepts of low-power symbols and high-power symbols, thus forming a DM-OSDM-IM system. The input data is first grouped. For each group, the data bits in each block are then divided into two parts. The first part is input into an index selector to generate patterns and corresponding symbols. and and The corresponding symbols are set to two different power levels, and the remaining part of the block is further divided into two groups, which are mapped to two different M values ​​respectively. h M lThe method is based on the bit modulation mode. Multiple groups of data are multiplexed into a single data. Finally, the impulse response is obtained by calculation at the receiving end, and then the signal after channel equalization is obtained. Compared with the traditional OFDM system and SC-FDE, the method respectively reduces the high PAPR and improves the system capacity, and further reduces the bit error rate and PAPR of the traditional OSM.

[0098] The above description is only the preferred embodiment of the application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with the technical features disclosed in the present application (but not limited to) having similar functions to form a technical solution.

Claims

1. A method of signal modulation based on dual-mode index ODSM, characterized in that, The method comprises: S1: grouping input data bits, each group being mapped into two parts in an OSDM block; S2: entering one part of bits into an index selector to generate a pattern, and the other part being respectively mapped into two different bit modulation modes, and combining to obtain data of each block after index modulation; S3: performing block processing on the obtained multiple groups of data by OSDM, then performing OSDM modulation, and multiplexing the multiple groups of data into one group of data; S4: passing the multiplexed data through a channel impulse response to obtain a signal after channel equalization, and obtaining a signal after equalization of each block; The S1 specifically includes: for input data of bits, using quantile divider to average into groups, each group has bits, that is , bits of each group are mapped to the length of OSDM block on , wherein , is the total number of symbols of OSM The S2 specifically comprises: S21: for the block in bit data is divided into two parts, the first part of bit is input into the index selector, to generate a pattern and ; S22: Remaining The bits are divided into two groups, each mapped to one of two different... Bit modulation methods can achieve different power distributions. and After obtaining and After that, the first The data consists of blocks, among which... and They are respectively and The corresponding symbols set two different power levels. And specifically, the modulation symbols used in two different modulation methods; The S3 specifically includes: group Length of data into row Column, where to meet , OSM modulation, Group data multiplexed into a single data , Dual-mode index modulation after data; The S4 specifically comprises: adding a cyclic prefix to the result of the data through the channel impulse response , obtaining , and simultaneously obtaining , wherein, is the time delay of the channel, represents one of the k high-power symbols; after obtaining the data after the dual-mode index modulation at the sending end , the pilot signal with strong autocorrelation characteristics is used to replace to be used for channel estimation at the receiving end, and the channel impulse response can be obtained at the receiving end through and ; obtaining said impulse response post-computing the matrix ， and obtain the signal after channel equalization wherein denotes , is the complex conjugate transpose of the matrix , is a row column identity matrix, and obtain the signal of the gth block after equalization .

2. The signal modulation method based on the dual-mode index OSDM according to claim 1, characterized in that, Further comprising: calculate The ED or LLR value of each received symbol is known from the transmitter. For each of the given patterns, calculate the value of each pattern. The sum of the calculated values ​​of the received symbols at each high-power symbol location is compared to find the pattern with the largest sum; this sum is the estimated pattern. The rest form a set Demodulation using ML detection All symbols: ， wherein, wherein, , denotes the block received signal, each symbol in the block is modulated by PSK symbols, the modulated symbols carried on the block are detected as , if each symbol in the block is modulated by PSK symbols, the modulated symbols carried on the block are detected as , denotes the specific modulation symbol estimate.

3. A signal modulation method based on dual-mode index OSDM according to claim 2, characterized in that, ML detection demodulation All symbols specifically include: Step a: If all symbols of , go to step d, else go to step b; Step b: jump to step d in response to detecting all of the symbols, else go to step c; Step c: Use Symbol substitution in middle The symbol, and update Use ML to detect the demodulated updated symbols and return to step a; Step d: use the complement of the set determined in step c , all symbols of the first block are detected by ED demodulation. ​ 4. A multi-dimensional OFDM based signal modulation system, characterized by The system comprises: A bit segmentation unit configured to group input data bits, each group being mapped into two parts in an OSDM block; A data processing unit configured to enter one part of bits into an index selector to generate a pattern, and the other part being respectively mapped into two different bit modulation modes, and combining to obtain data of each block after index modulation; An OSDM modulation unit configured to perform block processing on the obtained multiple groups of data by OSDM, then perform OSDM modulation, and multiplex the multiple groups of data into one group of data; A channel equalization unit configured to pass the multiplexed data through a channel impulse response to obtain a signal after channel equalization, and obtain a signal after equalization of each block; The bit partitioning unit includes: for input data of bits, using quantile partitioner to average into groups, each group has bits, that is , bits of each group are mapped to the length of OSDM block , wherein , is the total number of symbols of OSM The data processing unit specifically comprises: S21: for the block in bit data is divided into two parts, the first part of bit is input into the index selector, to generate a pattern and ; S22: the remaining bits are divided into two groups, which are mapped to two different modulation modes, respectively, to achieve different power allocations and After obtaining and , the data of the first block is obtained, wherein and are two different power levels set for and corresponding symbols, respectively and specifically represent the modulation symbols under two different modulation modes The OSDM modulation unit specifically comprises: group Length of data into row Column, which satisfies , OSM modulation, Group data multiplexed into a single data , Dual-mode index modulation data; The channel equalization unit specifically includes: the result after adding a cyclic prefix is... Data after channel impulse response ,get At the same time, obtain ,in, For the channel delay, Represents one of k high-power symbols; obtains dual-mode indexed modulated data at the transmitting end. Then, pilot signals with strong autocorrelation characteristics are utilized. replace Used for channel estimation at the receiver, which can be achieved at the receiver via... and Obtain the impulse response of the channel ; obtaining said impulse response post-computing the matrix ， and obtain the signal after channel equalization wherein denotes , is the complex conjugate transpose of the matrix , is a row column identity matrix, and obtain the signal of the gth block after equalization .

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