[0072] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following examples are used to further describe the present invention in detail.
[0073] As mentioned above, the communication system usually adopts a preamble signal before the data frame to assist the communication system to complete the synchronization process. Figure 7 A schematic diagram of the structure of the preamble signal and data frame is given. like Figure 7 As shown, the preamble signal may be shared by several data frames, or may be used by each data frame. The preamble signal generally adopts an autocorrelation signal with good autocorrelation that can provide accurate timing information. For example, the preamble signal can be a frame synchronization sequence, or a Barker code in the radar, or other autocorrelation. signal, which can provide accurate timing information.
[0074] Figure 8 and Figure 9 The schematic diagrams of the signal frame structure when multiple data frames share one preamble signal and each data frame use one preamble signal are respectively given. exist Figure 8 Among them, n data frames share one preamble signal, so each preamble signal corresponds to n data frames. exist Figure 9 , each of the n data frames uses a preamble signal, so each preamble signal corresponds to a data frame.
[0075] In the embodiment of the present invention, a preamble signal corresponding to the communication system parameters used by the transmitting end is selected, the preamble signal and the data frame are formed into a signal frame and then sent to the receiving end, and then the receiving end stores the communication system parameters from itself according to the preamble signal The corresponding communication system parameters are read from the parameter table corresponding to the preamble signal, thereby realizing the system parameters used in transmitting one or more frames of data frames by using the preamble signal. Therefore, the communication system parameter transmission scheme proposed by the embodiment of the present invention does not need to be negotiated. In addition, since the existing preamble signal is used, no additional data frame header or data frame overhead is required.
[0076] The following describes the implementation process of the embodiment of the present invention by taking the frame synchronization sequence as an example. The frame synchronization sequence consists of a pre-buffer, a pseudo-random (PN) sequence, and a post-buffer. The pre-buffer and the back-buffer are cyclic extensions of the PN sequence, and their lengths can be set according to specific conditions. The PN sequence is a pseudo-random sequence whose length is determined by the polynomial that generates the PN sequence. The frame synchronization sequence is generated by selecting the initial phase of the PN sequence generator polynomial, which can be used to identify different preamble signals, thus corresponding to different communication system parameters.
[0077] The length of the PN sequence in the frame synchronization sequence determines its spreading capability. The PN sequence has strong anti-interference ability, even under low signal-to-noise ratio or strong interference, it still has a high output value when performing correlation despreading at the receiving end, that is, it has a high correlation peak. .
[0078] During the synchronization process at the receiving end, the sliding correlation method or other methods are used to identify the two correlation peaks of the two adjacent frame synchronization sequences after despreading, and the distance between the two correlation peaks is the phase of the two frame synchronization sequences. Difference. This phase difference has 2 for the m-order PN sequence generator polynomial m-1 possibility, and 2 m-1 A possibility can correspond to 2 m-1 A parameter combination of a communication system. Through this corresponding manner, while the communication system is synchronizing, the information of the system parameters can be transmitted to the receiving end.
[0079] Figure 10 This is a schematic flowchart of a sending end sending communication system parameters in an embodiment of the present invention. see Figure 10 , the process includes the following steps:
[0080] Step 101, the transmitting end selects the frame synchronization sequence corresponding to the communication system parameter as the preamble signal.
[0081] It should be noted that the frame synchronization sequence pre-configured by both the sender and the receiver has the same corresponding relationship with the communication system parameters, so as to ensure that the receiver can correctly obtain the communication system parameters according to the frame synchronization sequence.
[0082] Step 102, the transmitting end combines the preamble signal and the data frame to form a signal frame.
[0083] Figure 11 This is a schematic diagram of framing at the transmitting end in the embodiment of the present invention. like Figure 11 As shown, the transmitting end divides the selected preamble signal and data into a signal frame, and the formed signal frame is as follows Figure 7 shown.
[0084]Step 103, the sending end sends the framed signal frame.
[0085] The above process will be specifically described below for two cases where n data frames share one preamble signal and each data frame uses one preamble signal.
[0086] In the case where n data frames share a preamble signal, the preamble signal is selected using two frame synchronization sequences, and the two frame synchronization sequences use different or the same PN sequence. In other words, the two PN sequences are generated by the same generator polynomial , but can have different initial phases or the same initial phase.
[0087] In this case, the composition of the signal frame structure is as follows Figure 12 As shown, the preamble signal includes frame synchronization sequence 1 and frame synchronization sequence 2, followed by n data frames corresponding to the preamble signal.
[0088] In the case of using one preamble signal for each data frame, the preamble signal is selected to use one frame synchronization sequence, and the frame synchronization sequence before the data frame adopts different or the same PN sequence. In other words, the PN sequence before each data frame is composed of the same A generator polynomial is generated, but can have different initial phases or the same initial phase.
[0089] In this case, the composition of the signal frame structure is as follows Figure 12 shown. The preamble signal corresponding to data frame 1 includes frame synchronization sequence 1, the preamble signal corresponding to data frame 2 includes frame synchronization sequence 2, . . . , and the preamble signal corresponding to data frame n includes frame synchronization sequence n.
[0090] The PN sequence is a pseudo-random coding sequence obtained by the spread spectrum coding method. The most commonly used PN sequence can use the maximum length linear feedback shift register sequence, that is, the m sequence, which can be generated by the shift register. The initial state of the shift register that generates the PN sequence can be set, and different initial states can generate different PN sequences, so different initial state settings can be used to generate different PN sequences.
[0091] The frame synchronization sequence 1 in the embodiment of the present invention may be formed by using a PN sequence generated by any initial phase (for example, the initial phase is 0000001), and this sequence is a basic synchronization sequence. Other frame synchronization sequences (frame synchronization sequence 2 to frame synchronization sequence n) may be generated by using the basic synchronization sequence, or may be generated by using other initial phases based on the same generator polynomial.
[0092] For example, the PN sequence of the 8th-order polynomial: p(x)=x 8 +x 6 +x 5 +x 1 , the length of the PN sequence is 255, and its generation is as follows Figure 14 shown. exist Figure 14 In the method shown in , after setting the initial state, a PN sequence with a length of 255 can be generated by shifting the D flip-flop 255 times, and this PN sequence can be used to form a frame synchronization sequence.
[0093] The process of receiving communication system parameters at the receiving end is described below. Figure 15 It is a schematic flow chart of receiving communication system parameters at the receiving end. see Figure 15 , the process includes the following steps:
[0094] Step 201, the receiving end receives the signal frame sent by the transmitting end.
[0095] Step 202, the receiving end identifies a frame synchronization sequence serving as a preamble signal in the signal frame. In this embodiment, a sliding correlation method or other methods may be used to find and identify the frame synchronization sequence in the signal frame.
[0096] Step 203: After identifying the frame synchronization sequence in the signal frame, the receiving end reads the corresponding communication system parameters from the parameter table storing the correspondence between the communication system parameters and the frame synchronization sequence according to the frame synchronization sequence.
[0097] Corresponding to the transmitting end, the above process will be specifically described below for two cases where n data frames share one preamble signal and each data frame uses one preamble signal.
[0098] In the case where n data frames share one preamble signal, the above-mentioned step of reading the corresponding communication system parameters from the parameter table according to the frame synchronization sequence includes: detecting the correlation peaks of the two frame synchronization sequences in the signal frame, and calculating the two frames. The distances between the correlation peaks of the synchronization sequences are synchronized, and then the corresponding communication system parameters are read from the parameter table according to the distances.
[0099] In the case where each data frame uses a preamble signal, the above-mentioned step of reading the corresponding communication system parameters from the parameter table according to the frame synchronization sequence includes: detecting the correlation peak of the frame synchronization sequence in the signal frame, and calculating the correlation peak with the preamble. The distance between the correlation peaks of the frame synchronization sequence in a signal frame, and then the corresponding communication system parameters are read from the parameter table according to the distance.
[0100] In these two cases, the corresponding relationship in the parameter table is specifically the corresponding relationship between the distance between the two correlation peaks and the parameters of the communication system.
[0101] For example, after adopting different initial states for a PN sequence of an 8th-order polynomial, the phase difference between the two sequences is a value between 0 and 127. The transmitting end and the receiving end predefine the 128 possibilities to correspond to a combination of system parameters, for example, phase 0 corresponds to 64QAM and 1/2 FEC encoding. Through this processing method, when the system performs operations such as synchronization or channel estimation, the system parameters used by the data frame in the current signal frame can be determined at the same time.
[0102] The following takes the frame synchronization sequence of an 8th-order polynomial as an example to further illustrate the correspondence between the phase difference of the correlation peak of the frame synchronization sequence and the system parameters.
[0103] For the frame synchronization sequence using an 8th-order polynomial, there are 128 possibilities for the phase difference of the correlation peak of the frame synchronization sequence.
[0104] Therefore, there are 128 parameter combinations supported by this embodiment of the present invention. Table 1 is an example of the parameter table, the initial state used in generating the basic frame synchronization sequence is 0000001, and the initial state used in generating other frame synchronization sequences is shown in Table 1.
[0105] phase difference
[0106] Table 1
[0107] Figure 16 It is a schematic structural diagram of an apparatus for sending a communication system parameter by a sending end in an embodiment of the present invention.
[0108] like Figure 16 As shown, the device includes a preamble signal selection module, a framing module and a sending module.
[0109] Wherein, the preamble signal selection unit is used to select the autocorrelation signal corresponding to the communication system parameter as the preamble signal, and provide the preamble signal to the framing module. The framing module is used to form a signal frame together with the preamble signal and the data block, and provide the signal frame to the sending module for transmission. The sending module sends a signal frame including the preamble signal and the data frame.
[0110] When the autocorrelation signal is a frame synchronization sequence, the preamble signal selection module may include a judgment module and a selection module, wherein the judgment module is used for judging whether a plurality of data frames share a preamble signal or each data frame uses a preamble signal, and The judgment result is provided to the selection module; the selection module is used to select two frame synchronization sequences as a preamble signal when multiple data frames share a preamble signal, and select a frame when each data frame uses a preamble signal The sync sequence acts as a preamble.
[0111] Figure 17 It is a device used by the receiving end to receive communication system parameters in the embodiment of the present invention. like Figure 17 As shown, the device includes a receiving module, an identifying module, a searching module, and a storage module storing the above-mentioned parameter table.
[0112] Wherein, the receiving module is used for receiving the signal frame from the transmitting end, and providing the received signal frame to the identifying module. The identification module is used to identify the autocorrelation signal as the preamble signal in the signal frame, and then provide the relevant information to the search module. The search module is used for reading the corresponding communication system parameters from the parameter table saved by the storage module according to the autocorrelation signal from the identification module.
[0113] As mentioned above, when the autocorrelation signal is a frame synchronization sequence, a correlator may be used as an identification module, and the correlator may use a sliding correlation method or other methods to identify the frame synchronization sequence.
[0114] When the autocorrelation signal is a frame synchronization sequence, the apparatus for receiving the communication system parameters at the receiving end may have the following Figure 18 shown structure. The identification module is a correlator, and the search module specifically includes a peak detector, a peak position memory, a distance calculator and a table lookup unit.
[0115] Among them, the frame synchronization sequence correlation peak and its position are stored in the peak position memory. The peak detector is used to detect the correlation peak of the synchronization sequence in the signal frame, save the currently detected correlation peak to the peak position memory and provide it to the distance calculator. The distance calculator is configured to calculate the distance between the two frame synchronization sequence correlation peaks according to the currently detected correlation peak and the previous correlation peak stored in the peak position memory, and provide the distance to the table lookup unit. The table lookup unit is used for reading the corresponding communication system parameters from the parameter table according to the distance.
[0116] Specifically, when multiple data frames share a preamble signal, the peak detector is used to detect the correlation peaks of the two frame synchronization sequences in the signal frame, and then save the correlation peaks into the peak position memory and provide Give the distance calculator. The distance calculator calculates the distance between the correlation peaks of the two frame synchronization sequences according to the two correlation peaks provided by the peak detector, and provides the distance to the table look-up unit. The table lookup unit is used for reading the corresponding communication system parameters from the parameter table according to the distance.
[0117] In the case of one preamble per data frame, a peak detector is used to detect the correlation peak of the frame synchronization sequence in the signal frame, store the correlation peak in the peak position memory and provide it to the distance calculator. The distance calculator calculates the distance between the correlation peak and the correlation peak of the frame synchronization sequence in the previous signal frame according to the correlation peak provided by the peak detector and the information of the correlation peak of the frame synchronization sequence in the previous signal frame stored in the peak position memory, And provide this distance to the table lookup unit. The table lookup unit is used for reading the corresponding communication system parameters from the parameter table according to the distance.
[0118] In both cases, the corresponding relationship in the parameter table is specifically the corresponding relationship between the distance between the two correlation peaks and the parameters of the communication system.
[0119] The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.
