Patent Publication Number: US-2017366299-A1

Title: Data Packet Processing Method and Apparatus in OFDMA System, and Storage Medium

Description:
TECHNICAL FIELD 
     The present invention relates to a data packet transmission technology in an Orthogonal Frequency Division Multiple Access (OFDMA) system, in particular to a data packet processing method and apparatus in an OFDMA system, and a storage medium. 
     BACKGROUND 
     The OFDMA technology is one of key technologies in a fourth generation mobile communication Long Term Evolution (LTE) system and can combine with a space-time coding technology, inter-symbol interference and inter-channel interference suppression technologies and a smart antenna technology to improve system performance to an utmost extent and improve communication throughput. In the fourth generation mobile communication LTE system, a multicarrier OFDMA technology is used in downlink communication, and a Single-Carrier Frequency Division Multiple Access (SC-FDMA) technology is used in uplink communication. 
     All subcarriers in OFDMA are orthogonal to each other, each subcarrier has an integral number of carrier periods in time of one symbol, a spectrum null of each carrier is overlapped with a spectrum null of an adjacent carrier, and thereby there is no interference between subcarriers. In addition, since carriers are partially overlapped, the spectrum utilization rate is greatly improved. Cyclic prefixes are filled into OFDMA symbol guard intervals to guarantee that the number of waveform periods contained in a delay copy of OFDMA symbols in a Fast Fourier Transform (FFT) period is also an integer. Thereby, signals whose delays are smaller than guard intervals would not produce Inter-symbol interference (ISI) and Inter-channel interference (ICI) in a demodulation process. In addition, a main advantage of the OFDMA system is that orthogonal subcarriers can realize modulation and demodulation by using Fast Fourier Transform (FFT/IFFT), thereby computation complexity can be obviously decreased and hardware realization is simple. 
     In a digital communication system, generally channel error correction coding needs to be performed on information data to improve reliability of data in a channel transmission process. Channel error correction coding which is more frequently used currently includes Turbo coding, LDPC coding, convolutional coding, RS coding, BCH coding, etc. Herein a binary Turbo code in an LTE system is a parallel concatenated code having an internal interleaver and generally is formed by two Recursive Systematic Convolutional (RSC) component code coders which have the same structure and are concatenated in parallel. The interleaver in the Turbo code performs random permutation on bit positions in an input binary information sequence before a second component code coder. When the interleaver is sufficiently large, the Turbo code has a characteristic similar to a random long code. 
     A Low Density Parity Check Code (LDPC) is a linear block code based on a sparse check matrix, and low-complexity coding and decoding can be realized by using sparsity of a check matrix thereof. Since LDPC codes are simple to decode and a throughput is comparatively high, they are used in microwave communication or local area network communication. 
     A convolutional code is also a comparatively common forward error correction code. A feature of the convolutional code is that, when coding is performed on input information at a certain moment, it is not only related to an input at a current moment, but also is related to inputs at multiple moments before the current moment, i.e., generation of a code word totally is restricted by information at multiple input moments. An RS code is a special non-binary Broadcast Channel (BCH) code having a very strong error correction capability, RS coding is a shortest distance maximization coding method, and decoding methods for RS coding and BCH coding generally uses hard decision decoding. 
     In a channel error correction coded block, generally a CRC sequence is used to perform error detection, CRC is an abbreviation of Cyclic Redundancy Check and generally is redundant information added to an information block before error correction coding. A CRC working method involves steps that redundant information is generated at a sending end, the redundant information is added behind an information bit and is jointly sent to a receiving end, and after the receiving end receives the information, whether the information block is correct is checked according to the same algorithm. 
     In a digital communication system, generally a source information block is comparatively large and needs to be segmented into smaller information blocks through code block segmentation, and then channel coding is performed on these smaller information blocks. Reasons for doing this are that, if a code length is long, a decoder for an error correction code would be very complex, delay would be comparatively great, and it is quite difficult to design an error correction code with a code length which changes in a large range because generally a length of a source information block changes and is not fixed. For an error correction code, the longer the code length is, the better the performance is, but the higher the complexity is. In addition, in an existing OFDMA system, the length of some error correction codes is comparatively great. For example, in an LTE system, the length may reach 6144 bits. As a result, a problem of comparatively great decoding delay of error correction codes is caused and the complexity is comparatively high. 
     In addition, an OFDMA system is very sensitive to phase noise and carrier frequency offset, this is a disadvantage of OFDMA technology. The entire OFDMA system has a particularly strict requirement on orthogonality between subcarriers, and any small carrier frequency offset would destroy orthogonality between subcarriers and cause ICI, and phase noise would also cause rotation and diffusion of code element constellation points to produce ICI. These influences would all decrease system communication reliability. Moreover, when an OFDMA communication system is under a fading channel, channels of different error correction code blocks in one OFDM symbol are caused to be different, and packet error performance of a final data packet would be caused to be decreased. Therefore, a processing method is urgently needed to improve data transmission reliability and system communication robustness and decrease decoding delay of an OFDMA system under a fading channel. 
     It is a pity that there is no related technology for reference currently. 
     SUMMARY 
     In order to solve the above-mentioned problem, embodiments of the present invention provide a data packet processing method and apparatus in an OFDMA system, and a storage medium. 
     The technical solution of the present invention is implemented as follows. 
     A data packet processing method in an Orthogonal Frequency Division Multiple Access (OFDMA) system, applied to a sending end, includes: 
     performing code block segmentation on a source data packet to be transmitted to obtain d data blocks; 
     respectively adding a Cyclic Redundancy Check, CRC, sequence to each data block of the d data blocks; 
     respectively performing error correction coding on the d data blocks added with the CRC sequence; 
     grouping the d data blocks on which the error correction coding is performed to obtain a information data packets with a same length; 
     performing packet coding on the a information data packets to obtain b check data packets; 
     performing constellation mapping modulation on the a information data packets and the b check data packets to obtain a first modulation symbol sequence with a length of k1 and a second modulation symbol sequence with a length of k2, herein the first modulation symbol sequence corresponds to the a information data packets and the second modulation symbol sequence corresponds to the b check data packets; mapping the first modulation symbol sequence to K ofdm1  continuous OFDM symbols according to a time order, and mapping the second modulation symbol sequence to M ofdm2  continuous OFDM symbols according to a time order. 
     Herein, when sending the M ofdm1  OFDM symbols and the M ofdm2  OFDM symbols, a first OFDM symbol in the M ofdm1  OFDM symbols is sent prior to a first OFDM symbol in the M ofdm2  OFDM symbols. 
     Herein a is an integer greater than or equal to 2, d is an integer greater than or equal to 2, b is an integer greater than or equal to 1, k1 and k2 are both integers greater than or equal to 1, and M ofdm1  and M ofdm2  are both integers greater than or equal to 1. 
     A data packet processing method in an Orthogonal Frequency Division Multiple Access (OFDMA) system, applied to a receiving end, includes: 
     receiving M ofdm1  continuous Orthogonal Frequency Division Multiplexing, OFDM, symbols including a first modulation symbol sequence and M ofdm2  continuous OFDM symbols including a second modulation symbol sequence, herein the first modulation symbol sequence includes a information data packets and the second modulation symbol sequence includes b check data packets; and the a information data packets includes d error correction code data blocks; and using information of the d error correction code data blocks and the b check data packets to decode to obtain a source data packet. 
     Herein a is an integer greater than or equal to 2, d is an integer greater than or equal to 2, b is an integer greater than or equal to 1, and M ofdm1  and M ofdm2  are both integers greater than or equal to 1. 
     A data packet processing apparatus in an Orthogonal Frequency Division Multiple Access (OFDMA) system, applied to a sending end, includes: 
     a code block segmentation module configured to perform code block segmentation on a source data packet to be transmitted to obtain d data blocks; 
     a CRC sequence adding module configured to respectively add a Cyclic Redundancy Check CRC sequence to each data block of the d data blocks; 
     an error correction coding module configured to respectively perform error correction coding on the d data blocks added with the CRC sequence; 
     a grouping module configured to group the d data blocks on which the error correction coding is performed to obtain a information data packets with a same length; 
     a packet coding module configured to perform packet coding on the a information data packets to obtain b check data packets; 
     a constellation mapping modulation module configured to perform constellation mapping modulation to the a information data packets and the b check data packets to obtain a first modulation symbol sequence with a length of k1 and a second modulation symbol sequence with a length of k2, herein the first modulation symbol sequence corresponds to the a information data packets and the second modulation symbol sequence corresponds to the b check data packets; 
     an OFDM modulation module configured to map the first modulation symbol sequence to M ofdm1  continuous OFDM symbols according to a time order, and map the second modulation symbol sequence to M ofdm2  continuous OFDM symbols according to a time order; and a sending module configured to send the M ofdm1  OFDM symbols and the M ofdm2  OFDM symbols, herein a first OFDM symbol in the M ofdm1  OFDM symbols is sent prior to a first OFDM symbol in the M ofdm2  OFDM symbols. 
     Herein a is an integer greater than or equal to 2, d is an integer greater than or equal to 2, b is an integer greater than or equal to 1, k1 and k2 are both integers greater than or equal to 1, and M ofdm1  and M ofdm2  are both integers greater than or equal to 1. 
     A data packet processing apparatus in an Orthogonal Frequency Division Multiple Access, OFDMA, system, applied to a receiving end, includes: 
     an OFDM symbol receiving module configured to receive M ofdm1  continuous Orthogonal Frequency Division Multiplexing (OFDM) symbols including a first modulation symbol sequence and M ofdm2  continuous OFDM symbols including a second modulation symbol sequence, herein the first modulation symbol sequence includes a information data packets and the second modulation symbol sequence includes b check data packets; and the a information data packets includes d error correction code data blocks; and an error correction decoding module configured to use information of the d error correction code data blocks and the b check data packets to decode to obtain a source data packet. 
     Herein a is an integer greater than or equal to 2, d is an integer greater than or equal to 2, b is an integer greater than or equal to 1, and M ofdm1  and M ofdm2  are both integers greater than or equal to 1. 
     A storage medium stores a computer program, herein the computer program is configured to execute the above data packet processing method in the OFDMA system. 
     In the technical solution of the embodiment of the present invention, OFDMA and data packet coding technologies are combined to perform data transmission, so that the receiving end can adopt a streamline-like mode to perform demodulation decoding, the decoding speed is faster and the receiving robustness is stronger. Once an OFDM symbol is received, all error correction code blocks of a previous OFDM symbol are firstly decoded at an interval of receiving a next OFDMA symbol, thereby the decoding delay is shortened, the speed is comparatively fast and throughput is large. Besides, since data packet coding is combined, all error correction code blocks would additionally have some check data blocks by means of a packet coding method. At the sending end, these check data blocks are sent after original error correction code data blocks, thus, when the receiving end performs decoding, the original error correction code blocks can be firstly decoded and whether they are correct is judged. If all are correct, the check data blocks do not need to be decoded any longer, thereby the decoding operation is reduced, the energy consumption is reduced and the decoding speed is improved. Moreover, if the original error correction code blocks are erroneously decoded, all error correction code blocks can be decoded again through packet decoding, the performance of each error correction code block can be improved and thereby the receiving robustness is improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a schematic diagram of access of an OFDMA system according to an embodiment of the present invention. 
         FIG. 2  illustrates a schematic diagram of frequency dimension and time dimension in an OFDMA system according to an embodiment of the present invention. 
         FIG. 3  illustrates a flowchart of a data packet processing method in an OFDMA system according to embodiment one of the present invention. 
         FIG. 4  illustrates a structural schematic diagram of components of a data packet processing apparatus in an OFDMA system according to embodiment two of the present invention. 
         FIG. 5  illustrates a schematic diagram of resource allocation of an OFDMA system according to example one in embodiment one/embodiment two of the present invention. 
         FIG. 6  illustrates a schematic diagram of resource allocation of an OFDMA system according to example five in embodiment one/embodiment two of the present invention. 
         FIG. 7  illustrates a schematic diagram of resource allocation of an OFDMA system according to example five in embodiment one/embodiment two of the present invention. 
         FIG. 8  illustrates a schematic diagram of data subjected to constellation mapping modulation according to example six in embodiment one/embodiment two of the present invention. 
         FIG. 9  illustrates a schematic diagram of two-dimensional time-frequency resource allocation of an OFDMA system according to example six in embodiment one/embodiment two of the present invention. 
         FIG. 10  illustrates a schematic diagram of two-dimensional time-frequency resource allocation of an OFDMA system according to example eight in embodiment one/embodiment two of the present invention. 
         FIG. 11  illustrates a flowchart of receiving and decoding of an OFDMA system according to example nine in embodiment one of the present invention. 
         FIG. 12  illustrates a flowchart of a data packet processing method in an OFDMA system according to embodiment three of the present invention. 
         FIG. 13  illustrates a structural schematic diagram of components of receiving and decoding modules of an OFDMA system according to example nine in apparatus embodiment two of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described below in detail in combination with the embodiments and with reference to the drawings. 
     It needs to be stated that embodiments of the present invention and all features in the embodiments may be mutually combined within the protection scope of the present invention under a situation of no conflict. Besides, although logical sequences are illustrated in the flowcharts, the illustrated or described steps may be executed according to sequences different from the sequences here under certain circumstances. 
     Embodiment One 
       FIG. 3  illustrates a flowchart of a data packet processing method in an OFDMA system according to embodiment one of the present invention. As illustrated in  FIG. 3 , the data packet processing method in the OFDMA system according to the embodiment of the present invention includes steps  300 - 309 . 
     In step  300 , code block segmentation is performed on a source data packet to be transmitted to obtain d data blocks. 
     In step  301 , a CRC sequence is respectively added to each data block of the d data blocks. In step  303 , error correction coding is respectively performed on the d data blocks added with the CRC sequence. 
     In step  305 , grouping is performed to obtain a information data packets with a same length. 
     In step  306 , packet coding is performed on the a information data packets to obtain b check data packets. 
     In step  307 , constellation mapping modulation is performed on the a information data packets to obtain a first modulation symbol sequence with a length of k1 and constellation mapping modulation is performed on the b check data packets to obtain a second modulation symbol sequence with a length of k2; or constellation mapping modulation is performed on the a information data packets and the b check data packets, herein modulation symbols including the a information data packets form a first modulation symbol sequence, a length of the first modulation symbol is k1, and modulation symbols including the b check data packets form a second modulation symbol sequence, and a length of the second modulation symbol sequence is k2. 
     In step  308 , the first modulation symbol sequence is mapped to M ofdm1  continuous OFDM symbols according to a time order, and the second modulation symbol sequence is mapped to M ofdm2  continuous OFDM symbols according to a time order, herein in sending order numbers, a first OFDM symbol in the M ofdm1  OFDM symbols is sent prior to a first OFDM symbol in the M ofdm2  OFDM symbols. As illustrated in  FIG. 2 , it illustrates a resource occupation situation according to this embodiment of the present invention. 
     In step  309 , the M ofdm1  OFDM symbols and the M ofdm2  OFDM symbols are sent to a second transmission node according to sending order numbers. 
     Herein, a is an integer greater than or equal to 2, d is an integer greater than or equal to 2, b is an integer greater than or equal to 1, k1 and k2 are both integers greater than or equal to 1, and M ofdm1  and M ofdm2  are both integers greater than or equal to 1. 
     As one implementation mode, in the sending order numbers, a first OFDM symbol in the M ofdm2  OFDM symbols is a last OFMA symbol in the M ofdm1  OFDM symbols or an xth OFDM symbol after the last OFMA symbol in the M ofdm1  OFDM symbols, herein x is greater than or equal to 1. 
     As one implementation mode, after the CRC sequence is added and before error correction coding is performed, first-time filling is firstly performed, the first-time filling is to fill m1i bits to an ith data block, herein m1i is an integer greater than or equal to 0, i=0, d−1, and d is an integer greater than or equal to 2. 
     As one implementation mode, after error correction decoding is performed and before grouping is performed to obtain the a information data packets with a same length, second-time filling is performed, the second-time filling is to add m2 bits to a head or tail of an entire error correction code data block, herein the entire error correction code data block includes d error correction code blocks, d is an integer greater than or equal to 2 and m2 is an integer greater than or equal to 0. 
     As one implementation mode, for the a information packets with a same length which are obtained through grouping, the number of bits of each information data packet is k×c, herein a is an integer greater than or equal to 2, k is the number of bits of an error correction code block, k is an integer greater than or equal to 1 and c is an integer greater than or equal to 1. 
     As one implementation mode, in the step that the CRC sequence is respectively added to each data block, a length of each CRC sequence is h bits, herein h is an integer greater than or equal to 1. 
     As one implementation mode, in the step that constellation mapping modulation is performed on the a information data packets to obtain the first modulation symbol sequence with the length of k1, all bits on which constellation mapping modulation is performed do not include the bit data of the first-time filling and the second-time filling, herein a is an integer greater than or equal to 2 and k1 is an integer greater than or equal to 1. 
     As one implementation mode, in the step of performing code block segmentation on a source data packet to be transmitted to obtain d data blocks, a length of each data block depends on the following parameters: a length of the source data packet, the number of subcarriers on each OFDM symbol allocated by system and used for transmitting data from first transmission node to second transmission node, a modulation order, an error correction code rate, the number of OFDM symbols, the number of error correction code blocks in information data packet, the number of error correction code blocks born on each OFDM symbol, the number of bits of CRC sequence and the number of check data packets obtained through packet coding, herein the modulation order is the number of bits carried by a constellation mapping modulation symbol, and d is an integer greater than or equal to 1. 
     As one implementation mode, a modulation order of the first modulation symbol sequence is Mod1′ and a modulation order of the second modulation symbol sequence is Mod2′, herein Mod1′ and Mod2′ are integers from 1 to 16; or the first modulation symbol sequence includes q1 modulation symbol subsequences, a modulation order in the subsequences is the same, Modi is a modulation order used by an ith modulation symbol subsequence in the first modulation symbol sequence, and Modi is an integer from 1 to 16, i=0, 1, . . . , (q1−1). The second modulation symbol sequence includes q2 modulation symbol subsequences, a modulation order in the subsequences is the same, Modj is a modulation order used by a jth modulation symbol subsequence in the second modulation symbol sequence, and Modj is an integer from 1 to 16, and j=0, (q2−1), herein the modulation order is the number of bits carried by a constellation mapping modulation symbol, and q1 and q2 are both integers greater than or equal to 1. 
     A table of relations among the number of bits carried by constellation mapping modulation symbol, the modulation order and the modulation mode is shown in Table 1: 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Number  
                 Modu- 
                 Modu- 
                 Number  
                 Modu- 
                 Modu- 
               
               
                 of carried 
                 lation 
                 lation 
                 of carried  
                 lation 
                 lation 
               
               
                 bits 
                 order 
                 mode 
                 bits 
                 order 
                 mode 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 1 
                 1 
                 BPSK 
                 9 
                 9 
                 512QAM 
               
               
                 2 
                 2 
                 QPSK 
                 10 
                 10 
                 1024QAM 
               
               
                   
                   
                 (4QAM) 
                   
                   
                   
               
               
                 3 
                 3 
                 8PSK 
                 11 
                 11 
                 2048QAM 
               
               
                   
                   
                 (8QAM) 
                   
                   
                   
               
               
                 4 
                 4 
                 16QAM 
                 12 
                 12 
                 4096QAM 
               
               
                 5 
                 5 
                 32QAM 
                 13 
                 13 
                 8192QAM 
               
               
                 6 
                 6 
                 64QAM 
                   
                   
                   
               
               
                 7 
                 7 
                 128QAM 
                   
                   
                   
               
               
                 8 
                 8 
                 256QAM 
               
               
                   
               
            
           
         
       
     
     As one implementation mode, in the step of performing packet coding on the a information data packets to obtain b check data packets includes: using ith bits in all a information data packets to form a sequence Si with a length of a bits, and performing single parity check coding, b-multiple bit parity check coding, Hamming coding or RS coding on Si to obtain a check sequence Ti with a length of b bits; and sequentially combining jth bits of all check sequences Ti to obtain a check data packet Pj with a length of n bits. 
     The above-mentioned single parity check coding refers to that: all input a bits are considered as a sequence Si, and binary exclusive or (XOR) addition is performed on Si to obtain one check bit. 
     The above-mentioned b-multiple bit parity check coding refers to that: all input a bits are considered as a sequence Si and binary XOR addition is performed on a subset Set1 of the set Si to obtain a first check bit; binary XOR addition is performed on a subset Set2 of a new set formed by the set S and the first check bit to obtain a second check bit; binary XOR addition is performed on a subset Set3 of a new set formed by the set S, the first check bit and the second check bit to obtain a third check bit; and so on, binary XOR addition is performed on a subset Setb of a new set formed by the set S and the first b−1 check bits to obtain a bth check bit. 
     Herein, i=0, 1, . . . , n−1, n is a length of an error correction code block set, n is an integer greater than 1, j=0, 1, . . . b−1, b is an integer greater than or equal to 1 and a is an integer greater than or equal to 2. 
     As one implementation mode, the step of mapping the first modulation symbol sequence to M ofdm1  continuous OFDM symbols according to a time order includes: mapping the first modulation symbol sequence to Nsc1×M ofdm1  two-dimensional time-frequency resource according to an order of frequency first and then time, herein frequency dimension is used for identifying index numbers of subcarriers in OFDM symbols, time dimension is used for identifying index numbers of OFDM symbols, the Nsc1×M ofdm1  two-dimensional time-frequency resource is M ofdm1  continuous OFDM symbols in time dimension, which are allocated by a system and are used for transmitting data from a first transmission node to a second transmission node, and Nsc1 continuous non-reference signal subcarriers in frequency dimension of each OFDM symbol, Nsc1 is an integer greater than or equal to 1 and M ofdm1  is an integer greater than or equal to 1. 
     As one implementation mode, in the step of mapping the first modulation symbol sequence to Nsc1×M ofdm1  two-dimensional time-frequency resource according to an order of frequency first and then time, a method for mapping to Nsc1 continuous non-reference signal subcarriers of an ith OFDM symbol includes one of the following modes: 
     Mode 1: firstly interleaving Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol, and then sequentially mapping the constellation mapping modulation symbols to Nsc1 non-reference signal subcarriers of the ith OFDM symbol, or mapping Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc1 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, or firstly sequentially mapping Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol to a logical buffer memory, and then mapping data in the logical buffer memory to Nsc1 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; and 
     Mode 2: sequentially mapping Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc1 non-reference signal subcarriers of the ith OFDM symbol; 
     herein i=0, 1, . . . . M ofdm1 −1, Nsc1 is an integer greater than or equal to 1 and M ofdm1  is an integer greater than or equal to 1. 
     As one implementation mode, if d is greater than M ofdm1 , the implementation is performed according to mode 1; otherwise, the implementation is performed according to mode 2; herein d is the number of error correction code blocks, d is an integer greater than or equal to 2, and M ofdm1  is an integer greater than or equal to 1. 
     As one implementation mode, the step that of mapping second modulation symbol sequence to M ofdm2  continuous OFDM symbols according to a time order includes: mapping the second modulation symbol sequence to Nsc2×M ofdm2  two-dimensional time-frequency resource according to an order of frequency first and then time, herein frequency dimension is used for identifying index numbers of subcarriers in OFDM symbols, time dimension is used for identifying index numbers of OFDM symbols, the Nsc2×M ofdm2  two-dimensional time-frequency resource is M ofdm2  continuous OFDM symbols in time dimension, which are allocated by a system and are used for transmitting data from a first transmission node to a second transmission node, and Nsc2 continuous non-reference signal subcarriers in frequency dimension of each OFDM symbol, Nsc2 is an integer greater than or equal to 1 and M ofdm2  is an integer greater than or equal to 1. 
     As one implementation mode, in the step of mapping the second modulation symbol sequence to Nsc2×M ofdm2  two-dimensional time-frequency resource according to an order of frequency first and then time, a method for mapping to Nsc2 continuous non-reference signal subcarriers of an ith OFDM symbol includes one of the following modes: 
     mode 1: firstly interleaving Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol and then sequentially mapping the constellation mapping modulation symbols to Nsc2 non-reference signal subcarriers of the ith OFDM symbol, or mapping Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc2 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, or firstly sequentially mapping Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol to a logical buffer memory, and then mapping data in the logical buffer memory to Nsc2 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; and 
     mode 2: sequentially mapping the Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc2 non-reference signal subcarriers of the ith OFDM symbol; 
     herein i=0, M ofdm2 −1, Nsc2 is an integer greater than or equal to 1 and M ofdm2  is an integer greater than or equal to 1. 
     As one implementation mode, if (b×c) is greater than M ofdm2 , the implementation is performed according to mode 1; otherwise, the implementation is performed according to mode 2, herein b is the number of check data packets, b is an integer greater than or equal to 1, c is the number of error correction code blocks included in each information data packet, c is an integer greater than or equal to 1, and M ofdm2  is an integer greater than or equal to 1. 
     As one implementation mode, in the process of mapping the first modulation symbol sequence and the second modulation symbol sequence to OFDM symbols, a process for mapping to Nsc continuous non-reference signal subcarriers of an ith OFDM symbol includes one of the following modes: 
     mode 1: firstly interleaving Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol and then sequentially mapping the constellation mapping modulation symbols to Nsc non-reference signal subcarriers of the ith OFDM symbol, or mapping Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, or firstly sequentially mapping Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol to a logical buffer memory, and then mapping data in the logical buffer memory to Nsc non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; and 
     mode 2: sequentially mapping Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc non-reference signal subcarriers of the ith OFDM symbol; 
     herein Nsc is the number of non-reference signal subcarriers in an ith OFDM symbol allocated by a system and used for transmitting data from a first transmission node to a second transmission node, Nsc is an integer greater than or equal to 1, i=0, M ofdm1 , M ofdm  is the number of all OFDM symbols to which the first modulation symbol sequence and the second modulation symbol sequence are mapped, and M ofdm  is an integer greater than 0. 
     As one implementation mode, if (d+b×c) is greater than M ofdm , the implementation is performed according to mode 1; otherwise, the implementation is performed according to mode 2, herein d is the number of error correction code blocks, d is an integer greater than or equal to 2, b is the number of check data packets, b is an integer greater than or equal to 1, c is the number of error correction code blocks contained in each information data packet, c is an integer greater than or equal to 1, M ofdm  is the number of all OFDM symbols to which the first modulation symbol sequence and the second modulation symbol sequence are mapped, and M ofdm  is an integer greater than 0. 
     As one implementation mode, the interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through row-row and col-column block interleaving of row-input column-output or a random input-output relation table, in which row and col are both integers greater than 0. 
     As an implementation mode, a bit length of each error correction code block in the information data packet is e, e=m×Nsc1×g, herein m is the number of bits carried by each constellation mapping modulation symbol, m is an integer greater than or equal to 1, Nsc1 is the number of non-reference signal subcarriers in an ith OFDM symbol configured by a system and used for transmitting data from a first transmission node to a second transmission node, i=0, 1, . . . , M ofdm1 −1, Nsc1 is an integer greater than or equal to 1, a specific numerical value of g is 1, 2, 3, 4, 6 or 7, and M ofdm1  is the number of OFDM symbols to which the first modulation symbol sequence is mapped, M ofdm1  is an integer greater than 0. 
     In an embodiment of the present invention, at a receiving end, a data packet is received according to the following mode: 
     receiving OFDM symbols; 
     demodulating the OFDM symbols, and obtaining Nsc constellation mapping modulation symbols born on an ith OFDM symbol according to a configuration situation of subcarrier resource configured by a system and used for transmitting data from a first transmission node to a second transmission node; 
     demodulating constellation mapping, i.e., demodulating the Nsc constellation mapping modulation symbols into soft bit information; 
     performing error correction decoding, i.e., performing error correction decoding on the demodulated soft bit information; 
     removing CRC sequences, i.e., removing CRC sequences in all error correction code blocks; 
     merging data, i.e., merging all data obtained after the CRC sequences are removed to obtain the source data packet sent by the first transmission node; 
     herein i=0, 1, . . . . M ofdm −1, M ofdm  is the number of all OFDM symbols, M ofdm  is an integer greater than 1 and Nsc is an integer greater than or equal to 1. 
     As one implementation mode, the error correction decoding mode at least includes that: 
     since b×c data blocks in check data packets also belong to an error correction code word space and can also be decoded, thus the number of error correction code blocks is d+b×c; after all error correction code blocks are decoded, whether a code word is erroneous is judged according to a CRC sequence and/or error correction code word space, if it is erroneous, soft bit information of an erroneous error correction code block is saved, and if it is correct, a cumulative XOR result of all error correction code blocks which are correctly decoded is calculated; according to a judgment condition that whether first d error correction code blocks are correctly decoded or all d+b×c error correction code blocks are correctly decoded, if the judgment condition is satisfied, the process is exited; if the judgment condition is not satisfied, through a packet decoding method, soft bit information of each erroneous error correction code word is demodulated out by using soft bit information of erroneous error correction code blocks, a cumulative XOR result of correct error correction code words and an XOR relation among all code blocks in packet coding, the erroneous error correction code blocks are decoded, and then according to the judgment condition that whether first d error correction code blocks are correctly decoded or all d+b×c error correction code blocks are correctly decoded, if the judgment condition is satisfied, the process is exited; and if the judgment condition is not satisfied, the process is exited or iteration is continuously performed to perform packet decoding, herein the maximum number of iterations is MAX; 
     herein d is the number of error correction code blocks, d is an integer greater than or equal to 2, b is the number of check data packets, b is an integer greater than or equal to 1, c is the number of error correction code blocks included in each information data packet, c is an integer greater than or equal to 1 and MAX is an integer greater than 1. 
     The soft bit information of each erroneous error correction code word is demodulated out by using soft bit information of erroneous error correction code blocks, a cumulative XOR result of correct error correction code words and an XOR relation among all code blocks in packet coding, a specific expression for calculating soft bit information LLR′ err(i,j)  of a jth bit of an ith erroneous error correction code block is as follow: 
         LLR′   err(i,j)   =LLR   err(i,j) )+ k 0×sign err(i,j)   ×MS   err(i,j)   ×C   crt(j)  
 
     herein parameter LLR err(i,j)  is saved soft bit information of a jth bit of an ith erroneous error correction code block, parameter k0 is a real number greater than 0, sign err(i,j)  is sign-bit cumulative result of soft bit information of jth bits of all other erroneous error correction code blocks except the ith erroneous error correction code block, MS err(i,j)  is an amplitude result provided by soft bit information of jth bits of all other erroneous error correction code blocks (here a minimum algorithm is used), C crt(j)  is a sign-bit cumulative result of soft bit information of jth bits of all correct error correction code blocks, and specific expressions are as follows: 
       sign err(i,j) =sign( LLR   err(0,j) )× . . . ×sign( LLR   err(i−1,j) )×sign( LLR   err(i+1,j) )× . . . ×sign( LLR   err(enum,j) )
 
         MS   err(i,j) =min(abs( LLR   err(0,j) ), . . . ,abs( LLR   err(i−1,j) ),abs( LLR   err(i+1,j) ), . . . ,abs( LLR   err(enum,j) ) 
         C   crt(j) =sign( LLR   crt(0,j) )×sign( LLR   crt(1,j) )× . . . ×sign( LLR   crt(cnum,j) ).
 
     As one implementation mode, Turbo coding, convolutional coding, LDPC coding, RS coding, Hamming coding, product coding or BCH coding is used as an error correction coding method of the error correction code blocks. 
     The essence of the technical solution of the present invention will be further described below through specific examples. 
     Example One 
     In an OFDMA communication system, a single OFDM symbol has 1024 subcarriers, and the number of effective data subcarriers is 800. The present example is used for transmitting data from a first transmission node which is a mobile user  100  to a second transmission node which is a base station  101 , as illustrated in  FIG. 1 . A data packet processing method in an OFDMA system according to the embodiment of the present invention at least includes the following steps  301 - 309 , as illustrated in  FIG. 3 . 
     In step  300 , code block segmentation is performed on a source data packet to be transmitted with a length of 1968 bits to obtain d=6 data blocks, herein a length of each data block is 328 bits. 
     In step  301 , a CRC sequence with a length of h=8 bits is respectively added to each data block, a length of each data block added with the CRC sequence becomes 336 bits, and since the length of each data block is the same and is equal to mother code input bits which are 336 bits, first-time filling is not needed. 
     In step  303 , Turbo error correction coding is respectively performed on d=6 data blocks added with the CRC sequence, a code length of Turbo error correction coding is 672 and a code rate is 1/2. 
     In step  305 , grouping is performed to obtain a=6 information data packets with a same length, herein each information data packet has 1×672 bits, each information data packet has 1 Turbo error correction code block, and since 6 information data packets are exactly obtained through grouping and each information data packet has 1 Turbo error correction code data block, second-time filling is not needed. 
     In step  306 , packet coding is performed on a=6 information data packets to obtain b=1 check data packet, herein a length of the check data packet is 672 bits, and a single parity check coding method is used in the packet coding. 
     In step  307 , a constellation mapping modulation mode is QPSK and a modulation order is 2, constellation mapping modulation is performed on the a=6 information data packets to obtain a first modulation symbol sequence with a length of k1=2016 and constellation mapping modulation is performed on the b=1 check data packet to obtain a second modulation symbol sequence with a length of k2=336; or constellation mapping modulation is performed on the a=6 information data packets and the b=1 check data packet, herein modulation symbols including the a=6 information data packets form a first modulation symbol sequence with a length of k1=2016, and other modulation symbols form a second modulation symbol sequence with a length of k2. 
     In step  308 , the first modulation symbol sequence is mapped to M ofdm1 =6 continuous OFDM symbols according to a time order, including that: the first modulation symbol sequence is mapped to (Nsc1=336)×(M ofdm1 =6) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 5; and the second modulation symbol sequence is mapped to M ofdm2 =1 continuous OFDM symbol according to a time order, including that: the second modulation symbol sequence is mapped to (Nsc2=336)×(M ofdm2 =1) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol, i=6, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. 
     In step  309 , the mobile user  100  sends the M ofdm1 =6 OFDM symbols and the M ofdm2 =1 OFDM symbols to the base station  101  according to sending order numbers. 
     Sending order numbers of all OFDM symbols and the mapping situation of two-dimensional time-frequency resource are as specifically illustrated in  FIG. 5 , the number of subcarriers configured by a system for the mobile user  100  transmitting data to the base station  101  is 336, data of the mobile user  502  are born on 7 OFDMA symbols, the first modulation symbol sequence  500  is born on the 0th to 5th OFDM symbols and the second modulation symbol sequence  501  is born on the 6th OFDM symbol. 
     Example Two 
     Differences of example two from example one lie in that each information data packet obtained through grouping in step  305  has 2×672 bits and a modulation mode used for the second modulation symbol sequence in step  307  is 16QAM, as described as follows. 
     In step  305 , grouping is performed on data obtained after Turbo error correction coding is performed to obtain a=3 information data packets with a same length, herein each information data packet has 2×672 bits, each information data packet has 2 Turbo error correction code blocks; and in step  306 , a length of 1 check data packet obtained through packet coding is also 2×672 bits. 
     In step  307 , a length of the first modulation symbol sequence is k1=2016 constellation mapping modulation symbols, a modulation order is Mod1′=2, a constellation mapping modulation mode is QPSK, a length of the first modulation symbol sequence is k2=336 constellation mapping modulation symbols, a modulation order is Mod2′=4 and a constellation mapping modulation mode is 16QAM; or the first modulation symbol sequence includes q1=2 modulation symbol subsequences, modulation orders in the subsequences are the same, a length of a 0th modulation symbol subsequence is 1344, a modulation mode used is BPSK, a modulation order is 1, a length of a 1st modulation symbol subsequence is 672, a modulation mode used is 16QAM, a modulation order is 4, the second modulation symbol sequence includes q2=2 modulation symbol subsequence, a length of a 0th modulation symbol subsequence is 168, a modulation mode used is QPSK, a modulation order is 2, a length of a 1st modulation symbol subsequence is 168, a modulation mode used is 64QAM and a modulation order is 6. 
     Example Three 
     Differences of example three from example one lie in that the packet coding method in step  306  is a dual parity check coding method and a modulation mode used for the second modulation symbol sequence in step  307  is 16QAM, as described as follows. 
     In step  306 , packet coding is performed on a=6 information data packets to obtain b=2 check data packets, a length of the check data packet is 672 bits and the packet coding uses a dual parity check coding method as follow: the 0th check data packet P0 selects all 6 Turbo error correction code blocks to perform single parity check coding, i.e., P0=C0+C1+ . . . +C5; and the 1st check data packet P1 selects all even-number Turbo error correction code blocks to perform single parity check coding with P0, i.e., P1=C0+C2+C4+P0, herein C0-C5 are 6 Turbo error correction code blocks, thereby 2 check data blocks P0 and P1 are obtained, and lengths are respectively 672 bits. 
     In step  307 , constellation mapping modulation is performed on the a=6 information data packets to obtain a first modulation symbol sequence with a length of k1=2016, a constellation mapping modulation mode is QPSK and a modulation order is 2; and constellation mapping modulation is performed on the b=2 check data packets to obtain a second modulation symbol sequence with a length of k2=336, a constellation mapping modulation mode is 16QAM and a modulation order is 4. 
     Example Four 
     A difference of example four from example one lies in step  308  as follow. 
     In step  308 , the first modulation symbol sequence is mapped to M ofdm1 =6 continuous OFDM symbols according to a time order, including that: the first modulation symbol sequence is mapped to (Nsc1=336)×(M ofdm1 =6) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly interleaved and then are sequentially mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol; or Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=0, 1, . . . , 5. 
     In addition, the second modulation symbol sequence is mapped to M ofdm2 =1 continuous OFDM symbol according to a time order, including that: the second modulation symbol sequence is mapped to (Nsc2=336)×(M ofdm2 =1) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc2=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly interleaved and then are sequentially mapped to Nsc2=336 non-reference signal subcarriers of the ith OFDM symbol; or Nsc2=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to Nsc2=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or Nsc2=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to Nsc2=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=6. 
     Herein, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. The interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through row-row and col-column block interleaving of row-input column-output or a random input-output relation table, herein row and col are both integers greater than 0, row=21 and col=16. 
     Example Five 
     A difference of example five from example one lies in step  308  and step  309  as follows. 
     In step  308 , the first modulation symbol sequence is mapped to M ofdm1 =7 continuous OFDM symbols according to a time order, including that: the first modulation symbol sequence is mapped to (Nsc1=228)×(M ofdm1 =7) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=228 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc1=228 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 6; and the second modulation symbol sequence is mapped to M ofdm2 =7 continuous OFDM symbol according to a time order, including that: the second modulation symbol sequence is mapped to (Nsc2=48)×(M ofdm2 =7) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc2=48 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc2=48 non-reference signal subcarriers of the ith OFDM symbol, i=7, 8, . . . , 13, herein i is a sending order number and an OFDM symbol with a smaller order number is sent more early. 
     In step  309 , a sending process is that: as illustrated in  FIG. 6 , after OFDM symbols including a first modulation symbol sequence  600  are completely sent, OFDM symbols including a second modulation symbol sequence  601  are directly sent; or as illustrated in  FIG. 7 , after OFDM symbols including a first modulation symbol sequence  700  are completely sent, OFDM symbols including a second modulation symbol sequence  701  are sent after waiting for 7 OFDM symbols. 
     Example Six 
     In an OFDMA communication system, a single OFDM symbol has 1024 subcarriers and the number of effective data subcarriers is 800. The present example is used for transmitting data from a first transmission node which is a base station  101  to a second transmission node which is a mobile user  100 , as illustrated in  FIG. 1 . A method according to the present invention at least includes the following steps, as illustrated in  FIG. 3 . 
     In step  300 , code block segmentation is performed on a source data packet to be transmitted with a length of 9620 bits to obtain d=20 data blocks, herein a length of each data block is 481 bits. 
     In step  301 , a CRC sequence with a length of h=8 bits is respectively added to each data block, herein a length of each data block added with the CRC sequence becomes 489 bits. 
     In step  302 , after the CRC sequence is added, first-time filling is performed on each data block, herein the first-time filling is to fill m1i=15 bits to an ith data block, and a filled bit is ‘0’, i=0, 1, . . . , 19, such that the length of each data block reaches 504 bits. 
     In step  303 , Turbo error correction coding is respectively performed on d=20 data blocks added with the CRC sequence to obtain a data block with the total number of bits being 13440, herein a code length of Turbo error correction coding is 672 and a code rate is 3/4. 
     In step  304 , second-time filling is performed on total data blocks after Turbo error correction coding is performed, herein the second-time filling is to add m2=672 bits to a head or tail of an entire error correction code data block, and a filled bit is ‘0’. 
     In step  305 , grouping is performed to obtain a=7 information data packets with a same length, herein each information data packet has 3×672 bits. 
     In step  306 , packet coding is performed on a=7 information data packets to obtain b=1 check data packet, herein a length of the check data packet is 3×672 bits and a single parity check coding method is used in the packet coding. 
     In step  307 , a constellation mapping modulation mode is 64QAM and a modulation order is 6, constellation mapping modulation is performed on the a=7 information data packets with the number of effective bits being 20×657 (as illustrated in  FIG. 8 , bits  800  of the first-time filling and bits  803  of the second-time filling are not included) to obtain a first modulation symbol sequence with a length of k1=2190, and constellation mapping modulation is performed on the b=1 check data packet with the number of effective bits being 3×657 (as illustrated in  FIG. 8 , all bits not including 7 bits subjected to parity check coding in the packet coding method belong to results  802  of first-time filled bits and second-time filled bits) to obtain a second modulation symbol sequence (which needs to be filled with 3 bits) with a length of k2=329. 
     In step  308 , the first modulation symbol sequence and the second modulation symbol sequence are mapped to 360×7 two-dimensional time-frequency resource on 7 continuous OFDM symbols according to a time order, as illustrated in  FIG. 9 , herein 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to 360 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 6; and herein the first modulation symbol sequence is mapped to 0th to 6th OFDM symbols  900 , and the second modulation symbol sequence is mapped to a 6th OFDM symbol  901  (a last subcarrier of the 6th OFDM symbol in the two-dimensional time-frequency resource is a filled symbol  902 ), i.e., in sending order numbers, a first OFDM symbol in the M ofdm2 =1 OFDM symbol to which the second modulation symbol sequence is mapped is a last OFDM symbol in the M ofdm1 =7 OFDM symbols to which the first modulation symbol sequence is mapped. 
     In step  309 , a base station  101  sends the 7 OFDM symbols to a mobile user  100  according to sending order numbers. 
     Example Seven 
     A difference of example seven from example six lies in step  308  as follow. 
     In step  308 , the first modulation symbol sequence and the second modulation symbol sequence are mapped to two-dimensional time-frequency resource on M ofdm1 =7 continuous OFDM symbols according to a time order, herein d is the number of Turbo code blocks (d=20), c is the number of Turbo code blocks included in each information data packet (c=3), b is the number of check data packets (b=1) and M ofdm  is the total number of needed OFDM symbols (M ofdm =7); according to a judgment condition that whether (d+b×c) is greater than M ofdm , if it is judged that the condition is satisfied at that moment, 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are interleaved firstly and then the constellation mapping modulation symbols are sequentially mapped to 360 non-reference signal subcarriers of the ith OFDM symbol; or 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to 360 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to 360 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=0, 1, . . . , 6. 
     Herein, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. The interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through row-input column-output row-row and col-column block interleaving or a random input-output relation table, herein row and col are both integers greater than 0, row=20 and col=18. 
     Example Eight 
     A difference of example eight from example six lies in step  308  as follow. 
     In step  308 , the first modulation symbol sequence is mapped to M ofdm1 =6 continuous OFDM symbols according to a time order, including that, as illustrated in  FIG. 10 , the first modulation symbol sequence is mapped to (Nsc1=365)×(M ofdm1 =6) two-dimensional time-frequency resource  1000  according to an order of frequency first and then time, herein d is the number of Turbo code blocks (d=20); and according to a judgment condition that whether d is greater than M ofdm1 , if it is judged that the condition is satisfied at that moment, Nsc1=365 constellation mapping modulation symbols mapped to an ith OFDM symbol are interleaved firstly and then the constellation mapping modulation symbols are sequentially mapped to Nsc1=365 non-reference signal subcarriers of the ith OFDM symbol; or Nsc1=365 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to Nsc1=365 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or Nsc1=365 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to Nsc1=365 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=0, 1, . . . , 5. 
     In addition, the second modulation symbol sequence is mapped to M ofdm2 =6 continuous OFDM symbols according to a time order, including that, as illustrated in  FIG. 10 , the second modulation symbol sequence is mapped to (Nsc2=55)×(M ofdm2 =6) two-dimensional time-frequency resource  1001  (the last subcarrier is a filled symbol) according to an order of frequency first and then time, herein b is the number of check data packets (b=1) and c is the number of Turbo code blocks included in each information data packet (c=3); and according to a judgment condition that whether b×c is greater than M ofdm2 , if it is judged that the condition is not satisfied at that moment, and as illustrated in  FIG. 10 , Nsc2=55 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc2=55 non-reference signal subcarriers of the ith OFDM symbol, herein i=6, 7, . . . , 11. 
     Herein, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. The interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through row-row and col-column block interleaving of row-input column-output or a random input-output relation table, herein row and col are both integers greater than 0, row=73 and col=5. 
     Example Nine 
     Example nine is applicable to a second transmission node (mobile user  100 ) in example six. As illustrated in  FIG. 11 , the following steps  1100 - 1105  are at least included. 
     In step  1100 , an ith OFDM symbol is received. 
     In step  1101 , the ith OFDM symbol is demodulated, and 360 constellation mapping modulation symbols born on the ith OFDM symbol are obtained according to a configuration of subcarrier resource configured by a system and used for transmitting to a mobile user  100 . 
     In step  1102 , constellation mapping is demodulated, a modulation mode is 64QAM and a modulation order is 6, and the 360 constellation mapping modulation symbols are demodulated into 360×6 soft bit information. 
     In step  1103 , error correction decoding is performed to decode all Turbo codes which belong to the ith OFDM symbol. 
     In step  1104 , CRC sequence removal is performed to remove CRC sequences in all Turbo code blocks. 
     In step  1105 , data merging is performed to merge all pure data obtained after CRC sequences are removed to obtain a source data packet sent by a first transmission node (base station  101 ). 
     As illustrated in  FIG. 12 , once an ith OFDM symbol is received, all error correction code blocks (Turbo code blocks) which belong to the ith OFDM symbol may be decoded, then error correction code blocks in an (i+1)th OFDM symbol are sequentially decoded, and thus by using a streamline-link mode, the decoding speed can be improved, herein i=0, 1, 2, . . . , 6. 
     Since 3 data blocks in the check data packet also belong to a Turbo code word space and can also be decoded, and the number of Turbo code blocks is 23; after all Turbo code blocks are decoded, whether a code word is erroneous is judged according to a CRC sequence and/or Turbo code word space, if it is erroneous, soft bit information of a Turbo correction code block is saved, and if it is correct, a cumulative XOR result C of all correct Turbo code blocks is calculated, C=C⊕C 1 ; according to a judgment condition that whether first 20 Turbo code blocks are correctly decoded or all 23 Turbo code blocks are correctly decoded, if the judgment condition is satisfied, the process is exited; if the judgment condition is not satisfied, through a packet decoding method, soft bit information of each erroneous Turbo code word is demodulated out by using soft bit information of erroneous Turbo code blocks, a cumulative XOR result of correct Turbo code words and an XOR relation among all code blocks in packet coding, the erroneous Turbo code blocks are decoded, and then according to the judgment condition that whether first 20 Turbo code blocks are correctly decoded or all 23 Turbo code blocks are correctly decoded, if the judgment condition is satisfied, the process is exited; and if the judgment condition is not satisfied, the process is exited or iteration is continuously performed to perform packet decoding, herein a maximum number of iterations is 5. 
     Example Ten 
     In an OFDMA communication system, a single OFDM symbol has 1024 subcarriers and the number of effective data subcarriers is 800. The present example is used for transmitting data from a first transmission node which is a base station  101  to a second transmission node which is a mobile user  100 , as illustrated in  FIG. 1 , herein the number of OFDM symbols is M ofdm =6, the number of subcarriers on each OFDM symbol allocated by a system and used for transmitting data from the first transmission node to the second transmission node is Nsc=512, a modulation order is Mu=4, an error correction code rate is R=1/2, the number of error correction code blocks in each information data packet is c=1, the number of error correction code blocks born on each OFDM symbol is k0=1, the number of bits of a CRC sequence is h=8 and the number of check data packets obtained through packet coding is b=1. A method according to the present invention at least includes the following steps, as illustrated in  FIG. 3 . 
     In step  300 , according to the following parameters: a length L=5080 of a source data packet, the number of subcarriers Nsc=512 on each OFDM symbol allocated by a system and used for transmitting data from the first transmission node to the second transmission node, a modulation order Mu=4, an error correction code rate R=1/2, the number M ofdm =6 of OFDM symbols, the number c=1 of error correction code blocks in each information data packet, the number of error correction code blocks k0=1 born on each OFDM symbol, the number of bits h=8 of each CRC sequence and the number of check data packets b=1 obtained through packet coding, calculation is performed to obtain the number of data blocks d=M ofdm ×k0−b×c=5, herein the size of each data block is L/d=1016, and code block segmentation is performed on the source data packet to be transmitted with the length of L=5080 bits to obtain d=5 data blocks, herein a length of each data block is 1016 bits. 
     In step  301 , a CRC sequence with a length of h=8 bits is respectively added to each data block, herein a length of each data block added with the CRC sequence becomes 1024 bits. 
     In step  302 , after the CRC sequence is added, first-time filling is performed on each data block, herein the first-time filling is to fill m1i=0 bits to an ith data block, and a filled bit is ‘0’, i=0, 1, . . . , 4, such that the length of each data block reaches 1024 bits. 
     In step  303 , Turbo error correction coding is respectively performed on d=5 data blocks added with the CRC sequence to obtain a data block with the total number of bits being 10240. 
     In step  304 , second-time filling is performed after Turbo error correction coding is performed, herein the second-time filling is to add m2=0 bits to a head or tail of an entire error correction code data block, and a filled bit is ‘0’. 
     In step  305 , grouping is performed to obtain a=5 information data packets with a same length, herein each information data packet has 2048 bits. 
     In step  306 , packet coding is performed on a=5 information data packets to obtain b=1 check data packet, herein a length of the check data packet is 2048 bits and a single parity check coding method is used in the packet coding. 
     In step  307 , a constellation mapping modulation mode is 64QAM and a modulation order is 4, and constellation mapping modulation is performed on the a=5 information data packets with the number of effective bits being 10240 to obtain a first modulation symbol sequence with a length of k1=2560, and constellation mapping modulation is performed on the b=1 check data packet with the number of effective bits being 2048 to obtain a second modulation symbol sequence with a length of k2=512. 
     In step  308 , the first modulation symbol sequence and the second modulation symbol sequence are mapped to 512×6 two-dimensional time-frequency resource on 6 continuous OFDM symbols according to a time order, herein 512 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to 512 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 5; and herein the first modulation symbol sequence is mapped to 0th to 4th OFDM symbols, and the second modulation symbol sequence is mapped to the 5th OFDM symbol, herein i is a sending order number of an OFDM symbol and an OFDM symbol with a smaller sending order number is sent more early. 
     In step  309 , a base station  101  sends the 7 OFDM symbols to a mobile user  100  according to sending order numbers. 
     Example Eleven 
     A difference of example eleven from example one and example ten lies in step  303 , where the used error correction coding method is convolutional coding, LDPC coding, RS coding, Hamming coding, product coding or BCH coding. 
     Embodiment Two 
     An embodiment of the present invention provides a data packet processing apparatus in an OFDMA system, applied to a sending end, at least including a code block segmentation module, a CRC sequence adding module, an error correction coding module, a grouping module, a packet coding module, a packet coding module, a constellation mapping modulation module, an OFDM modulation module and a sending module. 
     The code block segmentation module is configured to perform code block segmentation on a source data packet to be transmitted to obtain d data blocks. 
     The CRC sequence adding module is configured to respectively add a Cyclic Redundancy Check CRC sequence to each data block. 
     The error correction coding module is configured to respectively perform error correction coding on the d data blocks added with the CRC sequence. 
     The grouping module is configured to group the data blocks on which the error correction coding is performed to obtain a information data packets with a same length. 
     The packet coding module is configured to perform packet coding on the a information data packets to obtain b check data packets. 
     The constellation mapping modulation module is configured to perform constellation mapping modulation on the a information data packets to obtain a first modulation symbol sequence with a length of k1 and perform constellation mapping modulation on the b check data packets to obtain a second modulation symbol sequence with a length of k2; or perform constellation mapping modulation on the a information data packets and the b check data packets, herein modulation symbols including the a information data packets form a first modulation symbol sequence with a length of k1, and other modulation symbols form a second modulation symbol sequence with a length of k2. 
     The OFDM modulation module is configured to map the first modulation symbol sequence to M ofdm1  continuous OFDM symbols according to a time order, and map the second modulation symbol sequence to M ofdm2  continuous OFDM symbols according to a time order, herein in sending order numbers, a first OFDM symbol in the M ofdm1  OFDM symbols is sent prior to a first OFDM symbol in the M ofdm2  OFDM symbols. 
     The sending module is configured to send the M ofdm1  OFDM symbols and the M ofdm2  OFDM symbols to a second transmission node according to the sending order numbers. 
     Herein a is an integer greater than or equal to 2, d is an integer greater than or equal to 2, b is an integer greater than or equal to 1, k1 and k2 are both integers greater than or equal to 1, and M ofdm1  and M ofdm2  are both integers greater than or equal to 1. 
     Further, in sending order numbers, a first OFDM symbol in the M ofdm2  OFDM symbols is a last OFMA symbol in the M ofdm1  OFDM symbols or an xth OFDM symbol after the last OFMA symbol in the M ofdm1  OFDM symbols, herein x is greater than or equal to 1. 
     Further, after the CRC sequence adding module and before the error correction coding module, the apparatus includes a first-time filling module, and the first-time filling module is configured to fill m1i bits to an ith data block, herein m1i is an integer greater than or equal to 0, i=0, d−1, and d is an integer greater than or equal to 2. 
     Further, after the error correction coding module and before the grouping module, the apparatus includes a second-time filling module, and the second-time filling module is configured to add m2 bits to a head or tail of an entire error correction code data block, herein the entire error correction code data block includes d error correction code blocks, d is an integer greater than or equal to 2 and m2 is an integer greater than or equal to 0. 
     Further, the grouping module is configured to perform grouping to obtain a information data packets with a same length, and the number of bits of each information data packet is k×c, herein a is an integer greater than or equal to 2, k is the number of bits of an error correction code block, k is an integer greater than or equal to 1 and c is an integer greater than or equal to 1. 
     Further, the CRC sequence adding module is configured to respectively add a CRC sequence to each data block. Herein a length of each CRC sequence is h bits, and h is an integer greater than or equal to 1. 
     Further, the constellation mapping modulation module is configured to perform constellation mapping modulation on the a information data packets to obtain a first modulation symbol sequence with a length of k1, and all bits on which constellation mapping modulation is performed do not include bit data filled by the first-time filling module and the second-time filling module, herein a is an integer greater than or equal to 2 and k1 is an integer greater than or equal to 1. 
     Further, the code block segmentation module is configured to perform code block segmentation on a source data packet to be transmitted to obtain d data blocks, herein a length of each data block depends on the following parameters: a length of a source data packet, the number of subcarriers on each OFDM symbol allocated by system and used for transmitting data from first transmission node to second transmission node, a modulation order, an error correction code rate, the number of OFDM symbols, the number of error correction code blocks in an information data packet, the number of error correction code blocks born on each OFDM symbol, the number of bits of CRC sequence and the number of check data packets obtained through packet coding, herein the modulation order is the number of bits carried by a constellation mapping modulation symbol and d is an integer greater than or equal to 2. 
     Further, a modulation order of the first modulation symbol sequence in the constellation mapping modulation module is Mod1′ and a modulation order of the second modulation symbol sequence is Mod2′, herein Mod1′ and Mod2′ are integers from 1 to 16; or the first modulation symbol sequence includes q1 modulation symbol subsequences, a modulation order in the subsequences is the same, Modi is a modulation order used by an ith modulation symbol subsequence in the first modulation symbol sequence, Modi is an integer from 1 to 16, i=0, (q1−1), the second modulation symbol sequence includes q2 modulation symbol subsequences, a modulation order in the subsequences is the same, Modj is a modulation order used by a jth modulation symbol subsequence in the second modulation symbol sequence, Modj is an integer from 1 to 16 and j=0, (q2−1), herein the modulation order is the number of bits carried by a constellation mapping modulation symbol, and q1 and q2 are both integers greater than or equal to 1. 
     A table of relations among the number of bits carried by constellation mapping modulation symbol, the modulation order and the modulation mode is as shown in Table 2: 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Number  
                 Modu- 
                 Modu- 
                 Number  
                 Modu- 
                 Modu- 
               
               
                 of carried  
                 lation 
                 lation 
                 of carried  
                 lation 
                 lation 
               
               
                 bits 
                 order 
                 mode 
                 bits 
                 order 
                 mode 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 1 
                 1 
                 BPSK 
                 9 
                 9 
                 512QAM 
               
               
                 2 
                 2 
                 QPSK 
                 10 
                 10 
                 1024QAM 
               
               
                   
                   
                 (4QAM) 
                   
                   
                   
               
               
                 3 
                 3 
                 8PSK 
                 11 
                 11 
                 2048QAM 
               
               
                   
                   
                 (8QAM) 
                   
                   
                   
               
               
                 4 
                 4 
                 16QAM 
                 12 
                 12 
                 4096QAM 
               
               
                 5 
                 5 
                 32QAM 
                 13 
                 13 
                 8192QAM 
               
               
                 6 
                 6 
                 64QAM 
                   
                   
                   
               
               
                 7 
                 7 
                 128QAM 
                   
                   
                   
               
               
                 8 
                 8 
                 256QAM 
               
               
                   
               
            
           
         
       
     
     Further, the packet coding module is configured to perform packet coding on the a information data packets to obtain b check data packet, including: using ith bits in all a information data packets to form a sequence Si with a length of a bits, and performing single parity check coding, b-multiple bit parity check coding, Hamming coding or RS coding to Si to obtain a check sequence Ti with a length of b bits; and sequentially combining jth bits of all check sequences Ti to obtain a check data packet Pj with a length of n bits; 
     herein i=0, 1, . . . , n−1, n is a length of an error correction code block set, n is an integer greater than 1, j=0, 1, . . . , b−1, b is an integer greater than or equal to 1, and a is an integer greater than or equal to 2. 
     Further, in the OFDM symbol modulation module, the first modulation symbol sequence is mapped to M ofdm1  continuous OFDM symbols, including: mapping the first modulation symbol sequence to Nsc1×M ofdm1  two-dimensional time-frequency resource according to an order of frequency first and then time, herein frequency dimension is used for identifying index numbers of subcarriers in OFDM symbols and time dimension is used for identifying index numbers of OFDM symbols, the Nsc1×M ofdm1  two-dimensional time-frequency resource is M ofdm1  continuous OFDM symbols in time dimension, which are allocated by a system and are used for transmitting data from a first transmission node to a second transmission node, and Nsc1 continuous non-reference signal subcarriers in frequency dimension of each OFDM symbol, Nsc1 is an integer greater than or equal to 1 and M ofdm1  is an integer greater than or equal to 1. 
     Further, mapping the first modulation symbol sequence to Nsc1×M ofdm1  two-dimensional time-frequency resource according to an order of frequency first and then time, a method for mapping to Nsc1 continuous non-reference signal subcarriers of an ith OFDM symbol includes one of the following modes: 
     mode 1: firstly interleaving Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol and then sequentially mapping the constellation mapping modulation symbols to Nsc1 non-reference signal subcarriers of the ith OFDM symbol, or mapping Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc1 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, or firstly sequentially mapping Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol to a logical buffer memory, and then mapping data in the logical buffer memory to Nsc1 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; and 
     mode 2: sequentially mapping Nsc1 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc1 non-reference signal subcarriers of the ith OFDM symbol, 
     herein i=0, 1, . . . , M ofdm1 −1, Nsc1 is an integer greater than or equal to 1 and M ofdm1  is an integer greater than or equal to 1. 
     Further, if d is greater than M ofdm1 , the implementation is performed according to mode 1; otherwise, the implementation is performed according to mode 2, herein d is the number of error correction code blocks, d is an integer greater than or equal to 2, and M ofdm1  is an integer greater than or equal to 1. 
     Further, in the OFDM symbol modulation module, mapping the second modulation symbol sequence to M ofdm2  continuous OFDM symbols according to a time order includes: mapping the second modulation symbol sequence to Nsc2×M ofdm2  two-dimensional time-frequency resource according to an order of frequency first and then time, herein frequency dimension is used for identifying index numbers of subcarriers in OFDM symbols, time dimension is used for identifying index numbers of OFDM symbols, the Nsc2×M ofdm2  two-dimensional time-frequency resource is M ofdm2  continuous OFDM symbols in time dimension, which are allocated by a system and are used for transmitting data from a first transmission node to a second transmission node, and Nsc2 continuous non-reference signal subcarriers in frequency dimension of each OFDM symbol, Nsc2 is an integer greater than or equal to 1 and M ofdm2  is an integer greater than or equal to 1. 
     Further, mapping the second modulation symbol sequence to Nsc2×M ofdm2  two-dimensional time-frequency resource according to an order of frequency first and then time, a method for mapping to Nsc2 continuous non-reference signal subcarriers of an ith OFDM symbol includes one of the following modes: 
     mode 1: firstly interleaving Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol and then sequentially mapping the constellation mapping modulation symbols to Nsc2 non-reference signal subcarriers of the ith OFDM symbol, or mapping Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc2 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, or firstly sequentially mapping Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol to a logical buffer memory, and then mapping data in the logical buffer memory to Nsc2 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; and 
     mode 2: sequentially mapping Nsc2 constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc2 non-reference signal subcarriers of the ith OFDM symbol, 
     herein i=0, M ofdm2 −1, Nsc2 is an integer greater than or equal to 1 and M ofdm2  is an integer greater than or equal to 1. 
     Further, if (b×c) is greater than M ofdm2 , the implementation is performed according to mode 1; otherwise, the implementation is performed according to mode 2, herein b is the number of check data packets, b is an integer greater than or equal to 1, c is the number of error correction code blocks contained in each information data packet, c is an integer greater than or equal to 1, and M ofdm2  is an integer greater than or equal to 1. 
     Further, in the OFDM symbol modulation module, in the process of mapping the first modulation symbol sequence and the second modulation symbol sequence to OFDM symbols, mapping to Nsc continuous non-reference signal subcarriers of an ith OFDM symbol includes one of the following modes: 
     mode 1: firstly interleaving Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol and then sequentially mapping the constellation mapping modulation symbols to Nsc non-reference signal subcarriers of the ith OFDM symbol, or mapping Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, or firstly sequentially mapping Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol to a logical buffer memory, and then mapping data in the logical buffer memory to Nsc non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; and 
     mode 2: sequentially mapping Nsc constellation mapping modulation symbols mapped to an ith OFDM symbol to Nsc non-reference signal subcarriers of the ith OFDM symbol; 
     herein Nsc is the number of non-reference signal subcarriers in an ith OFDM symbol allocated by a system and used for transmitting data from a first transmission node to a second transmission node, Nsc is an integer greater than or equal to 1, i=0, 1, . . . , M ofdm1 , M ofdm  is the number of all OFDM symbols to which the first modulation symbol sequence and the second modulation symbol sequence are mapped, and M ofdm  is an integer greater than 0. 
     Further, if (d+b×c) is greater than M ofdm , the implementation is performed according to mode 1; otherwise, the implementation is performed according to mode 2, herein d is the number of error correction code blocks, d is an integer greater than or equal to 2, b is the number of check data packets, b is an integer greater than or equal to 1, c is the number of error correction code blocks contained in each information data packet, c is an integer greater than or equal to 1, M ofdm  is the number of all OFDM symbols to which the first modulation symbol sequence and the second modulation symbol sequence are mapped, and M ofdm  is an integer greater than 0. 
     Further, the interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through row-row and col-column block interleaving of row-input column-output or a random input-output relation table, herein row and col are both integers greater than 0. 
     Further, a bit length of each error correction code block in the information data packet is e, e=m×Nsc1×g, herein m is the number of bits carried by each constellation mapping modulation symbol, m is an integer greater than or equal to 1, Nsc1 is the number of non-reference signal subcarriers in an ith OFDM symbol configured by a system and used for transmitting data from a first transmission node to a second transmission node, i=0, M ofdm1 −1, Nsc1 is an integer greater than or equal to 1, a specific numerical value of g is 1, 2, 3, 4, 6 or 7, M ofdm1  is the number of OFDM symbols to which the first modulation symbol sequence is mapped, and M ofdm1  is an integer greater than 0. 
     An embodiment of the present invention further provides another data packet processing apparatus in an OFDMA system, applied to a receiving end, at least including an OFDM symbol receiving module, an OFDM symbol demodulation module, a constellation mapping demodulation module, an error correction decoding module, a CRC sequence removal module, a data merging module. 
     The OFDM symbol receiving module is configured to receive OFDM symbols. 
     The OFDM symbol demodulation module is configured to obtain Nsc constellation mapping modulation symbols born on an ith OFDM symbol according to a configuration situation of subcarrier resource configured by a system and used for transmitting data from a first transmission node to a second transmission node. 
     The constellation mapping demodulation module is configured to demodulate the Nsc constellation mapping modulation symbols into soft bit information. 
     The error correction decoding module is configured to perform error correction decoding on the demodulated soft bit information. 
     The CRC sequence removal module is configured to remove CRC sequences in all error correction code blocks. 
     The data merging module is configured to merge all data after the CRC sequences are removed to obtain a source data packet sent by the first transmission node. 
     Herein i=0, 1, . . . , M ofdm −1, M ofdm  is the number of all OFDM symbols, M ofdm  is an integer greater than 1 and Nsc is an integer greater than or equal to 1. 
     Further, the error correction decoding module at least configured to: 
     since b×c data blocks in check data packets also belong to an error correction code word space and can also be decoded, the number of error correction code blocks is d+b×c, after all error correction code blocks are decoded, judge whether a code word is erroneous according to a CRC sequence and/or error correction code word space, if it is erroneous, save soft bit information of an erroneous error correction code block, and if it is correct, calculate a cumulative XOR result of all error correction code blocks which are correctly decoded; according to a judgment condition that whether first d error correction code blocks are correctly decoded or all d+b×c error correction code blocks are correctly decoded, if the judgment condition is satisfied, exist the process; if the judgment condition is not satisfied, through a packet decoding method, demodulate out soft bit information of each erroneous error correction code word by using soft bit information of erroneous error correction code blocks, a cumulative XOR result of correct error correction code words and an XOR relation among all code blocks in packet coding, and decode the erroneous error correction code blocks, and then according to the judgment condition that whether first d error correction code blocks are correctly decoded or all d+b×c error correction code blocks are correctly decoded, if the judgment condition is satisfied, exist the process; and if the judgment condition is not satisfied, exist the process exits or continuously perform iteration to perform packet decoding, herein a maximum number of iterations is MAX. 
     Herein d is the number of error correction code blocks, d is an integer greater than or equal to 2, b is the number of check data packets, b is an integer greater than or equal to 1, c is the number of error correction code blocks contained in each information data packet, c is an integer greater than or equal to 1 and MAX is an integer greater than 1. 
     For demodulating out soft bit information of each erroneous error correction code word by using soft bit information of erroneous error correction code blocks, a cumulative XOR result of correct error correction code words and an XOR relation among all code blocks in packet coding, a specific expression for calculating soft bit information LLR′ err(i,j)  of a jth bit of an ith erroneous error correction code block is as follow: 
         LLR′   err(i,j)   =LLR   err(i,j)   +k 0×sign err(i,j)   ×MS   crt(i,j) )× C   crt(j)  
 
     herein parameter LLR err(i,j)  is saved soft bit information of a jth bit of an ith erroneous error correction code block, parameter k0 is a real number greater than 0, sign err(i,j)  is sign-bit cumulative result of soft bit information of jth bits of all other erroneous error correction code blocks except the ith erroneous error correction code block, MS err(i,j)  is an amplitude result provided by soft bit information of jth bits of all other erroneous error correction code blocks (here a minimum value algorithm is used), C crt(j)  is a sign-bit cumulative result of soft bit information of jth bits of all correct error correction code blocks, and specific expressions are as follows: 
       sign err(i,j) =sign( LLR   err(0,j) )× . . . ×sign( LLR   err(i−1,j) )×sign( LLR   err(i+1,j) )× . . . ×sign( LLR   err(enum,j) )
 
         MS   err(i,j) =min(abs( LLR   err(0,j) ), . . . ,abs( LLR   err(i−1,j) ),abs( LLR   err(i+1,j) ), . . . ,abs( LLR   err(enum,j) ) 
         C   crt(j) =sign( LLR   crt(0,j) )×sign( LLR   crt(1,j) )× . . . ×sign( LLR   crt(cnum,j) ).
 
     Further, Turbo coding, convolutional coding, LDPC coding, RS coding, Hamming coding, product coding or BCH coding is used as an error correction coding method of the error correction code blocks. 
     The technical solution of the present invention will be further described below through specific examples. 
     Example One 
     In an OFDMA communication system, a single OFDM symbol has 1024 subcarriers and the number of effective data subcarriers is 800. The present example is used for transmitting data from a first transmission node which is a mobile user  100  to a second transmission node which is a base station  101 , as illustrated in  FIG. 1 .  FIG. 4  illustrates a structural schematic diagram of components of a data packet processing apparatus in an OFDMA system according to embodiment two of the present invention. As illustrated in  FIG. 4 , the data packet processing apparatus in the OFDMA system according to an embodiment of the present invention includes a code block segmentation module  400 , a CRC sequence adding module  401 , an error correction coding module  403 , a grouping module  405 , a packet coding module  406 , a constellation mapping modulation module  407 , an OFDM modulation module  408  and a sending module  409 . 
     The code block segmentation module  400  is configured to perform code block segmentation on a source data packet to be transmitted with a length of 1968 bits to obtain d=6 data blocks, herein a length of each data block is 328 bits. 
     The CRC sequence adding module  401  is configured to respectively add a CRC sequence with a length of h=8 bits to each data block, herein a length of each data block added with the CRC sequence becomes 336 bits, and since the length of each data block is the same and is equal to mother code input bits which are 336 bits, first-time filling is not needed. 
     The error correction coding module  403  is configured to respectively perform Turbo error correction coding on d=6 data blocks added with the CRC sequence, herein a code length of Turbo error correction coding is 672, a code rate is 1/2, and since 6 information data packets are exactly obtained through grouping, and each information data packet has 1 Turbo error correction code data block, second-time filling is not needed. 
     The grouping module  405  is configured to perform grouping to obtain a=6 information data packets with a same length, herein each information data packet has 1×672 bits and each information data packet has 1 Turbo error correction code block. 
     The packet coding module  406  is configured to perform packet coding on a=6 information data packets to obtain b=1 check data packet, herein a length of the check data packet is 672 bits and a single parity check coding method is used in the packet coding. 
     The constellation mapping modulation module  407  is configured to, by using a constellation mapping modulation mode which is QPSK and a modulation order which is 2, perform constellation mapping modulation on the a=6 information data packets to obtain a first modulation symbol sequence with a length of k1=2016 and perform constellation mapping modulation on the b=1 check data packet to obtain a second modulation symbol sequence with a length of k2=336; or perform constellation mapping modulation on the a=6 information data packets and the b=1 check data packet, herein modulation symbols including the a=6 information data packets form a first modulation symbol sequence with a length of k1=2016, and other modulation symbols form a second modulation symbol sequence with a length of k2=336. 
     The OFDM modulation module  408  is configured to map the first modulation symbol sequence to M ofdm1 =6 continuous OFDM symbols according to a time order, which includes: mapping the first modulation symbol sequence to (Nsc1=336)×(M ofdm1 =6) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 5; and mapping the second modulation symbol sequence to M ofdm2 =1 continuous OFDM symbol according to a time order, which includes: mapping the second modulation symbol sequence to (Nsc2=336)×(M ofdm2 =1) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol, i=6, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. 
     The sending module  409  is configured to enable a mobile user  100  to send the M ofdm1 =6 OFDM symbols and the M ofdm2 =1 OFDM symbols to a base station  101  according to sending order numbers. 
     Sending order numbers of all OFDM symbols and the mapping situation of two-dimensional time-frequency resource are as specifically illustrated in  FIG. 5 , the number of subcarriers configured by a system for the mobile user  100  transmitting data to the base station  101  is 336, data of the mobile user  502  are born on 7 OFDMA symbols, the first modulation symbol sequence  500  is born on the 0th to the 5th OFDM symbols and the second modulation symbol sequence  501  is born on the 6th OFDM symbol. 
     Example Two 
     Differences of example two from example one lie in that each information data packet obtained through grouping in the grouping module  405  has 2×672 bits and a modulation mode used for the second modulation symbol sequence in the constellation mapping modulation module  407  is 16QAM, as described as follows. 
     In the grouping module  405 , grouping is performed on data obtained after Turbo error correction coding is performed to obtain a=3 information data packets with a same length, herein each information data packet has 2×672 bits, each information data packet has 2 Turbo error correction code blocks; and in the packet coding module  406 , a length of 1 check data packet obtained through packet coding is also 2×672 bits. 
     In the constellation mapping modulation module  407 , a length of the first modulation symbol sequence is k1=2016 constellation mapping modulation symbols, a modulation order is Mod1′=2, a constellation mapping modulation mode is QPSK, a length of the first modulation symbol sequence is k2=336 constellation mapping modulation symbols, a modulation order is Mod2′=4 and a constellation mapping modulation mode is 16QAM; or the first modulation symbol sequence includes q1=2 modulation symbol subsequences, modulation orders in the subsequences are same, a length of a 0th modulation symbol subsequence is 1344, a used modulation mode is BPSK, a modulation order is 1, a length of a 1st modulation symbol subsequence is 672, a used modulation mode is 16QAM, a modulation order is 4, the second modulation symbol sequence includes q2=2 modulation symbol subsequences, a length of a 0th modulation symbol subsequence is 168, a used modulation mode is QPSK, a modulation order is 2, a length of a 1st modulation symbol subsequence is 168, a used modulation mode is 64QAM and a modulation order is 6. 
     Example Three 
     Differences of example three from example one lie in that the packet coding method in the packet coding module  406  is a dual parity check coding method and a modulation mode used for the second modulation symbol sequence in the constellation mapping modulation module  407  is 16QAM, as described as follows. 
     In the packet coding module  406 , packet coding is performed on a=6 information data packets to obtain b=2 check data packets, herein a length of the check data packet is 672 bits and the packet coding uses a dual parity check coding method as follow: a 0th check data packet P0 selects all 6 Turbo error correction code blocks to perform single parity check coding, i.e., P0=C0+C1+ . . . +C5; and a 1st check data packet P1 selects all even-number Turbo error correction code blocks to perform single parity check coding with P0, i.e., P0=C0+C2+C4+P0, herein C0-C5 are 6 Turbo error correction code blocks, thereby 2 check data blocks Po and P1 are obtained, and lengths are respectively 672 bits. 
     In the constellation mapping modulation module  407 , constellation mapping modulation is performed on the a=6 information data packets to obtain a first modulation symbol sequence with a length of k1=2016, a constellation mapping modulation mode is QPSK and a modulation order is 2; and constellation mapping modulation is performed on the b=2 check data packets to obtain a second modulation symbol sequence with a length of k2=336, a constellation mapping modulation mode is 16QAM and a modulation order is 4. 
     Example Four 
     A difference of example four from example one lies in the OFDM modulation module  408  as follow. 
     In the OFDM modulation module  408 , mapping the first modulation symbol sequence to M ofdm1 =6 continuous OFDM symbols according to a time order, includes: mapping the first modulation symbol sequence to (Nsc1=336)×(M ofdm1 =6) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly interleaved and then are sequentially mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol; or Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or Nsc1=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to Nsc1=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=0, 1, . . . , 5. 
     In addition, mapping the second modulation symbol sequence to M ofdm2 =1 continuous OFDM symbol according to a time order, includes: mapping the second modulation symbol sequence to (Nsc2=336)×(M ofdm2 =1) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc2=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly interleaved and then are sequentially mapped to Nsc2=336 non-reference signal subcarriers of the ith OFDM symbol; or Nsc2=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to Nsc2=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or Nsc2=336 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to Nsc2=336 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=6. 
     Herein, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. The interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through the row-row and col-column block interleaving of the row-input column-output or a random input-output relation table, herein row and col are both integers greater than 0, row=21 and col=16. 
     Example Five 
     A difference of example five from example one lies in the OFDM modulation module  408  and the sending module  409  as follows. 
     In the OFDM modulation module  408 , mapping the first modulation symbol sequence to M ofdm1 =7 continuous OFDM symbols according to a time order, includes: mapping the first modulation symbol sequence to (Nsc1=228)×(M ofdm1 =7) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc1=228 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc1=228 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 6; and mapping the second modulation symbol sequence to M ofdm2 =7 continuous OFDM symbol according to a time order, includes: mapping the second modulation symbol sequence to (Nsc2=48)×(M ofdm2 =7) two-dimensional time-frequency resource according to an order of frequency first and then time, herein Nsc2=48 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc2=48 non-reference signal subcarriers of the ith OFDM symbol, i=7, 8, . . . , 13, herein i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. 
     In the sending module  409 , a sending process is that: as illustrated in  FIG. 6 , after OFDM symbols including a first modulation symbol sequence  600  are completely sent, OFDM symbols including a second modulation symbol sequence  601  are directly sent; or as illustrated in  FIG. 7 , after OFDM symbols including a first modulation symbol sequence  700  are completely sent, OFDM symbols including a second modulation symbol sequence  701  are sent after waiting for 7 OFDM symbols. 
     Example Six 
     In an OFDMA communication system, a single OFDM symbol has 1024 subcarriers and the number of effective data subcarriers is 800. The present example is used for transmitting data from a first transmission node which is a base station  101  to a second transmission node which is a mobile user  100 , as illustrated in  FIG. 1 . As illustrated in  FIG. 4 , a data packet processing apparatus in an OFDMA system according to an embodiment of the present invention at least includes a code block segmentation module  400 , a CRC sequence adding module  401 , a first-time filling module  402 , an error correction coding module  403 , a second-time filling module  404 , a grouping module  405 , a packet coding module  406 , a constellation mapping modulation module  407 , an OFDM modulation module  408  and a sending module  409 . 
     The code block segmentation module  400  is configured to perform code block segmentation on a source data packet to be transmitted with a length of 9620 bits to obtain d=20 data blocks, herein a length of each data block is 481 bits. 
     The CRC sequence adding module  401  is configured to respectively add a CRC sequence with a length of h=8 bits to each data block, herein a length of each data block added with the CRC sequence becomes 489 bits. 
     The first-time filling module  402  is configured to, after the CRC sequence is added, perform first-time filling on each data block, herein first-time filling is to fill m1i=15 bits to an ith data block, and a filled bit is ‘0’, i=0, 1, . . . , 19, such that the length of each data block reaches 504 bits. 
     The error correction coding module  403  is configured to respectively perform Turbo error correction coding to d=20 data blocks added with the CRC sequence to obtain a data block with the total number of bits being 13440, herein a code length of Turbo error correction coding is 672 and a code rate is 3/4. 
     The second-time filling module  404  is configured to perform second-time filling on total data blocks after Turbo error correction coding is performed, herein the second-time filling is to add m2=672 bits to a head or tail of an entire error correction code data block, and a filled bit is ‘0’. 
     The grouping module  405  is configured to perform grouping to obtain a=7 information data packets with a same length, herein each information data packet has 3×672 bits. 
     The packet coding module  406  is configured to perform packet coding on a=7 information data packets to obtain b=1 check data packet, herein a length of the check data packet is 3×672 bits and a single parity check coding method is used in the packet coding. 
     The constellation mapping modulation module  407  is configured to, by using a constellation mapping modulation mode which is 64QAM and a modulation order which is 6, perform constellation mapping modulation on the a=7 information data packets with the number of effective bits being 20×657 (as illustrated in  FIG. 8 , bits  800  of the first-time filling and bits  803  of the second-time filling are not included) to obtain a first modulation symbol sequence with a length of k1=2190, and perform constellation mapping modulation on the b=1 check data packet with the number of effective bits being 3×657 (as illustrated in  FIG. 8 , all other bits not including 7 bits subjected to parity check coding in the packet coding method belong to results  802  of first-time filled bits and second-time filled bits) to obtain a second modulation symbol sequence (which needs to be filled with 3 bits) with a length of k2=329. 
     The OFDM modulation module  408  is configured to map the first modulation symbol sequence and the second modulation symbol sequence to 360×7 two-dimensional time-frequency resource on 7 continuous OFDM symbols according to a time order, as illustrated in  FIG. 9 , herein 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to 360 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 6; and the first modulation symbol sequence is mapped to the 0th to the 6th OFDM symbols  900 , and the second modulation symbol sequence is mapped to the 6th OFDM symbol  901  (a last subcarrier of the 6th OFDM symbol in the two-dimensional time-frequency resource is a filled symbol  902 ), i.e., in sending order numbers, a first OFDM symbol in the M ofdm2 =1 OFDM symbol to which the second modulation symbol sequence is mapped is a last OFDM symbol in the M ofdm1 =7 OFDM symbols to which the first modulation symbol sequence is mapped. 
     The sending module  409  is configured to enable a base station  101  to send the 7 OFDM symbols to a mobile user  100  according to sending order numbers. 
     Example Seven 
     A difference of example seven from example six lies in the OFDM modulation module  408  as follow. 
     In the OFDM modulation module  408 , the first modulation symbol sequence and the second modulation symbol sequence are mapped to two-dimensional time-frequency resource on M ofdm =7 continuous OFDM symbols according to a time order, herein d is the number of Turbo code blocks (d=20), c is the number of Turbo code blocks contained in each information data packet (c=3), b is the number of check data packets (b=1) and M ofdm  is the total number of needed OFDM symbols (M ofdm =7); according to a judgment condition that whether (d+b×c) is greater than M ofdm , if it is judged that the condition is satisfied at this moment, 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are interleaved firstly and then the constellation mapping modulation symbols are sequentially mapped to 360 non-reference signal subcarriers of the ith OFDM symbol; or 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to 360 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or 360 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to 360 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=0, 1, . . . , 6. 
     Herein, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. The interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through the row-row and col-column block interleaving of the row-input column-output or a random input-output relation table, herein row and col are both integers greater than 0, row=20 and col=18. 
     Example Eight 
     A difference of example eight from example six lies in the OFDM modulation module  408  as follow. 
     In the OFDM modulation module  408 , mapping the first modulation symbol sequence to M ofdm1 =6 continuous OFDM symbols according to a time order includes: as illustrated in  FIG. 10 , mapping the first modulation symbol sequence to (Nsc1=365)×(M ofdm1 =6) two-dimensional time-frequency resource  1000  according to an order of frequency first and then time, herein d is the number of Turbo code blocks (d=20); and according to a judgment condition that whether d is greater than M ofdm1 , if it is judged that the condition is satisfied at this moment, Nsc1=365 constellation mapping modulation symbols mapped to an ith OFDM symbol are interleaved firstly and then the constellation mapping modulation symbols are sequentially mapped to Nsc1=365 non-reference signal subcarriers of the ith OFDM symbol; or Nsc1=365 constellation mapping modulation symbols mapped to an ith OFDM symbol are mapped to Nsc1=365 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table; or Nsc1=365 constellation mapping modulation symbols mapped to an ith OFDM symbol are firstly sequentially mapped to a logical buffer memory, and then data in the logical buffer memory are mapped to Nsc1=365 non-reference signal subcarriers of the ith OFDM symbol according to a random mapping relation table, herein i=0, 1, . . . , 5. 
     In addition, mapping the second modulation symbol sequence to M ofdm2 =6 continuous OFDM symbols according to a time order includes: as illustrated in  FIG. 10 , mapping the second modulation symbol sequence to (Nsc2=55)×(M ofdm2 =6) two-dimensional time-frequency resource  1001  (the last subcarrier is a filled symbol) according to an order of frequency first and then time, herein b is the number of check data packets (b=1) and c is the number of Turbo code blocks contained in each information data packet (c=3); and according to a judgment condition that whether b×c is greater than M ofdm2 , if it is judged that the condition is not satisfied at this moment, as illustrated in  FIG. 10 , Nsc2=55 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to Nsc2=55 non-reference signal subcarriers of the ith OFDM symbol, herein i=6, 7, . . . , 11. 
     Herein, i is a sending order number and an OFDM symbol with a smaller sending order number is sent more early. The interleaving method is row-row and col-column block interleaving of row-input column-output or random interleaving, and the random mapping relation table is an input-output relation table obtained through the row-row and col-column block interleaving of the row-input column-output or a random input-output relation table, herein row and col are both integers greater than 0, row=73 and col=5. 
     Example Nine 
     Example nine is applicable to a receiving end (mobile user  100 ) in example six. As illustrated in  FIG. 11 , an apparatus at least includes an OFDM symbol receiving module  1300 , an OFDM symbol demodulation module  1301 , a constellation mapping demodulation module  1302 , an error correction decoding module  1303 , a CRC sequence removal module  1304 , a data merging module  1305 . 
     The OFDM symbol receiving module  1300  is configured to receive an ith OFDM symbol. 
     The OFDM symbol demodulation module  1301  is configured to demodulate the ith OFDM symbol, and obtain 360 constellation mapping modulation symbols born on the ith OFDM symbol according to a configuration of subcarrier resource configured by a system and used for transmitting to a mobile user  100 . 
     The constellation mapping demodulation module  1302  is configured to demodulate the 360 constellation mapping modulation symbols into 360×6 soft bit information by using a modulation mode of 64QAM and a modulation order of 6. 
     The error correction decoding module  1303  is configured to decode all Turbo codes which belong to the ith OFDM symbol. 
     The CRC sequence removal module  1304  is configured to remove CRC sequences in all Turbo code blocks. 
     The data merging module  1305  is configured to merge all pure data obtained after CRC sequences are removed to obtain a source data packet sent by a first transmission node (base station  101 ). 
     As illustrated in  FIG. 12 , once an ith OFDM symbol is received, all error correction code blocks (Turbo code blocks) which belong to the ith OFDM symbol may be decoded, then error correction code blocks in an (i+1)th OFDM symbol are sequentially decoded, and thus by using a streamline-link mode, the decoding speed can be improved, herein i=0, 1, 2, . . . , 6. 
     Since 3 data blocks in the check data packet also belong to a Turbo code word space and can also be decoded, the number of Turbo code blocks is 23; after all Turbo code blocks are decoded, whether a code word is erroneous is judged according to a CRC sequence and/or Turbo code word space, if it is erroneous, soft bit information of a Turbo correction code block is saved, and if it is correct, a cumulative XOR result C of all correct Turbo code blocks is calculated, C=C⊕C 1 ; according to a judgment condition that whether first 20 Turbo code blocks are correctly decoded or all 23 Turbo code blocks are correctly decoded, if the judgment condition is satisfied, the process is exited; if the judgment condition is not satisfied, through a packet decoding method, soft bit information of each erroneous Turbo code word is demodulated by using soft bit information of erroneous Turbo code blocks, a cumulative XOR result of correct Turbo code words and an XOR relation among all code blocks in packet coding, the erroneous Turbo code blocks are decoded, and then according to the judgment condition that whether first 20 Turbo code blocks are correctly decoded or all 23 Turbo code blocks are correctly decoded, if the judgment condition is satisfied, the process is exited; and if the judgment condition is not satisfied, the process is exited or iteration is continuously performed to perform packet decoding, herein a maximum number of iterations is 5. 
     Example Ten 
     In an OFDMA communication system, a single OFDM symbol has 1024 subcarriers and the number of effective data subcarriers is 800. The present example is used for transmitting data from a first transmission node which is a base station  101  to a second transmission node which is a mobile user  100 , as illustrated in  FIG. 1 , herein the number of OFDM symbols is M ofdm =6, the number of subcarriers on each OFDM symbol allocated by a system and used for transmitting data from the first transmission node to the second transmission node is Nsc=512, a modulation order is Mu=4, an error correction code rate is R=1/2, the number of error correction code blocks in each information data packet is c=1, the number of error correction code blocks born on each OFDM symbol is k0=1, the number of bits of a CRC sequence is h=8 and the number of check data packets obtained through packet coding is b=1. An apparatus according to the present invention at least includes a code block segmentation module  400 , a CRC sequence adding module  401 , a first-time filling module  402 , an error correction coding module  403 , a second-time filling module  404 , a grouping module  405 , a packet coding module  406 , a constellation mapping modulation module  407 , an OFDM modulation module  408  and a sending module  409 , as illustrated in  FIG. 4 . 
     The code block segmentation module  400  is configured to, according to the following parameters: a length L=5080 of a source data packet, the number of subcarriers Nsc=512 on each OFDM symbol allocated by a system and used for transmitting data from the first transmission node to the second transmission node, a modulation order Mu=4, an error correction code rate R=1/2, the number of OFDM symbols M ofdm =6, the number of error correction code blocks c=1 in each information data packet, the number of error correction code blocks k0=1 born on each OFDM symbol, the number of bits h=8 of each CRC sequence and the number of check data packets b=1 obtained through packet coding, calculate and obtain the number of data blocks which is d=M ofdm ×k0−b×c=5, herein the size of each data block is L/d=1016, and perform code block segmentation on the source data packet to be transmitted with the length of L=5080 bits to obtain d=5 data blocks, herein a length of each data block is 1016 bits. 
     The CRC sequence adding module  401  is configured to respectively add a CRC sequence with a length of h=8 bits to each data block, herein a length of each data block added with the CRC sequence becomes 1024 bits. 
     The first-time filling module  402  is configured to, after the CRC sequence is added, perform first-time filling on each data block, herein the first-time filling is to fill m1i=0 bits to an ith data block, and a filled bit is ‘0’, i=0, 1, . . . , 4, such that the length of each data block reaches 1024 bits. 
     The error correction coding module  403  is configured to respectively perform Turbo error correction coding on d=5 data blocks added with the CRC sequence to obtain bits with the total number being 10240. 
     The second-time filling module  404  is configured to perform second-time filling after Turbo error correction coding is performed, herein the second-time filling is to add m2=0 bits to a head or tail of an entire error correction code data block, and a filled bit is ‘0’. 
     The grouping module  405  is configured to perform grouping to obtain a=5 information data packets with a same length, herein each information data packet has 2048 bits. 
     The packet coding module  406  is configured to perform packet coding on a=5 information data packets to obtain b=1 check data packet, herein a length of the check data packet is 2048 bits and a single parity check coding method is used in the packet coding. 
     The constellation mapping modulation module  407  is configured to, by using a constellation mapping modulation mode which is 64QAM and a modulation order which is 4, perform constellation mapping modulation on the a=5 information data packets with the number of effective bits being 10240 to obtain a first modulation symbol sequence with a length of k1=2560, and perform constellation mapping modulation on the b=1 check data packet with the number of effective bits being 2048 to obtain a second modulation symbol sequence with a length of k2=512. 
     The OFDM modulation module  408  is configured to map the first modulation symbol sequence and the second modulation symbol sequence to 512×6 two-dimensional time-frequency resource on 6 continuous OFDM symbols according to a time order, herein 512 constellation mapping modulation symbols mapped to an ith OFDM symbol are sequentially mapped to 512 non-reference signal subcarriers of the ith OFDM symbol, i=0, 1, . . . , 5; and herein the first modulation symbol sequence is mapped to the 0th to 4th OFDM symbols, and the second modulation symbol sequence is mapped to the 5th OFDM symbol, herein i is a sending order number of an OFDM symbol and an OFDM symbol with a smaller sending order number is sent more early. 
     The sending module  409  is configured to enable a base station  101  to send the 7 OFDM symbols to a mobile user  100  according to sending order numbers. 
     Example Eleven 
     A difference of example eleven from example one and example ten lies in the error correction coding module  403 , where the used error correction coding method is convolutional coding, LDPC coding, RS coding, Hamming coding, product coding or BCH coding. 
     An embodiment of the present invention further provides a storage medium storing a computer program, herein the computer program is configured to execute the data packet processing method in the OFDMA system according to each of the above-mentioned embodiments. 
     When the methods and apparatuses capable of improving transmission performance of data packets of a physical layer of a communication system according to the embodiments of the present invention are implemented in the forms of software function modules and are sold or used as independent products, these methods and apparatuses may also be stored in a computer-readable storage medium. Based on such understanding, one skilled in the art shall understand that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the forms of full hardware embodiments, full software embodiments or embodiments combining software and hardware. In addition, the present application may adopt the form of computer program products which are implemented on one or more computer-usable storage mediums including computer-usable program codes, and the storage mediums include but not limited to USB disks, mobile hard disks, Read-Only Memories (ROM), magnetic disk memories, CD-ROMs, optical memories and the like. 
     The present application is described according to flowcharts and/or block diagrams of the methods, apparatuses (systems) and computer program products of the embodiments of the present invention. It shall be understood that each flow and/or block in the flowcharts and/or block diagrams and combinations of flows and/or blocks in the flowcharts and/or block diagrams may be implemented by computer program instructions. These computer program instructions may be provided to a general-purpose computer, a dedicated computer, an embedded processor or other programmable data processing devices to produce a machine, such that instructions executed through a processor of a computer or other programmable data processing device produce an apparatus which is used for implementing functions designated in one or more flows of flowcharts and/or one or more blocks of block diagrams. 
     These computer program instructions may also be stored in a computer-readable memory which is capable of guiding computers or other programmable data processing devices to work in a specific manner, such that instructions stored in the computer-readable memory produce a product including an instruction device which implements functions designated in one or more flows of flowcharts and/or one or more blocks of block diagrams. 
     Theses computer program instructions may also be loaded on computers or other programmable data processing devices, such that a series of operation steps are executed on computers or other programmable data processing devices to perform processing implemented by computers, and thereby instructions executed on computers or other programmable data processing devices provide steps which are used for implementing functions designated in one or more flows of flowcharts and/or one or more blocks of block diagrams. 
     INDUSTRIAL APPLICABILITY 
     In the present invention, all error correction code blocks are re-decoded through packet coding and decoding, thus the performance of each error correction code block is improved, and thereby the receiving robustness is improved.