CN108900459A - GFDM/CDMA mixing multiple access radio switch-in method - Google Patents

Abstract

The invention discloses a GFDM/CDMA mixed multiple access wireless access method, which can eliminate the interference between GFDM sub-carriers by using the invention. The present invention is realized through the following technical solutions: the present invention aims at the problems that the users who use adjacent subcarriers will interfere with each other and are difficult to realize. In the multiple access wireless access system, the spread spectrum time slot ALOHA is introduced. After the user completes the time-frequency synchronization of the base station, each user randomly sends the uplink data that arrives at the base station at the beginning of each time slot; the number of subcarriers is K , each subcarrier can carry the number of symbols M in the generalized frequency division multiplexing GFDM system to number the subcarriers; when the user sends data, the PN sequence is added between adjacent subcarriers for spread spectrum, that is, the odd subcarriers use the same One PN1 uses the same PN2 for the even-numbered subcarriers, so as to cancel the interference between non-orthogonal subcarriers.

Description

GFDM/CDMA hybrid multiple access wireless access method

technical field

The invention relates to a wireless communication multiple access technology field based on generalized frequency division multiplexing (GFDM) (Generalized Frequency Division Multiplexing), especially a hybrid multiple access technology combining generalized frequency division multiple access and spread spectrum time slot Aloha.

Background technique

In recent years, ultra-wideband wireless communication systems usually use extremely short-duration pulse waveforms to modulate the transmitted data, and the modulation bandwidth is extended to several GHz levels, so that the system has low power consumption and extremely high data transmission rates. High, strong anti-multipath and narrow-band interference capabilities, large user capacity and a series of unique advantages. In a multi-user system, the receiver is interfered not only by background noise but also by other transmitting users. Since the phase and time delay of the interference pulse of other transmitting users to the receiver are random, it is necessary to calculate the interference caused by the pulse to the output of the receiver. With the continuous update of satellite communication technology and the continuous increase of business types, the existing technology has proposed fixed time slot allocation agreement (FAMA), demand allocation agreement (DAMA), random access agreement (RA), free access agreement Basic types of multiple access protocols such as (FA) and slotted ALOHA protocols. At present, there are mainly CFDAMA protocols that combine on-demand allocation and free allocation, CFDAMA that combines fixed allocation and on-demand allocation, CRDAMA that combines random access and on-demand allocation, and other types of mixed protocols. Time slot ALOHA is also applied to satellite communication and wireless digital communication network. The ALOHA protocol is divided into pure ALOHA and slotted ALOHA. The idea of the ALOHA protocol is very simple, as long as the user has data to send, just let them send. Of course, this will create a collision and cause frame corruption. In a time-slotted ALOHA system, the computer does not send data immediately after the user presses the Enter key, but waits until the next time slice begins. In this way, continuous pure ALOHA becomes discrete slotted ALOHA. Since the collision area of the collision is reduced to half of that of pure ALOHA on average, the channel utilization of slotted ALOHA can reach 36.8% (1/e), twice that of pure ALOHA. But for slotted ALOHA, the average transmission time of user data is higher than that of pure ALOHA system. A variety of multiplexing protocols is to share a common channel among many users of a system. This protocol must control the way users access the channel by requiring users to follow a certain principle. This protocol must control the distribution capacity of the channel. The user transmission and communication method is called a protocol. Channels are used to distinguish communication objects. A channel can only accommodate one user for a call. Many users who are talking at the same time are distinguished by channels. This is multiple access. When multiple users use a common medium to transmit is called multiple access. Multiple access protocols are therefore a principle for successful information transfer between users sharing the same transmission medium, and multiple access protocols are required when resources are used by more than one independent user. Without this protocol, collisions will occur when multiple users access transmission resources at the same time, so the multiple access protocol must at least solve these collision problems. The function of multiple access protocol technology is to enable terminals in the same network to share the same transmission resource. Multiple access protocols are used in transmission systems that share channel resources. In this case, the main reason for sharing resources is the connectivity of the system environment. In wireless transmission systems, there must be efficient resource utilization. When multiple users Using a common transmission medium, this transmission network consists of many point-to-point links. When one of the links is used by multiple users at the same time, multiplex technology is required, which means that different transmission information uses the same physical link. When the carrier frequency of the transmission signal is different to distinguish the channel to establish multiple access, it is called frequency division multiple access (FDMA); when the time of the transmission signal is different to distinguish the channel to establish multiple access, it is called time division. Multiple access mode (TDMA); when different code patterns of transmission signals are used to distinguish channels and establish multiple access, it is called code division multiple access mode (CDMA). The multiple access methods currently used in mobile communications include: Frequency Division Multiple Access FDMA, Time Division Multiple Access TDMA, Code Division Multiple Access CDMA and their mixed application methods. Establishing a wireless channel connection between users is a problem of multiple access methods. The method to solve the problem of multiple access is called multiple access technology. Multiple access technology is one of the key technologies of satellite communication, which has an important impact on the user capacity, complexity and economy of the system. The selection of multiple access protocols directly affects the spectrum utilization rate, system capacity, network structure, communication quality of service, and equipment complexity of the system. The traditional multiple access technology is based on the principle of orthogonal signal division to realize the separation of multi-user service signals, such as time division, frequency division, code division, space division, etc. Among them, frequency division multiple access technology is mature, stable, easy to implement and low in cost , but its spectrum utilization rate is low, and each user (remote station) must occupy a certain guard frequency band. Time division multiple access is to divide time into periodic frames, and each frame is divided into several time slots to send signals to the base station. Under the condition of timing and synchronization, the base station can receive each mobile terminal in each time slot respectively. signal without confusion. Compared with FDMA, TDMA has the advantages of better communication signal quality, better security, larger system capacity, and higher spectrum utilization rate, and is widely used in the field of broadband wireless access. CDMA technology assigns different code sequences to different users to share the same channel, and uses different codes to distinguish different users. In an actual environment, due to functional limitations of various multiple access technologies, multiple multiple access technologies are often used in combination.

Pseudo-code synchronization is a prerequisite for the normal operation of spread spectrum communication systems, and pseudo-code capture is a prerequisite for pseudo-code synchronization. In order to realize the concealment of the communication system, a hybrid multiple access method is generally adopted, such as a hybrid multiple access method of Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA). In this multiple access mode, the communication time is extremely short, the initial frequency difference is large, the signal dynamic range is large, the carrier-to-noise ratio is low, and there may be strong interference signals. At present, hybrid multiple access technologies include: MF-TDMA, TD-CDMA, etc., which belong to the category of single-carrier orthogonal multiple less efficient. Aiming at the problem of spectrum utilization, some solutions have been proposed in the prior art, such as adopting multi-carrier orthogonal multiple access technology and multi-carrier orthogonal multiple access scheme. It can be seen as a combination of multi-carrier modulation symbols and orthogonal/quasi-orthogonal multiple access schemes in time, frequency, and code domains. Compared with single-carrier systems, orthogonal multiple access in multi-carrier systems has greatly improved spectral efficiency and can greatly improve User traffic rate. However, OFDM multi-carrier technology is not applicable in some application scenarios due to its large out-of-band radiation, high peak-to-average power ratio, and sensitivity to frequency offset. When different users randomly access the same time slot, as long as they do not use the same subcarrier, the system can still distinguish between different users, but the problem here is that if the user selects an adjacent subcarrier, the adjacent subcarrier Carrier users will interfere with each other, which is difficult to achieve. Aiming at the disadvantage that the above users have selected adjacent sub-carriers, there will be interference d between each other, the industry has proposed a generalized frequency division multiplexing (GFDM) technology as an improved technology of OFDM. Generalized frequency division multiplexing (GFDM) is a multi-carrier transmission waveform scheme with high spectrum utilization, simple transmission and reception, small out-of-band power leakage, no need for synchronization between sub-bands, and flexible modulation. At present, most of the research focuses on the direction of GFDM waveform to realize self-interference suppression. Although GFDM can expand the data into a time-frequency two-dimensional block structure, each block contains multiple sub-carriers and sub-symbols, and the number of sub-carriers and sub-symbols can be flexibly configured according to different transmission scenarios, but this multi-carrier technology and time-frequency There are still some difficulties in the combination of code domain hybrid multiple access technology. It can be clearly seen from Figure 3 that each subcarrier at the receiving end will be interfered by two adjacent subcarriers. It is precisely because of the existence of self-interference between non-orthogonal subcarriers that it is necessary to use a highly complex receiver at the receiving end. Algorithm can obtain better bit error rate performance.

The purpose of the present invention is to solve the problems existing in the prior art, on the basis of GFDM, use the system of time slot ALOHA to carry out random access, expand the way of adjacent carrier frequency spectrum to improve the interference between GFDM subcarriers, and propose a method that can improve Hybrid multiple access technology that is spectrally efficient and increases system capacity.

Contents of the invention

The technical problem to be solved by the present invention is to provide a GFDM/CDMA hybrid multiple access wireless access method that can improve access efficiency, increase the capacity of the wireless access system, and improve the interference between GFDM sub-carriers.

The above object of the present invention can be achieved by the following measures, a GFDM/CDMA hybrid multiple access wireless access method is characterized in that it comprises the following steps: using GFDM/code division multiple access CDMA hybrid In the multiple access wireless access system, the spread spectrum time slot ALOHA is introduced. After the user completes the time-frequency synchronization of the base station, each user randomly sends the uplink data that arrives at the base station at the beginning of each time slot; the number of subcarriers is K , each subcarrier can carry the number of symbols M in the generalized frequency division multiplexing GFDM system to number the subcarriers; when the user sends data, the PN sequence is added between adjacent subcarriers for spread spectrum, that is, the odd subcarriers use the same One PN1 uses the same PN2 for the even-numbered subcarriers, so as to cancel the interference between non-orthogonal subcarriers. When each user sends data, randomly occupy the subcarrier ci of the generalized frequency division multiplexing GFDM symbol, and set the symbol positions of the remaining subcarriers to 0, and combine the modulation characteristics of the generalized frequency division multiplexing GFDM with the inherent characteristics of the spreading time slot ALOHA Combining the spread spectrum characteristics, different pseudo-random sequence spread spectrum is added between adjacent subcarriers; each user performs GFDM modulation on the spread spectrum subcarrier data and then transmits; the receiving end receives according to different time slots, and transmits time slots after GFDM modulation In ALOHA, the mixed signal performs matched filter detection to remove the influence of the filter, and then uses the corresponding PN sequence set to despread the frequency domain data of the odd and even subcarriers, and uses spread spectrum to expand the spectrum of adjacent subcarriers, and uses the inverse fast Fourier transform IFFT Demodulate multi-user time-domain data; detect whether there is a user who has selected the same subcarrier and the PN code of the same code division multiple access communication system CDMA, and chooses the same time slot to send, the default collision, discard the collision data, the collision user in After waiting for the acknowledgment character ACK timeout, after a random delay, a random subcarrier and PN code are selected for retransmission; if there is no collision, the receiving end sends the acknowledgment character ACK and resource allocation information to the user on the same time-frequency code resource block, and the user After receiving the acknowledgment character ACK, the relevant traffic channel resources can be occupied to transmit data according to the resource allocation information.

Compared with the prior art, the present invention has the following positive effects:

The present invention aims at the problem that users using adjacent sub-carriers will interfere with each other, which is difficult to realize, and offsets the interference by adding different pseudo-random sequence spread spectrum between adjacent sub-carriers. The good auto-correlation and cross-correlation of adjacent sub-carrier spreading sequences are fully utilized, so that the probability of users being correctly distinguished is greatly improved, and the access efficiency and system capacity of the wireless access system are greatly improved. In the random access system using slotted ALOHA, the method of expanding adjacent carrier frequency spectrum is used to improve the interference between GFDM sub-carriers and increase the degree of freedom of user-selectable signals. Under the condition of adding multiple spreading sequences, the modulation characteristics of GFDM are combined with the inherent spreading characteristics of spreading time slot ALOHA, and different pseudo-random sequence spreading is added between adjacent subcarriers to eliminate the subcarriers of GFDM interfering. The idea of spread spectrum is used to expand the spectrum of adjacent sub-carriers, so that the users using adjacent sub-carriers can be successfully distinguished. Moreover, when different users randomly access the same time slot, the interference between adjacent subcarriers selected by the users is offset.

The present invention introduces traditional spread spectrum time slot ALOHA on the basis of multi-carrier technology GFDM, and combines the modulation characteristics of GFDM with the inherent spread spectrum characteristics of spread spectrum time slot ALOHA. All the advantages of frequency slot ALOHA (such as simple system implementation, etc.), and on this basis, the advantages of multi-carrier transmission technology GFDM are introduced, and the GFDM transmission technology is perfectly combined with the spread spectrum technology in spread spectrum slot ALOHA The integration of the system greatly improves the access efficiency of users. Compared with Orthogonal Frequency Division Multiplexing OFDM, Generalized Frequency Division Multiplexing GFDM has lower peak-to-average power ratio (PAPR) and out-of-band spectral leakage. Compared with other multi-carrier waveform schemes, generalized frequency division multiplexing GFDM has stronger flexibility and adaptability.

The present invention creatively adds PN sequences between adjacent subcarriers for spreading, that is, uses the same PN1 for odd-numbered subcarriers, and uses the same PN2 for even-numbered subcarriers, so as to offset the interference between non-orthogonal subcarriers , without increasing too much complexity, which is the biggest innovation point of the present invention.

Description of drawings

Fig. 1 is a functional block diagram of the multi-carrier transmitter of the generalized frequency division multiplexing GFDM system of the present invention.

FIG. 2 is a schematic diagram of a slotted ALOHA random access multiple access mode.

Fig. 3 is a schematic diagram of a frequency response curve of a GFDM adjacent subcarrier filter.

The working process of this invention will be further described in detail below in conjunction with the accompanying drawings.

Detailed ways

See Figure 1. According to the present invention, in the wireless access system of multi-carrier transmitter generalized frequency division multiplexing GFDM/code division multiple access CDMA hybrid multiple access, the spread spectrum time slot ALOHA is introduced, and after the user completes the time-frequency synchronization of the base station, each user Randomly send the uplink data arriving at the base station at the start of each time slot; use the generalized frequency division multiplexing GFDM system with the number of subcarriers K and each subcarrier can carry M symbols, and number the subcarriers: c1, c2 , ..., ck; when the user sends data, the PN sequence is added between adjacent subcarriers for spreading, that is, the same PN1 is used for the odd-numbered subcarriers, and the same PN2 is used for the even-numbered subcarriers to offset the non-positive Interference between subcarriers. When each user sends data, the subcarrier ci of the GFDM symbol is randomly occupied, and the symbol positions of the remaining subcarriers are set to 0. Combining the modulation characteristics of GFDM with the inherent spreading characteristics of the spread spectrum slot ALOHA, the adjacent subcarriers Different pseudo-random sequences are added between carriers for spread spectrum; each user performs GFDM modulation on the spread-spectrum subcarrier data and then transmits; the receiving end receives according to different time slots, and performs matched filtering detection on the mixed signal in the time slot ALOHA to remove the influence of the filter. Then use the corresponding PN sequence set to despread the odd and even subcarrier frequency domain data respectively, use spread spectrum to expand the adjacent subcarrier spectrum, and demodulate the multi-user time domain data through inverse fast Fourier transform IFFT; detect whether there is any The user selects the same subcarrier and the same CDMA PN code of the CDMA communication system, and selects the same time slot for transmission, the default collision, discarding the collision data, the collision user waits for the confirmation character ACK after a random delay after timeout, selects the random Subcarriers and PN codes are retransmitted; if there is no collision, the receiving end sends the confirmation character ACK and resource allocation information to the user on the same time-frequency code resource block. After the user receives the confirmation character ACK, it can occupy the resources according to the resource allocation information Related traffic channel resources transmit data.

In a multi-carrier transmitter, the number of symbols transmitted per subcarrier is M, and the Kth subcarrier symbol Data is represented as M×1 data, M×1 subcarrier symbols The vector passes through the fast Fourier transform FFT, and the upsampled sequence set 1 {PN ₁ , PN ₃ , ..., PN _2n+1 } and the PN sequence set 2 {PN ₂ , PN ₄ , ..., PN _2n } to perform spread spectrum to form two pseudo-random sequence sets PN for the user to select odd-numbered subcarriers or even-numbered subcarriers LM×1 union vector. The frequency domain data is subjected to direct sequence spread spectrum, and the spread spectrum result is passed through the LM×1 filter, and then the cyclic shift is performed to obtain the KM×1 vector, and the KM×1 vector is summed, and after the fast Fourier transform FFT, the KM×1 signal is output vector, where K is the number of subcarriers. The specific steps to accomplish the above tasks include:

Step 1: After the user completes time-frequency synchronization with the base station, each user randomly sends uplink data to ensure that the arrival time at the base station is the start time of each time slot.

Step 2: When each user sends data, the generalized frequency division multiplexing GFDM system takes the number of even subcarriers as K, the number of odd symbols that each subcarrier can carry is M, and takes the power of each power of K=2, for the subcarriers _Carry out numbers _{c 1} , c ₂ , .

Step 3: There are two pseudo-random sequence sets {PN ₁ , PN ₃ , . . . , PN _{2n +1} }, {PN ₂ , PN ₄ , . In the previous step, if the user selects odd-numbered subcarriers, in the {PN ₁ , PN ₃ , ..., PN _2n+1 } pseudo-random sequence set, select any PN sequence in the odd-numbered PN sequence set to directly sequence its frequency domain data Spread spectrum; if an even-numbered subcarrier is selected, select any PN sequence in the even-numbered PN sequence set in the {PN ₂ , PN ₄ , ..., PN _2n } pseudo-random sequence set to perform direct sequence spread on its frequency domain data.

Step 4: According to the transmission block diagram shown in FIG. 1 , each user performs GFDM modulation on the subcarrier data after spectrum spreading and then transmits it.

Step 5: The receiving end receives according to different time slots, performs matched filter detection on the mixed signal in the time slot to remove the influence of the filter, and then uses the corresponding PN sequence set to despread the frequency domain data of the odd and even subcarriers respectively, and passes the fast Fourier transform The inverse transform IFFT demodulates the multi-user time domain data.

Step 6: Then detect whether there is a user who selects the same subcarrier and the same PN code and selects the same time slot to send, the default collision, the collision data is discarded, the collision user waits for the ACK timeout after a random delay, selects a random subcarrier, PN code for retransmission. If there is no collision, the receiving end sends ACK and resource allocation information to the user on the same time-frequency code resource block. After receiving the ACK, the user can occupy the relevant service channel resources to transmit data according to the resource allocation information.

See Figure 2. The hybrid multiple access technology based on generalized frequency division multiplexing can be discussed on a case-by-case basis. The following description is based on the special case that the set of pseudo-random sequences is {PN ₁ }, {PN ₂ }. Assume that in a mobile communication system, there are U1, U2, U3..., U _i ,..., U _L users who send data at the start position of each time slot according to the time slot ALOHA method, L is a natural number, and they will be divided into The specific working method of the invention is described in detail.

The first case is that only one user U ₁ generates the data d ⁽ⁱ⁾ to be sent within a period of time, then at the beginning of the next time slot that can send data, the user U 1 will follow the interval time slot along the channel at the beginning time Perform data transmission, retransmission and retransmission, and the receiving end normally receives the retransmission data without conflict.

The second situation is that within a period of time, a user U _i selects a subcarrier and generates data to be sent at the same time, and the subcarriers selected by each user are different, and initiates data transmission in the same time slot and retransmits .

The third case is that multiple users choose the same subcarrier and the same PN code, and choose the same time slot to send, K users, and 1<K<L, according to the interval time slot along the channel at the initial moment For data transmission, after waiting for the ACK timeout, the colliding user selects a random subcarrier and PN code for retransmission or retransmission after a random delay. By default, the colliding data is discarded, and K is an integer.

See Figure 3. GFDM introduces pulse-shaping filters to system transmission subcarriers. Although it increases the computational complexity of the system, it can also reduce out-of-band leakage and increase flexibility. In the frequency response curve of the GFDM adjacent subcarrier filter, the wireless access system uses a root-raised cosine pulse shaping filter with a roll-off factor of 0.5, and configures three PN ₁ , PN ₂ , and PN ₁ amplitude intersection subcarrier curves , forming the spectrum curve of each subcarrier.

The foregoing descriptions of the present invention and its embodiments are provided to those skilled in the art of the invention and are to be considered illustrative rather than restrictive. Engineers and technicians can implement specific operations based on the ideas in the claims of the invention, and can make various changes in form and details without departing from the spirit and scope of the present invention defined by the appended claims. Variety. All of the above should be considered as the scope of the present invention.

Claims (10)

1. A GFDM/CDMA hybrid multiple access wireless access method is characterized in that comprising the steps: in the wireless access system of multi-carrier transmitter generalized frequency division multiplexing GFDM/code division multiple access CDMA hybrid multiple access, introducing Spread spectrum time slot ALOHA, after the user completes the time-frequency synchronization of the base station, each user randomly sends uplink data that arrives at the base station at the beginning of each time slot; the number of subcarriers is K, and the number of symbols that each subcarrier can carry is M The generalized frequency division multiplexing GFDM system numbers subcarriers; when users send data, PN sequences are added between adjacent subcarriers for spreading, that is, the same PN1 is used for odd-numbered subcarriers, and the same PN1 is used for even-numbered subcarriers. A PN2 is used to cancel the interference between non-orthogonal sub-carriers. 2. the GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1, is characterized in that: when each user sends data, randomly occupies the subcarrier ci of generalized frequency division multiplexing GFDM symbol, and the remaining subcarriers The symbol position is set to 0, and the modulation characteristics of the generalized frequency division multiplexing GFDM are combined with the inherent spreading characteristics of the spreading time slot ALOHA, and different pseudo-random sequences are added between adjacent subcarriers for spreading. Subcarrier data is transmitted after GFDM modulation. 3. GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1 is characterized in that: the receiving end receives by different time slots, carries out matched filter detection removal filter to mixed signal in transmission time slot ALOHA after GFDM modulation Then use the corresponding PN sequence set to despread the odd and even subcarrier frequency domain data respectively, use spread spectrum to expand the adjacent subcarrier spectrum, and demodulate the multi-user time domain data through inverse fast Fourier transform IFFT; detect whether There is a situation where a user selects the same subcarrier and the PN code of the same code division multiple access communication system CDMA, and selects the same time slot to send, the default collision, the collision data is discarded, and the collision user waits for the confirmation character ACK after a random delay after timeout, Select random subcarriers and PN codes for retransmission; if there is no collision, the receiving end sends the confirmation character ACK and resource allocation information to the user on the same time-frequency code resource block. After the user receives the confirmation character ACK, according to the resource allocation information Occupy relevant business channel resources to transmit data. 4. GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1 is characterized in that: in multi-carrier transmitter, the symbol number that each subcarrier transmits is M, and the Kth subcarrier symbol Data is represented as M×1 data, M×1 subcarrier symbols The vector passes through the fast Fourier transform FFT, and the upsampled sequence set 1 {PN ₁ , PN ₃ , ..., PN _2n+1 } and the PN sequence set 2 {PN ₂ , PN ₄ , ..., PN _2n } to spread spectrum to form two pseudo-random sequence sets PN for users to select odd numbered subcarriers or even numbered subcarriers LM×1 union vector. 5. GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1 is characterized in that: select any PN sequence in odd PN sequence set or even PN sequence set to carry out direct sequence spread spectrum to its frequency domain data, spread spectrum The result is passed through the LM×1 filter, and then cyclically shifted to obtain the KM×1 vector, and after the sum of the KM×1 vector, the fast Fourier transform FFT is performed to output the KM×1 signal vector, where K is the number of subcarriers. 6. The GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1, characterized in that: after the user completes the time-frequency synchronization to the base station, each user randomly sends uplink data to ensure that the time of arrival at the base station is the beginning of each time slot time. 7. GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1, is characterized in that: when each user sends data, generalized frequency division multiplexing GFDM system is K with even subcarrier number, and each subcarrier can carry The number of odd symbols M, and take the power of each power of K=2, number the subcarriers as c ₁ , c ₂ ,..., c _k , randomly occupy the subcarrier c _i of the GFDM symbol, and assign the remaining subcarriers The sign position of is set to 0. 8. The GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1, characterized in that: if the user selects an odd-numbered symbol subcarrier, then in {PN ₁ , PN ₃ , ..., PN _2n+1 } pseudo _In the random sequence set, select any _PN sequence in the odd PN sequence set to perform direct sequence spread spectrum on its frequency domain data _; Any PN sequence in the even-numbered PN sequence set performs direct sequence spread spectrum on its frequency domain data, and n is a natural number. 9. The GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 1, characterized in that: based on the special case that the pseudo-random sequence set is {PN ₁ }, {PN ₂ }, it is set in a mobile communication In the system, there are U1, U2, U3..., U _i ,..., U _L users who send data at the beginning of each time slot in ALOHA mode; within a period of time, if only _one user U1 generates a waiting Send data d, then at the beginning of the next time slot that can send data, the user will send, resend and resend data according to the interval time slot along the channel at the beginning time, and the receiving end will receive the resent data normally, and will not A collision occurs, where L is a natural number. 10. GFDM/CDMA hybrid multiple access wireless access method as claimed in claim 9 is characterized in that: within a period of time, user U _i selects the subcarrier, produces data to be sent simultaneously, and the subcarrier selected by each user Carriers are different, and initiate data transmission in the same time slot, and retransmit; if multiple users select the same subcarrier and the same PN code, and choose the same time slot for transmission, K users, and 1<K<L, data is sent along the interval time slot of the channel at the initial moment. After the collision user waits for the ACK timeout, after a random delay, a random subcarrier and PN code are selected for retransmission or retransmission. The default collision is discarded. data, K is an integer.