TW201902164A - Cyclic-frequency shift orthogonal frequency division multiple access spread spectrum device - Google Patents

Abstract

A cyclic-Frequency shift orthogonal frequency division multiple access spread spectrum device is provided whose communication device performs signal transmission according to a frequency band having Q sub-bands, each sub-band having M sub-carriers, the Q sub-bands respectively having independent cyclic frequency shift values, and the communication device is used for performing the conversion between a string of bits and Q frequency-domain symbols by using a plurality of cyclic frequency shift values. Wherein, the Q frequency-domain symbols are generated according to Q data of Q stations, and Q stations have the corresponding Q sub-bands; the Q station have the corresponding string bits and are assigned to the Q sub-bands; and the cyclic frequency shift values are a frequency-ordered loop, and different cyclic-frequency shift values correspond to different bit values.

Description

 Spread frequency shifting orthogonal frequency division multiplexing access spread spectrum device  

The present invention relates to a spread spectrum apparatus, and more particularly to a spread spectrum apparatus of a Cyclic-Frequency Shift (CFS) Orthogonal Frequency Division Multiple Access (OFDMA).

Cyclic-Frequency Shift Orthogonal Frequency Division Multiplex Spread Spectrum (CFS-OFDM) technology, the message is transmitted through the cyclic frequency shift value of the wideband OFDM signal. The advantage is that it can still be transmitted with very low signal-to-noise ratio, which is very suitable for long-distance communication applications. By looping the preamble, the channel in the multipath is better than the direct sequence spread spectrum (DSSS), the frequency hopping spread spectrum (FHSS), and the chirp spread spectrum (Chirp Spread Spectrum). Traditional spread spectrum technologies such as CSS) have better performance. By properly selecting the frequency domain signal, the signal in the time domain has a very low power peak-to-average ratio, so the linearity requirement of the RF gain amplifier at the transmitting end is very low, which can greatly reduce the cost of the amplifier.

The purpose of the CFS-OFDMA spread spectrum device of the present invention is to enable a base station (Access Point, hereinafter referred to as AP) to simultaneously use multiple sub-bands and multiple workstations (hereinafter referred to as "station"), and the AP and multiple stations simultaneously pass CFS. - OFDM communication, to achieve the effect of improving the overall transmission rate. In the uplink transmission, each workstation only needs to transmit its own CFS-OFDM signal, so the power peak-to-peak ratio of the signal is extremely low, which greatly reduces the cost of the front-end gain amplifier.

The present invention provides a CFS-OFDMA device, comprising: at least one communication device, performing signal transmission according to a frequency band, the frequency band has Q sub-bands, and each sub-band has M sub-carriers, and the Q sub-bands have independent cyclic frequency shift values, And the communication device is configured to use a plurality of cyclic frequency shift values to perform conversion between a series of bits and Q frequency domain symbols; wherein the Q frequency domain symbols are generated according to Q data of the Q station, Q station The workstation has corresponding Q sub-bands; the Q station has corresponding bit strings and is allocated to Q sub-bands; and the cyclic frequency shift values are a frequency ordering cycle, and different cyclic frequency shift values correspond to different bit values .

In an embodiment, the at least one communication device includes a receiving device and a transmitting device. When the Q station performs uplink transmission, the transmitting device first transmits a synchronization packet to the Q workstation through a broadcast manner to confirm The time when the Q station starts to transmit; when the Q station receives the synchronization packet, according to the synchronization packet as a reference point of the transmission time axis, the Q station simultaneously simultaneously Q the fixed time The data is transmitted through a CFS-OFDM signal corresponding to a time domain packet in the corresponding Q subbands.

In an embodiment, the Q frequency domain symbols may be arranged according to the order of the M subcarriers; or the Q frequency domain symbols may be staggered according to the order of the M subcarriers.

100‧‧‧CFS-OFDMA spread spectrum device

110‧‧‧Communication device

200‧‧‧Transfer

210_1~210_Q‧‧‧Gray code coding unit

220_1~220_Q‧‧‧Modulation unit

230‧‧‧OFDM transmission unit

231‧‧‧Package unit

232‧‧‧window unit

233‧‧ Circulation preamble unit

234‧‧‧N-point anti-Fourier transform unit

240‧‧‧Transmission circuit Tx

300‧‧‧ receiving device

310_1~310_Q‧‧‧Gray decoding unit

320‧‧‧Demodulation Module

321_1~321_Q‧‧‧ Peak Judging Unit

322_1~322_Q‧‧‧Circular convolution unit

330‧‧‧OFDM receiving unit

331‧‧‧Package detection unit

332‧‧‧Circular leading removal unit

333‧‧‧N-point Fourier transform unit

340‧‧‧Receiving circuit Rx

Figure 1 shows a schematic diagram of a different cyclic frequency combined pattern corresponding to a bit value.

2 is a functional block diagram of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention.

3 is a functional block diagram showing a transmitting apparatus of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention.

4 is a schematic diagram showing a subband cutting manner of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a subband cutting manner of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention.

Fig. 6 is a functional block diagram showing a receiving apparatus of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention.

FIG. 7 is a schematic diagram showing a synchronous packet of uplink transmission of a CFS-OFDMA spread spectrum apparatus according to an embodiment of the present invention.

In an embodiment of the present invention, a CFS-OFDM technology is proposed, which is a new spread spectrum technology (Spread Spectrum), which can provide extremely stable wired (Wired) and wireless (Wireless) transmission, and is widely used in all communication systems. When there are multiple stations in the wireless network, we can cut the overall bandwidth into several sub-bands, each of which is used by different stations. The AP can transmit with CFS-OFDM at the same time with several stations. This type of multiplex access is called CFS-OFDMA. In addition to the stable transmission effect of the original CFS-OFDM, CFS-OFDMA improves the overall transmission performance of the network and greatly reduces the signal collision probability caused by large transmissions between stations, because it can communicate with multiple stations at the same time. In the uplink (uplink), each station only needs to transmit its own sub-band CFS-OFDM signal, so it has a very low peak-to-average power ratio (Peak to average power ratio), and the linear demand for the front-end amplifier is greatly reduced. cut costs. Combining the above advantages, CFS-OFDMA is very suitable for wireless Internet of Things, a large network system with up to thousands of stations.

In an embodiment, the sequentially arranged cyclic frequency ordering may be regarded as the first combined aspect, and the frequencies are shifted to the left or right in a cyclic manner as other combined manners, and each combined aspect corresponds to one Cyclic frequency shift value. More details are as follows. Figure 1 shows a schematic diagram of a different cyclic frequency combined pattern corresponding to a bit value. As shown in FIG. 1, in the present embodiment, the sequentially arranged frequency order S ₁₁ S ₁₂ S ₁₃ S _{14 is taken} as the first combined aspect, and the cyclic frequency displacement value m=0 is specified and is the first sub-band. . After the frequencies are shifted to the left by one unit in a cyclic manner, a frequency ordering S ₁₂ S ₁₃ S ₁₄ S _{11 is formed} , as a second combined aspect, where the cyclic frequency shift value m=1 and is the first sub-band, Other combinations, and so on. In this embodiment, different cyclic frequency combinations correspond to different cyclic frequency displacement values, and different cyclic frequency displacement values correspond to different bit values, and the bit values may be binary code or Gray coded.

For example, when N=4, a message of k=2 bits can be transmitted through the cyclic frequency shift value. As shown in Table 1 above (taking the first sub-band as an example), m is a cyclic frequency shift value transmitting two bits of information, the binary value is b ₂ b ₁ , the Gray code is g ₂ g ₁ , and the original subcarrier content For S ₁₁ S ₁₂ S ₁₃ S ₁₄ , when the cyclic frequency shift = 1, the subcarrier order becomes S ₁₂ S ₁₃ S ₁₄ S ₁₁ , and when the cyclic frequency shift = 2, the subcarrier order becomes S ₁₃ S ₁₄ S ₁₁ S ₁₂ , and so on. The example of Table 1 is a cyclic shift to the left, but the cyclic shift of the present invention is not limited to cyclic shifts to the left or to the right.

Referring to Table 2 above and the mathematical formula S (mod(k+m, N)), in an embodiment, the transmission signal of CFS-OFDM can satisfy the following formula (1): Where N is the number of all frequency domain subcarriers, S(k) is the frequency domain symbol, k is the kth subcarrier, s(n) is the time domain symbol, n is the nth time point, and m is the The cyclic frequency shift value is in units of subcarriers, mod(.,N) is module N, that is, the remainder is taken for N, and N can be implemented by the power of two.

Since the possible value of the cyclic frequency shift amount m is 0~N-1, a symbol of CFS-OFDM can transmit up to K=log ₂ (N) bit messages.

In theory, S(k) can be used as a CFS-OFDM signal as long as it is a non-periodic signal, but a proper choice of S(k) can achieve better transmission quality. The so-called appropriate selection includes the selection of the best auto-correlation characteristics and the lowest peak-to-average power ratio (PAPR) in the time domain. For example, when the selected S(k) is as shown in the following formula (4), the above two advantages are obtained:

In this embodiment, the PAPR of the real or imaginary part in the time domain is about 3 dB, and the auto-correlation is far greater than 0 only when k=0, in the case of k≠0. 0, so it is a very good choice as CFS-OFDM. This embodiment can reduce the linearity requirement of the RF gain amplifier at the transmitting end, and can greatly reduce the cost of the amplifier.

The CFS-OFDMA spread spectrum apparatus according to an embodiment of the present invention is a CFS-OFDM-based communication technology, which divides a frequency band into a plurality of sub-bands, and simultaneously uses multiple stations of CFS-OFDM to simultaneously operate CFS. - The transmission rate of OFDM is increased several times.

2 is a functional block diagram of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention. As shown in FIG. 2, according to an embodiment of the present invention, the spread spectrum device 100 of the CFS-OFDMA includes at least one communication device 110, and the communication device 110 performs signal transmission according to a frequency band; please note that the frequency band has Q sub-bands, and Each sub-band has M sub-carriers, Q sub-bands have independent cyclic frequency shift values, Q sub-bands respectively correspond to Q frequency-domain symbols, and the communication device 110 uses a plurality of cyclic frequency shift values to perform a series of bits and Qs. The conversion between the frequency domain symbols; wherein the Q frequency domain symbols are generated according to the Q data of the Q station, the Q station has a corresponding Q sub-band; the Q station has the corresponding bit and Allocating to the Q sub-bands; and the cyclic frequency shift values are a frequency-sequenced loop, and the different cyclic frequency shift values correspond to different bit values.

Assuming that the entire frequency band has a total of M subcarriers, the entire frequency band can be cut into Q subbands according to the Q station, and each subband is allocated to one station for use, and then the AP is simultaneously transmitted with the Q station by CFS-OFDM, the whole network. The transmission rate will increase by several times. For example, assuming M = 1024, each symbol of CFS-OFDM can carry log ₂ (1024) = 10 bits. If it is cut into 8 sub-bands, each sub-band has 128 sub-carriers, then CFS-OFDM of each sub-band can transmit log ₂ (128)=7 bits, and transmit with CSS-OFDMA simultaneously with eight stations, each symbol It can transmit 8×7=56 bits, that is, the transmission rate can reach 5.6 times as much as the original. Since the AP communicates with multiple stations at the same time with CFS-OFDM, this method is called CFS-OFDMA.

In one embodiment, at least one communication device 110 includes a transmitting device 200. In one embodiment, a receiving device 300 can be further included. The transmitting device 200 is configured to convert a series of bits into a plurality of frequency domain symbols, and convert the frequency domain symbols into a transmission signal St. The receiving device 300 is configured to receive the transmission signal St and convert the transmission signal St into a plurality of frequency domain symbols, and then convert the frequency domain symbols into a series of bits.

3 is a functional block diagram showing a transmitting apparatus of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention. In the downlink transmission end of the spread spectrum device of the CFS-OFDMA, as shown in FIG. 3, the transmission device 200 of the spread spectrum device 100 of the CFS-OFDMA includes: Q modulation units 220_1~220_Q, and Q sub-bands at the same time The M subcarriers are converted into the Q frequency domain symbols, and the Q frequency domain symbols are a function of a plurality of cyclic frequency shift values.

Referring to FIG. 3, the transmitting device 200 of the spread spectrum device 100 of the CFS-OFDMA may further include: Q Gray code encoding units 210_1 210210_Q, an OFDM transmitting unit 230, and a transmitting circuit Tx 240. In this embodiment, the data to be sent to the Q stations is Data_1 to Data_Q, respectively, and after each of the Gray code coding units 210_1~210_Q is Gray-coded, the Gray code coding units 210_1~210_Q are used according to the Q sub-data simultaneously. The format of the string bit is converted from Q binary code to Q Gray code to minimize the one bit error rate when the symbol is demodulated. The OFDM transmission unit 230 converts the Q frequency domain symbols into a time domain symbol and forms a time domain packet with the time domain symbols. The transmission circuit Tx 240 converts the time domain packet into a transmission signal St, and transmits it through a network route or a wireless signal.

In an embodiment, the OFDM transmission unit 230 includes an N-point inverse Fourier transform unit 234, a cyclic preamble (CP) unit 233, a window unit 232, and a packet composition unit 231. The N-point Inverse Fast Fourier Transform (N-IFFT) unit 234 is coupled to the Q modulation units 220_1~220_Q, respectively, and the N-point inverse Fourier transform unit 234 is converted to the N point according to the N-point frequency domain symbol. The time domain symbol, in other words, the N-point inverse Fourier transform unit 234 is used to convert the Q frequency domain symbol combinations into time domain symbols. The loop preamble unit 233 copies part of the symbols in the end of the N-point time-domain symbol packet to the front end of the N-point time-domain symbol. The window unit 232 is coupled to the cyclic preamble unit 233 for reducing interference of time domain packets in adjacent frequency bands. The packet composition unit 231 combines a preamble, a header, a payload, and generates a time domain packet using the N-point time domain symbol. In an embodiment, the transmitting device 200 can reduce the bit error rate to the lowest through the Gray code, and the decimal digital value after the Gray code conversion is the value of the cyclic frequency displacement, and according to the cyclic frequency displacement value, according to the formula (1). Convert the signal through the inverse Fourier to the time domain. Next, a Cyclic prefix (CP) is added to boost immunity to multiple paths. Finally, the window range is added to reduce interference to adjacent frequency bands.

Please note that the subband cutting method of the spread spectrum device 100 of the CFS-OFDMA is not limited as long as the subband is a subset of the overall frequency band. However, it is generally easier to cut into sub-bands of the same size, that is, each sub-band has the same number of sub-carriers N=M/Q.

There are two practical cutting methods. The first one is called a sub-band of a region type. As shown in FIG. 4, there are three sub-bands, each sub-band has four sub-carriers, which are represented by different patterns. Each sub-portion can be seen from FIG. The subcarriers of the frequency band are continuous; wherein the subcarriers S ₁₁ S ₁₂ S ₁₃ S ₁₄ are the specified cyclic frequency displacement values m=0 and are the first subbands, and the subcarriers S ₂₁ S ₂₂ S ₂₃ S ₂₄ are designated cycles The frequency shift value m=0 is the second sub-band, and the sub-carrier S ₃₁ S ₃₂ S ₃₃ S ₃₄ is the specified cyclic frequency displacement value m=0 and is the third sub-band, although only three sub-bands are depicted in FIG. 4 . However, the invention should not be limited thereto.

The second type is called a decentralized sub-band, and the sub-carriers of each sub-band are evenly staggered, as shown in FIG. The advantage of the decentralized sub-band is that there can be better channel dispersion, and the disadvantage is that the sub-bands are relatively easy to interfere with each other.

In other words, the Q frequency domain symbols may be arranged according to the order of the M subcarriers; or the Q frequency domain symbols may be staggered according to the order of the M subcarriers.

The transmitting end of the spread spectrum device of the CFS-OFDMA allocates the data Data_1 to Data_Q to the Q Gray code encoding units 210_1~210_Q, and then the Q modulation units 220_1~220_Q perform cyclic frequency shifts on the respective sub-bands according to the information. Frequency shift) Finally, the overall frequency domain signal is integrated into the time domain symbol through the N-point inverse Fourier transform unit 234, and the cyclic preamble is transmitted through the transmission circuit Tx 240.

Fig. 6 is a functional block diagram showing a receiving apparatus of a spread spectrum apparatus of a CFS-OFDMA according to an embodiment of the present invention. In the downlink receiving end of the spread spectrum device of the CFS-OFDMA, as shown in FIG. 6, the receiving device 300 of the spread spectrum device 100 of the CFS-OFDMA may include: a receiving circuit Rx 340, an OFDM receiving unit 330, and Q. Demodulation modules 320_1~320_Q and Q gray decoding units 310_1~310_Q. After receiving the transmission signal St through the network route or the wireless signal, the receiving circuit Rx 340 converts the transmission signal St into a time domain packet. The receiving circuit Rx 340 may include an analog front end AFE, and the analog front end circuit AFE may include, for example, an analog filter, a signal gainer, and an analog digital conversion circuit to process the Transmission signal St.

The OFDM receiving unit 330 receives the time domain packet and converts the time domain packet into the frequency domain symbols. In an embodiment, the OFDM receiving unit 330 includes a packet detection unit 331, a loop preamble removing unit 332, and an N-point Fast Fourier Transform (N-FFT) unit 333. The packet detection unit 331 is configured to monitor the time domain signal, and estimate whether the domain packet exists sometimes according to the frame preamble, and adjust the gain size. The loop preamble removal unit 332 removes the loop preamble in the time domain packet to reduce to a plurality of N point time domain symbols. The N-point Fourier transform unit 333 converts a plurality of N-point time-domain symbols into a plurality of frequency-domain symbols, in other words, an N-point Fourier transform unit 333 allocates the Q frequency-domain symbols to the M in the Q sub-bands Subcarriers, and restore the time domain symbols to the Q frequency domain symbols.

After detecting the signal, the packet detection unit 331 removes the cyclic preamble and converts it to the frequency domain through the N-point Fourier transform unit 333, and performs demodulation of the CFS-OFDM for each sub-band to solve the original transmission of the Q station. data.

The Q demodulation modules 320_1~320_Q are used to simultaneously demodulate the Q frequency domain symbols corresponding to the M subcarriers, and convert the corresponding bit values according to the corresponding cyclic frequency displacement values into corresponding corresponding bit values.

The Q demodulation modules 320_1~320_Q are used to simultaneously demodulate the Q frequency domain symbols into a corresponding series of bits. Please note that the Q Gray code decoding units 310_1~310_Q are used to convert the format of the serial bit bit from Q Gray code to Q binary code when the format of the string bit is Gray code.

In this embodiment, the demodulation modules 320_1~320_Q respectively include the circular convolution units 322_1~332_Q and the peak determination units 321_1~332_Q. The circular convolution units 322_1~322_Q respectively perform cyclic convolution of the Q frequency domain symbols; the peak determination units 321_1~321_Q are respectively coupled to the circular convolution units 322_1~322_Q and determine the plurality of peaks of the circular convolution result as the Corresponding to the cyclic frequency shift values of the Q frequency domain symbols, and converting the cyclic frequency shift values into the serial bit.

The OFDM receiving unit 330 of the spread spectrum device of the CFS-OFDMA detects the signal, performs the removal cycle preamble, converts to the frequency domain through the N-point Fourier transform unit 333, and sequentially allocates the subcarrier scheduling unit 335. Demodulation of CFS-OFDM is performed to each sub-band, including cyclic convolution, peak judgment, and gray decoding to solve the original data.

Please refer to FIG. 7. Please note that the uplink transmission of the CFS-OFDMA spread spectrum device, since multiple stations must simultaneously transmit CFS-OFDM signals in their respective sub-bands, it is necessary to synchronize to ensure that each station starts transmitting. The time error is within the allowable range. This synchronization work is usually performed by the AP to broadcast a synchronization packet in a broadcast or multicast manner. After receiving the synchronization packet, each station uses the synchronization packet as a reference for the transmission time axis. Point; after a fixed time, the Q station simultaneously transmits the Q data in the corresponding Q subbands through a CFS-OFDM signal corresponding time domain packet; in other words, for the AP end, the AP The terminal only detects time domain packets that are transmitted simultaneously with the Q workstation and combined in the air.

In an embodiment, the synchronization packet includes which frequency band should be used by each station to ensure that each station transmits the corresponding time domain packet using different frequency bands; and the synchronization packet does not limit the manner through which CFS-OFDMA can be used. The transmitting device of the spread spectrum device sends a synchronous packet to the Q station, and the invention should not be limited thereto.

The device and the method of the invention have the following characteristics: the CFS-OFDMA spread spectrum device is a CFS-OFDM-based multiplex communication technology, and the frequency band is divided into multiple sub-bands, and the AP and multiple stations simultaneously use CFS-OFDM for transmission. The transmission rate of the CFS-OFDM is increased by several times; the peak-to-average ratio of the signal power is extremely low in the uplink transmission, which can reduce the cost of the front-end amplifier; when the CFS-OFDMA spread spectrum device is uplinked, each station transmits only its own CFS-OFDM signal, the power peak-to-average ratio is very low, which can reduce the cost of the front-end amplifier; CFS-OFDMA's spread spectrum device allows multiple stations to transmit at the same time, thus greatly reducing the signal collision probability caused by multiple station transmissions.

The present invention has been described above by way of examples, and the scope of the invention is not limited thereto, and various modifications and changes may be made without departing from the scope of the invention.

Claims (10)

 A spread spectrum device for cyclic frequency shift orthogonal frequency division multiplexing access, comprising: at least one communication device, performing signal transmission according to a frequency band, the frequency band has Q sub-bands, and each sub-band has M sub-carriers, the Q The sub-bands have independent cyclic frequency shift values, and the communication device is configured to perform conversion between a series of bits and Q frequency-domain symbols by using the plurality of cyclic frequency shift values; wherein the Q frequency-domain symbols are According to the Q data of the Q station, the Q station has corresponding Q sub-bands; the Q station has corresponding bit bits and is allocated to the Q sub-bands; and the cyclic frequency shift values are one The frequency sequencing loop, and the different cyclic frequency shift values correspond to different bit values.    The spread spectrum device according to claim 1, wherein the at least one communication device comprises a receiving device and a transmitting device, and when the Q station performs uplink transmission, the transmitting device first transmits a synchronization packet to the Q through a broadcast manner. a workstation to confirm the start of transmission of each of the Q workstations; when the Q workstation receives the synchronization packet, the synchronization packet is used as a reference point of a transmission time axis, and the Q workstation is after a fixed time At the same time, the Q data is transmitted through a CFS-OFDM signal corresponding to a time domain packet in the corresponding Q subbands.    The spreading device according to claim 2, wherein the transmitting device comprises: Q modulation units, and simultaneously converting the M subcarriers in the Q subbands into the Q frequency domain symbols, the Q frequency domain symbols The element is a function of a plurality of the cyclic frequency shift values; and an OFDM transmission unit converts the Q frequency domain symbols into a time domain symbol and forms a time domain packet with the time domain symbol.    The spreading device according to claim 3, wherein the Q frequency domain symbols are arranged according to the order of the M subcarriers; or the Q frequency domain symbols may be interleaved according to the order of the M subcarriers. arrangement.   The spread spectrum device according to claim 3, wherein the time domain symbol satisfies the following formula: m = 0~ N -1 where N is the number of subcarriers per frequency domain of the OFDM transmission unit, S(k) is the frequency domain symbol, k is the kth subcarrier, and s(n) is the time domain signal n is the nth time point, m is the cyclic frequency shift value, in subcarriers, mod(.,N) is the remainder for N, N can be the power of two; and the Q frequency domain The symbol S(k) satisfies the following formula: , k =0~ N -1  The spread spectrum apparatus according to claim 5, wherein the OFDM transmission unit comprises: an N-point inverse Fourier transform unit for converting the Q frequency domain symbol combinations into the time domain symbols; a loop preamble ( a CP unit for copying a part of the symbols in the end of the time domain symbol to the front end of the time domain symbol to generate the time domain symbol; a window unit coupled to the loop preamble unit for reducing The time domain symbol interferes with the adjacent frequency band; and a packet component unit that uses the time domain symbol to generate the time domain packet.    The spreading device according to claim 3, wherein the transmitting device further comprises: Q Gray code encoding units, converting the format of the serial bit bit from the Q binary code to the Q Gray code.    The spreading device according to claim 2, wherein the receiving device comprises: an OFDM receiving unit configured to convert the time domain packet into the frequency domain symbol; and Q demodulation modules for simultaneously demodulating The Q frequency domain symbols corresponding to the M subcarriers are converted into corresponding different bit values according to the corresponding cyclic frequency shift values.    The spread spectrum apparatus according to claim 8, wherein the Q demodulation modules respectively comprise: a cyclic convolution unit, which respectively performs cyclic convolution of Q frequency domain symbols; and a peak determination unit, coupled Connecting to the circular convolution unit, and determining a plurality of peaks of the cyclic convolution result as the cyclic frequency shift values of the corresponding Q frequency domain symbols, and converting the cyclic frequency shift values into the serial bit .    The spreading device according to claim 8, wherein the OFDM receiving unit comprises: a packet detecting unit, estimating whether the time domain packet exists; and a looping preamble removing unit to remove the loop in the time domain packet a preamble to reduce to a plurality of time domain symbols; and an N-point Fourier transform unit, the Q frequency domain symbols are allocated to the M subcarriers in the Q subbands, and the time domain symbols are restored The Q frequency domain symbols are included, and the receiving device further comprises: Q Gray code decoding units for converting the format of the serial bits from the Q Gray codes to the Q binary codes.