WO2008011834A1

WO2008011834A1 - A sending and receiving method, device based on ofdm

Info

Publication number: WO2008011834A1
Application number: PCT/CN2007/070325
Authority: WO
Inventors: Bin Li; Meng Zhao; Lixia Xue; Yi Luo; Yinggang Du
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-07-19
Filing date: 2007-07-19
Publication date: 2008-01-31
Also published as: CN101110805A; CN101110805B

Abstract

A signal-sending method based on OFDM is disclosed and it includes: Divide signal into two parts at least. Map each part of the signal into an orthogonal code. Make pre-disposal to the orthogonal code and then send it out. Additionally, a signal-receiving method based on OFDM is also disclosed and it includes: Make pre-disposal to the received signal and recover channel signals including orthogonal code. Divide these channel signals into several parts according to mapping rule which is used as the signal is sent. Make corresponding disposal and error correction code decoding to these parts in combination. At the same time, a sending and receiving device based on OFDM is disclosed also. The sending and receiving system based on OFDM according to this invention wins stronger anti-jamming ability by improving the orthogonality among received spreading signal.

Description

Transceiver method and device based on orthogonal frequency division multiplexing

This application claims priority to Chinese Patent Application No. 200610106627.0, entitled "Transmission Method and System Based on Orthogonal Frequency Division Multiplexing", filed on July 19, 2006, the entire contents of which are hereby incorporated by reference. Combined in this application.

Technical field

The present invention relates to Orthogonal Frequency Division Multiplexing (OFDM) signal transmission technology in the field of mobile communications, and in particular, to a method and apparatus for transmitting and receiving based on orthogonal frequency division multiplexing.

Background technique

Cellular technology is a wireless mobile communication technology that divides a geographic area into a number of cells, called "cells." Mobile phones (or mobile phones) use this technology and are often referred to as cellular phones. In the cellular mobile communication system, the multi-carrier technology represented by Orthogonal Frequency Division Multiplexing (OFDM) has received extensive attention.

OFDM is a multi-carrier digital modulation technology. Unlike conventional single-carrier technology, such as Amplitude Modulation/Frequency Modulation (AM/FM), a single signal is transmitted at a single frequency. OFDM is in Multiple high-speed signals are simultaneously transmitted on a specially calculated orthogonal frequency. OFDM, in turn, is a multiplexing technique that multiplexes multiple signals onto different orthogonal subcarriers.

OFDM uses the data to be transmitted as frequency domain information, modulates it into a time domain signal, and transmits it on the channel, and performs inverse process demodulation at the receiving end. The modulation and demodulation of the OFDM system can be replaced by an Inverse Discrete Fourier Transform (IDFT) and a Discrete Fourier Transform (DFT), respectively. Passing N point IDFT The operation converts the frequency domain data symbols into time domain data symbols, and after carrier modulation, is sent to the channel. At the receiving end, the received signal is coherently demodulated, and then the baseband signal is subjected to an N-point DFT operation to obtain a transmitted data symbol. In practical applications, IDFT/DFT is implemented by Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT).

In order to improve the communication efficiency of low-rate signals such as control signals, there is a scheme in the prior art that uses a 1024-bit long WALSH code (Walsh code) mapping. Taking FIG. 1 as an example, it is a schematic diagram of signal transmission in the reverse control channel of the OFDM system in the prior art.

For each control channel signal, such as a channel quality indicator (CQI) 10-bit signal, first perform HADAMA D mapping, that is, select one of the 1024x1024 HADAMARD orthogonal matrices or In one column, a 1024-bit long WALSH (Walsh) code is obtained, which is then scrambled by a scrambling code. This scrambling is to distinguish other channels, so the scrambling codes of different channels are different. Then, the scrambled WALSH codes of different channels are added and combined. The combined 1024 bits are further scrambled to distinguish between different users, cells or sectors. The 1024 bits output after scrambling are divided into 8 sub-blocks, each sub-block contains 128 bits, and then 128-point FFT transform is performed for each sub-block, 128 complex values are output, and the resulting 1024 complex values are OFDM-based. It is carried on 128 subcarriers and 8 symbols.

The inventors have found that the above prior art solutions have the following problems in the implementation of the present invention: When transmitting signals through the OFDM system, there is no guarantee that the spread spectrum signals (such as WALSH codes) received by the receiving end are still orthogonal, and the reliability of the transmission is obtained. Not guaranteed. The main reason for the above situation is that due to the inherent frequency selective fading of OFDM systems and the inherent time-selective fading in mobile communications, different subcarriers are degraded at different times at different times, which leads to the transmission of control channels. The 1024-bit long WALSH orthogonal code that is transmitted is no longer orthogonal at the receiving end, so that the receiver's reception performance to the control channel is greatly degraded.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for transmitting and receiving based on orthogonal frequency division multiplexing, so that an OFDM-based transceiver system has stronger anti-interference capability, and can improve orthogonality of a spread spectrum signal received by a receiving end.

The present invention provides a transmission method based on orthogonal frequency division multiplexing, including: dividing a signal to be transmitted into at least two groups of signals; mapping each of the groups of signals to an orthogonal code; Each orthogonal code is preprocessed on the transmitting side and then transmitted.

The present invention also provides a receiving method based on orthogonal frequency division multiplexing, comprising the steps of: performing receiving side preprocessing on a received signal, and recovering a channel signal including a plurality of orthogonal codes therefrom; The channel signals of the plurality of orthogonal codes are grouped according to the orthogonal code length when the transmitting end performs mapping, and the joint orthogonal code correlation processing and error correction decoding are performed based on the grouped signals after the grouping.

The present invention further provides a transmitting device based on orthogonal frequency division multiplexing, comprising: a first grouping module, configured to divide a signal to be transmitted into at least two groups of signals; and a mapping module, configured to use the first grouping module Each of the output signals is mapped to an orthogonal code. The transmitting side pre-processing module is configured to perform pre-processing on the transmitting side of each orthogonal code output by the mapping module.

The present invention also provides a receiving apparatus based on orthogonal frequency division multiplexing, comprising: a receiving side preprocessing module, configured to perform receiving side preprocessing on the received signal, and recover a channel including multiple orthogonal codes therefrom. a second packet module, configured to group the signal including the multiple orthogonal codes into orthogonal code lengths mapped by the transmitting end; and a correlation processing and decoding module, configured to: after the grouped signals Perform joint orthogonal code correlation processing and error correction decoding.

According to the technical solution of the present invention, it can be seen that the signals to be transmitted are grouped, so that The length of each group of signals after grouping is smaller than the original length of the signal to be transmitted, and the length of one orthogonal code mapped to each group of signals is correspondingly shorter, and the time-frequency block occupied by the OFDM signal corresponding to each orthogonal code is also It is small, so it effectively resists the frequency selective fading and time selective fading inherent in the OFDM system, thereby improving the orthogonality of the spread spectrum signals received at the receiving end.

DRAWINGS

1 is a schematic diagram of signal transmission in a reverse control channel of an OFDM system in the prior art; FIG. 2 is a flowchart of a transmission method based on an OFDM system according to a first embodiment of the present invention; FIG. 3 is a first embodiment of the present invention. Schematic diagram of a transmission method based on an OFDM system;

4 is a flowchart of a receiving method based on an OFDM system according to a first embodiment of the present invention; FIG. 5 is a schematic diagram of a receiving method based on an OFDM system according to a first embodiment of the present invention;

6 is a schematic diagram showing the principle of a transmission method based on an OFDM system according to a second embodiment of the present invention;

7 is a schematic diagram showing the principle of a receiving method based on an OFDM system according to a second embodiment of the present invention;

8 is a schematic diagram showing the principle of a transmission method based on an OFDM system using other coding modes according to a second embodiment of the present invention;

9 is a schematic diagram showing the principle of an OFDM system-based receiving method using other coding modes according to a second embodiment of the present invention;

10 is a structural diagram of a transmitting and receiving apparatus based on an OFDM system according to a third embodiment of the present invention;

11 is a diagram of a transmitting and receiving apparatus based on an OFDM system according to a fourth embodiment of the present invention. Composition.

detailed description

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

In an embodiment of the present invention, the transmitting end performs error correction coding on the signal of a predetermined length, so that the transmitted signal has a certain gain in quality, and then groups the encoded signals to ensure the signal length of each group. Less than the original predetermined length, so that each group of coded signals is mapped to the orthogonal code, a shorter orthogonal code is obtained, and each orthogonal code is transmitted on consecutive time-frequency blocks of the OFDM system. Thereby, the frequency selective fading and time selective fading inherent in the OFDM system are avoided, and the orthogonal codes received by the receiving end are still orthogonal, which improves the reliability of information transmission.

The transmission and reception methods based on the OFDM system of the first embodiment of the present invention will be described in detail below. The transmission method based on the OFDM system of the present embodiment is as shown in FIG. 2.

Step 201: The transmitting end performs channel error correction coding on a predetermined length of the to-be-transmitted signal in each channel, and the error correction coding used may be a REED-MULLER ("RM") code, a Hamming code, or a BCH. Code and so on.

Specifically, please refer to FIG. 3, which is a schematic diagram of a principle of a transmission method based on an OFDM system according to a first embodiment of the present invention. When the transmitting end has 10 bits of signals to be transmitted in each of the plurality of channels, the 10-bit signals to be transmitted in each channel are respectively subjected to channel error correction coding. Taking the CQI channel as an example, the transmitting end uses the "REED - MULLER" code for channel error correction coding on the 10 bit signals to be transmitted in the CQI channel, and the encoder outputs 32 bits. Similarly, the other channels are to be transmitted. The 10-bit signal is encoded in the same way, resulting in 32 bits of the encoder output. In this step, the transmitted signal is obtained by performing channel error correction coding on a signal of a predetermined length to be transmitted. There is a certain gain in quality, which improves transmission reliability.

Next, proceeding to step 202: the transmitting end groups the encoded coded signals in each channel, and the length of each group of coded signals is less than a predetermined length. For the above case, the CQI channel is also taken as an example. The transmitting end divides the 32-bit encoded signals in the CQI channel into four groups, and each group of encoded signals has a length of 8 bits. Similarly, 32 bits of other channels are similarly The coded signals are divided into 4 groups.

Next, proceeding to step 203: the transmitting end maps each group of coded signals of each channel into an orthogonal code, such as a Walsh code.

Specifically, as shown in FIG. Similarly, taking the CQI channel as an example, the transmitting end maps each group of coded signals of the CQI channel to a Walsh code. Since each group of encoded signals has a length of 8 bits, a set of encoded signals is mapped to obtain a Walsh code having a length of ²⁸ , that is, 256 bits. That is to say, a total of 4x256=1024 bits of signals (four sets of coded signals in each channel) are obtained in each channel, which includes four Walsh codes, each of which has a length of 256 bits.

Next, proceeding to step 204: the transmitting end scrambles and combines the mapped signal and the pilot signal of each channel with corresponding channel scrambling codes.

Specifically, as shown in Figure 3. The transmitting end scrambles 1024 bits in each channel with corresponding channel scrambling codes, and different control channels use different scrambling codes to distinguish the control channels. For example, 1024 bits in the CQI channel are scrambled with the scrambling code of the CQI channel to obtain 1024 bits after scrambling. The transmitting end combines the signals scrambled by the channel scrambling code in each channel to obtain 1024 bit signals.

Next, proceeding to step 205, the transmitting end scrambles the combined signal with a cell scrambling code. Specifically, as shown in Figure 3. The transmitting side scrambles the combined 1024 bit signals with a cell scrambling code to distinguish different cells or sectors.

Next, proceed to step 206: the transmitting end performs DFT transformation on the signal scrambled by the cell scrambling code, Usually implemented by FFT transform.

Next, proceeding to step 207: the transmitting end modulates the DFT-converted signal into an OFDM signal transmission, where the OFDM signal corresponding to each orthogonal code is transmitted on consecutive time-frequency blocks. Specifically, for the above case, the transmitting end may divide the 1024-bit signal scrambled by the cell scrambling code into 8 sub-blocks before performing DFT conversion on the signal, so that each sub-block contains 128 bits, continuously. The two sub-blocks correspond to a Walsh orthogonal code. And performing DFT transform on a total of 1024 bit signals of 8 sub-blocks, modulating 1024 bit signals included in the 8 sub-blocks into OFDM signals, and mapping to 128 sub-carriers of an OFDM system for transmission, the 1024 A total of 8 OFDM symbols are required for transmission of bit information. For example, if an OFDM system has a total of 512 subcarriers, then the OFDM signal modulated by the 8 subblocks is mapped to 128 subcarriers of the 512 subcarriers and transmitted through 8 OFDM symbols. It should be noted that two consecutive sub-blocks corresponding to each Walsh code need to be transmitted on consecutive subcarriers and consecutive OFDM symbols.

A person skilled in the art can understand that the processing performed after the packet is mapped to an orthogonal code by the transmitting end includes, but is not limited to, the manner shown in the above steps 204 to 207, for example, when there is only one channel to be transmitted. In this case, there are no relevant steps for the merge. Therefore, the processing process after the packet mapping may be collectively referred to as the pre-processing process on the transmitting side, and may be implemented in various specific manners according to the actual situation, and is not limited to the manner shown in steps 204 to 207 in this embodiment. .

In the prior art, a 10-bit signal in a CQI channel is mapped to obtain a 1024-bit orthogonal code. In the present embodiment, a 10-bit signal in a CQI channel is error-correction-coded to obtain 32 bits. However, since each group of coded signals has only 8 bits after being grouped, each orthogonal code obtained after mapping has only 256 bits. Moreover, since each orthogonal code is shorter in length, and each The OFDM signal corresponding to the orthogonal code is transmitted on consecutive subcarriers and consecutive OFDM symbols, thereby effectively avoiding the frequency selective fading inherent in the OFDM system and the time selective fading inherent in mobile communication, thereby ensuring reception. The orthogonal codes in each channel received by the terminal are still orthogonal, thereby effectively avoiding mutual interference between users and achieving better reception quality, especially for high-speed mobile user equipment, and the improvement of reception quality is more remarkable.

It should be noted that the transmitting end may also divide the 1024 bit signals into 16 sub-blocks, each sub-block contains 64 bits, and the consecutive 4 sub-blocks correspond to a 256-long Walsh code, and the transmitting end only needs to guarantee one corresponding to one. The OFDM signal of the Walsh code is transmitted on consecutive subcarriers and consecutive OFDM symbols, so as to avoid the selective fading of frequency and time inherent in the OFDM system.

The receiving method corresponding to the first embodiment of the above-described OFDM system-based transmission method is as shown in FIG.

Step 401: The receiving end demodulates the received OFDM signal.

Next, proceed to step 402: The receiving end performs IDFT conversion on the demodulated signal. For the above case, please refer to FIG. 5 in detail, which is a schematic diagram of the principle of the OFDM system-based receiving method according to the first embodiment of the present invention. The receiving end extracts the samples on the 128 subcarriers in each OFDM symbol, and performs IDFT transformation on them, and collects 8 symbols in total, that is, a total of 1024 bits are obtained.

Next, proceeding to step 403: The receiving end de-interfers the IDFT-converted signal with a cell scrambling code. Specifically, the receiving end distinguishes the signals of the respective cells by multiplying the obtained 1024 bit signals by conjugate multiplexing of the cell scrambling codes.

Then, proceeding to step 404: the receiving end performs descrambling on the descrambling sequence by using the channel scrambling code. Specifically, as shown in FIG. 5, the receiving end further decodes the signal descrambled by the cell scrambling code by using a channel scrambling code. The channel signal of each channel is obtained.

Next, proceeding to step 405: the receiving end groups the channel signals descrambled by the channel scrambling code by the orthogonal code length mapped by the transmitting end. For the above case, since the length of each Walsh code mapped in the transmitting end is 256, the receiving end groups the 1024 bit signals of each channel obtained by descrambling the channel scrambling code into groups of 256 bits each. , get 4 sets of signals.

Next, proceeding to step 406: the receiving end performs correlation processing and error correction decoding of each group of signals to obtain a decoding result. Specifically, for each channel, the receiver is at all possible decoding junctions.

2

In the sequence, find the corresponding sequence with the largest £ £ 3⁄4 _W W value, and output the sequence as the decoding knot k=lm=\. Where x _k , _m is the mth bit of the kth group of signals, and _3⁄4m is the _mth of the orthogonal code corresponding to the kth group of signals encoded and grouped in the same manner as the transmitting end Bit, A is the number of coded signal groups, and B is the length of the orthogonal code.

For the above case, if the four signals of the CQI channel obtained by the receiving end are

•^j 1? 2 " · " 256 , 1? 2 " · ·, ^2 256 , ^3 1? 2 " · " 256 ^4 1? 2 " · " 256 '>^^_^^^·^Ι3⁄4· ^目1^1 The way to possible translation After the code results are encoded, they are grouped in the same way as the sender, and the corresponding orthogonal codes obtained after grouping are _{Wl l} , _{Wl 2} , ..., w _{1 256} , w _{2 1} , w _{2 2} ,...,w _{2 256} , w _{3 1} ,w _{3 2} ,...,w _{3 256} ^ w _{4 1} ,w _{4 2} ,...,w _{4 256} , then, in all possible translations Code knot

4 256

The largest sequence of values found in the result, which is the sender's

k=l

The decoding result of the CQI channel.

It should be noted that the purpose of performing channel error correction coding on the signal to be transmitted by the transmitting end is to improve the transmission reliability. Therefore, if only the orthogonality of the orthogonal code received by the receiving end is considered, The transmitting end may also perform channel error correction coding on the transmission signal, and directly group and map the signals to be transmitted. Therefore, if the transmitting end does not perform channel error correction coding on the signal to be transmitted, then when the receiving end finds the sequence with the largest value as the decoding result, the

The possible decoding result is the mth bit of the orthogonal code corresponding to the kth group signal obtained by the same packet as the transmitting end, and A is the number of signal groups. As can be seen from the 3⁄4 _w described in step 406, the essence is a certain channel letter.

The grouped signals of m=\ are combined and detected to find the required decoding result, that is, the joint orthogonal code correlation processing and error correction decoding are performed.

In addition, when the sender is introduced, it is mentioned that the processing after the grouping and mapping to the orthogonal code can be understood as the sending side pre-processing, and the specific implementation of the process can be determined according to the actual situation. Therefore, correspondingly, at the receiving end, steps 401 to 404 can also be understood as a receiving side of steps 401 to 404 shown in this embodiment. The purpose of the transmission side pre-processing is to recover a channel signal comprising a plurality of orthogonal codes from the received signal, thereby providing a desired signal for subsequent processing of the packet and the orthogonal code.

The second embodiment of the present invention is substantially the same as the first embodiment in the transmission and reception method based on the OFDM system, except that in the first embodiment, the transmitting end only scrambles the signals of the respective control channels with corresponding channels. After the scrambling and combining, in the embodiment, the transmitting end scrambles the pilot signal with the pilot channel scrambling code, and scrambles the scrambled pilot signal and the channel scrambling code of each control channel. The signals are combined, as shown in FIG. 6, which is a schematic diagram of a transmission method based on an OFDM system according to a second embodiment of the present invention. Correspondingly, using the channel scrambling code to descramble at the receiving end The obtained pilot signal is subjected to channel estimation, and the other channel signals are coherently demodulated according to the obtained channel estimation, and then the coherently demodulated signals of the other channels are separately grouped and orthogonal code correlated. The steps of processing and error correction decoding are as shown in FIG. Wherein, when the receiving end performs the correlation processing and the error correction decoding of the orthogonal code, in all possible decoding result sequences, find the corresponding sequence with the largest value of the ^^έ^^, the sequence Output as a decoding result. Where x _k , _m is

J

The mth bit of the kth group signal, _3⁄4m is the mth bit of the orthogonal code corresponding to the kth group signal encoded and grouped by the same way as the transmitting end, and Re represents the real part , * represents the conjugate, _m is the channel estimate, A is the number of coded signals, and B is the length of the orthogonal code. The transmitting end scrambles the pilot signal, and combines the scrambled pilot signal with the scrambled signal of each channel, so that the receiving end can perform the pilot signal obtained after the descrambling. Channel estimation, and coherent demodulation based on the obtained evaluation results, further improves the reception quality. Similarly, if the transmitting end does not perform channel error correction coding before performing the packet, the _3⁄4m is the _mth of the orthogonal code corresponding to the kth group signal obtained by the same packet as the transmitting end. Bits, A is the number of signal groups.

It should be noted that, since the signal to be transmitted of each channel can be error-corrected and encoded in various manners in the transmitting end, the encoded signal in each channel is not necessarily 32 bits, and is not necessarily divided into four. group. Assuming that the encoded signal is mxn bits and is divided into m groups, the transmission mode and the reception mode are as shown in FIG. 8 and FIG. 9, respectively, wherein when m is 4, n is 8; when m is 8, n is 7; When m is 16, n is 6.

A third embodiment of the present invention is based on an embodiment of a transmitting apparatus and a receiving apparatus of an OFDM system, as shown in FIG. In the transmitting device, the encoding module 110 is configured to perform error correction coding on the signal to be transmitted of a predetermined length, and output the signal; the first grouping module 120 is configured to output the signal of the encoding module. Dividing into at least two sets of coded signals and outputting, the length of each set is less than the predetermined length; 130 mapping module, configured to map each set of coded signals output by the first grouping module to an orthogonal code and output; The scrambling module 140, the mapped orthogonal codes of the channels output by the mapping module are scrambled and outputted by the corresponding channel scrambling code, and the merging module 150 is configured to scramble the first scrambling module. The signals of the subsequent channels are combined and output; the second scrambling module 160 is configured to perform scrambling on the signal output by the merging module, and output the signal; the DFT transform module 170 is configured to use the second scrambling module. The output signal is subjected to DFT conversion and output; the modulation module 180 is configured to modulate the signal output by the DFT transform module into an OFDM signal and output the signal; and the transmitting module 190 is configured to send the OFDM signal output by the modulation module. The sending module 190 transmits the OFDM signal corresponding to each orthogonal code on consecutive time-frequency blocks.

Similar to the embodiment of the transmitting method of the present invention, the transmitting end may not perform channel error correction encoding before the packet, and therefore the encoding module 110 may not be included in the transmitting end. And the first scrambling module 140, the merging module 150, the second scrambling module 160, the DFT transform module 170, the modulating module 180, and the sending module 190 can be summarized as a transmitting side preprocessing module, and the specific part of the sending side preprocessing module Implementations include, but are not limited to, the aforementioned internal structures.

The receiving device includes a receiving module 210 for receiving an OFDM signal, a demodulating module 220, configured to demodulate and output the OFDM signal received by the receiving module, and an IDFT transform module 230, configured to output the demodulation module. The signal is subjected to IDFT conversion and output; the second descrambling module 240 is configured to descramble the signal output by the IDFT transform module by using a cell scrambling code; and the first descrambling module 250 is configured to: the second descrambling module The output signal is descrambled and outputted by the channel scrambling code; the second grouping module 260 is configured to group the signals output by the first descrambling module according to the orthogonal code length mapped by the transmitting end, and output the same; 270. The group of signals output by the second grouping module are subjected to orthogonal code correlation processing and error correction decoding, and then output. Corresponding to the specific implementation of the sending device, the receiving module 210, the demodulating module 220, the IDFT transform module 230, the second descrambling module 240, and the first descrambling module 250 may be summarized as a receiving side preprocessing module, and the receiving The side pre-processing module provides the second grouping module 260 with its required channel signal including a plurality of orthogonal codes, and specific implementations of the receiving-side pre-processing module include, but are not limited to, the aforementioned internal structure.

The correlation processing and decoding module 270 is specifically configured to find out in all possible sequences of decoding results.

2

Corresponding £ ^X k, m ^W k, the maximum value of the sequence, this sequence as a decoding result, wherein, x _km is the m-th bit of the k-th group _signals, ¾m decoding result is possible with the sender via the same The mode encodes and encodes the mth bit of the orthogonal code corresponding to the kth group of signals, A is the number of coded signal groups, and B is the length of the orthogonal code. If the transmitting device does not perform channel error correction coding (ie, without the encoding module 110) before the packet, the _3⁄4m is an orthogonal code corresponding to the kth group signal obtained after the same decoding result as the transmitting end. The mth bit, A is the number of signal groups.

The transmitting and receiving apparatus based on the OFDM system of the fourth embodiment of the present invention is substantially the same as that of the third embodiment, as shown in FIG. 11, except that in the transmitting apparatus, the first scrambling module 140 is also used for the pair. The pilot signal is scrambled by the pilot channel scrambling code, and the combining module 150 combines the signals of the channels scrambled by the first scrambling module 140 and the pilot signals, and outputs the signals to the DFT transform module 170. In the receiving device, a channel estimation module 290 and a decoherence module 280 are added. The channel estimation module 290 is configured to perform channel estimation according to the pilot signal obtained after descrambling by the first descrambling module 250. The decohering module 280 is configured to use the estimated value obtained by the channel estimation module 290 for each channel signal. Coherent demodulation is performed and output to the second grouping module 260. The coherently demodulated channel signals are grouped by the second grouping module 260 according to the orthogonal code length mapped by the transmitting end, and then output to the correlation processing and error correction decoding module ₂₇₀ . Receiving device by including a pilot signal in a signal transmitted by the transmitting device The channel estimation can be performed according to the pilot signal obtained after descrambling, and coherent demodulation is adopted according to the obtained estimation result, thereby further improving the reception quality.

In the same manner as the above-described transmitting and receiving apparatus according to the third embodiment, the transmitting apparatus 110 may not be provided in the transmitting apparatus. Moreover, the receiving module 210, the demodulating module 220, the IDFT transform module 230, the second descrambling module 240, and the first descrambling module 250, the channel estimating module 290, and the decoherence module 280 in the receiving device may be summarized as the receiving side. Preprocessing module.

It can be seen from the foregoing embodiments of the present invention that, by adopting a technique of grouping a signal to be transmitted at a transmitting end and then mapping it to an orthogonal code, the length of each orthogonal code mapped is correspondingly shorter, and thus each The OFDM signal corresponding to the orthogonal code occupies a small time-frequency block, so it effectively resists the frequency selective fading and time-selective fading inherent in the OFDM system, thereby improving the spread spectrum signal received by the receiving end (eg, Orthogonality of orthogonal codes).

Further, by performing the technique of error correction coding before grouping the signals to be transmitted, the signal has a large gain in transmission quality.

Further, the transmitting end distinguishes the transmission signals of the plurality of channels by scrambling the channel scrambling code, and distinguishes the transmission signals of the different cells by the scrambling of the cell scrambling code, thereby effectively utilizing the spectrum resources.

Finally, the transmitting end performs scrambling on the pilot signal, and combines the scrambled pilot signal with the scrambled signal of each channel, and the receiving end performs channel estimation according to the descrambled pilot signal. The value, and coherent demodulation based on the obtained evaluation result, further improves the reception quality.

Although the invention has been illustrated and described with reference to the preferred embodiments of the present invention, it will be understood The spirit and scope of the invention.

Claims

Rights request

A transmission method based on orthogonal frequency division multiplexing, characterized in that it comprises:

Dividing the signal to be transmitted into at least two groups of signals;

Mapping each of the sets of signals to an orthogonal code;

The mapped orthogonal codes are preprocessed on the transmitting side and then transmitted.

The method according to claim 1, wherein before the dividing the signal to be transmitted into at least two groups of signals, the method further comprises: performing error correction coding on a sequence of information of a predetermined length in the channel to form the channel. Coded signal to be transmitted;

The step of dividing the signal to be transmitted into at least two groups of signals comprises dividing the coded signals to be transmitted in the channel into at least two groups of signals, wherein the length of each group of signals is less than a predetermined length of the sequence of information.

The method according to claim 1, wherein the signal corresponding to each orthogonal code is sent by a continuous time-frequency block.

The method according to any one of claims 1 to 3, wherein the step of performing the pre-processing of the mapped orthogonal codes on the transmitting side comprises:

Performing discrete Fourier transform on each of the mapped orthogonal codes;

The discrete Fourier transformed signal is modulated into an orthogonal frequency division multiplexed signal; and the modulated orthogonal frequency division multiplexed signal is transmitted.

The method according to claim 4, wherein, when the signal to be transmitted is included in the at least two channels, before the performing the discrete Fourier transform, the method further includes:

The orthogonal codes and pilot signals mapped in each channel are respectively scrambled by corresponding channel scrambling codes;

The signals after the above scrambling are combined.

A receiving method based on orthogonal frequency division multiplexing, comprising: performing receive side preprocessing on a received signal, and recovering a channel signal including a plurality of orthogonal codes therefrom;

The channel signals including the plurality of orthogonal codes are grouped by orthogonal code lengths when mapped by the transmitting end, and combined orthogonal code correlation processing and error correction decoding are performed based on the grouped signals.

7. The method according to claim 6, wherein: said performing orthogonal code correlation processing and error correction decoding step comprises: finding a corresponding £ value in all possible decoding result sequences; Maximum order

Column, the sequence is taken as the decoding result, where x _k , _m is the mth bit of the kth group signal, and w _km is the kth group after the possible decoding result is encoded and grouped in the same manner as the transmitting end The mth bit of the orthogonal code corresponding to the signal, A is the number of coded signal groups, and B is the length of the orthogonal code.

8. The method according to claim 6, wherein: performing the joint orthogonal code correlation processing and the error correction decoding step comprises: finding a corresponding maximum value among all possible decoding result sequences Preface

Column, the sequence is taken as the decoding result, where x _k , _m is the mth bit of the kth group signal, and w _km is the kth group signal after the possible decoding result is grouped in the same manner as the transmitting end The mth bit of the corresponding orthogonal code, A is the number of signal groups, and B is the length of the orthogonal code.

The method according to any one of claims 6 to 8, wherein the receiving side pre-processing step of the received signal comprises:

Demodulating the received signal; The demodulated signal is subjected to inverse discrete Fourier transform to obtain a channel signal including a plurality of orthogonal codes.

The method according to claim 9, wherein when the received signal includes signals of at least two channels, the receiving side pre-processing step further comprises: after the inverse discrete Fourier transform The signal is descrambled by the channel scrambling code to obtain a channel signal including a plurality of orthogonal codes and a pilot signal; the pilot signal is used for channel estimation, and the other channels are included according to the channel estimation. Channel signals of orthogonal codes are coherently demodulated;

The step of grouping the channel signals including the plurality of orthogonal codes is specifically: grouping the coherently demodulated channel signals including the plurality of orthogonal codes.

The method according to claim 10, wherein the performing the orthogonal code correlation processing and the error correction decoding step comprises:

a sequence, the sequence is used as a decoding result, where x _k , _m is the mth bit of the kth group of signals, and _3⁄4m is the kth group signal after the possible decoding result is encoded and grouped in the same manner as the transmitting end The mth bit of the corresponding orthogonal code, Re represents the real part, * represents the conjugate, h _k , _m is the channel estimate, A is the number of coded signals, and B is the length of the orthogonal code.

12. A transmitting device based on orthogonal frequency division multiplexing, comprising:

a first grouping module, configured to divide the signal to be transmitted into at least two groups of signals;

a mapping module, configured to map each group of signals output by the first grouping module to an orthogonal code;

The sending side pre-processing module is configured to perform pre-processing on the transmitting side of each orthogonal code output by the mapping module.

The transmitting device according to claim 12, wherein the transmitting side preprocessing module comprises:

a discrete Fourier transform module, configured to perform discrete Fourier transform on each orthogonal code output by the mapping module;

a modulation module, configured to modulate a signal output by the discrete Fourier transform module into an orthogonal frequency division multiplexing signal;

And a sending module, configured to send an orthogonal frequency division multiplexing signal output by the modulation module.

The transmitting device according to claim 13, wherein, when there is a signal to be transmitted in at least two channels, the transmitting side pre-processing module further includes a first scrambling module and a merging module; a scrambling module, configured to scramble each orthogonal code of each channel output by the mapping module with a corresponding channel scrambling code, and scramble the pilot signal with a pilot channel scrambling code;

The merging module is configured to combine the signals output by the first scrambling module and output the signals to the discrete Fourier transform module.

The transmitting device according to any one of claims 12 to 14, wherein the transmitting side preprocessing module transmits the signal corresponding to each orthogonal code in a continuous time frequency when transmitting Sent on the block.

The transmitting device according to any one of claims 12 to 14, further comprising: an encoding module: configured to perform error correction coding on a sequence of information of a predetermined length in the channel to form a to-be-transmitted channel in the channel. Coded signal

The first grouping module is specifically configured to divide the coded signals to be transmitted in the channel into at least two groups of signals, wherein a length of each group of signals is less than a predetermined length of the information sequence.

17. A receiving device based on orthogonal frequency division multiplexing, characterized in that

a receiving side preprocessing module, configured to perform preprocessing on the receiving side of the received signal, and recover therefrom a channel signal comprising a plurality of orthogonal codes;

a second grouping module, configured to group the signals including the plurality of orthogonal codes by orthogonal code lengths mapped by the transmitting end;

And a correlation processing and decoding module, configured to perform joint orthogonal code correlation processing and error correction decoding on the grouped signals.

The receiving device according to claim 17, wherein the receiving side preprocessing module comprises:

a receiving module, configured to receive an orthogonal frequency division multiplexing signal from the transmitting end;

a demodulation module, configured to demodulate the orthogonal frequency division multiplexed signal;

And an inverse discrete Fourier transform module, configured to perform inverse discrete Fourier transform on the demodulated signal to obtain a channel signal including a plurality of orthogonal codes.

19. The receiving device according to claim 17 or 18, wherein

The correlation processing and decoding module is specifically configured to find out in all possible decoding result sequences

2

Corresponding to the sequence with the largest value of £ £ ^X k,m ^W k„, the sequence is used as the decoding result, where _1⁄2

k=lm=l is the mth bit of the kth group of signals, and _3⁄4m is the mth bit of the orthogonal code corresponding to the kth group of signals encoded and grouped in the same manner as the transmitting end. , A is the number of coded signal groups, and B is the length of the orthogonal code.

The receiving device according to claim 17 or 18, wherein the received signal comprises a signal of at least two channels, and the receiving side preprocessing module further comprises:

a first descrambling module, configured to descramble the signal subjected to the inverse discrete Fourier transform by using a channel scrambling code to obtain a channel signal and a pilot signal including a plurality of orthogonal codes;

a channel estimation module, configured to perform channel estimation on the pilot signal; And a decoherence module, configured to perform coherent demodulation on the channel signals of the other channels including the plurality of orthogonal codes according to the channel estimation, and then output to the second grouping module.

21. The receiving device according to claim 20, wherein

The correlation processing and decoding module is specifically configured to find a sequence corresponding to the largest value of the corresponding 1^; 3⁄4„^^, „^ in all possible decoding result sequences, and use the sequence as a decoding result. Where x _k , _m is

J

The mth bit of the kth group signal, _3⁄4m is the mth bit of the orthogonal code corresponding to the kth group signal encoded and grouped by the same way as the transmitting end, and Re represents the real part , * represents the conjugate, _m is the channel estimate, A is the number of coded signals, and B is the length of the orthogonal code.