WO2008083605A1

WO2008083605A1 - A method and device for transmitting/receiving preamble signal based on ofdm

Info

Publication number: WO2008083605A1
Application number: PCT/CN2007/071398
Authority: WO
Inventors: Bin Li; Lixia Xue; Yi Luo
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-12-31
Filing date: 2007-12-29
Publication date: 2008-07-17
Also published as: CN101212437B; CN101212437A

Abstract

A method and device for transmitting/receiving preamble signal based on OFDM communication system are provided. The method includes: at the transmitting side, mapping a part of the preamble information in FPCH (Forward Physical Channel) to the signal code sequence, mapping the signal code sequence as a frequency domain signal to a sub-carrier of OFDM symbol, and transmitting it after OFDM modulation. At the receiving side, when receiving the preamble information in the FPCH, OFDM de-modulating the received signal, performing the correlation detecting between the de-modulated signal and the various possible signal code sequence, the information corresponding to the most correlative signal code sequence is the information transmitted by the transmitting side.

Description

OFDM-based prefix signal transceiving method and device

This application claims priority to Chinese Patent Application No. 200610063879.X, filed on December 31, 2006, entitled "OFDM-based prefix signal transmission and reception method and device", the entire contents of which are incorporated by reference. Used in conjunction with this application.

Technical field

The present invention relates to the field of wireless communications, and more particularly to an OFDM based communication technology.

Background technique

In recent years, multi-carrier transmission technology represented by Orthogonal Frequency Division Multiplexing (OFDM) has received extensive attention. Multi-carrier transmission decomposes data streams into several independent sub-data. The stream, each sub-stream will have a much lower bit rate. Demodulating the corresponding subcarriers with such low bit rate formed low rate multi-state symbols constitutes a plurality of low rate symbol parallel transmission transmission systems.

As a representative multi-carrier transmission technique, OFDM divides the spectrum into a number of sub-carriers, each of which is modulated with a lower data rate.

The OFDM system 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 Inverse Discrete Fourier Transform (IDFT) and Discrete Fourier Transform (DFT), respectively. The frequency-domain data symbols are transformed into time-domain data symbols by an N-point IDFT operation, and after carrier modulation, are transmitted 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). The adoption of FFT technology greatly reduces the complexity of OFDM systems, coupled with high-performance information processing devices such as Programmable Logic Device (PLD), Digital Signal Processor (DSP). The development and application of "Microprocessor" (Micro Processor, abbreviated as "μΡ") makes the implementation of OFDM system easier and becomes the most widely used multi-carrier transmission scheme.

In some scenarios using OFDM technology, orthogonal code sequences need to be modulated as information bits. Transmission on OFDM symbols. The prefix of the superframe in the forward physical channel of the 3rd Generation Partnership Project 2 ("3GPP2") Air Interface Evolution ("AIE") needs to be based on the orthogonal code. The sequence is modulated and transmitted on OFDM symbols. The orthogonal code sequence includes a Walsh code sequence, a DFT code sequence, and the like.

Specifically, the forward physical channel of the 3GPP2 AIE is composed of superframes, and each superframe has a preamble (prefix) for performing forward synchronization acquisition, identifying cells, broadcasting system parameters, and the like. The Preamble is composed of 8 OFDM symbols, and the last 3 OFDM symbols are called TDM1, TDM2, and TDM3. TDM1 is used to transmit synchronization acquisition and frequency offset estimation sequences. TDM2, TDM3 transmits Walsh code sequence, TDM2 is used to transmit sector identification information, TDM3 is used to transmit system information, and F-OSICH information is carried at the same time for power control.

For a 5 MHz OFDM system, the number of IFFT points used for OFDM modulation is 512 points, and the length of the Walsh code sequence that TDM2 needs to transmit is 512 bits. In the prior art, a Walsh code sequence of length 512 is first transformed into a frequency domain signal by a DFT of 512 points, and then mapped to subcarriers modulated to OFDM symbols by subcarriers. For a certain bandwidth OFDM system, it is usually necessary to reserve a certain number of guard subcarriers on both sides of the frequency band to prevent the spectrum of the transmitted signal from leaking and to interfere with other frequency bands. If the number of guard subcarriers is Ng and there is also a zero frequency subcarrier, the useful subcarrier is 512-Ng-1. That is to say, the frequency signal of the Walsh code sequence of the DFT of 512 points can only be mapped to 512-Ng-l effective subcarriers when mapping, usually Ng is odd, and needs to be truncated at both ends of the spectrum (Ng -l)/2 and (Ng+l)/2 points can be mapped onto OFDM symbols. After the frequency domain signal of the Walsh code sequence is mapped to the subcarrier of the OFDM symbol, it is transmitted through the antenna after OFDM modulation (IFFT conversion), as shown in Fig. 1.

Since the transmitting end uses 512-point DFT and 512-point IFFT, the transmitted signal is a time domain signal. Therefore, the receiving end needs to process all possible multipath signals in time domain. As shown in FIG. 2, the receiving end needs to All received time domain signals are subjected to multiple correlation detections, and the sequence of the transmitted Walsh codes is determined according to the maximum correlation peak thereof, thereby identifying different cells and obtaining related system parameter information. The complexity of time domain processing results in very high complexity for the receiver. In addition, due to the protection of the subcarriers, the guard band frequency of the Walsh code sequence after DFT transformation will be intercepted, which affects the frequency domain integrity of the Walsh code, and the performance of the receiving end detection is greatly reduced.

Summary of the invention Embodiments of the present invention provide a method and a device for transmitting and receiving a prefix signal based on OFDM, so that the complexity of the receiver is greatly reduced.

An embodiment of the present invention provides an OFDM-based prefix signal sending method, including the steps of: mapping partial prefix information in a forward physical channel into a signal code sequence, and mapping the signal code sequence as a frequency domain signal to an OFDM symbol. On the subcarrier, it is transmitted after OFDM modulation.

An embodiment of the present invention further provides an OFDM-based prefix signal receiving method, including the following steps: when receiving partial prefix information in a forward physical channel, performing OFDM demodulation on the received signal, and demodulating the received signal The signal is correlated with various possible signal code sequences, and the information corresponding to the most relevant signal code sequence is used as the information transmitted by the transmitting end.

An embodiment of the present invention further provides an OFDM-based prefix signal sending apparatus, including: a unit for mapping partial prefix information in a forward physical channel into a signal code sequence; and using the signal code sequence as a frequency domain The signal is mapped to a unit on a subcarrier of the OFDM symbol; a unit for performing OFDM modulation on the signal mapped to the OFDM symbol subcarrier.

An embodiment of the present invention further provides an OFDM-based prefix signal receiving apparatus, including: a unit for performing OFDM demodulation on the received signal when receiving partial prefix information in a forward physical channel; And a unit for performing correlation detection on the demodulated signal and various possible signal code sequences; and information for using the signal code sequence with the highest degree of correlation obtained by the correlation detection as a unit of information transmitted by the transmitting end.

In the embodiment of the present invention, the partial prefix information in the forward physical channel is mapped to a signal code sequence, and the signal code sequence is mapped as a frequency domain signal to a subcarrier of the OFDM symbol, and modulated by OFDM. When receiving the partial prefix information in the forward physical channel, the receiving end performs OFDM demodulation on the received signal, and performs correlation detection on the demodulated signal and various possible signal code sequences, and the signal code with the highest correlation degree is obtained. The information corresponding to the sequence is used as information transmitted by the transmitting end. Since the demodulated frequency domain information is detected at the receiving end, it is not necessary to separately detect all possible multipath signals, so that the complexity of the receiver is greatly reduced. DRAWINGS

1 is a schematic diagram of a transmitting end of an OFDM system in the prior art; 2 is a schematic diagram of a receiving end of an OFDM system in the prior art;

3 is a flowchart of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a first embodiment of the present invention;

4 is a schematic diagram of a first mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a first embodiment of the present invention;

5 is a schematic diagram of a second mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a first embodiment of the present invention;

6 is a schematic diagram of a third mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a first embodiment of the present invention;

7 is a schematic diagram of a fourth mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a first embodiment of the present invention;

8 is a flowchart of a receiving end in an OFDM-based prefix signal transmitting and receiving method according to a first embodiment of the present invention;

9 is a flowchart of a receiving end in an OFDM-based prefix signal transmitting and receiving method according to a second embodiment of the present invention;

FIG. 10 is a schematic diagram of a mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a third embodiment of the present invention; FIG.

11 is a flowchart of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a fourth embodiment of the present invention;

12 is a schematic diagram of a first mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a fourth embodiment of the present invention;

13 is a schematic diagram of a second mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a fourth embodiment of the present invention;

14 is a schematic diagram of a third mapping manner of a transmitting end in an OFDM-based prefix signal transmitting and receiving method according to a fourth embodiment of the present invention;

Figure 15 is a flowchart of a receiving end in an OFDM-based prefix signal transmitting and receiving method according to a fourth embodiment of the present invention.

detailed description

In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention will be described below with reference to the accompanying drawings. Further details are described.

At the transmitting end, the partial prefix information in the forward physical channel is mapped into a signal code sequence, and the signal code sequence is mapped as a frequency domain signal to a subcarrier of the OFDM symbol, and is transmitted after being modulated by OFDM. When receiving the partial prefix information in the forward physical channel, the receiving end performs OFDM demodulation on the received signal, and performs correlation detection on the demodulated signal and various possible signal code sequences, and the signal code with the highest correlation degree is obtained. The information corresponding to the sequence is used as information transmitted by the transmitting end. Since the receiving end detects the demodulated frequency domain information, it is not necessary to separately detect all possible multipath signals, so that the complexity of the receiver is greatly reduced.

A first embodiment of the present invention relates to an OFDM-based prefix signal transmission and reception method. At the transmitting end, as shown in FIG. 3, in step 310, the transmitting end maps the information to be transmitted, such as TDM2 and/or TDM3 in the prefix of the forward physical channel, to a Walsh orthogonal code sequence of length 512.

Next, proceeding to step 320, in order to further improve the performance in the case of high-speed movement, the Walsh orthogonal code sequence obtained by the mapping is interleaved by the interleaver. The Walsh code sequence is regular, and the existence of multipath fading will destroy the inherent properties of the Walsh code (such as orthogonality). At the same time, the protection subcarrier continuously cuts off some Walsh codes, which will destroy some important characteristics of the Walsh code (such as decreased correlation performance and reduced correlation peak), so that it cannot be correctly recognized by the receiving end. Interleaving the Walsh code to be transmitted makes the effects of multipath fading and guard subcarriers uniform, so that even if the frequency domain signal of the guard band or the zero frequency part is lost, it is only equivalent to introducing some noise, which does not cause the receiving end to be completely unable to Identify and improve the performance of signal code detection.

Next, proceeding to step 330, the interleaved code sequence is mapped onto the subcarriers of the OFDM symbol, and the code sequence on the subcarrier and/or the zero frequency partial subcarrier serving as the guard band is set to zero. In this embodiment, the DFT transform is not performed on the code sequence, so that the demodulated frequency domain information can be directly detected at the receiving end, and it is not necessary to separately detect all possible multipath signals, thereby greatly reducing the receiver of the receiving end. the complexity.

For the code sequences corresponding to TDM2 and TDM3 in the prefix of the forward physical channel, there may be multiple mapping methods. For example, the code sequences corresponding to TDM2 and TDM3 may be mapped to the first 256 consecutive subcarriers of the two OFDM symbols, respectively. And the last 256 consecutive subcarriers, as shown in FIG. 4; or, the code sequences corresponding to TDM2 and TDM3 are alternately mapped to 4 links of two OFDM symbols. On the remaining 128 subcarriers, as shown in FIG. 5; or, according to the importance of the information, map the code sequence corresponding to the more important TDM2 on 256 consecutive subcarriers in the middle part of the OFDM symbol, and the code corresponding to TDM3 The sequence is mapped on two consecutive 128 subcarriers outside the OFDM symbol, as shown in FIG. 6; or, the code sequences corresponding to TDM2 and TDM3 are mapped on other subcarriers other than the subcarrier used as the guard band, such as Figure 7; and so on.

Next, proceeding to step 340, the code sequence after the zero is subjected to OFDM modulation, and then transmitted through the antenna.

At the receiving end, as shown in FIG. 8, in step 810, the receiving end performs OFDM demodulation on the received signal to obtain a signal on the subcarrier transmitting the information of the transmitting end.

Next, proceeding to step 820, in order to prevent the noise signal on the sub-carrier corresponding to the guard band and the zero-frequency portion from interfering with the subsequent detection, the signals on the sub-carrier and the zero-frequency partial sub-carrier used as the guard band are set to zero, Improve the accuracy of the test.

In step 830, all possible 9-bit codes are generated by the sequence generator, and 512-bit Walsh code mapping is performed thereon.

Next, proceeding to step 840, the Walsh code sequences obtained by the mapping are interleaved. This interleaving is the same as the sender.

Next, proceeding to step 850, the signals after the zeroing of the interleaved Walsh code sequences are correlated. It can be divided into 4 blocks for correlation detection. In this embodiment, the received signal is not subjected to IDFT conversion, so that the demodulated frequency domain information can be directly detected at the receiving end, and it is not necessary to separately detect all possible multipath signals, thereby greatly reducing the receiver. The complexity.

Next, proceeding to step 860, the Walsh code sequence with the highest degree of correlation is selected, and the information corresponding to the Walsh code sequence is used as information transmitted by the transmitting end.

It should be noted that, in this embodiment, in order to prevent the noise signal on the subcarrier corresponding to the guard band and the zero frequency portion from interfering with the subsequent detection, among the received signals, the subcarrier and the zero used as the guard band. The signal on the frequency partial subcarrier is set to zero; or, in each Walsh code sequence used for correlation detection, the partial code sequence corresponding to the subcarrier and/or the zero frequency partial subcarrier used as the guard band is set to Zero, correlation detection of the signal by the Walsh code sequence after zeroing.

The second embodiment of the present invention also relates to an OFDM-based prefix signal transmission and reception method, the transmitting end of which is the same as that of the first embodiment, and the receiving end in the present embodiment is as shown in FIG. In step 910, the receiving end performs OFDM demodulation on the received signal to obtain a signal on the subcarrier transmitting the information of the transmitting end.

Next, proceeding to step 920, the demodulated signal is deinterleaved.

Next, proceeding to step 930, in order to prevent the noise signal on the sub-carrier corresponding to the guard band and the zero-frequency portion from interfering with the subsequent detection, the signals on the sub-carrier and the zero-frequency partial sub-carrier used as the guard band are set to zero, Improve the accuracy of the test afterwards.

Next, proceeding to step 940, the signal after zeroing is correlated with various possible Walsh code sequences.

Then, proceeding to step 950, the Walsh code sequence with the highest degree of correlation is selected, and the information corresponding to the Walsh code sequence is used as the information transmitted by the transmitting end.

The third embodiment of the present invention also relates to an OFDM-based prefix signal transmission and reception method, which is substantially the same as the first and second embodiments, except that in the first second embodiment, the code sequences corresponding to TDM2 and TDM3 are mapped together. On the 512 subcarriers of the two OFDM symbols, in the present embodiment, the code sequences corresponding to TDM2 and TDM3 are respectively mapped on 512 subcarriers of one OFDM symbol, and the code sequence corresponding to TDM2 is mapped to the second OFDM. On the 512 subcarriers of the symbol, the code sequence corresponding to TDM3 is mapped on 512 subcarriers of the 8th OFDM symbol, as shown in FIG. 10, which has good compatibility with the prior art.

The fourth embodiment of the present invention also relates to an OFDM-based prefix signal transmission and reception method, as shown in Fig. 11 at the transmitting end.

In step 1110, for the 9-bit information (TDM2 or TDM3, the primary transmission system parameter) to be transmitted, it is divided into the first half and the second half, the first half being n bits and the second half being m bits.

In step 1120, the n-bit portion is used as information carried in the physical resource, which is mapped to a 2 ^n- bit Walsh code sequence.

In step 1130, the scrambling mode is selected according to m bits, and there are 2 ^m scrambling modes in total.

Then, proceeding to step 1140, the mapped Walsh code sequence is subjected to force interference by the m-bit selected force perturbation mode.

Next, proceeding to step 1150, the scrambled code sequence is interleaved. The Walsh code sequence is regular. Due to the existence of multipath fading, the inherent characteristics of the Walsh code (such as orthogonality) will be destroyed. At the same time, the protection subcarrier continuously intercepts part of the Walsh code, which will destroy some important characteristics of the Walsh code (such as related performance degradation, correlation peak reduction), and thus cannot be correctly recognized by the receiving end. Interleaving the code sequence to be transmitted makes the effects of multipath fading and guard subcarriers uniform, so that even if the frequency domain signal of the guard band or the zero frequency part is lost, it is only equivalent to introducing some noise, which does not cause the receiver to completely fail. Identify and improve the performance of signal code detection.

Next, proceeding to step 1160, the interleaved code sequence is mapped onto the subcarriers of the OFDM symbol, and the code sequence on the subcarrier and/or the zero frequency partial subcarrier serving as the guard band is set to zero.

Next, proceeding to step 1170, the code sequence after the zero is subjected to OFDM modulation, and then transmitted through the antenna. In this embodiment, the DFT transform is not performed on the code sequence, so that the demodulated frequency domain information can be directly detected at the receiving end, and it is not necessary to separately detect all possible multipath signals, thereby greatly reducing the receiver of the receiving end. the complexity.

The following is an example in which n is equal to 8, and m is equal to 1. The transmitting end divides the 9-bit information to be transmitted into the first 8 bits and the last 1 bit, performs 256-bit Walsh code mapping on the 8-bit information, selects the scrambling mode according to the last 1 bit, and selects the scrambling mode according to the 1 bit. (There are two possible methods of scrambling) The orthogonal sequence obtained by mapping the 8-bit information is scrambled, and the scrambled code sequence is interleaved, and then mapped to subcarriers of two OFDM symbols. For 256 code sequences obtained by interleaving TDM2 or TDM3 information, there are many ways to map. For example, the code sequences corresponding to TDM2 and TDM3 are respectively mapped on 128 subcarriers of 2 OFDM symbols, and are repeatedly placed twice at corresponding time-frequency resource locations, and the code sequences corresponding to TDM2 and TDM3 can be interleaved and repeatedly mapped to 512 sub-carriers. On the carrier, as shown in FIG. 12, the code sequence corresponding to TDM2 may be repeatedly mapped on the middle 256 subcarriers to reduce the influence of the guard band, and the code sequence mapping corresponding to TDM3 is repeatedly mapped on the externally measured 256 subcarriers. As shown in Figure 13. The 256 symbols obtained by interleaving TDM2 or TDM3 may also be repeatedly mapped to 512 subcarriers of one corresponding OFDM symbol, as shown in FIG. Alternatively, it is also possible to add zero to the 8-bit information of TDM2 or TDM3, form 9-bit information, map 9-bit information to 512-bit Walsh code, and map 512-bit Walsh code to sub-carrier of OFDM symbol. An embodiment is the same. The invention includes, but is not limited to, these mapping methods. Then, the code sequence on the protection subcarrier and the subcarrier corresponding to the zero frequency is zeroed, because the code sequence obtained by the mapping is repeatedly transmitted, thereby weakening the influence of the guard band on it. After the zeroed code sequence is OFDM modulated, it is sent through the antenna Go out.

At the receiving end, as shown in Fig. 15, in step 1510, the received signal is subjected to OFDM demodulation to obtain a signal on the subcarrier transmitting the information of the transmitting end.

Next, proceeding to step 1520, in order to prevent the noise signal on the sub-carrier corresponding to the guard band and the zero-frequency portion from interfering with the subsequent detection, the signals on the sub-carrier and the zero-frequency partial sub-carrier used as the guard band are set to zero, Improve the accuracy of the test afterwards.

Next, proceeding to step 1530, the signal after the zero is deinterleaved.

Then, proceeding to step 1540, the deinterleaved signal is descrambled according to all possible scrambling modes of the transmitting end. There are usually 2 ^m descrambling modes, which is the length of the second half of the information transmitted by the sender.

Next, proceeding to step 1550, correlation detection is performed on the descrambled signals in various possible Walsh code sequences. Since the IDFT transform is not required at the receiving end to directly detect the frequency domain information, it is not necessary to separately detect all possible multipath signals, so that the complexity of the receiver is greatly reduced.

Next, proceeding to step 1560, selecting the Walsh code sequence with the highest degree of correlation, and using the information corresponding to the Walsh code sequence as the information transmitted by the transmitting end portion (ie, the first n bits of information), according to the corresponding Walsh code sequence with the highest degree of correlation. The method of scrambling obtains the information transmitted by the remaining part of the transmitting end (ie, the last m bits of information). In this way, more information can be transmitted through the same resource, and resource utilization is greatly improved without degrading system performance.

The same is given by taking n equal to 8, m equal to 1 as an example. After receiving the OFDM signal, the receiving end obtains the signal of the subcarrier transmitting the information of the transmitting end. Because the guard band and the subcarrier corresponding to the zero frequency have interference, in order to improve the accuracy of the detection, the corresponding position is set to zero. Then, the signal after zeroing is deinterleaved, and the deinterleaved signal is descrambled according to all possible scrambling modes (2 types in total), and the descrambled sequences are respectively associated with all possible Walsh codes. Correlation is performed, and the 8-bit information transmitted by the transmitting end is obtained according to the Walsh code with the highest degree of correlation, and the information of the remaining 1 bit of the channel is obtained according to the scrambling code method corresponding to the Walsh code sequence with the highest degree of correlation.

Alternatively, in the present embodiment, it is also possible to perform interleaving without performing scrambling. That is, the interpolating method is directly selected by the m-bit at the transmitting end, and the Walsh code sequence mapped by the n-bit information is interleaved by the selected interleaving method, and the interleaved code sequence is mapped onto the sub-carriers of the OFDM symbol. At the receiving end, according to all possible interleaving methods (2 ^m interleaving) of the transmitting end, the zeroed signal is opposite. The number is deinterleaved, and all signals after deinterleaving are correlatedly detected, and the partially transmitted information (first n bits) of the transmitting end is obtained according to the Walsh code sequence with the highest degree of correlation, according to the Walsh code sequence with the highest degree of correlation. The interleaving method obtains the information (the last m bits) transmitted by the rest of the transmitting side.

In addition, in this embodiment, the receiving end may also interleave or scramble various possible Walsh code sequences according to all possible interleaving or scrambling modes of the transmitting end, and perform interleaving or scrambling of each Walsh code sequence pair. The demodulated signal is correlated, and the partially transmitted information of the transmitting end is obtained according to the Walsh code sequence with the highest degree of correlation, and the remaining part of the transmitting end is obtained according to the interleaving or scrambling method corresponding to the Walsh code sequence with the highest degree of correlation. Information.

A fifth embodiment of the present invention relates to an OFDM-based prefix signal transmitting apparatus, including: a unit that maps partial prefix information into a signal code sequence; and maps the signal code sequence as a frequency domain signal to a unit on a subcarrier of an OFDM symbol A unit that transmits OFDM after subcarriers of OFDM symbols. The signal code sequence therein may be an orthogonal code sequence, such as a Walsh code sequence. The partial prefix information is TDM2 and/or TDM3 in the prefix of the forward physical channel. In this embodiment, the received signal is not required to be DFT-transformed, so that the demodulated frequency domain information can be directly detected at the receiving end, and it is not necessary to separately detect all possible multipath signals, thereby greatly reducing the receiver. The complexity.

The signal transmitting apparatus further includes: a unit that interleaves the sequence of signal codes to be transmitted; a unit that maps the interleaved signal code sequence to subcarriers of the OFDM symbol; a subcarrier and/or a zero frequency portion that will be used as a guard band A unit in which the signal code sequence on the subcarrier is set to zero. The sequence of signal codes is regular, and due to the presence of multipath fading, the inherent characteristics of the signal code (such as orthogonality) will be destroyed. At the same time, the protection subcarrier continuously cuts off part of the transmitted signal code, which will destroy some important characteristics of the transmitted signal code (such as related performance degradation, correlation peak reduction), and thus cannot be correctly recognized by the receiving end. The interleaving of the signal codes to be transmitted makes the effects of multipath fading and guard subcarriers uniform, so that even if the frequency domain signal of the guard band or the zero frequency portion is lost, it is only equivalent to introducing some noise, which does not cause the receiving end to completely fail. Identify and improve the performance of signal code detection.

The method may further include: dividing the partial prefix information to be transmitted into two units of n and m bits; mapping the n-bit portion into a unit of the signal code sequence; and selecting, in the manner of interleaving or scrambling, the unit of the m-bit portion; Interleaving or scrambling the signal code sequence by interleaving or scrambling Unit; mapping the interleaved or scrambled signal code sequence to a unit on a subcarrier of the OFDM symbol. A sixth embodiment of the present invention relates to an OFDM-based prefix signal receiving apparatus, including: a unit for performing OFDM demodulation on a received signal when receiving partial prefix information in a forward physical channel; and demodulating the signal A unit for performing correlation detection with various possible signal code sequences; and information corresponding to the signal code sequence having the highest degree of correlation obtained by correlation detection is used as a unit of information transmitted by the transmitting end. Wherein, the signal code sequence is an orthogonal code sequence, such as a Walsh code sequence. The partial prefix information is TDM2 and TDM3 in the prefix of the forward physical channel.

The signal receiving apparatus further includes: means for deinterleaving the demodulated signal; means for performing correlation detection on the deinterleaved signal; or comprising: means for interleaving various possible signal code sequences; The subsequent units of the signal code sequence perform correlation detection.

The signal receiving apparatus may further include: a unit that sets a partial signal corresponding to a subcarrier used as a guard band and/or a subcarrier of a zero frequency portion to zero in the received OFDM signal; correlating the signal after the zero is set a unit of detection; or comprising: a unit that sets a partial code sequence corresponding to a subcarrier used as a guard band and/or a subcarrier of a zero frequency portion to zero among various possible signal code sequences; A unit of signal code sequence for correlation detection. Thereby, the noise signal on the sub-carrier corresponding to the guard band and the zero-frequency portion is prevented from interfering with the subsequent detection.

The signal receiving apparatus may further include: a unit that deinterleaves or descrambles the demodulated signal according to all possible interleaving or scrambling modes of the transmitting end; and a unit that performs correlation detection on all signals after deinterleaving or descrambling Or, a unit that interleaves or scrambles various possible signal code sequences according to all possible interleaving or scrambling methods at the transmitting end; correlates the demodulated signals by interleaving or scrambled signal code sequences a unit for detecting; and comprising: a unit for obtaining information of a partial transmission of the transmitting end according to a signal code sequence with the highest degree of correlation after the correlation; and obtaining an excess of the transmitting end according to an interleaving or scrambling method corresponding to the signal code sequence having the highest correlation degree A unit of partially transmitted information. This enables more information to be transmitted through the same resources, greatly improving resource utilization without degrading system performance.

In summary, in various embodiments of the present invention, at the transmitting end, part of the prefix information in the forward physical channel is mapped into a signal code sequence, and the signal code sequence is mapped as a frequency domain signal to subcarriers of the OFDM symbol. , transmitted after OFDM modulation. When receiving the partial prefix information in the forward physical channel, the receiving end performs OFDM demodulation on the received signal, and the demodulated signal and various possibilities The signal code sequence performs correlation detection, and the information corresponding to the signal code sequence with the highest degree of correlation is used as the information transmitted by the transmitting end. Since the demodulated frequency domain information is detected at the receiving end, it is not necessary to separately detect all possible multipath signals, so that the complexity of the receiver is greatly reduced.

The signal code sequence to be transmitted is interleaved, and the interleaved signal code sequence is mapped onto the subcarriers of the OFDM symbol; the signal code sequence on the subcarrier and/or the zero frequency partial subcarrier used as the guard band is set to zero. The signal code is usually regular, and due to the presence of multipath fading, it will destroy the inherent characteristics of the signal (such as orthogonality). At the same time, the protection subcarrier continuously cuts off part of the transmitted signal, which will destroy some important characteristics of the transmitted signal (such as the related performance degradation, the correlation peak is reduced), so that it cannot be correctly recognized by the receiving end. The interleaving of the signal codes to be transmitted makes the effects of multipath fading and guard subcarriers uniform, so that even if the frequency domain signal of the guard band or the zero frequency portion is lost, it is only equivalent to introducing some noise, which does not cause the receiving end to completely fail. Identify and improve the performance of signal code detection.

At the transmitting end, the partial prefix information to be transmitted is divided into two parts of n and m bits, the n-bit part is mapped into a signal code sequence, and the interleaving or scrambling mode is selected according to the m-bit part; according to the selected interleaving or adding The scrambling method interleaves or scrambles the signal code sequence, and maps the interleaved or scrambled signal code sequence to the subcarriers of the OFDM symbol. At the receiving end, demodulating or descrambling the demodulated signal according to all possible interleaving or scrambling modes of the transmitting end; performing correlation detection on all signals after deinterleaving or descrambling, according to the most relevant signal among them The number sequence obtains the partial transmission information of the transmitting end, and the information transmitted by the remaining part of the transmitting end is obtained according to the interleaving or scrambling method corresponding to the most relevant signal code sequence. This enables more information to be transmitted through the same resources, greatly improving resource utilization without degrading system performance.

As can be seen from the technical solutions of the foregoing embodiments of the present invention, the signal code sequence mapped by the partial prefix information in the forward physical channel is directly mapped to the subcarrier of the OFDM symbol as the frequency domain signal, and then received. The terminal can perform correlation detection on the demodulated frequency domain information, and does not need to detect all possible multipath signals separately, thus greatly reducing the complexity of the receiver. At the same time, the influence of the protection subcarrier is overcome, and the characteristics of the OFDM system are utilized to enhance the transmission performance under the multipath channel.

In addition, the signal code sequence to be transmitted is interleaved, and the interleaved signal code sequence is mapped to subcarriers of the OFDM symbol; the signal code sequence on the subcarrier and/or the zero frequency partial subcarrier used as the guard band is set to zero. The signal code is usually regular, due to the existence of multipath fading, Destroy the inherent characteristics of the signal (such as orthogonality). At the same time, the protection subcarrier continuously cuts off part of the transmitted signal, which will destroy some important characteristics of the transmitted signal (such as related performance degradation, correlation peak reduction), so that it cannot be correctly recognized by the receiving end. The interleaving of the signal codes to be transmitted makes the effects of multipath fading and guard subcarriers uniform, so that even if the frequency domain signal of the guard band or the zero frequency portion is lost, it is only equivalent to introducing some noise, which does not cause the receiving end to completely fail. Identify and improve the performance of signal code detection.

In addition, at the transmitting end, the partial prefix information to be transmitted is divided into two parts of n and m bits, the n-bit part is mapped into a signal code sequence, and the interleaving or scrambling mode is selected according to the m-bit part; according to the selected interlacing Or scrambling the signal code sequence to interleave or scramble, and map the interleaved or scrambled signal code sequence to the subcarriers of the OFDM symbol. At the receiving end, demodulating or descrambling the demodulated signal according to all possible interleaving or scrambling modes of the transmitting end; performing correlation detection on all signals after deinterleaving or descrambling, according to the most relevant signal among them The number sequence obtains the information of the partial transmission of the transmitting end, and obtains the information transmitted by the remaining part of the transmitting end according to the interleaving or scrambling manner corresponding to the signal code sequence with the highest degree of correlation. This enables more information to be transmitted through the same resources, greatly improving resource utilization without degrading system performance.

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

An OFDM-based prefix signal sending method, comprising:

Mapping partial prefix information in the forward physical channel to a signal code sequence;

The signal code sequence is mapped as a frequency domain signal to subcarriers of an OFDM symbol, and is transmitted after OFDM modulation.

The OFDM-based prefix signal transmission method according to claim 1, wherein the signal code sequence is an orthogonal code sequence.

The method for transmitting an OFDM-based prefix signal according to claim 1, wherein the partial prefix information in the forward physical channel is TDM2 and/or TDM3 in a prefix of a forward physical channel.

The method for transmitting an OFDM-based prefix signal according to claim 1, wherein before the mapping the signal code sequence as a frequency domain signal to a subcarrier of an OFDM symbol, the method further comprises: pairing the signal code sequence Interlace.

The method for transmitting an OFDM-based prefix signal according to claim 1, further comprising: before performing the OFDM modulation:

The signal code sequence on the subcarrier and/or zero frequency partial subcarrier used as the guard band is set as a command.

The method for transmitting an OFDM-based prefix signal according to claim 1, wherein before mapping the partial prefix information in the forward physical channel to a signal code sequence, the method further comprises: placing the forward physical channel The partial prefix information is divided into two parts: n bits and m bits. The step of mapping the partial prefix information in the forward physical channel into the signal code sequence is specifically: the n in the partial prefix information in the forward physical channel. The bit portion is mapped to a signal code sequence;

Before mapping the signal code sequence as a frequency domain signal to a subcarrier of the OFDM symbol, the method further includes: selecting, according to the m bit portion in the partial prefix information, an interleaving or scrambling manner; according to the selected interlace or The signal code sequence is interleaved or scrambled in a scrambled manner.

The OFDM-based prefix signal transmitting method according to any one of claims 1 to 6, wherein the partial prefix information is mapped to the signal code sequence by one of: The number of bits of the prefix information, which is directly mapped to a signal code sequence of a corresponding length; If the bit number of the partial prefix information is less than N, padding bits are added to the information, and the padded N-bit information is mapped to a signal code sequence of a corresponding length.

The OFDM-based prefix signal transmission method according to any one of claims 1 to 6, wherein the signal code sequence is mapped to subcarriers of an OFDM symbol by one of the following methods or any combination thereof. :

Mapping a signal code sequence onto associated subcarriers of an OFDM symbol;

Mapping signal code sequences corresponding to different information on different consecutive subcarriers of at least two OFDM symbols;

Alternatingly mapping signal code sequences corresponding to different information on different consecutive subcarriers of at least two OFDM symbols;

And mapping, according to the importance degree of the information corresponding to the signal code sequence, a sequence of signal numbers corresponding to the relatively important information on a part of the subcarriers in the middle of the OFDM symbol;

Mapping the signal code sequence to other subcarriers other than the subcarrier used as the guard band; if the signal code sequence is a short message number sequence, the sequence of the short message number is repeatedly mapped on the subcarrier of the OFDM symbol .

9. A method for receiving a prefix signal based on OFDM, comprising:

Performing OFDM demodulation on the received signal when receiving partial prefix information in the forward physical channel;

Correlation detection is performed on the demodulated signal and various possible signal code sequences, and information corresponding to the signal code sequence with the highest degree of correlation is used as information transmitted by the transmitting end.

10. The OFDM-based prefix signal receiving method according to claim 9, further comprising: before performing the correlation detection on the demodulated signal and various possible signal code sequences:

The demodulated signal is deinterleaved or the various possible signal code sequences are interleaved.

11. The OFDM-based prefix signal receiving method according to claim 9, further comprising: before performing the correlation detection on the demodulated signal and various possible signal code sequences:

Or combining the demodulated signal or the various possible signal code sequences for use as a guard band The partial signals of the subcarriers and/or the zero frequency partial subcarriers are set to zero.

The OFDM-based prefix signal receiving method according to any one of claims 9 to 11, characterized in that

Before performing the correlation detection on the demodulated signal and the various possible signal code sequences, the method further includes: deinterleaving or descrambling the demodulated signal according to all possible interleaving or scrambling modes of the transmitting end; The steps of correlating the demodulated signal with various possible signal code sequences include:

Performing correlation detection on all signals after deinterleaving or descrambling and various possible signal code sequences, and obtaining partial information transmitted by the transmitting end according to the signal code sequence with the highest degree of correlation, according to the signal code sequence with the highest degree of correlation The corresponding interleaving or scrambling mode obtains the remaining part of the information transmitted by the transmitting end;

Or

Before performing the correlation detection on the demodulated signal and the various possible signal code sequences, the method further comprises: interleaving or scrambling the various possible signal code sequences according to all possible interleaving or scrambling modes of the transmitting end. The step of performing correlation detection on the demodulated information and various possible signal code sequences includes:

Performing correlation detection on the demodulated signal and each interleaved or scrambled signal code sequence, and obtaining partial information transmitted by the transmitting end according to the signal code sequence having the highest correlation degree, according to the letter with the highest degree of correlation The interleaving or scrambling method corresponding to the sequence of numbers obtains the remaining part of the information transmitted by the transmitting end.

An OFDM-based prefix signal transmitting apparatus, comprising: means for mapping partial prefix information in a forward physical channel into a signal code sequence; and mapping the signal code sequence as a frequency domain signal a unit on a subcarrier to an OFDM symbol;

A unit for transmitting OFDM modulated signals mapped to OFDM symbol subcarriers.

The OFDM-based prefix signal transmitting apparatus according to claim 13, wherein the signal code sequence is an orthogonal code sequence.

15. The OFDM-based prefix signal transmitting apparatus according to claim 13, characterized in that The partial prefix information in the forward physical channel is TDM2 and/or TDM3 in the prefix of the forward physical channel.

16. The OFDM-based prefix signal transmitting apparatus according to claim 13, further comprising: a unit for interleaving the signal code sequence; the mapping for mapping a signal code sequence as a frequency domain signal to OFDM The unit on the subcarrier of the symbol comprises: means for mapping the interleaved signal code sequence as a frequency domain signal onto a subcarrier of the OFDM symbol.

The OFDM-based prefix signal transmitting apparatus according to claim 13, further comprising: configured to set the signal code sequence on a subcarrier and/or a zero frequency partial subcarrier serving as a guard band a unit of zero;

The means for performing OFDM modulation on a signal mapped to an OFDM symbol subcarrier includes: means for performing OFDM modulation on the signal mapped to the OFDM symbol subcarrier by the above zeroing.

18. The OFDM-based prefix signal transmitting apparatus according to claim 13, wherein:

The device further includes: a unit for dividing the partial prefix information into two parts of n bits and m bits; the unit for mapping partial prefix information in a forward physical channel into a signal code sequence includes: Mapping the n-bit portion of the partial prefix information in the forward physical channel to a unit of a signal code sequence;

The apparatus further includes: means for selecting an interleaving or scrambling manner according to the m-bit portion; and means for interleaving or scrambling the signal code sequence according to the selected interleaving or scrambling manner; The unit for mapping a signal code sequence as a frequency domain signal to a subcarrier of an OFDM symbol comprises: mapping the interleaved or scrambled signal code sequence as a frequency domain signal to a subcarrier of an OFDM symbol Unit.

An OFDM-based prefix signal receiving device, comprising: configured to perform, when receiving partial prefix information in a forward physical channel, the received signal

OFDM demodulation unit;

a unit for performing correlation detection on the demodulated signal and various possible signal code sequences; information for using the signal code sequence with the highest degree of correlation obtained by the correlation detection as information transmitted by the transmitting end unit.

20. The OFDM-based prefix signal receiving apparatus according to claim 19, wherein the signal code sequence is an orthogonal code sequence.

21. The OFDM-based prefix signal receiving apparatus according to claim 19, wherein:

The apparatus further includes: means for deinterleaving the demodulated signal; the means for correlating detection of the demodulated signal with various possible signal code sequences includes: Means for correlating the deinterleaved signal with various possible signal code sequences;

Or

The apparatus further includes: means for interleaving the various possible signal code sequences; the means for correlating detection of the demodulated signal with various possible signal code sequences includes: A unit that performs correlation detection on the demodulated signal and the interleaved signal code sequence.

22. The OFDM-based prefix signal receiving apparatus according to claim 19, wherein:

The apparatus further includes: means for setting a partial signal corresponding to a subcarrier and/or a zero frequency partial subcarrier serving as a guard band to zero in the demodulated signal;

The unit for performing correlation detection on the demodulated signal and various possible signal code sequences includes: performing correlation detection on the demodulated signal after the zero-setting and various possible signal code sequences. Unit

Or

The apparatus further includes: means for setting a partial code sequence corresponding to a subcarrier and/or a zero frequency partial subcarrier serving as a guard band to zero among the various possible signal code sequences; The unit for performing correlation detection on the demodulated signal and various possible signal code sequences includes means for performing correlation detection on the demodulated signal and each of the zeroed signal code sequences.

The OFDM-based prefix signal receiving apparatus according to any one of claims 19 to 22, characterized in that

The apparatus further includes: means for deinterleaving or descrambling the demodulated signal according to all possible interleaving or scrambling modes of the transmitting end; the means for demodulating the signal and various possibilities The unit for performing correlation detection on the signal code sequence includes: means for performing correlation detection on the deinterleaved or descrambled all signals and various possible signal code sequences; The unit for using the information corresponding to the signal code sequence with the highest correlation degree obtained by the correlation detection as the information transmitted by the transmitting end includes: obtaining the partial information transmitted by the transmitting end according to the signal code sequence with the highest correlation degree after the correlation detection. a unit; and a unit for obtaining remaining portion information transmitted by the transmitting end according to an interleaving or scrambling manner corresponding to the most closely related signal code sequence.

The apparatus further comprises: means for interleaving or scrambling various possible signal code sequences according to all possible interleaving or scrambling modes of the transmitting end; the means for demodulating the signal and various possible The unit for performing correlation detection on the signal code sequence includes: means for performing correlation detection on the demodulated signal and the interleaved or scrambled signal code sequence;

The unit for using the information corresponding to the signal code sequence with the highest correlation degree obtained by the correlation detection as the information transmitted by the transmitting end includes: obtaining the partial information transmitted by the transmitting end according to the signal code sequence with the highest correlation degree after the correlation detection. a unit; and means for obtaining remaining portion information transmitted by the transmitting end according to an interleaving or scrambling manner corresponding to the most closely related signal code sequence.