CN101032105A - Transmitting device, receiving device, and communication system and method - Google Patents

Abstract

A receiving apparatus that can effectively use spectra to improve the interference resistance and the information transmission efficiency. In this apparatus, a channel estimating part (1006) uses a pilot received from the transmitting end to perform a channel estimation for each of subcarrier groups. A subcarrier group performance analyzer (1011) calculates, based on a channel estimation result, the SIR value of each subcarrier group. A control command generating part (1012) uses the SIR value of each subcarrier group to generate the puncture information and rate of the subcarrier group, then stores the generated puncture information and rate so as to perform an appropriate process when an S/P converting part (1005) performs an S/P conversion for next received information, and then feeds the generated puncture information and rate back to a transmitting apparatus.

Description

Sending device, receiving device, communication system and communication method

technical field

The present invention relates to a sending device, a receiving device, a communication system and a communication method, for example, to a sending device, a receiving device, a communication system and a communication method for adaptively adjusting subcarrier group rates in a subcarrier communication system.

Background technique

At present, with the development of theory and technology, many new technologies and new applications have appeared in mobile communication, such as Orthogonal Frequency Division Multiplexing (OFDM), MIMO and so on. These new technologies can greatly improve the performance of mobile communication systems and meet people's requirements for wireless multimedia and high-speed data transmission. For example, OFDM divides the channel into many orthogonal sub-channels in the frequency domain, and the carrier spectrum of each sub-channel overlaps with each other, which improves the spectrum utilization. At the same time, the signal bandwidth of each sub-channel is smaller than the channel bandwidth. Even if the entire channel is frequency selective, each sub-channel is relatively flat, thus greatly reducing the inter-symbol interference (ISI). The main advantages of OFDM are: each signal will not interfere with each other; it is not sensitive to multipath fading and Doppler frequency shift; there is no interference between users and adjacent cells; it can realize low-cost single-band receivers, etc. The main disadvantage of OFDM is that it is not very power efficient. Because OFDM has the advantages of strong anti-multipath ability and high spectrum utilization rate, it is suitable for high-speed wireless transmission.

In the transmission device of the existing OFDM system, it includes: a coding unit 101, an interleaving unit 102, a modulation unit 103, a pilot insertion unit 104, a serial-to-parallel conversion unit 105, and an inverse Fourier transform (hereinafter referred to as "IFFT") unit 106 , adding a guard interval and windowing unit 107, a digital-to-analog conversion (DAC) unit 108, and a transmitter (RFTX) 109 and other parts. Wherein, the pilot is inserted for channel estimation, and the SIR value of the subcarrier can be calculated according to the channel estimation result. In addition to some processes corresponding to the transmission, the receiving device of the OFDM system also includes channel estimation and information feedback parts. In other words, the receiving device includes: a receiver (RFRX) 111, an analog-to-digital conversion (ADC) unit 112, a deguard interval unit 113, a fast Fourier transform (hereinafter referred to as "FFT") unit 114, a parallel-to-serial transform unit 115, a channel estimation unit 116 , demodulation unit 117 , deinterleaving unit 118 , and decoding unit 119 .

In all OFDM carriers, usually 1% of the subcarriers have an attenuation 20dB lower than the average carrier, and 0.1% of the subcarriers have an attenuation lower than the average carrier 30dB. Severe fading on these subcarriers degrades system performance. Therefore, if adaptive rate adjustment is performed on each subcarrier according to the channel SIR performance of the subcarrier, the system performance can be optimized.

FIG. 1 is a structural block diagram of a traditional OFDM system transceiver. In the sending device in FIG. 1 , the encoding unit 101 encodes user information, the encoded information is interleaved by the interleaving unit 102 , and then modulated by the modulating unit 103 . The pilot insertion unit 116 inserts the pilot into the modulated information so as to estimate the channel, then the serial-to-parallel conversion unit 105 performs the serial-to-parallel conversion, the IFFT unit 106 performs IFFT, and the guard interval and windowing unit 107 adds the modulated information Guard intervals and windowing to prevent interference between subcarriers. Then, the information inserted into the guard interval is transmitted from the transmitter 109 through the digital-to-analog conversion unit 108 .

At the receiving device, the receiver 111 receives the information from the transmitter 109 and converts it from radio frequency to base frequency. The converted information passes through the digital-to-analog conversion unit 112 and the deguard interval unit 113 , and performs FFT in the FFT unit 114 . The information after FFT is sent to the channel estimator 116 through the parallel-to-serial transformation unit 115 . Then, channel estimator 116 performs channel estimation. Channel compensation can be performed according to the channel estimation result, and then the demodulation unit 117 performs information demodulation, then the deinterleaving unit 118 performs deinterleaving, and finally the decoding unit 119 performs decoding. Recover the original data after decoding.

However, in existing OFDM systems, the same transmission rate is generally used for all subcarriers. The disadvantage of this approach is that the difference in transmission performance of each subcarrier caused by frequency selective fading is not considered. If the transmission performance of a certain subcarrier is poor, but still adopts the same rate as other subcarriers with better performance, the anti-interference performance of the subcarrier will be poor, and the transmission efficiency will be very low.

Contents of the invention

The problem to be solved by the present invention

An object of the present invention is to provide a transmitting device, a receiving device, a communication system, and a communication method capable of improving anti-interference performance and signal transmission efficiency by effectively using spectrum.

The means used to solve the problem

The structure adopted by the sending device of the present invention includes: a subcarrier selection unit, which generates and outputs subcarrier selection signals of each subcarrier group according to the received subcarrier selection feedback information; The carrier selection signal selects the required sub-carriers in each sub-carrier group, and at the same time, allocates data on the selected sub-carriers; the inverse fast Fourier transform unit reverses the data allocated to each sub-carrier in the data allocation unit a fast Fourier transform; and a sending unit for sending the data after the inverse fast Fourier transform.

The receiving device of the present invention includes: a receiving unit for receiving data; a fast Fourier transform unit for performing fast Fourier transform on the data; a first parallel-serial transform unit for performing fast Fourier transform on the fast Fourier-transformed data according to the first parallel-serial transform control signal The data is subjected to a first parallel-to-serial conversion, and after the first parallel-to-serial conversion, the subcarriers of all data in the same carrier group are combined, and each combined subcarrier group is output; multiple channel estimation units, for Each of the corresponding subcarrier groups after the first parallel-to-serial conversion performs channel estimation; the subcarrier group analyzer analyzes the channel estimation results, and calculates the SIR value of each subcarrier group; the control command generation unit, according to each subcarrier The SIR value of the group generates subcarrier selection feedback information, and generates the first parallel-to-serial conversion control signal according to the subcarrier selection information in each carrier group in the generated subcarrier selection feedback information; and the sending unit, sending The subcarrier selection feedback information.

The structure of the communication system of the present invention is a communication system having a sending device for sending a signal and a receiving device for receiving a signal, the sending device includes: a subcarrier selection unit for selecting feedback information according to the received subcarrier, Generate and output the sub-carrier selection signals of each sub-carrier group; the data allocation unit selects the required sub-carriers in each sub-carrier group according to the sub-carrier selection signals of each sub-carrier group, and at the same time allocates the selected sub-carriers data; an inverse fast Fourier transform unit, performing inverse fast Fourier transform on the data assigned to each subcarrier in the data allocation unit; and a sending unit, sending the data after the inverse fast Fourier transform, and the receiving device includes: a receiving unit, receiving data; the fast Fourier transform unit performs fast Fourier transform on the data; the first parallel-serial transform unit performs the first parallel-serial transform on the fast Fourier-transformed data according to the first parallel-serial transform control signal, and passes through the After the first parallel-to-serial conversion, combine the subcarriers of all data in the same carrier group together, and output the combined subcarrier groups; multiple channel estimation units, for the corresponding subcarriers through the first parallel-to-serial conversion Each of the groups performs channel estimation; the subcarrier group analyzer analyzes the channel estimation results, and calculates the SIR value of each subcarrier group; the control command generating unit generates subcarrier selection feedback information according to the SIR values of each subcarrier group , and generate the first parallel-to-serial conversion control signal according to the subcarrier selection information in each carrier group in the generated subcarrier selection feedback information; and a sending unit that sends a signal with the subcarrier selection feedback information .

In the communication method of the present invention, the receiving device includes the following steps: receiving data; performing fast Fourier transform on the data; performing a first parallel-serial transform on the fast Fourier-transformed data according to a first parallel-serial transform control signal , after the first parallel-to-serial conversion, combine all data subcarriers in the same carrier group together, and output the combined subcarrier groups; for each of the combined subcarrier groups Performing channel estimation; analyzing the channel estimation result, calculating the SIR value of each subcarrier group; generating subcarrier selection feedback information according to the SIR value of each subcarrier group, and selecting the feedback information according to the generated subcarrier selection The selection information of subcarriers in each carrier group, generating the first parallel-to-serial conversion control signal; and sending the subcarrier selection feedback information, and causing the sending device to include the following steps: receiving the subcarrier selection feedback information; according to The received subcarrier selection feedback information generates and outputs subcarrier selection signals of each subcarrier group; according to the subcarrier selection signals of each subcarrier group, selects the required subcarriers in each subcarrier group, and at the same time, Allocating data on the selected subcarriers; performing an inverse fast Fourier transform on the data allocated to each subcarrier; and sending the inverse fast Fourier transformed data by the sending device.

Beneficial effects of the present invention

According to the present invention, the performance of anti-interference and the efficiency of information transmission can be improved by effectively using the frequency spectrum.

Description of drawings

FIG. 1 is a structural block diagram of a traditional OFDM system transceiver.

Fig. 2 shows the influence of frequency selective fading on the transmission performance of each sub-carrier according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of selecting an average rate of a carrier group according to an SIR value of a carrier group according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of selecting the number of subcarriers of each group according to the SIR value of the carrier group according to an embodiment of the present invention.

FIG. 5A shows the influence of frequency selective fading on the transmission performance of each subcarrier according to the embodiment of the present invention.

FIG. 5B is a schematic diagram of selecting an average rate of a carrier group according to the SIR value of the carrier group according to an embodiment of the present invention.

FIG. 5C is a schematic diagram of selecting the number of subcarriers of each group according to the SIR value of the carrier group according to the embodiment of the present invention.

FIG. 6A shows the influence of frequency selective fading on the transmission performance of each subcarrier according to the embodiment of the present invention.

FIG. 6B is a schematic diagram of selecting the average rate of a carrier group according to the SIR value of the carrier group according to an embodiment of the present invention.

FIG. 6C is a schematic diagram of selecting the number of subcarriers of each group according to the SIR value of the carrier group according to the embodiment of the present invention.

FIG. 7A shows the influence of frequency selective fading on the transmission performance of each subcarrier according to the embodiment of the present invention.

FIG. 7B is a schematic diagram of selecting the average rate of a carrier group according to the SIR value of the carrier group according to an embodiment of the present invention.

FIG. 7C is a schematic diagram of selecting the number of subcarriers of each group according to the SIR value of the carrier group according to the embodiment of the present invention.

FIG. 8 is a structural block diagram of a sending device according to an embodiment of the present invention.

FIG. 9 is a flowchart of a sending method according to an embodiment of the present invention.

FIG. 10 is a structural block diagram of a receiving device according to an embodiment of the present invention.

FIG. 11 is a flowchart of a receiving method according to an embodiment of the present invention.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

(implementation mode)

Puncture is a method of changing the rate and efficiency of information transmission. For example, puncturing a convolutional code with a coding efficiency of 1/2, assuming that the output sequence of the convolutional code after interleaving is {A ₁ B ₁ A ₂ B ₂ A ₃ B ₃ …}, if every 6 Delete 2 bits in each bit, then it becomes a code with an efficiency of 3/4, and the bit output after puncturing is {A ₁ B ₁ A ₂ B 3 A ₄ B ₄ A ₅ B ₆ A _{7 B 7 A 8} B ₉ ...}; If 2 bits are deleted in every 4 bits of the output, then it becomes a code with an efficiency of 2/3, and the bit output after puncturing is {A ₁ B ₁ A ₂ A ₃ B ₃ A ₄ A ₅ B ₅ A ₆ ...}. The 1/2 code decoding method can still be used only by adding 0 at the hole position during decoding. Therefore, punching makes encoding flexible, can effectively perform rate matching, and is much more convenient to use. In the present invention, all the sub-carriers in the OFDM system are grouped first, and then the sub-carriers are drilled according to the transmission of each group of sub-carrier groups, which can also change the transmission rate of each sub-carrier group and effectively improve the frequency spectrum. utilization rate. For example, suppose a (010110) puncturing table is used for a certain subcarrier group, where 1 indicates that the subcarrier is selected for data transmission; 0 indicates that the subcarrier is not used, and the transmission rate of the subcarrier group is reduced by half. Whether or not to use a subcarrier is determined according to the transmission performance of the subcarrier group where the subcarrier is located.

Figure 2 shows the impact of frequency selective fading on the transmission performance of each subcarrier. The thick line is the frequency selection characteristic of the channel. In Figure 2, the transmission performance of subcarriers f4 and f5 is very good, f3, f6, f7 and f8 are poor, and f1 and f2 are very poor. In this case, if each carrier adopts the same transmission mode, the information transmission efficiency will be very low. In order to make full use of the frequency spectrum and improve the efficiency of information transmission, the present invention proposes to combine several subcarriers together to form a subcarrier group, calculate the SIR value of each subcarrier group at the receiving device, and control the subcarrier group according to the measured SIR value The higher the SIR value, the higher rate can be used to select all or most of the subcarriers in the group for data transmission; Carrier drilling is used to select a few subcarriers for data transmission, and the rest of the subcarriers are idle. In this way, by selecting a high data rate for sub-carriers with good performance and selecting a low data rate for sub-carriers with poor performance, the purpose of effectively utilizing the frequency spectrum can be achieved.

In order to effectively utilize the transmission performance of the sub-carriers, several sub-carriers can be divided into a sub-carrier group, and the transmission rate of the sub-carrier group is adaptively adjusted according to the rate control information of the sub-carrier group fed back by the receiving device. The division of subcarrier groups may divide every N subcarriers into a group in sequence, and there are two methods for selecting the number N of subcarriers in each group.

Assume that the total number of carriers N is 64, and the number of groups M is 4 groups. In the first method, the number of subcarriers in each group is fixed throughout the process, and the number K of subcarriers in each carrier group is equal. Both contain 16 subcarriers, that is, the 1st to 16th subcarriers are the first group, the 17th to 32nd subcarriers are the second group, the 33rd to 48th subcarriers are the third group, and the 49th to 64th subcarriers is the fourth group; each contains 16 subcarriers.

In the second method, the number of subcarriers in each group is variable throughout the process, but the number of each group is equal, and the change in the number of subcarriers can be based on the Doppler frequency shift f _D of the receiving device. size to change. If f _D is large, the fading of the channel changes quickly, and the number K of subcarriers in the group can be reduced at this time; if the feedback f _D is small, the channel fading is slow, and the number of subcarriers in the group can be increased at this time Number K. For example, when f _D is large, K can be selected to be 8, so that there are 8 groups; when f _D is small, K can be selected to be 16, so that there are 4 groups.

The first method is relatively simple to implement, and the second method has better performance because the influence of the Doppler frequency shift f _D is considered, and the number of subcarriers in the group is adjusted in real time according to channel conditions. For example, if f _D is small, then the change of the channel is just slower. At this time, the number K of subcarriers in the group can be selected to be larger, so that the number of groups M is reduced, and the amount of feedback information of the receiving device is reduced, which reduces the processing speed of the feedback information. of complexity. If f _D is larger, then the change of the channel is faster, and the number K of sub-carriers in the group can be selected at this time to be small, so that the number of groups increases, the amount of feedback information increases, the selection of sub-carriers in the group is more accurate, and the frequency band utilization rate is improved. The efficiency of the system is also increased. When the SIR performance of the subcarrier group is good, all or most of the subcarriers in the carrier group can be used; hole, select some of the subcarriers to transmit data, and the rest of the subcarriers are idle and do not transmit data. The puncturing information of all subcarriers is used to control the serial-to-parallel conversion process.

The receiving end can calculate the SIR value of each subcarrier group according to the pilot signal inserted by the sending device, and can calculate the rate control information of each subcarrier group according to these values. The control information includes the number of subcarriers used in the subcarrier group and the labels of the used subcarriers. If the calculated SIR value of a certain subcarrier group is relatively high, a higher transmission rate is allocated to this group of subcarriers; if the SIR value of a carrier group is low, a lower transmission rate is allocated to this group of subcarriers. The information is fed back to the sending device so that the sending device can adjust the information rate of each subcarrier group; the information is also kept in the receiving device to control the information received next time. In this case, high transmission efficiency can be maintained even in frequency selective fading channels.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the illustrated embodiment, the number of subcarriers in the carrier group is selected using the second method, that is, a simple fixed number method.

FIG. 3 shows the transmission rate control of each carrier group under the frequency selective channel in the present invention. It is assumed that three subcarriers constitute one subcarrier group. The receiving device calculates the SIR value of each subcarrier group according to the pilot signal, and determines the transmission rate of each subcarrier group according to the obtained SIR value. This information is fed back to the sending device to control the transmission rate of each subcarrier group. A higher transmission rate is adopted for subcarrier groups with good channel performance, and a lower transmission rate is adopted for subcarrier groups with poor channel performance. In FIG. 3 , subcarriers 1 to 3 constitute a subcarrier group, and a transmission rate R1 is determined according to their transmission performance. Similarly, carriers 4, 5, and 6 form another carrier group, and because their transmission performance is better, their transmission rate R2 is higher.

FIG. 4 shows the selection of subcarriers in a carrier group under frequency selective channels in the present invention. In order to control the rate of the carrier group, the present invention chooses the method of puncturing the sub-carriers in the carrier group. Which subcarriers are used for data transmission is selected through a puncturing table. For example, if the number of carriers in the group is 4, and the puncturing table is (1010) according to the information fed back from the receiving device, then the first and third subcarriers in the group will be used to transmit data, and the second and the fourth subcarrier will not be used. The number of subcarriers to be selected is determined according to the SIR value of the carrier group obtained by the receiving device. If the SIR value is higher, the number of sub-carriers available is more; otherwise, the number of sub-carriers selected is less. Which subcarrier to select can be performed with reference to the conditions of the carrier groups on both sides. If the performance of the carrier groups on both sides is better, more subcarriers on both sides can be selected to transmit data. If the performance of the carrier groups on both sides is very poor, the intermediate subcarriers may be selected or subcarriers may be randomly selected or every other subcarrier or several subcarriers may be selected fixedly. If one side of the carrier group has better performance and the other side has poorer performance, focus on selecting subcarriers close to the side with better performance. In FIG. 4, carrier group 1 selects one subcarrier, carrier group 2 selects three subcarriers, and carrier group 3 selects two subcarriers.

5A to 5C show the selection of subcarriers in the present invention when the performance of both carrier groups (carrier group 1 and carrier group 3 ) is good. Carriers ( f1 , f2 , f3 ), ( f4 , f5 , f6 ), and ( f7 , f8 , f9 ) respectively constitute three subcarrier groups (carrier group 1 to carrier group 3 ). Considering the middle carrier group 2 ( f4 , f5 , f6 ) (subcarrier group to be selected), according to the level of its SIR value, it can be determined to select two subcarriers in this group for data transmission. According to Figure 5A and Figure 5B, it can be known from the frequency selection characteristics of the channel that the performance of carrier groups 1 and 3 on both sides of carrier group 2 is good, as shown in Figure 5C, the subcarriers (f4 and f6 ). Its corresponding drilling table is (101).

6A to 6C show the selection of sub-carriers in the present invention when the performance of the carrier groups on both sides is poor. Carriers (f1, f2, f3), (f4, f5, f6), (f7, f8, f9) respectively constitute three sub-carrier groups. Considering the carrier group 2 (f4, f5, f6) in the middle, according to the level of its SIR value, it can be determined to select a subcarrier in this group for data transmission. According to FIG. 6A and FIG. 6B , it can be seen from the frequency selection characteristics of the channel that the performance of carrier groups 1 and 3 on both sides of carrier group 2 is poor. As shown in FIG. 6C , the subcarrier (f5) in the middle of carrier group 2 is selected. Its corresponding drilling table is (010). Alternatively, a subcarrier may be randomly selected, or a selection manner with a fixed interval may also be adopted.

7A to 7C show the selection of subcarriers in the present invention when one carrier group has better performance. Carriers (f1, f2, f3), (f4, f5, f6), (f7, f8, f9) respectively constitute three sub-carrier groups. Considering the middle carrier group 2 (f4, f5, f6) (subcarrier group to be selected), according to the level of its SIR value, it can be determined to select a subcarrier in this group for data transmission. According to Figure 7A and Figure 7B, from the frequency selection characteristics of the channel, it can be known that the carrier group 3 (f7, f8, f9) on the right side of carrier group 2 has better performance, as shown in Figure 7C, select the carrier group close to the right side 3 subcarriers (f6). Its corresponding drilling table is (001).

Fig. 8 is a structural block diagram of the OFDM system sending device in the present invention. According to the present invention, the sending device includes: a coding unit 801, an interleaving unit 802, a modulation unit 803, a pilot insertion unit 804, a serial-to-parallel conversion and subcarrier selection unit 805, an IFFT unit 806, a guard interval and windowing unit 807, a digital Analog to Analog Converter (DAC) 808 , Transmitter (RFTX) 809 , Subcarrier Selector 810 . In the present invention, in order to improve efficiency, several sub-carriers are divided into one group for transmission rate control. Different subcarrier groups are assigned different transmission rates according to their transmission signal-to-interference ratios.

In Figure 8, the original information is first encoded by the encoding unit 801. The encoding is to insert some redundant information into the original information, so that the redundancy can be used in the receiver to overcome the interference and noise encountered by the signal during channel transmission. Impact. The encoding methods that are more commonly used now generally include Turbo codes and convolutional codes.

The coded information is interleaved in the interleaving unit 802. The interleaving disrupts the original transmission order of the signals, so that the original adjacent signals are scattered into different time periods, so that when burst interference or deep fading occurs, the information from the source The most important code bits of a block of bits will not be disturbed at the same time, and after the source bits are separated, error control coding can be used to weaken the influence of channel interference on the source bits.

The interleaved data is modulated in the modulation unit 803, so that the binary bit values are mapped to points in the constellation diagram to form corresponding symbols. The data can be modulated by QPSK, 16QAM and other modulation methods.

The modulated data is input to the pilot insertion unit 804, so that the receiving device performs channel estimation and carrier group performance calculation, and the signal after the pilot insertion then enters the serial-to-parallel conversion and subcarrier selection unit 805 (data allocation unit), and the serial-to-parallel conversion and subcarrier selection is performed under the control of subcarrier selector 810 . The subcarrier selector 810 receives the rate control information of the subcarrier groups fed back from the receiving device, and the information includes the number of carriers that should be selected for each carrier group and the labels of the subcarriers that should be selected. When serial-to-parallel conversion is performed, data is allocated on subcarriers selected for data transmission, while unselected subcarriers are not allocated to transmit data. In this way, after serial-to-parallel conversion, only those selected subcarriers have data.

In Figure 8, it is assumed that each carrier group contains 5 subcarriers, and 2 subcarriers are selected in the first carrier group according to its transmission characteristics, and the other subcarriers are not assigned data, which is shown as a disconnected state in the figure. In the second carrier group, because of its higher SIR value and better transmission performance, all five subcarriers are selected to transmit data. In the nth sub-carrier group, only one sub-carrier is selected for data transmission according to its transmission performance, and the other sub-carriers are not allocated data and are in a disconnected state.

After the serial-to-parallel conversion, all the subcarriers enter the IFFT unit 806 together, and the subcarriers assigned data in the serial-to-parallel conversion are directly sent to the IFFT unit 806 , and the subcarriers not assigned data are filled with 0 in the IFFT unit 806 . The transformed information needs to enter the guard interval adding and windowing unit 807 to prevent interference between subcarriers and avoid affecting the orthogonality between subcarriers.

Then, the information inserted into the guard interval is sent to the digital-to-analog converter 808, and the digital-to-analog converter 808 converts the signal from digital to analog form for transmission. Finally, the transmitter 809 sends the signal out.

Fig. 9 is a flow chart of the sending method of the OFDM system sending device in the present invention. In Fig. 9, the original information is encoded (step 901), redundant information is added to allow the receiving device to perform data error correction, and then interleaved (step 902) to combat burst interference or deep fading in the channel.

The interleaved data is modulated (step 903), and the binary bits are mapped to points in the constellation diagram to form corresponding symbols. Then a pilot is inserted (step 904), so that the receiving device can perform channel estimation. After the pilot is inserted, enter the process of serial-to-parallel conversion and subcarrier selection (step 907).

Before the serial-to-parallel conversion, it is necessary to extract the sub-carrier selection information of each carrier group (step 906) from the information fed back by the receiving device (step 905), and then perform serial-to-parallel conversion and sub-carrier selection. During serial-to-parallel conversion, data is allocated to different sub-carriers according to the obtained sub-carrier selection information. When processing the Nth subcarrier, if the subcarrier selection information returned from the receiving device indicates that the subcarrier is selected for data transmission (step 908), then allocate data on the subcarrier (step 909), otherwise, the No data is allocated on the subcarriers (step 910). If there are sub-carriers that have not been processed, the process continues (step 911).

After the processing of all subcarriers is completed, perform IFFT transformation (step 912), and then add guard interval and window to prevent the orthogonality between subcarriers from being destroyed. Then carry out digital-to-analog conversion (step 914 ), convert the digital signal into an analog signal, and then send information in step 915 .

Fig. 10 is a structural diagram of a receiving device of an OFDM system in the present invention. The receiving device includes a receiver (RFRX) 1001, an analog-to-digital converter (ADC) 1002, a deguard interval unit 1003, an FFT unit 1004, a parallel-serial conversion unit 1005, a plurality of channel estimation units 1006, a parallel-serial conversion unit 1007, Demodulation unit 1008 , deinterleaving unit 1009 , decoding unit 1010 , subcarrier group analyzer 1011 , control command generation unit 1012 , modulation unit 1013 , and transmitter (RFTX) 1014 .

In FIG. 10, after receiving the information, the receiver 1001 first converts it from radio frequency to base frequency.

The analog signal is converted into a digital signal through the analog-to-digital converter 1002 , and then the cyclic prefix added to maintain the orthogonality between subcarriers is removed through the deguard interval unit 1003 , and then the information enters the FFT unit 1004 . Multiple subcarriers are formed after FFT, some of which may not transmit data due to poor transmission performance.

In the parallel-to-serial conversion unit 1005 , the first parallel-to-serial conversion is performed on all subcarriers, and the parallel-to-serial conversion is performed under the control of the control command generation unit 1012 . The control command includes the selection of subcarriers in all carrier groups. After the first parallel-to-serial conversion, all subcarriers transmitting data in the same carrier group are merged together, and subcarriers that do not carry information are removed.

Then in the channel estimation unit 1006, the channel is estimated for each subcarrier group respectively, and the estimated result is input to the subcarrier group analyzer 1011 on the one hand, and used for channel compensation on the other hand.

After the channel estimation is completed, each carrier group enters the parallel-to-serial conversion unit 1007 again to synthesize one signal.

The synthesized signal is transmitted to the demodulation unit 1008 to demodulate the signal and recover the original binary signal. After completing these tasks, enter the de-interleaving unit 1009 to restore the original order of the signal,

Decoding is then performed in the decoding unit 1010 to correct correctable errors in the signal, remove redundant information, and restore the original data.

In addition, the channel estimation information is sent to the subcarrier group signal analyzer 1011, and the analyzer calculates the SIR value of each subcarrier group according to the estimation result.

The calculated SIR value is sent to the control command generation unit 1012, where the rate and puncturing information of each carrier group is generated. Then, the control command generation unit 102 stores the generated rate and puncturing information, so that the next received information can be processed accordingly when the serial-to-parallel conversion unit 1005 performs serial-to-parallel conversion. In addition, the generated rate and puncturing information is fed back to the sending device by the transmitter 1014 after being modulated by the modulation unit 1013 .

Fig. 11 is a flow chart of the receiving method of the receiving device of the OFDM system in the present invention. In FIG. 11, the receiving device first receives the information sent by the sending device (step 1101), and then performs analog-to-digital conversion (step 1102), converting the analog signal into a digital signal.

The obtained digital signal first removes the guard interval added by the sending device to maintain the orthogonality of subcarriers (step 1103), and then performs FFT (step 1104).

Multiple sub-carriers formed after FFT are subjected to parallel-to-serial transformation for the first time in step 1105, multiple sub-carriers in the same carrier group are combined, and then channel estimation is performed according to the pilot signal inserted in the signal (step 1106).

Perform performance analysis of subcarrier groups according to channel estimation results (step 1111), and then generate control information on subcarrier selection (step 1112). The control information includes grouping information of subcarriers in the next transmission obtained according to channel estimation and selection information of subcarriers in the grouping. These information are used to control the serial-to-parallel conversion (ST1105) when receiving the next information, so that the grouping of the sub-carrier groups and whether the sub-carriers in the group contain data information can be distinguished during the parallel-serial conversion. On the other hand, the information is modulated and converted into a signal form that is easy to send (step 1113), and then the control information is fed back to the sending device through step 1114, so as to control the rate of the carrier group of the sending device.

On the other hand, in step 1107, the channel estimated signal undergoes a second parallel-to-serial transformation to combine information of all carrier groups. Demodulate the combined information to restore the original binary signal (step 1108), and then de-interleave (step 1109) to restore the original sequence of the signal. Finally, decode (step 1110) to obtain the original information.

It should be noted that although the present invention is described above with respect to the structure of an OFDM communication system, the present invention can also be applied to any other sub-carrier communication systems that use sub-carriers for signal communication.

Although the present invention has been illustrated above in conjunction with preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications, substitutions and changes can be made to the present invention without departing from the spirit and scope of the present invention. . Therefore, the present invention is not limited by the above-mentioned embodiments.

Industrial availability

The transmitting device, receiving device, communication system, and communication method of the present invention are suitable for adaptive adjustment of the rate of a subcarrier group in a subcarrier communication system, for example.

Claims (20)

1. dispensing device comprises:

The subcarrier selected cell is selected feedback information according to the subcarrier that receives, and the subcarrier that generates and export each sub carrier group is selected signal;

Signal is selected according to the subcarrier of each sub carrier group in the data allocations unit, selects subcarrier required in each sub carrier group, simultaneously, and to distribute data on the selected subcarrier;

Contrary fast Fourier transform unit is carried out contrary fast fourier transform to the data of distributing to each subcarrier in described data allocations unit; And

Transmitting element, the data after the contrary fast fourier transform of transmission.

2. dispensing device according to claim 1, wherein, described each sub carrier group has equal sub-carrier number.

3. dispensing device according to claim 2 wherein, is determined sub-carrier number in the sub carrier group according to the size of the Doppler frequency shift of receiving terminal.

4. dispensing device according to claim 1, wherein, described subcarrier selects feedback information to be the information table of punchinging, and the described information table of punchinging is represented available subcarrier number and available subcarrier label in each sub carrier group.

5. receiving system comprises:

Receiving element receives data;

Fast Fourier transform unit is carried out fast fourier transform to described data;

The first parallel serial conversion unit, carry out first parallel serial conversion according to the described data of the first parallel serial conversion control signal after to fast fourier transform, through behind described first parallel serial conversion, the sub carrier group of all data in the same carrier wave set is lumped together, and each sub carrier group after the output combination;

A plurality of channel estimating unit are to carrying out channel estimating through each of the respective sub group of first parallel serial conversion;

The sub carrier group analyzer is analyzed channel estimation results, calculates the sir value of each sub carrier group;

The control command generation unit, sir value according to each sub carrier group generates subcarrier selection feedback information, and select in the feedback information in each carrier wave set the selection information of subcarrier is generated the described first parallel serial conversion control signal according to the described subcarrier that generates; And

Transmitting element sends described subcarrier and selects feedback information.

6. receiving system according to claim 5 wherein, also comprises: the second parallel serial conversion unit, carry out second parallel serial conversion to each sub carrier group after the described channel estimating, behind second parallel serial conversion, with the synthetic circuit-switched data of the data set of each sub carrier group.

7. receiving system according to claim 5, wherein, described each sub carrier group has equal sub-carrier number.

8. receiving system according to claim 7 wherein, is determined sub-carrier number in the sub carrier group according to the size of Doppler frequency shift.

9. receiving system according to claim 5, wherein, described subcarrier selects feedback information to be the information table of punchinging, and the described information table of punchinging is represented available subcarrier number and available subcarrier label in each sub carrier group.

10. receiving system according to claim 9, wherein, described control command generation unit is set the described information table of punchinging by following mode: when generating described subcarrier and selecting feedback information, at the sir value of the sub carrier group of alternative during greater than the sir value of the sub carrier group of the both sides of the sub carrier group of described alternative, at the bigger available subcarrier number of the sub carrier group setting of described alternative, simultaneously, determine the available subcarrier label according to the performance of the sub carrier group of described both sides; And the sir value of the sub carrier group of alternative is during less than the sir value of the sub carrier group of the both sides of the sub carrier group of described alternative, sub carrier group at described alternative is provided with less available subcarrier number, simultaneously, determine the available subcarrier label according to the performance of the sub carrier group of described both sides.

11. receiving system according to claim 10, wherein, in the available subcarrier label that carries out according to the performance of the sub carrier group of described both sides described determined, at the sir value of the sub carrier group of described both sides during less than the sir value of the sub carrier group of alternative, in the sub carrier group of described alternative, select quantity to equal the available subcarrier of determined available subcarrier number at random, determine the available subcarrier label; At the sir value of one of two sub carrier group of described both sides during greater than the sir value of the sub carrier group of alternative, more relatively subcarrier is selected in the nearer position of sub carrier group that has big SIR in the sub carrier group of described alternative in the sub carrier group of described both sides, and has the nearer less relatively subcarrier of position selection of sub carrier group of less SIR in the sub carrier group of described alternative in the sub carrier group of described both sides; At the sir value of two sub carrier group of described both sides during all greater than the sir value of the sub carrier group of alternative, more relatively subcarrier is selected in nearer position in the sub carrier group of described both sides in the sub carrier group of described alternative, and select less relatively subcarrier at the place, centre position of the sub carrier group of described alternative, perhaps come the chooser carrier wave randomly or with fixed intervals in the sub carrier group of described alternative.

12. one kind has the communication system that is used to send the dispensing device of signal and is used for the receiving system of received signal,

Described dispensing device comprises:

The subcarrier selected cell is selected feedback information according to the subcarrier that receives, and the subcarrier that generates and export each sub carrier group is selected signal;

Signal is selected according to the subcarrier of each sub carrier group in the data allocations unit, selects subcarrier required in each sub carrier group, simultaneously, and to distribute data on the selected subcarrier;

Contrary fast Fourier transform unit is carried out contrary fast fourier transform to the data of distributing to each subcarrier in described data allocations unit; And

Transmitting element, the data after the contrary fast fourier transform of transmission,

Described receiving system comprises:

Receiving element receives data;

Fast Fourier transform unit is carried out fast fourier transform to described data;

The first parallel serial conversion unit, carry out first parallel serial conversion according to the described data of the first parallel serial conversion control signal after to fast fourier transform, through behind described first parallel serial conversion, the sub carrier group of all data in the same carrier wave set is lumped together, and each sub carrier group after the output combination;

A plurality of channel estimating unit are to carrying out channel estimating through each of the respective sub group of first parallel serial conversion;

The sub carrier group analyzer is analyzed channel estimation results, calculates the sir value of each sub carrier group;

The control command generation unit, sir value according to each sub carrier group generates subcarrier selection feedback information, and select in the feedback information in each carrier wave set the selection information of subcarrier is generated the described first parallel serial conversion control signal according to the described subcarrier that generates; And

Transmitting element sends the signal with described subcarrier selection feedback information.

13. communication system according to claim 12, wherein, also comprise: the second parallel serial conversion unit, carry out second parallel serial conversion to each sub carrier group after the described channel estimating, behind second parallel serial conversion, with the synthetic circuit-switched data of the data set of each sub carrier group.

14. a communication means may further comprise the steps:

Receiving system receives data;

Described data are carried out fast fourier transform;

Carry out first parallel serial conversion according to the described data of the first parallel serial conversion control signal after to described fast fourier transform;

Through behind described first parallel serial conversion, the sub carrier group of all data in the same carrier wave set is lumped together, and export each sub carrier group after the described combination;

Each of sub carrier group after the described combination is carried out channel estimating;

Described channel estimation results is analyzed, calculated the sir value of each sub carrier group;

Generate subcarrier according to the sir value of each sub carrier group and select feedback information, and select in the feedback information in each carrier wave set the selection information of subcarrier is generated the described first parallel serial conversion control signal according to the described subcarrier that generates;

Send described subcarrier and select feedback information;

Dispensing device receives described subcarrier and selects feedback information;

Select feedback information according to the described subcarrier that receives, the subcarrier that generates and export each sub carrier group is selected signal;

Subcarrier according to each sub carrier group is selected signal, selects subcarrier required in each sub carrier group, simultaneously, and to distribute data on the selected subcarrier;

The data of distributing to each subcarrier are carried out contrary fast fourier transform; And

By the data after the contrary fast fourier transform of dispensing device transmission.

15. communication means according to claim 14 is wherein, further comprising the steps of: each sub carrier group after the described channel estimating is carried out second parallel serial conversion, through second parallel serial conversion, with the synthetic circuit-switched data of the data set of each sub carrier group.

16. communication means according to claim 14, wherein, described each sub carrier group has equal sub-carrier number.

17. communication means according to claim 16 wherein, is determined sub-carrier number in the sub carrier group according to the size of the Doppler frequency shift of described receiving system.

18. communication means according to claim 17, wherein, described subcarrier selects feedback information to be the information table of punchinging, and the described information table of punchinging is represented available subcarrier number and available subcarrier label in each sub carrier group.

19. communication means according to claim 18, wherein, the described information table of punchinging is set by following mode: when the described subcarrier of generation is selected feedback information, at the sir value of the sub carrier group of alternative during greater than the sir value of the sub carrier group of the both sides of the sub carrier group of described alternative, at the bigger available subcarrier number of the sub carrier group setting of described alternative, simultaneously, determine the available subcarrier label according to the performance of the sub carrier group of described both sides; And the sir value of the sub carrier group of alternative is during less than the sir value of the sub carrier group of the both sides of the sub carrier group of described alternative, sub carrier group at described alternative is provided with less available subcarrier number, simultaneously, determine the available subcarrier label according to the performance of the sub carrier group of described both sides.

20. communication means according to claim 19, wherein, in the available subcarrier label that carries out according to the performance of the sub carrier group of described both sides described determined, at the sir value of the sub carrier group of described both sides during less than the sir value of the sub carrier group of alternative, in the sub carrier group of described alternative, select quantity to equal the available subcarrier of determined available subcarrier number at random, determine the available subcarrier label; At the sir value of one of two sub carrier group of described both sides during greater than the sir value of the sub carrier group of alternative, more relatively subcarrier is selected in the nearer position of sub carrier group that has big SIR in the sub carrier group of described alternative in the sub carrier group of described both sides, and has the nearer less relatively subcarrier of position selection of sub carrier group of less SIR in the sub carrier group of described alternative in the sub carrier group of described both sides; At the sir value of two sub carrier group of described both sides during all greater than the sir value of the sub carrier group of alternative, more relatively subcarrier is selected in nearer position in the sub carrier group of described both sides in the sub carrier group of described alternative, and select less relatively subcarrier at the place, centre position of the sub carrier group of described alternative, perhaps come the chooser carrier wave randomly or with fixed intervals in the sub carrier group of described alternative.

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