CN101383793B - Method, apparatus and system for signal transmission and channel estimation - Google Patents
Method, apparatus and system for signal transmission and channel estimation Download PDFInfo
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- CN101383793B CN101383793B CN 200710076939 CN200710076939A CN101383793B CN 101383793 B CN101383793 B CN 101383793B CN 200710076939 CN200710076939 CN 200710076939 CN 200710076939 A CN200710076939 A CN 200710076939A CN 101383793 B CN101383793 B CN 101383793B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0224—Channel estimation using sounding signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
Abstract
The invention relates to the wireless communication field, and discloses a channel estimating method and the device thereof. The method can improve the channel estimating performance of the OFDM system without increasing the pilot frequency spending. The invention demodulates and decodes the data in virtual pilot channel, checks the decoded result, and reconstructs the decoded result as virtual pilot symbols and uses virtual pilot symbols and actual pilot symbols to estimate the channel when the decoded result passes through the check. All subcarriers forming the virtual pilot channel and allsubcarriers which are used for transmitting pilot symbols complement each other; for example, the two groups of subcarriers can be crosswise arranged at equal intervals.
Description
Technical field
The present invention relates to wireless communication field, particularly signal sends and channel estimation technique.
Background technology
The basis of OFDM (Orthogonal Frequency Division Multiplexing is called for short " OFDM ") technology is orthogonal multiple carrier, and it can be avoided in the Effective Raise transmission rate because the various interference that cause at a high speed.Adopt the OFDM technology can reach higher message transmission rate, in WLAN (wireless local area network), adopted at present this technology.
The basic principle of OFDM is by serial/parallel conversion data flow at a high speed, be assigned in several relatively low subchannels of speed and transmit, therefore, symbol period in every sub-channels can increase relatively, can alleviate because the intersymbol interference that the temporal dispersion that the multidiameter delay expansion of wireless channel produces causes system.In addition, because the introducing at protection interval, in the situation that the protection interval greater than maximum multipath delay spread, can also be eliminated to greatest extent because the intersymbol interference that multipath brings.If adopt Cyclic Prefix as the protection interval, can also avoid because the interchannel interference that multipath brings.
A major issue in ofdm system is channel estimating, and the performance of therefore improving channel estimating is significant.In ofdm system, generally adopt at present the channel estimation methods based on pilot tone, channel estimating based on pilot tone is generally divided two steps: first step is that pilot tone is estimated, namely the channel on the pilot frequency locations is estimated, specifically can be adopted criterion of least squares, minimum mean square error criterion etc.; Second step is Interpolate estimation, the channel that namely non-pilot symbol is set up is estimated, carry out interpolation according to the pilot frequency locations upper signal channel coefficient that has estimated and just can obtain the channel coefficients that non-pilot symbol is set up, specifically can adopt simple linear interpolation, also can adopt the more complicated methods such as high-order interpolation.
At present, in ofdm system, there have been some to use the research of virtual pilot frequency technology, such as the OFDM channel estimation scheme based on virtual pilot frequency and power control, it has used reliable data as virtual pilot frequency, and to these virtual pilot frequency power control, Fig. 1 has provided the schematic diagram of this scheme system receiving terminal.Concrete method of estimation can be summarized as following steps: at first, utilize pilot symbol transmitted to obtain initial channel estimation.Then, utilize the initial channel estimation information that obtains, carry out to received signal the channel fading compensation, obtain first modulated data symbol.Then first modulated data symbol of demodulation, the acquired information bit, the map information bit is the second modulation symbol again.To all data subcarriers, calculate the Euclidean distance between the first modulated data symbol and the second modulation symbol.If the Euclidean distance on certain subcarrier in a predefined threshold value, just is chosen as empty pilot tone so accordingly.Utilize at last real pilot tone and empty pilot tone, channel frequency response is carried out precision estimate.
Yet, the present inventor finds, in the OFDM channel estimation scheme based on virtual pilot frequency and power control, need to carry out demodulation to user data, and whether can be as virtual pilot frequency according to the distance threshold decision signal that receives between signal and the demodulation symbol, the virtual pilot frequency that chooses and actual pilot combined finish channel estimating, this mode can not be guaranteed the correctness of demodulation on the virtual pilot frequency symbol, thereby can not guarantee the reliability of virtual pilot frequency place channel estimating.In addition, user terminal will carry out virtual pilot frequency for each data subcarrier to be selected, thereby so that complexity is higher.
Summary of the invention
The technical problem underlying that embodiment of the present invention will solve provides a kind of channel estimation methods, device and system thereof, can improve the channel estimation reliability of ofdm system and the performance of raising ofdm system.
Another technical problem underlying that embodiment of the present invention will solve provides a kind of signaling method based on virtual pilot frequency, device, reduces the complexity of virtual pilot frequency technology and the performance of raising ofdm system.
For solving the problems of the technologies described above, embodiments of the present invention provide a kind of channel estimation methods, may further comprise the steps:
Data to the virtual pilot frequency channel are made demodulating and decoding;
Decoded result is carried out verification;
If by verification, then with decoded result reconstruct as the virtual pilot frequency symbol;
Use virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating.
Embodiments of the present invention also provide a kind of channel estimating apparatus, comprising:
Demodulating unit is used for the data of virtual pilot frequency channel are carried out demodulation;
Decoding unit is used for the decoding data after the demodulating unit demodulation;
Verification unit is used for the decoded result of decoding unit is carried out verification;
Judging unit is used for judging the whether verification by verification unit of decoded result;
Estimation unit is used for when judging unit is judged the verification of passing through verification unit, as the virtual pilot frequency symbol, uses virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating decoded result reconstruct.
Embodiments of the present invention also provide a kind of channel estimation system, comprising:
The first receiver is used for receiving user data and pilot data;
The second receiver, for the data that receive the virtual pilot frequency channel, wherein said the second receiver is decoded as the virtual pilot frequency symbol with the data demodulates of virtual pilot frequency channel, and wherein said virtual pilot frequency symbol is the symbol after the decoded result by verification is reconstructed;
Wherein, described the first receiver comprises a channel estimating unit, and it carries out channel estimating according to virtual pilot frequency symbol and actual pilot symbol.
For solving the problems of the technologies described above, embodiments of the present invention provide a kind of signaling method, may further comprise the steps:
Consist of the virtual pilot frequency channel by one group of subcarrier that is used for the transmission of data of reserving;
Give at least one user terminal with described virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation;
Send the data in the described virtual pilot frequency channel.
For solving the problems of the technologies described above, embodiments of the present invention provide a kind of sender unit, comprising:
The channel Component units is used for one group of subcarrier that is used for the transmission of data of reserving is consisted of the virtual pilot frequency channel;
Channel-assignment unit is given at least one user terminal with described virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation;
Transmitting element is for the data that send described virtual pilot frequency channel.
Embodiment of the present invention compared with prior art, the main distinction and effect thereof are:
Consist of the virtual pilot frequency channel by one group of subcarrier that is used for the transmission of data of reserving, do not choose empty pilot tone after need to not calculated all data subcarriers by terminal, thereby reduce system complexity.
Data to the virtual pilot frequency channel are made demodulating and decoding, and decoded result is carried out verification, if by verification, then with decoded result reconstruct as the virtual pilot frequency symbol, use virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating.Owing to when carrying out channel estimating, not only having used the actual pilot symbol, also used the virtual pilot frequency symbol by verification, not only can guarantee the reliability of virtual pilot frequency channel estimating, and improve the channel estimating performance of ofdm system.
Because the virtual pilot frequency channel still is used for the transfer of data of user terminal, so embodiments of the present invention do not increase the expense of pilot tone, have avoided the waste to system time frequency resource.
To the larger user terminal of signal attenuation, such as the user terminal of cell edge, can utilize virtual pilot frequency to carry out channel estimating so that be positioned at the user terminal of center of housing estate virtual pilot frequency channel priority allocation.Because being positioned at the user terminal of center of housing estate all is the user terminal with higher work signal to noise ratio basically, therefore, by by the user terminal that is positioned at center of housing estate, utilize virtual pilot frequency to obtain more accurately channel estimating, can so that the effective rate of utilization of virtual pilot frequency channel demonstrated fully so that systematic function can have larger improvement.
The virtual pilot frequency channel design is become complementary with the actual pilot channel, be equivalent to improve pilot density, thereby guaranteed the improvement of channel estimating performance.
The virtual pilot frequency channel uses the low code modulation mode of complexity, has guaranteed that the complexity of system can not increase much when improving channel estimating performance.
Description of drawings
Fig. 1 is the schematic diagram of system receiving terminal in the prior art;
Fig. 2 is the receiving terminal structural representation according to first embodiment of the invention;
Fig. 3 is the channel estimation methods flow chart according to first embodiment of the invention;
Fig. 4 is the virtual pilot frequency the first pattern schematic diagram according to first embodiment of the invention;
Fig. 5 is the virtual pilot frequency the second pattern schematic diagram according to first embodiment of the invention;
Fig. 6 is the third pattern schematic diagram of virtual pilot frequency according to first embodiment of the invention;
Fig. 7 is the Block Error Rate simulation result schematic diagram according to first embodiment of the invention;
Fig. 8 is the channel estimating apparatus structure chart according to third embodiment of the invention.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing embodiments of the present invention are described in further detail.
The first execution mode of the present invention relates to a kind of channel estimation methods, may further comprise the steps:,
First step: the data to the virtual pilot frequency channel are made demodulating and decoding;
Second step: decoded result is carried out verification;
Third step: if by verification, then with decoded result reconstruct as the virtual pilot frequency symbol;
The 4th step: use virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating.
Wherein the virtual pilot frequency symbol is to utilize the symbol that sends behind decoded result and transmitted power, the modulation coding mode signal reconstruct in the third step.Wherein first embodiment of the invention is specifically addressed in connection with the mechanism of receiver of the present invention.
In the present embodiment, the basic structure of receiver as shown in Figure 2, it comprises receiver 10 and receiver 20, wherein receiver 10 is traditional OFDM receiver, receiver 20 is compared with receiver 10, OFDM is transmitted and received branch road need to carry out certain modification, and concrete modification comprises: increased the virtual pilot frequency channel, increased signaling, increased the virtual pilot frequency data receiving channel and revised the channel estimation function module.
Wherein, embodiments of the present invention provide a kind of signaling method based on virtual pilot frequency, may further comprise the steps:
The first step consists of the virtual pilot frequency channel by one group of subcarrier that is used for the transmission of data of reserving;
Second step is given at least one user terminal with described virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation;
In the 3rd step, send the data in the described virtual pilot frequency channel.
According to above-mentioned signaling method, embodiments of the present invention provide a kind of sender unit based on virtual pilot frequency, comprising:
The channel Component units is used for one group of subcarrier that is used for the transmission of data of reserving is consisted of the virtual pilot frequency channel;
Channel-assignment unit is given at least one user terminal with described virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation;
Transmitting element is for the data that send described virtual pilot frequency channel.
Wherein, the virtual pilot frequency channel of increase is made of one group of data subcarrier of reserving; The signaling that increases can make system the relevant information of virtual pilot frequency channel can be broadcast to all user terminals; The virtual pilot frequency data receiving channel that increases is so that user terminal can receive the data of virtual pilot frequency channel; The input data of amended channel estimation function module are except actual pilot receives signal, the control signal that the errored block sign that also has virtual pilot frequency to receive signal, reconstruction signal and obtained by cyclic redundancy check (CRC) (Cyclic Redundancy Check is called for short " CRC ") consists of.
In the present embodiment, system will reserve the subcarrier that a part is used for the transmission of data, the subcarrier that is used for the transmission of data by this part that reserve consists of the virtual pilot frequency channel, again with the virtual pilot frequency channel allocation that consists of to the unique user terminal, perhaps the virtual pilot frequency channel distribution is several groups, give a plurality of user terminals, the user terminal that is assigned the virtual pilot frequency channel uses the virtual pilot frequency transmission user data that distributes.Because the virtual pilot frequency channel still is used for the transfer of data of user terminal, so present embodiment do not increase the expense of pilot tone, avoided the waste to system time frequency resource.The user terminal that is assigned the virtual pilot frequency channel is the larger user terminal of signal attenuation.Because the virtual pilot frequency channel allocation to the larger user terminal of signal attenuation, can utilize virtual pilot frequency to carry out channel estimating so that be positioned at the user terminal of center of housing estate.The user terminal that is positioned at center of housing estate all is the user terminal with higher work signal to noise ratio basically, therefore, by the user terminal that is positioned at center of housing estate, utilize virtual pilot frequency to obtain more accurately channel estimating, can so that the effective rate of utilization of virtual pilot frequency channel demonstrated fully so that systematic function can have larger improvement.
System needs the relevant information of virtual pilot frequency channel is broadcast to all user terminals by signaling, and relevant information comprises subcarrier number and the position of virtual pilot frequency channel, power and code modulation mode that the virtual pilot frequency channel uses.Wherein, the power of virtual pilot frequency channel use is more than or equal to the power of pilot channel use; The code modulation mode of virtual pilot frequency channel is the low code modulation mode of complexity, thereby has guaranteed that the complexity of system can not increase much when improving channel estimating performance; The code modulation mode that the virtual pilot frequency channel uses should be able to change encoding block length easily, as adopting the code modulation mode of convolution code.Because the virtual pilot frequency channel still is used for the transfer of data of user terminal, the data volume possibility of therefore carrying in the virtual pilot frequency channel is more also may be less, if the encoding block length that coded system produces is fixed, then when data volume is less, possibly can't obtain required encoding block length, so use the coded systems such as convolution code, and encoding block length rationally be set.
The below is specifically described the flow process of the channel estimation methods of present embodiment, as shown in Figure 3.
In step 410, user terminal is made demodulating and decoding to the data of virtual pilot frequency channel.Specifically, user terminal obtains the relevant information of virtual pilot frequency channel from broadcast message, according to the relevant information of the virtual pilot frequency channel that obtains, receives the data of virtual pilot frequency channel, and the data of virtual pilot frequency channel are carried out demodulating and decoding.Wherein, the user terminal of the data of virtual pilot frequency channel being made demodulating and decoding is the unallocated user terminal that the virtual pilot frequency channel is arranged.
Then, enter step 420, user terminal carries out verification to the result of decoding.That is to say, user terminal carries out CRC check to the result of decoding.
Then, enter step 430, judge whether by verification, if by verification, then enter step 450, if not by verification, then enter step 440.That is to say, user terminal judges by CRC check whether the encoding block that the coded system of virtual pilot frequency channel use produces is correctly decoded, if this encoding block is correctly decoded, namely the result of decoding is by verification, then enter step 450, if this encoding block is not correctly decoded, namely the result of decoding then enters step 440 not by verification.
In step 440, use the actual pilot symbol to carry out channel estimating.That is to say, when encoding block is not correctly decoded, when namely the virtual pilot frequency data have error code, so that the virtual pilot frequency symbol can not be reconstructed fully, so only use the actual pilot symbol to carry out channel estimating.
In step 450, with decoded result reconstruct as the virtual pilot frequency symbol.Specifically, after encoding block is correctly decoded, in conjunction with the relevant information of from broadcast message, obtaining the virtual pilot frequency channel, carry out signal reconstruction, obtain the virtual pilot frequency symbol.
In step 460, use virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating.That is to say, the virtual pilot frequency that receives and actual pilot symbol are combined, and utilize the virtual pilot frequency that obtains after the reconstruct to send symbol and known actual pilot transmission symbolic information, jointly finish channel estimating.
This shows, because when carrying out channel estimating, not only used the actual pilot symbol, also used the virtual pilot frequency symbol by verification, thereby can improve the channel estimating performance of ofdm system, and then significantly promoted the throughput of system, reduced the QAM high order modulation user's of residential quarter work thresholding.
In addition, it is worth mentioning that, present embodiment can be the subcarrier (namely consisting of the subcarrier of virtual pilot frequency channel) that is used for the transmission of data of reserving and the equally spaced cross arrangement of each subcarrier that is used for transmitted pilot symbol, the virtual pilot frequency channel design is become complementary with the actual pilot channel, be equivalent to like this improve pilot density, thereby guaranteed the improvement of channel estimating performance.Wherein intend pilot tone and can be used for improving pilot density on the frequency domain, also can be used for improving the pilot density on the time domain, perhaps both combinations, wherein virtual pilot frequency and 2: 1 situation of actual pilot quantity are example, the virtual pilot frequency pattern can illustrate such as Fig. 4, Fig. 5, Fig. 6 the design of three kinds of virtual pilot frequencies, and wherein to plant D be data for Fig. 4, Fig. 5, Fig. 6; R1 is the first reference symbol; R2 is that the second reference symbol: V is the virtual reference symbol:
Wherein Fig. 4 is for increasing the pilot density on the time domain.Pilot interval diminishes on the time domain, and pilot interval is constant on the frequency domain.Be suitable for the higher scene of translational speed, this moment, the time selectivity of channel was stronger, adopted the algorithm of frequency domain after the first time domain during channel estimating, can obtain higher gain.
Wherein Fig. 5 is for increasing the pilot density on the frequency domain.Pilot interval is constant on the time domain, and pilot interval diminishes on the frequency domain.Be suitable for time delay expansion large, the channel scene that namely frequency selectivity is stronger adopts the channel estimation method of time domain behind the first frequency domain, can obtain higher gain.
Wherein Fig. 6 is for increasing simultaneously the time-domain and frequency-domain pilot density.Pilot interval diminishes on the time domain, and pilot interval also diminishes on the frequency domain.This mode is applicable to translational speed and the moderate scene of time delay expansion.
Wherein Fig. 4, Fig. 5, Fig. 6 are the subcarrier that is used for the transmission of data of reserving and each subcarrier that is used for transmitted pilot symbol three kinds of execution modes of cross arrangement equally spaced, the invention is not restricted to above-mentioned three kinds of arrangement modes, any pattern with virtual pilot frequency channel design one-tenth and the complementation of actual pilot channel all is applicable to the present invention.
Come comparison to double difference between the scheme of virtual pilot frequency of later traditional scheme and present embodiment without traditional scheme, the pilot tone of virtual pilot frequency below by experiment simulation.What this experiment was adopted is that bandwidth is the descending OFDM access of Long Term Evolution (Long Term Evolution is called for short " LTE ") (Orthogonal Frequency Multiple Access is called for short " the OFDMA ") link of 20MHz.The channel estimation methods of emulation adopts least-squares estimation and single order interpolation.The virtual pilot frequency symbol all adopts quadrature photograph key (Quadrature Phases Shift Keying is called for short " QPSK ") modulation in the emulation, and virtual pilot frequency power equals public guide frequency power.The parameters of experiment simulation is as shown in table 1.
| Parameter | Numerical value |
| Carrier frequency (GHz) | 2.5 |
| Transmission bandwidth (MHz) | 20 |
| The subframe duration (ms) | 0.5 |
| Sample rate (MHz) | 30.72 |
| The IFFT size | 2048 |
| Number of sub carrier wave | 1201 |
| The CP number of samples | 512 (long CP) |
| Each interpolation for the OFDM number of |
6 |
| Channel | SCME/SCM?Suburban?Marco |
| Chnnel coding | Turbor＝1/3 |
| Coded block size (bit/block) | 250 |
| Data modulation | QPSK；16QAM；64QAM |
| UE speed (km/h) | 30 |
| Pilot frequency design | The first reference signal and the second reference signal |
| Channel estimating | 2 step linear interpolations (first step at time domain interpolation, second step at frequency domain interpolation) or perfect estimation |
| The virtual pilot frequency parameter | Numerical value |
| Chnnel coding | TbCCr＝1/2 |
| Coded block size (bit/block) | 400 |
| Data Modulation | QPSK |
| The virtual pilot frequency number | Identical with number of pilots (400) |
| The virtual pilot frequency pattern | Similar with pilot frequency design |
Table 1
The Block Error Rate performance curve of this experiment simulation as shown in Figure 7.Abscissa among Fig. 7 represents channel estimating performance; Ordinate presentation code Block Error Rate.As we know from the figure, in the situation of identical channel estimating performance, the coding Block Error Rate of employing virtual pilot frequency scheme is lower than the coding Block Error Rate without the traditional scheme of virtual pilot frequency all the time; In the situation of identical coding Block Error Rate, the channel estimating performance of employing virtual pilot frequency scheme is better than the channel estimating performance without the traditional scheme of virtual pilot frequency all the time.Under in 64QAM modulation, when Block Error Rate is 0.001, adopts the performance of virtual pilot frequency scheme and be about 1dB without the performance difference of virtual pilot frequency scheme; For 16QAM, its performance difference is about 0.5dB.Be better than the virtual pilot frequency scheme although adopt pilot tone to double later traditional scheme in the Block Error Rate performance, adopt pilot tone to double the expense that later traditional scheme has increased pilot tone, cause the waste of system time frequency resource.And in the virtual pilot frequency scheme, the virtual pilot frequency channel still is used for the transfer of data of user terminal, does not therefore increase the expense of pilot tone, has avoided the waste to system time frequency resource.
The second execution mode of the present invention relates to a kind of channel estimation methods equally, and present embodiment and the first execution mode are roughly the same, and its difference is, in the first embodiment, the power that the virtual pilot frequency channel uses is a grade; And in the present embodiment, the power that the virtual pilot frequency channel uses can be a plurality of grades according to the different demarcation of user terminal present position, and the grade of power is broadcast to all user terminals by signaling.Because come the power that the virtual pilot frequency channel uses is divided according to the position of user terminal, so that the user terminal of diverse location can use the power of different virtual pilot channel, thereby so that embodiments of the present invention are more flexible.
The 3rd execution mode of the present invention relates to a kind of channel estimating apparatus, as shown in Figure 8, comprising: demodulating unit is used for the data of virtual pilot frequency channel are carried out demodulation; Decoding unit is used for the decoding data after the demodulating unit demodulation; Verification unit is used for the decoded result of decoding unit is carried out verification; Judging unit is used for judging the whether verification by verification unit of decoded result; Estimation unit is used for when judging unit is judged the verification of passing through verification unit, as the virtual pilot frequency symbol, uses virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating decoded result.
Because when carrying out channel estimating, not only use the actual pilot symbol, also used the virtual pilot frequency symbol by verification, thereby can improve the channel estimating performance of ofdm system, and then significantly promoted the throughput of system, reduced the QAM high order modulation user's of residential quarter work thresholding.
The virtual pilot frequency channel is made of one group of subcarrier that is used for the transmission of data of reserving, each subcarrier that is used for the transmission of data of this reservation, with each subcarrier that is used for transmitted pilot symbol, equally spaced cross arrangement, that is to say, the virtual pilot frequency channel design is become complementary with the actual pilot channel, be equivalent to improve pilot density, thereby guaranteed the improvement of channel estimating performance, and because the virtual pilot frequency channel still is used for the transfer of data of user terminal, therefore present embodiment does not increase the expense of pilot tone, has avoided the waste to system time frequency resource.
The code modulation mode that this virtual pilot frequency channel uses is the low code modulation mode of complexity; And/or, the power that the power that this virtual pilot frequency channel uses uses more than or equal to pilot channel.Because the code modulation mode that the virtual pilot frequency channel uses is the low code modulation mode of complexity, guaranteed that the complexity of system can not increase much when improving channel estimating performance.
This channel estimating apparatus can also comprise: acquiring unit, for the relevant information of obtaining this virtual pilot frequency channel from broadcast message; Receiving element for the relevant information of this virtual pilot frequency channel that obtains according to acquiring unit, receives the data of this virtual pilot frequency channel; The relevant information of this virtual pilot frequency channel that the demodulation in this channel estimating apparatus, decoding unit are obtained according to acquiring unit is carried out demodulation, decoding.
Estimation unit in this channel estimating apparatus also is used for using the actual pilot symbol to carry out channel estimating when judging unit is judged the verification of not passing through verification unit.
In addition, it is worth mentioning that, each unit in the present embodiment is logical block, in actual applications, various physics realization mode can be arranged.
In sum, in embodiments of the present invention, the data of virtual pilot frequency channel are made demodulating and decoding, decoded result is carried out verification, if by verification, then with decoded result as the virtual pilot frequency symbol, use virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating.Because when carrying out channel estimating, not only used the actual pilot symbol, also used the virtual pilot frequency symbol by verification, thereby can improve the channel estimating performance of ofdm system, and then significantly promoted the throughput of system, reduced quadrature amplitude modulation (QUADRATURE AMPLITUDE MODULATION is called for short " QAM ") the high order modulation user's of residential quarter work thresholding.
Because the virtual pilot frequency channel still is used for the transfer of data of user terminal, so embodiments of the present invention do not increase the expense of pilot tone, have avoided the waste to system time frequency resource.
To the larger user terminal of signal attenuation, such as the user terminal of cell edge, can utilize virtual pilot frequency to carry out channel estimating so that be positioned at the user terminal of center of housing estate the virtual pilot frequency channel allocation.Because being positioned at the user terminal of center of housing estate all is the user terminal with higher work signal to noise ratio basically, therefore, by by the user terminal that is positioned at center of housing estate, utilize virtual pilot frequency to obtain more accurately channel estimating, can so that the effective rate of utilization of virtual pilot frequency channel demonstrated fully so that systematic function can have larger improvement.
Consist of each subcarrier of virtual pilot frequency channel, with each subcarrier that is used for transmitted pilot symbol, equally spaced cross arrangement, that is to say, the virtual pilot frequency channel design is become complementary with the actual pilot channel, be equivalent to improve pilot density, thereby guaranteed the improvement of channel estimating performance.
The code modulation mode that the virtual pilot frequency channel uses is the low code modulation mode of complexity, has guaranteed that the complexity of system can not increase much when improving channel estimating performance.
Although pass through with reference to some of the preferred embodiment of the invention, the present invention is illustrated and describes, but those of ordinary skill in the art should be understood that and can do various changes to it in the form and details, and without departing from the spirit and scope of the present invention.
Claims (25)
1. a channel estimation methods is characterized in that, may further comprise the steps:
Give at least one user terminal with the virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation; Wherein said virtual pilot frequency channel is made of one group of subcarrier that is used for the transmission of data of reserving;
Data to the virtual pilot frequency channel are made demodulating and decoding; The user terminal of wherein data of virtual pilot frequency channel being made demodulating and decoding is the unallocated user terminal that the virtual pilot frequency channel is arranged;
Decoded result is carried out verification;
If by verification, then with decoded result reconstruct as the virtual pilot frequency symbol;
Use virtual pilot frequency symbol and actual pilot symbol to carry out channel estimating.
2. channel estimation methods according to claim 1 is characterized in that, described virtual pilot frequency symbol is by decoded result, transmitted power and modulation coding mode signal reconstruct.
3. channel estimation methods according to claim 1 is characterized in that, each subcarrier that is used for the transmission of data of described reservation complements each other with each subcarrier that is used for transmitted pilot symbol, wherein adopts equally spaced cross arrangement.
4. channel estimation methods according to claim 1 is characterized in that, and is before described data to the virtual pilot frequency channel are made the step of demodulating and decoding, further comprising the steps of:
From broadcast message, obtain the relevant information of described virtual pilot frequency channel;
According to the relevant information of the described virtual pilot frequency channel that obtains, receive the data of described virtual pilot frequency channel;
Do in the step of demodulating and decoding in described data to the virtual pilot frequency channel, according to the relevant information of the described virtual pilot frequency channel that obtains, carry out described demodulating and decoding; The relevant information of wherein said virtual pilot frequency channel comprises one of following content or its combination in any:
Consist of the number of subcarrier of described virtual pilot frequency channel and the power that position, described virtual pilot frequency channel use, the code modulation mode that described virtual pilot frequency channel uses.
5. each described channel estimation methods in 4 according to claim 1 is characterized in that, described virtual pilot frequency channel uses the low code modulation mode of complexity.
6. each described channel estimation methods in 4 according to claim 1 is characterized in that the power that the power that described virtual pilot frequency channel uses uses more than or equal to the actual pilot channel.
7. each described channel estimation methods in 4 according to claim 1 is characterized in that, and is further comprising the steps of:
If described verification is not passed through, then use the actual pilot symbol to carry out channel estimating.
8. a channel estimating apparatus is characterized in that, comprising:
Acquiring unit, for the relevant information of obtaining the virtual pilot frequency channel from broadcast message, wherein said virtual pilot frequency channel is to distribute at least one user terminal, and the larger described virtual pilot frequency channel of the preferential acquisition of user terminal of signal attenuation; And described virtual pilot frequency channel is made of one group of subcarrier that is used for the transmission of data of reserving;
Demodulating unit is used for the data of virtual pilot frequency channel are carried out demodulation; The user terminal of wherein data of virtual pilot frequency channel being made demodulating and decoding is the unallocated user terminal that the virtual pilot frequency channel is arranged;
Decoding unit is used for the decoding data after described demodulating unit demodulation;
Verification unit is used for the decoded result of described decoding unit is carried out verification;
Judging unit is used for judging the whether verification by described verification unit of described decoded result;
Estimation unit is used for when described judging unit is judged verification by described verification unit, and as the virtual pilot frequency symbol, use virtual pilot frequency symbol and actual pilot symbol carry out channel estimating with decoded result reconstruct;
The relevant information of wherein said virtual pilot frequency channel comprises one of following content or its combination in any:
Consist of the number of subcarrier of described virtual pilot frequency channel and the power that position, described virtual pilot frequency channel use, the code modulation mode that described virtual pilot frequency channel uses.
9. channel estimating apparatus according to claim 8 is characterized in that, each subcarrier that is used for the transmission of data of described reservation complements each other with each subcarrier that is used for transmitted pilot symbol, wherein adopts equally spaced cross arrangement.
10. each described channel estimating apparatus in 9 according to claim 8 is characterized in that, described virtual pilot frequency channel uses the low code modulation mode of complexity; And/or,
The power that the power that described virtual pilot frequency channel uses uses more than or equal to the actual pilot channel.
11. a channel estimation system is characterized in that,
Described system is used for receiving the virtual pilot frequency channel that distributes, and the larger described virtual pilot frequency channel of terminal priority allocation of signal attenuation; Wherein said virtual pilot frequency channel is made of one group of subcarrier that is used for the transmission of data of reserving; This system specifically comprises:
First receiving device is used for receiving user data and pilot data;
The second receiving system, be used for receiving the data of virtual pilot frequency channel, wherein said the second receiving system is decoded as the virtual pilot frequency symbol with the data demodulates of virtual pilot frequency channel, and wherein said virtual pilot frequency symbol is the symbol after the decoded result by verification is reconstructed; The user terminal of wherein data of virtual pilot frequency channel being made demodulating and decoding is the unallocated user terminal that the virtual pilot frequency channel is arranged,
Wherein, described first receiving device comprises a channel estimating unit, and it carries out channel estimating according to virtual pilot frequency symbol and actual pilot symbol.
12. channel estimation system according to claim 11 is characterized in that, described the second receiving system comprises:
Demodulating unit is used for the data of virtual pilot frequency channel are carried out demodulation;
Decoding unit is used for the decoding data after described demodulating unit demodulation;
Verification unit is used for the decoded result of described decoding unit is carried out verification;
Judging unit is used for judging the whether verification by described verification unit of described decoded result.
13. channel estimation system according to claim 11 is characterized in that, each subcarrier that is used for the transmission of data of described reservation complements each other with each subcarrier that is used for transmitted pilot symbol, wherein adopts equally spaced cross arrangement.
14. channel estimation system according to claim 12 is characterized in that, also comprises:
Acquiring unit is for the relevant information of obtaining described virtual pilot frequency channel from broadcast message;
Receiving element for the relevant information of the described virtual pilot frequency channel that obtains according to described acquiring unit, receives the data of described virtual pilot frequency channel;
The relevant information of the described virtual pilot frequency channel that described demodulation, decoding unit are obtained according to described acquiring unit is carried out described demodulation, decoding;
The relevant information of wherein said virtual pilot frequency channel comprises one of following content or its combination in any:
Consist of the number of subcarrier of described virtual pilot frequency channel and the power that position, described virtual pilot frequency channel use, the code modulation mode that described virtual pilot frequency channel uses.
15. each described channel estimation system in 14 is characterized in that according to claim 11, the code modulation mode that described virtual pilot frequency channel uses is the low code modulation mode of complexity; And/or,
The power that the power that described virtual pilot frequency channel uses uses more than or equal to the actual pilot channel.
16. a signaling method is characterized in that,
Consist of the virtual pilot frequency channel by one group of subcarrier that is used for the transmission of data of reserving;
Give at least one user terminal with described virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation;
Send the data in the described virtual pilot frequency channel.
17. signaling method according to claim 16 is characterized in that,
Each subcarrier that is used for the transmission of data of described reservation complements each other with each subcarrier that is used for transmitted pilot symbol, wherein adopts equally spaced cross arrangement.
18. signaling method according to claim 16 is characterized in that, described virtual pilot frequency channel uses the low code modulation mode of complexity.
19. signaling method according to claim 16 is characterized in that, the power that the power that described virtual pilot frequency channel uses uses more than or equal to the actual pilot channel.
20. signaling method according to claim 16 is characterized in that, the method also comprises, the relevant information of described virtual pilot frequency channel is broadcast to all user terminals by signaling,
The relevant information of wherein said virtual pilot frequency channel comprises one of following content or its combination in any:
Consist of the number of subcarrier of described virtual pilot frequency channel and the power that position, described virtual pilot frequency channel use, the code modulation mode that described virtual pilot frequency channel uses.
21. a sender unit is characterized in that,
The channel Component units is used for one group of subcarrier that is used for the transmission of data of reserving is consisted of the virtual pilot frequency channel;
Channel-assignment unit is given at least one user terminal with described virtual pilot frequency channel allocation, and the larger described virtual pilot frequency channel of user terminal priority allocation of signal attenuation;
Transmitting element is for the data that send described virtual pilot frequency channel.
22. sender unit according to claim 21 is characterized in that,
Each subcarrier that is used for the transmission of data of described reservation complements each other with each subcarrier that is used for transmitted pilot symbol, wherein adopts equally spaced cross arrangement.
23. sender unit according to claim 21 is characterized in that, described virtual pilot frequency channel uses the low code modulation mode of complexity.
24. sender unit according to claim 21 is characterized in that, the power that the power that described virtual pilot frequency channel uses uses more than or equal to the actual pilot channel.
25. sender unit according to claim 21, it is characterized in that, this device also comprises, radio unit, the relevant information of described virtual pilot frequency channel is broadcast to all user terminals by signaling, and the relevant information of wherein said virtual pilot frequency channel comprises one of following content or its combination in any:
Consist of the number of subcarrier of described virtual pilot frequency channel and the power that position, described virtual pilot frequency channel use, the code modulation mode that described virtual pilot frequency channel uses.
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| CN 200710076939 CN101383793B (en) | 2007-09-03 | 2007-09-03 | Method, apparatus and system for signal transmission and channel estimation |
| PCT/CN2008/072177 WO2009030157A1 (en) | 2007-09-03 | 2008-08-27 | Method, device and system for signal transmission and channel estimation |
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| CN102970253B (en) * | 2011-09-01 | 2015-07-15 | 富士通株式会社 | Device and method for channel estimation on basis of demodulation reference signals and receiver |
| US8824527B2 (en) * | 2011-11-15 | 2014-09-02 | Acorn Technologies, Inc. | OFDM receiver with time domain channel estimation |
| CN102404258B (en) * | 2011-11-29 | 2014-07-09 | 华为技术有限公司 | Method, system and mobile terminal for estimating downstream channels |
| CN103067144B (en) * | 2012-12-25 | 2016-03-23 | 电信科学技术研究院 | A kind of iteration receiving method and equipment |
| CN103944841B (en) * | 2013-01-17 | 2017-03-08 | 展讯通信（上海）有限公司 | Channel estimation methods and its device in ofdm system |
| EP2768176B1 (en) * | 2013-01-17 | 2020-07-15 | Spreadtrum Communications (Shanghai) Co., Ltd. | Orthogonal frequency division multiplexing (ofdm) channel estimation to improve the smoothing process |
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| CN105282076B (en) * | 2014-06-12 | 2019-02-26 | 上海数字电视国家工程研究中心有限公司 | The generation method of leading symbol and the generation method of frequency-domain OFDM symbol |
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