CN112398772B - OFDM system receiving demodulation method and OFDM system receiver - Google Patents
OFDM system receiving demodulation method and OFDM system receiver Download PDFInfo
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Abstract
The invention provides an OFDM system receiving demodulation method and an OFDM system receiver, which are characterized by comprising the following steps: receiving service layer information and physical layer signaling to perform coding subframe control; and the decoding subframe control is used for judging the subframe where the current data of the user is located, and outputting a subframe instruction to be decoded for channel estimation, so that the subframe switching of different FFT sizes is continuously and stably carried out without introducing extra error codes and affecting the viewing experience of the user under the condition that the buffer space is not increased when the scene is switched by different subframe sizes.
Description
Technical Field
The present invention relates to an OFDM system reception demodulation technique, and in particular, to an OFDM system reception demodulation method and a channel estimation, synchronization, and equalization technique in a receiver.
Background
ATSC3.0 is a new generation digital broadcast television standard in the united states and is currently undergoing commercial advancement. The system corresponding to the standard is an advanced terrestrial digital broadcast television transmission system based on the OFDM air interface technology. The system adopts a plurality of new technologies in the wireless communication and broadcasting fields, such as LDM hierarchical multiplexing, more advanced LDPC coding, non-uniform constellation mapping and the like. The application of the novel technologies ensures the robustness of the ATSC3.0 system and simultaneously has more efficient spectrum utilization rate and more flexible application scene.
Among a series of new technologies adopted by the ATSC3.0 system, the multi-subframe flexible configuration technology provides great help for expanding the application scene of the ATSC3.0 system.
Future ATSC3.0 system signals are expected to be received by both stationary devices (e.g., televisions) and mobile devices (e.g., car televisions, cell phones, etc.). The multi-subframe flexible configuration technology can set a plurality of subframes with different parameters in one ATSC3.0 physical frame, and the subframes can be configured with different parameters such as FFT size, GI length and the like. Because the size of the FFT corresponds to the interval of the subcarriers, when the OFDM symbol in one subframe has a larger FFT size (such as 32K), the subcarrier interval is smaller, the spectrum utilization rate is higher, and the method is suitable for fixed reception requiring high transmission rate; when the OFDM symbol in one subframe has a smaller FFT size (e.g., 8K), the subcarrier spacing is larger, the spectrum utilization is lower, but the OFDM symbol can resist larger doppler spread, so that the OFDM symbol is suitable for mobile reception requiring high robustness. Therefore, with the multi-subframe flexible configuration technique, in one ATSC3.0 physical frame, a plurality of subframes with different FFT sizes are set in combination, so that the simultaneous existence of fixed reception and mobile reception can be supported with lower signaling overhead. The physical frame structure of the ATSC3.0 system, as well as the flexible configuration of multiple subframes, is shown in fig. 1.
Fig. 1 is a schematic diagram of a configuration of multiple subframes in an ATSC3.0 physical frame structure in the related art. As can be seen from fig. 1, the physical frame contains a preamble symbol, a signaling symbol and a plurality of subframes, e.g. subframe 0 is set to a 32k FFT and subframe n-1 is set to an 8k FFT.
Fig. 2, on the other hand, is a block diagram of a typical OFDM system receiver in the prior art. The receiver of an OFDM system often has a structure as shown in fig. 2.
The receiver of the OFDM system comprises: the device comprises a deviation adjusting module, an FFT conversion module, a channel estimation module, a multipath detection module, a frequency deviation/time deviation estimation module and an equalization module. By the above modules, it can be known that the time domain received signal R is transformed into the frequency domain OFDM received symbol R through FFT. The channel estimation module obtains an estimated value H of the frequency domain channel impulse response by utilizing R, and sends the R and the H to a subsequent equalization module to obtain an estimated value X of a transmitted signal. Meanwhile, the H output by the channel estimation is often applied to a multipath detection module and a frequency deviation and time deviation estimation module, the multipath information output by the multipath detection module is used for filtering the channel estimation module, and the estimation results output by the frequency deviation and time deviation estimation module are used for deviation adjustment of the front end of the receiver.
In an ATSC3.0 system, an ATSC3.0 receiver performs channel estimation due to the scattered distribution characteristic of pilots, comprising the steps of:
step one: performing least square estimation on the pilot frequency position to obtain an initial channel estimation result at the pilot frequency position;
step two: increasing the density of an initial channel estimation value on a current OFDM symbol by using a time domain interpolation method;
step three: and obtaining the channel estimation results of all the subcarriers by frequency domain interpolation by using all the initial channel estimation results on the current OFDM symbol.
In this case, the channel estimation module often needs to buffer a different number of OFDM symbols backwards in order to implement the time domain interpolation described in the second step, depending on the pilot interval in the time domain.
For example, in the ATSC3.0 standard, the time domain pilot spacing is defined as the parameter Dy, and Dy is fixed to a value of 2 at 32K FFT size, whereas Dy may be given a value of 4 or 2 at 8K FFT size. Therefore, to minimize the amount of symbol buffering, the channel estimate typically buffers a different number of symbols back at different FFT sizes. Fig. 3 and 4 are schematic diagrams of channel estimation time domain interpolation in the prior art when the 32K FFT size (dy=2) and the 8K FFT size (dy=4). For example, when 32K FFT size, the channel estimate is buffered backward by 1 OFDM symbol; and when the FFT size is 8K, the channel estimate is buffered 3 OFDM symbols backward. Taking the 32K FFT size as an example, dy=2, the process of channel estimation time domain interpolation is shown in fig. 3, and taking the 8K FFT size as an example, dy=4, the process of channel estimation time domain interpolation is shown in fig. 4. As can be seen from fig. 3, the time-domain interpolation of the channel estimate needs to be delayed by one symbol for the 32K FFT size, and 3 symbols for the 8K FFT size. From fig. 3 and fig. 4, it can be seen that the number of symbol delays of the channel estimation time domain interpolation is different from each other.
When all subframes in the ATSC3.0 physical frame are configured to the same FFT size, the channel estimation module only needs to continuously perform symbol buffering according to the fixed number of buffered symbols, and time domain interpolation. However, in ATSC3.0 physical frames, the technical problem faced becomes more complex when subframes of different FFT sizes are present. Because at the sub-frame boundary, when the FFT size is abrupt, the cadence of the channel estimation output symbols is disturbed due to the different number of backward buffered symbols.
As follows, when subframes of different FFT sizes exist, a subframe of a larger FFT size is assumed, the number of channel estimation delay symbols is n, and a subframe of a smaller FFT size is assumed, the number of channel estimation delay symbols is m. The current schemes for dealing with the switching scenes of subframes with different FFT sizes mainly comprise the following two schemes:
1. scheme one: the subframes with the respective FFT sizes are also according to the respective original delay schemes, so that when a received signal is switched from the subframe with the larger FFT size to the subframe with the smaller FFT size, a channel estimation module outputs m-n symbols later; and when the received signal is switched from a subframe with smaller FFT size to a subframe with larger FFT size, the output of m-n symbols is lost in channel estimation. This has the advantage that the delay of the data to the decoder (time delay) does not have to be significantly dithered without adding additional storage. The disadvantage is that when the received signal is switched from the subframe with smaller FFT size to the subframe with larger FFT size, the missing symbol will fixedly introduce a part of decoding failure of the code block, which seriously affects the user experience.
2. Scheme II: and (3) unifying t=3 (t is the maximum symbol delay number corresponding to the channel estimation when the size of the FFT is 8K). The advantage is that no performance loss occurs, but the delay storage capacity (definition) of the received data (definition) is obviously increased (about 3 times larger than the original), and the time delay of the data reaching the decoder is jittery (symbol delay is fixed, but symbol intervals are different in different FFT sizes).
In the two schemes, one is that the buffer space is not increased, but extra error codes are introduced, so that the watching experience of a user is influenced; the other is that the watching experience of the user is not affected, but the buffer memory space is additionally increased, and the cost of the terminal chip is increased.
Disclosure of Invention
The invention aims to provide an OFDM system receiving demodulation method and an OFDM system receiver, which can continuously and stably switch subframes with different FFT sizes without increasing a buffer space when channel estimation time domain interpolation is carried out, and extra error codes are not introduced, so that the watching experience of a user is not influenced.
In order to achieve the above object, the present invention provides a method for demodulating received signals in an OFDM system, comprising the steps of: receiving service layer information and physical layer signaling to perform coding subframe control; and the decoding subframe control is used for judging the subframe where the current data of the user is located, and outputting a subframe instruction to be decoded for channel estimation.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have a feature that the channel estimation has the following time domain interpolation steps: determining a sub-mode to be entered according to the current coding subframe indication and the FFT size relation of subframes before and after the subframe during switching; respectively carrying out time domain interpolation according to the current sub-mode; and outputting the time domain interpolation result to perform the next processing to obtain a final channel estimation result.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have a feature, wherein determining the sub-mode to be entered according to the current coding subframe indication and the subframe FFT size relationship before and after the subframe during switching includes: when the FFT small subframe is switched to the FFT large subframe and the decoding subframe is indicated as the small subframe, a first decoding subframe control sub-mode is entered; when the FFT small subframe is switched to the FFT large subframe and the decoding subframe is indicated as the large subframe, entering a second decoding subframe control sub-mode; when the FFT big subframe is switched to the FFT small subframe and the decoding subframe is indicated as the big subframe, entering a third decoding subframe control sub-mode; and entering a fourth coding subframe control sub-mode when the FFT large subframe is switched to the FFT small subframe and the coding subframe is indicated as the small subframe.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have a feature in that the first coding subframe control sub-mode includes: in the FFT sizes of subframes before and after the subframes in switching, the number of channel estimation delay symbols of the smaller subframes is m, the number of channel estimation delay symbols of the larger subframes is n, the first m symbols of the larger subframes do not participate in channel estimation time domain interpolation calculation of the last m symbols of the smaller subframes, and the channel estimation module discards the first m-n symbols of the larger subframes when outputting.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have a feature in that the second coding subframe control sub-mode includes: in the FFT subframe size before and after the subframe in switching, the channel estimation delay symbol number of the smaller subframe is m, the channel estimation delay symbol of the larger subframe is n, the first n symbols of the larger subframe do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the smaller subframe, and the channel estimation module discards the last m-n symbols of the smaller subframe when outputting.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have a feature in that the third coding subframe control sub-mode includes: in the FFT subframe size before and after the subframe in switching, the channel estimation delay symbol number of the larger subframe is n, the channel estimation delay symbol of the smaller subframe is m, the first n symbols of the subframe with smaller FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with larger FFT size, and the channel estimation module is used for carrying out multi-delay m-n symbols at the beginning of the smaller subframe in output.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have a feature that the fourth coding subframe control sub-mode includes: in the FFT subframe sizes before and after the subframe in switching, the channel estimation delay symbol number of the larger subframe is n, the channel estimation delay symbol number of the smaller subframe is m, the first n symbols of the subframe with smaller FFT size, and the channel estimation time domain interpolation calculation of the last n symbols of the subframe with larger FFT size are selected to be output or not.
The OFDM system reception demodulation method provided by the present invention may further have a feature in which the subframe boundary symbols before and after the subframe at the time of switching are replaced according to the subframe to be decoded currently.
In the OFDM system receiving demodulation method provided by the present invention, further, the method may further have the feature of further including: and carrying out equalization processing on corresponding symbols according to the output symbol result of the channel estimation module, so that each symbol of the subframe to be decoded is equalized, and the continuity of subsequent decoding is ensured.
In addition, the invention also provides an OFDM system receiver, which is characterized by comprising: the decoding subframe control module is used for judging the subframe where the current data of the user is located, outputting a subframe indication to be decoded and outputting the subframe indication to the channel estimation module.
In the OFDM system receiver provided by the present invention, further, the OFDM system receiver may further have a feature in which a channel estimation module is configured to perform time domain interpolation: determining a sub-mode to be entered according to the current coding subframe indication and the size relation of subframes before and after the subframe during switching; respectively carrying out time domain interpolation according to the current sub-mode; and outputting the time domain interpolation result to perform the next processing to obtain a final channel estimation result.
In the OFDM system receiver provided by the present invention, further, the OFDM system receiver may further have a feature that the OFDM system receiver further includes: the device comprises a deviation adjusting module, an FFT conversion module, a channel estimation module, a multipath detection module, a frequency deviation/time deviation estimation module and an equalization module, wherein the time domain received signal R is known to be converted into a frequency domain OFDM received symbol R through FFT, the channel estimation module obtains an estimated value H of frequency domain channel impulse response by utilizing the R, the R and the H are sent to a subsequent equalization module to obtain an estimated value X of a transmitted signal, the estimated value H of channel estimation output is used for the multipath detection module, the frequency deviation and the time deviation estimation module, multipath information output by the multipath detection module is used for filtering the channel estimation module, and an estimated result output by the frequency deviation and time deviation estimation module is used for deviation adjustment of the front end of a receiver.
Effects and effects of the invention
The OFDM system receiving demodulation method and the OFDM system receiver can be better applied to channel estimation and synchronous equalization technology under the switching scene of subframes with different FFT sizes, for example, as described in the new generation broadcast television standard ATSC3.0 in the United states, and can continuously and stably switch subframes with different FFT sizes without increasing the buffer space, thereby not introducing extra error codes and not affecting the watching experience of users.
Drawings
Fig. 1 is a schematic diagram of a configuration of multiple subframes in an ATSC3.0 physical frame structure in the related art.
Fig. 2 is a block diagram of a typical OFDM system receiver in the prior art.
Fig. 3 is a schematic diagram of a prior art 32K FFT size (dy=2) channel estimation time domain interpolation.
Fig. 4 is a schematic diagram of a prior art 8K FFT size (dy=4) channel estimation time domain interpolation.
Fig. 5 is a block diagram of an OFDM system receiver according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of the control of the channel estimation input/output symbol in the first subframe control sub-mode according to the embodiment of the present invention.
Fig. 7 is a schematic diagram of the control of the channel estimation input/output symbol in the second subframe control sub-mode according to the embodiment of the present invention.
Fig. 8 is a schematic diagram of a channel estimation input/output symbol control in a third subframe control sub-mode according to an embodiment of the present invention. And
Fig. 9 is a schematic diagram of a channel estimation input/output symbol control in a fourth subframe control sub-mode according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
In the ATSC3.0 system, it is possible for the transmitter to transmit two subframes of different FFT sizes within one physical frame, but because the two subframes correspond to different traffic types, only one of the subframes needs to be received at the same time for a certain receiver. By utilizing the characteristics of the receiver, a decoding subframe control module can be added on the basis of the original receiver structure, and the logic control function inside the channel estimation can be enhanced.
Fig. 5 is a block diagram of an OFDM system receiver according to an embodiment of the present invention. As shown in fig. 5. The system is based on fig. 2, except for a deviation adjusting module, an FFT conversion module, a channel estimation module, a multipath detection module, a frequency deviation/time deviation estimation module and an equalization module which are included in a receiver of the OFDM system. The OFDM system receiver of the invention is newly added with a coding subframe control module, takes information obtained from a service layer, namely service layer information (for example, which path of data is watched by a user), and physical layer signaling results, namely physical layer signaling (for example, which subframe is respectively watched by each path of data) as inputs, and inputs the information, namely the service layer information (for example, which subframe is watched by the user) into the coding subframe control module, wherein the coding subframe control module is used for judging which subframe the data watched by the user is positioned, and takes the subframe number as a subframe indication to be decoded and outputs the subframe number to the channel estimation module.
The enhanced channel estimation module, the internal time domain interpolation, according to the output of the decoding subframe control module, the channel estimation has the following processing steps:
step one, the channel estimation module determines the sub-mode to be entered by the processing according to the current coding sub-frame indication and the relation between the front and back of the sub-frames during switching.
The decoding subframe control module can give a subframe indication to be decoded according to the information given by the current service layer (which path of data is watched by a user) and combining a physical layer signaling result (which subframe is respectively in each path of data), and transmits the indication to the channel estimation module.
And step two, the channel estimation module determines a processing branch according to the current coding subframe indication and the relation between the front subframe and the rear subframe during switching. In this embodiment, two subframes of 8K FFT Size and 32K FFT Size are illustrated.
If the current FFT subframe Size is switched from a small subframe to a large subframe and the decoding subframe control module indicates that the FFT Size is a small subframe, for example, if the current FFT Size is switched from 8K FFT Size to 32K FFT Size and a subframe with 8K FFT Size needs to be decoded, the first decoding subframe control mode is entered into branch 1.
If the current FFT subframe Size is switched from a small subframe to a large subframe and the coding subframe control module indicates that the FFT Size is a large subframe, for example, if the current FFT Size is switched from 8K FFT Size to 32K FFT Size and a subframe with 32K FFT Size needs to be decoded, the method enters branch 2, i.e. enters a second coding subframe control sub-mode.
If the current FFT subframe Size is switched from a large subframe to a small subframe and the coding subframe control module indicates that the FFT Size is a large subframe, for example, if the current FFT Size is switched from 32K FFT Size to 8K FFT Size and a subframe with 32K FFT Size needs to be decoded, the third coding subframe control mode is entered, and branch 3 is entered.
If the current FFT subframe Size is switched from a large subframe to a small subframe and the coding subframe control module indicates that the FFT Size is a small subframe, for example, if the current FFT Size is switched from 32K FFT Size to 8K FFT Size and a subframe with 8K FFT Size needs to be decoded, the method enters a branch 4, i.e. enters a fourth coding subframe control sub-mode.
Step three, the time domain interpolation module of the channel estimation processes according to the current processing branch, namely according to the current branch, namely the sub-mode, respectively:
in this embodiment, the larger and smaller subframes of the larger FFT size and the smaller FFT size refer to the larger and smaller subframes before and after switching, and will not be described in detail.
[ Branch 1 ]
The number of channel estimation delay symbols of the subframe with smaller FFT size is set as m, and the number of channel estimation delay symbols of the subframe with larger FFT size is set as n, so as to ensure the continuity of channel estimation results of the subframe with smaller FFT size. The first m symbols of the subframe with larger FFT size do not participate in the channel estimation time domain interpolation computation of the last m symbols of the subframe with smaller FFT size. It can be seen that the channel estimation module discards the first m-n symbols of the subframe with larger FFT size when outputting.
Fig. 6 is a schematic diagram of the control of the channel estimation input/output symbol in the first subframe control sub-mode according to the embodiment of the present invention.
As shown in fig. 6, if the subframe with smaller FFT size is 8K FFT size, the subframe with larger FFT size is 32K FFT size, where the dashed line of the input symbol represents not participating in time domain interpolation.
Since the channel estimation delay symbol of the 8K subframe is m=3, the channel estimation delay symbol of the 32K subframe is n=1, in order to ensure the continuity of the 8K subframe, the 2 nd, 3 rd and 4 th input symbols (corresponding to the first three symbols of the 32K subframe and the first m=3 symbols) do not participate in the time domain interpolation calculation of the channel estimation (i.e. are represented by dotted arrows), the 2 nd, 3 rd and 4 th output symbols (corresponding to the last three symbols of the 8K subframe and the last m=3 symbols) are only used for unidirectional interpolation when performing the time domain interpolation. It can be seen that the channel estimation module discards the first two symbols of the 32K subframe, i.e., m-n=2, when outputting.
[ Branch 2 ]
The number of channel estimation delay symbols of the subframe with smaller FFT size is set as m, and the number of channel estimation delay symbols of the subframe with larger FFT size is set as n, so as to ensure the continuity of channel estimation results of the subframe with larger FFT size. The first n symbols of the subframe with larger FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with smaller FFT size. It can be seen that the channel estimation module discards the last m-n symbols of the subframe with smaller FFT size when outputting.
Fig. 7 is a schematic diagram of the control of the channel estimation input/output symbol in the second subframe control sub-mode according to the embodiment of the present invention.
As shown in fig. 7, if the subframe with smaller FFT size is 8K FFT size, the subframe with larger FFT size is 32K FFT size, where the dashed line of the input symbol represents not participating in time domain interpolation.
Since the channel estimation delay symbol of the 8K subframe is m=3 and the channel estimation delay symbol of the 32K subframe is n=1, the input/output symbol control of the channel estimation is shown in fig. 7 to ensure the continuity of the 32K subframe. The input symbol No. 2 (corresponding to the first symbol of the 32K subframe, the first n=1 symbols) does not participate in the time domain interpolation calculation of the channel estimation (i.e. indicated by the dashed arrow), and the output symbol No. 2 (corresponding to the third last symbol of the 8K subframe) performs unidirectional interpolation only by using the least square result of the previous symbol when performing the time domain interpolation. It can be seen that the channel estimation module discards the last two symbols of the 8K subframe, i.e. the last m-n=2 symbols, when outputting.
[ Branch 3: ' s of
Let n be the number of channel estimation delay symbols of the subframe with larger FFT size and m be the number of channel estimation delay symbols of the subframe with smaller FFT size. To ensure the continuity of channel estimation results for the large FFT size coded subframes. The first n symbols of the subframe with smaller FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with larger FFT size. As can be seen, the channel estimation module, when outputting, outputs m-n symbols at the beginning of the subframe with smaller FFT size.
Fig. 8 is a schematic diagram of a channel estimation input/output symbol control in a third subframe control sub-mode according to an embodiment of the present invention.
As shown in fig. 8, if the subframe with smaller FFT size is 8K FFT size, the subframe with larger FFT size is 32K FFT size, where the dashed line of the input symbol represents not participating in time domain interpolation.
Since the channel estimation delay symbol of the 32K subframe is n= 1,8K subframe and the channel estimation delay symbol of the 32K subframe is m=3, the input/output symbol control of the channel estimation is shown in fig. 8 to ensure the continuity of the 32K subframe. The input symbol No. 3 (corresponding to the first symbol of the 8K subframe, the first n=1 symbols) does not participate in the time domain interpolation calculation of the channel estimation (i.e. indicated by the dashed arrow), the output symbol No. 3 (corresponding to the last symbol of the 32K subframe, the last n=1 symbols) performs unidirectional interpolation only by using the least square result of the previous symbol when performing the time domain interpolation. It can be seen that the channel estimation module, when outputting, delays 2 symbols output more at the beginning of the 8K subframe, i.e. for input symbols 4, 5, there is no corresponding output symbol.
[ Branch 4 ]
The channel estimation delay symbol number of the subframe with larger FFT size is set as n, the channel estimation delay symbol of the subframe with smaller FFT size is set as m, and in order to ensure the continuity of the decoding subframe with smaller FFT size, the channel estimation processing process of the branch 4 is basically the same as that of the branch 3, namely the first n symbols of the subframe with smaller FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with larger FFT size, and the last n symbols of the subframe with larger FFT size can be selectively output or not output.
Wherein the branch 3 and the branch 4 differ only here: the last n symbols of the subframe with the larger FFT size are only interpolated in one direction, and the subframe with the larger FFT size is not a decoded subframe, so that the output may be selected or not (here, the non-dashed line, i.e., the circular breakpoint line, indicates).
Fig. 9 is a schematic diagram of a channel estimation input/output symbol control in a fourth subframe control sub-mode according to an embodiment of the present invention.
As shown in fig. 9, for the branch 4, since the channel estimation delay symbol of the 32K subframe is n= 1,8K subframes and the channel estimation delay symbol of the 32K subframe is m=3, the symbol control of the branch 4 is similar to the branch 3 as a whole, and the input symbol No. 3 (corresponding to the first symbol of the 8K subframe, the first n=1 symbols) does not participate in the time domain interpolation calculation of the channel estimation (i.e., indicated by the dashed arrow). The difference is that, for the 3 rd output symbol (the last symbol of the 32K subframe corresponds to the last n=1 symbol), since it is only subjected to unidirectional interpolation and the 32K subframe is not a decoding subframe, output may be selected or not.
And step four, outputting a time domain interpolation result to perform next processing to obtain a final channel estimation result. The method comprises the steps of multipath detection, and a frequency offset and time offset estimation module performs necessary processing according to an output time domain interpolation result of channel estimation.
In this embodiment, the method may further include step five: and the equalization module performs equalization processing on the corresponding symbols according to the output symbol result of the channel estimation module. And equalizing each symbol of the subframe to be decoded, so as to ensure the continuity of subsequent decoding.
From the description of branches 1 to 4 above, it will be understood that time-domain interpolation may be understood as using the result of the symbol located in the next in the time domain to estimate the position of the space of the symbol located in the previous. The problem with sub-frame switching is to consider how to trade off sub-frame boundary symbols according to the sub-frame currently to be decoded.
Further referring to the block diagram of fig. 5, it can be seen that, in the present invention, a part of the control modules are added with the decoding subframes, and a part of the control modules are added with logic control in the channel estimation time domain interpolation. The second and third steps are implemented by a channel estimation module, and are not implemented by a decoding subframe control module.
Those skilled in the art will recognize that the above description is merely one or more implementations of many embodiments of the invention and is not intended to limit the invention. Any equivalent changes, modifications and equivalents of the above-described embodiments fall within the scope of the claims, as long as they are within the true spirit of the present invention.
Claims (10)
1. An OFDM system reception demodulation method, comprising the steps of:
receiving service layer information and physical layer signaling to perform coding subframe control; and
the decoding subframe control is used for judging the subframe where the current data of the user is located, and outputting a subframe instruction to be decoded for channel estimation;
the channel estimation has the following time domain interpolation steps:
determining a sub-mode to be entered according to the current coding subframe indication and the FFT size relation of subframes before and after the subframe during switching;
respectively carrying out time domain interpolation according to the current sub-mode; and
and outputting the time domain interpolation result to perform the next processing to obtain a final channel estimation result.
2. The OFDM system reception demodulation method of claim 1, comprising:
wherein determining the sub-mode to be entered according to the current coding subframe indication and the subframe FFT size relation before and after the subframe during switching comprises:
when the FFT small subframe is switched to the FFT large subframe and the decoding subframe is indicated as the small subframe, a first decoding subframe control sub-mode is entered;
when the FFT small subframe is switched to the FFT large subframe and the decoding subframe is indicated as the large subframe, entering a second decoding subframe control sub-mode;
when the FFT big subframe is switched to the FFT small subframe and the decoding subframe is indicated as the big subframe, entering a third decoding subframe control sub-mode; and
when the FFT large subframe is switched to the FFT small subframe and the coding subframe is indicated as the small subframe, a fourth coding subframe control sub-mode is entered.
3. The OFDM system reception demodulation method of claim 1, comprising:
wherein the first coding subframe control sub-mode comprises:
in the FFT sizes of the subframes before and after the subframe in switching, the number of channel estimation delay symbols of the smaller subframe is m, the number of channel estimation delay symbols of the larger subframe is n,
the first m symbols of the larger subframe do not participate in the channel estimation time domain interpolation computation of the last m symbols of the smaller subframe,
the channel estimation module discards the first m-n symbols of the larger subframe when outputting.
4. The OFDM system reception demodulation method of claim 1, comprising:
wherein the second coding subframe control sub-mode comprises:
in the FFT subframe size before and after the subframe in switching, the channel estimation delay symbol number of the smaller subframe is m, the channel estimation delay symbol of the larger subframe is n,
the first n symbols of the larger subframe do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the smaller subframe,
the channel estimation module discards the last m-n symbols of the smaller sub-frame when outputting.
5. The OFDM system reception demodulation method of claim 1, comprising:
wherein the third coding subframe control sub-mode comprises:
in the FFT subframe size before and after the subframe in switching, the channel estimation delay symbol number of the larger subframe is n, the channel estimation delay symbol of the smaller subframe is m,
the first n symbols of the subframe with smaller FFT size do not participate in the channel estimation time domain interpolation calculation of the last n symbols of the subframe with larger FFT size,
the channel estimation module delays m-n symbols at the beginning of the smaller subframe when outputting.
6. The OFDM system reception demodulation method of claim 1, comprising:
wherein the fourth coding subframe control sub-mode comprises:
in the FFT subframe size before and after the subframe in switching, the channel estimation delay symbol number of the larger subframe is n, the channel estimation delay symbol of the smaller subframe is m,
and the first n symbols of the subframe with smaller FFT size, and the last n symbols of the subframe with larger FFT size are subjected to channel estimation time domain interpolation calculation, and are selected to be output or not output.
7. The OFDM system reception demodulation method of claim 1, comprising:
and switching the subframe boundary symbols before and after the subframe according to the subframe to be decoded currently.
8. The OFDM system reception demodulation method of claim 1, comprising:
may further comprise: and carrying out equalization processing on corresponding symbols according to the output symbol result of the channel estimation module, so that each symbol of the subframe to be decoded is equalized, and the continuity of subsequent decoding is ensured.
9. An OFDM system receiver, comprising:
a decoding subframe control module, and a channel estimation module,
wherein, the business layer information and the physical layer signaling are input into a coding subframe control module,
the decoding subframe control module is used for judging the subframe where the current data of the user is located, outputting a subframe instruction to be decoded and outputting the subframe instruction to the channel estimation module;
the channel estimation module is used for performing time domain interpolation:
determining a sub-mode to be entered according to the current coding subframe indication and the size relation of subframes before and after the subframe during switching;
respectively carrying out time domain interpolation according to the current sub-mode; and
and outputting the time domain interpolation result to perform the next processing to obtain a final channel estimation result.
10. The OFDM system receiver of claim 9, further comprising:
a deviation adjusting module, an FFT conversion module, a channel estimation module, a multipath detection module, a frequency deviation/time deviation estimation module and an equalization module,
wherein, the time domain received signal R is converted into a frequency domain OFDM received symbol R through FFT,
the channel estimation module obtains an estimated value H of the frequency domain channel impulse response by utilizing R, sends R and H to a subsequent equalization module to obtain an estimated value X of a transmitted signal,
the estimated value H output by the channel estimation is used for a multipath detection module and a frequency deviation and time deviation estimation module, multipath information output by the multipath detection module is used for filtering the channel estimation module, and an estimated result output by the frequency deviation and time deviation estimation module is used for deviation adjustment of the front end of the receiver.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101478338A (en) * | 2008-01-04 | 2009-07-08 | 大唐移动通信设备有限公司 | Multiplex transmission method for public reference signal and special reference signal |
| CN101938620A (en) * | 2010-09-16 | 2011-01-05 | 上海高清数字科技产业有限公司 | Movie-mode video signal processing method and device |
| EP3116136A1 (en) * | 2015-07-09 | 2017-01-11 | STMicroelectronics (Rousset) SAS | Method for estimating a time-invariant transmission channel, and corresponding receiver |
| WO2017155304A1 (en) * | 2016-03-08 | 2017-09-14 | 삼성전자 주식회사 | Transmitter and subframe arrangement method therefor |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101505091B1 (en) * | 2009-05-19 | 2015-03-31 | 삼성전자주식회사 | Apparatus and method for initial synchronization wireless communication system based on ofdm |
| US10291367B2 (en) * | 2015-07-01 | 2019-05-14 | Samsung Electronics Co., Ltd. | Transmitting apparatus and receiving apparatus and controlling method thereof |
| US10038573B2 (en) * | 2016-05-23 | 2018-07-31 | Comtech Systems Inc. | Apparatus and methods for adaptive data rate communication in a forward-scatter radio system |
-
2019
- 2019-08-14 CN CN201910747661.3A patent/CN112398772B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101478338A (en) * | 2008-01-04 | 2009-07-08 | 大唐移动通信设备有限公司 | Multiplex transmission method for public reference signal and special reference signal |
| CN101938620A (en) * | 2010-09-16 | 2011-01-05 | 上海高清数字科技产业有限公司 | Movie-mode video signal processing method and device |
| EP3116136A1 (en) * | 2015-07-09 | 2017-01-11 | STMicroelectronics (Rousset) SAS | Method for estimating a time-invariant transmission channel, and corresponding receiver |
| WO2017155304A1 (en) * | 2016-03-08 | 2017-09-14 | 삼성전자 주식회사 | Transmitter and subframe arrangement method therefor |
Non-Patent Citations (1)
| Title |
|---|
| 美国新一代数字电视ATSC 3.0标准技术体系S32物理层介绍;Luke Fay;《广播与电视技术》;全文 * |
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