CN112422473B - System and method for joint frequency offset estimation strategy - Google Patents

System and method for joint frequency offset estimation strategy Download PDF

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CN112422473B
CN112422473B CN202011241345.8A CN202011241345A CN112422473B CN 112422473 B CN112422473 B CN 112422473B CN 202011241345 A CN202011241345 A CN 202011241345A CN 112422473 B CN112422473 B CN 112422473B
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frequency offset
offset estimation
ssb
trs
dmrs
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CN112422473A (en
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黄静静
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Shanghai Institute of Microwave Technology CETC 50 Research Institute
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38—Demodulator circuits; Receiver circuits
    • H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
    • H04L27/3854—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
    • 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
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H04L27/2659—Coarse or integer frequency offset determination and synchronisation
    • 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
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H04L27/266—Fine or fractional frequency offset determination and synchronisation
    • 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
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/16—Discovering, processing access restriction or access information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/20—Manipulation of established connections
    • H04W76/28—Discontinuous transmission [DTX]; Discontinuous reception [DRX]

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Abstract

The invention provides a system and a method for combining frequency offset estimation strategies, which select different SSB modes for frequency offset estimation in different scenes, meet the requirements of different scenes, improve the precision of frequency offset estimation and the flexibility of the frequency offset estimation strategies, and further improve the performance of a receiver and the throughput rate of a channel. In a connected state scene, for periodic TRS and SSB periodic reference signals, by introducing DMRS reference signals, the situation that the system performance and the throughput rate are reduced due to the fact that no synchronous tracking signal exists for a long time can be effectively avoided. The invention can meet the requirements of different application scenes of 5G NR, and improves the precision of frequency offset estimation and the performance of a receiver; the flexibility of a frequency offset estimation strategy is improved; the situation that the system performance and the throughput rate are reduced due to the fact that no synchronous tracking signal exists for a long time is avoided.

Description

System and method for joint frequency offset estimation strategy
Technical Field
The present invention relates to, and in particular, to a system and method for joint frequency offset estimation strategy.
Background
For a wireless mobile communication system, due to time-varying nature of a wireless channel, doppler shift occurs in a wireless signal during transmission, or frequency deviation occurs between a carrier frequency of a transmitter and a local oscillator of a receiver, which may destroy orthogonality between OFDM systems, and further cause mutual interference between subcarriers, thereby deteriorating system performance. Therefore, a User Equipment (UE) needs to design a targeted frequency offset estimation method for estimating a frequency offset, and perform corresponding correction compensation on the UE to ensure the performance of the UE.
Only periodically configured TRS and SSB signals exist in a 5G NR (New Radio, New air interface) system for synchronous tracking; but TRS and SSB signals 22014c, which are periodically configured, if the configuration period is too large (e.g., 160ms), it will cause a loss of synchronization and degrade receiver performance. Therefore, in order to meet the requirements of different application scenarios, a DMRS (PDSCH) reference signal is introduced, and high-precision frequency offset estimation precision is provided for the UE through joint frequency offset estimation of the TRS and SSB signals, so that the performance of a receiver is improved; in different scenes, the strategy flexibility of frequency offset estimation is further improved through mode selection of the reference signal, and the precision of frequency offset estimation and the performance of a receiver are improved.
Patent document CN1719815A discloses a method and a device for frequency offset estimation and correction, which enables the complexity of a frequency offset estimation algorithm to be low, the complexity of system implementation to be low, the frequency offset estimation precision to be high, and the performance of a frequency offset tracking loop to be improved, thereby achieving the best performance of statistical significance. The frequency offset estimation and correction method and the device thereof set frequency offsets with certain intervals before and after the frequency offset estimation value, respectively use the two frequencies to carry out frequency mixing on pilot frequency symbols and carry out coherent accumulation to obtain energy, and use the deviation between the two energies as the measurement of the residual frequency deviation of the system; the coherent accumulation energy of the pilot frequency symbol is maximized after the frequency deviation correction through a feedback adjustment method, so that the maximum likelihood estimation of the frequency deviation is achieved. The structure and performance of the patent still leaves room for improvement.
Disclosure of Invention
In view of the defects in the prior art, the present invention provides a system and a method for combining frequency offset estimation strategies.
The method for combining the frequency offset estimation strategy provided by the invention comprises the following steps:
step S1: judging whether the current scene is an initial cell search or I _ DRX (Idle DRX and Inactive DRX) scene;
step S2: if the current situation is in an initial cell search or I _ DRX (Idle DRX and Inactive DRX) scene, carrying out frequency offset estimation by using an SSB mode 0;
step S3: judging whether the current scene is in a C _ DRX scene or not, and acquiring C _ DRX scene judgment information;
step S4: according to the C _ DRX scene judgment information, if the current scene is in the C _ DRX scene, respectively carrying out frequency offset estimation by using an SSB mode0 and a TRS;
step S5, judging whether SSB/TRS/additional DMRS (PDSCH) exists in the current time slot, and acquiring judgment information of the current time slot;
step S6: according to the current time slot judgment information, if only an additional DMRS (PDSCH) exists, a mode selection strategy is carried out, and the DMRS in the mode is used for estimating frequency offset;
step S7: according to the current time slot judgment information, if only TRS exists, a mode selection strategy is carried out, and the TRS in the mode is used for estimating frequency offset;
s8, judging information according to the current time slot, if only SSB exists, judging whether the signal-to-noise ratio under the time slot is larger than a threshold value, if so, estimating frequency offset by using an SSB mode1, otherwise, estimating frequency offset by using a single-symbol DMRS (PDSCH);
step S9: if more than one reference signal exists, executing a frequency offset estimation strategy;
step S10: when none of the additional DMRS, TRS, SSB is present, a single symbol DMRS (pdsch) is used to estimate the frequency offset.
Preferably, the step S9 includes:
step S9.1: when only the TRS and the SSB exist at the same time, acquiring the information of the TRS and the SSB existing at the same time;
according to the simultaneous existence information of the TRS and the SSB, when the frequency deviation estimated values of the TRS and the SSB are both in the frequency deviation range of the TRS, selecting the frequency deviation estimated value of the TRS; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the TRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
Preferably, the step S9 includes:
step S9.2: when only the DMRS and the SSB exist at the same time, acquiring the existence information of the DMRS and the SSB at the same time;
according to the information that the DMRS and the SSB exist at the same time, when the frequency offset estimation values of the DMRS and the SSB are both in the frequency offset range of the DMRS, the frequency offset estimation value of the DMRS is selected; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the DMRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
Preferably, the step S9 further includes:
step S9.3: when only TRS and DMRS exist at the same time, both select one of the TRS and the DMRS to carry out frequency offset estimation.
Preferably, the step S9 further includes:
step S9.4: when the additional DMRS, TRS and SSB exist, and the signal-to-noise ratio of the SSB is higher than a threshold value, acquiring further strategy control information;
according to the further strategy control information, when the frequency offset estimation value of the SSB exceeds the range of the frequency offset estimation values of the TRS and the DMRS, the frequency offset estimation value of the SSB is selected;
when the frequency offset estimation values of the DMRS and the SSB exceed the range of the estimation value of the TRS but are both in the range of the frequency offset estimation value of the DMRS, selecting the frequency offset estimation value of the DMRS;
when the frequency offset estimation values of the TRS and the SSB exceed the range of the estimation value of the DMRS but are both in the range of the frequency offset estimation value of the TRS, selecting the frequency offset estimation value of the TRS;
and when the TRS, the SSB and the DMRS are all in the range of the frequency offset estimation value of the minimum RS (TRS/DMRS), selecting the frequency offset estimation value corresponding to the minimum RS (TRS/DMRS).
The system for combining the frequency offset estimation strategy provided by the invention comprises the following components:
module M1: judging whether the current scene is an initial cell search or I _ DRX (Idle DRX and Inactive DRX) scene;
module M2: if the current situation is in an initial cell search or I _ DRX (Idle DRX and Inactive DRX) scene, carrying out frequency offset estimation by using an SSB mode 0;
module M3: judging whether the current scene is in a C _ DRX scene or not, and acquiring C _ DRX scene judgment information;
module M4: according to the C _ DRX scene judgment information, if the current scene is in the C _ DRX scene, respectively carrying out frequency offset estimation by using an SSB mode0 and a TRS;
a module M5, which is used for judging whether the SSB/TRS/additional DMRS (PDSCH) exists in the current time slot and acquiring the judgment information of the current time slot;
module M6: according to the current time slot judgment information, if only an additional DMRS (PDSCH) exists, a mode selection strategy is carried out, and the DMRS in the mode is used for estimating frequency offset;
module M7: according to the current time slot judgment information, if only TRS exists, a mode selection strategy is carried out, and the TRS in the mode is used for estimating frequency offset;
the module M8. judges the information according to the current time slot, if only SSB exists, it judges whether the signal-to-noise ratio in the time slot is greater than the threshold, if yes, the frequency offset is estimated using SSB mode1, otherwise, the frequency offset is estimated using single symbol dmrs (pdsch);
module M9: if more than one reference signal exists, executing a frequency offset estimation strategy;
module M10: when none of the additional DMRS, TRS, SSB is present, a single symbol DMRS (pdsch) is used to estimate the frequency offset.
Preferably, said module M9 comprises:
module M9.1: when only the TRS and the SSB exist at the same time, acquiring the information of the TRS and the SSB existing at the same time;
according to the simultaneous existence information of the TRS and the SSB, when the frequency deviation estimated values of the TRS and the SSB are both in the frequency deviation range of the TRS, selecting the frequency deviation estimated value of the TRS; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the TRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
Preferably, said module M9 comprises:
module M9.2: when only the DMRS and the SSB exist at the same time, acquiring the existence information of the DMRS and the SSB at the same time;
according to the information that the DMRS and the SSB exist at the same time, when the frequency offset estimation values of the DMRS and the SSB are both in the frequency offset range of the DMRS, the frequency offset estimation value of the DMRS is selected; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the DMRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
Preferably, the module M9 further includes:
module M9.3: when only TRS and DMRS exist at the same time, both select one of the TRS and the DMRS to carry out frequency offset estimation.
Module M9.4: when the additional DMRS, TRS and SSB exist, and the signal-to-noise ratio of the SSB is higher than a threshold value, acquiring further strategy control information;
according to the further strategy control information, when the frequency offset estimation value of the SSB exceeds the range of the frequency offset estimation values of the TRS and the DMRS, the frequency offset estimation value of the SSB is selected;
when the frequency offset estimation values of the DMRS and the SSB exceed the range of the estimation value of the TRS but are both in the range of the frequency offset estimation value of the DMRS, selecting the frequency offset estimation value of the DMRS;
when the frequency offset estimation values of the TRS and the SSB exceed the range of the estimation value of the DMRS but are both in the range of the frequency offset estimation value of the TRS, selecting the frequency offset estimation value of the TRS;
and when the TRS, the SSB and the DMRS are all in the range of the frequency offset estimation value of the minimum RS (TRS/DMRS), selecting the frequency offset estimation value corresponding to the minimum RS (TRS/DMRS).
Preferably, the method comprises the following steps: the frequency offset estimation device is used for the terminal;
the described frequency offset estimation apparatus comprises: a first judging unit for judging whether the current scene is in an initial cell search or I _ DRX (Idle DRX and Inactive DRX) scene;
the frequency offset estimation apparatus further comprises: the second judgment unit judges whether the current scene is in a C _ DRX scene or not;
the described frequency offset estimation apparatus further comprises: a third judging unit, which judges whether the SSB/TRS/additional DMRS (PDSCH) exists in the current time slot;
the described frequency offset estimation apparatus further comprises: a first frequency offset estimation unit that estimates a frequency offset using the SSB mode 0;
the described frequency offset estimation apparatus further comprises: a second frequency offset estimation unit, which estimates the frequency offset by using the estimation strategy of SSB/TRS/DMRS;
the described frequency offset estimation apparatus further comprises: a third frequency offset estimation unit that estimates a frequency offset using the DMRS;
the described frequency offset estimation apparatus further comprises: a fourth frequency offset estimation unit that estimates a frequency offset using the TRS;
the described frequency offset estimation apparatus further comprises: a fifth frequency offset estimation unit that estimates a frequency offset using the SSB mode 1;
the described frequency offset estimation apparatus further comprises: a sixth frequency offset estimation unit that estimates a frequency offset using the SSB mode 0;
the described frequency offset estimation apparatus further comprises: a seventh frequency offset estimation unit that estimates a frequency offset using a single symbol dmrs (pdsch);
the described frequency offset estimation apparatus further comprises: the first mode selection unit selects a DMRS frequency offset estimation mode;
the described frequency offset estimation apparatus further comprises: and a second mode selection unit which selects the TRS frequency offset estimation mode.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, different SSB modes are selected for frequency offset estimation in different scenes, so that the requirements of different scenes are met, the precision of frequency offset estimation and the flexibility of a frequency offset estimation strategy are improved, and the performance of a receiver and the throughput rate of a channel are further improved;
2. in a connected state scene, for periodic TRS and SSB periodic reference signals, by introducing DMRS reference signals, the condition that the system performance and the throughput rate are reduced due to the fact that no synchronous tracking signals exist for a long time can be effectively avoided;
3. according to the invention, for the condition that resources of a reference signal such as TRS/DMRS are preempted, by introducing mode selection, frequency offset estimation can be flexibly carried out, and the flexibility of frequency offset estimation and the system performance are improved;
4. for the condition that at least two of SSB/TRS/DMRS signals exist, the selection of the strategy of the invention not only avoids the condition that the TRS and the DMRS reference signal are used for estimating distortion under large frequency offset (for example, frequency offset exceeding the frequency offset range of the TRS and the DMRS), but also can ensure higher estimation precision under small frequency offset.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a flow chart of the joint frequency offset estimation strategy of the present invention.
FIG. 2 is a diagram illustrating a SSB frequency offset estimation mode according to the present invention.
Fig. 3 is a schematic diagram of a frequency offset estimation process according to the present invention.
Fig. 4 is a schematic diagram of frequency offset estimation modes of four DMRS symbols according to the present invention.
Fig. 5 is a schematic diagram of a TRS symbol frequency offset estimation mode according to the present invention.
Fig. 6 is a diagram illustrating comparison of estimated values of frequency offset estimation of different modes of TRS under different SNRs according to the present invention.
FIG. 7 is a diagram illustrating the comparison of the estimated values of the frequency offset estimation of the SSB of the present invention under different SNRs.
Fig. 8 is a schematic diagram illustrating comparison of estimated values of frequency offset estimation of different modes of DMRS under different SNRs according to the present invention.
FIG. 9 is a diagram illustrating comparison of the estimated values of the frequency offset estimation of three reference signals under different SNRs according to the present invention.
FIG. 10 is a schematic diagram of the comparison of the estimated lower values of the SSB and TRS frequency offsets under different SNR when the TRS frequency offset estimation range is exceeded.
Fig. 11 is a schematic structural diagram of a joint frequency offset estimation apparatus 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 invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention can meet the requirements of different application scenes of 5G NR, and improves the precision of frequency offset estimation and the performance of a receiver; the flexibility of a frequency offset estimation strategy is improved; the situation that the system performance and the throughput rate are reduced due to the fact that no synchronous tracking signal exists for a long time is avoided.
Specifically, in one embodiment, a joint frequency offset estimation method, as shown in fig. 1, includes:
s1: judging whether the current scene is an initial cell search or I _ DRX (Idle DRX and Inactive DRX) scene, if so, executing S2, estimating frequency offset by using an SSB mode0 mode, and if not, executing S3.
S2: the frequency offset is estimated based on the SSB mode0, where the SSB frequency offset estimation mode is shown in fig. 2. The specific estimation algorithm flow is shown in fig. 3, and is specifically implemented as follows:
for example, the frequency offset estimation of SSB _ mode0 mode
(1) Time-domain correlation between symbols:
corr(rx，tx，re，0)＝H(rx，tx，re，sym(1))*conj(H(rx，tx，re，sym(0)))
corr(rx，tx，re，1)＝H(rx，tx，re，sym(2))*conj(H(rx，tx，re，sym(1)))
wherein corr (rx, tx, re, 0) indicates that the re subcarrier of the rx-th antenna on the first PBCH symbol in the SSB is related to the re subcarrier of the rx-th antenna on the SSS symbol in the SSB, and corr (rx, tx, re, 1) indicates that the re subcarrier of the rx-th antenna on the SSS symbol in the SSB is related to the re subcarrier of the rx-th antenna on the second PBCH symbol in the SSB. rx denotes a reception antenna, tx denotes an antenna port, and re denotes a subcarrier.
(2) The correlation results are accumulated as:
Figure BDA0002768464990000071
corr represents the phase offset between 3 symbols of the SSB.
(3) Calculating a phase angle of a frequency offset estimate
Figure BDA0002768464990000072
(4) Calculating a frequency offset estimate
Δf＝Ang*Scal
Where Scal is the frequency offset estimation factor of the SSB mode0 mode, and Δ f represents the frequency offset estimate for each reference signal.
S3: and judging whether the current scene is a C _ DRX (connect DRX) scene, if so, executing S4, otherwise, executing S5, and judging whether the SSB/TRS/additional DMRS (PDSCH) exists in the current time slot.
S4: the method comprises the steps of estimating frequency offset based on an SSB mode0 mode and a TRS mode, wherein the method is suitable for a C _ DRX scene, and because the sleep time is long and large frequency offset exists, firstly, estimating the frequency offset by using the SSB mode0 mode, compensating data, and then, estimating residual frequency offset by the TRS mode on the basis of estimating the residual frequency offset, so that the frequency offset estimation precision is improved, and the performance of a receiver is improved.
S5: judging whether SSB/TRS/additional DMRS (PDSCH) exists in the current time slot, if the SSB/TRS/additional DMRS (PDSCH) does not exist in the current time slot, executing S6, and estimating frequency offset by using single-symbol DMRS (PDSCH); if only the DMRS exists, S7, mode selection based on DMRS frequency offset estimation is executed; if only TRS is present, then S8 is executed, mode selection based on TRS frequency offset estimation; if only SSB exists, executing S9, and judging whether the SNR of the current time slot is larger than the threshold value of SSB frequency offset estimation; if there is more than one RS, S10 is performed.
S6: the process estimates a frequency offset using a single-symbol dmrs (pdsch). The specific estimation algorithm is as follows:
(1) performing point-to-point conjugate multiplication on the DMRS time domain sequence extracted by the receiving end and the local DMRS time domain signal to represent y (rx, tx, k), as shown in the following formula:
y(rx，tx，k)＝conj(S(k))*r(rx，tx，k)
wherein, S (k) is a local DMRS time domain signal, and r (rx, tx, k) is a DMRS time domain sequence extracted by a receiving end
(2) Dividing y (rx, tx, k) into front and rear ends, assuming that the number of IFFT points is N, the two ends are respectively:
Figure BDA0002768464990000081
Figure BDA0002768464990000082
the two sequences are respectively added as:
Figure BDA0002768464990000083
Figure BDA0002768464990000084
correlating the two sequences
Figure BDA0002768464990000085
(3) Calculating a frequency offset value
Figure BDA0002768464990000086
Wherein fs is the sampling rate and N/2 is the number of sampling points at intervals
S7: mode selection based on DMRS frequency offset estimation, where mode selection is shown in fig. 4. According to the condition that whether the resource of the current DMRS symbol is preempted or not, if four DMRS symbols exist currently, and if the resource of the current DMRS symbol is not preempted, the four symbols can be used for carrying out frequency offset estimation; if 1 of the DMRS symbols is preempted, frequency offset estimation can be performed based on the remaining three symbols; if there are two DMRS symbols preempted, then frequency offset estimation may be based on the remaining two symbols. After the mode selection is finished, S11 is executed to perform frequency offset estimation based on the DMRS of the mode. With the frequency offset estimates for each mode at different SNRs shown in fig. 8.
S8: mode selection based on TRS frequency offset estimation. With mode selection as shown in figure 5. According to the condition whether the current TRS symbol has the preempted resource, if four TRS symbols exist currently, and if the TRS symbols are not preempted, the four symbols can be used for carrying out frequency offset estimation; if 1 of the TRS symbols is preempted, then frequency offset estimation can be performed based on the remaining three symbols; if there are two TRS symbols to be preempted, frequency offset estimation can be performed based on the remaining two symbols. After the mode selection is finished, S12 is executed to perform frequency offset estimation based on the TRS of the mode. Wherein the frequency offset estimation for each mode at different SNRs is shown in fig. 6.
S9: judging whether the SNR of the current time slot is larger than the threshold value of SSB frequency offset estimation, if so, executing S13 to carry out frequency offset estimation based on SSBmode 1. the mode1 is selected because in the synchronous tracking state in the connection state, the frequency offset range does not need to be too large, the precision requirement on the frequency offset estimation is higher, and the mode1 just meets the requirement. If not, S6 is performed, which estimates a frequency offset using a single-symbol dmrs (pdsch). Wherein the frequency offset estimation for each mode at different SNRs is shown in fig. 7.
S10: frequency offset estimation based on SSB/TRS/DMRS (PDSCH). This step is discussed in several cases:
1. when only TRS and SSB exist at the same time, steps S6, S8, and S12 are performed, and the strategy is as follows: when the frequency deviation estimated values of the TRS and the SSB are both in the frequency deviation range of the TRS, selecting the frequency deviation estimated value of the TRS; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the TRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB. Wherein a comparison of TRS and SSB at different SNRs is shown with reference to fig. 9 and 10. Fig. 9 shows that the TRS frequency offset estimation accuracy is higher than the SSB frequency offset estimation accuracy under the same SNR. Fig. 10 shows that when the frequency offset exceeds the TRS estimation range, the TRS estimated value is the residual frequency offset obtained by subtracting the maximum estimation range from the current frequency offset value, and the SSB estimated value exceeds the TRS estimation range, and the SSB estimated value may be selected.
2. When only DMRS and SSB coexist, steps S6, S7, and S11 are performed, and the strategy is as follows: when the frequency offset estimation values of the DMRS and the SSB are both in the frequency offset range of the DMRS, selecting the frequency offset estimation value of the DMRS; when the frequency offset estimation value of the SSB exceeds the frequency offset range of the DMRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB
3. When only TRS and DMRS coexist, S8 and S12 or S7 and S11 are performed. This is because, as can be seen from fig. 9, the two reference signals have close accuracy, so that one of the two reference signals is selected for frequency offset estimation.
4. When all three signals are present, and the signal-to-noise ratio of the SSB is above the threshold, the selection strategy is as follows:
(1) performing steps S6, S7 and S11, S8 and S12, and selecting the frequency offset estimate of the SSB when the frequency offset estimate of the SSB is out of the range of the frequency offset estimates of the TRS and DMRS.
(2) Performing steps S6, S7 and S11, S8 and S12, and when the frequency offset estimates of the DMRS and SSB are out of the TRS estimate range but are both within the DMRS frequency offset estimate range, selecting the DMRS frequency offset estimate.
(3) Performing steps S6, S7 and S11, S8 and S12, and when the frequency offset estimates of TRS and SSB are out of the DMRS estimate range but are both within the frequency offset estimate range of TRS, selecting the frequency offset estimate of TRS.
(4) Executing steps S6, S7 and S11, S8 and S12, and when the TRS, the SSB and the DMRS are all within the range of the frequency offset estimation value of the minimum RS (TRS/DMRS), selecting the frequency offset estimation value corresponding to the minimum RS (TRS/DMRS).
S11: a flow chart of a specific implementation of the DMRS _ mode-based frequency offset estimation algorithm is shown in fig. 3. The implementation algorithm may be described with reference to S2.
S12: a flowchart of a frequency offset estimation algorithm based on TRS _ mode, which is implemented with reference to fig. 3. The implementation algorithm may be described with reference to S2.
S13: a specific implementation flow chart of the frequency offset estimation algorithm based on the SSB _ mode1 is shown in fig. 3. The implementation algorithm may be described with reference to S2.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (10)

1. A method for joint frequency offset estimation strategy, comprising:
step S1: judging whether the current scene is an initial cell search or an I _ DRX scene, if so, executing a step S2; if not, go to step S3;
step S2: if the current situation is in an initial cell search or I _ DRX scene, using an SSB mode0 to carry out frequency offset estimation;
step S3: judging whether the current scene is in a C _ DRX scene or not, if so, executing a step S4; if not, go to S5;
step S4: if the current situation is in a C _ DRX scene, respectively carrying out frequency offset estimation by using an SSB mode0 and a TRS;
step S5: judging whether the SSB/TRS/additional DMRS exists in the current time slot, if so, executing the step S6;
if only the TRS is present, the step S7 is performed;
if only SSB exists, then step S8 is executed;
if more than two reference signals in the SSB/TRS/additional DMRS exist, executing step S9;
when the additional DMRS, TRS, SSB do not exist, performing step S10;
step S6: carrying out a mode selection strategy, and estimating frequency offset by using the DMRS in the mode;
step S7: performing a mode selection strategy, and estimating frequency offset by using TRS in the mode;
step S8: judging whether the signal-to-noise ratio under the time slot is larger than a threshold value, if so, estimating frequency offset by using an SSB mode1, otherwise, estimating frequency offset by using a single-symbol DMRS;
step S9: executing a selective frequency offset estimation strategy; the selective frequency offset estimation strategy comprises a plurality of frequency offset estimation strategies;
step S10: frequency offset is estimated using a single-symbol DMRS.
2. The method of joint frequency offset estimation strategy according to claim 1, wherein said step S9 includes:
step S9.1: when only the TRS and the SSB exist at the same time, acquiring the information of the TRS and the SSB existing at the same time;
according to the simultaneous existence information of the TRS and the SSB, when the frequency deviation estimated values of the TRS and the SSB are both in the frequency deviation range of the TRS, selecting the frequency deviation estimated value of the TRS; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the TRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
3. The method of joint frequency offset estimation strategy according to claim 1, wherein said step S9 includes:
step S9.2: when only the DMRS and the SSB exist at the same time, acquiring the existence information of the DMRS and the SSB at the same time;
according to the information that the DMRS and the SSB exist at the same time, when the frequency offset estimation values of the DMRS and the SSB are both in the frequency offset range of the DMRS, the frequency offset estimation value of the DMRS is selected; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the DMRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
4. The method of joint frequency offset estimation strategy according to claim 1, wherein said step S9 further comprises:
step S9.3: when only TRS and DMRS exist at the same time, both select one of the TRS and the DMRS to carry out frequency offset estimation.
5. The method of joint frequency offset estimation strategy according to claim 1, wherein said step S9 further comprises:
step S9.4: when the additional DMRS, TRS and SSB exist, and the signal-to-noise ratio of the SSB is higher than a threshold value, acquiring further strategy control information;
according to the further strategy control information, when the frequency offset estimation value of the SSB exceeds the range of the frequency offset estimation values of the TRS and the DMRS, the frequency offset estimation value of the SSB is selected;
when the frequency offset estimation values of the DMRS and the SSB exceed the range of the estimation value of the TRS but are both in the range of the frequency offset estimation value of the DMRS, selecting the frequency offset estimation value of the DMRS;
when the frequency offset estimation values of the TRS and the SSB exceed the range of the estimation value of the DMRS but are both in the range of the frequency offset estimation value of the TRS, selecting the frequency offset estimation value of the TRS;
and when the TRS, the SSB and the DMRS are all in the range of the frequency offset estimation value of the minimum RS, selecting the frequency offset estimation value corresponding to the minimum RS.
6. A system for joint frequency offset estimation strategy, comprising:
module M1: judging whether the current scene is an initial cell search or an I _ DRX scene, if so, executing a module M2; if not, then block M3 is executed;
module M2: if the current situation is in an initial cell search or I _ DRX scene, using an SSB mode0 to carry out frequency offset estimation;
module M3: judging whether the current scene is in a C _ DRX scene, if so, executing a module M4; if not, go to S5;
module M4: if the current situation is in a C _ DRX scene, respectively carrying out frequency offset estimation by using an SSB mode0 and a TRS;
module M5: judging whether the SSB/TRS/additional DMRS exists in the current time slot, and if the SSB/TRS/additional DMRS exists only, executing a module M6;
if only TRS is present, then module M7 is executed;
if only SSB exists, module M8 is executed;
if more than two reference signals in the SSB/TRS/additional DMRS exist, executing a module M9;
when the additional DMRS, TRS, SSB are not present, executing a module M10;
module M6: carrying out a mode selection strategy, and estimating frequency offset by using the DMRS in the mode;
module M7: performing a mode selection strategy, and estimating frequency offset by using TRS in the mode;
module M8: judging whether the signal-to-noise ratio under the time slot is larger than a threshold value, if so, estimating frequency offset by using an SSB mode1, otherwise, estimating frequency offset by using a single-symbol DMRS;
module M9: executing a selective frequency offset estimation strategy; the selective frequency offset estimation strategy comprises a plurality of frequency offset estimation strategies;
module M10: frequency offset is estimated using a single-symbol DMRS.
7. The system of joint frequency offset estimation strategy according to claim 6, wherein said module M9 comprises:
module M9.1: when only the TRS and the SSB exist at the same time, acquiring the information of the TRS and the SSB existing at the same time;
according to the simultaneous existence information of the TRS and the SSB, when the frequency deviation estimated values of the TRS and the SSB are both in the frequency deviation range of the TRS, selecting the frequency deviation estimated value of the TRS; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the TRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
8. The system of joint frequency offset estimation strategy according to claim 7, wherein said module M9 comprises:
module M9.2: when only the DMRS and the SSB exist at the same time, acquiring the existence information of the DMRS and the SSB at the same time;
according to the information that the DMRS and the SSB exist at the same time, when the frequency offset estimation values of the DMRS and the SSB are both in the frequency offset range of the DMRS, the frequency offset estimation value of the DMRS is selected; and when the frequency offset estimation value of the SSB exceeds the frequency offset range of the DMRS and the signal-to-noise ratio is higher at the moment, selecting the frequency offset estimation value of the SSB.
9. The system of joint frequency offset estimation strategy according to claim 1, wherein said module M9 further comprises:
module M9.3: when only TRS and DMRS exist at the same time, both select one of the TRS and the DMRS to carry out frequency offset estimation.
Module M9.4: when the additional DMRS, TRS and SSB exist, and the signal-to-noise ratio of the SSB is higher than a threshold value, acquiring further strategy control information;
according to the further strategy control information, when the frequency offset estimation value of the SSB exceeds the range of the frequency offset estimation values of the TRS and the DMRS, the frequency offset estimation value of the SSB is selected;
when the frequency offset estimation values of the DMRS and the SSB exceed the range of the estimation value of the TRS but are both in the range of the frequency offset estimation value of the DMRS, selecting the frequency offset estimation value of the DMRS;
when the frequency offset estimation values of the TRS and the SSB exceed the range of the estimation value of the DMRS but are both in the range of the frequency offset estimation value of the TRS, selecting the frequency offset estimation value of the TRS;
and when the TRS, the SSB and the DMRS are all in the range of the frequency offset estimation value of the minimum RS, selecting the frequency offset estimation value corresponding to the minimum RS.
10. The system of joint frequency offset estimation strategy according to claim 1, comprising: a frequency offset estimation device;
the described frequency offset estimation apparatus comprises: the first judging unit is used for judging whether the current scene is in an initial cell search or I _ DRX scene;
the frequency offset estimation apparatus further comprises: the second judgment unit judges whether the current scene is in a C _ DRX scene or not;
the described frequency offset estimation apparatus further comprises: the third judging unit judges whether the SSB/TRS/additional DMRS exists in the current time slot or not;
the described frequency offset estimation apparatus further comprises: a first frequency offset estimation unit that estimates a frequency offset using the SSB mode 0;
the described frequency offset estimation apparatus further comprises: a second frequency offset estimation unit, which estimates the frequency offset by using the estimation strategy of SSB/TRS/DMRS;
the described frequency offset estimation apparatus further comprises: a third frequency offset estimation unit that estimates a frequency offset using the DMRS;
the described frequency offset estimation apparatus further comprises: a fourth frequency offset estimation unit that estimates a frequency offset using the TRS;
the described frequency offset estimation apparatus further comprises: a fifth frequency offset estimation unit that estimates a frequency offset using the SSB mode 1;
the described frequency offset estimation apparatus further comprises: a sixth frequency offset estimation unit that estimates a frequency offset using the SSB mode 0;
the described frequency offset estimation apparatus further comprises: a seventh frequency offset estimation unit that estimates a frequency offset using a single symbol DMRS;
the described frequency offset estimation apparatus further comprises: the first mode selection unit selects a DMRS frequency offset estimation mode;
the described frequency offset estimation apparatus further comprises: and a second mode selection unit which selects the TRS frequency offset estimation mode.
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