CN110890940B

CN110890940B - Method and device for decoding MIB carried by PBCH, storage medium and terminal

Info

Publication number: CN110890940B
Application number: CN201911164497.XA
Authority: CN
Inventors: 王琤; 张凯; 杨殷
Original assignee: Spreadtrum Communications Shanghai Co Ltd
Current assignee: Spreadtrum Communications Shanghai Co Ltd
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2022-04-12
Anticipated expiration: 2039-11-25
Also published as: CN110890940A

Abstract

A decoding method and device, storage medium and terminal for MIB carried by PBCH are provided, the method comprises: receiving a PBCH signal and demodulating the PBCH signal to obtain soft bits; storing the soft bits into one or more soft buffers, or performing soft combination on the soft bits and the soft bits in the one or more soft buffers, and storing the soft bits after the soft combination into the one or more soft buffers; decoding soft bits in the soft buffer when at least a part of PBCH signals are received, wherein the decoded data comprises a check part and a content part; verifying the content part by using the verification part; if the verification is successful, performing virtual inspection filtering on the content part, and determining whether the content part passes the virtual inspection filtering; and if the false detection filtering is passed, taking the content part as the MIB. The scheme of the invention can improve the success rate of MIB decoding.

Description

Method and device for decoding MIB carried by PBCH, storage medium and terminal

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for decoding an MIB carried by a PBCH, a storage medium, and a terminal.

Background

In many communication systems, for example, Long Term Evolution (LTE), narrowband Internet of Things (NB-IoT), Internet of Things (Internet of Things, IoT), and a User Equipment (UE) need to continuously receive a Physical Broadcast Channel (PBCH) to obtain basic information of a cell for subsequent communication after acquiring information such as time (timing), frequency (frequency) and the like through processing of a synchronization signal. Successful demodulation of PBCH is crucial.

Specifically, PBCH carries a Master Information Block (MIB). The MIB contains the most basic information of the cell, such as the hyper frame number, the system frame number, and the scheduling information of the system information block SIB 1. The DL-SCH (Downlink Shared Channel) needs to be received and decoded by the Information, and the reading of the subsequent System Information Block (SIB) is completed.

For a communication system with a high Signal-to-Noise Ratio (SNR), taking LTE as an example, the MIB decoding method of PBCH mainly decodes the demodulated soft bits and then performs CRC check on the decoded data, and since the LTE system has a high Signal-to-Noise Ratio and PBCH occupies more resources, the MIB decoding success rate is also high.

However, for a narrowband communication system with low signal-to-noise ratio, for example, in an NB-IoT system, the signal-to-noise ratio may be very low, for example, -12.6dB, and the frequency domain resource occupied by PBCH is also very small, so that multiple PBCH signals need to be received and combined to achieve decoding, but the PBCH signals carrying the same MIB information that can be used for combining are limited by the length of tti (transmission Time interval), which also limits the receiving performance of PBCH. And frequent blind/non-blind decoding is required to obtain MIB information as soon as possible, which may result in a too high PBCH false detection probability. Once the PBCH is falsely detected, the SIB1 continues to be received with the wrong information until the SIB1 demodulation is confirmed to fail, resulting in reduced efficiency, wasted time, and adverse impact on the system.

There is a need for a method for MIB decoding of PBCH, which can improve the receiving performance of PBCH under low snr and reduce the problem of excessive false detection probability caused by frequent blind decoding/non-blind decoding.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method and a device for decoding MIB carried by PBCH, a storage medium and a terminal, which can improve the receiving performance of PBCH under low signal-to-noise ratio and reduce the false detection probability of PBCH, thereby improving the success rate of MIB decoding.

To solve the above technical problem, an embodiment of the present invention provides a method for decoding an MIB carried by a PBCH, including the following steps: receiving a PBCH signal and demodulating the PBCH signal to obtain soft bits; storing the soft bits into one or more soft buffers, or performing soft combination on the soft bits and the soft bits in the one or more soft buffers, and storing the soft bits after the soft combination into the one or more soft buffers; decoding soft bits in the soft buffer when at least a part of PBCH signals are received, wherein the decoded data comprises a check part and a content part; verifying the content part by using the verification part; if the verification is successful, performing virtual inspection filtering on the content part, and determining whether the content part passes the virtual inspection filtering; and if the false detection filtering is passed, taking the content part as the MIB.

Optionally, the method for decoding the MIB carried by the PBCH further includes: and for the received PBCH signals, if the verification fails or the duration of the PBCH signals which do not pass the false detection filtering reaches the preset duration, determining that the MIB decoding fails.

Optionally, the MIB contains dynamic fields, and the real TTI boundary has a correspondence with one or more soft buffers; before soft combining the soft bits with the soft bits in one or more soft buffers, the method for decoding the MIB carried by the PBCH further includes: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the real TTI boundary when the time point of receiving the PBCH signal crosses the real TTI boundary.

Optionally, the MIB includes dynamic fields, and each assumed TTI boundary has a corresponding relationship with one or more soft buffers; before soft combining the soft bits with the soft bits in one or more soft buffers, the method for decoding the MIB carried by the PBCH further includes: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the assumed TTI boundary when the time point of receiving the PBCH signal crosses the assumed TTI boundary.

Optionally, the associated soft bits are changed by the influence of the dynamic field, and the associated soft bits include one or more of: the soft bit corresponding to the check code and the soft bit determined according to the coding memory length of the coder.

Optionally, the dynamic field is selected from one or more of: a hyper frame number related field and a system frame number related field; and/or the encoder for encoding comprises a convolutional encoder.

Optionally, when at least a portion of the PBCH signal is received, decoding the soft bits in the soft buffer includes: and when the times of the received PBCH signals are integral multiples of the preset times, decoding the soft bits in the soft buffer.

Optionally, when at least a portion of the PBCH signal is received, decoding the soft bits in the soft buffer includes: determining a decoding frequency according to the number of times of the received PBCH signals, and decoding the soft bits in the soft buffer by adopting the decoding frequency; wherein the decoding frequency increases with the number of times of receiving PBCH signals, or the decoding frequency remains unchanged with the number of times of receiving PBCH signals.

Optionally, the performing false drop filtering on the content part, and determining whether to pass the false drop filtering includes: determining values of one or more fields in the content part, and determining to pass the false detection filtering when the values of the one or more fields have a preset legal threshold range and all accord with the preset legal threshold range.

Optionally, one or more fields in the content portion are selected from one or more of: scheduling information of a system information block SIB1, the number of cell antennas, and partial information of a cell ID.

Optionally, when the PBCH belongs to an FDD NB-IoT system, the one or more fields are SIB1 scheduling information, the scheduling information is represented by 4 bits, and the preset legal threshold range is 0 to 11.

Optionally, the performing false drop filtering on the content part, and determining whether to pass the false drop filtering includes: determining values of one or more fields in the content portion, and determining to pass the false detection filtering when the values of the one or more fields are equal to a known preset value.

Optionally, one or more fields in the content portion are selected from one or more of: operation mode information, number of cell antennas, and partial information of cell ID.

To solve the foregoing technical problem, an embodiment of the present invention provides a device for decoding an MIB carried by a PBCH, including: a receiving module, adapted to receive the PBCH signal and demodulate the PBCH signal to obtain soft bits; the soft combining module is suitable for storing the soft bits into one or more soft buffers, or performing soft combining on the soft bits and the soft bits in one or more soft buffers, and storing the soft bits after soft combining into one or more soft buffers; a decoding module, adapted to decode soft bits in the soft buffer when at least a portion of the PBCH signal is received, the decoded data including a check portion and a content portion; the verification module is suitable for verifying the content part by adopting the verification part; the virtual inspection filtering module is suitable for carrying out virtual inspection filtering on the content part when the verification is successful and determining whether the content part passes the virtual inspection filtering; and the MIB determining module is suitable for taking the content part as the MIB when filtering is carried out through virtual inspection.

In order to solve the foregoing technical problem, an embodiment of the present invention provides a storage medium, on which computer instructions are stored, and when the computer instructions are executed, the steps of the above method for decoding the MIB carried by the PBCH are executed.

In order to solve the foregoing technical problem, an embodiment of the present invention provides a terminal, including a memory and a processor, where the memory stores computer instructions capable of being executed on the processor, and the processor executes the steps of the above method for decoding a MIB carried by a PBCH when executing the computer instructions.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:

in this embodiment of the present invention, before soft combining the soft bits with the soft bits in one or more soft buffers, whenever a time point of receiving a PBCH signal crosses a true/assumed TTI boundary, the soft bits corresponding to the dynamic field and the associated soft bits are cleared from the soft bits in the one or more soft buffers corresponding to the true/assumed TTI boundary. Compared with the prior art that PBCH signals which can be used for merging and bear the same MIB content are limited by the TTI length, the scheme of the embodiment of the invention enables the PBCH signals to be merged across the TTI boundary, breaks through the limitation that the PBCH signals which can be used for merging are limited by the TTI length, can avoid the condition that the PBCH receiving time point cannot be merged due to the change of dynamic fields in the MIB content when the PBCH receiving time point crosses the TTI boundary, is favorable for improving the receiving performance of the PBCH under the low signal-to-noise ratio, and accordingly improves the success rate of MIB decoding.

Further, in the embodiment of the present invention, when at least a portion of PBCH signals are received and the number of times of the received PBCH signals is an integer multiple of a preset number, the soft bits in the soft buffer are decoded, which helps to balance and reduce the probability of false detection and to obtain MIB information as soon as possible.

Further, in the embodiment of the present invention, when at least a portion of PBCH signals are received, a decoding frequency is determined according to the number of times of the received PBCH signals, and the decoding frequency is adopted to decode the soft bits in the soft buffer; the decoding frequency is increased along with the increase of the number of times of receiving the PBCH signals, or the decoding frequency is kept unchanged along with the increase of the number of times of receiving the PBCH signals, so that the balance between the reduction of the probability of false detection and the obtaining of the MIB information as soon as possible is further facilitated.

Further, in the embodiment of the present invention, when the soft bits in the soft buffer are decoded, and then the content part is checked by using the check part, and then the content part is subjected to the dummy detection filtering according to the known information, and whether the content part passes the dummy detection filtering is determined, the situation that the dummy detection filtering is too high due to frequent blind decoding/non-blind decoding can be effectively improved, which is helpful for improving the success rate of the dummy detection filtering, and reducing the probability of the dummy detection, thereby improving the success rate of the MIB decoding.

Drawings

Fig. 1 is a schematic diagram illustrating a coding and modulation process of a PBCH channel in the prior art;

fig. 2 is a flowchart of a method for decoding MIB carried by PBCH in an embodiment of the present invention;

FIG. 3 is a diagram illustrating an MIB encoding sequence according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating encoded bits that remain unchanged across TTI boundaries in an embodiment of the present invention;

fig. 5 is a flowchart of another method for decoding MIB carried by PBCH in an embodiment of the present invention;

fig. 6 is a schematic structural diagram of an apparatus for decoding MIB carried by PBCH in an embodiment of the present invention.

Detailed Description

As previously mentioned, for communication systems with low signal-to-noise ratio, such as NB-IoT systems, the SNR can be very low, e.g., -12.6dB, requiring MIB information to be obtained as quickly as possible by combining multiple times and performing blind/non-blind decoding frequently.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating a coding and modulation process of a PBCH channel in the prior art.

Specifically, the MIB carried by the PBCH is taken as 34 bits for example, and is encoded into 150 bits after a 16-bit Cyclic Redundancy Check (CRC) code is added, where, for example, the CRC may also be masked according to 1 or 2 transmit antennas, and the encoding mode may be, for example, a Tail-biting convolutional code (TBCC) with a code rate of 1/3.

Then, the method carries out Rate matching (Rate matching) to obtain 1600 bits, further scrambles (Scrambling) the 1600 bit long Scrambling sequence, then changes the Scrambling sequence into 800 symbols by QPSK Modulation (Modulation), and divides (segmentates) the 800 symbols into 8 parts, namely block 0-block 7.

Where one is transmitted every 80ms for every 100 symbols, the copy is repeated 8 times in 80ms, once every 10 ms. It takes 640ms in total to transmit one MIB information. I.e. the TTI of PBCH is 640 ms. By the next 640 milliseconds, one part of the 34 bits is semi-static and the content is not changed, but another part is dynamic and changes, such as the high order bits of the SFN and the low order bits of the H-SFN.

The inventor of the present invention has found through research that in the prior art, the TTI of the PBCH in the NB-IoT/IoT system is 640ms, i.e. the same MIB content is transmitted in 640 ms. In a TTI, the MIB content is repeatedly transmitted for multiple times, and the repeated transmissions are combined at the receiving end, so that the PBCH can be demodulated at a low SNR, but still has a certain failure probability.

Further, since the CRC of PBCH is only 16 bits, and the NB-IoT/IoT operating point SNR can be very low, MIB information needs to be obtained as soon as possible by combining multiple times and performing blind/non-blind decoding frequently, which introduces an excessively high PBCH false detection probability. Once the PBCH is falsely detected, SIB1 continues to be collected with the wrong information until SIB1 demodulation is confirmed to fail. Since the SNR can be very low, the SIB1 can have a long time to confirm the demodulation failure, which wastes much time and adversely affects the system, such as long cell access delay.

In the embodiment of the invention, a PBCH signal is received and demodulated to obtain soft bits; storing the soft bits into one or more soft buffers, or performing soft combination on the soft bits and the soft bits in the one or more soft buffers, and storing the soft bits after the soft combination into the one or more soft buffers; decoding soft bits in the soft buffer when at least a part of PBCH signals are received, wherein the decoded data comprises a check part and a content part; verifying the content part by using the verification part; if the verification is successful, performing virtual inspection filtering on the content part, and determining whether the content part passes the virtual inspection filtering; and if the false detection filtering is passed, taking the content part as the MIB. By adopting the scheme, the soft bits in the soft buffer can be decoded, then the content part is verified by the verifying part, and then the content part is subjected to virtual detection filtering according to the known information when the virtual detection filtering is performed, and whether the content part passes the virtual detection filtering is determined, so that the condition that the probability of the virtual detection is too high due to frequent blind decoding/non-blind decoding can be effectively improved, the success rate of the virtual detection filtering is improved, the probability of the virtual detection is reduced, and the success rate of MIB decoding is improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Referring to fig. 2, fig. 2 is a flowchart of a method for decoding MIB carried by PBCH in an embodiment of the present invention. The method for decoding the MIB carried by the PBCH may include steps S21 to S26:

step S21: receiving a PBCH signal and demodulating the PBCH signal to obtain soft bits;

step S22: storing the soft bits into one or more soft buffers, or performing soft combination on the soft bits and the soft bits in the one or more soft buffers, and storing the soft bits after the soft combination into the one or more soft buffers;

step S23: decoding soft bits in the soft buffer when at least a part of PBCH signals are received, wherein the decoded data comprises a check part and a content part;

step S24: verifying the content part by using the verification part;

step S25: if the verification is successful, performing virtual inspection filtering on the content part, and determining whether the content part passes the virtual inspection filtering;

step S26: and if the false detection filtering is passed, taking the content part as the MIB.

In a specific implementation of step S21, the PBCH signal is demodulated to obtain soft bits, wherein the demodulation may include steps of demodulation, descrambling, de-rate matching, and the like. It should be noted that the PBCH signal may be demodulated to obtain the soft bits each time it is received, or for example, the PBCH signal may be received multiple times, and then IQ combining is performed before demodulation, and the present invention is not limited thereto.

Referring to fig. 3, fig. 3 is a schematic diagram of a MIB coding sequence in the embodiment of the present invention.

Specifically, in one embodiment, the MIB coding order may be: for MIB information block a₀,a₁,...,a_A-1CRC addition (CRC attachment) to obtain c₀,c₁,...,c_K-1Then Channel coding is carried out to obtain

Further performing Rate matching (Rate matching) to obtain e₀,e₁,...,e_E-1. The CRC may be 16 bits in length, and encoded using 1/3 TBCC.

With continued reference to fig. 2, in an implementation of step S22, the Soft bits are stored in one or more Soft buffers, or Soft-combined (Soft-combining) with the Soft bits in the one or more Soft buffers, and the Soft-combined Soft bits are stored in the one or more Soft buffers.

Specifically, the soft bits obtained in step S21 for the first time may be directly stored in one or more soft buffers, or for example, the one or more soft buffers may be cleared before the PBCH signal is received for the first time, and then the soft bits are soft-combined with the soft bits (in this case, 0) in the one or more soft buffers, and the soft-combined soft bits are stored in the one or more soft buffers. The soft bits obtained in step S21 each time may be soft-combined with soft bits in one or more soft buffers, for example, and the soft-combined soft bits may be stored in one or more soft buffers. Further, in some cases or conditions, the soft bits obtained in step S21 may be directly stored in one or more soft buffers, which is not limited by the invention.

It should be noted that, before soft combining the soft bits with the soft bits in one or more soft buffers, a step of clearing some of the soft bits may be further included.

Specifically, the MIB contains a dynamic field, the true TTI boundary has a corresponding relationship with one or more soft buffers, and before soft combining the soft bits with the soft bits in the one or more soft buffers, the method for decoding the MIB carried by the PBCH may further include: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the real TTI boundary when the time point of receiving the PBCH signal crosses the real TTI boundary. Specifically, the MIB contains dynamic fields, each hypothetical TTI boundary having a correspondence with one or more soft buffers; before soft combining the soft bits with the soft bits in one or more soft buffers, the method for decoding the MIB carried by the PBCH further includes: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the assumed TTI boundary when the time point of receiving the PBCH signal crosses the assumed TTI boundary.

It should be noted that before soft combining the soft bits with the soft bits in one or more soft buffers, a step of clearing some of the soft bits whenever the time point of receiving the PBCH signal crosses the true/assumed TTI boundary may be further included, and the specific implementation time of this clearing step is not limited in the present invention, and only needs to be performed before soft combining the soft bits with the soft bits in the soft buffers for the first time after crossing the true/assumed TTI boundary, for example, after receiving the PBCH signal for the last time before the true/assumed TTI boundary and demodulating the soft combining decoding check, or before soft combining after demodulating the PBCH signal for the first time after the true/assumed TTI boundary.

It should be noted that the partial zero clearing is only required to be performed before the first soft combining after the TTI boundary is crossed, but the partial zero clearing is not necessarily performed before the soft combining after the PBCH demodulation is received for the first time after the TTI boundary is crossed, and may also be performed after the PBCH is received for the last time in the last TTI, for example, that is, the operations from step S21 to step S23 are not necessarily limited. Specifically, it is necessary to perform the soft combining before the first soft combining in the next TTI.

Further, the associated soft bits vary as a result of the dynamic field, and the associated soft bits may include one or more of: the soft bit corresponding to the check code and the soft bit determined according to the coding memory length of the coder.

Wherein the check code may include CRC.

Referring to fig. 4, fig. 4 is a schematic diagram of coded bits that remain unchanged across TTI boundaries according to an embodiment of the present invention.

As mentioned above, the TTI of the PBCH in the NB-IoT/IoT system is 640ms, i.e. the TTI is the transmission period of the PBCH, and the MIB content carried by the PBCH in each TTI remains unchanged. The same MIB content is repeatedly transmitted several times in one TTI, and PBCH can be demodulated at low SNR by combining the repeated transmissions at the receiving end.

Since there is a certain probability that PBCH is still not correctly decoded through the combination of one TTI at a low SNR. The invention improves the demodulation performance of PBCH under low SNR by combining across TTI. For example, for simplicity, fig. 4 shows encoded bits (encoded bits) that remain unchanged after crossing TTI boundaries after TBCC encoding with a code rate of 1/3, and soft bits corresponding to the encoded bits can be used for combining across TTIs. Due to rate matching, the locations of these soft bits in the soft buffer, which are determined by the method of rate matching and are predictable, may be scattered.

Further, the dynamic field may be selected from one or more of: a hyper frame number related field and a system frame number related field; and/or the encoder for encoding comprises a convolutional encoder.

In general, the MIB may include any number of fields, each field may carry any type of information and may have any size, and the information in each field may be semi-static or dynamic, and the present invention is not limited thereto.

In the MIB in the embodiment of the present invention, except for the hyper System Frame Number (hyper System Frame Number) related field and the System Frame Number (System Frame Number) related field, other fields are semi-static and substantially unchanged. Due to the characteristics of the convolutional code, a part of coded bits (encoded bits) does not change after crossing the TTI boundary, that is, the part that remains unchanged shown in fig. 4, so that the soft bits corresponding to the part that remains unchanged can be retained after crossing the TTI boundary to continue soft combining.

Specifically, at the UE receiving end, for example, at the time of initial cell access, through cell search, the UE can know where the 80ms boundary is, but does not know the 640ms boundary, that is, the UE does not know the TTI boundary of the PBCH.

Therefore, when the UE starts to receive PBCH at, for example, an 80ms boundary (it should be noted that the UE may select to start receiving at the 80ms boundary, but the UE does not necessarily need to start receiving at the 80ms boundary, and the present invention is not limited thereto), the UE does not know which of 8 80ms included in 640ms is the 80ms, that is, which of block0 to block7 is received, so that the UE needs to go to test every possible TTI and can also understand blind decoding of 8 possible TTI boundaries. Table 1 shows a schematic diagram of 8 hypotheses.

TABLE 1

Specifically, if the PBCH signal received in the first 80ms is referred to as D, the PBCH signal received in the next 80ms may be referred to as D +1, and so on. Since it is difficult to determine which of blocks 0 to 7 is D, the UE may have 8 hypotheses, corresponding to block0 for D, block1 for D, and so on. Correspondingly, the UE needs to have 8 soft buffers for these 8 different hypotheses. Then for hypothesis 1, D is block0, then naturally D +1 is block1, D +2 is block2, and so on, until D +7 is block7, and then D +8 is block0 for the next PBCH TTI, for this hypothesis the TTI boundary between D +7 and D +8 can be considered. Then, for example, the soft bits in the soft buffer corresponding to hypothesis 1 may be partially cleared after the last PBCH signal of D +7 is received and the soft combining decoding check is demodulated, or partially cleared before the soft combining is performed after the first PBCH signal of D +8 is received and demodulated.

Similarly, for example, for the assumption 7, D corresponds to block6, then D +1 is block7, D +2 is block0 for the next PBCH TTI, D +9 is block7, and D +10 is block0 for the next PBCH TTI, then for this assumption, a TTI boundary exists between D +1 and D +2, and a TTI boundary also exists between D +9 and D + 10. That is, for hypothesis 7, the soft bits in the soft buffer corresponding to hypothesis 7 may be partially cleared once at each of the two boundaries.

Further, taking the NB-loT MIB shown in fig. 4 as an example, the first 6 bits are dynamic, if the 6 bits change, the CRC also changes, and since the length of the coding memory in the tail-biting convolutional encoder used in NB-IoT is 6 bits, the first 6 bits will be affected after convolutional coding, and since the code rate is 1/3, the soft bits corresponding to the total (6+6+16) × 3 ═ 84 coded bits need to be cleared, and the soft bits corresponding to the other 66 coded bits can be retained.

More specifically, one MIB information may be transmitted in 640 milliseconds. I.e. the TTI of PBCH is 640 ms. By the next 640 milliseconds, one part of the 34 bits is semi-static and does not change in content, but another part changes dynamically, such as the high order bits of the SFN and the low order bits of the H-SFN, and affects the CRC as well. In addition, because the convolutional codes have coding memory, the 6-bit change affects 6 bits after the codes (for example, NB-IoT, the length of the convolutional code coder memory in NB-IoT is 6), so that only 3 × (50-6-6-16) ═ 66 bits of the 150 bits after the codes are unchanged.

It should be noted that, for initial cell access in NB-IoT, there are more than 8 hypotheses, since the number of base station transmit antennas is also unknown (1 or 2, blind decoding is performed by UE by adding CRC mask), so there are 8 × 2 possibilities, which requires 16 soft buffers, 2 for each possible TTI boundary. PBCH detection at NB-IoT initial access requires blind decoding of TTI boundaries and the number of base station transmit antennas.

In this embodiment of the present invention, before soft combining the soft bits with the soft bits in one or more soft buffers, the MIB decoding method further includes: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the assumed TTI boundary when the time point of receiving the PBCH signal crosses the assumed TTI boundary. By adopting the scheme of the embodiment of the invention, the PBCH signals can be combined across the TTI boundary, the limitation of the length of the TTI on the PBCH signals which can be used for combination is broken through, the condition that combination cannot be carried out due to the change of dynamic fields in MIB contents when the time point for receiving the PBCH crosses the TTI boundary can be avoided, the receiving performance of the PBCH under the low signal-to-noise ratio is improved, and the success rate of MIB decoding is improved.

With continued reference to fig. 2, in an implementation of step S23, upon receiving at least a portion of the PBCH signal, the soft bits in the soft buffer are decoded, and the decoded data includes a parity portion and a content portion. Wherein the check portion may be a CRC.

In a specific implementation manner of the embodiment of the present invention, the step of decoding the soft bits in the soft buffer when at least a part of the PBCH signal is received may include: and when the times of the received PBCH signals are integral multiples of the preset times, decoding the soft bits in the soft buffer.

Specifically, assuming that the UE receives a PBCH signal every 10 ms, the UE may perform demodulation and descrambling on the PBCH signal (the scrambling code used for descrambling may be different for each hypothesis, because the scrambling codes used for different blocks may be different), perform rate de-matching on the PBCH signal to obtain soft bits, then perform soft combining on, for example, 8 groups of soft bits obtained and the existing contents in 8 soft buffers corresponding to 8 hypotheses, and store the soft bits after soft combining into corresponding soft buffers, and then perform viterbi decoding and CRC checking on the soft bits in 8 soft buffers corresponding to 8 hypotheses if the number of times of the received PBCH signal reaches an integer multiple of a preset number of times.

It is noted that the probability of false positive increases almost linearly with the number of decoding checks. Since, for example, NB-IoT systems need to receive PBCH at very low SNR, such as-12.6 dB, and need to perform multiple combining for correct decoding, if PBCH signal is received once, the probability of false detection is too high (for example, in the initial cell access phase, PBCH signal is received once within one TTI, the probability of false detection may be as high as 8 × 2 × 8 × 8/2^16 ^ 0.0156), but there is an opportunity to obtain MIB information in the shortest time. If the decoding is finished after one TTI is finished, the probability of false detection can be reduced (8 x 2/2^16 is 2.44e-4), but more unnecessary time is wasted, the time delay of cell access is prolonged, and the error rate is increased more organically. Therefore, a preset number of times, for example, 4, is set, and each time the number of times of receiving PBCH signals reaches an integer multiple of 4, the false detection probability is reduced by 4 times compared with each decoding. Thus helping to balance the reduction of the probability of false positive and the obtaining of MIB information as quickly as possible.

Further, in another specific implementation manner of the embodiment of the present invention, a decoding frequency may be determined according to the number of times of receiving the PBCH signal, and the decoding frequency is adopted to decode the soft bits in the soft buffer; wherein the decoding frequency increases with the number of times of receiving PBCH signals, or the decoding frequency remains unchanged with the number of times of receiving PBCH signals.

Similarly, determining the decoding frequency according to the number of times of receiving the PBCH signal can further balance the reduction of the probability of false detection and the acquisition of MIB information as soon as possible. As the number of times the PBCH signal is received increases, the frequency of decoding may, for example, remain unchanged, increase, and remain unchanged. Since the likelihood of being able to correctly decode increases as the number of times PBCH is received increases, increasing the decoding frequency by stage further helps to balance the reduction of the probability of false detection and the obtaining of MIB information as soon as possible.

In a specific implementation of step S24, the content part is verified using the verification part.

It should be noted that, an appropriate checking manner may be used to check the content part, for example, CRC check, and in the embodiment of the present invention, a specific checking manner is not limited.

In an implementation of step S25, if the verification is successful, dummy detection filtering is performed on the content part, and it is determined whether the dummy detection filtering is passed.

In a specific implementation manner of the embodiment of the present invention, the step of performing virtual inspection filtering on the content part and determining whether the content part passes the virtual inspection filtering may include: determining values of one or more fields in the content part, and determining to pass the false detection filtering when the values of the one or more fields have a preset legal threshold range and all accord with the preset legal threshold range.

Further, one or more fields in the content portion may be selected from one or more of: scheduling information of a system information block SIB1, the number of cell antennas, and partial information of a cell ID.

That is, in the embodiment of the present invention, whether some fields are legal values or illegal values may be adopted for judgment.

In this embodiment of the present invention, when the PBCH belongs to an FDD NB-IoT system, the one or more fields may be SIB1 scheduling information, the scheduling information may be represented by 4 bits, and the preset legal threshold may be in a range from 0 to 11.

Specifically, taking FDD NB-IoT system as an example, the legal value of 4 bits in schedulinglnfossib 1 indicating SIB1 scheduling information can only be 0 to 11.

It is noted that, for example, NB-IoT systems need to receive PBCH at very low SNR, such as-12.6 dB, need to get MIB information as soon as possible through multiple combining and frequent blind/non-blind decoding, resulting in too high false detection probability. Therefore, the content part is subjected to virtual inspection filtering by utilizing the preset legal threshold range of some fields, the success rate of the virtual inspection filtering is improved, and the virtual inspection probability is reduced.

In another specific implementation manner of the embodiment of the present invention, the step of performing false drop filtering on the content part and determining whether the content part passes the false drop filtering may include: determining values of one or more fields in the content portion, and determining to pass the false detection filtering when the values of the one or more fields are equal to a known preset value.

Further, one or more fields in the content portion may be selected from one or more of: operation Mode information (Operation Mode Info), the number of cell antennas, and partial information of cell ID.

That is, in the embodiment of the present invention, some known fields may be used for judgment.

It should be noted that, for example, the NB-IoT system may need to receive MIB information again in some cases during the non-initial access phase, at this time, the cell information may be in a known state, and includes the number of antennas and SFN information sent by the cell base station, and the TTI boundary of PBCH and the mask of CRC are used as known information, and at this time, no assumption needs to be made, and the UE only needs to use one soft buffer to perform soft combining continuously, and perform decoding check and other operations. However, since the NB-IoT system needs to receive PBCH at a very low SNR, for example, -12.6dB, it needs to perform multiple combining to decode correctly, and to obtain MIB information as soon as possible, it needs to decode frequently, that is, in the case of non-blind decoding, there is also a case of too high false detection probability. Therefore, the content part is subjected to virtual detection filtering by using certain known fields, the success rate of virtual detection filtering is improved, and the probability of virtual detection is reduced.

Further, for example, the NB-IoT system may need to receive the MIB information again in some cases at the non-initial access stage, and some fields in the MIB have prior information, for example, the operation mode of the cell is known, so that the operation mode information (operationmode info) in the MIB information may also be used for the false detection filtering, thereby further improving the success rate of the false detection filtering and reducing the false detection probability.

In the implementation of step S26, if filtering is passed, the content part is taken as the MIB.

In the embodiment of the invention, the soft bits in the soft buffer are decoded, then the content part is checked by the check part, and when the virtual detection filtering is carried out, the content part is subjected to the virtual detection filtering according to the known information, and whether the virtual detection filtering is passed or not is determined, so that the condition that the probability of the virtual detection is overhigh due to frequent blind decoding/non-blind decoding can be effectively improved, the success rate of the virtual detection filtering is improved, the probability of the virtual detection is reduced, and the success rate of MIB decoding is improved.

Referring to fig. 5, fig. 5 is a flowchart of another method for decoding MIB carried by PBCH in an embodiment of the present invention. The other method for decoding the MIB carried by the PBCH may include steps S501 to S514, which are described below.

In step S501, a PBCH signal is received.

In step S502, demodulation is performed to obtain soft bits. Wherein the received PBCH signal is demodulated.

It is noted that in the case where there are multiple hypotheses, the demodulation may be different for different hypotheses, and there may be one or more sets of soft bits. The demodulation may include steps of demodulation, descrambling, de-rate matching, and the like.

In step S503, it is determined whether the PBCH signal crosses the TTI boundary, if so, step S504 is performed, and if not, the soft bits in the soft buffer are cleared, and if not, step S505 is performed.

In step S505, soft combining is performed with the soft bits in the soft buffer. Specifically, the soft bits demodulated in step S502 for the first time may be directly stored in the soft buffer, or for example, the soft buffer is cleared first, then the soft bits and the soft bits (in this case, 0) in the soft buffer are soft-combined, and the soft bits after soft-combining are stored in the soft buffer. The soft bits demodulated in step S502 and the soft bits in the soft buffer may be soft-combined, and the soft-combined soft bits may be stored in the soft buffer.

It should be noted that, in the case that the true TTI boundary is known, the step of clearing part of the soft bits in the soft buffer in step S504 may be: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the real TTI boundary when the time point of receiving the PBCH signal crosses the real TTI boundary. If there is a TTI boundary hypothesis, in step S503, it is necessary to determine whether each TTI boundary hypothesis crosses its corresponding hypothetical TTI boundary, and the step of clearing part of the soft bits in the soft buffer in step S504 may be: and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the assumed TTI boundary when the time point of receiving the PBCH signal crosses the assumed TTI boundary.

In step S506, determining whether the number of times of receiving the PBCH signal is an integer multiple of a preset number of times, and if so, performing the decoding operation of step S507, specifically, decoding the soft bits in the soft buffer; if not, executing step S508 to determine whether the preset end time is reached.

In step S508, it is determined whether a preset termination time is reached, if yes, step S514 is executed, and the MIB fails to be decoded; if the judgment result is no, the procedure returns to step S501, and continues to receive the PBCH signal.

In step S509, a CRC check is performed.

In particular, the content portion may be verified using the verification portion.

In step S510, it is determined whether the CRC check is successful, and if the determination result is yes, step S511 is executed, and a false check filtering operation is performed; if not, executing step S508 to determine whether the preset end time is reached.

In step S512, it is determined whether filtering is passed through the dummy check, if yes, step S513 is executed to obtain MIB information and determine that MIB decoding is successful; if not, executing step S508 to determine whether the preset end time is reached.

In step S514, the MIB fails to decode. Since a certain time period (preset termination time period) has been tried, the MIB decoding can be terminated.

Further, in step S513 and step S514, the soft buffer may be set to be cleared after the MIB decoding is successful or failed.

It should be noted that, in this embodiment, the clearing of part of the soft bits in the soft buffer in step S504 is performed before the soft combining after the PBCH is demodulated for the first time after the TTI boundary is crossed, in fact, this step only needs to be performed before the soft bits obtained by the demodulation and the soft bits in the soft buffer are soft combined for the first time after the TTI boundary is crossed, and the specific performing time is not limited in the present invention. For example, after the last demodulation soft combining decoding check of the PBCH signal received before the TTI boundary is truly/supposedly performed, on the basis of fig. 5, step S503 and step S504 are moved to step S508 to determine that the predetermined termination time has not been reached, that is, when the determination result of determining whether the predetermined termination time has been reached is negative, it is determined whether the next PBCH signal received crosses the TTI boundary, if the determination result is positive, part of the soft bits in the soft buffer are cleared, and then the procedure returns to step S501 to continue receiving the PBCH; if the judgment result is no, the procedure returns to step S501, and continues to receive PBCH.

In the flow shown in fig. 5, taking the case that the NB-IoT system knows the number of antennas transmitted by the base station and does not know the TTI boundary as an example, specifically, the UE receives the PBCH signal, demodulates the received PBCH signal to obtain 8 groups of soft bits, soft-combines the obtained 8 groups of soft bits and the existing contents in the 8 soft buffers corresponding to the 8 hypotheses, respectively stores the soft bits after soft-combining into the corresponding soft buffers, and further performs viterbi decoding, CRC checking, and virtual check filtering on the soft bits in the 8 soft buffers corresponding to the 8 hypotheses. This is repeated until there are soft bits in a soft buffer that have passed the check and passed the dummy filtering, at which point the MIB can be considered decoded. The hypothetical TTI boundary for this soft buffer can be considered to be the true TTI boundary. Or if the decoding of the soft bits in any soft buffer is still not passed through the checksum filtering after the preset termination time is reached, the MIB decoding is considered to be failed, and the MIB decoding is terminated.

In a specific implementation, more details regarding steps S501 to S514 are performed with reference to fig. 1 and the foregoing description, and are not repeated herein.

In this embodiment of the present invention, before soft combining the soft bits with the soft bits in one or more soft buffers, whenever a time point of receiving a PBCH signal crosses a true/assumed TTI boundary, the soft bits corresponding to the dynamic field and the associated soft bits are cleared from the soft bits in the one or more soft buffers corresponding to the true/assumed TTI boundary. Compared with the prior art that PBCH signals which can be used for merging and bear the same MIB content are limited by the TTI length, the scheme of the embodiment of the invention enables the PBCH signals to be merged across the TTI boundary, breaks through the limitation that the PBCH signals which can be used for merging are limited by the TTI length, can avoid the condition that the PBCH receiving time point crosses the TTI boundary and cannot be merged due to the change of dynamic fields in the MIB content, is beneficial to improving the receiving performance of the PBCH under the condition of low signal to noise ratio, and thus improves the success rate of MIB decoding.

Referring to fig. 6, fig. 6 is a schematic structural diagram of an apparatus for decoding MIB carried by PBCH in an embodiment of the present invention. The decoding device for MIB carried by PBCH may include:

a receiving module 61, adapted to receive the PBCH signal and demodulate the PBCH signal to obtain soft bits;

a soft combining module 62, adapted to store the soft bits into one or more soft buffers, or soft combine the soft bits with soft bits in one or more soft buffers, and store the soft bits after soft combining into one or more soft buffers;

a decoding module 63, adapted to decode soft bits in the soft buffer when at least a portion of the PBCH signal is received, where the decoded data includes a check portion and a content portion;

a verification module 64 adapted to verify the content part using the verification part;

a false detection filtering module 65, adapted to perform false detection filtering on the content part when the verification is successful, and determine whether the content part passes the false detection filtering;

a MIB determination module 66 adapted to take the content part as the MIB when filtering by false detection.

For the principle, specific implementation and beneficial effects of the apparatus for decoding the MIB carried by the PBCH, please refer to the description related to the method for decoding the MIB carried by the PBCH shown in the foregoing and fig. 1 to 5, which is not described herein again.

An embodiment of the present invention further provides a storage medium, on which computer instructions are stored, and when the computer instructions are executed, the steps of the method for decoding the MIB carried by the PBCH shown in fig. 1 to 5 are executed. The storage medium may be a computer-readable storage medium, and may include, for example, a non-volatile (non-volatile) or non-transitory (non-transitory) memory, and may further include an optical disc, a mechanical hard disk, a solid state hard disk, and the like.

An embodiment of the present invention further provides a terminal, which includes a memory and a processor, where the memory stores computer instructions capable of being executed on the processor, and the processor executes the steps of the method for decoding the MIB carried by the PBCH shown in fig. 1 to 5 when executing the computer instructions. The terminal includes, but is not limited to, a mobile phone, a computer, a tablet computer and other terminal devices.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for decoding MIB carried by PBCH is characterized by comprising the following steps:

receiving a PBCH signal and demodulating the PBCH signal to obtain soft bits;

storing the soft bits into one or more soft buffers, or performing soft combination on the soft bits and the soft bits in the one or more soft buffers, and storing the soft bits after the soft combination into the one or more soft buffers;

decoding soft bits in the soft buffer when at least a part of PBCH signals are received, wherein the decoded data comprises a check part and a content part;

verifying the content part by using the verification part;

if the verification is successful, performing virtual inspection filtering on the content part, and determining whether the content part passes the virtual inspection filtering;

and if the false detection filtering is passed, taking the content part as the MIB.

2. The method of decoding the MIB carried by a PBCH of claim 1, further comprising:

and for the received PBCH signals, if the verification fails or the duration of the PBCH signals which do not pass the false detection filtering reaches the preset duration, determining that the MIB decoding fails.

3. The method of claim 1, wherein the MIB comprises a dynamic field, wherein the actual TTI boundary corresponds to one or more soft buffers; before soft combining the soft bits with soft bits in one or more soft buffers, further comprising:

and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the real TTI boundary when the time point of receiving the PBCH signal crosses the real TTI boundary.

4. The method of claim 1, wherein the MIB comprises a dynamic field, and each hypothetical TTI boundary corresponds to one or more soft buffers;

before soft combining the soft bits with soft bits in one or more soft buffers, further comprising:

and clearing the soft bits corresponding to the dynamic field and the associated soft bits in each soft bit in the one or more soft buffers corresponding to the assumed TTI boundary when the time point of receiving the PBCH signal crosses the assumed TTI boundary.

5. Method for decoding MIB carried by PBCH according to claim 3 or 4, characterized in that said associated soft bits vary under the influence of said dynamic field and comprise one or more of the following:

the soft bit corresponding to the check code and the soft bit determined according to the coding memory length of the coder.

6. Method for decoding MIB carried by PBCH according to claim 3 or 4,

the dynamic field is selected from one or more of: a hyper frame number related field and a system frame number related field;

and/or the presence of a gas in the gas,

the encoder for encoding includes a convolutional encoder.

7. The method of claim 1, wherein decoding soft bits in the soft buffer upon receiving at least a portion of a PBCH signal comprises:

and when the times of the received PBCH signals are integral multiples of the preset times, decoding the soft bits in the soft buffer.

8. The method of claim 1, wherein decoding soft bits in the soft buffer upon receiving at least a portion of a PBCH signal comprises:

determining a decoding frequency according to the number of times of the received PBCH signals, and decoding the soft bits in the soft buffer by adopting the decoding frequency;

wherein the decoding frequency increases with the number of times of receiving PBCH signals, or the decoding frequency remains unchanged with the number of times of receiving PBCH signals.

9. The method of claim 1, wherein the virtually examining and filtering the content part, and the determining whether to pass virtually examining and filtering comprises:

determining values of one or more fields in the content part, and determining to pass the false detection filtering when the values of the one or more fields have a preset legal threshold range and all accord with the preset legal threshold range.

10. The method of decoding MIB carried by a PBCH of claim 9, wherein one or more fields in the content portion are selected from one or more of:

scheduling information of a system information block SIB1, the number of cell antennas, and partial information of a cell ID.

11. The method of claim 9, wherein the one or more fields are SIB1 scheduling information, the scheduling information is represented by 4 bits, and the predetermined legal threshold is in a range from 0 to 11, when the PBCH belongs to an FDD NB-IoT system.

12. The method of claim 1, wherein the virtually examining and filtering the content part, and the determining whether to pass virtually examining and filtering comprises:

determining values of one or more fields in the content portion, and determining to pass the false detection filtering when the values of the one or more fields are equal to a known preset value.

13. The method of decoding MIB carried by a PBCH of claim 12, wherein one or more fields in the content portion are selected from one or more of:

operation mode information, number of cell antennas, and partial information of cell ID.

14. An apparatus for decoding MIB carried by a PBCH, comprising:

a receiving module, adapted to receive the PBCH signal and demodulate the PBCH signal to obtain soft bits;

the soft combining module is suitable for storing the soft bits into one or more soft buffers, or performing soft combining on the soft bits and the soft bits in one or more soft buffers, and storing the soft bits after soft combining into one or more soft buffers;

a decoding module, adapted to decode soft bits in the soft buffer when at least a portion of the PBCH signal is received, the decoded data including a check portion and a content portion;

the verification module is suitable for verifying the content part by adopting the verification part;

the virtual inspection filtering module is suitable for carrying out virtual inspection filtering on the content part when the verification is successful and determining whether the content part passes the virtual inspection filtering;

and the MIB determining module is suitable for taking the content part as the MIB when filtering is carried out through virtual inspection.

15. A storage medium having stored thereon computer instructions which, when executed, perform the steps of the method of decoding MIB carried by PBCH of any of claims 1 to 13.

16. A terminal comprising a memory and a processor, said memory having stored thereon computer instructions executable on said processor, wherein said processor, when executing said computer instructions, performs the steps of the method of decoding MIB carried by PBCH of any of claims 1 to 13.