Non-instantaneous decoding method

Abstract

The present application discloses a non-instantaneous decoding method, which is applied in a wireless communication system. The wireless communication system includes a transmitting end and a corresponding receiving end. The process optimization method for the receiving end to perform the non-instantaneous decoding includes the following steps: after confirming that the current subframe is a non-instantaneous decoding subframe, performing pilot channel estimation on the non-instantaneous decoding subframe, and storing frequency domain data of the current subframe for use; after confirming that the current subframe is a subsequent subframe adjacent to the non-instantaneous decoding subframe, merging the pilot channel estimation of the non-instantaneous decoding subframe and the pilot channel estimation performed on the subsequent subframe on the subsequent subframe and performing channel estimation of data RE (Resource Elements); obtaining a channel estimation on the data RE according to the merged pilot channel estimation, and performing equalization, descrambling and rate matching on the non-instantaneous decoding subframe and the subsequent subframe respectively.

Description

Technical Field

[0001] The present application relates to a wireless communication technology, and in particular to a non-instantaneous decoding method and related circuits used in wireless communication technology. Background Art

[0002] Reducing overhead and improving receiver performance are the constant pursuits of communication systems. Reducing overhead can directly reduce power consumption, while improving receiver performance can reduce the number of retransmissions and indirectly reduce power consumption. This demand is particularly strong in low-power wide area networks that have strict power consumption requirements.

[0003] This application focuses on systems that do not need to output decoding results immediately in the current subframe, making full use of the system's own characteristics to improve the channel estimation performance of some data blocks, thereby achieving performance improvement while reducing processing overhead.

[0004] Some attempts to improve the performance of such systems have been made before. For example, the document "Reduction of NB-IoT system information acquisition time" improves performance through symbol-level coherent merging. Symbol-level merging can improve received data and thus improve channel estimation. However, this approach is limited to the case where the data is the same. If the data on the two subframes is not a simple repetition, symbol-level merging cannot be performed before channel estimation and equalization.

[0005] There are other ideas for optimizing channel estimation. For example, the document "LS reply on NB-IoT SI acquisition delay" mentions that the number of subframes for channel estimation can be increased. However, when the channel is highly time-variant or there is residual frequency offset, the effect of merging subframes with longer intervals together will be greatly reduced.

[0006] Based on these considerations, it is indeed necessary to further propose a better solution for the current non-instantaneous decoding system. Summary of the invention

[0007] The embodiment of the present application provides a non-instantaneous decoding system and method thereof, which can solve the problem that when the data on two subframes are not simply repeated, symbol-level merging cannot be performed before channel estimation and equalization; it can also solve the problem that when the channel time variability is strong or there is residual frequency deviation, the effect of merging subframes with longer intervals together will be affected.

[0008] In order to solve the above technical problems, this application is implemented as follows:

[0009] A non-instantaneous decoding method is provided, which is applied in a wireless communication system. The wireless communication system includes a transmitting end and a corresponding receiving end. The receiving end performs the non-instantaneous decoding method, including the following steps: after confirming that the current subframe is a non-instantaneous decoding subframe, performing pilot channel estimation on the non-instantaneous decoding subframe and storing frequency domain data of the subframe; after confirming that the current subframe is a subsequent subframe adjacent to the non-instantaneous decoding subframe, merging the pilot channel estimation of the non-instantaneous decoding subframe and the pilot channel estimation performed on the subsequent subframe on the subsequent subframe and performing channel estimation of data RE; obtaining a channel estimation on the data RE according to the merged pilot channel estimation, and performing equalization, descrambling and rate matching on the non-instantaneous decoding subframe and the subsequent subframe respectively.

[0010] Therefore, the present application can be applied to scenarios where data is not directly repeated, and is relatively insensitive to channel time variability and residual frequency offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a receiving flow chart (1) of a non-real-time decoding method according to an embodiment of the present application.

[0012] Figure 2 To continue Figure 1 Receiving flow chart of the non-real-time decoding method (II).

[0013] Figure 3 To continue Figure 2 Receiving flow chart of the non-real-time decoding method (III).

[0014] Figure 4 When TBS=208 bits, the performance comparison diagram when using the solution of the present invention and the traditional conventional process is shown.

[0015] Figure 5 When TBS=680 bits, the performance comparison diagram when using the solution of the present invention and the traditional conventional process is shown.

[0016] Figure 6 A schematic diagram of the non-real-time decoding method of the present invention applied to a MIMO-OFDM device. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0018] This application is applicable to non-instantaneous decoding systems, for example, non-instantaneous decoding systems where data is not directly repeated. For example, the additional SIB1 (Additional System Information Block 1) transmission mechanism introduced in the Release 15 version of the Narrow-Band Internet of Things (NB-IoT) system. Because for scenarios where data is directly repeated, symbol-level merging of received data in the time domain or frequency domain is a more concise solution.

[0019] In a network system, there is often a scenario where a data block is divided into several subframes for transmission. Decoding often occurs after the data block is completely received, so not every subframe needs to be decoded. For these subframes that do not need to be decoded, the equalization result does not need to be used when the current subframe is decoded immediately.

[0020] Before introducing the embodiments of the present application, in order to facilitate understanding of the differences between the present application and traditional practices, the general process of the OFDM communication system is mentioned in the document "MIMO-OFDM Wireless Communications with Matlab", and the general sending and receiving processes of NB-IoT are mentioned in the documents "A Tutorial on NB-IOT Physical Layer Design" and "An Efficient Downlink Receiver Design for NB-IoT". Compared with traditional practices, the idea of ​​the present application is to postpone the equalization and subsequent processing of these non-instantaneous decoding subframes to subsequent subframes, so as to use the channel estimation results merged with the channel estimation of subsequent subframes. In addition, the present application is applicable to non-instantaneous decoding systems, such as non-instantaneous decoding scenarios where data is not directly repeated.

[0021] The channel bandwidth in the OFDM communication system consists of multiple resource blocks (RBs), where a plurality of consecutive subcarriers form a resource block. A resource element (RE) is defined as a subcarrier (frequency domain) and an OFDM symbol (time domain).

[0022] Regarding an embodiment of the present application, the present application is not limited to the additional system information module (Additional SIB1), but for ease of understanding, Additional SIB1 is used as an example to illustrate the embodiment of the present application, please refer to Figure 1 shown.

[0023] Specifically, when Additional SIB1 is activated, the repetition is 16 and the period is 2560ms, which means that a complete SIB1 data block contains 16 SIB1 subframes. The data structure of SIB1 data: the time span of one repetition is 160ms, and the legal SIB1 is transmitted on subframe index number 4 every other frame. When the Additional SIB1 mechanism is activated, subframe index number 3 before subframe index number 4 with SIB1-NB also carries SIB1-NB data. In the document "ATutorial on NB-IOT Physical Layer Design" of 3GPP TS 36.211, section 10.2.6 mentions that when receiving Additional SIB1, if it is in StandAlone mode, NRS (Narrowband Reference Signal) exists in subframes #0, #1, #3, #4, and subframe #9 without NSSS. If it is InBand mode, NRS exists in subframes #0, #4, subframe #9 without NSSS, and subframe #3 carrying SIB1. Therefore, it cannot be assumed that there is NRS in the position of #3 that transmits SIB1 with an interval of 1 subframe. Considering that in Additional SIB1, a complete SIB1 data block contains 16 SIB1 subframes, and the complete data block is often not received on #3, and no decoding is required, the present invention considers only performing pilot channel estimation at #3, merging the pilot channel estimation of subframes #3 and #4 on the adjacent #4 and performing data RE channel estimation, and then performing equalization and subsequent operations on the stored frequency domain data on subframe #3, and other operations on subframe #4 itself remain unchanged.

[0024] like Figure 1 As shown, it includes a non-instantaneous decoding method, which is applied in a wireless communication system, the wireless communication system includes a transmitting end and a corresponding receiving end, the non-instantaneous decoding method is to solve the technical problem that if the data on two subframes are not simply repeated in the non-instantaneous decoding scenario, symbol-level merging cannot be performed before channel estimation and equalization. In addition, the non-instantaneous decoding method is relatively insensitive to channel time variation or residual frequency offset by using adjacent subframes as much as possible for merging.

[0025] See also Figure 1, wherein the receiving end performs the non-instantaneous decoding method including the following steps: after confirming that the current subframe is a non-instantaneous decoding subframe, performing pilot channel estimation on the non-instantaneous decoding subframe, and storing the frequency domain data of the subframe for equalization and subsequent related processing of subsequent subframes; after confirming that the current subframe is a subsequent subframe adjacent to the non-instantaneous decoding subframe, merging the pilot channel estimation of the non-instantaneous decoding subframe and the pilot channel estimation performed on the subsequent subframe on the subsequent subframe and performing channel estimation of data RE; obtaining a channel estimation on the data RE according to the merged pilot channel estimation, and performing equalization, descrambling and rate matching on the non-instantaneous decoding subframe and the subsequent subframe respectively.

[0026] Specifically, see Figures 1 to 3 As shown, when the process optimization method of the non-instantaneous decoding system is executed at the receiving end, the non-instantaneous decoding method includes the following steps (for simplicity, the following description is only for subframes #3 and #4 containing SIB1):

[0027] Step S110: first demodulate the Orthogonal frequency-division multiplexing (OFDM) signal.

[0028] Step S120: After confirming whether the current subframe is a non-real-time decoding subframe, it means confirming whether the current subframe is subframe index number 3. If so (subframe index number is 3), frequency domain data is stored for processing in a subsequent subframe (i.e., subframe index number 4) (step S122), and after storage is completed, step S130 is entered. If not (subframe index number is 4), frequency domain data storage is not required, and step S130 is directly entered.

[0029] Step S130: Perform pilot channel estimation (NRS channel Estimation) of the current subframe. If the current subframe is subframe index number 3, store the pilot channel estimation.

[0030] Step S140: Determine whether the current subframe is a subsequent subframe adjacent to the non-real-time decoding subframe (ie, subframe index number 4). If yes, merge the pilot channel estimation performed by subframe index number 3 and subframe index number 4 on subframe index number 4 (step S142).

[0031] In this step, if the current subframe is the subframe index number 3, then the process proceeds to step S140 (step S144); if the current subframe is the subframe index number 4, then the process continues to proceed to the following steps.

[0032] Step S150: Obtain a channel estimate on the data RE according to the combined pilot channel estimate.

[0033] Step S160: using the channel estimation result on the data RE, the frequency domain data on the subframe index number 3 and the frequency domain data on the subframe index number 4 are respectively equalized and descrambled.

[0034] Step S170: writing the equalized and descrambled soft information on subframe index number 3 and subframe index number 4 into a circular buffer corresponding to the interleaved data at the transmitting end, and performing rate matching.

[0035] In this step, it is determined whether the current subframe triggers the decoding condition (step S172), and the condition for triggering decoding includes receiving a complete data block. If yes, the following steps are continued. If no, the processing of the current subframe is terminated (step S176).

[0036] Step S180: deinterleave the soft information in the circular buffer.

[0037] Step S190: Decoding.

[0038] Step S200: Cyclic Redundancy Check (CRC), abbreviated as CRC check.

[0039] For simulation results, please refer to Figure 4 and Figure 5 The TBS (Transport Block Size) configuration under Additional SIB1 is described in Table 16.4.1.5.2-1 of the document "MIMO-OFDM Wireless Communications with Matlab". MIMO (Multiple-Input Multiple-Output) means multiple inputs and multiple outputs. The maximum and minimum TBS are selected for illustration. Figure 4 and Figure 5 The performance comparison between the solution of the present invention and the conventional process is shown when TBS=208bits and TBS=680bits respectively. The simulation conditions are InBand mode, dual antennas, ETU channel, 5Hz Doppler spread, and 50Hz frequency deviation.

[0040] It can be seen that after using the solution of the present invention, the signal to noise ratio (SNR) required to achieve BLER (Block Error Rate) 5% when TBS = 208 bits is about 0.6 dB lower than that of the traditional solution, and the SNR required to achieve BLER 5% when TBS = 680 bits is about 0.4 dB lower than that of the traditional solution. Because the working point of AdditionalSIB1 transmission is low and the transmission subframes with NRS are relatively sparse, the channel estimation of merging one more subframe obtains considerable performance gain.

[0041] like Figure 6 As shown, the non-real-time decoding method of the present invention can be applied to a MIMO-OFDM receiver 600, which includes a plurality of antennas 601, a plurality of cyclic prefix (CP) removal and Fast Fourier Transform (FFT) circuits 602, a channel estimation 603 and a plurality of equalizers 604, a parallel to serial (P / S) circuit 605, a demodulator 606 and a bit stream receiver 607. The non-real-time decoding method of the present invention can be performed by the equalizer 606 in the MIMO-OFDM receiver 600, thereby improving the channel estimation result used inside the equalizer.

[0042] In summary, since only pilot channel estimation is performed on subframe #3, channel estimation of data RE is not performed, and channel estimation of data RE is performed only on subframe index number 4, based on a pair of subframe index number 3 and subframe index number 4, the present application saves one channel estimation operation of data RE compared with the traditional process, and the overall processing overhead is reduced. The present application can be applied to scenarios where data is not directly repeated, and reduces processing overhead while improving performance, and is relatively insensitive to channel time variability and residual frequency offset.

Claims

1. A non-real-time decoding method, applied in a wireless communication system, wherein the wireless communication system comprises a transmitting end and a corresponding receiving end, characterized in that: The receiving end performs the non-instantaneous decoding method, comprising the following steps: After confirming that the current subframe is a non-instantaneous decoding subframe, performing pilot channel estimation on the non-instantaneous decoding subframe; After confirming that the current subframe is a subsequent subframe adjacent to the non-instantaneous decoding subframe, on the subsequent subframe, after combining the pilot channel estimation of the non-instantaneous decoding subframe and the pilot channel estimation performed on the subsequent subframe, a channel estimation of the data RE is performed; A channel estimate on the data RE is obtained according to the combined pilot channel estimate, and equalization, descrambling and rate matching are performed on the non-instantaneous decoding subframe and the subsequent subframe respectively.

2. The non-instantaneous decoding method according to claim 1, wherein: After confirming that the current subframe is a non-real-time decoding subframe, the method further includes: storing data on the frequency domain data RE of the non-real-time decoding subframe for subsequent subframe processing.

3. The non-instantaneous decoding method according to claim 1, wherein: After the receiving end executes the step of estimating the pilot channel for the non-real-time decoding subframe, it is confirmed whether the current subframe is the subsequent subframe; if not, the subsequent steps are interrupted.

4. The non-instantaneous decoding method according to claim 1, wherein: In the step of performing the channel estimation on the data RE at the receiving end, the combined pilot channel estimation is used as the channel estimation on the data RE.

5. The non-instantaneous decoding method according to claim 1, wherein: In the step of performing the rate dematching at the receiving end, the soft information after equalization descrambling on the non-instantaneous decoding subframe and the subsequent subframe is written into a circular buffer corresponding to the interleaved data at the transmitting end.

6. The non-instantaneous decoding method according to claim 5, wherein: After the receiving end performs the de-rate matching step, it is determined whether the current subframe triggers the decoding condition. If so, the subsequent steps are continued.

7. The non-instantaneous decoding method according to claim 6, wherein: When the receiving end determines the condition for triggering decoding of the current subframe, the soft information in the circular buffer is deinterleaved.

8. The non-instantaneous decoding method according to claim 7, wherein: After the receiving end performs the deinterleaving step, the soft information in the circular buffer is decoded.

9. The non-instantaneous decoding method according to claim 8, wherein: After the receiving end executes the decoding step, a cyclic redundancy check is performed on the decoded soft information.

10. The non-instantaneous decoding method according to claim 1, wherein: When the receiving end performs the equalization and subsequent steps, the frequency domain data of the adjacent non-real-time decoding subframes stored previously are processed simultaneously.

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