System and method for locating all synchronization signal blocks on 5G NR channels

Abstract

Embodiments disclosed herein include systems and methods for locating all synchronization signal blocks on a 5G new radio channel. Such systems and methods may include: measuring downlink signal energy over the bandwidth of the 5G new radio channel to identify a center frequency of a signal broadcast on the 5G new radio channel; processing the signal at the center frequency of the signal to identify a first synchronization signal block and a global OFDM symbol boundary among a plurality of synchronization signal blocks on the wireless radio channel, and using the global OFDM symbol boundary for all grid frequencies of the 5G new radio channel to identify remaining synchronization signal blocks among the plurality of synchronization signal blocks.

Description

Technical Field

[0001] The present invention relates generally to radio frequency (RF) communication hardware. More specifically, the present invention relates to systems and methods for locating all synchronization signal blocks (SSBs) on 5G New Radio (NR) channels. Background Art

[0002] Wireless cellular technology has been expanded to adopt 5G standards that can operate in standalone mode or non-standalone mode, and include the use of 5G NR channels that can have one or more SSBs. In standalone mode, a 5G NR channel can contain only one cell-defined SSB, which is located on a wider global synchronization grid with a corresponding global synchronization channel number (GSCN). For example, for frequency ranges above 24.25GHz (i.e., the FR2 part of the 5G standard), the GSCN grid step size is 17.28MHz. Because there are only a few candidate frequencies to search, the user equipment can feasibly search for cell-defined SSBs at startup, and after the user equipment is connected to the 5G NR channel, the user equipment can receive a radio resource control command to search for other SSBs at different frequencies (which are not necessarily on the global synchronization grid). Other SSBs can be located on any frequency within a certain bandwidth of the 5G NR channel bandwidth on the new radio absolute radio frequency channel number (NR-ARFCN) grid, which is narrower than the global synchronization grid. For example, for the FR2 part of the 5G standard, the NR-ARFCN grid step size is only 60KHz. Therefore, it is feasible to locate other SSBs in standalone mode. In non-standalone mode, after the user equipment is connected to the 4G LTE network, the user equipment can receive SSB frequency information from the radio resource control command, but in non-standalone mode, the SSB does not have to be located on the global synchronization grid. Therefore, it is also feasible to locate SSBs in non-standalone mode.

[0003] In some cases, network monitoring and measurement may require blind search and identification of all SSBs on the 5G NR channel, not just the SSB defined by this one cell, thus requiring the user equipment to search for valid cells on each NR-ARFCN grid frequency. However, the bandwidth of the 5G NR channel is wide. For example, for the FR2 frequency portion of the 5G standard, the minimum channel bandwidth is 100MHz, for the FR2 frequency portion of the 5G standard, the maximum channel bandwidth is 400MHz, and for a subcarrier spacing (SCS) of 120KHz, the bandwidth of the SSB is typically 28.8MHz. These characteristics of the 5G NR channel mean that for the FR2 frequency portion of the 5G standard, one of the SSBs can be located on at least one of the 1186 NR-ARFCN grid frequencies. Therefore, in order to blindly scan and identify all SSBs, the scanning receiver needs to perform a primary synchronization signal (PSS) correlation search on each sampling time offset for each grid frequency candidate, which may be prohibitive in terms of time and cost when multiplied by the large number of frequencies. Summary of the invention

[0004] In view of the above, there is a need for improved systems and methods. According to a first aspect of the present invention, a method is provided, the method comprising: measuring downlink signal energy over a bandwidth of a wireless radio channel to identify a center frequency of a signal broadcast on the wireless radio channel; processing the signal at the center frequency of the signal to identify a first synchronization signal block and a global OFDM symbol boundary for a plurality of synchronization signal blocks for the wireless radio channel; and using the global OFDM symbol boundary for all grid frequencies of the wireless radio channel to identify the remaining synchronization signal blocks in the plurality of synchronization signal blocks. According to an embodiment of the first aspect of the present invention, the method further comprises: calculating a cyclic prefix correlation of the signal at the center frequency of the signal to identify the first synchronization signal block and the global OFDM symbol boundary in the plurality of synchronization signal blocks; and calculating a primary synchronization signal correlation for all the grid frequencies at the global OFDM symbol boundary to identify the remaining synchronization signal blocks in the plurality of synchronization signal blocks. According to an embodiment of the first aspect of the present invention, the method further comprises: performing secondary synchronization signal correlation at a peak of the primary synchronization signal correlation result for all the grid frequencies. Alternatively, the method further includes: performing DM-RS correlation for all the grid frequencies at the global OFDM symbol boundary to identify a channel estimate; and performing MIB decoding and demodulation on the channel estimate. Alternatively, the method further includes: calculating the primary synchronization signal correlation for all the grid frequencies at the global OFDM symbol boundary by the following operations: calculating the primary synchronization signal correlation for all the grid frequencies for the first time at each boundary in the OFDM symbol boundary; and calculating the primary synchronization signal correlation for all the grid frequencies for the second time at each boundary in the OFDM symbol boundary, wherein, for the first time, it is assumed that the global OFDM symbol boundary for all the grid frequencies indicates the first OFDM symbol in the half-subframe of the signal, and wherein, for the second time, it is not assumed that the global OFDM symbol boundary for all the grid frequencies indicates the first OFDM symbol in the half-subframe of the signal.Alternatively, the method further comprises: calculating the cyclic prefix correlation of the signal at the center frequency of the signal by: calculating the cyclic prefix correlation of the signal for the first time at the center frequency of the signal; calculating the cyclic prefix correlation of the signal for the second time at the center frequency of the signal; and selecting the result of the cyclic prefix correlation with the highest correlation value for identifying the first synchronization signal block and the global OFDM symbol boundary among the multiple synchronization signal blocks, wherein for the first time, it is assumed that the subcarrier spacing of the signal is a first value, and wherein, for the second time, it is assumed that the subcarrier spacing of the signal is a second value different from the first value. Alternatively, the method further comprises: calculating the cyclic prefix correlation of the signal as a mobile correlation at the center frequency of the signal. Alternatively, the method further comprises: identifying the maximum square peak output value according to the cyclic prefix correlation to identify the global OFDM symbol boundary. According to another embodiment of the first aspect of the present invention, wherein the wireless radio channel comprises a 5G radio channel. According to another embodiment of the first aspect of the present invention, the method further comprises: identifying the frequency edge of the signal by measuring the downlink signal energy. According to a second aspect of the present invention, a system is provided, comprising: a radio frequency transceiver; and a programmable processor, wherein the radio frequency transceiver receives a signal broadcast on a wireless radio channel, and wherein the programmable processor performs the following operations: measuring downlink signal energy over the bandwidth of the wireless radio channel to identify the center frequency of the signal; processing the signal at the center frequency of the signal to identify the first synchronization signal block and the global OFDM symbol boundary of a plurality of synchronization signal blocks for the wireless radio channel; and using the global OFDM symbol boundary for all grid frequencies of the wireless radio channel to identify the remaining synchronization signal blocks in the plurality of synchronization signal blocks. According to an embodiment of the second aspect of the present invention, wherein the programmable processor performs the following operations: calculating a cyclic prefix correlation of the signal at the center frequency of the signal to identify the first synchronization signal block and the global OFDM symbol boundary of the plurality of synchronization signal blocks; and calculating a primary synchronization signal correlation for all the grid frequencies at the global OFDM symbol boundary to identify the remaining synchronization signal blocks in the plurality of synchronization signal blocks. In this embodiment, the programmable processor performs secondary synchronization signal correlation at the peak of the primary synchronization signal correlation result for all the grid frequencies. Alternatively, the programmable processor performs DM-RS correlation for all of the grid frequencies at the global OFDM symbol boundary to identify a channel estimate, and wherein the programmable processor performs MIB decoding and demodulation on the channel estimate.Alternatively, the programmable processor calculates the primary synchronization signal correlation for all the grid frequencies at the global OFDM symbol boundary by: calculating the primary synchronization signal correlation for a first time at each of the OFDM symbol boundaries for all the grid frequencies; and calculating the primary synchronization signal correlation for a second time at each of the OFDM symbol boundaries for all the grid frequencies, wherein, for the first time, it is assumed that the global OFDM symbol boundary for all the grid frequencies indicates the first OFDM symbol in the half-subframe of the signal, and wherein, for the second time, it is not assumed that the global OFDM symbol boundary for all the grid frequencies indicates the first OFDM symbol in the half-subframe of the signal. Alternatively, wherein the programmable processor calculates the cyclic prefix correlation of the signal at the center frequency of the signal by: calculating the cyclic prefix correlation of the signal for the first time at the center frequency of the signal; calculating the cyclic prefix correlation of the signal for the second time at the center frequency of the signal; and selecting the result of the cyclic prefix correlation with the highest correlation value for identifying the first synchronization signal block and the global OFDM symbol boundary among the plurality of synchronization signal blocks, wherein for the first time, the subcarrier spacing of the signal is assumed to be a first value, and wherein for the second time, the subcarrier spacing of the signal is assumed to be a second value different from the first value. Alternatively, wherein the programmable processor calculates the cyclic prefix correlation of the signal as a mobile correlation at the center frequency of the signal. Alternatively, wherein the programmable processor identifies the maximum square peak output value based on the cyclic prefix correlation to identify the global OFDM symbol boundary. According to another embodiment of the second aspect of the present invention, wherein the wireless radio channel comprises a 5G radio channel. According to another embodiment of the second aspect of the present invention, wherein the programmable processor identifies the frequency edge of the signal by measuring the downlink signal energy. According to a third aspect of the present invention, a method is provided, comprising: measuring downlink signal energy over a bandwidth of an LTE radio band to identify a center frequency of a signal broadcast on the LTE radio band; calculating a cyclic prefix correlation of the signal at the center frequency of the signal to identify the global OFDM symbol boundary of the LTE radio band; and calculating a master synchronization signal correlation at the global OFDM symbol boundary for all grid frequencies of the LTE radio band to identify a valid LTE channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a simplified diagram of OFDM symbol alignment at different frequencies as known in the art;

[0006] Figure 2 is a simplified diagram of using CP-OFDM on a 5G NR channel in downlink transmission as known in the art;

[0007] Figure 3 is a block diagram of a system according to the disclosed embodiments;

[0008] Figure 4 is a flow chart of a method according to the disclosed embodiments; and

[0009] Figure 5 is a flow chart of a method according to the disclosed embodiments. DETAILED DESCRIPTION

[0010] While the present invention has embodiments in many different forms, specific embodiments thereof are shown in the drawings and will be described in detail herein to understand that the disclosure should be considered as illustrative of the principles of the invention. The invention is not intended to be limited to the specific illustrated embodiments.

[0011] Embodiments disclosed herein may include systems and methods for locating all SSBs on a 5G NR channel. In particular, Figure 1 As can be seen in, it is known that 5G NR channels use orthogonal frequency division multiplexing (OFDM) symbols that are synchronized in time for different frequencies and different SCS sizes. The systems and methods described herein can identify global OFDM symbol boundaries for all 5G NR channels, and then apply the global OFDM symbol boundaries to all grid frequencies of the 5G NR channels to identify all SSBs.

[0012] For example, the systems and methods described herein may include: measuring downlink signal energy over the bandwidth of a 5G NR channel to identify a center frequency of a signal broadcast on the 5G NR channel. The systems and methods described herein may then include: processing the signal at the center frequency of the signal to identify the first of the SSBs and the global OFDM symbol boundary in the SSBs on the 5G NR channel; and using the global OFDM symbol boundary for all grid frequencies of the 5G NR channel to identify the remaining SSBs in the SSBs.

[0013] In some embodiments, measuring the downlink signal energy may further include identifying the frequency edges of the signal, and in these embodiments, the systems and methods described herein may identify the power and bandwidth of the signal by using a slope algorithm to identify the center frequency of the signal and the frequency edges of the signal.

[0014] In some embodiments, the 5G NR channel may be located near the LTE channel, and in these embodiments, measuring the downlink signal energy may include locking to the LTE channel instead of the 5G NR channel. However, because the LTE channel is synchronized with the 5G NR channel in time, the global OFDM symbol boundaries of the LTE channel and the 5G NR channel are aligned. Therefore, when the systems and methods described herein lock to the LTE channel, the systems and methods described herein also lock to the 5G NR channel.

[0015] In some embodiments, the systems and methods described herein may include calculating a cyclic prefix (CP) correlation of the signal at the center frequency of the signal to identify the first SSB in the SSB and the global OFDM symbol boundary. In particular, Figure 2 As can be seen in the figure, it is known that the 5G NR channel uses CP-OFDM in downlink transmission, which has a CP length T of the last part of the current OFDM symbol of length Tμ. cp Make a copy and set the CP length to T cp Inserted in front of the current OFDM symbol. The systems and methods described herein can use this repetition of the CP length to perform CP correlation. For example, when the sampled signal sequence is s(i), i=0, 1...M, the OFDM symbol length is N samples, and the CP length is CP, for offset i, Equation 1 can be used to calculate the CP correlation.

[0016] Equation 1:

[0017] In some embodiments, the CP correlation of the signal can be calculated as a moving correlation at the center frequency of the signal. For example, when the CP correlation is calculated for the next sampling time offset, the oldest term can be removed from the summation and the new term can be added. In some embodiments, the result of the CP correlation can be a complex number, which can be squared to identify energy values ​​for comparison. In these embodiments, the OFDM symbol start timing can be found by the maximum squared CP correlation peak, and this OFDM symbol boundary can then be applied to all grid frequencies of the 5G NR channel.

[0018] In some embodiments, downlink transmissions may include both data transmissions and synchronous transmissions (e.g., SSB), and in these embodiments, SSB may use a different SCS than data transmissions. For example, in the FR2 frequency portion of the 5G standard, data transmissions may use an SCS of 60 KHz, but SSB may use an SCS of 120 KHz. This larger SCS may provide greater resistance to frequency drift introduced by the oscillator at mmWave frequencies. In particular, as Figure 1As can be seen in the CP length of the first OFDM symbol in a 0.5ms long half-subframe can be longer than the CP length of other OFDM symbols. This difference in length is designed to align half-subframes for SCSs of different sizes. For example, Table 1 identifies the CP lengths of all OFDM symbols when the OFDM sampling length is 512 samples.

[0019] Table 1. CP lengths of different parameter sets for normal CP

[0020] SCS(KHz) CP length of the first OPDM symbol CP length of the remaining OFDM symbols 15 40 36 30 44 36 60 52 36 120 68 36 240 100 36

[0021] 5G NR channels are designed to have flexible slot formats that are configured to be downlink, uplink, or flexible, but the first OFDM symbol is always downlink or flexible, while other OFDM symbols can be any of downlink, uplink, or flexible. Therefore, the first OFDM symbol has a greater chance of receiving a downlink transmission than other OFDM symbols, which, together with the longer CP length, makes it more desirable to correlate with the CP length of the first OFDM symbol (if any). However, there may not be a CP length for the first OFDM symbol, and in this case, the CP correlation of the signal can be calculated twice at the center frequency of the signal: once assuming a first SCS (e.g., 60KHz), and another time assuming a different second SCS (e.g., 120KHz). The systems and methods described herein can then select the result with the highest correlation value from two such calculations for identifying the first SSB in the SSB and the global OFDM symbol boundary.

[0022] In some embodiments, after identifying a global OFDM symbol boundary, the systems and methods described herein may include calculating PSS correlations for all grid frequencies at the global OFDM symbol boundary to identify the remaining SSBs in the SSB. Advantageously, because PSS correlations do not need to be performed for all grid frequencies at each sampling time offset, the processing time of the systems and methods described herein is significantly reduced compared to known systems and methods. Alternatively, PSS correlations may be limited to global OFDM symbol boundaries.

[0023] For example, in known systems and methods (where PSS correlation is performed at each sampling time offset, for each NR-ARFCN grid frequency, an OFDM symbol length of 512 samples, and a CP length of 36 samples), the PSS correlation needs to be repeated for all 548 possible sampling time offsets. In the presence of a large number of NR-ARFCN grid frequencies, the total processing throughput is very high, which results in a low scanning speed. However, in the systems and methods described herein (where PSS correlation is calculated only at the identified global OFDM symbol boundaries), signal processing can theoretically be performed only once, while known systems and methods need to perform it 548 times, resulting in a total processing time saving of 548:1.

[0024] In embodiments where the CP length of the first OFDM symbol in each half-subframe is longer than the CP length of other OFDM symbols, the CP correlation can only identify the global OFDM symbol boundary, but cannot identify the OFDM symbol index within the half-subframe. Therefore, in these embodiments, when the global OFDM symbol boundary is applied to all grid frequencies, the PSS correlation can be calculated twice: once assuming that the global OFDM symbol boundary for all grid frequencies identifies the first OFDM symbol in the half-subframe, and the other time does not assume that the global OFDM symbol boundary for all grid frequencies identifies the first OFDM symbol in the half-subframe. Therefore, when performing two PSS correlations, the amount of processing time saved can be reduced to 548:2 compared to known systems and methods.

[0025] In some embodiments, the systems and methods described herein may perform secondary synchronization signal correlation at the peak of the PSS correlation results for all grid frequencies to identify the remaining SSB in the SSB. For example, in some embodiments, the systems and methods described herein may perform DM-RS correlation at the global OFDM symbol boundary for all grid frequencies to identify the channel estimate, and the systems and methods described herein may perform MIB decoding and demodulation on the channel estimate to identify the remaining SSB in the SSB.

[0026] The systems and methods described herein can be used to find all valid LTE channels for a particular LTE band. For example, for LTE bands above 2 GHz with a total bandwidth in the range of 100 MHz and an LTE channel grid size of 100 KHz, the channel search in known systems and methods can start with PSS correlation at each sampling time offset. However, the systems and methods described herein can perform CP correlation to identify global OFDM symbol boundaries at every 5 MHz frequency step. The systems and methods described herein can then use the global OFDM symbol boundaries to perform PSS correlation only at the global OFDM symbol boundaries for all candidate grid frequencies within 5 MHz.

[0027] Figure 3 FIG. 2 is a block diagram of an RF communication system 20 according to the disclosed embodiment. Figure 3 As can be seen in FIG. 2 , the RF communication system 20 may include a user device 22 and a broadcast device 23 , and the user device 22 may include a programmable processor 26 and an RF transceiver 24 that may receive an RF signal broadcasted by the broadcast device 23 .

[0028] Figure 4 is a flow chart of method 100 according to the disclosed embodiment. Figure 4 As can be seen in , method 100 may include: as in 102, the programmable processor 26 measures the downlink signal energy over the bandwidth of the wireless radio channel to identify the center frequency of the signal broadcast by the broadcasting device 23 on the wireless radio channel. Then, method 100 may include: as in 104, the programmable processor 26 processes the signal at the center frequency of the signal to identify the first SSB of multiple SSBs on the wireless radio channel and the global OFDM symbol boundary. Finally, method 100 may include: as in 106, the programmable processor 26 uses the global OFDM symbol boundary for all grid frequencies of the wireless radio channel to identify the remaining SSBs of the multiple SSBs.

[0029] Figure 5 is a flow chart of a method 200 according to the disclosed embodiment and shows Figure 4 An embodiment of the method 100. Figure 5As can be seen in , method 200 may include: as in 202, the programmable processor 26 measures the downlink signal energy over the bandwidth of the wireless radio channel to identify the center frequency of the signal broadcast by the broadcasting device 23 on the wireless radio channel. Then, method 200 may include: as in 204, the programmable processor 26 calculates the CP correlation of the signal at the center frequency of the signal to identify the first SSB and the global OFDM symbol boundary on the wireless radio channel. Next, method 200 may include: as in 206, the programmable processor 26 identifies whether there is a next SSB on the next grid frequency of the wireless radio channel by: calculating the PSS correlation at the global OFDM symbol boundary and for the next grid frequency; performing secondary synchronization signal correlation at the peak of the PSS correlation result; performing DM-RS correlation at the global OFDM symbol boundary and for the next grid frequency to identify the channel estimate; and performing MIB decoding and demodulation on the channel estimate.

[0030] After identifying whether there is a next SSB on the next grid frequency, as in 206, the method 200 may include the programmable processor 26 determining whether the next SSB has been searched for in each grid frequency, as in 208. If so, the method 200 may terminate, as in 210. However, if each grid frequency has not been searched, the method 200 may include the programmable processor 26 continuing to identify whether there is a next synchronization signal block on the next grid frequency of the wireless radio channel, as in 206.

[0031] Although several embodiments have been described in detail above, other modifications are possible. For example, other components may be added to or removed from the described systems, and other embodiments may fall within the scope of the invention.

[0032] It will be observed from the foregoing that many variations and modifications may be implemented without departing from the spirit and scope of the present invention. It should be understood that no limitation regarding the particular system or method described herein is intended or should be inferred. Of course, it is intended to cover all such modifications as fall within the spirit and scope of the present invention.

Claims

1. A communication method, comprising: measuring downlink signal energy over a bandwidth of a radio channel to identify a center frequency of a signal broadcast on said radio channel; calculating a cyclic prefix correlation of the signal at the center frequency of the signal to thereby identify a first synchronization signal block of a plurality of synchronization signal blocks and a global OFDM symbol boundary for the radio channel; and A primary synchronization signal correlation is calculated for all grid frequencies of the radio channel at the global OFDM symbol boundaries to identify remaining synchronization signal blocks of the plurality of synchronization signal blocks.

2. The method according to claim 1, further comprising: Secondary synchronization signal correlation is performed at a peak of the primary synchronization signal correlation results for all of the grid frequencies.

3. The method according to claim 1, further comprising: performing DM-RS correlation at the global OFDM symbol boundary for all of the grid frequencies to identify a channel estimate; as well as MIB decoding and demodulation are performed on the channel estimate.

4. The method according to claim 1, further comprising: Calculating the primary synchronization signal correlation for all the grid frequencies at the global OFDM symbol boundaries by: calculating the primary synchronization signal correlation for all the grid frequencies for the first time at each of the OFDM symbol boundaries; and calculating the primary synchronization signal correlation a second time for all the grid frequencies at each of the OFDM symbol boundaries, wherein, for the first time, the global OFDM symbol boundary for all the grid frequencies is assumed to indicate the first OFDM symbol in a half-subframe of the signal, and Wherein, for the second time, the global OFDM symbol boundary for all the grid frequencies is not assumed to indicate the first OFDM symbol in the half-subframe of the signal.

5. The method according to claim 1, further comprising: Calculating the cyclic prefix correlation of the signal at the center frequency of the signal by: calculating the cyclic prefix correlation of the signal for the first time at the center frequency of the signal; calculating the cyclic prefix correlation of the signal for a second time at the center frequency of the signal; and selecting the result of the cyclic prefix correlation having the highest correlation value for use in identifying the first synchronization signal block of the plurality of synchronization signal blocks and the global OFDM symbol boundary, Wherein, for the first time, it is assumed that the subcarrier spacing of the signal is a first value, and For the second time, it is assumed that the subcarrier spacing of the signal is a second value different from the first value.

6. The method according to claim 1, further comprising: The cyclic prefix correlation of the signal is calculated as a moving correlation at the center frequency of the signal.

7. The method according to claim 1, further comprising: A maximum square peak output value is identified based on the cyclic prefix correlation to identify the global OFDM symbol boundary.

8. The method according to claim 1, wherein: The radio channel comprises a 5G radio channel.

9. The method according to claim 1, further comprising: Frequency edges of the signal are identified by measuring the downlink signal energy.

10. A communication system comprising: RF transceiver; as well as Programmable processors, wherein the radio frequency transceiver receives a signal broadcast on a radio channel, and The programmable processor performs the following operations: measuring downlink signal energy over a bandwidth of the radio channel to identify a center frequency of the signal; calculating a cyclic prefix correlation of the signal at the center frequency of the signal to thereby identify a first synchronization signal block of a plurality of synchronization signal blocks and a global OFDM symbol boundary for the radio channel; and A primary synchronization signal correlation is calculated for all grid frequencies of the radio channel at the global OFDM symbol boundaries to identify remaining synchronization signal blocks of the plurality of synchronization signal blocks.

11. The system according to claim 10, wherein: The programmable processor performs secondary synchronization signal correlation at peaks of the primary synchronization signal correlation results for all of the grid frequencies.

12. The system according to claim 10, wherein: The programmable processor performs DM-RS correlation for all of the grid frequencies at the global OFDM symbol boundary to identify a channel estimate, and wherein the programmable processor performs MIB decoding and demodulation on the channel estimate.

13. The system according to claim 10, wherein: The programmable processor calculates the primary synchronization signal correlation for all of the grid frequencies at the global OFDM symbol boundaries by: calculating the primary synchronization signal correlation for all of the grid frequencies for a first time at each of the OFDM symbol boundaries; and calculating the primary synchronization signal correlation a second time at each of the OFDM symbol boundaries for all the grid frequencies, wherein the first time it is assumed that the global OFDM symbol boundary for all the grid frequencies indicates the first OFDM symbol in the half-subframe of the signal, and wherein the second time it is not assumed that the global OFDM symbol boundary for all the grid frequencies indicates the first OFDM symbol in the half-subframe of the signal.

14. The system according to claim 10, wherein: The programmable processor calculates the cyclic prefix correlation of the signal at the center frequency of the signal by: calculating the cyclic prefix correlation of the signal for a first time at the center frequency of the signal; calculating the cyclic prefix correlation of the signal for a second time at the center frequency of the signal; And selecting the result with the highest correlation value in the cyclic prefix correlation for identifying the first synchronization signal block among the multiple synchronization signal blocks and the global OFDM symbol boundary, wherein the subcarrier spacing of the signal is assumed to be a first value for the first time, and wherein the subcarrier spacing of the signal is assumed to be a second value different from the first value for the second time.

15. The system according to claim 10, wherein: The programmable processor calculates the cyclic prefix correlation of the signal as a moving correlation at the center frequency of the signal.

16. The system of claim 10, wherein: The programmable processor identifies a maximum square peak output value based on the cyclic prefix correlation to identify the global OFDM symbol boundary.

17. The system according to claim 10, wherein: The radio channel comprises a 5G radio channel.

18. The system of claim 10, wherein: The programmable processor identifies frequency edges of the signal by measuring the downlink signal energy.

19. A communication method, comprising: measuring downlink signal energy over a bandwidth of an LTE radio frequency band to identify a center frequency of a signal broadcast over the LTE radio frequency band; calculating a cyclic prefix correlation of the signal at the center frequency of the signal to identify global OFDM symbol boundaries for the LTE radio band; and A primary synchronization signal correlation is calculated for all grid frequencies of the LTE radio band at the global OFDM symbol boundaries to identify a valid LTE channel.

Images