5GNR digital remote system for realizing TDD synchronization by using CPRI and synchronization method of 5GNR digital remote system

Abstract

The invention belongs to the technical field of 5G. The invention provides a 5GNR digital remote system for realizing TDD synchronization by using a CPRI. The 5GNR digital remote system comprises a near-end machine and a far-end machine, the near-end machine is used for generating a main end 10ms frame header of the CPRI by using a first local counter; tDD synchronization is completed, and a 10ms frame header of 5GNR is generated; the numerical value of a first local counter when the 10ms frame header of the 5GNR occurs is used as a relative relation value between the 10ms frame header of the 5GNR and the 10ms frame header of the main end of the CPRI; acquiring uplink and downlink switching information of the 5GNR; transmitting a relative relation value between the 10ms frame header of the 5GNR and the 10ms frame header of the master end of the CPRI and uplink and downlink switching information of the 5GNR to a remote terminal through a CPRI interface; the far-end machine is used for recovering a 10ms frame header of a slave end of the CPRI through a CPRI interface protocol; the 10ms frame header of the slave end of the 5GNR is recovered by using the relative relation values of the 10ms frame header of the slave end of the CPRI, the 10ms frame header of the 5GNR and the 10ms frame header of the master end of the CPRI; and generating local TDD uplink and downlink signals by using the 10ms frame header of the slave end of the 5GNR and the received uplink and downlink switching information of the 5GNR, thereby realizing TDD synchronization.

Description

Technical Field

[0001] The present invention belongs to the field of 5G technology, and in particular relates to a 5G_NR digital remote system and a synchronization method thereof for realizing TDD synchronization using CPRI. Background Art

[0002] In mobile communication networks, due to various reasons, it is impossible for the network to achieve complete seamless coverage. For operators, sometimes it is difficult to build and open base stations in some coverage blind areas due to cost and transmission conditions.

[0003] The 5G_NR digital remote system is a mobile communication base station signal remote device, which serves as an auxiliary means of base station coverage. By converting the RF signal to a digital signal, and then transmitting the digitized optical signal, and compensating for the optical loss digitally, the system efficiency can be better improved. The 5G_NR digital remote system consists of a near-end machine and a far-end machine. After the wireless signal is coupled from the base station, it enters the near-end machine through electro-optical conversion, converts the electrical signal into an optical signal, and then transmits it from the near-end machine to the optical fiber, and then to the far-end machine through the optical fiber. The signal is converted into an electrical signal and enters the RF unit for amplification. After the signal is amplified, it is sent to the transmitting antenna to cover the target area. The working principle of the uplink is the same. The signal sent by the mobile phone reaches the far-end machine through the receiving antenna, and then reaches the near-end machine and returns to the base station, such as Figure 1 This is how the 5G_NR digital telemetry system works.

[0004] 5G_NR digital remote system can expand the service range and eliminate coverage blind spots, such as signal blind spots formed by obstacles such as mountains, buildings, and trees. In suburban areas, it can enhance the field strength and expand the coverage of suburban stations. It can also solve indoor coverage problems such as signal attenuation blind spots in large buildings, underground shopping malls, tunnels, etc. In addition, the signal of idle base stations can be guided to the coverage area of ​​busy base stations to relieve busyness.

[0005] Most of the existing 5G_NR digital remote systems use external synchronization modules or on-board FPGAs to obtain synchronization information from baseband signals, and complete TDD synchronization through complex calculations to extract TDD synchronization information. Although these methods can solve the synchronization problem, there are many devices in a system, which will cause problems such as increased costs or increased FPGA complexity and costs. In addition, the number of remote devices in a remote system is far greater than that of near-end devices, and the increase in the cost of remote devices has a greater impact on the system cost. Summary of the invention

[0006] The present invention aims at the problem that the TDD synchronization method of the 5G_NR digital remote system in the prior art is complicated and costly, and provides a 5G_NR digital remote system that uses CPRI to realize TDD synchronization, including a near-end machine and a far-end machine, wherein the near-end machine and the far-end machine are connected via a CPRI interface, and there is at least one far-end machine;

[0007] The near-end machine is used to generate a 10ms frame header of the master end of CPRI by using the first local counter; complete TDD synchronization and generate a 10ms frame header of 5G_NR;

[0008] The value of the first local counter when the 10ms frame header of 5G_NR occurs is used as the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI;

[0009] Obtain 5G_NR uplink and downlink switching information;

[0010] The relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI and the uplink and downlink switching information of 5G_NR are transmitted to the remote machine through the CPRI interface;

[0011] The remote machine is used to recover the CPRI slave end 10ms frame header through the CPRI interface protocol;

[0012] The relative relationship between the 10ms frame header of the CPRI slave end, the 10ms frame header of the 5G_NR, and the 10ms frame header of the CPRI master end is used to restore the 10ms frame header of the 5G_NR slave end.

[0013] Utilize the 10ms frame header of the 5G_NR slave end and the received uplink and downlink switching information of the 5G_NR to generate local TDD uplink and downlink signals to achieve TDD synchronization.

[0014] In one embodiment, the remote machine adds a first-level cache for the relative relationship value between the received 10ms frame header of 5G_NR and the master-end 10ms frame header of CPRI.

[0015] In one embodiment, the remote machine generates a second local counter based on the 10ms frame header of the slave end of CPRI. When the value of the second local counter is equal to the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the CPRI master end, it is the position of the 10ms frame header of the slave end of 5G_NR.

[0016] In one embodiment, the remote machine generates a third local counter using the 10ms frame header of the slave end of 5G_NR. When the value of the third local counter is equal to the uplink and downlink switching information of 5G_NR, the conversion of the TDD signal from 0 to 1, or from 1 to 0 is completed to generate local TDD uplink and downlink signals.

[0017] In one embodiment, the remote machine is cascaded with N lower-level remote machines in sequence, where N is greater than or equal to 1; the remote machine is used to transmit the relative relationship value between the received 5G_NR 10ms frame header and the CPRI master-end 10ms frame header and the uplink and downlink switching information of the 5G_NR to the cascaded lower-level remote machines in sequence, and the lower-level remote machines achieve TDD synchronization based on the received information.

[0018] The present invention also provides a method for realizing TDD synchronization of a 5G-NR digital remote system by using CPRI, comprising the following steps:

[0019] Step 1: The near-end machine uses the first local counter to generate a 10ms frame header of the CPRI master end, completes TDD synchronization, and generates a 10ms frame header of 5G_NR; obtains uplink and downlink switching information of 5G_NR;

[0020] Step 2: Use the value of the first local counter when the 10ms frame header of 5G_NR occurs as the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI;

[0021] Step 3: The near-end machine transmits the relative relationship value of the 10ms frame header of the 5G_NR and the 10ms frame header of the master end of the CPRI and the uplink and downlink switching information of the 5G_NR to the remote machine through the CPRI interface;

[0022] Step 4: The remote machine recovers the CPRI slave 10ms frame header through the CPRI interface protocol;

[0023] Step 5: The remote machine uses the relative relationship value of the 10ms frame header of the CPRI slave end, the 10ms frame header of the 5G_NR, and the 10ms frame header of the CPRI master end to restore the 10ms frame header of the 5G_NR slave end;

[0024] Step 6: The remote machine uses the 10ms frame header of the 5G_NR slave end and the received uplink and downlink switching information of the 5G_NR to generate local TDD uplink and downlink signals to achieve TDD synchronization.

[0025] In one embodiment, in step 5, the remote machine adds a first-level cache for the relative relationship value between the received 10ms frame header of 5G_NR and the master-end 10ms frame header of CPRI.

[0026] In one embodiment, in step 5, the remote machine generates a second local counter based on the 10ms frame header of the slave end of CPRI. When the value of the second local counter is equal to the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the CPRI master end, it is the 10ms frame header of the slave end of 5G_NR.

[0027] In one embodiment, in step 6, the remote machine generates a third local counter using the 10ms frame header of the slave end of 5G_NR. When the value of the third local counter is equal to the uplink and downlink switching information of 5G_NR, the conversion of the TDD signal from 0 to 1, or from 1 to 0 is completed to generate a local TDD uplink and downlink signal.

[0028] In one embodiment, the following steps are also included: the remote machine transmits the relative relationship between the 10ms frame header of 5G_NR and the 10ms frame header of the main end of CPRI and the uplink and downlink switching information of 5G_NR to the Nth level remote machine in sequence, where N is greater than or equal to 1; any level of remote machine executes steps 4-6 to generate local TDD uplink and downlink signals to achieve TDD synchronization.

[0029] The beneficial effect of the present invention is that the present invention generates the master end 10ms frame header of CPRI by using a local counter at the near end machine, calculates the relative relationship between the 10ms frame header of 5G_NR and the master end 10ms frame header of CPRI, and transmits it to the remote end machine. The remote end machine uses the 10ms timing function of the CPRI interface itself to complete the recovery of the slave end 10ms frame header of 5G_NR which is different from the source of this system, thereby generating local TDD uplink and downlink signals to achieve TDD synchronization. It can be seen that the present invention can achieve TDD synchronization between the remote end machine and the near end machine by using only simple counting, which greatly reduces the design cost and complexity of the remote end machine in TDD synchronization, and this invention is compatible with 4G synchronization without additional overhead. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 , diagram of application scenario of optical fiber repeater station in the background technology of the present invention.

[0031] Figure 2 , a flowchart of the near-end processing of the 5G_NR digital remote system in Example 1 of the present invention.

[0032] Figure 3 , a flowchart of the remote device processing of the 5G_NR digital remote system in Example 1 of the present invention.

[0033] Figure 4 , structural diagram of the one-to-one 5G_NR digital remote system in Example 1 of the present invention.

[0034] Figure 5 , structural diagram of the one-to-many 5G_NR digital remote system in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] Example 1

[0037] In this example, a 5G_NR digital remote system for implementing TDD synchronization using CPRI is provided, including a near-end machine and a far-end machine, wherein the near-end machine and the far-end machine are connected via a CPRI interface.

[0038] When the system is working, Figure 2 As shown. First, the near-end machine uses the first local counter to generate the CPRI master end 10ms frame header, completes TDD synchronization, generates the 5G_NR 10ms frame header, and obtains the uplink and downlink switching information of 5G_NR. The value of the first local counter when the 5G_NR 10ms frame header occurs is used as the relative relationship value between the 5G_NR 10ms frame header and the CPRI master end 10ms frame header.

[0039] The first local counter is used to generate the master-end 10ms frame header of the CPRI. It should be noted that the counter clock frequency should be high enough to accurately count to 10ms. In this example, the first local counter uses a 10ms counter.

[0040] TDD synchronization includes the following steps: 1. Use the cross-correlation algorithm to complete PSS synchronization. 2. Perform frequency offset estimation and compensation. 3. Complete SSS synchronization and obtain PCI information. 4. Demodulate PBCH and obtain MIB and SIB information. Thus, the TDD frame header is produced, and the uplink and downlink time slot ratio and special subframe format of TDD are obtained. TDD synchronization is completed. The TDD synchronization method is a common prior art in this field and will not be repeated here.

[0041] Secondly, the near-end machine transmits the relative relationship between the 10ms frame header of 5G_NR and the 10ms frame header of the main end of CPRI, as well as the uplink and downlink switching information of 5G_NR to the far-end machine through the CPRI interface. Specifically, the spare bits of the management channel or data channel of the CPRI protocol are transmitted to the far-end machine through the optical port.

[0042] After receiving the above information, the remote machine adds a level 1 cache to the relative relationship value between the received 5G_NR 10ms frame header and the CPRI master end 10ms frame header. The purpose is to avoid recovery errors caused by each update of the relative relationship value, so an extra level of cache is added to the value to make its update position away from the position where the slave end 5G_NR 10ms frame header is generated.

[0043] like Figure 3 As shown, after the remote machine recovers the 10ms frame header of the CPRI slave end through the CPRI interface protocol, the relative relationship value of the 10ms frame header of the CPRI slave end, the 10ms frame header of the 5G_NR and the 10ms frame header of the CPRI master end is used to recover the 10ms frame header of the 5G_NR slave end.

[0044] Specifically, the remote machine generates a second local counter based on the 10ms frame header of the slave end of CPRI. When the value of the second local counter is equal to the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the CPRI master end, it is the position of the 10ms frame header of the slave end of 5G_NR.

[0045] Finally, the remote machine uses the 10ms frame header of the slave end of 5G_NR and the uplink and downlink switching information of the received 5G_NR to generate local TDD uplink and downlink signals to achieve TDD synchronization. Specifically, the remote machine uses the 10ms frame header of the slave end of 5G_NR to generate a third local counter. When the value of the third local counter is equal to the uplink and downlink switching information of 5G_NR, the conversion of the TDD signal from 0 to 1, or from 1 to 0, is completed to generate local TDD uplink and downlink signals. The second local counter and the third local counter are both local 10ms counters.

[0046] Furthermore, in practical applications, the near-end machine is usually connected to multiple remote machines. There can be multiple or one remote machine, each connected to the near-end machine. The remote machine can also be connected to N lower-level remote machines in sequence, where N is greater than or equal to 1. In other words, the remote machine can be connected to multiple or one first-level remote machines, and the first-level remote machine can be connected to one or more second-level remote machines, and so on, until the Nth-level remote machine is cascaded. The cascading methods are as follows: Figure 4 and Figure 5 The difference is that after the first-level remote machine realizes TDD synchronization as described above, the relative relationship value between the received 10ms frame header of 5G_NR and the 10ms frame header of the main end of CPRI and the uplink and downlink switching information of 5G_NR are transmitted to the next-level remote machine to complete the TDD information transmission in the cascade state. The next-level remote machine realizes TDD synchronization according to the received information and the above-mentioned remote machine synchronization method.

[0047] It should be noted that there is a delay between the TDD signal of the remote machine recovered by the above method and the TDD signal of the near-end machine. This delay is due to the delay of the CPRI frame caused by the optical fiber length, which causes the delay of the slave 10ms frame header recovered by the remote machine relative to the master 10ms frame header of the near-end machine. The same baseband data will also have the same delay after being transmitted through the CPRI frame on the optical fiber. In a one-to-one system with one near-end machine and one remote machine, the baseband signal delay is consistent with the recovered TDD signal delay. The purpose of our design is to align the baseband signal with the TDD signal, so there is no need to adjust the TDD signal separately. In a one-to-many system with one near-end machine and multiple remote machines, in order to achieve the consistency of the delay of each remote machine, the calculation and adjustment of the system delay, the baseband signal delay and the delay adjustment value of the recovered TDD signal are also consistent. It only needs to be adjusted according to the delay value of the baseband signal, and no additional resources are required. The present invention cleverly utilizes simple counting to realize TDD synchronization of the remote machine and the near-end machine, thereby greatly reducing the design cost and complexity of TDD synchronization of the remote machine.

[0048] The design of the present invention is generated when the digital remote system is connected to the base station via an air interface, the clocks are not synchronized, and there are problems caused by frequency deviation. The system is internally a synchronous system, and the remote machine needs to be synchronized with the clock chip of the proximal machine. The temperature stability of the clock chip of the proximal machine is between ±100 and ±250ppb, which is equivalent to a deviation of 1-2.5ns every 10ms. The relative relationship between the 10ms frame header of 5G_NR and the 10ms frame header of the CPRI master end is filled in the free bit of the CPRI superframe data channel and updated every 10ms. This deviation value has no effect on the TDD system. In the actual application of the system, the uplink and downlink rate tests are completely normal. The present invention is completely feasible.

[0049] Example 2

[0050] This example provides a method for implementing TDD synchronization of a 5G_NR digital remote system using CPRI, which is applied to the system described in Example 1 and includes the following steps:

[0051] Step 1: The near-end machine uses the first local counter to generate a 10ms frame header of the CPRI master end, completes TDD synchronization, and generates a 10ms frame header of 5G_NR; obtains uplink and downlink switching information of 5G_NR;

[0052] Step 2: Use the value of the first local counter when the 10ms frame header of 5G_NR occurs as the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI;

[0053] Step 3: The near-end machine transmits the relative relationship value of the 10ms frame header of the 5G_NR and the 10ms frame header of the master end of the CPRI and the uplink and downlink switching information of the 5G_NR to the remote machine through the CPRI interface;

[0054] Step 4: The remote machine recovers the CPRI slave 10ms frame header through the CPRI interface protocol;

[0055] Step 5: The remote machine uses the relative relationship value of the 10ms frame header of the CPRI slave end, the 10ms frame header of the 5G_NR, and the 10ms frame header of the CPRI master end to restore the 10ms frame header of the 5G_NR slave end; the remote machine adds a first-level cache to the relative relationship value of the received 10ms frame header of the 5G_NR and the 10ms frame header of the CPRI master end. The remote machine generates a second local counter according to the 10ms frame header of the CPRI slave end. When the value of the second local counter is equal to the relative relationship value of the 10ms frame header of the 5G_NR and the 10ms frame header of the CPRI master end, it is the 10ms frame header of the 5G_NR slave end.

[0056] Step 6: The remote machine uses the 10ms frame header of the slave end of 5G_NR and the received uplink and downlink switching information of 5G_NR to generate local TDD uplink and downlink signals to achieve TDD synchronization. The remote machine uses the 10ms frame header of the slave end of 5G_NR to generate a third local counter. When the value of the third local counter is equal to the uplink and downlink switching information of 5G_NR, the conversion of the TDD signal from 0 to 1, or from 1 to 0, is completed to generate local TDD uplink and downlink signals.

[0057] The remote machine transmits the relative relationship between the 10ms frame header of 5G_NR and the 10ms frame header of the main end of CPRI and the uplink and downlink switching information of 5G_NR to the Nth level remote machine in sequence, where N is greater than or equal to 1; any level of remote machine executes steps 4-6 to generate local TDD uplink and downlink signals to achieve TDD synchronization.

[0058] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The above-mentioned embodiments only express the implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A 5G_NR digital remote system for realizing TDD synchronization using CPRI, comprising a near-end machine and a far-end machine, wherein the near-end machine and the far-end machine are connected via a CPRI interface, and there is at least one far-end machine, characterized in that: The near-end machine is used to generate a 10ms frame header of the master end of CPRI by using the first local counter; complete TDD synchronization and generate a 10ms frame header of 5G_NR; The value of the first local counter when the 10ms frame header of 5G_NR occurs is used as the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI; Obtain 5G_NR uplink and downlink switching information; The relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI and the uplink and downlink switching information of 5G_NR are transmitted to the remote machine through the CPRI interface; The remote machine is used to recover the CPRI slave end 10ms frame header through the CPRI interface protocol; The relative relationship between the 10ms frame header of the CPRI slave end, the 10ms frame header of the 5G_NR, and the 10ms frame header of the CPRI master end is used to restore the 10ms frame header of the 5G_NR slave end. Utilize the 10ms frame header of the 5G_NR slave end and the received uplink and downlink switching information of the 5G_NR to generate local TDD uplink and downlink signals to achieve TDD synchronization.

2. According to claim 1, a 5G_NR digital remote system for realizing TDD synchronization using CPRI, characterized in that The remote machine adds a first-level cache for the relative relationship value between the received 10ms frame header of 5G_NR and the 10ms frame header of the main end of CPRI.

3. According to claim 2, a 5G_NR digital remote system for realizing TDD synchronization using CPRI, characterized in that The remote machine generates a second local counter based on the 10ms frame header of the slave end of CPRI. When the value of the second local counter is equal to the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the CPRI master end, it is the position of the 10ms frame header of the slave end of 5G_NR.

4. According to claim 3, a 5G_NR digital remote system for realizing TDD synchronization using CPRI is characterized in that ,The remote machine uses the 10ms frame header of the slave end of 5G_NR to generate a third local counter. When the value of the third local counter is equal to the uplink and downlink switching information of 5G_NR, the conversion of the TDD signal from 0 to 1, or from 1 to 0, is completed, and a local TDD uplink and downlink signal is generated.

5. A 5G_NR digital remote system for implementing TDD synchronization using CPRI according to any one of claims 1 to 4, characterized in that The remote machine is cascaded with N lower-level remote machines in sequence, where N is greater than or equal to 1; the remote machine is used to transmit the relative relationship value between the received 5G_NR 10ms frame header and the CPRI master-end 10ms frame header and the uplink and downlink switching information of 5G_NR to the cascaded lower-level remote machines in sequence, and the lower-level remote machines realize TDD synchronization according to the received information.

6. A method for realizing TDD synchronization of 5G_NR digital remote system using CPRI, characterized in that , including the following steps: Step 1: The near-end machine uses the first local counter to generate a 10ms frame header of the CPRI master end, completes TDD synchronization, and generates a 10ms frame header of 5G_NR; obtains uplink and downlink switching information of 5G_NR; Step 2: Use the value of the first local counter when the 10ms frame header of 5G_NR occurs as the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the master end of CPRI; Step 3: The near-end machine transmits the relative relationship value of the 10ms frame header of the 5G_NR and the 10ms frame header of the master end of the CPRI and the uplink and downlink switching information of the 5G_NR to the remote machine through the CPRI interface; Step 4: The remote machine recovers the CPRI slave 10ms frame header through the CPRI interface protocol; Step 5: The remote machine uses the relative relationship value of the 10ms frame header of the CPRI slave end, the 10ms frame header of the 5G_NR, and the 10ms frame header of the CPRI master end to restore the 10ms frame header of the 5G_NR slave end; Step 6: The remote machine uses the 10ms frame header of the 5G_NR slave end and the received uplink and downlink switching information of the 5G_NR to generate local TDD uplink and downlink signals to achieve TDD synchronization.

7. A method for realizing TDD synchronization of a 5G_NR digital remote system using CPRI according to claim 6, characterized in that In step 5, the remote machine adds a first-level cache for the relative relationship value between the received 5G_NR 10ms frame header and the CPRI master end 10ms frame header.

8. A method for realizing TDD synchronization of a 5G_NR digital remote system using CPRI according to claim 7, characterized in that In step 5, the remote machine generates a second local counter based on the 10ms frame header of the slave end of CPRI. When the value of the second local counter is equal to the relative relationship value between the 10ms frame header of 5G_NR and the 10ms frame header of the CPRI master end, it is the 10ms frame header of the slave end of 5G_NR.

9. A method for realizing TDD synchronization of a 5G_NR digital remote system using CPRI according to claim 8, characterized in that In step 6, the remote machine generates a third local counter using the 10ms frame header of the slave end of 5G_NR. When the value of the third local counter is equal to the uplink and downlink switching information of 5G_NR, the conversion of the TDD signal from 0 to 1, or from 1 to 0, is completed to generate a local TDD uplink and downlink signal.

10. A method for realizing TDD synchronization of a 5G_NR digital remote system using CPRI according to claim 9, characterized in that , also includes the following steps: the remote machine transmits the relative relationship between the 10ms frame header of 5G_NR and the 10ms frame header of the main end of CPRI and the uplink and downlink switching information of 5G_NR to the Nth level remote machine in sequence, N is greater than or equal to 1; any level of remote machine executes steps 4-6 to generate local TDD uplink and downlink signals to achieve TDD synchronization.

Images