Automatic analysis and warning method of optical connection between BBU combination and RRU of radio station

Abstract

An Automated Analysis and Warning of Optical Transmission (AWOT) between BBU unit and RRU of radio transmitting station accurately and quickly identifies errors on an optical transmission line, thereby reducing costs in terms of labor and equipment, and at the same time reducing service downtime of mobile communication systems.

Claims

1. A method to automatically analyze and warn optical connection status between a BBU (Base Band Unit) and a RRU (Remote Radio Unit) in an Automated Analysis and Warning of Optical Transmission (AWOT) includes the following steps: (i) read a warning status of a CPRI (Common Public Radio Interface) and an optical power of a photoelectric converter module on the BBU; (ii) connect to the RRU via an Ethernet interface, in case of a successful connection, perform step (iii), otherwise, if connection is unsuccessful, perform step (v); (iii) read an optical power of the photoelectric converter module on the RRU; (iv) calculate an attenuation on an optical link from BBU to RRU and vice versa, from RRU to BBU using the following formula: $\begin{array}{cc}\Delta 1=10\log \left(\frac{P_{\mathrm{BBU}\_\mathrm{TX}}}{P_{\mathrm{RRU}\_\mathrm{RX}}}\right)\Delta 2=10\log \left(\frac{P_{\mathrm{RRU}\_\mathrm{TX}}}{P_{\mathrm{BBU}\_\mathrm{RX}}}\right)& \left(1\right)\end{array}$ wherein, Δ1 (dB) is the attenuation on the optical path from BBU to RRU, Δ2 (dB) is the attenuation on the optical path from the RRU to the BBU, P.sub.BBU_TX (mW) is an emitted optical power of SFP on the BBU, P.sub.BBU_RX (mW) is an obtained optical power of SFP on the BBU, P.sub.RRU_TX (mW) is an emitted optical power of SFP on the RRU, P.sub.RRU_RX (mW) is an obtained optical power of SFP on the RRU; (v) analyze an optical transmission fault and give the following warnings: TABLE-US-00005 Connect CPRI Situation P.sub.BBU_TX P.sub.BBU_RX P.sub.RRU_TX P.sub.RRU_RX the RRU warnings 1 normal normal normal normal yes no 2 normal normal normal x yes yes 3 normal x normal normal yes yes 4 normal normal normal normal yes yes 5 normal normal normal normal yes yes 6 error x x x x x 7 normal error NA NA are not no 8 normal normal NA NA are not yes 9 normal normal NA NA are not no Situation Δ1 Δ2 Error code 1 0 < Δ1 ≤ 0 < Δ2 ≤ OPT_CONN_NORMAL attenuation attenuation threshold threshold 2 Δ1 > x OPT_CABLE_BROKEN Attenuation threshold 3 x Δ2 > OPT_CABLE_BROKEN Attenuation threshold 4 Δ1 < 0 0 < Δ2 ≤ OPT_SFP_BROKEN attenuation threshold 5 0 < Δ1 ≤ Δ2 < 0 OPT_SFP_BROKEN attenuation threshold 6 x x OPT_SFP_BBU_BROKEN 7 NA NA OPT_CONN_ERROR_1 8 NA NA OPT_CABLE_BROKEN 9 NA NA ETH_CONN_ERROR wherein, Optical power P.sub.BBU_TX, P.sub.BBU_RX, P.sub.RRU_TX and P.sub.RRU_RX 3 thresholds are normal, warning and error, x is an occurrence of any possible event, NA is not applicable, attenuation threshold is an allowable attenuation on the optical transmission line, attenuation threshold is calculated by a product of the attenuation coefficient α (dB/km) with an optical wire length L (km), α is defined in accordance to the ITU Telecommunication standardization and summarized in the following table: TABLE-US-00006 Attenuation Wavelength coefficient α Fiber type (nm) (dB/km) G.652.A 1310 0.5 1550 0.4 G.652.B 1310 0.4 1550 0.35 1625 0.4 G.652.C, G.652.D 1310-1625 0.4 G.653.A, G.653.B 1550 0.35 G.655.C, G.655.D, 1550 0.35 G.655.E 1625 0.4 Error code is defined in the following table: TABLE-US-00007 Error code Describe OPT_CONN_NORMAL Optical connection is in normal condition, without errors OPT_CABLE_BROKEN The optical cable is damaged OPT_SFP_BROKEN SFP on RRU or SFP on BBU fails OPT_SFP_BBU_BROKEN The SFP on the BBU is broken OPT_CONN_ERROR_1 It can happen in one of the following 3 cases: - Failure of optical cord from RRU to BBU - SFP on RRU failure - RRU off ETH_CONN_ERROR The Ethernet communication has an error.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 depicts a radio reception station using CPRI and optical transmission.

(2) FIG. 2 shows a flowchart of the implementation steps of the AWOT method according to the invention.

(3) FIG. 3 shows a drawing of a radio base station using the AWOT method.

(4) FIG. 4 illustrates the results of implementing the AWOT method in the case of good SFP and optical fiber.

(5) FIG. 5 illustrates the results of implementing the AWOT method in case SFP on the BBU fails.

(6) FIG. 6 illustrates the results of performing the AWOT method in the case of a damaged optical cord.

(7) FIG. 7 illustrates the results of implementing the AWOT method in case of SFP on RRU failure.

DETAILED DESCRIPTION

(8) The following section describes in detail the method of automatic analysis and warning of optical connection status between the BBU unit and the RRU unit in the radio base station. As shown in FIG. 2, the AWOT method under the invention includes the following 5 steps:

(9) Step 1: Read Warning Status of CPRI and Optical Power of Photoelectric Converter Module on BBU

(10) The CPRI block has a register to store the alarm state, including the warnings about the transmission line such as loss of signal (LOS), loss of frame alignment (Loss Of Frame—LOF). The AWOT method reads the alarm register value of the CPRI to perform the analysis in Step 5. In parallel with the reading of the CPRI state, the AWOT method reads the TX and RX optical power values of the photoelectric converter module on BBU.

(11) Step 2: Connect to the RRU Via Ethernet Interface, in Case of Successful Connection, Perform Step 3, Otherwise, if the Connection is not Successful, Perform Step 5.

(12) The CPRI unit on the BBU and RRU has an Ethernet interface that is used for the exchange of management and control messages. Specifically, BBU can access the RRU via Ethernet interface to get information about the operational status of the RRU. The protocol used is Secure Shell (SSH), there are two situations, in case the connection is successful, follow step 3, if the connection is not successful, follow step 5.

(13) Step 3: Read the Optical Power of SFP on the RRU

(14) After BBU has access to the RRU, the AWOT method reads the TX and RX optical power of the photoelectric converter module on the RRU, and sends the reading to the BBU.

(15) Step 4: Calculate the Attenuation on the Optical Link from BBU to RRU and Vice Versa, from RRU to BBU

(16) When there is enough data on the optical power of SFP on the RRU and BBU, AWOT method calculates the attenuation on the optical transmission line by the formula (1) below:

(17) $\begin{array}{cc}\Delta 1=10\log \left(\frac{P_{\mathrm{BBU}\_\mathrm{TX}}}{P_{\mathrm{RRU}\_\mathrm{RX}}}\right)\Delta 2=10\log \left(\frac{P_{\mathrm{RRU}\_\mathrm{TX}}}{P_{\mathrm{BBU}\_\mathrm{RX}}}\right)& \left(1\right)\end{array}$
Inside, Δ1 (dB) is the attenuation on the optical path from BBU to RRU, Δ2 (dB) is the attenuation on the optical path from the RRU to the BBU, P.sub.BBU_TX (mW) is the emitted optical power of SFP on the BBU, P.sub.BBU_RX (mW) is the obtained optical power of SFP on the BBU, P.sub.RRU_TX (mW) is the emitted optical power of SFP on the RRU, P.sub.RRU_RX (mW) is the obtained optical power of SFP on the RRU,
Step 5: Analyze the Fault on the Optical Transmission Line and Give Warnings

(18) First, the AWOT system performs analysis based on the state of the CPRI block. When there is no warning from the CPRI unit, and the optical power on the SFP is at a normal level, the AWOT system concludes that the optical connection is normal. Conversely, when there is an alarm from the CPRI unit, the AWOT system will automatically analyze the optical power value on the SFP of the BBU and RRU, thereby giving the alarms following Table 1:

(19) TABLE-US-00001 TABLE 1 Circumstances associated with optical connection between BBU and RRU Connect CPRI Situation P.sub.BBU_TX P.sub.BBU_RX P.sub.RRU_TX P.sub.RRU_RX the RRU warnings Δ1 Δ2 Error code 1 normal normal normal normal yes no 0 < Δ1 ≤ 0 < Δ2 ≤ OPT_CONN_NORMAL attenuation attenuation threshold threshold 2 normal normal normal x yes yes Δ1 > x OPT_CABLE_BROKEN Attenuation threshold 3 normal x normal normal yes yes x Δ2 > OPT_CABLE_BROKEN Attenuation threshold 4 normal normal normal normal yes yes Δ1 < 0 0 < Δ2 ≤ OPT_SFP_BROKEN attenuation threshold 5 normal normal normal normal yes yes 0 < Δ1 ≤ Δ2 < 0 OPT_SFP_BROKEN attenuation threshold 6 error x x x x x x x OPT_SFP_BBU_BROKEN 7 normal error NA NA no no NA NA OPT_CONN_ERROR_1 8 normal normal NA NA no yes NA NA OPT_CABLE_BROKEN 9 normal normal NA NA no no NA NA ETH_CONN_ERROR
Inside, Optical power P.sub.BBU_TX, P.sub.BBU_RX, P.sub.RRU_TX and P.sub.RRU_RX 3 thresholds are normal, warning and error, x is the occurrence of any possible event, NA is not applicable, The attenuation threshold is the allowable attenuation on the optical transmission line, the attenuation threshold is calculated by the product of the attenuation coefficient α (dB/km) with the optical wire length L (km), α is defined according to the ITU Telecommunication standardization and summarized in Table 2 below:

(20) TABLE-US-00002 TABLE 2 Loss coefficient by fiber type Attenuation Wavelength coefficient α Fiber type (nm) (dB/km) G.652.A 1310 0.5 1550 0.4 G.652.B 1310 0.4 1550 0.35 1625 0.4 G.652.C, G.652.D 1310-1625 0.4 G.653.A, G.653.B 1550 0.35 G.655.C, G.655.D, 1550 0.35 G.655.E 1625 0.4 The error codes are defined in the following Table 3:

(21) TABLE-US-00003 TABLE 3 Explanation of error codes Error code Describe OPT_CONN_NORMAL Optical connection is in normal condition, without errors OPT_CABLE_BROKEN The optical cable is damaged OPT_SFP_BROKEN SFP on RRU or SFP on BBU fails OPT_SFP_BBU_BROKEN The SFP on the BBU is broken OPT_CONN_ERROR_1 It can happen in one of the following 3 cases: - Failure of optical cord from RRU to BBU - SFP on RRU failure - RRU off ETH_CONN_ERROR The Ethernet communication has an error

(22) Based on the automatic analysis and warning of optical connection condition described in Step 1 to Step 5 above, the AWOT method follows the patent. can accurately and quickly identify the cause of a fault on the optical transmission line automatically. This is also the main purpose of the method according to the patent.

Invention Execution Example

(23) To demonstrate the effectiveness of the invention, an automated method of analyzing and warning the AWOT optical connection status was deployed and integrated into the BBU and RRU. The results of the test will help to evaluate the effectiveness of the method according to the invention.

(24) As shown in FIG. 3, when integrated into BBU and RRU, the system adopts the AWOT method consisting of the following 5 processing blocks: SFP optical power reading block; Ethernet communication block; Reading the state of CPRI block; Optical loss calculation block; Analysis and error warning block.

(25) The functions of the blocks in this system are designed according to the calculation steps of the AWOT method according to the invention, specifically as follows:

(26) 1. SFP Optical Power Reading Block

(27) This block performs optical power reading of photoelectric converter module through I2C communication standard (Inter-Integrated Circuit). This block is integrated on BBU and RRU. The value read is composed of the optical power emitted and the obtained optical power.

(28) 2. Ethernet Communication Block

(29) When applying the AWOT method, the Ethernet communication unit is responsible for sending the optical power value of SFP on the RRU to BBU.

(30) 3. Reading the State of CPRI Block

(31) This block performs CPRI access and reads the CPRI's state register. CPRI status includes normal operation (no warning) and alert state such as LOS alert, LOF alarm.

(32) 4. Optical Loss Calculation Block

(33) This block computes the optical path attenuation from BBU to RRU and the optical path attenuation from RRU to BBU according to formula (1).

(34) 5. Analysis and Error Warning Block

(35) After having information about the state of CPRI, optical power of SFP and optical loss on the transmission line, this block performs analysis and makes conclusions according to Table 1.

(36) The configuration of the system applying the AWOT method is listed in Table 4.

(37) TABLE-US-00004 TABLE 4 Table of experimental system parameters Parameters Value CPRI speed 6,144 Gbps Fiber length 1000 m Fiber type G.652.A SFP type Finisar FTLF1326P3BTL, wave length 1310 nm

(38) Specifically, when deploying the system, we execute the following experiments:

(39) Experiment 1: using SFP and good quality optical wire. As shown in FIG. 4, the program running on BBU retrieves information from the system applying the AWOT method and prints the information on the BBU operation window. The printed information is numbered 1 to 5 corresponding to the steps taken by the AWOT method. Note that the actual optical power value of SFP on the BBU is the line starting with the word “Value”. It can be seen that FIG. 4 is the result of AWOT method implementation in case of good quality optical connection, AWOT system issue OPT_CONN_NORMAL message.

(40) Experiment 2: using broken SFP for BBU. As shown in FIG. 5, the SFP's transmitting optical power is at the fault threshold, the AWOT method issues warning error code OPT_SFP_BBU_BROKEN.

(41) Experiment 3: Using damaged optical wires. As shown in FIG. 6, the obtained optical power of SFP on the RRU is very small compared to the optical power emitted by the SFP on the BBU, i.e. the optical wire directed from the BBU to the RRU has a large attenuation, the AWOT method gives warning. error codeOPT_CABLE_BROKEN.

(42) Experiment 4: using failed SFP for RRU. As shown in FIG. 7, the obtained optical power of SFP on BBU is at fault threshold, BBU cannot connect to RRU. The AWOT method then gives an error code warningOPT_CONN_ERROR_1.

(43) Thus, when applying AWOT method, the status of optical connection between BBU and RRU is reported accurately and quickly.

EFFECTIVENESS OF THE INVENTION

(44) The method of automatic analysis and warning of optical connection status between BBU unit and RRU of radio base station according to the patent is easy to apply and highly effective. The AWOT method according to the invention has solved the problem of finding the cause of the optical connection failure accurately and quickly. From there, it reduces the cost of labor and equipment, and at the same time, reduces the time lost telecommunications network service.