Determining distance to source of passive intermodulation product (PIM) in a distributed base station

Patent metadata

Field	Value
Publication number	US-10345438-B2
Application number	US-201715709264-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Sep 19, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A method for determining the distance to source of a passive intermodulation (PIM) product for a distributed base station is provided. The method includes generating a test signal; transmitting the test signal on a front haul communication link between a baseband unit and a remote radio head of the distributed base station; receiving the PIM product as a reflected signal at the remote radio head; multiplying the reflected signal by a conjugate of the test signal to create a sinewave; determining a frequency of the sinewave; and determining the distance to the source of the PIM based on the determined frequency of the sinewave.

First claim

The invention claimed is:

1. A method for determining the distance to a source of a passive intermodulation (PIM) product for a distributed base station, the method comprising:
generating a test signal wherein the test signal comprises a chirp defined by:

chirp
⁡

(
n
)

=

Ae

{

j
⁢

⁢
2
⁢

π
⁡

(

f
t

⁢
n

+

1
2

⁢

mn
2

)

}

with an initial frequency (f t ) that is set to a negative value and a frequency change rate (m) is positive, A is a constant, and n is a discrete time index;
transmitting the test signal on a front haul communication link between a baseband unit and a remote radio head of the distributed base station;
receiving the PIM product as a reflected signal at the remote radio head;
multiplying the reflected signal by a conjugate of the test signal to create a sinewave;
determining a frequency of the sinewave; and
determining the distance to the source of the PIM based on the determined frequency of the sinewave.

2. The method of claim 1 , wherein generating the test signal comprises generating a chirp signal and a continuous wave (CW) signal.

3. The method of claim 1 , wherein generating the test signal includes generating a PN sequence, a Zadoff-Chu sequence or any sequence that shows good correlation properties.

4. The method of claim 1 , wherein transmitting the test signal comprises transmitting the test signal at a high enough power to generated an intermodulation (IM) product in a component of the remote radio head in order to estimate the RRH round trip delay and the delay of the front haul link.

5. The method of claim 1 , wherein determining the distance to the source comprises determining round trip travel time between the remote radio head and the PIM source from the frequency of the reflected signal.

6. A method for determining the distance to a source of a passive intermodulation (PIM) product for a distributed base station, the method comprising:
generating a test signal wherein the test signal comprises a chirp defined by:

chirp
⁡

(
n
)

=

Ae

{

j
⁢

⁢
2
⁢

π
⁡

(

f
t

⁢
n

+

1
2

⁢

mn
2

)

}

with an initial frequency (f t ) that is set to a negative value and a frequency change rate (m) is positive, A is a constant, and n is a discrete time index;
transmitting the test signal on a front haul communication link between a baseband unit and a remote radio head of the distributed base station;
receiving the PIM product as a reflected signal at the remote radio head;
analyzing an Eigen component of the reflected signal; and
determining the distance to the source of the PIM based on the analysis of the Eigen component.

7. The method of claim 6 , wherein analyzing an Eigen component comprises:
multiplying the reflected signal by a conjugate of the test signal to create a sinewave; and
determining a frequency of the sinewave, wherein the distance to the source of the PIM is based on the frequency of the sinewave.

8. A tester for determining the distance from a distributed base station to a source of passive intermodulation (PIM), the tester comprising:
a signal generator configured to be coupled to a front haul communication link between a baseband unit and a remote radio head of the distributed base station, wherein the signal generator is configured to generate a test signal, wherein the test signal comprises a chirp defined by:

chirp
⁡

(
n
)

=

Ae

{

j
⁢

⁢
2
⁢

π
⁡

(

f
t

⁢
n

+

1
2

⁢

mn
2

)

}

with an initial frequency (f t ) that is set to

Assignees

• Commscope Technologies Llc

Inventors

• Gander Martial Germain

Classifications

• G01S11/023 Primary

  using impedance elements varying with distance · CPC title

• H04B17/27

  for locating or positioning the transmitter · CPC title

• H04B17/102

  Power radiated at antenna · CPC title

• H04B17/103

  Reflected power, e.g. return loss · CPC title

• H04B17/0085

  using test signal generators · CPC title