EP2219263A1

EP2219263A1 - Error detection method and apparatus thereof

Info

Publication number: EP2219263A1
Application number: EP09290101A
Authority: EP
Inventors: Martin Dillenburger
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2009-02-12
Filing date: 2009-02-12
Publication date: 2010-08-18
Anticipated expiration: 2029-02-12
Also published as: ATE508491T1; EP2219263B1; DE602009001237D1

Abstract

In a broad aspect, the invention relates to a method for cabling error detection in a base station coupled to an antenna array system, the antenna array system comprising a plurality of antenna elements and a plurality of antenna cables, the antenna cables coupling the base station with the antenna elements. The method comprises: obtaining an antenna parameter of each first and second antenna elements of said antenna array system, said antenna parameter indicating a phase shift between said first and second antenna elements; measuring an overall phase shift between each first and second antenna elements; and calculating said sum of phase shifts of each first and second antenna cables by subtracting said antenna parameter of said first and second antenna elements from said overall phase shift of said first and second antenna elements. The method further comprises: obtaining at least two results of a phase shift of at least said first antenna cable by combining different sums of phase shifts of said first and second antenna cables; comparing said two results of said phase shifts of each first antenna cable; and detecting cabling error if said two results differ by any value except 0 or PI.

Description

Field of the invention

The invention relates to a method for cabling error detection in a base station of a mobile communication system, and to a base station.

Background and related art

An antenna array is formed of multiple antenna elements coupled to a common source in order to produce a directive radiation pattern. The spatial relationship between the antenna elements further contributes to the directivity of the antenna as well.
In the antenna arrays, the groups of antennas is built so that the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in an undesired direction. The antenna array system can be used, for example, to transmit one or more beams onto one or more different directions.

Summary of the invention

In a broad aspect, the invention relates to a method for cabling error detection in a base station coupled to an antenna array system, the antenna array system comprising a plurality of antenna elements and a plurality of antenna cables, the antenna cables coupling the base station with the antenna elements. The method comprises: obtaining an antenna parameter (Smn) of each first (n) and second (m) antenna elements of the antenna array system, the antenna parameter indicating a phase shift between the first and second antenna elements; measuring an overall phase shift (Anm) between each first and second antenna elements, wherein the overall phase shift (Anm=Snm+Cn+Cm) equals the antenna parameter (Smn) of the first and second antenna elements plus a sum of phase shifts (Cn + Cm) of first and second antenna cables, the first and second antenna cables coupling the first and second antenna elements to the base station respectively; and calculating the sum of phase shifts of each first and second antenna cables by subtracting the antenna parameter (Snm) of the first and second antenna elements from the overall phase shift (Anm) of the first and second antenna elements.
The method further comprises: obtaining at least two results of a phase shift of at least the first antenna cable by combining different sums of phase shifts of the first and second antenna cables; comparing the two results of the phase shifts of each first antenna cable; and detecting cabling error if the two results differ by any value except 0 or PI.
An advantage of the embodiment is that an automatic and early detection of the cabling error, avoids the need of a manual check by unnecessarily reaching the high antenna mounting conditions. Another advantage of the embodiment is that when the cabling errors are correctly positioned after cabling error detection, this will improve the accuracy in the transmission of the beams and the construction of the radiation pattern.
In accordance with an embodiment, the method further comprises: obtaining a third result of the phase shift of at least the first antenna cable, wherein no cabling error is detected if a first and a second result of the two results are equal or differ by PI and if the third result differs by zero or pi.
In accordance with an embodiment, the antenna parameter represents phase shift between pairs of the antenna array elements.
In accordance with an embodiment, no cabling error is detected if the first and the second result differ within a margin error.
In accordance with an embodiment, the antenna elements of the antenna array system are connected to a base station via antenna cables of different lengths.
In accordance with an embodiment, the base station uses a calibration algorithm for compensating the different cable lengths by calculating the phase shift for each antenna cable.
In accordance with an embodiment, the antenna array system transmits a plurality of beams. In accordance with an embodiment, the antenna array system is an adaptive antenna system.
In accordance with an embodiment, the cabling error occurs when first and second antenna cables are twisted.
In another broad aspect, the invention relates to a base station in a communication network, the base station coupled to an antenna array system, the antenna array system comprising a plurality of antenna elements and a plurality of antenna cables, the antenna cables coupling the base station with the antenna elements, the base station comprising:

a module for obtaining an antenna parameter (Smn) of each first (n) and second (m) antenna elements of the antenna array system. The antenna parameter indicates a phase shift between the first and second antenna elements;
a module for measuring an overall phase shift (Anm) between each first and second antenna elements. The overall phase shift (Anm=Snm+Cn+Cm) equals the antenna parameter (Smn) of the first and second antenna elements plus a sum of phase shifts (Cn + Cm) of first and second antenna cables. The first and second antenna cables couple the first and second antenna elements to the base station respectively. The first and second antenna elements represent all pair combination of antenna elements of the antenna system;
a module for calculating the sum of phase shifts of each first and second antenna cables by subtracting the antenna parameter (Snm) of the first and second antenna elements from the overall phase shift (Anm) of the first and second antenna elements. The calculation is the result of solving the formula of the overall phase shift, and obtaining: Cn+Cm=Anm-Snm.

The base station further comprises:

a module for obtaining at least two results of a phase shift of at least the first antenna cable by combining different sums of phase shifts of the first and second antenna cables;
a module for comparing the two results of the phase shifts of each first antenna cable; and
a module for detecting cabling error if the two results differ by any value except 0 or PI.

In accordance with an embodiment, the base station further comprises:

a module for obtaining a third result of the phase shift of at least the first antenna cable, wherein no cabling error is detected if a first and a second result of the two results are equal or differ by PI and if the third result differs by zero or pi.

Brief description of the drawings

In the following preferred embodiments of the invention will be described in greater detail by way of example only making reference to the drawings in which:

Figure 1: shows an embodiment of a base station coupled to an antenna array system,
Figure 2: shows an embodiment of the antenna parameters of an antenna array system,
Figure 3: shows an example of a cabling error in the cables that couple the base station with the antenna elements of the antenna array system,
Figure 4: shows an embodiment of a method for detecting cable error,
Figure 5: shows an example of the calculation of the overall phase shift and the calculation of the sum of phase shifts,
Figure 6: shows an example of the calculation of the phase shift of the antenna cables and the comparison between the results of the phase shifts.

Detailed description

Fig. 1 shows a block diagram 100 of a telecommunication system comprising a base station 101, a plurality of antenna cables 102, and an antenna array system 103. The plurality of cables 102 has different lengths and the phase shift of each cable is initially unknown. Therefore, the base station 101 compensates the cable length of the plurality of cables 102 by using a calibration algorithm by taking the known antenna parameters of the antenna array system 103 as an input data.
The antenna array system may be for example an adaptive antenna system. The antenna array system may transmit a plurality of beams into different directions.
Fig. 2 shows the details of an antenna array system 200 comprising a plurality of antenna elements 201-204. Each of the antenna elements 201-204 are coupled to a base station through an antenna cable as presented in fig. 1. Each of the cables may have a different length. The antenna array system 200 is able to produce a directive radiation pattern and therefore transmitting a set of beams into different directions.
The antenna parameters of the antenna array system indicate a phase shift between a first and a second antenna element. The antenna parameters are previously known values from each antenna array system. The antenna parameter S₁₂ describes the phase shift between the first antenna element and the second antenna element; the antenna parameter S₁₃ describes the phase shift between the first antenna element 201 and the third antenna element 203. Further, the antenna parameter S₁₄ describes the phase shift between the first antenna element 201 and the fourth antenna element 204; the antenna parameter S₂₃ describes the phase shift between the second antenna element 202 and the third antenna element 203; the antenna parameter S₃₄ describes the phase shift between the third antenna parameter 203 and the fourth antenna parameter 204, and finally the antenna parameter S₂₄ describes the second antenna element 202 and the fourth antenna element 204. All these six antenna parameters are used as inputs in the method of detecting cabling error in the plurality of antenna cables that couple the base station with the antenna array system.
Fig. 3 shows a communication transmitter 300 comprising a base station 301 coupled to a plurality of antenna cables 302 and an antenna array system 303 coupled to a plurality of antenna cables 302. In the block diagram 300, the first cable C1 is twisted with the second cable C2 and therefore they describe an example of a cabling error that may incur in a failure in the transmission of the signal to the antenna array system 303 from the base station 301. An early detection of the cabling error without the need of a manual cable check is highly advantageous due to the high antenna mounting conditions. Further, when the cabling errors are correctly positioned after cabling error detection, this will improve the accuracy in the transmission of the beams and the construction of the radiation pattern.
Fig. 4 shows a flowchart 400 of a cabling error detection method in a base station of a mobile communication system. The mobile communication system comprises a base station coupled to an antenna array system, the antenna array system comprising a plurality of antenna elements and a plurality of antenna cables. The antenna cables coupling the base station with the antenna elements. In a first step 401, the antenna parameter of each first and second antenna elements of the antenna array system is obtained. The antenna parameters indicate a phase shift between the first and the second antenna elements, and these are predefined values obtained, for example, from the antenna array manufacturer. In a second step 402, an overall phase shift between each first and second antenna element is measured. The overall phase shift equals the antenna parameter of the first and the second antenna element plus a sum of phase shifts of first and second antenna cables. The first and second antenna cables couple the first and second antenna elements to the base station respectively.
In a third step 403 the sum of phase shifts of each first and second antenna cables is calculated. The calculation follows a subtraction of the antenna parameter of the first and second antenna elements from the overall phase shift of the same first and second antenna element.
In a fourth step 404 at least two results of phase shift of all antenna cables are obtained by combining different sums of phase shifts of all antenna cable pairs.
In a fifth step, the two results of the phase shifts of each antenna cable are compared and in a sixth step, the cabling error is detected if the two results differ by any value not equal to 0 or PI.
It is recommendable that the antenna array system comprises at least four antenna elements, and therefore, the plurality of antenna cables should comprise at least four cables, in order to have independent ways to calculate the phase shifts from the phase shift sums (Cn+Cm). If the results of the previous step are equal or differ by PI, a third result of a phase shift of the respective antenna cable has to be obtained. Then, no cabling error is detected if the first and the second results of the two results are equal or differ by PI, and if the third result differs by 0 or PI.
The antenna parameter represents phase shift between pairs of the antenna array elements and under normal circumstances, no cabling error is detected if the first and the second result differ within a margin error.
Fig. 5 shows an example of the possible calculations to obtain the overall phase shift 501 and the sum of phase shift of the first and the second antenna elements 502. As it was previously explained, the overall phase shift of between each first and second antenna element is measured by the base station. Also, the antenna parameters of each first and second antenna elements are obtained as predefined values. In the formulas of the overall phase shift 501, the Anm represent the measured overall phase shift value and Snm represents the antenna parameters.
Therefore, as the overall phase shift equals the antenna parameter of the first and second antenna elements plus the sum of the phase shifts of the first and the second antenna cables (Cn+Cm), the sum of the phase shifts of each first and second antenna cable are calculated, as shown in the formulas of 502.
If for example four antenna cables couple the base station with the antenna array system, where the antenna array system comprises four antenna elements, six sums of phase shifts of first and second antenna elements are obtained, each of them describing a different combination of the first and second antenna cables. The results of the sums of the phase shifts of the antenna cables will be combined in order to obtain at least two results of the phase shift of at least a first antenna cable. The two results of the phase shift is obtained by combining the different sums of phase shifts of the first and second antenna cables as represented in 502.
Fig. 6 shows the calculation 601 of three results of the cables phase shifts c1 and c2. By combining the sums of the phase shifts 502, the single antenna cable phase shifts are obtained. On c1a, three different sums of cable shifts containing the single cable phase shifts c1, c2 and c3 is used for obtaining the first result of the cable shift.
The second phase shift c1b result of the same cable length is obtained from the sums of cable phase shifts containing the cable phase shifts c1, c2 and c4. Finally, the third result of the cable phase shift c1c is obtained from the cable phase shifts c1, c3 and c4.
Further, two of the three results of the phase shift of each first antenna cable are compared 602 and a cabling error is detected if the two results differ by any value except 0 or PI. If the two results are equal or differ by PI, a third result of a phase shift is obtained. The third result is compared with the other two results. If the third result is equal to the other two, or differs by PI, no cabling error is detected.

Finally, it is recommendable to obtain the results of the phase shifts of all cables that couple the antenna array system with the base station. In that way, the results of the phase shifts can be compared for each cable, and a cabling error can be detected at any position of the connection between the base station and the antenna array system.

List of reference numerals

100	Block diagram
101	Base station
102	Plurality of antenna cables
103	Antenna array system
200	Antenna array system
201	First antenna element
202	Second antenna element
203	Third antenna element
204	Fourth antenna element
300	Block diagram
301	Base station
302	Plurality of antenna elements
303	Antenna array system
400	Flowchart
401	First step
402	Second step
403	Third step
404	Fourth step
405	Fifth step
406	Sixth step
500	Calculations
501	Overall phase shift calculation
502	Sum of phase shift calculation
600	Phase shift comparison

Claims

A method (400) for cabling error detection in a base station coupled to an antenna array system, the antenna array system comprising a plurality of antenna elements (201,202,203,204) and a plurality of antenna cables, the antenna cables coupling the base station with the antenna elements, the method comprising:
- obtaining (401) an antenna parameter (S₁₂) of each first and second antenna element of said antenna array system, said antenna parameter indicating a phase shift between first and second antenna elements;

- measuring (402) an overall phase shift (501) between each first and second antenna elements, wherein said overall phase shift (501) equals said antenna parameter (Smn) of said first and second antenna elements plus a sum of phase shifts of first and second antenna cables, said first and second antenna cables coupling said first and second antenna elements to said base station respectively;

- calculating (403) said sum of phase shifts (502) of each first and second antenna cables by subtracting said antenna parameter (Snm) of said first and second antenna elements from said overall phase shift (Anm) of said first and second antenna elements;

- obtaining (404) at least two results (601) of a phase shift of at least said first antenna cable by combining different sums of phase shifts of said first and second antenna cables;

- comparing (405) said two results (602) of said phase shifts of each first antenna cable;

- detecting cabling error if said two results differ by any value except 0 or PI.
The method of claim 1 further comprising:
- obtaining a third result (601) of said phase shift of at least said first antenna cable, wherein no cabling error is detected if a first and a second result of said two results are equal or differ by PI and if said third result differs by zero or pi.
The method of claim 1, wherein said antenna parameter (S₁₂) represents phase shift between pairs of said antenna array elements.
The method of claim 2, wherein no cabling error is detected if said first and said second result differ within a margin error.
The method of any of the preceding claims, wherein said antenna elements of said antenna array system are connected to a base station via antenna cables of different lengths.
The method of claim 5, wherein said base station uses a calibration algorithm for compensating said different cable lengths by calculating said phase shift for each antenna cable.
The method of any of the preceding claims, wherein said antenna array system transmits a plurality of beams.
The method of any of the preceding claims, wherein said antenna array system is an adaptive antenna system.
The method of any of the preceding claims, wherein said cabling error occurs when first and second antenna cables are twisted (300).
A base station (101) in a communication network, the base station (101) coupled to an antenna array system (103, 200), the antenna array system (103, 200) comprising a plurality of antenna elements (201, 202, 203, 204) and a plurality of antenna cables (102), the antenna cables coupling the base station (101) with the antenna elements (201, 202, 203, 204), the base station comprising:
- means for obtaining an antenna parameter (Smn) of each first (n) and second (m) antenna elements of said antenna array system, said antenna parameter indicating a phase shift between said first and second antenna elements;

- means for measuring an overall phase shift (Anm) between each first and second antenna elements, wherein said overall phase shift equals said antenna parameter (Smn) of said first and second antenna elements plus a sum of phase shifts of first and second antenna cables, said first and second antenna cables coupling said first and second antenna elements to said base station respectively;

- means for calculating said sum of phase shifts of each first and second antenna cables by subtracting said antenna parameter (Snm) of said first and second antenna elements from said overall phase shift (Anm) of said first and second antenna elements;

- means for obtaining at least two results of a phase shift of at least said first antenna cable by combining different sums of phase shifts of said first and second antenna cables;

- means for comparing said two results of said phase shifts of each first antenna cable;

- means for detecting cabling error if said two results differ by any value except 0 or PI.
The base station of claim 10 further comprising:
- means for obtaining a third result of said phase shift of at least said first antenna cable, wherein no cabling error is detected if a first and a second result of said two results are equal or differ by PI and if said third result differs by zero or pi.
The base station of claim 10, wherein no cabling error is detected if said first and said second result differ within a margin error.
The base station of claim 10, wherein said base station uses a calibration algorithm for compensating said different cable lengths by calculating said phase shift for each antenna cable.
The base station of claim 10, wherein said antenna elements of said antenna array system are connected to a base station via antenna cables of different lengths.