Multiplex communications – Diagnostic testing – Fault detection
Reexamination Certificate
2000-06-21
2004-07-27
Pham, Chi (Department: 2663)
Multiplex communications
Diagnostic testing
Fault detection
C370S216000, C455S424000
Reexamination Certificate
active
06768719
ABSTRACT:
The present invention relates to a method and apparatus for location of faults in a mobile radio telecommunications system as well as a base station and a network element specially adapted for assisting in the location of faults as well, as a method of operating the base station and the network element.
TECHNICAL BACKGROUND
FIG. 1
is a schematic representation of possible organizations of base station transceivers S, M, MS with respect to a base station controller (BSC)
6
in a cellular radio mobile telephone system. Typically, each base station S
1
-
3
, M
1
-
4
, SM
1
-
9
is connected to the BSC
6
by means of a data telecommunications link
1
-
5
, e.g. a Pulse Code Modulated (PCM) link. There are various ways of arranging the PCM links. One simple way is to connect each base station transceiver S
1
-
3
by means of a single communications link, e.g. a cable or microwave link
2
, directly to the BSC
6
to form a star configuration. Alternative methods include multidrop connections to base station transceivers, e.g. a single multidrop with a linear series of base station transceivers M
1
-
3
connected together by a communications link
4
, or a multidrop configuration in the form a ring of transceivers SM
1
-
9
connected by a communications link
5
which allows the feed to be either anticlockwise or clockwise.
One problem which is particularly marked with the star configuration is the location of faults. A more detailed drawing of such a known base station transceiver (BTS,
10
) is shown in FIG.
2
. BTS
10
is similar in architecture to S2000, S4000 or S8000 indoor or outdoor BTS as supplied by Nortel Networks, Guyancourt, France. The BTS
10
includes a base common function unit (BCF)
11
, a transmitter receiver unit (TRX)
12
and a power supply unit (PSU)
13
. The BCF unit
11
includes a control & switch double board (CSW
1
and CSW
2
)
15
,
16
to manage the BTS
10
, to configure and supervise the other modules in the BTS
10
as well as to control the BTS operations and maintenance requirements. The BCF
11
also includes an alarm circuit
26
and a signaling concentrator
19
. The BCF
11
also provides through the synchronization unit
18
the necessary timing for all the modules in the BTS
10
, e.g. the reference clock for TDM radio signals on the air interface
22
. The BCF
11
also provides conversion of external signals from the BSC to internal signals and vice versa. The PCM interface (DTI)
17
provides control of the incoming signals from, and the outgoing signals to the BSC usually in the form of pulse code modulated (PCM) signaling. The BCF
11
also provides the necessary switching of the PCM slots, in particular, the multiplexing and demultiplexing of the signaling channels between the TRX
12
and the PCM slots.
The TRX
12
provides full duplex operation on the radio interface
22
, e.g. transmission of signals via the transmitter
25
and transmission coupler
27
, amplification of the received radio frequency signals from the air interface
22
via the transmission coupler
27
and receiver
24
and TDMA frame processing in the frame processing unit
23
. Transmission coupler
27
may be a duplexer. Further, TRX
52
may include a second antenna for spatial diversity, the main antenna
28
and the second antenna
29
being connected to the receiver RX
64
via a splitter
21
. Usually, there are several TRX
25
in any transceiver, first of all to provide redundancy and secondly so that at least one TRX may broadcast the beacon or pilot signal which is used by mobile units to locate the cell and to identify the BTS and make contact with it.
Fault situations are summarized in table 1. A fault in the PCM link means that the BTS
10
may be functioning correctly but there is a problem in the cable link from the BSC
6
to the BTS
10
. A major fault in the BTS means that the BTS
10
is not able to set up a PCM link to the BSC
6
despite the fact that the PCM communication link is working correctly. A fault in the TRX means that the transmitter is faulty but this can be alleviated by transfer of the functionality of the affected TRX to another TRX.
TABLE 1
Fault in
Major
Fault
Effect on the
Operations and
PCM
Fault
in
beacon signal
Maintenance
State
link
in BTS
TRX
(BCCH)
recognition
F1
Yes
OFF
?
F2
Yes
ON (other
Event reported
TRX)
F3
Yes
OFF
?
For the state F2 a fault occurs in one of the TRX
25
. This results in the operation of this TRX being taken over by another TRX in the BTS
10
so there is no loss of the beacon signal and no loss of user calls provided the capacity is not exceeded. In states F1 and F3 the PCM signal and information derived therefrom (e.g. timing) is not provided within the BCF
11
. This may result in no beacon signal being propagated and service being lost. The operation and maintenance system (which may be operated by a different entity than the network provider) cannot distinguish between a fault in the DTI
17
and a fault in the PCM connection to the DTI
17
because it is not provided with sufficient information from the network elements such as the BTS
10
and/or the BSC
6
.
Accordingly, when such a fault occurs a crew may be dispatched to test and rectify the fault. This involves going to the BTS
10
in question and determining whether the PCM interfaces
17
, the BCF
11
, and the TRX's are working properly are working correctly and that therefore the fault lies in the PCM connection. This wastes time and is an expensive solution.
GB 2,287,157 describes an operations and maintenance system for a base station transceiver which is connected to a base station controller to provide remote monitoring of the base station transceiver. The remote monitoring uses the PCM link to the base station transceiver so that loss of the PCM link for some reason means simultaneous loss of the remote monitoring facility.
It is an object of the present invention to provide a mobile radio communications system and a method of operating the same which can be reliably identify faults in a communication link to a base station transceiver without requiring an on-site inspection.
SUMMARY OF THE INVENTION
The present invention includes a mobile telecommunications system comprising network having at least one base station transceiver for communication with mobile terminals within a first geographic area; the network being adapted for communicating messages to an from the at least one base station transceiver; the at least one base station transceiver being connected to a first communications link of the network for receipt and transmission of user messages; the at least one base station transceiver being adapted so that when the at least one base station transceiver detects a fault in the first communications link the at least one base station transceiver continues to transmit a beacon or pilot signal; and the network is adapted to monitor activity of the mobile terminals for determination of whether the beacon or pilot signal is being transmitted from the at least one base station transceiver. A resource manager may carry out the monitoring of mobile terminal behavior. The resource manager may be located in a network element such as a base station controller. The mobile terminal activity to be monitored may be attempts by mobile terminals to handover to the at least one base station transceiver or to perform a forward handover from the at least one base station transceiver to another base station transceiver in the system or to perform a call re-establishment with another base station transceiver, or signal strength measurements of beacon signals from the at least one base station transceiver reported by mobile terminals communicating with a base station transceiver other than the at least one base station transceiver. In a CDMA system the mobile terminal activity may be requests for the at least one base station transceiver to be placed on the Active list as this is an indication that the pilot signal is being received.
The present invention also includes a method of operating a mobile telecommunicat
Barnes & Thornburg
Ferris Derrick W
Nortel Networks Limited
Pham Chi
LandOfFree
Method and apparatus for mobile assisted detection of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for mobile assisted detection of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for mobile assisted detection of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3251350