Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-04-28
2001-07-24
Nguyen, Lee (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S067150, C455S067700, C455S226200, C455S522000, C379S021000
Reexamination Certificate
active
06266527
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates generally to telecommunications systems and methods for maintaining voice quality in a wireless network, and specifically to measuring the power and bit error rate on the up-link and down-link channels simultaneously.
2. Background and Objects of the Present Invention
Cellular telecommunications is one of the fastest growing and most demanding telecommunications applications ever. Today it represents a large and continuously increasing percentage of all new telephone subscriptions around the world. Cellular networks have evolved into two different networks. The European cellular network uses the Global System for Mobile Communication (GSM) digital mobile cellular radio system. In the United States, cellular networks have traditionally been primarily analog, but recent advances have been incorporating digital systems within the analog networks. One such North American cellular network is the D-AMPS network, which is described hereinbelow.
With reference now to
FIG. 1
of the drawings, there is illustrated a D-AMPS Public Land Mobile Network (PLMN), such as cellular network
10
, which in turn is composed of a plurality of areas
12
, each with a Mobile Switching Center (MSC)
14
and an integrated Visitor Location Register (VLR)
16
therein. The MSC/VLR areas
12
, in turn, include a plurality of Location Areas (LA)
18
, which are defined as that part of a given MSC/VLR area
12
in which a Mobile Station (MS)
20
may move freely without having to send update location information to the MSC/VLR area
12
that controls the LA
18
.
Mobile Station (MS)
20
is the physical equipment, e.g., a car phone or other portable phone, used by mobile subscribers to communicate with the cellular network
10
, each other, and users outside the subscribed network, both wireline and wireless. The MS
20
may also include a Subscriber Identity Module (SIM) card
13
, or other memory, which provides storage of subscriber related information, such as a subscriber authentication key, temporary network data, and service related data (e.g. language preference).
Each Location Area
12
is divided into a number of cells
22
. The MSC
14
is in communication with a Base Station (BS)
24
, which is the physical equipment, illustrated for simplicity as a radio tower, that provides radio coverage to the geographical part of the cell
22
for which it is responsible.
With further reference to
FIG. 1
, the PLMN Service Area or cellular network
10
includes a Home Location Register (HLR)
26
, which is a database maintaining all subscriber information, e.g., user profiles, current location information, International Mobile Subscriber Identity (IMSI) numbers, and other administrative information. The HLR
26
may be co-located with a given MSC
14
, integrated with the MSC
14
, or alternatively can service multiple MSCs
14
, the latter of which is illustrated in FIG.
1
.
The VLR
16
is a database containing information about all of the Mobile Stations
20
currently located within the MSC/VLR area
12
. If an MS
20
roams into a new MSC/VLR area
12
, the VLR
16
connected to that MSC
14
will request data about that MS
20
from the home HLR database
26
(simultaneously informing the HLR
26
about the current location of the MS
20
). Accordingly, if the user of the MS
20
then wants to make a call, the local VLR
16
will have the requisite identification information without having to reinterrogate the HLR
26
. In the aforedescribed manner, the VLR and HLR databases
16
and
26
, respectively, contain various subscriber information associated with a given MS
20
.
Currently, speech and data are transmitted from the BS
24
to the MS
20
on a down-link channel
30
and from the MS
20
to the BS
24
on an up-link channel
32
. If the power transmitted by the BS
24
on the down-link
30
is too high, in some areas of the cell
22
, e.g., near the corners of the cell
22
, the customer will see a good signal on the MS
20
power meter, but the MS
20
will not be able to access the system, because the up-link
32
power of the MS
20
is not strong enough. In addition, even if the MS
20
can access the system, the speech quality on the up-link
32
is usually poor. Furthermore, in order to reduce co-channel interference, which is the interference caused by the use of the same frequency within two different clusters of cells
22
, the power on the down-link
30
must be minimized.
The BS
24
has two receiver antennas, for diversity, and one transmitting antenna. In certain areas of the cell
22
, the reception on the down-link
30
can be poor, e.g., the bit error rate (BER) is high, because the transmitting antenna is not suitably located for this area of the cell
22
, but, at the same time, the reception on the up-link
32
can be good, e.g., the BER is low, because at least one of the receiving antennas is located satisfactorily with respect to the same area of the cell
22
. Therefore, in order to maintain a system with balance links, e.g., up-link
32
and down-link
30
, both in power and in the BER, the power and BER must be known at each point in the cell
22
for both the up-link
32
and the down-link
30
, simultaneously.
In order to sufficiently analyze the power and BER for the up-link
32
and down-link
30
, a technician must drive the area covered by the cell
22
and compare both in real time and in off-line, the difference between the up-link
32
and the down-link
30
for both the signal strength and the BER. Currently, there are three options for performing these measurements. First, the technician can drive the area and measure only the down-link
30
. However, in this case, the down-link
30
and the up-link
32
can not be compared at every point in the cell
22
. Secondly, the technician can compare the logs from the MSC
14
, which show the reading for both the up-link
32
and the down-link
30
at the same time. However, in this case, the exact location of the MS
20
within the cell
22
is not available. Finally, as discussed in Suutarinen, WO 97-342024, both the up-link
32
and down-link
30
can be measured simultaneously with knowledge of the location, but the setup has to be done in the MSC
14
and two technicians are required: one in the MSC
14
measuring and receiving the power and BER, and one driving the cell
22
with an MS
20
. Thus, the above solutions do not give a real time solution in the field for the drive technician.
It is, therefore, an object of the invention to perform real time measurements in the field of both power and BER for both the up-link and down-link substantially simultaneously.
It is a further object of the invention to allow the power and BER measurements to be performed in the field by one technician.
It is still a further object of the invention to have all of the information, e.g., up-link and down-link power and BER measurements, as well as the geographical location of the mobile terminal, within the mobile terminal itself in order to analyze the system and make decisions more easily, faster and more efficiently.
SUMMARY OF THE INVENTION
The present invention is directed to telecommunications systems and methods for measuring the bit error rate (BER) and power on the up-link and down-link channels substantially simultaneously from the mobile terminal itself. The location coordinates are already stored within the mobile terminal, and therefore, real time analysis can be performed in the field. This can be accomplished by including an application within a memory in the mobile terminal, which can initiate Link Balance (LB) start and stop commands, which are then sent from the mobile terminal to the base station. Alternatively, the mobile terminal can be connected to a laptop computer, which has an application within a memory responsible for instructing the mobile terminal to send the LB start and stop commands. Once the LB start command is received by the base station, the base station measures and calculates the power and BER o
Ericsson Inc.
Jenkens & Gilchrist P.C.
Nguyen Lee
Nguyen Simon
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