Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2001-03-30
2004-10-19
Tran, Congvan (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S062000, C455S067110, C455S439000, C455S452200
Reexamination Certificate
active
06807424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to cellular telephone systems, the making of frequency plan revisions within such systems and, in particular, to the collection of radio environment statistics data, especially downlink data, that is evaluated in connection with the making of such revisions.
2. Description of Related Art
The following background discussion is presented in the context of some of the frequency plan revision procedures taught by U.S. Pat. No. 6,052,593 (hereinafter referred to as the “Guimont Patent”) and U.S. Pat. No. 6,212,386 (hereinafter referred to as the “Briere Patent”). The disclosure of each Patent has been incorporated by reference, and thus only a general, very broad, discussion of these procedures is presented herein in order to provide the reader with sufficient background information useful in understanding certain concerns with these procedures that are addressed by the present invention. For a more detailed understanding of these frequency plan revision procedures, the reader is requested to directly consult the Guimont and Briere Patents, as well as other references discussing operations for manual and automatic frequency planning for cellular telephone networks.
Reference is now made to
FIG. 1
(which is based on
FIG. 2
of the Guimont Patent) illustrating one type of frequency plan revision procedure. In step
100
, radio environment statistics measurements are made with respect to a cell. These measurements, made on a cell by cell basis in accordance with known procedures, include a measurement of the uplink interference with respect to not only selected (i.e., currently used) frequencies for that cell, but also candidate (i.e., not currently used, but available) frequencies for that cell. These measurements further include a measurement of uplink and downlink bit error rate.
Next, in step
102
, analysis is made of the reported radio environment statistics measurements for a given cell. This analysis is typically referred to as an evaluation, and involves the calculation (either manual or automated), with respect to each sub-frequency group containing selected frequencies, and each sub-frequency group containing candidate frequencies, of the average interference and bit error rate values.
In step
104
, the results of the evaluation (step
102
) are used to determine a possible frequency plan reshuffling for a given cell. The determined reshuffling of step
104
typically comprises the removal of certain ones of the selected sub-frequency groups which show unacceptable analyzed radio environment statistics measurements, in favor of a replacement with certain ones of the candidate sub-frequency groups which show acceptable analyzed radio environment statistics measurements. Many reshufflings
104
may be determined and considered before settling in step
106
on one or more of the reshufflings. These chosen reshufflings of step
106
are commonly (and hereinafter) referred to as “proposals” for changes in the frequency plan of the cellular telephone system for a certain cell.
Each of the proposals
106
is next submitted for frequency mode validation in step
110
which determines whether the candidate sub-frequency groups within the proposal for a given cell are valid (i.e., fit) with respect to the current physical configuration (i.e., the number and operating capabilities of the included transceivers) of that cell and in particular its base station.
Next, the frequencies within the candidate sub-frequency groups are hypothetically distributed in step
120
to the transceivers of the current cell configuration. Next, a network validation check is made in step
130
on the proposal
106
to determine whether any adverse consequences to the network might arise from an actual (i.e., physical as opposed to hypothetical) implementation of the proposal.
Approved proposals
106
are then submitted in step
150
for pre-update verification which tests for unacceptable interference by considering both the uplink interference radio statistic measurements previously made in step
100
and currently made mobile assisted handoff (MAHO) downlink interference measurements.
A proposal for a cell which is confirmed through pre-update verification is then implemented in step
160
to effectuate a retune of the transceivers in that cell to the frequencies which were assigned in the automatic frequency assignment process of step
120
.
Reference is now made to
FIG. 2
(which is based on
FIG. 2
of the Briere Patent) illustrating another frequency plan revision procedure. The procedure implements a three-pass operation. A first pass, identified generally by arrow
200
, is referred to as evaluation. The evaluation pass
200
creates one or more revision proposals for one or more cells in response to the consideration of radio environment statistics measurements which report uplink interference measurements and uplink/downlink bit error rate measurements. A second pass, identified generally by arrow
202
, is referred to as pre-update verification. The pre-update verification pass
202
is performed to confirm no more than one proposal for each cell in response to the additional consideration of downlink interference measurements. A third pass, identified generally by arrow
204
, is referred to as post-update verification. The post-update verification pass
204
verifies, following network update in accordance with one of the proposals, that network interference levels following the update are satisfactory.
First, a conventional radio environment statistics recording function is used to collect uplink interference measurements and uplink/downlink bit error rate measurements in step
206
. The evaluation pass
200
processes the measurements to determine proposed frequency plan reshuffling(s) for a given cell. Next, each proposal is validated against certain validation rules relating, for example, to channel allocation and data required for hand-off. An option (step
210
) is then given to request pre-update verification
202
(executed at step
216
) for each of the created proposals (using the step
214
made downlink interference measurements and additional step
206
measurements) to narrow the proposal options to one (best or preferred) proposal per cell. Acceptable proposals are then implemented through a network update retune (step
212
). An option (step
220
) is then given to engage in post-update verification
204
for each of the accepted and implemented proposals. This pass
204
assists the operator in identifying implemented (i.e., deployed) proposals that do not satisfactorily reduce interference and improve network operation. Additional step
214
and step
206
measurements are made and evaluated in step
222
to either (step
224
) confirm the deployed proposal or identify (step
226
) deployed proposals that should be abandoned through a roll-back in step
228
.
Specific attention is now directed to the radio environment statistics measurements (i.e., the data collection efforts) made in connection with frequency revision planning (whether manual or automatic) like those taught above by steps
100
and
150
of
FIG. 1
, and steps
206
and
214
of FIG.
2
. It is important to obtain a sufficient number of data points in order to perform the proposal related calculations (see, for example, the algorithm and particularly step
102
of
FIG. 1
, and the algorithm and particularly steps
208
,
216
and
222
of FIG.
2
). Sufficiency is generally not an issue with respect to those measurements made on the uplink by network base stations. The system can configure the base stations, and the base stations typically have enough resources and available time to collect the right amount of data. With respect to downlink measurements, on the other hand, it has been noticed that in some instances the amount of collected downlink data is insufficient to execute the proposal related calculation algorithm.
The reason for this is related to the fact that the downlink measurements are normally
Jenkens & Gilchrist
Telefonaktiegolaget LM Ericsson (publ)
Tran Congvan
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