Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-11-04
2001-03-06
Vo, Nguyen (Department: 2745)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S008000, C455S446000, C455S067150
Reexamination Certificate
active
06198918
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention relates to a method and apparatus for restoring operation to cells within a radiocommunication network after a system disturbance, and more particularly, to a method and apparatus for scheduling recovery of cells within a radiocommunication network based on the anticipated traffic density within each cell immediately following recovery.
2. Discussion of Related Art
An exemplary cellular radio communication system is illustrated in FIG.
1
. As shown there, a geographic region served by the system is subdivided into a number of cells, each containing a base station. In this exemplary case, there are ten cells C
1
≧C
10
including base stations B
1
-B
10
, respectively. Although the cells are shown as having a hexagonal shape, this is merely a graphical convention; in actuality, the cells may have a variety of “shapes” depending on the terrain covered by the cell and the characteristics of the antenna used by the cell's base station. Although not shown, each cell is also typically divided into a plurality of sectors which are serviced by a respective plurality of base station sector antennas.
Mobile terminals M
1
-M
10
are shown scattered throughout the geographic coverage area encompassed by cells C
1
-Cl
0
. Each mobile terminal typically communicates with its nearest base station, using, for instance, frequencies assigned to that base station. The base stations of adjacent cells use different frequencies so as to reduce interference between neighboring cells. When a mobile terminal moves from one cell to another, the system will transfer any ongoing call to the new cell. Alternatively, in the Code Division Multiple Access (CDMA) protocol (e.g., in the IS-95 standard), all cells share a common wide-band channel. In this protocol, a mobile terminal can simultaneously communicate with plural base stations during handoff from one cell to another.
As illustrated in
FIG. 1
, base stations B
1
-B
10
are coupled to a mobile services switching center (MSC), which provides a connection to a public switched telephone network (PSTN) (not shown), which, in turn, provides connection to various communication devices, such as a telephone handset, terminal, etc. (not shown).
Various safeguards can be taken to ensure the continuity of radiocommunication service provided by the network. Nevertheless, interruptions in service can and do occur. These interruptions may be due to the deliberate actions of a system operator, or may be caused by various system failures. For instance, planned interruptions may be used to perform maintenance on the system or to make upgrades. Failures may be attributed to transmission and other processing errors, power failures, component failures, etc. Whatever the cause, these interruptions result in a temporary blocking of communication services provided by the entire system or parts thereof. In the following discussion, the term “disruption” (or “disturbance”) is used to describe these interruptions in service, which encompasses any type of planned or unplanned interruption in service.
After a disruption, the communication service provided in each cell must be restored. Cells are typically restored sequentially, such that operation is restored to the network on a cell-by-cell basis. (This is because, at the present time, restoring all of the cells at the same time is not feasible, because it would impose a large processing burden on the system.) In one technique, operation is restored to the cells in a random order, such that no cell is given priority over other cells when powering up the cells. In a second technique, cells are restored according to a fixed schedule.
The above-described techniques for restoring operation to the radiocommunication cells have a number of drawbacks. With reference to
FIG. 1
, traffic may differ from cell to cell. For instance, there may be more traffic in cell C
1
than in adjacent cell C
2
because, for instance, cell C
1
corresponds to a heavily populated urban area while cell C
2
corresponds to a more rural area. In the first mentioned technique, power is restored on a random basis, such that any one of cells C
1
-C
10
is powered up first. This means that the busiest cell, C
1
, may not be powered up first. This can result in a loss of revenue for the system operator, since the cell with the greatest potential demand for service (e.g., the potential number of calls) is not necessarily restored first. Also, users of mobile terminals are understandably disturbed when they are unable to initiate or receive calls during a system disturbance. Restoring operation to cells in a random order does not minimize this disturbance, since, again, the cell with the greatest number of potential calls is not necessarily restored first.
The second technique addresses some of these concerns by, for instance, allowing the system to restore power to a cell which serves an urban area before a cell which serves a rural area. Yet this provision may not be enough to account for the complexity in traffic patterns within a coverage area. As mentioned, the exemplary cell C
1
corresponds to an urban area, and therefore may have greater traffic than adjacent rural cell C
2
. However, assume that cell C
1
correspond to a business district within a city which has heavy call traffic during normal working hours, but otherwise has relatively low traffic. Accordingly, cell C
1
may have heavier call traffic than cell C
2
during the middle of the day, but the traffic of cell C
2
might exceed that of cell C
1
at other times. For instance, if cell C
2
included a major roadway into the urban area C
1
, the traffic in cell C
2
could conceivably be higher than the traffic in cell C
1
during “rush” hours. Similar variable density patterns may be present in other cells, which may be attributed to a variety of reasons, including special unpredictable events which result in an entirely anomalous traffic pattern throughout the coverage area. The end result is that it is difficult to predict which cell may be busiest at any moment, making the second mentioned recovery technique also unsatisfactory.
Hence, it is a general objective of the present invention to provide a method and system for re-establishing operation within cells in a more “intelligent” manner so as to provide more efficient management of the radiocommunication system.
SUMMARY
These and other objectives of the present invention are achieved through an “intelligent” technique for restoring operation to a plurality of cells within a wireless communication system after a system disruption based on the anticipated traffic density within each cell immediately following recovery. The anticipated traffic density can be based on prevailing conditions within the system shortly prior to the time that the system disruption occurred.
The technique includes the step of estimating the traffic within each cell to provide a plurality of traffic measurements. These traffic measurements are stored. In the event of a disruption in service, the measurements are accessed. The system then restores operation to cells within the wireless communication system in accordance with the accessed traffic measurements, e.g., such that the cell which had the heaviest traffic immediately before system disruption is restored before other cells. The remaining cells can then be restored in an order based on their traffic levels just prior to the disruption. That is, after the cell with the heaviest traffic is restored, the cell with the second highest traffic is restored, followed by the cell with the third heaviest traffic, etc.
The preferential restoration of cells having the highest anticipated traffic densities maximizes the revenue of the system and minimizes customer dissatisfaction.
REFERENCES:
patent: 5625866 (1997-04-01), Lidbrink et al.
patent: 0 708 573 A2 (1996-04-01), None
patent: WO96/42177 (1996-12-01), None
patent: WO97/24896 (1997-07-01), None
Robin Smith et al., “Distributed Management of Future Global Multi-Service Networks,” British Telecommunications En
Burns Doane Swecker & Mathis L.L.P.
Telefonaktiebolaget LM Ericsson (publ)
Vo Nguyen
LandOfFree
Intelligent cell recovery does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Intelligent cell recovery, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Intelligent cell recovery will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2492421