Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-11-13
2001-10-02
Kincaid, Lester G. (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S454000, C455S515000, C455S166100, C455S185100
Reexamination Certificate
active
06298236
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a cellular telephone network. More specifically, it relates to a method of use of a wireless control channel in a microcellular system.
BACKGROUND OF THE INVENTION
In a representative zone structure for a cellular communication system, such as is illustrated in
FIG. 3A-3C
, a repeating pattern is formed with a number of hexagonal cells or zones; e.g., four cells in
FIG. 3A
, seven cells in
FIG. 3B
, and 12 cells in FIG.
3
C. In each cell pattern, the same control channel, or number of control channels, is allotted to each cell having the same designation (in this instance, the same digit
1
-
12
) assigned thereto. No two adjacent cells are assigned the same designation and control channels, in order to avoid the effects of local interference. The number of control channels allotted to each cell is pre-assigned in a fixed manner.
For a microcellular system (MCS), it has been usual to allot control channels for each service area in a fixed manner, similar to the system employed for an ordinary cellular system described above. However, when applying the standard control channel allotting method to an MCS, problems are encountered. For example, it is difficult to arrange cells in an MCS in a regular manner, such as the hexagonal layout shown in FIGS.
3
A-
3
C, and is correspondingly difficult, therefore, to allot control channels in a fixed manner. Furthermore, since the number of zones to be covered differs greatly for each MCS, there are many cases in which the number of channels required must be changed for each such system. A mobile unit seeking to obtain service in one of a plurality of MCS's must, consequently, store information relating to all of the control channels which might be used and must search all of the stored control channels in order to find the control channels allotted to the local MCS for each use. The time involved in such searching significantly inhibits usage of a mobile unit.
It is, therefore, an objective of the present invention to provide a method of use of a control channel in an MCS in which a required control channel or channels may be arbitrarily selected depending upon the conditions under which the MCS is to be used.
It is a further objective of the invention to provide a method of use of a control channel whereby a mobile unit can locate a control channel for the MCS in a minimum search time.
SUMMARY OF THE INVENTION
These and other objectives are realized by the present invention wherein a control channel block can be arbitrarily allotted to an MCS according to the conditions under which the MCS is placed for use. The MCS broadcasts its channel block, comprising the control channel(s) allotted to the MCS, on all of the control channels being used by that MCS. A mobile unit seeking access to an MCS initially searches all of the control channels in a stored total channel block in an effort to receive the channel block information which is being broadcasted from the MCS. The mobile unit then compares the received channel block information to the channel block information already stored therein and replaces its memory content with the newly received channel block information, if different from the stored information. All of the channels in a stored channel block are searched in accordance with a predetermined search cycle to locate an available control channel. If the mobile unit is moved and no control channel is identified during a search of the stored channel block, a search is made of the total channel block in an attempt to locate a control channel, preferably at a search cycle which is longer than the pre-determined cycle given the time necessary to conduct the total search.
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Nagamatsu Jun
Terashima Masaki
Yamada Jun
Amster Rothstein & Ebenstein
Kincaid Lester G.
Matsushita Electric Industrial Company Ltd.
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