Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-06-11
2001-04-03
Maung, Nay (Department: 2681)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S452200, C370S329000
Reexamination Certificate
active
06212388
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 arising from an application entitled, METHOD AND SYSTEM FOR INCREASING FREQUENCY ASSIGNMENT IN A MOBILE TELECOMMUNICATION SYSTEM, earlier filed in the Korean Industrial Property Office on Jun. 15, 1998, and there duly assigned Ser. No. 1998-22289.
FIELD OF THE INVENTION
The present invention relates to a mobile telecommunication system using a radio frequency channel to provide communication services to a plurality of subscribers. More particularly, the present invention relates to method and system for increasing frequency assignment for multiple communication units by incorporating verification and optimization process, wherein a channel list for the newly added frequency assignment (FA) is distinguished from another channel list for the previously existing frequency assignments (FAs).
DESCRIPTION OF THE RELATED ART
FIG. 1
illustrates a conventional CDMA mobile telecommunication system, and includes a plurality of base transceiver stations (BTSs)
30
,
31
for providing a subscriber with communication service through a mobile station (MS)
40
,
41
, a plurality of base station controllers (BSCs)
20
,
21
for controlling the plurality of BTSs
30
,
31
, and a mobile switching center (MSC)
10
for connecting the plurality of BSCs
20
,
21
to a public switched telephone network (PSTN)
11
.
A cellular mobile telecommunication system makes it possible for more subscribers to communicate with each other by improving the efficiency in the amount of traffic capacity that can be carried in allocated radio spectrum bands. As a demand for cellular service grows, operator of such system attempts to make maximum effective use of the available radio frequency bandwidth in order to accommodate the service demand. A cell division technology is widely used to improve the efficiency in frequency reuse. One of the known cell division technologies is a sectorization. In such a method, a cell is generally divided into three equal parts by spacing three
120
degrees antennas, each sector has only seven channels to achieve optimal traffic capacity while maintaining acceptable signal quality.
Typically, each sector cell operates on either a primary frequency or a secondary frequency, and a mobile station is initially set up to detect for either the primary or secondary frequency, and these frequencies are shared by all the BTS. Each FA has its own codes, different from each other, serving to provide various traffic channels. Thus, as the number of subscribers grow, the BTS (or sector) accommodates more subscribers by incorporating frequency assignment process which attempts to avoid assigning the same frequency to the mobile station.
FIG. 2
represents an illustration of a plurality of frequency assignments (FAs) to which the BTS supports. As illustrated in
FIG. 2
, each sector (&agr;, &bgr;, and &ggr; sector) can support up to maximum of seven FAs. The BTS stores a status report for each of the seven FAs and their frequency values in a program loaded data (PLD), which represents the data relating to system configuration information that is necessary for managing the mobile telecommunication system. If the number of subscribers is added, the BTS provides the mobile station with allocating new frequency assignments that are available for use in accordance with the PLD.
A mobile station within a cell communicates with a BTS via radio channel. A channel being established from the BTS to the mobile station is called a forward channel, and a channel being established from the mobile station to the BTS is called a reverse channel. The mobile station and BTS receive/transmit the voice information and data information with each other through a traffic channel. The forward channel consists of pilot channel, synchronous channel, paging channel and access channel, which are located in the overhead channel.
In the CDMA cellular system, the mobile station and BTS first receive/transmit data from each other via the overhead channel, prior to establishing the communication link. The paging channel transmits system information, and other numerous messages in order to establish a call-setup to the mobile station, which operates within the coverage area of the BTS. The BTS transmits all the system configuration and timing information to the mobile station. Based on this information, the mobile station selects a specific frequency to establish a communication link and to maintain the call. The system configuration information relating to FAs is called channel list message (CDMA_CH_LIST), which contains information to determine whether the communication channel is active within that cell. Further, the channel list message can be transmitted periodically, or instantaneously transmitted whenever a new FA is added or deleted.
The process of generating the channel list by the BTS is described as follow: The BTS generates the channel list, which contains system information relating to each FA, based on the information stored in the PLD. The PLD includes a database and a look up table associated with prior events and current status for each FA, and also includes St_CDMA_Id_Num_Map_Data and St_CDMA_Ch_Config_BTS.
St_CDMA_Id_Num_Map_Data includes a frequency value for the each frequency assignment in the unit of MHz. St_CDMA_Ch_Config_BTS includes data corresponding to an attempt mode (or state) or an acknowledgement mode (or state) corresponding FA. The attempt mode of FA indicates an inactive state wherein the mobile station ignores the channel list message and thus not able to establish the communication link within a cell on a particular channel, and the acknowledgement mode indicates state wherein the mobile station accepts the channel message and thereby the communication link within a cell is established (or active) on a particular channel.
St_CDMA_Ch_Config_BTS also includes various types of channel number information for each frequency assignment. It contains information relating to the discreet location of various frequencies such as such as primary, second, and normal. In accordance with what type of channel data and the location of frequency on the channel list, it can be determined as to whether the operator is using which specific channel.
After determining the acknowledgement status of FA and the active status of each sector, the frequency value corresponding to that particular sector can be derived from the PLD. Then, a channel list can be generated to include the determined frequency value, and this generated channel list is transmitted to a mobile via normal paging channel element (PCE). Accordingly, the mobile station can now know the status of each sector and the FA using the channel list.
FIG. 3
shows an example illustrating the channel list showing the status of frequency assignment of each sector. As illustrated in
FIG. 3
, it is possible to understand that &agr; sector (
1
), &bgr; sector (
2
) and &ggr; sector (
3
) are all normal and
1
FA and
2
FA are allowed to be operated. The frequency value of the
1
FA is 100 MHz and the frequency value of the
2
FA is 200 MHz. The rest FAs are all set to 0 (‘zero’), and the mobile station will interpret them as being out of service (OOS).
The mobile station, by receiving the channel list generated as stated above, can know the information regarding first two FAs in the corresponding area. Accordingly, the mobile station will perform a call attempt, and maintains the communication by selecting either one of the two FAs that are in service.
When a new FA is added, the BTS managing the current channel list generates another new channel list to reflect the newly added FA.
FIG. 4
shows a flow chart illustrating a conventional method for generating a new channel list when a new FA is added. If a new FA is added (s
110
), the BTS generates a new PLD reflecting the new FA per each sector (s
120
). Then, referring to the PLD of the BTS, it is determined for which channel number of the new FA is established as eithe
Cha Steve
Klauber & Jackson
Maung Nay
Samsung Electronics Co,. Ltd.
Vuong Quochien
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