Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
2001-06-12
2004-06-15
Chin, Vivian (Department: 2682)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S456100, C455S450000, C455S452200, C455S509000, C370S335000, C370S230000
Reexamination Certificate
active
06751465
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radio communication permission control system which carries out an access permission control when one of communication terminals such as portable phones accesses a reception apparatus such as a base station for communication start.
2. Description of the Related Art
A communication apparatus using a mobile communication terminal such as a portable phone becomes popular rapidly. Especially, attention is recently paid to the communication :apparatus of the CDMA (code division multiple access) communication system which is difficult to undergo influence of noise and interference from other signals by using the spectrum spreading technique. The mobile terminal such as a portable phone adopts a cell system to attempt the effective use of a frequency band, and a channel is allocated to the mobile terminal in each cell.
By the way, the number of channels possible to be allocated in one cell, that is, the number of communicable mobile terminals which can communicate and call at a time is finite. Therefore, as a typical example, the number of mobile terminals which request communication at a time in one cell exceeds the permissible number of communication terminals in some probability. In such a case, the phenomena will occur in which it is not possible to connect with a base station regardless of requests of communication.
FIGS. 1A and 1B
show a random access channel (RACH) system for the channel acquisition and it is used in a part of the communication terminals of the CDMA communication system. In the system shown in these figures, a random access channel system is used for an upward link channel from the mobile terminal to the base station. The communication terminal (not shown) requesting the communication outputs a preamble signal
11
composed of a predetermined code sequence as shown in
FIG. 1A
at the time when trying to start communication. When receiving the preamble signal
11
, the base station (not shown) replies an ACK (affirmative) signal
12
to the mobile terminal as shown in
FIG. 1B
, when permitting the communication. The base station replies a NACK (negative) signal when the base station does not permit the communication, although it is not illustrated. The mobile terminal receives the ACK signal
12
and start the communication and outputs a message section
13
having transmission data as the content as shown in FIG.
1
A.
In this way, in the random access channel system, the preamble signal
11
is used as a signal requesting message section
13
. In other words, the message section
13
itself is common to all the mobile terminals, and the signal used for each mobile terminal to request a use right of the message section
13
to the base station is the preamble signal
11
.
The number of message sections
13
which the base station can allocate in one cell is finite. Therefore, as described above, a specific mobile terminal transmits the preamble signal
11
once again, if still requesting the communication when the specific mobile terminal has transmitted the preamble signals
11
but is not permitted to communicate for the reply of the NACK signal. In such a case, when the communication chances are equally allocated to the mobile terminals which have sent out the preamble signals
11
, the specific mobile terminal is occasionally not given a chance each time. Such a specific mobile terminal must wait for the communication permission for a long time.
For this reason, a proposal is made to eliminate such inequality. For example, in Japanese Laid Open Patent Application (JP-A-2000-32530), a mobile station in a distant place is given an opportunity to transmit under the situation in which the mobile stations in the neighborhood of a base station continuously tries to transmit signals. In this proposal, the mobile terminal on the position where the electric wave is relatively weak can be protected. However, the communication opportunity cannot be given in a higher priority to the mobile terminal in which access is refused regardless of the near and far positions when the accesses compete.
Also, in another proposal, data for specifying the mobile terminal in which a communication request is refused is stored in the base station. When the mobile terminal transmits the preamble signal
11
in the next opportunity, the message section
13
is allocated in,a higher priority to the mobile terminal corresponding to the stored data under the situation where accesses from mobile terminals compete. To realize such a proposal, what data should be stored in the base station is important as the data for specifying the mobile terminal.
As the simplest technique, it will be considered that a unique preamble signal
11
is allocated to every mobile terminal and a code sequence of the preamble signal is stored in the base station as the data for specifying a mobile terminal. For this purpose, it is presupposition that different preamble signals
11
are allocated to the respective mobile terminals separately, as in the phone number. However, such a technique cannot be adopted for all mobile terminals in the communications system. For example, in the communications system which is planed to introduce in every country of the world since 2001, and is called W-CDMA (Wideband Code Division Multiple Access) system, a random access channel system is adopted in the same way. However, the number of kinds of the preamble signal
11
prepared in a same cell (area) is a ten and a few. Therefore, when the mobile terminals more than the number of kinds exist in the same area, the mobile terminal which has transmitted preamble signal
11
cannot be specified by this preamble signal
11
.
In conjunction with the above description, an adaptive array receiving apparatuses disclosed in Japanese Laid Open Patent application (JP-A-Heisei 9-247005). In this reference of the adaptive array receiving apparatus, an adaptive control is turned off for a preamble section (t
2
) of a reception signal and turned on for a data section (t
3
). In order to obtain a sufficient converging time, the reception data are read out twice and the converging operation is carried out for the reading operation. The number of time of repetition of the reading operation is predetermined based on adopted data format length of the system. In this way, an adaptive signal processing section (
7
) extracts only a signal transmitted,:from a specific terminal from among reception signals when the reception signals compete.
Also, a directional control antenna apparatus is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 10-70502). In this reference, the directionality control antenna apparatus has an array antenna which transmits and receives electric wave to a mobile station in its area for a base station. A frequency convert section converts a reception signal of the array antenna into an intermediate frequency signal or a baseband frequency signal and converts a transmission signal of the intermediate frequency signal or the baseband frequency into a transmission frequency signal. The incoming direction estimating section estimates the incoming direction of the electric wave from the mobile station using the output signal from the frequency converting section and estimates the number of stations existing in the area in the direction of the mobile station. The antenna directionality control unit changes the phase and amplitude of the transmission signal or the reception signal and turns the direction of the peak of the directional beam of the array antenna to the direction of the mobile station estimated by the incoming angle estimating section. The reception from the mobile station and the transmission to the mobile station are carried out in a time divisional manner by use of the same directional beams formed by the antenna directionality control unit.
Also, a directional control antenna apparatus is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 11-215049). In this reference, a mobile station has a communica
Chin Vivian
Dao Minh
Foley & Lardner LLP
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