Apparatus for making a random access to the reverse common channel of a base station in CDMA and method therefor

Abstract

An apparatus for making a plurality of terminals have a random access to the reverse common channel system in CDMA, comprises code synchronization detection information broadcast means provided in the base station for broadcasting the state information of a channel card in real time for the terminals to recognize the code synchronization detection when the code synchronization of a certain data is acquired through performing the code synchronization of the preambles transmitted from the terminals through the reverse common channel, and data transmission determination, means provided in the terminals for making the terminals to have attempted data transmission in the same time slot with the data of the code synchronization detection continuously transmit data and the other terminals stop data transmission.

Description

[0001]NOTE: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,614,771. The reissue applications are application Ser. Nos. 11 / 218,277, filed Sep. 2, 2005 (the present application), and 11 / 951,939, filed Dec. 6, 2007, which is a continuation reissue application of Ser. No. 11 / 218,277 and is still pending.<?insert-end id="INS-S-00001" ?>BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention concerns an apparatus for making a plurality of cellular phones randomly access a common channel to transmit data in CDMA (Code Division Multiple Access), and a method therefor.[0004]2. Technical Background[0005]Recently, it has been demanded that the mobile communication system may provide data communication services to enable exchanges of moving image and character data together with those of conventional voiced information during movement IMT-2000 (International Mobile Telecommunication-2000) is an international project to dev...

AI Technical Summary

Benefits of technology

[0011]It is an object of the present invention to provide an apparatus for making a plurality of cellular phones randomly access a common channel to transmit data in CDMA, which enables the base station to broadcast a signal representing whether it has acquired the synchronization signal of the data received through the reverse common channel or no, so as to prevent the terminals from unnecessarily transmitting data, thereby avoiding interference signals generated in the reverse common channel.

[0012]It is another object of the present invention to reduce the power used in the terminal to employ an exclusive channel or the reverse common channel to transmit data, and to enable the failed terminal to quickly retransmit data.

[0013]It is still another object of the present invention to provide an apparatus for making a plurality of cellular phones randomly access a common channel to transmit data in CDMA, which may stably perform the code synchronization and the tracking thereof with a preamble of the same length, and achieve reliable data transmission, and reduce the time taken for transmitting data.

[0014]It is further another object of the present invention to enable the base station to broadcast the information concerning the state of the channel card to all terminals in real time so as to prevent the terminals from unnecessarily transmitting data.

Problems solved by technology

Generally, the circuit-switch, which is employed in the present public switched telephone network (PSTN), digital cellular system and personal communication system, is not desirable to make such high speed data transmission because of ineffectively using a limited number of channels.

In this case, it is very ineffective that the packet data is assigned with an exclusive channel as the voiced data.

However, such ALOHA suffers the inefficiency of data transmission performed without any timed schedule between the base station and terminals, and network overloaded due to frequent collision of data transmitted by a number of terminals.

However, since the slotted ALOHA makes the data transmission basically in the contention mode, it is impossible to avoid collisions of data transmitted from the terminals.

Thus, if the synchronization is exactly acquired in the preamble but with an error in transmission of the substantial data, the preamble should be retransmitted reducing the data transmission efficiency.

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