CDMA mobile station and CDMA transmission method

Details CDMA mobile station and CDMA transmission method CDMA mobile station and CDMA transmission method

1999-03-16

2002-10-15

Chin, Wellington (Department: 2664)

Multiplex communications

Communication over free space

Combining or distributing information via code word channels...

C370S503000, C455S522000, C455S574000

Reexamination Certificate

active

06466563

ABSTRACT:

TECHNICAL FIELD
The present invention relates to CDMA mobile station apparatuses and CDMA transmission methods such as digital car telephones and portable telephones used for cellular radio communication systems.
BACKGROUND ART
For radio communication systems such as digital car telephones and portable telephones, a multiple access system is used in which multiple mobile station apparatuses perform communications with a single base station apparatus simultaneously. Recently, as one of these line switching systems using this multiple access system, a CDMA (Code Division Multiple Access) system is used because of its high frequency utilization efficiency.
Data transmission timing in a conventional CDMA mobile station apparatus is explained using a timing chart shown in FIG.
1
.
FIG. 1A
is a timing chart showing data transmission timing during data transmission. Pilot symbols (hereafter referred to as “PL”) and transmission power control symbols (hereafter referred to as “TPC”) are periodically inserted into data, forming a frame. When a portion from the start of a PL to the start of the next PL is calculated as one slot, one frame generally consists of 16 slots, 10 ms.
FIG. 1B
is a timing chart showing data transmission timing during transmission on transmission standby. “During transmission on transmission standby” means a time corresponding to less than K frames after completion of data transmission or a time corresponding to less than L frames in which a CRC detection of received data resulted in NG (K and L are predetermined constants). On transmission standby, the CDMA mobile station apparatus transmits burst data in which only a PL and TPC are written and other bits are left in blank for each slot.
Here, the CRC (Cyclic Redundancy Check) detection means processing for detecting errors in received data by judgment by a comparison between a received CRC bit which is given with a coefficient of a remainder polynomial obtained by dividing an information bit by an n-th degree generating function, and a CRC bit generated from the received data. A complete match between the two means that the received data have been received correctly (OK) and mismatch of at least one element means that the received data contain errors (NG).
FIG. 1C
is a timing chart showing the data transmission timing at the end of transmission. The end of transmission means a state in which at least K frames are detected after data transmission is completed and at least L frames in which a CRC detection of the received data resulted in NG are detected.
As shown in
FIG. 1C
, the conventional CDMA mobile station apparatus stops transmission of burst data in a certain time after the end of communication in order to reduce power consumption of batteries by a transmission amplifier.
Because of this, the conventional CDMA mobile station apparatus above takes time to establish synchronization when restarting communication, and it has to send a dummy signal, an unnecessary signal, instead of data in the meantime until synchronization is established, resulting in a problem of reducing the transmission efficiency.
DISCLOSURE OF INVENTION
A first objective of the present invention is to provide a CDMA mobile station apparatus and CDMA transmission method which can maintain established synchronization with a base station apparatus while reducing power consumption when there are no data to be transmitted.
This objective is achieved by controlling the transmission interval of burst data to N slots (N: a natural number) when a certain time has elapsed after the end of data transmission.


REFERENCES:
patent: 5896374 (1999-04-01), Okumura et al.
patent: 6034952 (2000-03-01), Dohi et al.
patent: 6088324 (2000-07-01), Sato
patent: 6144860 (2000-11-01), Komatsu
patent: 8-008871 (1996-01-01), None
“Experiment On Transmission Of Mobile Radio Access Using Coherent Multicode DS-CDMA”, Technical Report of IEICE, RCS95-80, dated Oct. 20, 1995 with English Abstract.
English language abstract of JP 8-008871.

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