EP0652650A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
CDMA communication with multiplex transmission of data over a wide range from a low to a high rate
Assignee: NTT Docomo Inc
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Filing: 1994-10-31
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Granted: —
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Expires: 2014-10-31
Abstract
Abstract A CDMA communications method capable of multiplex transmission of data over a wide range from a low rate to high rate such as image data without a considerable increase in a circuit scale. A fundamental transmission rate is determined, for example, at 32 kbps, a rate higher than 8 kbps conventionally used. The data whose transmission rate is equal to the fundamental transmission rate is transmitted in frames including no vacant portion. Data whose transmission rate is lower than the fundamental transmission rate (16 kbps, for example) are transmitted in frames including vacant portions. The vacant portions are not transmitted. This makes it possible to receive data through other channels during a time period associated with the vacant portions. Data of a higher transmission rate, 128 kbps, for example, can be multiplexed and transmitted through four channels using different spreading codes.
Inventors
- 👤 Fumiyuki Adachi
- 👤 Mamoru Sawahashi
- 👤 Tomohiro Ntt Tomioka Daiichi Dokushin-Ryo Dohi
- 👤 Shinji Uebayashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 05:49
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/24; H04B7/26; H04B7/2628; H04B7/264
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
122 words
A CDMA (Code Division Multiple Access) communications method for transmitting transmission data through one or more channels between base stations and a mobile station, said method characterized by comprising the steps of: generating a frame including at least a part of said transmission data and a vacant portion when a transmission rate of said transmission data is lower than a predetermined rate, said vacant portion having no data to be transmitted; performing a primary modulation of said frame to produce a primary modulation signal; performing a secondary modulation of said primary modulation signal using a spreading code, to produce a secondary modulated wideband signal, said spreading code being different for each of said channels; and transmitting said wideband signal using a carrier.
Claim 2
Dependent Claim
59 words
The CDMA communications method as claimed in claim 1, characterized in that said step of generating a frame comprises the steps of: predetermining a transmission rate higher than a minimum transmission rate as a fundamental transmission rate; and determining a frame length such that the frame includes no vacant portion when data is transmitted at said fundamental transmission rate.
Claim 3
Dependent Claim
24 words
The CDMA communication method as claimed in claim 2, characterized in that said minimum transmission rate is a rate of transmitting a voice signal.
Claim 4
Dependent Claim
43 words
The CDMA communications method as claimed in claim 2, further characterized by comprising the step of generating a plurality of frames to be assigned to a plurality of said channels when data is transmitted at a rate higher than said fundamental transmission rate.
Claim 5
Dependent Claim
79 words
The CDMA communications method as claimed in claim 1, characterized in that said step of generating a frame comprises the step of time-compressing said transmission data by a factor of N at every time period T (N is an integer greater than one, and T is the length of a frame at said fundamental transmission rate) when the transmission rate of said transmission data is 1/N of said fundamental transmission rate, thereby providing said frame with said vacant portion.
Claim 6
Dependent Claim
71 words
The CDMA communications method as claimed in claim 5, further characterized by comprising the steps of: obtaining said primary modulation signal by receiving a wideband signal associated with one of said channels, and by despreading said wideband signal using a spreading code; and restoring said transmission data by primarily demodulating said primary modulation signal obtained at the step of obtaining, and by time-expanding the demodulation output by a factor of N.
Claim 7
Dependent Claim
80 words
The CDMA communications method as claimed in claim 6, further characterized by comprising the steps of: measuring received power of a common control channel signal transmitted from a base station other than a base station with which the mobile station is communicating, by switching said spreading code during a time period corresponding to said vacant portion in said frame; and deciding during communications a base station to which the communication is to be switched in accordance with said received power.
Claim 8
Dependent Claim
54 words
The CDMA communications method as claimed in claim 6, further characterized by comprising the steps of: receiving common control channel data transmitted from at least one of said base station during a time period corresponding to said vacant portion of said frame by switching said spreading code; and demodulating said common control channel data.
Claim 9
Dependent Claim
73 words
The CDMA communications method as claimed in claim 7, characterized in that said step of generating a frame comprises the step of generating a frame from said transmission data by using a plurality of T/N long portions in said frame, said transmission data having a transmission rate equal to or less than (N-1)/N times of said fundamental transmission rate of said channel, where N is an integer equal to or greater than three.
Claim 10
Dependent Claim
127 words
A CDMA (Code Division Multiple Access) communications apparatus for transmitting transmission data through one or more channels between base stations and a mobile station, said apparatus characterized by comprising: means for generating a frame including at least a part of said transmission data and a vacant portion when a transmission rate of said transmission data is lower than a predetermined rate, said vacant portion having no data to be transmitted; means for performing a primary modulation of said frame to produce a primary modulation signal; means for performing a secondary modulation of said primary modulation signal using a spreading code, to produce a secondary modulated wideband signal, said spreading code being different for each of said channels; and means for transmitting said wideband signal using a carrier.
Claim 11
Dependent Claim
60 words
The CDMA communications apparatus as claimed in claim 10, characterized in that said means for generating a frame comprises: means for predetermining a transmission rate higher than a minimum transmission rate as a fundamental transmission rate; and means for determining a frame length such that the frame includes no vacant portion when data is transmitted at said fundamental transmission rate.
Claim 12
Dependent Claim
24 words
The CDMA communications apparatus as claimed in claim 11, characterized in that said minimum transmission rate is a rate of transmitting a voice signal.
Claim 13
Dependent Claim
42 words
The CDMA communications apparatus as claimed in claim 11, further characterized by comprising means for generating a plurality of frames to be assigned to a plurality of said channels when data is transmitted at a rate higher than said fundamental transmission rate.
Claim 14
Dependent Claim
78 words
The CDMA communications apparatus as claimed in claim 10, characterized in that said means for generating a frame comprises means for time-compressing said transmission data by a factor of N at every time period T (N is an integer greater than one, and T is the length of a frame at said fundamental transmission rate) when the transmission rate of said transmission data is 1/N of said fundamental transmission rate, thereby providing said frame with said vacant portion.
Claim 15
Dependent Claim
72 words
The CDMA communications apparatus as claimed in claim 14, further characterized by comprising: means for obtaining said primary modulation signal by receiving a wideband signal associated with one of said channels, and by despreading said wideband signal using a spreading code; and means for restoring said transmission data by primarily demodulating said primary modulation signal obtained by said means for obtaining, and by time-expanding the demodulation output by a factor of N.
Claim 16
Dependent Claim
81 words
The CDMA communications apparatus as claimed in claim 15, further characterized by comprising: means for measuring received power of a common control channel signal transmitted from a base station other than a base station with which the mobile station is communicating, by switching said spreading code during a time period corresponding to said vacant portion in said frame; and means for deciding during communications a base station to which the communication is to be switched in accordance with said received power.
Claim 17
Dependent Claim
55 words
The CDMA communications apparatus as claimed in claim 15, further characterized by comprising: means for receiving common control channel data transmitted from at least one of said base station during a time period corresponding to said vacant portion of said frame by switching said spreading code; and means for demodulating said common control channel data.
Claim 18
Dependent Claim
72 words
The CDMA communications apparatus as claimed in claim 16, characterized in that said means for generating a frame comprises means for generating a frame from said transmission data by using a plurality of T/N long portions in said frame, said transmission data having a transmission rate equal to or less than (N-1)/N times of said fundamental transmission rate of said channel, where N is an integer equal to or greater than three.
Claim 19
Dependent Claim
45 words
A CDMA communication method in which data representing continuous speech is sampled at a first data rate and data is transmitted at a second data rate, higher than the first data rate, whereby transmission of continuous speech data results in gaps in the transmitted data.
Claim 20
Dependent Claim
46 words
A transmitter for CDMA communication, having means to sample input speech data at a first data rate and means to transmit data at a second data rate higher than the first data rate, whereby transmission of continuous speech data results in gaps in the transmitted data.
Claim 21
Dependent Claim
39 words
A receiver for CDMA communication, having means to receive data at a transmission data rate, and means to decode received data with gaps into data for continuous speech at a speech data rate lower than the transmission data rate.
Claim 22
Dependent Claim
33 words
A CDMA signal carrying continuous voice data at a first data rate in the form of data packets at a second data rate, higher than the first data rate, with gaps between them.
Claim 23
Dependent Claim
60 words
A CDMA communication method comprising transmitting data from a transmitter over a first code-division channel, the said data having gaps arranged in a predictable manner, receiving the data at a receiver, predicting the gaps at the receiver, and during the gaps either receiving data over another code-division channel or searching for another transmitter which can be heard by the receiver.
Claim 24
Dependent Claim
50 words
A transmitter for CDMA communication, having means to transmit data at a first data rate, and means to arrange data for transmission, which data has a data rate below the first data rate, into data at the first data rate with gaps distributed in it according to a predetermined rule.
Claim 25
Dependent Claim
64 words
A receiver for CDMA transmission, having means for decoding data received over a code-division channel at a first data rate, means for identifying that the received data contains gaps and for predicting when gaps will occur, and control means for controlling the receiver to decode data received over a different code-division channel or to search for transmissions from a different receiver during said gaps.
Claim 26
Dependent Claim
37 words
A CDMA signal carrying data at a first data rate in the form of data packets at a second data rate, higher than the first data rate, with gaps provided between packets according to a predetermined rule.
References Cited (Backward Citations)
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