US5790549A
Expired / Lapsed
US
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Subtractive multicarrier CDMA access methods and systems
Assignee: Ericsson Inc
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Filing: 1996-02-29
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Granted: 1998-08-04
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Expires: 2016-02-29
Abstract
Abstract Apparatuses and methods for practicing subtractive multi-carrier CDMA techniques are disclosed. A channel is divided into a plurality of contiguous subchannels, wherein in each subchannel an amount of spreading is reduced in accordance with the number of subchannels. The channel can be divided into a Plurality of timeslots and a fraction of the total number of conversations sharing the channel can be allocated to each timeslot. A radio communications device, using such a method, can employ one timeslot for transmission and another time slot for reception.
Inventors
- 👤 Paul W. Dent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:24
CPC Classifications
H; H04; H04J; H04J13/00; H04L; H04L5/00; H04L5/0001; H04L5/0014; H04L5/0016; H04L5/0021; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7097; H04B1/7103; H04B1/7107; H04B7/00; H04B7/24; H04B7/26; H04B7/2618; H04J4/00; H04L27/00; H04L27/26; H04L27/2601; H04L5/003; H04L5/0058; H04L5/0073; H04L5/02; H04L5/023; H04L5/026
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
162 words
A method of communicating information between a first station and a plurality of second stations, said method comprising: allocating to each of said plurality of second stations a frequency band containing a first number of subchannels, at least one timeslot in a repeating time-division multiple access frame period, and an access code; modulating information for transmission by said first station to one of said plurality of second stations onto a radio signal using said allocated timeslot, subchannels and access code, wherein each subchannel carries substantially the same information for said one of said plurality of second stations; simultaneously transmitting modulated signals from said first station to said second stations that use a same allocated timeslot and have at least some of said first number of subchannels in common; and receiving said transmissions at said one of said second stations in the at least one allocated timeslot and decoding information intended for said one of said second stations using the allocated access code.
Claim 2
Independent Claim
162 words
A method of communicating information between a first station and a plurality of second stations, said method comprising: allocating to each of said plurality of second stations a frequency band containing a first number of subchannels, at least one timeslot in a repeating time-division multiple access frame period, and an access code; modulating information for transmission by said first station to one of said plurality of second stations onto a radio signal using said allocated timeslot, subchannels and access code, wherein each subchannel carries substantially the same information for said one of said plurality of second stations; simultaneously transmitting modulated signals from said first station to said second stations that use a same allocated timeslot and have at least some of said first number of subchannels in common; and receiving said transmissions at said one of said second stations in the at least one allocated timeslot and decoding information intended for said one of said second stations using the allocated access code.
Claim 3
Dependent Claim
140 words
A receiving system for receiving signals in a designated timeslot using plural radio subchannel frequencies in a designated frequency channel, and a designated access code, said receiving system comprising: antenna means for receiving radio signals; receiver means coupled to said antenna means for filtering and amplifying said received radio signals in said designated frequency channel and converting said received radio signals to a stream of numerical samples; frequency decimation means for processing said numerical sample stream to produce separate sample streams, each separate sample stream being representative of a signal in an associated subchannel, each subchannel having substantially the same information; and subchannel processing means for processing signals in said associated subchannel using said designated access code to separate a wanted signal from unwanted signals having other access codes and to produce output information symbols carried by said wanted signal.
Claim 4
Dependent Claim
140 words
A receiving system for receiving signals in a designated timeslot using plural radio subchannel frequencies in a designated frequency channel, and a designated access code, said receiving system comprising: antenna means for receiving radio signals; receiver means coupled to said antenna means for filtering and amplifying said received radio signals in said designated frequency channel and converting said received radio signals to a stream of numerical samples; frequency decimation means for processing said numerical sample stream to produce separate sample streams, each separate sample stream being representative of a signal in an associated subchannel, each subchannel having substantially the same information; and subchannel processing means for processing signals in said associated subchannel using said designated access code to separate a wanted signal from unwanted signals having other access codes and to produce output information symbols carried by said wanted signal.
Claim 5
Dependent Claim
45 words
The receiving system according to claim 2 wherein said subchannel processing means includes interference reduction means to process an unwanted signal by using its designated access code to reduce an interfering effect when processing said wanted signal using the access code of the wanted signal.
Claim 6
Dependent Claim
23 words
The receiving system according to claim 3 in which said interference reduction means includes means for processing signals in descending signal strength order.
Claim 7
Dependent Claim
23 words
The system according to claim 4 in which the strongest signal first processed is a pilot signal modulated with a fixed access code.
Claim 8
Dependent Claim
27 words
The system according to claim 4 in which the strongest signal first processed is a broadcast control channel signal carrying call alert messages addressed to individual receivers.
Claim 9
Dependent Claim
25 words
The system according to claim 5 in which the second strongest signal is a broadcast control signal carrying call alert messages addressed to individual receivers.
Claim 10
Dependent Claim
72 words
The system according to claim 3 in which said interference reduction means includes: signal transforming means using the access code of a first signal to perform a transform of received signals to a transform domain; nulling means to set a component in said transform domain corresponding to said first signal to zero; and inverse transforming means for using said access code and proceeding to decode a second signal using its access code.
Claim 11
Dependent Claim
15 words
The system according to claim 8 in which said transforming means performs a Walsh-Hadamard transform.
Claim 12
Dependent Claim
15 words
The system according to claim 8 in which said transform domain is the frequency domain.
Claim 13
Dependent Claim
25 words
The system according to claim 10 in which said transform domain component set to zero by said nulling means is a DC or zero-frequency component.
Claim 14
Dependent Claim
31 words
The system according to claim 3 in which said interference reduction means is a joint demodulation means that decodes at least two signals simultaneously using their designated access codes in combination.
Claim 15
Dependent Claim
51 words
A method according to claim 1 including the step of: allocating timeslots for transmission from one of said plurality of second stations to said first station which are offset in time from said at least one timeslot that is allocated for reception by said one of said plurality of second stations.
Claim 16
Dependent Claim
44 words
The method according to claim 1 in which said step of allocating further comprises the step of: selecting a number of said subchannels and timeslots allocated to one of said second stations based on a desired information transmission rate to provide a bandwidth-on-demand capability.
Claim 17
Independent Claim
143 words
A method of communicating information between at least one of a plurality of base stations and at least one of a plurality of mobile stations, said method comprising the steps of: allocating, to each of said at least one of said plurality of mobile stations, a frequency band containing a number of subchannel frequencies; modulating information for transmission by said at least one base station to said at least one mobile station onto a radio signal which includes said subchannel frequencies; transmitting said information-modulated radio signal to said at least one mobile station; receiving said transmission at said at least one mobile station together with signals transmitted to other mobile stations that at least partially overlap in some of said subchannel frequencies; and processing each subchannel using interference-reduction processing to reduce interference in each subchannel separately, each subchannel containing substantially the same information.
Claim 18
Independent Claim
143 words
A method of communicating information between at least one of a plurality of base stations and at least one of a plurality of mobile stations, said method comprising the steps of: allocating, to each of said at least one of said plurality of mobile stations, a frequency band containing a number of subchannel frequencies; modulating information for transmission by said at least one base station to said at least one mobile station onto a radio signal which includes said subchannel frequencies; transmitting said information-modulated radio signal to said at least one mobile station; receiving said transmission at said at least one mobile station together with signals transmitted to other mobile stations that at least partially overlap in some of said subchannel frequencies; and processing each subchannel using interference-reduction processing to reduce interference in each subchannel separately, each subchannel containing substantially the same information.
Claim 19
Dependent Claim
22 words
The method according to claim 15 in which said step of interference-reduction processing further comprises jointly demodulating at least two overlapping signals.
Claim 20
Dependent Claim
39 words
The method according to claim 15 in which said step of interference-reduction processing further comprises demodulating an interfering signal in a subchannel and then subtracting the demodulated, interfering signal before proceeding to demodulate a wanted signal in the subchannel.
Claim 21
Dependent Claim
32 words
The method of claim 15 in which said step of allocating further comprises the step of: allocating frequency bands to mobile stations which are any one of overlapping, partially overlapping and non-overlapping.
Claim 22
Dependent Claim
110 words
A receiver for receiving radio transmissions in which information is modulated onto multiple frequency subchannels within a frequency channel comprising: local oscillator means for generating a local oscillator signal having a frequency which is between frequencies associated with two of said multiple frequency subchannels; quadrature downconversion means for converting a received signal to I and Q quadrature baseband signals using said local oscillator signal; DC offset removal means for processing said I and Q signals to remove unwanted DC offsets therefrom; and A-to-D conversion means for receiving said processed I and Q signals from said DC offset removal means and converting said processed I and Q signals to digital representation.
Claim 23
Dependent Claim
110 words
A receiver for receiving radio transmissions in which information is modulated onto multiple frequency subchannels within a frequency channel comprising: local oscillator means for generating a local oscillator signal having a frequency which is between frequencies associated with two of said multiple frequency subchannels; quadrature downconversion means for converting a received signal to I and Q quadrature baseband signals using said local oscillator signal; DC offset removal means for processing said I and Q signals to remove unwanted DC offsets therefrom; and A-to-D conversion means for receiving said processed I and Q signals from said DC offset removal means and converting said processed I and Q signals to digital representation.
Claim 24
Independent Claim
115 words
A method of communicating information between a first station and a plurality of second stations, said method comprising: dividing an allocated channel bandwidth into a plurality of subchannels, each subchannel having a plurality of timeslots; grouping said plurality of timeslots in each subchannel into a repeating frame structure; allocating to each of said plurality of second stations at least one of said plurality of time slots on at least one of said plurality of subchannels and an access code; assigning, for each of said plurality of second stations, a frame in said repeating frame structure of each subchannel for transmitting overhead information from said first station; and transmitting said overhead information in said assigned frames.
Claim 25
Independent Claim
115 words
A method of communicating information between a first station and a plurality of second stations, said method comprising: dividing an allocated channel bandwidth into a plurality of subchannels, each subchannel having a plurality of timeslots; grouping said plurality of timeslots in each subchannel into a repeating frame structure; allocating to each of said plurality of second stations at least one of said plurality of time slots on at least one of said plurality of subchannels and an access code; assigning, for each of said plurality of second stations, a frame in said repeating frame structure of each subchannel for transmitting overhead information from said first station; and transmitting said overhead information in said assigned frames.
Claim 26
Dependent Claim
16 words
The method of claim 20, wherein said overhead information is slow associated control channel (SACCH) information.
Claim 27
Dependent Claim
31 words
The method of claim 20, wherein said assigned frame for one of said plurality of second stations is different from said assigned frame for another of said plurality of second stations.
Claim 28
Dependent Claim
24 words
The method of claim 20, wherein said frames assigned to each of said plurality of second stations are staggered within said repeating frame structure.
Claim 29
Dependent Claim
32 words
The method of claim 20, wherein said frame assigned to one of said plurality of second station is different for each subchannel allocated to said one of said plurality of second stations.
Claim 30
Dependent Claim
33 words
The method of claim 20, wherein said frame assigned to one of said plurality of second station is the same for each subchannel allocated to said one of said plurality of second stations.
Claim 31
Independent Claim
133 words
A method of communicating information between a first station and a plurality of second stations, said method comprising: dividing an allocated channel bandwidth into a plurality of subchannels, each subchannel having a plurality of timeslots; grouping said plurality of timeslots in each subchannel into a repeating frame structure; allocating to each of said plurality of second stations at least one of said plurality of timeslots on at least one of said plurality of subchannels and an access code; assigning, for each of said plurality of second stations, a frame in said repeating frame structure of each subchannel in which said first station does not transmit to said second station; and transmitting said signals to said second stations in said respective allocated at least one timeslots other than those associated with said assigned frame.
Claim 32
Independent Claim
133 words
A method of communicating information between a first station and a plurality of second stations, said method comprising: dividing an allocated channel bandwidth into a plurality of subchannels, each subchannel having a plurality of timeslots; grouping said plurality of timeslots in each subchannel into a repeating frame structure; allocating to each of said plurality of second stations at least one of said plurality of timeslots on at least one of said plurality of subchannels and an access code; assigning, for each of said plurality of second stations, a frame in said repeating frame structure of each subchannel in which said first station does not transmit to said second station; and transmitting said signals to said second stations in said respective allocated at least one timeslots other than those associated with said assigned frame.
Claim 33
Dependent Claim
26 words
The method of claim 26, wherein said assigned frame is the same frame within said repeating frame structure for each of said plurality of second stations.
Claim 34
Dependent Claim
33 words
The method of claim 26, wherein said assigned frame for at least one of said plurality of second stations is different from said assigned frame for another of said plurality of second stations.
Claim 35
Dependent Claim
22 words
The method of claim 26, wherein said frames assigned to said plurality of second stations are staggered within said repeating frame structure.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-08-03 | 2002-02-02 | 2002-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-08-03 | 2006-02-02 | 2006-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-08-03 | 2010-02-02 | 2010-08-04 | $7700.00 | Window Closed / Lapsed |