Code division multiple access (CDMA) communication system

• US 20040252668A1
• Filed: 05/28/2004
• Published: 12/16/2004
• Est. Priority Date: 06/30/1995
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Jacques, Alexander, Kowalski, John, Ozukturk, Fatih, Lomp, Gary
• Granted Patent: US 7,903,613 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/70753 Partial phase search
• CPC Class Codes: H04B 1/70754 Setting of search window, i.e. range of code offsets to be searched H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/70755 Setting of lock conditions, e.g. threshold
• CPC Class Codes: H04B 1/70758 Multimode search, i.e. using multiple search strategies
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 1/7183 Synchronisation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects
• CPC Class Codes: H04B 2201/7071 with dynamic control of receiver resources
• CPC Class Codes: H04B 7/2637 for logical channel control
• CPC Class Codes: H04B 7/264 for data rate control
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/0077 Multicode, e.g. multiple codes assigned to one user
• CPC Class Codes: H04J 13/10 : Code generation
• CPC Class Codes: H04J 2013/0037 : Multilevel codes
• CPC Class Codes: H04L 1/004 : by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0059 : Convolutional codes
• CPC Class Codes: H04L 2027/003 : at baseband only
• CPC Class Codes: H04L 2027/0053 : Closed loops
• CPC Class Codes: H04L 25/0212 : of impulse response
• CPC Class Codes: H04L 27/206 : using a pair of orthogonal carriers, e.g. quadrature carriers
• CPC Class Codes: H04L 27/2332 : using a non-coherent carrier
• CPC Class Codes: H04W 52/08 : Closed loop power control
• CPC Class Codes: H04W 52/146 : Uplink power control
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/241 : taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/245 : taking into account received signal strength
• CPC Class Codes: H04W 52/247 : where the output power of a terminal is based on a path parameter sent by another terminal
• CPC Class Codes: H04W 52/26 : using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/322 : Power control of broadcast channels
• CPC Class Codes: H04W 52/325 : Power control of control or pilot channels
• CPC Class Codes: H04W 52/343 : taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 : distributing total power among users or channels
• CPC Class Codes: H04W 52/36 : with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/44 : in connection with interruption of transmission
• CPC Class Codes: H04W 52/50 : at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 52/52 : using AGC [Automatic Gain Control] circuits or amplifiers
• CPC Class Codes: H04W 52/54 : Signalisation aspects of the TPC commands, e.g. frame structure
• CPC Class Codes: H04W 52/60 : using different transmission rates for TPC commands

Abstract

A subscriber unit for use in a multiple access spread-spectrum communication system includes a spread spectrum radio interface, responsive to a rate function signal from a base station, and first and second despreaders. The base station assigns the rate function spread-spectrum message channels and the first despreader recovers and modifies an information signal one of the spread spectrum message channels. The information channel mode is then modified for processing by the second despreader, with the second despreader supporting a different information signal rate. The subscriber unit has a capability of communicating with a dynamically changing a transmission rate of an information signal which includes multiple spread spectrum message channels. The system includes a closed loop power control system for maintaining a minimum system transmit power level for a radio carrier station and the subscriber units, and system capacity management for maintaining a maximum number of active subscriber units for improved system performance.

Claims

1. A subscriber unit for use in a multiple access spread-spectrum communication system, the subscriber unit comprising:

a spread spectrum radio interface, responsive to a rate function signal from a base station, wherein the base station assigns the rate function ones of a plurality of spread-spectrum message channels;

a first despreading means for recovering a respective information signal and modifying signal from a first one of the spread spectrum message channels; and

information channel mode modification means responsive to the rate function signal for reassigning an output of the first despreading means to a second despreading means which supports the different information signal rate, the second despreading means corresponding to a second spread spectrum message channel, whereby the subscriber unit has a capability of communicating by dynamically changing a transmission rate of an information signal transmitted to a subscriber through a first spread-spectrum message channel of the plurality of spread spectrum message channels.

2. The subscriber unit according to claim 1 further comprising:

means for synchronizing a message according to sequential sub-epoch boundaries of the plurality of spread spectrum message channels; and

means for sending the information signal through the first spread spectrum message channel prior to one of the sub-epoch boundaries and for sending the information signal through the second spread spectrum message channel to the substantial exclusion of the first spread spectrum message channel subsequent to the sub-epoch boundary.

3. The subscriber unit according to claim 1 wherein:

the rate function signal corresponds to a dynamically changed transmission rate of an information signal received from a remote processing unit and an identification of an information signal rate of the respective information signal; and

the rate function signal comprises a modify signal corresponding to the information signal rate.

4. The subscriber unit according to claim 3 comprising the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels.

5. The subscriber unit according to claim 3 comprising:

the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels; and

information channel mode modification means responsive to the modify signal for switching the respective information signal from the first spread-spectrum message channel supporting a first information channel rate to one other spread-spectrum message channel, the one other spread-spectrum message channel having a different information channel rate supporting the identified information signal rate.

6. The subscriber unit according to claim 3 comprising:

the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels corresponding to a modify signal response from the base station;

the modify signal corresponding to an information signal rate;

the rate signal corresponding to an identified information signal rate of the respective information signal; and

the information signal and the modify signal assigned to different ones of the plurality of spread-spectrum message channels.

7. A subscriber unit for use in a multiple access spread-spectrum communication system, the subscriber unit capable of communicating by dynamically changing a transmission rate of an information signal transmitted to a subscriber through a first spread-spectrum message channel of a plurality of spread spectrum message channels, the subscriber unit comprising:

a spread spectrum radio interface, responsive to a rate function signal from a base station, wherein the base station assigns the rate function ones of the plurality of spread-spectrum message channels;

a first despreading circuit, the first despreading circuit capable of recovering the respective information signal and modifying signal from the first spread spectrum message channel; and

an information channel mode modification circuit responsive to the rate function signal for reassigning an output of the first despreading circuit to a second despreading circuit which supports the different information signal rate, the second despreading circuit corresponding to a second spread spectrum message channel.

8. The subscriber unit according to claim 7 further comprising:

a synchronization circuit, the synchronization circuit capable of synchronizing a message according to sequential sub-epoch boundaries of the plurality of spread spectrum message channels; and

a circuit sending the information signal through the first spread spectrum message channel prior to one of the sub-epoch boundaries and for sending the information signal through the second spread spectrum message channel to the substantial exclusion of the first spread spectrum message channel subsequent to the sub-epoch boundary.

9. The subscriber unit according to claim 7 wherein:

the rate function signal corresponds to a dynamically changed transmission rate of an information signal received from a remote processing unit and an identification of an information signal rate of the respective information signal; and

the rate function signal comprises a modify signal corresponding to the information signal rate.

10. The subscriber unit according to claim 9 comprising the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels.

11. The subscriber unit according to claim 9 comprising:

the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels; and

an information channel mode modification circuit responsive to the modify signal for switching the respective information signal from the first spread-spectrum message channel supporting a first information channel rate to one other pre-determined spread-spectrum message channel, the one other pre-determined spread-spectrum message channel having a different information channel rate supporting the identified information signal rate.

12. The subscriber unit according to claim 9 comprising:

the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels corresponding to a modify signal response from the base station;

the modify signal corresponding to the information signal rate;

the rate signal corresponding to an identified information signal rate of the respective information signal; and

the information signal and the modify signal assigned to different ones of the plurality of spread-spectrum message channels.

13. A subscriber unit for use in a multiple access spread-spectrum communication system, in which a transmission rate of an information signal transmitted to a subscriber corresponding to the subscriber unit has a dynamically changed transmission rate, the subscriber unit comprising:

synchronization circuitry capable of synchronizing a message according to sequential sub-epoch boundaries of the plurality of spread spectrum message channels; and

a spread spectrum radio interface capable of sending the information signal through the first spread spectrum message channel prior to one of the sub-epoch boundaries and sending the information signal through the second spread spectrum message channel to the substantial exclusion of the first spread spectrum message channel subsequent to the sub-epoch boundary.

14. The subscriber unit according to claim 13 comprising:

the spread spectrum radio interface responsive to a rate function signal from a base station, the rate function assigned to ones of the plurality of spread-spectrum message channels;

a first despreader, the first despreader providing an information signal and modifying signal from the first spread spectrum message channel; and

information channel signal processor, the information channel signal processor modifying the information channel signal in response to the rate function signal for reassigning the signal from the first despreader to a second despreader.

15. The subscriber unit according to claim 14 wherein the second despreader provides an output corresponding to a second spread spectrum message channel.

16. The subscriber unit according to claim 13 comprising:

a circuit receiving a rate function signal which corresponds to a dynamically changed transmission rate of an information signal received from a remote processing unit and an identification of an information signal rate of the respective information signal, wherein the rate function signal comprises a modify signal corresponding to the information signal rate.

17. The subscriber unit according to claim 16 comprising the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels.

18. The subscriber unit according to claim 16 comprising:

the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels; and

information channel mode modification circuit responsive to the modify signal for switching the respective information signal from the first spread-spectrum message channel supporting a first information channel rate to one other pre-determined spread-spectrum message channel, the one other pre-determined spread-spectrum message channel having a different information channel rate supporting the identified information signal rate.

19. The subscriber unit according to claim 16 comprising:

the information signal and the modify signal assigned to respectively different ones of the plurality of spread-spectrum message channels corresponding to a modify signal response from the base station;

the modify signal corresponding to the information signal rate;

the rate signal corresponding to an identified information signal rate of the respective information signal; and

the information signal and the modify signal assigned to different ones of the plurality of spread-spectrum message channels.