System and method for maintaining wireless channels over a reverse link of a CDMA wireless communication system

• US 6,940,842 B2
• Filed: 01/12/2004
• Issued: 09/06/2005
• Est. Priority Date: 12/17/1997
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Tantivy Communications Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr.
• Primary Examiner(s): Qureshi, Afsar
• Application Number:
  US10/755,874
• Publication Number:
  US 20040213176A1
• Time in Patent Office: 603 Days
• Field of Search: 370/208, 370/335, 370/342, 370/441, 370/468, 370/206, 370/209, 370/280, 370/334, 375/142, 375/150, 375/358, 455/450
• US Class Current: 370/335
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• 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 2001/70706 using a code tracking loop, e.g. a delay locked loop
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates
• CPC Class Codes: H04B 2201/70709 with discontinuous detection
• CPC Class Codes: H04B 2201/70715 with application-specific features
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/165 Variable formats
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length
• CPC Class Codes: H04Q 11/0428 Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
• CPC Class Codes: H04Q 2213/13098 Mobile subscriber
• CPC Class Codes: H04Q 2213/13202 Network termination [NT]
• CPC Class Codes: H04Q 2213/13204 : Protocols
• CPC Class Codes: H04Q 2213/13209 : ISDN
• CPC Class Codes: H04Q 2213/13216 : Code signals, frame structure
• CPC Class Codes: H04Q 2213/1327 : Release and resetting of connection
• CPC Class Codes: H04Q 2213/13298 : Local loop systems, access network
• CPC Class Codes: H04Q 2213/13332 : Broadband, CATV, dynamic bandwidth allocation
• CPC Class Codes: H04Q 2213/1336 : Synchronisation
• CPC Class Codes: H04Q 2213/13389 : LAN, internet
• CPC Class Codes: H04W 24/00 : Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/20 : Negotiating bandwidth
• CPC Class Codes: H04W 28/22 : Negotiating communication rate
• CPC Class Codes: H04W 56/00 : Synchronisation arrangements
• CPC Class Codes: H04W 56/0045 : compensating for timing error by altering transmission time
• CPC Class Codes: H04W 56/0075 : based on arrival time vs. expected arrival time
• CPC Class Codes: H04W 72/044 : based on the type of the allocated resource
• CPC Class Codes: H04W 72/0446 : Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/0453 : Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/0466 : the resource being a scrambling code
• CPC Class Codes: H04W 72/21 : in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 74/00 : Wireless channel access
• CPC Class Codes: H04W 74/04 : Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 76/28 : Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: H04W 84/14 : WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

A method for providing wireless communication of digital signals is provided, with the digital signals being communicated between wireless subscriber units and a base station. The digital signals are communicated using at least one radio frequency (RF) channel via Code Division Multiple Access (CDMA) modulated radio signals defined by orthogonal codes. The method includes making available a plurality of orthogonal subchannels within each CDMA RF channel. Available orthogonal subchannels are allocated on an as-needed basis for subscriber units actively sending data. An idling mode connection is provided on a reverse link for subscriber units which are powered on, but not actively sending data, by assigning a shared orthogonal subchannel to at least two different subscriber units, but utilizing different time slots of the shared orthogonal subchannel.

Claims

1. A method for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency (RF) channel via Code Division Multiple Access (CDMA) modulated radio signals defined by orthogonal codes, the method comprising:

making available a plurality of orthogonal subchannels within each CDMA RF channel, each orthogonal subchannel having a data rate less than a nominal data rate of the digital signals;

allocating available orthogonal subchannels on an as-needed basis for subscriber units actively sending data, with the number of orthogonal subchannels being allocated changing during a given session; and

providing an idling mode connection on a reverse link for subscriber units which are powered on, but not actively sending data, by assigning a shared orthogonal subchannel to at least two different subscriber units, but utilizing different time slots of the shared orthogonal subchannel.

2. A method according to claim 1 wherein the different time slots of the shared orthogonal subchannel are uniquely assigned.

3. A method according to claim 2 wherein providing the idling mode connection for each subscriber unit powered on but not actively sending data further comprises sending a heartbeat signal in its uniquely assigned time slot at a data rate that is low enough to maintain bit synchronization with the base station.

4. A method according to claim 2 wherein a subscriber unit enters an active mode from an idling mode by sending a command signal to the base station using its uniquely assigned time slot to request allocation of additional available orthogonal subchannels.

5. A method according to claim 4 wherein each subscriber unit comprises at least one data buffer;

and further comprising each subscriber unit monitoring their at least one data buffer to determine when to send the command signal to the base station.

6. A method according to claim 4 wherein the base station uses a respective forward access channel for each subscriber unit in the active mode;

and further comprising each subscriber unit in the active mode monitoring the forward access channel to determine when to return to the idling mode connection.

7. A method according to claim 6 wherein for each subscriber unit monitoring the forward access channel;

further comprising sending a request to the base station for changing the number of allocated subchannels dedicated to the subscriber unit sending the request.

8. A method according to claim 7 where the number of allocated subchannels is increased;

and wherein the increased allocated subchannels have a predetermined relationship to the uniquely assigned time slot for the subscriber unit sending the request.

9. A method according to claim 4 wherein each subscriber unit comprises at least one data buffer;

wherein the base station uses a respective forward access channel for each subscriber unit in the active mode; and

further comprising each subscriber unit in the active mode monitoring their at least one data buffer to determine when to return to the idling mode connection.

10. A method according to claim 4 wherein each subscriber unit comprises at least one data buffer;

and further comprising each subscriber unit in the active mode monitoring their at least one data buffer to determine when to return to the idling mode connection.

11. A method according to claim 1 wherein each subscriber unit in the idling mode connection receives feedback from the base station relating to an adjustment of its transmit timing.

12. A method according to claim 1 wherein each subscriber unit in the idling mode connection receives feedback from the base station relating to an adjustment of its transmit power.

13. A method for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency (RF) channel via Code Division Multiple Access (CDMA) modulated radio signals defined by orthogonal codes, the method comprising:

making available a plurality of orthogonal subchannels within each CDMA RF channel;

allocating available orthogonal subchannels on an as-needed basis for subscriber units actively sending data, with the number of orthogonal subchannels being allocated changing during a given session; and

providing an idling mode connection on a reverse link for subscriber units in an idling mode and which are powered on, but not actively sending data, by

assigning a shared orthogonal subchannel to at least two different subscriber units, but utilizing different time slots of the shared orthogonal subchannel, and

sending a heartbeat signal from each subscriber unit in the idling mode to the base station in its uniquely assigned time slot at a data rate that is low enough to maintain bit synchronization with the base station.

14. A method according to claim 13 wherein the different time slots of the shared orthogonal subchannel are uniquely assigned.

15. A method according to claim 14 wherein a subscriber unit enters an active state from the idling state by sending a command signal to the base station using its uniquely assigned time slot to request allocation of additional available orthogonal subchannels.

16. A method according to claim 15 wherein each subscriber unit comprises at least one data buffer;

and further comprising each subscriber unit monitoring their at least one data buffer to determine when to send the command signal to the base station.

17. A method according to claim 15 wherein the base station uses a respective forward access channel for each subscriber unit in the active state;

and further comprising each subscriber unit in the active state monitoring the forward access channel to determine when to return to the idling state.

18. A method according to claim 17 wherein for each subscriber unit monitoring the forward access channel;

further comprising sending a request to the base station for changing the number of allocated subchannels dedicated to the subscriber unit sending the request.

19. A method according to claim 18 where the number of allocated subchannels is increased;

and wherein the increased allocated subchannels have a predetermined relationship to the uniquely assigned time slot for the subscriber unit sending the request.

20. A method according to claim 15 wherein each subscriber unit comprises at least one data buffer;

wherein the base station uses a respective forward access channel for each subscriber unit in the active state; and

further comprising each subscriber unit in the active state monitoring their at least one data buffer to determine when to return to the idling state.

21. A method according to claim 15 wherein each subscriber unit comprises at least one data buffer;

and further comprising each subscriber unit in the active state monitoring their at least one data buffer to determine when to return to the idling state.

22. A method according to claim 13 wherein each subscriber unit in the idling state receives feedback from the base station relating to an adjustment of its transmit timing.

23. A method according to claim 13 wherein each subscriber unit in the idling state receives feedback from the base station relating to an adjustment of its transmit power.