Fast acquisition of traffic channels for a highly variable data rate reverse link of a CDMA wireless communication system

• US 20050259624A1
• Filed: 07/18/2005
• Published: 11/24/2005
• Est. Priority Date: 06/01/1998
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Tantivy Communications Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr.
• Granted Patent: US 7,480,280 B2
• Time in Patent Office: Days
• 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 service option overlay for a CDMA wireless communication in which multiple allocatable subchannels are defined on a reverse link by assigning different code phases of a given long pseudonoise (PN) code to each subchannel. The instantaneous bandwidth needs of each on-line subscriber unit are then met by dynamically allocating none, one, or multiple subchannels on an as needed basis for each network layer connection. The system efficiently provides a relatively large number of virtual physical connections between the subscriber units and the base stations on the reverse link for extended idle periods such as when computers connected to the subscriber units are powered on, but not presently actively sending or receiving data. These maintenance subchannels permit the base station and the subscriber units to remain in phase and time synchronism. This in turn allows fast acquisition of additional subchannels as needed by allocating new code phase subchannels. Preferably, the code phases of the new channels are assigned according to a predetermined code phase relationship with respect to the code phase of the corresponding maintenance 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 channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the method comprising the steps of:

a) making available a plurality of subchannels within each CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

b) allocating available subchannels only on an as-needed basis, wherein the number of subchannels allocated is variable during the duration of a given session; and

c) on a reverse link, providing an idling mode connection for subscriber units which are powered on, but not presently actively sending data, wherein the idling mode connection is operable to enable to subchannels to be reallocated without reestablishing a bit synchronization with the base station.

2. A method as in claim 1 wherein the step of providing an idling mode connection the subscriber unit sends a heartbeat signal at a data rate which is low enough to maintain the bit synchronization with the base station.

3. A method as in claim 2 wherein the data rate of the heartbeat signal is from about 37 to 80 bps.

4. A method as in claim 1 wherein in order to reduce the overhead of maintaining the connections, instead of assigning a different Walsh code to each subscriber, the subscriber units use the same PN long code but at different code phases.

5. A method as in claim 2 wherein the heartbeat message is time slotted between inactive links, to allow fewer dedicated base station receivers to maintain the links.

6. A method as in claim 1 wherein to enter an active state, the subscriber unit sends a command requesting a higher data service rate.

7. A method as in claim 6 wherein upon receiving a request for higher capacity data or voice traffic, the base station hands the link to a reverse channel traffic processor, and the higher rate is then made available by the base station assigning additional code phases to the subscriber unit.

8. A method as in claim 7 wherein the additional code phases are assigned in a predetermined phase relationship to minimize overhead transmissions from the base station traffic channel processor.

9. A method as in claim 6 wherein the ramp-up of data rate may occur in two phases, with the subscriber unit first being granted only access to a lower available rate channel, prior to granting access to a full rate channel.

10. A method as in claim 1 wherein if the base station determines that the maximum data rate for one connection is not enough, additional code channels are assigned to the subscriber.

11. A method as in claim 10 wherein the additional channels have a predetermined relationship to the original code phase.

12. A method as in claim 1 wherein a plurality of subchannels are made available on a single radio frequency carrier by assigning orthogonal codes for each subchannel.