System and method for maintaining timing of synchronization messages over a reverse link of a CDMA wireless communication system

• US 20050013284A1
• Filed: 07/21/2004
• Published: 01/20/2005
• Est. Priority Date: 06/01/1998
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Tantivy Communications Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr.
• Granted Patent: US 7,773,566 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04W 74/00 Wireless channel access

Abstract

A method for operating a subscriber unit that communicates with a code division multiple access (CDMA) wireless network is provided. At the subscriber unit, synchronization information is encoded with a CDMA code. The CDMA encoded synchronization information is transmitted from the subscriber unit in discrete repeating intervals. The discrete repeating intervals are separated by other discrete repeating intervals during which the subscriber unit does not transmit synchronization information.

Claims

1-36. -36. (Cancelled).

37. A method for operating a subscriber unit that communicates with a code division multiple access (CDMA) wireless network comprising the steps of:

encoding at the subscriber unit synchronization information with a CDMA code; and

transmitting from the subscriber unit the CDMA encoded synchronization information in discrete repeating intervals, with the discrete repeating intervals being separated by other discrete repeating intervals during which the subscriber unit does not transmit synchronization information.

38. The method of claim 37 further comprising the steps of:

monitoring a buffer at the subscriber unit;

supplying user information to the buffer;

requesting permission to use a first CDMA code for supporting the transmission of a portion of the user information;

requesting permission to use a second CDMA code for supporting the transmission of the user information not in the portion; and

transmitting the user information from the subscriber unit using the first and second CDMA codes.

39. The method of claim 37 wherein each of the discrete repeating intervals comprises a time slot of a recurring frame.

40. The method of claim 37 wherein the discrete repeating intervals are of equal duration.

41. The method of claim 40 further comprising the step of receiving a message defining a size of the discrete repeating intervals.

42. The method of claim 40 wherein the synchronization information comprises a heartbeat message.

43. The method of claim 38 wherein the step of transmitting synchronization information in discrete repeating intervals does not occur during the step of transmitting user information.

44. A method for operating a subscriber unit to maintain synchronization when not actively transmitting data comprising the steps of:

receiving from a base station a message defining discrete repeating intervals during which the subscriber unit transmits synchronization information encoded with a CDMA code at the subscriber unit; and

, transmitting from the subscriber unit to the base

station the encoded synchronization information in the discrete repeating intervals.

45. The method of claim 44 wherein the discrete repeating intervals comprise time slots.

46. The method of claim 44 wherein the discrete repeating intervals are of equal duration.

47. The method of claim 44 further comprising the steps of:

monitoring a buffer at the subscriber unit;

supplying user information to the buffer;

requesting permission to use a first CDMA code for supporting transmission of a portion of the user information;

requesting permission to use a second CDMA code for supporting transmission of the user information not in the portion; and

transmitting from the subscriber unit the user information using the first and second CDMA codes.

48. The method of claim 44 further comprising the step of receiving a message defining a size of the discrete repeating intervals.

49. A method for supporting variable rate data transfers on a communication link between a base station and a field unit in a wireless CDMA communication system, the method comprising:

transmitting user information from the field unit to the base station using a first allocation of bandwidth; and

, transmitting synchronization information from the

field unit to the base station using a second allocation of bandwidth during discrete repeating intervals of time when the field unit is not actively transmitting user information using the first allocation of bandwidth.

50. The method of claim 49 wherein the discrete repeating intervals of time are of equal duration.

51. The method of claim 49 further comprising the step of receiving a message from the base station defining a size of the discrete repeating intervals.

52. The method of claim 49 wherein the synchronization information comprises bit synchronization information.