Minimal maintenance link to support synchronization

• US 9,301,274 B2
• Filed: 07/10/2013
• Issued: 03/29/2016
• Est. Priority Date: 02/07/2000
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Nelson, G. Rodney Jr., Hoffmann, John E., Rouphael, Antoine J., Proctor, James A.
• Primary Examiner(s): Smith, Marcus R
• Assistant Examiner(s): Tsegaye, Saba
• Application Number:
  US13/938,500
• Publication Number:
  US 20130301636A1
• Time in Patent Office: 993 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 56/005 compensating for timing error by adjustment in the receiver

Abstract

Multiple field units in a CDMA system are synchronized for communication with a base station using a shared forward and reverse link channel. Each field unit is assigned a time slot in a forward link channel to receive messages from the base station. Likewise, each field unit is assigned a time slot on a common reverse link channel for transmitting messages to the base station. Timing alignment among each of many field units and the base station is achieved by analyzing messages received at the base station in a corresponding time slot from each field unit. Thereafter, a message is transmitted in a corresponding time slot to a particular field unit from the base station for adjusting its timing so that future messages transmitted from the field unit are received in the appropriate time slot at the base station. In this way, minimal resources are deployed to maintain communication and precise synchronization between a base station and each of multiple users, minimizing collisions between field units transmitting in adjacent time slots on the reverse link.

Claims

1. A method comprising:

assigning a plurality of codes to a field unit;

transmitting an indication of the plurality codes to the field unit;

receiving a first message in at least one time slot, wherein the first message includes one of the plurality of codes, and the one of the plurality of codes is associated with a type of field unit request;

analyzing the one of the plurality of codes to determine a timing adjustment to be made at the field unit to synchronize the field unit with a base station; and

transmitting a second message to the field unit that includes a multi-bit value notifying the field unit of an amount to advance or retard its initial timing to achieve synchronization with the base station.

2. The method of claim 1 wherein the one of the plurality of codes comprises a plurality of symbols.

3. The method of claim 1, wherein the timing adjustment is a single bit.

4. The method of claim 1, wherein the plurality of codes comprise a plurality of groups of one or more codes, and each of the plurality of groups of one or more codes is associated with a type of field unit request.

5. The method of claim 1, wherein each of at least two of the plurality of codes are respectively associated with a different type of field unit request.

6. The method of claim 1, wherein the type of field unit request is a request to enter an active mode.

7. The method of claim 1, wherein the type of field unit request is a request for bandwidth.

8. The method of claim 1, wherein the type of field unit request is a request by the field unit to transmit data.

9. The method of claim 1, wherein transmitting the second message to the field unit constitutes a coarse timing adjustment message which additionally provides the field unit with a slot timing reference for receiving and transmitting messages in assigned time slots.

10. The method of claim 1, further comprising:

monitoring an access channel of the base station to detect request the first request by the field unit to establish a wireless link with the base station;

receiving the link request message at base station, the link request message including a sequence of pilot symbols followed by data identifying the field unit making having sent the link request; and

accessing details at the base station regarding a particular subscriber and characteristics of the corresponding field unit.

11. A base station operable in a wireless communication network, the base station comprising:

a transmitter configured to transmit an indication of a plurality of codes to a field unit; and

a receiver configured to receive a message containing a code from a field unit to determine a timing adjustment to be made at the field unit to synchronize the field unit with the base station,

wherein the received code is associated with a type of field unit request;

wherein the transmitter is further configured to transmit a feedback message to the field unit containing the timing adjustment; and

wherein the timing adjustment indicates a multi-bit value notifying the field unit of an amount to advance or retard its initial timing to achieve synchronization with the base station.

12. The base station of claim 11, wherein a first channel supports communication from the base station to the field unit and a second channel supports communication from the field unit to the base station and wherein the first channel and the second channel comprise time slots.

13. The base station of claim 11, wherein the receiver is configured to receive the message containing the code over a plurality of symbols.

14. The base station of claim 11, wherein the plurality of codes comprise a plurality of groups of one or more codes, and each of the plurality of groups of one or more codes is associated with a type of field unit request.

15. The base station of claim 11, wherein each of at least two of the plurality of codes are respectively associated with a different type of field unit request.

16. The base station of claim 11, wherein the type of field unit request is a request to enter an active mode.

17. The base station of claim 11, wherein the type of field unit request is a request for bandwidth.

18. The base station of claim 11, wherein the type of field unit request is a request by the field unit to transmit data.

19. A field unit operable in a wireless communication network, the field unit comprising:

a receiver configured to receive an indication of a plurality of codes from a base station; and

a transmitter configured to transmit an access identifier selected from the plurality of codes received from the base station, wherein the selected code is associated with a type of field unit request;

wherein the receiver is further configured to receive, from the base station, a feedback message based on the transmitted code; and

wherein the feedback message contains a multi-bit value notifying the field unit of an amount to advance or retard its initial timing to achieve synchronization with the base station.

20. The field unit of claim 19, wherein a first channel supports communication from a base station to the field unit and a second channel supports communication from the field unit to the base station and wherein the first channel and the second channel comprise time slots.