Minimal maintenance link to support synchronization
View Patent ↗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.
1. A method for supporting wireless communications, the method comprising:
assigning a plurality of pseudorandom noise (PN) codes for use by a field unit;
transmitting an indication of the plurality of PN 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 PN codes, and the one of the plurality of PN codes is associated with a type of field unit request;
analyzing the one of the plurality of PN 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 the timing adjustment, wherein the timing adjustment indicates an amount to advance timing and alternatively an amount to retard timing.
2. The method of claim 1 wherein the one of the plurality of PN 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 PN codes comprise a plurality of groups of one or more PN codes, and each of the plurality of groups of one or more PN 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 PN 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. A base station operable in a wireless communication network, the base station comprising:
a transmitter configured to transmit an indication of a plurality of pseudorandom noise (PN) codes to a field unit; and
a receiver configured to receive a message containing a PN 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 PN 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, wherein the timing adjustment indicates an amount to advance timing and alternatively an amount to retard timing.
10. The base station of claim 9 , 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.
11. The base station of claim 9 , wherein the receiver is configured to receive the message containing the PN code over a plurality of symbols.
12. The base station of claim 9 , wherein the plurality of PN codes comprise a plurality of groups of one or more PN codes, and each of the plurality of groups of one or more PN codes is associated with a type of field unit request.
13. The base station of claim 9 , wherein each of at least two of the plurality of PN codes are respectively associated with a different type of field unit request.
14. The base station of claim 9 , wherein the type of field unit request is a request to enter an active mode.
15. The base station of claim 9 , wherein the type of field unit request is a request for bandwidth.
16. The base station of claim 9 , wherein the type of field unit request is a request by the field unit to transmit data.
17. A field unit operable in a wireless communication network, the field unit comprising:
a receiver configured to receive an indication of a plurality of pseudorandom noise (PN) codes from a base station; and
a transmitter configured to transmit a PN code selected from the plurality of PN codes indicated by the base station, wherein the selected PN 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 PN code, wherein the feedback message contains a timing adjustment that indicates an amount to advance timing and alternatively an amount to retard timing.
18. The field unit of claim 17 , 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 the first channel and the second channel comprise time slots.
19. The field unit of claim 17 , wherein the transmitter is configured to transmit the PN code over a plurality of symbols.
20. The field unit of claim 17 , wherein the plurality of PN codes comprise a plurality of groups of one or more PN codes, and each of the plurality of groups of one or more PN codes is associated with a type of field unit request.
21. The field unit of claim 17 , wherein each of at least two of the plurality of PN codes are respectively associated with a different type of field unit request.
22. The field unit of claim 17 , wherein the type of field unit request is a request to enter an active mode.
23. The field unit of claim 17 , wherein the type of field unit request is a request for bandwidth.
24. The field unit of claim 17 , wherein the type of field unit request is a request by the field unit to transmit data.
25. A method for use in a field unit operable in a wireless communication network, the method comprising:
receiving an indication of a plurality of pseudorandom noise (PN) codes from a base station;
selecting a PN code from the plurality of PN codes indicated by the base station, wherein the selected PN code is associated with a type of field unit request;
transmitting the selected PN code to the base station; and
receiving a message, from the base station, based on the transmitted selected PN code, wherein the message contains a timing adjustment that indicates an amount to advance timing and alternatively an amount to retard timing.
26. The method of claim 25 , further comprising:
adjusting transmission timing based on the timing adjustment.
27. The method of claim 25 , 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 the first channel and the second channel comprise time slots.
28. The method of claim 25 , wherein the transmitter is configured to transmit the selected PN code over a plurality of symbols.
29. The method of claim 25 , wherein the plurality of PN codes comprise a plurality of groups of one or more PN codes, and each of the plurality of groups of one or more PN codes is associated with a type of field unit request.
30. The method of claim 25 , wherein each of at least two of the plurality of PN codes are respectively associated with a different type of field unit request.
31. The method of claim 25 , wherein the type of field unit request is a request to enter an active mode.
32. The method of claim 25 , wherein the type of field unit request is a request for bandwidth.
33. The method of claim 25 , wherein the type of field unit request is a request by the field unit to transmit data.