Minimal maintenance link to support synchronization

摘要

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.

主权项

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.