Apparatus And Method For Establishing Uplink Synchronization In A Wireless Communication System

What is this patent about?

’503 is related to the field of wireless communication systems, specifically addressing the problem of uplink synchronization in systems employing carrier aggregation . In such systems, a user equipment (UE) communicates with a base station (eNB) using multiple component carriers (CCs). Maintaining accurate uplink synchronization is crucial for efficient communication, but the propagation delays can vary significantly between different CCs, especially when they are widely separated in frequency or served by different network elements.

The underlying idea behind ’503 is to group component carriers into uplink timing groups and then use a delegate CC within each group to establish and maintain uplink synchronization. The eNB transmits timing advance (TA) commands based on the delegate CC, and the UE applies this TA to all other CCs within the same timing group. This approach avoids the need for independent synchronization procedures for each CC, simplifying the process and reducing overhead.

The claims of ’503 focus on a communication method and apparatus for both the UE and the eNB. The UE receives a Radio Resource Control (RRC) message through a primary CC, which contains information about a second uplink timing group including a secondary CC. The UE then transmits a random access preamble through one or more CCs, each acting as a delegate CC for its respective timing group. The eNB responds with a random access response containing a Timing Advance (TA) value for each timing group, which the UE then applies to the secondary CC.

In practice, the eNB configures the UE with information about the uplink timing groups and designates a delegate CC for each group. The UE then initiates a non-contention based random access procedure on the delegate CC. The eNB measures the timing offset on the delegate CC and sends a TA command back to the UE. The UE then applies this TA command to all CCs within the same timing group, ensuring that all uplink transmissions from the UE within that group are synchronized with the eNB.

This approach differs from prior solutions that treat each CC independently or assume a single timing advance for all CCs. By grouping CCs with similar propagation characteristics and using a delegate CC for synchronization, ’503 provides a more efficient and robust method for maintaining uplink synchronization in carrier aggregation systems. This is particularly important for achieving high data rates and reliable communication in modern wireless networks.