Uplink Synchronization via Extended Cyclic Prefix
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Solution Overview
Problem
In wireless networks, uplink transmissions from user equipment (UEs) to base stations often experience interference due to round-trip delays and multi-path propagation, leading to unsynchronized signals, which can be mitigated by adjusting timing advance, but this requires additional overhead signaling, especially for small data transmissions.
Innovation Solution
The use of longer cyclic prefix durations in uplink transmissions to compensate for propagation delays, allowing synchronization without adjusting timing advance, thereby omitting timing advance reference signaling and reducing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing advance adjustment is used to synchronize uplink transmissions, then uplink synchronization is improved, but signaling overhead increases
Solution Approach 1:
The patent changes the cyclic prefix length parameter from its conventional value to an extended value that can accommodate the maximum round-trip delay in the cell. This parameter change allows the system to achieve uplink synchronization without requiring timing advance adjustments, thereby eliminating the signaling overhead associated with timing advance commands while maintaining reliable synchronized uplink transmissions
2Reliability
If cyclic prefix length is extended to compensate for propagation delays, then uplink synchronization is achieved without timing advance signaling, but transmission overhead increases
Solution Approach 1:
The patent applies parameter change by extending the cyclic prefix length to a specific value that covers the maximum round-trip delay in the cell. This extended cyclic prefix acts as a guard interval that absorbs propagation delays, enabling uplink synchronization without timing advance signaling. The patent optimizes this parameter extension to be just sufficient for synchronization purposes, minimizing the additional overhead while achieving the desired reliability
Solution Approach 2:
The patent extracts the timing advance signaling function from the system by using the extended cyclic prefix to handle propagation delays. Instead of using dynamic timing advance commands to adjust for delays, the system extracts this adjustment function and incorporates it into the static extended cyclic prefix structure, thereby eliminating the need for continuous timing advance signaling overhead
3Productivity
If timing advance reference signaling is omitted to reduce overhead, then signaling efficiency improves, but uplink synchronization may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-configuring the user equipment with the extended cyclic prefix length before uplink transmissions begin. This preliminary configuration of the cyclic prefix parameter prepares the system in advance to handle propagation delays, ensuring that uplink synchronization is maintained without requiring subsequent timing advance adjustments or reference signaling during the transmission process
Data Source
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AI summary
Uplink synchronization may be achieved without adjusting for timing advance by using longer/larger cyclic prefix durations to compensate for differences in propagation delays, including the cell round-trip delays and environment based multipath delays. In this way, timing advance reference signaling may be omitted from the uplink transmissions. In some embodiments, the cyclic prefix duration is determined based on a characteristic of a base station's coverage area, such as a coverage area size or coverage area type. For example, a longer cyclic prefix length may be used when a base station has a larger coverage area than when the base station has a smaller coverage area. As another example, a different cyclic prefix length may be used for different coverage types.