Frequency Error Estimation for Multi-RAT Synchronization
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Solution Overview
Problem
Wireless communication systems face performance degradation and increased power consumption when user equipment (UE) devices support multiple radio access technologies (RATs), particularly due to tune-away operations between advanced and legacy networks, such as LTE and GSM, which disrupt data transmission and battery life.
Innovation Solution
The UE device employs a method to detect synchronization beacons intermittently across multiple time periods and uses a frequency error estimate from one RAT to adjust the clock for another RAT, reducing the need for frequent tune-aways and optimizing power usage by minimizing deep fading events and frequency errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE performs frequent tune-away operations to detect synchronization beacons on the second RAT, then synchronization accuracy is improved, but LTE throughput and power consumption are degraded
Solution Approach 1:
The patent performs frequency error estimation during LTE uplink transmission periods before the actual synchronization beacon detection on the second RAT. This preliminary frequency error measurement allows the UE to pre-compensate for frequency offsets, enabling more accurate synchronization beacon detection with fewer tune-away operations, thus resolving the contradiction between synchronization accuracy and LTE throughput
2Measurement precision
If the UE performs frequent tune-away operations to detect synchronization beacons on the second RAT, then synchronization accuracy is improved, but power consumption is increased
Solution Approach 1:
The patent performs frequency error estimation during LTE uplink transmission periods before the actual synchronization beacon detection on the second RAT. This preliminary frequency error measurement allows the UE to pre-compensate for frequency offsets, enabling more accurate synchronization beacon detection with fewer tune-away operations, thus resolving the contradiction between synchronization accuracy and power consumption
3Measurement precision
If the UE uses separate frequency error estimation for each RAT, then measurement precision is improved, but device complexity and processing overhead are increased
Solution Approach 1:
The patent merges the frequency error estimation process by using the same estimation performed for LTE uplink synchronization to also support synchronization on the second RAT. Instead of performing separate frequency error estimations for each RAT, the system combines the measurement into a single operation during LTE uplink periods, reducing processing overhead while maintaining accuracy through the preliminary estimation approach
Solution Approach 2:
The frequency error estimation mechanism is designed to serve multiple functions: it supports both LTE uplink synchronization and synchronization beacon detection on the second RAT. This multi-functional approach allows a single frequency error measurement to benefit multiple RATs, reducing overall system complexity and processing requirements
Data Source
AI summary
Performing detection of a synchronization beacon. The UE may include a first radio which supports, e.g., simultaneously, a first radio access technology (RAT) and a second RAT. The UE may perform transmission according to the first RAT on the first radio with a base station. The UE may receive a request to perform a tune-away to detect a synchronization beacon on the second RAT. The synchronization beacon may repetitively occur in successive first time periods. The UE may repeatedly perform a search for the synchronization beacon in different sub-portions over successive first time periods. The search may be repeatedly performed until the synchronization beacon is located in a respective sub-portion of one of the successive time periods.