Inter-Frequency Measurement Prioritization for LTE Handover
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Solution Overview
Problem
In LTE wireless communication systems, performing inter-frequency measurements on a large number of carriers can lead to increased measurement time, potentially causing handover delays and traffic interruptions, especially for UEs in motion, as they struggle to complete necessary measurements before a handover is required.
Innovation Solution
Implementing a prioritization mechanism where higher priority measurements, such as those targeting macro cells, are performed sooner and more frequently than lower priority measurements, like those targeting small cells, with predetermined delay requirements to ensure timely handover and minimize communication disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inter-frequency measurements are performed on a large number of carriers, then measurement coverage is improved, but measurement time increases causing handover delays
Solution Approach 1:
The patent segments the measurement tasks by dividing carriers into priority groups (first priority and second priority). The UE performs measurements on first priority carriers more frequently and with shorter measurement periods, while second priority carriers are measured less frequently. This segmentation allows the system to maintain comprehensive measurement coverage across multiple carriers while reducing the time spent on less critical measurements, thereby resolving the contradiction between coverage and measurement time.
Solution Approach 2:
The patent implements preliminary action by configuring the UE with priority information and measurement parameters in advance through RRC signaling from the eNB. The UE is pre-instructed on which carriers to measure first and what measurement gaps to use, allowing it to perform measurements efficiently without delays during actual handover decisions. This preliminary configuration enables the UE to be ready for handover faster.
2Measurement precision
If measurements are performed on all carriers with equal priority, then measurement completeness is improved, but handover response time deteriorates
Solution Approach 1:
The patent applies local quality by assigning different measurement priorities to different carriers based on their importance. First priority carriers (such as those with better signal quality or covering critical areas) receive more measurement resources and shorter measurement periods, while second priority carriers receive fewer resources. This differentiated approach ensures that measurements are complete for all carriers while critical carriers are measured with higher precision and speed, improving handover response time.
3Reliability
If measurement frequency is increased for all carriers, then handover reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamics by making the measurement frequency adaptive rather than static. The measurement period for each carrier is dynamically adjusted based on its priority level and the UE's movement state. When the UE is in motion, measurements on first priority carriers are performed more frequently to ensure handover reliability. When the UE is stationary or moving slowly, the measurement frequency is reduced. This dynamic adjustment maintains handover reliability while significantly reducing energy consumption compared to continuous high-frequency measurements on all carriers.
Data Source
AI summary
Systems and methods for prioritizing inter-frequency measurement are disclosed herein. User equipment (UE) may be configured to communicatively couple to an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (eNB). The eNB may determine a priority for performing each of a plurality of inter-frequency measurement. The eNB may indicate the priority of each measurement to the UE. The eNB may transmit lists of higher priority and lower priority measurement objects. The lists may be separate and/or concatenated. Alternatively, or in addition, each measurement object may include a priority indicator, or the priority may be determined from the type of measurement object. In some embodiments, the eNB may provide indications of normal priority and low priority measurement objects and/or indications of normal priority and high priority measurement objects. The UE may perform measurements according to the indicated priorities.