LTE Handover Skipping Random Access for LSA Spectrum Release
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Solution Overview
Problem
LTE networks face challenges in efficiently adapting to dynamic spectrum availability due to the need for frequent handovers when incumbent users reclaim Licensed Shared Access (LSA) spectrum, leading to increased over-the-air signaling and reduced quality of service, especially when hundreds of User Equipments (UEs) need to switch from LSA to primary LTE bands.
Innovation Solution
Implementing a faster, less computationally expensive intra-eNB inter-frequency handover process that allows UEs to skip the random access procedure (RAP) by synchronizing frames between collocated LTE and LSA physical cells, using enhanced RRC message formats to indicate skipping RAP and providing dedicated preambles when necessary, thereby reducing the need for RAP and minimizing service disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs perform standard handover procedures including random access procedure when switching from LSA to primary LTE bands, then handover reliability is improved, but handover time and signaling overhead increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing frames between collocated LTE and LSA physical cells before handover is needed. This allows the UE to skip the random access procedure during actual handover, as the timing alignment is already established. The frame synchronization is performed in advance when the LSA cell is active and collocated with the LTE cell, preparing the conditions for rapid handover when spectrum reclamation occurs.
2Reliability
If standard handover procedures are used for spectrum reclamation, then connection reliability is maintained, but over-the-air signaling increases and quality of service deteriorates
Solution Approach 1:
The patent extracts and removes the random access procedure from the handover process for UEs that are handed over due to LSA spectrum reclamation. By identifying specific handover scenarios where the source and target cells are collocated and frame-synchronized, the patent eliminates the RAP step entirely, keeping only the essential handover signaling. This extraction significantly reduces over-the-air signaling while maintaining connection reliability through the pre-established frame synchronization.
3Speed
If frame synchronization is implemented between collocated LTE and LSA cells, then handover speed is improved, but system complexity increases
Solution Approach 1:
The patent applies local quality by implementing frame synchronization specifically for collocated LTE and LSA physical cells, rather than requiring universal synchronization across all cells. The synchronization mechanism is activated only in the local context where LTE and LSA cells share the same physical location and timing relationships. This localized approach enables fast handover for affected UEs without requiring system-wide changes or increasing overall network complexity.
Data Source
AI summary
Embodiments of Evolved Node-B (eNBs), user equipment (UE) and methods for licensed shared access (LSA) handover are generally described herein. An eNB includes hardware processing circuitry to receive a command to release spectrum resources in a LSA band over which the eNB serves an LSA cell; to determine whether user equipment (UEs) served by the eNB are permitted to skip a random access process (RAP) to be handed over to a target cell operating on a band separate from the LSA band; and to transmit a message to a UE served by the eNB instructing the UE that the UE is to be handed over to the target cell, the message including one or more indicators based on the determination. Other apparatuses, systems and methods are also disclosed.