Handover to Multi-Band Cells via EARFCN Signaling
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Solution Overview
Problem
Existing wireless communication systems face challenges in handover procedures when user equipment (UE) supports bands that overlap with newer frequency bands not defined in earlier standards, leading to improper UE behavior and handover failures, especially when UEs do not comprehend extension signaling for multiple band support.
Innovation Solution
The UE indicates its supported bands to the network and can be handed over to any overlapping band, receiving an absolute radio frequency channel number from the serving station to connect, regardless of whether it matches a supported or used band, allowing for seamless handovers without relying on legacy band indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE relies on legacy band indicators for handover, then the handover procedure is simple and well-defined, but the UE cannot properly hand over to newer frequency bands not defined in earlier standards
Solution Approach 1:
The patent changes the handover parameter from legacy band indicators to absolute radio frequency channel numbers (EARFCNs). This allows the UE to hand over to any frequency band by matching EARFCN values rather than relying on predefined band indicators, enabling compatibility with new frequency bands while maintaining simple UE behavior
Solution Approach 2:
Instead of the network checking if the target band matches UE supported bands, the patent inverts the approach by having the UE connect to any EARFCN provided by the network without autonomous termination checks. This reverses the traditional handover validation logic and simplifies the procedure
2Reliability
If the UE autonomously terminates connection when target cell does not transmit in supported bands, then the UE protects itself from incompatible connections, but handover fails when roaming to cells in new frequency bands
Solution Approach 1:
The patent inverts the autonomous termination logic by specifying that the UE shall NOT autonomously terminate the connection if the target cell does not transmit in any of the UE's supported bands. This allows the UE to maintain connections with cells in new frequency bands while the network ensures compatibility through proper EARFCN assignment
Solution Approach 2:
The EARFCN acts as an intermediary parameter that bridges the UE and network for handover. The network provides the EARFCN of the target cell, and the UE uses this absolute frequency reference to connect without needing to verify band compatibility, enabling seamless roaming to new bands
3Measurement precision
If the network verifies band compatibility before handover, then handover accuracy is high, but network implementation complexity increases
Solution Approach 1:
The patent extracts the band compatibility verification from the network's handover decision process. Instead of the network verifying whether target bands match UE supported bands, the system simply provides the EARFCN and lets the UE connect directly, removing the complex verification step while maintaining accuracy through absolute frequency referencing
Data Source
AI summary
Methods, apparatuses, and computer program products for handover to cell supporting multiple frequency bands are provided. One method comprises indicating, by a UE, supported bands to a serving eNB, and indicating to the serving eNB that the UE can be handed over to any band overlapping with the supported bands. The method may also include receiving the EARFCN of a target eNB from the serving eNB, and connecting to the target eNB regardless of whether the EARFCN corresponds to any band indicated by the target eNB as being supported and/or regardless of whether the EARFCN is equal to an EARFCN indicated as being used by the target eNB. The indicating may further include indicating to the serving eNB that the UE will not autonomously terminate connection with a target cell if the target eNB does not transmit in any of the indicated supported bands.