RAN Cache Identifier for Inter-RAT Handover Continuity
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Solution Overview
Problem
During Inter-RAT handovers in wireless communication systems, the network node fails to recognize and continue cache sessions for user equipment, leading to session loss due to the lack of a common identifier across different Radio Access Technologies (RATs).
Innovation Solution
A method where the network node creates and uses a common RAN cache identifier to identify and continue cache sessions across different RATs by including it in handover signaling, ensuring seamless handover of media streams from a source cell to a target cell of a different RAT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a network node supports multiple RATs without a common identifier mechanism, then device complexity is reduced and ease of operation is improved, but cache session continuity is lost during Inter-RAT handovers
Solution Approach 1:
The source base station includes the cache session identifier in the handover request message before the handover is executed. This preliminary inclusion of the identifier allows the target base station to recognize and continue the cache session without requiring complex post-handover identification mechanisms.
Solution Approach 2:
The handover request message serves as an intermediary carrier that transports the cache session identifier from the source base station to the target base station. This intermediary mechanism enables identifier transfer without requiring direct communication between base stations or complex multi-step verification processes.
2Adaptability or versatility
If the network node uses separate identifier systems for different RATs, then adaptability to various RATs is improved, but information loss occurs during handover due to unrecognized cache sessions
Solution Approach 1:
A universal cache session identifier is implemented that can be recognized across different RATs (LTE, WCDMA, GSM). The identifier structure and transmission mechanism are designed to be RAT-agnostic, allowing the same identifier format to function across multiple radio access technologies without requiring conversion or translation.
Solution Approach 2:
The handover request message structure is designed to uniformly carry the cache session identifier regardless of the source or target RAT. This homogeneous approach ensures that the identifier is preserved in its original form throughout the handover process, preventing information loss that would occur with RAT-specific transformations.
3Reliability
If the network node implements comprehensive handover signaling for cache session identification, then reliability of cache session continuity is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The cache session identifier is extracted as a distinct, standalone element within the handover request message. Rather than embedding identification logic throughout the entire signaling protocol, the identifier is separated into a specific field that can be independently processed by the target base station, reducing overall signaling complexity while maintaining reliability.
Data Source
AI summary
A method in a network node for handling a cache session between the network node and a user equipment during a handover of the user equipment from a source cell of a first RAT to a target cell of a second RAT being different from the first RAT is provided. The user equipment and the network node are comprised in a wireless communications system. The network node receives (704) an identifier. The identifier identifies a cache session in the network node. The cache session is associated with a play-out for a media stream to the user equipment via a source base station serving the user equipment in the source cell. The network node identifies (705) the cache session as pertaining to the user equipment subject to said handover, by means of the received identifier. The network node then continues (708) the identified cache session via a target base station serving the target cell, when the handover of the user equipment from the source cell to the target cell has been performed.