Group Handover via Nested PDCP PDUs in Relay UEs
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Solution Overview
Problem
Current wireless network architectures face challenges in synchronizing handover procedures for relay UE and remote UEs, particularly in handling Packet Data Convergence Protocol (PDCP) messages during group handover, where ensuring simultaneous delivery of encrypted handover commands to relay and remote UEs is difficult due to the basic relaying architecture limitations.
Innovation Solution
A method and system for group handover in wireless networks that involves processing mobility commands in the PDCP layer to generate PDCP Protocol Data Units (PDUs), encapsulating these PDUs within Radio Resource Control (RRC) messages, and transmitting them to relay UEs, which then extract and forward them to remote UEs, ensuring synchronized handover operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the basic relaying architecture is used to forward PDCP PDUs from eNB to relay UE, then the architecture remains simple and straightforward, but it cannot deliver encrypted handover commands for remote UEs simultaneously with the relay UE's own handover command
Solution Approach 1:
The patent embeds PDCP PDUs containing remote UE handover commands within the RRC message structure intended for the relay UE. The encrypted handover commands for remote UEs are nested as payload within the relay UE's RRC container, allowing simultaneous delivery through a single message transmission from source eNB to relay UE, which then forwards both its own command and the nested remote UE commands.
Solution Approach 2:
The patent segments the handover command delivery by separating the relay UE's own handover command from the remote UEs' handover commands. The relay UE's command is processed through normal RRC/PDCP layers, while remote UE commands are extracted, encrypted with their respective security keys, and embedded as nested PDCP PDUs within the relay UE's RRC message container, enabling differentiated handling and simultaneous delivery.
2Productivity
If separate handover procedures are used for relay UE and remote UEs, then each UE can be handled independently, but race conditions occur between relay handover and remote handovers and excessive air signaling is generated
Solution Approach 1:
The patent merges the relay UE handover procedure with the remote UE handover procedures into a single coordinated group handover operation. The source eNB generates a single RRC message containing both the relay UE's handover command and nested PDCP PDUs with remote UE handover commands. This unified approach eliminates race conditions by ensuring all UEs receive their handover commands simultaneously and reduces air signaling by transmitting one consolidated message instead of multiple separate commands.
3Reliability
If complete RRC messages encrypted according to each remote UE's security configuration are generated, then security is maintained for each UE, but the message complexity and processing overhead increase significantly
Solution Approach 1:
The patent uses the relay UE as an intermediary to handle multiple security configurations. The source eNB generates a single RRC message encrypted with the relay UE's security key, containing nested PDCP PDUs that hold separately encrypted handover commands for each remote UE. Each remote UE's command within the nested structure is encrypted with that specific UE's security key, allowing the system to maintain individual security requirements while using a unified message structure transmitted through the relay UE intermediary.
Data Source
AI summary
A method and system for group handover is provided. In an embodiment, a method in a network component for group handover in a wireless network includes receiving, at the network component, a mobility command from a target base station. The method also includes processing, with the network component, the mobility command in a packet data convergence protocol (PDCP) layer of a context for a remote user equipment (UE) to generate a PDCP Protocol Data Unit (PDU). The method also includes encapsulating the PDCP PDU as a field in a radio resource control (RRC) message to the relay UE.