Relay Node Handover via X2-C Bearer in LTE-Advanced
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Solution Overview
Problem
Conventional mobile communication systems lack regulation for handling handover processes when relay nodes are connected, particularly in LTE-Advanced systems, and existing solutions do not adequately address handovers involving relay stations and radio bearers.
Innovation Solution
The mobile communication system implements a handover process between relay nodes and radio base stations using an X2-C radio bearer, with control signals sent via this bearer, and includes specific layer functions such as PHY, MAC, RLC, PDCP, and SCTP to manage the handover, allowing the mobile station to switch between relay nodes and radio base stations without requiring significant protocol stack renovations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If relay nodes are connected in LTE-Advanced mobile communication system, then network coverage and capacity are improved, but handover process regulation is missing causing system complexity increase
Solution Approach 1:
The patent applies universality by making the existing X2 bearer interface serve multiple functions: it maintains its original role for direct eNB-to-eNB communication while simultaneously enabling relay node handover support through the same interface. This allows the system to handle both conventional and relay-scenario handovers using a unified mechanism, avoiding the need for separate handover protocols for relay nodes.
Solution Approach 2:
The patent uses the X2 bearer as an intermediary mechanism that enables indirect communication between the mobile station and the target base station through the relay node during handover. The relay node acts as a mediator that forwards handover control signals between the mobile station and the network, allowing handover to proceed without requiring new direct signaling paths.
2Adaptability or versatility
If new handover protocols for relay nodes are developed, then handover functionality is improved, but protocol stack complexity and implementation difficulty increase
Solution Approach 1:
The patent makes the existing X2 bearer interface universal by enabling it to handle both conventional eNB-to-eNB handovers and relay node handovers through the same protocol stack. The existing network layer, transport layer, and radio bearer functions are reused without modification, allowing relay node handover to proceed using the same implementation framework as traditional handovers.
Solution Approach 2:
The system applies self-service by allowing the existing X2 bearer infrastructure to automatically support relay node handovers without requiring new protocol developments. The same signaling mechanisms, message formats, and processing logic that serve conventional handovers continue to function for relay scenarios, with the relay node seamlessly integrating into the existing handover flow.
3Reliability
If additional radio bearers are established for relay node handover, then handover control is improved, but system resource consumption and complexity increase
Solution Approach 1:
The patent achieves universality by enabling the existing X2 bearer to serve dual purposes: maintaining its original function for direct base station communication while simultaneously supporting relay node handover control. This eliminates the need to create separate dedicated radio bearers for relay handover, as the same bearer infrastructure handles both scenarios.
Solution Approach 2:
The patent merges the handover control function for relay nodes with the existing X2 bearer infrastructure. Instead of creating separate signaling paths or additional bearers, the patent combines relay node handover control into the existing eNB-to-eNB handover framework, allowing both functions to coexist on the same radio bearer resources.
Data Source
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AI summary
A mobile communication system in which a relay node and a radio base station are connected via a radio bearer, wherein the relay node comprises: as a radio bearer function of setting the radio bearer between the relay node and the radio base station, a physical layer function; an MAC layer function provided as an upper layer function of the physical layer function; an RLC layer function provided as an upper layer function of the MAC layer function; and a PDCP layer function provided as an upper layer function of the RLC layer function, the relay node comprises: an IP layer function as an upper layer function of the radio bearer function; an SCTP layer function provided as an upper layer function of the IP layer function; and an X2AP layer function provided as an upper layer function of the SCTP layer function, the radio base station comprises: as a radio bearer function of setting the radio bearer between the radio base station and the relay node, a physical layer function; an MAC layer function provided as an upper layer function of the physical layer function; an RLC layer function provided as an upper layer function of the MAC layer function; and a PDCP layer function provided as an upper layer function of the RLC layer function, the radio base station comprises: an IP layer function as an upper layer function of the radio bearer function; an SCTP layer function provided as an upper layer function of the IP layer function; and an X2AP layer function provided as an upper layer function of the SCTP layer function, and a control signal relating to a handover process is configured to terminate between the X2AP layer function of the relay node and the X2AP layer function of the radio base station wherein the handover process is between the status of the mobile station communicating with the radio base station via the relay node and the status of the mobile station communicating with the radio base station.