Handover in Heterogeneous Wireless Networks
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Solution Overview
Problem
In heterogeneous wireless networks, frequent handovers between macro and low power nodes result in significant overhead due to the need for radio resource reconfiguration and physical layer changes, which is inefficient and increases latency.
Innovation Solution
A new handover procedure where user equipment (UE) maintains a connection with a macro node while moving between low power nodes, using UE-specific parameters for channel configuration, allowing seamless transition without tearing down and rebuilding radio resources, and utilizing UE-specific parameters like CSI-RS and DMRS for channel initialization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If frequent handovers are performed between macro and low power nodes, then coverage and capacity are improved, but overhead and latency increase due to radio resource reconfiguration
Solution Approach 1:
The system performs preliminary actions by pre-configuring UE-specific parameters (CSI-RS resources, DMRS parameters, power control settings) at the target low power node before handover occurs. The source eNB provides this configuration information to the target eNB in advance, so that when handover is triggered, the UE can immediately use the pre-configured parameters without waiting for reconfiguration messages, thereby reducing handover latency while maintaining coverage expansion
Solution Approach 2:
The system implements dynamic handover parameters where the UE maintains different parameter sets for different nodes. The UE dynamically switches between pre-configured parameter sets corresponding to different low power nodes based on measurement reports, rather than using static parameters that require reconfiguration during handover. This dynamic approach enables seamless transitions between nodes without the overhead of reconfiguring radio resources
2Reliability
If traditional handover procedure is used with radio resource reconfiguration, then connection reliability is maintained, but device complexity and signaling overhead increase
Solution Approach 1:
The source eNB performs preliminary actions by providing the target eNB with all necessary UE-specific configuration information (CSI-RS resource configurations, DMRS parameters, power control settings, PUCCH/PUSCH parameters) before handover is executed. This pre-provisioning of configuration data eliminates the need for complex reconfiguration signaling during handover, reducing both device complexity and signaling overhead while maintaining connection reliability through the use of pre-validated parameters
Solution Approach 2:
The invention extracts the configuration information provision step from the traditional handover procedure. Instead of including full reconfiguration messages in the handover execution phase, the system separates the configuration provisioning (done in advance by source eNB to target eNB) from the handover execution (where only a handover command is sent to UE). This extraction simplifies the handover procedure and reduces signaling overhead while maintaining all necessary configuration details for reliable connection
Data Source
AI summary
Technology for performing a handover in a heterogeneous wireless network (HetNet) is disclosed. One method comprises receiving, at an anchor serving cell in the HetNet, channel measurement reports made by a user equipment (UE) for a plurality of cells. A transmission point change request can be sent, based on the channel measurements for the UE, from the anchor serving cell to a target transmission point. The target transmission point is located in one of the plurality of cells. A transmission point change indicator is sent from the anchor cell to the UE to indicate a change in TP with which the UE will communicate via an air interface, while maintaining a connection to the anchor serving cell.