Dynamic Point Selection for Seamless CoMP Mobility
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Solution Overview
Problem
Handover in CoMP networks becomes problematic due to extensive offset, causing mobility-related issues in both downlink and uplink transmissions, especially in scenarios with large differences in propagation delays between synchronization sources and transmission points.
Innovation Solution
Implementing dynamic point selection and multiple Fast Fourier Transform (FFT) processing to handle timing and frequency mismatches, allowing seamless mobility support by adjusting FFT windows based on measured timing offsets and using control information parameters for coordinated scheduling and beamforming across eNBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CoMP is implemented to serve UEs in 3GPP LTE networks, then network capacity and data transmission rates are improved, but handover becomes problematic due to extensive offset causing mobility-related issues
Solution Approach 1:
The patent implements dynamic point selection where the transmission point can be switched between multiple eNBs based on real-time channel conditions. The system dynamically adjusts the active transmission point during handover to minimize offset effects and maintain seamless connectivity, resolving the contradiction between network capacity and handover reliability
Solution Approach 2:
The patent changes the timing parameter by introducing pre-FFT synchronization that adjusts the FFT window based on measured timing offsets before the actual data transmission. This parameter adjustment compensates for propagation delay differences between eNBs, enabling reliable handover while maintaining high network capacity
2Reliability
If dynamic point selection is implemented to handle timing offsets, then mobility performance is improved, but device complexity increases due to multiple FFT processing requirements
Solution Approach 1:
The patent performs preliminary synchronization actions by measuring timing offsets and adjusting FFT windows before actual data transmission occurs. This pre-processing of timing information simplifies the overall complexity by preparing synchronization parameters in advance, reducing the computational burden during dynamic handover operations
3Object-affected harmful factors
If pre-FFT synchronization is used to maintain signal integrity, then inter-symbol interference is reduced, but processing time increases due to timing offset measurement and adjustment
Solution Approach 1:
The patent maintains continuous synchronization by periodically measuring timing offsets and adjusting FFT windows without interrupting the data transmission flow. This continuous operation eliminates the need for complete re-synchronization after each handover, reducing processing time while maintaining signal integrity and minimizing inter-symbol interference
Data Source
AI summary
Devices and methods of determining offsets for different eNBs in a dynamic switched CoMP network are generally described. A UE may receive, in an RRCConnectionReconfiguration message, DL parameter sets associated with different eNBs and having reference signal information for a PSS, SSS and DRS. The UE may receive reference signals based on the DL set associated with the eNB and determine a timing/frequency offset based on the reference signals. The offsets may be used to decode a dynamically switched PDSCH indicated by a PDCCH. The DL sets may indicate which PDCCH to detect or the PDCCH from the same cNB may be used and the PDSCH determined from a DCI in the PDCCH. A UL DCI may indicate which of UL parameter sets to use. The UL sets may indicate a reference signal to determine path loss and a timing advance value.