GSM-R LTE Coexistence via EPDCCH Gap Allocation
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Solution Overview
Problem
Current communication systems in railway networks face challenges in upgrading from GSM-R to LTE due to resource constraints and the need for separate frequency bands, which is not feasible due to monetary and availability issues, and existing dual communication systems require separate frequency bands, consuming many resources.
Innovation Solution
The method exploits gaps between narrowband channels of GSM-R to co-locate GSM-R and LTE systems on a single frequency band, using Enhanced Physical Downlink Control Channel (EPDCCH) and Demodulation Reference Symbols (DM-RS) to increase throughput, allowing GSM-R to be enhanced with LTE without requiring new frequency bands, and minimizing channel resource overlap to protect GSM-R quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate frequency bands are used for GSM-R and LTE systems, then communication quality is maintained, but frequency band resources are consumed excessively
Solution Approach 1:
The patent merges GSM-R and LTE systems into a single frequency band by placing LTE resource blocks in the gaps between GSM-R narrowband channels. This combining approach allows both systems to coexist in the same spectrum, reducing total frequency band consumption while maintaining communication quality through careful resource isolation.
Solution Approach 2:
The patent implements a nested structure where LTE resource blocks are embedded within the gaps of the GSM-R frequency band. The LTE system is nested inside the available spaces of the GSM-R band, creating a hierarchical frequency allocation where one system's resources are contained within the overall spectrum allocation of the other.
2Quantity of substance
If GSM-R and LTE are co-located on a single frequency band, then frequency band resources are saved, but channel resource overlap and interference occur
Solution Approach 1:
The patent segments the frequency band into distinct regions: GSM-R narrowband channels occupy specific frequency positions, while LTE resource blocks are allocated to the gaps between these channels. This segmentation creates clear boundaries that prevent channel resource overlap and minimize interference between the two systems.
Solution Approach 2:
The patent applies local quality by assigning different resource allocation patterns to different parts of the frequency band. In regions where GSM-R channels are active, LTE resources are excluded; in the gaps between GSM-R channels, LTE resource blocks are placed. This localized resource allocation optimizes spectrum utilization while preventing interference.
3Productivity
If LTE resource blocks are placed in gaps between GSM-R narrowband channels, then spectrum efficiency is improved, but system complexity increases
Solution Approach 1:
The patent implements dynamic resource allocation where the network can flexibly assign LTE resource blocks to different gap positions between GSM-R channels based on traffic demands and channel conditions. This dynamic approach improves spectrum efficiency by adapting resource usage to actual needs while the underlying gap structure maintains manageable system complexity.
Data Source
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AI summary
The invention relates to a method for operating a first and a second communication system, having a first and a second predetermined frequency band (13, 17), respectively, to be used for communication between a user terminal (4) and a node (2) of a cellular network (1), wherein the first communication system (11) has at least two narrowband channels (14, 15), which are distributed with a mutual spacing (16) over the first frequency band (13), and wherein the second communication system (12) has a set (18) of channel resources (19), which are distributed contiguously over the second frequency band (17), wherein the first and the second frequency band (13, 17) overlap, and communication is performed only in those channel resources (19) that do not overlap with the narrowband channels (14, 15), and wherein Enhanced Physical Downlink Control Channel (EPDCCH) and Demodulation Reference Symbols (DM-RS) are employed instead of the Physical Downlink Control Channel (PDCCH) and regular Reference Symbols (RS) of the LTE system. The invention further relates to a node of a cellular network for communication with the user terminal.