DMRS Sequence Offset Mapping for Partial-Bandwidth NR Scheduling
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Solution Overview
Problem
In LTE networks, Cell-specific Reference Signals (CRS) lead to high network energy consumption and unnecessary interference due to continuous transmission, while Demodulation Reference Signals (DMRS) require terminals to know the system bandwidth and scheduled bandwidth positions, which is not feasible in NR networks with wide bandwidths.
Innovation Solution
Wireless communication devices determine a sequence offset for DMRS sequences relative to the system bandwidth, allowing them to identify the portion of the sequence that overlays their scheduled bandwidth without knowing the system bandwidth, through network signaling and defined mappings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRS are transmitted continuously to provide reliable reference signals, then UE can rely on their presence, but network energy consumption increases and unnecessary interference is created
Solution Approach 1:
The patent transitions from continuous CRS transmission to periodic DMRS transmission only when data is scheduled. DMRS are transmitted in a periodic manner synchronized with data transmissions, eliminating the need for continuous reference signal transmission while maintaining reliability for active data sessions.
Solution Approach 2:
The patent extracts the reference signal functionality from the always-on CRS and implements it separately through DMRS that are only transmitted when needed. This separates the reference signal transmission from continuous system operation, allowing energy-efficient transmission only during active data sessions.
2Use of energy by stationary object
If DMRS are used to reduce energy consumption and interference, then network efficiency improves, but terminals must know system bandwidth and scheduled bandwidth positions which increases device complexity
Solution Approach 1:
The patent introduces a mapping relationship as an intermediary between the terminal and the full system bandwidth. The terminal only needs to know its configured bandwidth and the mapping rules, not the complete system bandwidth structure. This intermediary mapping simplifies terminal complexity while enabling DMRS usage.
Solution Approach 2:
The patent segments the system bandwidth into terminal-configured bandwidth portions. Each terminal only needs to manage its own configured bandwidth segment and the corresponding DMRS mapping, rather than managing the entire system bandwidth. This segmentation reduces terminal complexity significantly.
3Adaptability or versatility
If terminals are configured with only a fraction of system bandwidth in NR, then device capabilities are matched to network requirements, but terminals cannot determine DMRS sequence elements without knowing system bandwidth
Solution Approach 1:
The patent applies preliminary action by pre-configuring terminals with bandwidth information and mapping relationships before DMRS transmission. The network provides terminal-configured bandwidth parameters and mapping rules in advance, allowing terminals to determine the correct DMRS sequence elements without needing to know the full system bandwidth during operation.
Solution Approach 2:
The patent uses a mapping relationship as an intermediary that connects the terminal's configured bandwidth to the system bandwidth. This mapping allows terminals with limited bandwidth capabilities to correctly identify DMRS sequence elements corresponding to their scheduled bandwidth without requiring knowledge of the complete system bandwidth structure.
Data Source
AI summary
Methods and apparatuses disclosed herein enable the use of Demodulation Reference Signal (DMRS) sequences that are numbered relative to an overall system bandwidth, while simultaneously enabling wireless communication devices to determine the DRMS sequence elements mapped to their scheduled bandwidths within the system bandwidth. Advantageously, the wireless communication devices need not know the system bandwidth, or even be aware of where their scheduled bandwidths reside within the system bandwidth.