Mapping DM-RS in LTE-A Special Subframes for Signal Reception
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Long Term Evolution Advanced (LTE-A) wireless networks, some special subframe configurations do not have demodulation reference signals (DM-RS) assigned for transmission within the special subframe, preventing the user equipment (UE) from receiving signals during the downlink pilot time slot (DwPTS) of these subframes.
Innovation Solution
The evolved Node B (eNB) transmits DM-RSs in the DwPTS of special subframes with specific configurations, such as special subframe configuration 0 with a normal or extended cyclic prefix, ensuring the UE can receive signals by assigning DM-RSs to appropriate resource elements, avoiding collisions with primary and secondary synchronization signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If DM-RS are not assigned in the DwPTS of special subframe configurations, then the device complexity is reduced, but the UE cannot receive signals during the DwPTS
Solution Approach 1:
The patent applies local quality by assigning DM-RS to specific resource elements within the DwPTS based on the special subframe configuration. Different configurations receive DM-RS assignments in different resource element patterns, allowing the system to maintain simplicity where not needed while ensuring signal reception capability where required. The mapping circuitry selectively applies DM-RS assignment patterns based on the specific configuration type.
Solution Approach 2:
The patent changes the parameter of DM-RS assignment by introducing configuration-dependent mapping rules. The mapping circuitry modifies the resource element assignment parameters based on the special subframe configuration, enabling dynamic adaptation of DM-RS placement to resolve the contradiction between maintaining simple configurations and ensuring signal reception capability.
2Measurement precision
If DM-RS are assigned to resource elements in the DwPTS, then the UE can demodulate transmissions, but resource elements may collide with synchronization signals
Solution Approach 1:
The patent segments the resource elements in the DwPTS into different groups: some assigned to DM-RS and others reserved for synchronization signals based on the special subframe configuration. The mapping circuitry divides the resource element space and assigns DM-RS only to non-colliding positions, preventing interference while maintaining demodulation capability.
Solution Approach 2:
The mapping circuitry acts as an intermediary that coordinates between DM-RS assignment and synchronization signal placement. It mediates the resource element allocation by applying configuration-specific mapping rules that ensure DM-RS and synchronization signals occupy disjoint resource element sets, eliminating collisions while preserving both functions.
3Adaptability or versatility
If special subframe configurations without DM-RS assignment are used, then the network flexibility is improved, but channel estimation accuracy deteriorates
Solution Approach 1:
The patent introduces dynamic DM-RS assignment based on the special subframe configuration. The mapping circuitry adaptively applies different DM-RS mapping patterns according to the active configuration, enabling the system to maintain configuration flexibility while ensuring channel estimation accuracy is preserved through appropriate DM-RS placement in each configuration type.
Data Source
AI summary
Methods, apparatuses, and systems are described related to mapping special subframes in a wireless communication network. In embodiments, an eNB may assign demodulation reference signals (DM-RSs) and/or cell-specific reference signals (CRSs) to a downlink pilot time slot (DwPTS) of a special subframe responsive to a determined configuration of the special subframe. In embodiments, an eNB may bundle the DwPTS or an uplink pilot time slot (UpPTS) of the special subframe with another subframe for scheduling. In embodiments, a UE may estimate a channel associated with the special subframe based on DM-RSs and/or CRSs transmitted in another subframe. In embodiments, an eNB may exclude the DwPTS from scheduling for certain special subframe configurations if a new carrier type (NCT) is used. In embodiments, an eNB may exclude certain special subframe configurations from use for NCT communications. Other embodiments may be described and claimed.