Downlink Resource Puncturing Around Reserved LTE Resource Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MTC devices in LTE networks face challenges in receiving downlink transmissions due to collisions with reserved Resource Elements (REs) for Reference Signals (RSs), particularly when these collisions occur in repeated subframes, leading to degraded performance or inability to decode messages like PDSCH and EPDCCH.
Innovation Solution
The solution involves using Orthogonal Cover Codes (OCCs) to indicate the presence of reserved REs, allowing MTC devices to dynamically detect and avoid or rate-match around these REs, ensuring accurate demodulation of downlink channels like EPDCCH and PDSCH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If MTC devices use reduced RF bandwidth to lower cost and power consumption, then device cost and power consumption are reduced, but the ability to receive conventional PDCCH is lost and coverage is degraded
Solution Approach 1:
The patent segments the downlink transmission into different regions: a first region for EPDCCH transmission and a second region for PDSCH transmission. This segmentation allows MTC devices with reduced bandwidth to receive control information in the first region while the base station transmits data in the second region, resolving the contradiction between reduced bandwidth and reception reliability.
Solution Approach 2:
The patent applies preliminary action by having the base station transmit Downlink Control Information (DCI) before the actual data transmission. The DCI includes reservation information that preliminarily indicates which resource elements are reserved for reference signals, allowing the MTC device to prepare its reception parameters in advance and avoid collisions with reserved REs during the actual data reception.
2Reliability
If the base station transmits downlink messages in repeated subframes to enhance coverage, then coverage is improved, but collisions with reserved REs increase and decoding performance degrades
Solution Approach 1:
The patent implements feedback through the base station transmitting reservation information in the DCI for each repeated subframe. This feedback mechanism allows the MTC device to know in advance which REs are reserved in each repetition, enabling the device to adjust its reception parameters dynamically and avoid decoding errors caused by collisions with reference signals in any of the repeated subframes.
Solution Approach 2:
The patent applies dynamics by making the resource allocation flexible rather than fixed. The base station dynamically indicates reserved REs through DCI signaling for each repeated subframe, allowing the MTC device to adapt its reception parameters dynamically across different subframes. This dynamic approach enables the device to handle varying collision patterns in repeated transmissions without fixed decoding assumptions.
3Measurement precision
If the base station uses rate matching around reserved REs, then reception accuracy is improved, but the device must have prior knowledge of reserved RE locations which is not available before RRC configuration
Solution Approach 1:
The patent applies preliminary action by having the base station transmit reservation information in the DCI before the actual data reception. This preliminary indication of reserved RE locations allows the MTC device to prepare its reception parameters in advance without requiring complex RRC configuration, resolving the contradiction between reception accuracy and configuration complexity.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Systems and methods are disclosed herein that relate to transmitting and receiving a transmission when there is a collision between the transmission and reserved resource elements. In some embodiments, a radio access node for a cellular communications network is disclosed, wherein the radio access node comprises a transceiver, a processor, and memory storing instructions executable by the processor whereby the radio access node is operable to transmit, via the transceiver, a downlink transmission to a wireless device using one or more Physical Resource Blocks (PRBs) that comprise reserved Resource Elements (REs) by puncturing the downlink transmission at positions of the reserved REs. In some embodiments, the downlink transmission is an Enhanced Physical Downlink Control Channel (EPDCCH) transmission or a Physical Downlink Shared Channel (PDSCH) transmission. Further, in some embodiments, the reserved REs are REs utilized for one or more CSI-RSs.