Relay Link Control Channel Mapping for LTE Interference
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Solution Overview
Problem
Current LTE systems face challenges in transmitting control information from an eNode-B to a relay node due to interference and limitations in using MBSFN subframes, which restricts the ability of relay nodes to receive control information simultaneously with sending data to User Equipment (UE).
Innovation Solution
Implementing a method for transmitting a relay link control channel using Frequency Division Multiplex (FDM) or Time Division and Frequency Division Multiplex (TDM-FDM) modes, where control information is mapped across resource blocks and OFDM symbols in a subframe, allowing the eNode-B and relay node to determine the quantity and positions of resource blocks for carrying control information based on cell ID, enabling flexible scheduling and frequency diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MBSFN subframes are used for relay link control channel transmission, then coverage and capacity are improved, but interference occurs between eNode-B to relay node link and relay node to UE link
Solution Approach 1:
The patent segments the control channel transmission into two distinct time periods: first control information (sent before the subframe boundary) and second control information (sent after the subframe boundary). This temporal segmentation allows the relay node to separate its receiving function (first control information) from its transmitting function (second control information to UE), eliminating self-interference while maintaining coverage and capacity benefits of MBSFN subframes.
Solution Approach 2:
The patent implements periodic action by using specific subframe configurations (e.g., subframes 0, 5, and configured MBSFN subframes) for relay control channel transmission. The control information is transmitted in a periodic manner with defined time offsets and subcarrier spacing, allowing the system to achieve reliable control information delivery while avoiding interference through structured periodic scheduling.
2Use of energy by moving object
If control channel and service channel are separated in time (TDM mode), then power consumption of UE is reduced, but control channel flexibility is limited
Solution Approach 1:
The patent introduces dynamic configurability through higher-layer parameters that allow the control channel position and structure to be adjusted based on system conditions. The time offset, subcarrier spacing, and resource allocation can be dynamically configured through RRC signaling, enabling the system to adapt between power-saving TDM modes and flexible FDM modes according to traffic requirements and UE capabilities.
Solution Approach 2:
The patent changes key parameters including cyclic shift values, time offsets, and subcarrier spacing to optimize control channel transmission. By modifying these parameters based on cell ID, subframe type, and configuration, the system achieves both power efficiency (through TDM separation) and flexibility (through parameter adjustment) in relay control channel transmission.
3Measurement precision
If blind detection is performed on multiple candidate control channels, then control information accuracy is improved, but detection time and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the relay node with specific control channel parameters through higher-layer signaling before actual transmission. The cyclic shift, time offset, and resource allocation are predetermined based on cell ID and configuration, allowing the relay node to directly decode the control channel without performing extensive blind detection, thus reducing detection time while maintaining accuracy.
Data Source
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AI summary
A method and system for transmitting a relay link control channel are disclosed for realizing the mapping and transmission of a control channel on a link from an eNode-B to a relay node. In the present invention, in a frequency division multiplex mode, control information is carried by one or more resource blocks in the frequency direction and the universal set of OFDM symbols available to a relay link in a subframe in the time direction; in a time division and frequency division multiplex mode, control information is carried by one or more resource blocks in the frequency direction and a subset of OFDM symbols available to a relay link in a subframe in the time direction; in a time division multiplex mode, control information is carried by all the resource blocks in the frequency direction and a subset of OFDM symbols available to a relay link in a subframe in the time direction; and the mapping of the control channel includes mapping in the time direction and/or the frequency direction. The present invention has backward compatibility and can obtain frequency diversity again. The time division multiplex mode can save power consumption, and the frequency division multiplex mode and the time division and frequency division multiplex mode have the advantages of flexible service scheduling.