Relay Backhaul Channel Design for In-Band Half-Duplex Wireless Systems
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Solution Overview
Problem
In wireless communication systems, relay nodes face challenges in listening to PDCCH transmissions from donor NodeBs due to the nature of MBSFN subframes, leading to limitations in relay backhaul channel design, particularly in in-band half-duplex operations.
Innovation Solution
The implementation of a relay backhaul channel using FDM, TDM/FDM, or joint R-PDCCH/R-PDSCH channels, which includes specific resource blocks for reference signals to facilitate communication with relay nodes, enabling effective demodulation of control and data channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MBSFN subframes are used to create blank periods for receiving DL communications from donor NodeB, then relay backhaul communication is enabled, but the relay node cannot listen to PDCCH transmissions from the donor NodeB
Solution Approach 1:
The relay backhaul channel is segmented into separate control channel resources and data channel resources. The control channel uses specific resource blocks (RBs) that are exclusively allocated for control signaling, while data channels use different RBs. This segmentation allows the relay node to properly receive and process control information without interference from data transmissions during MBSFN intervals.
Solution Approach 2:
A dedicated relay backhaul control channel is introduced as an intermediary between the donor NodeB and the relay node. This control channel carries control information specifically designed for relay backhaul operations, separate from the standard PDCCH used for UE communications. The control channel includes reference signals and control elements that enable the relay node to correctly interpret backhaul control messages during MBSFN subframes.
2Productivity
If in-band half-duplex operation is implemented for relay nodes, then frequency efficiency is improved, but communication reliability deteriorates due to inability to transmit and receive on the same band simultaneously
Solution Approach 1:
The in-band resources are segmented into distinct control channel regions and data channel regions within the same frequency band. The control channel is allocated specific resource blocks that are protected from data transmissions, allowing the relay node to reliably receive control signaling even while operating in half-duplex mode. This segmentation ensures that control information is not corrupted by simultaneous data transmissions.
Solution Approach 2:
Different quality requirements are applied to different parts of the relay backhaul channel. Control channel resources are allocated with higher protection and dedicated reference signals to ensure high reliability for control signaling. Data channel resources use standard allocation with appropriate coding and modulation. This local quality differentiation ensures that the critical control functions maintain high reliability while allowing flexible data transmissions.
Data Source
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AI summary
An apparatus and method for designing a relay backhaul channel in a wireless communication system are provided. At least one relay node utilized for communication with respective user devices and at least one relay backhaul channel for conducting in-band half-duplex communication with the at least one relay node are identified. The relay backhaul channel may be an FDM channel, a TDM/FDM channel, or a joint R-PDCCH/R-PDSCH channel. The relay channel is used for communicating with the at least one relay node. The supportable ranks of the R-PDSCH channel may depend on the number of resources reserved for demodulation reference signals in the R-PDCCH region.