Relay Node Subframe Allocation for Self-Interference Reduction
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Solution Overview
Problem
The existing LTE wireless communication network's relay operation in Release 8 (Rel-8) FDD mode faces challenges with self-interference and incompatible HARQ timing due to the use of the same frequency band for both transmission and reception at relay nodes, which complicates the allocation of subframes and HARQ control handling.
Innovation Solution
A method is introduced where downlink subframes for the radio access node to relay node communication are allocated only when the corresponding subframe for relay to user equipment transmission is of a type that indicates no data is received beyond the control region, ensuring uplink subframes are allocated four transmission time intervals later, allowing for HARQ process management and minimizing self-interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the relay node uses the same frequency band for both transmission and reception, then spectrum efficiency is improved, but self-interference occurs between transmission and reception
Solution Approach 1:
The patent segments the time domain into different subframe types (MBSFN subframes and non-MBSFN subframes) to separate transmission and reception operations. By configuring certain subframes as MBSFN subframes where the relay node does not transmit data beyond the control region, the system creates temporal separation between transmission and reception, allowing the relay node to receive from donor eNB without self-interference while still using the same frequency band.
2Object-generated harmful factors
If MBSFN subframes are configured for relay-user equipment links, then self-interference is avoided, but HARQ timing compatibility with Rel-8 is lost
Solution Approach 1:
The patent introduces dynamic HARQ timing adjustment mechanisms that adapt to the MBSFN subframe configuration. The HARQ feedback timing is dynamically determined based on the subframe type and the configured MBSFN pattern, allowing the system to maintain HARQ operations while accommodating the periodicity differences between MBSFN patterns (10ms or 40ms) and uplink HARQ (8ms). This dynamic adaptation enables compatibility with Rel-8 timing where possible while supporting inband relaying requirements.
3Productivity
If downlink subframes are allocated for eNB-RN transmission, then backhaul communication is enabled, but uplink subframe allocation becomes constrained
Solution Approach 1:
The patent applies preliminary action by pre-configuring MBSFN subframe patterns and determining the set of candidate subframes for downlink transmission before actual resource allocation. The donor eNB configures the relay node with a pattern indicating which subframes are MBSFN subframes, and this configuration is used beforehand to determine HARQ timing and allocate uplink subframes. This preliminary configuration simplifies the allocation process by establishing rules in advance rather than making complex decisions in real-time.
Data Source
AI summary
The present invention relates to a transmission of information in a wireless communication network between a radio access node and a relay node, wherein, according to a new ground rule, for each allocated downlink subframe for a downlink transmission from the access node to the relay node, an uplink transmission subframe for an uplink transmission is allocated four transmission time intervals later. A downlink subframe is only allocated when a further subframe of the same transmission time interval for a transmission from the relay node to the user equipment is a subframe of a type that indicates to a user equipment that no data are received beyond a control region of the subframe.