Relay Reception Subframe MBSFN Configuration for LTE Channel Measurement
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Solution Overview
Problem
Legacy terminals in LTE Rel-8 systems fail to recognize the base station when a relay is involved, leading to inaccurate channel quality measurement and increased demodulation errors due to the absence of cell-specific RS in specific subframes during data transmission from the base station to the relay.
Innovation Solution
Implementing a relay reception subframe (relay-rx-subframe) reported as a Multicast Broadcast Single Frequency Network (MBSFN) subframe, allowing terminals to correctly identify and measure wireless channel quality by distinguishing it from non-MBSFN subframes, even when the relay does not transmit the cell-specific RS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the relay does not transmit cell-specific RS in subframes during the wireless link (eNB-R) interval, then data transmission from base station to relay is enabled, but terminal channel quality measurement becomes inaccurate
Solution Approach 1:
The patent introduces a dummy cell-specific reference signal as an intermediary element that mediates between the relay's data reception function and the terminal's channel measurement function. This dummy RS allows terminals to perform accurate channel quality measurements without interfering with the relay's ability to receive data from the base station during backhaul subframes.
2Measurement precision
If the relay transmits cell-specific RS in all subframes, then terminal channel quality measurement is accurate, but data reception from base station at relay is blocked
Solution Approach 1:
The patent segments the subframe structure into different types (MBSFN subframes and non-MBSFN subframes) with different RS transmission behaviors. In MBSFN subframes, the relay transmits a dummy cell-specific RS for terminal measurement, while in non-MBSFN subframes, the relay receives data from the base station without transmitting RS, thus resolving the conflict between measurement accuracy and data reception.
3Adaptability or versatility
If legacy terminals operate in relay-assisted systems without specific configuration, then system compatibility is maintained, but handover decisions become erroneous and demodulation errors increase
Solution Approach 1:
The patent changes the parameter configuration by configuring MBSFN subframes with specific properties that differ from regular subframes. This parameter change allows legacy terminals to correctly identify which subframes are suitable for channel measurement and handover decisions, preventing erroneous handovers while maintaining system compatibility without requiring new terminal types.
Data Source
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AI summary
Disclosed are a data transmission/reception apparatus and method of a wireless communication system using a relay. The data transmission/reception apparatus of the relay sets a relay reception subframe (hereinafter, referred to as 'relay-rx-subframe'), and reports, to a terminal within a cell coverage, that the set relay-rx-subframe is a Multicast Broadcast Single Frequency Network (MBSFN) subframe, so that a legacy terminal may be provided with services in a wireless communication system using the relay.