Relay Node Signal Format Conversion for Interference Mitigation
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Solution Overview
Problem
In LTE-advanced systems, the inability to distinguish between unicast data and MBMS data transmitted in a MBSFN environment leads to interference, as there is no guarantee that scrambling codes for PDSCH and PMCH can be distinguished, and timing deviations between base stations degrade code identification capabilities.
Innovation Solution
A radio communication system that includes a processor in the second radio station to convert the communication format of a scrambled radio signal, making it distinguishable from the first radio signal, thereby preventing interference by converting MBMS data from the MBSFN communication format to the unicast communication format or single cell MBMS communication format for relay transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MBMS data is transmitted in MBSFN mode using the same radio frequency as unicast data, then broadcast data can be transmitted to multiple base stations simultaneously, but unicast data and MBMS data become indistinguishable causing interference
Solution Approach 1:
The relay node acts as an intermediary device that receives MBMS data from base stations and retransmits it to mobile stations using a different communication format (unicast format with distinct scrambling code), thereby mediating between the MBSFN broadcast transmission and the mobile station reception to prevent interference
Solution Approach 2:
The patent applies different communication formats to different transmission scenarios: MBSFN format for base station-to-relay node transmission and unicast format for relay node-to-mobile station transmission, allowing local differentiation of signal characteristics to enable distinction between broadcast and unicast data
2Device complexity
If the same scrambling code is used for both PDSCH and PMCH, then communication format conversion is simplified, but code identification capability deteriorates due to timing deviations between base stations
Solution Approach 1:
The relay node applies different scrambling codes to different data types in its local transmission: it uses the original MBSFN scrambling code for receiving broadcast data from base stations, but applies a distinct unicast scrambling code when retransmitting to mobile stations, thereby locally differentiating the signals to maintain code identification capability
Solution Approach 2:
The relay node serves as an intermediary that receives signals with one scrambling code from base stations and retransmits them with a different scrambling code to mobile stations, thereby mediating the code identification issue caused by timing deviations between synchronous base stations
Data Source
AI summary
In a radio communication system a first radio station performs communication by the use of a first radio signal. A second radio station receives a second radio signal which is indistinguishable from the first radio signal. A third radio station is in a radio communication area of the first radio station and a radio communication area of the second radio station. A communication format conversion unit generates a third radio signal by converting a communication format of the second radio signal to a communication format which is distinguishable from the first radio signal, and communicates with the third radio station by the use of the third radio signal.