Relay Station Offset Signaling for Control Channel Capacity
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Solution Overview
Problem
In mobile communication systems with multiple radio access technologies (RATs), the conventional method requires a control channel of large capacity to report RAT information, which becomes insufficient as the number of mixed RATs increases, leading to potential channel capacity issues.
Innovation Solution
A relay station configuration that adds a frequency, time, or power offset to signals from a base station, allowing a mobile station to detect its coverage area without needing a control channel for RAT information reporting, by relaying signals with these offsets between different RAT coverage areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a control channel is used to report RAT information to mobile stations, then mobile stations can detect their coverage area and available services, but the control channel capacity becomes insufficient as the number of mixed RATs increases
Solution Approach 1:
The patent extracts the RAT information reporting function from the control channel and implements it through physical layer signaling (reference signal offsets) in the data channel. This separates the information delivery mechanism from the control channel, allowing RAT coverage area detection without consuming control channel capacity.
Solution Approach 2:
The patent introduces reference signal offsets as an intermediary mechanism to convey RAT information. Instead of directly reporting RAT information through the control channel, the system uses offset values in reference signals as a mediator to indirectly indicate coverage area and available services, reducing control channel overhead.
2Area of stationary object
If relay transmission is used to expand base station coverage area, then fewer base stations are needed, but the system complexity increases with multiple RATs and coverage area detection requirements
Solution Approach 1:
The patent changes the parameter space by using reference signal offsets (frequency, time, or power domain offsets) as a compact representation of RAT coverage information. This parameter-based approach simplifies the system by encoding multiple pieces of coverage area information into a single offset value, reducing detection complexity.
Solution Approach 2:
The patent makes the reference signal offset mechanism universal across multiple RATs. The same offset-based indication method works for different radio access technologies (LTE, WLAN, WiMAX), providing a unified approach for coverage area detection that reduces overall system complexity despite the presence of multiple RATs.
Data Source
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AI summary
Provided is a mobile communication system which includes a plurality of RAT (Radio Access Technology) and can eliminate the need of a control channel for reporting RAT information so as to prevent congestion or shortage of the control channel capacity. In the mobile communication system, an LTE relay station (30) has a cover area (31) identical to a cover area (21) owned by a WLAN host station (20) and relays/transmits the signal received from an LTE base station (10) to a mobile station (40) in the cover area (31). The LTE relay station (30) adds to the signal received from the LTE base station (10), one of the offsets: a frequency offset, a time offset, and a power offset as information indicating that the mobile station (40) which receives a relay signal from the local station is located in the cover area (21) of WLAN and transmits the signal after offset addition to the mobile station (40) located in the cover area (31) (i.e., the cover area (21)).