Relay Station MCS Adjustment for Multi-Stage Relay Delay Reduction
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Solution Overview
Problem
In multi-stage relay systems, the usage efficiency of resources is reduced due to constant reception state of relay stations and increased delay, making it difficult to utilize resources effectively, especially when signal attenuation occurs, leading to inefficient retransmissions.
Innovation Solution
Implementing a method where relay stations adjust their Modulation and Coding Scheme (MCS) based on ACK/NACK signals from downstream stations to perform cooperative relay, reducing unnecessary retransmissions and optimizing resource usage by setting the same MCS for successful signal transmission and predicting retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relay stations maintain constant reception state to improve signal reception quality, then reception quality improves, but resource usage efficiency decreases
Solution Approach 1:
The relay station dynamically adjusts its operational state between reception and transmission modes based on ACK/NACK feedback from downstream stations. Instead of maintaining a constant reception state, the relay station transitions to transmission mode when ACK is received, thereby improving resource utilization while maintaining reception quality through selective operational states
Solution Approach 2:
The system implements feedback mechanisms where downstream relay stations send ACK/NACK signals to upstream relay stations based on signal reception quality. This feedback enables upstream relay stations to adjust their behavior (continue receiving or switch to transmission), resolving the contradiction by making reception quality improvement conditional and resource-efficient
2Area of stationary object
If multiple relay stages are used to extend coverage, then coverage area increases, but delay increases
Solution Approach 1:
Relay stations perform preliminary actions by storing received signals in buffers before transmission. When ACK is received indicating successful downstream reception, the relay station can immediately transmit from buffer without waiting for retransmission cycles, reducing delay while maintaining extended coverage through multiple relay stages
Solution Approach 2:
The system maintains continuous useful action by enabling relay stations to switch to transmission mode upon receiving ACK, eliminating idle waiting periods. This continuous operation through multiple relay stages reduces overall delay while preserving the coverage extension benefit of multi-stage relay
3Reliability
If relay stations store signals in buffer and combine at maximum ratio to improve reception quality, then reception quality improves, but device complexity increases
Solution Approach 1:
Instead of all relay stations performing buffer storage and maximum ratio combining, the invention applies this technique selectively. Only relay stations that need to improve reception quality for specific signals perform buffer storage and combining, while others simply forward signals, thereby reducing overall device complexity while maintaining reception quality where needed
Data Source
AI summary
Disclosed is a radio communication device capable of improving the usage efficiency of resources in multi-stage relay to reduce the amount of delay of a relay signal and improving the reception quality of signals by a relay station or a base station. A transmission determining unit 16 determines whether to transmit the relay signal and whether to transmit ACK/NACK on the basis of whether there is an error in the relay signal, and on the basis of ACK/NACK received from a one-hop-downstream radio communication device. An MCS determining unit 17 provided in the transmission determining unit 16 determines an MCS for the relay signal. A transmission instruction generated by the transmission determining unit 16 is output to a buffer 11 and an ACK/NACK generating unit 19. The determined MCS is output to an error correction coding unit 12 and a modulation unit 13. The ACK/NACK generating unit 19 generates ACK when there is no error in the relay signal, and generates NACK when there is an error in the relay signal.