Wireless Access Method Switching for Power Headroom Constraints
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Solution Overview
Problem
In wireless communication systems, Adaptive ARQ retransmission control does not consider Power Headroom (PH), leading to transmission power shortages for users with limited PH, such as cell-edge users, resulting in incorrect data reception by base stations.
Innovation Solution
The system selects an access method with lower peak power for retransmissions, allocates transmission signals to contiguous frequency bands, and increases transmission power based on PH, using multiple antennas with high channel gain to ensure sufficient power and improve cell throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Adaptive ARQ retransmission control is used to improve data transmission reliability, then retransmission can be performed with different parameters, but transmission power shortages occur for users with limited Power Headroom
Solution Approach 1:
The patent dynamically switches between different access methods (SC-FDMA and DFT-S-OFDM) based on the mobile station's Power Headroom status. When PH is insufficient, the system transitions from the original access method to an alternative with lower peak power requirements, enabling flexible adaptation to power constraints while maintaining retransmission capability
Solution Approach 2:
The patent changes the access method parameter (switching between SC-FDMA and DFT-S-OFDM) to alter the peak power characteristics. By selecting an access method with different power properties, the system can perform retransmission within the available power budget while still achieving reliable data transmission
2Productivity
If access methods with high peak power are used to improve transmission performance, then data transmission efficiency is enhanced, but users without sufficient Power Headroom cannot perform retransmission
Solution Approach 1:
The system dynamically adapts the access method selection based on real-time Power Headroom conditions. For initial transmission, high-performance access methods can be used, but for retransmission when PH is limited, the system switches to power-efficient access methods, ensuring both transmission efficiency and retransmission capability are maintained appropriately
3Measurement precision
If retransmission is performed with increased transmission power to ensure correct reception, then data reception accuracy is improved, but Power Headroom constraints prevent further power increase
Solution Approach 1:
Instead of increasing power within the same access method, the patent changes the access method parameter to one with lower peak power requirements. This allows the system to achieve sufficient reception accuracy through a different transmission approach that is compatible with the available Power Headroom
Solution Approach 2:
The patent uses a different access method as an alternative copy of the transmission mechanism. When the original access method cannot achieve correct reception due to power constraints, the system employs an alternative access method that achieves the same goal of correct data reception within the power budget
Data Source
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AI summary
An access method, transmission power, an antenna to be used, and the number of antennas are controlled in consideration of a PH indicating a transmission power headroom. A wireless communication system which includes a base station and a mobile station and in which the mobile station performs data transmission to the base station by allocating a transmission signal converted into a frequency signal to contiguous frequency bands or non-contiguous frequency bands divided into a predetermined number, wherein, when retransmission occurs in the data transmission the mobile station has performed by allocating the transmission signal converted into the frequency signal into the non-contiguous frequency bands, the base station determines a transmission power headroom of the mobile station in the allocation of the transmission signal to the non-contiguous frequency bands, and, if a result of the determination shows that there is not a transmission power headroom, the base station instructs the mobile station to allocate the transmission signal to the contiguous frequency bands and to perform the retransmission by increasing transmission power.