Uplink Channel Alignment via Timing Offset for PAR Reduction
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Solution Overview
Problem
The peak-to-average power ratio (PAR) increases when additional uplink dedicated physical channels are multiplexed in UMTS systems, leading to potential signal distortion and increased amplifier costs, particularly for high-speed data users utilizing both HSDPA and EU-DCH services.
Innovation Solution
Aligning physical channels with a timing offset to avoid simultaneous transmission and code multiplexing, thereby reducing the PAR when multiplexing EU-DPCCH and EU-DPDCH with other channels, and ensuring they are not transmitted at the same time as HS-DPCCH, using timing offset information assigned by the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional uplink dedicated physical channels are code multiplexed to support EU-DCH services, then system capacity and service versatility are improved, but the peak-to-average power ratio increases causing signal distortion and requiring more expensive amplifiers
Solution Approach 1:
The patent segments the uplink transmission time into different time slots, separating the transmission of EU-DPCCH/EU-DPDCH from HS-DPCCH. By dividing the time domain, the system allows multiple physical channels to be multiplexed without simultaneous transmission, thus controlling the peak-to-average power ratio while maintaining service versatility.
Solution Approach 2:
The patent implements periodic transmission patterns where EU-DPCCH and EU-DPDCH are transmitted in specific time slots alternating with HS-DPCCH transmissions. This periodic separation ensures that channels are not simultaneously active, preventing PAR increase while enabling multiple services.
2Productivity
If physical channels are transmitted simultaneously for efficient data transmission, then productivity is improved, but the peak-to-average power ratio increases leading to signal distortion
Solution Approach 1:
The patent segments the transmission timeline into distinct slots for different physical channels. By separating HS-DPCCH and EU-DPCCH/EU-DPDCH transmissions in time, the system maintains efficient data transmission while preventing signal distortion caused by simultaneous high-power channel transmissions.
Solution Approach 2:
The patent applies preliminary timing offset configuration where the base station pre-calculates and assigns time offset values to mobile stations. This preliminary timing setup ensures that channels are transmitted at appropriate times without overlapping, preventing signal distortion before it occurs.
3Productivity
If more physical channels are multiplexed to support high-speed data services, then system capacity is improved, but amplifier costs increase due to higher peak power requirements
Solution Approach 1:
The patent segments the transmission schedule to prevent simultaneous activation of multiple high-power channels. By time-division multiplexing EU-DPCCH, EU-DPDCH, and HS-DPCCH, the system achieves high system capacity while keeping peak power requirements manageable, thus reducing amplifier cost.
Solution Approach 2:
The patent implements dynamic timing offset adjustment where the base station can flexibly assign different time offsets to different mobile stations based on their service requirements. This dynamic scheduling allows the system to optimize between system capacity and peak power consumption, balancing performance and hardware cost.
Data Source
AI summary
In a method for aligning a plurality of physical channels for uplink transmission two or more physical channels may be aligned based on a timing offset so that the two channels are transmitted in the uplink at a time instant different than a time of uplink transmission for a third physical channel. Accordingly, the two physical channels may be code multiplexed with additional physical channels other than the third physical channel to generate a code-multiplexed signal to be used for uplink transmission. The timing offset information may be assigned to the user from a base station, for example, in order to align the two physical channels. Accordingly, an increase in peak-to-average power ratio my be avoided and/or reduced if multiplexing the two physical channels with other physical channels for uplink transmission.