Secondary Pilot Channel Power Modulation for CDMA2000
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently boosting pilot channel transmission levels, particularly in CDMA2000 Release D systems, due to limitations in conveying timely and optimal information about the Reverse Secondary Pilot Channel (R-SPICH) transmission levels, leading to suboptimal decoding and increased complexity in receivers.
Innovation Solution
A method and apparatus that modulate the Secondary Pilot Channel (SPICH) using Quadrature Phase-Shift Keying (QPSK) to convey information about its transmission level, allowing for optimal combination with the primary Pilot Channel (PICH), enabling timely and accurate demodulation of traffic channels by determining relative transmission levels and minimizing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the R-SPICH transmission power level is increased to enhance pilot channel combining accuracy, then the phase reference precision is improved, but the transmission power consumption increases and interference to other channels increases
Solution Approach 1:
The patent applies dynamic power adjustment by transmitting the R-SPICH at different power levels (first power level and second power level) depending on the data rate and channel conditions. The power level is not fixed but adapts dynamically to match the associated data channel requirements, optimizing the balance between pilot combining accuracy and power consumption.
Solution Approach 2:
The patent changes the transmission power parameter of the R-SPICH based on data rate and channel conditions. By varying the power level parameter dynamically, the system achieves optimal pilot channel combining for different operating conditions without unnecessarily increasing power consumption or interference.
2Reliability
If the R-SPICH transmission power is made variable to match data rates, then the decoding accuracy is improved, but the receiver complexity increases due to need for timely information about transmission levels
Solution Approach 1:
The patent implements feedback mechanisms where the mobile station transmits information about its data rate and channel conditions back to the base station. This feedback enables the base station to adjust the R-SPICH power level appropriately, ensuring accurate pilot combining while managing receiver complexity through informed control decisions.
Solution Approach 2:
The mobile station autonomously determines its data rate and channel conditions, and this self-assessment information is used to control the R-SPICH power level. The system serves itself by using the mobile station's own operational parameters to guide the pilot channel transmission, reducing the need for complex external control.
3Reliability
If the R-SPICH is transmitted at high power to ensure adequate reception accuracy, then the data channel decoding is improved, but the interference to other channels increases
Solution Approach 1:
The patent dynamically adjusts the R-SPICH power level based on the associated data channel's requirements. By matching the pilot power to the data rate and channel conditions, the system ensures adequate reception accuracy for high-rate data channels while avoiding excessive power that would cause unnecessary interference to other channels during low-rate or idle periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the effectiveness of pilot channel combinations, improving data reception accuracy and reducing latency, while maintaining backward compatibility and minimizing resource wastage across varying data rates and channel conditions.
Implementation Method 1
modulate the Secondary Pilot Channel (SPICH) using Quadrature Phase-Shift Keying (QPSK) to convey information about its transmission level
Implementation Method 2
the R-SPICH may be combined with the R-PICH to enhance, in steps, the precision of a coherent demodulation phase reference
Data Source
AI summary
In a method and apparatus suitable to convey timely information for facilitating accurate reception of transmitted data, a pilot signal is modulated to convey information. The information may facilitate efficient interpretation of an associated traffic signal. Modulation of a pilot signal frame may be limited to ensure early detection, and/or to minimize impairment of pilot functionality. In one embodiment, a Secondary Pilot Channel (SPICH) is transmitted at one of several selectable power levels to boost effectiveness of a phase reference, and is modulated to indicate the selected level. Such timely information enables prompt optimal combining of the SPICH with a primary Pilot Channel (PICH), and/or permits processing efficiencies for an associated traffic channel. Pilot signal frames may be transmitted at a predetermined level during a detection preamble portion of a frame to ensure accurate and early detection, and at a more optimal level thereafter.