Pilot Tone Power Allocation for HRPD Slot Boundary Errors
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Solution Overview
Problem
In high-rate packet data (HRPD) mobile communication systems using the OFDM transmission scheme, the channel estimation performance varies significantly based on the position of OFDM symbols within a slot, leading to higher reception error probabilities for symbols at slot boundaries due to inconsistent power allocation to pilot and data tones.
Innovation Solution
An apparatus and method that adjust the power ratio of pilot tones to data tones based on the position of OFDM symbols within a slot, allowing for variable power allocation to improve channel estimation and reception performance by setting different pilot-to-data tone power ratios for symbols at slot centers and boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed power ratio is allocated to pilot and data tones regardless of OFDM symbol position, then the system complexity is reduced, but the channel estimation performance degrades at slot boundaries
Solution Approach 1:
The patent applies local quality by allocating different power ratios to pilot tones based on their position within the slot. Specifically, pilot tones in OFDM symbols at slot boundaries are allocated a higher power ratio (e.g., 1/4 or 1/3 of total power) compared to pilot tones in central OFDM symbols (e.g., 1/6 or 1/5 of total power). This position-dependent power allocation improves channel estimation accuracy at critical boundary positions without uniformly increasing system complexity.
Solution Approach 2:
The patent implements dynamic power allocation where the pilot-to-data power ratio varies according to the temporal position of the OFDM symbol within the slot structure. The system dynamically adjusts power distribution: higher pilot power for boundary symbols (first and last symbols of each slot) and lower pilot power for central symbols. This dynamic approach optimizes channel estimation performance adaptively while maintaining manageable system complexity through structured power ratio definitions.
2Reliability
If more power is allocated to pilot tones at slot boundaries, then the reception error probability is reduced, but the overall power efficiency decreases
Solution Approach 1:
The patent applies local quality by concentrating higher power allocation specifically for pilot tones in OFDM symbols located at slot boundaries, where channel estimation is most critical due to potential interference and fading. The power ratio is locally optimized at these boundary positions (e.g., pilot power = 1/4 of total power) while using lower ratios for central symbols (e.g., pilot power = 1/6 of total power), thereby improving reliability where needed without uniformly sacrificing power efficiency across the entire transmission.
Solution Approach 2:
The patent changes the power allocation parameter dynamically based on symbol position. By defining different power ratios (α for boundary symbols, β for central symbols where α > β), the system optimizes the balance between reliability and power efficiency. This parameter change ensures sufficient pilot power at critical boundary positions to reduce reception errors while maintaining better overall power efficiency compared to uniform high power allocation across all symbols.
Data Source
AI summary
An apparatus and method transmits a packet data symbol in a high-rate packet data (HRPD) mobile communication system for broadcasting service. A transmission processor generates a modulated symbol by encoding, interleaving and modulating a physical layer packet to be transmitted, and arranges the modulated symbol in a data tone. A tone inserter inserts a guard tone and a pilot tone into the data tone. A tone power allocator sets a different pilot-to-data tone power ratio according to a position of a slot, in which the packet data symbol is included, and allocates power according to the pilot-to-data tone power ratio. A transmitter transmits the packet data symbol.