Processor Power Mode Switching for Wireless Channel Estimation
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Solution Overview
Problem
In wireless communication networks, particularly in LTE, there is a challenge in balancing channel estimation accuracy and power consumption during periods of no transmission, as continuous monitoring for accuracy increases power consumption, while relying on prior reference symbols for power savings can result in lower accuracy and incorrect channel estimation.
Innovation Solution
A method where a processor determines sets of consecutive subframes with no scheduled transmission, switches between power modes to conserve energy, and uses strategically selected reference symbols, such as those in the zero-th and eleventh OFDM symbols of subframes, to calculate wireless properties like channel estimation, optimizing between power savings and accuracy based on transmission gap duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous monitoring is performed during periods of no transmission to maintain channel estimation accuracy, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The processor enters a low-power mode during periods of no transmission and periodically wakes up to receive reference symbols at specific intervals (e.g., every 10th subframe or at designated OFDM symbols). This periodic monitoring maintains channel estimation accuracy while significantly reducing power consumption compared to continuous monitoring, as the processor remains dormant during intervals between reference symbol receptions.
Solution Approach 2:
The system pre-identifies the locations of reference symbols in advance based on known transmission patterns. During low-power mode, the processor is scheduled to wake up only at these pre-determined reference symbol locations. This preliminary identification allows the processor to efficiently switch to active mode only when necessary, optimizing the balance between maintaining measurement precision and minimizing energy usage.
2Measurement precision
If the processor remains in active mode during all subframes, then channel estimation accuracy is maintained, but power consumption increases
Solution Approach 1:
The processor alternates between active and low-power modes based on the periodic transmission pattern of reference symbols. During low-power mode, the processor consumes minimal energy, and during active mode, it processes received reference symbols to maintain accurate wireless property calculations. This periodic operation dramatically reduces average power consumption while preserving measurement accuracy.
Solution Approach 2:
The system extracts only the essential reference symbol reception operations from the continuous processing stream. Instead of maintaining full processor functionality during all subframes, only the critical function of receiving and processing reference symbols is preserved in active mode, while all other processing functions are suspended during low-power mode. This extraction allows significant power savings without compromising the essential channel estimation function.
3Use of energy by stationary object
If the processor enters low-power mode during all subframes with no transmission, then power consumption is reduced, but channel estimation accuracy deteriorates
Solution Approach 1:
The processor enters low-power mode during most subframes with no transmission but periodically wakes up to receive reference symbols at predetermined intervals (e.g., every 10th subframe or at specific OFDM symbols within subframes). This periodic activation ensures that channel estimation accuracy is maintained by regularly updating wireless property calculations with fresh reference symbol data, while still achieving significant power savings during the intervals when the processor remains in low-power mode.
Solution Approach 2:
Reference symbols serve as intermediaries that bridge the low-power and active states. The processor uses these periodically transmitted reference symbols as mediator data points to maintain accurate channel estimation without requiring continuous active processing. The reference symbols carry the essential information needed to update wireless properties, allowing the processor to remain in low-power mode between these intermediary update points.
Data Source
AI summary
A station configured to perform a method for determining a wireless property such as a channel estimate, a channel estimation track, a time tracking loop, and a frequency tracking loop. The method includes determining a set of consecutive subframes in which no transmission is scheduled, placing a processor into a first power mode during at least a portion of the set of consecutive subframes, placing the processor into a second power mode during at least another portion of the set of consecutive subframes, receiving a first reference symbol when the processor is in the second power mode and calculating a wireless property based on the first reference symbol.