Mobile Wireless Device Frame Structure for Demodulation
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Solution Overview
Problem
Mobile wireless communications devices face increased computational and power demands when demodulating signals with memory, such as CPM or MSK, due to the need to utilize previous signal portions for demodulation, which complicates the decoding process and reduces power efficiency.
Innovation Solution
A frame structure is introduced that includes a data portion and a termination portion, where the termination portion drives the modulation to a known ending state, simplifying demodulation at the receiver and reducing computational load by exploiting this known state, thereby increasing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If modulations with memory (CPM, MSK) are used to improve power amplifier efficiency and reduce PAPR, then power efficiency and transmission range are improved, but computational complexity and memory demands increase due to the need for maximum likelihood sequence estimation
Solution Approach 1:
The transmitter performs preliminary actions by precomputing and storing the relationship between input data sequences and output signal phases in lookup tables. This allows the receiver to simplify demodulation by directly querying these precomputed values rather than performing complex maximum likelihood sequence estimation, thus resolving the contradiction between power efficiency and demodulator complexity.
2Power
If modulations with memory are used to reduce peak-to-average power ratio and increase average transmit power, then transmission range is improved, but the computational load on the receiver increases
Solution Approach 1:
The transmitter creates copies of the precomputed phase information in lookup tables that can be efficiently queried by the receiver. Instead of the receiver performing computationally intensive maximum likelihood sequence estimation, it copies and uses the precomputed phase relationships, significantly reducing receiver computational load while maintaining the power and range benefits of modulations with memory.
3Measurement precision
If maximum likelihood sequence estimation is used to demodulate modulations with memory, then demodulation accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The system performs preliminary computation at the transmitter to precalculate and store phase information in lookup tables. This preliminary action enables the receiver to achieve accurate demodulation through simpler table lookup operations rather than complex maximum likelihood sequence estimation, thus maintaining demodulation accuracy while reducing device complexity and power consumption.
Data Source
AI summary
A mobile wireless communications device may include an antenna, and a transceiver coupled to the antenna. The transceiver may use a modulation having memory for a message in a frame structure including a data portion and a termination portion based upon the data portion. The termination portion may drive the modulation to a desired known ending state. The modulation may include a spread spectrum modulation or a non-spread modulation.