Convolution Encoder Input Shaping for Energy-Efficient Symbol Selection
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Solution Overview
Problem
Conventional IEEE 802.11x transmitters are not energy efficient, limiting the ability to reduce transmit power in dense user environments, such as vehicular networks, due to equal probability symbol selection from a hypercube in the constellation diagram, which does not reach channel capacity.
Innovation Solution
An input selector that shapes the input for the convolution encoder to select symbols from a k-dimensional hypersphere instead of a hypercube, increasing energy efficiency by probabilistically selecting lower energy symbols, allowing for rate adaptivity without changing the code rate or constellation, using an enumerative algorithm for efficient amplitude selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If symbols are selected with equal probability from a hypercube in the constellation diagram, then the transmitter operates with simple symbol selection, but energy efficiency is poor and transmit power cannot be reduced
Solution Approach 1:
The patent changes the geometric parameters of the constellation diagram by selecting symbols from an n-dimensional hypersphere instead of a hypercube. This parameter change in the selection space fundamentally improves energy efficiency while maintaining compatible transmitter structure
Solution Approach 2:
The input selector pre-processes the input bits by shaping them according to the hypersphere geometry before encoding. This preliminary shaping action ensures that the encoded symbols will naturally fall within the energy-efficient hypersphere region, avoiding the need for complex post-processing
2Productivity
If symbols are selected from a hypercube, then the constellation structure is simple, but channel capacity is not reached and energy efficiency is limited
Solution Approach 1:
The patent transforms the constellation selection from a hypercube geometry to a hypersphere geometry by changing the mathematical parameters of the symbol selection process. This allows the system to reach channel capacity while keeping the transmitter structure compatible with IEEE 802.11 standards
3Power
If conventional IEEE 802.11x symbol selection is used, then the transmitter is simple to implement, but transmit power must remain high to maintain reliability in dense user environments
Solution Approach 1:
By changing the symbol selection geometry from hypercube to hypersphere, the patent improves the signal-to-noise ratio performance, allowing transmit power to be reduced while maintaining signal reliability in dense vehicular network environments
Data Source
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AI summary
An input selector for selecting an input of a convolution encoder of a transmitter is disclosed. The input selector comprises a shaper block and an input-select block. The shaper block is configured to receive an input comprising a first number of input bits, the shaper block configured to generate a shaped bit stream corresponding to the first number of input bits. The input-select block is configured to generate an encoder input bit stream for the encoder based on the shaped bit stream, wherein the input-select block generates the encoder input bit stream such that, when input into the encoder, a first bit of the encoder input bit stream sets a state of the encoder in order that a subsequent second bit of the encoder input bit stream causes the encoder to generate a bit of the shaped bit stream at a pre-determined position in an encoder output bit stream.