Modified IM-OFDM Subcarrier Segmentation for Energy Efficiency
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Solution Overview
Problem
Existing OFDM-based communication systems face challenges in balancing energy efficiency and spectral efficiency, leading to increased energy consumption and greenhouse gas emissions, particularly in mobile terminals and IoT applications.
Innovation Solution
A new spectral-energy-efficient transmission scheme for OFDM-based communication systems is introduced, which uses a modified IM-OFDM technique that increases the total number of transmit data bits via a given set of subcarriers while significantly reducing energy consumption by forcing some subcarriers to be silent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If standard OFDM modulation is used to transmit data, then spectral efficiency is maintained at conventional levels, but energy consumption increases significantly
Solution Approach 1:
The patent segments the OFDM subcarriers into active and inactive sets, where only a subset of subcarriers is activated for data transmission in each OFDM symbol. This segmentation allows the system to reduce energy consumption by deactivating unnecessary subcarriers while maintaining acceptable spectral efficiency through careful selection of active subcarriers that carry the most important data bits.
Solution Approach 2:
The patent dynamically adjusts the set of active subcarriers based on the data bits to be transmitted. By varying which subcarriers are activated across different OFDM symbols, the system achieves flexible energy-efficient transmission that adapts to different data rates and channel conditions, resolving the contradiction between energy saving and transmission productivity.
2Productivity
If more subcarriers are activated to increase data transmission capacity, then spectral efficiency improves, but energy consumption increases proportionally
Solution Approach 1:
The patent applies partial action by activating only a subset of available subcarriers rather than all subcarriers simultaneously. This allows the system to transmit data at reduced rates when energy saving is prioritized, or to activate more subcarriers when higher data rates are needed, creating a flexible trade-off between energy consumption and transmission capacity.
Solution Approach 2:
The patent changes the parameter of subcarrier activation status (active/inactive) to control the balance between energy consumption and data transmission capacity. By varying the number and selection of active subcarriers as a controllable parameter, the system can adjust its operating point along the energy-capacity trade-off curve.
3Productivity
If index modulation techniques are used to enhance spectral efficiency, then data transmission capacity increases, but detection complexity increases
Solution Approach 1:
The patent segments the data bits into two sets: those modulated on active subcarriers and those conveyed through the index selection itself. This segmentation allows the receiver to process data in two distinct stages - first detecting the active subcarrier pattern (index modulation) and then decoding the modulated symbols, which simplifies the overall detection process compared to treating all bits uniformly.
Solution Approach 2:
Instead of modulating all data bits directly on subcarriers (conventional approach), the patent inverts the approach by using the subcarrier selection pattern itself to convey information. This inversion shifts the detection burden from processing all modulated symbols to identifying the active subcarrier pattern, which can be more efficient with appropriate detection algorithms.
Data Source
AI summary
A method for data transmission using OFDM-based communication systems comprising the steps of obtaining a binary vector to be transmitted; converting the binary vector in a b base vector, being b a base greater than 2. Encoding the b base vector by means of a modulation technique; Transmitting the encoded vector via multi-subcarriers, using an OFDM transmission scheme.