MIMO-OFDM Subcarrier and Antenna Selection via Channel Metrics
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Solution Overview
Problem
Existing wireless communication systems, particularly OFDM, lack the ability to effectively utilize sub-carrier level resource allocation, leading to inefficient power control and modulation schemes that do not adapt well to varying channel conditions in MIMO systems.
Innovation Solution
The method involves calculating channel metrics for each transmit antenna, allocating sub-carriers based on these metrics, and implementing adaptive modulation and power control on a per-antenna or per-sub-carrier basis, with the option to apply waterpouring only to selected antennas and using SNR as a metric for power allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional OFDM power control and modulation schemes are used, then system implementation is simple, but resource allocation efficiency is poor and does not adapt to varying channel conditions
Solution Approach 1:
The patent applies local quality by implementing per-subcarrier power control and modulation schemes. Each subcarrier is assigned specific modulation orders and power levels based on its individual channel conditions, rather than using uniform parameters across all subcarriers. This allows the system to adapt locally to varying channel quality across the frequency spectrum.
Solution Approach 2:
The patent implements dynamic power control and modulation adaptation based on real-time channel conditions. The system dynamically adjusts power allocation and modulation schemes for different subcarriers and antennas according to measured channel quality, enabling the system to respond to changing propagation conditions rather than using static parameters.
2Productivity
If uniform power allocation is used across all antennas, then implementation is straightforward, but throughput and link margin are not optimized
Solution Approach 1:
The patent changes the power allocation parameter from a uniform value across all antennas to antenna-specific and subcarrier-specific power levels. The system calculates optimal power distribution based on channel metrics for each antenna-subcarrier combination, adjusting power parameters to maximize throughput and link margin rather than using fixed equal allocation.
Solution Approach 2:
The patent segments the power allocation into distinct components for different antennas and subcarriers. Rather than treating the MIMO-OFDM system as a single entity with uniform parameters, the system divides power control into independent controllable units per antenna and per subcarrier, allowing granular optimization of resource distribution.
Data Source
AI summary
A method and apparatus for radio resources control in a multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) communication system are disclosed. Channel metric is calculated for each of a plurality of transmit antennas. Sub-carriers are allocated to each transmit antenna in accordance with the channel metric of each transmit antenna. Signals are transmitted using the allocated sub-carriers at each antenna. Adaptive modulation and coding and transmit power control of each sub-carrier may be further implemented in accordance with the channel metric. Power control may be implemented per antenna basis or per sub-carrier basis. In performing power control, a subset of transmit antennas may be selected and waterpouring may be applied only to the selected antennas. Waterpouring may be based on SNR instead of channel response.