Centralized Channel Estimation for Multi-Carrier Allocation
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Solution Overview
Problem
In TDM multi-carrier systems, uplink traffic is vulnerable to frequency-selective fading due to varying channel characteristics among terminals, making it difficult to coordinate multiple users and optimize sub-carrier allocation, while existing methods increase system complexity and introduce delays.
Innovation Solution
A frame structure with a centralized period for channel estimation and sub-carrier allocation, where terminals transmit probe messages for channel estimation, and network devices allocate suitable sub-carriers, eliminating the need for terminal estimation and feedback channels, allowing for efficient sub-carrier allocation and improved data transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminals perform channel estimation and feedback channels are established for each terminal, then sub-carrier allocation optimization is achieved, but system complexity increases and transmission delays are introduced
Solution Approach 1:
The patent extracts the channel estimation function from individual terminals and centralizes it at the network device. The network device performs channel estimation on uplink probe messages to obtain channel characteristics for all sub-carriers, eliminating the need for terminals to perform estimation and for feedback channels to be established. This resolves the contradiction by maintaining allocation optimization while reducing system complexity.
Solution Approach 2:
The patent introduces probe messages as an intermediary mechanism. Terminals transmit probe messages on uplink sub-carriers, which serve as intermediaries carrying channel information. The network device uses these probe messages to estimate channel characteristics without requiring direct feedback from terminals, thus optimizing sub-carrier allocation while avoiding the complexity of terminal-based estimation and feedback channels.
2Ease of manufacture
If centralized channel estimation is performed by the network device on probe messages, then terminal design is simplified and system complexity is reduced, but rapid global channel characterization must be achieved within limited time
Solution Approach 1:
The patent implements preliminary channel estimation by the network device during the uplink transmission period. The network device performs channel estimation on received probe messages before the downlink transmission period begins, obtaining channel characteristics in advance. This preliminary action allows the system to quickly allocate sub-carriers in the downlink period without time-consuming terminal-based estimation and feedback procedures.
Data Source
AI summary
In order to improve efficiency for sub-carrier allocation in a TDM multi-carrier system, the invention provides a novel frame structure and corresponding method and apparatus. During a centralized short period, each terminal sends a probe message including a predefined sequence to a network device and the network device estimates the channel characteristics for each sub-carrier with respect to each terminal by estimating the received probe message. In this way, sub-carrier allocation can be improved and sub-carriers with good channel characteristics are allocated to appropriate terminals.