On-demand reverse-link pilot transmission for channel estimation
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Solution Overview
Problem
In communication systems, especially in FDD systems, the inefficiency of pilot transmission leads to high interference and resource overhead due to the need for continuous pilot signals from all terminals, limiting the use of advanced scheduling and transmission techniques.
Innovation Solution
Implementing on-demand pilot transmission on the reverse link, where a base station selectively assigns terminals for pilot transmission based on demand, allowing for channel estimation and data scheduling only when necessary, using techniques like wideband or narrowband pilots, and employing advanced methods like beamforming and eigensteering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all terminals transmit pilots continuously, then channel estimation accuracy is improved, but resource overhead and interference increase
Solution Approach 1:
The patent implements dynamic pilot transmission where terminals transmit pilots on-demand based on scheduling decisions rather than continuously. The base station requests pilots from specific terminals before scheduling them for forward link data transmission, making the pilot transmission dynamic and adaptive to actual channel estimation needs.
Solution Approach 2:
The system uses reverse link data transmission to serve the dual purpose of carrying both user data and pilot signals when terminals are scheduled. The terminals themselves provide the channel estimation information through their scheduled transmissions, eliminating the need for separate dedicated pilot transmissions from all terminals.
2Measurement precision
If all terminals transmit pilots continuously, then channel estimation accuracy is improved, but interference to other base stations increases
Solution Approach 1:
The patent extracts the pilot transmission function from continuous operation and implements it only when needed for scheduled terminals. By separating the pilot transmission requirement from universal continuous transmission and applying it selectively to only those terminals being scheduled for forward link data, the harmful interference is significantly reduced.
Solution Approach 2:
Instead of requiring full pilot transmission from all terminals continuously, the patent applies partial action by requesting pilots only from the specific subset of terminals that need channel estimation for upcoming forward link scheduling. This partial action maintains necessary measurement precision while minimizing excessive interference.
3Measurement precision
If pilots are transmitted frequently, then channel estimation accuracy is improved, but system efficiency decreases
Solution Approach 1:
The patent implements periodic on-demand pilot transmission triggered by scheduling events rather than continuous periodic transmission from all terminals. Pilots are requested and transmitted only at specific intervals when the base station needs to schedule terminals for forward link data transmission, maintaining channel estimation accuracy while improving system efficiency.
Data Source
AI summary
Pilots are transmitted on demand on a reverse link and used for channel estimation and data transmission on a forward link. A base station selects at least one terminal for on-demand pilot transmission on the reverse link. Each selected terminal is a candidate for receiving data transmission on the forward link. The base station assigns each selected terminal with a time-frequency allocation, which may be for a wideband pilot, a narrowband pilot, or some other type of pilot. The base station receives and processes on-demand pilot transmission from each selected terminal and derives a channel estimate for the terminal based on the received pilot transmission. The base station may schedule terminals for data transmission on the forward link based on the channel estimates for all selected terminals. The base station may also process data (e.g., perform beamforming or eigensteering) for transmission to each scheduled terminal based on its channel estimate.