NB-IoT TDD Scheduling Delay Parameter for Collision Avoidance
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Solution Overview
Problem
Conventional NB-IoT systems face challenges in scheduling wireless transmissions using Time Division Duplex (TDD) due to the need to arrange uplink and downlink resources without collision, as they must be interleaved in different time periods on the same frequency band, leading to inefficiencies in scheduling delay management.
Innovation Solution
A base station and user equipment system that determines a parameter of scheduling delay, allowing the user equipment to calculate a target subframe for wireless transmission based on the parameter and a reference subframe in a sequence of TDD subframes, excluding unavailable subframes to avoid collisions and optimize resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If TDD is adapted for scheduling wireless transmissions with the same method as FDD, then the scheduling delay problem can be solved, but uplink and downlink resources will collide since they must be interleaved in different time periods on the same frequency band
Solution Approach 1:
The patent segments the TDD subframes into different categories (downlink subframes, uplink subframes, special subframes) and applies different scheduling rules to each category. The base station transmits downlink control information in downlink subframes, and the user equipment performs uplink transmission in uplink subframes after processing in special subframes, thereby avoiding resource collision while maintaining efficient scheduling.
Solution Approach 2:
The patent introduces dynamic scheduling parameters including scheduling delay values and subframe category indicators that allow the system to adaptively adjust the timing relationship between downlink control information and uplink transmission based on the specific TDD configuration, avoiding fixed timing assumptions that would cause collisions.
2Ease of operation
If uplink and downlink resources are arranged in different frequency bands (FDD), then scheduling can be performed independently without collision, but resource utilization efficiency decreases due to separate frequency allocation
Solution Approach 1:
The patent merges uplink and downlink resources into the same frequency band by using TDD, where different time slots within the same frequency band are allocated for different directions. This combines the frequency resources while using time division to maintain scheduling independence, thereby improving resource utilization efficiency.
Solution Approach 2:
The patent transitions from frequency-based resource separation (FDD) to time-based resource separation (TDD), adding the time dimension as the primary separator between uplink and downlink resources. This dimensional change allows more flexible resource allocation and improves overall resource utilization while maintaining scheduling independence through time-domain coordination.
Data Source
AI summary
A wireless transmission method for Narrow Band-Internet of Things (NB-IoT) includes: receiving, by a user equipment, a parameter of scheduling delay from a base station; calculating, by the user equipment, a target subframe, designated by the base station, in a sequence of Time-Division Duplex (TDD) subframes according to the parameter of scheduling delay and a reference subframe in the sequence of TDD subframes; and performing, by the user equipment, a wireless transmission with the base station in the target subframe; wherein the parameter of scheduling delay corresponds to the number of available subframes between the reference subframe and the target subframe in the sequence of TDD subframes, and categories of the available subframes are related to the direction of the wireless transmission.