ACK/NACK Resource Allocation in NB-IoT TDD Systems
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Solution Overview
Problem
The existing mechanism for allocating ACK/NACK resources in NB-IoT FDD systems does not apply to TDD systems, as multiple subframe offsets can correspond to the same uplink ACK/NACK start subframe, failing to achieve time domain reuse and reducing flexibility in resource allocation.
Innovation Solution
A method for allocating ACK/NACK resources in NB-IoT TDD systems that involves generating allocation information with an offset indication for the start time of acknowledgment message transmission resources, allowing flexible allocation of uplink time-frequency resources, including time-domain and frequency-domain resources, to ensure effective ACK/NACK transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the existing FDD-based ACK/NACK resource allocation mechanism is applied to TDD systems, then the implementation complexity is reduced, but the resource utilization efficiency deteriorates due to multiple subframe offsets mapping to the same uplink start subframe
Solution Approach 1:
The patent changes the parameter used for resource allocation from subframe offset to uplink slot index. By using the formula n+k0 where n is the downlink slot index and k0 is the offset in uplink slots, the system achieves both simplicity and efficient resource utilization in TDD mode, avoiding the collision problem where multiple offsets map to the same resource.
2Ease of operation
If the FDD subframe offset mechanism is used in TDD systems, then the allocation mechanism remains simple and familiar, but the flexibility in resource allocation deteriorates due to the unique TDD uplink-downlink subframe configuration
Solution Approach 1:
The patent introduces dynamic adaptability by configuring different k0 offset values based on TDD uplink-downlink configurations. The system can dynamically adjust the offset parameter to match different TDD scenarios, making the allocation mechanism both simple to operate and flexible enough to handle various TDD configurations.
Solution Approach 2:
By changing from fixed subframe offset to dynamic uplink slot index with configurable k0 offset, the system maintains operational simplicity while achieving flexibility. The parameter transformation allows the same basic mechanism to work across different TDD configurations without complex adjustments.
3Adaptability or versatility
If multiple subframe offsets are allowed in TDD systems, then the scheduling flexibility is improved, but the time domain reuse fails because multiple offsets correspond to the same uplink ACK/NACK start subframe
Solution Approach 1:
The patent transitions from one-dimensional subframe offset to two-dimensional indexing by combining downlink slot index n with uplink slot offset k0. This dimensional change allows multiple combinations to map to different uplink resources, achieving both scheduling flexibility and time domain reuse by distributing resources across different uplink slots.
Data Source
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AI summary
The present disclosure provides an acknowledgment message resource allocation method applicable to an NB-IoT TDD cell, and a corresponding base station and corresponding user equipment for performing the method. The user equipment according to an embodiment of the present invention includes: a receiving unit, configured to receive allocation information of acknowledgment message transmission resources, the allocation information including offset indication information instructing an offset j0 of a start time of the acknowledgment message transmission resources with respect to a reference time, and the offset jo instructing an offset expressed by a number of NB-IoT uplink slots; and a transmitting unit, configured to perform acknowledgment message transmission based on the allocation information.