Uplink Data Transmission in LAA Cells via Partial Subframe Allocation
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Solution Overview
Problem
In LTE systems with licensed-assisted access (LAA) cells, the current method of allocating entire subframes for uplink data transmission leads to low probability of channel preemption due to conflicts with WiFi devices, resulting in inefficient spectrum utilization.
Innovation Solution
A terminal device receives resource allocation indication information for a subframe that includes multiple time units, listens for an idle channel before the subframe, and sends uplink data in preempted time-frequency resources within those units, allowing for partial subframe transmission even if the channel is not idle throughout the entire subframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the base station allocates the uplink resource to the UE in an entire subframe format, then the resource allocation is simple and clear, but the probability of channel preemption is low and spectrum utilization is poor
Solution Approach 1:
The patent segments the uplink transmission resource from an entire subframe level to a partial subframe level. The base station allocates resources for only part of the subframe (e.g., first few slots or symbols) instead of the whole subframe, enabling the UE to transmit uplink data in the allocated partial resources while leaving remaining resources available for other uses, thereby improving spectrum utilization while maintaining allocation simplicity
Solution Approach 2:
The patent applies partial action by allocating uplink resources for only a portion of the subframe rather than the entire subframe. The UE performs LBT and transmits data in the allocated partial resources (e.g., first N slots or symbols), and the base station receives data in these partial resources, achieving better spectrum efficiency without requiring full subframe commitment
2Speed
If the UE performs LBT at a short period before the subframe boundary, then the channel access is timely, but conflict with WiFi devices increases and preemption probability decreases
Solution Approach 1:
The patent applies preliminary action by having the UE perform LBT in advance of the allocated partial subframe transmission opportunity. The UE continuously monitors the channel before the allocated resources and prepares for transmission, ensuring timely channel access while the base station is already ready to receive in the pre-allocated partial subframe resources
Solution Approach 2:
The patent introduces dynamic resource allocation where the actual transmission resources can vary within the allocated partial subframe based on LBT outcomes. The UE can transmit in the allocated partial resources if channel is clear, or defer transmission, while the base station dynamically adapts its reception to match the actual UE transmission timing and resource usage
3Productivity
If the UE preempts only some resources in a subframe, then spectrum utilization improves, but the UE cannot send uplink data under current allocation rules
Solution Approach 1:
The patent segments the subframe into allocated partial resources and unallocated resources. The base station explicitly allocates resources for only part of the subframe to the UE, and the UE transmits uplink data in these segmented partial resources. This segmentation enables partial subframe usage while maintaining clear resource boundaries and transmission capability
Solution Approach 2:
The patent changes the resource allocation parameter from full subframe duration to partial subframe duration (e.g., allocating only first N slots or symbols). This parameter change allows the system to utilize only the necessary portion of the subframe for uplink transmission, improving spectrum utilization while maintaining full uplink data transmission capability within the allocated resources
Data Source
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Figure 4(a)
AI summary
The present invention provides an uplink data transmission method and a device. The method includes: receiving, by a terminal device in a subframe m, first resource allocation indication information sent by a network device, where the first resource allocation indication information is used to indicate a first time-frequency resource that is allocated to the terminal device and that occupies a subframe m+n in an LAA cell, and the subframe m+n includes s time units; starting, by the terminal device, to listen on a channel of the LAA cell before the subframe m+n; if detecting, after a start moment of the first time unit and before a start moment of a tth time unit, that the channel is in an idle state, sending uplink data in tth to sth time units, where t is greater than 1 and less than or equal to s; and if detecting, before the start moment of the first time unit, that the channel is in the idle state, sending uplink data in the s time units. Therefore, the uplink data can be efficiently sent, and spectrum utilization of the LAA cell can be improved.