Uplink Time Alignment Timer for Wireless Devices
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Solution Overview
Problem
Wireless communication devices face challenges in maintaining uplink timing alignment due to congestion and timeslot allocation, leading to subframes where they are not synchronized with the network, resulting in delays and inefficiencies.
Innovation Solution
Implementing a time alignment timer and preemptive request mechanism that allows wireless communication devices to proactively request uplink timing alignment before the current grant expires, ensuring continuous synchronization with the network by identifying and utilizing available subframes for timing alignment requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless devices wait for network grants to request uplink timing alignment, then network control is maintained, but uplink timing alignment is lost during congestion and timeslot allocation delays occur
Solution Approach 1:
The patent implements a time alignment timer that proactively triggers uplink timing alignment requests before the current alignment grant expires. This preliminary action prevents the device from falling into an unsynchronized state, eliminating the need to wait for network grants during congestion. The timer monitors the remaining validity period of the uplink timing alignment grant and initiates a new alignment request when a threshold is approached, ensuring continuous synchronization.
2Reliability
If wireless devices request uplink timing alignment frequently, then continuous synchronization is maintained, but network congestion increases and resource overhead increases
Solution Approach 1:
The patent employs dynamic adjustment of the time alignment timer threshold based on network conditions and device state. The threshold can be modified by network configuration parameters, allowing the system to adapt the frequency of alignment requests. When network conditions are favorable, the threshold can be set to trigger requests slightly before expiration. When congestion is detected, the threshold can be adjusted to reduce request frequency, optimizing the balance between maintaining synchronization and minimizing network overhead.
Solution Approach 2:
The system implements feedback mechanisms where the network responds to timing alignment requests with grants that include validity duration information. The device uses this feedback to adjust its timer settings and determine when to initiate the next alignment request. This closed-loop feedback ensures that alignment requests are made only when necessary, preventing excessive networking traffic while maintaining continuous synchronization.
3Ease of operation
If wireless devices use traditional wait-for-grant mechanisms, then network control is maintained, but communication delays occur during timeslot allocation
Solution Approach 1:
By proactively initiating uplink timing alignment requests before the current grant expires, the device eliminates the waiting period that occurs with traditional mechanisms. The preliminary action ensures that the device maintains synchronization without needing to wait for network timeslot allocation decisions, significantly reducing the speed of alignment restoration while the network retains control through timer configuration and grant validation.
Data Source
AI summary
A method for wireless communication is disclosed. A time alignment timer is started. It is determined when the time alignment timer will expire. A time alignment request subframe that is prior to the time alignment timer expiring is identified. Uplink time alignment is requested in the time alignment request subframe.