LTE TDD Semi-Persistent Scheduling Periodicity Offset for VoIP
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Solution Overview
Problem
In LTE TDD systems, semi-persistent scheduling conflicts arise between retransmitted and newly transmitted packets due to the synchronous HARQ process, especially when combined with TTI bundling in TDD DL/UL Subframe Configuration 1, leading to resource conflicts.
Innovation Solution
The method involves setting a periodicity offset in the semi-persistent scheduling multi-periodicity mode by determining delta values based on the system frame number, allowing for alternate periodicities T1 and T2 to avoid conflicts between retransmitted and newly transmitted packets, thereby scheduling uplink data effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semi-persistent scheduling is used with synchronous HARQ in TDD systems, then resource allocation efficiency is improved, but time confliction occurs between retransmitted and newly transmitted packets
Solution Approach 1:
The patent applies dynamics by making the scheduling periodicity adjustable between two values (T1 and T2) instead of fixed. The base station dynamically selects which periodicity to use based on the system frame number parity, allowing the system to adapt between different scheduling intervals to avoid conflicts between retransmitted and newly transmitted packets while maintaining resource allocation efficiency
Solution Approach 2:
The patent changes the scheduling periodicity parameter between two different values (T1 and T2) depending on the system frame number. When the system frame number is even, one periodicity is used; when odd, the other periodicity is used. This parameter change resolves the time confliction by shifting the scheduling timeline to avoid overlap between HARQ retransmissions and new packet transmissions
2Reliability
If multi-periodicity mode is used to avoid time confliction, then packet transmission reliability is improved, but signaling overhead increases
Solution Approach 1:
The patent implements self-service by enabling the user equipment to automatically determine which periodicity (T1 or T2) to use based on the system frame number parity without requiring explicit signaling from the base station. The UE autonomously selects the appropriate periodicity according to the predefined rule, eliminating the need for additional signaling messages to convey periodicity selection information
Data Source
AI summary
A user uplink data scheduling method and user equipment, which are applied to multiple-periodicity mode semi-persistent scheduling supporting Transmission Timing Interval (TTI) bundling in the second Downlink/Uplink (DL/UL) timing interval proportion configuration mode (Time Division Duplex (TDD) DL/UL subframe configuration 1) in a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) TDD system. The user uplink data scheduling method includes the steps of: acquiring an indication message transmitted from a base station for indicating user uplink data based on the multiple-periodicity mode semi-persistent scheduling; setting a periodicity offset of the multiple-periodicity mode semi-persistent scheduling; determining the periodicities of the multiple-periodicity mode semi-persistent scheduling of per two adjacent TTI bundles according to the set offset; scheduling user uplink new transmission packet data according to the determined periodicities of the multiple-periodicity mode semi-persistent scheduling. The problem that the new-transmission packet and the re-transmission packet of the same user of the multiple-periodicity semi-persistent scheduling conflict is solved, and signal overhead is reduced when TTI bundling supports the VoIP service and so on.