Half-Duplex WTRU Time-Division Oscillator Switching
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Solution Overview
Problem
The migration of Machine-Type Communications (MTC) devices from GSM/GPRS networks to LTE networks is hindered by the need for multiple radio access technologies and inefficient spectrum usage, with low-cost MTC devices requiring reduced RF component count and simpler implementation to minimize costs and maintain spectral efficiency.
Innovation Solution
A half-duplex wireless transmit/receive unit (HD-WTRU) method that determines overlap between uplink scheduling requests and downlink shared channel transmissions, allowing it to receive and process downlink transmissions while avoiding uplink and physical random access channel preamble transmissions, thereby reducing the need for dual oscillators and simplifying the device design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single oscillator is used in half duplex FDD mode to reduce cost, then manufacturing cost is reduced, but the device cannot simultaneously receive downlink and transmit uplink signals
Solution Approach 1:
The patent implements dynamic switching between uplink and downlink modes using a single oscillator. The WTRU switches its operational mode based on the scheduled transmission type, allowing the same hardware to adapt to different communication directions without requiring dual oscillators, thus resolving the contradiction between cost reduction and operational versatility
Solution Approach 2:
The system uses periodic switching between uplink and downlink operations in half-duplex mode. The single oscillator is reconfigured periodically to match the scheduled transmission direction, enabling the device to maintain cost-effectiveness while achieving the necessary signal reception and transmission capabilities through time-division
2Productivity
If the WTRU transmits uplink scheduling request and physical random access channel preamble simultaneously with downlink shared channel, then uplink communication is maintained, but spectral efficiency is reduced due to time overlap
Solution Approach 1:
The base station performs preliminary scheduling actions by allocating time resources that avoid overlap between uplink and downlink transmissions. The WTRU is scheduled to transmit uplink signals in time slots that do not conflict with downlink receptions, ensuring spectral efficiency while maintaining uplink reliability through advance time resource allocation
Solution Approach 2:
The patent resolves the time collision by introducing a time-domain separation dimension. Instead of attempting simultaneous transmission in the same time slot, the system schedules uplink and downlink transmissions in different time dimensions, allowing both to occur without spectral efficiency loss while maintaining communication reliability
Data Source
AI summary
A method performed by a HD-WTRU may comprise determining that an uplink SR and/or a PRACH preamble overlaps in time with one or more subframes of a scheduled downlink shared channel transmission. When the overlap occurs, the HD-WTRU may receive the downlink shared channel transmission on the one or more subframes. The HD-WTRU may process the downlink shared channel transmission, not transmit the SR and not transmit the PRACH preamble.