D2D Link HARQ Adaptation via Base Station Mediation
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Solution Overview
Problem
Current direct communication between user equipment (UE) and UE relaying methods face challenges in maintaining effective hybrid automatic repeat request (HARQ) and adaptive transmission, particularly in device-to-device (D2D) links, especially when using unlicensed bands or in environments with interference, which affects the quality of service and frequency reuse.
Innovation Solution
A method for processing HARQ and adaptive transmission in D2D links using uplink and downlink bands in TDD or FDD cellular communication systems, where UE determines transmission modes and power based on initial settings from the base station or feedback from counterpart UE, with options for continuous or periodic updates, and includes mechanisms for switching to cellular links when communication fails, utilizing channel reciprocity and piggyback schemes for control information transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct communication between UE is performed using unlicensed band, then frequency use efficiency is improved, but communication performance deteriorates due to interference
Solution Approach 1:
The patent introduces a base station as an intermediary to manage D2D communications in unlicensed bands. The base station performs scheduling, power control, and interference coordination, thereby enabling frequency reuse while mitigating the interference-related performance deterioration that would otherwise occur in unlicensed band D2D communications
2Productivity
If UE relay communication is implemented, then transmission capacity of UE at cell boundary is improved, but system complexity increases due to additional D2D link management
Solution Approach 1:
The base station serves as a mediator that manages the D2D links established for UE relay communication. It performs scheduling, power control, and HARQ coordination for relay UEs, thereby enabling enhanced transmission capacity at cell boundaries while centralizing the complexity management in the base station rather than distributing it across multiple UEs
Solution Approach 2:
The patent makes the D2D communication framework universal by enabling it to serve multiple functions: direct UE-UE communication, UE relay communication, and integration with existing cellular links. This multi-functionality allows the same mechanism to handle various communication scenarios without requiring separate complex management systems for each type
3Reliability
If HARQ and adaptive transmission are implemented in D2D link, then communication reliability is improved, but transmission overhead increases due to control information exchange
Solution Approach 1:
The patent merges HARQ control information with data transmission by piggybacking ACK/NACK signals on the PUSCH channel. This combining approach enables reliable communication through HARQ while minimizing control overhead, as the acknowledgment information is transmitted simultaneously with data rather than separately
Solution Approach 2:
The patent implements feedback mechanisms where receiving UE sends ACK/NACK information back to transmitting UE through the base station. This feedback enables adaptive transmission and HARQ retransmission decisions, improving communication reliability while the feedback is efficiently delivered through integrated control signaling rather than separate dedicated channels
Data Source
AI summary
Provided is a method of processing hybrid automatic repeat request (HARQ) and adaptive transmission of a device-to-device (D2D) link. In the method, an operation method of user equipment (UE) includes (a) receiving an initial transmission mode (TM) and transmission power for the D2D link from a base station, and performing data transmission through the D2D link, (b) determining, at the UE, a TM and transmission power of a succeeding subframe, or receiving a TM control value and a transmission power control value from counterpart UE of the D2D link and determining the TM and the transmission power of the succeeding subframe, and (c) performing the data transmission to the counterpart UE using the determined TM and transmission power. Here, (b) and (c) are repeated.