D2D Discovery Resource Allocation in LTE-A Networks
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Solution Overview
Problem
In 3GPP LTE-A systems, device-to-device (D2D) discovery signal transmissions conflict with cellular data and control transmissions, particularly when UEs are heavily scheduled, leading to reduced opportunities for D2D signal transmission and potential disruptions to cellular services.
Innovation Solution
The evolved Node B (eNB) requests UE reports on D2D discovery needs and assigns or prioritizes resources to manage D2D signal transmissions, allowing UEs to request Type-2 resources or indicate priority for D2D participation, thereby optimizing resource allocation and avoiding conflicts with cellular traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D discovery signal transmission is set with higher priority than cellular data or control, then D2D discovery opportunities increase, but cellular services are disrupted (DL retransmissions and CQI transmission are affected)
Solution Approach 1:
The eNB performs preliminary scheduling of cellular data and control transmissions, anticipating potential D2D discovery needs. By proactively allocating resources and predicting UE D2D requirements, the system prepares in advance to avoid conflicts, allowing D2D transmissions to occur at predetermined times without disrupting cellular services.
Solution Approach 2:
The system implements feedback mechanisms where UEs report their D2D discovery needs to the eNB, and the eNB adjusts scheduling decisions based on this feedback. This closed-loop approach allows the network to dynamically balance D2D discovery opportunities with cellular service requirements, ensuring reliable cellular operations while maintaining D2D functionality.
2Ease of operation
If Type-1 resource allocation is used for RRC Connected mode UEs, then autonomous D2D resource selection is enabled, but resource conflicts with cellular traffic occur when UEs are heavily scheduled
Solution Approach 1:
The system dynamically adjusts resource allocation between Type-1 and Type-2 based on UE scheduling conditions. When UEs are heavily scheduled with cellular traffic, the eNB transitions them from autonomous Type-1 selection to eNB-controlled Type-2 allocation, ensuring D2D opportunities are maintained while adapting to changing traffic conditions.
Solution Approach 2:
The eNB acts as an intermediary between UEs and D2D resources. Instead of direct autonomous selection or complete eNB control, the eNB mediates by receiving D2D need reports from UEs and making informed resource allocation decisions, balancing autonomous operation with network coordination.
3Adaptability or versatility
If idle mode UEs use Type-1 resource allocation, then resources are obtained without RRC connected state, but resource coordination with network is reduced
Solution Approach 1:
Different resource allocation strategies are applied to different UE states: idle mode UEs use Type-1 autonomous selection for flexibility, while connected mode UEs use Type-2 eNB-controlled allocation for coordination. This localized approach matches the allocation method to the specific operational context of each UE.
Data Source
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AI summary
Various communication systems may benefit from techniques and systems for resource allocation. For example, communication systems of the third generation partnership project may benefit from device to device discovery resource allocation methods and systems. A method can include determining that downlink data transmission may cause conflict between uplink control channel transmission and device to device discovery signal transmissions or that uplink shared channel transmissions may conflict with device to device discovery signal transmissions; and requesting a user equipment to report device to device discovery needs based on the determining.