D2D Operation Mode Switching for Wireless Communication Reliability
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Solution Overview
Problem
Device-to-device (D2D) operations in wireless communication systems face interruptions due to reliance on network-scheduled resources, leading to reliability issues, especially in public safety networks where D2D transmission may be stopped or delayed due to RRC connection failures.
Innovation Solution
Implementing a method where a user equipment (UE) switches from a mode 1, relying on network-scheduled resources, to a mode 2, using exceptional resources autonomously selected from a predetermined pool, when the RRC connection establishment fails or is problematic, ensuring continuous D2D operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal transmits data using network-scheduled resources in mode 1, then the resource allocation is controlled by the network, but the transmission may be stopped or delayed when RRC connection establishment fails
Solution Approach 1:
The terminal dynamically switches between mode 1 (network-scheduled resources) and mode 2 (autonomous resources) based on RRC connection status. When RRC connection establishment fails, the terminal transitions from mode 1 to mode 2, enabling continuous D2D transmission without network scheduling. This dynamic adaptation resolves the contradiction by maintaining transmission continuity while preserving network control when conditions permit.
Solution Approach 2:
The invention changes the resource allocation parameter from network-controlled (mode 1) to autonomous selection (mode 2) based on RRC connection status. By monitoring RRC connection establishment success, the terminal adjusts the resource allocation mode, ensuring reliable D2D operation continues even when network connection fails, thus improving both reliability and transmission continuity.
2Ease of operation
If the terminal uses autonomous resources in mode 2, then the transmission continuity is maintained, but the resource allocation loses network control
Solution Approach 1:
The terminal dynamically adjusts the degree of autonomy in resource allocation based on RRC connection status. In mode 2, when RRC connection fails, the terminal autonomously selects resources from a pre-configured pool, maintaining transmission continuity. When RRC connection succeeds, the terminal returns to mode 1 where the network controls resource allocation, preserving network control and reliability for normal operations.
Solution Approach 2:
The invention introduces an intermediary mechanism (pre-configured resource pool) that enables autonomous resource selection in mode 2 while maintaining a connection to network control. The resource pool is pre-configured by the network, serving as an intermediary that allows autonomous operation without complete loss of network control, thus resolving the contradiction between transmission continuity and resource allocation control.
3Reliability
If the terminal waits for RRC connection establishment before transmitting D2D data, then the network control is maintained, but the transmission delay increases
Solution Approach 1:
The network pre-configures resource pools for mode 2 operation before D2D transmission begins. When RRC connection establishment fails, the terminal can immediately use these pre-configured resources without waiting for network scheduling decisions, significantly reducing transmission delay while maintaining network control through the pre-configuration process.
Solution Approach 2:
The terminal dynamically switches to mode 2 with autonomous resource selection when RRC connection establishment fails, eliminating the waiting time for network scheduling. This dynamic response reduces D2D transmission delay while the network maintains control through pre-configuration and subsequent monitoring, resolving the contradiction between network control and transmission speed.
4Ease of operation
If the terminal switches to mode 2 upon RRC connection failure, then the transmission continuity is maintained, but the device complexity increases
Solution Approach 1:
The invention extracts the resource allocation decision-making function from the complex RRC protocol layer and implements it in the MAC layer with simple rules: if RRC connection fails, switch to mode 2 and autonomously select resources from the pre-configured pool. This extraction reduces device complexity by avoiding complex interactions between protocol layers while maintaining transmission continuity.
Solution Approach 2:
The terminal performs self-service by autonomously selecting resources from the pre-configured pool in mode 2 without requiring complex network coordination. This self-service mechanism maintains transmission continuity while reducing device complexity, as the terminal uses simple autonomous selection rather than complex protocol interactions.
Data Source
AI summary
Provided are a method for device-to-device (D2D) performed by a terminal in a wireless communication system and a terminal using the method. The method is characterized by: delivering data related to D2D operation from an upper layer to a lower layer from among protocol layers of the terminal; starting a timer when the data is delivered; and transmitting a D2D signal using an exception resource, when the timer expires.