Priority-Based Channel Preemption in D2D Wireless Communication
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Solution Overview
Problem
In device-to-device wireless communication, existing methods for allocating communication resources in uncoordinated access schemes fail to effectively reduce collisions and prioritize high-priority users or transmissions, especially in scenarios where network coverage is limited or unavailable.
Innovation Solution
A method where user equipment determines the priority of active users and transmissions, and only requests resource allocation if its priority is higher, using pre-emption signals and predefined preamble signatures to allocate resources efficiently, ensuring that higher priority users can preempt lower priority users and transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If uncoordinated access is used to allow autonomous resource allocation in device-to-device communication, then network coverage requirements are reduced and flexibility is improved, but collision probability increases and resource allocation efficiency deteriorates
Solution Approach 1:
The transmitting UE performs preliminary actions by sending an announcement message before actual data transmission to reserve the communication channel. This preliminary reservation reduces the probability of collision by informing other UEs of the intended resource usage in advance, while maintaining the uncoordinated access flexibility.
Solution Approach 2:
The system implements a cushioning mechanism by requiring UEs to send announcement messages that reserve channels beforehand. This creates a protective buffer that prevents collisions by notifying other potential transmitters of the reserved resources, reducing collision probability while maintaining autonomous access.
2Reliability
If CSMA/CA protocol is used to reduce collisions through RTS/CTS handshaking, then collision avoidance is improved, but device complexity increases and the protocol cannot be directly applied to broadcast links
Solution Approach 1:
The invention extracts and adapts only the essential collision avoidance concept from CSMA/CA, implementing a simplified announcement-based reservation mechanism. Instead of the full RTS/CTS handshake protocol, the system uses unidirectional announcement messages that reserve channels without requiring complex bidirectional handshaking, reducing device complexity while maintaining collision avoidance benefits.
Solution Approach 2:
Instead of using the conventional CSMA/CA approach where the receiver sends CTS/ACK signals back to the transmitter, the invention inverts the approach by having the transmitter send announcement messages to reserve the channel unidirectionally. This inversion simplifies the protocol for broadcast links where multiple receivers exist and traditional ACK mechanisms are impractical.
3Productivity
If all communication channels are currently in use by lower priority users, then resource utilization is maximized, but high priority users cannot communicate and service quality deteriorates
Solution Approach 1:
The system implements dynamic priority-based channel allocation where the announcement message includes priority information. When a high-priority UE wants to communicate, it can preempt lower-priority channel usage by sending its announcement message, which causes lower-priority UEs to release their reserved channels. This dynamic mechanism ensures resource utilization is maintained while allowing high-priority services to obtain channels when needed.
Solution Approach 2:
The invention changes the parameter of channel allocation from static to dynamic by incorporating priority levels in the announcement messages. The system monitors priority parameters and allows parameter changes in channel assignment based on urgency, enabling high-priority users to displace lower-priority users from channels while maintaining overall resource utilization through continuous reuse by available UEs.
4Reliability
If transmitting UE sends announcement message on a separate channel to reserve resources, then collision avoidance is improved, but resource overhead increases and half-duplex constraints are violated
Solution Approach 1:
The invention merges the announcement message transmission with the data transmission by allowing the announcement to be sent on the same communication channel that will be used for data transfer. This combining eliminates the need for separate reservation channels, reducing resource overhead while maintaining collision avoidance through the announcement mechanism. The half-duplex constraint is satisfied as the UE transmits the announcement and then receives acknowledgments or proceeds with data transmission in sequence.
Data Source
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AI summary
A method of requesting a communication channel for use by a user equipment for broadcasting data to at least one further user equipment when all of a plurality of communication channels configured for direct user equipment to user equipment communication are currently being used, wherein each of the plurality of communication channels is a half duplex channel and each of the plurality of communication channels has an associated preamble identifying a block of transmission resources comprising the communication channel. The method comprises: determining a priority of an active user equipment currently broadcasting data to other user equipment using one of the plurality of communication channels; and in response to detecting that the priority is lower than a current priority of the user equipment, transmitting a request for use of the one of the plurality of communication channels.