Recipient Usage Indication for Carrier Frequency in BFD
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Solution Overview
Problem
Existing medium access control mechanisms, such as CSMA, face challenges in managing radio transmissions among multiple nodes sharing the same carrier frequency, leading to issues like the 'hidden node' and 'exposed node' problems, which result in collisions and inefficient frequency utilization.
Innovation Solution
A method where radio devices receive indications about carrier frequency usage from other devices, allowing them to control their transmissions and avoid collisions by using BFD capabilities for simultaneous reception and transmission, and broadcasting recipient usage indications to optimize frequency usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CSMA scheme is used for distributed medium access control, then nodes can autonomously coordinate access attempts, but hidden node problem occurs where nodes cannot detect transmissions from distant nodes causing collisions
Solution Approach 1:
The patent introduces an access node as an intermediary that receives transmission requests from multiple UEs, determines carrier frequency availability, and provides feedback to UEs. This mediator resolves the hidden node problem by centralizing the collision detection function at the access node, which can detect transmissions from all UEs in its coverage area regardless of their mutual visibility.
Solution Approach 2:
The patent implements a feedback mechanism where the access node monitors the carrier frequency, determines its availability, and transmits availability indications back to UEs. This feedback loop allows UEs to make informed transmission decisions based on real-time channel status information from the access node, preventing collisions that would occur with purely distributed sensing.
2Reliability
If CSMA scheme is used for distributed medium access control, then nodes can detect ongoing transmissions locally, but exposed node problem occurs where nodes defer transmissions unnecessarily due to detecting transmissions that do not cause interference at their target access node
Solution Approach 1:
The access node provides authoritative feedback on carrier frequency availability to each UE based on its own reception status. This feedback overrides local sensing decisions, allowing UEs to transmit even when they locally detect other transmissions, as long as the access node indicates the frequency is available. This resolves the exposed node problem by replacing local, potentially misleading sensing with centralized, accurate availability information.
Solution Approach 2:
The access node acts as a mediator that reconciles local sensing decisions with global channel availability. It receives transmission requests from UEs that have detected the carrier as free, verifies actual availability at its receiver, and provides binding availability indications. This intermediary function prevents unnecessary transmission deferrals caused by the exposed node problem.
3Productivity
If multiple UEs share the same carrier frequency with different access nodes, then frequency utilization is improved, but coordination complexity increases due to need for distributed arbitration across multiple access nodes
Solution Approach 1:
The patent segments the medium access control function by allowing each access node to independently manage and arbitrate carrier frequency usage within its own coverage area. Each access node maintains independent state information and provides independent availability indications to its UEs. This segmentation simplifies coordination by eliminating the need for complex inter-access-node communication and arbitration mechanisms.
Solution Approach 2:
The patent implements preliminary action by having UEs transmit availability requests to their respective access nodes before attempting carrier sensing. The access node pre-determines carrier availability based on its reception status and provides this information back to the UE before the UE performs local sensing. This preliminary determination by the access node simplifies subsequent coordination by establishing authoritative channel state information in advance.
Data Source
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AI summary
A radio device (100) receives a radio transmission on a carrier frequency. While receiving the radio transmission, the radio device (100) transmits an indication that the carrier frequency is in use by the radio transmission to the radio device (100). This indication may then be used by a further radio device (10, 11) for controlling a radio transmission to the radio device (100), e.g., by deciding whether, when, or how to use the carrier frequency for this radio transmission.