Synchronized Contention Windows for Unlicensed Spectrum Access
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Solution Overview
Problem
Current wireless communication systems in unlicensed frequency bands face interference and inefficiencies due to contention-based medium access procedures, particularly in scenarios with multiple network operators, leading to increased signaling overhead and communication latency.
Innovation Solution
Implementing a technology-neutral medium access mechanism that utilizes synchronized contention windows, allowing all nodes to access the shared communication channel simultaneously, thereby reducing interference and enhancing fairness and receiver protection, especially in CoMP scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If contention-based medium access procedures are used in unlicensed frequency bands, then multiple network operators can access the shared channel, but interference and communication inefficiency increase
Solution Approach 1:
The contention window is divided into multiple slots, with the first slot reserved for high priority traffic and subsequent slots for normal traffic. This segmentation allows high priority transmissions to access the channel without competing with normal traffic, reducing interference and improving communication efficiency while maintaining multiple access capability
Solution Approach 2:
Different quality parameters are assigned to different traffic types within the same contention window. High priority traffic is granted preferential access in the first slot with higher priority marking, while normal traffic accesses in subsequent slots. This local differentiation resolves the contradiction by providing both multi-operator access and reliable high-priority communication
2Ease of operation
If synchronized contention windows are implemented for all radio access technologies, then fairness and receiver protection improve, but system complexity increases
Solution Approach 1:
The synchronization mechanism uses a universal frame structure and contention window format that can be adopted by multiple radio access technologies (LTE, NR, WiFi). By defining a common framework that works across different technologies, the patent achieves fairness without requiring technology-specific complex synchronization protocols
Solution Approach 2:
Contention windows are structured with periodic synchronization points and regular slot patterns. This periodic structure provides predictable access opportunities for all nodes while maintaining manageable complexity through repeating patterns rather than ad-hoc synchronization requirements
3Loss of time
If high priority traffic is given preferential access in the first slot, then communication latency is reduced, but access fairness for normal traffic may be compromised
Solution Approach 1:
The contention window is segmented into multiple slots where the first slot is dedicated to high priority traffic and subsequent slots are allocated to normal traffic. This segmentation ensures high priority traffic experiences minimal latency by accessing the channel first, while normal traffic maintains fair access opportunities in later slots, resolving the contradiction between latency reduction and access fairness
Data Source
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AI summary
Technology neutral coexistence and high priority traffic is disclosed for use in unlicensed frequency bands. Synchronization boundaries are defined in which synchronous contention windows across all radio access technologies attempting access to a shared communication channel occur periodically. Between the synchronous contention windows, the nodes may return to asynchronous access procedures. Such synchronous access procedures may be applicable to certain power classes or deployment type nodes. Additionally, various priority schemes for the synchronous contention window may be used to ensure protection of higher priority nodes or traffic, such as ultra-reliable low latency communication (URLLC) traffic. According to certain aspects, the deployment of such synchronous access methodology may be triggered via signaling from initiating devices. Additional aspects may provide for a technology neutral receiver protection mechanism by defining resources for protection signaling during receiver protection intervals between successive synchronous contention windows.