Joint Spectrum Allocation and Cache Placement in D2D Networks
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Solution Overview
Problem
Existing cache placement strategies in device-to-device (D2D) networks face challenges due to the need for exact network topology or channel state information, limited storage capacity in D2D devices, and sub-optimal performance when allowing multiple file caching, which affects system throughput and fairness.
Innovation Solution
The proposed solution involves joint spectrum allocation and random caching strategies that maximize the mean logarithm utility using spatial statistics and file requesting probabilities, with closed-form formulas for optimal spectrum allocation and caching probabilities, allowing devices to cache multiple files without requiring exact network topology or CSI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If devices cache multiple files, then system throughput is improved, but storage capacity constraints make it difficult to cache all popular files
Solution Approach 1:
The patent changes the parameter from binary caching (cache or not cache) to probabilistic caching (cache with probability p_n). This allows the system to optimize the expected number of cached files and system throughput by adjusting caching probabilities, rather than being constrained by hard storage limits on specific files.
Solution Approach 2:
Instead of requiring devices to cache all popular files (excessive action), the patent allows partial caching where devices cache files with optimized probabilities. This partial action approach achieves the optimal balance between storage constraints and system throughput by caching only the necessary portion of popular files.
2Reliability
If exact network topology or CSI is required for cache placement, then cache hit probability is improved, but system complexity and information acquisition difficulty increase
Solution Approach 1:
The patent replaces the expensive and complex requirement for exact network topology information with a simple statistical parameter (spatial density). This disposable approximation approach achieves comparable cache hit probability without the burden of acquiring and maintaining detailed network topology or CSI.
Solution Approach 2:
The patent changes the information requirement from complex network topology/CSI to simple spatial density statistics. This parameter simplification reduces the complexity of information acquisition while maintaining effective cache placement performance through probabilistic modeling.
3Reliability
If cache placement optimizes for cache hit probability, then local performance is improved, but fairness among devices is not considered
Solution Approach 1:
The patent creates a universal cache placement framework that simultaneously achieves cache hit probability optimization and fairness among devices. The spatial density-based probabilistic approach serves multiple functions: it optimizes local cache performance while also ensuring equitable access across the network, making the system adaptable to both individual and collective performance requirements.
Data Source
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AI summary
A method, system and apparatus are disclosed. A network node is configured to communicate with a wireless device, WD, where the network node configured to, and/or comprising a radio interface and/or comprising processing circuitry configured to: receive an indication whether the WD is to cache at least one file based on spatial statistics of a cache-enabled device-to-device, D2D, network collected by the WD, and perform spectrum allocation based on the received indication.