Selective PMK-R1 Caching for Wireless Roaming Latency
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Solution Overview
Problem
The existing wireless network roaming process incurs latency due to the need for full authentication and key generation at new access points, which can lead to increased computing and storage costs, especially in dense environments with many potential roaming access points.
Innovation Solution
Selective caching of precursor keys (PMK-R1) at access points based on the likelihood of client device roaming, determined by factors like path loss and historical frequency, reduces the need for repeated key generation and storage, thereby streamlining the roaming process while conserving resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full authentication and key generation is performed at every access point during roaming, then security is maintained, but latency increases and computing/storage costs increase
Solution Approach 1:
The patent pre-generates and caches Pairwise Master Keys (PMKs) at access points before roaming occurs. When a client device roams to a new access point, the cached PMK is immediately available for the 4-way handshake, eliminating the need for real-time key generation and reducing roaming latency while maintaining security
Solution Approach 2:
The patent implements selective caching of PMKs at specific access points based on predicted client device roaming patterns. Instead of uniformly caching at all access points, the system identifies and caches PMKs only at access points where clients are likely to roam, optimizing the balance between security, latency reduction, and resource consumption
2Loss of time
If precursor keys are cached at all access points, then roaming latency is reduced, but storage and computing costs increase
Solution Approach 1:
The system selectively caches PMKs at specific access points based on predicted client device roaming patterns. By analyzing historical data and determining which access points are most likely to be visited by clients, the system caches PMKs only at those locations, reducing overall storage requirements while maintaining the latency benefits where needed
Solution Approach 2:
Instead of caching PMKs at all possible access points (excessive action), the system performs partial caching only at access points with predicted client presence. This partial action approach achieves sufficient latency reduction without the prohibitive storage costs of universal caching
3Speed
If precursor keys are pre-computed and stored, then roaming speed is improved, but computing resources are consumed
Solution Approach 1:
PMKs are pre-computed and cached at access points before clients need them during roaming. This preliminary action shifts the computing workload from real-time roaming events to background operations, improving roaming speed while distributing computing resource consumption over time
Solution Approach 2:
The system performs pre-computation of PMKs only at access points where clients are predicted to roam, rather than at all access points. This localized pre-computation approach reduces overall computing resource consumption while maintaining roaming speed improvements at the relevant locations
Data Source
AI summary
Systems and methods are provided for seamless roaming in a network. First, a client device is authenticated at a first access point of the network. Next, a processor selectively determines, among remaining access points in the network, second access points at which respective precursor keys, such as Pairwise Master Keys R1 (PMK-R1s) are to be computed. The second access points are determined based on any of respective path losses from the first access point to the second access points and respective historical frequencies at which the client device associates at the respective remaining access points. For the second access points, the respective PMK-R1s are computed and transmitted to the second access points to be cached. Next, following a request from the client device to reassociate to a second access point of the second access points, the client device is authenticated at the second access point based on a corresponding PMK-R1.