Wireless Client Multi-AP Association for Handoff Latency
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Solution Overview
Problem
Current wireless local area networks experience delays in handoff processes, particularly for real-time applications like audio and video transmissions, due to the need for wireless clients to associate with a single access point and switch to another when signal characteristics deteriorate, which can take up to 100 ms or more.
Innovation Solution
Enabling wireless clients to associate simultaneously with multiple wireless access points, allowing for seamless handoffs by exchanging information related to connections, sessions, and flows, and designating multiple access points as primary for different communications, thereby maintaining continuity and increasing data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a wireless client associates with a single wireless access point, then the device complexity is reduced, but the handoff time increases to 100 ms or more
Solution Approach 1:
The wireless client performs preliminary association with multiple wireless access points before handoff is needed. By pre-establishing connections with candidate access points, the client eliminates the need for time-consuming scanning and authentication during actual handoff, reducing handoff time from 100+ ms to near-instantaneous switching.
Solution Approach 2:
The system dynamically adjusts the number and selection of associated wireless access points based on real-time signal conditions and handoff requirements. The client can transition from single-AP association to multi-AP association dynamically, optimizing the balance between connection management complexity and handoff performance.
2Speed
If a wireless client associates with multiple wireless access points simultaneously, then the handoff speed increases, but the device complexity increases
Solution Approach 1:
The system segments the handoff process into distinct phases: preliminary association phase where multiple access points are connected, and active communication phase where data flows through selected access points. This segmentation allows the client to maintain multiple connections without proportionally increasing complexity during active data transmission.
Solution Approach 2:
The patent introduces an intermediary mechanism where the wireless client uses protocol data units to manage and coordinate multiple associations efficiently. This intermediary protocol layer abstracts the complexity of multi-AP management, allowing fast handoffs while maintaining manageable system complexity through standardized communication procedures.
3Reliability
If a wireless client performs handoff by scanning beacons and reassociating, then the connection reliability is maintained, but the handoff time increases
Solution Approach 1:
The wireless client performs preliminary association with multiple access points before handoff is triggered, pre-validating connection reliability. This preliminary action ensures that when handoff occurs, the client can immediately switch to a pre-validated access point without performing time-consuming beacon scanning and reassociation procedures, thus maintaining reliability while reducing handoff time.
Solution Approach 2:
The system creates copies of connection state information across multiple associated access points. By maintaining connection state copies at multiple APs beforehand, the client can perform instantaneous handoff without losing connection reliability, as the new access point already has the necessary session information to continue communication without full reassociation.
Data Source
AI summary
Multiple simultaneous associations with Wireless Access Points (WAPs) may be formed by a given wireless client to enable handoffs between the WAPs to be accelerated and, optionally, to enable both WAPs to provide simultaneous wireless services to the wireless client. Upon forming a primary association with one WAP the wireless client scans for beacon signals from other WAPs. Upon detecting another WAP, the wireless client transmits a Request To Send (RTS) message to the new WAP indicating the identity of the primary WAP. The wireless client may also identify the new WAP to the primary WAP using a RTS message. The primary and secondary WAPs exchange information so that, in the event of a handoff, the required information has already been shared with the new WAP. Optionally, the several WAPs may provide simultaneous service to the wireless client.