Mobile Node Handoff via Bounded Delay Channel Switching
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Solution Overview
Problem
In wireless LANs, the handoff process between access points is inefficient, leading to packet loss and reduced data or voice transmission quality due to the time required for authentication, authorization, and encryption key assignment, causing handoff latency and packet delays.
Innovation Solution
The method involves periodically switching between channels during handoff, using one channel for ongoing communication and another for the handoff process, employing dual-MAC addresses to maintain connections with both access points, and utilizing bounded delay channel switching and power saving modes to minimize latency and packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the handoff procedure is performed sequentially (switching channels to authenticate with target AP), then authentication and authorization are completed, but packet loss occurs and transmission quality degrades
Solution Approach 1:
The mobile node performs authentication and authorization with the target access point before actually switching channels for data transmission. By preparing the handoff credentials in advance while still connected to the current AP, the node ensures that when the channel switch occurs, the authentication is already complete, eliminating delays during the transition.
Solution Approach 2:
The mobile node maintains continuous data transmission by switching between channels rapidly - using the current AP channel for data packets and the target AP channel for authentication procedures. This interleaved approach ensures that data transmission continues without interruption while handoff procedures are simultaneously completed.
2Adaptability or versatility
If the mobile node switches channels to perform handoff authentication, then connection to target AP is established, but data packets are lost during the transition
Solution Approach 1:
The mobile node employs periodic channel switching between the current AP channel and target AP channel in a structured manner. During duty cycles, it transmits data packets on the current channel; during sleep cycles, it switches to the target channel for authentication and key assignment. This periodic pattern ensures both data transmission and handoff completion without packet loss.
Solution Approach 2:
The handoff process is segmented into distinct phases: data transmission phase on the current channel, authentication phase on the target channel, and transition phase. By dividing the handoff into separate temporal and functional segments, the node can maintain data transmission integrity while completing authentication procedures without causing packet loss.
3Reliability
If authentication and authorization are performed during handoff, then secure connection is established, but transmission quality decreases due to delays
Solution Approach 1:
Authentication, authorization, and encryption key assignment are performed in advance during the authentication phase before data transmission begins on the target channel. By completing all security procedures beforehand, the actual data transmission experiences no delays, maintaining high transmission quality while ensuring secure connection establishment.
Data Source
AI summary
Methods performed by a mobile node (MN) in a secured network for handoff of communication from a serving access point (AP) to a target AP are provided. In a bounded delay channel switching (BDCS) method, the MN periodically switches between a first channel and one of multiple other channels during handoff, utilizes the first channel to transmit/receive packets to/from a corresponding node (CN) via the serving AP and utilizes one of the other channels to perform the handoff procedure to the target AP. In a dual-MAC switching (DMS) method, the MN employs a first MAC (medium access control) address to transmit/receive packets to/from the serving AP and a second MAC address to perform the handoff procedure to the target AP. The BDCS and DMS methods may be used concurrently, and may be used in a secured network that complies with, e.g., the IEEE 802.11, IEEE 802.1x or IEEE 802.11i plus IEEE 802.11f standards.