MIH Function Link Ownership for IEEE 802.21 Handover
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Solution Overview
Problem
The IEEE 802.21 specification does not provide a mechanism to support multiple MIH Users simultaneously changing the state of a link, leading to potential race conditions and inconsistencies in link state management, and lacks an efficient method for signaling link ownership between local and remote nodes.
Innovation Solution
A link ownership scheme is introduced within the MIHF, where a Link Ownership Manager (LOM) allocates and manages link ownership among MIH Users, and the MIH_Register request primitive is modified to include a SetOfOwnedLinks parameter for remote link ownership allocation, ensuring only one MIH User can change the link state and facilitating efficient signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple MIH Users are allowed to change link state simultaneously, then link management flexibility is improved, but link state consistency deteriorates due to race conditions
Solution Approach 1:
The patent segments the link state management rights by introducing the concept of link ownership. Each link is assigned to a specific MIH User (owner) who has exclusive rights to change its state. This segmentation prevents multiple users from simultaneously modifying the same link state, eliminating race conditions while still allowing flexible multi-user management through the ownership assignment mechanism.
Solution Approach 2:
The patent introduces a link ownership manager as an intermediary component that mediates between multiple MIH Users and the link state management function. This manager assigns and tracks link ownership, controlling which user can modify which link state. The intermediary resolves conflicts by ensuring only the owner of a given link can change its state at any given time, maintaining consistency while enabling flexible multi-user access.
2Reliability
If link ownership signaling is added between local and remote nodes, then link state consistency is improved, but signaling complexity increases
Solution Approach 1:
The patent makes the MIH_Register request primitive multi-functional by adding the SetOfOwnedLinks parameter. This single parameter change enables the existing primitive to serve dual purposes: traditional registration functionality plus link ownership allocation. By making the primitive universal, the patent avoids creating separate signaling protocols for ownership, thereby maintaining consistency without proportionally increasing signaling complexity.
Solution Approach 2:
The patent merges the link ownership allocation function with the existing MIH_Register primitive. Instead of creating a separate ownership signaling mechanism, the ownership information is embedded within the registration process. This merging approach consolidates multiple functions into a single signaling exchange, reducing overall protocol complexity while achieving reliable link state consistency through ownership tracking.
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AI summary
Currently, the I.E.E.E. 802.21 specification allows multiple MIH (Media-Independent Handover) Users in a single MIH Function. However, the specification is not clear about how multiple MIH Users are supported by a single MIHF (MIH Function) under a constraint in which if there is only one MIH User is allowed to change the state of a particular link during a particular period of time. This document proposes a detailed architecture which allows for the co-existence of multiple MIH Users by introducing a link ownership scheme in the MIHF (MIH Function). The proposed link ownership scheme also supports the scenario in which the state of a link of a mobile node is changed by a network node by modifying the MIH_Register primitives in the I.E.E.E. 802.21 specification to signal the set of allocated links to a remote MIH User on the network node. The modification of MIH_Register primitive also has the added benefit of allowing the network node to subscribe to events on a specific set of links present in the mobile node as opposed to not knowing any of the links at all.