Cellular IP (CIP) and Its Use in Detail
Overview of Cellular IP
Cellular IP (CIP) is a micro-mobility protocol designed to complement Mobile IP by handling local mobility within a limited geographical area, such as a campus or metropolitan network. It is optimized for environments with a high density of mobile devices that frequently change their points of attachment to the network, such as in cellular networks or wireless LANs.
Key Components of Cellular IP
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Cellular IP Gateway (GW)
- Acts as the interface between the Cellular IP network and the broader Internet.
- The gateway’s IP address serves as the care-of-address (COA) for all mobile hosts (MHs) attached to the network.
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Base Stations (BS)
- Serve as access points for mobile hosts.
- Replace traditional IP routing with Cellular IP routing and location management.
- Communicate with mobile hosts via wireless interfaces and route IP packets within the Cellular IP network.
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Mobile Hosts (MH)
- Devices that move within the Cellular IP network while maintaining connectivity.
How Cellular IP Works
Routing Mechanism
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Uplink Packets:
- Originate from the mobile host and are routed hop-by-hop to the gateway.
- The path taken by these packets is cached in base stations (routing cache).
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Downlink Packets:
- Addressed to a mobile host and routed using the reverse path stored in the routing cache.
Paging Mechanism
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Idle Mobile Hosts:
- Hosts that have not received data packets for a system-specific time.
- Their downlink routes timeout and are removed from the routing cache.
- These hosts periodically send paging-update packets (empty IP packets addressed to the gateway) to maintain their presence in the paging cache.
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Active Mobile Hosts:
- Maintain entries in both routing and paging caches.
- Periodically send route-update packets to keep their routing cache mappings valid.
Handover Process
- Mobile-Controlled Handover (MCHO):
- Initiated by the mobile host based on signal measurements from base stations.
- Semi-Soft Handover:
- During handover, downlink packets are temporarily delivered through both the old and new base stations to minimize packet loss.
- Mappings for the old base station timeout and are cleared automatically.
Advantages of Cellular IP
- Efficient Location Management:
- Separates idle and active hosts, reducing unnecessary signaling overhead.
- Flexible Handover:
- Supports seamless handover with minimal packet loss.
- Scalability:
- Handles large numbers of mobile hosts by leveraging localized routing and paging.
- Simplicity:
- Mobile hosts are memory-less and rely on the network for routing and paging.
- Global Migration Support:
- Works alongside Mobile IP to provide both local and global mobility solutions.
Use Cases of Cellular IP
- Wireless Campus Networks:
- Provides seamless mobility for users moving between access points within a university or corporate campus.
- Cellular Networks:
- Enhances mobility management for mobile devices in cellular systems, reducing latency during handovers.
- Internet of Things (IoT):
- Supports efficient mobility for IoT devices in industrial or smart city environments.
Conclusion
Cellular IP is a robust and scalable solution for managing micro-mobility in IP networks. By leveraging localized routing, paging, and semi-soft handovers, it ensures seamless connectivity for mobile hosts while minimizing signaling overhead. Its integration with Mobile IP makes it a versatile choice for modern wireless networks.