Mobile WiMAX Handover Types (802.16e)

This document outlines the mobile WiMAX handover types as per the IEEE 802.16e standard. We’ll cover both intra-ASN and inter-ASN handovers.

There are two main WiMAX standards: fixed WiMAX, which follows IEEE 802.16-2004 OFDM specifications, and mobile WiMAX, which follows IEEE 802.16e OFDMA specifications. Mobile WiMAX architecture supports intra-ASN handover, inter-ASN handover, and roaming between Network Service Providers (NSPs).

This support enables seamless handover at vehicular speeds, catering to both micro and macro mobility scenarios. As we know, handover or handoff is crucial for allowing mobile subscribers to maintain continuous service without interruption, even when moving out of a base station’s coverage area.

This applies to both Circuit Switched (CS) and Packet Switched (PS) calls. CS calls are typically used for voice communication, while PS calls are used for data communication (e.g., internet access).

Intra-ASN Handover

Intra-ASN handover occurs between Base Stations (BSs) within the same ASN coverage. The BSs can be interfaced with the same ASN Gateways or with different ASN Gateways. Crucially, these gateways must be within the coverage of the same ASN.

WiMAX interfaces R6 and R8 are used for intra-ASN handover. The R4 interface is used when the target BS is connected to another ASN gateway. Importantly, in intra-ASN handover, no IP address update is required.

Inter-ASN Handover

Inter-ASN handover occurs between Base Stations (BSs) connected to different ASNs. In this type of mobile WiMAX handover, ASN Gateways need to coordinate to ensure seamless handover.

There are two primary methods for handling data in inter-ASN handover:

• Anchoring: This method does not involve any path updates.
• Re-anchoring: This method does involve path updates.