Soft Handover

Soft Handover:

A mobile station communicates with two base stations simultaneously

Mobile Searches for Other Cells - looks for Sync Channel

Reports Candidate Cells to System

Receives Assignment for Soft Handoff from Network

Must Determine System Frame Number from Each Cell to Properly Time Align Each Cell’s Transmissions.

The  System Frame Number (SFN) is multiplexed with the BCH transport channel and is carried over-the-air on the P-CCPCH.

Above figure shows Soft HandOver, Uplink.

Above figure shows Soft HandOver, Downlink.