SHO Soft Handover

Soft handover (SHO) is a technique used in cellular communication systems, such as GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunications System), to enable seamless handover of a mobile device from one base station to another. Soft handover allows for improved call quality, reduced call drops, and uninterrupted service for mobile users.

During a soft handover, the mobile device is connected to multiple base stations simultaneously. This is in contrast to hard handover, where the mobile device is briefly disconnected from the serving base station before being connected to the target base station. Soft handover provides a smooth transition by maintaining overlapping coverage areas between neighboring base stations.

The process of soft handover involves the following steps:

1. Neighbor Cell Measurement: The mobile device continuously measures signal strengths and quality from neighboring base stations. These measurements are used to determine the potential target cells for handover.
2. Handover Decision: When the signal strength and quality of a neighboring cell exceed a certain threshold, the network initiates the handover process. The decision to initiate a soft handover is based on algorithms and parameters defined by the network operator.
3. Connection Setup: Once the handover decision is made, the network establishes a connection with the target base station. At this stage, both the serving base station and the target base station are active and involved in the communication.
4. Data Forwarding: During the soft handover, the mobile device receives and sends data through both the serving and target base stations. This redundancy ensures that there is no loss of data during the handover process. The network combines the data received from both base stations to ensure seamless communication.
5. Signal Combining: The signals received from the serving and target base stations are combined at the network side to generate the best possible signal quality. The network evaluates and selects the optimal signal from the multiple received signals to provide the highest quality connection.
6. Handover Completion: Once the network determines that the target base station provides better signal quality and stability, the serving base station reduces its power and eventually releases the connection with the mobile device. The mobile device then continues the communication solely with the target base station.

Soft handover offers several advantages over hard handover. Firstly, it reduces the likelihood of call drops and improves call quality since the mobile device remains connected to multiple base stations. Secondly, soft handover enables seamless handover without interruption, as the mobile device can receive and transmit data through multiple base stations simultaneously. Finally, soft handover provides better coverage and reliability by utilizing the overlapping coverage areas of neighboring base stations.

Overall, soft handover is an essential feature in cellular communication systems to ensure uninterrupted connectivity and high-quality service for mobile users.