Handover Measurements in LTE

In LTE (Long-Term Evolution), handover measurements are crucial for ensuring seamless mobility as User Equipment (UE) moves across different cells within the network. These measurements assist in deciding when and to which cell a handover should occur. Here’s an overview of key handover measurements in LTE:

  1. Received Signal Strength (RSS):
    • RSS measures the power level of the signal received from neighboring cells. When the signal strength of a neighboring cell becomes stronger than the serving cell beyond a certain threshold, it may trigger a handover.
  2. Reference Signal Received Power (RSRP):
    • RSRP is a more specific measure of signal strength, focusing on the power level of the reference signals from the serving and neighboring cells. Handover decisions can be based on RSRP values to ensure a reliable handover to a cell with a stronger reference signal.
  3. Reference Signal Received Quality (RSRQ):
    • RSRQ takes into account both the signal strength and the quality of the received signal. It is the ratio of RSRP to the Received Signal Strength Indicator (RSSI). RSRQ helps in determining the quality of the received signal and is considered in handover decisions.
  4. Cell Identity (PCI, ECI):
    • The Physical Cell Identity (PCI) or E-UTRAN Cell Identity (ECI) uniquely identifies cells. Measurements of neighboring cell identities are essential for handover decisions.
  5. Time Advance (TA):
    • Time Advance provides information about the time delay between the UE and the serving cell. This is crucial for accurate timing synchronization and handover decisions.
  6. Signal-to-Noise Ratio (SNR):
    • SNR measures the ratio of the received signal power to the background noise level. A high SNR indicates a clear and reliable signal, influencing handover decisions.
  7. Inter-Frequency and Inter-RAT Measurements:
    • In addition to intra-frequency handovers (within the same frequency), LTE supports inter-frequency and Inter-Radio Access Technology (Inter-RAT) handovers. Measurements of neighboring cells in different frequencies or radio access technologies are considered for inter-frequency and Inter-RAT handovers.
  8. Event A and Event B Reporting:
    • Events A and B are specific conditions triggering measurement reports. Event A may be triggered when the serving cell becomes too weak, while Event B may be triggered when a neighboring cell becomes stronger.

These measurements are part of the LTE Radio Resource Management (RRM) system and are performed periodically or in response to specific events. They enable the network to make informed decisions about when and to which cell a handover should occur, ensuring a smooth and uninterrupted user experience during mobility.

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