Latency in telecommunications and networking refers to the time delay between the transmission of a signal and its receipt. It is a critical performance metric in data communication and affects how quickly data can be sent and received over a network.
Below are detailed explanations of the key latency KPIs (Key Performance Indicators) in LTE:
LTE Latency KPIs.
1. Access Latency.
Access latency refers to the delay experienced during the initial connection phase when a UE (User Equipment) attempts to connect to the network. It can be divided into two main types:
AccessLatency_Attach: This KPI measures the time duration from when the UE sends an Attach Request message to when the UE sends an Attach Complete message. It represents the time taken for the UE to attach to the LTE network.
AccessLatency_Idle2Active: This KPI measures the time duration from when the UE, which is in idle mode, sends an RRCConnectionRequest message to when the UE sends an RRCConnectionReconfiguration message. It indicates the time taken for the UE to transition from idle mode to active mode.
2. Service Latency.
Service latency evaluates the delay associated with specific services provided by the network. It can be measured through drive tests or stationary tests and can be distinguished by different services:
- ServiceLatency_Ping_32_bytes: This KPI measures the latency of a ping service using 32-byte packets.
- ServiceLatency_Ping_1460_bytes: This KPI measures the latency of a ping service using 1460-byte packets.
3. Control Plane HO Interrupt Latency
This KPI evaluates the latency in the control plane during a handover process. It is defined as the time duration from when the UE receives the handover command (RRCConnectionReconfiguration after MeasurementReport) to when the UE sends the handover confirm message (RRCConnectionReconfigurationComplete). This KPI is measured through drive tests.
Below are Control Plane HO Interrupt Latency KPIs list.
ControlPlane_Interrupt_IntraLTE_HO
ControlPlane_Interrupt_IRATHO_L2C
ControlPlane_Interrupt_IRATHO_L2W
ControlPlane_Interrupt_IRATHO_L2G4. User Plane HO Interrupt Latency
This KPI measures the interruption in the user plane during a handover process. The user plane interrupt latency can be observed at different layers such as the IP layer, RLC layer, or MAC layer. It is defined as the time duration from the last RLC layer packet received before the handover to the first RLC layer packet received after the handover. This KPI is also measured through drive tests.
Below are User Plane HO Interrupt Latency KPIs list.
UserPlane_Interrupt_IntraLTE_HO
UserPlane_Interrupt_IRATHO_L2C
UserPlane_Interrupt_IRATHO_L2W
UserPlane_Interrupt_IRATHO_L2GSummary
Understanding and measuring these various latency components in LTE networks is crucial for network optimization and providing a high-quality user experience. Each KPI provides insights into different aspects of network performance, from initial connection times to service-specific delays and handover interruptions. By analyzing and optimizing these KPIs, operators can improve the efficiency and reliability of their LTE networks.