Dear community friends, today I would like to introduce self-organizing network (SON) to you.
With the rapid development of LTE mobile communications technologies, the mobile communications industry is experiencing explosive development in the Internet era. The emergence of new technologies and new systems poses higher and higher requirements on network construction and O&M of operators. Compared with an earlier wireless communications system, the LTE system can provide a larger wireless bandwidth, and provide a larger quantity of broadband applications with higher quality, for example, a mobile video service with a high bandwidth requirement and an online game with high latency. A key challenge for each LTE operator is how to provide services to subscribers in an efficient and low-cost manner. Therefore, operators must control capital expenditure (CAPEX) on LTE infrastructure construction and operating expenditure (OPEX) related to LTE network operation.
Figure 1 SON Background
What are the objectives of SON?
To help LTE operators better manage a large number of base stations from different vendors and reduce OPEX, the concept of the SON emerges. Telecom operators expect a network that can be self-configured, self-operated, and self-optimized. Wireless communication operators want their base station networks to be deployed without consulting technical experts. With this feature, you can quickly install base stations, configure parameters required for base station operation, quickly discover neighboring cells, and automatically adjust configurations when a network fault occurs. The radio parameters of the air interface can be automatically optimized. In addition, operators expect automatic configuration and interconnection between transit nodes and network nodes and the ability to select and optimize QoS for services. The preceding functions are self-optimized networks (SON). Therefore, the SON supports early planning, mid-term operation, and later network optimization of the entire communications network.
Figure 2 Objectives of SON
SON provides the following functions:
Self-planning
Dynamically replan the network based on capacity expansion, service detection, and optimization requirements, and then go to.
Self-configuration
Automatic connection and configuration, automatic integration of new eNodeBs into the network, automatic connection setup with the EPC (S1 interface) and neighboring eNodeBs (X2 interface), and automatic configuration
Self-optimization
Automatically adjusts and optimizes local eNodeBs and network management with the assistance of UE and eNodeB measurements.
Self-healing
Automatically detects, locates, and removes faults.
What Is Self-Configuration?
Self-configuration refers to the automatic configuration and startup of the base station.
1. The purpose of self-configuration is to standardize the configuration parameters of the base station. The upper-layer software can automatically configure the BTS to ensure the correct running status only when the BTS configuration parameters are standardized.
2. Self-configuration enables the auto-deployment function of the base station to take effect when the base station is installed on the base station. After the base station is powered on, it automatically connects to the upper-level management system to obtain the required data and software. Configuration data is automatically delivered and loaded, the software is automatically installed, IP addresses are automatically allocated, radio transmission parameters are automatically updated, and the configuration status is automatically updated to the upper-layer NMS (network management system).
What is self-optimization (ANR)?
Figure 3 Self-optimization-ANR
1. The source eNodeB delivers the UE measurement configuration, instructing the UE to measure neighboring cells based on the configuration requirements.
2. The UE reports the PCI that meets the measurement configuration to cell A in the form of measurement reports. The measurement report contains the PCI of cell B. The source eNodeB finds that the PCI of cell B does not exist in its NCL. Then, the UE continues the following procedure.
3. The UE reads the ECGI, tracking area code (TAC), and PLMN ID list of cell B based on the newly discovered PCI.
4. Through proper scheduling, the source eNodeB allows the UE to read the ECGI, TAC, and PLMN ID of cell B over the BCH（Tracking Area Code）.
5. The UE reports the read ECGI, TAC, and PLMN ID to the source eNodeB.
6. The source eNodeB adds the newly discovered neighboring cells to the NCL and adds the neighbor relationships to the NRT（neighboring relation table）.
What Is Self-Optimization MRO?
Figure 4 Self-Optimization-MRO
MRO (Mobility load balance) identifies different handovers and measures them, such as the proportion of handover delays, proportion of premature handovers, and measurement of handovers to bad cells. MRO optimizes handover-related parameters based on measurement results. For example, the eNodeB automatically adjusts and optimizes handover parameters and neighbor relationships. This minimizes handover failures, call drops, and unnecessary handovers on the network increases the handover success rate, enhances UE mobility, and improves user experience and resource utilization.
What is self-optimization-MLB?
Figure 5 Self-optimization-MLB
1. MLB implements load balancing among cells and improves network performance.
2. Load balancing is a concept in radio resource management. Resource management is to directly control resource allocation to maximize resources. SON is to adjust the parameters of the radio resource management algorithm by detecting the status of the radio system so that the radio resource management system can run better. It is a relatively slow but directional control.
3. Load balancing aims to balance the resources of the entire radio network to prevent local overload. When the terminal is in the active state, it can adjust the handover parameters of the network to hand over the terminal to the network source with a relatively low load and adjust the parameters of the cell load. This avoids potential network load imbalance caused by a call initiated by a terminal. The implementation solution is to notify neighboring cells of their own load information to each other and adjust their own cell handover parameters by knowing the load information of surrounding cells to achieve balance.
What is Self-Healing - CODC (Cell Outage Detection and Compensation)?
Figure 6 Self-Healing - CODC
Cell outage indicates that services cannot be accessed or KPIs deteriorate sharply due to faults or alarms in a cell. This greatly affects network performance, especially on a single-frequency and single-mode network. User experience is greatly affected.
The Cell Outage Management feature performs the following functions in sequence:
1. Cell outage detection is used to monitor the cell status on the network and detect outage cells.
2. Service adjustment in outage cells is used to transfer UEs in outage cells. To prevent new UEs from accessing the outage cell, prohibit incoming handovers to the local cell, and trigger online UEs to be handed over to neighboring cells.
3. The cell outage recovery operation is used to restore the services of the cell by reactivating the outage cell.
The emergence of SON improves user experience and reduces operators' costs. It's a win-win good thing.
That's what I'm sharing about SON. Comments are welcome.
