SON Self Configuration
- Self Configuration aspects of Self Organising Networks, SON, how they work, and their effect on the cellular networks.
The self-configuration aspects of self-organising networks, SON enable new cell sites to be added using a plug and play approach. Self-configuration reduces the level of installer input and thereby reduces costs while ensuring that the cell integrates correctly into the overall network.
As cellular networks become more complicated changes to hardware and software including the deployment of new network elements becomes more complicated.
As cells become smaller to accommodate the increased levels of overall network data traffic and as revenues per bit fall, it becomes even more important to ensure that this process is automated as much as possible.
SON Self Configuration major features
There are a number of major elements that are included within the self-configuration of the new base station. These include aspects such as the following:
- Automatic configuration of initial radio transmission parameters : The automatic configuration of the radio transmission parameters within the SON Self configuration is of great importance. While some information will be available centrally, other information is best gathered by the base station or eNB itself. With a base station in place it is normally found that the planned data is not quite as expected and some adjustments need to be made to provide the optimum performance and this procedure can be very time consuming.
A technique called Dynamic Radio Configuration, DRC is used which allows the base station to become adaptive to the current radio network topology. The DRC configures a variety of items including the cell ID, initial power and antenna tilt settings, etc..
The various settings required can be determined by the base station, eNB when it is in its installation process. These will ensure that real measured parameters are used rather than estimated ones from any planning tools.
- Automatic neighbour relation, ANR, management: One of the major labour intensive activities for mobile network operators is the updates for neighbour cell relationships to facilitate easy handovers. It is necessary to have the correct neighbour relationships in place otherwise this will result in dropped calls as a result of handovers failing to complete correctly.
The manual update of neighbour relationships become even more complicated as the network needs to decide if it can handover to a neighbour cell with a similar radio access technology, or whether it has to change, e.g. from LTE to HSPA, etc.. The UE is provided with a neighbour list by the base station or Node B, and this provides the frequencies the UE should monitor for handover.
The elements of Self Organising Networks, SON that provide this element of SON self-configuration includes the automatic neighbour cell configuration and this can be largely automated. Network performance will also benefit from the optimised and up to date lists as correct neighbour lists will increase the number of successful handovers, and also reduce the network load from additional set-ups required for poor handovers.
An additional advantage is that with LTE possessing a very flat structure to improve latency, etc, the operator would need to manually configure huge amounts of neighbour data within the LTE eNBs. In this way SON self-configuration of the neighbour relationships can significantly reduce OPEX and improve performance and efficiency while providing a better service for the users, thereby having a positive impact on churn.
- Automatic connectivity management: The auto-connectivity system provides the ability for the new base station, eNB to automatically connect to its domain management system. There are several stages involved in the set-up of the connectivity:
- Basic connectivity set-up: The base station, eNB requires an initial IP configuration to enable backhaul connectivity to be established. This initial IP configuration may be replaced later with a more permanent, post set-up IP configuration.
- Initial secure connection set-up: The security of the backhaul connection is based upon the use of keys. Once the keys have been set up and verified, the secure communications is possible. Only when secure communication is available can data be transferred.
- Site identification: This is required to define which configuration data is to be used. This is needed because most sites require some pre-configuration data to be used.
- Download of final configuration and transport parameters: This stage must be completed before the next stage in the connectivity management can take place.
- Secure connection set-up: At this stage the temporary secure connection is taken down and a new connection with full security is established. This may use either TLS or IPsec.
- Self-test: A self-test is normally performed as part of the SON self-configuration to ensure the correct operation of the equipment prior to final active service.
- Automatic inventory: This activity includes aspects such as identifying what hardware boards are fitted, software level, antennas, etc. In this way the base station is able to identify its capabilities. As most of the base stations will have various options that could be fitted dependent upon the capabilities required, it is necessary for the SON self-configuration software to perform an inventory check before proceeding further.
SON self-configuration deployment
The adoption of SON self-configuration involves the whole network. Capability must be introduced into many areas of the network to provide for the self-configuration to be undertaken. While many of the facilities can be self-configured, so pre-planning is normally required to enable the system to start operation.
However in many instances new cells can be added with the minimum of input from the operator. Femtocells are a prime example of this, they are deployed on an ad-hoc bases. They need to undertake all the stages of self-configuration that are outlined here.
By Ian Poole
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