Self-Organising Network (SON) capabilities are of vital importance to future networks. The good news is that they are not purely conceptual, but available from Ubiquisys and being used in live networks such as Network Norway and Softbank in Japan.
Within 3GPP a number of key principles are outlined, primarily with LTE in mind, however the Ubiquisys Femto Grid has been implemented with these capabilities included for WCDMA.
The key principles are those outlined in the chart below:
3GPP SON Principles
The standard Ubiquisys standalone femto functionality provides some of these, but when femtocells collaborate as they do in the Enterprise Grid, nearly all of these are addressed, as the summary below explains:
- Coverage and capacity optimization: Dynamic power adaptation means that the coverage of the cells self-optimises according to the required coverage on a per call basis. The ability of the grid to adapt in the case of loss of service from a cell means that the capacity is optimised
- Interference Reduction: Rather than cell switching on/off, Ubiquisys utilises an adaptive algorithm that limits the max power used in downlink and uplink according to the conditions of the surrounding macrocells and femtocells
- Automated Configuration of Physical Cell Identity: Ubiquisys provides auto-configuration of physical cell ID by the femtocell itself and its algorithms ensure “collision free” and “confusion free” capabilities
- Mobility Robustness Optimisation: Ubiquisys implements techniques to learn from history of the successful and unsuccessful handover rates on a per HNB to HNB basis and adapts the handover algorithms accordingly, by varying the thresholds for reporting measurements and the one-on-one cell stickiness
- Mobility Load Balancing Optimisation: Reactive and proactive load balancing are enabled by the exchange of real-time load information between the HNBs. Ubiquisys’ load balancing algorithms work across overlapping cells in the Grid
- RACH Optimisation: The Ubiquisys solution coordinates the power and interference of neighbour femtocells RACHs. This is being developed to cover the LTE radio technology accordingly
- Automatic Neighbour Relation Function: Ubiquisys’ uses an advanced solution for automatic neighbour discovery, with full listen mode, fast sniff mode and with HNB to HNB information exchanges, to build a complete macro and femtocells neighbour list, with all parameters needed for handover procedures
- Inter-cell Interference Coordination: Ubiquisys provides advanced techniques of interference prevention/mitigation, both between HNB and macrocells and between HNBs