Kristina Zetterberg

Neighbor Cell Relation List and Physical Cell Identity Self-Organization in LTE

Automation of radio network management is a key determinant to work reduction for wireless operators. By replacing time consuming and costly tasks with automatic mechanisms, operational expenditure can be reduced. In this paper we present a method for automatic configuration of locally-unique physical cell identities and neighbor cell relation lists in 3G long term evolution (LTE). This method makes use of mobile measurements to update the neighbor cell relation lists in the cells and to detect local cell identity conflicts, report the conflicts to the operation support systems (OSS) and resolve them. The performance of the approach is determined using simulations of realistically deployed macro networks. Conducted simulations illustrate the ability of the method to resolve local cell identity conflicts. In particular, the method is capable of both accommodating new cells and handling a worst case scenario where all cells are initiated with the same local cell identities and where neighbor cell relation lists are empty.

Embedding Multiple Self-Organisation Functionalities in Future Radio Access Networks

Wireless network operators today allocate considerable manual effort in managing their networks. A viable solution for lowering the manual effort is to introduce self-organisation functionalities. In this paper we discuss the challenges that are encountered when embedding multiple self-organisation functionalities into an overall self-organisation concept for future wireless networks. We foresee that there will most likely be a need of a rather complex coordination mechanism for handling multiple self-organisation functionalities in future wireless access networks.

On self-optimization of the random access procedure in 3G Long Term Evolution

Operationally efficient radio networks typically feature a high degree of self-organization. This means less planning efforts and manual intervention, and a potential for better radio resource utilization when network elements adapts its operation to the observed local conditions. The focus in this paper is self-optimization of the random access channel (RACH) in the 3G Long Term Evolution (LTE). A comprehensive tutorial about the RACH procedure is provided to span the complexity of the self-optimization. Moreover, the paper addresses RACH key performance metrics and appropriate modeling of the various steps and components of the procedure. Finally, some coupling between parameters and key performance metrics as well as self-optimization examples are presented together with a feasibility discussion. The main ambition with this workshop paper is to present and define a relevant set of self-optimization problems, rather than to provide a complete solution.

Neighbor cell relation list and measured cell identity management in LTE

Radio network management simplification concerns to some extent the removal, not the simplification, of tasks. In this paper we present an approach for automatic network management in 3G long term evolution (LTE), namely, methods for automatic configuration of locally-unique physical cell identities and neighbor cell relation lists. We show that these issues can be removed from the list of planning tasks and completely replaced by autonomous algorithms. These algorithms make use of mobile measurements to detect local cell identity conflicts, resolve them, and to update the neighbor cell relation lists in the cells. The performance of the approach is determined using simulations of realistically deployed macro networks. The simulations illustrate the ability of the algorithms to resolve local cell identity conflicts. In particular, the algorithms are capable of both accommodating new cells and handling a worst case scenario where all cells are initiated with the same local cell identities and where neighbor cell relation lists are empty. The contributions in this paper are meant to aid operators by allowing them to replace time consuming and costly tasks with automatic mechanisms, thus, reducing operational expenditure.

Self-Optimisation of Admission Control and Handover Parameters in LTE

In mobile cellular networks the handover (HO) algorithm is responsible for determining when calls of users that are moving from one cell to another are handed over from the former to the latter. The admission control (AC) algorithm, which is the algorithm that decides whether new (fresh or HO) calls that enter a cell are allowed to the cell or not, often tries to facilitate HO by prioritising HO calls in favour of fresh calls. In this way, a good quality of service (QoS) for calls that are already admitted to the network is pursued. In this paper, the effect of self-optimisation of AC parameters on the HO performance in a long term evolution (LTE) network is studied, both with and without the self-optimisation of HO parameters. Simulation results show that the AC parameter optimisation algorithm considerably improves the HO performance by reducing the amount of calls that are dropped prior to or during HO.

Towards Random Access Channel Self-Tuning in LTE

Future radio access networks are expected to show a high degree of self-organization. This paper addresses self- tuning of the random access channel (RACH) in the 3G Long Term Evolution (LTE). The feasibility of self-tuning is investigated by means of simulation, where the coupling between several parameters and the performance of RACH is provided. The conclusion of the simulations is that RACH self-tuning is indeed possible given that UE assisted measurements are available for the self-tuning mechanism.

On design principles for self-organizing network functions

With an increasing number of SON functions deployed in cellular radio networks, conflicts between the actions proposed by independently-designed and distributed SON functions may arise. The process of minimizing the occurrence, and the consequences, of such conflicts is referred to as SON coordination. SON coordination can be achieved either by a separate entity, a SON coordinator, controlling the actions of each SON function during operation, or in the design of the SON functions as such, through a conflict free SON design. In both cases, the SON functions should be designed in a way compliant with the coordination method used. This paper proposes a number of SON design principles to apply in order to achieve this. In the case of an operational SON coordinator, SON functions should be able to deal with the possible actions that are taken by the SON coordination function in order not to worsen the problems experienced in the network. In the case of conflict free SON design the aim is at removing potential conflicts already in the design phase. The ambition of this paper is not to provide a complete set of design guidelines that address all aspects. Instead, the target is to open up the discussion on the distributed SON design principles in the community.

On Heterogeneous Networks Mobility Robustness

Heterogeneous network 3GPP LTE deployments are considered as a prime candidate to meet increasing demand for mobile broadband service coverage and capacity. Such deployments also need to support mobility that is as robust as in traditional macro deployments. In this paper, we analyze the handover performance in heterogeneous deployments to better understand potential behavior of automatic handover parameter adjustments. Such a Self-Organizing Network (SON) feature is commonly known as Mobility Robustness Optimization (MRO). The analyses indicate difficult challenges with handovers from low power to high power base stations, and an evolved handover procedure that improves the user experience during such times is presented. These results are key for developing an MRO algorithm for heterogeneous networks.

On automatic establishment of relations in 5G radio networks

One of the first key self-organizing features introduced in LTE was Automatic Neighbor Relations (ANR), a function for automatically generating relations between radio network entities that is needed for many features such as active-mode mobility, load balancing and dual connectivity. Given the benefits of ANR in LTE, we foresee that procedures for relations establishment will be an important integrated part of 5G systems as well. Moreover, the new emerging technology components of 5G such as massive beamforming expand the scope of relations beyond the neighbor relations of LTE. In this paper, we give an overview of key 5G radio access components, discuss the need for different types of identifiers and relations, and comment on the impact from the ultra-lean design principle of 5G. The paper also discusses some possible procedures for automatic relation establishment in consideration of the specific 5G aspects.