Sara Modarres Razavi

Exploiting Tracking Area List for Improving Signaling Overhead in LTE

Reducing the overhead required for tracing mobile devices is one of the major aspects in the study of mobility management of a cellular network. The Long Term Evolution (LTE) systems give a more flexible configuration of Tracking Area (TA) design by means of Tracking Area List (TAL). Being a novel concept, TAL goes beyond the capability of the conventional TA approach. Although TAL is expected to be able to reduce the overall signaling overhead by overcoming a couple of major limitations of the conventional TA concept, how to apply TAL in large scale networks, remains unexplored. In this paper, we present a novel approach for allocating and assigning TA lists. The approach does not require any data other than what is needed for conventional TA design. We present numerical results to illustrate the approach for a realistic network of Lisbon city. The experiments demonstrate the ability of TAL in reducing the signaling overhead compared to the conventional TA concept.

Dynamic Tracking Area List configuration and performance evaluation in LTE

Reducing the signaling overhead for tracing user equipment (UE), while maintaining the improved performance over time despite the changes in UE location and mobility patterns, is a challenging issue in the area of mobility management. Flexibility and automatic reconfiguration are two significant features in Long Term Evolution (LTE) systems. The Tracking Area List (TAL) is a novel concept in LTE systems, which allows a more flexible configurations, expecting to reduce the overall signaling overhead. In this paper, we first present a ”rule of thumb” method to allocate and assign TALs for a network. The easily applied approach does not require any data other than what is available for conventional TA design. Second we compare the performance of an optimum conventional TA design with the suggested TAL design for a large scale network in Lisbon, Portugal. A thorough computation is done to make a justified evaluation. We follow the comparison during specific time intervals for one complete day, and we illustrate the performance of reconfiguration for each approach. The results clearly demonstrate the ability of dynamic TAL in reducing the signaling overhead and maintaining a good performance due to reconfiguration compared to the conventional TA design.

Performance improvement of LTE tracking area design: a re-optimization approach

A key component in location management in Long Term Evolution (LTE) networks is the design of tracking areas (TAs). TA design must be revised over time in order to adapt to changes and trends in user location and mobility patterns. In this paper we present a re-optimization approach for revising a given TA design. The approach is justified by the fact that, once a TA design is in use, it is not feasible to deploy a greenfield design that significantly differs from the current one. By re-optimization, the design is successively improved by re-assigning some cells to TAs other than their current ones. Moreover, to account for the service interruption of TA reconfiguration, there is a limit on the amount of traffic affected by the re-assignments. To solve the resulting NP-hard optimization problem, we develop an algorithm based on repeated local search. We present computational experiments for a realistic TA planning scenario for the city of Lisbon. The experiments demonstrate the effectiveness of the proposed approach.

Mitigating mobility signaling congestion in LTE by overlapping tracking area lists

Avoiding signaling congestion in location management of cellular networks is becoming increasingly important as the population of user equipments (UEs) rapidly grows. Congestion can occur due to massive mobility of UEs behaving in a similar manner, such as the train movement scenario. In this paper, we explore the use of overlapping tracking area lists (TALs) in Long Term Evolution (LTE) networks for congestion mitigation that is not possible with the conventional tracking area concept. Each cell can use multiple and overlapping TALs, to be allocated to UEs requesting their TALs from the cell. We show that finding the optimal proportional use of TALs can be formulated as a linear program. Solving the linear program minimizes the maximum tracking area updates occurring between the cells. We present numerical results to illustrate the performance of the approach. The experiments demonstrate the effectiveness of overlapping TALs for mitigating mobility signaling congestion.

Mitigating signaling congestion in LTE location management by overlapping tracking area lists

Avoiding signaling congestion is a key aspect in location management of cellular networks. The signaling load in this context corresponds to the use of location update and paging messages for tacking user equipments (UEs). Signaling congestion may occur due to many UEs behaving in a similar manner, e.g., massive and simultaneous UE mobility in a train movement scenario. For Long Term Evolution (LTE) networks, location management can be based on the use of tracking area lists (TALs), each being a list containing multiple tracking areas (TAs). In this paper, the scheme of using TALs with overlapping TAs is applied for signaling congestion mitigation. One or multiple TALs that potentially overlap are allocated to each cell, and the TALs are assigned to the UEs that make their location updates in the cell. We derive linear programming formulations for finding the optimal proportional use of overlapping TALs for congestion avoidance. The main advantage of our approach is that it does not require the collection of detailed UE mobility information apart from what is available to the network. We report numerical results for realistic scenarios. The optimization approach yields promising results for reducing signaling congestion, and the performance region of optimized overlapping TALs goes significantly beyond the capability of the conventional TA scheme.

Positioning for the Internet of Things: A 3GPP Perspective

Many use cases in the Internet of Things (IoT) will require or benefit from location information, making positioning a vital dimension of the IoT. The 3GPP has dedicated a significant effort during its Release 14 to enhance positioning support for its IoT technologies to further improve the 3GPPbased IoT eco-system. In this article, we identify the design challenges of positioning support in LTE-M and NB-IoT, and overview the 3GPPs work in enhancing the positioning support for LTE-M and NB-IoT. We focus on OTDOA, which is a downlink based positioning method. We provide an overview of the OTDOA architecture and protocols, summarize the designs of OTDOA positioning reference signals, and present simulation results to illustrate the positioning performance.

Optimizing the Tradeoff between Signaling and Reconfiguration: A Novel Bi-Criteria Solution Approach for Revising Tracking Area Design

Improving the tracking areas (TA) configuration over time to reduce signaling overhead is vital for location management of Long Term Evolution networks. The user location and mobility patterns have ...

On dynamic signaling congestion mitigation by overlapping tracking area lists

Mitigating signaling congestion of tracing user equipments (UEs), adaptively to the changes in UE location and mobility patterns is a challenging issue in mobility management of Long Term Evolution (LTE) networks. Signaling congestion usually occurs due to many UEs behaving in a similar manner, e.g., massive and simultaneous UE mobility in a train movement scenario. LTE networks allow the use of tracking area lists (TALs), each being a list containing multiple tracking areas (TAs). The overlapping TAL scheme has been previously used for signaling congestion mitigation for snapshot scenarios. For maintaining the improved performance over non-list-oriented TA configuration over time, an automatic dynamic configuration framework, which is a key aspect in Self-Organizing Network (SON), has been applied in this paper. We develop a linear programming model for optimal TAL configuration. Repetitively solving the model for different time intervals gives an evaluation framework on the performance of SON location management. Comprehensive numerical results are presented in this study using a large-scale realistic network scenario. The experiments demonstrate the effectiveness of the SON dynamic framework in reducing the total signaling overhead of the network compared to the static TA. Moreover, the overlapping TAL scheme significantly improves the performance of the network in the tracking area update congested scenarios over the conventional TA configuration.