A Flexible Handoff Prioritization Scheme for Improved Quality of Service in Mobile Networks

Efficient handoff prioritization schemes make mobile networks to perform better. However, most existing schemes have the common characteristics of reducing the call drop probability and increasing the call block probability; this decreases the general network performance. The reservation of channels for the use of handoff calls alone has not proved to be an efficient approach to optimally utilize the network limited channel resources. These approaches are such that even when the reserved channels are not in use, new calls could still get blocked if there are no channels among the shared channels to allocate to the new calls. In trying to maintain an improved QoS for handoff calls while ensuring an acceptable QoS for new calls, different methods have been suggested for new calls to access and use the reserved channels while priority is still given to handoff calls since it is more frustrating to have an on-going call dropped than blocking a new call. Network parameters such as call drop probability and traffic intensity had been used separately to determine when new calls could be granted access to use the reserved channels or otherwise. Handoff queuing and other call admission control approaches have also been used. This paper proposes the use of traffic intensity and call drop probability to decide whether the new calls could use the reserved channels or not. Also proposed is the need to keep the number of reserved channels fixed rather than calculating the numbers to reserve per time therefore reducing the computational complexity of the scheme. The simulation results showed an improved QoS for the handoff calls while producing a commensurate improvement for the new calls through a reduced Call drop Probability and call block probability. Keywords: Call block probability, Call drop probability, traffic intensity, handoff prioritization, mobile network DOI: 10.7176/JIEA/11-1-03 Publication date: January 31st 202

Network-Based UE Mobility Estimation in Mobile Networks

International audienceThe coexistence of small cells and macro cells is a key feature of 4G and future networks. This heterogeneity, together with the increased mobility of user devices can generate a high handover frequency that could lead to unreasonably high call drop probability or poor user experience. By performing smart mobility management, the network can pro-actively adapt to the user and guarantee seamless and smooth cell transitions. In this work, we introduce an algorithm that takes as input sounding reference signal (SRS) measurements available at the base station (eNodeB in 4G systems) to estimate with a low computational requirement the mobility level of the user and with no modification at the user device/equipment (UE) side. The performance of the algorithm is showcased using realistic data and mobility traces. Results show that the classification of UE speed to three mobility classes can be achieved with accuracy of 87% for low mobility, 93% for medium mobility, and 94% for high mobility, respectively

Vertical Handoff Decision Criteria with LTE Network

A handover decision scheme in LTE networks either based on single or multiple criteria. The number of criteria is directly depending on the totalhandovertime.A vertical handover decision algorithm based on the fuzzy control theory. The algorithm takes into consider the factors of Power Level, Cost and Bandwidth. After establishing the membership functions, membership degrees of corresponding factors can be determined, which are processed by the Weight Vector. Finally, the Fuzzy Vertical Handoff Decision Vector is derived and vertical handover decision can be made. It is shown through simulation that the algorithm realizes the optimized vertical handover by evaluating and analyzing various input parameters

An Alternative Approach to the Determination of Optimum Reservations for Handover in GSM Networks

This work presents an alternative approach to the computation of the optimum reservations to be made in a GSM network for handover call requests. Prioritizing handover calls in a cellular network such as the GSM is necessary so as to guarantee seamless connection. Successful handover enhances the quality of service (QoS) of a network as the later is directly dependent on call continuity. In a previous analysis, the expression for the optimum reservations to be made was determined using the Gaussian Elimination method which had limitations because the power series used only considered the second order. Also, the set of equations to be solved was reduced to three thereby giving a result that does not quite represent the general system. In this work, the logarithmic approach is adopted which captures the total system capacity under test. A more reliable function for the determination of optimum reservations required in a system is thus derived. This new approach is also compared with that obtained using the Gaussian Elimination method

Open vs Closed Access Femtocells in the Uplink

Femtocells are assuming an increasingly important role in the coverage and capacity of cellular networks. In contrast to existing cellular systems, femtocells are end-user deployed and controlled, randomly located, and rely on third party backhaul (e.g. DSL or cable modem). Femtocells can be configured to be either open access or closed access. Open access allows an arbitrary nearby cellular user to use the femtocell, whereas closed access restricts the use of the femtocell to users explicitly approved by the owner. Seemingly, the network operator would prefer an open access deployment since this provides an inexpensive way to expand their network capabilities, whereas the femtocell owner would prefer closed access, in order to keep the femtocell's capacity and backhaul to himself. We show mathematically and through simulations that the reality is more complicated for both parties, and that the best approach depends heavily on whether the multiple access scheme is orthogonal (TDMA or OFDMA, per subband) or non-orthogonal (CDMA). In a TDMA/OFDMA network, closed-access is typically preferable at high user densities, whereas in CDMA, open access can provide gains of more than 200% for the home user by reducing the near-far problem experienced by the femtocell. The results of this paper suggest that the interests of the femtocell owner and the network operator are more compatible than typically believed, and that CDMA femtocells should be configured for open access whereas OFDMA or TDMA femtocells should adapt to the cellular user density.Comment: 21 pages, 8 figures, 2 tables, submitted to IEEE Trans. on Wireless Communication