In this paper, we investigate the impact of mobility on user performance in the context of dense LTE-A networks. To this end, we propose simple analytical models that capture mobility through the distribution of the mobile users sojourn time, i.e., the time a mobile user is physically present in a given cell. We use these models to derive the throughput of users who remain spatially static during their whole data transmission and the amount of handovers generated by moving users. We analyze the impact on performance of some key parameters such as the size of the small cell, the speed and proportion of mobile users and the distribution of their sojourn time. Numerical evaluation and simulation results are provided to assess the accuracy of the latter model and gain insight into the global system performance.

In this paper, we propose analytical models to derive the performance of dual carrier mobile HSDPA mobile networks. Specifically, we analyze the flow-level performance of two inter-carrier load balancing schemes and the gain engendered by Carrier Aggregation (CA). CA is one of the most important features of HSPA+ networks; it allows devices to be served simultaneously by several carriers. We propose Volume Balancing (VB) and Join the Fastest Queue (JFQ), a load-balancing mechanism that allows the traffic of non-CA users to be distributed over the aggregated carriers. We then evaluate the performance of both CA and non-CA users by means of analytical modeling. We show that the proposed schemes achieve efficient load balancing. We also investigate the impact of mixing traffic of CA and non-CA users in the same cell and show that performance is practically insensitive to the traffic mix.

Caching is a key component for Content Distribution Networks and new Information-Centric Network architectures. In this paper, we address performance issues of caching networks running the RND replacement policy. We first prove that when the popularity distribution follows a general power-law with decay exponent α > 1, the miss probability is asymptotic to O( C1-α) for large cache size C. We further evaluate network of caches under RND policy for homogeneous tree networks and extend the analysis to tandem cache networks where caches employ either LRU or RND policies.

A central objective in designing LTE networks was to provide a better quality of experience for the end user. One of the implemented enhancements is a direct connection between neighbouring eNodeBs through the X2interface. This interface enables mobility management and the transfer of the user's data in case of a handover. The aim of this paper is to provide an analytical model to dimension the X2link bandwidth under certain performance objectives. We take into account radio interface conditions in order to establish handover rates and we use the Kaufman-Roberts formula to compute the needed X2bandwidth. We also study the impact of traffic management schemes (admission control and QoS differentiation) and of transport protocols on X2dimensioning.

A general logarithmic equivalent is given for the stationary complementary distribution function of a fluid queue fed by a large number of on/off sources. Close asymptotic approximations are also provided. These approximations are numerically validated and applied to the dimensioning of an ATM multiplexer offered variable bit rate sources of general on/off type.>

When variable-bit-rate sources are multiplexed in an asynchronous transfer mode (ATM) network, there arise queues with a particular form of correlated arrival process. Such queues are analyzed by exploiting a result expressing the distribution of work in system of the G/G/1 queue originally derived by V.E. Benes (1963). A simple alternative demonstration of this result is analyzed and extended to the case of fluid input systems. The result is applied first to a queue where the arrival process is a superposition of periodic sources (the Sigma D/sub i//D/1 queue), and then to a variable-input-rate constant-output-rate fluid system. The latter is shown to model the so-called burst component of the considered superposition queuing process. The difference between this and the real queue, the cell component, can be evaluated by means of the results obtained for the Sigma D/sub i//D/1 queue. The relative importance of these two components is explored with reference to the particular case of a superposition of on/off sources.>