Provision of seamless service to multimedia applications in cellular wireless networks largely depends on the way calls are handled during handoff. Hence, sufficient resources must be provided for handoff (HO) connections when a mobile station (MS) moves from one cell to another. Effective allocation of resources can be achieved when the exact future trajectory of MSs is known in advance. However, such a scenario is unrealistic. The next best possibility is to employ user mobility prediction to determine the cell(s) a MS will likely visit in the near future. In this paper, we present an extensive survey and classification of channel (bandwidth) reservation schemes which employ user mobility prediction in the resource reservation process. We also present a survey and classification of call admission control (CAC) schemes, including discussion of prioritized and non-prioritized handoff schemes, which can be useful for researches both in academia and industry.

Predictive mobile-oriented channel reservation schemes in wireless cellular networks

Link dimensioning, i.e., selecting a (minimal) link capacity such that the users' performance requirements are met, is a crucial component of network design. It requires insight into the interrelationship among the traffic offered (in terms of the mean offered load M, but also its fluctuation around the mean, i.e., 'burstiness'), the envisioned performance level, and the capacity needed. We first derive, for different performance criteria, theoretical dimensioning formulas that estimate the required capacity c as a function of the input traffic and the performance target. For the special case of Gaussian input traffic, these formulas reduce to c = M + αV, where α directly relates to the performance requirement (as agreed upon in a service level agreement) and V reflects the burstiness (at the timescale of interest). We also observe that Gaussianity applies for virtually all realistic scenarios; notably, already for a relatively low aggregation level, the Gaussianity assumption is justified. As estimating M is relatively straightforward, the remaining open issue concerns the estimation of V. We argue that particularly if V corresponds to small time-scales, it may be inaccurate to estimate it directly from the traffic traces. Therefore, we propose an indirect method that samples the buffer content, estimates the buffer content distribution, and 'inverts' this to the variance. We validate the inversion through extensive numerical experiments (using a sizeable collection of traffic traces from various representative locations); the resulting estimate of V is then inserted in the dimensioning formula. These experiments show that both the inversion and the dimensioning formula are remarkably accurate.

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Resource dimensioning through buffer sampling

Call admission control (CAC) strongly influences the performance of 3G/4G spread spectrum systems because it determines the number of active users that are admitted to the network, i.e., influences spectral efficiency. A novel air interface CAC algorithm is introduced in this paper. It optimizes the utilization of radio resources and provides real-time adaptation to the radio channel with generalized multiplicative fading. Users are handled as memory-less traffic sources. The suggested CAC method was evaluated for lognormal fading and on/off traffic.

Dynamic Call Admission Control for Uplink in 3G/4G CDMA-Based Systems

Parsimonious estimates of bandwidth requirement for quality of service packet networks

In packet based communication networks, loss bound is a significant parameter in Quality of Service(QoS) guarantees, especially in real-time distributed applications. Unfortunately, most approaches presenting loss problem are based on the approximates of the buffer overflow probability, which have been shown incorrect in most of time. Recently, network calculus has been widely used to obtain the performance bounds in QoS analysis, and a deterministic result for loss bound has been proposed. Different from previous research, this paper wants to emphasize the importance of stochastic probability in the study of loss bound. The loss issue is examined from a envelop process perspective and a stochastic loss bound with moment generating function are obtained finally. A brief conclusion and the future work is introduced in the last section.

An Extended Stochastic Loss Bound with Moment Generating Function

Quantifying Resource Usage : A Large Deviation-Based Approach (Special Issue on Internet Technology II)

This paper identifies the requirements placed against a resource manager function for use in QoS-enabled IP networks. The structure of the Internet and the composition of the services motivate the development of on-line resource brokers that can make admission decisions in real time, based on the best up-to-date information available on the state of the network. The difficulties with traffic models and traffic characterisation stimulate the use of measurement-based techniques that bypass the modelling step and provide the resource requirements of the traffic directly. The paper introduces a novel method for the computation of the bandwidth requirement of Internet traffic flows using the many sources asymptotics. The estimator method significantly reduces the computational complexity of the calculations, allowing the real-time operation of the algorithm even in a measurement-based environment. The method delivers bandwidth-type quantity, the format preferred by Internet control applications. The savings arising from the reduced computational complexity compared to existing methods are demonstrated in a numerical example.

Alternative admission rules based on the many sources asymptotics

This paper reviews the applicability of simplified bandwidth requirement estimators that need only the mean and the peak rates of traffic flows as input, instead of the full statistical description of the traffic required by their original form. The estimators approximate the effective bandwidth function, the key component of the bandwidth requirement estimate, with the logarithmic moment generating function of on-off source. It is demonstrated that this on-off type approximation has to be used with care as it results in a loss of information about the traffic streams. This is manifested in the reduction of the advanced bandwidth estimator method of the many sources asymptotics into the basic Chernoff-type technique. As a consequence bandwidth requirement estimator built on/off type approximation overlook the multiplexing gain occurring in the buffers, which results in overly conservative estimates close or equal to the peak rate when applied to traffic aggregates.

On the applicability of the on-off type approximation of the effective bandwidth function

Towards efficient decision rules for admission control based on the many sources asymptotics

In cellular mobile communication systems, the mobility of vehicles affects some important parameters, such as handover rates, channel occupancy times and blocking probabilities. The present work is based on a model proposed in [1] that suggests a convenient and practical approach to build an analytic traffic model, which also includes the effect of vehicle mobility.

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Papers

Quantifying Resource Usage : A Large Deviation-Based Approach (Special Issue on Internet Technology II)

Alternative admission rules based on the many sources asymptotics

On the applicability of the on-off type approximation of the effective bandwidth function

Towards efficient decision rules for admission control based on the many sources asymptotics

Mobility and Traffic Analysis for WCDMA Networks