Call Blocking Probability Research Articles

Call Blocking Probability and Effective Throughput for Call Admission Control of CoMP Joint Transmission

Coordinated multipoint transmission (CoMP) with the joint transmission (JT) scheme is employed in cellular networks to improve data rate and cell-edge throughput and/or to increase system throughput. In CoMP-JT, since the user equipment (UE) is capable of receiving the desired signal from an adjacent cell, as well as from its serving cell, it can achieve an improved signal-to-interference ratio (SIR). However, this scheme entails exhaustion of resources in serving base stations. In this paper, we propose a call admission control scheme (CAC) to improve the performance of CoMP-JT-based cellular systems. In this CAC scheme, the CoMP-JT technique is applied to UEs located near the edge of a cell. To establish an analytical model for CoMP-JT-based cellular systems, we introduce a model for traffic analysis using a 2-D Markov chain and approximate the computation of the power sum of multiple lognormal random components in a multicell environment. Performances of CoMP-JT-based cellular systems are evaluated with respect to two quality-of-service (QoS) constraints pertaining to call-blocking and outage probabilities, respectively, from the network-layer and the physical-layer perspectives. We first measure the resource utilization and call blocking probability for the downlink resources for various offered loads in the cell. Based on that, we obtain the outage probability and effective throughput of the system. The analytical results are compared with computer simulations. Finally, we consider the dynamic point selection (DPS) scheme that is a modified version of the JT scheme, in which some resources of adjacent cells are muted.

Public Safety Priority-Based User Association for Load Balancing and Interference Reduction in PS-LTE Systems

This paper addresses the issues of user association in multi-tier heterogeneous networks (HetNets) to reduce co-channel interference and provide load balancing for proactively offloading users onto mobile personal cells (mPC). Previously, much of the literature discussed the user' association problem for HetNets with conventional fixed small cells. The problem discussed in the existing literature is easy to analyze owing to fix nature of the small cells. In this paper, we focus on the mPC instead of fixed small cells, which complicates the user association problem due to its nature of mobility. In this paper, we propose the public safety (PS) users priority-based mPC user association (PS-UA) scheme for load balancing and interference reduction in highly fluctuating PS long-term evolution systems. The proposed scheme improves the user-association problem by minimizing call blocking probability (CBP) according to the network load conditions and PS user priority. Moreover, it further improves user signal-to-interference-and-noise ratio by implementing enhanced intercell interference coordination scheme to further reduce the interference to the offloaded users. System-level simulations confirmed the validity of the proposed PS-UA scheme, because it convincingly reduces the CBP for PS users as compared with the conventional static user association scheme.

Energy-Efficient WiFi Offloading and Network Management in Heterogeneous Wireless Networks

We consider the joint WiFi offloading, admission control, and network management for the integrated WiFi and OFDMA-based cellular network. Specifically, we propose a quality-of-service (QoS) and mobility-aware admission control scheme that efficiently offloads macrocell traffic to WiFi and integrates a novel bandwidth borrow-return strategy while guaranteeing QoS requirements for users. These QoS constraints are explicitly modeled considering the throughput performance of carrier sense multiple access with collision avoidance scheme in the IEEE 802.11 WLAN and the fractional frequency reuse in the downlink cellular network. Then, we develop an analytical model to derive the blocking probabilities for calls in different service areas of a cell. Based on this analysis, we study the joint base station switching, power control, and traffic offloading problem for energy minimization under QoS constraints. We consider the time-varying call traffic and develop an algorithm to find the optimal solution of the problem. Numerical results are presented to demonstrate the performance of the proposed cross-layer resource management framework in the integrated network.

Load Balancing Early Handoff Scheme for Multimedia Data Transmission in Wireless Networks

This study developed a load balancing early handoff scheme that enables transfer part of heavy load in a base station to the others using the overlap between base stations in wireless cellular networks. The proposed scheme reduces the new call blocking probability (CBP) and handoff call connection dropping probability (CDP) as well as to increase the resource utilization of wireless networks. Since the scheme is triggered by a connection request received by the base station, it immediately reflects the loading of the base station. The proposed load balancing early handoff policy can be integrated in diverse call admission control schemes. The effectiveness of the load balancing early handoff scheme is demonstrated by integrating it with DMTBR to improve the call admission control function. Additionally, NS2 is used to simulate the load balancing early handoff scheme in a wireless network with wrap-around model. The simulation results show that the proposed scheme can effectively improve the wireless network resource utilization.

Load‐aware user association with quality of service support in heterogeneous cellular networks

In this study, the authors propose a user association scheme with quality of service support for load balancing in heterogeneous cellular networks (HCNs), which jointly considers user's achievable rate and load level of each BS instead of only utilising the former. To reveal how HCNs should self-organise, the authors formulate it as a network-wide weighted utility maximisation problem. Note that the formulated problem is a non-linear mixed-integer one, and its optimal solutions may be very difficult to be found when it is large-scale. To solve the proposed problem, the authors design a low-complexity distributed algorithm via dual decomposition. Numerical results show that, compared with the range expansion association (REA) and best power association (BPA), the strategy has a higher load balancing level (LBL) and a lower call blocking probability (CBP). Meanwhile, the proposed algorithm occupies a very fast convergence rate when its parameters are set properly.

Wavelength decomposition approach for computing blocking probabilities in multicast WDM optical networks

We present an approximate analytical method to evaluate the blocking probabilities in multicast Wavelength Division Multiplexing (WDM) networks without wavelength converters. Our approach is based on the wavelength decomposition approach in which the WDM network is divided into layers (colors) and the moment matching method is used to characterize the overflow traffic from one layer to another. Analyzing blocking probabilities for unicast and multicast calls in each layer of the network is derived from an exact approach. We assume static routing with either First-Fit or random wavelength assignment algorithm. Results are presented which indicate the accuracy of our method.

Estimation of Always Best Connected Network in Heterogeneous Environment Based on Prediction of Recent Call History and Call Blocking Probability

Presently, the emergence of 4G heterogeneous network has attracted most of the user centric applications like video chatting, online mobile interactive classroom besides voice services. To facilitate such bandwidth hungry multimedia applications and to ensure QoS (Quality of Service), Always Best Connected (ABC) network is to be selected among available heterogeneous network. The selection of the ABC network is based on certain design parameters such as cost factor, bandwidth utilization, packet delivery ratio, security, throughput, delay, packet loss ratio and call blocking probability. In this paper, all the above mentioned design parameters are considered to evaluate the performance of Always Best Connected network under heterogeneous environment for mobile users. In addition, to select Always Best Connected network in a heterogeneous environment, a novel parameter namely recent call history-‘rch' is proposed to predict the call blocking probability (Cbp) of a network.The estimation of ‘rch' parameter in terms of Cbp avoids unnecessary hand-off and enhances the effective bandwidth utilization of a cellular network under heavy load condition.A QoS mapper submodule is proposed in the QoS broker module to predict the ‘rch' parameter of a network to select an optimum network. Further, a statistcal model based on Bayesian network using the data on recent call history is applied for Cbp estimation and simulated over various heterogeneous environment condition. The simulated results show improved performance of user centric applications when compared with non-predictive methods.

Energy-Efficient Base-Station Cooperative Operation with Guaranteed QoS

With the explosive deployment of the information and communications technology (ICT) infrastructures, the rising cost of energy and increased environmental awareness has sparked a keen interest in the development and deployment of energy-efficient communication technologies. As a major player in the ICT sector, the energy efficiency of the mobile cellular networks can be significantly improved by switching off some base stations during off-peak periods. In this paper, we propose an energy-efficient BS switching strategy, and use cooperative communication techniques among the base stations to effectively extend network coverage. We incorporate both the path-loss and fading effects in our system model, and derive closed-form expressions for two important quality of service metrics, the call-blocking probability and the channel outage probability. The proposed scheme guarantees the quality of service of the user equipments by identifying the user equipments situated at the worst-case locations. The energy-saving performance is evaluated and compared with the conventional uni-pattern operation. Both analytical and numerical results show that the proposed energy-efficient switching strategy, facilitated by BS cooperation, can provide significant energy-saving potential for the cellular networks with guaranteed quality of service.

A new MAC protocol for broadband wireless communications and its performance evaluation

This paper presents a new Time Division Multiple Access/Frequency Division Duplexing (TDMA/FDD) based Medium Access Control (MAC) protocol for broadband wireless networks, supporting Quality of Service (QoS) for real-time multimedia applications. It also gives the Call Blocking Probability (CBP), packet end-to-end delay and utilization analysis of different service classes, as they are most essential performance criterions in broadband wireless network assessment. The Connection Admission Control (CAC) mechanism in the proposed MAC efficiently organizes the bandwidth allocation for different service classes by means of a fairness based scheduling algorithm. In addition, the simulation model of the proposed MAC scheme is realized by using OPNET Modeler network simulator. The results of the analytical calculations for the CBPs are compared to those of the simulation of the proposed MAC, thus validity of the MAC protocol is proved.

Factors Reducing Call Blocking Probability by Exploiting Erlang B &C Formulas

Current and future communication schemes tend to use OFDM systems in order to provide high data transmission and less inter symbol interference.In this paper, we present the benefits of exploiting the a prior information about the structure of the Wireless channel on the performance of channel estimation for orthogonal frequency-division multiplexing (OFDM) systems. The work presented here mainly focus on channel Estimation for the various algorithm techniques which is used for OFDM system. The analytic treatment is complemented by thorough numerical investigation in order to validate the performance of the different techniques. A complete model including in both the time domain and the frequency domain is used for the multicarrier system, which models the received signal to noise ratio (SNR) of each subcarrier and further presents the estimation techniques which is describe the behavior of the OFDM system model in the wireless channel. On the other hand, the fast- varying fading amplitudes are tracked by using least-squares techniques that exploit temporal correlation of the fading process (modal filtering).

Performance Evaluation of Cellular Radio System with Directed Retry

In this paper the arrival of calls (new and handoff) in personal communications services (PCS) network are modeled according a Markov Arrival Process (MAP). The purpose of our study is to improve the performance of the cellular mobile system by using directed retry scheme. The cut of priority scheme have also been applied to provide priority to handoff calls. Here we construct tractable model using fixed channel assignment scheme with priority to handoff voice calls. The proposed directed retry scheme with finite buffering for handoff voice calls is useful for improving the handoff blocking probability of handoff voice calls. The integrated traffic model has been constructed for finite population. FIFO fashion has been taken for arrival calls. The balking behavior of the calls has also been taken into consideration. The expressions for various performance indices viz. blocking probabilities for different traffic, overall blocking probability, offered carried load etc. are determined for above model. It is clear from the analytical results that by increasing overlapping area and retrying in overlapping area, a substantial improvement can be achieved.

Decreasing the Call Blocking Probability of Broadband IPTV Services in Stationary and Peak-hour Scenarios

In the provisioning of broadband Internet Protocol TV (IPTV) services, call blocking probability (CBP) denotes the ratio of failed user requests, which is one of the most important metrics on IPTV quality of experience (QoE). This paper aims to evaluate and further to decrease the end-to-end (E2E) CBP of IPTV services in both stationary and peak-hour scenarios. At first, we analyze a currently typical xDSL based IPTV delivery network architecture and its simplification. Then, a recently developed IPTV user behavior model is briefly presented. Next, a state-vector-based simulation model is proposed to evaluate the E2E CBP in an entire IPTV delivery network with tree topology. The simulation model is then applied to both stationary and peak-hour scenarios, and thereafter, a comparative simulation study demonstrates significant differences between the E2E CBPs evaluated in the two different scenarios. After that, we elaborate an extended TV channel admission control (TCAC) scheme to be applied in an entire IPTV delivery network. Simulation experiments illustrate the potential of our TCAC scheme to enhance the IPTV QoE by relatively decreasing the E2E CBP significantly (up to 25%), in both stationary and peak-hour scenarios.

Utility‐based probabilistic call admission control for complete fairness in wireless networks

SUMMARYResource reservation or the other prioritization strategies adopted by Call Admission Control (CAC) schemes in wireless networks lead to unfair resource allocation to users belonging to different service classes (SCs) due to high divergence among the respective call blocking probabilities (CBPs). In this paper, we propose dynamic optimization of probabilistic CAC (P‐CAC) schemes to assure CAC fairness among users of different SCs in wireless networks. The approach is based on users utility combined with fairness optimization, aiming at dynamically determining the probability value in the P‐CAC scheme. This optimal probability is adjusted to network ongoing traffic, CBPs of each SC, prioritization levels characterizing the SCs supported, and the users risk aversion, which reflects their behavior toward the perceived QoS. The existence and uniqueness of the optimal probability that leads to absolute fairness among the users of a wireless network are proven. Copyright © 2012 John Wiley & Sons, Ltd.

A new queueing model for spectrum renting in mobile cellular networks

Spectrum renting is an operation practice that can be applied to relieve the temporary capacity shortages of a specific service area in wireless cellular networks. However, works in the literature do not take into account the specific feature of the present wireless technology. That is, the separate blocks of user channels are defined in each frequency band in the current standards for public mobile cellular networks, and each block should be controlled by a single network operator.This paper is the first attempt to model the spectrum renting policies and the call admission control in a realistic way. The comparison between a queueing model and a simulation model confirms that the proposed queueing model incorporating exponentially distributed call durations can be used to evaluate the performance of mobile cellular networks with call holding times following the lognormal distribution as well. Numerical results show that the variants of the Fractional Guard Channel Policy provide an efficient tool to guarantee the grade of service of handover calls at the expense of increased blocking probability of fresh calls. Furthermore, only spectrum renting can be used to decrease the blocking probability of fresh calls without compromising the grade of service of handover calls.

A Cooperative Cell Model in Computational Mobile Grid

Computation in the mobile grid nodes under the cellular network environment requires an efficient management of wireless channels along with the user mobility. Due to random movement of the mobile devices, the load over the cells in terms of initiation of new computation or carryover computation (handoff) may vary dynamically. This may result in non-availability of free channels for Inter-task communication leading in the drop of carryover computation or to initiate the new computation in the current cell. The proposed work designs a model by instigating substantive cooperation among underutilized and the overloaded cells, considering importance to the frequency reuse and assigning priority to the on-going computation in the computational mobile grid. The model seeks cooperation by grouping the cells in different sizes to reduce the blocking and dropping of the computation. Blocking of the communication is very serious in computational mobile grid environment as the drop may result in the termination of the computation. The model aims at minimizing the Call Block Probability (CBP) and Call Drop Probability (CDP) in the mobile grid by making the clusters of different sizes. A simulation experiment to evaluate the performance of the proposed model reveals the effectiveness of this model.

Performance analysis of multicast routing and wavelength assignment protocol with dynamic traffic grooming in WDM networks

The need for on-demand provisioning of wavelength-routed channels with service-differentiated offerings within the transport layer has become more essential because of the recent emergence of high bit rate Internet protocol IP network applications. Diverse optical transport network architectures have been proposed to achieve the above requirements. This approach is determined by fundamental advances in wavelength division multiplexing WDM technologies. Because of the availability of ultra long-reach transport and all-optical switching, the deployment of all-optical networks has been made possible. The concurrent transmission of multiple streams of data with the assistance of special properties of fiber optics is called WDM. The WDM network provides the capability of transferring huge amounts of data at high speeds by the users over large distances. There are several network applications that require the support of QoS multicast, such as multimedia conferencing systems, video-on-demand systems, real-time control systems, etc. In a WDM network, the route decision and wavelength assignment of lightpath connections are based mainly on the routing and wavelength assignment RWA. The multicast RWA's task is to maximize the number of multicast groups admitted or minimize the call-blocking probability. The dynamic traffic-grooming problem in wavelength-routed networks is generally a two-layered routing problem in which traffic connections are routed over lightpaths in the virtual topology layer and lightpaths are routed over physical links in the physical topology layer. In this paper, a multicast RWA protocol for capacity improvement in WDM networks is designed. In the wavelength assignment technique, paths from the source node to each of the destination nodes and the potential paths are divided into fragments by the junction nodes and these junction nodes have the wavelength conversion capability. By using the concept of fragmentation and grouping, the proposed scheme can be generally applied for the wavelength assignment of multicast in WDM networks. An optimized dynamic traffic grooming algorithm is also developed to address the traffic grooming problem in mesh networks in the multicast scenario for maximizing the resource utilization and minimizing the blocking probability. Copyright © 2011 John Wiley & Sons, Ltd.

Provide a Model for Handover Technology in Wireless Networks

Fast Handovers for the MIPv6 (FMIPv6) has been proposed to reduce the Handover latency, in the IETF. It could not find the acceptable reduction, so led to more efforts to improve it and however the creation of multiple Handover methods in the literature. A stable connection is very important in mobile services so the mobility of device would not cause any interruption in network services and thus mobility management plays a very important role. Mobile IPv6 has become a general solution for supporting mobility between different networks on the internet which a flawless connection needs to be managed properly. In order to select the appropriate method, in this paper, all the proposed methods have been classified according to the identified performance metrics. Call blocking probability, Handover blocking probability, Probability of an unnecessary handover, Duration of interruption and delay, as the most important Handover algorithm performance metrics are introduced. The AHP method will be deployed to weight the metrics in a sample topology according to the selected sound application. Then the TOPSIS method will be employed to find the appropriate Handover algorithm.

Minimization of Call Blocking Probability using Auxiliary Stations

Minimization of Call Blocking Probability using Auxiliary Stations

The extended connection‐dependent threshold model for call‐level performance analysis of multi‐rate loss systems under the bandwidth reservation policy

SUMMARYFirstly, we reviewed two extensions of the Erlang multi‐rate loss model, whereby we can assess the call‐level QoS of telecom networks supporting elastic traffic: (i) the extended Erlang multi‐rate loss model, where random arriving calls of certain bandwidth requirements at call setup can tolerate bandwidth compression while in service; and (ii) the connection‐dependent threshold model, where arriving calls may have several contingency bandwidth requirements, whereas in‐service calls cannot tolerate bandwidth compression. Secondly, we proposed a new model, the extended connection‐dependent threshold model. Calls may have alternative bandwidth requirements at call setup and can tolerate bandwidth compression while in service. We proposed a recurrent formula for the efficient calculation of link occupancy distribution and consequently call blocking probabilities, link utilization, and throughput per service class. Furthermore, in the proposed model, we incorporated the bandwidth reservation policy, whereby we can (i) equalize the call blocking probabilities of different service classes, (ii) guarantee specific QoS per service class, and (iii) implement different maximum bandwidth compression/expansion rate per service class so that the network supports both elastic and stream traffic. The accuracy of the new model is verified by simulation. Moreover, the proposed model performs better than the existing models. Finally, we generalize the proposed model by incorporating service classes with either random or quasi‐random arrivals. Copyright © 2011 John Wiley & Sons, Ltd.

Generalized Queueing Model for Call Blocking Probability and Resource Utilization in OFDM Wireless Networks

Chen and Chen have dealt with a queueing model for obtaining some performance measures of OFDM wireless systems. Recently, Pla et al. have proposed the multi-class Erlang loss model as a more adequate one. However, the above two models considered only subcarriers as system resources, even though power is also another limited resource of OFDM systems. This letter proposes a generalized queueing model incorporating two kinds of resources, power and subcarriers.