Switching Center Research Articles

An efficient metric-based (EM-B) location management scheme for wireless cellular networks

In the current era, the wireless cellular network is gaining much attention in the network mobility for qualitative service. Towards enhancing the QoS and narrowing the dilemma of network management (location management) an efficient metric-based location management technique is introduced in this paper to capture the current location of mobile subscribers. The attributes of this technique are based on metrics calculation and location management message routing path determination. First, the current mobile switching center will calculate the shortest metric-based path between current and master (previous) location of mobile terminals (user), thereafter it performs the location management procedure through the optimal suggested path by the mobile switching center. This proposed technique will reduce the signaling cost, registration delay, call setup delay, network overheads and total location management cost. The proposed analytical model checks the scalability and effectiveness of proposed system over certain attributes and a comparison is made with the existing available techniques.

Building better backhaul

Cellular networks have always relied on connections between each basestation and a mobile telephone exchange or switching centre (MtX/MsC) to 'backhaul' phonecalls and mobile data to the rest of the network. Backhaul has for years been taken for granted by all but a relatively small group of technicians and engineers who manage, maintain, and develop the time-divisionmultiplexing (TDM) systems that provide this vital connectivity.

Tree network design avoiding congestion

We introduce in this paper an optimal method for tree network design avoiding congestion. We see this problem arising in telecommunication and transportation networks as a flow extension of the Steiner problem in directed graphs, thus including as a particular case any alternative approach based on the minimum spanning tree problem. Our multi-commodity formulation is able to cope with the design of centralized computer networks, modern multi-cast multi-party or hub-based transportation trees. The objective in such cases is the minimization of the sum of the fixed (structural) and variable (operational) costs of all the arcs composing an arborescence that links the origin node (switching center, server, station) to every demand node (multi-cast participants, users in general). The non-linear multi-commodity flow model is solved by a generalized Benders decomposition approach.

라그랑지안 기반의 휴리스틱 기법을 이용한 셀룰러 모바일 네트워크의 설계

Cellular network is comprised of several base stations which serve cellular shaped service area and each base station (BS) is connected to the mobile switching center (MSC). In this paper, the configuration modeling and algorithm of a cellular mobile network with the aim of minimizing the overall cost of operation (handover) and network installation cost (cabling cost and installing cost of mobile switching center) are considered. Handover and cabling cost is one of the key considerations in designing cellular telecommunication networks. For real-world applications, this configuration study covers in an integrated framework for two major decisions: locating MSC and assigning BS to MSC. The problem is expressed in an integer programming model and a heuristic algorithm based on Lagrangian relaxation is proposed to resolve the problem. Searching for the optimum solution through exact algorithm to this problem appears to be unrealistic considering the large scale nature and NP-Completeness of the problem. The suggested algorithm computes both the bound for the objective value of the problem and the feasible solution for the problem. A Lagrangian heuristics is developed to find the feasible solution. Numerical tests are performed for the effectiveness and efficiency of the proposed heuristic algorithm. Computational experiments show that the performance of the proposed heuristics is satisfactory in the quality of the generated solution.

Optimal Mobile Switching Center Positioning and Cells Assignment Using Lagrangian Heuristic

This paper deals with the configuration of a wireless network with the aim of minimizing the overall cost of both operation and network installation. The trade-off between the operation cost and the installation cost is the key consideration when designing cellular telecommunication networks, and can save costs and improve the performance of the network. In this paper, we propose an integrated framework for selecting Mobile Switching Center (MSC) among the candidate MSCs and assigning Base Stations (BSs) to the selected MSCs with the objective function of minimizing the cost of MSC setup, BS to MSC cabling, as well as the cost of handover. Capacity constraint for the selected MSC is also considered in the problem. The problem is expressed in an integer programming model and the Lagrangian relaxation method is proposed to solve the problem by dualizing some constraints. The Lagrangian relaxed problem is decomposed into subproblems that can be resolved optimally. The Lagrangian heuristic algorithm is suggested to find feasible solutions to the original problem. Computational experiments are performed to test the effectiveness and efficiency of the proposed heuristic algorithm. In the experiments, Lagrangian bounds on the optimal solution are used to show the effectiveness of the algorithm. The results of the proposed algorithm are also compared with those of some conventional meta-heuristics, Tabu search (TS) and Genetic algorithm (GA). The computational experiments show that the performance of the proposed heuristics is satisfactory in both the speed and the quality of the solution generated.

Security Aspects in Mobile Ad Hoc Network (MANETs): Technical Review

Mobile Ad hoc networks (MANETs) are a new paradigm of wireless network, offering unrestricted mobility without any underlying infrastructure such as base station or mobile switching centers. Basically ad hoc network is a collection of nodes communicating with each other by forming a multi-hop network. In a mobile ad hoc network, it is much more vulnerable to attacks than a wired network due to its limited physical security, dynamically changing network topology, energy constrained operations and lack of centralized administration. Since all the nodes in the network collaborate to forward the data, the wireless channel is prone to active and passive attacks by malicious nodes, such as Denial of Service (DoS), eavesdropping, spoofing, etc. The intent of this paper is to investigate the security goal, security challenges and different types of active and passive attacks on MANETs.

Mechanism of Regulation of Native Cardiac Muscle Thin Filaments by Rigor Cardiac Myosin-S1 and Calcium

We have studied the mechanism of activation of native cardiac thin filaments by calcium and rigor myosin. The acceleration of the rate of 2'-deoxy-3'-O-(N-methylanthraniloyl)ADP (mdADP) dissociation from cardiac myosin-S1-mdADP-P(i) and cardiac myosin-S1-mdADP by native cardiac muscle thin filaments was measured using double mixing stopped-flow fluorescence. Relative to inhibited thin filaments (no bound calcium or rigor S1), fully activated thin filaments (with both calcium and rigor-S1 bound) increase the rate of product dissociation from the physiologically important pre-power stroke myosin-mdADP-P(i) by a factor of ∼75. This can be compared with only an ∼6-fold increase in the rate of nucleotide diphosphate dissociation from nonphysiological myosin-mdADP by the fully activated thin filaments relative to the fully inhibited thin filaments. These results show that physiological levels of regulation are not only dependent on the state of the thin filament but also on the conformation of the myosin. Less than 2-fold regulation is due to a change in affinity of myosin-ADP-P(i) for thin filaments such as would be expected by a simple "steric blocking" of the myosin-binding site of the thin filament by tropomyosin. Although maximal activation requires both calcium and rigor myosin-S1 bound to the cardiac filament, association with a single ligand produces ∼70% maximal activation. This can be contrasted with skeletal thin filaments in which calcium alone only activated the rate of product dissociation ∼20% of maximum, and rigor myosin produces ∼30% maximal activation.

Multi home agent and pointer-based (MHA–PB) location management scheme in integrated cellular-WLAN networks for frequent moving users

In this paper, we introduces a multi home agent and pointer-based location management scheme. Multi home agent preserves the location information for different wireless technologies (Universal Mobile Telecommunication system, Wireless Local Area Networks) and maintains a cache for the location information of mobile host. In addition, an index based call delivery system has been proposed. The performance comparisons and numerical analysis are helpful to find out the efficiency and effectiveness of the proposed system, with respect to existing location management techniques (single registration scheme, and dual home agent scheme). It has been observed that the registration cost, call setup delay, registration delay and overhead at mobile switching center are reduces in the proposed MHA–PB scheme.

Practical Implications for Backhaul: A View into the National Broadband Plan [MicroBusiness

The Federal Communications Commission (FCC) announced an aggressive agenda for implementing key aspects of the nation's first-ever National Broadband Plan (NBP). The NBP focuses in multiple places on backhaul, which is the transport of voice, video, and data traffic from a wireless carrier's or public safety network's base station (or cell site) to its mobile switching center (MSC). Backhaul appears in the NBP in both direct and nuanced ways.

High-Capacitance-Ratio Warped-Beam Capacitive MEMS Switch Designs

This paper presents a detailed analysis of the design, fabrication, and testing of a high-isolation electrostatically actuated capacitive shunt switch for X-band applications. The dual-warped-beam switch's RF performance is fine-tuned simultaneously in the off and on states by introducing warped bimetallic beams to the switch's edge to increase the effective capacitive area in the downstate and to the switch's center to decrease the effective capacitive area in the upstate. As a result, the dual-warped-beam switches demonstrate an off-to-on capacitive ratio of up to 170 without the need for thin dielectrics or high dielectric constant materials, exhibiting excellent RF performance. High isolation at X-band of less than 40 dB is also obtained with the introduction of inductive meandered springs into the switch structure. This novel tuning design mechanism for capacitive switches utilizing warped bimetallic beams has the advantage of simplicity and flexibility without the added complexity of using thinner dielectrics, tuned circuits, or larger size.

MicroRNA in the Adaptive Immune System, in Sickness and in Health

MicroRNA are emerging as key regulators of the development and function of adaptive immunity. These 19-24 nucleotide regulatory RNA molecules have essential roles in multiple faucets of adaptive immunity, from regulating the development of the key cellular players to the activation and function in immune responses. MicroRNA are involved in T cell and B cell differentiation in the thymus and bone marrow, and subsequent peripheral homeostasis. The contribution of specific microRNA to the adaptive immune response becomes even more apparent during the effector phases: class switching and germinal centre formation in B cells, differentiation into functional lineages in T cells, and activation of antigen-presentation cells through pattern-recognition pathways. With the capacity of microRNA to alter the survival and death of T and B cells, control over microRNA expression is essential to prevent adaptive immune cells from unregulated proliferation. MicroRNA can act both as 'oncomirs' and tumour suppressors, and thus dysregulation of microRNA in lymphocytes can cause malignancies. In this review, we will describe the role of microRNA in generating a productive adaptive response, and the consequences if microRNA-mediated repression of lymphocytes is perturbed.

The role of CD154 in haematopoietic development

CD154 (CD40 ligand, CD40L, gp139) is a co-stimulatory molecule of the tumour necrosis factor (TNF) family. CD154 was originally discovered on T-cells, and was found to be involved in many immune responses including B-cell activation, isotype switching, and germinal centre formation. The expression of CD154 on other haematopoietic and non-haematopoietic cells suggests that CD154 has other functions as well. Indeed, CD154 is involved in many pathological processes, including inflammatory and autoimmune diseases. Genetic studies in patients and mice taught us that CD154 might affect haematopoietic stem and progenitor cells (HSPCs), T-cell, B-cell, and dendritic cell (DC) progenitors. Moreover, the development of specific T-cell and DC subsets critically depends on CD154. Furthermore, CD154 is involved in lymphoid malignancies. Here we highlight the role of CD154 in the developing lymphoid system, including the biology of HSPC and lineage-committed T-cell, B-cell, NK, and DC progenitors. Further, the clinical and therapeutic implications of CD154 interactions in lymphopoiesis will be discussed.

Design collaborative systems with multiple AF-relays for asynchronous frequency-selective fading channels

Distributed systems with multiple amplify-andforward (AF) relays are very appealing, due to their ease of implementing space diversity. Although their performance on synchronous flat-fading channels was well understood, the corresponding design and optimization in asynchronous frequency selective fading (AFSF) channels remains unsolved. In this paper, we tackle the problem in the information-theoretic framework, revealing that multi-relay amplify-and-forward (MR-AF) systems over AFSF channels can be better understood through the concept of virtual sub-channels. Each relay node virtually performs two functions, appropriately amplifying sub-channel signals on one hand and serving as a local switching center on the other. System design, therefore, reduces to the determination of optimal amplification factors, switching matrices, and power allocation among the source, relays and relevant sub-channels. The optimization is implemented in a layered structure. The effects of asynchronism and knowledge of channel information on mutual information are also investigated.

LOCATING THE MEDIAN OF A TREE IN REAL TIME

Determining the optimal location of a switching center in a tree network of users is accurately modeled by the median problem. A real-time approach is used in this paper to investigate the dynamics of such a communication network in two cases: (1) a growing tree of nodes associated with equal demand rates, and (2) a stream of corrections that arbitrarily change the demand rates at the nodes. The worst-case analysis performed in both situations clearly demonstrates the importance of parallelism in such real-time paradigms. It is shown that the error generated by the best sequential algorithm in the first case can be arbitrarily large. A synergistic behavior is revealed when the quality-up is investigated in the second case.

Particle swarm optimization for mobile network design

In mobile network design, the challenge is to efficiently determine the locations of base control stations (BSCs), mobile switching centers (MSCs), and their connecting links for given locations of base transceiver stations (BTSs) so that a predefined objective function is satisfied. In this paper, a particle swarm optimization- (PSO-) based optimization engine is used to effectively lay out the network components and their interconnections such that the overall deployment cost is kept as low as possible. The performance of the PSO-based engine is then compared with a genetic algorithm- (GA-) based one. The simulation results show that the PSO-based optimization engine is able to successfully optimize the network deployment cost and significantly outperforms the GA-based optimization engine.

Topical Application of Cream-emulsified CD86 siRNA Ameliorates Allergic Skin Disease by Targeting Cutaneous Dendritic Cells

Induction of the co-stimulatory molecule CD86 on dendritic cells (DCs) in the peripheral tissues is a critical event in triggering antigen-specific immune responses. In this study, we propose a new small interfering RNA (siRNA)-based therapy using cream-emulsified CD86 siRNA, targeting DCs for murine contact hypersensitivity (CH) and atopic dermatitis (AD)-like disease. Topical application of CD86 siRNA efficiently inhibited CH and markedly decreased the numbers of infiltrating CD86(+) or major histocompatibility complex (MHC) class II(+) cells in murine ear skin. The total number of cells, the percentage of hapten-carrying DCs, and their CD86 expression in the regional lymph nodes (RLNs) also significantly decreased. These results suggest that the silencing of CD86 in local DCs inhibits the recruitment and migration of DCs into the skin and RLNs, respectively, resulting in reduced antigen-specific local inflammation. The therapeutic efficacy of the CD86 siRNA was confirmed in AD-prone NC/Nga mice. Treatment produced marked amelioration in the clinical manifestations of AD and reduced the antigen-specific production of interleukin-4 (IL-4) and serum immunoglobulin E (IgE) and IgG1. Our results suggest that the targeting of cutaneous DCs by CD86 siRNA may be a promising strategy in the treatment of allergic skin disease.

An Intelligent Paging Strategy Using Rule-Based AI Technique for Locating Mobile Terminals in Cellular Wireless Networks

This paper proposes an efficient rule-based paging strategy (RBPS) using a well-known concept of artificial intelligence, namely, rule base. The novelty of the scheme lies in devising ldquorulesrdquo that offer a potential mapping from seemingly disparate input data items (yet having some statistical relations) to an almost exact position of mobile terminals (MTs). Considering the conventional models of call arrival, cell residence, and mobility, we have developed a stochastic model to analyze the performance of the scheme. Interestingly, RBPS requires no additional processing at MTs and involves a nominal overhead at mobile switching centers. Simulation results reveal that RBPS significantly outperforms the blanket paging scheme adopted in global system for mobile (GSM) communications. In addition, results are very much encouraging when compared with the popular shortest-distance-first scheme. Finally, RBPS is generic enough to be potentially used in next-generation wireless networks, irrespective of any standards, with only minor adaptations to conform to the respective standards.

A tabu search algorithm for the global planning problem of third generation mobile networks

In this paper, we propose a tabu search (TS) algorithm for the global planning problem of third generation (3G) universal mobile telecommunications system (UMTS) networks. This problem is composed of three NP-hard subproblems: the cell, the access network and the core network planning subproblems. Therefore, the global planning problem consists in selecting the number, the location and the type of network nodes (including the base stations, the radio network controllers, the mobile switching centers and the serving GPRS (General Packet Radio Service) support nodes) as well as the interconnections between them. After describing our metaheuristic, a systematic set of experiments is designed to assess its performance. The results show that quasi-optimal solutions can be obtained with the proposed approach.

Fuzzy logic based neural network models for load balancing in wireless networks

In this paper, adaptive channel borrowing approach fuzzy neural networks for load balancing (ACB-FNN) is presented to maximized the number of served calls and the depending on asymmetries traffic load problem. In a wireless network, the call's arrival rate, the call duration and the communication overhead between the base station and the mobile switch center are vague and uncertain. A new load balancing algorithm with cell involved negotiation is also presented in this paper. The ACB-FNN exhibits better learning abilities, optimization abilities, robustness, and fault-tolerant capability thus yielding better performance compared with other algorithms. It aims to efficiently satisfy their diverse quality-of-service (QoS) requirements. The results show that our algorithm has lower blocking rate, lower dropping rate, less update overhead, and shorter channel acquisition delay than previous methods.

Combined Guard Channel and Mobile-Assisted Handoff for Cellular Networks

For cellular communication systems, mobility and limited radio coverage of a cell require calls to be handed over from one base station system (BSS) to another. Due to the limited bandwidth available in various cells, there is a finite probability that an ongoing call, while being handed off, may get dropped. Minimizing the dropping of ongoing calls during handoff is an important design criterion. Some digital cellular systems, e.g., the global system for mobile communications and the IS-136, use mobile-assisted handoff (MAHO), in which a mobile terminal (MT) assists its BSS, and a mobile switching center in making handoff decisions. MAHO requires an MT to regularly report, back to its serving BSS, its current radio-link state [defined in terms of the received signal strength indicator (RSSI) and the bit error rate (BER)] of transmissions received from neighboring BSSs. Some researchers have suggested that a base station needs to give priority to the handoff calls over the new calls. This requires each cell to reserve a number of guard channels (GCs) to be used exclusively for processing of the handoff calls. Since MAHO makes handoff decisions based solely on RSSI/BER measurements, there is a finite probability that some handoff calls may get dropped due to the nonavailability of free channels in the neighboring cell to which the call is being handed off. Conversely, if a handoff decision is based solely on the availability of a free channel, without regard to the signal quality, it may result in some of the handed-off calls being dropped due to poor signal quality. In this paper, we propose a new handoff technique by combining the MAHO and GC techniques. In the proposed technique, the MT reports back not only the RSSI and the BER but the number of free channels that are available for the handoff traffic as well. This will ensure that a handed-off call has acceptable signal quality as well as a free available channel. The performance of this handoff technique is analyzed using an analytical model whose solution gives the desired performance measures in terms of blocking and dropping probabilities.