FAULT-TOLERANT DISTRIBUTED CHANNEL ALLOCATION ALGORITHMS FOR CELLULAR NETWORKS

In cellular networks, channels should be allocated efficiently to support communication betweenmobile hosts. In addition, in cellular networks, base stations may fail. Therefore, designing a faulttolerantchannel allocation algorithm is important. That is, the algorithm should tolerate failuresof base stations. Many existing algorithms are neither fault-tolerant nor efficient in allocatingchannels.We propose channel allocation algorithms which are both fault-tolerant and efficient. In theproposed algorithms, to borrow a channel, a base station (or a cell) does not need to get channelusage information from all its interference neighbors. This makes the algorithms fault-tolerant,i.e., the algorithms can tolerate base station failures, and perform well in the presence of thesefailures.Channel pre-allocation has effect on the performance of a channel allocation algorithm. Thiseffect has not been studied quantitatively. We propose an adaptive channel allocation algorithmto study this effect. The algorithm allows a subset of channels to be pre-allocated to cells. Performanceevaluation indicates that a channel allocation algorithm benefits from pre-allocating allchannels to cells.Channel selection strategy also inuences the performance of a channel allocation algorithm.Given a set of channels to borrow, how a cell chooses a channel to borrow is called the channelselection problem. When choosing a channel to borrow, many algorithms proposed in the literaturedo not take into account the interference caused by borrowing the channel to the cells which havethe channel allocated to them. However, such interference should be considered; reducing suchinterference helps increase the reuse of the same channel, and hence improving channel utilization.We propose a channel selection algorithm taking such interference into account.Most channel allocation algorithms proposed in the literature are for traditional cellular networkswith static base stations and the neighborhood relationship among the base stations is fixed.Such algorithms are not applicable for cellular networks with mobile base stations. We proposea channel allocation algorithm for cellular networks with mobile base stations. The proposedalgorithm is both fault-tolerant and reuses channels efficiently.KEYWORDS: distributed channel allocation, resource planning, fault-tolerance, cellular networks,3-cell cluster model

FAULT TOLERANT SYSTEM FOR CELLULAR NETWORK

In cellular communication networks, the geographical area is divided into smaller regions, called cells. In each cell, there is one Mobile Service Station (MSS) as well as a number of Mobile Hosts (MH). The communication between MSSs is, in general, through wired links, while the links between an MH and MSS is wireless. A Mobile Host can communicate with other Mobile Hosts in the system only through the Mobile Service Station in its cell. This kind of architecture is shown in Fig. 1. There are two kinds of channels available to an MH: communication channel and control channel. The former is used to support communication between an MH and the MSS in its cell, while the latter is set aside to be used exclusively to send control messages that are generated by the channel allocation algorithm

A Novel Load Balancing Scheme for Hot-spot Cells

The radio spectrum that is available to us is very limited. The cellular network works fine when the traffic conditions are normal or below normal. But when the cellular traffic increases the network cannot perform efficiently under this increasing traffic load as the radio spectrum to serve this increasing traffic is very limited. To avoid degradation and to increase performance of wireless cellular network frequency reuse and channel allocation techniques are used. The sole purpose of the channel allocation techniques is to allocate the available channel in such a way that the call blocking probability is reduced. In this paper we propose a HCA technique which will reduce the call blocking probability when the Cell becomes a hot spot i.e. the cellular traffic is beyond normal. These papers propose a novel load balancing scheme that will allocate channel to the overburden cell using hot spot notification. The HCA scheme is a combination of FCA and DCA scheme which effectively utilize the central pool for allocation of channels to the cells under heavy traffic. This HCA Scheme work like FCA in initial stages i.e. under low traffic levels and more like DCA at later stages i.e. high traffic levels and also reduces the Call blocking probability to great extent

A Novel Adaptive Channel Allocation Scheme to Handle Handoffs

Wireless networking is becoming an increasingly important and popular way of providing global information access to users on the move. One of the main challenges for seamless mobility is the availability of simple and robust handoff algorithms, which allow a mobile node to roam among heterogeneous wireless networks. In this paper, the authors devise a scheme, A Novel Adaptive Channel Allocation Scheme (ACAS) where the number of guard channel(s) is adjusted automatically based on the average handoff blocking rate measured in the past certain period of time. The handoff blocking rate is controlled under the designated threshold and the new call blocking rate is minimized. The performance evaluation of the ACAS is done through simulation of nodes. The result shows that the ACAS scheme outperforms the Static Channel Allocation Scheme by controlling a hard constraint on the handoff rejection probability. The proposed scheme achieves the optimal performance by maximizing the resource utilization and adapts itself to changing traffic conditions automatically.Comment: 9 Pages; in International Journal of Distributed and Parallel system

Efficient Utilization of Channels Using Dynamic Guard Channel Allocation with Channel Borrowing Strategy in Handoffs

User mobility in wireless data networks is increasing because of technological advances and the desire for voice and multimedia applications. These applications, however, require fast handoffs between base stations to maintain the quality of the connections. In this paper, the authors describe the use of novel and efficient data structure which dynamically allocates guard channel for handoffs and introduces the concept of channel borrowing strategy. The proposed scheme allocates the guard channels for handoff requests dynamically, based on the traffic load for certain time period. A new originating call in the cell coverage area also uses these guard channels if they are unused. Our basic idea is to allow Guard channels to be shared between new calls and handoff calls. This approach maximizes the channel utilization. The simulation results prove that the channel borrowing scheme improves the overall throughput.Comment: International Conference CCSEA 2012 at New Delhi May 27. arXiv admin note: substantial text overlap with arXiv:1206.306

Mobile cloud computing and network function virtualization for 5g systems

The recent growth of the number of smart mobile devices and the emergence of complex multimedia mobile applications have brought new challenges to the design of wireless mobile networks. The envisioned Fifth-Generation (5G) systems are equipped with different technical solutions that can accommodate the increasing demands for high date rate, latency-limited, energy-efficient and reliable mobile communication networks. Mobile Cloud Computing (MCC) is a key technology in 5G systems that enables the offloading of computationally heavy applications, such as for augmented or virtual reality, object recognition, or gaming from mobile devices to cloudlet or cloud servers, which are connected to wireless access points, either directly or through finite-capacity backhaul links. Given the battery-limited nature of mobile devices, mobile cloud computing is deemed to be an important enabler for the provision of such advanced applications. However, computational tasks offloading, and due to the variability of the communication network through which the cloud or cloudlet is accessed, may incur unpredictable energy expenditure or intolerable delay for the communications between mobile devices and the cloud or cloudlet servers. Therefore, the design of a mobile cloud computing system is investigated by jointly optimizing the allocation of radio, computational resources and backhaul resources in both uplink and downlink directions. Moreover, the users selected for cloud offloading need to have an energy consumption that is smaller than the amount required for local computing, which is achieved by means of user scheduling. Motivated by the application-centric drift of 5G systems and the advances in smart devices manufacturing technologies, new brand of mobile applications are developed that are immersive, ubiquitous and highly-collaborative in nature. For example, Augmented Reality (AR) mobile applications have inherent collaborative properties in terms of data collection in the uplink, computing at the cloud, and data delivery in the downlink. Therefore, the optimization of the shared computing and communication resources in MCC not only benefit from the joint allocation of both resources, but also can be more efficiently enhanced by sharing the offloaded data and computations among multiple users. As a result, a resource allocation approach whereby transmitted, received and processed data are shared partially among the users leads to more efficient utilization of the communication and computational resources. As a suggested architecture in 5G systems, MCC decouples the computing functionality from the platform location through the use of software virtualization to allow flexible provisioning of the provided services. Another virtualization-based technology in 5G systems is Network Function Virtualization (NFV) which prescribes the instantiation of network functions on general-purpose network devices, such as servers and switches. While yielding a more flexible and cost-effective network architecture, NFV is potentially limited by the fact that commercial off-the-shelf hardware is less reliable than the dedicated network elements used in conventional cellular deployments. The typical solution for this problem is to duplicate network functions across geographically distributed hardware in order to ensure diversity. For that reason, the development of fault-tolerant virtualization strategies for MCC and NFV is necessary to ensure reliability of the provided services

Resource optimization, spectrum allocation and fault tolerance planning in broadband wireless networks

In current (4G) and future (5G) broadband cellular networks, new cell coverage planning ideas, network architectures proposals, novel physical resources allocation optimization techniques, and dynamic spectrum allocation optimization frame works provide good opportunities for mobile service providers (MSPs) to improve their return on investments (ROI), and for mobile equipments manufacturers to increase their profit and market share. Despite the attractive opportunities that network architecture, cell planning and resources allocation optimization offers, there are many challenges and difficulties that are facing MSPs when planning and operating networks to cope with the tremendous increase in mobile applications and to satisfy different users requirements. Physical resources allocation, spectrum allocation optimization, network architecture enhancement, and fault tolerance cell planning are major issues in broadband cellular networks. The work accomplished in this thesis aims at enhancing the network performance by optimizing the planning and operations of the network. Different optimization techniques are used throughout this thesis to help increase the spectral and energy efficiency in 4G and 5G networks. The objectives of this study are four objectives, first to propose a physical resources allocation utility based frame work using a novel utility function that can jointly optimize the maximum normalized spectral efficiency (NSE) and power consumed locally in each cell in order to increase the mobile service providers ROI. The ROI is enhanced by increasing the profits through maximizing the network spectral efficiency and decreasing the operational costs by minimizing the power consumption in the network. The second objective is to determine the optimal down-link frequency partition configuration that can efficiently allocate the spectrum resources to different network frequency partitions in order to globally achieve the same joint optimization objective by addressing the DFPCs dynamic behavior according to the network topology, load conditions, and users distribution. The third objective is to propose a new network architecture that consists of a data collection system that aid as a traffic data repository and a decision support system (DSS) introduced as a new self optimization module within the self organized networks (SON) framework to automate the optimization of the dynamic spectrum allocation. The last objective is to perform a network planning that aims at placing the optimal number of relay stations that aid in achieving network full coverage and minimum rate requirements with a fault tolerance functionality to avoid network failures and using the self organized frame work to perform the self healing by managing the backup solutions needed in response to the network failures. In order to achieve the previously mentioned objectives a detailed study to the state of the art in network planning using relay stations, physical resource allocation, dynamic spectrum allocation, network architecture and SON frame work is conducted. Different methodologies such as integer linear programming, stochastic programming and non-parametric estimation analysis are presented to propose a novel physical resources and dynamic spectrum allocation schemes. A plan-do-control-act model is also proposed within the DSS in the new suggested network architecture for continuous improvement of spectrum allocation. A non-linear to linear formulation conversion using an expanded space state is utilized to perform an in-band fault tolerance network planning that consider network interference between relay stations and base stations and avoid network failures. Simulations and results are conducted to validate the proposed methodologies and to compare it against state of the art work