Dynamic Channel Allocation Technique Research Articles

A modified energy detection based dynamic spectrum sharing technique and its real time implementation on wireless platform for cognitive radio networks

Cognitive radio offers a flexible and efficient utilization of radio frequency resources by dynamic spectrum sharing as required in next gen (5G) architecture of wireless communication. The channel allocation time, probability of false alarm detection and spectral efficiency are the major performance parameters to characterize a spectrum sharing technique. This paper presents modified energy detection based dynamic channel allocation technique based on sensing the power spectral density of idle spectrum bands i.e. spectrum hole. Receiver operating characteristics (ROC) curves have been used to analyze the detector performance of sensing with respect to probability false alarm at different values of SNR. Allocation of unoccupied bands to the SUs has been done by coalition based cooperative game, which provides SUs with an incentive to cooperate. Based on their worth, SUs get payoffs which have been computed using Shapely values as a one-point solution. Vickrey–Clarke–Groves (VCG) auction mechanism has been used to allocate the spectrum resources fairly to each user. On the basis of allocation time, the present model for dynamic spectrum access appears to be more efficient as compared to the conventional opportunistic spectrum access model.

Channel Allocation with Sub-Optimal Power Control in WiMAX Networks Using Fuzzy Inference System

Abstract Power allocation and energy consumption of mobile subscriber stations are very important issues for the WiMAX (IEEE 802.16) networks. This paper proposes a dynamic channel allocation technique for efficient power management in multi-channel IEEE 802.16 networks (WiMAX). In our scheme, each Subscriber Station (SS) has one transceiver and can be tuned between multiple channels, intending to eliminate the secondary interference. The Base Station (BS) identifies the data rate required by a SS for proper communication and allocates a channel with specific bandwidth with sub-optimal transmission power to suite the data rate requirement. The estimated power requirement and interference levels are fuzzified to identify the feasible solutions. Matlab Simulations demonstrate the effectiveness of the proposed method in terms of Channel Acquisition Delay, Average Transmitter Power and Packet Delivery ratio.

Dynamic Channel Allocation Technique for Distributed Multi-radio Multichannel Multi-path Routing Protocol in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) have gained main attraction in providing flexible network services and support to the end users. There are many efforts seen to design robust routing protocol for WMNs and solutions are proposed to standardized channel allocation techniques. There are various approaches dedicated to maximize the network though put and minimize network interface. Existing multi radio multi channel routing protocols utilize only single channel situation and static channel allocation degrades the performance of the WMNs. The challenge is to allocate channel without link interference and to improve end-to-end throughput efficiency in multipath routing for WMNs. In this paper, we propose a dynamic channel allocation technique is proposed for multi path routing protocol for WMNs. Dynamic channel allocation is used to avoid the inter-flow and intra-flow channel competition and interference. The protocol establishes and maintains multiple channel dimensional disjoint points changing frequently and each data flow is separated into multiple paths. NS2 simulations are carried out for the evaluation of the performance of the proposed channel allocation technique and compared with popular routing protocols of Mesh Networks Ad hoc On Demand Distance Vector Routing Protocol (AODV) and Hybrid Wireless Mesh Protocol (HWMP). The simulation results show that proposed dynamic channel allocation technique achieve better adaptability with less overhead and interference. The multipath routing show increase end-to-end throughput significantly.

Token based distributed dynamic channel allocation in wireless communication network

Channel allocation in wireless communication network plays a crucial role in the performance of the network. Fixed scheme for channel allocation does not account for any non-uniform traffic in the network. Dynamic scheme, on the other hand, ensures that whenever a cell requires a channel, it is allocated pertaining to the frequency reuse constraints. The fact that distributed dynamic channel allocation technique has recently gained popularity is due to its high reliability and scalability. In this paper we propose a token based mutual exclusion technique to solve the problem of distributed dynamic channel allocation. We will show through simulation, how message exchange between cells is reduced in token based relaxed mutual exclusion as opposed to other relaxed mutual exclusion techniques.

Software Agent Structure for Performance Index Improvement of Cellular Network

Efficient reuse of limited radio spectrum is vital issue to support increasing number of mobile terminals and heterogeneous traffic scenarios. Dynamic channel allocation (DCA) technique is suitable to solve the problem. The drawback of dynamic channel allocation is it may upgrade performance of one cluster and degrade performance of other cluster in large scale cellular network. To balance performance of clusters and increase carried traffic in network, there is need of enhancement of DCA techniques. To introduce improvement in the dynamic channel approach, the paper suggested Multi Agent System (MAS) of physical agents ported at base stations working on the principle of cooperative negotiation to improve the QoS of the network. We formulated an integrated framework which includes fundamental mechanism of call admission control and resource management using hybrid channel allocation (HCA). To balance performance index of various clusters of network, agent negotiation is executed. Our simulation results show that it is possible to significantly enhance performance index of network due to MAS-HCA approach when compared with ES based and ILP based HCA schemes proposed in literature.

Dynamic resource allocation scheme under traffic condition in satellite systems

As the traffic distribution in China mainland is far from uniform, a new traffic model in China mainland is presented on the basis of per-capita Gross Domestic Product (GDP) and density of population. Based on this characteristic traffic model, a new Traffic Dependent Dynamic Channel Allocation and Reservation (TDDCAR) technique is proposed, the simulation model is built, and the strategies’ performance is evaluated through computer simulation. The simulation results show that, compared to the conventional Fixed Channel Allocation (FCA), TDDCAR estimates the traffic conditions in every spot beam and frequently adjusts the traffic according to current traffic conditions. It has achieved a significant improvement in new call blocking probability, handover blocking probability, and fair index, particularly, in heavy traffic conditions. The building of traffic model in China mainland and the analysis of the simulation results has been a key foundation for the study of resource allocation schemes in the future.

A Resource Allocation Scheme of Low-Earth Orbit Satellite System Based on the Traffic Modelling

Traffic modelling is the foundation of satellite resource management. Considering the uneven traffic distribution in China, a traffic model of low-earth orbit satellite is established in this study according to the per-capita GDP and the density of population. Base on this model, a new dynamic channel allocation and reservation (DCAR) technique is proposed. The performance of the call blocking probability, the handoff blocking probability and the channel utilisation is evaluated by simulation. Different from the fixed channel allocation, DCAR implements channel allocation by estimating the traffic conditions of all spot beams. The simulation results show that DCAR achieves a significant improvement on call blocking probability and handover blocking probability, particularly under heavy traffic load.

Forecasting-Based Dynamic Virtual Channel Management for Power Reduction in Network-on-Chips

In this paper, a forecasting-based dynamic virtual channel allocation technique for reducing the power consumption of network on chips is introduced. Based on the network traffic as well as past link and total virtual channel utilizations, the technique dynamically forecasts the number of virtual channels that should be active. It is based on an exponential smoothing forecasting method that filters out short-term traffic fluctuations. In this technique, for low (high) traffic loads, a small (large) number of VCs are allocated to the corresponding input channel. To assess the efficacy of the proposed method, the network on chip has been simulated using uniform, transpose, hotspot, NED, and realistic GSM voice codec traffic profiles. Simulation results show that up to a 35% reduction in the buffer power consumption and up to 20% savings in the overall router power consumption may be achieved. The area and power dissipation overheads of the technique are negligible.

Channel Asymmetry in Cellular OFDMA-TDD Networks

This paper studies time division duplex- (TDD-) specific interference issues in orthogonal frequency division multiple access- (OFDMA-) TDD cellular networks arising from various uplink (UL)/downlink (DL) traffic asymmetries, considering both line-of-sight (LOS) and non-LOS (NLOS) conditions among base stations (BSs). The study explores aspects both of channel allocation and user scheduling. In particular, a comparison is drawn between the fixed slot allocation (FSA) technique and a dynamic channel allocation (DCA) technique for different UL/DL loads. For the latter, random time slot opposing (RTSO) is assumed due to its simplicity and its low signaling overhead. Both channel allocation techniques do not obviate the need for user scheduling algorithms, therefore, a greedy and a fair scheduling approach are applied to both the RTSO and the FSA. The systems are evaluated based on spectral efficiency, subcarrier utilization, and user outage. The results show that RTSO networks with DL-favored traffic asymmetries outperform FSA networks for all considered metrics and are robust to LOS between BSs. In addition, it is demonstrated that the greedy scheduling algorithm only offers a marginal increase in spectral efficiency as compared to the fair scheduling algorithm, while the latter exhibits up to 20% lower outage.

Dynamic channel allocation techniques using adaptive modulation and adaptive antennas

This article studies the impact of adaptive quadrature amplitude modulation (AQAM) on network performance when applied to a cellular network, using adaptive antennas in conjunction with both fixed channel allocation (FCA) and locally distributed dynamic channel allocation (DCA) schemes. The performance advantages of using adaptive modulation are investigated in terms of the overall network performance, mean transmitted power, and the average network throughput. Adaptive modulation allowed an extra 51% of users to be supported by an FCA 4-QAM network, while in conjunction with DCA, an additional 54% user capacity was attained.

Adaptive antenna array assisted dynamic channel allocation techniques

The performance of base station adaptive antenna arrays (AAAs) is investigated in conjunction with fixed channel allocation (FCA) and dynamic channel allocation (DCA) schemes. Locally distributed DCA arrangements are studied and benchmarked against standard FCA, in the context of both line-of-sight (LOS) and multipath propagation environments. One-, two-, four-, and eight-element AAAs are employed using the sample matrix inversion (SMI) beamforming algorithm, in both the up- and the downlink. In most investigated scenarios, the locally optimized least interference algorithm (LOLIA) exhibited the best overall compromise in terms of a set of combined metrics, such as the forced termination probability, new call blocking probability, and the probability of a low quality access.

UpdateSearch: A New Dynamic Channel Allocation Scheme for Mobile Networks That Can Adjust to System Loads

Distributed dynamic channel allocation techniques are an integral part of distributed mobile computing systems where nodes communicate among themselves via wireless radio channels. The channel allocation schemes can be broadly categorized as search based or update based. Search based techniques have low messaging complexity and are suited for high system load and low request rates. On the other hand update based schemes have higher messaging complexity but are more suitable for low system load and high request rates. This paper presents a combined scheme, called UpdateSearch, which provides the advantages of both types of schemes. UpdateSearch is parameterized by the number of channel classes k, 1≤k≤n, where n is the total number of channels in the system. The parameter k can be adjusted to control the number of concurrent searches and degree of contention between cells competing for channels in the system. For ke1 and ken the scheme respectively behaves as basic search and basic update scheme l2r. A simple analytical model is used to compare the performance of UpdateSearch for various values of k with the basic update and search techniques in terms of channel allocation time and number of simultaneous channel selections allowed in the system under different system loading conditions.

Handover queuing strategies with dynamic and fixed channel allocation techniques in low Earth orbit mobile satellite systems

This paper deals with the performance evaluation of various resource management strategies that are suitable for low Earth orbit mobile satellite systems (LEO-MSSs). A user mobility model has been proposed and its statistical parameters have been derived. Both fixed channel allocation (FCA) and dynamic channel allocation (DCA) techniques have been considered. Moreover, in order to reduce the handover failure probability, we have assumed that interbeam handover requests which do not immediately obtain service can be queued. In particular, two different queuing disciplines have been compared: (a) the first input first output (FIFO) scheme and (b) a new technique called last useful instant (LUI) which is based on the knowledge of the maximum time within which the handover procedure must be accomplished. Implementation aspects for the LUI technique in a LEO-MSS have been discussed also in comparison with the measurement-based priority scheme (MBPS), previously proposed in the literature on this subject. The efficiency of the LUI queuing scheme as regards the FIFO technique has been investigated by simulations for both DCA and FCA techniques. An analytical approach has been also presented in order to allow the performance evaluation of the FCA scheme with different handover queuing disciplines.

Comparison of two novel heuristic dynamic channel allocation techniques in cellular systems

Dynamic channel assignment (DCA) has been discussed in the literature as a way to achieve improved resource management in cellular networks. In the simplest dynamic allocation scheme, all channels are kept in a central pool and are used on a call-by-call basis. DCA is therefore a complex real time operation and various heuristic methods have been devised as mechanisms to give a fast and reliable solution to this problem. This paper examines the implementation of a DCA model using two approaches from the field of evolutionary computation. The first is the so called genetic algorithm (GA) and the second is the combinatorial evolution strategy (CES). Computer simulations evaluate and compare these proposed heuristic DCA schemes concerning their application to a cellular model for both uniform and non-uniform traffic load conditions. © 1998 John Wiley & Sons, Ltd.

Satellite-UMTS traffic dimensioning and resource management technique analysis

The universal mobile telecommunications system (UMTS) will consist of space UMTS (S-UMTS) and terrestrial UMTS (T-UMTS) components. An algorithm for predicting the traffic capacity in terms of the number of subscribers for the satellite component of UMTS is presented. The algorithm takes into account the takeup characteristics of new products, the growth of gross domestic product (GDP), the projection of population, the tariff of the service, and price fall over the forecast period. The predicted traffic is used to generate a traffic grid in terms of Erlang of dimension 36/spl times/72 in steps of 5/spl deg/ in both the latitude and longitude directions. The traffic grid is used to evaluate the performance of a dynamic channel allocation (DCA) technique as, well as a fixed channel allocation (FCA) technique. Both channel allocation techniques have been considered with the queuing of handover (QH) requests. In order to compare the respective techniques' performance, a low-earth orbit mobile satellite system (LEO-MSS) mobility model is developed to take into account the effect of satellites' motion during interbeam handovers. A theoretical model for obtaining the values of blocking probabilities for low-traffic loads is presented. Finally, the performance of the DCA-QH technique is compared with the FCA-QH technique under suitably defined traffic and mobility conditions.

Performance comparison of different dynamic channel allocation techniques for mobile satellite systems

AbstractDynamic Channel Allocation (DCA) techniques permit a high resource utilization in cellular networks and are able to adapt themselves in the presence of rapid variations of traffic loads offered to the cells. Therefore, they are particularly suitable for Mobile Satellite Systems (MSSs). This paper compares the performance of several DCA solutions that are based on the evaluation of a cost function in terms of both quality of service parameters (i.e., blocking probabilities) and signaling load to be supported by the system. Both GEostationary Orbit (GEO) and Low Earth Orbit (LEO) MSSs have been considered. A particularly interesting DCA solution is proposed that tries to serve a new call attempt in a cell where no channel is available by means of a channel reconfiguration in an interfering cell. Handover requests that do not attain immediately service can be queued for a maximum time in order to enhance system performance.

Bounds and Performance Networks of Reuse Partitioning in Cellular

In this paper we study a scheme that allows asmooth increase of the capacity of a cellular system forcircuit switching by applying cell partitioning andusing dynamic channel allocation techniques. A bound is computed for this reuse partitioningscheme that gives the maximum theoretical gainaccomplished in the system bandwidth. The performance ofthe proposed scheme in terms of blocking probability is evaluated both when the position of themobiles remains unchanged and when mobility is takeninto account. The numerical results show that thecapacity of the proposed scheme is sensibly higher than that of a fixed allocation scheme.

PERFORMANCE STUDY OF AN INTEGRATED SATELLITE/TERRESTRIAL MOBILE COMMUNICATION SYSTEM

Terrestrial cellular networks and mobile satellite systems are expected to converge towards a future integrated satellite/terrestrial mobile communication network. Besides a system globalization, the integration of terrestrial and satellite mobile systems will lead to the unloading of the fixed part of the mobile network. This paper proposes an integrated satellite/terrestrial mobile communication system and evaluates its performance in terms of the blocking probability for new call attempts, the call dropping probability and the probability of unsuccessful call. This communication system was simulated and its performence compared with that of a stand-alone terrestrial mobile system. In the terrestrial part of the system we have considered fixed channel allocation (FCA) and dynamic channel allocation (DCA) techniques. Satellite channels can have equal or lower priority compared to terrestrial channels. The improvement of the system performance by means of satellite-to-terrestrial handovers was also estimated.

A dynamic channel allocation technique based on Hopfield neural networks

The interest in global spectrum allocation techniques is growing with the always increasing spectrum demand for (cellular) mobile communications. However, the best algorithms suffer from high computational times that reduce the possibility of a practical implementation. This paper deals with a dynamic channel allocation (DCA) technique based on an energy function whose minimization gives the optimal allocation. Due to the particular formulation of such an energy function, the minimization can be performed by a Hopfield neural network for which a fast hardware implementation has been recently proposed in the literature. The performance of the proposed DCA technique is derived by computer simulations. Comparisons with a classical fixed allocation technique (FCA) and a different DCA technique are shown to highlight the better performance of the proposed DCA technique.

Call blocking performance for dynamic channel allocation technique in future mobile satellite systems

Different dynamic channel allocation (DCA) approaches based on the evaluation of a cost function are proposed. The scenario considered is low earth orbit and geostationary orbit mobile satellite systems. A suitable user mobility model has been defined to generate interbeam handover requests. Different alternatives to manage interbeam handovers have been investigated. Among them, the most promising solution seems to be the queuing of handover requests. The quality of service parameters that have been considered are: blocking probability for new call arrivals, handover failure probability and the probability of incompletely served call owing to the initial blocking or to the failure of a subsequent handover request. Comparisons among the proposed DCA techniques and the fixed channel allocation technique have been carried out to find a solution that represents a good trade-off between the blocking performance and the required signalling load.