Hybrid Channel Allocation Research Articles

An adaptive context-aware vertical handover decision algorithm for heterogeneous networks

In a heterogeneous network, vertical handovers occur frequently between different access technologies to meet the requirements of mobile users. The selection of an access technology for a mobile user for handover largely depends on the contextual information of the user and network at that point of time. In this work, we have proposed an adaptive, context-aware vertical handover decision algorithm for heterogeneous networks. Both static and dynamic contextual information about the user and the network are given as inputs to our proposed algorithm. They are provided proactively by the networks to the mobile nodes on a timely basis. An optimal network scanning procedure is introduced as part of the handover process to minimize the energy consumption of the nodes. We also propose a utility function-based cell load balancing mechanism to improve overall resource utilization. In addition, a delay-sensitive handover traffic-based hybrid channel allocation mechanism is proposed. The simulation results clearly suggest that the proposed work significantly enhanced the overall performance of the system as compared to some existing work in terms of call blocking probability, channel utilization rate, consumed energy, and handover delays.

An improved fast transform algorithm based on adaptive hybrid channel allocation in TSCH networks

Time Slotted Channel Hopping (TSCH) is one of the five access behavior technologies defined in the IEEE 802.15.4e standard. Research shows that the wireless sensor network with single dynamic and static channel allocation in TSCH mode has higher performance. The clogging rate results in unnecessary energy waste. Therefore, this paper proposes an adaptive hybrid channel allocation strategy (AHCA) to measure the link quality change of wireless sensor networks in TSCH mode. The strategy estimates the part of the channel quality and determines whether the node wants to transmit on this channel and the optimal channel for node information transmission. According to the change of the amount of information transmitted, the hybrid channel allocation scheme of the dynamic and static channel ratio is adaptively adjusted to reduce the energy consumption of the information transmission process. This article performs experimental simulation on Contiki-NG. The experimental results show that the proposed scheme has shorter transmission time and lower congestion rate than the single dynamic static channel allocation wireless sensor network. The more reasonable and effective measurement, analysis and use of channel resources can fundamentally increase the amount of information transfer in wireless sensor networks per unit time, and thus extend the lifetime of wireless sensor networks.

A Review on Hybrid Channel Allocation Schemes for Cellular Mobile Telecommunication Systems

A Review on Hybrid Channel Allocation Schemes for Cellular Mobile Telecommunication Systems

Resource Allocation for Green Cloud Radio Access Networks With Hybrid Energy Supplies

In this paper, we study sustainable resource allocation for cloud radio access networks (CRANs) powered by hybrid energy supplies (HES). Specifically, the central unit (CU) in the CRANs distributes data to a set of radio units (RUs) powered by both on-grid energy and energy harvested from green sources, and allocates channels to the selected RUs for downlink transmissions. We formulate an optimization problem to maximize the net gain of the system which is the difference between the user utility gain and on-grid energy costs, taking into consideration the stochastic nature of energy harvesting process, time-varying on-grid energy price, and dynamic wireless channel conditions. A resource allocation framework is developed to decompose the formulated problem into three subproblems, i.e., the hybrid energy management, data requesting, and channel and power allocation. Based on the solutions of the subproblems, we propose a net gain-optimal resource allocation (GRA) algorithm to maximize the net gain while stabilizing the data buffers and ensuring the sustainability of batteries. Performance analysis demonstrates that the GRA algorithm can achieve close-to-optimal net gain with bounded data buffer and battery capacity. Extensive simulations validate the analysis and demonstrate that GRA algorithm outperforms other algorithms in terms of the net gain and delay performance.

Mitigating Uplink Interference in Femto–Macro Coexisted Heterogeneous Network by Using Power Control

In the femto–macro coexisted heterogeneous network, the uplink transmission of femtocell user equipment (FUE) interferes with the macrocell base station (MBS) and deteriorates the capacity of macrocell user equipments (MUEs). To mitigate the cross-tier interference, a power control mechanism is proposed to adjust transmission power of FUE. The approach of this paper is to derive the minimum transmission power to achieve the required modulation and coding scheme and the maximum transmission power without violating the maximal tolerable interference of MBS, respectively. By selecting the minimum one among the two derived transmission power and the maximum allowable transmission power of an FUE as the transmission power of each FUE, the cross-tier interference from FUEs to MBS are alleviated. Simulation results show that when femtocells and macrocell are operated in the co-channel allocation approach, the average capacity of MUEs by using the proposed power control mechanism can be increased by 53.4% as compared to that without power control when 40 femtocells are deployed. The cost for the improvement is a reduction in the average FUE capacity by 7.3%. When the hybrid channel allocation approach is employed, the average capacity of MUEs can be further increased by 21.3%. Hence, the proposed power control mechanism is an efficient solution to mitigate the cross-tier interference and improve the average capacity of MUE with an acceptable reduction in the capacity of FUEs for the femto–macro coexisted heterogeneous network.

A Review of Menace of Call Drops in India and Possible Ways to Minimize It

In this age of wireless telecommunications, it is expected from the telecom service providers that the quality of services is the best; but unfortunately, it is not so and in India the telecom sector is struggling with a menace called Call Drops. Most of the operators in India do not meet the benchmark set by the TRAI for call drops. So, keeping in mind the Indian context of the problem, in this paper, the overall condition of call drops has been reviewed and possible ways to minimize the phenomena of call drops- Cell Splitting and Sectoring, Dynamic channel allocation, Hybrid channel allocation. Also, mathematical proof of relevance of these methods has been provided through Erlang B Formula and various other methods of proving used in other scientific pieces of work have been discussed such as Poisson Probability Function with a discrete variable. The data collected from various resources shows the gravity of the problem. Cell splitting and sectoring methods result in improvised soft handover mechanisms which in turn decrease the rate of call drops. This paper provides a brief but sufficed introduction to the term of call drops and also proposes some simple but efficient ways to cope this menace.

Hybrid channel allocation in cellular network based on genetic algorithm and particle swarm optimisation methods

The challenge in wireless cellular network is to suit the changeable traffic demand by assigning appropriate channels from limited frequency spectrum and to maintain a desirable stratum of interference level. The system capacity can be improved by a reduction in interference effect by applying effectual channel assignment technique. This work proposes, genetic algorithm (GA) and particle swarm optimisation (PSO) techniques, with hybrid channel allocation for interference reduction. In GA, integer genetic representation for crossover and mutation operation is applied and graph theory based fitness function is designed. In PSO, hard and soft constraints are used for designing fitness function. The proposed GA and PSO compute co-channel and co-site interferences represented by interfering edges, the computation time and generations/iterations required. The signal-to-interference ratio (SIR) is determined, considering attenuation of the signal predicted by applying Hata propagation model. The performances of the proposed methods are applied on benchmark instances and are compared with the reported literature. The proposed PSO shows improvement in performance than GA in terms of reduction in interference, required computation time, generations/iterations required also improvement in the SIR.

On Demand Stable Routing with Channel Allocation and Backoff Countdown Optimization in Wireless Mesh Networks

The multi-channel and multi-interface wireless mesh networks (WMNs) allow multiple orthogonal channels simultaneously to facilitate increased broadband connectivity to the end-users. Many efforts have been devoted to allocate the channels to the interfaces in a multi-channel multi-interface setting. Recently, the hybrid channel allocation mechanism jointly optimizes the routing and channel assignment, by utilizing the queuing traffic. It is essential to map the optimization of traffic distribution on each channel along with channel switching in such an order that it adapts to the changing traffic. However, the contention in medium access and channel switching delay are the key issues in a multi-channel hidden terminal problem. The proposed optimized stable path- channel allocation and routing (OSCAR) protocol is a hybrid multi-channel protocol that reduces the communication delay without degrading the network performance. The proposed work, OSCAR determines a highly stable path that increases mesh routers to improve the routing efficiency. The channel allocation mechanism mainly promotes queue dynamics based probabilistic channel selection (QDPCS), and backoff countdown optimization (BCO). An essential component of the QDPCS scheme is the factor of queuing utilization, and this strategy selects a least congested channel. The BCO mechanism creates the logical order among contending nodes based on the remaining backoff value. It reduces the medium access delay and enables the feasibility of scheduled transmissions without degrading the network throughput. Finally, the performance evaluation results show that the OSCAR protocol outperforms the existing protocol over WMNs.

车载自组网MAC层相关技术的研究

随着车载自组网的发展，如何优化底层通信是车载自组网中研究的热点。为提高网络容量及信道利用率，本文提出了一种基于混合分配的VANET信道优化策略。在网络拥塞控制方面，针对车载自组网的特殊性，本文提出了一种基于缓冲区优化的拥塞预防策略，对缓冲区内的消息包进行一定的丢包，尽可能地降低网络拥塞发生的可能性。最后，通过仿真实验对提出的策略进行验证。仿真结果表明：该策略合理分配了信道，显著提高了网络的吞吐量。 With the development of VANET, how to optimize the underlying communication becomes a re-search hot. A VANET channel optimization strategy based on hybrid channel allocation is probed. In the network congestion control, aiming at the particularity of VANET, a congestion prevention strategy based on buffer optimization is discussed. Some data packets are thrown away in buffer to relieve the pressure of buffer and reduce the possibility of network congestion. The proposed strategy is verified by simulation experiment. The experiment results indicate that channels are allocated reasonably and the network throughput is improved significantly.

An optimization technique for efficient channel allocation in cellular network

For today’s wireless mobile communication systems, efficient use of limited radio spectrum with minimum interferences is required. Itinvestigates an Optimal Genetic Algorithm approach (GA) for Hybrid Channel allocation (NP hard) focusing on reduction in interference in cellular Network. Obtained an interference graph based fitness function to enhance the performance of HCA for interference reduction. It is shown that the use of integer genetic representation for Crossover and mutation operation enhances the speed of GA leading to less computation time. Comparison of proposed method is done with reported literature for KUNZ 4 which results in less co-channel and co-site interference depicted by interfering edges and also number of generations required are less. The result for KUNZ 1, KUNZ 2 and KUNZ 3 are obtained with minimum interference along with computation time.

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.

다양한 환경에 적용이 가능한 UHGA 채널 할당 방식

스마트 기기의 보급 확대로 다양한 콘텐츠를 서비스하는 이동 단말기의 한정된 채널 할당 문제가 심화되고 있다. 이동통신망에서는 이동국에서 채널할당 요청이 있을 때 교환국에서 각 기지국에 속한 이동국에 채널을 할당한다. 이 때 한정된 채널을 효과적으로 할당하기 위한 다양한 방식들이 제안되고 있는데, 여기서는 하이브리드 채널 할당에 유전 알고리즘을 이용한 UHGA(Universal Hybrid Channel Assignment using Genetic Algorithm)이 농촌 지역이나 도심 지역과 같은 다양한 환경의 범용 망에 적용되어 효율성이 있음을 시뮬레이션을 통해 검증한다. As the spread of smart devices that service variety of content, limited mobile terminal channel assignment problem has intensified. In the channel assignment in mobile networks mobile switching center at the request belongs to each base station allocates the channel to the mobile station. This effectively allocate the limited channels of various methods have been proposed for, in this case a hybrid channel allocation using genetic algorithms UHGA (Universal Hybrid Channel Assignment using Genetic Algorithm) in rural areas or urban areas, such as universal network applied to a variety of environments that the efficiency is verified through simulation.

Optimal Channel Allocation with Hot-Spot Technique in Wireless Network

In wireless mobile communication systems, proper channel allocation scheme is required. Due to the limitation of available frequency spectrum, channels must be reused as much as possible to increase system capacity. Complication arises in channel allocation, when more than one cell become “hot-spot” in the network of one BSC. The cells become “hot-spot” when bandwidth resources currently available in those cells are not sufficient to sustain any more call. In hybrid channel allocation, cells send a multilevel hot-spot notification to the dynamic pool of BSC on each channel request that cannot be satisfied locally at the base station. Proportional to the current hot-spot level of the cell, this hot-spot notification will request more than one channel to assign to the requesting cell. Severe complication arises, when not even one channel available in the dynamic pool of BSC in order to assign to requesting cells. This is the situation, when call starts dropping or blocking. This paper presents a new scheme in which BSC will fetch those ideal channels, which are borrowed to requesting cell from the dynamic pool in the time of hot spot but become ideal in the temporary pool of BTS for some period of time. BTS make use of these channels in order to sustain new incoming call .The proposed algorithm in this paper will reduce the call dropping probability comparatively more than the simple hybrid channel allocation algorithm.

Survey of Channel Allocation Algorithms Research for Cellular Systems

<b> </b><b> </b>In recent years, we have witnessed a huge interest in the study of channel allocation and handoff strategies for cellular systems to ensure continuous services that guarantee QoS to mobile users. In this paper, we have a detailed discussion of different categories of wireless channel allocation schemes. The basic purpose of the study is to provide a comprehensive review of different categories of channel allocation algorithms in cellular systems and to recommend future directions of research in the area. The paper gives a survey of published papers for discussing channel allocation schemes for cellular system. The QoS is always a major concern for the services offered through cellular systems and it is observed that there are always trade-offs among various parameters of the QoS of these services. There are many published papers which have taken care of different QoS parameters such as call blocking probability, call dropping probability along with other performance parameters. This paper provides details of the different categories of channel allocation schemes including static channel allocation, dynamic channel allocation and hybrid channel allocation studied in literature. Also in this paper, we explore the different channel allocation strategies, including the scenarios in which channel allocation strategies based on centralized channel control, distributed channel control, mutual exclusion algorithms and genetic algorithms, are used. Also, we have summarizes trade-offs between different channel allocation schemes in terms of their complexity and performance. In this paper, channel allocation in different context of complex situations such as the ones arising in offering multimedia based services and other arising in the channel allocation for mobile base station systems and use of power management in channel allocation are explained. This paper also examines different handoff handling provision and prioritization schemes proposed in the literature for cellular systems.

HANDOFF DETERMINATION FOR A HYBRID CHANNEL ALLOCATION ALGORITHM IN WIRELESS AND MOBILE NETWORKS

The handoff rate is identified in a hybrid channel allocation algorithm of a wireless and mobile network. In this network model, both new calls and handoff calls to a cell have possibilities to borrow channels from the control center if all allocated channels to the cell are used up. In addition, there is a buffer with finite size reserved exclusively for handoff calls in a cell when they arrived but are not be able to borrow channels from the control center. In this paper, we derived a novel and theoretical expression of the handoff rate in the network first. This analytical expression for handoff rate is a general form which covers several special cases discussed in the literature. Then, an efficient iterative algorithm to calculate this handoff rate is proposed also. By using this algorithm, the handoff rate and the blocking probability of both new calls and handoff calls will be successfully derived at the same time. Furthermore, our numerical analysis validates the algorithm and the corresponding theoretic expression.

HYBRID CHANNEL ALLOCATION IN WIRELESS CELLULAR NETWORKS

The enormous growth of mobile telephone traffic, along with the limited number of channels available, requires efficient reuse of channels. Channel allocation schemes can be divided into three categories: Fixed Channel Allocation (FCA), Dynamic Channel Allocation (DCA) and Hybrid Channel Allocation (HCA). In HCA, channels are divided into two disjoint sets: one set of channels is assigned to each cell on FCA basis, while the others are kept in a central pool for dynamic assignment. This paper presents a hybrid channel allocation notification to the central pool on each channel request that cannot be satisfied locally at the base station. This notification will request more than one channel to be assigned to the requesting cell. When FCA would not support call then borrowed channels will be in use. The simulation study of the protocol indicates that the blocking probability of HCA will be low for less traffic and high for high traffic.

Joint hybrid channel allocation and multi-path routing protocol in mesh networks

In order to optimize the multi-interface and multi-channel resource in wireless mesh network, this paper studied the single-interface multi-path routing protocol and the policy of channel allocation in single-path networks, proposed the multi-path routing protocol - AODV-MP by combining the hybrid channel allocation method, which can not only realize the parallel transmission of multi-path in the network, but also increase the entire throughput rate of the network. Through analyzing the characteristics of multi-path routing protocol and considering the interference factors Signal-to-Noise Ratio ( SNR) related to neighboring nodes, the routing metric judgment WCETTSNR was put forward, and the routing metric worked as the ratio standard for traffic distribution. The AODV-MP multi-path routing protocol had been tested on the NS2 network simulation platform and the results indicate that the proposed protocol can increase the network throughput by approximately 45% and largely decrease the network delay in the situation of heavy traffics.

A Hybrid Resource Allocation Strategy with Queuing in Wireless Mobile Communication Networks

The main objective of third and future wireless mobile communication networks is to provide services efficiently to the mobile users in all environments. In wireless mobile Communication the channel allocation and quality of service are the major factors and important issues to decide the system performance. Here in our work a Hybrid Channel Allocation(HCA)strategy for channel allocation and queuing technique applied to Hybrid Channel Allocation strategy for Quality of Service(QoS) provisioning are implemented. The proposed HCA strategy considers new calls in Fixed Channel Allocation (FCA) method and handoff calls in Dynamic Channel Allocation (DCA) method to reduce the call blocking and call dropping probabilities. The application of queuing technique applied to HCA strategy increases the efficiency of the cellular system performance especially in micro and pico cellular environments and effectively utilize the available allocated radio spectrum. The performance shows the decrease in call blocking and dropping and an increased number of users in the available channels.

A hybrid channel allocation algorithm with priority to handoff calls in mobile cellular networks

This paper proposes and investigates a novel analytical model of a hybrid channel allocation algorithm within wireless cellular networks. Each cell of the network consists of a predesigned fixed number of channels and the network may approve the request for extra channels for both new and handoff calls if all predesigned channels are occupied. This approval depends on the types of new and handoff calls, as well as the number of approved additional channels in the cell. If a request is denied for the arriving new call, this call will be blocked and cleared from the system. However, if a request is denied for an arriving handoff call, this call will not be blocked immediately but rather put on hold in a buffer with finite space. The implication behind this is to give priority to handoff calls. For this proposed hybrid channel allocation scheme, we first obtain the stationary distribution of each cell when there are i calls connecting to the system and j calls holding on in the buffer. We then derive new and handoff call blocking probabilities, the average number of borrowed channels, and the average delay period of handoff calls. The numerical results show that the proposed hybrid algorithm is more efficient than other approaches, specifically, in comparison with methods without a borrowing capability for new calls and those without a reserved buffer priority for handoff calls. The idea and results presented in this paper are expected to provide guidelines for field data processing within current wireless and mobile network design and performance evaluation.

Resource management model and performance evaluation for satellite communications

AbstractEfficient resource management is mandatory to achieve maximum system capacity for next generation communications systems. Resource management deals with the available spectral band, time, power, and space for a transmission signal. It includes (i) the frequency planning, (ii) the selection of transmit power, and (iii) the assignment of the channels and access nodes to the users. The paper presents a generalized notation as well as graph algorithms for resource management problems. Impairment graphs can be used for frequency planning, whereas flow graphs are suitable for channel access problems. To evaluate the performance of the resource management, service criteria (such as blocking or the carrier to interference ratio C/I) or efficiency criteria (bandwidth requirements) can be derived from the graphs. The resource management techniques are applied to satellite networks with non‐geostationary orbits yielding time‐variant network topologies. As a simple example, the channel assignment and capacity optimization of the EuroSky Way system are shown. Furthermore, a comparison of fixed, dynamic and hybrid channel allocation schemes (FCA, DCA, HCA) for a typical MEO satellite scenario is given. Satellite diversity and its impact on bandwidth requirement and transmission quality is also examined. Finally, it is shown how spread spectrum systems can be investigated with the presented tools. Copyright © 2001 John Wiley &amp; Sons, Ltd.