Enhanced dynamic radio resource allocation performance using a gradient descent algorithm

We propose a framework for network-assisted radio resource management in wireless data networks. This type of radio resource management techniques offer implementation and capacity benefits compared to conventional, interference-measurement based, dynamic channel assignment (DCA) algorithms. The basic idea is to use interbase signaling to shift most of the burden of the resource allocation from the air interface to the backbone infrastructure. By exchanging channel assignment as well as other relevant information in real time through the backbone network, each base can calculate the impact of a resource assignment on the system. As a result, rapid interference measurements, which are typically needed to implement DCA schemes, are replaced by a limited amount of path loss measurements and the computation of interference conditions by the base stations. This significantly reduces the measurement and over-the-air signaling requirements, and can also provide an opportunity for a better optimization of the system performance. We focus on two specific algorithms: network-assisted least-interference-based dynamic packet assignment (NA-LI-DPA) and network-assisted dynamic packet assignment with throughput optimization (NA-DPA). NA-LI-DPA closely resembles a least-interference-based dynamic channel assignment algorithm, and NA-DPA attempts to further improve the overall system throughput. The algorithms, as defined, are appropriate for a best-effort data service, where the primary goal is to provide a higher throughput. However, it will be clear from the discussion that it is also feasible to alter the algorithms to optimize performance metrics other than throughput, e.g., to ensure a certain quality of service. We show through simulation that, for a system like enhanced general packet radio service (EGPRS) system, NA-DPA can provide a throughput that is 50% higher than random packet assignment, and 25% higher than that obtained by conventional DCA algorithms.

There are two types of strategies to assign the channels to a cell: fixed channel assignment (FCA) and dynamic channel assignment (DCA). The basic characteristics of DCA are presented in comparison with FCA. The authors introduce various DCA strategies and discuss some of most important DCA research topics currently being pursued. In particular, the authors focus on microcellular systems, including a proposed MD (moving direction) strategy. It uses the information a mobile station's (MS's) moving direction with the DCA strategy. A channel is selected among those occupied by MSs moving in the same direction with the concerned MS. In this manner, the MS can still use the same channel at the handover with high probability. DCA requires more radio equipment at each base station than FCA, and it requires elaborate channel assignment control. However, it exploits the limited frequency spectrum efficiently and has a lower forced call-termination rate than FCA when the blocking rates are equal.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Built upon a shared wireless medium, wireless network is particularly vulnerable to jamming attacks. The ability to recover from attacks and maintain an acceptable level of service degradation is a crucial aspect in the design of a wireless network. To address this issue, this paper investigates the network restoration solutions via the joint design of traffic rerouting, channel re-assignment, and scheduling. Efficient routing and channel assignment schemes can relieve the interference caused by both the normal network nodes and the jamming nodes. Therefore, based on the necessary conditions of schedulability, we first formulate the optimal network restoration problem as linear programming problem, which gives an upper bound on the achievable network throughput. After we solve the LP problems, we have a set of flows assigned to edges that have been assigned to different channels. And based on the LP solutions, we provide a greedy scheduling algorithm using dynamic channel assignment, which schedules both the network traffic and the jamming traffic. In particular, we consider two strategies, namely global restoration and local restoration, which can support a range of tradeoffs between the restoration latency and network throughput after restoration. To quantitatively evaluate the impact of jamming attacks during and after restoration, we define two performance degradation indices, transient disruption index (TDI) and throughput degradation index (THI). Finally, extensive performance evaluations are performed to study the impact of various jamming scenarios in a multi-hop multi-channel wireless network.

Novel strategies for automatic satellite constellation design with satellite diversity and radio resource management are proposed. The automatic satellite constellation design means that some parameters of satellite constellation design can be determined simultaneously. The total number of satellites, the altitude of a satellite, the angle between planes, the angle shift between satellites and the inclination angle are considered in the design. Satellite constellation design is modelled using a multiobjective genetic algorithm. This method is applied to low Earth orbit (LEO), medium Earth orbit (MEO) and hybrid constellations. The use of a genetic algorithm allows automatic satellite constellation design while achieving dual satellite diversity statistics. Furthermore, a strategy for dynamic channel allocation is proposed that uses a genetic algorithm for use in mobile satellite systems (MSS) networks. The main idea behind this algorithm is to use the minimum cost as a metric to provide optimum channel solutions for specified interference constraints. The simulation is designed for a MEO satellite constellation. Using this algorithm, the proposed model outperforms conventional dynamic channel assignment (DCA) schemes in terms of call blocking and call dropping probability. Generally, genetic algorithms are robust to dynamic variations in satellite constellation design and provide resource allocation improvements in DCA in MSS networks.

In GSM Telecommunication networks it is important to efficiently utilize the scarce radio spectrum using a proper channel assignment scheme. The objective of a Channel Assignment problem is to assign a required number of channels to each cell in a way to achieve both efficient frequency spectrum utilization and minimization of interference effects (by satisfying a number of channel reuse constraints). Dynamic Channel Assignment (DCA) assigns the channels to the cells dynamically according to traffic demand, and hence, can provide higher capacity (or lower call blocking probability), fidelity and quality of service than the fixed assignment schemes. Devising a DCA, that is practical, efficient, and which can generate high quality allocations, is challenging. This paper presents an effective and efficient Modified Genetic Algorithm (MGA) for the solution of DCA Problem.

This paper describes communication traffic characteristics in cellular systems where dynamic channel assignment is used and the traffic intensity in each cell is not equal. Clique packing is used as a model of dynamic channel assignment, and communication traffic characteristics of clique packing under the unequal load are discussed. Communication traffic characteristics of practical dynamic channel assignment methods, such as first-available method, are also discussed by using the clique packing model. The results of this paper contribute to estimation of the blocking performance of dynamic channel assignment under the unequal traffic load.

In cellular mobile communications, how to achieve optimum system capacity with limited frequency spectrum is one of the main research issues. Many dynamic channel assignment (DCA) schemes have been proposed and studied to increase the capacity of cellular systems. Reuse partitioning (RP) is another technique to achieve higher capacity by reducing the overall reuse distance. In this paper, a new network-based DCA scheme with the use of RP technique is proposed, namely dynamic reuse partitioning with interference information (DRP-WI). The scheme aims to minimize the effect of assigned channels on the availability of channels for use in the interfering cells and to reduce their overall reuse distances. Simulation results have confirmed the effectiveness of DRP-WI scheme. Under both uniform and nonuniform traffic distributions, DRP-WI exhibits outstanding performance in improving the system capacity. It can provide about 100% capacity improvement as compared to conventional fixed channel assignment scheme.

Blocking probabilities in cellular mobile communication networks using dynamic channel assignment are hard to compute for realistic sized systems. This computational difficulty is due to the structure of the state space, which imposes strong coupling constraints amongst components of the occupancy vector. Approximate tractable models have been proposed, which have product form stationary state distributions. However, for real channel assignment schemes, the product form is a poor approximation and it is necessary to simulate the actual occupancy process in order to estimate the blocking probabilities.Meaningful estimates of the blocking probability typically require an enormous amount of CPU time for simulation, since blocking events are usually rare. Advanced simulation approaches use importance sampling (IS) to overcome this problem. In this article, we study two regimes under which blocking is a rare event: low-load and high cell capacity. Our simulations use the standard clock (SC) method. For low load, we propose a change of measure that we call static ISSC , which has bounded relative error. For high capacity, we use a change of measure that depends on the current state of the network occupancy. This is the dynamic ISSC method. We prove that this method yields zero variance estimators for single clique models, and we empirically show the advantages of this method over naïve simulation for networks of moderate size and traffic loads.

In cellular mobile communication systems, a channel assignment problem has been extensively studied. In order to avoid exhaustive search, the number of reallocatable channel is limited only one in TPB method which is one of dynamic channel assignment proposed by Chang. In this paper, a dynamic channel assignment by using the maximum neural network with reinforced self-feedback (MNN-RS) is proposed. From numerical experiments, it is confirmed that the proposal improves blocking probability and reduces the probability that blocking probability exceeds arrowable rate. Lastly the proposed model is implemented on Xilinx FPGA XCV300E and scalability is discussed.

The radio frequency spectrum, a scarce resource in mobile communications, has to be efficiently utilized with the objective of increasing the network capacity and minimizing the interference. A variety of channel assignment strategies have been developed to achieve these objectives. Not only the mobility of the wireless user but also different types of wireless multimedia services create uncertainty in demand and non-optimum use of radio resources. As the cell sizes get smaller, there is a greater need for efficient channel assignment algorithms which are desired to dynamically balance the load of the system by performing reassignments when needed. Static schemes are no longer desirable for small cell systems under heavy and non-uniform multi-rate traffic. We propose a dynamic multi-channel assignment algorithm where the assignment decision is assisted by the mobiles. Our algorithm is based on the concept of network flows, which provide us with the framework to uniformly handle all the events occurring in the system including possible degradation and improvement of the existing assignments. This model enables fast local computations and avoids global reconfiguration which prevent other algorithms being practical.

The variety of services offered in cellular networks is rapidly increasing. However, optimizing the GSM/EDGE air interface for a multitude of services remains a big challenge. Dynamic frequency and channel assignment (DFCA) provides powerful tools to manage the highly variable interference tolerance properties of different services in the air interface. The application of the DFCA concept in a GERAN (GSM/EDGE radio access network) with a mix of services is studied. The technical implementation of DFCA with multiple service support is also presented. The concepts are validated with extensive simulations. Simulations involve multiple scenarios with varying service mixes including both circuit switched and packet switched services. The results show significant capacity gains in both single service and multiple service scenarios.

In this paper we refer to a specific class of Dynamic Channel Allocation (DCA) strategies, namely the inferferencefree, timid, not-conditioned class. The main concern of this work is to verify if and to what extent strategies belonging to this class can offer better performance than Fixed Channel Allocation (FCA). The interest in this kind of strategies is motivated by their feasibility with current TDM technologies, the limited amount of information required to carry out channel assignments and their intrinsic stability. In this framework we present a simple, but very attractive DCA strategy, the so-called Geometric DCA (GDCA). A performance evaluation is carried out to compare some representative DCA strategies of the considered class, by using a user mobility model that accounts for the large fluctuations of the number of users in a cell coverage area expected in a microcellular environment. The effect of the non-null propagation time required by the information exchange in the DCA strategies is also taken into account. It emerges that the proposed GDCA allows better performance than more sophisticated strategies already proposed, at the expense of a frequency planning carried out only at network configuration. This is due to the ability of GDCA to exploit the a priori information to maintain a tight geometric packing of used carriers. The reported results also show that DCA strategies in the considered class cope with large and sudden traffic fluctuations remarkably better than the FCA scheme does and that the advantage becomes more evident as the burstiness of the user mobility process (hence of the offered traffic) increases.

In order to fully exploit the aggregate bandwidth available in the radio spectrum, future wireless mesh networks (WMN) are expected to take advantage of multiple orthogonal channels, where the nodes have the ability to communicate with multiple neighbours simultaneously using multiple radios (NICs) over orthogonal channels. Dynamic channel assignment is critical for ensuring effective utilization of the non-overlapping channels. Several algorithms have been proposed in recent years, which aim at achieving this. However, all these schemes inherently assume that the mesh nodes are well-behaved without any malicious intentions. A recent work has exposed the vulnerabilities in channel assignment algorithms. In this paper, a mechanism is proposed to secure the channel assignment algorithms, addressing the security vulnerabilities in the existing algorithms. The proposed mechanism successfully prevents the WMN from the recently exposed attacks. The simulation based experiments show the effectiveness of the proposed solution. The experiments also show that the incurred overhead because of security is negligible.

Heterogeneous networks constitute a promising solution to the emerging challenges of 5G networks. According to the specific network architecture, a macro-cell base station (MBS) shares the same spectral resources with a number of small cell base stations (SBSs), resulting in increased co-channel interference (CCI). The efficient management of CCI has been studied extensively in the literature and various dynamic channel assignment (DCA) schemes have been proposed. However, the majority of these schemes consider a uniform approach for the users without taking into account the different quality requirements of each application. In this work, we propose an algorithm for enabling dynamic channel assignment in the 5G era that receives information about the interference and QoS levels and dynamically assigns the best channel. This algorithm is compared to state-of-the-art channel assignment algorithm. Results show an increase of performance, e.g., in terms of throughput and air interface latency. Finally, potential challenges and way forward are also discussed.

Most of the existing Medium Access Control (MAC) protocols for ad hoc networks involve the use of a single wireless channel as the transmission medium. Throughput of a single channel MAC protocol is li-mited by the bandwidth of a single channel. Use of multiple channels helps to alleviate this problem. One of the existing methodologies towards using multiple channels in a MAC protocol for ad-hoc networks is to assign one channel as the control channel and the rest as data channels. However, dedicating one channel completely for control messages leads to a poor utili-zation of the available bandwidth. In this paper, we propose a Control-channel-Reuse-based Multiple-channel MAC (CRM-MAC) protocol in ad-hoc net-works which identifies mechanisms to improve the bandwidth utilization. The proposed protocol derives from an existing multi-channel MAC solution called Dynamic Channel Assignment (DCA). We demonstrate the improvement in our proposed protocol over DCA through extensive simulations.