Multi-constrained Max–Min Fair Resource Allocation in Multi-channel Wireless Sensor Networks

Wireless Personal Communications - Recent rich applications for the Internet of Things are demanding large bandwidth for communication which can cause congestion within multi-hop wireless sensor...     

Wireless Regional Area Networks and Cognitive Radio 2

The IEEE 802.22 Working Group hasbeen formed in November 2004with the task ofdeveloping astandard for the Wireless RegionalArea Network (WRAN) based onCognitive Radio (CR) technologies. Thestandard includes PhysicalLayer (PHY)and Media Access Control(MAC), usingthe already allocated fallow spectrums tobroadcast TVwith no interference. TheWRAN employs CR technologies tosense and estimate the televisionfrequencies and uses the dynamicspectrum management to find andallocate fallow …     

Adaptive Cost-Based with Max–Min AMC Routing Algorithm for Increasing Utilization and Reducing Blocking in IEEE 802.16j WiMAX Networks

Based on the IEEE 802.16e standard, WiMAX has proposed a relay-based mechanism, namely IEEE 802.16j, to extend the service area of the Multihop Relay Base Stations (MR-BSs) and to improve the Received Signal Strength quality. IEEE 802.16j thus can achieve two significant advantages: extending the WiMAX service area with a low-cost solution and compatible with the existing WiMAX specifications. The Relay Station (RS) can be classified into three types: Fixed RS, Nomadic RS and Mobile RS according to diverse features of mobility and relaying range. A multihop-relay WiMAX network including various types of RSs exhibits a critical routing issue, i.e., how to determine an efficient relay-based routing path between a Mobile Station (MS) and a MR-BS. This paper thus proposes an IEEE 802.16j-conformed relay-based adaptive competitive on-line routing approach that focuses on the Non-Transparent Relay-Station (NT-RS) mode, where the path with the least cost and the highest AMC coding rate will be selected in terms of the link bandwidth, path length and channel conditions. Numerical results indicate that the proposed routing approach significantly outperforms other approaches in Fractional Reward Loss, network utilization and average end-to-end path delay.     

Wireless Regional Area Networks and Cognitive Radio(1)

1 Wireless Regional Area Networks (WRANs) and IEEE802.22 The advent of information era has been followed by all of the more extensive application of wireless services and devices, such asmobile communications, radio broadcast, and television. All these are exhausting spectrum resource andmaking it more precious than land andmineralresources. Nowadays,transmitters and receivers forcommunication systems needcertification from government to enter acommunication network. Therefore, thereare b…     

Achieving Max–Min lifetime and fairness with rate allocation for data aggregation in sensor networks

We consider the rate allocation problem for data aggregation in wireless sensor networks with two objectives: (1) maximizing the minimum (Max–Min) lifetime of an aggregation cluster and (2) achieving fairness among all data sources. The two objectives are generally correlated with each other and usually, they cannot be maximized simultaneously. We adopt a lexicographic method to solve this multi-objective programming problem. First, we recursively induce the Max–Min lifetime for the aggregation cluster. Under the given Max–Min lifetime, we then formulate the problem of maximizing fairness as a convex optimization problem, and derive the optimal rate allocation strategy by iterations. We also present low-complexity algorithms that an aggregation cluster can use to determine the Max–Min network lifetime and the fair rate allocation. Our simulation results validate our analytical results and illustrate the effectiveness of the approach.     

Performance Analysis and Optimal Power Allocation for Space–Time and Amplify-and-Forward Cooperative System

In this paper, we consider a space?Ctime and amplify-and-forward (ST-AF) cooperative system which consists of two-antenna source, single-antenna relay and destination. Source transmits Alamouti space?Ctime coding symbols to destination with cooperation of relay which adopts AF strategy. Closed-form symbol error rate (SER) is derived for the ST-AF system with PSK signals. Moreover, a SER approximation is developed to show the asymptotic performance of the ST-AF cooperative system in medium and high SNR regimes. For comparison, the SER approximation of another cooperative space?Ctime coding (C-STC) scheme is also derived. Theoretical analysis shows that the ST-AF can obtain more diversity gain and achieve higher diversity order than C-STC. Statistical optimal power allocation (OPA) algorithm for the ST-AF cooperative system is presented based on the SER performance. It turns out the OPA only depends on the channel links related to the relay, not depend on the direct link between source and destination. Finally, numerical simulations validate the theoretical analysis.     

Joint Relaying Selection and Power Allocation Algorithms for Cooperative Cellular System

1IntroductionWireless communications have rapidly evolved in therecent decades[1]. An architecture based on introducingcooperative relayingtechnologiesintothe cellular infras-tructure[2 ~5],seems a solution which addresses futuretoughened requirements with respect to particular datarate and range by alleviating some of the shortcomingsof today s cellular concept .Repeateris asi mple coopera-tive relaying scheme with low complexity[6 ~7], whichcan be the Non-Regenerative Relaying Station (NR…     

Distributed algorithms for lifetime maximization in sensor networks via Min–Max spanning subgraphs

We consider the problem of static transmission-power assignment for lifetime maximization of a wireless sensor network with stationary nodes operating in a data-gathering scenario. Using a graph-theoretic approach, we propose two distributed algorithms, MLS and BSpan, that construct spanning trees with minimum maximum (minmax) edge cost. MLS is based on computation of minmax-cost paths from a reference node, while BSpan performs a binary search over the range of power levels and exploits the wireless broadcast advantage. We also present a simple distributed method for pruning a graph to its Relative Neighborhood Graph, which reduces the worst-case message complexity of MLS under natural assumptions on the path-loss. In our network simulations both MLS and BSpan significantly outperform the recently proposed Distributed Min–Max Tree algorithm in terms of number of messages required.     

Joint Beamforming and Time Switching Designs for Energy-Constrained Cognitive Two-Way Relay Networks

In this paper, we investigate a joint beamforming and time switching(TS) design for an energy-constrained cognitive two-way relay(TWR) network. In the network, the energy-constrained secondary user(SU) relay employs TS protocol to harvest energy from the signals sent by the circuit-powered primary user(PU) transmitter, and then exploits the harvested energy to perform information forwarding. Our aim is to maximize the sum rate of SUs under the constraints of the data rate of PU, the energy harvesting and the transmit power of the SU relay. To determine the beamforming matrix and TS ratio, we decouple the original non-convex problem into two subproblems which can be solved by semidefinite relaxation and successive convex optimization methods. Furthermore, we derive closed form expressions of the optimal solutions for each subproblem, which facilitates the design of a suboptimal iterative algorithm to handle the original sum rate maximization problem. Simulation results are presented to illustrate the effectiveness and superior performance of the proposed joint design against other conventional schemes in the literature.     

Radio resource management for LTE-A relay-enhanced cells with spatial reuse and max–min fairness

One of the major issues in LTE-Advanced (LTE-A) systems is the poor capacity at the cell edge. This is mainly due to the interference experienced by the users as a result of the aggressive frequency reuse usually implemented. Relaying offers an attractive solution for this problem by offering better links than those with the eNodeB (eNB) for the terminals suffering from high path loss or high interference. However, adding relays complicates the resource allocation problem at the eNB and therefore the need for more efficient schemes arises. This is also aggravated by the reuse of resource blocks (RBs) by the relays to fully exploit the scarce spectrum, which, in turn, leads to intra-cell interference. In this paper, we study the joint power and resource allocation problem in LTE-A relay-enhanced cells that exploit spatial reuse. To guarantee fairness among users, a max–min fair optimization objective is used. This complex problem is solved using coordinate ascent and the difference of two convex functions (DC) programming techniques and the proposed scheme indeed converges to a local-optimum quickly. This is shown to be a satisfactory solution according to the simulation results that indicate an almost sevenfold increase in the 10th percentile capacity when compared to previously proposed solutions.     

Joint Downlink Scheduling and Radio Resource Allocation for User-Individual QoS in Adaptive OFDMA Wireless Communication Systems

1Introduction Futurewirelessandmobilecommunicationsystems areexpectedtoofferhigherdatarates,tosupporta largenumberofsubscribersandtoensurethefulfillment ofQualityofService(QoS)requirements,giventhe limitedavailabilityoffrequencyspectrumandtimevary ingchan…     

Spectrum Sensing in Cognitive Radio Using Actor–Critic Neural Network with Krill Herd-Whale Optimization Algorithm

Wireless Personal Communications - Spectrum sensing is the active research area in the Cognitive radio networks that initiates the effective data sharing between the licensed and the unlicensed...     

Cognitive Radio – A Current Snapshot and Some Thoughts on Commercialization for Future Cellular Systems

Cognitive Radio (CR) has received tremendous interest during the past decade from almost all research disciplines in wireless communications. Meanwhile, companies across the world in the value chain are showing more and more interest in CR. This is due to the expected significant scarcity of spectrum caused by data-consuming modern smartphones or similar mobile devices. However, partly conflicting interests and severe technical challenges remain for a successful commercialization of CR ideas, in particular for Long-Term Evolution (LTE) cellular systems. The aims of this survey are as follows: 1) we try to limit the various physical parameters (e.g. the carrier frequency range, the cell size) being relevant for cognitive cellular systems either in qualitative or in quantitative terms, 2) a conceptual approach for a performance bound being of practical relevance will be pointed out, 3) different players in the value chain of cellular systems and potential conflict of interests will be discussed, 4) the technical state-of-the-art CR and the remaining major challenges will be highlighted, 5) a current snapshot about the quickly evolving area of regulation and standardization will be provided. Finally, some products, services and prototypes for CR will be presented.     

Max–min utility fair flow management for networks with route diversity

A regional central manager is employed to set aside, for the regional (or back-bone) network that it manages, for each flow class, communications capacity resources for a specific future time horizon. In the context of such a traffic management operation, a longer temporal scale is involved in controlling the admission and distribution of flows across the network. For management scal-ability purposes, flows are aggregated into flow classes. Furthermore, we consider a network operation under which multiple simultaneously activated routes are employed, across possibly distinct segments, to distribute traffic between identified source–destination pairs. We aim to ensure that the utility assigned to each class is as high as feasibly possible while striving to raise the utility gained by all classes in a max–min fair manner. In doing so, we incorporate the communications capacity constraints that are imposed by the underlying hybrid of directional and/or multiple-access wireline and wireless communications media employed across the network system. We develop and present in this paper an optimal algorithm for solving such a traffic management problem. It yields multi-utility-based max–min fair distributions of flow rates, per each class, across the specified multitude of simultaneously activated multi-segment routes. To guarantee that admitted flows are granted their desired capacity resources (and targeted corresponding utility levels), the selection of optimal flow distributions across the network routes is combined with the use of a flow admission control scheme that serves to optimally limit the aggregate rate of flows admitted for each flow class. As illustrative examples, we demonstrate the effectiveness of our solution in comparing its performance with that obtained under the use of a traffic regulation scheme that is not overlaid with a traffic management mechanism that serves to set aside resources for the support of flow classes. We also illustrate the use of our optimal algorithm for determining the optimal placement of unmanned aerial vehicle platforms that serve to supplement a terrestrial transport segment with a space-based one. Copyright © 2010 John Wiley & Sons, Ltd.     

An implementation of Min–Max optimization for multipath SCTP through bandwidth estimation based resource pooling technique

Multipath transport protocols like Stream Control Transmission Protocol (SCTP) and Multipath TCP (MPTCP) have been introduced in the past as alternatives to traditional single path transport protocols like TCP and UDP. Various approaches to divide the flow on multiple paths have also been proposed in the literature. In this work, we show that the bandwidth estimation based resource pooling (BERP) congestion control algorithm is a practical implementation of the Min–Max optimization approach for flow division and verify this through ns-2 based simulations.     

Quadrature ���� Modulators for Cognitive Radio��I/Q Imbalance Analysis and Complex Multiband Principle

This article discusses the applicability of quadrature ΣΔ modulator (QΣΔM) based analog-to-digital (A/D) conversion in cognitive radio (CR) receivers. First, unavoidable in-phase/quadrature (I/Q) mismatch effects, limiting the dynamic range, are analyzed in closed-form in the case of a first-order modulator. In addition, using the derived analytical converter model, it is shown that notching the signal transfer function (STF) of the modulator at the mirror frequencies of the desired signals will effectively cancel the I/Q imbalance induced mirror-frequency interference in case of the modulator feedback mismatch. In practice, such STF design is easy to implement within the existing converter circuitry, as will be demonstrated in this article. The latter part of the article proposes a novel complex multiband QΣΔM scheme, particularly aimed for the CR receivers. This multiband scheme allows parallel reception of scattered frequency chunks in the CR context and is stemming from the additional degrees of freedom in noise transfer function (NTF) design, provided by the QΣΔM principle. Here multiple noise shaping notches on distinct frequencies are effectively realized through proper design of complex NTF. The modulator structure also allows flexible reconfigurability of the notches with straightforward parameterization of the modulator transfer functions. When combined with the above mirror-frequency rejecting STF design, the concept is demonstrated and proved effective and robust against I/Q imbalances using practical radio signal simulations in realistic received signal conditions.