Channel allocation schemes

About: Channel allocation schemes is a research topic. Over the lifetime, 10656 publications have been published within this topic receiving 182117 citations.

HetNets with cognitive small cells: user offloading and distributed channel access techniques

Abstract: Heterogeneous networks, consisting of macrocells overlaid with small cells (eg, femtocells, picocells, microcells) provide a fast, flexible, cost-efficient, and fine-tuned design and expansion for existing cellular wireless networks to satisfy the ever increasing demand for network capacity In HetNets, small cells serve as offloading spots in the radio access network to offload users and their associated traffic from congested macrocells However, due to their large-scale deployment in random locations, limited transmit power, and the lack of complete coordination, the coexistence and efficient operation of small cells is very challenging In this article, we discuss the coexistence challenges posed to small cells and show that, with cognition capabilities (eg, achieved through spectrum sensing), small cells can overcome the posed challenges and efficiently coexist in a multitier cellular wireless network Then we discuss a statistical tool, stochastic geometry, to model and analyze heterogeneous cellular networks We give two examples where the stochastic geometry tools can be exploited to obtain insightful design guidelines First, we exploit stochastic geometry to evaluate the load of each network tier and study different offloading techniques used to control this load Second, we exploit stochastic geometry to maximize frequency reuse efficiency through spectrum sensing design for channel access and compare two channel access techniques based on spectrum sensing

Spectrum management in cognitive radio ad hoc networks

Abstract: The problem of spectrum scarcity and inefficiency in spectrum usage will be addressed by the newly emerging cognitive radio paradigm that allows radios to opportunistically transmit in the vacant portions of the spectrum already assigned to licensed users. For this, the ability for spectrum sensing, spectrum sharing, choosing the best spectrum among the available options, and dynamically adapting transmission parameters based on the activity of the licensed spectrum owners must be integrated within cognitive radio users. Specifically in cognitive radio ad hoc networks, distributed multihop architecture, node mobility, and spatio-temporal variance in spectrum availability are some of the key distinguishing factors. In this article the important features of CRAHNs are presented, along with the design approaches and research challenges that must be addressed. Spectrum management in CRAHNs comprises spectrum sensing, sharing, decision, and mobility. In this article each of these functions are described in detail from the viewpoint of multihop infra-structureless networks requiring cooperation among users.

Wireless channel allocation using an auction algorithm

Abstract: We develop a novel auction-based algorithm to allow users to fairly compete for a wireless fading channel. We use the second-price auction mechanism whereby user bids for the channel, during each time slot, based on the fade state of the channel, and the user that makes the highest bid wins use of the channel by paying the second highest bid. Under the assumption that each user has a limited budget for bidding, we show the existence of a Nash equilibrium strategy, and the Nash equilibrium leads to a unique allocation for certain channel state distribution, such as the exponential distribution and the uniform distribution over [0, 1]. For uniformly distributed channel state, we establish that the aggregate throughput received by the users using the Nash equilibrium strategy is at least 3/4 of what can be obtained using an optimal centralized allocation that does not take fairness into account. We also show that the Nash equilibrium strategy leads to an allocation that is Pareto optimal (i.e., it is impossible to make some users better off without making some other users worse off). Based on the Nash equilibrium strategies of the second-price auction with money constraint, we further propose a centralized opportunistic scheduler that does not suffer the shortcomings associated with the proportional fair scheduler.

BodyMAC: Energy efficient TDMA-based MAC protocol for Wireless Body Area Networks

Abstract: Wireless Body Area Networks (WBANs) enable placement of tiny biomedical sensors on or inside the human body to monitor vital body signs. The IEEE 802.15.6 task group is developing a standard to optimize WBAN performance by defining the physical layer (PHY) and media access control (MAC) layer specifications. In this paper an energy efficient MAC protocol (BodyMAC) is proposed. It uses flexible bandwidth allocation to improve node energy efficiency by reducing the possibility of packet collisions and by reducing radio transmission times, idle listening and control packets overhead. BodyMAC is based on a Downlink and Uplink scheme in which the Contention Free Part in the Uplink subframe is completely collision free. Three types of bandwidth allocation mechanisms allow for flexible and efficient data and control communications. An efficient Sleep Mode is introduced to reduce the idle listening duration, especially for low duty cycle nodes in the network. Simulation results show superior performance of BodyMAC compared to that of the IEEE 802.15.4 MAC.

Device-centric spectrum management

Abstract: Efficient spectrum allocation in open spectrum systems is a challenging problem, particularly for devices with constrained communication resources such as sensor and mobile ad hoc networks. We propose a device-centric spectrum management scheme with low communication costs, where users observe local interference patterns and act independently according to preset spectrum rules. We propose five rules that tradeoff performance with implementation complexity and communication costs, and derive a lower bound on each user's allocation based on these rules. Experimental results show that our proposed rule-based approach reduces communication costs from efficient collaborative approaches by a factor of 3-4 while providing good performance