Energy-delay tradeoffs in impulse-based ultra-wideband body area networks with noncoherent receivers

© 2014 IEEE. In this paper we address the problem of rate scheduling in the Impulse Radio (IR) ultra-wideband (UWB) wireless body area networks (WBANs) and the minimum energy required to stabilize the queuing system. Targeting low complexity WBAN applications, we assume noncoherent receivers based on energy detection and autocorrelation for all nodes. The coordinating node can minimize the average energy consumption of the system and achieve the queue backlog stability of the sensor nodes by controlling the number of pulses per symbol. We first illustrate the necessary and sufficient conditions of network stability for a multi-mode UWB system and then propose a feasible rate scheduling algorithm based on the Lyapunov optimization theory. The scheduling algorithm uses the instantaneous channel state information and the length of the local queue of all sensor nodes and can approach the optimal energy-delay tradeoff of the network. We apply our theoretical framework to the IR-UWB physical layer of the IEEE 802.15.6 standard and extract the optimal physical layer modes that can achieve the desired energy-delay tradeoff

Random Sums of Random Variables and Vectors

status: publishe

Long-range dependence of Markov renewal processes

This paper examines long-range dependence (LRD) and asymptotic properties of Markov renewal processes generalizing results of Daley for renewal processes. The Hurst index and discrepancy function, which is the difference between the expected number of arrivals in (0, t] given a point at 0 and the number of arrivals in (0, t] in the time stationary version, are examined in terms of the moment index. The moment index is the supremum of the set of r > 0 such that the rth moment of the first return time to a state is finite, employing the solidarity results of Sgibnev. The results are derived for irreducible, regular Markov renewal processes on countable state spaces. The paper also derives conditions to determine the moment index of the first return times in terms of the Markov renewal kernel distribution functions of the process.17 page(s

The Difference between the product and the convolution product of distribution functions in Rn

18 page(s

A novel genetic-fuzzy power controller with feedback for interference mitigation in Wireless Body Area Networks

Wireless Body Area Networks (WBANs) are an emerging technology for short-range wireless communication inside, on or around the human body, mainly for medical applications. A WBAN's scarcest resource is power. Due to the mobility of WBANs as well as the limited number of available channels, signals of neighboring WBANs can cause interference that may severely degrade the reliability and performance of the system and lead to more power consumption. In this paper, we propose a fast converging fuzzy power controller (FPC) with feedback whose inputs are the current interference power level, Signal-to-Interference-and-Noise (SINR) and the current transmission power level to provide interference mitigation in WBANs. We utilize a genetic algorithm to design and optimize the FPC to simultaneously maximize capacity, minimize power consumption and minimize convergence time. We compare the performance of the proposed approach with two game-theory power control approaches. Our simulation results show that compared to these other approaches, the proposed FPC provides a substantial saving in power consumption as well as quick convergence that is independent of the number of nodes in the system, while sacrificing only a small amount of capacity. © 2011 IEEE

Random Sums of Random Variables and Vectors

Let fX;Xi; i = 1; 2; :::g denote independent positive random variables having a common distribution function F(x) and, independent of X, let N denote an integer valued random variable. Using S(0) = 0 and S(n) = S(n ?? 1) + Xn, the random sum S(N) has distribution function G(x) = 1Xi=0 P(N = i)P(S(i) _ x) and tail distribution G(x) = 1 ?? G(x). In which case, we say that the distribution function G is subordinated to F with subordinator N. Under suitable conditions, it can be proved that G(x) s E(N)F(x) as x ! 1. In this paper, we extend some of the existing results. In the place of i.i.d. random variables, we use variables that are independent or variables that are asymptotically in- dependent. We also consider multivariate subordinated distribution functions.Subexponential distributions; regular variation; O-regular variation; subordination

Adaptive Hybrid ARQ (A-HARQ) for Ultra-Reliable Communication in 5G

© 2017 IEEE. In this paper, we address the need for motivating applications, such as mission critical industrial control and medical applications, to operate under the Ultra-Reliable Communication (URC) mode in the future 5th Generation (5G) cellular wireless networks, while also under strict Quality of Service (QoS) constraints such as ultra-low latency. Reliability has been shown to improve by using Hybrid Automatic Repeat reQuest (HARQ) for the retransmission (RTX) of erroneous packets during poor channel conditions. However, this can increase the delay to unacceptable levels if more than 1 RTX is required. Thus, an Adaptive HARQ (A-HARQ) scheme is proposed, where RTX are done on better quality sub-bands, with resources dynamically allocated based on Channel Quality Indicator (CQI) reports. A-HARQ also increases the number of RTX within a 4 ms time period, by utilising Transmission Time Interval (TTI) bundling to decrease the delay incurred from many RTX. A performance analysis is conducted, where A-HARQ was shown to have about 35% lower delay than the legacy HARQ, with a slight decrease in throughput, for low Signal-to-Noise (SNR) values

Spectrum sharing in femtocell based networks using an equal priority power control game

© 2017 IEEE. In order to keep pace with the recent proliferation of wireless services and mobile applications, efficient and flexible radio spectrum utilization needs to be ensured in next-generation mobile networks. In this regard, we present a game-Theoretic spectrum-sharing scheme, by considering coexistence of a set of femtocells, belonging to multiple networks, in a coverage area where all cells have an equal priority of accessing the spectrum. We formulate a non-cooperative transmit-power-control game, in which all the femtocells share the spectrum by adjusting their transmit powers according to the interference, until the transmit power is stabilized. We prove that a Nash equilibrium exists for the proposed non-cooperative game, verify that it is unique and highlight the role of specific game parameters in this regard. A novel dual-mode solution is proposed for implementation of the game, which ensures that an equilibrium point can be reached having minimum coordination among the network elements. Finally, we present simulation results to show that the game converges to a Nash equilibrium and provide a throughput performance analysis

Dynamic power control in wireless body area networks using reinforcement learning with approximation

A Wireless Body Area Network (WBAN) is made up of multiple tiny physiological sensors implanted in/on the human body with each sensor equipped with a wireless transceiver that communicates to a coordinator in a star topology. Energy is the scarcest resource in WBANs. Power control mechanisms to achieve a certain level of utility while using as little power for transmission as possible can play an important role in reducing energy consumption in such very energy-constrained networks. In this paper, we propose a novel power controller to mitigate internetwork interference in WBANs and increase the maximum achievable throughput with the minimum energy consumption. The proposed power controller employs reinforcement learning with approximation to learn from the environment and improve its performance. We compare the performance of the proposed controller to two other power controllers, one based on game theory and the other one based on fuzzy logic. Simulation results show that compared to the other two approaches, RLPC provides a substantial saving in energy consumption per bit, with a substantial increase in network lifetime. © 2011 IEEE