Results 21  30
of
116
Distributed power and admission control for timevarying wireless networks
 in Proc. IEEE International Symposium on Information Theory (ISIT
, 2004
"... Abstract — This paper presents new distributed power and admission control algorithms for adhoc wireless networks in random channel environments. Previous work in this area has focused on distributed control for adhoc networks with fixed channels. We show that the algorithms resulting from such fo ..."
Abstract

Cited by 19 (0 self)
 Add to MetaCart
(Show Context)
Abstract — This paper presents new distributed power and admission control algorithms for adhoc wireless networks in random channel environments. Previous work in this area has focused on distributed control for adhoc networks with fixed channels. We show that the algorithms resulting from such formulations do not accurately capture the dynamics of a timevarying channel. The performance of the network in terms of power consumption and generated interference, can be severely degraded when power and admission control algorithms that are designed for deterministic channels are applied to random channels. In particular, some wellknown optimality results for deterministic channels no longer hold. In order to address these problems we propose a new criterion for power optimality in adhoc wireless networks. We then show that the optimal power allocation for this new criterion can be found through an appropriate stochastic approximation algorithm. We also present a modified version of this algorithm for tracking nonstationary equilibria, which allows us to perform admission control. Ultimately, the iterations of the stochastic approximation algorithms can be decoupled to form fully distributed online power and admission control algorithms for adhoc wireless networks with timevarying channels. I.
Interference Avoidance for Wireless Systems
 In Vehicular Technology Conference
, 1999
"... Motivated by the emergence of programmable radios, we seek to understand a new class of communication system where pairs of transmitters and receivers can adapt their modulation/demodulation method in the presence of interference to achieve better performance. Using signal to interference ratio as a ..."
Abstract

Cited by 18 (10 self)
 Add to MetaCart
Motivated by the emergence of programmable radios, we seek to understand a new class of communication system where pairs of transmitters and receivers can adapt their modulation/demodulation method in the presence of interference to achieve better performance. Using signal to interference ratio as a metric and a general signal space approach, we present a class of iterative distributed algorithms for synchronous systems which results in an ensemble of optimal waveforms for multiple users connected to a common receiver (or colocated independent receivers). That is, the waveform ensemble meets the Welch Bound with equality and therefore achieves minimum average interference over the ensemble of signature waveforms. We describe fixed points for a number of scenarios. 1 Introduction Wireless system designers have always had to contend with interference from both natural sources and other users of the medium. Thus, the classical wireless communications design cycle has consisted of measu...
Power Control by Interference Prediction for Broadband Wireless Packet Networks
 IEEE Trans. on Wireless Communications
, 2002
"... A Kalmanfilter method for power control is proposed for broadband, packetswitched TDMA wireless networks. By exploiting the temporal correlation of cochannel interference, a Kalman filter is used to predict future interference power. Based on the predicted interference and estimated path gain bet ..."
Abstract

Cited by 18 (3 self)
 Add to MetaCart
(Show Context)
A Kalmanfilter method for power control is proposed for broadband, packetswitched TDMA wireless networks. By exploiting the temporal correlation of cochannel interference, a Kalman filter is used to predict future interference power. Based on the predicted interference and estimated path gain between the transmitter and receiver, transmission power is determined to achieve a desired signaltointerferenceplusnoise ratio (SINR). A condition to ensure power stability in the packetswitched environment is established and proven for a special case of the Kalmanfilter method. The condition generalizes the existing one for a fixed pathgain matrix, as for circuitswitched networks. Performance results reveal that the Kalmanfilter method for power control provides a significant performance improvement. Specifically, when messages consist of 10 packets on average, the 90th and 95th percentile of the SINR by the new method are 3.79 and 5.46 dB above those when no power control is in use, and lie just 0.96 and 1.14 dB below the upperbound performance of the optimal power control, respectively, in a system with 4sector cells and an interleaved frequency assignment of a reuse factor of 2/8. In addition, the new method performs noticeably better than the deltamodulation method and a simple scheme that uses the last measurement as predicted interference power. In an example of 8PSK modulation and average message length of 20 packets, the SINR performance gain by the new method improves the network throughput by about 150 % and 70%, relative to no power control and the simple scheme, respectively.
Distributed and nonautonomous power control through distributed convex optimization
 IEEE INFOCOM
"... Abstract — We consider the uplink power control problem where mobile users in different cells are communicating with their base stations. We formulate the power control problem as the minimization of a sum of convex functions. Each component function depends on the channel coefficients from all the ..."
Abstract

Cited by 17 (7 self)
 Add to MetaCart
(Show Context)
Abstract — We consider the uplink power control problem where mobile users in different cells are communicating with their base stations. We formulate the power control problem as the minimization of a sum of convex functions. Each component function depends on the channel coefficients from all the mobile users to a specific base station and is assumed to be known only to that base station (only CSIR). We then view the power control problem as a distributed optimization problem that is to be solved by the base stations and propose convergent, distributed and iterative power control algorithms. These algorithms require each base station to communicate with the base stations in its neighboring cells in each iteration and are hence nonautonomous. Since the base stations are connected through a wired backbone the communication overhead is not an issue. The convergence of the algorithms is shown theoretically and also verified through numerical simulations. I.
A KalmanFilter Method for Power Control in Broadband Wireless Networks
"... A Kalmanfilter method for power control is proposed for broadband, packetswitched TDMA wireless networks. By observing the temporal correlation of cochannel interference when transmitters can send data contiguously, a Kalman filter is used to predict interfence power in the future. Based on the pr ..."
Abstract

Cited by 16 (9 self)
 Add to MetaCart
(Show Context)
A Kalmanfilter method for power control is proposed for broadband, packetswitched TDMA wireless networks. By observing the temporal correlation of cochannel interference when transmitters can send data contiguously, a Kalman filter is used to predict interfence power in the future. Based on the predicted interference and estimated path gain between the transmitter and receiver, transmission power is determined to achieve a desired signaltointerferenceplusnoise ratio (SINR). Performance results reveal that the Kalmanfilter method for power control provides a significant performance improvement. Specifically, when a message consists of 10 packets on average, the 90 and 95 percentile of the SINR by the new method are 3.94 and 5.53 dB above those when no power control is in use, and lie just 0.73 and 1.04dB below the upperbound performance of the optimal power control, respectively, in a system with 4sector cells and an interleaved frequency assignment of a reuse factor of 2/8 [WL98]. As a byproduct, these results show that the cell layout and assignment scheme combined with the new method for power control can be used to support highspeed data services.
Joint receiver and transmitter optimization for energyefficient CDMA communications
 IEEE J. Sel. Areas Commun., Special Issue on Multiuser Detection for Advanced Communications Systems and Networks
, 2008
"... iv ..."
(Show Context)
Crosslayer design for power efficiency and QoS provisioning in multihop wireless networks
 IEEE Trans. Wireless Commun
, 2006
"... Abstract — In recent years, it has become common consensus that independent consideration of communication layers often turns out to be inadequate in terms of providing the desired quality of service (QoS) and power efficiency in wireless networks. The need for a synergistic, crosslayer design fra ..."
Abstract

Cited by 14 (0 self)
 Add to MetaCart
(Show Context)
Abstract — In recent years, it has become common consensus that independent consideration of communication layers often turns out to be inadequate in terms of providing the desired quality of service (QoS) and power efficiency in wireless networks. The need for a synergistic, crosslayer design framework has already been identified. In that respect, our work constitutes an important step towards a better understanding of the crosslayer paradigm by simultaneously targeting both the power efficiency and the endtoend QoS in multihop wireless networks. More specifically, we address the joint problem of power control and scheduling with the objective of minimizing the total transmit power subject to the endtoend bandwidth guarantees and the bit error rate constraints of each communication session. After identifying the inherent difficulty of the problem, we propose two classes of heuristic algorithms that rely on graph theory principles as well as on derived metrics such as effective interference. The first heuristic follows a topdown design strategy by solving the schedule feasibility problem as the initial step and then targeting the total power efficiency. On the other hand, the second heuristic follows a bottomup approach that schedules one wireless link at a time by greedily filling up the available time slots. The simulation results reveal valuable insights about the performance of each strategy. The topdown design strategy turns out to address power efficiency issues better, whereas the bottomup design strategy with a properly selected cost function for link scheduling shows better performance in finding a feasible solution, namely one that satisfies both the QoS and the transmit power constraints. Our results also illustrate the impact of routing decisions on the feasibility and the power efficiency of multihop wireless networks through employing different routing criteria in the experiments. Index Terms — Crosslayering, energy efficiency, multihop ad hoc networks, power control, QoS, scheduling. I.
Fast stochastic power control algorithms for nonlinear multiuser receivers,”
 IEEE Trans. Commun.,
, 2002
"... ..."
Variance Minimization Stochastic Power Control in CDMA Systems
 in CDMA Systems”, Proceedings of IEEE Conference on Communications 2002
, 2002
"... In this paper, a stochastic uplink power control problem is considered for CDMA systems. A distributed algorithm is proposed based on stochastic linear quadratic optimal control theory assuming SIR measurements contain white noise. The proposed scheme minimize the sum of the variance of mobile' ..."
Abstract

Cited by 13 (2 self)
 Add to MetaCart
In this paper, a stochastic uplink power control problem is considered for CDMA systems. A distributed algorithm is proposed based on stochastic linear quadratic optimal control theory assuming SIR measurements contain white noise. The proposed scheme minimize the sum of the variance of mobile's transmission power and the variance of SIR error, with guaranteed stability. Simulation results indicate the effectiveness of the proposed algorithm.
Stochastic power control for timevarying longterm fading wireless channels
 in Proceedings of the American Control Conference
"... The power control (PC) of wireless networks is formulated using a stochastic optimal control framework. The performance of stochastic optimal power control for timevarying long term fading channels, in which the evolution of the dynamical channel is described by a stochastic differential equations ..."
Abstract

Cited by 12 (6 self)
 Add to MetaCart
(Show Context)
The power control (PC) of wireless networks is formulated using a stochastic optimal control framework. The performance of stochastic optimal power control for timevarying long term fading channels, in which the evolution of the dynamical channel is described by a stochastic differential equations (SDE) is determined. Unlike the common random or free space static models usually encountered in the literature, the SDE essentially capture the spatialtemporal variations of lognormal fading wireless channels as well as the randomness. The solution of the stochastic optimal control is obtained through pathwise optimization, which is solved by linear programming using predictable power control strategies (PPCS). The algorithm can be implemented using an iterative numerical scheme. The performance measure of the algorithm is interference or outage probability. Simulation results show that the performance of PPCS using stochastic models outperforms the performance of PC based on static models. The PPCS algorithm can be used as long as the channel model does not change significantly. If predictable control strategies do not hold, it is shown that the proposed power control problem reduces to particular convex optimizations.