The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Jens Zander - One of the best experts on this subject based on the ideXlab platform.
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Constrained Power control
Wireless Personal Communications, 1994Co-Authors: Sukeshini A Grandhi, Jens Zander, Roy YatesAbstract:High system capacities can be achieved by controlling the Transmitter Power in multiuser radio systems. Power control with no constraint on the maximum Power level has been studied extensively in earlier work [1–18]. Transmitter Power is at a premium in radio systems such as cellular systems and PCS. There is a limit on the maximum Transmitter Power especially at the terminals (e.g. mobile units and handsets) since the Power comes from a battery. In this paper we study Power control that maximizes the minimum carrier to interference ratio (CIR), with a constraint on the maximum Power. The optimal Power vector solution lies on the boundary of the constrained Power vector set and achieves a balance in the CIR's. Results indicate that the constraints do not induce any stability problems. A distributed scheme with favourable convergence properties and close to optimum performance is presented. Simulation results show that the algorithm tries to maximize the number of terminals served with CIR greater than or equal to the target CIR, while conserving Power.
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Transmitter Power control for co channel interference management in cellular radio systems
4th WINLAB Workshop on Third Generation Wireless Networks, 1994Co-Authors: Jens ZanderAbstract:Transmitter Power control is a necessity to combat “near-far” problems in radio systems using receivers with limited “dynamic range” (such as conventional DSCDMA systems). Transmitter Power control, however, can also be used to control cochannel interference, i.e. interference from other users using the same channel (code or time slot). For this purpose, it has been shown that the optimum Transmitter Power configuration is found by solving an eigenvalue problem. The paper reviews some recent results in this area. The basic models as well as the concepts of achievable C/I, up/down-link equivalence and C/Ibalancing are introduced. Both the interference limited (noise-less) case as well as models including thermal noise are treated. Results show that substantial improvements in system capacity can be achieved, particulary in conjunction with Dynamic Channel Allocation. The optimum Power control schemes are shown to be robust against implementational shortcomings.
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Comment on "Performance of optimum Transmitter Power control in cellular radio systems"
IEEE Transactions on Vehicular Technology, 1994Co-Authors: Jens Zander, M. FrodighAbstract:In the original paper, it was conjectured that the system performance in the up-link and down-link in a cellular radio system under optimum Transmitter Power control should be statistically similar. In this comment we show that the achievable signal-to-interference ratios in the up- and down-links are, in fact, identical at every instant. >
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Transmitter Power Control for Co-Channel Interference Management in Cellular Radio Systems - An Overview and some Recent Results
1993Co-Authors: Jens ZanderAbstract:Transmitter Power Control for Co-Channel Interference Management in Cellular Radio Systems - An Overview and some Recent Results
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Performance of optimum Transmitter Power control in cellular radio systems
IEEE Transactions on Vehicular Technology, 1992Co-Authors: Jens ZanderAbstract:Most cellular radio systems provide for the use of Transmitter Power control to reduce cochannel interference for a given channel allocation. Efficient interference management aims at achieving acceptable carrier-to-interference (C/I) ratios in all active communication links in the system. Such schemes for the control of cochannel interference are investigated. The effect of adjacent channel interference is neglected. As a performance measure, the interference (outage) probability is used, i.e., the probability that a randomly chosen link is subject to excessive interference. In order to derive upper performance bounds for Transmitter Power control schemes, algorithms that are optimum in the sense that the interference probability is minimized are suggested. Numerical results indicate that these upper bounds exceed the performance of conventional systems by an order of magnitude regarding interference suppression and by a factor of 3 to 4 regarding the system capacity. The structure of the optimum algorithm shows that efficient Power control and dynamic channel assignment algorithms are closely related.
David J. Goodman - One of the best experts on this subject based on the ideXlab platform.
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ICASSP (3) - Minimize the total Power consumption for multiuser video transmission over CDMA wireless network: a two-step approach
Proceedings. (ICASSP '05). IEEE International Conference on Acoustics Speech and Signal Processing 2005., 1Co-Authors: Yao Wang, Elza Erkip, David J. GoodmanAbstract:We consider a CDMA cell with multiple terminals transmitting video signals. We minimize the sum of signal processing and Transmitter Power while the received quality at each terminal is guaranteed. The system parameters to be adjusted include video coding bit rate, video compression complexity and Transmitter Power. Instead of full search in the space of {bit rate, complexity, Transmitter Power} for all users, we design a two-step fast algorithm to reduce the computation burden in the base station. In our algorithm, the search in the base station is over the space of complexity only. Our results indicate that, for the same class of video users, the one who is closest to the base station compresses at least complexity. This is used to further reduce the computation required by our algorithm.
Norman S. Kopeika - One of the best experts on this subject based on the ideXlab platform.
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beam width and Transmitter Power adaptive to tracking system performance for free space optical communication
Applied Optics, 1997Co-Authors: Shlomi Arnon, Stanly Rotman, Norman S. KopeikaAbstract:The basic free-space optical communication system includes at least two satellites. To communicate between them, the Transmitter satellite must track the beacon of the receiver satellite and point the information optical beam in its direction. Optical tracking and pointing systems for free space suffer during tracking from high-amplitude vibration because of background radiation from interstellar objects such as the Sun, Moon, Earth, and stars in the tracking field of view or the mechanical impact from satellite internal and external sources. The vibrations of beam pointing increase the bit error rate and jam communication between the two satellites. One way to overcome this problem is to increase the satellite receiver beacon Power. However, this solution requires increased Power consumption and weight, both of which are disadvantageous in satellite development. Considering these facts, we derive a mathematical model of a communication system that adapts optimally the Transmitter beam width and the transmitted Power to the tracking system performance. Based on this model, we investigate the performance of a communication system with discrete element optical phased array Transmitter telescope gain. An example for a practical communication system between a Low Earth Orbit Satellite and a Geostationary Earth Orbit Satellite is presented. From the results of this research it can be seen that a four-element adaptive Transmitter telescope is sufficient to compensate for vibration amplitude doubling. The benefits of the proposed model are less required Transmitter Power and improved communication system performance.
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Beamwidth and Transmitter Power adaptive to tracking-system performance for free-space optical communication
Space Sciencecraft Control and Tracking in the New Millennium, 1996Co-Authors: Arnon Shlomi, Stanley R. Rotman, Norman S. KopeikaAbstract:The basic free space optical communication system includes at least two satellites. In order to communicate between them, the Transmitter satellite must track the beacon of the receiver satellite and point the information optical beam in its direction. Optical tracking and pointing systems for free space suffer during tracking from high amplitude vibration due to background radiation from interstellar objects such as sun, moon, earth and stars in the tracking field of view or mechanical impact from satellite internal and external sources. The vibrations of the beam pointing increase the bit error rate and jam communication between the two satellites. One way to overcome this problem is to increase the satellite receiver beacon Power. However this solution requires increased Power consumption and weight. These two factors are disadvantageous in satellite development. Considering these facts, we derive a mathematical model of a communication system that adapts optimally the Transmitter beamwidth and the transmitted Power to the tracking system performance. Based on this model, we investigate the performance of a communication system with discrete level optical phased array Transmitter telescope gain. An example for a practical communication system between a low earth orbit satellite (LEO) and a geostationary earth orbit satellite (GEO) is presented. From the results of this work it is seen that a four level adaptive Transmitter telescope is sufficient to compensate for vibration amplitude doubling. The benefits of the proposed model are less required Transmitter Power and improved communication system performance.
C.w. Bostian - One of the best experts on this subject based on the ideXlab platform.
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Throughput optimization and Transmitter Power saving (totps) algorithm and extended totps (etotps) algorithm for ieee 802.11 links
2006Co-Authors: C.w. BostianAbstract:The IEEE 802.11 wireless local area network (WLAN) standard supports multiple transmission modes. However, the higher mandatory data rate mode does not necessarily yield higher throughput. This research started from the relationship between the link throughput and the channel's carrier-to-noise (C/N) ratio. Two algorithms are proposed, a throughput optimization and Transmitter Power saving (TOTPS) algorithm and an extended throughput optimization and Transmitter Power saving (ETOTPS) algorithm, based on the knowledge of the C/N ratio at the receiver. In particular, we take the approach of adjusting link parameters like Transmitter Power and transmission mode to achieve the maximum throughput at different C/N values. Since the TOTPS algorithm tends to reduce the Transmitter Power without degrading the link throughput, Transmitter Power can be saved. This not only prolongs battery life, which is critical in ad hoc wireless networks, but also reduces the potential interference to neighboring wireless network systems. The ETOTPS algorithm, on the other hand, aims for higher throughput by trading in more Transmitter Power. This is particularly desired for high-speed data transfer in an emergency situation. Both algorithms are developed to be applied to IEEE 802.11b, IEEE 802.11a and IEEE 802.11g links.
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WCNC - A throughput optimization and Transmitter Power saving algorithm for IEEE 802.11b links
IEEE Wireless Communications and Networking Conference 2005, 1Co-Authors: C.w. BostianAbstract:The IEEE 802.11 wireless local area network (WLAN) standard supports multiple transmission modes. However, the higher mandatory data rate mode does not necessarily yield higher throughput. We show the relationship between the link throughput and the channel's carrier-to-noise (C/N) ratio. We propose a throughput optimization and Transmitter Power saving (TOTPS) algorithm based on the knowledge of the C/N ratio at the receiver. In particular, we take the approach of adjusting link parameters, like Transmitter Power and transmission mode, to achieve the maximum throughput at different C/N values. Since this algorithm tends to reduce the Transmitter Power without degrading the link throughput, Transmitter Power can be saved. This not only prolongs battery life, which is critical in ad hoc wireless networks, but also reduces the potential interference to neighboring wireless network systems. This algorithm can also be applied to IEEE 802.11a and IEEE 802.11g links.
Franco Mazzenga - One of the best experts on this subject based on the ideXlab platform.
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Capacity analysis of UWB systems with Transmitter Power constraints
2005 IEEE 61st Vehicular Technology Conference, 1Co-Authors: Romeo Giuliano, Franco MazzengaAbstract:Ultra wide bandwidth (UWB) wireless technology plays a key role in future beyond third generation systems guaranteeing very high bit rates availability, low Power consumption, low costs and location capabilities. The peaceful acceptance of the UWB technology worldwide is mainly related to coexistence issues with other existing (and future) narrowband and wideband systems sharing the spectrum with UWB. This led regulatory bodies to impose restrictions on UWB transmissions thus implicitly limiting the UWB system capacity intended as the number of users that can be served for a specified outage probability. In this work we provide a methodology to evaluate the UWB system capacity under the Federal Communications Commission (FCC) constraints. UWB networks with Power controlled UWB devices are considered. The concept of irreducible outage probability is introduced. Results can be used to analyze the performance of a given network topology and/or to provide useful design hints for an UWB indoor system with devices communicating in accordance to a clustered master-slave network topology.
