| 1. |
- Andersin, Michael, et al.
(författare)
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Distributed Discrete Power Control in Cellular PCS
- 1998
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Ingår i: Wireless personal communications. - : Springer. - 0929-6212 .- 1572-834X. ; 6:3, s. 211-213
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Tidskriftsartikel (refereegranskat)abstract
- Transmitter power control has proven to be an efficient method to control cochannel interference in cellular PCS, and to increase bandwidth utilization. Power control can also improve channel quality, lower the power consumption, and facilitate network management functions such as mobile removals, hand-off and admission control. Most of the previous studies have assumed that the transmitter power level is controlled in a continuous domain, whereas in digitally power controlled systems, power levels are discrete. In this paper we study the transmitter power control problem using only a finite set of discrete power levels. The optimal discrete power vector is characterized, and a Distributed Discrete Power Control (DDPC) algorithm which converges to it, is presented. The impact of the power level grid on the outage probability is also investigated. A microcellular case study is used to evaluate the outage probabilities of the algorithms.<
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| 2. |
- Andersin, Michael, et al.
(författare)
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Gradual removals in cellular PCS with constrained power control and noise
- 1995
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Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. - 0780330021 ; , s. 56-60
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Konferensbidrag (refereegranskat)abstract
- In this paper we study the mobile removal problem in a cellular PCS network where transmitter powers are constrained and controlled by a distributed constrained power control (DCPC) algorithm. Due to transmitter mobility and random signal propagation, there are system states where not all transmitters can be supported, even under the optimal power control. Thus, some of them should be removed. It can be shown that finding the optimal removal set is an NP-complete problem, and therefore gives rise to heuristic algorithms. In this paper we study and compare among three classes of transmitter removal algorithms, one-by-one removals, multiple removals and power control with removals combined. All removal algorithms are compared with respect to their outage probabilities and their time to convergence to a steady state. The power control with removals combined algorithm emerges as the best approach with respect to both criteria.
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| 3. |
- Andersin, Michael, et al.
(författare)
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Gradual Removals in Cellular PCS with Constrained Power Control and Noise
- 1996
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Ingår i: Wireless networks. - : Kluwer Academic Publishers. - 1022-0038 .- 1572-8196. ; 2:1, s. 27-43
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we study the mobile removal problem in a cellular PCS network where transmitter powers are constrained and controlled by a Distributed Constrained Power Control (DCPC) algorithm. Receivers are subject to nonÂnegligible noise, and the DCPC attempts to bring each receiver's CIR above a given target. To evaluate feasibility and computational complexity, we assume a paradigm where radio bandwidth is scarce and interÂbase station connection is fast. We show that finding the optimal removal set is an NP-Complete problem, giving rise for heuristic algorithms. We study and compare among three classes of transmitter removal algorithms. Two classes consist of algorithms which are invoked only when reaching a stable power vector under DCPC. The third class consist of algorithms which combine transmitter removals with power control. These are One-by-one Removals, Multiple Removals, and Power Control with Removals Combined. In the class of power control with removals combined, we also consider a distributed algorithm which uses the same local information as DCPC does. All removal algorithms are compared with respect to their outage probabilities and their time to converge to a stable state. Comparisons are made in a hexagonal macro-cellular system, and in two metropolitan micro-cellular systems. The Power Control with Removals Combined algorithm emerges as practically the best approach with respect to both criteria.
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| 4. |
- Andersin, Michael, et al.
(författare)
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Soft Admission in Cellular PCS with Constrained Power Control and Noise
- 1995
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Ingår i: Proc 5th WINLAB Workshop on Third Generation Wireless Information Networks. ; , s. 287-320
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Konferensbidrag (refereegranskat)abstract
- We study the mobile admission control problem in a cellular PCS network where trans- mitter powers are constrained and controlled by a Distributed Constrained Power Control (DCPC) algorithm. Receivers are subject to non-negligible noise, and the DCPC attempts to bring each receiver's CIR (Carrier to Interference Ratio) above a given quality target. Two classes of distributed admission controls are considered. One is a Non-Interactive Admission Control (N-IAC), where an admission decision is instantaneously made based on the system state. The other is an Interactive Admission Control (IAC), under which the new mobile is permitted to interact with one or more potential channels before a decision is made. The algorithms are evaluated with respect to their execution time, and their decision errors. Two types of errors are examined. Type I error, where a new mobile is erroneously accepted and results an outage; and type II error, where a new mobile is erroneously rejected and results in blocking. The algorithms in the N-IAC class accept a new mobile, if and only if the uplink and the downlink interferences are below certain corresponding thresholds. These algorithms are subject to errors of type I and type II. In the IAC class, we derive a Soft and Safe (SAS) admission algorithm, which is type I and type II error free, and protects the CIRs of all active links at any moment of time. A Fast-SAS version which is only type I error free, is proposed for practical implementation, and evaluated in several case studies.
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| 5. |
- Andersin, Michael, et al.
(författare)
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Time Variant Power Control in Cellular Networks
- 1996
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Ingår i: Proceedings of the 1996 7th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC'96. - : IEEE. - 0780336925 ; , s. 193-197
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Konferensbidrag (refereegranskat)abstract
- We study the transmission power control in a cellular network where users' mobility results in a time varying gain matrix. A framework for evaluating the channel quality is specified, and an asymptotic representation of the link gain evolution in time is obtained. Then, a time variant distributed constrained power control (TVPC) which copes with user mobility is derived. The algorithm is compared to a classical distributed constrained power control (DCPC), as well as to a constant-received power control and constant-transmitted power. The comparison reveals that the classical DCPC exhibits an outage probability close to one, unless some counter-measures are taken. The TVPC algorithm however, copes well with users' mobility and provides a close to optimal scale up factor for the signal to interference ratio (SIR) target.
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| 6. |
- Andersin, Michael, et al.
(författare)
-
Transmission power cost of mobility in cellular networks
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We study the transmission power control in a cellular network where users mobility results in a time varying gain matrix. A framework for evaluating the channel quality is specified, and an asymptotic representation of the link gain evolution in time is obtained. Then, a variant of a standard Distributed Constrained Power Control (DCPC) which copes with user mobility is derived. These two power controls, as well as constantÂreceived power and constantÂtransmitted power controls are compared with respect to their outage probabilities in a ManhattanÂlike microcellular system. The comparison reveals that the classical DCPC algorithm has an outage probability close to one, unless some counterÂmeasures are taken. The time variant algorithm however, copes well with users mobility and provides a close to an optimal scale up factor for the Signal to Interference Ratio (SIR) target. Furthermore, the time variant algorithm provides a substantial improvement in spectrum utilization compared to the other algorithms above.
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| 7. |
- Kim, Seong-Lyun, et al.
(författare)
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Combined power control and transmission rate selection in cellular networks
- 1999
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Ingår i: Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th. - New York : IEEE. - 0780354354 ; , s. 1653-1657
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Konferensbidrag (refereegranskat)abstract
- Emerging multimedia services in cellular radio systems introduce a variable transmission rate, which raises the problem of controlling transmission rates in a spectrally efficient way. We formulate the problem into a combined power and rate control, for which we suggest two different algorithms. In the first one, we derive an algorithm applying the Lagrangian relaxation technique. In the other method, called selective power control we extend a fixed rate power control algorithm to solve the problem. Computational experiments carried out on a CDMA system indicate that the proposed algorithms give satisfying performance in terms of system throughput, outage probability and transmission power consumption.
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| 8. |
- Rosberg, Zvi
(författare)
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Fast Power Control in Cellular Networks Based on Short-Term Correlation of Rayleigh Fading
- 1997
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Konferensbidrag (refereegranskat)abstract
- The fast transmission power control problem in a cellular network is studied when the sig nal attenuation is subject to a fast timevarying multipath Rayleigh fading. An asymptotic representation of the link gain evolution in time is first derived, and then used for construct ing a Fast Time Variant distributed constrained Power Control (FTVPC). The proposed FTVPC power control successfully counteracts Rayleigh fading and demonstrates significant lower outage probabilities in comparison with the ConstantReceived Power control (CRP). It is shown that a potential improvement of 4=3 in the spectrum utilization can be obtained by FTVPC compared to CRP. A comparison with a network without Rayleigh fading under a previously studied Time Variant Power Control (TVPC), is also made. Not surprisingly, it turned out that Rayleigh fading is very difficult to counteract, and it adds a substantial amount of outages.
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| 9. |
- Rosberg, Zvi, et al.
(författare)
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Towards a framework for power control in cellular radio systems
- 1998
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Ingår i: Wireless networks. - : ACM/Kluwer Academic Publishers. - 1022-0038 .- 1572-8196. ; 4:3, s. 215-222
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Tidskriftsartikel (refereegranskat)abstract
- Efficiently sharing the spectrum resource is of paramount importance in wireless communication systems, in particular in Personal Communications where large numbers of wireless subscribers are to be served. Spectrum resource sharing involves protecting other users from excessive interference as well as making receivers more tolerant to this interference. Transmitter power control techniques fall into the first category. In this paper we describe the power control problem, discuss its major factors, objective criteria, measurable information and algorithm requirements. We attempt to put the problem in a general framework and propose an evolving knowledge dashbank to share, study and compare between algorithms.
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