| 1. |
- Rasti, Mehdi, et al.
(författare)
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A Distributed and Efficient Power Control Algorithm for Wireless Networks
- 2008
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Ingår i: 2008 IEEE 19TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS. - : IEEE. - 9781424426430 ; , s. 1494-1499
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Konferensbidrag (refereegranskat)abstract
- In the well-known distributed target-SIR tracking power control algorithm, when the target-SIR requirements are not reachable for all users, all non-supported users (those who do not reach their target SIRs) transmit at their maximum power. Such users inefficiently consume their energies, and introduce unnecessary interference to others, which in turn unnecessarily increases the number of non-supported users. To deal with this, the smallest number of users should be removed due to infeasibility of the system (gradual removal problem). We present a new distributed constrained power control (DCPC) algorithm to address the gradual removal problem. The basic idea is that any transmitting user whose required transmit power for reaching its target-SIR exceeds its maximum power is temporarily removed. Each temporarily removed user resumes its transmission if its required transmit power for reaching its target-SIR goes below a given threshold (lower than its maximum power). This threshold is determined by each removed user in a distributed manner using only local information. We will show that our proposed algorithm has at least one-fixed point (i.e., its convergence can be guaranteed), and at the equilibrium where the algorithm converges, all transmitting users (the users whose transmit powers are greater than zero) reach their target SIRs consuming the minimum aggregate transmit power. Furthermore, in contrast to the existing DCPC algorithms, no user is unnecessarily removed in our proposed scheme, i.e., it is efficient. Our simulation results confirm our analytic developments and show that our scheme outperforms the existing DCPCs in addressing the gradual removal problem, in terms of convergence, outage probability and power consumption.
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| 2. |
- Rasti, Mehdi, et al.
(författare)
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A Distributed Dynamic Target-SIR-Tracking Power Control Algorithm for Wireless Cellular Networks
- 2010
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Ingår i: IEEE Transactions on Vehicular Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9545 .- 1939-9359. ; 59:2, s. 906-916
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Tidskriftsartikel (refereegranskat)abstract
- The well-known fixed-target-signal-to-interference-ratio (SIR)-tracking power control (TPC) algorithm provides all users with their given feasible fixed target SIRs but cannot improve the system throughput, even if additional resources are available. The opportunistic power control (OPC) algorithm significantly improves the system throughput but cannot guarantee the minimum acceptable SIR for all users (unfairness). To optimize the system throughput subject to a given lower bound for the users' SIRs, we present a distributed dynamic target-SIR tracking power control algorithm (DTPC) for wireless cellular networks by using TPC and OPC in a selective manner. In the proposed DTPC, when the effective interference (the ratio of the received interference to the path gain) is less than a given threshold for a given user, that user opportunistically sets its target SIR (which is a decreasing function of the effective interference) to a value higher than its minimum acceptable target SIR; otherwise, it keeps its target SIR fixed at its minimum acceptable level. We show that the proposed algorithm converges to a unique fixed point starting from any initial transmit power level in both synchronous and asynchronous power-updating cases. We also show that our proposed algorithm not only guarantees the (feasible) minimum acceptable target SIRs for all users (in contrast to the OPC) but also significantly improves the system throughput, compared with the TPC. Furthermore, we demonstrate that DTPC, along with TPC and OPC, can be utilized to apply different priorities of transmission and service requirements among users. Finally, when users are selfish, we provide a game-theoretic analysis of our DTPC algorithm via a noncooperative power control game with a new pricing function.
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| 3. |
- Rasti, Mehdi, et al.
(författare)
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Constrained Opportunistic Power Control in Wireless Networks
- 2008
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Ingår i: 2008 IEEE 19TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS. - : IEEE. - 9781424426430 ; , s. 2095-2098
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Konferensbidrag (refereegranskat)abstract
- In the opportunistic power control algorithm (OPC), designed in each user tries to keep the product of its transmit power and its experienced effective interference to a constant, called the target signal-interference product (SIP). This increases the transmit power when the channel is good and reduces it when the channel is poor (opportunism). It has been shown that the OPC always converges to a fixed point irrespective of whether the power is constrained (where there is no upper bound on transmit power) or unconstrained (where an upper bound on transmit power is taken into account). It has also been shown via simulation that the throughput achieved by the unconstrained OPC is significant (as compared to other existing distributed schemes), and is an increasing function of the target-SIP set by users, in the sense that a higher target-SIP results in a higher throughput. In this paper, we show that in contrast to the unconstrained OPC, when the constrained OPC is applied, not only the throughput is not necessarily increased as the target-SIPs increase, but it may even decrease if some users set their target-SIPs at high values. Furthermore, we propose a heuristic solution to determine the target-SIPs by users in a distributed manner. Our simulation results show that the throughput achieved by our distributed setting of the target-SIPs very closely approaches the maximum achievable throughput by the constrained OPC, and is very close to the global optimum value.
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| 4. |
- Rasti, Mehdi, et al.
(författare)
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Improved Distributed Power Control Algorithms with Gradual Removal in Wireless Networks
- 2008
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Ingår i: 2008 EUROPEAN WIRELESS CONFERENCE. - : IEEE. - 9783800731022 ; , s. 165-169
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Konferensbidrag (refereegranskat)abstract
- In the well-known distributed target-SIR tracking power control algorithm, when the target-SIR requirements are not reachable for all users (due to heavy load and/or deep fading), some users transmit at maximum power without reaching their target SIR. Such users inefficiently consume their energies, and introduce unnecessary interference to others, which in turn results in more unnecessary non-supported users. To alleviate the situation, a minimal number of users have to be removed (the gradual removal problem). In this paper, we propose improvements to two algorithms that were shown to be the best of the existing distributed power control algorithms for the gradual removal problem, and demonstrate that the improved algorithms have smaller outage probabilities. In addition, we show that the convergence rate for one of our improved algorithms is substantially better than those of both original algorithms.
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| 5. |
- Rasti, Mehdi, et al.
(författare)
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Pareto and Energy-Efficient Distributed Power Control with Feasibility Check in Wireless Networks
- 2011
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Ingår i: IEEE Transactions on Information Theory. - : IEEE. - 0018-9448 .- 1557-9654. ; 57:1, s. 245-255
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Tidskriftsartikel (refereegranskat)abstract
- We formally define the gradual removal problem in wireless networks, where the smallest number of users should be removed due to infeasibility of the target-SIR requirements for all users, and present a distributed power-control algorithm with temporary removal and feasibility check (DFC) to address it. The basic idea is that any transmitting user whose required transmit power for reaching its target-SIR exceeds its maximum power is temporarily removed, but resumes its transmission if its required transmit power goes below a given threshold obtained in a distributed manner. This enables users to check the feasibility of system in a distributed manner. The existence of at least one fixed-point in DFC is guaranteed, and at each equilibrium, all transmitting users reach their target-SIRs consuming the minimum aggregate transmit power. Furthermore, in contrast to the existing algorithms, no user is unnecessarily removed by DFC, i.e., DFC is Pareto and energy-efficient. We also show that when target-SIRs are the same for all users, DFC minimizes the outage probability. Simulation results confirm our analytical developments and show that DFC significantly outperforms the existing schemes in addressing the gradual removal problem in terms of convergence, outage probability, and power consumption.
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| 6. |
- Sulaiman, Naji, et al.
(författare)
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Cultural vs. state borders : plant foraging by Hawraman and Mukriyan kurds in western Iran
- 2024
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Ingår i: PLANTS. - : MDPI. - 2223-7747. ; 13:7
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Tidskriftsartikel (refereegranskat)abstract
- Plant foraging is a millennia-old activity still practiced by many people in the Middle East, particularly in the Fertile Crescent region, where several socioeconomic, ecological, and cultural factors shape this practice. This study seeks to understand the drivers of plant foraging in this complex region characterized by highly diverse linguistic, religious, and cultural groups. Our study aims to document the wild plants used by Kurds in Western Iran, identify similarities and differences among Hawraman and Mukriyan Kurdish groups in Iran, and compare our findings with a previous study on the Hawramani in Iraq. Forty-three semi-structured in-depth interviews were conducted in Kurdish villages of Western Iran. The results revealed the use of 44 wild food plant taxa, their preparation, and culinary uses. Among the reported taxa, 28 plant taxa were used by Mukriyani, and 33 by Hawramani. The study revealed a significant difference between the Hawraman and Mukriyan regions in Iran, whereas there is a high similarity between Hawramani Kurds in Iran and Iraq. We found that the invisible cultural border carries more weight than political divisions, and this calls for a paradigm shift in how we perceive and map the distribution of ethnobotanical knowledge.
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