Traffic-prediction-assisted dynamic power saving mechanism for IEEE 802.16e wireless MANs

How to reduce the energy consumption powered mainly by battery to prolong the standby time is one of the crucial issues for IEEE 802.16e wireless MANs.By predicting the next downlink inter-packet arrival time,three traffic-prediction-assisted power saving mechanisms based on P-PSCI,i.e.,PSCI-PFD,PSCI-ED and PSCI-LD,were proposed.In addition,the corresponding adjustment strategies for P-PSCI were also presented when there were uplink packets to be transmitted during sleep mode.Simulation results reveal that compared with the sleep mode algorithm recommended by IEEE 802.16e,the proposed mechanism P-PSCI can improve both energy efficiency and packet delay for IEEE 802.16e due to the consideration of the traffic characteristics and rate changes.Moreover,the results also demonstrate that PSCI-PFD (a=-2) significantly outperforms PSCI-ED,PSCI-LD,and the standard sleep mode in IEEE 802.16e is in terms of energy efficiency and packet delay.

Uplink Power Saving Potential of Cellular System with Fixed Relays

This paper presented a scheme of relayed cellular mobile telecommunication network,which only employs fixed digital relays and not more than two-hop relay routes.Power saving potential of the network is deeply studied under the assumption of not occupying additional frequency bands(i.e.relays share the same frequency bands as used by the base stations).Theoretical analysis and simulation results have both shown that,with the same radio coverage requirement,the necessary effective transmission powers in such a relayed network have greatly decreased compared to conventional cellular network.

PERFORMANCE ANALYSIS OF POWER SAVING CLASS OF TYPE Ⅲ IN IEEE 802.16E WITH USER INITIATED TRAFFIC

A novel method for analysing the performance of power saving class of Type III in IEEE 802.16e is proposed, which is applicable to design, maintenance and management for mobile wireless metropolitan area network. Considering the memoryless nature of user initiated packet arrival, a Geom/G/1 queue model with multiple vacations and setup period is built to capture the principle for the power saving class of Type III. By using an embedded Markov chain method and the boundary state variable theory, we obtain the queueing measures such as queueing length, waiting time and busy cycle in steady state. Correspondingly, we derive explicitly the performance measures for the power saving class of Type III in terms of handover ratio, energy saving ratio, and average packet response time. Based on numerical results, we develop a cost function to determine numerically the optimal length of sleep window and the minimal cost with different offered loads.

The research of power saving frequency conversion speed regulation experiment system

A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis and experiment results show the frequency difference method is a ideal power saving speed regulation method for the dou- ble inverter and motor system.The experiment system is simply structured,convenient to operate and provides a new way of character testing for frequency conversion speed regulation.

On the Development of China's Thermal Power in the 21st Century while Saving the Energy and Protecting the Environment

In light of China s Ninth Five-year Plan (1996-2000) for Electric Power Industry & the Long Term Targets by the Year 2010, the paper considers the strategy for developing China’s thermal power in the 21st century shall be the efficiency and cleaning technology of coal use. Especially important is the structure of power sources and configuration of technology process, and secondly the implementation of energy saving and environmental protection ideology in the various stages of thermal power construction and design work.

Three Kinds of Religion in Hungary Lessons of Three By-elections in Local Political Context

There has been a long tradition in the history of Hungarian intellectuals that dates as far back as the 1930s.It became well-known as the clash between the“populist”(nepies)and“urbanite”(urbanus)camps as two factions of the intellectual classes or status groups.However,the author’s historical investigations show that this clash originated during the first reform period of Hungarian history(1830-1848),when the“Centralists”under the leadership of József Eötvös confronted the“Municipalists”whose leading figure was Lajos Kossuth.The former group represented the Western Europe oriented faction,who heavily called into question the county system,while the members of the latter group warranted it as the bulwark of the Hungarian constitution.The conflict was renewed between the two world wars as“westernizing”urbanites opposed the“Magyar”-oriented populists.Also,after the regime change in the 1990s,this old clash posited itself politically first as the strife between the Hungarian Democratic Forum and the Free Democrats and later on it got the form of a European-oriented Leftist-Liberal wing facing the moderate Right.The desperate struggle between the two political wings appeared at the local level as well.The author describes a paradigmatic case of the overall contradiction in a case study.During the local elections in a Hungarian village the post-communist mayor was forced to run against a traditionally religious mayor,while the entire village population,including civil society,followed the desperate clash up to an unserviceable stage.At this point,a third mayor candidate stepped in competing with both former enemies and won the exceptional election.The new mayor transcended both the post-communist era and the oppositional mayor of traditional religious background,for as the great-grand child of a landowner in the period preceding the Second World War who was persecuted in the Communist era;this mayor restituted the continuity with the ancient landowner class.And at the same time,while jettisoning the old-fashioned religion,she exhibited a certain attachment to a new type,as it were,a postmodern religiosity.

Strategies Regarding Operating Voltage Levels in Distribution Networks

The power/energy losses reduction in distribution systems is an important issue during planning and operation, with important technical and economical implications. Thus, the energy losses minimization implies not only the technical improvement of the network, through its renewal with the introduction of the technological innovations in the equipment and circuit components as well as the optimal planning of the design and development of the network, but also requires the use of the methods and software tools to facilitate the operation process. The paper presents a strategy for power / energy saving which is replacement of the 6 kV voltage level with 20 kV voltage level. In this line, different urban distribution networks were analyzed using fuzzy techniques for load modeling.

Enhanced power saving mechanism for supporting multicast services in 802.11 wireless LANs

Traditional 802.11 power saving mechanism (PSM) treats multicast and broadcast traffic equally, and suffers sig-nificant performance degradation with multicast background traffic. This paper proposes an enhanced PSM that effectively dif-ferentiates multicast streams. It re-arranges the virtual bitmap of the traffic indication map (TIM) to carry traffic status for mul-ticast groups and introduces a concept of sequential transmission of multi-addressed data to facilitate differentiation among mul-ticast groups. Our analysis shows that the enhanced PSM can effectively save power in mixed traffic environments.

Dynamic Power Saving via Least-Square Self-Tuning Regulator in the Virtualized Computing Systems

In recent years,power saving problem has become more and more important in many fields and attracted a lot of research interests.In this paper,the authors consider the power saving problem in the virtualized computing system.Since there are multiple objectives in the system as well as many factors influencing the objectives,the problem is complex and hard.The authors will formulate the problem as an optimization problem of power consumption with a prior requirement on performance,which is taken as the response time in the paper.To solve the problem,the authors design the adaptive controller based on least-square self-tuning regulator to dynamically regulate the computing resource so as to track a given reasonable reference performance and then minimize the power consumption using the tracking result supplied by the controller at each time.Simulation is implemented based on the data collected from real machines and the time delay of turning on/off the machine is included in the process.The results show that this method based on adaptive control theory can save power consumption greatly with satisfying the performance requirement at the same time,thus it is suitable and effective to solve the problem.

Maximizing power saving with state transition overhead for multiple mobile subscriber stations in WiMAX

In the IEEE 802.16e/m standard, three power saving classes （PSCs） are defined to save the energy of a mobile sub- scriber station （MSS）. However, how to set the parameters of PSCs to maximize the power saving and guarantee the quality of service is not specified in the standard. Thus, many algorithms were proposed to set the PSCs in IEEE 802.16 networks. However, most of the proposed algorithms consider only the power saving for a single MSS. In the algorithms designed for multiple MSSs, the sleep state, which is set for activation of state transition overhead power, is not considered. The PSC setting for real-time connections in multiple MSSs with consideration of the state transition overhead is studied. The problem is non-deterministic polynomial time hard （NP-hard）, and a suboptimal algorithm for the problem is proposed. Simulation results demonstrate that the energy saving of the proposed algorithm is higher than that of state-of-the-art algorithms and approaches the optimum limit.